Quantitative bone imaging biomarkers to diagnose temporomandibular joint osteoarthritis.

Bone degradation of the condylar surface is seen in temporomandibular joint osteoarthritis (TMJ OA); however, the initial changes occur in the subchondral bone. This cross-sectional study was performed to evaluate 23 subchondral bone imaging biomarkers for TMJ OA. The sample consisted of high-resolution cone beam computed tomography scans of 84 subjects, divided into two groups: TMJ OA (45 patients with TMJ OA) and control (39 asymptomatic subjects). Six regions of each mandibular condyle scan were extracted for computation of five bone morphometric and 18 grey-level texture-based variables. The groups were compared using the Mann-Whitney U-test, and the receiver operating characteristics (ROC) curve was determined for each variable that showed a statically significance difference. The results showed statistically significant differences in the subchondral bone microstructure in the lateral and central condylar regions between the control and TMJ OA groups (P< 0.05). The area under the ROC curve (AUC) for these variables was between 0.620 and 0.710. In conclusion, 13 imaging bone biomarkers presented an acceptable diagnostic performance for the diagnosis of TMJ OA, indicating that the texture and geometry of the subchondral bone microarchitecture may be useful for quantitative grading of the disease.

Three-dimensional analysis of condylar changes in surgical correction for open bite patients with skeletal class II and class III malocclusions.

The aim of this study was to quantify three-dimensional condylar displacements as a result of two-jaw surgery for open bite correction in patients with skeletal class II and class III malocclusion. Pre-surgical (T1) and post-surgical (T2) cone beam computed tomography scans were taken for 16 patients with skeletal class II (mean age 22.3±9.47years) and 14 patients with skeletal class III (mean age 25.6±6.27years). T2 scans were registered to T1 scans at the cranial base. Translational and rotational condylar changes were calculated by x,y,z coordinates of corresponding landmarks. The directions and amounts of condylar displacement were assessed by intra- and inter-class Mann-Whitney U-test or t-test. Class II patients presented significantly greater amounts of lateral (P=0.002) and inferior (P=0.038) translation than class III patients. The magnitudes of condylar translational displacements were small for both groups. Skeletal class III patients had predominantly medial (P=0.024) and superior (P=0.047) condylar translation. Skeletal class II patients presented greater condylar counterclockwise pitch (P=0.007) than class III patients. Two-jaw surgery for the correction of open bite led to different directions and amounts of condylar rotational displacement in patients with skeletal class II compared to class III malocclusion, with greater rotational than translational displacements.

Soft tissue assessment before and after mandibular advancement or setback surgery using three-dimensional images: systematic review and meta-analysis.

The aim of this systematic review was to evaluate the effects of mandibular advancement or setback surgery on the facial soft tissue assessed using three-dimensional images. An electronic search was performed in the MEDLINE, Cochrane Library, Scopus, Virtual Health Library (VHL), Web of Science, and OpenGrey databases. Inclusion criteria comprised studies that evaluated the soft tissues of adult patients before and after mandibular advancement or setback surgery using computed tomography or magnetic resonance imaging. The risk of bias was analyzed. A total of 3501 studies were retrieved. The titles and abstracts of 2071 studies were read and 2040 of them were excluded. Thirty-one articles were read in full and six fulfilled the eligibility criteria and were included. A meta-analysis was performed using three of these articles. The correlation was significant and strong in the chin area (r=0.876 and r=0.868) and moderate for the lower lip/lower incisor (r=0.690). The ratio for lower lip/infradentale was 78% and for Pog'/Pog was 98%. Due to the limited number of articles included, there is weak evidence to infer that changes in the facial soft tissue due to mandibular advancement or setback are significant, but changes in the lower lip tend to be smaller than changes in the chin area.

Counterclockwise maxillomandibular advancement surgery and disc repositioning: can condylar remodeling in the long-term follow-up be predicted?

