ObjectivesTo test the applicability, accuracy, precision, and reproducibility of various 3D superimposition techniques for radiographic data, transformed to triangulated surface data.MethodsFive superimposition techniques (3P: three-point registration; AC: anterior cranial base; AC + F: anterior cranial base + foramen magnum; BZ: both zygomatic arches; 1Z: one zygomatic arch) were tested using eight pairs of pre-existing CT data (pre- and post-treatment). These were obtained from non-growing orthodontic patients treated with rapid maxillary expansion. All datasets were superimposed by three operators independently, who repeated the whole procedure one month later. Accuracy was assessed by the distance (D) between superimposed datasets on three form-stable anatomical areas, located on the anterior cranial base and the foramen magnum. Precision and reproducibility were assessed using the distances between models at four specific landmarks. Non parametric multivariate models and Bland-Altman difference plots were used for analyses.ResultsThere was no difference among operators or between time points on the accuracy of each superimposition technique (p>0.05). The AC + F technique was the most accurate (D<0.17 mm), as expected, followed by AC and BZ superimpositions that presented similar level of accuracy (D<0.5 mm). 3P and 1Z were the least accurate superimpositions (0.790.05), the detected structural changes differed significantly between different techniques (p<0.05). Bland-Altman difference plots showed that BZ superimposition was comparable to AC, though it presented slightly higher random error.ConclusionsSuperimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities. In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.

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Conventional dental-borne rapid maxillary expansion (RME) leads to a widening of the airways, followed by improved nasal breathing. Although combined skeletal-dental appliances are nowadays being inserted increasingly often and provide a force at the center of resistance in the nasomaxillary complex, no study exists so far that shows whether this treatment may improve the expansionary effect on the airways. In this study, low-dose computed tomography (CT) images from 31 patients (average age 14.63 ± 0.38 years) were examined retrospectively. Both records (T0 = before expansion and T1 = immediately after maximum expansion) were taken in a time interval of 25 days to avoid growth influence. Five patients were treated with Hyrax RME, 6 patients with Hybrid RME, and 20 patients with acrylic cap RME. The total airway volume increased highly significantly (mean +7272.6 mm(3); P < 0.001, power = 0.998), representing an average airway expansion of +11.54 % (2.35 %/mm activation). While the nasopharynx and oropharynx showed highly significant expansion (P < 0.000, power = 0.999), the airway at the laryngopharynx did not change significantly (P > 0.779, power = 0.05). Although the patients were significantly older in the Hybrid RME group (P = 0.006), the positive rhinological effects were comparable within all groups of different appliances (P > 0.316). Hybrid RME may, therefore, be an advisable procedure in patients with nasomaxillary impairment and pronounced patient's age.

IntroductionRapid maxillary expansion (RME) is a common technique to improve the dental and skeletal transverse width in cases of constricted maxillary arches. Although retention after RME has been widely examined, there is still no clear statement about the minimal retention time in postpubertal patients and many practitioners have retention concepts varying between three and six months.MethodsThis retrospective study consisted of 14 patients who were either treated with a Haas-type RME (6 patients) or a Hybrid-RME (8 patients). The average age was 15.8 years (min. 13.5 years, max. 23.0 years).Low-dose CT scans were taken initially before placement of the RME (T0), directly after maximal activation (T1) and (in six cases) also in retention after 6 months (T2). Using a 3D-software (“OnDemand3D”/Cybermed Inc.) in analogy to the method published by Franchi et al. (AJODO Volume 137/ Number 4) all values were measured twice at an interval of 1 month to assess the method error and the intraoperator reliability.Statistical analysis was performed using SPSS 21 for Mac. Possible influences of the RME-type were assessed using the univariate ANOVA. Changes in the sutural density between the different points of time were examined using paired t-tests.ResultsThe density of the suture decreased significantly after expansion (T0-T1) with both types of RME (p = 0.000). In the retention period there was a significant increase of the sutural density (p = 0.007) although it did not achieve the initial level (p = 0.002).Conclusions1. The midpalatal suture was opened in all analysed patients.2. In postpubertal patients a retention time of six months does not allow sufficient reorganization of the suture.3. Therefore, a retention period longer than six months seems to be beneficial to prevent relapses in postpubertal patients.

The aim of this study was to evaluate the morphological nasal changes associated with rapid maxillary expansion (RME) which is used in the treatment of skeletal maxillary narrowness. The study was performed with 20 patients 12 girls and 8 boys between the ages of 10 and 15 (13.4±0.99) and compared with a control group consisting of 16 subjects 10 girls and 6 boys between the ages of 10 and 15 (13.25±1.18). Lateral and anteroposterior radiographs were taken before RME (T1), after RME (T2) , and after retention (T3). Greater alar cartilage width, nasal cavity width, vertical and sagittal movement of the tip of nose, SNA° and nasolabial angle measurements were evaluated to understand the morphological and positional changes of the nose associated with RME. The results showed that the greater alar cartilage width returned to its original position, the nasal cavity width increased, and the tip of the nose moved downward and minimally forward; as well, SNA° returned to its original value and a small increase occurred in the nasolabial angle due to RME. Soft tissue changes may be considered clinically non-significant compared with the controls. RME did not affect the patients' frontal nasal appearance and mid-face soft tissue profile.

Objective: The literature indicates a correlation between vertebral morphologic anomalies and some orthodontic malocclusions. The aim of this study was to examine the occurrence of the types of cervical vertebral anomalies (CVAs) in subjects with transverse maxillary deficiency (TMD) and to compare this with the occurrence of CVA in a control group without TMD. Materials and Method: A sample of 47 Turkish patients (17 boys, 30 girls) with TMD and another sample of 47 Turkish patients (15 boys, 32 girls) with adequate maxillary transversal dimensions was studied. A visual assessment of the cervical column was made using lateral cephalometric films. Characteristics of the cervical column were classified according to Sandham as fusions and posterior arch deficiencies of C1 (PADs). Clinically normal appearance was determined when the first 4 vertebrae could be traced as separate entities with all anatomic components present. Differences in occurrence of CVA between the groups and between genders were assessed by v 2 independence test. Results: In the TMD group, 10,6% of the subjects had fusion in the cervical column, and 14,9% had PAD. In the control group, 17% of the subjects had fusion of the cervical column, and 8,5% had PAD. The occurrence of PAD was significantly increased in the TMD group (p,0.05), while no significant difference was found between the groups for occurrence of fusion (p.0.05). No statistically significant gender differences were found in the occurrence of CVA in the TMD group and the control group (p.0.05). Conclusion: No difference was found in the occurrence of fusion between the subjects with TMD and the subjects without TMD, and the occurrence of PAD was significantly increased in subjects with TMD. (Turkish J Orthod. 2015;27:136-142)