Evaluation of antibiofilm and mechanical properties of new nanocomposites based on acrylic resins and silver vanadate nanoparticles

ObjectiveThe purpose of this study was evaluate, for the first time, the impact of incorporation of nanostructured silver vanadate (β-AgVO₃) in antibiofilm and mechanical properties of dental acrylic resins (poly(methyl methacrylate), PMMA).DesignThe β-AgVO₃ was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and microanalysis (SEM/EDS). Resins specimens were prepared with 0–10% wt.% β-AgVO₃ and characterized by SEM, XRD and optical microscopy_. The antibiofim activity of the samples against Candida albicans and Streptococcus mutans was investigated by XTT reduction test, colony-forming units (CFUs), and confocal laser scanning microscopy (CLSM). The flexural strength, hardness, and surface roughness of the samples containing β-AgVO₃ were compared with the pure PMMA matrix.ResultsThe incorporation of 10% β-AgVO₃ significantly reduced the metabolic activity of C. albicans and S. mutans (p < 0.05). There was a reduction in microbial load (CFU/mL) of microorganisms for the different concentrations used (p < 0.05), which was confirmed by confocal microscopy. The addition of β-AgVO₃ did not change the mechanical properties of hardness and surface roughness of the resins (p > 0.05). However, flexural strength decreased with the addition of amounts greater than 1% (p < 0.05).Conclusionsβ-AgVO₃ additions in dental acrylic resin may have an impact on inhibition of biofilm of main microorganisms associated with dental prostheses. However, the viability of clinical use should be evaluated in function of changed promoted in some mechanical properties.     

Novel antibacterial low-shrinkage-stress resin-based cement

ObjectiveA low-shrinkage-stress resin-based cement with antibacterial properties could be beneficial to create a cement with lower stress at the tooth-restoration interface, which could help to enhance the longevity of the fixed dental restoration by reducing microleakage and recurrent caries. To date, there has been no report on the development of a low-shrinkage-stress and bio-interactive cement. Therefore, the objectives of this study were to develop a novel low-shrinkage-stress resin-based cement containing dimethylaminohexadecyl methacrylate (DMAHDM) and investigate the mechanical and antibacterial properties for the first time.MethodsThe monomers urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE) were combined and denoted as UV resin. Three cements were fabricated: (1) UV+ 0%DMAHDM (experimental control); (2) UV+ 3%DMAHDM, (3) UV+ %5DMAHDM. RelyX Ultimate cement was used as commercial control. Mechanical properties and Streptococcus mutans (S. mutans) biofilms growth on cement were evaluated.ResultsThe novel bio-interactive cement demonstrated excellent antibacterial and mechanical properties. Compared to commercial and experimental controls, adding DMAHDM into the UV cement significantly reduced colony forming unit (CFU) counts by approximately 7 orders of magnitude, metabolic activities from 0.29 ± 0.03 A₅₄₀/cm² to 0.01 ± 0.01 A₅₄₀/cm², and lactic acid production from 22.3 ± 0.74 mmol/L to 1.2 ± 0.27 mmol/L (n = 6) (p < 0.05). The low-shrinkage-stress cement demonstrated a high degree of conversion of around 70 %, while reducing the shrinkage stress by approximately 60%, compared to a commercial control (p < 0.05).ConclusionsThe new antibacterial low-shrinkage-stress resin-based cement provides strong antibacterial action and maintains excellent mechanical properties with reduced polymerization shrinkage stress.Clinical significanceA low-shrinkage-stress resin-based cement containing DMAHDM was developed with potent antibacterial effects and promising mechanical properties. This cement may potentially enhance the longevity of fixed dental restoration such as a dental crown, inlay, onlay, and veneers through its excellent mechanical properties, low shrinkage stress, and strong antibacterial properties.     

Antibacterial response of oral microcosm biofilm to nano-zinc oxide in adhesive resin

ObjectiveVarious nanoparticles are currently under investigation to impart biointeractivity for dental materials. This study aimed to: (1) formulate an experimental dental adhesive containing ZnO nanoparticles; (2) evaluate its chemical and mechanical properties; and (3) assess the antibacterial response against oral microcosm biofilm.MethodsNanosized ZnO was chemically and morphologically evaluated. ZnO was incorporated at 0 (G_CTRL), 2.5 (G_2.5%), 5 (G_5%) and 7.5 (G_5%) wt.% in an experimental dental adhesive. The adhesives were evaluated for the degree of conversion (DC), flexural strength (FS), and elastic modulus (E). The antibacterial activity was evaluated using a 48 h-microcosm biofilm model after the formation of acquired pellicle on samples’ surfaces. Colony-forming units (CFU), metabolic activity, and live/dead staining were assessed.ResultsNanosized ZnO presented characteristic peaks of Zn-O bonds, and the particles were arranged in agglomerates. The DC ranged from 62.21 (±1.05) % for G_Ctrl to 46.15 (±1.23) % for G_7.5% (p < 0.05). G_7.5% showed lower FS compared to all groups (p < 0.05). Despite achieving higher E (p < 0.05), G_2.5% did not show differences for G_Ctrl regarding the FS (p > 0.05). G_7.5% had lower CFU/mL compared to G_Ctrl for mutans streptococci (p < 0.05) and total microorganisms (p < 0.05), besides presenting lower metabolic activity (p < 0.05) and higher dead bacteria via biofilm staining.SignificanceThe dental adhesives' physicochemical properties were similar to commercial adhesives and in compliance with ISO recommendations. G_7.5% restricted the growth of oral microcosm biofilm without impairing the physicochemical performance.     

