Evaluation of clinical performance of additively manufactured and milled polyetheretherketone (PEEK) inlays compared with indirect composite resin inlays over a one-year follow-up: A randomized clinical trial

Abstract

Statement of problem: Data on polymer materials, particularly polyetheretherketone (PEEK) used in restorative dentistry, are scarce, as is knowledge concerning the clinical efficacy of PEEK restorations produced through additive manufacturing when compared with existing indirect materials and techniques. Purpose: The purpose of this randomized clinical trial was to evaluate the clinical performance of additively manufactured and milled PEEK inlays compared with composite resin inlays according to modified United State Public Health Service (USPHS) criteria over a 1-year follow- up. Material and methods: Participants were allocated into 3 distinct categories based on the materials and techniques used: R1 denoting teeth restored with 3 dimensionally (3D) printed PEEK inlays (N=16), R2 representing teeth restored with milled PEEK inlays (N=16), and R3 indicating the comparator group comprising teeth restored with milled composite resin inlays (N=16). After the placement of inlay restorations, evaluations were conducted at 3 time points (T): baseline (T0), 6 months (T1), and 12 months (T2) by using the modified USPHS criteria for assessing anatomic form, color match, marginal discoloration, marginal adaptation, surface texture, secondary caries, retention, and postoperative sensitivity. Ordinal data were analyzed using the Kruskal-Wallis test, followed by the Dunn post hoc test for between group comparisons, as well as the Friedman test, followed by the Nemenyi post hoc test for within group comparisons (α=.05). Results: Across all parameters and intervals, most of the restorations within each group exhibited an alfa score, with no statistically significant differences noted (P>.05). However, concerning color match, all restorations within the PEEK groups received a bravo score, indicating a statistically significant difference in intergroup comparison between the milled composite resin groups and the PEEK group (P<.001). However, no significant variances were noted in the scores evaluated across different follow-up periods (P>.05). Conclusions: Subtractive and additive manufacturing techniques, as well as PEEK and composite resin materials together, offer clinically acceptable functioning restorations over 1 year. PEEK material can be used as a suitable alternative to commonly used indirect composite resin intracoronal restorations in posterior areas. Improvements in terms of surface texture and esthetics are required.