Primary tooth ankylosis: report of case with histological analysis.

Two primary molars in infraclusion showing clinical and radiographic signs of ankylosis, were subject to histological examination by bright field and polarization microscopy. The roots revealed signs of ongoing resorptive and reparative processes and in some areas dentin with signs of resorption-or repair cementum-were fused with simple lamellar or osteonic bone. These results suggest that ankylosis of primary molars can result from a disturbance of root resorption, with repair processes prevailing over resorptive ones and leading to excessive deposition of bone besides cementum-as a consequence of bone-inductive properties of dentin.