Objective vs subjective analyses of arch form and preformed archwire selection.

INTRODUCTION: Maintaining a patient's original arch form increases treatment stability. In this study, we assessed the agreement between subjective analyses of arch form and archwire selection by orthodontists and an objective method with Cast Analyzer Iranian X software (Khallaghane Mehr, Tehran, Iran). METHODS: Thirty-six casts with normal occlusion were scanned with a laser. The software generated the best-fit curve using a fourth-degree polynomial equation to the clinical bracket points on the casts; then it selected the best preformed nickel-titanium archwire based on the root mean square calculation either objectively or semiobjectively. Three orthodontists selected the best-fit curve and archwire subjectively using the casts. To assess intraexaminer reliability, the same orthodontists reevaluated 10 casts after 2 weeks. To assess interexaminer reliability, the 3 orthodontists performed the analyses with the software and on the casts. Agreements were evaluated with the intraclass correlation coefficient and Dahlberg's formula. RESULTS: The semiobjective method (visual selection of wire by orthodontists using the software) yielded the best results. The differences were clinically negligible between the objective (fully automated) and semiobjective methods (1.30 vs 1.36 mm). CONCLUSIONS: The objective method improved wire adaptation to the clinical bracket points. Agreement among orthodontists regarding wire selection will improve significantly when they are trained to use the software.

Photographic Facial Soft Tissue Analysis by Means of Linear and Angular Measurements in an Adolescent Persian Population.

OBJECTIVE: To obtain objective average measurements of the profile and frontal facial soft tissue to be used as a guide for aesthetic treatment goals. Methods and Materials : This observational study included 110 females and 130 males high school students aged 16-18 years. None of the subjects had any facial deformities. All of them and their parents gave consent to take part in this study. In each case, two standard photographs of profile and frontal views were taken 27 landmarks were digitized on photographs. The mean, standard deviation, and range for a total of 43 facial indices were calculated digitally by computer software. The Student's t-test was used to compare males and females. Results : The ratio between the lower and middle facial thirds was one to one, but the height of the upper facial third was proportionally smaller than the other two-thirds in both sexes. Boys had greater nasal length, depth, and prominence than girls with statistically significant differences. Both upper and lower lips were more prominent in girls than in boys. All measurements of the chin showed sexual dimorphism characterized by greater chin height and prominence and deeper mentolabial sulcus. Boys had greater facial dimensions than girls. Mouth width, nasal base width, and intercanthal distance were significantly greater in boys. Conclusion : The labial, nasal, and chin areas showed sexual dimorphism in most of the parameters used in this study. Boys had larger faces, greater facial heights, longer nasal, labial, and chin lengths, and greater nasal, labial, and chin prominence.

Validity and reliability of a three-dimensional dental cast simulator for arch dimension measurements.

BACKGROUND: The accuracy and reproducibility of measurements in a locally made three dimensional (3D) simulator was assessed and compared with manual caliper measurements. MATERIALS AND METHODS: A total of 20 casts were scanned by our laser scanner. Software capabilities included dimensional measurements, transformation and rotation of the cast as a whole, separation and rotation of each tooth and clip far. Two orthodontists measured the intercanine width, intermolar width and canine, molar and arch depth on the casts and in 3D simulator. For calculating the reliability coefficient and comparing random and systematic errors between the two methods, intra-class correlation coefficient of reliability (ICC), Dahlberg and paired t-test were used, respectively. The ICC and Dahlberg's formula were also applied to assess intra-examiner and inter-examiner reliability of measurements on the casts and in the simulator (P < 0.05). RESULTS: Canine and molar depth measurements had low reliability on the casts. Reliability between methods for the remaining three variables was 0.87, 0.98 and 0.98 in the maxilla and 0.92, 0.77 and 0.94 in the mandible, respectively. The method error was between 0.31 and 0.48 mm. The mean intra-observer difference were 0.086 and 0.23 mm in the 3D method and caliper. The inter-observer differences were 0.21 and 0.42 mm, respectively. CONCLUSION: The maximum average absolute difference between the two methods was <0.5 mm, indicating that the new system is indeed clinically acceptable. The examiner reliability was higher in 3D measurements.