Zirconia implants are appreciated in some clinical indications in light of their aesthetic appearance and good biocompatibility. The aim of this work was to evaluate the performance of a newly ...developed two-piece zirconia/polyether ketone ketone (PEKK) implant-abutment combination after long-term cyclic loading in a hydrothermal environment, using a new protocol adapted from two available ISO standards. Sixteen implants (n = 8/group) were embedded according to ISO 14801 and divided into two groups: implants in the Observational Group (OG) were cyclically loaded for 60 days (98 N, 10 million loading cycles, 2 Hz) in 85 °C water in a chewing simulator, while non-loaded/non-aged implants (as-received) constituted the Control Group (CG). After 4.7 million loading cycles, one OG implant fractured in the chewing simulator. The surviving implants were compared to CG implants by X-ray diffraction (XRD) to investigate potential ageing as suggested by ISO 13356, but also μ-Raman spectroscopy, Focused-Ion-Beam - Scanning-Electron-Microscopy (FIB-SEM), and load-to-fracture. Ageing was shown to have limited influence on the evaluated zirconia implant, with increased monoclinic content after loading/ageing being to a shallow transformed zone of ~2 μm at the implant surface. However, OG implants showed a significantly decreased fracture load of 751 ± 231 N (CG: 995 ± 161 N; p = .046). These values enable clinical application, but the fact that one failure was recorded during cyclic fatigue along with the significant decrease in strength after cyclic loading/ageing suggest that there may be room for further optimization of especially the PEKK abutment. Furthermore, good agreement was observed between the fracture modes of the implant that failed during the cyclic fatigue experiment and the in vivo failure of one implant during pre-clinical trials, validating the interest of the in vitro protocol used in this work to check the reliability of zirconia implant.
•First study evaluating a two-piece, injection-moulded zirconia implant against PEKK abutment.•Strength was sufficient for clinical application but affected by the long-term cyclic fatigue in hydrothermal environment.•The loading/ageing combination had a limited impact on the zirconia, but more pronounced on the PEKK abutment.•Tests were based on the adaptation of two ISO standards: ISO 14801 and ISO 13356.•A combination of these standards may be proposed to check a priori the reliability of zirconia-based implants.•Further research is needed to address the potential degradation of PEKK under cyclic fatigue in humid environment.
Objectives
This study aimed to describe a disability‐simulating learning unit (DSLU) to raise dental students’ awareness of the special needs of patients with disabilities as well as to measure the ...effect of the DSLU on ableism.
Methods
A DSLU among final‐year undergraduate dental students (n = 33), was developed and evaluated. The students were randomly divided into two groups (Group I, n = 17; Group II, n = 16). Group II only received conventional teaching (control group), whereas Group I was additionally exposed to the DSLU (intervention group). In the DSLU, typical physical restrictions and the associated difficulties in attending dental appointments were simulated with the help of simulation suits. Four different stations offered the opportunity to experience typical signs of disability in a dental context. About 2 months after the DSLU, both groups were asked to answer the Symbolic Ableism Scale (SAS). An analysis was conducted to examine the participants’ average total score and several subscores. The Mann–Whitney U Test was employed to control the differences between the study groups.
Results
Overall, the students in the intervention group had a significantly (p = .001) lower mean SAS summary score (median = .37; IQR .32–.42) than the students in the control group (median = .50; IQR .39–.53). For the components “individualism” (p < .0001) and “excessive demands” (p = .002) significant group differences could be observed.
Conclusion
The DSLU is a potentially feasible and effective method for influencing students’ ableism attitude.
Objective. To test whether or not the modified design of the test implant (intended to increase primary stability) has an equivalent effect on MBL compared to the control. Methods. Forty patients ...were randomly assigned to receive test or control implants to be installed in identically dimensioned bony beds. Implants were radiographically monitored at installation, at prosthetic delivery, and after one year. Treatments were considered equivalent if the 90% confidence interval (CI) for the mean difference (MD) in MBL was in between −0.25 and 0.25 mm. Additionally, several soft tissue parameters and patient-reported outcome measures (PROMs) were evaluated. Linear mixed models were fitted for each patient to assess time effects on response variables. Results. Thirty-three patients (21 males, 12 females; 58.2±15.2 years old) with 81 implants (47 test, 34 control) were available for analysis after a mean observation period of 13.9±4.5 months (3 dropouts, 3 missed appointments, and 1 missing file). The adjusted MD in MBL after one year was −0.13 mm (90% CI: −0.46–0.19; test group: −0.49; control group: −0.36; p=0.507). Conclusion. Both implant systems can be considered successful after one year of observation. Concerning MBL in the presented setup, equivalence of the treatments cannot be concluded. Registration. This trial is registered with the German Clinical Trials Register (ID: DRKS00007877).
