DIAGNOSIS/TREATMENT/PROGNOSIS ARTICLE ANALYSIS &EVALUATION ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION In vivo degradation of resin-dentin bonds in humans over 1 to 3 years. Hashimoto M, Ohno H, Kaga M, Endo K, Sano H, Oguchi H. J Dent Res 2000;79(6):1385-91. REVIEWERS Laura Tam, DDS, MSc Asbjorn Jokstad, DDS, PhD PURPOSE/QUESTION Is the strength of resin-dentin bonds of restorations placed in primary teeth reduced over time in vivo? SOURCE OF FUNDING Government (Grant-in Aid for Scientific Research No. 11470401 from the Ministry of Education, Science and Culture, Japan) TYPE OF STUDY/DESIGN Cohort study LEVEL OF EVIDENCE Level 2: Limited-quality, patient- oriented evidence STRENGTH OF RECOMMENDATION GRADE Not applicable J Evid Base Dent Pract 2010;10:21-22 1532-3382/$36.00 Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jebdp.2009.11.011 The Bond Between Resin Composite Restorations and Dentin may Degrade in the Mouth Over Time SUMMARY Subjects The subjects were outpatients who attended the Department of Pediatric Dentistry of Hokkaido University for treatment of caries. The laboratory study of the dentin-restoration interface of the pulpal wall of Class II com- posite resin restorations in extracted deciduous molars were collected from 2 different sources. The first source was restored teeth from a prospective cohort with up to 3 years of observations (n = 22), and the second source was intact teeth from a cross-sectional convenience sample that were subse- quently prepared using the same restorative materials and procedure as in vivo and restored extraorally (n = 13) as control specimens. Ethical approval was obtained by the appropriate institutional review board. Key Exposure/Study Factor The primary study factor was the length of time spent by the resin-dentin bond in the oral cavity: (1) control (24 hours in distilled water only); (2) 1 to 2 years; or (3) 2 to 3 years. Main Outcome Measure The primary outcome measure was the integrity of the resin-dentin bond, measured within 2 weeks of tooth extraction represented by microtensile bond strength and by micromorphometric measurements of the fracture surfaces in a scanning electron microscope. Main Results There were significant differences in microtensile bond strengths among all 3 groups—control group, 28.3 6 11.3 MPa; 1 to 2 years, 15.2 6 4.4 MPa; 2 to 3 years, 9.1 6 5.1 MPa (P < .05)—to suggest that the structural integrity of resin-dentin bonds decreased over time. The investigators related the charac- teristics of the microstructure of the fractured specimens to the observed re- ductions in microtensile bond strength and attributed this association to in vivo degradation of adhesive and composite resin and of exposed collagen lo- cated in the demineralized dentin beneath the resin-impregnated hybrid layer. Conclusions The authors concluded that degradation of resin-dentin bond structures occurs after aging in the oral cavity. COMMENTARY AND ANALYSIS This article presented new information regarding the effectiveness of resin- dentin bonds over time in vivo. The vast majority of resin-dentin bond stud- ies are conducted in vitro for short time periods. Significant improvements have been made to dentin-bonding agents, as demonstrated by increasing bond strength results measured in the short term. This in vivo study con- firmed in vitro aging studies conducted in water and highlighted the