Periodontal surgery NYC: Socket Grafting in the Posterior Maxilla Reduces the Need for Sinus Augmentation

Periodontal Surgery NYC: Socket Grafting and Sinus Augmentation

In the aid of periodontal surgery NYC, this research endeavored to explore whether socket grafting – the filling of a tooth socket with soft tissue, demineralized and freeze-dried bone particles and irradiated bone – reduces the need for sinus augmentation for the purpose of dental implants. Sinus augmentation is a surgical procedure whereby the soft tissue and sinus membrane are carefully peeled away from the upper jaw bone at the back of the mouth to reveal the maxilla. Bone grafting periodontal surgery is then performed on the area to provide support for dental implants. Patients can take anywhere between three to six months to properly heal.

The reason for this periodontal surgery in NYC is that patients that do not present sufficient bone density in the posterior of the maxilla generally need to undergo sinus augmentation before they will be considered viable candidates for dental implants. Without robust enough bone tissue to support the titanium screw upon which the artificial tooth crown is affixed, the implant will become easily dislodged and the periodontal surgery deemed a failure. Dental implants are one of the best possible solutions to single/multiple missing teeth and so, in the event of a displaced tooth, periodontal surgery becomes unavoidable should the patient wish to restore aesthetics and functionality to their mouth.

Periodontal Surgery NYC: Research Methodology

This periodontal surgery NYC study compared the three variables in relation to augmented and non-augmented alveolar sockets:

• Dimensional alterations,

• The need for sinus floor elevation, and

• The histologic wound healing (‘histology’ being the organization and microscopic structure of soft tissue).


Sixteen human extraction sockets were either grafted or left untreated and the following evaluations made:

• Alveolar ridge alterations were evaluated at baseline (the time of the periodontal surgery NYC), three and six months post-extraction;

• Histologic analyses were conducted at three, six, and nine months.

• Implant placement with or without sinus floor augmentation was decided at 6 months.

Periodontal Surgery NYC: Research Findings and Conclusions

The most significant finding of this research endeavor was that three of eight patients (37.5%) in the control group underwent sinus floor augmentation compared to one of six (16.7%) in the experimental group. What this essentially means, is that the alveolar ridge augmentation procedure presented here increases the possibility of periodontal surgery NYC success for dental implants without the need for a sinus augmentation procedure.

Smokeless Tobacco Use and Periodontal Disease NYC in a Rural Male Population

A study investigating smokeless tobacco use found that people who chew tobacco or retain it in their mouths display greater gingival recession prevalence and extent.

Periodontal Disease NYC: Investigating the Effects of Smokeless Tobacco Use on Oral Health

Despite the reported effects of smokeless tobacco (ST) on the periodontium (the soft tissues surrounding and supporting the teeth), the incidence of periodontal disease NYC, and the high prevalence of ST use in rural populations and in men, studies on this specific topic are limited. With such a gap in the literature on this subject, it is the purpose of this cross-sectional investigation to evaluate the periodontal health status and incidence of periodontal disease NYC in male ST users from a rural population. However, before the methodology is explored, the term ‘smokeless tobacco’ needs elucidation. Smokeless tobacco, in the context of the United States and this research, generally refers to tobacco leaves that are placed between the lower or upper lip and the gums, or alternatively chewed.

Investigating Health and Periodontal Disease NYC and the Connection with Smokeless Tobacco Consumption: Methodology

The study sample of this periodontal disease NYC study consisted of 73 adult male residents of two rural Appalachian Ohio counties that were daily ST users and presented unilateral mandibular oral ST keratosis lesions. Keratosis legions generally take the form of a growth in the upper layer of soft tissue or gum. Subjects completed a questionnaire and received an oral examination in which the following variables were recorded:

• Teeth present (the number of missing teeth, if any)
• ST keratosis lesion,
• Plaque and gingival index (the severity of accumulation)
• Probing depth (PD) (to what extent the gingival can be separated from the tooth)
• Recession depth (RD) (to what extent the gum has receded from the tooth, exposing the root), and
• Attachment level

A Statistical analysis was conducted, which compared ST-site mandibular teeth (teeth adjacent to the subject's unilateral ST keratosis lesion) to NST-site teeth (contralateral corresponding teeth).

Investigation of Periodontal Disease NYC in ST Users: Results

Of the 73 ST users recruited for this analysis, the following results were obtained:

• Recession prevalence is much greater in ST-site quadrants (36%) compared to NST-site quadrants (18%).
• Twice as many teeth had recession on ST-site (approximately 20%) than NST-site (approximately 10%).
• Average buccal (cheek-side) RD on ST-site teeth did not differ from that on the NST-site teeth. Although average buccal attachment loss is greater on ST-site teeth, the mean difference is <0.5 mm.
• When stratified by years of ST use, subjects using ST for 10 to 18 years exhibit the most differences between ST and NST sites, whereas subjects using ST for <10 years show no differences.

From this analysis, the authors conclude that the results indicate that greater gingival recession prevalence and extent are associated with ST placement site in rural male ST users. The implications in terms of periodontal disease NYC remain to be investigated, but from these initial findings, it can be inferred that ST users are at a greater risk due to gum recession and tooth root exposure.

Osseointegration of Dental Implants NYC in Patients Undergoing Bisphosphonate Treatment

Osteonecrosis of the jaw is a severe disease that poses a higher risk to patients receiving bisphosphonate therapy. This review endeavors to determine the link between dental implant patients receiving BP therapy and the risk of ONJ

Dental Implants NYC and the Risk of Osteonecrosis Induced by Bisphosphonate Treatment: Study Motivation

Bisphosphonates (BPs) are an important group of drugs used for the treatment of metabolic and oncologic (cancer-related) pathologies involving the skeletal system. However, osteonecrosis of the jaw (ONJ) is a complication observed in patients using oral or intravenous (IV) BPs. Osteonecrosis, from its Latin origins, can literally be translated to “Bone death” and occurs when the bone loses its blood supply, resulting in structural collapse and incredible pain and arthritis. In the case of ONJ, the bone of the mandible and/or maxilla can be affected by this severe diseasing causing the appearance of lesions in the gingiva (gums) that do not heal. Furthermore, acute infection, inflammation and pain set in as the bone, which is exposed by the lesions, deteriorates.

Investigating the Link Between Dental Implants NYC and the Risk of Osteonecrosis in Patients Receiving BP Therapy

As a result of the observations connecting patients undergoing BP therapy and ONJ, those who are expected to receive dental implants NYC should be informed of the possible risks. The purpose of this particular literature review is to assess the osseointegration of dental implants NYC in patients undergoing BP therapy. Osseointegration refers to the biological fusing of the titanium screws of the dental implants NYC to the bone of the jaw. The MEDLINE-PubMed databases of The National Library of Medicine, National Institutes of Health, Bethesda, Maryland, were searched for articles addressing the focused question: Can dental implants NYC osseointegrate and remain functionally stable in patients undergoing oral and IV BP therapy? In other words, could dental implants NYC be successful in patients receiving BP therapy intravenously? To begin finding the answer to this core research issue, databases were searched from 1995 up to and including February 2010 using the following terms in different combinations:

• Bisphosphonate,
• Dental implant,
• Immediate-loading,
• Implant survival rate,
• Intravenous,
• Oral,
• Osseointegration, and
• Osteonecrosis.

Dental Implants NYC, BP Therapy and ONJ: Review Results

The initial search of the above-mentioned keywords yielded 89 articles. Scrutiny of the titles and abstracts reduced the number of articles to 12 (seven case reports and five retrospective studies). In 10 studies, the patients were using oral BPs, and in two studies, patients were using IV BPs. The results of the review were as follows:

• Six case reports showed that the placement of dental implants NYC in patients using BPs could yield a successful osseointegration and post-operative function.
• Four retrospective studies demonstrated that BPs did not have a negative influence on implant success.
• Two studies showed a negative impact of BPs on implant success.
Of the 12 case studies performed, only two demonstrated that BP had a negative impact upon the success of dental implants NYC. In conclusion, the authors remark that dental implants NYC can biologically fuse with the jaw bone (osseointegrate) and remain functionally stable in patients using BPs.

Gum disease NYC risk factors: what you need to know for healthy gums

How old are you?
The chance of developing gum or periodontal disease increases considerably as you get older. Studies indicate that older people have the highest rates of periodontal disease and need to do more to maintain good oral health. However, as you read ahead, if you are a young patient (under 40 years old) and have any of the risk factors, you may have more serious dental problems that will worsen with time and require professional treatment in a timely way.

