Marilia Yatabe

Morfologia alveolar sob a perspectiva da tomografia computadorizada: definindo os limites biológicos para a movimentação dentária

Introduction: Computed tomography (CT) permits the visualization of the labial/buccal and lingual alveolar bone. Objectives: This study aimed at reporting and discussing the implications of alveolar bone morphology, visualized by means of CT, on the diagnosis and orthodontic treatment plan. Methods: Evidences of the interrelationship between dentofacial features and labial/buccal and lingual alveolar bone morphology, as well as the evidences of the effects of the orthodontic movement on the thickness and level of these periodontal structures were described. Results: Adult patients may present bone dehiscences previously to orthodontic treatment, mainly at the region of the mandibular incisors. Hyperdivergent patients seems to present a thinner thickness of the labial/buccal and lingual bone plates at the level of the root apex of permanent teeth, compared to hypodivergent patients. Buccolingual tooth movement might decentralize teeth from the alveolar bone causing bone dehiscences. Conclusion: The alveolar bone morphology constitutes a limiting factor for the orthodontic movement and should be individually considered in the

Alveolar Bone Morphology in Patients With Bilateral Complete Cleft Lip and Palate in the Mixed Dentition: Cone Beam Computed Tomography Evaluation

Objectives To verify the thickness and level of alveolar bone around the teeth adjacent to the cleft by means of cone beam computed tomography (CBCT) in patients with complete bilateral cleft lip and palate prior to bone graft surgery and orthodontic intervention. Method The sample comprised 10 patients with complete bilateral cleft lip and palate (five boys and five girls) in the mixed dentition. The mean age was 9.5 years, and all subjects showed a G3 interarch relationship according to the Bauru index. The thickness of alveolar bone surrounding the maxillary incisors and the maxillary canines was measured in CBCT axial section using the software iCAT Xoran System. The distance between the alveolar bone crest and the cement-enamel junction (CEJ) was measured in cross sections. Results The tomography images showed a thin alveolar bone plate around teeth adjacent to clefts. No bone dehiscence was observed in teeth adjacent to clefts during the mixed dentition. A slight increase in the distance between the alveolar bone crest and the CEJ was observed in the mesial and lingual aspects of canines adjacent to cleft. Conclusion In patients with BCLP in the mixed dentition, teeth adjacent to the alveolar cleft are covered by a thin alveolar bone plate. However, the level of alveolar bone crest around these teeth seems to be normal, and no bone dehiscence was identified at this age.

3D Mandibular Superimposition: Comparison of Regions of Reference for Voxel-Based Registration.

Introduction The aim was to evaluate three regions of reference (Björk, Modified Björk and mandibular Body) for mandibular registration testing them in a patients’ CBCT sample. Methods Mandibular 3D volumetric label maps were built from CBCTs taken before (T1) and after treatment (T2) in a sample of 16 growing subjects and labeled with eight landmarks. Registrations of T1 and T2 images relative to the different regions of reference were performed, and 3D surface models were generated. Seven mandibular dimensions were measured separately for each time-point (T1 and T2) in relation to a stable reference structure (lingual cortical of symphysis), and the T2-T1 differences were calculated. These differences were compared to differences measured between the superimposed T2 (generated from different regions of reference: Björk, Modified Björk and Mandibular Body) over T1 surface models. ICC and the Bland-Altman method tested the agreement of the changes obtained by nonsuperimposition measurements from the patients’ sample, and changes between the overlapped surfaces after registration using the different regions of reference. Results The Björk region of reference (or mask) did work properly only in 2 of 16 patients. Evaluating the two other masks (Modified Björk and Mandibular body) on patients’ scans registration, the concordance and agreement of the changes obtained from superimpositions (registered T2 over T1) compared to results obtained from non superimposed T1 and T2 separately, indicated that Mandibular Body mask displayed more consistent results. Conclusions The mandibular body mask (mandible without teeth, alveolar bone, rami and condyles) is a reliable reference for 3D regional registration.