This study investigated predictive risk factors of condylar remodeling changes after counterclockwise maxillomandibular advancement (CCW-MMA) and disc repositioning surgery. Forty-one female patients (75 condyles) treated with CCW-MMA and disc repositioning had cone beam computed tomography (CBCT) scans taken pre-surgery, immediately after surgery, and at an average 16 months post-surgery. Pre- and post-surgical three-dimensional models were superimposed using automated voxel-based registration on the cranial base to evaluate condylar displacements after surgery. Regional registration was performed to assess condylar remodeling in the follow-up period. Three-dimensional cephalometrics, shape correspondence (SPHARM-PDM), and volume measurements were applied to quantify changes. Pearson product-moment correlations and multiple regression analysis were performed. Highly statistically significant correlation showed that older patients were more susceptible to overall condylar volume reduction following CCW-MMA and disc repositioning (P≤0.001). Weak but statistically significant correlations were observed between condylar remodeling changes in the follow-up period and pre-surgical facial characteristics, magnitude of the surgical procedure, and condylar displacement changes. After CCW-MMA and disc repositioning, the condyles moved mostly downwards and medially, and were rotated medially and counterclockwise; displacements in the opposite direction were correlated with a greater risk of condylar resorption. Moreover, positional changes with surgery were only weakly associated with remodeling in the follow-up period, suggesting that other risk factors may play a role in condylar resorption.

Zygomaticomaxillary suture maturation: Part II-The influence of sutural maturation on the response to maxillary protraction.

OBJECTIVE: To evaluate the influence of the maturational stages of zygomaticomaxillary sutures (ZMS) on the response to maxillary protraction. SUBJECTS AND METHODS: A total of 40 Class III patients were treated retrospectively with either a combination of rapid maxillary expansion and facial mask (RME/FM) or bone-anchored maxillary protraction (BAMP). The RME/FM group consisted of 18 patients (mean age 8.3 years), while the BAMP group was comprised of 22 patients (mean age 11.8 years). The initial CBCT images (T1) of the ZMSs were classified blindly. 3D models from CBCT images at the start and at the end of orthopaedic treatment were registered on the anterior cranial base, and corresponding structures were measured on colour-coded maps and semitransparent overlays. The amounts of protraction of the maxilla, zygoma, orbitale and maxillary first molars for both groups were analysed with two-way ANOVA with Holm-Sidak post hoc test for multiple comparisons. RESULTS: A significant association was found between the early maturation stages of the ZMSs and the amount of maxillary protraction, regardless of the protraction method used. Class III patients with ZMS stages A and B showed greater maxillary protraction than patients at stage C. CONCLUSION: The maturational stages of ZMS are associated with the response maxillary protraction.

Three-dimensional skeletal mandibular changes associated with Herbst appliance treatment.

OBJECTIVES: Three-dimensional evaluation of skeletal mandibular changes following Herbst appliance treatment. SETTING AND SAMPLE POPULATION: Retrospective case-control study, based on a sample size calculation. Twenty-five pubertal patients treated with Herbst appliance (HAG), and 25 matched Class II patients who received other non-orthopaedic dental treatments (CG). MATERIAL AND METHODS: Three-dimensional models were generated from pre-treatment (T0) and post-treatment (T1) cone beam computed tomograms. Volumetric registration on the cranial base was used to assess mandibular displacement; volumetric regional registration was performed to evaluate mandibular growth. Quantitative measurements of X, Y, Z and 3D Euclidian changes, and also qualitative visualization by colour-mapping and semi-transparent overlays were obtained. RESULTS: Downward displacement of the mandible was observed in both HAG and CG (2.4 mm and 1.5 mm, respectively). Significant forward displacement of the mandible was observed in the HAG (1.7 mm). HAG showed greater 3D superior and posterior condylar growth than the CG (3.5 mm and 2.0 mm, respectively). Greater posterior growth of the ramus was noted in the HAG than in CG. CONCLUSIONS: Immediately after Herbst therapy, a significant mandibular forward displacement was achieved, due to increased bone remodelling of the condyles and rami compared to a comparison group. Three-dimensional changes in the direction and magnitude of condylar growth were observed in Herbst patients.

Three-dimensional regional displacement after surgical-orthodontic correction of Class III malocclusion.

