Optimizing the use of panoramic radiography for determining the position of impacted permanent maxillary canines.

The purpose of this research was to test the reliability of a modified magnification method for determining the position of an impacted canine from a single panoramic radiograph. This retrospective study evaluated 114 panoramic radiographs showing 136 impacted maxillary canines. The widths of the impacted canines, contralateral erupted canines, and ipsilateral maxillary incisors were measured, and ratios for the canine-incisor index (CII) and canine-canine index (CCI) were calculated. The impacted canines were also classified according to their location in the vertical plane (apical, middle, or coronal zone) relative to the contralateral central incisor. Continuous data were analyzed for normal distribution, and logistic and multivariate logistic regression models were conducted. The Benjamini-Hochberg procedure with a false discovery rate of 0.05 was used to account for multiple testing. The intrarater reliability was excellent for impacted canine, central incisor, and contralateral canine measurements (intraclass correlation coefficient > 0.9). The CII and vertical zone were strong predictors of an impacted canine position with clinically useful sensitivity and specificity values (0.69 and 0.74, respectively, based on an area under the curve concordance statistic of 0.75). A predictive range was evident for the CII of palatally (1.10-1.39) and buccally (0.90-1.19) impacted canines in the middle and coronal zones, respectively. The occurrence of palatal or buccal positioning was not significantly associated with the CCI (P = 0.2). The CII and vertical zone identified from a single panoramic radiograph can be used to determine the buccopalatal position of an impacted canine, with more reliability if the impacted canine crown is in the middle or coronal zone of the contralateral central incisor.

Compensations in Bone Morphology and the Dentition in Patients With Untreated Unilateral Cleft Lip and Palate: A Cone-Beam Computed Tomographic Analysis.

OBJECTIVE: The purpose of this study was to quantitatively assess dentoalveolar and skeletal compensations in patients with untreated unilateral cleft lip and palate (UCLP). We hypothesized that there are significant skeletal and dental adaptations in UCLP cases compared to a comparison maxillary crossbite group. DESIGN: A convenience retrospective sample of 30 patients with UCLP and a comparison group of 30 patients with unilateral posterior crossbite without CLP. Cone-beam computed tomography scans (CBCTs) were used to evaluate dental and skeletal compensations. In addition, alveolar bone thickness was measured at 2-mm increments in mesiodistal and faciolingual cross-sectional views along the long axis of the central incisors. Alveolar bone height was measured, and the percentage of root length supported by bone was calculated. RESULTS: Compensations for unilateral cleft lip and palate were restricted to the cleft site and adjacent structures. Dental compensations include alteration in the position of cleft-adjacent maxillary incisors and maxillary canines. No gross skeletal compensations were found. Alveolar support of cleft adjacent incisors was similar to controls except for measurements in the most coronal and apical regions. The cleft group contralateral incisors exhibited buttressing effects and had significantly higher alveolar thickness in the coronal half of the tooth. There was less (5%) alveolar coverage of the cleft-facing aspect of the central incisor root than all other incisors. CONCLUSION: The bone adaptation to the presence of a cleft was localized in the vicinity of the cleft, and adaptations in the mandible were not apparent.

Dental school application timing: implications for full admission consideration and improving diversity of dental students.

The national underrepresentation of minorities in dental schools and the dental profession is a significant concern. Despite efforts over previous years, the number of practicing dentists from underrepresented minority (URM) groups has increased very little. Many dental schools have adopted a holistic admissions review process that uses noncognitive factors in an effort to increase diversity. However, application timing also significantly impacts the success of candidates. This study examined whether URM students' applying late in the application cycle contributes to their lower enrollment. This study attempted to fill a void in the dental admissions knowledge base by examining whether the timing of dental school applications in a rolling admissions system with a set number of interview spots favors those who apply early. De-identified applications (N=1,673) from one U.S. dental school in 2011 were examined. A binary logistic regression analysis revealed that URM applicants were significantly more likely to apply later in the admission cycle than non-URM applicants by a factor of 63 percent (p=0.001), increasing the competiveness for fewer remaining spots. These results suggest the need for pre-admission interventions and for future research to understand and address barriers that impact application timing.