Are you female or male?
Studies suggest there are genetic differences between men and women that affect the risk of developing gum disease. While women tend to take better care of their oral health than men do, women's oral health is not markedly better than men's. This is because hormonal fluctuations throughout a woman's life can affect many tissues, including gum tissue.

Do your gums ever bleed?
Bleeding gums can be one of the signs of gum disease. Think of gum tissue as the skin on your hand. If your hands bled every time you washed them, you would know something was wrong. However if you are a smoker, your gums may not bleed, and therefore, “hide” the severity of your condition.

Are your teeth loose?
Periodontal (gum) disease is a serious inflammatory disease that is caused by a bacterial infection, and leads to destruction of the attachment fibers and supporting bone that hold your teeth in your mouth. When neglected, teeth can become loose and fall out. Loose teeth, even though nothing hurts, are a sign of periodontal or gum disease.

Have your gums receded, or do your teeth look longer?
One of the warning signs of gum disease includes gums that are receding or pulling away from the teeth, causing the teeth to look longer than before.

Do you smoke or use tobacco products?
Studies have shown that tobacco use may be one of the most significant risk factors in the development and progression of periodontal disease. Smokers are much more likely than non-smokers to have calculus form on their teeth, have deeper pockets between the teeth and gums, and lose more of the bone and tissue that support the teeth. And yet, smokers may have no signs or symptoms of gum disease because the smoke masks the underlying problems.

Have you seen a dentist in the last two years?
Daily brushing and flossing will help remove bacterial plaque and even keep calculus formation to a minimum, but it won't prevent gum disease or calculus from forming. A professional dental cleaning at least twice a year is necessary to remove calculus from places your toothbrush and floss may have missed. If you are prone to gum disease, more frequent professional cleanings will help maintain your periodontal condition.

How often do you floss?
Studies demonstrate that including flossing as part of your oral care routine can actually help reduce the amount of gum disease-causing bacteria found in the mouth, therefore contributing to healthy teeth and gums. Brushing, alone, will not keep your mouth and gums healthy.

Do you currently have any of the following health conditions?
i.e. Heart disease, osteoporosis, osteopenia, high stress, or diabetes
Ongoing research suggests that periodontal disease may be linked to these conditions. The bacteria associated with periodontal disease can travel into the blood stream and pose a threat to other parts of the body. Healthy gums may lead to a healthier body. High stress levels release hormones into the bloodstream that act as “food” for the bacteria that cause gum disease. When you are under stress, you are “feeding” the problem.

Have you ever been told that you have gum problems, gum infection or gum inflammation?
Over the past decade, research has focused on the role chronic inflammation may play in various diseases, including periodontal or gum, disease. Data suggests that having a history of periodontal disease makes you six-times more likely to have future periodontal problems. Periodontal disease is often silent, meaning symptoms may not appear until an advanced stage of the disease.

Have you had any adult teeth extracted due to gum disease?
Most gum problems are generalized among a number or teeth, and are not isolated to a single tooth. For this reason, if you have lost a tooth to gum disease, the likelihood exists that you have a gum condition that needs to be treated, even if nothing hurts or you are unaware of any symptoms.

Have any of your family members had gum disease?
Research suggests that the bacteria that cause periodontal disease can pass through saliva, and remain on your toothbrush. For this reason, it is unwise to share toothbrushes. Individuals with advanced gum problems should be aware that they can transmit this to another family member through their saliva. Also, research proves that up to 30% of the population may be genetically susceptible to gum disease. Despite aggressive oral care habits, these people may be six times more likely to develop periodontal disease.

Gum disease, also known as periodontal disease, is a silent disease. It is chronic, much in the way diabetes, lupus, rheumatoid arthritis and other diseases are, and as such, must be treated, contained, and monitored by a dental professional. Except in extreme instances, early intervention will help an individual save their teeth in comfort and good function when suffering gum disease in NYC.

Dental 3D Cone Beam CT Imaging: Part V Dental Incidentalomas (Pre-surgical analysis for the insertion of dental implants)

Using 3D CT imaging for diagnostic purposes in medicine has uncovered incidental tumors that had no clinical symptoms in various tissues when there was no previous suspicion that they were present. These incidental tumors have been dubbed “incidentalomas,” and been discovered in adrenal glands, kidneys, pituitary glands, thyroid glands, liver, lungs, and the parathyroid glands (1-18). It has been estimated that approximately 7% of all patients over 60 may harbor a benign growth (often of the adrenal gland) and with the increase of “whole-body CT scanning” as part of health screening programs, the chance of finding incidentalomas is expected to increase to 37% (19). These chance findings will, in many cases, require further investigation.

A search of the dental literature did not reveal any studies that dealt with incidental findings on 3D CT studies taken on cone beam scanners. Nor has the term “incidentaloma” been applied to dentistry.

In this 3D CT cone beam study, 500 consecutive patients sent to one of nine i-dontics, llc radiologic labs were analyzed for a variety of normal and abnormal findings. Part I studied why patients were referred for CT studies including their age, gender, and format of the requested study. Part II studied the lingual artery and its insertion into the mandible. Part III studied the frequency and location of bifid canals. Part IV studied the length and location of the anterior canal extending anterior to the mental foramen. And in this study, Part V, the frequency and type of incidental findings on patients ostensibly sent to a dental CT radiological lab for 3D scans for dental implants were analyzed.

Methods and Materials

Data from five hundred (500) consecutive patients sent for 3D CT cone beam studies to one of 9 centers located in 3 states were evaluated. Scans were taken on either i-CAT (8 centers) or on a NewTom 3G scanner, and uploaded to a central data center. All studies were converted to SimPlant™ (Materialise, Glen Burnie, MD.). When not specified, the data was converted to SimPlant™ version 10.

In this part of the 3D study, the following parameters were recorded for each patient: if the maxillary sinuses were free of pathology or to what extent pathology was present. In addition, the following were noted: the presence of radiolucencies at the apices of teeth; were the teeth noted with radiolucencies vital or non-vital; impacted teeth and supernumeraries, retained roots, cysts, the presence of dental implants, and the radiopaque presence of bone graft material. Other incidental findings noted on the 3D Ct images included the notation of severe periodontal bone loss, fourth molars, condensing osteitis, surgical tacks, etc.
Results

Five hundred (500) patients were included in this study. Of the five hundred, two hundred and four (204) were referred exclusively for maxillary studies and an additional seventy-nine (79) (refer to Part I of this study), were referred for both maxillary and mandibular studies. A total of two hundred and eighty-three maxillas studied (Figure 1) for observations about the maxillary sinus. The CT scans for all 500 patients were analyzed for incidental findings.

Figure 1. Of the 500 patients in this study, 279 had maxillary scans evaluated.

Ninety-one (91) patients had both maxillary sinuses free of pathology while ninety (90) patients had pathology in both sinuses at the same time, as noted on the CT images. Pathology was defined as less than 1mm of a mucosal thickening measured at any part of the sinus visible in the CT scan. When pathology was present (1mm or greater of mucosal thickening), one maxillary sinus remained clear or free of pathology in 78 patients: 41 in the right and 37 in the left.

When present, the amount of mucosal thickening was measured in each sinus. The mucosal thickening in the right sinus averaged 5.3mm and it measured 5.6mm in the left sinus.

In addition, 26 patients had polyps in the right maxillary sinus and 22 patients had polyps in the left maxillary sinus. Six maxillary sinuses were totally blocked both right and left (Figure 2). Polyps were observed in some patients with mucous thickenings, so that the total number of observations is greater than the 283 maxillary sinuses studied.

Figure 2. 91 of the 283 maxillary scans had no pathology in both the right and left maxillary sinuses. 90 patients had pathology noted in both maxillary sinuses and 78 patients had pathology in only one of the maxillary sinuses. 48 patients had a polyp noted in either the right or left maxillary sinus, or both.

Reasons for dental 3D CT scans. The predominant reason for referral for dental CT scans was for pre-surgical analysis for the insertion of dental implants. Four hundred and fifty-one patients (451) were referred for implants; 20 for impacted teeth; 10 for pathology; 7 for endodontics; 4 for orthodontics; 1 for TMJ disorder; 7 unknown (Figure 3).

Figure 3. A = 451 Patients referred for CTs for implants; B = 20 patients for impacted teeth; C = 10 patients for pathology; D = 7 patients for endodontics; E = 4 patients for orthodontics; F = 1patient for TMJ; G = 7 patients unknown reason for referral for CT.

