Dental wear proxy correlation in a long-term feeding experiment on sheep ( Ovis aries )

Dietary reconstruction in vertebrates often relies on dental wear-based proxies. Although these proxies are widely applied, the contributions of physical and mechanical processes leading to meso- and microwear are still unclear. We tested their correlation using sheep ( Ovis aries , n = 39) fed diets of varying abrasiveness for 17 months as a model. Volumetric crown tissue loss, mesowear change and dental microwear texture analysis (DMTA) were all applied to the same teeth. We hereby correlate: (i) 46 DMTA parameters with each other, for the maxillary molars (M1, M2, M3), and the second mandibular molar (m2); (ii) 10 mesowear variables to each other and to DMTA for M1, M2, M3 and m2; and (iii) volumetric crown tissue loss to mesowear and DMTA for M2. As expected, many DMTA parameters correlated strongly with each other, supporting the application of reduced parameter sets in future studies. Correlation results showed only few DMTA parameters correlated with volumetric tissue change and even less so with mesowear variables, with no correlation between mesowear and volumetric tissue change. These findings caution against interpreting DMTA and mesowear patterns in terms of actual tissue removal until these dental wear processes can be better understood at microscopic and macroscopic levels.

Effect of Le Fort I Maxillary Advancement and Clockwise Rotation on the Anteromedial Cheek Soft Tissue Change in Patients with Skeletal Class III Pattern and Midface Deficiency: A 3D Imaging-Based Prediction Study

Patients with a skeletal Class III deformity may present with a concave contour of the anteromedial cheek region. Le Fort I maxillary advancement and rotational movements correct the problem but information on the impact on the anteromedial cheek soft tissue change has been insufficient to date. This three-dimensional (3D) imaging-assisted study assessed the effect of surgical maxillary advancement and clockwise rotational movements on the anteromedial cheek soft tissue change. Two-week preoperative and 6-month postoperative cone-beam computed tomography scans were obtained from 48 consecutive patients who received 3D-guided two-jaw orthognathic surgery for the correction of Class III malocclusion associated with a midface deficiency and concave facial profile. Postoperative 3D facial bone and soft tissue models were superimposed on the corresponding preoperative models. The region of interest at the anteromedial cheek area was defined. The 3D cheek volumetric change (mm3; postoperative minus preoperative models) and the preoperative surface area (mm2) were computed to estimate the average sagittal movement (mm). The 3D cheek mass position from orthognathic surgery-treated patients was compared with published 3D normative data. Surgical maxillary advancement (all p < 0.001) and maxillary rotation (all p < 0.006) had a significant effect on the 3D anteromedial cheek soft tissue change. In total, 78.9%, 78.8%, and 78.8% of the variation in the cheek soft tissue sagittal movement was explained by the variation in the maxillary advancement and rotation movements for the right, left, and total cheek regions, respectively. The multiple linear regression models defined ratio values (relationship) between the 3D cheek soft tissue sagittal movement and maxillary bone advancement and rotational movements of 0.627 and 0.070, respectively. Maxillary advancements of 3–4 mm and >4 mm resulted in a 3D cheek mass position (1.91 ± 0.53 mm and 2.36 ± 0.72 mm, respectively) similar (all p > 0.05) to the 3D norm value (2.15 ± 1.2 mm). This study showed that both Le Fort I maxillary advancement and rotational movements affect the anteromedial cheek soft tissue change, with the maxillary advancement movement presenting a larger effect on the cheek soft tissue movement than the maxillary rotational movement. These findings can be applied in future multidisciplinary-based decision-making processes for planning and executing orthognathic surgery.

Use of CBCT Guidance for Tooth Autotransplantation in Children

Tooth autotransplantation (TAT) offers a viable biological approach to tooth replacement in children and adolescents. The aim of this study was to evaluate the outcome of the cone-beam computed tomographic (CBCT)–guided TAT compared to the conventional TAT protocol and to assess the 3-dimensional (3D) patterns of healing after CBCT-guided TAT (secondary aim). This study included 100 autotransplanted teeth in 88 patients. Each experimental group consisted of 50 transplants in 44 patients (31 males and 19 females). The mean (SD) age at the time of surgery was 10.7 (1.1) y for the CBCT-guided group. This was 10.6 (1.3) y for the conventional group. The mean (SD) follow-up period was 4.5 (3.1) y (range, 1.1 to 10.4 y). Overall survival rate for the CBCT-guided TAT was 92% with a success rate of 86% compared to an 84% survival rate and a 78% success rate for the conventional group ( P > 0.005). The following measurements were extracted from the 3D analysis: root hard tissue volume (RV), root length (RL), apical foramen area (AFA), and mean and maximum dentin wall thickness (DWT). Overall, the mean (SD) percentage of tissue change was as follows: RV gain by 65.8% (34.6%), RL gain by 37.3% (31.5%), AFA reduction by 91.1% (14.9%), mean DWT increase by 107.9% (67.7%), and maximum DWT increase by 26.5% (40.1%). Principal component analysis (PCA) identified the mean DWT, RV, and maximum DWT as the parameters best describing the tissue change after TAT. Cluster analysis applied to the variables chosen by the PCA classified the CBCT group into 4 distinct clusters (C1 = 37.2%, C2 = 17.1%, C3 = 28.6%, C4 = 17.1%), revealing different patterns of tissue healing after TAT. The CBCT-guided approach increased the predictability of the treatment. The 3D analysis provided insights into the patterns of healing. CBCT-guided TAT could be adopted as an alternative for the conventional approach. (Clinical trial center and ethical board University Hospitals, KU Leuven: S55287; ClinicalTrials.gov Identifier: NCT02464202)