Composite resins for posterior tooth restorations have become a viable alternative to dental amalgam. Failures sometimes cannot be easily explained, and we hypothesize that a genetic component may influence longevity of restorations. We aimed to determine if there is any evidence for a difference in the performance of amalgams versus composite resin in extensive posterior restorations. We also aimed to determine if risk factors such as age, sex, smoking tobacco, alcohol drinking, diabetes status, and periodontal health status may have a role in the failures of extensive anterior composite restorations. Finally, we investigated if genetic variation in matrix metalloproteinases that are present in the mineralized dentin is associated with failure of composite resin. The data used to perform this research were obtained from the Dental Registry and DNA Repository project after screening 4,856 patients. All restorations were evaluated at times of 1, 2, and 5 years after the restoration placement. 6,266 amalgam and 2,010 composite restorations were analyzed in a total of 807 patients in a period of approximately 10 years (period corresponding to the database existence). An additional 443 extensive direct composite resin restorations in anterior teeth were also studied. Failure rates of amalgam and composite restorations are similar, and by the end of 5 years, composites outperformed amalgams slightly. Failures of anterior composite restorations occurred more often in males who smoked tobacco (p = 0.05), despite a similar number of females and males that smoked tobacco in the sample (116 individuals smoked tobacco, 54 females and 62 males). Alcohol drinking increased failure rate within 2 years (p = 0.03). We found a statistically significant association between matrix metalloproteinase 2 rs9923304 and failure of composite restorations (p = 0.007). Composite resins can replace amalgam restorations. Smoking tobacco and drinking alcohol will increase the chance of restoration failure.

This work aimed to further evaluate the association of MMP20 rs1784418 C>T and dental caries experience with the hypothesis that MMP20 rs1784418 C>T is a risk factor for dental caries. 184 children 4-7 years of age had their caries experience determined and buccal cheek swabs collected for DNA extraction to test for association with the MMP20 rs1784418 C>T using standard statistical approaches. A meta-analytic approach was also implemented to compile previous discrepant reports of the same association. We found an association between MMP20 rs1784418 C>T and dental caries experience in primary dentition (p = 0.01). The meta-analysis showed that this association appears to favor individuals born in Brazil and not Turkey. MMP20 rs1784418 C>T appears to protect against dental caries, but its effects are likely to be more marked in certain populations.