The Effect of Implant-supported Fixed Prosthesis on the Periodontal Ligament Width and Structure in Opposing Natural Teeth of Macaca Fascicularis

Background and aims: Although rehabilitation of the partially dentate jaw with implant-supported fixed prosthesis has achieved high success rates, little is known regarding their effects on the opposing natural dentition. The periodontal ligament (PDL) functions as a dynamic attachment apparatus, and responds to occlusal forces by widening/narrowing and alterations in collagen fiber density/ orientation. This study aimed to determine the effects of occlusal load from implant-borne bridgework on PDL of the opposing natural teeth. Materials and Methods: Test samples consisted of four healthy adult male Macaca fascicularis with implant-supported 3-unit bridgework at the second premolar-second molar regions of their mandibles – one side for immediate-loading and the other side for delayed-loading, in a split mouth design. Another pair of monkeys with natural dentition served as normal controls. After 3 months of functional loading, the animals were sacrificed. Non-decalcified sections were prepared for histomorphometric assessment of PDL structure, cervical and apical widths. Results: PDL collagen fiber density and orientation were similar in both groups and no signs of inflammation were present. The width of PDL of the teeth in the experiment group at the cervical and apical regions were significantly increased compared to control (p<0.05). Conclusion: PDL widening might reflect a functional response to occlusal forces from the ‘rigidly ankylosed’ implant-supported fixed prosthesis.