A Histobacteriological Reappraisal of Contemporary Deep and Extremely Deep Caries Management Recommendations

The 2026 European Federation of Conservative Dentistry-European Society of Endodontology-Organisation for Caries Research guideline recommends selective or stepwise caries removal for deep caries to reduce pulp exposure and preserve tooth structure. However, avoiding exposure does not establish the absence of pulpal infection. This histology-referenced study tested whether radiographic classification as deep or extremely deep caries was associated with bacterial penetration into the pulp. The null hypothesis was that there was no association.

Thirty-two extracted permanent teeth with carious lesions approaching or involving the pulp were examined. Two blinded examiners classified preoperative periapical radiographs by consensus using the European Society of Endodontology criteria. One tooth was unclassified. Demineralized sections stained with hematoxylin and eosin and Taylor's modified Brown and Brenn stain were evaluated for bacterial penetration and pulpal inflammation. Fisher's exact test assessed the association.

Sixteen teeth were classified as deep caries and 15 as extremely deep caries. Bacterial penetration was identified in 13 of 16 deep lesions (81.2%) and 13 of 15 extremely deep lesions (86.7%), for an overall frequency of 26 of 31 teeth (83.9%). Most affected teeth showed moderate or extensive inflammation. No significant association was detected between the radiographic category and bacterial penetration (P = 1.000).

The null hypothesis was not rejected. In this extraction-enriched cohort, radiographic depth and absence of exposure did not reliably identify pulps without bacterial invasion. Selective and stepwise caries removal may remain clinically useful, but their outcomes should not be interpreted as proof of pulpal health. Clinical and patient-centered outcomes should be considered with tissue-level evidence when evaluating infection and healing.