This study aimed to evaluate the 12-month clinical performance of direct composite restorations by placing polyethylene fibers in different directions in endodontically treated posterior teeth. In this clinical study, Clearfil SE Bond (Kuraray/Japan) adhesive system, G-aenial Universal Injectable (GC/Tokyo, Japan), G-aenial A'chord (GC/Tokyo, Japan) composites, and polyethylene fiber (Ribbond, USA) were used. In the restoration of the teeth included in the study, polyethylene fiber was placed in different directions according to the amount of remaining tooth tissue and cavity preparation. The restorations were divided into three groups according to the direction of fiber placement ('O' shape, mesiodistal I shape, buccolingual I shape) (n=12). Restorations were evaluated according to modified USPHS criteria in 1st week and 6th months from the placement date. The Chi-square test was used for statistical analysis of the difference between the groups, and the Cochran Q test was used for the significance of the difference between time-dependent changes within each group (p<0.05).

Inclusion Criteria:

A patient presenting with;

1. over 18 years of age
2. a normal periodontal status and good general health
3. endodontically treated premolar and molar teeth
4. teeth in contact with the opposing tooth and subjected to normal occlusal forces
5. attend follow-up appointments

Exclusion Criteria:

1. poor oral hygiene status
2. those with severe or chronic periodontitis
3. absence of adjacent and antagonist teeth
4. potential behavioral problems (e.g. bruxism)
5. allergy to any product used in the study
6. systemically unhealthy
7. pregnant and lactating women