Longitudinal Assessment of Denture Maintenance Needs in an Overdenture Population.

PURPOSE: To evaluate the longitudinal denture maintenance needs of a tooth-supported overdenture population. MATERIALS AND METHODS: This prospective cohort study was composed of patients who had received tooth-supported overdentures from 1974 to 1994 in the Department of Prosthodontics, University of Iowa. There were 272 persons with 662 abutments who fulfilled the inclusion criteria. To simplify analysis and reduce the number of confounding variables, only those participants wearing complete maxillary dentures and opposing complete mandibular overdentures supported by teeth #22 and #27 were included in this analysis. The denture maintenance needs of these participants were identified and related to age, gender, length of time wearing overdentures, number of medications, and denture-wearing habits. Descriptive statistics and bivariate analyses were used for the statistical analysis (α = 0.05). RESULTS: Of the 91 participants (mean age = 59.5 ± 10.1 years; 63.7% male) who fulfilled the inclusion criteria at baseline, 48.4% took 1 to 3 medications daily, and 84.6% wore their dentures day and night. The percentages of participants who needed one or more of the following denture treatments were: 91.2% denture base adjustments, 76.9% laboratory processed relines, 61.5% denture remakes, 33% laboratory remount and occlusal adjustment, 22% repaired bases, and 19.8% needed denture teeth replaced. Bivariate analyses indicated that participants who were 65 years and older needed more denture adjustments than patients younger than 65 years (p = 0.0343). Participants who had worn overdentures for more than 5 years were more likely to require denture remakes (p = 0.0304). Participants who wore their dentures only during the day were less likely to require repairs (p = 0.0403). Participants who did not take any medications were significantly less likely to require denture base repairs (p = 0.0258). For the 35 participants who returned for recalls at all 4 time points, males were more likely to need denture teeth repaired or replaced (p = 0.0335) and those aged 50 to 64 were more likely to need 2 or more adjustments (p = 0.0311). No overdenture abutments were lost by the participants in this study. CONCLUSIONS: According to the results of this study, age, medication usage, denture-wearing habits, and age of the overdentures were significant factors associated with denture maintenance needs. Persons wearing overdentures need regular recalls, because they have continuing maintenance needs.

[Microbial contamination of the implant-abutment connections: Review of the literature]. / Pénétration microbienne dans la connectique pilier-implant : revue de littérature.

Today manufacturing process of dental implant parts allows for a precision of fit between implant and abutment of several microns. This microgap opens and closes under occlusal forces, leading to a pumping effect and to a contamination of the implant from bacteria and oral fluids. This kind of contamination is seen in all systems even if less often with internal connections that offers a better fit. Apart from this junction area, the screw well is another contamination pathway if the filling materials do not guarantee a hermetic sealing. The nature of contamination depends on the surrounding oral flora. When present, contamination leads to a persistent inflammatory reaction nearby the seal. The use of antiseptics or other materials for sealing the microgap decreases the risk of contamination and improves the gingival reaction. However, these solutions are time-limited.

Use of implant-supported prostheses in edentulous mandibles among prosthodontists in Sweden.

The aim of this study was to investigate the production of mandibular implant-supported fixed and removable prostheses among prosthodontic specialists in Sweden and to compare the results with findings in a similar study made in 2001 (17). Questionnaires regarding treatment with mandibular implant prostheses during 20011 were mailed to all specialists in prosthodontics in Sweden (n = 156, according to available data). Of the 156 questionnaires, 129 (83%) were returned and of those 114 were completed. The reported number of treatments with mandibular implant-supported prostheses varied much among the specialists. Fixed implant prostheses were more common than overdentures (means 11 and 3, median values 8 and 2, respectively). However, the range was large for both alternatives. Ten (9%) of the specialists reported no treatment with fixed implant prostheses while 29 (25%) had not made any implant overdenture during 2011. The most common anchorage system for overdentures in 2011 (as well as in 2001) was two un-splinted implants with ball attachments or Locator abutments. The most common reasons for choosing overdenture treatment instead of a fixed implant prosthesis in 2011 were the reduced cost and the patient's main wish to improve denture retention. A majority of the prosthodontists (58%) reported that patients with implant overdentures were as satisfied as those with fixed implant-supported prostheses, whereas 40% claimed they were less satisfied. Two respondents (2%) considered that overdenture patients were more satisfied than those with a fixed prosthesis. It can be concluded that the general attitude among Swedish prosthodontists towards implant overdentures has not changed much during the 10-year period between the present and the previous investigation.An overdenture is still a seldom-used option in implant treatment of patients with edentulous mandibles in Sweden. Instead, a fixed implant-supported prosthesis continues to be the preferred option,

Nonlinear finite element analysis of three implant- abutment interface designs.

The objective of this study was to investigate the mechanical characteristics of implant-abutment interface design in a dental , using nonlinear finite element analysis (FEA) method. This finite element simulation study was applied on three commonly used commercial dental implant systems: model I, the reduced-diameter 3i implant system (West Palm Beach, FL, USA) with a hex and a 12-point double internal hexagonal connection; model II, the Semados implant system (Bego, Bremen, Germany) with combination of a conical (450 taper) and internal hexagonal connection; and model III, the Brinemark implant system (Nobel Biocare, Gothenburg,Sweden) with external hexagonal connection. In simulation, a force of 170 N with 45" oblique to the longitudinal axis of the implant was loaded to the top surface of the abutment. It has been found from the strength and stiffness analysis that the 3i implant system has the lowest maximum von Mises stress, principal stress and displacement while the Br Bnemark implant system has the highest. It was concluded from our preliminary study using nonlinear FEA that the reduced-diameter 3i implant system with a hex and a 12-point double internal hexagonal connection had a better stress distribution, and produced a smaller displacement than the other two implant systems.