Temporary anchorage device insertion variables: effects on retention.

OBJECTIVE: To quantify the influence of temporary anchorage device (TAD) insertion variables on implant retention. MATERIALS AND METHODS: Three hundred thirty TADs from three companies were placed in synthetic bone replicas at variable depths and angulations and compared. Clinically relevant forces were applied to the TADs until failure of retention occurred. RESULTS: In all three implants, increased insertion depth increased implant retention. As the distance from the abutment head to the cortical plate increased, the retention of all three implants decreased. A significantly greater force to fail was required for a 90 degrees insertion angle than for 45 degrees or 135 degrees insertion angles. No significant difference was found between the 45 degrees and 135 degrees insertion angles. A significant reduction in force to fail occurred when comparing 90 degrees and 45 degrees oblique insertion angles. CONCLUSIONS: Increasing penetration depth of TADs results in greater retention. Increased abutment head distance from cortical plate leads to decreased retention. Placement of TADs at 90 degrees to the cortical plate is the most retentive insertion angle. Insertion at an oblique angle from the line of force reduces retention of TADs.

The essential work of fracture of thermoplastic orthodontic retainer materials.

OBJECTIVE: To investigate whether oral cleansing agents affect the essential work of fracture (EWF) and plastic work of fracture (PWF) for two types of orthodontic thermoplastic retainer materials. MATERIALS AND METHODS: Polyethylene-terephthalate-glycol (PETG; Tru-Tain Splint) and polypropylene/ethylene-propylene rubber (PP-EPR) blend (Essix-C+) sheets were compared. For each material, six sets of 25 sheets were thermoformed into double-edge-notched-tension specimens; subsets of five specimens were formed with internotch distances (L) equal to 6, 8, 10, 12, or 14 mm, respectively. Sets were stored (160 hours, 25 degrees C) in air (DRY), distilled water (DW), Original Listerine (LIS), mint Crest ProHealth (CPH), 3% hydrogen peroxide (HP), or Polident solution (POL). Specimens were fractured in tension at 2.54 mm/min. Areas under load-elongation curves were measured to determine total work of fracture (W(f)). Linear regressions (W(f) vs L [n = 25]) yielded intercepts (EWF) and slopes (PWF). Ninety-five percent confidence intervals were used to evaluate differences in EWF and PWF estimates. RESULTS: PP-EPR blends showed higher EWFs after storage in HP vs storage in DW. PP-EPR blend showed higher EWFs after storage in CPH vs PETG. After HP storage, PP-EPR exhibited lower PWFs than with any other storage conditions. PP-EPR exhibited higher PWFs than PETG after storage in DRY, DW, and LIS. CONCLUSIONS: Compared with DW, none of the cleansers decreased the energy to initiate fracture. With one exception, no cleanser decreased the energy to continue plastic fracture extension. In PP-EPR blend, increased resistance to fracture initiation was observed with CPH and HP, yet, surprisingly, HP decreased resistance to plastic fracture growth.

Evaluation of orthodontic mini-implant anchorage in premolar extraction therapy in adolescents.

INTRODUCTION: The purpose of this study was to determine the success rate, positional stability, and patient evaluation of orthodontic mini-implants (OMIs). METHODS: Thirteen patients (8 girls, 5 boys; average age, 14 years 10 months) were treated with 82 OMIs measuring 1.6 mm in diameter and 6 mm in length placed in the buccal alveoli (1 unloaded OMI and 1 loaded OMI per quadrant). The right or left side of each arch was randomly selected for immediate loading with up to 250 g of direct force; the contralateral side was loaded 3 to 5 weeks later. Serial impressions, clinical observations, and orthodontic maintenance were performed until adequate space closure was achieved. RESULTS: The overall OMI success rate was 70.73%. As calculated with a mixed-model analysis, there was no statistically significant difference between the success rates of immediately loaded OMIs (80.0%) and delayed loaded OMIs (80.95%). The combined success rate for loaded OMIs (80.49%) was significantly higher than that of unloaded OMIs (60.98%). Patients' motivation for OMI treatment was primarily the desire to avoid headgear. Using a 100-mm visual analog scale, the patients indicated average scores of 54.77 for the amount of pain during OMI placement and 27.10 for the amount of pain during OMI removal. CONCLUSIONS: OMIs are a predictable, effective, and well-tolerated anchorage source for adolescents. Neither the timing of force application nor the force itself precipitated failure of the OMIs. Orthodontic forces can be applied immediately to OMIs. Various anatomic and behavioral conditions unique to adolescents and a clinical learning curve can affect the success rate of OMIs.