Incidental findings. While 451 patients (out of 500) were referred for a 3D dental CT scan for the express purpose of pre-surgical planning for implant insertion, many incidental findings were noted. The most common incidental findings (Figure 4) were periapical radiolucencies (229), socket preservation bone grafts (46), impacted teeth (27), retained root tips (24), sinus grafts (12), cysts (8), and supernumerary teeth (2). In addition, 70 dental implants were previously inserted in these patients. Other observations (142) included cementomas, surgical screws and tacks, assorted opacities within the body of either arch, 4th molars, blunted apices (due to orthodontics), blocked ethmoid sinus, condensing osteitis, and advanced periodontal disease nearly to the apices of many teeth.

Figure 4 The most common incidental findings were: 229 periapical radiolucencies; 46 socket preservation bone grafts; 27 impacted teeth; 24 retained root tips; 12 sinus grafts; 8 cysts; 2 supernumerary teeth.

Discussion

In the medical literature, the term “incidentaloma” refers to the discovery of a previously unsuspected tumor when taking a CT scan for another purpose. This term has not entered the dental literature. It is suggested that a dental “incidentaloma” be defined as the discovery of any unsuspected pathology, anomaly, dental structure (such as a retained root tip, impacted tooth, or supernumerary), or deviation from normal anatomy on a CT scan. The implications of these findings challenge the dentist and dental surgeon to be familiar with both normal and abnormal structures as they present on 3D cone scan imaging, which can appear different and unfamiliar compared to traditional 2D X-ray images such as periapical dental films or panoramic X-rays. Furthermore, it is incumbent for the dentist to interpret the entire field of view of each CT scan, and not just the area of concern, such as a dental implant site or a recalcitrant endodontic lesion or where the IAN is relative to an impacted third molar.

The most frequent incidental finding in this study was periapical radiolucencies. Many authors have acknowledged that 3D cone beam CT scans are extremely accurate and can be relied on for making a diagnosis of periapical pathology (20-23). For purposes of this study, periapical pathology was defined as a lesion expanding larger than 1mm from the apex. This was chosen to remove doubt that a pseudoperiapical lesion was not a thickened PDL due to trauma from occlusion. There was no attempt to obtain the previous history of teeth with root canal therapy to compare the size of the present lesion with past X-rays. No determination was made if a periapical lesion noted in this study was old, non-expanding, or a healing granuloma.

This 3D CT study noted trends in therapy. For instance, 46 extraction sockets were treated with graft material and the dental surgeon was interested in a 3D analysis of the healing lesion. Likewise, patients who had previously had maxillary sinus grafts (12) received 3D CT scans to determine the success of these surgeries.

Twenty-seven (27) teeth other than the ones patients who were originally referred for CT scans, were impacted, and two supernumeraries were noted. These “incidental” findings were sent in a report to each dentist for their review, final approval, and action when they deemed it necessary.

It is apparent that with the advent of dental cone beam scanners, more dentists will take advantage of 3D technology for better surgical planning, improved diagnostic preparation for orthodontic patients, all of which contribute to lower risk and more successful outcomes for the patients. While dentists embrace 3D technology, they need to become familiar with normal and abnormal landmarks. In addition, they need to be prepared to identify incidental findings and inform their patients as to the existence of these findings and their clinical relevance.

Conclusion

This study noted many incidental findings on 3D dental CT scans and suggests that these findings be described as “incidentalomas.” These unexpected findings include sinus pathology, cysts, impacted teeth, supernumeraries, periapical radiolucencies, and more. It is suggested that dentists become more familiar with normal and abnormal landmarks in the increased field of view of CT studies, especially when these 3D images are taking in preparation for dental implant treatment planning.
Acknowledgements: Support for this study was generously given by Nobel Biocare AB Gothenberg, Sweden (Grant 2006-492) and Imaging Sciences Inc., Hatfield, PA.

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Dental 3D Cone Beam CT Imaging: Part IV Anterior Extension of IAN from Mental Foramen (Pre-surgical analysis for the insertion of dental implants)

Dental 3D CT cone beam imaging has many purposes including accurate dental implant placement and the identification of key anatomic structures. While there is an extensive literature analyzing the many aspects of the anterior loop extending from the mental foramen which compare the frequency and accuracy of this landmark from radiographs, cadaver dissection, and CT imaging (1-5), no study has measured the anterior extension of the inferior alveolar nerve (IAN) relative to distance from the edentulous crest, apices of teeth, and more. In Greenstein and Tarnow’s exhaustive literature review of the anatomy and clinical ramifications of the mental foramen, they conclude that since there is little correlation between viewing the anterior loop on radiographic and its actual clinical location, they recommend “leaving a 2mm zone of safety between an implant and the coronal aspect of the nerve” (6). In their literature review, it is suggested to use CT scans to help identify the anterior loop. They recommend that particular attention to variations in the anatomy in the area of the mental foramen be considered in addition to both functional and esthetic demands in order to avoid complications to the neurovasculature.

This study, using dental cone beam 3D CT scanners, evaluated various normal and abnormal landmarks noted in 500 consecutive patients referred to dental CT radiological labs for a variety of reasons, but most of which were for the insertion of dental implants. Part I of this study analyzed the demographics and reasons for the patients being referred for CT scans; Part II studied anatomic considerations of the insertion of the lingual artery into the mandible; Part III analyzed the frequency and location of bifid canals. In this study, Part IV, the anterior extension of the inferior alveolar nerve is studied on 3D CT images, and its clinical ramifications are discussed.

Methods

Data from five hundred (500) consecutive patients sent to i-dontics center from 9 centers located in 3 states for 3D dental CT studies, were evaluated. Scans were taken on either i-CAT (8 centers) or NewTom 3G scanners and uploaded to a central data center. All studies were converted to SimPlant™ (Materialise, Glen Burnie, MD). When not specified, the data was converted to SimPlant™ version 10.

Two hundred and Ninety-six (296) mandibles were studied on 3D CT studies using the measuring tool on the SimPlant Master™ Program. The following were measured: the length of the anterior extension of the IAN from the most mesial aspect of the mental foramen as identified in a 1mm slice; the distance of the anterior extension from the edentulous alveolar crest; the distance of the anterior extension from the apices of teeth; how many anterior extensions of the IAN were connected from right to left at the midline; and how many mental foramina were located on the alveolar crest.

Results

Almost 97% of the 296 mandibles analyzed in this study had at least one measurable extension of the IAN anterior to the most mesial aspect of the mental foramen (Figure 1), as noted on cone beam dental CT studies.


Figure 1. Nearly 97% of all mandibles had an anterior extension; nine patients did not have a measureable anterior extension of the IAN as seen on a 3D cone beam study.

Fourteen patients (4.73%) did not have an extension on the right side; eleven patients (3.72%) did not have an extension on the left side.

The average length of the anterior extension extending from the mesial rim of the mental foramen is 12.0 mm on the right and 11.8 mm on the left (Figure 2).


Figure 2. The average length of the anterior extension from the mental foramen bilaterally is nearly 12.0 mm.

The distance from the superior most portion of the anterior extension of the IAN to the edentulous crest was measured on images from a 3D dental cone beam scanner. In most instances, the bone loss was level and the radiographic extension was parallel to the crest enabling a single measurement either on the right or left side, or both. The average depth of the extension under an edentulous right crest was 10.5mm and 11.0mm under the left side (Figure 3-3A).


Figure 3. Average measurement to edentulous alveolar crest was 10.5mm on right anterior mandible. (Stereolithographic model courtesy of BioMedical Modeling, Boston, MA).


Figure 3A. Average measurement to edentulous alveolar crest was 11.0mm on left anterior mandible. (Stereolithographic model courtesy of BioMedical Modeling, Boston, MA).

The distance from the anterior extension of the canal to the apex of a tooth measured from 3D CT images when the dentition was present was measured from the most anterior extent of the canal vertically to the apex of the adjacent tooth. The preponderance of teeth measured in this situation were situated under the apices of the lateral incisors. In all instances, the measurement was vertical from the tooth apex to the top of the extended canal. Both right and left measurements, seen on 3D CT images, were identical: 17.0mm from the anterior extent of the canal to the nearest root apex.

A continuous loop, defined as an extension of the canal that emanates from both the right and left mental foramina and is seen to connect in the midline was viewed on 77 patients (26.01%). In Figure 4, the anterior extensions of the canal can be seen in different coronal (panoramic) slices of the same individual.


Figure 4. Coronal slices in the same patient demonstrate examples of a continuous canal as observed and noted in this study.

Figures 5 and 5A demonstrate a continuous anterior extension that joins in the midline. Various branches emanate from the canal displaying that may be viewed in CT cone beam images but not 2D dental X-rays.


Figure 5. Example of a continuous anterior extension of the canal with multiple branches extending from the main trunk.


