Dental implants, NYC: Esthetic Implants with Natural Pink

Dental implants, while more commonplace and accepted as a “routine” dental procedure, are still undergoing refinements in New York City. No longer are we satisfied with the fact that the jaw bone has fused to the implant – we call this osseointegration – but we strive for the most esthetic outcome possible. Dentists need to be vigilant about how thin or thick a patient’s gum tissue is. We call this the “biotype.” When the tissue is thick, dental implant esthetics are easier to achieve. If the tissue is thin, as in this example, the implant can be seen through the gums, giving it a gray hue.

Thin tissue permits implant to be visible through gums

While virtually all dental implants are composed of titanium, and regardless of how the surface is roughened to enhance bone attachment, the implants are gray. To date, attempts to make “white” dental implants have not been all that successful. But now, there is a new implant by Keystone Dental, Inc., that addresses this important esthetic issue.

Keystone has created the “Genesis” implant that has a pink collar that is called, AnaTite™ that projects a hue that resembles gingival tissue. Not only is the collar pink on this dental implant, but the abutment which supports the crown, is also pink.


The result is an esthetic crown, supported by a stable dental implant under the gums.


The picture, below demonstrates the cosmetic benefit of using the Genesis dental implant in NYC.

Dental implants in New York City are a successful procedure that can be enhanced by the type of implant used. While most implants osseointegrate, the biotype of a patient’s gingival may affect the esthetic outcome. Patients needing implants in NYC should become familiar with their tissue type, whether it is thin or thick, and what cosmetic outcome can be expected from a New York City periodontist inserting a dental implant.

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.

References

1) Brånemark P-I. Osseointegration and its experimental background. J Prosthet Dent 50:399-408, 1983


2) Schwarz MS, Rothman SLG, Rhodes ML et al: Computed tomography: Part I. Preoperative assessment of the mandible for endosseous implant surgery. Int J Oral Maxillofac Implants 3: 137-141, 1987.

3) Schwarz MS, Rothman SLG, Rhodes ML et al: Computed tomography: Part II. Preoperative assessment of the maxilla for endosseous implant surgery. Int J Oral Maxillofac Implants 3: 143-148, 1987.


4) Casselman JW, Deryckere F, Robert Y et al: Denta Scan: program of x-ray computed tomographic reconstruction used for the anatomical evaluation of the mandible and maxilla in preoperative assessment of dental implants. Ann Radiol 33: 408-417, 1990.

5) King JM, Caldarelli DD, Petasnick JP: DentaScan: a new diagnostic method for evaluating mandibular and maxillary pathology. Laryngoscope 102: 379-387, 1992.

6) Yanagisawa K, Friedman CD, Vining EM et al: DentaScan imaging of the mandible and maxilla. Head Neck 15: 1-7, 1993.

7) Calgaro A, Bison L, Bellis GB, Pozzi Mucelli R: Dentascan computed tomography of the mandibular incisive canal. Its radiologic anatomy and the therapeutic implications. Radiol Med 98: 337-341, 1999.

8) Au-Yeung K.M.; Ahuja A.T.; Ching A.S.C.; Metreweli C.: DentaScan in oral imaging. Clinical Radiol 56: 700-713, 2001.


9) Abrahams JJ: Dental implants and multiplanar imaging of the jaw. In: Som PM, Curtin HD (eds). Head and neck imaging, 3rd ed, p 350-374. Mosby, St. Louis, 1996.

10) Mozzo P, Procacci C, Tacconi A, Tinazzi Martini P, Bergamo Andreis A.: A new volumetric CT machine for dental imaging based on the cone-beam technique: preliminary results. Eur Radiol. 1998; 8:1558–1564.


11) Sonick M Abrahams J, Faiella R.: A comparison of the accuracy of periapical panoramic and computerized tomographic radiograph in locating the mandibular canal. Int J Oral Maxillofac Implants, 9:455-460; 1994.


12) Winter, AA: Why CT scans are already the standard of care. NYSD J 73:vol 6: 28-30, 2007.

13) JB Ludlow, LE Davies-Ludlow, SL Brooks, and WB Howerton: Dosimetry of 3 CBCT devices for oral and maxillofacial radiology: CB Mercuray, NewTom 3G and i-CAT. Dentomaxillofacial Radiology 35: 219-226, 2006.

14) Mah J, Danforth R, Bumann, Hatcher D. Radiation absorbed in maxillofacial imaging with a new dental computed tomography device. OOO. 2003; 96:508–513.

Ridge Splitting: Ridge Augmentation Without Grafts or Membranes

Ridge Augmentation is a commonplace procedure to rebuild bone lost when teeth are removed.



Note the concavity caused by removing a tooth

The goal of implant treatment is not only to successful insert the implant and fabricate a crown on it so the patient can function in comfort, but to missing bone, gum tissue, and to have the implant “emerge” out of the bone like a natural tooth.



The expanded ridge restores the missing bone and gum tissue.

demonstrates the post-operative result after an implant has been inserted, the atrophic ridge expanded by a ridge splitting technique, and the crown is inserted.



The goal is to make the implant crown, including its supporting tissues, indistinguishable from a natural tooth and its tissues. In this case, the implant crown is on the right.
In most cases with severe alveolar bone loss, a procedure – known as ridge augmentation – is commonly performed to increase the width of the atrophic ridge by using bone grafts and a membrane. The healing time for this prodecure is roughly six months. This long healing time delays the time when the final restoration can be fabricated and inserted, and it is costly. An alternative is to expand the ridge via a special technique that reduces the healing time, is less costly, and yields a predictable, lasting result.
Another example of ridge splitting that helps to restore lost tissues caused by the removal of a tooth can be seen.



