Background: Patient specific surgical guides (PSG) have been widely used to achieve a precise 3D implant position. However, they prevent external cooling systems from reaching the osteotomy site sufficiently. So, heat generated during guided implant surgery is greater than free hand technique. Adding internal irrigation channel to the conventional surgical guides allows better diffusion of irrigation to the osteotomy site and reduces heat generation.

Aim of the study: Is to introduce a patient specific surgical guide design with internal irrigation system and compare it to the conventional surgical guide with external irrigation clinically through bone temperature, implant stability and radiographically by CBCT through crestal bone loss and bone density.

Inclusion Criteria:

• Patient with missing mandibular posterior premolar or molar teeth.
• Tooth extraction at the implant sites was performed at least 4 months before the surgery.
• Residual alveolar bone height more than 10 mm.
• With minimum alveolar bucco-lingual dimension of 6 mm.
• Free from any systemic disease or local pathological lesions that may affect bone healing or contraindicate implant placement.

Exclusion Criteria:

• Severe atrophic alveolar ridge (height less than 10mm, width less than 6mm).
• Bad oral hygiene ( Silness-Löe index (score 2-3).
• Heavy smoker (smoke greater than or equal 25 cigarettes per day).
• Presence of acute infections or periapical lesions in adjacent teeth.
• Parafunctional habits.
• Pregnant females.