RESUMEN
Additively manufactured subperiosteal jaw implants (AMSJI) are patient-specific, 3D-printed, titanium implants that provide an alternative solution for patients with severe maxillary bone atrophy. The aim of this study was to evaluate the bony remodeling of the maxillary crest and supporting bone using AMSJI. Fifteen patients with a Cawood-Howell Class V or greater degree of maxillary atrophy were evaluated using (cone beam) computed tomography scans at set intervals: one month (T1) and twelve months (T2) after definitive masticatory loading of bilateral AMSJI implants in the maxilla. The postoperative images were segmented and superimposed on the preoperative images. Fixed evaluation points were determined in advance, and surface comparison was carried out to calculate and visualize the effects of AMSJITM on the surrounding bone. A total mean negative bone remodeling of 0.26 mm (SD 0.65 mm) was seen over six reference points on the crest. Minor bone loss (mean 0.088 mm resorption, SD 0.29 mm) was seen at the supporting bone at the wings and basal frame. We conclude that reconstruction of the severely atrophic maxilla with the AMSJI results in minimal effect on supporting bone. Reduced stress shielding with a biomechanically tuned subperiosteal implant does not induce radiographically significant crestal bone atrophy.
RESUMEN
INTRODUCTION AND AIM: Buccal bone thickness is considered to be an important factor during implant surgery. Its resorption might have an effect on the soft tissue stability and eventually on implant survival. This study aimed to investigate the resorption of the buccal bone over the first 12 months after implant loading. MATERIALS AND METHODS: Twenty-four subjects (47 implants) were included. The buccal bone thickness was measured during implant surgery at several distances from the implant shoulder using a specifically designed device which allows buccal bone thickness measurements without the elevation of a muco-periostal flap. These measurements were repeated after 12 months of loading. Sixteen implants were placed flapless and 31 with the elevation of a flap. Of the latter, 19 were placed following a one-stage protocol and 12 following a two-stage protocol. RESULTS: The mean reduction in buccal bone thickness, when all groups pooled, was 0.26, 0.36, 0.35 and 0.27 mm at the shoulder and 2, 4 and 6 mm apically. Implants with initial bone thickness <1mm (thin buccal plate) did not lose significantly more bone than those with an initial thickness ≥1mm (thick bone plate) except in the 'open-flap, one-stage' group (P = 0.009). A flapless procedure leads to less bone resorption compared to an open-flap procedure (P = 0.03). However, the number of surgeries (one stage vs. two stages) did not influence the rate of bone resorption (P = 0.23). CONCLUSION: Within the limitations of this study, one might question the necessity of having a thick bone plate at the vestibular site of the implant.