When immediately temporizing an implant, relining and cementation of the provisional can be a challenging, time-consuming, and contaminating procedure. Excess resin and cement need to be carefully ...removed from the fresh wound. This can be overcome by digitally backward planning the treatment with subsequent production of a surgical guide to be used by both the technician and the dentist. In this report, a patient with a fractured and hopeless central incisor and an apical radiolucency at his compromised (root-canal treated, post and core build-up) contralateral counterpart was treated using guided implant installation, immediate placement of a prefabricated screw-retained provisional, and apicoectomy. Dehiscence of the buccal plate after tooth extraction resulting in the need for hard- and soft-tissue grafting and delayed surgery did not affect the clinical outcome.
Additive manufacturing is becoming an increasingly important technique for the production of dental restorations and assistive devices. The most commonly used systems are based on vat polymerization, ...e.g., stereolithography (SLA) and digital light processing (DLP). In contrast, fused filament fabrication (FFF), also known under the brand name fused deposition modeling (FDM), is rarely applied in the dental field. This might be due to the reduced accuracy and resolution of FFF compared to vat polymerization. However, the use of FFF in the dental sector seems very promising for in-house production since it presents a cost-effective and straight forward method. The manufacturing of nearly ready-to-use parts with only minimal post-processing can be considered highly advantageous. Therefore, the objective was to implement FFF in a digital dental workflow. The present report demonstrates the production of surgical guides for implant insertion by FFF. Furthermore, a novel approach using a temperature-sensitive filament for bite registration plates holds great promise for a simplified workflow. In combination with a medical-grade filament, a multi-material impression tray was printed for optimized impression taking of edentulous patients. Compared to the conventional way, the printed thermoplastic material is pleasant to model and can allow clean and fast work on the patient.
The aim of this ex-vivo study was to evaluate the load capacity of direct or indirect endodontically restored maxillary central incisors with Class III defects, with or without glass-fiber posts.
...Seventy-two extracted human maxillary central incisors were endodontically treated and bi-proximal Class III cavities were prepared. Specimens were randomly allocated to six groups (n = 12): direct restoration with composite (C); direct restoration with composite and additional glass-fiber post (CP); ceramic veneer restoration (V), ceramic veneer restoration and additional glass-fiber post (VP), ceramic crown restoration (Cr), ceramic crown restoration and additional glass-fiber post (CrP). Specimens were exposed to thermomechanical loading (TML: 1.2 million cycles, 1 to 50 N; 6000 thermal cycles between 5°C and 55°C for 1 min each), and subsequently linearly loaded until failure (Fmax N) at an angle of 135 degrees 3 mm below the incisal edge on the palatal side. Statistical tests were performed using the Kruskall-Wallis and Mann-Whitney U-Test.
During dynamic loading by TML, one early failure occurred in group C, CP, and CrP. Subsequent linear loading resulted in mean fracture load values N of C = 483 ± 219, CP = 536 ± 281, V = 908 ± 293, VP = 775 ± 333, Cr = 549 ± 258, CrP = 593 ± 259. The Kruskal-Wallis test showed significant differences of load capacity between groups (p < 0.05). Mann-Whitney U-test revealed significantly lower maximum fracture load values of group C compared to group V (p = 0.014), after Bonferroni-Holm correction. Non-restorable root fracture was the most frequent type of failure.
Endodontically treated maxillary central incisors with Class III defects directly restored with composite are as loadable as indirect crown restorations. Compared to full-coverage restorations, less invasive veneers appear to be more beneficial. Additional placement of glass-fiber posts shows no positive effect.
The tasks of this working group were to evaluate the existing evidence on the efficiency and efficacy of the digital and conventional workflows for the fabrication of fixed implant reconstructions, ...to assess the performance of all-ceramic fixed implant reconstructions and, finally, to evaluate the outcomes of internally and externally connected implant abutments and reconstructions.
Four reviews were available analyzing the current literature on the respective topics. One review dealt with the efficiency and efficacy of digital and conventional fabrication workflows. Two reviews analyzed the outcomes of all-ceramic fixed implant reconstructions, one focusing on single-implant reconstructions and the other evaluating multiple-unit implant fixed dental prostheses (FDPs). The fourth review evaluated the clinical outcome on external, respectively, internal implant-abutment connections. These reviews were the basis for the discussions within the group and at the plenary sessions.
The present consensus report gives the consensus statements, the clinical recommendations, and the implications for future research as discussed and approved by the plenum of the consensus conference. The four manuscripts by Mühlemann et al., Rabel et al., Pieralli et al., and Pjetursson et al. are published as part of the journal supplement of the present EAO consensus conference.
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