Mandibular and glenoid fossa changes after bone-anchored maxillary protraction therapy in patients with UCLP: A 3-D preliminary assessment

OBJECTIVE To assess mandibular and glenoid fossa (GF) changes after bone-anchored maxillary protraction (BAMP) therapy in patients with unilateral complete cleft lip and palate (UCLP). MATERIALS AND METHODS The cleft group (CG) comprised 19 patients with (mean initial age of 11.8 years). The noncleft group (NCG) comprised 24 patients without clefts (mean initial age of 11.7 years). Both groups had Class III malocclusion and were treated with BAMP therapy for 18 and 12 months, respectively. Cone-beam computed tomography (CBCT) exams were performed before and after treatment and superimposed on the anterior cranial fossa (ACF). Mandibular rotations and three-dimensional linear displacements of the mandible and GF were quantified. A t-test corrected for multiple testing (Holm-Bonferroni method) and a paired t-test were used to compare, respectively, the CG and NCG and cleft vs noncleft sides (P < .05). RESULTS Immediately after active treatment, the GF was displaced posteriorly and laterally in both groups relative to the ACF. The overall GF changes in the CG were significantly smaller than in the NCG. Condylar displacement was similar in both groups, following a posterior and lateral direction. The gonial angle was displaced similarly posteriorly, laterally, and inferiorly in both groups. The intercondylar line rotated in opposite directions in the CG and NCG groups. In the CG, most changes of the GF and mandible were symmetrical. CONCLUSIONS Overall GF and mandibular changes after BAMP therapy were similar in patients with and without clefts. The exception was the posterior remodeling of the GF that was slightly smaller in patients with UCLP.

Diagnostic index: an open-source tool to classify TMJ OA condyles

Osteoarthritis (OA) of temporomandibular joints (TMJ) occurs in about 40% of the patients who present TMJ disorders. Despite its prevalence, OA diagnosis and treatment remain controversial since there are no clear symptoms of the disease, especially in early stages. Quantitative tools based on 3D imaging of the TMJ condyle have the potential to help characterize TMJ OA changes. The goals of the tools proposed in this study are to ultimately develop robust imaging markers for diagnosis and assessment of treatment efficacy. This work proposes to identify differences among asymptomatic controls and different clinical phenotypes of TMJ OA by means of Statistical Shape Modeling (SSM), obtained via clinical expert consensus. From three different grouping schemes (with 3, 5 and 7 groups), our best results reveal that that the majority (74.5%) of the classifications occur in agreement with the groups assigned by consensus between our clinical experts. Our findings suggest the existence of different disease-based phenotypic morphologies in TMJ OA. Our preliminary findings with statistical shape modeling based biomarkers may provide a quantitative staging of the disease. The methodology used in this study is included in an open source image analysis toolbox, to ensure reproducibility and appropriate distribution and dissemination of the solution proposed.

SVA: shape variation analyzer

Temporo-mandibular osteo arthritis (TMJ OA) is characterized by progressive cartilage degradation and subchondral bone remodeling. The causes of this pathology remain unclear. Current research efforts are concentrated in finding new biomarkers that will help us understand disease progression and ultimately improve the treatment of the disease. In this work, we present Shape Variation Analyzer (SVA), the goal is to develop a noninvasive technique to provide information about shape changes in TMJ OA. SVA uses neural networks to classify morphological variations of 3D models of the mandibular condyle. The shape features used for training include normal vectors, curvature and distances to average models of the condyles. The selected features are purely geometric and are shown to favor the classification task into 6 groups generated by consensus between two clinician experts. With this new approach, we were able to accurately classify 3D models of condyles. In this paper, we present the methods used and the results obtained with this new tool.

Bone-anchored maxillary protraction therapy in patients with unilateral complete cleft lip and palate: 3-dimensional assessment of maxillary effects

Introduction The aim of this study was to 3‐dimensionally assess the treatment outcomes of bone‐anchored maxillary protraction (BAMP) in patients with unilateral cleft lip and palate. Methods The cleft group comprised 24 patients with unilateral cleft lip and palate and Class III malocclusion with mean initial and final ages of 11.8 and 13.2 years, respectively. The noncleft group comprised 24 noncleft patients with Class III malocclusion with mean initial and final ages of 11.9 and 12.9 years, respectively. Cone‐beam computed tomography examinations were performed before and after BAMP therapy in both groups and superimposed at the cranial base. Three‐dimensional displacements of maxillary landmarks were quantified and visualized with color‐coded maps and semitransparent superimpositions. The t test corrected for multiple testing (Holm‐Bonferroni method), and the paired t test was used for statistical comparison between groups and sides, respectively (P <0.05). Results BAMP produced anterior (1.66 mm) and inferior (1.21 mm) maxillary displacements in the cleft group with no significant differences compared with the noncleft group. The maxillary first molars of the cleft group showed significantly greater medial displacement than did those in the noncleft group. The zygoma showed significantly greater lateral displacement at the cleft side compared with the noncleft side. Conclusions BAMP caused similar amounts of maxillary protraction in patients with and without unilateral cleft lip and palatem with discrete differences between the cleft side and the noncleft side. HighlightsBAMP outcomes were assessed 3‐dimensionally in patients with cleft lip and palate.BAMP caused a symmetric maxillary protraction in patients with cleft lip and palate.BAMP is a promising treatment to reduce the need for orthognathic surgery.

