The aim of this retrospective study is to analyze the survival rate of implants placed in residual bone height (RBH) less than 4.5 mm during an overall follow-up of 5 years, by using Straumann and Astra implant designs with or without sinus bone grafting. A total of 77 patients were examined and treated in two private practices in the regions of Hamra and Jounieh, Lebanon, by two periodontists from 2009 to 2019. These patients received 104 implants (83 Straumann implants and 21Astra implants) where 94 implants underwent osteotomy sinus floor elevation with bone graft and 10 implants without bone graft. The radiographic images were analyzed by three examiners: two periodontists and one oral radiologist. Written informed consents were obtained from all patients prior to treatment. All patients had to fulfill the inclusion criteria elaborated hereinafter. A total of 75.96% of implants were placed at the molars sites and 24.04% at the premolars sites. All 104 implants were clinically stable except 2 Straumann implants which suffered early failure (before the implant loading) and 1 Straumann implant late failure (3 months after the implant loading). All the failed implants were placed in a RBH > 4 mm. The cumulative success rate was 97.12% during an overall follow-up of 5 years. The crestal approach for maxillary sinus floor elevation is a viable technique that can be used in patients with minimal RBH < 4.6 mm.