Biomaterial investigations in dentistry最新文献

Background: White spot lesions (WSL), plaque buildup, and poor oral hygiene are all consequences of the intricate bracket patterns found in fixed orthodontic treatment. Therefore, coatings made of titanium oxide (TiO₂) and cobalt-doped zinc ferrite (CZFO) nanoparticles were evaluated for their antibacterial qualities to address this issue.

Objective: The objective of this study was to evaluate and compare the antibacterial effects of TiO₂ and CZFO when used as surface modificants for orthodontic stainless-steel brackets in reducing the proliferation of Streptococcus mutans (S. mutans).

Materials and methods: The study was conducted as two main groups: a TiO₂ group and a CZFO group. Each group was subsequently divided into three subgroups: a control group (petri dish containing S. mutans strain in broth without brackets), uncoated brackets (n = 20), and coated brackets (n = 20) resulting in a total of 40 brackets per group. The brackets were coated using a hydrothermal process followed by microbiological assays to determine the colony-forming units (CFU) of S. mutans.

Statistical analysis: Results were analyzed within groups using one-way ANOVA, followed by post hoc Tukey tests. Differences between the two coatings were analyzed using independent Student's t-test.

Results: In their respective groups, the TiO₂-coated and CZFO-coated brackets showed significantly lower CFUs of S. mutans (2.46 ± 0.15 and 2.93 ± 0.59 log₁₀CFU/mL, respectively) than the control group (5.07 ± 0.24 and 4.64 ± 0.30 log₁₀ CFU/mL respectively) and the uncoated brackets (4.56 ± 0.49 and 4.52 ± 0.24 log₁₀ CFU/mL respectively) (Group TiO₂-p < 0.001, Group CZFO-p = 0.004) . No significant difference in CFU was found between TiO₂ and CZFO coatings.

Conclusion: In this study, both TiO₂ and CZFO coated brackets proved to be better than their respective control groups at reducing the viability of S. mutans. CZFO coated brackets exhibited antibacterial effects comparable to UV-activated TiO₂ brackets, even under visible light.

The aim of this study was to evaluate the effect of sweat and adhesives on color stability, roughness (Ra) and Shore A hardness of two silicones for facial prostheses with different pigmentation. Samples of Silastic MDX4-4210 and A-2186 silicone were made for the proposed tests, distributed into 12 groups according to their pigmentation and adhesive used and were immersed in artificial sweat for 3 months, disinfected every 3 days with neutral soap. Measurements of color stability, roughness and hardness were performed according to ISO 21920 and CIEDE2000 using a spectrophotometer and ISO 868, respectively. There was a statistically significant color change in the two silicones used, with the groups that had the least change being those without adhesive applied to their surface (controls). There was also a reduction in roughness in all groups, with MDX4-4210 being the roughest silicone. In terms of Shore A hardness, all the groups became harder after the experimental period, with A-2186 achieving the highest results. Color change, Shore A hardness and roughness showed significant changes in the MDX4-4210 and A-2186 silicones for the proposed tests. Even so, all the results found were clinically acceptable, making both silicones excellent options for use in maxillofacial rehabilitation.

Introduction: Ca²⁺ release from specimens made of a composite containing dicalcium phosphate dihydrate particles (CaHPO₄.2H₂O, dicalcium phosphate dihydrate [DCPD]) was followed during 1 year.

Methods: Specimens were individually immersed in deionized water (n = 3). Every 2 weeks, immersion medium was collected and specimens were transferred to new vials with fresh medium. Ca²⁺ release was quantified using induced coupled plasma-optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey test (alpha: 5%).

Results: Ca²⁺ release was observed during the entire 12-month period. Cumulative release was 1635.1 ± 145.3 μg/cm² (179.7 ± 16.0 ppm), corresponding to 23.8 ± 2.0% of the total Ca mass in the specimen.

Conclusion: The tested composite was capable of sustained Ca²⁺ release in water for 1 year. In spite of the limitations of this screening test, the results suggest that composites containing Calcium phosphate (CaP) particles could offer a long-term Ca²⁺ supply to the adjacent dental tissues.

Objective: The development of ion-releasing resin composites is expected to reduce the risk of secondary caries. This study compared the degree of monomer conversion, biaxial flexural strength/modulus, elemental release, and remineralisation potential of a novel ion-releasing dental composite (Renewal MI) containing monocalcium phosphate monohydrate and polylysine.

