Analysis of the Anatomic Relationship Between the Mandibular First Molar Roots and Mandibular Canal Using Cone-Beam Computed-Tomography in 101 Dogs.

The mandibular first molar (M1) tooth of the dog is commonly involved in dental procedures. Tooth roots and the mandibular canal can vary in location, which has not been described on a large scale. The objective of this study was to describe the three-dimensional anatomic relationship of the mandibular M1 tooth roots and the mandibular canal in dogs. Cone-beam computed tomography (CBCT) was used to evaluate the anatomic relationship between the M1 tooth roots and the mandibular canal. CBCT images were collected from 101 canine cadaver heads from a variety of unknown breeds. All skulls used in this study were mesaticephalic, confirmed by facial index calculations. The position of the apex in relation to the mandibular canal and in relation to the buccal and lingual cortices was recorded and analyzed in relation to mandibular bone height: root length ratio. When evaluating the apex in a buccal-lingual relationship, the tooth roots were found to be located closer to the lingual cortex in 73.3% of M1 roots. Tooth root apical positions were found to be symmetric between the right and left side of the mouth in 93% of mesial roots and 95% of distal roots. Apical positions relative to the mandibular canal within the same tooth were found to be consistent in 52% of teeth. Teeth with roots dorsal to the mandibular canal were associated with the largest mandibular bone height: root length ratio. CBCT provides a more precise overview than dental radiographs of three-dimensional anatomy. The tooth root position can be estimated in a clinical setting based on the ratio of mandibular bone height to tooth root length obtained from intraoral radiographs. Understanding the relative location of important anatomic structures is key to avoiding complications associated with various dental procedures. This study has documented that assessing anatomic structures with 2D imaging alone is flawed, and the large majority of dogs have M1 roots closer to the lingual aspect than the buccal aspect of the mandible.

A dedicated breast-PET/CT scanner: Evaluation of basic performance characteristics.

PURPOSE: Application of advanced imaging techniques, such as PET and x ray CT, can potentially improve detection of breast cancer. Unfortunately, both modalities have challenges in the detection of some lesions. The combination of the two techniques, however, could potentially lead to an overall improvement in diagnostic breast imaging. The purpose of this investigation is to test the basic performance of a new dedicated breast-PET/CT. METHODS: The PET component consists of a rotating pair of detectors. Its performance was evaluated using the NEMA NU4-2008 protocols. The CT component utilizes a pulsed x ray source and flat panel detector mounted on the same gantry as the PET scanner. Its performance was assessed using specialized phantoms. The radiation dose to a breast during CT imaging was explored by the measurement of free-in-air kerma and air kerma measured at the center of a 16 cm-diameter PMMA cylinder. Finally, the combined capabilities of the system were demonstrated by imaging of a micro-hot-rod phantom. RESULTS: Overall, performance of the PET component is comparable to many pre-clinical and other dedicated breast-PET scanners. Its spatial resolution is 2.2 mm, 5 mm from the center of the scanner using images created with the single-sliced-filtered-backprojection algorithm. Peak NECR is 24.6 kcps; peak sensitivity is 1.36%; the scatter fraction is 27%. Spatial resolution of the CT scanner is 1.1 lp/mm at 10% MTF. The free-in-air kerma is 2.33 mGy, while the PMMA-air kerma is 1.24 mGy. Finally, combined imaging of a micro-hot-rod phantom illustrated the potential utility of the dual-modality images produced by the system. CONCLUSION: The basic performance characteristics of a new dedicated breast-PET/CT scanner are good, demonstrating that its performance is similar to current dedicated PET and CT scanners. The potential value of this system is the capability to produce combined duality-modality images that could improve detection of breast disease. The next stage in development of this system is testing with more advanced phantoms and human subjects.

American Academy of Periodontology Best Evidence Consensus Statement on Selected Oral Applications for Cone-Beam Computed Tomography.

