Although selective removal of carious tissue to soft dentin (SRCT-S) has been proposed as the standard of care for the management of deep dentin caries, it is unclear whether a cavity liner is necessary. This double blinded randomized controlled clinical trial aims to analyze the behavior of a resin restoration performed after SRCT-S for deep dentin caries, treated either with a Glass Ionomer or only with a Self-Etching Adhesive, in permanent teeth. The study will include 142 restorations allocated to either experimental arm. After 12 and 24 months, restoration survival, pulp response and radiographic lesion progression will be assessed.

Introduction: Minimally invasive dentistry has been proposed as an conceptual framework for the conservative management of caries lesions. This approach allows reducing potential adverse effects derived from the conventional treatment, including the loss of pulp vitality. Complete removal carious tissues compromising deep dentin significantly increases the risk of pulp exposure and post-operative symptoms, leading in many cases, to the need for endodontic treatment, with the subsequent high costs and low coverage for the population. In this context, a new technique for the management of deep caries lesions has been introduced called selective removal of carious tissue to soft dentin (SRCT-S), which partially removes only the outer layer of the affected tissue, leaving carious tissue in the pulpal wall, but not on the lateral walls of the operatory cavity. This procedure has been reported in several studies, with lower clinical time, cheaper cost and lower discomfort for the patient. The SRCT-S aims to preserve pulp vitality, prevent access of nutrients to carious tissue, stopping the caries process and preserving a greater amount of dental structure. Although the SRCT-S technique has proven effective compared to conventional treatments, it is unclear and with insufficient evidence about how to manage the remaining carious tissue and whether a cavity lining agent is needed. This decision may have important clinical implications, but there is no general consensus, strongly suggesting further research. Objective: To analyze the behavior of a resin restoration performed after SRCT-S for deep dentin caries, treated either with a Glass Ionomer or only with a Self-Etching Adhesive, in permanent teeth. Methodology: A double blinded randomized controlled clinical trial was devised. Trained dentists will treat the 142 restorations included in deep dentin carious lesions of permanent molars, at the dental clinics of the University of Talca. After recruiting, patients will be randomly assigned to the experimental groups: Group 1: (n=71) no cavity lining, treating carious tissue with self-conditioning adhesive followed by composite resin restoration and Group 2: (n=71) remaining carious tissue covered with a conventional glass ionomer followed by composite resin restoration. The dependent variables (outcomes) will be; a. clinical: restoration survival and pulp response and b. radiographic: lesion progression. Clinical and radiographic outcomes will be monitored annually at 12 and 24 months. The analysis of the restorations and the pulp response will be performed with Weibull regression. The Friedman test will be applied for the analysis of the data regarding radiographic subtraction, (p≤0.05). Given the lack of studies on the subject with longitudinal evaluations, this project is expected to contribute relevant evidence that impacts the generation of novel guidelines for the management of deep dentin caries. Additionally, the results will contribute evidence to increase the support to a more conservative clinical behavior.

Inclusion Criteria:

• Patients with a permanent molar or premolar with a deep caries lesion that compromises from the inner half of the dentin (determined by radiographic examination).
• Tooth restorable by a direct resin restoration.
• Absence of pulp sensibility verified by cold test
• Absence of a history of spontaneous pain or vertical and horizontal percussion.
• Absence of periapical lesion, verified through periapical radiographs.
• Primary injury.

Exclusion Criteria:

• Systemic conditions with poor control or uncompensated.
• Cervical margin of the cavity in dentin or root cement.
• Tooth already restored or with secondary caries.

Subjects will not know the type of treatment they will receive. The data analysis will be carried out assigning a letter to the treatment arms, and the identity of the arms will not be revealed up until the end of the analysis.