Vital pulp therapy: histopathology and histobacteriology-based guidelines to treat teeth with deep caries and pulp exposure

Vital pulp therapy (VPT) encompasses distinct treatment modalities for deep caries that approximate the pulp chamber in vital teeth. Confusion exists in the literature in terms of the indication and rationale for each VPT approach. The objectives of the present study are to elucidate the indications for VPT and to present a set of histopathology and histobacteriology-based guidelines for VPT in teeth with deep caries. Two hundred and sixty-four carious, unrestored and VPT-treated human teeth, which were extracted for reasons not related to the present study. The teeth were processed for histological and histobacteriological examination. Other 757 clinical cases that received different VPT procedures were followed-up to identify success rates, with the longest observational period of 30 years. Follow-up of the clinical cases indicated that direct pulp capping was successful in 73.2%, partial pulpotomy in 96.4% and full pulpotomy in 77.8% of the cases. Histological and histobacteriological examination showed a localised inflammatory response that commonly occurred in the subjacent pulp tissue as soon as the enamel was penetrated by caries. If the softened and infected dentine were completely excavated, without pulp exposure, and the cavity restored with an adequate restoration, pulp inflammation frequently subsided. In teeth showing pulp exposure, the extent of bacterial penetration varied and areas of infection presented severe pulp inflammation, including micro-abscesses. However, the pulp tissue apical to the infected/inflamed area was usually uninflamed and normal. Guidelines based on the present histopathological, histobacteriological and clinical findings are proposed for VPT and mainly involve direct examination of dentine and the exposed pulp tissue under deep caries for decision-making, and require strict asepsis during procedures. Vital pulp therapy following the guidelines proposed in the present article has the potential to improve the outcome of the conservative treatment of mature teeth with deep caries and in some occasions may be an alternative to pulpectomy. A guideline for VPT in the treatment of deep caries is proposed, focusing on direct observation of dentine and the exposed pulp tissue under deep caries. Stringent aseptic techniques are mandatory for VPT procedures to be successful.