BACKGROUND: The American Academy of Periodontology (AAP) recently embarked on a Best Evidence Consensus (BEC) model of scientific inquiry to address questions of clinical importance in periodontology for which there is insufficient evidence to arrive at a definitive conclusion. This review addresses oral indications for use of cone-beam computed tomography (CBCT). METHODS: To develop the BEC, the AAP convened a panel of experts with knowledge of CBCT and substantial experience in applying CBCT to a broad range of clinical scenarios that involve critical structures in the oral cavity. The panel examined a clinical scenario or treatment decision that would likely benefit from additional evidence and interpretation of evidence, performed a systematic review on the individual, debated the merits of published data and experiential information, developed a consensus report, and provided a clinical bottom line based on the best evidence available. RESULTS: This BEC addressed the potential value and limitations of CBCT relative to specific applications in the management of patients requiring or being considered for the following clinical therapies: 1) placement of dental implants; 2) interdisciplinary dentofacial therapy involving orthodontic tooth movement in the management of malocclusion with associated risk on the supporting periodontal tissues (namely, dentoalveolar bone); and 3) management of periodontitis. CONCLUSION: For each specific question addressed, there is a critical mass of evidence, but insufficient evidence to support broad conclusions or definitive clinical practice guidelines.

Adaptation of airline crew resource management principles to dentistry.

BACKGROUND: The aviation industry uses crew resource management (CRM) to address the human aspect of error. Dentistry can incorporate these concepts to reduce dental error. The authors provide a checklist to help clinicians mitigate error. METHODS: Health care systems have begun to focus on medical error. During the past 30 years, the airline industry has developed mitigation strategies that are being adapted for medicine. CRM involves the use of information, equipment and people to increase safety by targeting early identification of errors. RESULTS: To enhance safety, practitioners must implement forward-thinking strategies. Because human error is inevitable, threat and error management (TEM) techniques are needed to help identify and trap error before it develops into unexpected outcomes. Risk analysis increases situational awareness (SA) of potential dental error. Efficiency increases with early error detection. CONCLUSIONS: The authors provide a dental checklist that is divided into "appointment review," "before procedure," "procedure," "before dismissal" and "after dismissal" to organize dental activities in a manner that enhances error detection. PRACTICE IMPLICATIONS: The dental checklist is a tool to incorporate CRM and TEM techniques into the dental care environment to increase SA, safety and efficiency.

Biological space adaptation to implant dimensions.

PURPOSE: Implant osseointegration has been well described, but coronal osseous healing continues to be investigated because of its impact on esthetic results and long-term maintenance. Although numerous implant diameters and designs exist, little is known about the role of these parameters on surrounding bone. Therefore, this study aimed at elucidating the influence of implant dimensions on crestal bone morphology. MATERIALS AND METHODS: Sixty Biomet/3i implants (20 standard, 20 wide, and 20 expanded platform [XP]) were randomly placed in posterior quadrants of 5 mongrel dogs. After healing, exposure of the implants to the oral cavity, and euthanasia of the animals, samples were harvested. Histomorphometric measurements were performed to determine the bone cuff height, width, and angle, and analysis of variance was applied to compare groups. RESULTS: Formation of a periimplant cuff was noticed in all implant sites. Mean cuff height was 0.8 mm, 1 mm, and 1.4 mm for standard, wide, and XP implants, respectively. Mean cuff width was 1.9 mm, 2.1 mm, and 2.8 mm for standard, wide, and XP implants, respectively. These differences were statistically significant between wide and XP implants (P = .035), as well as between standard and XP implants (P = .001). Angle did not differ significantly between implants of different platform widths. CONCLUSIONS: Craterization after placement of healing abutments and a healing period was observed around all implants. Width and height of the cuff varied significantly with implant diameter and platform design, but the angle formed with the implant did not vary significantly.

Precision of flapless implant placement using real-time surgical navigation: a case series.

PURPOSE: To demonstrate the predictability of flapless surgery using navigation surgery. MATERIALS AND METHODS: Computer-generated preoperative implant planning was compared to actual placement by CT (computerized tomography) scanning of patients before and after surgery. Once pre- and postoperative coordinates of virtual implants were obtained, linear distances and angles were calculated. Coronal and apical errors consisted of the shortest distance from the preoperative planning to the postoperative overlay. RESULTS: Fourteen implants were placed in 6 patients who received CT scans before and after implant placement. Preoperative implant planning using software was compared to actual placement. The average discrepancy of the head of the implant was 0.89 mm +/- 0.53 SD (range, 0.32 to 1.96). The average discrepancy of the apex of the implant was 0.96 mm +/- 0.50 SD (range, 0.25 to 1.99). The average angle discrepancy and standard deviation were 3.78 degrees +/- 2.76 SD (range, 0.60 to 9.87). CONCLUSION: Optical computerized navigation is vulnerable to technological and technical errors. Yet, the present case series suggests that less than 1 mm of mean linear deviation and less than 4 degrees of angular deviation might be attainable.

