Purpose: The aim of this study was to evaluate decision making with regard to detection and treatment of carious lesions on occlusal tooth surfaces and to evaluate the possible costs related to the different treatment plans of a group of clinicians in private practice. Materials and Methods: Forty extracted permanent teeth with no fillings or macroscopic carious cavitations were selected and radiographed, using a standard method similar to bitewing and then mounted in two models. A sample of 130 clinicians in private practice in Piracicaba, Brazil were asked to carry out combined visual-radiographic caries examination of the occlusal surfaces and to recommend possible treatment plans for each surface. Teeth were sectioned bucco-lingually and caries was assessed using a stereomicroscope and classified as either enamel or dentine lesions. The costs of treatments suggested by each examiner were calculated, using a fee scale reported by the Brazilian Federal Council of Dentistry. Results: Most teeth (53.7%) that were found to be sound on histological examination were considered to have enamel lesions. In 85.7% of these cases, the clinicians recommended restorative treatments. There was about 14-fold difference among clinicians concerning the costs related to decision making. Conclusion: Not only did the clinicians overestimate the presence and depth of carious lesions, but they also tended to treat enamel lesions using invasive therapeutic procedures. Great disparities were observed with regard to treatment costs related to decision making. Assuming an in vivo situation, the clinicians may be performing overtreatments and consequently interfering in the quality of patients' oral health. Keywords: caries detection, health care costs, patient care planning