Accuracy of Dental Models Fabricated Using Recycled Poly-Lactic Acid.

Based on the hypothesis that the fabrication of dental models using fused deposition modeling and poly-lactic acid (PLA), followed by recycling and reusing, would reduce industrial waste, we aimed to compare the accuracies of virgin and recycled PLA models. The PLA models were recycled using a crusher and a filament-manufacturing machine. Virgin PLA was labeled R, and the first, second, and third recycles were labeled R1, R2, and R3, respectively. To determine the accuracies of the virgin and reused PLA models, identical provisional crowns were fitted, and marginal fits were obtained using micro-computed tomography. A marginal fit of 120 µm was deemed acceptable based on previous literature. The mesial, distal, buccal, and palatal centers were set at M, D, B, and P, respectively. The mean value of each measurement point was considered as the result. When comparing the accuracies of R and R1, R2, and R3, significant differences were noted between R and R3 at B, R and R2, R3 at P, and R and R3 at D (p < 0.05). No significant difference was observed at M. This study demonstrates that PLA can be recycled only once owing to accuracy limitations.

Effectiveness of curcumin-based antimicrobial photodynamic therapy against Staphylococcus aureus.

PURPOSE: This study investigated the effectiveness of curcumin-based antimicrobial photodynamic therapy (aPDT) against Staphylococcus aureus (S. aureus), the causative agent of ventilator-associated pneumonia. METHODS: Curcumin was added to S. aureus culture medium at concentrations of 25, 2.5, and 0.25 µM. After 60 min (20-25°C), each culture was irradiated for 1 and 3 min, and viable bacteria were counted. Curcumin (25 µM) was also added to a bacterial suspension with D-mannitol and sodium azide; microbial counts were determined after irradiation for 3 min. RESULTS: S. aureus was significantly reduced in the 1-min (P = 0.043) and 3-min (P = 0.011) irradiation groups in comparison to the 0-min irradiation group with 25 µM curcumin. No significant differences were observed between the curcumin alone group and the curcumin plus D-mannitol or sodium azide group. CONCLUSION: The findings of this study indicate that prolonged exposure (≥1 min) of S. aureus to LED in 25 µM curcumin solution induces cell wall injury. Curcumin-based aPDT as an adjunct to conventional oral care, employing existing dentistry equipment, offers a promising approach that does not rely on antimicrobial drugs or allows the emergence of resistant bacterial strains. This suggests its potential role in future strategies aimed at preventing ventilator-associated pneumonia.

Fit accuracy of resin crown on a dental model fabricated using fused deposition modeling 3D printing and a polylactic acid filament.

Purpose We considered the possibility of reducing industrial waste by fabricating and reusing dental models prepared using a fused deposition modeling (FDM) 3D printer and polylactic acid (PLA) filaments. The purpose of this study was to verify the accuracy of models fabricated using FDM and PLA.Methods The same provisional crown was used to check the marginal fit on PLA models prepared using an intraoral scanner (IOS) and FDM, plaster models made with silicone impression material and plaster, and resin models prepared using an IOS and stereolithography apparatus (SLA) 3D printer. The marginal fit was measured using micro-computed tomography at four points on the tooth: the buccal center (B), palatal center (P), mesial center (M), and distal center (D) points.Results At point B, the marginal gaps were 118 ± 21.7, 62 ± 16.4, and 50 ± 26.5 µm for the PLA, resin, and plaster models, respectively, with a significant difference between the PLA model and the other two. However, the marginal gap at all other measurement points was not significantly different between the models (P > 0.05).Conclusions We compared the accuracy of the models fabricated using the FDM, SLA, and conventional methods. The combination of FDM and PLA filaments showed no significant differences from the other models, except at point B, indicating its usefulness. Therefore, FDM and PLA may become necessary materials for dental treatment in the future.

Impact on Porphyromonas gingivalis of antimicrobial photodynamic therapy with blue light and Rose Bengal in plaque-disclosing solution.

OBJECTIVES: Antimicrobial photodynamic therapy (aPDT) in periodontal pockets using lasers is difficult to perform in some cases because of the high cost of irradiation equipment and the narrow irradiation field. The purpose of the present study was to examine the effects of aPDT in combination with a plaque-disclosing solution and blue light-emitting diode (LED), which are used for composite resin polymerization. METHODS: The reactive oxygen species generated by irradiating 0.001% RB or MB with blue light were analyzed using electron spin resonance spectroscopy. Blue-light exposure was performed at 6.92, 20.76 and 124.6 J. The microorganism to be sterilized was Porphyromonas gingivalis. After aPDT, colony-forming units (CFUs) were measured to estimate cell survival. Carbonylated protein (PC) levels were used to evaluate oxidative stress. All statistical analyses were performed with Tukey's multiple comparisons test or the unpaired t-test. RESULTS: Singlet oxygen (1O2) generation was confirmed by RB+blue LED. 1O2 production was significantly greater with the blue LED irradiation of RB than that of MB (p < 0.0001). CFUs were significantly lower in the blue LED-irradiated group than in the non-LED-irradiated group (p < 0.01). The bactericidal effect increased in a time-dependent manner. aPDT increased PC levels. No morphological changes were observed in P. gingivalis. CONCLUSIONS: The present results suggest that aPDT exerts bactericidal effects against P. gingivalis by increasing oxidative stress through the generation of 1O2 in cells. Periodontal disease may be treated by aPDT using the equipment available in dental offices.

Evaluation of Antimicrobial Effects on Dental Impression Materials and Biofilm Removal by Sodium Dichloroisocyanurate.

