Journal of oral science最新文献

Purpose: To evaluate the effect of die spacer thickness on the fit and load to failure of cantilever resin-bonded fixed dental prostheses (RBFDPs).

Methods: Two identical maxillary RBFDPs with a retainer on the canine were designed to replace a lateral incisor. One design involved a closely fitting retainer with no die spacer (NDS), and the other included an 80-µm die spacer (DS). A total of 10 RBFDPs were produced for each group by selective laser melting. To simulate a natural canine abutment, lithium disilicate abutments were fabricated digitally. After bonding the RBFDP with an adhesive resin luting agent, the marginal fit was measured, and the specimens were then loaded until failure of the luting agent.

Results: The mean marginal fit in the NDS and DS groups was 79.1 µm and 75.7 µm, respectively, and the corresponding mean maximum load to failure was 272.8 N and 254.7 N, respectively. The inter-group differences in these values were not significant.

Conclusion: The inclusion of a RBFDP die spacer had no effect on the marginal fit and maximum load to failure. In addition, the die spacer had no significant effect on the pattern of resin luting agent failure.

Purpose: This study evaluated how the formation of various types of precipitates affects the accuracy of electronic apex locators in determining the working length.

Methods: Two hundred and forty extracted human maxillary incisors were selected. A total of eight groups were used: four groups (n = 30) for the application of different irrigants; saline, sodium hypochlorite (5.25% NaOCl), chlorhexidine (2% CHX) and ethylenediaminetetraacetic acid (EDTA) (17% EDTA), and four groups (n = 30) for the formation of precipitates; orange-brown (2% CHX + 5.25% NaOCl), orange-white (2% CHX + 0.16% NaOCl), white milky (2% CHX + 17% EDTA), salt (2% CHX + saline). Electronic working length was determined by two different electronic apex locators.

Results: The success rate of the 5.25% NaOCl group was significantly higher than that of the white milky precipitate group. The electronic apex locators were highly effective in identifying working length, but the success rate of both devices declined due to the production of a white milky precipitate.

Conclusion: The study emphasizes the importance of selecting appropriate irrigation protocols for optimal treatment outcomes, as the chemical interactions between solutions and precipitates significantly influence electronic apex locator measurements, highlighting the need for careful consideration of irrigant compatibility.

Purpose: This laboratory-based study evaluated the effects of sintering protocols, yttria content, and zirconia thickness on the optical properties of monolithic zirconia.

Methods: Three partially stabilized zirconia (PSZ) materials, one monolayer (HT) and two multilayer (GE, FX) samples, with thicknesses of 0.5-1.5 mm were tested under conventional and speed sintering protocols. Translucency parameter (TP), color difference (ΔE₀₀), and spectral reflectance were measured using a spectrophotometer against standardized black and white backgrounds. Statistical analyses were performed using a one-way analysis of variance, Tukey's post-hoc tests, and correlation analysis.

Results: The TP values decreased with increasing zirconia thickness; significant differences were observed between the sintering protocols. Speed sintering resulted in lower transparency in certain materials, particularly GE. Conversely, HT exhibited consistent optical properties across the sintering protocols. The ΔE₀₀ values for multilayer zirconia exceeded clinically acceptable thresholds, with greater variations observed for thicker specimens. Spectral reflectance curves were minimally influenced by the sintering protocol and thickness for monolayer zirconia, whereas they showed significant variations for multilayer zirconia.

Conclusion: The results indicate that sintering protocols and material composition significantly influence the optical properties of zirconia, underscoring the necessity of optimizing processing conditions to enhance both esthetic and functional performance in clinical applications.

Purpose: Oral hygiene is mainly maintained by mechanical plaque removal, but this is often inadequate in older adults. Isodecyl galactosides (ID-Gal) inhibits bacterial co-aggregation and could promote the maintenance and improvement of oral hygiene. In this study, the efficacy of ID-Gal-containing foam dentifrice in oral hygiene among older adults was evaluated.

Methods: Fifty-six subjects aged 65 years or older visited Tokushima University Hospital and were randomly assigned to interventions using ID-Gal-containing foam dentifrice applied to the dorsum of the tongue, or to controls using their usual dentifrice. Microbiological and clinical oral health parameters were evaluated before, and at 1 and 2 months after the intervention.

Results: The intervention group showed significant decreases in black pigment-producing bacteria on the dorsum of the tongue, Fusobacterium, and total bacterial counts on the mucosa below the denture base after 1 month. Additionally, the intervention group showed significant decrease in the Winkle Tongue Coating Index (WTCI) after 2 months.

Conclusion: ID-Gal-containing foam dentifrice decreased the number of bacteria by suppressing plaque formation and contributed to a reduction in the number of bacteria on the tongue and the WTCI. Collectively, these results suggest that ID-Gal-containing foam dentifrice is effective in maintaining and improving oral hygiene.

This study was conducted to clarify the usefulness of a newly developed occlusal force device. An arbitrary load was applied to the device 100 times, and the measured values were recorded. The loading and measured values were extremely close, and the error rate was fairly small. There was a close relationship between the occlusal force measured with a device based on the dental prescale and that measured using the new device. These results suggest that the newly developed device can measure and evaluate occlusal force with a degree of accuracy equivalent to the dental prescale.

Purpose: To compare the clinical success of different forms of vital pulp therapy using various pulp-capping materials.

