Prospective, Split-mouth, Comparative Study to Compare Clinical Outcomes of Two Different Posterior Composite

Inclusion Criteria: * Each subject must need at least 2 restorations in a vital posterior tooth (in different quadrants) * Restorations may be indicated for caries removal and restoration, replacement of defec-tive restorations (i.e. fractured, stained, unaesthetic), or requested replacement of un-aesthetic restorations. * Must have given written consent to participate in the trial * Must be available for the required follow-up visits over 2 years * Restored teeth must have occlusal contact with opposing teeth or restored teeth * Restoration width should be equal to or greater than 1/3 the distance from buccal to lin-gual cusp tips * 75% of the restorations Class II (minimum) and 25% Class I * One, two or three surfaces per restoration * Each Class II will have at least one proximal contact * 75% in molars (minimum) and 25% in premolars * All restored teeth must have at least one occlusal contact in habitual closure * Must have 20 or more teeth with evidence of bilateral posterior tooth contacts * Teeth that require one or no cuspal build-ups * Vital tooth * Preoperative sensibility on the teeth to be treated at maximum 3 on visual analog scale (10 = maximum) * Patient wishes to be treated in this clinical trial after oral information by the operator and after signing the informed patient form Exclusion Criteria: * Allergies to ingredients of the materials under investigation (monomers) * Do not meet all inclusion criteria above * Have medical complications (organ transplants, long term antibiotic or steroid treatment, cancer or are immunocompromised) or disabilities rendering them unable to tolerate the time required to complete the restorations or to provide adequate oral hygiene * Suffer from xerostomia either by taking medications known to produce xerostomia or those with radiation induced xerostomia or Sjogren's syndrome subjects * Have teeth with advanced or severe periodontitis, rampant caries or poor oral hygiene which may require extraction of the teeth to be restored * Present with any systemic or local disorders that contraindicate the dental procedures included in this study * Patients reporting having severe grinding/bruxing or clenching or in need of TMJ-related therapy * Have tooth with exposed pulp during preparation or caries removal or require indirect pulp capping * Inclusion of teeth that are non-vital or that exhibit signs of pulpal pathology (pulpitis) * If the working field cannot be maintained in a dry state for treatment