Evaluation of tooth position, occlusion, and interproximal contacts after transplantation of immature third molars

The aim of the present investigation was to examine position, occlusion, and interproximal contacts of 139 transplanted third molars in 136 patients (94 females, 42 males) with a mean age of 17.6 years at the time of transplantation. Ninety-two teeth were placed directly into favourable positions and left to erupt spontaneously. Forty-seven teeth were transplanted into atrophied jaw sections and underwent post-operative orthodontic adjustment. According to the post-operative treatment performed, the sample was divided into two groups: transplants with or without subsequent orthodontic treatment. The mean post-operative observation time was 4.4 years. Study models were obtained from all patients and the American Board of Orthodontics Objective Grading System was adapted for evaluation of position, occlusion, and interproximal contacts of the transplanted teeth. A Mann-Whitney U-test was used to determine significant intergroup differences with respect to the final scores and the various evaluated criteria. Absence of occlusal contacts was found in more than 30 per cent, absence of both interproximal contacts in more than 15 per cent, and inadequate position in more than 40 per cent of the transplants without subsequent orthodontic treatment. The poorest results were observed for maxillary teeth transplanted into the mandible. The results of the present study show that incorrect positioning with absence of occlusal and interproximal contacts are frequent findings in transplanted teeth. Short-term orthodontic adjustment, especially of maxillary transplants into the mandible, seems to be advisable in order to obtain correct positioning and function of these teet

A novel method for assessment of human midpalatal sutures using CBCT-based geometric morphometrics and complexity scores

Introduction: Management of dentofacial deficiencies requires knowledge about sutural morphology and complexity. The present study assesses midpalatal sutural morphology based on human cone-beam computed tomography (CBCT) using geometric morphometrics (GMM) and complexity scores. The study is the first to apply a sutural complexity score to human CBCT datasets and demonstrates the potential such a score has to improve objectiveness and comparability when analysing the midpalatal suture. Materials and methods: CBCTs of various age and sex groups were analysed retrospectively (n = 48). For the geometric morphometric analysis, landmark acquisition and generalised Procrustes superimposition were combined with principal component analysis to detect variability in sutural shape patterns. For complexity analysis, a windowed short-time Fourier transform with a power spectrum density (PSD) calculation was applied to resampled superimposed semi-landmarks. Results: According to the GMM, younger patients exhibited comparable sutural patterns. With increasing age, the shape variation increased among the samples. The principal components did not sufficiently capture complexity patterns, so an additional methodology was applied to assess characteristics such as sutural interdigitation. According to the complexity analysis, the average PSD complexity score was 1.465 (standard deviation = 0.010). Suture complexity increased with patient age (p < 0.0001), but was not influenced by sex (p = 0.588). The intra-class correlation coefficient exceeded 0.9, indicating intra-rater reliability. Conclusion: Our study demonstrated that GMM applied to human CBCTs can reveal shape variations and allow the comparison of sutural morphologies across samples. We demonstrate that complexity scores can be applied to study human sutures captured in CBCTs and complement GMM for a comprehensive sutural analysis

Root development of immature third molars transplanted to surgically created sockets

PURPOSE: The aim of this study was to compare root development after transplantation of teeth into surgically created sockets or into fresh extraction sites. PATIENTS AND METHODS: The sample consisted of 62 patients with a total of 64 transplanted immature third molars. All transplants were at root development stages 3 to 4. In 22 cases, a new socket was created by means of burs. Forty-two teeth transplanted into a fresh extraction site served as controls. Postoperative root development was determined on intraoral radiographs taken immediately after transplantation and at the final follow-up. For all transplants, extraoral storage time and number of trials were recorded during transplantation. RESULTS: No significant intergroup differences were observed at root development stage 3. In contrast, at root development stage 4 transplantations to surgically created sockets showed a significantly lower final root length (P =.025) and root length increment (P =.038) than transplants in the control group. In addition, a significant correlation was determined in the prepared socket group at developmental stage 4 between root length increment and extraoral storage time (r = -0.910, r(2) = 0.828, P <.001) or number of trials in the recipient socket (r = -0.775, r(2) = 0.601, P <.001). CONCLUSIONS: Teeth at advanced developmental stages transplanted to surgically created sockets show an impaired postoperative root development. A possible explanation might be damage of Hertwig's epithelial root sheath during the transplantation procedure

Changes in incisor third-order inclination resulting from vertical variation in lingual bracket placement

Objective: To test the null hypothesis that third-order measurements are not correlated to lingual incisor features seen on radiographs. Material and Methods: The lateral headfilms of 38 untreated, norm-occlusion subjects without incisor abrasions or restorations were used for third-order measurements of upper and lower central incisors and assessment of the inclination of four sites suitable for lingual bracket placement with reference to the occlusal plane perpendicular. Lingual sections were determined by the tangents at the incisal fossa (S1), at the transition plateau between incisal fossa and the cingulum (S2), by a constructed line reaching from the incisal tip to the cingulum (S3), and by a tangent at the cingulum convexity (S4). Third-order angles were also assessed on corresponding dental casts using an incisor inclination gauge. Regression analysis was performed using the third-order measurements of both methods as the dependent variables and the inclination of the lingual enamel sections (S1, S2, S3, S4) as the independent variables. Results: The null hypothesis was rejected. For the most common bracket application sites located on the lingual shovel (S1 and S2), third-order inclination changes of 0.4-0.7 degrees are expected for each degree of change in the inclination of the lingual surface. The impact of bracket placement errors on third-order angulation is similar between sections S1 and S2 and the cingulum convexity (S4). Section S3 proved to be least affected by interindividual variation. Conclusion: The third-order measurements are correlated to lingual incisor features. Accordingly, third-order changes resulting from variation in lingual bracket placement can be individually predicted from radiographic assessments