Dental model cast accuracy can be affected by many variables as tray material, impression material and time elapsed before pouring the impression. All these factors would affect the accuracy of the surgical guide

Impression inversion with markers technique avoids the dimension changes that may happen from pouring of the dental model cast. Also it saves time as no need for optical scan of the model cast and for scan appliance even in cases of multiple restoration. Adding markers to impression tray ensures an accurate merge even if the patient has restored dentition that may cause scatter during the CT/CBCT scan.

This study will is for Assessment of the Accuracy of Surgical Guide designed from Dental Model Optical Scan versus Impression Inversion with Markers techniques in Computer Guided Implantology.

Inclusion Criteria:

1. Partially Edentulous patients seeking for dental implants

2. Patients with Bucco-lingual bone thickness more than 6 mm allowing flapless implant placement.

3. Medically free patients.

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   Exclusion Criteria:

1- Patients with thin ridges. 2- Patients with systemic disease that may affect bone quality. 3- Patients with poor oral hygiene and active periodontal diseases. 4- Anatomical situations requiring regenerative procedure. 5- Completely edentulous patient 6-Patient with limited mouth opening

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Each patient will be given a code by the researcher (A.A) and the observers will be blind to which group this case belong.

Patients, evaluators and data analyst will be blinded