Background. The authors aimed to determine whether dentists in practices belonging to The Dental Practice-Based Research Network (DPBRN) were more likely to repair or to replace a restoration that they diagnosed as defective; to quantify dentists' specific reasons for repairing or replacingrestorations; and to test the hypothesis that certain dentist-, patient- and restoration-related variables are associated with the decision between repairing and replacing restorations. Methods. This cross-sectional studyhad a consecutive patient and restoration recruitment design. Practitioner-investigators (P-Is) recorded data for consecutively seen restorations inpermanent teeth that needed repair or replacement. The DPBRN is a consortium of dental practitioners and dental organizations in the United Statesand Scandinavia. The collected data included the primary reason for repairorreplacement, tooth surface or surfaces involved, restorative materials used and patients' demographic information. Results. P-Is collected data regarding 9,484 restorations from 7,502 patients in 197 practices. Seventy-five percent (7,073) of restorations were replaced and 25 percent (2,411)repaired. Secondary caries was the main reason (43 percent, n = 4,124)for treatment. Factors associated with a greater likelihood of repairing versus replacing restorations (P<.05) included having graduated from dental school more recently, practicing in a large group practice, being the dentistwho placed the original restoration, patient's being of an older age, the original restorative material's being something other than amalgam,restoration of a molar and the original restoration's involving fewer tooth surfaces. Conclusions. DPBRN dentists were more likely to replace thanto repairrestorations. Secondary caries was the most common reason forrepairing orreplacing restorations. Certain dentist-, patient- and restoration-related variables were associated with the repair-or-replace decision.Clinical Implications. The selection of minimally invasive treatment for an existingrestoration is critical, as it may affect the longevity of thetooth.