Classification of the Type of Contact Between Primary Molars as an Indicator of the Likelihood of Future Caries

Contact areas between first and second primary molars, shaped by concave/convex proximal surface morphology, are associated with proximal caries with concave surfaces linked to biofilm stagnation. This study aimed to evaluate the accuracy and clinical feasibility of a scoring system for classifying contact types (concave-concave, concave-convex, convex-convex, convex-concave) for dental practitioners.

Following ethical approval and informed consent, 116 4-5-year-old children were enrolled. A calibrated examiner assessed caries on the distal of first molars and mesial of second molars using ICDAS-merged criteria and scored 464 proximal contacts clinically and radiographically. Stone models from silicone impressions were also scored by 17 trained practitioners, who repeated scoring a week later and assessed contacts clinically in six children. Practitioners completed a feasibility and satisfaction questionnaire.

Convex-convex contacts were most prevalent (58.6%), followed by convex-concave (32.6%). Contact type significantly correlated with caries (OR = 13.5; 95% CI: 6.4-28.3). Inter- and intra-examiner reproducibility ranged from 0.71 to 0.82. Most practitioners felt very (64.7%) or moderately (35.3%) capable of applying the system, found it low in difficulty (70.6%), and expressed high satisfaction (82.4%).

The study indicated that it is possible for dental practitioners to classify the proximal contact types between primary molars both in an accurate and clinically feasible way. The system exhibited high reproducibility and practitioner satisfaction, indicating its potential as a valuable tool for identifying caries-prone surfaces and supporting evidence-based caries management.