Novel antibacterial dental resin containing silanized hydroxyapatite nanofibers with remineralization capability

ObjectivesSecondary caries is the primary issue that causes restoration failure. The objectives of this study were to: (1) synthesize silanized hydroxyapatite nanofibers loaded with erythromycin (s-HAFs@EM); (2) evaluate the mechanical property, antibacterial activity, and remineralization capability of the novel dental resin containing s-HAFs@EM.Methodss-HAFs were prepared by the solvothermal approach and loaded with EM. Characterization and antibacterial activity were evaluated. Subsequently, s-HAFs@EM were incorporated into dental resin at different mass fractions (5 %, 10 %, 15 %, and 20 %), and then they were submitted to characterization, including mechanical property, antibacterial activity, remineralization capability, and cytotoxicity.Resultss-HAFs@EM were successfully synthesized, and they exhibited excellent antibacterial activity. Resin containing 15 % s-HAFs@EM exhibited the best flexural strength (118.67 ± 15.71 MPa) and elastic modulus (2.02 ± 0.30 GPa) (P < 0.05), which were increased by 65.43 % and 90.7 %, compared to those of neat resin, respectively. Resin with 15–20 % s-HAFs@EM showed high antibacterial rate (>85 %) when compared control group (P < 0.05). Furthermore, resin also exhibited a definite remineralization capability and good biosafety in vitro.SignificanceThis novel multifunctional resin with improved mechanical property, desirable antibacterial activity and remineralization capability is promising to combat secondary caries.     

Towards the development of self-healing and antibacterial dental nanocomposites via incorporation of novel acrylic microcapsules

ObjectiveThe main aim of the current work was to develop the novel self-healing dental composites contained poly(methyl methacrylate) (PMMA) microcapsules. The effects of PMMA microcapsule content in self-healing performance and mechanical properties of dental composites including flexural strength, flexural modulus, and fracture toughness were discussed. The antibacterial activity and non-toxicity properties of optimum self-healing dental composites were also investigated.MethodsNovel acrylic microcapsules were prepared using triethylene glycol dimethacrylate (TEGDMA) as healing agent and PMMA as microcapsule shell via solvent evaporation method. The silica nanoparticles with the mean size of 15–20 nm were treated by 3-methacryloxypropyltrimethoxysilane (MPS) to enhance their adhesion and dispersion within the acrylic matrix of composite. Acrylic microcapsules with mass fractions of 0%, 5%, 10%, and 15% were added into a mixture of acrylic resins and MPS-grafted SiO₂ nanoparticles. The strength and elastic modulus of dental composites were measured by the flexural test. The single edge V-notched beam (SEVNB) method was applied to investigate fracture toughness (K_IC) and healing ef?ciency. The results were then statistically analyzed using one-way analysis of variance (ANOVA) at the con?dence level of 0.95.ResultsAcrylic microcapsules were synthesized with the mean size around 30 µm and the core content of about 15 wt%. The grafting percentage of MPS surface modifier onto SiO₂ nanoparticles was measured 3.2%. The incorporation of PMMA microcapsules into the dental composites had no significant effect on flexural properties. The self-healing dental composites also indicated the high efficient healing performance in the range of 78–121%. The self-healing dental composites also exhibited impressive antibacterial activity against Streptococcus mutans (S. mutans). The MTT assay also revealed that the incorporation of acrylic microcapsules in dental composites has no cytotoxicity effects.Signi?canceIn the current study, for the first time, the self-healing dental nanocomposites contained acrylic microcapsules were prepared with excellent healing performance and antibacterial properties.     

