Evaluation of computer guided placement of Zygomatic implants utilizing intra sinus versus extra sinus surgical approach for the reconstruction of atrophic maxilla. The expected benefit from the current study is to select the most suitable approach for Zygomatic implant placement with the least postoperative complications

During the last ten years, there has been an increase in the number of edentulous patients looking for and seeking out rehabilitation. Formerly, individuals with edentulous maxilla and mandibles were rehabilitated with removable complete dentures, but it was associated with poor patients' satisfaction.

Alveolar bone atrophy results from loss of bony support due to the physiological process that naturally takes place after tooth loss, especially in the upper arch. Due to its shape and structure, the maxilla is an extremely challenging arch to reconstruct with dental implants.

Oral and Maxillofacial surgeons began utilizing alternative methods to replace missing teeth with osseointegrated dental implants in atrophic maxilla. As a result, different methods were developed for handling of this issue, including tilted implants, sinus elevation, the use of Pterygoid implants, the use of short implants and Zygomatic implants.

Inclusion Criteria:

1. Patients with severely atrophic edentulous upper arch (Cawood class IV, V, VI) that could not be restored by other type of treatment
2. Patients who had at least 8-12 mm vertical bone height in anterior maxilla to allow installation of 2 conventional implants.
3. Lacking posterior maxillary bone support due to significant sinus pneumatistion
4. Good systemic health (ASA score I-II)
5. Highly motivated patients.

Exclusion Criteria:

1. Patient not willing to give his/her informed consent.
2. Patients with systemic disease that did not permit the surgical procedure (including general anaesthesia).
3. Patients with uncontrolled diabetes or under bisphosphonate therapy.
4. Heavy smoker.(> 20 cigarettes daily)
5. Patient with psychiatric problems, severe bruxism or other parafunctional habits.
6. Acute sinusitis.
7. Malignancy or pathology in Maxilla or Zygoma.

Each patient will be given a code by the researcher and the observers will be blind to which group this case belong. Patients, radiographic outcome assessor and statistician will be blinded.