Background: Dental implants provide a functional and esthetic replacement for missing teeth. Many individuals with edentulous posterior maxilla often present inadequate bone volume and vertical height between the floor of the sinus and the edentulous ridge due to the maxillary sinus pneumatization, rendering it inadequate to accept a dental implant. Many different methods have been developed for entering the sinus cavity and elevating the Schneiderian membrane to place various bone graft materials to create adequate bone volume for implant placement. These procedures are aimed at inducing new bone formation in the space created between the bony walls of the sinus cavity and the elevated Schneiderian membrane so that dental implants can be placed after adequate osteogenesis to allow for implant-supported restorations to be constructed.

The aim of this retrospective study was to determine the early failure rate of the implants that placed in the posterior maxilla with and without sinus bone augmentation that require removal or have already been lost before or at abutment connection.

Methods: This retrospective study was performed at Saint Louis University Center for Advanced Dental Education and Southern Illinois University School of Dental Medicine. Electronic records (Dentrix, Axium) of patients who underwent dental implant placement in the posterior maxilla with or without sinus bone augmentation in the Department of Graduate of Periodontics in Saint Louis University from 2002 to 2017 and Department of Graduate of Dentistry in Southern Illinois University School of Dental Medicine from 2007 to 2017 were analyzed. Information was gathered concerning length and diameter of implant placed, the method of sinus augmentation, location of surgery in the mouth, patient's history of smoking, diabetes. The early failure rate of the implants that placed in the posterior maxilla with and without sinus bone augmentation that require removal or have already been lost before or at abutment connection was recorded. Statistical analysis of the data was performed. Statistical analysis of the data was performed.

Results: This study included 2324 implants that were placed for 1256 patients (786 female, 470 male). Their ages ranged from 20 to 92, with median age of 62. 72 patients were smokers and 51 of them were diabetic. 594 implants (25.55% of the total implants) were placed in sites that had maxillary sinus augmentation using a crestal approach. 22 of those implants failed (3.7%). 418 implants (17.98% of the total implants) were placed in sites which had maxillary sinus augmentation using a lateral window approach. 10 of those implants failed (2.39%). 88 implants (3.78% of the total implants) were placed in sites that had maxillary sinus augmentation using both crestal and lateral window sinus graft approaches. 2 of those implants failed (2.27%). 1398 implants (60% of the total implants) were placed in sites with no sinus augmentation. 73 of those implants failed (5.2%).

The comparison of early failure rate between the implants which were placed in sites with a crestal sinus augmentation approach and the implants which were placed in sites without sinus augmentation revealed no significant difference (P=0.8871).

The comparison of early failure rate between the implants which were placed in sites with a lateral sinus augmentation approach with the implants which were placed in sites without sinus augmentation revealed no significant difference (P=0.8123).

Finally, the comparison of early failure rate between the implants which were placed in sites with both crestal and lateral sinus augmentation approaches with the implants which were placed in sites without sinus augmentation revealed no significant difference (P=0.9049).

Conclusions: No significant differences were found for the early failure rates of implants placed in maxillary posterior sites (occur before or at abutment connection or before occlusal loading takes place), when comparing the implants which placed in sites with lateral, crestal or both sinus augmented and non-augmented groups.