This clinical trial aims to evaluate dentin bridge formation over the pulp following selective caries removal in permanent teeth with deep carious lesions (ICDAS scores 5-6). A total of 66 patients will be enrolled and randomly allocated to receive either a bioactive restorative system (bioactive universal adhesive combined with a bioactive bulk-fill resin composite) or a conventional non-bioactive restorative system. Clinical assessments, including pulp sensibility testing and patient-reported pain evaluation, together with three-dimensional radiographic analysis using cone beam computed tomography, will be conducted to assess the thickness and quality of reparative dentin bridge formation. Outcomes will be evaluated at baseline and during follow-up periods extending up to 24 months to compare the effectiveness of both restorative approaches in preserving pulp sensibility and promoting dentin-pulp complex repair.

This randomized controlled clinical trial is designed to evaluate the clinical and radiographic outcomes of a bioactive restorative system compared with a conventional restorative system following selective caries removal in permanent molars with deep carious lesions (ICDAS scores 5-6).

A total of 66 eligible patients will be recruited according to predefined inclusion and exclusion criteria and randomly allocated into two parallel groups. After selective removal of carious dentin to soft dentin, cavities will be restored using either a bioactive restorative system (bioactive universal adhesive combined with bioactive bulk-fill resin composite) or a non-bioactive restorative system (conventional universal adhesive and bulk-fill resin composite).

Clinical assessments will include evaluation of pulp sensibility and patient-reported pain, while radiographic assessment of dentin bridge formation-regarding presence, thickness, and quality-will be performed using three-dimensional cone beam computed tomography. Outcomes will be evaluated at baseline and during follow-up periods extending up to 24 months to compare the effectiveness of both restorative approaches in preserving pulp vitality and promoting dentin-pulp complex repair

Inclusion Criteria:

Patient-related criteria:

1. Adult patients (age: 18-40 years) of both genders.
2. Good oral hygiene.
3. Willing to sign the informed consent.
4. Cooperative patients who accept the follow-up period.

Tooth-related criteria:

1. Posterior permanent caries (ICDAS 5-6).
2. Radiographically, caries is extending 50% of dentine with a radiopaque layer between the carious lesion and the pulp chamber.
3. Sensitive teeth according to the cold pulp test.
4. Negative response in percussion test.

Exclusion Criteria:

Patient-related criteria:

1. Allergy to any of the restorative materials.
2. Patients undergoing orthodontic treatment with fixed appliances.
3. Pregnant women.
4. Patients with debilitating systemic diseases.
5. Patient who frequently uses analgesics or any drugs that could mask the pain.

Tooth-related criteria:

1. Teeth with previous restorations.
2. Spontaneous pain or prolonged pain (more than 15 s) after the sensitivity test (cold test), which would indicate irreversible pulpitis.
3. Negative sensibility tests, periapical radiolucency, and sensitivity to axial or lateral percussion.
4. Mobile teeth, indicating periodontal disease or trauma.
5. External or internal resorption.
6. Chipped teeth or Cuspal loss

This is a double-blinded trial: participants and outcome assessors/analysts will be blinded to treatment allocation. The operator (E.H.) cannot be blinded due to differences in handling and placement of the two materials