the aim of this study is to compare the influence of different palatal vault configurations on the accuracy and scan speed of IO scans in cases of completely edentulous arches. The null hypothesis is that there is no difference in scanning time, and trueness and precision of IO scans between class I, II and III palatal vault configurations.

A reference model will be created for each of the three groups with different palatal vault configurations. PVS material (DMG Silagum, Germany) will be used for impressions in a one-step process by an experienced operator, and type IV plaster (Heraeus, Germany) will be used to produce the models. These models will then bedigitized by an experienced operator using an extraoral scanner (Trios 3; 3Shape, Copenhagen, Denmark). The STL scan file of the maxillary model will be imported into CAD software (Meshmixer; Autodesk, San Rafael, CA, USA) to generate a reference file. Reference markers will then be added to the digital files to aid the superimposition process during digital subtraction operations.For intraoral scans, the entire maxilla of each patient will be digitally captured using an intraoral scanner (TRIOS POD, 3Shape, Copenhagen, Denmark).According to ISO standards, specifically ISO 5725-1, the accuracy of digital impressions obtained with intraoral scanners (IOS) will be evaluated according to two main parameters: trueness and precision.

Inclusion Criteria:

• 1. Full tooth loss in the maxilla; 2. Absence of infectious diseases; 3. Systemic good health; 4. Age between 50 and 75 years; 5. Willingness to cooperate throughout the data collection process

Exclusion Criteria:

• Exclusion criteria included: 1. Presence of any remaining teeth; 2. Inability to comprehend the study's objectives and procedures; 3. Palatal defect or lesion; 4. Postoperative scarring on the palate; 5. Limitations in mouth opening.

All eligible participants who will comprehend the study's purpose and expresse their willingness to take part and sign a consent form will be enrolled in the study. The subjects will consist of dental patients who were seeking treatment for complete tooth loss in either the upper or lower jaw, or both. A total of thirty patients with complete edentulism, attending the outpatient clinic of MSA University, will be recruited for this research.