Ideal Versus Late Secondary Alveolar Bone Graft Surgery: A Bone-Thickness Cone-Beam Computed Tomographic Assessment

Objective: To compare the bone morphology after secondary alveolar bone graft surgery (SABG) performed before and after permanent canine eruption. Design: Cross-sectional study. Setting: Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, SP, Brazil. Patients: 25 cone-beam computed tomography (CBCT) scans of complete unilateral cleft lip and palate (CLP) individuals who underwent SABG before or after eruption of the permanent canine taken 2 and 6 months (T1 and T2) after SAGB, resulting in 50 CBCT scans. Two groups were assessed, Ideal Group (IG; n = 10) and Late Group (LG; n = 15), according to the time of the SABG. Interventions: SABG buccal-palatal thicknesses were measured in 3 different root levels: cement-enamel junction (cervical slice), middle point of the root (intermediate slice), and apex of the central incisor (apical slice). Thickness measurements were assessed in the mesial, distal, and intermediate aspects of the alveolar bone graft. Clinical long-term follow-up was also done. Results: The IG showed significantly greater bone thickness, especially in the intermediate and apical slices, when compared to LG, in T1 and T2. Bone thickness was maintained over time. Clinically, all the IG individuals completed orthodontics, and no major complications were observed. In contrast, 27% of the LG individuals had failures, and rehabilitation was achieved through prosthesis. Conclusion: Ideal SABG presents with better results compared with late ABG. When it is not possible to perform SABG at the ideal time, acceptable outcomes still can be expected for late bone grafting.

Accuracy and Reliability of Mandibular Digital Model Registration Using the Mucogingival Junction as a Reference

OBJECTIVE The aim of the study was to validate a method of mandibular digital model (DM) registration, acquired from an intraoral scanner, compared with high-resolution voxel-based cone beam computed tomography (CBCT) registration with use of the mucogingival junction as the reference. STUDY DESIGN Pre- and post-treatment CBCT and DM images from 12 adults were randomly selected from an initial sample of 40 patients who had undergone orthodontic treatment. The DM registration was performed in 6 steps: (1) construction of 3-dimensional (3-D) volumetric label maps of CBCT scans, (2) voxel-based registration of CBCT scans, (3) prelabeling of CBCT images, (4) approximation and registration of DM models to the corresponding CBCT models, (5) mucogingival-junction registration of pretreatment and post-treatment DM images, and (6) measurements. The Mann-Whitney U test was used to calculate the significance of differences between the CBCT and DM registrations. The intraclass correlation coefficient (ICC) was performed to assess reproducibility of the registration method. RESULTS When registered CBCT models and registered DM models were compared, no statistically significant differences in the measurements were found (right-left P = .267; anterior-posterior P = .238; superior-inferior P = .384; and 3-D P = .076). ICC showed excellent intra- and inter-rater correlation (ICC > 0.90). CONCLUSIONS The method of DM registration of the mandible with use of the mucogingival junction as the reference is accurate, reliable, and reproducible.

Volumetric reconstruction and determination of minimum crosssectional area of the pharynx in patients with cleft lip and palate: comparison between two different softwares

Abstract Objective: The aim of this study was to assess the accuracy of volumetric reconstruction of the pharynx by comparing the volume and minimum crosssectional area (mCSA) determined with open-source applications (ITK-Snap, www.itksnap.org ; SlicerCMF) and commercial software (Dolphin3D, 11.8, Dolphin Imaging & Management Solutions, Chatsworth, CA, USA) previously validated in the literature. Material and Methods: The sample comprised of 35 cone-beam computed tomography (CBCT) scans of patients with unilateral cleft lip and palate, with mean age of 29±15. Three-dimensional volumetric models of the pharynx were reconstructed using semi-automatic segmentation using the applications ITK-Snap (G1) and Dolphin3D (G2). Volumes and minimum cross-sectional areas were determined. Inter- and intra-observer error were calculated using ICC test. Comparison between applications was calculated using the Wilcoxon test. Results: Volumes and minimum crosssectional area were statistically similar between applications. ITK-Snap showed higher pharynx volumes, but lower mCSA. Visual assessment showed that 62.86% matched the region of mCSA in Dolphin3D and SPHARM-PDM. Conclusion: Measurements of volume and mCSA are statistically similar between applications. Therefore, open-source applications may be a viable option to assess upper airway dimensions using CBCT exams.