Materials and methods: The degree of monomer conversion after light curing for 20 s was determined (n = 8). The biaxial flexural strength and modulus after immersion in water for 24 h (n = 8) were evaluated. Additionally, the release of Ca and P after immersion in water for 2 weeks was assessed (n = 3). A disc specimen of the material (n = 1) was attached to the demineralised dentine and then immersed in simulated body fluid for 2 weeks to qualitatively determine mineral precipitation on dentine. The commercial comparison included Filtek Z350 XT, EQUIA Forte HT, FUJI VII, and FUJI II LC.

Results: FUJI II LC demonstrated the highest degree of conversion (97.6%) compared to Renewal MI (57.2%) and Filtek Z350 XT (61.2%). The highest flexural strength was observed in Filtek Z350 XT (271 MPa), followed by MI (135 MPa), FUJI II LC (109 MPa), EQUIA Forte HT (50 MPa), and FUJI VII (35 MPa). The biaxial flexural modulus of Renewal MI (3.2 GPa) was comparable to that of EQUIA FORTE HT (3.8 GPa) and FUJI II LC (3.6 GPa). Ca and P release of MI (11 ppm, 45 ppm) was higher than that of FUJI VII (<0.1 ppm, 0.7 ppm). The precipitation of mineral precipitates in dentinal tubules of demineralised dentine was not detected in all materials.

Conclusion: Renewal MI demonstrated a degree of conversion similar to commercial resin composite but exhibited lower strength. However, its strength was much higher than conventional glass ionomer cements. The material promoted the high release of elements, which was expected to encourage the remineralising actions.

Purpose: This scoping review aimed to investigate how different storage media of extracted human teeth before and after preparation of specimens influence the outcomes of various dental materials intended for clinical application.

Materials and methods: Literature search in four databases and by manual searching was carried out on a predefined PIO as follows: Population - extracted human teeth; Intervention - different storage media; Outcome(s) - material properties.

Results: After screening 110 studies, 11 were included in the scoping review. Eight studies examined storage media effects before specimen preparation and three after specimen preparation. Four studies focused on enamel bonding, six on dentine, and one both on enamel and dentine. Concerning storage of extracted teeth prior to specimen preparation, cryopreservation, Chloramine T and thymol had no negative effect on bond strength to enamel. One study found Chloramine T to increase microleakage at enamel margins whereas another study found no negative effect. Storage in formalin, ethanol and thymol also had no negative effect on microleakage at enamel margins. Cryopreservation decreased bond strength to coronal dentine, but not to mid-coronal or deep dentine. Formalin, Chloramine T, ethanol and thymol had no negative effect on bond strength to dentine nor on microleakage at dentine margins. However, one study found long-term storage in Chloramine T to increase microleakage at dentine margins. Concerning storage of extracted teeth after specimen preparation, thymol significantly lowered bond strength to enamel, whereas formalin had no negative effect. Sodium hypochlorite had no negative effect on bond strength to dentine, and finally, formalin, Chloramine T, ethanol, and thymol had no negative effect on microleakage at dentine margins. Risk of bias assessment showed one high quality study, while the remaining 10 had questionable quality.

Conclusions: The effects of storage media on in-vitro dental material testing are variable and substrate-dependent, with dentine showing greater susceptibility than enamel. While distilled water and cryopreservation showed relative stability, other media like thymol and Chloramine T produced inconsistent results. Standardized protocols and further research are needed to ensure reliable and comparable outcomes.

Objective: This study examined the effect of Sr/F-bioactive glass nanoparticles (Sr/F-BAG) concentration on 1.1% NaF toothpaste. The effects of additives on pH, fluoride and elemental release, dentin remineralisation, and cytotoxicity were determined.

Materials and methods: Sr/F-BAG particles were incorporated into 1.1% NaF toothpaste (0, 1, 2, and 4 wt%). F release and pH upon immersion in deionised water were determined using a fluoride-specific electrode and pH meter (n = 8). Elemental release was analysed using Inductively Coupled Plasma Optical Emission Spectroscopy (n = 3). Dentin remineralisation (mineral-to-collagen ratio) after application of experimental toothpaste was compared using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR, n = 9). Cytotoxicity was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (n = 3). Colgate PreviDent 5000 Plus toothpaste (PV) was used as a commercial comparison.