Influence of implant diameter on surrounding bone.

OBJECTIVES: Implant osseointegration is dependent upon various factors, such as bone quality and type of implant surface. It is also subject to adaptation in response to changes in bone metabolism or transmission of masticatory forces. Understanding of long-term physiologic adjustment is critical to prevention of potential loss of osseointegration, especially because excessive occlusal forces lead to failure. To address this issue, wide-diameter implants were introduced in part with the hope that greater total implant surface would offer mechanical resistance. Yet, there is little evidence that variation in diameter translates into a different bone response in the implant vicinity. Therefore, this study aimed at comparing the impact of implant diameter on surrounding bone. MATERIAL AND METHODS: Twenty standard (3.75 mm) and 20 wide (5 mm) implants were placed using an animal model. Histomorphometry was performed to establish initial bone density (IBD), bone to implant contact (BIC) and adjacent bone density (ABD). RESULTS: BIC was 71% and 73%, whereas ABD was 65% and 52%, for standard and wide implants, respectively. These differences were not statistically different (P>0.05). Correlation with IBD was then investigated. BIC was not correlated with IBD. ABD was not correlated to IBD for standard implants (r2=0.126), but it was correlated with wide implants (r2=0.82). In addition, a 1 : 1 ratio between IBD and ABD was found for wide implants. It can be concluded, within the limits of this study, that ABD may be influenced by implant diameter, perhaps due to differences in force dissipation.

Computer-aided design/computer-aided manufacturing surgical guidance for placement of dental implants: case report.

Dental implant rehabilitation faces increasing prosthetic and esthetic demands, requiring precise surgical planning and placement. Presurgical treatment evaluation can now be accomplished using 3-dimensional computed tomography imaging. Although software has been developed to assist in implant selection and localization, transferring this information to the surgical field has remained a difficult task. Over the last few years, computer-aided design and manufacturing have made it possible to use data from computed tomography in order to transfer virtual implant placement to the surgery. One of these techniques utilizes a small computer-driven drilling mechanism that transfers implant planning on a laboratory model. This novel approach may be advantageous once available in dental laboratories and/or offices. This report presents the method and, for the first time, illustrates it with a fully edentulous advanced clinical case. Resulting clinical benefits over traditional procedures are discussed.

Periapical surgery using CAD/CAM guidance: preclinical results.

Apicoectomy is a surgical procedure requiring precise planning and access to locate apices and avoid vital anatomic structures. Traditional methods limit treatment because they rely on two-dimensional radiography and corrective actions during surgery. Surgical guidance, which uses computed tomography and computer-aided design and computer-aided manufacturing processing, has been utilized in dentistry, but not in endodontics. Therefore, the aim of this study was to introduce periapical surgical guidance using computed tomography and computer-aided design and computer-aided manufacturing surgical guides and to compare apical access accuracy using guidance versus a conventional method. Results showed that distance from the apex was 0.79 mm (+/-0.33 SD) using guidance and 2.27 mm (+/-1.46 SD) using freehand drilling. An error greater than 3 mm occurred over 22% of the time freehand, yet never occurred with guidance. This in vitro study suggests that greater accuracy and consistency can be achieved during endodontic surgery with surgical guidance. Advantages also include presurgical visualization in three dimensions.

Effect of rhPDGF-BB delivery on mediators of periodontal wound repair.

