Periodontal status of indirect resin composite restorations with proximal box elevation: 3-year clinical results

This prospective controlled clinical trial aimed to evaluate the periodontal status of posterior indirect resin composite (IRC) restorations followed by proximal box elevation (PBE), based on clinical and radiographic parameters. Additionally, the study investigated the influence of restoration depth and supracrestal tissue attachment (STA) violation on periodontal outcomes.

A total of 80 molars with deep cervical margins were restored using IRC (SR Nexco) with PBE (Tetric-N Flow and Tetric-N Ceram). Of these, 42 restorations with PBE on one proximal surface (mesial or distal) in 39 patients were included. The test group consisted of the proximal surfaces restored with PBE due to subgingival margin placement, whereas the control group comprised the opposite proximal surfaces of the same teeth without restoration. Periodontal parameters including plaque index (PI), gingival index (GI), probing pocket depth (PPD), and bleeding on probing (BoP) were assessed at baseline (15 days after cementation), and at 6, 12, 24, and 36 months. Standardized periapical radiographs were used to monitor alveolar bone levels at designated follow-ups. Test and control sides were compared using the Robust Mixed ANOVA test (PI, GI, PPD) and McNemar's test (BoP).

Data were available from 42, 39, 33, and 30 teeth at baseline, 6, 12, 24, and 36 months. No significant differences were found at any time point (p > 0.05) for none of the periodontal parameters. PPD values showed a significant change over time (p = 0.001), with pairwise differences observed between baseline and 12-, 24-, and 36-month measurements, as well as between 6- and 36-month, 12- and 36-month, and 24- and 36-month time points. Within the test group, no significant differences in BoP were found among STA grades (p > 0.05).

PBE appears to be biologically safe and clinically acceptable, even when the restorative margin is located close to or slightly within the STA, without leading to severe periodontal response resulting in alveolar bone resorption.

PBE facilitates the adhesive restoration of deep proximal cavities without surgical intervention. The findings support the clinical use of PBE in anatomically challenging cases where subgingival margin elevation is required.

ClinicalTrials.gov identifier: NCT03832829.