Date of Award


Document Type


Degree Name

Master of Dental Science (MDS)



Research Advisor

Edward F. Harris, Ph.D.


Quinton C. Robinson, D.D.S., M.S. Richard A. Williams, D.D.S., M.S.


Malocclusion, Tooth Size, Crowding, Mesiodistal, Crown Dimensions, Dental Cast


From among numerous potential causes of dental malocclusion, tooth size has been implicated as one factor. Prior studies show that mesiodistally larger teeth increase the risk of malocclusion. The present report extends our understanding by testing for graded responses between crown size and the extent of dental malocclusion. Maximum mesiodistal crown dimensions of all 14 permanent tooth types (excluding third molars) were measured in 207 American white adolescents (routine orthodontic patients), and 10 measures of malocclusion (e.g., rotations, displacements, spacing) were recorded. Analysis of covariance (controlling for sexual dimorphism in tooth size) disclosed (1) significant positive associations between crown size and measures of crowding and (2) significant negative associations between crown size and measures of spacing. Of note, significant associations are widespread, involving all tooth types, both those emerging early and late. This systemic effect seems due to the intercorrelations among tooth dimensions and to the cumulative effects of crown sizes summed across multiple teeth—and this is borne out by multivariate models. Overall, tooth size probably is not commonly the paramount cause of malocclusion, but it is a readily documented influence, and its importance probably is increasing due to secular increases of crown sizes in response to diminished morbidity and improved nutrition.