Abstract
Background: The aim of this study was to investigate at what level of misalignment of the mandibular incisors dental professionals and lay people begin to recognize dental crowding, which was distinguished from ideal dental alignment.& para;& para;Methods: A mandibular occlusal photograph with an ideal dental alignment formed the basis of this study. By rotation of a central incisor, a lateral incisor, or both lateral incisors, the photograph was morphed to mimic varying degrees of dental misalignment. The altered photographs were then scored by the following groups of people: orthodontists (ORT), general dentists (GD), lay people with prior experience of orthodontic treatment (LWO), or lay people with no history of orthodontic treatment (LNO).& para;& para;Results: When the amount of Little's irregularity index (LII) reached 1 mm for a central incisor, it triggered ORT to consider providing orthodontic treatment. In contrast, the concern of GD and LWO was aroused at 1.5 mm. The ORT noted crowding of a lower lateral incisor at 1.5 mm of LII, whereas GD and LWO were sensitive to 2.0 mm. It is noteworthy that the LNO ignored the misalignment of either a central incisor or a lateral incisor even when LII was at 2.0 mm. When both lower lateral incisors were morphed, all groups were aware of 2 mm of misalignment.& para;& para;Conclusions: Orthodontists were more critical than other groups when evaluating the misalignment of the lower incisors. These results provide orthodontic professionals with information that may help to determine how much dental crowding the general public is willing to accept without treatment. (C) 2012 World Federation of Orthodontists.