Furkan Dindaroğlu

Accuracy and reliability of 3D stereophotogrammetry: A comparison to direct anthropometry and 2D photogrammetry

OBJECTIVE To evaluate the accuracy of three-dimensional (3D) stereophotogrammetry by comparing it with the direct anthropometry and digital photogrammetry methods. The reliability of 3D stereophotogrammetry was also examined. MATERIALS AND METHODS Six profile and four frontal parameters were directly measured on the faces of 80 participants. The same measurements were repeated using two-dimensional (2D) photogrammetry and 3D stereophotogrammetry (3dMDflex System, 3dMD, Atlanta, Ga) to obtain images of the subjects. Another observer made the same measurements for images obtained with 3D stereophotogrammetry, and interobserver reproducibility was evaluated for 3D images. Both observers remeasured the 3D images 1 month later, and intraobserver reproducibility was evaluated. Statistical analysis was conducted using the paired samples t-test, intraclass correlation coefficient, and Bland-Altman limits of agreement. RESULTS The highest mean difference was 0.30 mm between direct measurement and photogrammetry, 0.21 mm between direct measurement and 3D stereophotogrammetry, and 0.5 mm between photogrammetry and 3D stereophotogrammetry. The lowest agreement value was 0.965 in the Sn-Pro parameter between the photogrammetry and 3D stereophotogrammetry methods. Agreement between the two observers varied from 0.90 (Ch-Ch) to 0.99 (Sn-Me) in linear measurements. For intraobserver agreement, the highest difference between means was 0.33 for observer 1 and 1.42 mm for observer 2. CONCLUSIONS Measurements obtained using 3D stereophotogrammetry indicate that it may be an accurate and reliable imaging method for use in orthodontics.

Evaluation and comparison of root resorption between tooth-borne and tooth-tissue borne rapid maxillary expansion appliances: A CBCT study.

OBJECTIVE To compare volumetric root resorption after rapid maxillary expansion (RME) between tooth-borne and tissue-borne appliances using CBCT. Repair in resorption cavities after 6 months of fixed retention was also compared. MATERIALS AND METHODS A sample of 33 subjects were randomly divided into two groups: Hyrax (n  = 16) and Haas (n = 17). CBCT scans were taken 6 months before expansion, immediately after expansion, and 6 months after fixed retention. Mimics Innovation V 16.0 software was used for segmentation and volumetric measurement of 198 teeth. Bland-Altman plots, independent samples t test, repeated measures analysis of variance, and the Friedman test were used for statistical analysis. RESULTS Differences in root resorption after RME and repair after retention were not significant between the hyrax and Haas appliances or between male and female. Significant differences were found between preexpansion and postexpansion root volumes in the first premolars and molars--even in unattached second premolars. When the percentage of root volume loss is considered, no significant difference was found between the first premolar, second premolar, and first molar. Volumetric changes after 6 months of retention were not statistically significant. CONCLUSIONS More resorption was observed in the Hyrax expander group. But it was not statistically significant. Repair was observed after 6 months of retention. Heavy RME forces affected premolars and molar similarly.

Social smile reproducibility using 3-D stereophotogrammetry and reverse engineering technology

OBJECTIVE To assess the range of social smile reproducibility using 3-D stereophotogrammetry and reverse engineering technology. MATERIALS AND METHODS Social smile images of white adolescents (N  =  15, mean age  =  15.4 ±1.5 years; range  =  14-17 years) were obtained using 3dMDFlex (3dMD, Atlanta, Ga). Each participant was asked to produce 16 social smiles at 3-minute intervals. All images were obtained in natural head position. Alignment of images, segmentation of smile area, and 3-D deviation analysis were carried out using Geomagic Control software (3D Systems Inc, Cary, NC). A single image was taken as a reference, and the remaining 15 images were compared with the reference image to evaluate positive and negative deviations. The differences between the mean deviation limits of participants with the highest and the lowest deviations and the total mean deviations were evaluated using Bland-Altman Plots. RESULTS Minimum and maximum deviations of a single image from the reference image were 0.34 and 2.69 mm, respectively. Lowest deviation between two images was within 0.5 mm and 1.54 mm among all participants (mean, 0.96 ± 0.21 mm), and the highest deviation was between 0.41 mm and 2.69 mm (mean, 1.53 ± 0.46 mm). For a single patient, when all alignments were considered together, the mean deviation was between 0.32 ± 0.10 mm and 0.59 ± 0.24 mm. Mean deviation for one image was between 0.14 and 1.21 mm. CONCLUSIONS The range of reproducibility of the social smile presented individual variability, but this variation was not clinically significant or detectable under routine clinical observation.

