Aim: To investigate the effect of the CAD/CAM formed Zirconia bar retained overdenture on periodontal health in terms of Plaque Index (PI), Gingival Index (GI) and Relative attachment level (RAL) in addition to marginal bone height change (MBH change) of the supporting mandibular abutments in comparison to conventionally constructed Cobalt- Chromium bar retained overdenture.
Materials and methods: Twenty patients were randomly selected with only two remaining mandibular canines. Patients were randomly allocated into two groups. Each group received maxillary complete denture and mandibular overdenture retained by bar attachment where group A patients received Zirconia bar retained overdentures while group B patients received Cobalt-Chromium (Co-Cr) bar retained overdenture. The PI, GI, and change in RAL of the abutments were evaluated at loading time (0 month), six, and twelve months follow up visits. Standardized Long cone paralleling technique with periapical x-rays was used to evaluate the MBH change.
Results: Group B showed significant increase in the mean values of PI, GI and change in RAL in comparison with group A at six and twelve months follow up visits. On the other hand, insignificant difference in MBH change proximal to the abutments was detected between the two groups although group B showed higher MBH change values than group A.
Conclusion: The Zirconia bar showed superior results compared to conventional Co-Cr bar on the periodontal health of the abutments concerning PI, GI and change in RAL. However, comparable results were shown regarding the effect on MBH change proximal to the abutment teeth.