Comparison between KPG Index and OPG Measurements: Predicting Orthodontic Treatment Duration and Difficulty Level in Impacted Canines

Abstract

Objective: To compare 2D (Orthopantomogram) and 3D KPG index based on (CBCT) measurements to predict the treatment duration and difficulty level of orthodontic treatment for canine impaction. Study Design: Cross sectional analytical study. Place and Duration of Study: Orthodontic Department, Rehman College of Dentistry, Peshawar from 4th September ,2017 till 8th August ,2020. Materials and Methods: OPG and CBCT (Cone beam computed tomography) records of 49 impacted canines were scored for both 2D and 3D indexes. KPG index measurements were taken for each impacted canine in x, y, z planes, scored from 0- 5 and summed up. Based on these scores, each impaction was classified into two categories, Easy to Moderate (0–14), Difficult to very Difficult (15 -30). Following 2D measurements were taken on OPG, cusp tip distance to the occlusal plane, cusp tip position relative to adjacent lateral incisor, and inclination of canine relative to midline. Comparisons were made using Chi square test and Spearman’s correlation was used to find any association between 2D and 3D methods. P values ≤0.05 were considered significant. Results: 68.8% of the impacted canines were found on the palatal side with a female (73.5%) predilection. The 2D Ericson and Kurol analysis and Stewart's indexes showed a significant difference when compared with 3D KPG index (p= 0.001) and a moderate correlation (r=0.47). Comparison between the 2D indexes showed an insignificant difference (p=0.90) and a weak correlation (r=0.26). Conclusion: 3D KPG index measurements, compared to the 2D indexes, showed a significant difference and a moderate correlation. Therefore, KPG index can be used in place of 2D indices to accurately locate, determine the difficulty level and treatment duration of orthodontic treatment of impacted canines.

Keywords

• canine impaction, cbct (cone beam computed tomography), kpg index.