European Journal of Oral Sciences最新文献

This study aimed to investigate the effect of autoclave sterilization on the leaching of nickel ions from stainless steel crowns and space maintainer bands used in pediatric dentistry. Sixty space maintainer bands and 60 stainless steel crowns were divided into sterilized (Amsco Century V-120 Prevac steam sterilizer) and non-sterilized groups. These samples were immersed in artificial saliva, placed in individual petri dishes, and then incubated at 37°C. The samples were analyzed for 42 days using a gas chromatography-mass spectrometry (GC-MS) machine to quantify the release of nickel ions. Nickel release was higher in the sterilized samples than in the non-sterilized samples for both space maintainer bands and stainless steel crowns. This trend persisted throughout most days of the experiment, with a peak release observed on day 7. Autoclave sterilization had a significant impact on ion release, raising potential concerns regarding the material's biocompatibility. Dentists should be mindful of the increased nickel release observed from sterilized crowns and bands, as this information could influence treatment decisions, especially in children who are predisposed to allergies.

An increasing number of patients with malocclusion are choosing clear aligners for treatment, leading to a substantial rise in their production. Given the potential environmental impact of plastic products, recycling clear aligners is crucial. This study employed alkaline hydrolysis to recover the degradation products of clear aligners. The aligners were subjected to hydrolysis under various reaction conditions, including different concentrations of sodium hydroxide (NaOH), temperature, reaction time, ethanol-to-water mass ratio, and stirring rate. After the reaction, the organic components were isolated using thin-layer chromatography (TLC) plates, and their structure was characterized by ¹H-NMR spectroscopy and mass spectrometry. The degradation product was identified as 4,4′-methylenedianiline (MDA). The optimal reaction conditions for achieving the maximum degradation yield of MDA were determined to be stirring at 300 rpm at 130°C in a solution containing 5 wt% NaOH and a 1:1 mass ratio of ethanol to water for 24 h. This method demonstrates that clear aligners can be effectively recycled through alkaline hydrolysis, supporting global efforts to reduce environmental emissions.

This study investigated the effect of porcelain firing cycles and fabrication techniques on the microstructure, marginal, and internal fit of implant-cemented cobalt-chromium alloys (Co-Cr) frameworks. Two groups of Co-Cr specimens were prepared: one using selective laser melting (SLM) and the other through the lost wax-casting technique (C). Each group was further divided into two subgroups: as-manufactured and porcelain-fired specimens. The microstructure was analyzed using x-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM/EDX). Ten Co-Cr frameworks per manufacturing technique were fabricated, with marginal and internal discrepancies measured using micro-CT before and after the firing cycles. The results were analyzed by two-way ANOVA and Tukey multiple-comparison tests. The results showed a mixed microstructure of γ-fcc and ε-hcp cobalt-based phases, with porcelain firings increasing ε-Co content, especially in group C. The C specimens exhibited distribution of small pores, while no pores/defects were found in the SLM group. The SLM group, although not at a statistically significant level, showed reduced marginal and internal discrepancy values after firings. In the same behavior pattern, the C group exhibited statistically significantly lower discrepancy values. Ultimately, all subgroups demonstrated clinically acceptable marginal adaptation, but the SLM frameworks exhibited superior marginal and internal fit which remained unaffected by the firing cycles.

Dental black stain is a form of external discoloration appearing as a dark line or an incomplete coalescence of dark spots in the cervical third of the tooth. This review aims to provide an up-to-date clinical and biological summary of dental black stain of bacterial origin. Black stain is esthetically unwelcome to patients, and clinicians frequently attempt its removal. Dental black plaque has a prevalence rate of 2.4%–20% affecting both genders equally and may appear throughout the lifetime. Most studies investigating the microflora of black stain reveal that Actinomyces spp. are the most abundant species found. Most authors have found a correlation between black stain and a low caries incidence. Interestingly, individuals with black stain demonstrate higher salivary concentrations of iron, sodium, copper, and calcium/phosphate, higher pH, and lower salivary flow. Standard treatment involves repeated professional ultrasonic cleaning. Alternative treatments include photo-dynamic therapy, application of virgin coconut oil, peroxide therapy, lactoferrin, or oral probiotics. Our best interpretation of the causes implicates the involvement of oral bacteria, resulting in the deposition of iron ions in patients with altered salivary composition. The use of any treatments should be balanced against potential damage to the teeth as a result of the therapy.

