Evaluating the effects of functional orthodontic treatment on mandibular osseous structure using fractal dimension analysis of dental panoramic radiographs.

OBJECTIVE: To evaluate the effects of functional appliance treatment on mandibular trabecular structure using fractal dimension (FD) analysis of dental panoramic radiographs. MATERIALS AND METHODS: This study was conducted using digital panoramic radiographs of 45 patients with Class II malocclusion treated with functional appliances (treatment group, mean age: 11.39 ± 0.97 years; 23 girls, 22 boys) acquired before (T0) and after (T1) treatment and the panoramic radiographs of 45 control subjects who had undergone no orthodontic treatment (control group, mean age: 11.31 ± 0.87 years; 23 girls, 22 boys). FD values in the condylar process, mandibular corpus, and mandibular angle were analyzed from the panoramic radiographs of both groups. RESULTS: Analysis of changes in FD between T0 and T1 revealed significant increases in the FD values of the right and left condylar processes and right mandibular corpus in the treatment group (P < .001) and in the right condylar process in the control group (P < .05). Between-group comparisons demonstrated that the treatment group showed greater changes in the condylar process (right, P < .001; left, P < .05) and right mandibular corpus (P < .05) compared to controls. Correlation analysis between the cephalometric and FD changes in the treatment group showed the right condylar process changes were negatively correlated with GoGn/SN angle (P < .05) and positively correlated with Co-Go (P < .05), although these correlations were weak. CONCLUSIONS: FD analysis demonstrated significant changes in trabeculation of the condyle and mandibular corpus in the treatment group compared to the control group. Functional appliance treatment may lead to skeletal correction by altering skeletal form and trabeculation of the mandibular bone.

Evaluation of Maxillofacial Characteristics in Individuals with Anterior Open Bite Using Denture Frame Analysis.

KEYWORDS: The aim of this study was to evaluate the effectiveness of denture frame analysis (DFA) in individuals with anterior open bite who had completed pubertal peak growth (post-peak). METHODS: This retrospective study was conducted using the cephalometric radiographs and hand-wrist X-rays of 50 individuals with open bite (mean age: 17.33±3 years; 35 female, 15 male) and a control group of 50 individuals without open bite (mean age: 17.38±2.72; 35 female, 15 male). All individuals included in the study were skeletal Class I and had completed or nearly completed skeletal growth. Skeletal and dental measurements pertaining to DFA were done and the data were analyzed using independent samples t test and Mann-Whitney U test. RESULTS: Measurements assessing the vertical dimension showed that GoGn/SN, Frankfurt horizontal (FH)/mandibular plane (MP), palatal plane (PP)/MP, occlusal plane (OP)/MP, and OP-MP/PP-MP measurements were significantly greater in the open bite group (p<0.001). AB/MP angle was significantly larger in the control group (p<0.05). The open bite group had shorter A'-P' (posterior maxillary length; p<0.05) and, therefore, higher A'-6'/A'-P' ratio (p<0.01). CONCLUSION: Our results suggest that there may be a close association between maxillary OP inclination and mandibular position in individuals with open bite, and that open bite may arise due to maxillary denture base deficiency, especially in the posterior region. DFA may be useful in the differential diagnosis of open bite and in treatment planning, particularly when determining the need for tooth extraction.

Effects of wear time differences of removable functional appliances in class II patients: prospective MRI study of TMJ and masticatory muscle changes.

OBJECTIVES: The aim of this prospective study was to evaluate the short-term effects of full-time and night-time wear of functional appliances on the temporomandibular joint (TMJ) and masticatory muscles and to compare the differences in craniofacial structures, TMJ, and masticatory muscles with magnetic resonance imaging (MRI). METHODS: The study was carried out using cephalometric radiographs and MRI of 20 Class II patients who were treated with monoblock/twin-block appliances. The patients were divided into 2 groups: ten patients in Group 1 used their appliances all day, while ten patients in Group 2 were instructed to wear the appliances during sleep. After at least 6 months of uninterrupted treatment, post-treatment cephalograms and MRI were obtained for patients whose molar relationship improved by at least a half cusp width. Signal intensity ratios (SIR) of TMJ structures and morphological evaluations of masticatory muscles were done for all patients. RESULTS: It was found a significant increase in SIR values of the condylar process, articular disc, retrodiscal tissue, and masticatory muscles for all treatment groups. Length of the masseter and medial pterygoid muscles increased to varying degrees which left side of Group 2 was significantly increased (P < 0.05). The volume of all muscles also increased to varying degrees. CONCLUSIONS: The cephalometric and MRI findings of this study show that the treatment effects were similar for both wear schedules.

Evaluation of temporomandibular joint, masticatory muscle, and brain cortex activity in patients treated by removable functional appliances: a prospective fMRI study.

OBJECTIVES: The aim of this study is to evaluate the effects of functional orthodontic appliances on the masticatory muscles, temporomandibular joint (TMJ), and brain to determine whether using functional appliances full-time or only at night yields different results. METHODS: 16 patients with Class II malocclusion were included in this study. Eight patients were instructed to wear their appliances (monoblock/twinblock) full-time and the other eight patients were instructed to wear them at night while sleeping. An additional 10 patients with Class II malocclusion were later included as a pre-treatment control group. Signal intensity ratios (SIR) of TMJ structures and morphological evaluations of the masticatory muscles were done for all patients. Functional MRI (fMRI) data were also obtained from the patients while performing chewing and biting movements. RESULTS: ANB angle was reduced significantly in both the full-time and night wear groups, by values of 1.17° and 1.35°, respectively (p < 0.05). MRI showed that SIRs were significantly increased in both groups in the masticatory muscles, retrodiscal pad, condylar process, and articular disc (p < 0.05). Both resting and task-based fMRI evaluation revealed significant increases in blood oxygen level dependent signals in several regions of the brain in both groups (p < 0.05). CONCLUSIONS: The cephalometric and MRI findings of this study indicate that the treatment effects were similar for both wear schedules. Functional appliances should be regarded not as simple devices that treat Class II malocclusion through skeletal and dental correction alone, but as exercise devices that lead to neuromuscular changes by facilitating muscle adaptation and activating various brain regions.

Investigation of natural head posture in different head types.

The aim of this study was to investigate natural head posture (NHP) in different head types. Lateral cephalograms of 99 adults (Mean age, 21.8 years +/- SD, 2.2 yrs, range between 19 and 29 yrs) were examined. Head types were determined as Hyperbrachycephal, Brachycephal, Mesocephal or Dolichocephal according to the cephalic index. Analysis of variance and the Duncan's test were performed to assess inter-group differences for the parameters. The findings revealed that, NHP was statistically not different between the head type groups. Thus, it was suggested that environmental factors during growth may alter NHP, as well as craniofacial morphology but in a different manner (i.e. degree and direction) in each head type.