Clinical Crown Height of Posterior Teeth: Implications for Tooth Preparation

Objectives: This preliminary study measured clinical crown height of posterior teeth in young healthy adults. Clinical crown height influences margin placement of crown preparations. Required wall height for crown preparations is a function of tooth size and axial wall taper. Tapers typically used require a preparation height of approximately 3 mm to ensure adequate resistance and retention (Maxwell, Gen Dent,1990; Goodacre et al, J Prosthet Dent, 2001). Knowledge of clinical crown height can help predict the probability of subgingival margin placement. Published values report measurements to the CEJ rather than to the gingival margin. Methods: In this blind study, Type IV stone casts were made from alginate impressions of 46 young adults (19 female, 27 males; mean age 23.5 yrs.). Clinical crown height was measured at 6 locations corresponding to periodontal probing sites for all first molars and premolars. Buccolingual and mesiodistal width were also recorded. Tooth orientation was considered for all 3248 standardized measurements. Age, sex, malposition, arch constriction, existing restorations and wear patterns were recorded. Mean and standard deviation values were calculated. Results: Premolar and molar clinical crown height at four line angle locations was consistently lower for females (range:1.7- 3.2 mm ) than for males (range:2.6-3.6 mm). Values for coronal width were consistent with those reported by Wheeler (1940). Conclusions: Findings suggest that in this population, proximal margins for crown preparations on the measured teeth should be placed subgingivally to ensure adequate retention and resistance.