This study aimed to assess the impact of flavonoid-based antioxidant application after in-office bleaching with 35% hydrogen peroxide on the shear bond strength of resin to bovine enamel, comparing it with 10% sodium ascorbate. Bovine enamel blocks (n = 10) were randomly assigned to one of five pretreatments: (i) no bleaching, (ii) bleaching without antioxidant application, and (iii) bleaching followed by a 1-min application of 10% sodium ascorbate, (iv) 5% naringin, or (v) 10% naringin. Color analysis was conducted using a digital spectrophotometer. Shear bond strength was assessed on two, 2-mm-diameter resin cylinders per block using a universal testing machine at 0.5 mm/min until fracture. Enamel surface morphology was analyzed using scanning electron microscopy. Shear bond strength values and color parameters (ΔE_ab, ΔE₀₀, and ΔWI_D) were analyzed using one-way ANOVA, while t-tests were used for the individual color parameters lightness (L*), green–red (a*), blue–yellow (b*), and chroma (C*). None of the antioxidants resulted in bond strength values as high as those observed without bleaching. However, application of sodium ascorbate and 5% naringin after bleaching significantly increased bond strength compared with bleached enamel without antioxidant. Antioxidants had no significant impact on color. The predominant failure modes were adhesive between the adhesive and enamel, and mixed.

The aim of this study was to investigate the effect of low oxygen environment during printing on the mechanical properties of 3D printed aligners. Thirty-six 3D printed rectangular (20 × 20 × 10 mm) specimens were fabricated using the SprintRay Pro 55 printer and equally divided into two groups. Eighteen of them were built under normal atmosphere conditions during printing (CON) and the rest by continuously purging pure (NIT), thereby eliminating the oxygen content. Both groups underwent post-curing in an illuminated chamber. Three samples from each group were analyzed by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). The remaining specimens underwent metallographic grinding/polishing followed by nano-indentation testing. The mechanical properties measured were: Martens Hardness (HM), indentation modulus (E_IT), and elastic index (η_IT). Statistically significant differences between groups were assessed using Mann–Whitney tests (α = 0.05). Both groups showed identical ATR-FTIR spectra and complete C = C conversion. No statistically significant differences in the parameters tested were seen. The medians (interquartile ranges) were HM CON: 68.0 N/mm² (65.0–71.0 N/mm²), NIT: 73.0 N/mm² (67.0–83.0 N/mm²); E_IT CON: 1999.0 MPa (1952.0–2154.0 MPa); NIT: 2047.0 MPa (1702.0–2104.0 MPa); η_IT CON: 28.0% (27.2%–29.0%) and NIT: 28.9% (27.1%–31.4%). The results of this study showed that elimination of oxygen during printing does not affect the mechanical properties of 3D printed aligners.

This study evaluated in vitro three internal fixation methods for short bilateral sagittal split osteotomy (BSSO) of the mandibular ramus using polyurethane replicas. After simulating an 8-mm mandible advancement with a counterclockwise rotation of 6° to the occlusal plane, the short BSSO was fixed bilaterally by using: (i) three linear bicortical screws; (ii) one miniplate with four monocortical screws and one bicortical screw (hybrid system); and (iii) two miniplates with eight monocortical screws. The load was measured on the central incisors or first molars bilaterally at the displacements of 1, 3, 5, and 7 mm. The data were analyzed using one-way analysis of variance (ANOVA) with Tukey's post hoc test. In addition, a linear regression analysis with dummy variables was performed for each combination of displacement and loading point. There were no statistically significant differences in the loads applied to both central incisors and first molars bilaterally among fixation methods at 1-mm displacement. However, the necessary load was larger for the two miniplates method for 3-, 5-, and 7-mm displacements. Considering the biomechanical aspects and the cost benefit related to the fixation materials, using three linear bicortical screws or a hybrid system may be more favorable than employing two miniplates with eight monocortical screws.

