Choi J, et al. J Dent Anesth Pain Med. 2021 Apr;21(2):87-98. https://doi.org/10.17245/jdapm.2021.21.2.87

This study aimed to investigate the influence of changes in age-related physiological muscular and dental factors on masticatory function. This study was conducted in 211 healthy participants divided into four different age groups: 20–45 years (Gr1); 45–60 years (Gr2); 61–70 years (Gr3); and ≥71 years (Gr4). For objective evaluation of masticatory function, the masticatory performance, bite force, posterior bite area (PBA), functional tooth units (FTUs), the number of remaining teeth, tongue pressure, masseter muscle thickness (MMT), and handgrip strength were examined. Food intake ability (FIA) and the Oral Health Impact Profile-14 score were assessed subjectively using questionnaires. A significant decrease in the number of remaining teeth, FTUs, handgrip strength, and FIA was found in Gr4, and a significant decrease in the tongue pressure, PBA, and bite force was found in those aged ≥61 years. In groups 1 and 3, an association of the PBA with masticatory performance was observed. However, there was no significant decreasing trend in the MMT with respect to masticatory performance with aging. With sufficient FTUs and posterior tooth support, although age-dependent decreases in the bite force, tongue pressure and handgrip strength were observed, masticatory performance was maintained. Establishing the PBA by improving occlusion through dental treatment is thought to be important for masticatory function.

During the three-dimensional (3D) printing process of a dental prosthesis, using photopolymer resin, partially polymerized resin is further cured through the postcuring process that proceeds after the printing, which improves the stability of the printed product. The mechanical properties of the end product are known to be poor if the postcuring time is insufficient. Therefore, this study evaluated the effect of the postcuring time of the 3D-printed denture base on its dimensional stability, according to the aging period. The 3D prints were processed after designing maxillary and mandibular denture bases, and after the following postcuring times were applied: no postcuring, and 5, 15, 30, and 60 min. The dimensional stability change of the denture base was evaluated and analyzed for 28 days after the postcuring process. The trueness analysis indicated that the mandibular denture base had lower output accuracy than the maxillary denture base, and the dimensional stability change increased as postcuring progressed. In the no postcuring group for the mandible, the error value was 201.1 ± 5.5 µm (mean ± standard deviation) after 28 days, whereas it was 125.7 ± 13.0 µm in the 60 min postcuring group. For both the maxilla and the mandible, shorter postcuring times induced larger dimensional stability changes during the aging process. These findings indicate that in order to manufacture a denture base with dimensional stability, a sufficient postcuring process is required during the processing stage.

This study attempted to determine the dimensional stability of maxillary and mandibular edentulous denture bases constructed using three-dimensional (3D) printing systems based on stereolithography and digital light processing according to the postcuring treatment time and the removal time of the support structure. Three-dimensional printing of the designed denture base file was performed using two types of 3D printing photocurable resin (standard gray resin (Formlabs) (Somerville, MA, USA) and MAZIC D resin (Vericom) (Anyang, Korea)) and their compatible 3D printers (Form3 (Formlabs) and Phrozen Shuffle (Phrozen) (Hsinchu City, Taiwan)). Different postcuring times (no postcuring, and 15, 30, 45, and 60 min) and times of removal of the support structure were set for each group. Data relating to the denture bases in all groups were obtained using 3D scanning with a tabletop scanner after postcuring. All acquired data were exported to 3D analysis software, and the dimensional changes during postcuring of the denture base were analyzed using RMSE (root-mean-square error) values. It could be confirmed that the dimensional changes increased with postcuring time, and the accuracy was higher in the maxilla than in the mandible. The accuracy was highest for the group in which the postcuring process was performed while the support structure was present.

Doh RM, et al. J Dent Anesth Pain Med. 2018 Jun;18(3):177-182. https://doi.org/10.17245/jdapm.2018.18.3.177

This report describes a case of teriparatide (TPTD) therapy for bisphosphonate (BP)-related osteonecrosis of the jaw induced after implant placement. A 75-year-old woman taking oral BP was referred with uncontrolled osteonecrosis of the mandible related to the implant placement. With conservative treatment, BP was suspended and daily subcutaneous injections of 20 μm/d TPTD were started. After 4 months of the therapy, fixture removal and sequestrectomy were performed. Histological analysis revealed necrotic lamellar bone and empty osteocytic lacunae. In contrast, multiple irregular reversal lines of the lamellar bone and active osteoblasts were noted adjacent to the lesion. There was a significant increase in serum C-terminal telopeptide cross-link of type 1 collagen and serum osteocalcin after commencement of the therapy. After 7 months off therapy, the serum levels of the 2 markers remained at a high level compared with the baseline.