The aim of the study is to evaluate the clinical performance of new bioactive injectable composite compared to nanohybrid composite during the restoration of posterior cavities

Statement of the problem:

Marginal defects of composite fillings are often thought to be caused by poor adaptation of the restorative material to the cavity wall. To avoid these defects, particularly in posterior teeth, the use of flowable composites has been advocated because of their ability to 'wet' and adapt well to cavity margins and walls. However, flowable composites have a lower filler content and usually weaker mechanical properties than conventional composites.

The continued development of resin composites has led to formulations designed to further simplify the filling procedure, provide better mechanical properties, reduce the effect of polymerization shrinkage stresses and improve aesthetics. Recently, a new type of highly filled flowable composite has been developed. It is characterized by its high viscosity and is claimed to have improved mechanical properties not dissimilar from conventional composite restorative materials. This composite contains nano-sized filler particles, and due to its consistency, the material has been referred to as an 'injectable composite'.

Rationale for carrying out the trial:

The rationale of this study is to evaluate the mechanical performance of injectable composite resin against nanohybrid composites, because of its easy handling, time-saving, better margin adaptation, and the gain of extra mechanical properties at the same time.

Inclusion Criteria:

• Participants:

  1. Age range 20-50 years.
  2. Males Or females .
  3. Co-operative patients approving to participate in the trial.

• Teeth:

  1. class I or II carious lesions premolars and molars.
  2. Vital upper or lower teeth with no signs of irreversible pulpitis and pulpal necrosis.
  3. Presence of favorable occlusion and teeth are in normal contact with the adjacent teeth.

Exclusion Criteria:

• Participants:

  1. Patients with general systemic illness.
  2. Allergic history against any component of used material.
  3. Disabilities.
  4. Pregnancy
  5. Xerostomia.
  6. Lack of compliance.
  7. Evidence of parafunctional habits.
  8. Temporomandibular joint disorders.

• Teeth:

  1. Periapical pathology or signs of pulpal pathology.
  2. Endodontically treated teeth.
  3. Tooth hypersensitivity.
  4. Possible prosthodontic restoration of teeth.
  5. Heavy occlusion and occlusal contacts or history of bruxism.
  6. Severe periodontal affection.