This systematic review examines the decontamination techniques used to clean titanium (Ti) implant surfaces covered with in vitro bacterial biofilms. The selected studies were gathered from the PubMed and Web of Science databases. These include in vitro studies investigating decontamination methods used to clean Ti implant surfaces coated with bacterial biofilms until January 2024. The determined studies were filtered according to the PRISMA guidelines, and the Science in Risk Assessment and Policy (SciRAP) was used to assess the reporting and methodological quality of the included studies. A total of 634 full-length peer-reviewed articles were identified. After excluding duplicate papers between the databases and screening according to the predefined inclusion and exclusion criteria, 13 studies were included. The decontamination methods investigated included mechanical, chemical, and physical methods, either as a single or in a combined approach. Significant variability was observed among the included studies. Combining the mechanical and physical methods with a chemical yielded the most significant reduction in both single- and multiple-species biofilms. The current results do not indicate that any single decontamination technique is more effective than others in eradicating bacterial biofilm from Ti surfaces; the combined approach was more advantageous than the single ones.

Changes in the protein expression pattern of osteoblastic lineage cells from the alveolar bone (OLAB) during medication-related osteonecrosis of the jaw (MRONJ) have rarely been investigated. This lack of information is partly because of the limited availability of healthy samples and the lack of human alveolar bone cell lines for research. The aim of the present study was to investigate the bone proteins collagen 1, runt-related transcription factor 2 (RUNX2), and tumor necrosis factor ligand superfamily member 11 (RANKL). Furthermore, we established a cell lineage of OLAB suitable for the analyses of protein expression. We used immunohistochemistry to determine protein expression patterns in vivo. OLAB were treated during culture with zoledronate or denosumab and analyzed by immunocytochemistry and western blotting. Collagen 1 was decreased in vivo in patients with MRONJ and in vitro by denosumab. Zoledronate reduced the level of RUNX2 in vitro. However, RANKL was not significantly affected by zoledronate or denosumab. The results of the present study will help us elucidate the cellular mechanisms of MRONJ. Although culture of OLAB with zoledronate and denosumab significantly altered the protein expression patterns, future research is needed to examine the effects of bone scaffolds, biofilms, and additional cell types mimicking in vivo conditions.

This study aimed to evaluate the effect on the mechanical and microbiological properties of incorporating calcium glycerophosphate (CaGP) and/or xylitol into resin modified glass ionomer cement (RMGIC). Six experimental cements were tested: i) RMGIC without additions; and RMGIC with ii) 5% xylitol; iii) 10% xylitol; iv) 3% CaGP; v) 3% CaGP and 5% xylitol, or vi) 3% CaGP and 10% xylitol. The compressive strength, diametral tensile strength and surface hardness were determined (24 h and 7 days). Antimicrobial/antibiofilm activity was evaluated. Compressive strength values after 24 h for +3% CaGP & 5% xylitol were higher and similar to RMGIC. After 7 days, +3% CaGP & 5% xylitol presented the highest compressive strength values. The +3% CaGP & 10% xylitol showed the lowest values of diametral tensile strength values (24 h). The RMGIC with +3% CaGP & 5% xylitol showed the highest diametral tensile strength (7 days). The surface hardness (24 h) were highest for the RMGIC and +10% xylitol. After 7 days, +3% CaGP & 5% xylitol showed the highest value. The +3% CaGP & 5% xylitol or +3% CaGP & 10% xylitol showed the lowest levels of microbial/biofilm formation. The addition of CaGP/xylitol promoted improved the mechanical and antibacterial properties of RMGIC.