Growth factors such as platelet-derived growth factor (PDGF) exert potent effects on wound healing including the regeneration of tooth-supporting structures. This investigation examined the effect of the local delivery of PDGF-BB when combined with reconstructive periodontal surgery on local wound fluid (WF) levels of PDGF-AB, vascular endothelial growth factor (VEGF), and bone collagen telopeptide (ICTP) in humans with advanced periodontitis. Sixteen patients exhibiting localized periodontal osseous defects were randomized to one of three groups (beta-TCP carrier alone, beta-TCP + 0.3 mg/mL of recombinant human PDGF-BB [rhPDGF-BB], or beta-TCP + 1.0 mg/mL of rhPDGF-BB) and monitored for 6 months. WF was harvested and analyzed for PDGF-AB, VEGF, and ICTP WF levels. Teeth contralateral to the target lesions served as controls. Increased levels of VEGF in the WF was observed for all surgical treatment groups with the 1.0 mg/mL rhPDGF-BB group showing the most pronounced difference at 3 weeks in the AUC analysis versus control (p < 0.0001). PDGF-AB WF levels were increased for the carrier alone group compared to both rhPDGFBB groups. Low-dose rhPDGF-BB application elicited increases in ICTP at days 3-5 in the wound healing process, suggesting a promotion of bone turnover at early stages of the repair process (p < 0.02). These results demonstrate contrasting inducible expression patterns of PDGF-AB, VEGF, and ICTP during periodontal wound healing in humans.

Advanced surgical guidance technology: a review.

To maximize the outcome of implant placement, the use of advanced radiographic procedures such as computerized tomography, along with fabrication of surgical guides, has been advocated to inform surgeons of ideal implant location. More recently, simulation computer software has been introduced to view radiographic images and test potential implant locations. Yet, surgical guides are processed based on ideal tooth position, with little consideration for underlying anatomical limitations, which creates a disconnection between diagnostic planning and surgical restrictions. In response to this "missing link," computer-assisted design and computer-assisted manufacturing, as well as real-time surgical navigation were recently developed to obtain fully integrated surgical and prosthetic planning. Today, there are several technologies available, but, to our knowledge, a systematic assessment of surgical guidance has not yet been performed. Therefore, the aims of this review are to introduce advanced radiographic and software modalities, and present a detailed assessment of computer-assisted design and computer-assisted manufacturing methods and surgical navigation.

Accuracy of cone beam computed tomography for periodontal defect measurements.

BACKGROUND: Periodontal diagnosis relies heavily on traditional two-dimensional radiographic assessment. Despite efforts in improving reliability, current methods of detecting bone level changes over time or determining three-dimensional architecture of osseous defects are inadequate. To address these issues, computed tomography (CT) has been explored because of its ability to produce accurate three-dimensional imaging, but limitations such as radiation, machine size, and cost have made this approach impractical. Recently, cone beam computed tomography (CBCT) has turned this concept into potential reality because these lower-cost small machines produce high-quality data. Yet there is little research to establish periodontal bone measurement using CBCT as a valid method. Therefore, the aim of this study was to compare CBCT measurements of periodontal defects to traditional methods. METHODS: Artificial osseous defects were created on mandibles of dry skulls. CBCT scanning, periapical radiography (PA), and direct measurements using a periodontal probe were compared to an electronic caliper that was used as a standard reference. RESULTS: Linear measurements for all defects revealed no statistical differences between bone sounding, radiography, and CBCT. There was a significant difference when comparing isolated interproximal measurements using a probe versus the caliper (P<0.001) but no significant difference for CBCT or radiography. All bony defects were identifiable and measurable directly or with CBCT. In comparison, buccal and lingual defects could not be measured with radiographs. CONCLUSIONS: Overall, all three modalities are useful for identifying interproximal periodontal defects. Compared to radiographs, the three-dimensional capability of CBCT offers a significant advantage because all defects can be detected and quantified.

Effect of rhPDGF-BB on bone turnover during periodontal repair.

