On the necessity of complete caries excavation: a narrative review

Selective caries excavation is recommended as an alternative to complete (non-selective) caries excavation. In the selective procedure, a thin layer of caries-altered dentine is left in deep cavities to avoid pulp exposure and the tooth is restored with a definitive bacteria-proof (sealed) restoration in the same appointment. The theory behind selective caries excavation is that leaving carious dentine in deep lesions is not a problem, because the cavity is sealed by an adhesive restoration. Thus, the remaining bacteria are cut off from any substrate, “starve”, and the caries cannot progress. However, not only cariogenic bacteria, which are dependent on a supply of substrate in the form of carbohydrates, occur in carious dentine, but also anaerobic asaccharolytic bacteria, which can metabolise proteins from demineralized collagen. These bacteria remain active even under adhesive restorations and lead to inflammation of the pulp tissue. In addition, endotoxins, which are released by decomposed (“starved”) microorganisms, diffuse through the dentine and also lead to pulp inflammation. Even if patients often have no clinical symptoms (pain, radiological signs of inflammation), histological examinations have shown that a chronic inflammatory reaction of the pulp is present after selective caries excavation. Consequently, the absence of clinical symptoms does not mean that the pulp tissue is healthy, nor can the actual condition of the pulp be determined using a sensibility test after selective caries excavation (free of inflammation or not). Thus, studies based on these clinical criteria are irrelevant for drawing conclusions about the success of selective caries excavation. A higher probability of success using selective caries excavation compared to vital pulp therapy (direct capping, pulpotomy) cannot be determined per se. Therefore, complete caries excavation should be favoured in order to prevent bacterial contamination and thus preclude development of a chronic inflammatory reaction of the pulp. After non-selective caries excavation, vital pulp therapy should be performed by using a calcium silicate cement for pulp capping before an adhesive restoration is subsequently placed. When performed correctly, this treatment has been shown to achieve higher success rates than selective caries excavation.