Abstract
The purpose of this investigation is to evaluate the validity of TPI in the assessment of malocclusion in Japanese. Plaster models obtained from 163 females of 18 to 24years of age were examined according to TPI, and ranked for severity of malocclusion by three orthodontists. The following results were obtained after the comparison between the order of TPI value and the orthodontic ranking. TPI showed a reasonable validity because the Spearman rank correlation coefficient was 0.806. There were some overestimated cases in TPI, such as maxillary incisal crowding, mandibular incisal crowding, deep bite, molar malocclusion, and ectopic eruption.
There were several underestimated cases in TPI, such as inversion of incisors, maxillary protrusion, edge to edge, diastema, midline displacement, and mandibular incisor aplasia. These were thought to be unacceptable faults.
Therefore it is concluded that some modification must be considered to the weighting of TPI in order to apply it for epidemiological survey in Japanese.