Three-dimensional evaluation of social smile symmetry

OBJECTIVE To evaluate the social smile symmetry using three-dimensional (3D) stereophotogrammetric images. MATERIALS AND METHODS The study was conducted with 3D facial images of 30 individuals (age range 13-25 years). The rest position was considered as the reference image and the social smile image was aligned on this image using the best-fit alignment method. The spatial differences between the same points established on both images using 3D analyses were determined for right and left points in X, Y, and Z planes. RESULTS The highest difference related to spatial distance in right and left points was -0.56 mm (95% confidence interval [CI], -1.19, 0.06 mm) between right and left commissure (Com) points. The difference was not significant, and the Bland-Altman upper and lower limits were -3.85 mm and 2.71 mm, respectively. The highest difference for the transversal plane was found in Com points, similarly to the spatial distance (mean: 0.50 mm, 95% CI, -2.62, 1.02 mm). The differences between the changes in the left and right points in the Y and Z plane were not significant (P > .05). CONCLUSIONS The social smile was observed to show asymmetry in varying amounts in the different directions. Asymmetry increases in some cases, specifically for the corners of the mouth.

Root Resorption in Orthodontics

Root resorption has been the subject of many studies, and it can be caused by many factors such as the mechanics used during orthodontic treatment, factors related to the type and magnitude of the force, and other factors related to treatment such as the type of tooth movement and malocclusion. The clinical importance of root resorption is directly related to its detectability. Therefore, orthodontic and biological factors that may cause root resorption were evaluated using various imaging methods in present use. In this review, root resorption in orthodontics was considered from different viewpoints.

Evaluation of the Relationship between Curve of Spee, WALA-FA Distance and Curve of Wilson in Normal Occlusion

Objective To test the hypotheses that (i) there is a significant correlation between the curve of Spee (COS), basal arch (WALA ridge) to dental arch distance (WALA-FA distance) and curve of Wilson (CW) and that (ii) the deepening of the COS is affected by the CW and the WALA-FA distance. Methods Mandibular models of 50 patients aged between 20 and 35 years were scanned with TRIOS. The xyz coordinate system was determined, and a reference occlusal plane was generated. The depth of the COS, the CW, and WALA-FA distance were measured using an engineering software. Results The greatest difference in the measurement of the depth of the COS between the right and left was found to be 0.41±0.50 mm in the first molar teeth. On the basis of the results of Pearson correlation analysis, there was no strong correlation between the depth of the COS, the CW, and the WALA-FA distance. Conclusion It was shown that there was no strong correlation between the depth of COS, CW, and WALA-FA distance. The CW and WALA-FA distance could not be effective in the deepening of the COS.

Perception of Smile Esthetics by Orthodontists and Laypersons: Full Face and A Localized View of The Social and Spontaneous Smiles

Objective The aim of the study was to evaluate the parameters that might affect the esthetic perception of localized and full-face views of social and spontaneous smiles. Methods Video records of 40 individuals were used. Further, 200 images of each individual were captured for social and spontaneous smiles with and without calibration glasses. Full-face images of social smile (SSF) and spontaneous smile (smile of joy) (JSF) were obtained. Furthermore, the mouth-area images of the same social (SSM) and spontaneous (JSM) smiles from each subject were acquired. Here 160 images were evaluated by orthodontists and laypersons using the Q-sort method. The data were analyzed with logistic regression and independent samples t-test. Results From the orthodontic perspective, upper lip thickness (p=0.004), lip curtain over incisors (p=0.016), maxillary incisor display (p=0.01), and buccal corridor ratio (p=0.006) were significant to determine attractive and unattractive images when viewing localized social smiles. Laypersons identified no particular parameter to explain the variation in preferences for all the image groups (p>0.05). Conclusion Upper lip thickness and maxillary incisor display during smiling were found to be effective for distinguishing images as attractive and unattractive by orthodontists. No objective evaluations for the attractiveness were made by laypersons.

Inconsistency between ANB Angle and Wits Appraisal in the Turkish Population

Objective: The aim of this study was to investigate the cephalometric parameters that impair the consistency between the Wits and ANB measurements, which are used in the determination of anteroposterior jaw relationships by logistic regression analysis in the Turkish population. Methods: This retrospective study was conducted on 207 lateral cephalometric radiographs of 100 females (mean age: 15.5±1.09 years; age range: 14.2–17.3 years) and 107 males (mean age: 15.1±0.93 years; age range: 14.1–16.9 years) obtained from the archives of the orthodontic department. Lateral cephalometric radiographs were divided into two groups according to the presence of inconsistency between the ANB angle and Wits appraisal. The cephalometric parameters that cause the inconsistency were determined using a logistic regression method with the creation of three different regression models. Results: We found posterior rotation of the mandible (SN-MP0) (OR=1.09; p=0.029) as an independent predictor of the inconsistency in Model 1. In Model 2, SN-MP0 (OR=1.11; p=0.016) was also found to be effective on the development of the inconsistency. In Model 3, inclination of the occlusal plane (OP-SN0) (OR=1.07, p=0.02) was the independent predictor of the inconsistency. Conclusion: An increase in SN-MP0 and OP-SN0 are effective in the development of inconsistency between the ANB and Wits appraisals in the Turkish population.