Effect of MMP inhibitor pre-treatment on the fracture resistance of single versus multiple pin post endodontic restorations: an in vitro study

Background: Bond degradation by dentin MMPs can reduce the longevity of post endodontic restorations. Chlorhexidine may improve bond stability, but its effect with different post systems is not well established. This study assessed whether MMP inhibitor pretreatment enhances fracture resistance in single and multiple pin post restorations. Materials and Methods: Forty single-rooted maxillary premolars were extracted, and their crowns were sectioned at the cementoenamel junction (CEJ), followed by endodontic treatment. After the post space was prepared via a standardized technique, the samples were distributed into four groups: Group 1 , single-fiber post with no dentin pretreatment; Group 2 , single-fiber post with dentin pretreated with a matrix metalloprotein (MMP) inhibitor; 2 %, chlorhexidine solution ( Globus Medisys , Vadodara, Gujarat, India ); Group 3 , multiple Dentapreg pins ( Dentapreg ; ADM , Brno , Czech Republic ) without dentin pretreatment; and Group 4 , multiple Dentapreg pins with dentin pretreated with a MMP inhibitor. Fracture resistance was assessed after post placement and core build-up via a universal testing machine, in which a 45° compressive load was applied at 1 mm/min until failure. The data were analyzed via one-way ANOVA and Tukey’s post hoc test, with significance set at P < 0.05. Results: Group 4 presented the highest mean fracture resistance, followed by Groups 3, 2, and 1, with statistically significant differences ( P < 0.05). Conclusion: Within the limits of this study, the evidence indicated that dentapreg pin posts exhibited greater fracture resistance than single-fiber-reinforced posts did. Additionally, the application of 2% chlorhexidine after etching significantly increased the fracture resistance strength. Clinical significance: Understanding how MMP inhibition influences the performance of different post systems can help clinicians make more informed material choices. This may ultimately support the selection of restoration techniques that offer greater reliability and longevity in endodontically treated teeth.