this study aims to compare the clinical performance of hard hybrid ceramics and composite resin indirect restorations fabricated by CAD/CAM technology for the vital teeth with occluso-proximal cavities. the clinical performance assessed include marginal adaptation primarily and in addition to Color match, marginal discoloration, aesthetic anatomic form, recurrent caries and restoration fracture and post-operative hypersensitivity. the clinical performance will be assessed after the restoration cementation, after 6, 12, 18 and 24 months.

A wide variety of materials is now available for the fabrication of indirect restorations used to manage extensive carious lesions, including high-strength ceramics, hybrid ceramics, and resin-composite blocks. Each material offers distinct advantages in strength, wear resistance, aesthetics, and bonding performance, thereby expanding treatment options for severely compromised posterior teeth. However, these differences in mechanical and optical behavior, marginal adaptation, and long-term durability under functional stresses complicate clinical material selection.

Limited data is available comparing the clinical performance of these materials, particularly in large cavities in these regions. More information is needed on how they prevent post-treatment sensitivity, maintain edge quality, and resist discoloration, wear, and fractures.

Though short-term studies indicate excellent survival rates and aesthetic results for CAD/CAM hybrid ceramic inlays (more than 90% survival after two years), and systematic reviews imply that CAD/CAM resin composite inlays match ceramic restorations (success rates ranging from 85.7% to 100% for composites versus 93.3% to 100% for ceramics). There is a lack of direct clinical comparisons between these two material types in vital molars with occluso-proximal cavities. Much of the existing research is constrained to onlay designs or mixed-material groups, creating a significant gap in understanding which CAD/CAM block type delivers superior long-term performance for inlay restorations in vital teeth.

Inclusion Criteria:

• Systematically healthy male or female subjects aged 16 to 50 years.
• Patients with good oral hygiene.
• Presence of a single vital molar with coronal destruction due to caries, defined as radiographic evidence of caries involving more than 50% of the total dentin thickness with loss of at least one proximal wall.
• Cavitary preparation involving loss of at least one proximal walls (mesial and/or distal), with intact buccal and lingual walls, and all cavosurface margins located in enamel.
• Presence of functional opposing teeth in stable occlusion

Exclusion Criteria:

• Presence of systemic diseases (e.g., uncontrolled diabetes, immune disorders).
• Current pregnancy or lactation.
• Documented allergy to resin-based composites or adhesive systems.
• Evidence of pulpal necrosis or previous endodontic treatment in the target tooth.
• Presence of cracks or fractures involving the tooth structure.
• Active localized or generalized periodontal disease.
• Evidence of parafunctional habits, including bruxism or clenching.
• High caries risk.