Figure 5A. Some of the many branches extending from the main canal and the anterior extension are highlighted.

Eight (8) edentulous patients (2.70%) had the mental foramina exit on top of the alveolar crest.

Discussion

The anterior loop of the mental nerve is commonly described as that part of the neurovascular bundle that transverses anterior and inferior to the mental foramen only to loop back to exit the mental foramen (8-11). While it is often difficult to follow its extend on 2D dental X-rays, it is easier to view these anterior loops on 3D CT images.

When mandibles were dissected, the anterior loop was detected in 60% of 37 cadaver mandibles (12). The length of the loop in this 3D CT study (12) ranged from 0.5 to 5mm. In another study, Neiva et al (13) probed the anterior loop in 22 cadavers, noting that it was present in 88% of the patients and that its mean length was 4.13mm ranging from 1.0 – 11.0mm.

Studies have found CT scans more accurate than traditional 2D dental imaging (14-18) and they should be considered for locating inferior alveolar canals or mental foramina not easily viewed on traditional 2D dental images (periapical films or panoramic images) when considering implant placement, removal of impacted teeth, or treating pathologic lesions.

This 3D Ct cone beam study confirmed, along with other studies, that the alveolar ridge resorbs approximately 6.0-6.5mm when teeth are extracted, which is the average distance noted between the ridge to the anterior extension when compared to root apices to the anterior extension of the canal (1-2).

Using CT scans, Rothman found that the length of the anterior loop could be as long as 10.0mm (19) compared to this study, where it was found the average length for the anterior continuation of the nerve 11.8mm on the left side and 12.0 mm on the right. What is apparent in this study is that the average length of the anterior extension of the canal is greater than in other reported studies. It is unclear if this finding is a function of interpretation or is a result of the accuracy of dental cone beam scanners. What is clear is that these radiographic canals exist, but their clinical importance is a matter of speculation and requires further investigation.

For example, are these radiographic canals filled with nerve and vascular tissues or are they empty? Do they innervate gingival tissues? The answers to these questions are clinically relevant for a host of reasons. When these anterior extensions of the canal are identified on 3D CT images, should they be avoided during dental implant placement? Should increased bleeding be anticipated? Should the patient be informed that there is a chance there will be an altered sensation to the gingiva and adjacent tissues if these canals are penetrated during dental implant surgery? Further investigation will help determine the answers to these questions.

Conclusions

In this 3D dental cone beam CT study, 296 mandibles were studied on dental cone beam scanners. The anterior extension of the IAN was measured relative to length and distance from edentulous ridges or apices of teeth. The clinical ramifications of this anatomic entity were discussed, including the value of 3D imaging when inserting dental implants.

Acknowledgements

Support for this study was generously given by Nobel Biocare AB Gothenberg, Sweden (Grant 2006-492) and Imaging Sciences Inc., Hatfield, PA.


References

1. Gershenson A, Nathan H, Luchansky E. Mental foramen and mental nerve: changes with age. Acta Anat (Basel) 126:21-28, 1986.

2. Ulm CW, Solar P, Biahout R, Marejka M, Watzek G, Gruber H. Location of the mandibular canal within the atrophic mandible. Br J Oral Maxillofac Surg 31:370-375, 1993.

3. Dharmar S. Locating the mandibular canal in panoramic radiographs. Int J Oral Maxillofac Implants 12:113-117, 1997.

4. Kieser J, Kuzmanovic D, Payne A, Dennison J, Herbison P. Patterns of emergence of the human mental nerve. Arch Oral Biol 47:743=747, 2002.

5. Oguz O, Bozkir MG. Evaluation of location of mandibular and mental foramina in dry, young, adult human male, dentulous mandibles. West Indian Med J 1:14-16, 2002.

6. Greenstein G, Tarnow D. The Mental Foramen and Nerve: Clinical and Anatomical Factors Related to Dental Implant Placement: A Literature Review. J

7. Mraiwa N, Jacobs R, van Steenberghe D, Quirynen M. Clinical Assessment and Surgical Implications of Anatomic Challenges in the Anterior Mandible Clinical Implant Dentistry and Related Research 5:219-225, 2006

8. Kumanovic DV, Payne AG, Kieser JA, Dias GJ. Anterior loop of the mental nerve: A morphological and radiographic study. Clin Oral Implants Res 14:464-471, 2003.

9. Misch CE. Root form surgery in the edentulous mandible: Stage I implant insertion. In: Misch CE, ed. Implant Dentistry, 2nd ed. St. Louis: The CV Mosby Company 347-370, 1999.

10. Bavitz JB, Harn SD, Hansen CA, Lang M. An anatomical study of mental neurovascular bundle-implant relationships. In J Oral Maxillofac Implants 8:563-567, 1993.

11. Jalbout Z, Tabourian G. Glossary of Implant Dentistry. Upper Montclair, NJ International Congress of Oral Implantologists 16, 2004

12. Solar P, Ulm C, Frey G, Matejka M. A classification of the intraosseous paths of the mental nerve. Int J Oral Maxillofac Implants. 9:339-344, 1994.

13. Neiva RF, Gapski R. Wang HL. Morphometric analysis of implant-related anatomy in Caucasian skulls. J Periodontol 75:1061-1067, 2004.

14. Polland KE, Munro S, Reford G, et al. The mandibular canal of the edentulous jaw. Clin Anat. 14:445-452, 2001.

15. Sonick M, Abrahams J, Faiella RA. A comparison of the accuracy of periapical panoramic, and computerized tomographic radiographs in locating the mandibular canal. Int J Oral Maxillofac Implants 9:455-460, 1994.

16. Lindh C, Petersson A. Radiologic examination for location of the mandibular canal: A comparison between panoramic radiography and conventional tomography. Int J Oral maxillofac Implants 4:249-253 1989.

17. Bou Serhal C, Jacobs R, Flygare L, Quirynen M, van Steenberghe D. Perioperative validation of localization of the mental foramen Dentomaxillofac radiol 31:39-43, 2002.

18. Klinge B, Petersson A, Maly P. Location of the mandibular canal: Comparison of macroscopic findings, conventional radiography, and computed tomography. In J Oral Maxillofac Implants 4:327-332, 1989.

19. Rothman SLG. Dental Applications of Computerized Tomography. Chicago: Quintessence 42-24, 1998.

Dental 3D Cone Beam CT Imaging: Part III

Dental cone beam 3D CT scans enable dentists to view anatomic structures not easily seen on 2D dental x-rays, including bifid mandibular canals, which is a common variation of the mandibular canal. The mandibular canal may split along different positions of the mandibular nerve; one branch may be smaller than the other (1-2). Langlais et al reported a 0.95% prevalence of bifid mandibular canals (3) while Sanchis (4) reported an incidence of bifid nerves as 0.4%, finding 7 out of 2012 mandibles that were studied. Many authors have investigated the incidence of bifid canals using panoramic or CT 3D images or both, and have concluded that while uncommon, they need to be identified when surgical procedures, such as removal of impacted third molars, insertion of dental implants in NYC, and osteotomies, are to be performed (5 - 9).

Once multiple (bifid) canals are identified, the local anesthetic injection technique, prosthetic design, and surgical procedures can need to be modified to prevent pain and discomfort during treatment procedures (10) in order to insure better outcomes.

The purpose of this study was to identify the incidence of bifid and/or multiple branches emanating from the inferior alveolar canal in 500 consecutive patients needing dental implants in NYC using cone beam 3D CT imaging .

Methods and Materials

CT scans of the dental arches from five hundred (500) consecutive patients taken in nine (9) centers located in three (3) states were uploaded to the main processing center of a single dental radiological practice (i-dontics, llc., New York, N.Y.), which is limited to taking and processing 3D CT images for the dental community. Scans were taken on either i-CAT scanners (8 centers) or on a (1) NewTom 3G scanner. All studies pertaining to gum disease in New York City were converted to SimPlant™ (Materialise, Glen Burnie, MD). When not specified, the data was converted to SimPlant™ version 10.

In Part I of the cone beam 3D CT study, the following parameters were recorded for each patient: age, gender, reason for the CT scan, which dental arch was to be studied, the format for the delivery of the data, and whether or not a radiographic guide was used. These results were published in Part I of the study. Parameters relative to the prevalence, location, and diameter of the lingual artery were measured and reported in Part II. The value and relevance of 3D imaging was also discussed in this paper.

In this study, Part III, the incidence of bifid nerves of the inferior alveolar canal were recorded by viewing images from a 3D dental cone beam CT scan. The position of the second canal was noted and listed as posterior to the teeth, within the body of the mandible but posterior to the mental foramen, coincident with the mental foramen, or anterior to the mental foramen. Multiple branches (more than two) were identified and recorded.

