This study will evaluate the performance of three different tooth-colored onlay materials in adult patients' posterior teeth. First, investigators will use a bulk-fill composite resin to raise the cavity margin above the gum line and below the contact point. Then each patient will receive three onlays made from different materials. Investigators will follow patients at 2 weeks, 6 months, 18 months, and 24 months to assess how well the onlays fit, function, and whether restorations cause sensitivity or new decay. The results will help dentists choose the most durable onlay restorations for deep-margin elevation cases.

Inclusion Criteria:

1. Molar tooth with proximal subgingival carious lesion of ICDAS 4 or 5, causing weakening of one or more cusps.
2. Normal alignment with the adjacent and opposing teeth.
3. Acceptance of the follow-up period and recall visits for 2 years.

Exclusion Criteria:

1. Distance between the gingival margin and the crestal bone < 2 mm.
2. The tooth would require direct pulp capping.
3. Poor oral hygiene (or not completing the oral hygiene phase).
4. Chronic periodontitis.
5. Pulpitis or non-vital tooth.
6. Orthodontic treatment.
7. Parafunctional habits.
8. Systemic disease.
9. Pregnancy.
10. Teeth act as abutment for fixed or removable prosthesis.
11. Occlusion of fewer than 20 teeth