Clinical Outcomes of Pterygoid Implants: Systematic Review and Metaanalysis

Background: Dental implant rehabilitation of patients with severe posterior maxillary atrophy is challenging due to anatomic; surgical access and bio-mechanical features. Several treatment have been proposed, i.e., tilted; short; tuberosity; zygomatic or pterygoid implants and several bone graft techniques. NOe of them is considered the gold standard, with their specific disadvantages. Modern implantology seeks for treatments that favor predictability with lower morbidity, time and total treatment costs. Aim/Hypothesis: Pterygoid implants are in line with modern Implantology concepts, and yet, it is not a widely spread treatment modality and do not have a wide range published studies. The aim of this systematic review was to analyze pterygoid implant survival rates in patients with atrophic posterior maxilla. Materials and Methods: This systematic review was performed in accordance with the PRISMA guidelines and registered in the PROSPERO database. An extensive search of electronic databases (PubMed/Medline, Science Direct, Embase, and Cochrane Library) was carried out for articles published between January 1995 and January 2019 using the following key words: “pterygoid implants,” “pterygomaxillary implants,” “pterygoid plate implants,” and “tuberosity implants”. The quality of each study included in this review was assessed using the Australian National Health and Medical Research Council (NHMRC) scale. A risk quality and bias assessment was performed to eliminate studies not specifying, or with inconsistent data on, the length and/or engagement of implant in the pterygoid laminae of the sphenoid bone. The survival rates of pterygoid implants were analyzed, as well as implant length and insertion angulation. Failure and survival data, surgical and implant characteristics, and peri-implant bone loss were analyzed. Results: The database search identified 325 studies. 36 full-text articles were selected based on titles and abstract reviews and only 6 studies meet all the eligibility criteria. All studies were retrospective case series ranging from 1994 to 2015. The mean age of patients was 53.17 years old. A total of 634 patients received 1.893 pterygoid implants, with a mean implant survival rate of 94.87%. The follow-up period ranged from 12 to 132 months. Implant length varied from 13 to 20 mm. None of the studies reported significant clinical, surgical, or prosthetic complications. The mean healing was 4-6 months prior to implant loading. Two studies reported low peri-implant bone loss of the pterygoid implants of 1.21 mm and 0.71 mm, respectively. All studies mentioned the importance of adequate implant length and proper implant angulation to engage the cortical bone of the pterygoid plate. Of a total of 1893 pterygoid implants, 97 implants were lost and most of the failures occured before loading. Conclusions and Clinical Implications: The outcomes of the present systematic review should be interpreted with caution because of certain limitations. Yet, good clinical and prosthetic results were found, with very few complications associated. Within the limits of this meta-analysis, this study demonstrates comparable implant survival rates between pterygoid and conventional implants in other regions of the maxilla. This procedure may be considered suitable for unilateral, bilateral or total atrophic maxilla implant rehabilitation. Keywords: Pterygoid implant, Pterygomaxillary implant, Atrophic maxilla