All CT studies were made into 1.0 mm slides and viewed both in the coronal and transaxial planes. To be counted as a bifid canal, each offshoot had to be continuous with the main inferior alveolar canal in each slice. For consistency, all CT studies were examined for bifid or multiple branches that were offshoots of the inferior alveolar canal by one examiner. A proper CT investigation is essential for perfect diagnosis of gum disease in NYC.

Results

Two hundred and ninety-six (296) mandibles were included in this 3D CT dental cone beam study. Of these, 186 patients or nearly sixty-three percent (62.84%) did not demonstrate evidence of a bifid canal. In contrast, 110 patients or more than thirty-seven percent (37.16%) had one or more bifid canals.


Figure 1. Nearly 63% of the mandibles studied did not have evidence of a bifid canal. However, 37,16% of the patients had one or more bifid canals.

Of the 110 patients demonstrating bifid canals, 56 or 50.9% had one bifid canal. Two bifid canals, as noted on CT scans, were demonstrated in 37 or 33.6% of the mandibles and 17 or 15.45% had three or more canals.


Figure 2. Of the mandibles demonstrating a bifid canal, more than half (50.9%) had one canal, while 33.6% had two canals and 15.45% had three or more canals.

Fifty-five (55.45%) of bifid canals were unilateral. Two thirds (67%) of the unilateral bifid canals were on the right side of the mandible; one third (33%) of the unilateral bifid canals were on the left side of the mandible. Nearly 46% (45.55) of the bifid canals were bilateral. These findings determined by viewing 3D CT images.


Figure 3. Fifty-five percent of the bifid canals were unilateral while nearly 46% were identified bilaterally.

In addition to identifying if a bifid canal was present, if it was in only the right or left side of the mandible or if they were bilateral, the location of each bifid canal was noted in the following manner: did it end at the mental foramen, posterior to mental foramen, or continue anterior to the mental foramen. Nine (9) bifid canals (8.18%) ended at the mental foramen, 94 or 85.45% ended posterior to the mental foramen and 7 or 6.36% continued anterior to the mental foramen.


Figure 4. The majority of the bifid canals (85%) ended posterior to the mental foramen, with 8 percent ending at the mental foramen and 6% extending beyond (anterior) the mental foramen.

Discussion

The relative incidence of bifid canals has been reported as less than 1% (3,4) of all gum disease in NYC, while it has been shown that the split of the mandibular nerve may be of unequal sizes (1,2). Regardless of the frequency of identifying bifid canals, various authors have identified the surgical risks and complications that may be experienced when they are encountered, including an inability to obtain profound anesthesia using a local anesthetic (5-9), injury from NYC dental implants, removing impacted wisdom eeth, and more.

In order to achieve standardization and consistency, the authors agreed as to what constitutes a bifid canal as identified on the 3D image: any branch that appeared as a continuous radiolucent canal extending from the inferior alveolar nerve. All 3D CT slices were 1mm in thickness and all bifid canals were viewed and appeared to emanate from the IAN in three planes: axial, coronal, and sagittal. Once the parameters were defined, one researcher examined and identified all of the bifid canals noted in this study, which were then verified by a second author.

Based on these parameters, the incidence of identifying bifid canals in this study was greater than in previously reported studies: 37%. The concept of bi- means “two,” and bifid means forked or cleft. While the purpose of this CT cone beam study in NYC gum disease was to identify the incidence of bifid canals, more than two canals of the IAN were identified in 17 patients or 15.45% of the cases. In most instances, 3 branches were identified; in one case, 8 branches were identified.

A relative few bifid canals ended at the mental foramen or extended anterior to it: 16 patients in total, or 14.54%. More than 85% of the bifid nerves identified in this study, as determined by 3D CT cone beam images, ended posterior to the mental foramen.

The significance of the findings in this study matters relative to the size and location of the bifid canals, and what clinical procedure is anticipated being performed. When it comes to operative dentistry, it has been postulated that bifid nerves may explain why anesthesia is not as profound as it should be when employing a local anesthetic. When encountered, infiltration of the local anesthetic to anesthetize these extra branches of the IAN may help achieve greater local anesthesia.

When planning New York City dental implants surgery, it is helpful to identify if bifid canals exist in the surgical site. Encountering these extra canals may not only contribute to unwanted local paresthesias of the gingival that these aberrant nerve branches may serve, but may explain unusual bleeding that emanates from the alveolar bone (10-11) during periodontal osseous or dental implant surgeries.

Figures 5 and 6 illustrate an example of multiple canals as they were identified in this study of gum disease in New York. While the widest branch, which is anterior to tooth #18, is evident on the panoramic slice, smaller canals are highlighted in Figure 6. Note the arrow in Figure 5 that highlights another bifid canal. Careful inspection will note additional canals emanating from the right IAN.


Figure 5. Arrow indicates a small bifid canal that starts and ends distal to tooth #31. A larger canal can be seen anterior to tooth #18.


Figure 6. The canal is highlighted in red, illustrating 3 bifid canals.

Mention must be made of the value of 3D images identifying normal and abnormal structures when compared to 2D images. Figure 7 is a panoramic image (formatted in a 15 mm trough) taken on a patient that was referred to the CT lab after an implant was inserted that resulted in paresthesia in the patient.


Figure 7. Patient presented after an implanted was inserted in the #30 site resulting in paresthesia.

Figure 8 highlights a bifid branch of the IAN that was traumatized by the implant. This aberrant branch was not evident in the panoramic view due to the dense cortical bone. Traditional 2D imaging - both panoramic or periapical film – is limited in revealing key anatomic structures that are obscured by thick buccal and/or lingual bone. In this example, using 3D imaging prior to implant insertion would have identified the bifid (aberrant) branch and altered the surgical site.


Figure 8. A bifid nerve rises from the IAN and was traumatized by the implant insertion.
It is suggested that more studies be undertaken to identify bifid canals and their clinical significance.

Conclusion

Utilizing 3D cone beam CT scanning images, this study identified bifid canals in 110 out of 296 patients. The incidence (37%) was greater than reported in other studies. The clinical implications of bifid canals were discussed, as well as an appreciation for the value of utilizing 3D CT cone beam scanners when possibly considering dental implants in New York City.

Acknowledgements: Support for this study was generously given by Nobel Biocare AB Gothenberg, Sweden (Grant 2006-492) and Imaging Sciences Inc., Hatfield, PA.

References:

1. Mardini S, Gohel A. Exploring the Mandibular Canal in 3 Dimensions.
An Overview of Frequently Encountered Variations in Canal Anatomy. AADMRT Newsletter, Fall 2008.

2. Jacobs R, Mraiwa N, vanSteenberghe D, Gijbels F, Quirynen M. Appearance, location, course, and morphology of the mandibular incisive canal: an assessment on spiral CT scan. Dentomaxillofacial Radiology 31:322-327, 2002.

3. Langlais RP, Broadus R, Glass B. Bifid mandibular canals in panoramic radiographs. Journal of the American Dental Association 110:923-926, 1985.

4. ] Sanchis JM, Penarrocha M, Soler F. Bifid mandibular canal. J. Oral Maxillofac. Surg. 61: 422–424, 2003.

5. Rouas P, Nancy J, Bar D. Identification of double mandibular canals: literature review and three case reports with CT scans and cone beam CT. Dentomaxillofacial Radiology 36:34-38, 2007

6. Naitoh M, Hiraiwa Y, Aimiya H, Gotoh M, Ariji Y, Izumi M, Kurita K, Ariji E.
Bifid Mandibular Canal in Japanese. Clinical Science and Techniques Implant Dentistry. 16:24-32, 2007.

7. Claeys V, Wackens G. Bifid mandibular canal: literature review and case report. Dentomaxillofacial Radiology 34, 55-58, 2005.

8. Auluck A, Ahsan A, Pai KM, Shetty C. Anatomical variations in developing mandibular nerve canal: a report of three cases. Neuroanatomy; 4: 28–30, 2005.

9. Dario LJ. Implant placement above a bifurcated mandibular canal: A case report. Implant Dent 11: 258-261, 2002.

10. Auluck A, Ahsan A, Pai KM, Mupparapu M. Multiple mandibular nerve canals: Radiographic observations and clinical relevance. Report of 6 cases. Quintessence International. 38:781-787, 2007.

