Statement of the problem: Accurate digital scans of edentulous patients is challenging due to the absence of anatomic landmarks and geometric variations along the dental arch. Whether adding an auxiliary geometric device (AGD) will improve scanning is unclear.

Purpose: The aim of the study is to analyze the accuracy of complete-arch digital scans of completely edentulous arches by placing auxiliary geometric device.

Material and Methods: This in vivo study included patients who received complete arch screw-retained prostheses supported by 4 implants. Seven patients were randomly chosen; a dual scan protocol was performed for digital implant planning. Surgical guide and AGD were 3d printed. Three different data acquisition methods for each individual: Open tray impression digitized by extraoral scanner (EO Group), Intraoral scan by using Medit i600 with AGD (M600 Group), and Intraoral scan (CEREC Primescan; Dentsply Sirona) with AGD (PS Group). A reference model was formed to check the accuracy of these 3 data acquisitions. The framework was designed and printed for the 3 groups to be placed in the reference model to check the passivity. Passivity was tested through modified 1-screw test by measuring the marginal gap by using a digital camera (add magnification). Each framework was placed in the patient's mouth to re-check the passivity, the best one was delivered to the patient after 4 months after osteointegration of the implants.

Inclusion Criteria:

• For a maxillary edentulous patient, the last extraction should be at least six months
• Non-smokers
• 50-70 years of age
• Have good oral hygiene and motivation.

Exclusion Criteria:

• Patients with major systemic diseases that may affect osseointegration
• Uncontrolled diabetes mellitus
• The need for extensive bone grafting in the planned implant site
• Pregnant female patient
• Under bisphosphonate treatment
• Limited mouth-opening for executing the guided implant surgery.