Association of Occlusal Morphology with Cracked Teeth: A 3D Morphometric Comparative Clinical Study.

INTRODUCTION

Tooth morphology may predispose tooth cracking, yet evidence linking occlusal morphology to cracked molars remains limited. This study aimed to investigate the association between them, to establish reference intervals for early risk detection and management of cracked teeth.

METHODS

Eighty-three cracked molars (68 patients) and 83 matched controls (69 volunteers) were analyzed. Occlusal morphologies (functional/nonfunctional cuspal inclination/height/slope) were measured using intraoral scans (Trios, 3Shape, Denmark) and analyzed using 3D digital design software. The crack initiation side (CIS) and propagation side (CPS) of crack lines were identified. Paired t-tests were used to compare the differences between groups. Multivariate logistic regression was used to assess correlations between occlusal morphology and cracked molars.

RESULTS

Maxillary cracked molars exhibited steeper functional cuspal inclinations (CIS: [31.87 ± 7.72]°, CPS: [29.03 ± 7.50]°) than controls ([26.01 ± 7.01]°, [25.61 ± 7.47]°, P < .05), with 4°-6° differences. Mandibular cracked molars showed steeper inclinations only in functional cusps on CIS ([30.79 ± 7.89]° vs [24.53 ± 6.97]°, P < .05). Functional cuspal heights were 0.2-0.4 mm higher in cracked teeth than in controls for both arches (P < .05). Cracked molars exhibited flatter functional cusp slopes. Multivariate analysis identified CIS inclination (OR 1.098) and CPS height (OR 3.407) of functional cusps as maxillary risk factors; CIS functional cuspal height (OR 8.177) showed the highest risk for mandibular cracked molars.

CONCLUSIONS

Within the limitations of this study, specific occlusal morphologies were correlated with cracked teeth. The identification of an excessively steep or high functional cusp in a molar warrants a thorough examination for crack lines. Morphology-guided occlusal adjustments should be considered in the treatment of cracked molars.