This study was designed to evaluate and compare the 2-year clinical performance of two different resin-matrix ceramic inlays

The design of this prospective randomized controlled clinical trial was a split-mouth, two-arm, double-blinded clinical trial, with an allocation ratio of 1:1. The reporting of the trial followed the Consolidated Standards of Reporting Trials (CONSORT) Statement. Twelve adult patients seeking dental treatments in the Conservative Dentistry Department outpatient clinic, Faculty of Dentistry, Mansoura University, were enrolled in the current study with a total of twenty-four compound inlay cavities. Each patient must sign a consent form before participating in the current study. The study was conducted from August 2023 to August 2025 as a part of the doctoral dissertation. Mansoura University's institution's ethics committee approved the form and protocol before conducting the study. The sample size was calculated using the G*Power statistical program. Based on an effect size of 0.4, a significance level of 5% (p < 0.05), and a statistical power of 80%, a minimum of 10 samples per group was required. To compensate for potential dropouts, the total sample size was increased to 12 patients, yielding a total of 24 restorations.

Inclusion Criteria:

1. The presence of two molars with compound proximal carious lesions or defective restorations involving two surfaces (occluso-mesial or occluso-distal cavities) corresponding to Black's Class II, with a severity score of 4 or 5 according to the International Caries Detection and Assessment System (ICDAS)
2. The buccolingual width of lesions should exceed two-thirds of the intercuspal distance.
3. The teeth were required to be vital and free from any periapical radiolucency.
4. The teeth were required to be in normal alignment, in contact with sound adjacent teeth, and have antagonist teeth present in normal occlusion.

Exclusion Criteria:

1. The presence of uncontrolled systemic disease, pregnancy or breastfeeding.
2. Patients with extremely poor oral hygiene, active periodontal disease, or those involving in orthodontic treatment or periodontal surgery.
3. Patients with wear facets and parafunctional habits as clinching and bruxism.
4. Hypersensitive, endodontically treated, non-vital or cracked teeth.
5. Teeth with proximal cavities involving more than two surfaces, those that exhibited pulp exposure during caries excavation and required direct pulp capping, or those with missing cusps necessitating cusp capping.
6. Teeth without proximal contact, missing neighbouring or opposing teeth
7. Patients with known unavailability to attend recall visits, or with known allergy to any component of the study materials.

Data will be available within 6 months for 3 years

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