Resumo BACKGROUND: This study explored the attitude of registered dentists in Biscay towards prescribing antibiotics and/or antiseptics to prevent potential infections after surgical extraction of completely bone-impacted third molars in otherwise healthy individuals, with no history of infection. MATERIAL AND METHOD: We sent letters to 931 registered dentists in Biscay, with an explanation of the study objectives, description of a case of lower third molar impaction, including a panoramic radiograph, and a questionnaire. The questionnaire asked whether they would prescribe antibiotics and/or antiseptics, in the hypothetical case of lower third molar extraction surgery presented, and if so, when, what type, at what dose and how long for. RESULTS: The questionnaire was completed by 261 dentists (28%), with a mean age of 44.3 years old (SD 11.05) and mean of 18.7 years working as a dentist (SD 9). A total of 216 dentists (82.7%) considered it necessary to prescribe antibiotics. Of these, 126 (58.3%) would prescribe amoxicillin and 74 (34.5%) amoxicillin/clavulanic acid, while 129 dentists (59%) would prescribe antibiotics both before and after surgery and 10 (4.6%) only after surgery. The most common doses were amoxicillin 500 mg or 750 mg every 8 hours, and amoxicillin/clavulanic acid 875/125 mg every 8 hours, in both cases for a mean of 7 days. Further, 74 dentists (28%) said they would use immediate post-extraction socket irrigation with chlorhexidine, while 211 (81%) would prescribe antiseptics in the postoperative period, of whom 97% recommended chlorhexidine. We did not find significant differences in the use of antibiotics or antiseptics by dentist age (ANOVA p=0.22 and p=0.53, respectively), or professional experience (ANOVA p=0.45 and p=0.62). CONCLUSIONS: In our sample, the prophylactic prescription of antibiotics and/or chlorhexidine is widespread in clinical practice, in most cases amoxicillin and amoxicillin/clavulanic acid for a week, starting the treatment before surgery.