An evaluation of the Pi analysis in the assessment of anteroposterior jaw relationship.

OBJECTIVE: This study has investigated two new cephalometric variables, the Pi angle and Pi linear in the evaluation of anteroposterior skeletal discrepancy. DESIGN: Retrospective cross-sectional study. SETTING: Manipal College of Dental Sciences, Manipal, India SUBJECTS AND METHOD: A sample of 155 subjects (mean age 19·7 years) were subdivided into skeletal class I, II and III groups based upon ANB angle. Descriptive data were calculated for each variable and group. Receiver operating characteristics curves were used to examine sensitivity and specificity of the Pi angle in the discrimination between different skeletal groups. Correlation coefficients were obtained for each of the parameters to compare their relationship with other parameters in the class I group. Coefficient of determination, regression coefficient, regression equation and standard error of estimate were also calculated from the parameters showing significant correlation with the Pi angle. RESULTS: Mean values for the Pi angle in skeletal class I, II and III subjects were 3·40 (±2·04), 8·94 (±3·16) and -3·57 (±1·61) degrees, respectively. For the Pi linear they were 3·40 (±2·20), 8·90 (±3·56) and -3·30 (±2·30) mm for class I, II and III subjects, respectively. Receiver operating characteristic curves showed that a Pi angle greater than 5 degrees had 89% sensitivity and 82% specificity for discriminating a skeletal class II group from class I. A Pi angle of less than 1·3 degrees had 100% sensitivity and 84% specificity in discriminating skeletal class III groups from class I. The overall accuracy for discriminating class II groups from class I was 85% and for class III from class I, 90%. Thus, a cut-off point between class I and II groups could be considered a Pi angle of approximately 5 degrees and between class I and class III, approximately 1·3 degrees. There were no statistically significant correlations found between Pi angle and ANB (0·07), Beta angle (-0·04) and WITS analysis (0·19). The highest level of correlation was obtained for the Pi angle and Pi linear (0·96). CONCLUSION: The anglar and linear components of the Pi analysis are a suitable method for assessing anteroposterior jaw discrepancy in daily clinical practice.

Investigation of the transmigrated canine in an orthodontic patient population.

OBJECTIVE: To investigate the prevalence, demographic and clinical characteristics of transmigrated canines in a south Indian orthodontic patient population. DESIGN: Retrospective observational study. SETTING: Manipal University, Manipal, India. SUBJECTS AND METHODS: Panoramic radiographs of 3500 patients were examined and data collected regarding the number and side of transmigrated canines, sex and age of patients, any other associated pathologies and subsequent treatment. Transmigrated canines were classified according to Mupparapu's classification. RESULTS: The prevalence of transmigrated canines in this population was found to be 0.46% of which, seven were males (age: 17-51 years) and nine were females (age: 17-35 years). All transmigrated canines were unilateral and impacted. Eleven canines migrated from the left to the right side, and five migrated from the right to the left. Of the 16 patients, 13 had retained primary canines and 3 had exfoliated primary canines. Eight canines exhibited a type 1 transmigratory pattern, type 2, type 4 and type 5 transmigratory patterns were exhibited by two canines each. One of the canines was classified as type 3. Three canines were associated with dentigerous cyst formation. Four cases were treated by orthodontic traction, while one was removed surgically. Others were observed periodically. CONCLUSIONS: Diagnosis of transmigration at earlier stages is important to prevent more complex occlusal problems.

Unusual intraosseous transmigration of impacted tooth.

Transmigration of an impacted tooth through the symphyseal suture is a rare and special developmental anomaly of unknown etiology that is unique to the mandibular canine. Maxillary canine transmigration is even rarer. Transmigrated canines are particularly significant due to the aesthetic and functional importance. A maxillary lateral incisor crossing the mid-palatal suture has never been reported in the literature. The aim of this report is to present the first case of simultaneous transmigration of a lateral incisor and canine in the maxilla. The paper also reports four unusual cases of unilateral canine transmigration in the maxilla and mandible and successful eruption of one of the transmigrated mandibular canines following orthodontic traction. Etiology of transmigration and its clinical considerations are also discussed.