Overhanging dental restorations (ODR) are a major dental health problem. An ODR is defined as an extension of restorative material beyond the confines of a cavity preparation. They have been strongly implicated as an etiologic factor in the progression of periodontal disease and are alarmingly prevalent. In addition to promoting plaque accumulation, they change a nondestructive subgingival flora to a destructive one. There is good documentation that bleeding, gingivitis, and bone loss increase in tissues adjacent to ODR as compared to homologous teeth. Removal of ODR enhances the effectiveness of the hygienic phase of periodontal therapy. Many ODR, however, are not detected on radiographs and are evident only by use of an explorer directed subgingivally. For this reason and others, many are not removed. This literature review summarizes research concerning the prevalence, significance and removal of ODR.