Background: The aim of this study is to evaluate the stresses on the supporting bone, implants, and framework materials under masticatory forces in mandibular overdenture prostheses modeled with different framework materials and different implant types, using the Finite Element Analysis (FEA). Methods: For the finite element modeling, two identical mandibular jaw models were created; one with two standard (diameter:4.1 mm/12 mm length) and the other with two mini-implants (diameter:2.4 mm/12 mm length) were placed in the canine teeth area. The polymethylmethacrylate (PMMA) denture was modeled upon them, supported by Cobalt Chromium alloy (CoCr), Poly-ether ether ketone (PEEK), and Zantex materials with framework. No framework was added as a control model; only PMMA overdenture prosthesis was modeled. Results: Regardless of the framework materials of the overdenture prostheses, the stress values ​​on mini-implants in all models yielded approximately two times higher results comparing to standard implants. More stress transmission was observed in the supporting bone and implants in the control prostheses and overdenture prostheses supported with respectively PEEK, Zantex, CoCr alloy frameworks, respectively. In the framework materials, more stress occurred on CoCr, Zantex and PEEK in that order. Conclusion: In the light of this study, the use of mini-implants as an alternative to standard implants is not promising in terms of distribution and transmission of chewing stresses. As a framework material, standard rigid metal alloys were found to be more advantageous than polymer materials in terms of stress distribution.

In this study, we aimed to compare the marginal and internal fit of single-crown restorations fabricated using digital and conventional impression techniqu

Background: Numerous intraoral scanners (IOS) devices are currently used for intraoral impressions in prosthodontics. It is crucial to assess the accuracy and precision of these devices for clinical use. Aim: This in vitro study aimed to assess and compare the accuracy and precision of six IOS in the all-on-4 treatment concept. Trueness evaluation involved aligning the data from six dental scanners with the reference model. Precision analysis encompassed aligning the data from all six scanners within their respective groups. Methods: An edentulous maxillary model was utilized, with four implants placed at 12, 15, 22, and 25 teeth positions, simulating the all-on-4 approach using resin acrylic. Following the placement of scanbodies, each of the six IOSs (Primescan, Trios 3, Trios 4, Trios 5, Virtuo Vivo, and Medit i 700) performed eight scans of the model. An industrial scanner was employed for the control group. Data alignment and comparison were executed using the CloudCompare software (v2.11.3, General Public License of Telecom ParisTech, Paris, France). Statistical scrutiny encompassed the Shapiro–Wilk, Levene’s, and Games–Howell tests. Results: Among the scanners, Primescan exhibited the highest trueness (35.75 ± 26.08 μm), whereas the Medit i700 demonstrated superior precision (0.163 μm). Conclusion: IOS can be used to make dental impressions within the all-on-4 concept. More comprehensive and clinical studies are needed on this subject.