Maxillary sinus floor elevation through lateral access was first proposed in 1977 [1], while the technique was published in 1984 [2]. Several modifications in the surgical approach and the biomaterials used have been introduced over time [3,4,5]. In a systematic review with meta-analysis, it was concluded that the best survival rate was observed when implants with rough surface and membrane to cover the lateral window were used [3]. However, another systematic review with meta-analysis did not find a difference in survival rate for a lateral window with or without the protection of a membrane [5]. Moreover, clinical studies reported higher proportions of new bone at grafted sinuses protected by a collagen membrane compared to unprotected sites [6, 7], while in a systematic review with meta-analysis, no differences in bone formation were disclosed [8]. The use of a collagen membrane did not prevent the loss of biomaterial through the lateral window [9,10,11].

Nevertheless, the closure of the antrostomy with bone was documented by CBCTs taken after 9 months of healing [10, 11]. Even though the lateral window might be assessed as closed at the CBCTs analysis, a histological study in humans showed higher amounts of bone and bone marrow at biopsies taken from the grafted sites through the alveolar crest compared to those from the antrostomy region [12]. Moreover, some antrostomies presented incomplete healing of the region, with connective tissue interposed between the margin of the antrostomies that affected a complete closure and corticalization.

The repositioning of the bone window removed before sinus floor elevation from the antrostomy is another option that has been applied both in clinical [13, 14] and in experimental studies [15, 16], and optimal results have been reported. Though data have been reported on autogenous bone used alone or mixed with bone substitutes [14, 17]; no data have been reported on the use of autogenous bone only in the antrostomy and in the subjacent region.