Clinical Performance of Injectable and Conventional Resin Composites in Posterior Class I Restorations

Overview

This study compared the one-year clinical performance of two tooth-colored filling materials used for restoring cavities in posterior teeth: a highly filled injectable resin composite and a conventional resin composite. The study included 38 participants aged 20 to 26 years who required at least two Class I restorations in permanent premolars or molars. Each participant received both restorative materials in different teeth using a randomized split-mouth design. A total of 120 restorations were placed, including 60 restorations with G-ænial Universal Injectable and 60 restorations with G-ænial Posterior. The restorations were evaluated one week, six months, and 12 months after placement using the FDI criteria, which assess esthetic, functional, and biological properties. In addition, 20 participants with 64 restorations were randomly selected for a detailed assessment of restoration surfaces and margins. Digital impressions were obtained, three-dimensional resin replicas were produced, and the replicas were examined using scanning electron microscopy. The study aimed to determine whether the two restorative materials differed in their clinical and micromorphological performance during the one-year follow-up period.

This was a prospective, randomized, assessor-blinded, split-mouth clinical trial conducted at the Department of Restorative Dentistry, Faculty of Dentistry, Van Yüzüncü Yıl University. Systemically healthy individuals with good oral hygiene and at least two carious lesions classified as International Caries Detection and Assessment System scores 4 or 5 in permanent premolars and/or molars were eligible. Individuals with bruxism, malocclusion, xerostomia, or periodontal disease were excluded. Teeth with previous restorations, endodontic treatment, periodontal or periapical pathology, or no antagonist or adjacent tooth were also excluded. Thirty-eight participants aged 20 to 26 years were enrolled. A total of 120 posterior Class I restorations were placed. Each participant received both study materials in different eligible teeth according to a split-mouth design. The first eligible tooth and the material assigned to that tooth were determined by coin toss, and allocation of the remaining eligible teeth continued clockwise within the dental arches. G-ænial Posterior, a conventional resin composite, was used for 60 restorations, and G-ænial Universal Injectable, a highly filled injectable resin composite, was used for 60 restorations. All restorations were placed by the same clinician using standardized cavity preparation, adhesive, light-polymerization, finishing, and polishing procedures. Participants were unaware of the material used in each tooth. Clinical assessments were performed by another investigator who was not involved in placing the restorations. The restorations were evaluated one week, six months, and 12 months after placement using the FDI evaluation system. Esthetic, functional, and biological properties were scored from 1 to 5. Scores of 1 to 3 were considered clinically acceptable, whereas scores of 4 or 5 were considered clinically unacceptable. Twenty participants with 64 restorations were randomly selected for micromorphological assessment. Digital impressions were obtained at one week, six months, and 12 months. Three-dimensional resin replicas were manufactured and examined by scanning electron microscopy. The visible restoration margins were assessed for marginal integrity, excess material, marginal fractures, negative marginal steps, marginal leakage, and other surface or marginal defects. The examiner performing the micromorphological assessment was blinded to the clinical evaluation results.