Quality Evaluation of Zirconium Dioxide Frameworks Produced in Five Dental Laboratories from Different Countries.

PURPOSE: The aim of this study was to assess and compare quality as well as economic aspects of CAD/CAM high strength ceramic three-unit FDP frameworks ordered from dental laboratories located in emerging countries and Switzerland. MATERIAL AND METHODS: The master casts of six cases were sent to five dental laboratories located in Thailand (Bangkok), China (Peking and Shenzhen), Turkey (Izmir), and Switzerland (Bern). Each laboratory was using a different CAD/CAM system. The clinical fit of the frameworks was qualitatively assessed, and the thickness of the framework material, the connector height, the width, and the diameter were evaluated using a measuring sensor. The analysis of the internal fit of the frameworks was performed by means of a replica technique, whereas the inner and outer surfaces of the frameworks were evaluated for traces of postprocessing and damage to the intaglio surface with light and electronic microscopes. Groups (dental laboratories and cases) were compared for statistically significant differences using Mann-Whitney U-tests after Bonferroni correction. RESULTS: An acceptable clinical fit was found at 97.9% of the margins produced in laboratory E, 87.5% in B, 93.7% in C, 79.2% in A, and 62.5% in D. The mean framework thicknesses were not statistically significantly different for the premolar regions; however, for the molar area 4/8 of the evaluated sites were statistically significantly different. Circumference, surface, and width of the connectors produced in the different laboratories were statistically significantly different but not the height. There were great differences in the designs for the pontic and connector regions, and some of the frameworks would not be recommended for clinical use. Traces of heavy postprocessing were found in frameworks from some of the laboratories. The prices per framework ranged from US$177 to US$896. CONCLUSIONS: By ordering laboratory work in developing countries, a considerable price reduction was obtained compared to the price level in Switzerland. Despite the use of the standardized CAD/CAM chains of production in all laboratories, a large variability in the quality aspects, such as clinical marginal fit, connector and pontic design, as well as postprocessing traces was noted. Recommended sound handling of postprocessing was not applied in all laboratories. Dentists should be aware of the true and factitious advantages of CAD/CAM production chains and not lose control over the process.

Early loading of titanium dental implants with an intra-operatively conditioned hydrophilic implant surface after 21 days of healing.

OBJECTIVES: The aim of the present observational medical device performance study was to test whether implants with an intra-operatively conditioned hydrophilic surface can be safely reconstructed when applying an early loading protocol after 21 days in partially edentulous posterior mandibles. MATERIAL AND METHODS: Partially edentulous patients with missing teeth in the posterior mandible were recruited. Immediately after implant placement, the implant position was indexed using a pickup impression technique. ISQ values were measured after 21 days of healing. When ISQ values were ≥70, the implants were directly restored with provisional reconstructions in occlusal contact allowing an early loading protocol. ISQ values were repeated again at 1, 3, and 6 months postloading. Clinical parameters (mPLI, mSBI, PPD, DIM, and CAL) were assessed. Standardized periapical radiographs were obtained after surgery, at implant loading and 3 and 6 months later. Changes over time were analyzed for statistical significance using the nonparametric method by Brunner & Langer (SAS Proc Mixed). RESULTS: Fifteen partially edentulous patients with healed sites in the posterior mandible received 20 implants. All implants healed uneventfully. At 21 days, all implants achieved an ISQ value of ≥70 (mean of 3 measurements) and were reconstructed at this time point with provisionals. ISQ values showed a gradual increase from baseline to 3 and 6 months postloading. The assessment of clinical parameters revealed stable tissue integration. The evaluation of the radiographs showed that 3 and 6 months after loading the median mesial and distal marginal bone levels had stabilized at the border between the rough surface and the 1-mm machined implant collar. CONCLUSION: Functional occlusal loading of implants with a hydrophilic, moderately rough endosseal surface 3 weeks after placement appears to be a safe and predictable treatment option in healed sites in the posterior mandible without need of bone augmentation procedures.