[Clinical evaluation of two transalveolar methods for sinus augmentation with placing 1 204 implants immediately]

Objective: To compare the clinical outcomes of posterior maxillary implant surgery when using the regular transalveolar approach or with the crestal approach-sinus (CAS-KIT), a device for maxillary sinus membrane elevation by the crestal approach using a special drilling system and hydraulic pressure. Methods: In this retrospective study 887 patients during Jan 2012 to July 2015 in Hangzhou Dental Hospital with underwent either regular transalveolar approach or CAS-KIT approach for maxillary augmentation; whereas 11 patients dropped out for the reason of serious membrane perforations. Totally, 876 patients with 1 204 plants, placed immediately after transalveolar maxillary augmentation, were included in this study. The data analysis was performed by radiological measures to assess the changes in height of maxillary sinus floor after the transalveolar augmentation at different time points. In addition, the complications after surgery, failure rates, osseointegration condition and the performance of rehabilitation were evaluated as well. Results: Five hundred and three patients were experienced with regular transalveolar approach, and 7 patients were drop out for the serious membrane perforations. Thus, 496 patients received 653 implants in this group; the average lifted range in maxillary sinus floor height changes was (4.08±3.45) mm. The complications were minor membrane perforations during procedure in 64 patients, postoperative maxillary sinus infection happening in 2 patients and 13 patients experienced rehabilitation failure. Three hundred and eighty-four patients had CAS-KIT approach with 4 patients dropped out. Three hundred and eighty patients get 551 implants with the mean lifted range of (8.36±4.07) mm in maxillary sinus floor height changes. Minor membrane perforations during procedure occurred in 31 people and 2 got postoperative maxillary sinus infection. The 4 year overall survival rate of 1 204 implants was 97.26%, with four implants fell off after 3 months of rehabilitation and one implant occurred after one year of rehabilitation. Conclusions: The regular transalveolar sinus lift technique is easier and time saving, but the compromised lifting range in maxillary sinus floor height and the comparatively high occurrence of intraoperative membrane perforations should be concerned. Using CAS-KIT could be an alternative method to perform maxillary sinus augmentation with a reduced incidence of complications. There was no statistically difference in implant failure rates and incidence of postoperative maxillary sinus infection between two groups.