Periodontal ligament areas and occlusal forces in dentitions restored with cross-arch unilateral posterior two-unit cantilever bridges

This investigation was undertaken in order to analyse to what extent the magnitudes of chewing and biting forces in dentitions restored with cross-arch unilateral posterior two-unit cantilever bridges are correlated to the area of the periodontal tissue supporting the abutments. 12 subjects, whose dentitions were periodontally treated and prosthetically restored, participated in the study. The chewing and biting forces, simultaneously measured in various parts of, as well as over the entire dentition, were correlated to the periodontal ligament areas of the abutments supporting the bridge constructions. A strong positive correlation (r = 0.83; P less than 0.01) was found between the total remaining periodontal ligament area and the mean total chewing force. A positive correlation (r = 0.57; P = 0.05) was also found between the local remaining periodontal ligament area of the posterior end abutment tooth and the local chewing force in that region. No positive correlation was found between the amount of periodontal tissue support and the magnitude of the forces developed during biting with maximal strength in habitual occlusion either totally or locally, although there was a strong tendency (r = 0.54; 0.6 greater than P greater than 0.5) towards decreasing total maximal bite force with decreasing total remaining periodontal ligament area. A strong positive correlation (r = 0.74; P less than 0.01) was found on the end abutment side between the local remaining periodontal ligament area of the end abutment tooth and the local forces in that region during biting with maximal strength over a limited area at a time.(ABSTRACT TRUNCATED AT 250 WORDS)