BACKGROUND: After tooth loss, the posterior maxilla is usually characterized by 
limited bone height secondary to pneumatization of the maxillary sinus and/or 
collapse of the alveolar ridge that preclude in many instances the installation 
of dental implants. In order to compensate for the lack of bone height, several 
treatment options have been proposed. These treatment alternatives aimed at the 
installation of dental implants with or without the utilization of bone grafting 
materials avoiding the perforation of the Schneiderian membrane. Nevertheless, 
membrane perforations represent the most common complication among these 
procedures. Consequently, the present review aimed at the elucidation of the 
relevance of this phenomenon on implant survival and complications.
MATERIAL AND METHODS: Electronic and manual literature searches were performed 
by two independent reviewers in several databases, including MEDLINE, EMBASE, 
and Cochrane Oral Health Group Trials Register, for articles up to January 2018 
reporting outcome of implant placement perforating the sinus floor without 
regenerative procedure (lateral sinus lift or transalveolar technique) and graft 
material. The intrusion of the implants can occur during drilling or implant 
placement, with and without punch out Schneiderian. Only studies with at least 
6 months of follow-up were included in the qualitative assessment.
RESULTS: Eight studies provided information on the survival rate, with a global 
sample of 493 implants, being the weighted mean survival rate 95.6% (IC 95%), 
after 52.7 months of follow-up. The level of implant penetration (≤ 4 mm or 
> 4 mm) did not report statistically significant differences in survival rate 
(p = 0.403). Seven studies provided information on the rate of clinical 
complications, being the mean complication rate 3.4% (IC 95%). The most frequent 
clinical complication was epistaxis, without finding significant differences 
according to the level of penetration. Five studies provide information on the 
radiographic complication; the most common complication was thickening of the 
Schneiderian membrane. The weighted complication rate was 14.8% (IC 95%), and 
penetration level affects the rate of radiological complications, being these of 
5.29% in implant penetrating ≤4 mm and 29.3% in implant penetrating > 4 mm, 
without reaching statistical significant difference (p = 0.301).
CONCLUSION: The overall survival rate of the implants into the sinus cavity was 
95.6%, without statistical differences according to the level of penetration. 
The clinical and radiological complications were 3.4% and 14.8% respectively. 
The most frequent clinical complication was the epistaxis, and the radiological 
complication was thickening of the Schneiderian membrane, without reaching 
statistical significant difference according to the level of implant penetration 
inside the sinus.