Changes in the periodontal membrane due to apical periodontitis

Teeth with an apical inflammatory lesion were studied by light microscopic morphometrical procedures to estimate the volumetric density of periodontal ligament tissues by point counting. Sixty-four root surfaces were investig ated from coronal to apical, The observed tissue changes were similar in gr oups with and without bacteria, except for an elevated volumetric density o f inflammatory cells in the first group. The attachment was lost apically, Principal fibers running to the root surface and extensions in the cementum decreased from coronal to apical, but were replaced by fibers running para llel to cementum and fibers oriented in a network. We suggest that acellula r extrinsic fiber cementum was lost, whereas cellular mixed stratified ceme ntum was built. The cellular mixed stratified cementum synthesis was by inc lusion of the remaining fibers from the acellular extrinsic fiber cementum, We suspect that the changes were the result of the anti-inflammatory react ion caused by the periapical lesion.