Adaptive adjustment of the adolescent porcine mandibular condyle

The effect of occlusal support during primary dentition on the mandibular condyle remains controversial. We sought to determine whether unilateral loss of occlusal support leads to quantifiable adaptive changes of the condyle. Quantitative analysis of condylar growth and spongy bone volume after unilateral removal of teeth on the left side in adolescent minipigs was examined over a period of 4 months. Serial sagittal sections of the temporomandibular joint were examined using microradiography, fluorescence microscopy, and light microscopy. The condyles on the nonextracted side showed a higher growth rate than those on the extracted side, with a 1.56-fold thicker (p = 0.003) additional vertical bone layer. This factor was greater ventrally than dorsally (p = 0.0311), increasing from dorsomedial (1.33) to ventrolateral (2.38). There was therefore a reciprocal change of the condylar surface curve between the left and right condyles. Increased condylar growth correlated with a lower subchondral spongy bone volume (7.38% difference, p = 0.002). The amount of mineralized bone matrix generated was estimated to be about 1.33-fold higher in the nonextraction side condyles compared with those on the extraction side. Thus, unilateral loss of occlusal support was shown to lead to quantifiable alterations of condylar vertical growth and spongy bone volume in minipigs.