this study is aiming to Assess postoperative complications and bone quality and quantity in augmentation of horizontally atrophic maxillary ridge using a 1:1 mixture of autograft and xenograft particulate bone covered with collagen membrane with the new Sausage technique™ versus using the same mixture covered with titanium mesh.

patients with atrophic maxillary ridge < 4 mm will be selected in this study for augmentation for future implant placement. The full thickness flap will be elevated including one extra tooth on each side of the edentulous area or if completely edentulous 5 mm on each side.. the bone bed will be prepared by cleaning any debris and Multiple decortication holes will be performed with a 2.0 mm round bur. the harvested bone from the chin is then mixed with the xenograft with ratio 1:1 and then put on the recipient site and will be covered with a collagen membrane with the Sausage technique (intervention group) and the other group the graft will be covered with titanium mesh (control group).

flap is repositioned and sutured. followup for 6 months and then CBCT is done. Reopening after 6 months, core biopsy is taken by a 2 mm thickness trephine from the healed augmented bone at the site of implant placement and will be sent for histomorphometric analysis and the bone thickness (buccolingual ) dimension is measured using a caliper and from the CBCT (cone beam CT) the bone width gain will be calculates and recorded.

postoperative complications( infection, wound dehiscence or membrane exposure) will be monitored and recorded.

Inclusion Criteria:

1. Patients with horizontal atrophied maxillary ridge (thin ridge) less than 4mm.
2. All ages and both sexes were included in this study.
3. Patients should be free from any systemic disease that may affect normal healing of bone, and predictable outcome.
4. Patients with physical and psychological tolerance

Exclusion Criteria:

1. Patients with high risk systemic diseases like uncontrolled diabetes mellitus. As uncontrolled diabetes mellitus has a negative impact on normal bone healing. 8
2. Heavy smokers.4
3. Alcohol or drug abuse
4. Gingival bleeding or full mouth plaque index ≥ 25%.4
5. Patients with physical and psychological intolerance. As psychological stress will affect the immune system and patient's fitness including healing capacity. 9
6. Unavailability for regular follow-ups

because the two interventions used in this trial are clearly different and easily recognized by the investigator and the participants. neither the participant nor the investigator could be blinded