Dental materials are inevitably contaminated with oral microorganisms. To prevent transmission of infectious diseases, impressions need to be disinfected. In the present study, we examined the disinfection effects on impression materials and biofilm removal by sodium dichloroisocyanurate (SDIC). Exponentially growing Streptococcus mutans, Escherichia coli, Staphylococcus aureus and Candida albicans, and dental plaque bacteria were suspended in phosphate buffered saline (PBS) and exposed for 1, 5 and 10 min to 1 mL of the 10 ppm, 100 ppm, 1,000 ppm, and 10,000 ppm SDIC solutions. The bactericidal effect was evaluated by colony forming units of each microorganisms. Moreover, the effect of SDIC solution on S. mutans biofilm was examined. Bactericidal effects of SDIC solutions on oral bacteria on dental impression surfaces were assessed and the surface quality of dental casts after immersion in SDIC solution for 30 min was observed under a scanning electron microscope. The number of all bacterial strains, including plaque bacteria, were significantly decreased by SDIC solution treatment in a dose-dependent manner. Significant S. mutans biofilm removing activity of SDIC was observed in 1,000 and 10,000 ppm solution. The number of oral bacteria adhering to the surfaces of impressions markedly decreased following 10-min immersion in the 1,000 ppm SDIC solution. The 30-min immersion of dental impression in the 1,000 ppm SDIC solution did not adversely affect the surface roughness of dental casts. The results indicate that SDIC Solution is useful to deactivate oral bacteria on dental impression.

Inhibitory effect of omega-3 fatty acids on alveolar bone resorption and osteoclast differentiation.

In this study, a Porphyromonas gingivalis (P.g.)-infected mouse periodontitis model was used to investigate the effect of omega-3 fatty acid intake on differentiation and maturation of cultured osteoclast. Four-week-old C57BL/6JJcl mice were divided into four groups according to the diets they were fed from the beginning of the experiment (i.e., food containing omega-3 or omega-6 fatty acids) and whether they were orally administered P.g. Thirty-three days after beginning the experiment, bone marrow cells were sampled from the femoral bone of mice from each group and differentiated into osteoclasts; the effects of the ingestion of different fatty acids were subsequently investigated. There was no statistical interaction between the different fatty acids and P.g. infection on the number of osteoclasts (P = 0.6). However, the fatty acid type affected the number of osteoclasts in mice (P = 0.0013), with the omega-3 groups demonstrating lower osteoclast numbers than the omega-6 groups. Furthermore, the addition of resolvin E1 (RvE1), which is an omega-3 fatty acid-derived lipid mediator, suppressed the differentiation of mouse cultured osteoclasts (P < 0.0001). Therefore, the ingestion of omega-3 fatty acids may suppress osteoclast differentiation while inhibiting bone resorption and tissue destruction due to periodontitis.

Inhibitory effects of azithromycin on the adherence ability of Porphyromonas gingivalis.

BACKGROUND: Porphyromonas gingivalis is a major pathogen and has a high detection rate in periodontal disease. Fimbriae and hemagglutinin are expressed by P. gingivalis, and these play an important role in the adherence of the bacteria to periodontal tissue and biofilm formation. The aim of this study was to investigate the effects of sub-minimal inhibitory concentrations (sub-MICs) of azithromycin on the adherence of P. gingivalis, focusing on the inhibition of fimbriae expression and hemagglutinin activity. METHODS: P. gingivalis ATCC 33277 were incubated anaerobically with sub-MICs of azithromycin at 37°C by gentle shaking for 18 hours. The bacterial cells were harvested, washed twice with phosphate-buffered saline (PBS), and the proteins analyzed by 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting. Adherence assay and hemagglutinin activity tests were done with the same culture. RESULTS: The results of SDS-PAGE indicated that the sub-MICs of azithromycin inhibited 41-kDa fimbrial protein expression and hemagglutinin activities. The disappearance of 41-kDa fimbrial protein expression and long fimbriae in 0.4 µg/mL, 0.2 µg/mL, and 0.1 µg/mL of azithromycin was confirmed by western blotting and transmission electron microscopy. The adherence of P. gingivalis to human gingival epithelial cells was reduced by sub-MICs of azithromycin compared with the adherence levels without antibiotic. CONCLUSIONS: These results suggest that sub-MICs of azithromycin may reduce the adherence of P. gingivalis to host cells, by inhibiting production of fimbriae and hemagglutinin activities. Therefore, azithromycin can be used as a biofilm treatment of periodontal disease caused by P. gingivalis.

Detection of anti-citrullinated protein antibody (ACPA) in saliva for rheumatoid arthritis using DBA mice infected with Porphyromonas gingivalis.

OBJECTIVE: The anti-citrullinated protein antibody (ACPA), an autoantibody of rheumatoid arthritis (RA), is very specific in the diagnosis of RA and has been detected in early cases and several years before the onset of the disease. In this study, we focused on ACPA and examined whether it could be detected in saliva whether it is associated with periodontal disease. DESIGN: Porphyromonas gingivalis (Pg) or Escherichia coli (Ec) was administered into the oral cavity of DBA/1JJmsSlc mice. The arthritis index was measured in foot bones, and collected saliva and serum. The amount of ACPA in serum and saliva was measured using ELISA, and antibodies in serum, saliva, and foot bones were detected and analysed by western blotting. RESULT: Histopathological analysis of foot bones of the Pg/RA group detected greater inflammatory cell infiltration than in the RA group, and bone resorption was evident. Furthermore, ELISA results show that the amount of ACPA in serum was significantly higher in the Pg/RA group (P < 0.05), with a tendency to also increase in the saliva. In addition, western blotting results show a 55 kDa citrullinated protein in the serum and saliva of the RA and Pg/RA groups. CONCLUSIONS: We conclude that Pg infection increases ACPA in the serum and is reflected in the saliva, and may be involved in the inflammatory progression of RA.