Root surface area of the mandibular cuspid and bicuspids.

Background: The purpose of this study was to determine the total root surface area of extracted teeth by computerized image analysis and the amount of remaining attachment area assuming various amounts of bone loss due to periodontal disease.

Methods: One hundred fifty extracted mandibular teeth were evaluated, and measured from cusp tip to the cemento-enamel junction (CEJ), CEJ to root apex, and cusp tip to root apex. The fulcrum point of the tooth was also measured, along with the total root surface area of attachment and total surface area of attachment remaining following simulation of attachment loss in 2 mm increments. Measurements were made on 80 teeth on one proximal surface and either the buccal or lingual surface and multiplied by a factor of 2. Measurements on 70 teeth were made on all 4 root surfaces to predict the accuracy of measuring only 2 surfaces to determine root surface area. Images of the tooth surfaces were obtained by video camera and converted to computer image with measurement of the surface areas.

Results: The total root surface area for the mandibular cuspids and first and second bicuspids was 275.88 mm2, 251.45 mm2, and 271.81 mm2, respectively. The 2-sided and 4-sided measurements for the mandibular first bicuspid were 252.55 mm2 and 247.02 mm2, respectively (P>0.05).

Conclusions: This study found the total root surface area to be greater than that in most previous studies. Increasing attachment loss is related to decreasing root surface area; however, this relationship is not directly proportional. No statistical difference was found between measuring 4 surfaces versus only 2 surfaces.