11. Winter AA. Bleeding from a Nutrient Canal: A Case Report. NY State Dent J 46:646, 1980.

Dental 3D Cone Beam CT Imaging: Part II Insertion of Lingual Artery

With the proliferation of more 3D dental cone beam CT scanners, more and more patients arebeing prescribed to have dental CT scans taken for a variety of reasons. At the present time, many scans are taken within the treating dentist’s office where the clinician owns his/her own3Dscanner. However, most dentists do not own their own cone beam 3D CT scanner. In instanceswhen 3D images are needed, patients may be referred to a dental radiological lab that isspecifically designed as a freestanding office that performs CT scanning for the dental community. While a majority of dental patients currently referred for CT scans are for pre-surgical dental implant analyses to avoid injuring the mandibular nerve or violating the maxillary sinuses, other common reasons for 3D imaging include identifying the precise location of impacted teeth, studies for an assortment of pathologies, views of the condyles, and for orthodontic analyses (1).

Part I of this dental cone beam CT study analyzed the demographics of 500 consecutive patients referred to i-dontics, llc radilogical labs (2). This article, Part II, consists of observations regarding the frequency, width, and location of the insertion of the lingual artery into the mandible on 296 out of 500 consecutive patients referred to a dental radiological lab for 3D CT scans. This study identified the radiographic presence or absence of the lingual artery, where it inserted into the mandible, how many branches of the lingual artery were present and what was the diameter of the most superior branch of the lingual artery. A discussion of the clinical ramifications of identifying the width and location of the insertion of the lingual artery as they relate to dental implant insertion follows.

Methods and Materials

Dental 3D CT scans of the dental arches from five hundred (500) consecutive patients taken in nine (9) centers located in three (3) states were uploaded to the main processing center of a single dental radiological practice (i-dontics, llc., New York, N.Y. USA) which is limited to taking and processing 3D CT images for the dental community. Dental scans were taken on either i-CAT scanners (8 centers) or on a (1) NewTom 3G scanner. All studies were converted to SimPlant™ (Materialise, Glen Burnie, MD, USA). When not specified, the data was converted to SimPlant™ version 10. The following parameters were recorded for each patient: age, gender, reason for the dental 3D CT scan, which dental arch was to be studied, the format for the delivery of the data, and whether or not a radiographic guide was used. These results were published in Part I of the study.

In this study, mandibles were evaluated for the following: the radiographic presence or absence of the lingual artery, where it inserted into the mandible, how many branches of the lingual artery were present and what was the diameter of the most superior branch of the lingual artery. These anatomic structures are vital to recognize in order to reduce risk and optimize dental implant placement.

Results

3D cone beam dental CT scans from 500 consecutive patients requiring were included in this study. Of them, 296 cases were of the mandible. The following observations were noted:

# of lingual arteries:

1. 290 or 98% had observable insertions of the lingual artery into the mandible.

2. 119 or 40.2% had one lingual artery

3. 139 or 47% had 2 lingual arteries

4. 31 or 10.7% had 3 lingual arteries.

5. 1 or 0.34% had four lingual arteries

Figure 1. 40.2% had one lingual artery; 47% had 2 branches; 10.7% had 3 branches and there was 1 patient with 4 branches of the lingual artery.

Location of insertion of lingual artery relative to mandibular height:

A. Average length of lingual artery inserted into the alveolar bone = 9.6mm

B. 10 cases inserted in the crestal 1/3 = 3.44%

C. 262 cases inserted in middle 1/3 = 88.5%

D. 176 cases inserted in apical 1/3 = 59.45%

Location of insertion of lingual artery relative to the genial tubercle:

a. 271 cases of lingual artery inserted above tubercle = 91.55%

b. 170 cases of lingual artery inserted below tubercle = 57.43%

c. 37 cases of lingual artery inserted on tubercle = 12.76%

Diameter of lingual artery measured by “rule” calibrated in software:

i. 233 lingual arteries less than 1mm diameter = 80.3%

ii. 57 lingual arteries greater than 1mm in diameter = 19.7%

Examples

Increasingly dental 3D cone beam CT imaging is being utilized for dental implant placement, yet many clinicians continue to rely on 2D dental X-rays including periapical films and panoramic images. Patients may be referred for a dental CT scan when there is limited bone available above the inferior alveolar canal or for atrophic bone under the maxillary sinuses. Oftentimes, there is a sense of security when dental implants are being placed anterior to the mental foramina, especially when two or more implants are utilized to help stabilize a mandibular denture or fixed prosthesis. While the risks remain limited, a review of the literature minimally suggests that the location and diameter of the insertion of the lingual artery into the mandible is as important as knowing the width and density of the available bone. The following examples demonstrate the value of 3D imaging in preparation for placement of anterior mandibular dental endosseous implants.

Figure 2 is a panoramic view of an edentulous site in the mandibular anterior where dental implants were to be considered for insertion. In this image, there is no way to determine the width of the available bone or where the lingual artery inserts into the mandible without the benefit of 3D cone scan CT imaging.

Figure 2. Panoramic view does not reveal the width of the bone or the location of the insertion of the lingual artery into the mandible.

Figure 3 is a transaxial view through the #25 site. It reveals a narrow, spinous crest of bone that contains very little cancellous bone which is too narrow – at that point - to insert a dental implant. Midway down the lingual plate, the lingual artery can be observed inserting into the mandible. This artery is not very wide but may be of concern should a dental implant be inserted through it, piercing the lingual plate of bone. This information was not clinically evident on conventional 2D X-ray imaging.

Figure 3. Transaxial (cross-sectional) view demonstrates the value of 3D imaging by exposing the narrow width of the crestal bone and the location of where the lingual artery inserts into the mandible.

Figure 4 is an example (no implant is planned in this case) of a wide-diameter lingual artery that puts the patient in jeopardy should this artery be severed during implant surgery. This is an example of a critical anatomic structure that cannot be observed through conventional 2D X-ray imaging (dental periapical films or panoramic images) but is readily apparent in transaxial (cross-sectional) views from dental CT cone beam scanners.

Figure 4. An example of a wide lingual artery viewed in cross-section than cannot be seen in 2D images.

While atrophy compromises any edentulous area adjacent or proximal to key anatomic structures for dental implant placement, the mandibular anterior region is vulnerable to potential risk relative to the width and insertion of the lingual artery. Seemingly harmless perforations can lead to large hematomas or an arterial bleed that could discharge a considerable amount of blood into the lingual soft tissues. Sometimes, a delayed sublingual hematoma forms as the result of reflex or it my rebound by dilating after the effect of vasoconstrictors wears off from the local anesthetic. Oftentimes, the adjacent soft tissues exert enough pressure to tamponade itself to avert a bleeding crisis (5). If this does not happen, the surgeon needs an action plan to control sublingual hemorrhaging or dire consequences may result from continued bleeding. Employing the benefits of 3D dental cone beam scanners mitigates these risks to the patient.

Discussion

In this study, the presence, location, length and diameter of the insertion of the lingual artery into the mandible in 296 mandibles were evaluated by 3D cone beam CT dental scanners. Two hundred and ninety (290) or 98% of the patients had identifiable lingual arteries with the remainder having vessels inserting in the premolar areas. Eighty-seven percent (87.2%) had either one or two lingual arteries with the superior most vessel inserting through the middle of the lingual plate in 88.5% of the patients. Over 91% (91.55%) of the vessels inserted above the genial tubercle and 80.3% of the vessels were less than 1mm in diameter.

Schick et al (3) scanned 32 patients scheduled for mandibular dental implants to determine if CT scans could depict the presence, diameter, position, direction and frequency of vessels. In their study, lingual vascular canals were demonstrated in all patients. Most lingual canals were located in the midline and the mean diameter of the lingual canals was 0.7mm. Similar studies in 3 cadavers confirmed these findings, concluding that the occurrence, position and size of the lingual vessels could be depicted on CT scans.

As more patients seek dental implant placement in order to avoid or stabilize mandibular dentures, it is important for dentists to understand the limitations of 2D X-rays imaging especially when it comes to identifying the presence, location, and diameter of the lingual artery and its insertion into the mandible. Niamtu described a case of a near-fatal airway obstruction that resulted from sublingual bleeding following dental implant placement (4).

Isaacson (5) described the incidence and possible causes for a sublingual hematoma including dental implant insertion in the mandible likely caused by bleeding from perforation of the lingual cortex and violation of one of the branches of the sublingual or facial arteries. A review of the literature revealed that these occurrences could be life-threatening and that clinicians need to be prepared for the management of an acute airway obstruction that could result in intubation or tracheotomy (6-17)

Conclusion

Part II of this study evaluated parameters involving the lingual artery on dental 3D CT cone beam studies in 296 patients. Observations included the radiographic presence or absence of the lingual artery, where it inserted into the mandible, how many branches of the lingual artery were present and what was the diameter of the most superior branch of the lingual artery.

