the aim of this study is To evaluate and compare the clinical performance of Self- Cure Bulk fill Composite Resin Versus Conventional Bulk fill resin composite in Restoration of Proximal Lesions over a Period of 24 months Follow-up.

Examination and selection of all patients will be done according to inclusion and exclusion criteria. A class II cavity will be prepared after local anesthesia has been given as required. Sectional matricing and wedging will be done.Followed by, placement of restorative material according to the randomization sequence.

For the intervention: The sectional matrix will be applied first, followed by filling of cavity with Self-Cure bulk-fill Resin Composite. (Stela Automix or Stela Capsule, SDI Ltd, Australia) For the control group: The sectional matrix will be applied first, followed by filling of the cavity with the bulk-fill resin composite material (Tetric N-Ceram Bulk Fill, Liechtenstein). Clinical evaluation will be done using USPHS criteria at 6,12,18 and 24 monthes follow up

Patient-related criteria:

Inclusion criteria:

• Patients consulting in one of the outpatient clinics listed above.
• Able to tolerate necessary restorative procedures.
• Provide informed consent.
• Accepts the 18 months follow-up period.

Exclusion criteria:

• Medically compromised patients, as they will not be able to attend multiple appointments or may require special management.
• Pregnant women; as radiographs cannot be taken for them.
• Allergy to any of the restorative materials, including anesthetics.
• Uncooperative patients, will not abide by the instructions or attend the appointments.

Tooth related criteria:

Inclusion criteria:

• Teeth with primary proximal carious lesions.
• Teeth are vital according to pulp-sensitivity tests.
• Well-formed and fully-erupted in normal functional occlusion with natural antagonist and adjacent teeth.

Exclusion criteria:

• Deciduous teeth; as the study is targeting only permanent teeth.
• Teeth with previous restorations, which may add another variable to the study (type of old restorative material, extent of recurrent caries).
• Spontaneous pain or prolonged pain after sensitivity tests (cold and electrical tests), which would indicate irreversible pulpal damage.
• Negative sensitivity tests, periapical radiolucencies and sensitivity to axial or lateral percussion, which would indicate pulp necrosis.
• Teeth presenting external or internal resorption, with adverse pulpal reactions which may affect the outcome of the study.
• Teeth with cervical caries; which can't be evaluated on periapical radiographs.