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.

Scleral exposure changes after Le Fort I maxillary advancement with vertical component in individuals with skeletal Class III malocclusion-A stereophotogrammetric image study.

OBJECTIVE: This retrospective study aimed to evaluate inferior scleral exposure changes in Class III patients that underwent orthognathic surgery with Le Fort I osteotomy with and without vertical displacement. MATERIALS AND METHODS: Preoperative and 6 months postoperative cephalograms and stereophotogrammetric images of 45 subjects (mean age: 21.66 ± 2.97 years) who underwent orthognathic surgery for Class III correction were retrieved. Subjects were divided into 3 groups: maxillary advancement-only (AO), maxillary advancement + impaction (AI) and maxillary advancement + downfracture (AD). Exclusion criteria were mandibular-only surgery, occlusal canting, facial asymmetry, orbital surgery and craniofacial syndrome. One investigator measured inferior scleral exposure on both sides using following landmarks: upper eyelid margin (A), inferior limbus (B) and lower eyelid margin (C). Distance between A and C was recorded as overall eye height (E), and distance between B and C was recorded as inferior sclera exposure (S). S:E ratio in percentage was calculated to standardize sclera exposure relative to overall eye height. Wilcoxon signed-rank and Kruskal-Wallis tests were used for statistical analysis (P < .05). RESULTS: Mean value of maxillary movements was as follows: 4.21 ± 1.82 mm advancement in AO, 5.08 ± 2.18 mm advancement and 2.33 ± 0.99 mm impaction in AI, 3.95 ± 1.45 mm advancement and 3.1 ± 0.71 mm downfracture in AD. Change in reduction of scleral exposure was significant in all groups (P < .05). AI group bilaterally and AO group right side had highest differences (-4.96 ± 4.86, -6.09 ± 4.21, -4.99 ± 3.23, respectively). There was no significant difference between groups in S:E ratio changes (P > .05). CONCLUSION: Intergroup comparisons showed no statistically significant difference, revealing similar reduction in all three groups despite the differences in the vertical movement variable.

Assessment of the Diagnostic Skills of General Dentists in Different Types of Orthodontic Malocclusions.

OBJECTIVE: One of the biggest problems in publicly funded dental clinics is the patient waiting list. The appropriate referral plays a key role in avoiding an increase in the number of patients on this waiting list. This study aimed to assess general dentists' diagnostic skills and approaches for different malocclusions. METHODS: A questionnaire was prepared using photos of 8 patients previously treated for different malocclusions. One hundred twenty general dentists (83 female, mean age: 24 ± 1.18 years; 37 male, mean age: 24 ± 1.95 years) participated in the survey and were asked to decide whether the patient needed orthodontic treatment or orthognathic surgery, and to provide the reason for surgery (irregular teeth, or both unesthetic profile and irregular teeth), and the cause of the unesthetic profile (mandibular protrusion, mandibular retrusion, maxillary protrusion, maxillary retrusion). RESULTS: The answers suggesting the need for orthodontic treatment were significantly higher for all malocclusions except for the Class II camouflage case. Of the Class III cases, the general dentists chose orthognathic surgery for both surgery and facemask cases (93.1%, 66.4% respectively). For the severe open bite case, orthognathic surgery was chosen with a ratio of 81.2%, and orthognathic surgery was decided as not necessary for the mild open bite case (74.8%). Among the surgery cases, mandibular retrusion for the Class II case (94.6%), mandibular protrusion for Class III case (95.4%), and maxillary retrusion for the severe open bite case (44.6%) were the maximum reported reasons. CONCLUSION: The distinction between camouflage and surgical treatment was better made by dentists in Class II and open bite cases than in Class III cases.

Comparison of the effects of rapid maxillary expansion and alternate rapid maxillary expansion and constriction protocols followed by facemask therapy.

OBJECTIVE: The aim of this retrospective study was to evaluate and compare the changes in the pharyngeal airway (PA), maxillary sinus volume, and skeletal parameters after rapid maxillary expansion (RME) and alternate rapid maxillary expansion and constriction (Alt-RAMEC) followed by facemask (FM) therapy. METHODS: The records of 40 patients with skeletal Class III malocclusion due to maxillary retrognathism were collected, and the patients were assigned into two groups. The first group comprised 8 male and 12 female patients (mean age, 10.0 ± 1.1 years) treated using RME/FM for an average of 10 months. The second group comprised 10 male and 10 female patients (mean age, 9.64 ± 1.3 years) treated using Alt-RAMEC/FM for an average of 12 months. Cone-beam computed tomography images acquired before (T0) and after treatment (T1) were evaluated. RESULTS: Regarding the skeletal effects, significant differences between the groups were the increase in ANS-HRP (perpendicular distance of ANS to the horizontal reference plane, 0.99 mm, p <0.05) in the Alt-RAMEC/FM group and the decrease in PP-SN (palatal plane to Sella-Nasion plane, 0.93°, p < 0.05) in the RME/FM group. Maxillary sinus volumes increased significantly in both the groups, and the increase was statistically significantly higher in the Alt-RAMEC/FM group. Although no significant intergroup differences were observed in PA volumes, both lower (1,011.19 mm3) and total (1,601.21 mm3), PA volume increased significantly in the Alt-RAMEC/FM group. CONCLUSIONS: The different expansion devices and protocols used with FM therapy do not seem to affect the forward movement of the maxilla and PA volumes. In contrast, the increase in maxillary sinus volume was greater in the Alt-RAMEC/FM protocol.