Dental implant placement in the mandibular anterior region is most often a benign procedure. However, dentists should bear in mind the potential risk of severing the lingual artery and piercing the lingual plate. The limitations of 2D X-rays compared to value of 3D cone beam CT images were discussed, including limiting risk and enhancing the clinical outcome for dental implant placement and subsequent restorations.

Acknowledgements: Support for this study was generously given by Nobel Biocare AB Gothenberg, Sweden (Grant 2006-492) and Imaging Sciences Inc., Hatfield, PA.

References

1.Valiathan A, Dhar S, Verma N: 3D CT imaging in Orthodontics: adding a new dimension to diagnosis and treatment planning. Trends Biomater. Artif. Organs 21:116-120, 2008

2.Winter AA, Yousefzadeh K, Pollack AS, Stein MI, Murphy FJ, Angelopoulos C. Dental Radiological Lab Usage and Findings: Part I Demographics (accepted for publication in JICAD 2009

3.Schick S, Zauza K, Watzek G. Lingual Vascular Canals of the Mandible: Evaluation with Dental CT. Radiology 220:186-189, 2001

4.Niamtu, J. Near-fatal airway obstruction after routine implant placement. Clinical notes. O Med, P Path, O Rad & End 92(6)597-600, 2001

5.Isaacson, T. Sublingual hematoma formation during immediate placement of mandibular endosseous implants. JADA 135:168-172, 2004.

6.Goldstein B. Acute dissecting hematoma: a complication of oral and maxillofacial surgery. J Oral Surg 39(1):40–3, 1981

7.Mordenfield A, Andersson L, Bergstrom B. Hemorrhage in the floor of mouth during implant placement in the edentulous mandible: a case report. Int J Oral Maxillofac Implants 12:558–61, 1997

8.ten Bruggenkate CM, Krekeler G, Kraaijenhagen HA, Foitzik C, Oosterbeek HS. Hemorrhage of the floor of the mouth resulting from lingual perforation during implant placement: a clinical report. Int J Oral Maxillofac Implants 8:329–34, 1993

9.Mason ME, Triplett RG, Alfonso WF. Life-threatening hemorrhage from placement of a dental implant. J Oral Maxillofac Surg 48: 201–4. 1990

10. Givol N, Chaushu G, Halamish-Shani T, Taicher S. Emergency tracheostomy following life-threatening hemorrhage in the floor of the mouth during immediate implant placement in the mandibular canine region. J Periodontol 71:1893–5, 2000

11.Burke R, Masch G. Lingual artery hemorrhage. Oral Surg Oral Med Oral Pathol 62:258–61, 1986

12.Krenkel C, Holzner K. Lingual bone perforation as causal factor in a threatening hemorrhage of the mouth floor due to a single tooth implant in the canine region. Quintessence 37:1003–8, 1986?

13.Laboda G. Life-threatening hemorrhage after placement of an endosseous implant: report of case. JADA 121:599–600, 1990?

14. Darriba MA, Mendonca-Caridad JJ. Profuse bleeding and life-threatening airway obstruction after placement of mandibular dental implants. J Oral Maxillofac Surg 55:1328–30, 1997

15. Panula K, Oikarinen K. Severe hemorrhage after implant surgery (letter). Oral Surg Oral Med Oral Pathol Oral Radiol 87(1):2, 1999

16. Mardinger O, Manor Y, Mijiritsky E, Hirshberg A. Lingual perimandibular vessels associated with life-threatening bleeding: an anatomic study. Int J Oral Maxillofac Implants. 22(1):127-31, 2007

17. Kattan B, Snyder H. Lingual artery hematoma resulting in upper airway obstruction. J Emerg Med 9:421-424, 1991

Dental 3D Cone Beam CT Imaging: Part I Demographics

Dental 3D cone beam CT imaging has replaced traditional medical CT scans that first became commonplace after endosseous dental implants were first introduced by Dr. Per-Ingver Brånemark (1) in the early 1980s. With the advent of the DentaScan software, dentists viewed CT images in multiple planes: coronal (known as panoramic), axial, and sagittal (known as cross-sectional or transaxial) for better and safer implant placement. Applications for CT scans extended from implantology to other oral and maxillofacial uses (2-9). Until recently, CT scanners were situated in medical radiological offices where dentists referred their patient for 3D studies for implant treatment planning. With the introduction of cone beam volumetric tomographic (CBVT) scanners in April, 2001, a new era of dental radiology was launched (10).

These 3D cone beam dental (CBVT) scanners, approved by the FDA as dental devices and often referred to as “dental CT scanners,” offered improved diagnostic tools over existing medical CT scanners due to their low-dose radiation requirements and more accurate, diagnostic images for implant placement, removal of impacted wisdom teeth, and more. Dental radiological labs first gained recognition (1972) in California when oral and maxillofacial radiological technicians were permitted to own and operate X-rays centers. Upon their introduction, these radiological labs embraced cone beam scanners (NewTom 9000).

The first change to a 3D dental scanner was introduced by Imaging Sciences International - the i-CAT™ - in March, 2004. This dental CT cone beam scanner had a smaller footprint and was designed for dental offices. Rather than lie on a gurney, patients would sit in a chair while the scan was taken. This version of the CBVT scanner enabled busy dental practitioners to buy 3D CT scanners. In addition to using it for their own patients, dentists often solicited colleagues in their community to their send patients for dental 3D CT images. In effect, they created de facto radiological practices. And still others, both dentists and/or entrepreneurs, created freestanding radiological labs for the express purpose of taking and processing 3D CT images for other dentists.

To date, data concerning the type of patient referred to a dental cone beam radiological center and the reason for the prescribed 3D CT scan has been anecdotal. While it is assumed that the main reason most dental patients are referred for CT scans is for pre-surgical dental implant analyses, no article has studied the demographics of this relatively new phenomenon: the dental cone beam 3D CT radiological lab.

The purpose of this study was to determine how and for what reason dentists currently utilize a 3D cone beam CT imaging center. In addition to the types of patients and the reasons they were referred for CT scans, the following were recorded from each study when appropriate: the incidence and location of the lingual artery inserting into the mandible, measurements and observations about the extension of the inferior alveolar canal anterior to the mental foramen, the incidence and location of bifid canals, the incidence of sinus pathology, and the identification of incidental findings other than the reason for the CT referral including impacted teeth, periapical radiolucencies, pathologies, retained roots, etc. All of these anatomical structures impact on the success, failure, and risk of dental implants, removal of impacted third molars, and other dental surgical procedures.

Part I of this study consists of data of patients referred to a dental radiological lab for 3D CT scans including age, gender, purpose of the CT study, which arch was requested, if a radiographic guide was used, and in which format the study was requested to be processed.

Methods and Materials

Data from five hundred (500) consecutive patients sent to i-dontics center from 9 centers located in 3 states were evaluated. Scans were taken on either a cone beam 3D i-CAT (8 centers) CT scanners or on a NewTom 3G (Manhattan) scanner and uploaded to a central data center. All studies were converted to SimPlant™ (Materialise, Glen Burnie, MD). When not specified, the data was converted to SimPlant™ version 10. The following parameters were recorded for each patient: age, gender, reason for the scan (i.e. dental implants), dental arch studied, the format for the delivery of the data, and whether or not a radiographic guide was used.

Results

One Hundred and ten (110) dentists referred 500 patients for 3D cone beam CT studies. Two hundred and twenty-eight (228) or 44.4 % of all patients referred for were male; two hundred and seventy-two (272) or 55.6% of the patients were females (Figure 1).


Figure 1. Gender of patients.


Patient ages ranged from 15 – 102 years (Figure 2). The mean age was 56.7 years.


Figure 2. Number of patients in each age category.

Reasons for CT scans. The predominant reason for referral for dental CT cone beam scan was for pre-surgical analysis for dental implants. Four hundred and fifty-one patients (451) were referred for dental implants; 20 for impacted teeth; 10 for pathology; 7 for endodontics; 4 for orthodontics; 1 for TMJ disorder; 7 unknown (Figure 3).


Figure 3. A = 451 Patients referred for CTs for implants; B = 20 patients for impacted teeth; C = 10 patients for pathology; D = 7 patients for endodontics; E = 4 patients for orthodontics; F = 1patient for TMJ; G = 7 patients unknown reason for referral for CT.

Each 3D CT study was categorized either as a mandibular scan or a maxillary scan, or both, regardless of the reason for the dental CT 3D scan (implants, impactions, endodontic problems, or pathology). In the single instance of a TMJ study, the patient also had an edentulous mandibular site evaluated for an implant, so this patient was counted as a mandibular study (Figure 4).