PURPOSE: Growth factors such as platelet-derived growth factor (PDGF) exert potent effects on wound healing including the regeneration of periodontia. Pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) is a well-known biomarker of bone turnover, and as such is a potential indicator of osseous metabolic activity. The objective of this study was to evaluate the release of the ICTP into the periodontal wound fluid (WF) following periodontal reconstructive surgery using local delivery of highly purified recombinant human PDGF (rhPDGF)-BB. METHODS: Forty-seven human subjects at five treatment centres possessing chronic severe periodontal disease were monitored longitudinally for 24 weeks following PDGF regenerative surgical treatment. Severe periodontal osseous defects were divided into one of three groups and treated at the time of surgery with either: beta-tricalcium phosphate (TCP) osteoconductive scaffold alone (active control), beta-TCP+0.3 mg/ml of rhPDGF-BB, or beta-TCP+1.0 mg/ml of rhPDGF-BB. WF was harvested and analysed for local ICTP levels by radioimmunoassay. Statistical analysis was performed using analysis of variance and an area under the curve analysis (AUC). RESULTS: The 0.3 and 1.0 mg/ml PDGF-BB treatment groups demonstrated increases in the amount of ICTP released locally for up to 6 weeks. There were statistically significant differences at the week 6 time point between beta-TCP carrier alone group versus 0.3 mg/ml PDGF-BB group (p<0.05) and between beta-TCP alone versus the 1.0 mg/ml PDGF-BB-treated lesions (p<0.03). The AUC analysis revealed no statistical differences amongst groups. CONCLUSION: This study corroborates the release of ICTP as a measure of active bone turnover following local delivery of PDGF-BB to periodontal osseous defects. The amount of ICTP released from the WF revealed an early increase for all treatment groups. Data from this study suggests that when PDGF-BB is delivered to promote periodontal tissue engineering of tooth-supporting osseous defects, there is a direct effect on ICTP released from the wound.

Variation in periodontal diagnosis and treatment planning among clinical instructors.

Consistency in clinical decision making may be necessary for reliable assessment of student performance and teaching effectiveness, yet little has been done to examine variation in periodontal diagnosis and treatment planning among dental school faculty. The purpose of this investigation was to examine variation among faculty in diagnosis and management of common periodontal diseases. Twenty-seven clinical instructors (periodontists, general dentists, dental hygienists, and first- and second-year periodontal graduate students) reviewed three web-based cases and answered a brief questionnaire focusing on radiographic interpretation, periodontal diagnosis, and treatment planning. Response rates for the three cases ranged from 62 percent to 70 percent. Clinical instructors' rating of percent bone loss in the majority of cases varied between three descriptive categories for the same tooth. Greater consistency in periodontal diagnosis was noted within the graduate student group as compared to periodontal and dental hygiene faculty groups. Diagnoses offered for one of the three patients varied between gingivitis and chronic and aggressive periodontitis. Six to nineteen different treatment plans (many with subtle differences) were submitted for each of the three cases. Inter-rater variation was qualitatively more prevalent than intra-rater variation. To our knowledge, this is the first study to document substantial variation among instructors in radiographic interpretation, diagnosis, and treatment planning for common periodontal diseases. Qualitative judgments speculating on the impact of variability among dental school faculty on student performance and patient care can be made but as yet remain unknown. Consistent use of accepted practice guidelines and greater consensus-building opportunities may decrease variation among faculty and enhance dental education.

Implant plastic surgery: a review and rationale.

Implant dentistry has been established as a predictable treatment modality with high clinical success rates. Esthetic considerations of implant restorations have been gaining increased interest over the years. The role of periodontal plastic surgical procedures in the creation and maintenance of peri-implant soft tissue heights to facilitate better esthetics has become more popular. The available plastic surgery procedures and their clinical applications are reviewed in this article. Emphasis is placed on factors to consider for proper case selection and ideal treatment planning.

Guided tissue regeneration-based root coverage: meta-analysis.

