Ki-Sun Lee, DDS, MSc/Sang-Wan Shin, DDS, MPH, PhD, MSc/Sang-Pyo Lee, DDS, MSc/Jong-Eun Kim, DDS, MSD/Jee-Hwan Kim, DDS, MSD, PhD/Jeong-Yol Lee, DMD, MSc, PhD: Purpose: The purpose of this pilot study was to evaluate and compare polyetherketoneketone (PEKK) with different framework materials for implant-supported prostheses by means of a three-dimensional finite element analysis (3D-FEA) based on cone beam computed tomography (CBCT) and computer-aided design (CAD) data. Materials and Methods: A geometric model that consisted of four maxillary implants supporting a prosthesis framework was constructed from CBCT and CAD data of a treated patient. Three different materials (zirconia, titanium, and PEKK) were selected, and their material properties were simulated using FEA software in the generated geometric model. Results: In the PEKK framework (ie, low elastic modulus) group, the stress transferred to the implant and simulated adjacent tissue was reduced when compressive stress was dominant, but increased when tensile stress was dominant. Conclusion: This study suggests that the shock-absorbing effects of a resilient implant-supported framework are limited in some areas and that rigid framework material shows a favorable stress distribution and safety of overall components of the prosthesis.

Purpose: The purpose of this study was to elucidate the differences of the prevalence and diameter of the posterior superior alveolar artery (PSAA) and the distance of its inferior border from the alveolar crest on computed tomography (CT) images according to age and sex. Materials and Methods: CT images of maxilla in 200 patients were randomly selected from patients who underwent CT imaging at Yonsei University Dental Hospital, and analyzed. The prevalence of the PSAA in maxillary sinus and the distance of its inferior border from the alveolar crest in the premolar and molar area were measured. Results: The average prevalence of the PSAA on CT images was 52.0%, and it is higher in males (64%) than in females (40%). The diameter of the PSAA was 1.52 ± 0.47 mm (mean ± SD), and larger in males. The distance from the PSAA to the alveolar crest was greater in the premolar area (18.90 ± 4.21 mm) than in the molar area (15.45 ± 4.04 mm), and it did not differ significantly with age or sex. Conclusions: The prevalence of the PSAA on CT images was higher, and the diameter was larger in males. The PSAA was more close to the alveolar crest in the molar areas. The evaluation of the PSAA in maxillary sinus on CT images before surgery could reduce the likelihood of excess bleeding during surgery especially in molar areas.

The aim of this study was to evaluate the biomechanical behavior and long-term safety of high performance polymer PEKK as an intraradicular dental post-core material through comparative finite element analysis (FEA) with other conventional post-core materials. A 3D FEA model of a maxillary central incisor was constructed. A cyclic loading force of 50 N was applied at an angle of 45° to the longitudinal axis of the tooth at the palatal surface of the crown. For comparison with traditionally used post-core materials, three materials (gold, fiberglass, and PEKK) were simulated to determine their post-core properties. PEKK, with a lower elastic modulus than root dentin, showed comparably high failure resistance and a more favorable stress distribution than conventional post-core material. However, the PEKK post-core system showed a higher probability of debonding and crown failure under long-term cyclic loading than the metal or fiberglass post-core systems.

The amount of photopolymer material consumed during the three-dimensional (3D) printing of a dental model varies with the volume and internal structure of the modeling data. This study analyzed how the internal structure and the presence of a cross-arch plate influence the accuracy of a 3D printed dental model. The model was designed with a U-shaped arch and the palate removed (Group U) or a cross-arch plate attached to the palate area (Group P), and the internal structure was divided into five types. The trueness and precision were analyzed for accuracy comparisons of the 3D printed models. Two-way ANOVA of the trueness revealed that the accuracy was 135.2 ± 26.3 µm (mean ± SD) in Group U and 85.6 ± 13.1 µm in Group P. Regarding the internal structure, the accuracy was 143.1 ± 46.8 µm in the 1.5 mm-thick shell group, which improved to 111.1 ± 31.9 µm and 106.7 ± 26.3 µm in the roughly filled and fully filled models, respectively. The precision was 70.3 ± 19.1 µm in Group U and 65.0 ± 8.8 µm in Group P. The results of this study suggest that a cross-arch plate is necessary for the accurate production of a model using 3D printing regardless of its internal structure. In Group U, the error during the printing process was higher for the hollowed models.