TOOTH THICKNESS AT THE FURCATION ENTRANCE OF LOWER MOLARS

Better understanding of the furcation anatomy may serve to decrease th e risk of pulpal injury during rotary odontoplasty, a procedure often used in conjunction with guided tissue regeneration. The purpose of th is study was to determine (i) the tooth thickness about the furcation entrance of lower molars, and (ii) whether there is a relationship bet ween tooth thickness and patient age. 40 mandibular 1st molars (M1) (m ean age=36.2; range 10-65 years) and 40 mandibular 2nd molars (M2) (me an age=37.9; range 14-70 years) were collected. Age, gender and furcat ion involvement (if any) were noted for each tooth at the time of extr action. Teeth were sectioned in half, buccal-lingual, at the furcation entrance with a rotary diamond blade. A standardized linear reference scale was placed on each experimental section and an 8x10 in. photogr aph generated. The distance from the floor of the pulp chamber to 5 pr edetermined sites on the root surface was calculated. The data were ex pressed as (a) the mean of each site and (b) the mean of each tooth (t he average of the 5 points of each tooth). Analysis of covariance fail ed to show a relationship between thickness measurements and gender or furcation involvement. Thus, the data was subjected to simple regress ion analysis to determine the relationship of age with tooth and cemen tum thickness. This study revealed that by site, the mean measurements ranged from 2.7-3.0 mm for both M1 and M2. The single least/greatest measurements of the 5 sites were for M1: 1.6/4.7 mm and for M2: 1.8/4. 2 mm. By tooth, the average distance from the pulp to the root surface was 2.83 mm (+/-0.49) for M1 and 2.88 mm (+/-0.44) for M2. Regression analysis of tooth thickness with age was significant for M1 only. The maximum slope of the 5 sites was approximately 0.3 mm/10 years. No re lationship was found between cementum thickness and age for either too th group. The results of this study indicate that the majority of time s the pulp is 1.6-4.2 mm from the root surface in the vicinity of the furcation entrance of lower 1st and 2nd molars. Although tooth thickne ss in this area may increase with age, the amount is not enough to for ego judicious odontoplasty on older patients.