Effects of Immediate Dentin Sealing and Quercetin on the Fracture Strength of Ceramic Inlays in Premolars of Daibetics

AIM: This in vitro study evaluated the effects of immediate dentin sealing (IDS) versus delayed dentin sealing (DDS), dentin pretreatment with quercetin (Qu), and their combination on the fracture strength (FS) of diabetic and non-diabetic premolars restored with ceramic inlays after thermomechanical aging. METHODS: Forty-eight extracted premolars from diabetic individuals and forty-eight from non-diabetic individuals were collected and prepared for standardized MOD lithium disilicate ceramic inlays. Each category of teeth was divided into four groups according to the cementation technique (IDS or DDS) and the presence or absence of Qu pretreatment during inlay cementation. For IDS, the same adhesive was applied in combination with a flowable composite. All restored premolars underwent thermomechanical aging followed by FS testing under axial compression. Data were analyzed using three-way ANOVA and t-tests (P = .05). RESULTS: Technique, Qu treatment, diabetes mellitus (DM), and the interactions between DM and Qu (P = .004) and between DM and technique (P = .021) were significant. The interaction among all three factors and the interaction between technique and Qu were not significant. In all groups except DDS/Qu, diabetic premolars exhibited lower FS than non-diabetic premolars (P < .001). IDS resulted in significantly higher FS in both tooth types (P < .001). The positive effect of Qu pretreatment was observed only in diabetic premolars (P < .001). CONCLUSION: In diabetic premolars, IDS and Qu pretreatment substantially enhanced the FS of teeth restored with ceramic inlays, with the greatest improvement observed when both were combined. In non-diabetic premolars, a significant improvement was observed only with IDS. CLINICAL RELEVANCE: Diabetes-related changes in dentin may compromise the performance of adhesive restorations. Understanding the effects of dentin sealing techniques and the potential benefits of Qu may help improve the durability of indirect restorations in patients with diabetes.