Hypodontia as a risk marker for epithelial ovarian cancer: a case-controlled study.

BACKGROUND: Genetic mutations that result in hypodontia also may be associated with abnormalities in other parts of the body. The authors conducted a study to establish the prevalence rates of hypodontia among subjects with epithelial ovarian cancer (EOC) and control subjects to explore possible genetic associations between these two phenotypes. METHODS: The authors recruited 50 subjects with EOC and 100 control subjects who did not have EOC. The authors performed a dental examination on each subject to detect hypodontia, and they reviewed pertinent radiographs and dental histories. They also recorded any family history of cancer and hypodontia. RESULTS: The prevalence of hypodontia was 20 percent for EOC subjects and 3 percent for control subjects. The difference between these two hypodontia rates was significant. This difference implied that women with EOC are 8.1 times more likely to have hypodontia than are women without EOC. The severity of hypodontia was similar between the two groups, with one to two teeth being affected. Maxillary lateral incisors followed by second premolars were the most frequently affected teeth. CONCLUSION: The preliminary data suggest a statistical association between hypodontia of the permanent dentition and EOC. CLINICAL IMPLICATIONS: Genetic analysis of the genes of interest is necessary to explore similarities between hypodontia and EOC further. An association could allow hypodontia to serve as a potential risk marker for EOC.

Undergraduate basic science preparation for dental school.

In the Institute of Medicines report Dental Education at the Crossroads, it was suggested that dental schools across the country move toward integrated basic science education for dental and medical students in their curricula. To do so, dental school admission requirements and recommendations must be closely reviewed to ensure that students are adequately prepared for this coursework. The purpose of our study was twofold: 1) to identify student dentists' perceptions of their predental preparation as it relates to course content, and 2) to track student dentists' undergraduate basic science course preparation and relate that to DAT performance, basic science course performance in dental school, and Part I and Part II National Board performance. In the first part of the research, a total of ninety student dentists (forty-five from each class) from the entering classes of 1996 and 1997 were asked to respond to a survey. The survey instrument was distributed to each class of students after each completed the largest basic science class given in their second-year curriculum. The survey investigated the area of undergraduate major, a checklist of courses completed in their undergraduate preparation, the relevance of the undergraduate classes to the block basic science courses, and the strength of requiring or recommending the listed undergraduate courses as a part of admission to dental school. Results of the survey, using frequency analysis, indicate that students felt that the following classes should be required, not recommended, for admission to dental school: Microbiology 70 percent, Biochemistry 54.4 percent, Immunology 57.78 percent, Anatomy 50 percent, Physiology 58.89 percent, and Cell Biology 50 percent. The second part of the research involved anonymously tracking undergraduate basic science preparation of the same students with DAT scores, the grade received in a representative large basic science course, and Part I and Part II National Board performance. Using T-test analysis correlations, results indicate that having completed multiple undergraduate basic science courses (as reported by AADSAS BCP hours) did not significantly (p < .05) enhance student performance in any of these parameters. Based on these results, we conclude that student dentists with undergraduate preparation in science and nonscience majors can successfully negotiate the dental school curriculum, even though the students themselves would increase admission requirements to include more basic science courses than commonly required. Basically, the students' recommendations for required undergraduate basic science courses would replicate the standard basic science coursework found in most dental schools: anatomy, histology, biochemistry, microbiology, physiology, and immunology plus the universal foundation course of biology.