Unilateral loss of occlusal support during deciduous dentition and its consequences to the growing mandibular condyle.

Loss of supporting zones during deciduous dentition effects the condylar growth and the spongybone density of the mandibular condyle. This is a quantitativeanalysis. The deciduous molars of micropigs are removed unilaterally. Sequence fluorochrome labeling is performed during the four month course of experiment.The examination is done on non-decalcified serial sagittal sections of the TMJ. The condyles of the distracted joints show a higher growth-rate compared to theextraction-side condyles, resulting in an 1.56 (p=0.003) times thicker additional vertical bone layer. This factor is ventral higher than dorsal (p=0.0311), increasing at the most from dorsomedial (1.33) to ventrolateral (2.38), which implies a reciprocal change of the condylar surface curve. However, the higher condylar growth of the unloaded condyles is correlated to a lower density of the corresponding subchondral spongy bone (7.38% difference, p=0.002). The total amount of bone produced is 1.33 times higher on the unloaded side. Aside with adaptive changes degenerative changes occur as well. So, for the first time the influence of unilateral loss of occlusal support on the mandibular condyles vertical growth, its trabecular bone volume and its amount of mineralized bone-matrix generated is quantified. Unilateral loss of occlusal support during deciduous dentition may lead to undesired adaptive and degenerative changes of the TMJ. Keywords: occlusal-support, unilateral-loss, quantification, condylar-growth, condylar-shape, subchondral-spongy-bone-density, degenerative-changes