Figure 4. CT scans for the maxilla = 40.8%; CT scans for the mandible = 43.4%; CT scans for both arches = 15.8%.


Delivery format. CT dental cone beam studies were requested in a variety of formats: via Internet; transparencies; CD; Prints. In 12 instances, studies were requested in multiple formats by students in the implant program at New York University College of Dentistry. Consequently, 512 different formats were requested for the studies: transparencies = 42; glossy prints = 55; CDs = 239; and 176 via the Internet (Figure 5).


Figure 5. Formats for CT scans were received in four ways: Film, Prints, Internet, and CD.

Software. Four hundred and four (404) requests were made for specific 3D CT dental treatment planning software. The requests were as follows: SimPlant™ = 273; DICOM = 114; i-CAT/i-Vision = 14; NobelGuide = 3. All DICOM cases, except for the 3 requested for NobelGuide, were imported into VIP software by Implant Logic Systems. When no request was made for a specific software format, then prints or film were printed in SimPlant™ format, but these numbers are not counted as specific software requests. The total number of requests + prints + film exceeds 500 patients since some doctors requested studies in multiple formats (Figure 6).


Figure 6. CT studies for the most common 3D third party software requested was SimPlant™, followed closely by DICOM used specifically for VIP software by Implant Logic Systems.

Over the years, SimPlant has issued many different versions of its 3D dental implant software. As a SimPlant™ Master Site, it was noted that dentists did not install each new version as they were released. Most of this study was compiled just before version 11 was released. As a result, of the 273 studies in SimPlant™, the following versions were requested: version 8 = 19; version 9 = 130; version 10 = 105; version 11 = 12; SimPlant viewer = 7 (Figure 7).


Figure 7. Demonstrates the proportion of the different versions of SimPlant™ requested.

Radiographic Guides. One hundred and eight patients (108) had radiographic guides fabricated by their dentists that were inserted during the CT scan. These guides helped pinpoint” more accurate dental implant placement, while reducing surgical risks. Of these, 3 were for NobelGuides. Patients presenting with guides = 21.6%.

DISCUSSION

Sir Godfrey Newbold Hounsfield conceived of creating a radiological (CT) machine to create cross-sectional views in 1967. In 1972, Hounsfield introduced the first Computed Tomographic scanner; CT reconstruction software dedicated to dental diagnostics has been available since the 1980s. This software, known as the DentaScan, enabled multi-planar views of the CT data into axial or occlusal, panoramic-like or coronal, and sagittal or cross-sectional images of either arch (2-4), which aided dental surgeons in implant placement.

The next milestone for dentists in 3D CT imaging was the introduction of the NewTom 9000 cone beam volumetric scanner by QR Verona in the late 1990s (10). This scanner received FDA approval in the United States in April, 2001. Unlike a medical scanner, the NewTom 9000 was designed specifically to image the maxillofacial region. The patient exposure effective dose is 50 μSv which is significantly less than a high-resolution medical CT scan and similar to that of a dental periapical full-mouth series.13,14 Since then, there has been a proliferation of manufacturers (the most notable was Imaging Sciences Inc., Hatfield, PA) introducing similar 3D cone beam CBVT scanners to the marketplace that took the scan with the patient sitting in a chair rather than lying on a gurney. In time, a host of 3D software vendors (Materialise, Glen Burnie, MD) entered the marketplace that enabled DICOM files created by these scanners to be imported into their respective software. Software frequently used for dental implants include NobelGuide™ by NobelBiocare, VIP™ by Implant Logic Systems, SimPlant™ by Materialise, and In Vivo™ by Anatomage. In orthodontics, Dolphin Imaging™ by Dolphin, SureCef™ etc. are also available.

As with other clinical innovations, common usage lags behind its introduction to the profession. This is true of dental implants, where market penetration is estimated to be in the range of 4-8%. Likewise, the utilization of diagnostic 3D imaging lags behind the long-time accepted use of 2D imaging of dental periapical and panoramic films, in spite of the fact that these images can be distorted (11). As such, the increased utilization of 3D diagnostic imaging is arguably becoming the standard of care when it comes to pre-surgical analyses of complex dental implant treatment plans (12).


In the present study 500 consecutive patients, referred by 110 different dentists, were evaluated as to their age, gender, and reason for being referred to a dental 3D imaging center that utilizes a CBVT (cone beam) scanner. Forty-four (44%) percent of the patients referred were male; 56% were female. Patients ranged from 15-102 years of age, with an average age of 56.7 years. Younger patients were most often referred for orthodontic reasons, to evaluate impacted teeth, or were post-orthodontic and were being evaluated for sites of congenitally missing teeth for implant placement, most often for missing maxillary lateral incisors.

The single reason for the vast majority of patients, 451 or 90.2% referred was for dental implants. Other reasons for CT scans included: evaluating impacted teeth (4%); pathology (2%); endodontics (1.4%); orthodontics (0.8%); TMJ disorder (0.2%) and 7 patients were referred for unknown reasons (1.4%).


Referrals for single arches – maxilla (40.8%) versus mandible (43.4%) - were similar, while 15.8% or 79 patients were referred for 3D CT cone beam scans of both arches.

There was diversity in how dentists wanted to receive the CT 3D dental studies. 512 different formats were requested: transparencies, glossy prints, studies on a CD or to receive the study via the Internet. Twelve dentists required multiple formats. The format dentists most preferred was CD (47%), followed by the Internet (34%). Glossy prints (11%) and 8 x 10 transparency format (8%) were the least requested. It should be noted that most of the Internet requests were for DICOM studies and were made by dentists using VIP™ software by Implant Logic Systems or SimPlant™ by Materialise. Those dentists, or a member of their staff, who were comfortable using the Internet had web access in their offices and took advantage of the speed, efficiency, and benefits of Internet transmission.


The most common third party 3D dental software used by dentists in this study was SimPlant™ (54.6%). One hundred and fourteen (114) DICOM images (22.8%) were requested, which were converted into VIP™ or NobelGuide™ software; 14 studies (2.8%) were requested for either i-CAT or i-Vision™ (by Imaging Sciences, Inc) and 3 studies (0.6%) required 2 scans for NobelGuide™ by NobelBiocare. The more common usage of SimPlant is not surprising since there are many SimPlant Master™ sites in the New York tri-state area and dentists have been accustomed to using this software for many years. The relatively high request for DICOM images was a function of geography due to the popularity of VIP software in the Brooklyn/Long Island area. While the different 3D dental software usage has been consistent in this study over a long period of time, regional trends may dictate which studies are requested from different CBVT radiological labs.

SimPlant™, long the established leader in 3D dental software, issues new versions of their treatment planning software frequently. Yet, the experience at this SimPlant Master Site indicates that dentists do not install the latest version when it is first received. While some dentists do install it immediately, many wait when they are comfortable with the present version they are using or, perhaps, they choose to wait to make certain “bugs” are not discovered by other users before they install it in their systems. Consequently, 19 studies were processed in version 8, while versions 9, 10, and the recently issue v. 11 were more commonly used. Since the data was collected, SimPlant™ version 12.0 has been issued.


The most unexpected finding of this study was that 108 or 21.6% of all patients referred for 3D CT scans came with radiological guides to be worn during the scan. These guides used gutta-percha, barium sulfate, or medical ball bearings as markers to be seen on the CT scans to help guide the dentist in interpreting where dental implants should be inserted. There was no attempt to determine how many surgical guides were created from the data in this study.

The results of this study demonstrate that while dentists use 3D cone beam imaging predominantly for dental implants, patients are referred to help diagnose and treat other dental entities. Future articles compiled from this data will report on the incidence and location of the lingual artery inserting into the mandible, measurements and observations about the extension of the inferior alveolar canal anterior to the mental foramen, the incidence of bifid canals, the incidence of sinus pathology, and the identification of incidental findings other than the reason for the CT referral including impacted teeth, periapical radiolucencies, pathologies, retained roots, and more.


Conclusion

A study of 500 patients referred to i-dontics dental radiological centers for 3D cone beam (CBVT) studies indicated the majority of patients were referred for pre-surgical analyses for dental implant insertion. Other reasons include impacted teeth, orthodontic problems, and a variety of oral and dental pathologies, recalcitrant endodontic lesions, and TMJ disorders. A significant number of patients (21.6%) presented with and wore radiological guides during the CT scan.

Acknowledgements: Support for this study was generously given by NobelBiocare AB Gothenberg, Sweden (Grant 2006-492) and Imaging Sciences Inc., Hatfield, PA.

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