OBJECTIVES: To investigate how displacements of maxillo-mandibular structures are associated with each other at splint removal and 1 year post-surgery following 1-jaw and 2-jaw surgeries for correction of Class III malocclusion. SETTING AND SAMPLE POPULATION: Fifty patients who underwent surgical correction with maxillary advancement only (n = 25) or combined with mandibular setback (n = 25) were prospectively enrolled in this study. METHODS: Cone-beam computed tomographies were taken pre-surgery, at splint removal and at 1 year post-surgery. Three-dimensional cranial base superimpositions and shape correspondence were used to measure the outcomes from pre-surgery to splint removal (surgical changes) and splint removal to 1 year post-surgery (post-surgical adaptations). Pearson's correlation coefficients were used to evaluate the association between the regional displacements. RESULTS: Both surgery groups presented mandibular clockwise rotation with surgery and post-surgical adaptive counterclockwise rotation. In patients treated with maxillary advancement only, the surgical changes of the maxilla were significantly correlated with chin changes. The amount and direction of chin autorotation were significantly correlated with right and left ramus autorotation. Right and left condylar displacements were significantly correlated. One year post-surgery, adaptive displacements and bone remodeling of both rami were correlated with the chin and condylar changes. For the 2-jaw group, the few correlations between the positional and remodeling changes in the anatomic regions of interest observed due to the surgery were different than those observed after post-surgical adaptations, suggesting that these changes occurred independently. CONCLUSION: Our results indicate that surgical displacements and post-surgical adaptations are often correlated in one-jaw surgery and are, in general, independent in two-jaw surgery.

3D superimposition and understanding temporomandibular joint arthritis.

OBJECTIVES: To investigate the 3D morphological variations in 169 temporomandibular ioint (TMJ) condyles, using novel imaging statistical modeling approaches. SETTING AND SAMPLE POPULATION: The Department of Orthodontics and Pediatric Dentistry at the University of Michigan. Cone beam CT scans were acquired from 69 subjects with long-term TMJ osteoarthritis (OA, mean age 39.1±15.7 years), 15 subjects at initial consult diagnosis of OA (mean age 44.9±14.8 years), and seven healthy controls (mean age 43±12.4 years). MATERIALS AND METHODS: 3D surface models of the condyles were constructed, and homologous correspondent points on each model were established. The statistical framework included Direction-Projection-Permutation (DiProPerm) for testing statistical significance of the differences between healthy controls and the OA groups determined by clinical and radiographic diagnoses. RESULTS: Condylar morphology in OA and healthy subjects varied widely with categorization from mild to severe bone degeneration or overgrowth. DiProPerm statistics supported a significant difference between the healthy control group and the initial diagnosis of OA group (t=6.6, empirical p-value=0.006) and between healthy and long-term diagnosis of OA group (t=7.2, empirical p-value=0). Compared with healthy controls, the average condyle in OA subjects was significantly smaller in all dimensions, except its anterior surface, even in subjects with initial diagnosis of OA. CONCLUSION: This new statistical modeling of condylar morphology allows the development of more targeted classifications of this condition than previously possible.

One-year assessment of surgical outcomes in Class III patients using cone beam computed tomography.

The purpose of this study was to apply a novel method to evaluate surgical outcomes at 1 year after orthognathic surgery for Class III patients undergoing two different surgical protocols. Fifty patients divided equally into two groups (maxillary advancement only and combined with mandibular setback) had cone beam computed tomography (CBCT) scans taken pre-surgery, at splint removal, and at 1-year post-surgery. An automatic cranial base superimposition method was used to register, and shape correspondence was applied to assess, the overall changes between pre-surgery and splint removal (surgical changes) and between splint removal and 1-year post-surgery at the end of orthodontic treatment (post-surgical adaptations). Post-surgical maxillary adaptations were exactly the same for both groups, with 52% of the patients having changes >2mm. Approximately half of the post-surgical changes in the maxilla for both groups were vertical. The two-jaw group showed significantly greater surgical and post-surgical changes in the ramus, chin, and most of the condylar surfaces (P<0.05). Post-surgical adaptation on the anterior part of the chin was also more significant in the two-jaw group (P<0.05). Regardless of the type of surgery, marked post-surgical adaptations were observed in the regions evaluated, which explain the adequate maxillary-mandibular relationship at 1-year post-surgery on average, with individual variability.

Evaluation of pharyngeal airway space amongst different skeletal patterns.

