Remodeling of teeth by grinding.

Pulp and dentin reactions to extensive grinding of human teeth were studied clinically and histologically. The facial portions of forty-eight premolars to be extracted for orthodontic reasons were reshaped to "lateral incisors" using diamond instruments and abundant water cooling. Following grinding and polishing with sandpaper discs and pumice, topical fluoride was administered. The patients were asked to report any increased sensitivity reactions. The teeth were extracted at 0, 1, or 3 weeks or 3 to 5 months and examined histologically. No significant discomfort was reported by the patients except for an initial period of a few days during which there was increased sensitivity to temperature changes. The histologic findings indicated that extensive remodeling of young permanent teeth is possible with no or only minor pulp and dentin reactions. Some initial localized effects in terms of aspiration of odontoblast nuclei, hyperemia, absence of a cell-free zone, and slight cellular infiltration were sometimes observed, but the long-term observations indicated that these reactions were transient. Secondary dentin formation was not registered. It is important that gentle grinding techniques with abundant water spray be used and that smooth and self-cleansing surfaces which allow hypermineralization of the ground enamel and dentin be prepared. In a few teeth in which proximal retention areas were unintentionally prepared, caries developed and marked pulp reactions occurred. Therefore, great care must be taken not to introduce proximal steps when mesiodistal tooth width adjustments are performed. The present study has provided histological and clinical evidence to indicate that even extensive recontouring by grinding may not be harmful to the teeth. This should encourage orthodontists to remodel teeth by grinding to improve the final occlusal and esthetic results in a number of different cases.