Gender Determination in Pakhtun Pakistani Population Using Dental Arch Dimensions: A Digital Model Study

@#Introduction: In circumstances where the ante mortem list is unknown, gender determination would exclude onehalf of the population, aid in a more precise search of the ante mortem records. This study aims to formulate gender prediction models in the Pakhtun Pakistani population using digital dental arch dimensions. Methods: Data collection and analysis of the dental casts were conducted on 128 subjects, 64 males and 64 females from the Pakistani population. The mean age of the subjects was 19.2 years old. Several linear dental arch dimensions were measured and recorded for both upper and lower arches. Results: It was found that gender differences in linear arch dimensions were statistically significant for both males and females (p<0.05); in which the arch dimensions for the males were larger than the arch dimensions for the females. Stepwise discriminant function analysis found that the highest discriminant power of the variables was present within the inter-second premolar width for the upper arch and inter-molar width for the lower arch. These variables significantly contributed to gender variance. Moreover, the prediction of 67.2% of original grouped cases for the upper arch and 66.4% of cross-validated group cases was correct. Similarly, the correct prediction was made on 64.8% of original grouped cases for the lower arch and 64.1% of cross-validated group cases. Conclusion: The dental arch dimensions were larger among the males compared to the females. Prediction models obtained in this study were moderately strong predictors which may be used as an adjunct to predict gender.

Efficacy of the Prefabricated Myofunctional Appliance T4FTM in Comparison to Twin Block Appliance for Class II Division 1 Malocclusion Treatment: A Randomized Clinical Trial

@#Introduction: The aim of the study was to compare the changes in the skeletal and dentoalveolar structures in Malay patients with Class II Division 1 malocclusion treated by prefabricated re-mouldable customizable functional appliance (T4FTM) and Twin Block (TB) appliance. Methods: A randomised clinical trial was carried out with samples randomly assigned to active (TB appliance) and experimental (T4FTM appliance) groups. Pre- and post-treatment lateral cephalometric radiographs were taken for each subject and the overjet was clinically measured at the same intervals. 20 angular and linear measurements were chosen and measured separately. Results: Independent t test was used to compare the changes between the two groups. A significant difference between the groups was seen with overjet at 2.14 mm (p < 0.01), Sv_Pog distance at 1.83mm (p < 0.05), Sv_ii distance at 2.55 mm (p < 0.001), horizontal distance from the upper to the lower incisor tip at 1.81 mm which was statistically significant (p < 0.05). The other variables SNB and ANB angles too showed a significant difference. However, all the favourable changes were noted in the TB group. Conclusion: T4FTM appliance could be an effective appliance for the management of British Standard Institute's Class II Division 1 malocclusion on Class II skeletal pattern. However, the TB group differed significantly and had a more favourable correction in terms of the sagittal skeletal and dentoalveolar discrepancy.

Comparison of Dento-Alveolar and Skeletal Changes Between Immediate and Delayed Placement of Fixed Appliances After Twin Block Therapy

@#Introduction: A parallel design randomized clinical trial was conducted to compare dentoalveolar and skeletal changes in two groups of patients who had completed twin block therapy; one group had a three-month night-time retention period whereas the other group had no retention period, after twin block therapy but before fixed appliances. Methods: 26 participants of Malay ethnicity aged 10 to 15 years were included in the trial and had an overjet of 5mm or greater, molar relationship greater than half cusp Class II on a skeletal Class II base which had been corrected to a Class I molar relationship following twin block therapy. Following randomization, the 26 were divided into two groups of 13. Group A had fixed appliances bonded immediately whereas group B continued wearing twin block at night for three months, after which fixed appliances were bonded. Lateral cephalograms assessed were those taken before randomization, upon twin block therapy completion (T1) and six months after bond-up of fixed appliances (T2). Results: Paired t-test showed several statistically significant dentoalveolar and skeletal changes in group A. In contrast, only condylar head position exhibited a statistically significant change in group B. Despite a statistical significance, changes measured in both groups were minimal at less than 2mm and therefore clinically insignificant. Independent t-test showed no statistically significant difference between the changes recorded in both groups. Conclusion: The results suggest that a three-month night-time retention period after twin block therapy does not lead to any changes that may be considered clinically beneficial.

New prediction equations for the estimation of maxillary mandibular canine and premolar widths from mandibular incisors and mandibular first permanent molar widths: A digital model study / 대한치과교정학회지

OBJECTIVE: The primary aim of the study was to generate new prediction equations for the estimation of maxillary and mandibular canine and premolar widths based on mandibular incisors and first permanent molar widths. METHODS: A total of 2,340 calculations (768 based on the sum of mandibular incisor and first permanent molar widths, and 1,572 based on the maxillary and mandibular canine and premolar widths) were performed, and a digital stereomicroscope was used to derive the the digital models and measurements. Mesiodistal widths of maxillary and mandibular teeth were measured via scanned digital models. RESULTS: There was a strong positive correlation between the estimation of maxillary (r = 0.85994, r2 = 0.7395) and mandibular (r = 0.8708, r2 = 0.7582) canine and premolar widths. The intraclass correlation coefficients were statistically significant, and the coefficients were in the strong correlation range, with an average of 0.9. Linear regression analysis was used to establish prediction equations. Prediction equations were developed to estimate maxillary arches based on Y = 15.746 + 0.602 × sum of mandibular incisors and mandibular first permanent molar widths (sum of mandibular incisors [SMI] + molars), Y = 18.224 + 0.540 × (SMI + molars), and Y = 16.186 + 0.586 × (SMI + molars) for both genders, and to estimate mandibular arches the parameters used were Y = 16.391 + 0.564 × (SMI + molars), Y = 14.444 + 0.609 × (SMI + molars), and Y = 19.915 + 0.481 × (SMI + molars). CONCLUSIONS: These formulas will be helpful for orthodontic diagnosis and clinical treatment planning during the mixed dentition stage.

The assessment of accuracy and reproducibility of cephalometric analyses using Computer-Assisted Simulation System for Orthognathic Surgery (CASSOS) software

Cephalometric analyses using computer software have more advantages than manual analyses. However, the software should be evaluated for the accuracy and reproducibility before it can be used. The aims of the present study were: 1) to compare the differences in accuracy and precision between utilizing scanned images and soft copy images with the software 2) to assess the reproducibility of software and manual cephalometric analyses. Fifteen cephalograms were selected randomly from the Record Unit, Hospital Universiti Sains Malaysia. All films had 10 fiducial points marked and were scanned at 75 dots per inch (dpi) and 300 dpi. Manual and digital measurements were compared to obtain magnification factors. Seven digital x-ray images of a caliper were taken. The mean differences were measured between the fixed caliper measurement and digital measurements. Subsequently, 37 cephalograms were traced manually and digitally with Computer-Assisted Simulation System for Orthognathic Surgery (CASSOS) software to assess its accuracy and reproducibility after applying the obtained magnification factor. Steiner analysis was utilized and T tests were used to evaluate the mean difference. P<0.01 was considered significant. The magnification factors of 300dpi and 75dpi for both horizontal and vertical measurements were 0.50 and 0.95 respectively, while magnification factor for softcopy image measurements was 0.89. Cephalometric comparisons between original and digital images showed statistically significant differences for several variables but the mean differences were clinically insignificant. Although some distortion was noted, it was clinically acceptable after correction of the enlarged images with magnification factors. The reproducibility of CASSOS is excellent and as good as other commercially available cephalometric software.