It is assumed that the reduction of the flap dimension could provide a reduction of surgical time, post surgical complications and patient's discomfort when compared with the traditional surgical approach.

16 edentulous patients in maxillary posterior area were treated with a bilateral sinus lift procedure. Once enrolled in the study impressions were realised and the radiographic stent prepared, with radio-opaque references fixed in the positions where the implants should be inserted. Pre-surgical CT scan was executed after placing the stent in its proper position in patient's mouth. If no surgical contra-indications were detected at CT evaluation, patients were involved in the study.

Inclusion Criteria:

• patient edentulous in the maxillary posterior area on both left and right side
• residual bone height in the maxillary premolar and molar region less than 4mm

Exclusion Criteria:

• history of systemic diseases that would contraindicate surgical treatment

all the involved patients were edentulous in the maxillary posterior area , bilaterally, with a residual bone heigh of less then 4 mm; for this reason they required a surgical bone reconstruction for implant placement.