Results: The addition of 0 to 4 wt% Sr/F-BAG linearly increased pH and F release of the 1.1% NaF toothpaste. Each 1 wt% increase in Sr/F-BAG concentration, raised pH by 0.3 and fluoride release by 457 ppm. The additives also enhanced the release of Ca, P, and Sr from the experimental toothpaste. At high concentration of Sr/F-BAG (4 wt%), the pH of the experimental toothpaste was comparable to PV (p > 0.05) but with significantly higher fluoride release (p < 0.05). However, PV demonstrated a significantly higher increase in mineral-to-collagen ratio compared to the experimental materials. The dentin surface treated with PV also showed more evident mineral precipitation. Furthermore, the experimental toothpaste containing 4 wt% Sr/F-BAG demonstrated higher cell viability (90%) than PV (56%).

Conclusion: The addition of Sr/F-BAG enhanced the release of F, Ca, P, Sr, and increased the pH of the toothpaste. However, the experimental toothpaste with added bioactive glass up to 4 wt% did not demonstrate superior remineralising effects compared to commercial 1.1% NaF toothpaste. In addition, the incorporation of Sr/F-BAG promoted the cytocompatibility of the experimental toothpaste.

Aim: This study aimed to evaluate the antibacterial, antibiofilm, antioxidant and anti-inflammatory properties and of Halimeda gracilis extracts.

Materials and methods: The H. gracilis sample was washed and extracted using methanol. The mixture was homogenized using a blender and centrifuged at high speed (10,000 × g) for 2 min, then stirred at room temperature for 30 min using magnetic stirrer, to ensure thorough extraction. Afterward, it was centrifuged at 5,000 × g for 10 min to separate the dissolved components from undissolved debris. Following this antioxidant activity was assessed using DPHH assay, the antimicrobial effects were tested against Streptococcus mutans, Escherichia coli, Enterococcus faecalis and Shigella sonnei using Kirby-Bauer disk diffusion, biofilm inhibition assay was done to assess biofilm inhibition against S. mutans, E. coli, E. faecalis and S. sonnei. Finally, the anti-inflammatory activities of the H. gracilis were determined using a modified version of the BSA assay.

Results: When tested against S. mutans, E. coli, E. faecalis, and S. sonnei strains, the antimicrobial evaluation revealed that the extract successfully inhibited biofilm formation when tested against the same organism, and it also demonstrated increased activity with increasing concentration. The zone of inhibition progressively expanded with increasing concentration, reaching a maximum of 17 mm ± 0.1 for 100 µg/mL. In terms of antioxidant activity, the H. gracilis metholic extract gradually increased from 10 µg/mL to a higher activity at 40 µg/mL in comparison to the control and blank, and then decreased at a dose of 50 µg/mL. At different doses, the anti-inflammatory action of H. gracilis extracts successfully inhibited BSA denaturation, which causes inflammation; the maximum activity has been observed.

Conclusion: This comprehensive analysis highlights H. gracilis as a valuable natural resource with multifaceted biological activities, supporting its further investigation for therapeutic applications in dentistry.

Purpose: The aim of this study was to evaluate the mechanical, surface, and optical properties of two 3D-printed crown and bridge resins (CROWNTEC and Temp PRINT). Additionally, the study assessed the effects of printing orientation and accelerated hydrothermal aging on their mechanical properties.

Materials and methods: Specimens were 3D-printed using digital light processing technology (Asiga MAX™). Mechanical properties, including flexural strength (FS), compressive strength, and fracture toughness (FT), were determined for each material following ISO standards. Three printing orientations (0°, 45°, and 90°) were used for fabricating 3-point bending specimens. Surface hardness was evaluated using a Vickers indenter. Two-body wear tests were conducted using a ball-on-flat configuration in a chewing simulator with 15,000 cycles, and wear depth was measured with a non-contact 3D optical profilometer. Disk-shaped specimens (n = 5/material) were prepared to measure translucency parameter, gloss and light penetration. For gloss measurement, specimens underwent laboratory-machine polishing (4,000-grit abrasive paper) and chairside two-step hand polishing (Top Dent DiaComposite). Posterior composite crowns (n = 10/material) were fabricated and subjected to cyclic fatigue aging (5,000 cycles at Fmax = 150 N) before quasi-static loading to fracture. The microstructure of each material was analyzed using scanning electron microscopy (SEM). Data were statistically analyzed using ANOVA and Tukey's HSD test.

Results: Hydrothermal aging, printing orientation, and material type significantly affected the FS values (p < 0.05). Temp PRINT showed superior FS (129 MPa) and FT (1.3 MPa m^1/2) compared to CROWNTEC (102 MPa, 0.9 MPa m^1/2), particularly at 0° orientation. Gloss measurements revealed no significant differences between materials (p > 0.05) across used polishing systems. SEM analysis demonstrated differences in microstructure between the materials.

