49 Maxillary implant overdentures: surgical templates in atrophic jaws 3.3 RESULTS Clinical performance A total of 24 implants was placed in 11 patients. The implants had a length of 13 to 15 mm. All but one template had a good fit during implant placement, which means that the templates could be placed easily at the nasal fulcrum and they fit the labial aspect of the alveolar process precisely (Table 3.1). One template could not be placed properly on the left side. The left clamp failed to slide over the nasal aperture after placing the template on the alveolar bone. Once the left clamp was removed, the template could be properly positioned. However, the accuracy was not calculated for this implant (patient 6, implant location 23). All the other implants were placed with good primary stability and no post-operative complications occurred. Post-operative pain was self-limiting and managed with over the counter pain medication. After a 3-month osseointegration period, second stage surgery was performed; no implants were mobile so healing abutments were placed and an implant-supported maxillary overdenture was fabricated. None of the implants were lost during the follow-up period of 6 months after implant placement. Inter-observer variation The intra-class coefficient between the two observers was 0.84 for global deviation, with a mean difference of <0.1 mm, which indicates good reproducibility. Accuracy Implant accuracy results are presented in table 1. The mean deviations at the implant shoulder were 1.1±0.5mm (global deviation) mm, 0.8±0.5mm (lateral deviation) and 0.7±0.4 mm (depth deviation). The mean angular deviation of the implants was 7.2±3.4°. 3.4 DISCUSSION The aim of this study was to assess the clinical usability and accuracy of nasal aperture supported templates in patients with severe maxillary bone atrophy (Cawood class V and VI). Overall, the template fits were stable and secure, with satisfying implant placement accuracy. Other studies Recent BST studies show a mean global deviation at the implant shoulder of 0.7±0.4mm to 1.6±0.9mm and a mean angular deviation of 2.4±1.0° to 4.6±2.6°11-13. These results are comparable to the current study, despite the fact that semi-guided templates were used, and despite the fact that only Cawood class V or VI patients were treated, while the other studies did not mention the available bone volume. Our angular deviation was slightly higher than in other studies. Vercruyssen et al.13 showed that a lack of guided placement did not affect angular deviation when comparing templates with semi- and full guidance. However, their results were not corrected for different types of bone density. Ozan et al.12 compared angular deviation between groups with high and low bone 3
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