Objective To study the combined effect of simulated occlusal loading and plaque-derived biofilm on the interfacial integrity of dental composite restorations, and to explore whether the effects are modulated by the incorporation of sucrose. Methods MOD-class-II restorations were prepared in third molars. Half of the specimens (n = 27) were subjected to 200,000 cycles of mechanical loading using an artificial oral environment (ART). Then, both groups of specimens (fatigued and non-fatigued) were divided into three subgroups for testing in CDC-reactors under the following conditions: no biofilm (Control), biofilm with no sucrose (BNS) and biofilm pulsed with sucrose (BWS). BNS and BWS reactors were incubated with a multispecies inoculum from a single plaque donor whereas the control reactor was not. The BWS reactor was pulsed with sucrose five times a day. The biofilm challenges were repeated sequentially for 12 weeks. pH was recorded for each run. Specimens were examined for demineralization with micro-CT and load capacity by fast fracture test. Results Demineralization next to the restorations was only detectable in BWS teeth. Fracture loads were significantly reduced by the concomitant presence of biofilm and sucrose, regardless of whether cyclic mechanical loading was applied. Cyclic loading reduced fracture loads under all reactor conditions, but the reduction was not statistically significant. Conclusions Sucrose pulsing was required to induce biofilm-mediated degradation of the adhesive interface. We have presented a comprehensive and clinically relevant model to study the effects of mechanical loading and microbial challenge on the interfacial integrity of dental restorations.
Bibliographical noteFunding Information:
This study was partially supported by the National Institute of Dental and Craniofacial Research (NIDCR), USA through Grant No. 1 R01 DE021366 , the CONICYT Becas Chile Scholarship Program, Chilean Government and a Doctoral Dissertation fellowship, University of Minnesota . In addition, we would like to thank Dr. Robert S. Jones for his contributions to this study. The authors of this manuscript declare that no benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
- Adhesive interface
- Cyclic loading
- Mechanical fatigue
- Oral biofilms
- Resin composite