Obese patients are at risk of dental erosion due to micronutrient deficiency, consumption of soft drinks, gastric reflux disease and vomiting. The present study evaluates the presence of dental erosion in obese patients before and after bariatric surgery using the BEWE (basic erosive wear examination) scoring system. A total of 62 patients with severe obesity were included in the analysis, 31 in the control group (without bariatric surgery) and 31 in the surgery group (after bariatric surgery). BEWE scores did not vary between groups. Vitamin D deficiency was detected in 19 patients in the control group and three in the surgery group (p < 0.001). The serum calcium and vitamin D values were significantly higher in the surgery group (p = 0.003, p < 0.001 consecutively). All patients after bariatric surgery showed compliance with supplements, including vitamin D and calcium daily. Patients after bariatric surgery were less likely to drink soft drinks regularly (p = 0.026). Obese patients, before or after bariatric surgery, are at risk for erosive dental wear. However, with sufficient education prior to surgery and consistent intake of vitamin and mineral supplements, significant erosive dental wear after bariatric surgery could be avoided. Regular dental examination should be included in the check-up and follow-up program.