The influence of fixed prosthesis placement on the clinical effectiveness of non-surgical periodontal therapy

Fixed prostheses are essential for restoring teeth with compromised structures. However, the margins of prosthesis potentially create an interface that interferes with proper cleaning. This study evaluated whether the fixed prosthesis placement influenced the clinical effectiveness of non-surgical periodontal therapy (NSPT).

Clinical records from 202 patients with generalized chronic periodontitis receiving NSPT at the National Taiwan University Hospital in 2012-2014 were included. The change and improvement ratio (IR) of clinical parameters following NSPT in the entire dentition or posterior region, and all or periodontitis-affected teeth/crowns (T/C) and sites were evaluated. The differences among natural teeth (NT), prosthetic crowns (PC), and abutments (AB) were compared by using Kruskal-Wallis tests followed by Dunn's post-hoc test.

Gingival recession (REC) was greater in PC and AB groups than in the NT group before NSPT, while tooth mobility was also lower in the AB group. REC gain was lower in the AB group after NSPT, while mobility reduction was inferior in the PC and AB groups for all or periodontitis-affected T/C and sites. In periodontitis-affected T/C, IRs in probing pocket depth reduction and clinical attachment gain were lower in the PC group, and mobility reduction was lower in the AB group. The tendency in the posterior region is similar but was less pronounced than in the entire dentition.

The effectiveness of NSPT and the improvement of periodontal parameters are reduced when fixed prostheses present. MB reduction is inferior in AB teeth relative to NT.