Postoperative Sensitivity and clinical evaluation of Posterior Composite Restorations in medium and deep cavities placed using two insertion techniques (Two-Years-Randomized Clinical Study)

Objective: This prospective randomized clinical study had two objectives, the first was to evaluate the influence of the cavity depth (medium and deep) and the insertion technique (flowable bulk and incremental layering) on the occurrence of postoperative sensitivity (POS) in single-surface (class I) posterior composite resin restorations; and the second was to evaluate the clinical performance of these restorations over two-year period using selected united states public health service (USPHS) Criteria.
Methods: A total of 15-females and 17 males of an average age 25.6 ± 6.1 years were enrolled in this clinical study. Patient selection was based on predetermined clinical criteria. In each patient, one pair of active occlusal caries (class I) of almost the same depth were included, each of which was located in a different quadrant (split-mouth design). Patients were divided into two groups based on the cavity depth: G1 included 21-pairs of medium-class I and G2 included 11-pairs of deep-class I. Cavities were randomly allocated to one of the two composite resin insertion methods: incremental layering using a nanohybrid resin composite only as control (CeramX-Mono) and a flowable bulk-fill base (SDR) veneered with CeramX-Mono. Methods used in cavity preparation, bonding procedures, finishing, and polishing were standardized and rubber-dam was used for all the clinical procedures. Evaluation of postoperative sensitivity (POS) was carried out at baseline (immediately after restoration), one-day, one-week, and one-month after treatment using cold/air stimuli, and recorded using a visual analog scale. The clinical evaluation of the restorations was carried out at baseline, one year and two-years, using modified USPHS selected relevant criteria according to van Dijken (1986): anatomic form, marginal integrity, color match and secondary caries. Scores of POS were statistically analyzed using Chi-square test, Fisher’s exact test and ordinal regression at the level of significance P ≤ 0.05. Scores of the clinical criteria were analyzed using cumulative frequency distribution of scores. Fisher’s Exact test was used to compare between the two cavity depths. Wilcoxon signed-rank test was used to compare between the two techniques. Friedman’s test was used to study the changes by time within each group. Results: there was no statistically significant effect of gender and age on sensitivity grades. There was no significant difference between sensitivity grades at baseline for all groups. However, deep-cavity groups showed the significantly higher prevalence of mild to moderate sensitivity than medium-cavity groups. In a medium-cavity group, there was no statistically significant difference between sensitivity grades at one-day after restoration using the two techniques. All cases showed no POS at one-week and one-month. However, in the deep-cavity group, layering-technique showed the statistically significantly higher prevalence of mild sensitivity than bulk-fill technique one-day after restoration. There was no significant difference between the two techniques after one-week. Additionally, the entire deep-cavity group showed no sensitivity at one-month. Clinical evaluation of all restorations showed excellent performance at 2-year follow-up with 0% failure rate. The cavity depth and the insertion technique showed no significant effect on anatomical form, color match and marginal discoloration with a range of (scores 0-1). All cases showed excellent marginal continuity and no recurrent caries (score 0). However, in deep cavity groups at one-year evaluation, bulk fill showed a statistically significant higher prevalence of slight color mismatch (score 1) than layering technique which didn’t change significantly after two-years.
Conclusion: Bulk fill technique based on SDR flowable base can be considered an alternative to conventional layering when the clinically relevant thickness is required. Bulk fill insertion may be significant in minimizing POS in high C-factor class I without sacrificing the physical and mechanical properties in stress-bearing areas. Both techniques showed acceptable clinical performance with predominantly excellent scores for all the clinical parameters analyzed in this 2-year follow-up clinical study.