Minimum lateral wall heights for conservative class I cavity preparations

To quantify the minimum necessary Class I cavity preparation lateral wall heights (LWH) for a cavity preparation 0.8 mm in width and extending to the dentin-enamel junction in a set of extracted human permanent posterior teeth.

183 bucco-lingual or mesio-distal undecalcified sections were cut from a set of 73 posterior teeth. Macroscopic digital images were made of fissures within the sections and a computer-generated digital measuring device was superimposed to obtain LWH measurements corresponding to a cavity preparation 0.8 mm in width and extending to the dentin-enamel junction. Preparation LWH data was analyzed by tooth type and groups for mean, minimum, maximum, standard deviation, count, and frequency distribution.

LWH varied between 1.2 mm and 2.5 mm for the 183 fissures tested. Mean LWH was 1.925 mm with a standard deviation of 0.262 mm. The most common LWH was 2.0 mm, found in 18% of the samples. Seventy percent of LWHs were 2.0 mm or less. Only two sections had LWHs of 1.2 mm, both in maxillary first premolars. Only two sections had LWHs of 2.5 mm, one in a mandibular second molar and the other in a maxillary first molar. Maximum LWH correlated positively (r = .469) with bucco-lingual crown width.