The aim of the present study was to evaluate the dimensions of the pharyngeal airway space (PAS) in awake, upright children with different anteroposterior skeletal patterns using cone beam computed tomography (CBCT). The volume, area, minimum axial area and seven linear measurements of PAS were obtained from the CBCT images of 50 children (mean age 9.16 years). The patients were divided in two groups according to the ANB angle (group I 2° ≤ ANB ≤ 5°; group II ANB > 5°). Means and standard deviations of each variable were compared and correlated using independent t-test and Pearson's correlation test. There were statistically significant differences in the following parameters: angle formed by the intersection between NA and NB lines (p<0.001), angle formed by the intersection between SN and NB lines (p<0.05), Minimal pharyngeal airway space between the uvula and the posterior pharyngeal wall (p<0.05), airway volume (p<0.01), airway area (p<0.01) and minimum axial area (p<0.05). The anteroposterior cephalometric variable SNB had positive correlation with the variables PAS-UP (p<0.01), Minimal pharyngeal airway space between the uvula tip and the posterior pharyngeal wall (p<0.05), Pharyngeal airway space on mandibular line (p<0.05), Minimal pharyngeal airway space between the back of the tongue and the posterior pharyngeal wall (p<0.05), volume airway (p<0.05), airway area (p<0.05) and minimum axial area (p<0.05). The vertical cephalometric variables angle formed by the intersection between SN and GoGn lines (p<0.05) and angle formed by the intersection between FH and mandible plane (p<0.05) showed negative correlation with PAS-UT. These results showed that PAS was statistically larger in group I than group II, indicating that the dimensions of the PAS are affected by different anteroposterior skeletal patterns.

Effects of orthognathic surgery on oropharyngeal airway: a meta-analysis.

Oropharyngeal changes caused by orthognathic surgery have been a concern because the sleep quality of patients may be enhanced or worsened by these changes. The purpose of this meta-analysis was to identify, review and compare scientific literature about changes in airway in adult patients undergoing orthognathic surgery to correct anteroposterior osseous discrepancies. An electronic search of four databases was carried out up to July 2010, with supplemental hand searching of the references of the retrieved articles. Quality assessment of the included articles was carried out. Data were extracted and a meta-analysis was performed. Heterogeneity was assessed amongst the studies and results were presented in forest plots. 49 studies met the inclusion criteria. Only studies with moderate or high methodological soundness were included in the review. Moderate evidence was found to support a significant decrease in the oropharyngeal airway in mandibular setback surgery, a milder decrease in bimaxillary surgery to correct Class III and an increase in maxillomandibular advancement surgery. Evidence is lacking on airway volume changes after orthognathic surgery.

Evaluation of the cytotoxicity of latex and non-latex orthodontic separating elastics.

OBJECTIVE: To test the hypothesis that a difference in cytotoxicity exists between latex and non-latex orthodontic separating elastics. MATERIAL AND METHODS: Five intra-oral separating elastics from different manufactures (four latex and one non-latex) were divided into five groups of 15 elastics each: Group MA (non-latex elastics, Masel), Group MO (natural latex, Morelli), Group DE (natural latex, Dentaurum), Group TP (natural latex, TP Orthodontics) and Group UN (natural latex, Unitek). The cytotoxicity assay was performed using cell cultures (epithelial HEp-2 cells originating from human laryngeal carcinoma) that were submitted to the cell viability test with neutral red (dye-uptake) at 24, 48, 72 and 168 h. Analysis of variance (anova) with multiple comparisons and Tukey's test were employed (p < 0.05). RESULTS: The results showed no statistically significant differences between groups MA, DE, TP and UN in relation to Group CC (cell control) for experimental times of 24, 48 and 168 h (p > 0.05). Morelli, Dentaurum, TP Orthodontics and Unitek elastics induced a great amount of cell lyses at 72 h. CONCLUSION: One can demonstrate that the Masel elastic induced less cell lysis compared with other elastics, but all trademarks were found to be clinically biocompatible. CLINICAL RELEVANCE: Separating orthodontic elastics are used in the interdental subgingival region with the aim to separate the teeth for placement of orthodontic bands. However, latex has been known to cause allergy. As these materials are widely used in clinical orthodontics, care regarding the cytotoxicity of orthodontic elastics should be taken. Thus, clinically proven biocompatible materials should be acquired whenever possible.