O'Sullivan, Michael

Purpose: Radiographs are commonly used to assess the fit of implant components, but there is no clear agreement on the amount of misfit that can be detected by this method. This study investigated the effect of gap size and the relative angle at which a radiograph was taken on the detection of component misfit. Different types of implant connections (internal or external) and radiographic modalities (film or digital) were assessed. Materials and Methods: Twelve internal-connection and 12 external-connection implant analogs with impression copings were assembled, with radiolucent washers interposed, to produce vertical misfits of 0, 12.7, 25, 38, 51, 63, 76, 88, 102, 114, 127, and 190 µm. A custom-made positioning apparatus was used to obtain radiographs of the components at angulations between 0 and 35 degrees. The images were randomized, and three experienced examiners assessed whether a gap was visible at the interface. Their responses were compared to the actual status of the samples, and a probability model was constructed to predict the likelihood of a correct answer at any combination of gap and angle. Results: The relative angulation of the radiograph and the dimension of the gap were the most significant factors affecting an examiner's diagnostic ability. A 0-µm gap viewed at 0 degrees was the combination most accurately diagnosed. Implant component misfits as small as 12.7 µm were reliably detected with radiographs up to 5 degrees from the orthogonal projection; this was similar with configurations of 25 to 38 µm/10 degrees and 51 µm/15 degrees. There was good (inter-)examiner reliability. Neither the type of component used nor the radiographic media used influenced diagnostic ability. Conclusion: The angulation of the x-ray beam relative to implant components needs to be controlled when using radiographs to detect component misfit. Keywords: dental implants, implant abutment, implant failure, implant misfit, radiographs

Purpose: During extensive prosthodontic treatment, the use of an accurately adjusted articulator is recommended to simulate mandibular movements. This clinical study was undertaken to assess any possible effect of the underlying skeletal pattern on programming articulator settings. Materials and Methods: Subjects (n = 73, mean age: 22.8 ± 6.8 years) were recruited from a dental school and two regional specialist orthodontic units. Subjects were allocated into groups based on their underlying sagittal (I, II, or III) and vertical (reduced, average, or increased) skeletal patterns by three orthodontists and three prosthodontists who examined their profile photographs. Electronic pantographic recordings were made of each subject using the Cadiax Compact system to record the sagittal condylar inclination (SCI), progressive mandibular lateral translation (PMLT), and immediate mandibular lateral translation (IMLT). Results: Agreement between assessors for sagittal skeletal pattern classification was excellent (97% for total or good agreement); agreement for vertical skeletal pattern was high, but at a lower level than that for sagittal relationships (70% for total or good agreement). SCI settings for sagittal II subjects were significantly higher than those for sagittal I (P .05) and sagittal III (P .001) subjects. Differences were statistically significant, with mean SCI differences of 4 and 7 degrees, respectively. No statistical difference could be observed between SCI values in the sagittal I and III groups. Subjects with an average vertical skeletal pattern had SCI values lower than those with a reduced vertical skeletal pattern (P = .058) and an increased vertical skeletal pattern (P .01, statistically significant). No patterns could be determined for PMLT or IMLT between the study groups. Conclusion: During prosthodontic treatment of patients with a noticeable skeletal discrepancy, appropriate consideration should be given to customizing SCI values.

Purpose: The objective of this study was to assess the accuracy of the model-based NobelGuide method in transferring preoperative planning and estimation of bone volume to the surgical situation. Materials and Methods: Thirteen implant replicas were placed in bounded edentulous spaces in nine human cadavers. Highly restrictive guides were fabricated using preoperative bone mapping data. A stone cast was modified to represent the bone contours at the implant site. Postoperative impressions were taken for comparison with the planning cast that had been used to generate the guides. Mucoperiosteal flaps were raised over each implant site, and the areas were inspected for fenestrations, thread exposures, or dehiscences. A coordinate measuring device was used to obtain positional and angular information from each implant placed in the planned and postsurgical casts. These were compared and analyzed for clinical and statistical significance. Results: The median value for linear accuracy in three dimensions for the model-based NobelGuide was 0.48 mm and the median angular deviation was 2.88 degrees. The greatest measured errors were still within clinically acceptable limits. The bone mapping was of sufficient diagnostic value for implant placement in sites with sufficient bone volume (greater than 5 mm buccolingually). In sites with insufficient bone volume, dehiscences were seen, but the accuracy was independent of bone volume. Conclusion: The use of the model-based NobelGuide encourages adherence to the restorative-driven approach. The accuracy of the method is within acceptable limits for guided surgery described in the literature, and the use of the bone mapping is satisfactory in cases with adequate bone volume. The technique can also be used in sites with insufficient bone volume, but a mucoperiosteal flap procedure is recommended. Keywords: bone mapping, computed tomography, dental implant placement, model-based planning

Purpose: To assess and compare patient satisfaction and oral health-related quality of life (OHQOL) in patients treated with implant-supported overdentures and complete implant fixed prostheses. Materials and Methods: From a database of patients who had undergone implant treatment over a 6-year period, a study population of 62 patients was identified; every patient had at least four implants placed in one edentulous arch and was restored with either an overdenture or a fixed prosthesis. Patients were examined and a self-administered, structured multiple-response questionnaire, including the Oral Health Impact Profile-14 measurement tool and a patient satisfaction survey, was used to evaluate patient-centered treatment outcomes. Results: Generally, patient satisfaction was very high in both the implant overdenture and fixed prosthesis groups, although the subjects in the overdenture group, who had mostly maxillary prostheses, reported significantly lower overall satisfaction and lower satisfaction with chewing capacity and esthetics. In just three categories-cost, satisfaction with treating doctor, and ability to perform oral hygiene measures-the fixed prosthesis group was less satisfied than the removable overdenture group, but the difference was not significant. Similarly, the overall OHQOL was high, although patients receiving a fixed prosthesis demonstrated significantly lower psychologic discomfort and psychological disability compared to the overdenture group. Conclusions: Among all patients who had similar numbers of implants placed, those who received an implant overdenture were less satisfied and had lower OHQOL than the patients who had a fixed prosthesis. Since patient and dentist preferences influenced the type of prosthesis provided, it is likely that subjective, patient-related factors are major determinants of satisfaction and treatment outcomes. Keywords: dental implants, patient satisfaction, quality of life, treatment outcomes