Clinical Performance of HVGIC vs Bulk Fill Composite in Class II Cavities of Posterior Teeth: A 12-Month RCT

Overview

Study Title: Clinical Performance of Highly Viscous Glass Ionomer versus Bulk Fill Resin Composite Restorative Materials in Moderate Class II Cavities of Permanent Posterior Teeth: A 12-Month Randomized Clinical Study Study Design: Split-mouth, randomized clinical trial on 31 patients with at least two moderate Class II carious lesions in permanent posterior teeth. Each patient receives two restorations-bulk fill resin composite on one side and highly viscous glass ionomer (HVGIC) on the other. Aim: To compare the clinical performance of bulk fill resin composite and HVGIC restorations over 1 week (baseline), 6 months, and 12 months using the modified United States Public Health Services (USPHS) criteria. Primary Outcome: Marginal adaptation of the restorations Secondary Outcomes: 1. Anatomic form 2. Contact point 3. Restoration retention 4. Marginal discoloration 5. Surface texture 6. Color match 7. Secondary caries 8. Postoperative sensitivity Methodology Highlights: Evaluation by two blinded examiners Standardized cavity prep and material application Clinical evaluation using USPHS criteria at all follow-up intervals Statistical analysis with chi-square, ANOVA, or non-parametric tests as appropriate (R software v4.3.2) Ethical Considerations: Approved by the Faculty of Dentistry, Ain Shams University Research Ethics Committee Informed consent will be obtained from all participants Significance: This study helps determine whether HVGIC can be a clinically viable alternative to bulk fill resin composite in moderate Class II cavities, with implications for durability, patient compliance, and cost-effectiveness

Title: Clinical Performance of Highly Viscous Glass Ionomer versus Bulk Fill Resin Composite Restorative Materials in Moderate Class II Cavities of Permanent Posterior Teeth: A 12-Month Randomized Clinical Study Study Overview: This study is a prospective, randomized, split-mouth clinical trial designed to compare the clinical performance of bulk fill resin composite and highly viscous glass ionomer (HVGIC) restorative materials in moderate Class II cavities of permanent posterior teeth over a 12-month period. The evaluation of restorations will be based on the modified United States Public Health Services (USPHS) criteria at three time intervals: 1 week (baseline), 6 months, and 12 months post-treatment. Rationale and Background: The challenge of achieving a long-lasting, mechanically resilient, esthetically acceptable restoration in stress-bearing areas such as Class II cavities continues to drive innovation in restorative dentistry. While resin composites offer favorable physical and esthetic properties, their inherent polymerization shrinkage and technique sensitivity have prompted the development of alternatives like bulk fill composites, which allow deeper curing and reduced shrinkage. Meanwhile, glass ionomer materials-notably HVGICs-have seen advancements aimed at improving their physical and mechanical properties, particularly with the introduction of resin coating systems such as the EQUIA system. The need for comparative clinical evaluation under real-world conditions remains critical to guide clinical decision-making. Aim of the Study: To evaluate and compare the clinical performance of bulk fill resin composite and highly viscous glass ionomer restorations in moderate Class II cavities of permanent posterior teeth over time using the modified USPHS evaluation criteria. Objectives: To assess the clinical behavior of bulk fill resin composite and HVGIC restorations in Class II cavities. To determine the effect of time (1 week, 6 months, and 12 months) on the clinical performance of these restorative materials. Research Question: Is there a significant difference in the clinical performance between bulk fill resin composite and highly viscous glass ionomer restorations in moderate Class II cavities of permanent teeth over a 12-month follow-up? Hypothesis: The null hypothesis (H₀) states that there is no significant difference in clinical performance between the two restorative materials, nor does the time interval significantly influence their performance. Study Design: A split-mouth, randomized controlled clinical trial involving 31 patients, each presenting with at least two moderate Class II carious lesions, one on each side of the mouth. This design allows direct intra-individual comparison between materials under similar oral conditions. Setting: Outpatient clinics of the Operative Dentistry Department, Faculty of Dentistry, Ain Shams University, Cairo, Egypt. Sample Size Calculation: Based on a power analysis with α = 0.05, β = 0.2 (power = 80%), and an effect size of ω = 0.398, the calculated sample size was 62 restorations (31 patients). A 15% increase was added to account for possible dropouts, resulting in a final sample of 72 restorations (36 patients). Randomization and Blinding: Random allocation will be performed using www.randomization.com. Allocation concealment will be ensured, and two independent blinded evaluators will perform outcome assessment at each follow-up point. Clinical Procedure: Bulk fill composite group: Rubber dam isolation, selective enamel etching, universal adhesive application, placement of bulk fill composite per manufacturer's instructions. HVGIC group: Cotton roll isolation, cavity conditioning with polyacrylic acid, insertion of HVGIC using a capsule system, finishing with diamond stones on the same day. Follow-up and Evaluation: Clinical evaluation at 1 week, 6 months, and 12 months using the modified USPHS criteria, which include: Statistical Analysis: Categorical data: Chi-square test Numerical and ordinal data: Shapiro-Wilk test for normality If normally distributed: Repeated measures ANOVA with Bonferroni post hoc test If not: Friedman's test with Dunn's post hoc Significance level: p \< 0.05 Software: R version 4.3.2 for Windows Ethical Considerations: Study approved by the Faculty of Dentistry, Ain Shams University Research Ethics Committee Participants will provide informed written consent No harm expected beyond standard dental procedures; restorations needing repair or replacement will be redone free of charge Funding: No external funding was received. Risks and Benefits: Risks: Minimal: possible restoration failure requiring repair or replacement Benefits: Free treatment and 12-month follow-up Improved understanding of restorative options for clinicians and patients Research Significance: This study provides valuable clinical data comparing two widely used restorative materials under routine conditions. The findings may influence material selection in moderate Class II cavities and support evidence-based improvements in clinical practice.