Facial morphology differences in monozygotic twins: a retrospective stereophotogrammetric study.

OBJECTIVE: To assess soft tissue differences between monozygotic twins (MZ) for the total face and between facial regions using three-dimensional (3D) stereophotogrammetry and quantitative surface-based 3D deviation analyses. MATERIALS AND METHODS: The study sample consisted of 14 untreated MZ twins (6 males, 8 females, mean age: 14.75 years) from the archive of Marmara University, Department of Orthodontics. The images were taken by the 3dMDface system, and 3dMDvultus software was used for removal of undesired areas and approximation of the images. Then, stereolithography (.stl) format images were superimposed using the best-fit algorithm using 3-matic software. The face was divided into facial thirds, and upper lip and lower lip + chin regions were created. For the comparison, 3D deviation analyses were performed, and a color map and histogram were created. The data were presented as mean deviation, root mean square (RMS), median, and interquartile range. RESULTS: Between the facial thirds, there was no significant difference in soft tissue differences for mean deviation. A statistically significant difference was found between the upper and lower face for the RMS value. For the comparison of upper lip and lower lip + chin region, the only significant difference was for the RMS. When the data were presented as median and interquartile range, there were no statistically significant differences between any facial regions. CONCLUSIONS: Lower facial third and lower lip + chin regions had the greatest differences within MZ twin pairs. The genetic and environmental influences might not be the same for different parts of the face.

Soft tissue evaluation after maxillary protraction with RPE or with the ALT-RAMEC protocol : A controlled 3D study.

PURPOSE: To evaluate soft tissue changes following maxillary protraction with different expansion protocols using three-dimensional (3D) stereophotogrammetry. METHODS: Pretreatment (T0) and postprotraction (T1) stereophotogrammetry and lateral cephalometric images of skeletal class III patients were included in this retrospective study. In all, 32 patients were treated either with a combination of rapid palatal expansion and facemask (RPE/FM; n = 16; mean age: 9.94 ± 0.68 years) or with alternate rapid maxillary expansion and constriction together with a facemask (Alt-RAMEC/FM; n = 16; mean age: 9.74 ± 1.35 years). As a control group 16 untreated patients were recruited (mean age: 9.46 ± 0.8 years). For superimpositioning of the 3D images taken at T0 and T1, the face was divided into defined regions and 3D and differences between the groups were evaluated using 3­matic software (Materialise Europe, Leuven, Belgium). Cephalometric analyses were also performed. RESULTS: While the increases in the cephalometric parameters SNA and ANB were significantly greater in the treatment groups, the value for SNB also increased in the control group (p < 0.05). The results of the stereophotogrammetry analyses demonstrated that the mean changes in the RPE/FM and in the Alt-RAMEC/FM groups were significantly different for the midface compared to the control group (0.33 ± 0.26 mm, 0.3 ± 0.31 mm, 0.1 ± 0.18 mm). The maximum positive, negative, and mean changes were also significantly different between the treatment and control groups for the upper lip (p < 0.05). For the lower lip and the chin significant backward movements in the RPE/FM as well as in the Alt-RAMEC/FM group (-1.06 ± 1.26 mm, -0.68 ± 0.45 mm) were observed, while the control group (0.09 ± 0.53 mm) presented changes in the opposite direction. Regarding soft tissue changes, no significant differences were found between the RPE/FM and Alt-RAMEC/FM groups. CONCLUSION: Both treatment protocols improved the soft tissue profile due to a forward movement of the midface and the upper lip, and a backward movement of the lower lip and chin, compared to the control group.

Changes in the condylar head after orthognathic surgery in Class III patients: a retrospective three-dimensional study.

OBJECTIVES: To evaluate the axial and dimensional changes of the condylar head after orthognathic surgery, including Le Fort I and bilateral sagittal split ramus osteotomies, and to assess condylar remodeling through three-dimensional (3D) surface superimposition. MATERIALS AND METHODS: Twenty-four patients (15 females, 9 males; mean age: 32.22 ± 6.92 years) with skeletal Class III deformity were included in the study. Cone-beam computed tomography data obtained in the preoperative (T0) and postoperative (T1) periods were examined using Mimics and 3-Matic software. The height, depth, and width of the condylar head and its angular changes were measured. The volumes of the 3D reconstructed models were calculated, and remodeling amounts were evaluated through regional surface superimposition. Statistical significance was set at P < .05. RESULTS: Following the surgery, there was a significant decrease in the size of condyles (P < .05). An inward rotation of the condyles was found in the axial plane (T0: 79.60 ± 6.01°, T1: 76.6 ± 6.48°, P < .05). The maximum resorption, maximum apposition, mean remodeling, and mean absolute remodeling were -2.63 ± 1.23 mm, 1.15 ± 0.4 mm, -0.30 ± 0.34 mm, and 0.73 ± 0.43 mm, respectively. No correlation was found between the angular changes and remodeling parameters or linear and volumetric changes of the condylar head (P > .05). CONCLUSIONS: Condyles undergo a remodeling process with a resorptive character following orthognathic surgery, without clinically significant effects in the present study.

Tongue pressure changes before, during and after crib appliance therapy.

OBJECTIVE: To describe tongue pressure changes before, during, and after crib appliance therapy in mixed dentition open bite cases. MATERIALS AND METHODS: A crib appliance was applied to each of the 13 patients in the study group. The control group consisted of six patients. Tongue pressures were measured using a diaphragm-type pressure transducer during rest position and swallowing in changing intervals for 12 months in both groups. Tongue pressures were performed on the upper first molar, upper and lower central incisors, and on the middle spur of the crib appliance. RESULTS: In the study group, the initial resting tongue pressure on the upper molar increased after appliance insertion and was followed by a decreasing trend for 12 months. The resting tongue pressures on the upper and lower incisors remained lower than initial values at the end of 12 months. Swallowing pressures returned to initial values at the end of 12 months, and the changes were insignificant. The resting and swallowing tongue pressures on the middle spur of the crib appliance decreased gradually during the 10 months (P < .05). Pressure changes in the control group were insignificant for all measurements. Open bite values in the study group increased significantly by the end of 12 months. CONCLUSIONS: Measurements performed on the crib confirm the tongue adaptation to environmental changes. Resting tongue pressures at the 12th month remained lower than the initial values. These findings indicate adaptive behavior of the tongue to open bite closure and the new position of the incisors.