Clinical Indications and Outcomes of Sinus Floor Augmentation With Bone Substitutes: An Evidence-Based Review

Abstract

Tooth loss, resulting from various causes such as periodontal disease or dental caries, can lead to the subsequent resorption of the alveolar bone process [1]. This fundamentally complicates implant-based rehabilitation, especially in the posterior maxilla. Crestal migration of the maxillary sinus floor due to pneumatization, combined with resorption of the alveolar bone, can result in inadequate residual bone height. This situation may require pre-implant interventions like sinus floor elevation (SFE) to ensure enough bone for implant placement [2, 3].

Several strategies have been introduced to increase the bone height in the posterior maxilla [3-5]. SFE has been shown to have relatively high success in augmenting the posterior maxilla with a deficient bone height. Two main techniques have been introduced: (1) The transalveolar (vertical, closed) SFE, and (2) The lateral window approach (open). It should be noted that several modifications of these techniques have also been introduced [6-8].

Given that this regenerative intervention aims to enhance bone height and width to facilitate proper implant placement, dental implants can be placed simultaneously with the sinus augmentation procedure (referred to as the “one-stage” technique). Alternatively, a staged approach may be employed, where bone augmentation occurs during the initial surgical intervention, followed by the placement of dental implants once adequate bone volume has been established (known as the “two-stage” technique) [9, 10].

The classical sinus lift procedure, introduced by Tatum in the 1970s, involves a lateral window approach [11, 12]. This technique involves creating incisions to expose the sinus wall, followed by a trapdoor osteotomy to access the sinus membrane and cavity. Careful dissection and membrane elevation are performed to create space for graft material. If sufficient basal bone is present, implants may be placed simultaneously, protruding through the sinus cavity and protected by the sinus membrane. The remaining space is typically filled with bone replacement grafts, and the window opening is closed with a barrier membrane. However, a two-stage approach is required if the basal bone is inadequate, and implants are placed only after sufficient bone regeneration [9].

In contrast, an alternative, less-invasive technique introduced by Tatum and modified by Summers is the crestal approach [13]. When indicated, this approach involves elevating the sinus floor through the alveolar crest using osteotomes. Summers' modification utilizes concave-tipped tapered osteotomes to fracture the maxillary floor and elevate the sinus membrane. This technique is less invasive, less time-consuming, and allows for better bone density and implant stability due to lateral compression exerted by the osteotomes. After membrane elevation, various bone grafting materials may be used to fill the resulting space. However, the need for graft material post-lifting has been debated, as clot stabilization may promote new bone formation [14]. Despite favorable implant survival rates exceeding 90% reported in systematic reviews, blind procedures carry risks of complications [15].

In conclusion, the presence of residual maxillary bone, ranging from 3 to 8 mm, influences the choice of approach and augmentation procedure for implant placement in the sinus area. The speed of bone regeneration is influenced by factors such as the angle and distance from the sinus walls, with narrower angles and closer distances, as well as the size of lateral window preparation, resulting in faster new bone formation. Biomaterial selection and formulation, such as ABB, and porcine xenografts play a crucial role in achieving optimal outcomes, with considerations for resorption rates and material consistency. Additionally, the use of putty materials offers advantages in terms of handling and sinus membrane elevation. However, it is important to acknowledge the potential differences in resorption rates among various biomaterials.

The authors declare no conflicts of interest.