Conclusion: Temp PRINT demonstrated superior mechanical performance compared to CROWNTEC, which exhibited higher translucency values. The printing orientation was identified as a critical parameter influencing the mechanical properties and overall performance of 3D printed restorations.

Introduction: Endodontic infections are biofilm-mediated, demanding effective biofilm eradication from the root canal. Root canal complexities, coupled with bacterial biofilm resistance, pose challenges to thorough disinfection. Irrigation, particularly with sodium hypochlorite, is crucial in endodontics. Activation techniques, like sonic or ultrasonic oscillations, enhance irrigant penetration and biofilm disruption, improving decontamination and treatment outcomes.The aim of the present study was to evaluate the effectiveness of XP Finisher, EndoUltra, Eddy and Irriflex in the reduction of the multispecies endodontic biofilm formed by Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans and Proteus mirabilis.

Methods: A total of 44 single-rooted mandibular premolars were selected and divided into groups for investigation: Group A: Irriflex, Group B: XP Finisher, Group C: Eddy system, and Group D: EndoUltra system. Multispecies biofilms, comprising Enterococcus faecalis, Proteus mirabilis, Pseudomonas aeruginosa, and Candida albicans, were cultured and inoculated into the pre-treated dentinal canals, which were then incubated for 16 days. Following this, the canals were subjected to the respective irrigation protocols. Bacterial counts were assessed using sterile paper points and culture techniques post-irrigation. Additionally, four non-inoculated root canals were used as negative controls for comparison.

Results: EndoUltra achieved the highest reduction in Total Bacterial Count (TBC) with a median decrease of 75% (interquartile range [IQR]: 70-80%), significantly better than XP Finisher (p = 0.001) and Irriflex (p = 0.001). Eddy led to a reduction in Pseudomonas aeruginosa (PA) with a median decrease of 85% (IQR: 80-90%), significantly outperforming Irriflex (p = 0.001) and XP Finisher (p = 0.001). For Enterococcus faecalis (EF), EndoUltra had a median reduction of 70% (IQR: 65-75%), significantly better than Eddy (p = 0.01) and Irriflex (p = 0.001), while XP Finisher resulted in a reduction of 60% (IQR: 55-65%). EndoUltra showed the highest reduction in Proteus mirabilis (ProM) with 80% (IQR: 75-85%), significantly better than Irriflex (p = 0.001) and XP Finisher (p = 0.001), with Eddy also better than Irriflex (p = 0.009). EndoUltra reduced Candida albicans (CA) by 65% (IQR: 60-70%), significantly outperforming XP Finisher (p = 0.001) and Eddy (p = 0.001).

Conclusion: Within its limitations, this study identified EndoUltra as highly effective in reducing bacterial counts, indicating its potential utility in disinfecting root canals. These findings underscore the significance of such methods in enhancing treatment outcomes and addressing root canal infections.

Over the past two decades, dental pulp regeneration has become a major focus in endodontology. The currently applied clinical strategies are referred to as 'revitalisation' procedures. These biology-based treatment strategies aim at regenerating lost pulp tissues in necrotic teeth, in the absence or even more in the presence of periapical bone lesion, clinical signs and symptoms. Such approaches are generally - but not exclusively - used in immature teeth to promote root maturation, both in length and in thickness, ultimately to reduce their risk of fracture. A growing body of evidence has led to increased understanding and reliability of these treatment strategies, which are now considered as a valid alternative treatment option besides conventional ones, mainly the apical plug technique. However, all systematic reviews evaluating clinical outcomes concluded that there is a lack of robust long-term studies on the subject; most published cases of revitalisation having a relatively short-term follow-up, usually under 2 years. In this context, several major challenges remain to be addressed to better understand the promises and limitations of revitalisation procedures as compared to other treatment options, mainly the placement of an apical plug made of hydraulic calcium silicate cement. The purpose of this paper was therefore to identify some of the important remaining challenges related to such procedures, which can be broadly categorised into biological and mechanical ones, affecting treatment success and tooth survival. Meeting these challenges requires close collaboration between both researchers and clinicians, to establish guidelines, evaluate and understand treatment outcomes, and update guidelines accordingly. However, it is not always easy for researchers to understand the clinical reality faced by practitioners. In order to facilitate their mutual understanding, the aforementioned challenges were illustrated by providing clinical context through a series of atypical clinical cases with long-term follow-up (4-8 years).