Methods: Two independent researchers selected relevant articles from databases, extracted data, evaluated bias risk, and performed meta-analysis. Among 337 studies retrieved, 21 with a total of 1,816 participants and 1,948 treated permanent teeth were eligible and selected for 17 types of comparison. Meta-analysis was conducted for only six of these 17 comparisons.

Results: Among the six comparisons, the success of direct pulp capping with mineral trioxide aggregate (MTA) was significantly higher than that using calcium hydroxide (relative risk = 1.21, 95% confidence interval = 1.02-1.42, P = 0.03). There was no significant difference in the success of direct pulp capping between mineral trioxide aggregate and biodentine, nor between partial pulpotomy and full pulpotomy for either type of pulp capping material.

Conclusion: The use of MTA for direct pulp capping appears to yield significantly better clinical success than the use of calcium hydroxide.

Purpose: This study investigated the relationship between periodontitis severity and oral health-related quality of life (OHRQoL) among Korean adults.

Methods: This retrospective study included 291 adults aged 20-59. Age, sex, dental visits during the past year, frequency of tooth brushing, number of teeth, and dental caries were designated as confounders, and their information was collected. The severity of periodontitis was dichotomized into no/mild and moderate/severe. OHRQoL was evaluated using the Korean version of the 14-item oral health impact profile (OHIP-14K). Logistic and negative binomial regression analyses were used to calculate odds ratios (OR) or incidence rate ratios (IRR) with 95% confidence intervals (CI).

Results: The prevalence, severity, and extent of oral impact according to total OHIP-14K score were significantly higher in patients with moderate/severe periodontitis than in those with no/mild periodontitis (P < 0.05). The adjusted regression model indicated that age, sex, number of teeth and severity of periodontitis (OR = 2.22, 95% CI = 1.23-3.99) were significantly associated with the prevalence of impacts. Regarding the severity of impacts, sex, dental visits, and severity of periodontitis (IRR = 1.44, 95% CI = 1.16-1.79) were significantly associated with OHRQoL. Regarding the extent of impacts, sex, and severity of periodontitis (IRR = 1.85, 95% CI = 1.21-2.84) were significantly related to OHRQoL.

Conclusion: The severity of periodontitis is inversely related to the OHRQoL in Korean adults.

Purpose: The purpose of this study was to investigate swallowing function of older adults with lowered hyoid bone position.

Methods: A total of 60 older adults (23 males and 37 females, mean age: 70.1 years) with no diagnosed dysphagia participated in the study. Participants were divided into two groups (High and Low group) based on the anterior point of the hyoid bone (H) with respect to the line connecting the most inferior and anterior point on the corpus of the third cervical vertebra (C3) and Menton (Me). Swallowing function was measured using the Repetitive Saliva Swallow Test (RSST), the Eating Assessment Tool (EAT-10), jaw-opening force (JOF) and tongue pressure (TP). Each group was studied for its relationship to swallowing function. Additionally, the RSST of males and females in the Low group were compared.

Results: Males in the Low group had a significantly higher JOF (P = 0.009) in the RSST ≥ 5 group than in the RSST < 5 group. Females in the Low group had no measurements that showed significant differences between the RSST ≥ 4 and RSST < 4 groups.

Conclusion: JOF may affect swallowing function in older males with lowered hyoid bone position.

Purpose: Inorganic polyphosphate (PolyP), a polymer of orthophosphate, strongly promotes mineralized tissue formation. This study explored the conditions necessary for PolyP to induce calcified deposits in cartilage and assessed the role of insulin in modulating PolyP-induced tissue calcification.

Methods: Murine chondrogenic ATDC5 cells were cultured under growth, mineralization, or PolyP-induced calcification conditions, with or without insulin. Calcified nodules were stained with Alizarin Red S, and conditioned media were analyzed for pH and lactate concentration using a pH meter and a lactate assay kit-WST.

Results: PolyP treatment of ATDC5 cells led to calcified deposits by day 5, both with and without insulin. However, in the presence of insulin, these deposits were nearly fully decalcified by day 14. Conditioned media with insulin had a lower pH and a higher lactate concentration compared to those without insulin, with lactate levels sufficient to demineralize the PolyP-induced calcified deposits.

Conclusion: These data suggest that treatment of ATDC5 chondrogenic cells with PolyP accelerates the formation of mineralized tissue. However, PolyP-induced calcified nodules undergo demineralization owing to lactate production by cells in the presence of insulin.

Purpose: The purpose of this study was to investigate the influence of substrates under the three-dimensional periodontal ligament (3D PDL) tissue on its biological functions after compressive stimulation.

Methods: A 3D PDL tissue was created using a poly(L-lactic acid) (PLLA) porous scaffold impregnated with human periodontal ligament fibroblasts (hPDLFs). It was then placed on a polyetheretherketone (PEEK) substrate, which has a comparable elastic modulus to bone and was compressed (25 g/cm²) for 1, 3, and 7 days. The morphology and biological functions of the hPDLFs in the 3D PDL tissue on the PEEK substrate were evaluated and compared with those on the polystyrene (PS) substrate.

Results: Compressive forces for the PLLA porous scaffold on the PEEK substrate were higher than those on the PS substrate. hPDLFs were present throughout the PLLA porous scaffold and there was no morphological change upon compressive stimulation. Increased expression of osteoclastogenic genes was observed after 3 days of compressive stimulation, while the level of these genes was increased by changing the substrate under the PDL tissue from PS to PEEK.

Conclusion: The substrate placed under the PDL tissue during compressive stimulation affects the biological functions of hPDLFs.