Note the “dished in” or caved in appearance caused by the removal of the left central incisor.



Notice how the lost tissues have been restored via ridge splitting, recreating normal root anatomy, normal gingival architecture, and an esthetic crown.

demonstrate an atrophic ridge. Without performing some form of bone enhancement, the implant would be inserted in an unfavorable position. Biting forces could be deleterious and oral hygiene measures could be difficult. Esthetics would be severely compromised. Under most circumstances, dental surgeons try to correct this defect with a ridge augmentation procedure that utilizes expensive materials and takes a long time to heal. An alternative, known as ridge splitting, enables the skilled clinician to expand the ridge and, at the same time, insert a dental implant without the need for either bone graft material or a membrane known as GBR or Guided Bone Regeneration technique.



Note the compressed ridge where the tooth is missing. If the implant is inserted in this bone, without changing its width, the implant will be too palatal and out of alignment.



demonstrates how the ridge is expanded and a space opened wide enough to insert a dental implant.



demonstrates the bone flap created by the ridge splitting and the implant being inserted.



Thisi is a cross-sectional 3D image of the implant after 3 months of healing. Notice that the “bone flap” has healed and remains present.
While ridge augmentation and GBR is acceptable and well-documented technique, ridge splitting accomplishes the same goals of recreating both lost hard and soft tissues without using expensive materials or taking a long time to heal. While technique sensitive, ridge splitting is atraumatic and simpler for the patient, with a predictable outcome.

*These images are from author’s previous practice.

Extract and Implant vs. Crown Lengthening

The decision-making process as to when to save a compromised tooth as opposed to extracting it has been influenced by the predictable success of dental implants. Factors considered in saving a tooth include whether there is enough structure left to support a crown; is the decay or tooth fracture so deep as to require a root canal or osseous surgery; is retreatment of a previously done root canal required; does bone need to be removed in order to make a proper-fitting crown; and what is the dental status of the adjacent teeth?

The following case typifies how these and other factors help the patient and treating dentist decide on the best treatment course for a problem tooth.
A 25 yr old female presented with a post-and-core fractured at the bone level on tooth #29 (Fig 1). The crown could no longer be attached, the root canal filling was incomplete, and the adjacent tooth (#28) had no restoration.



figre 1 : The tooth structure is at the bone level.

To save the tooth, bone needed to be removed (crown-lengthening) in order to gain enough root structure to fabricate a properly fitting crown. Weighing the many treatment steps and risks necessary to save this tooth – removing the post to retreat the root canal or performing a root-end surgery known as an apicoectomy, removing bone, and fabricating a restoration that has an unfavorable crown-to-root ratio, it was decided to extract the tooth and insert a dental implant.



Figure 2. Tooth removed.

Figure 2 demonstrates the tooth removed and a direction indicator to help determine the implant placement. The osteotomy site was prepared and a NobelBiocare Active implant inserted into the site (Fig 3).



Figure 3. Implant in place.

In this case, it was determined that the best treatment for a 25 year-old patient was not engage in the multiple risks to save the tooth that would leave the patient the patient with a compromised tooth. This treatment choice resulted in preserving bone, not damaging the adjacent teeth by making a bridge, and being able to insert a dental implant at the time the tooth was extracted in order to provide the most predictable and lasting treatment for a severely compromised tooth.

Launching a New Dental Practice Is a Challenge in This Economy

What most people inherently know but don’t think about is that unless it’s an emergency like a throbbing toothache or a facial swelling that requires immediate care, dentistry competes for discretionary dollars. What sort of discretionary dollars? New clothes, vacations, jewelry, presents or even that new car. Being mindful that this is not a good economic environment to start a dental practice, Dr. Alan Winter still decided to leave his periodontal group practice and strike out on his own. In order to achieve this goal, a number of thought processes were critical in how he went about this daunting task. The first step was to find a suitable office.

In New York City, this is not easy. He had to be in mid-town, and he had to be centrally located to both his referring dentists and to public transportation. He also had to find a building willing to take on a dentist as a tenant, because many buildings look unfavorably on dentists due to the traffic of patients, water needs, and the smell of medicaments (even though this is ancient history). As luck would have it, a colleague, Dr. Marc Beshar was in the market to transfer his lease and existing dental office to a dentist so that he could move his cosmetic practice a few blocks over to a landmark building. Dr. Beshar’s needs turned into the first cornerstone of Dr. Winter’s plan: find an existing office to minimize dollars required to build out a new facility.

In this case, Dr. Beshar had four operatories and a laboratory that was in a room large enough to be turned into a treatment room. In addition, he had already negotiated a new lease with his building’s landlord, paving the way for another dentist to continue in his space. When Dr. Winter learned of this opportunity, he jumped at the chance of taking over the lease in a favorable location with a landlord committed to a dental tenant. Dr. Winter bought the existing equipment from Dr. Beshar and an added benefit was to turn the laboratory into a fifth treatment room.

As soon as the deal was struck, Dr. Winter next searched for associates to form a group that would offer a full range of periodontal treatments, including periodontal (osseous) surgery, gum grafts, dental implants, laser gum surgery and more and help pay for the expenses to run the office. Dr. Winter put an ad in the New York State Dental Journal, and within a month had met and interviewed three outstanding candidates. Rather than pick one, he selected all three who were young and eager to start periodontal practices in Manhattan, but did not have the means or opportunity do to so these tough economic times. So within three months, Dr. Winter went from considering starting a new periodontal practice to not only acquiring and readying a new office, but forming Central Park Periodontics, that will immediately impact New York City dentistry and periodontal care as it is launched on July 1, 2010.