Short-term clinical and micromorphological comparison of injectable and paste composites in occlusal cavities

The aim of this clinical trial was to evaluate and compare the 12-month performance of a contemporary injectable and a conventional paste-type resin composite in Class I cavities using the modified USPHS criteria, supported by SEM analysis.

A total of 72 teeth from 34 volunteers were included. Each participant received at least two restorations (one per material); in cases where more eligible cavities were present, additional restorations were performed accordingly. All restorations were performed under rubber dam isolation following conservative Class I cavity preparation, using selective enamel etching and a universal adhesive. All procedures were carried out by the same clinician using a paste-type resin composite (Filtek Z250 Universal Restorative) and an injectable resin composite (G-ænial Universal Injectable). Two calibrated investigators evaluated restorations at baseline, 6, and 12 months using modified USPHS criteria. SEM analysis was conducted on a total of 66 epoxy replicas obtained at baseline, 6, and 12 months from 11 randomly selected participants. Statistical analysis was performed using SPSS (Version 23.0, IBM, NY) with Pearson's chi-square and Cochran's Q tests.

Both materials demonstrated comparable and clinically acceptable performance over the 12-month evaluation period according to the modified USPHS criteria, with no statistically significant differences observed at any time point across all criteria, although minor changes were observed in marginal adaptation and color match in a few restorations (p > 0.05). All participants attended the follow-up visits, resulting in a 100% recall and retention rate.

The injectable (G-ænial Universal Injectable) and paste-type (Filtek Z250) resin-composites demonstrated comparable and clinically acceptable short-term performance in Class I occlusal restorations, although longer-term follow-up is needed to confirm these findings.

As trial registration took place after the first participant was enrolled, the study was retrospectively registered at ClinicalTrials.gov on December 21, 2023, with ID: NCT06192667. https://register.

gov/prs/beta/studies/S000DTX600000072/recordSummary /.