The rehabilitation of the posterior maxilla with an implant-supported prosthesis is often a demanding treatment for the implant surgeon. The local anatomy can be difficult due to a reduced ridge height in potential implant sites. The present clinically oriented paper discusses the three surgical options available: (i) the utilization of short implants, (ii) sinus floor elevation (SFE) with the lateral window technique, and (iii) SFE with the transalveolar osteotome technique. A thorough clinical and radiographic examination is required to choose the appropriate surgical approach, which should offer a successful outcome with high predictability and a low risk of complications. In addition, treatment should offer minimal invasiveness and morbidity, when possible. Low morbidity is offered by short 6-mm implants, which are utilized when multiple implants are feasible with splinted implant crowns. A single tooth replacement with 6-mm implants in molar sites is only used in exceptional situations. In all other situations, SFE is required. Both surgical techniques are well documented, but the transalveolar osteotome technique is utilized less frequently, since it requires a ridge height of 5 - 8 mm and a flat morphology of the sinus floor. Whenever possible, a simultaneous implant placement is performed to avoid a second surgery. For that, sufficient primary stability is important, which can be optimized with tissue level implants. In addition, grafting with a composite graft is preferred, which includes locally harvested autogenous bone chips mixed with a low-substitution bone filler. The various treatment options are discussed and documented with case reports.
Loss of teeth in the posterior maxilla is a frequent scenario encountered in dentistry. Brugger et al. (2015), analyzing a 3-year patient pool in a surgical specialty clinic, reported that the posterior maxilla accounted for 36% of the total number of sites treated with dental implants (Brugger et al. 2015). This area has always been considered a challenging region with its unique anatomy of teeth and alveolar bone as well as its proximity and relationship to the maxillary sinus. Early findings in implant dentistry demonstrated significantly lower survival rates in the posterior maxilla, which were correlated with different causes such as poor bone density, complex anatomy and loading protocols with shorter healing periods (Adell et al. 1981, Jaffin & Berman 1991). We must not forget that those were the days where titanium implants with a machined surface were most often used. In addition, longer implants (≥ 15 mm) with bicortical stabilization were recommended (Bahat 1993). Hence, the use of large autogenous bone grafts, mostly from an extraoral donor site, was often encouraged (Tolman 1995).
The primary objectives of implant therapy continue to be successful treatment outcome with high predictability concerning long-term function and esthetics and low risk of complications (Buser and Chen 2008). The ultimate goal is long-term success of 30+ years, which means that an inserted and restored implant should have the best prerequisites for successful long-term stability. The secondary objectives of therapy include minimal invasiveness and morbidity, including the least number of surgical procedures and shorter healing periods. In the past 15 to 20 years of fine tuning in implant dentistry, aspects related to the secondary objectives have substantially improved to make implant therapy more attractive for patients and more patient friendly, but without jeopardizing the primary objectives of therapy (Buser et al. 2017).
Successful outcomes in implant therapy are influenced by four factors as first outlined by Buser and Chen (Buser and Chen 2008). This concept, documented with four interconnected circles, can also be applied to the treatment of the posterior maxilla (Fig. 1). The first and most important circle reflects the implant surgeon, or rather his/her clinical team, since the treatment quality by the surgical and restorative dentist – often provided by the same person – is probably the most crucial factor. Additional members of the clinical team are also the dental technician and – if available – the dental hygienist for the supporting maintenance care program. The talent and expertise of the implant surgeon are decisive for the treatment outcome, as he/she examines the patient to establish his/her risk profile, decides on the most appropriate treatment option, selects the necessary biomaterials, and finally performs the surgical treatment. The crucial importance of this first circle is also documented by the fact that it is larger than the three other circles.
The second circle represents the patient with his/her risk factors, indicators and determinants, which include medical, dental and anatomical risk factors together with smoking. All these factors must be considered in the selection of the most appropriate treatment option. In the posterior maxilla, the local anatomy is probably the most relevant factor for the selection of the treatment approach.
The third circle represents the biomaterials, which include the selected implant and its material, surface, shape, diameter and length, and the implant abutment. In addition, bone grafts, bone substitutes, and barrier membranes are important elements for sinus floor elevation (SFE) procedures. Lastly, the fourth circle to consider is the treatment approach itself for a given clinical situation. In the posterior maxilla with a reduced ridge height and pneumatized sinus cavity, various treatment options are available to achieve the anticipated treatment outcome.
In accordance with the scope of the Forum Implantologicum, the purpose of this clinical paper is to discuss the surgical options available for implant therapy in the posterior maxilla in partially edentulous patients. It reflects the authors’ personal long and thoroughly documented experience in the field. In addition, it provides clinical recommendations for when to use which treatment option to have the best chance of a successful treatment outcome in this challenging clinical scenario.