The study is a within-subject randomized clinical trial that will compare and evaluate patients' satisfaction and digitally analyze denture space Confines. Group I: CAD/CAM. (computer-aided design/computer-aided manufacturing) Conventional complete dentures will be designed based on the bone support concept, Group II: CAD/CAM neutral zone complete dentures will be designed based on the neutral zone concept. The participants will be selected according to inclusion and exclusion criteria and will be randomly allocated into both groups and then shuffled to the other group using the Research Randomizer Program.

This study is designed as a randomized clinical trial applying a within-subject comparison of two different complete denture types as follows; group I: CAD/CAM conventional complete dentures will be designed based on the bone support concept, group II: CAD/CAM neutral zone complete dentures will be designed based on the neutral zone concept. The study will be carried out on twelve completely edentulous patients exhibiting advanced residual ridge resorption, each patient will receive two sets of complete dentures in a random sequence, and each set of CDs will be worn for at least eight weeks after the last recall visit before assessments. Upon delivery of the second set of CDs, the first set will be withheld from the patient. For each denture set, patient satisfaction will be rated using a patient denture assessment PDA questionnaire that will be assessed via a Likert scale, the obtained scores will be used to compare the two denture types. Also by using special digital software, a comparison between group I and II virtual complete denture images will be conducted.

Inclusion Criteria:

1. Patients who have been completely edentulous in both jaws (maxilla and mandible) for a long period.
2. The age of patients ranges from 50 to 80 years old.
3. Patients with a resorbed mandibular ridge.
4. Patients with a Class I maxillo-mandibular relationship
5. Patients with adequate inter-arch space.
6. Patients with good neuromuscular control.
7. Patients without any tempo-mandibular disorder.

Exclusion Criteria:

1. Patients with any oral diseases that may affect complete denture construction
2. Patients with bad oral hygiene.
3. Patients with oral parafunctional habits.
4. Hysterical patients.
5. Patients will undergo or have previously received chemotherapy or radiotherapy.
6. Drug-addicted patients.

Twelve patients will be randomly assigned to one of two groups (I or II) by a practitioner who will not be involved in patient selection or treatment but will be aware of the randomization sequence and have access to the randomization lists. This will be stored on a password-protected laptop, and the randomly generated codes will be placed in sequentially ordered, opaque, and sealed envelopes using a research randomizer (https://www.randomizer.org/). Participants were randomized to first receiving either Conventional CAD/CAM manufactured complete removable dentures Based on bone support concept or CAD/CAM neutral zone complete dentures will be designed based on the neutral zone concept and then after 3 months cross over to the other set. Patients and clinical practitioners are blinded to the type of prostheses at all study times.