Introduction
In this study, we investigated tooth-wear patterns in adolescents with either normal occlusion or Class II Division 2 malocclusion.
Methods
The sample consisted of dental casts from 165 subjects that were divided into 2 groups: 115 normal occlusion subjects (mean age, 14.3 years) and 50 complete Class II Division 2 subjects (mean age, 13.9 years). Dental wear was assessed by using a modified version of the tooth wear index. The 2 groups were compared with the Mann-Whitney test for the frequency and severity of wear on each surface of each group of teeth. The level of statistical significance was set at 5%.
Results
The normal occlusion group statistically had greater tooth wear on the incisal surfaces of the maxillary lateral incisors and the incisal surfaces of the maxillary canines than did the Class II Division 2 malocclusion group. The malocclusion group showed statistically greater tooth wear on the labial surfaces of the mandibular lateral incisors, the occlusal surfaces of the maxillary premolars and first molars, the occlusal surfaces of the mandibular premolars, the palatal surfaces of the maxillary second premolars, and the buccal surfaces of the mandibular premolars and first molars than did the normal occlusion group.
Conclusions
Subjects with normal occlusion and those with complete Class II Division 2 malocclusions have different tooth-wear patterns. Tooth wear on the malocclusion subjects should not be considered pathologic but, rather, the consequence of different interocclusal arrangements.
Editor’s comments
Tooth wear is an all-embracing term used to describe the combined processes of abrasion, erosion, and attrition. Attrition is the regular, slow, and progressive loss of dental tissues as a consequence of tooth-to-tooth contact (as in mastication), and it has specific characteristics. First, if attrition is the only cause of tooth wear, it will be seen only in areas of occlusal contact. Second, attrition creates wear facets with a specific appearance: shiny, flat, and sharp-edged. Third, attrition produces similar amounts of wear on opposing teeth. Finally, if attrition is the cause, the worn teeth must have occlusal contact during mandibular excursion. The purpose of this study from the University of São Paulo, Brazil, and the University of Michigan was to compare the pattern of tooth wear in subjects with Class II Division 2 malocclusion with that in subjects with normal occlusal relationships.
The authors used a version of the tooth wear index (TWI). Modifications consistent with the World Health Organization standards allow application of the index in broad epidemiological surveys for both the deciduous and permanent dentitions. In total, 11,880 dental surfaces were evaluated. Of these, 77.7% had no dental wear, 20.1% had incipient lesions, 0.4% had moderate lesions, and 1.8% were excluded. No severe lesions were found. The normal occlusion group statistically had greater tooth wear on the incisal surfaces of the maxillary lateral incisors and canines than did the malocclusion group.
This study is an uncommon and interesting work on this subject. Although the references were selected to present a comprehensive point of view, the article ignores functional occlusal criteria. The attritional occlusion is a physiologic-dynamic phenomenon, and yet this study was based only on static records: dental casts. No “canine-guidance” and “group-function” methods of analysis were considered in the subjects. Overall, this article is still important because it draws attention to functional occlusal criteria. The results show that patients with normal occlusion and complete Class II Division 2 malocclusion have some tooth wear. Tooth wear in malocclusion patients should not be considered pathologic but, rather, a consequence of different interocclusal arrangements.