BACKGROUND: The goal of guided tissue regeneration-based root coverage (GTRC) is to repair gingival recession via new attachment formation. Numerous clinical trials have been conducted utilizing the concept of GTR to promote root coverage. Most GTRC studies have had relatively small sample sizes and have not utilized power calculations to determine appropriate sample size; therefore, it is difficult to draw strong conclusions from them. Hence, the purpose of this study is to combine data from currently available GTRC studies and to use meta-analysis to determine whether GTRC provides significantly improved clinical outcomes compared to conventional periodontal plastic surgical approaches for the treatment of marginal tissue recession. METHODS: Studies were identified that used GTR approaches to treat gingival recession from January 1990 to October 2001. Information from each study was entered into a database. Data were analyzed according to the following criteria: GTRC versus conventional mucogingival surgery (CMGS); membrane type; root conditioning; pretreatment recession depth; adjunctive use of bone replacement graft (BRG); and source of funding. Studies were ranked independently, and mean data from each were weighted accordingly. Meta-analysis was performed using the weighted means for each group. Paired t tests were used to determine statistical significance between each pair of groups. RESULTS: Forty papers were included for analysis. GTRC resulted in an average of 74% recession depth reduction, 41% complete root coverage, 3 mm AL gain, and 1 mm KG gain. Both GTRC and CMGS produced significant (P < 0.05) improvement compared to baseline measurements. Compared to GTRC, CMGS resulted in significantly (P < 0.05) increased KG (2.1 mm vs. 1.1 mm), root coverage (81% vs. 74%), and percentage of defects with complete root coverage (55% vs. 41 %). Use of absorbable membranes, root conditioning, shallow pretreatment recession (< 4 mm), and corporate sponsorship all resulted in significantly (P < 0.05) improved percentages of sites with complete root coverage but had no effect on other parameters. CONCLUSIONS: Based on this meta-analysis, guided tissue regeneration-based root coverage can be used successfully to repair gingival recession defects. Conventional mucogingival surgery, however, resulted in statistically better root coverage, width of keratinized gingiva, and complete root coverage.

Accuracy of implant placement with a stereolithographic surgical guide.

PURPOSE: Placement of dental implants requires precise planning that accounts for anatomic limitations and restorative goals. Diagnosis can be made with the assistance of computerized tomographic (CT) scanning, but transfer of planning to the surgical field is limited. Recently, novel CAD/CAM techniques such as stereolithographic rapid prototyping have been developed to build surgical guides in an attempt to improve precision of implant placement. However, comparison of these advanced techniques to traditional surgical guides has not been performed. The goal of this study was to compare the accuracy of a conventional surgical guide to that of a stereolithographic surgical guide. MATERIALS AND METHODS: CT scanning of epoxy edentulous mandibles was performed using a cone beam CT scanner with high isotropic spatial resolution, while planning for 5 implants on each side of the jaw was performed using a commercially available software package. Five surgeons performed osteotomies on a jaw identical to the initial model; on the right side a conventional surgical guide (control side) was used, and on the left side a stereolithographic guide was used (test side). Each jaw was then CT scanned, and a registration method was applied to match it to the initial planning. Measurements included distances between planned implants and actual osteotomies. RESULTS: The average distance between the planned implant and the actual osteotomy was 1.5 mm at the entrance and 2.1 mm at the apex when the control guide was used. The same measurements were significantly reduced to 0.9 mm and 1.0 mm when the test guide was used. Variations were also reduced with the test guide, within surgeons and between surgeons. DISCUSSION: Surgical guidance for implant placement relieves the clinician from multiple perioperative decisions. Precise implant placement is under investigation using sophisticated guidance methods, including CAD/CAM templates. CONCLUSION: Within the limits of this study, implant placement was improved by using a stereolithographic surgical guide.

Stereolithographic surgical templates for placement of dental implants in complex cases.

In recent years, dental implant rehabilitation has faced demands from prosthetic and esthetic arenas that call for increasingly ideal outcomes, which require precise surgical planning and placement. Anatomic limitations and bone quantity and quality can now be evaluated using more sophisticated radiographic techniques, although transferring this information to the surgical phase has been at best a difficult task. Recently, computer-aided design and manufacturing have made it possible to use data from computerized tomography to not only plan implant rehabilitation, but also to transfer this information to the surgery. One of these techniques uses stereolithography, a laser-driven polymerization process that fabricates an anatomic model and surgical templates. This novel approach is illustrated with two advanced cases, demonstrating that the technique not only allows for the precise translation of the treatment plan directly to the surgical field, but also offers many significant benefits over traditional procedures.

Guidelines for periodontal prostheses serve esthetic and functional demands: a case report.

Periodontal-prosthesis guidelines have long been defined to specifically address dental reconstructions after moderate to advanced periodontal disease has occurred. More recently, specific dental techniques and materials have shown promise in addressing patients' increasing esthetic demands. However, treatment planning to achieve pleasing results for patients with advanced periodontitis requires a complex, multispecialty approach that is rarely discussed. A case report and literature review illustrate that the original periodontal-prosthesis guidelines not only remain useful today for obtaining esthetic results but also conform to recent understanding of maxillomandibular physiology.