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KPG index versus OPG measurements: a comparison between 3D and 2D methods in predicting treatment duration and
Domenico Dalessandri1, Marco Migliorati2, Luca Visconti3
1Department of Orthodontics, School of Dentistry, University of Brescia, Piazzale Spedali Civili 1, 25123 Brescia, Italy ; Department of Medical, Surgical and Health Sciences, School of Dentistry, University of Trieste, Piazza Ospitale 1, 34129 Trieste, Italy.
Aim:
The aim of this study was to test the agreement between orthopantomography (OPG) based 2D measurements and the KPG index, a new index based on 3D Cone Beam Computed Tomography (CBCT) images, in predicting orthodontic treatment duration and difficulty level of impacted maxillary canines.
Materials And Methods:
OPG and CBCT images of 105 impacted canines were independently scored by three orthodontists at t 0 and after 1 month (t 1), using the KPG index and the following 2D methods: distance from cusp tip and occlusal plane, cusp tip position in relation to the lateral incisor, and canine inclination. Pearson's coefficients were used to evaluate the degree of agreement and the χ(2) with Yates correction test was used to assess the independence between them.
Results:
Inter- and intrarater reliability were higher with KPG compared to 2D methods. Pearson's coefficients showed a statistically significant association between all the indexes, while the χ(2) with Yates correction test resulted in a statistically significant rejection of independency only for one 2D index.
Conclusions:
2D indexes for predicting impacted maxillary canines treatment duration and difficulty sometimes are discordant; a 3D index like the KPG index could be useful in solving these conflicts.