The development and testing of glaze materials for application to the fit surface of dental ceramic restorations

ObjectivesThe aims of the study were to develop and test overglaze materials for application to the fit surface of dental ceramic restorations, which could be etched and adhesively bonded and increase the flexural strength of the ceramic substrate.MethodsThree glaze materials were developed using commercial glass powders (P25 and P54, Pemco, Canada). P25 (90 wt%) was mixed with P54 (10 wt%) to produce (P25/P54). P54 (90 wt%) was mixed with P25 (10 wt%) to produce (P54/P25). P25 (90 wt%) was mixed with 10 wt% of an experimental glass powder (P25/frit). Eighty-two disc specimens (14 mm × 2 mm) were produced by heat pressing a leucite glass–ceramic and were sandblasted with 50 μm glass beads. Group 1 control specimens (10) were sandblasted. Groups 2–4 (10 per group) were coated using P25/frit (Group 2), P25/P54 (Group 3) and P54/P25 (Group 4) overglazes before sintering. Groups 1–4 were etched for 2 min using 9.5% HF (Gresco, USA). Composite cylinders (Marathon^® v, Den-Mat) were light cured and bonded to the glazed and prepared disc surfaces and groups water stored for 8 days. Groups were tested using shear bond strength (SBS) testing at 0.5 mm/min. Disc specimens (42) were tested using the biaxial flexural strength (BFS) test at a crosshead speed of 0.15 mm/min. Group 1 was tested as sandblasted (21) and Group 2 (21) after coating the tensile surface with P25/frit. Xrd, Eds and Sem analyzes were carried out.ResultsMean SBS (MPa ± S.D.) were: Group 1: 10.7 ± 2.1; Group 2: 9.8 ± 1.9; Group 3: 1.8 ± 1.0 and Group 4: 2.6 ± 1.7. Groups 1 and 2 were statistically different to Groups 3 and 4 (p < 0.001), but there was no difference between Groups 1 and 2 and 3 and 4 (p > 0.05). The mean BFS (MPa ± S.D.) of the overglazed Group 2 (200.2 ± 22.9) was statistically different (p < 0.001) to Group 1 (150.4 ± 14.3).SignificanceThe P25/frit overglaze significantly (p < 0.001) increased the biaxial flexural strength of the leucite glass–ceramic substrate and produced comparable shear bond strengths to an etched and bonded control. The application of etched overglaze materials to dental glass–ceramic and ceramic substrates may be useful in adhesive dentistry.     

Investigating the mechanophysical and biological characteristics of therapeutic dental cement incorporating copper doped bioglass nanoparticles

ObjectiveThis study was investigated the mechanophysical properties of zinc phosphate cement (ZPC) with or without the copper doped bioglass nanoparticles (Cu-BGn) and their biological effect on dental pulp human cells and bacteria.Materials and methodsCu-BGn were synthesized and characterized firstly and then, the experimental (Cu-ZPC) and control (ZPC) samples were fabricated with similar sizes and/or dimensions (diameter: 4 mm and height: 6 mm) based on the International Organization of Standards (ISO). Specifically, various concentrations of Cu-BGn were tested, and Cu-BGn concentration was optimized at 2.5 wt% based on the film thickness and overall setting time. Next, we evaluated the mechanophysical properties such as compressive strength, elastic modulus, hardness, and surface roughness. Furthermore, the biological behaviors including cell viability and odontoblastic differentiation by using dental pulp human cells as well as antibacterial properties were investigated on the Cu-ZPC. All data were analyzed statistically using SPSS® Statistics 20 (IBM®, USA). p < 0.05 (*) was considered significant, and ‘NS’ represents nonsignificant.ResultsCu-BGn was obtained via a sol-gel method and added onto the ZPC for fabricating a Cu-ZPC composite and for comparison, the Cu-free-ZPC was used as a control. The film thickness (≤ 25 µm) and overall setting time (2.5–8 min) were investigated and the mechanophysical properties showed no significance (‘NS’) between Cu-ZPC and bare ZPC. However, cell viability and odontoblastic differentiation, alkaline phosphate (ALP) activity and alizarin red S (ARS) staining were highly stimulated in the extracts from the Cu-ZPC group compared to the ZPC group. Additionally, the antibacterial test showed that the Cu-ZPC extracts were more effective than the ZPC extracts (p < 0.05).SignificanceCu-ZPC showed adequate mechanophysical properties (compressive strength, hardness, and surface roughness) and enhanced odontoblastic differentiation as well as antibacterial properties compared to the ZPC-only group. Based on the findings, the fabricated Cu-ZPC might have the potential for use in the field of dental medicine and clinical applications.     

Development of a novel resin with antimicrobial properties for dental application

The adhesion of biofilm on dental prostheses is a prerequisite for the occurrence of oral diseases.

Objective

To assess the antimicrobial activity and the mechanical properties of an acrylic resin embedded with nanostructured silver vanadate (β-AgVO₃).

Material and Methods

The minimum inhibitory concentration (MIC) of β-AgVO₃ was studied in relation to the species Staphylococcus aureus ATCC 25923, Streptococcus mutans ATCC 25175, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. The halo zone of inhibition method was performed in triplicate to determine the inhibitory effect of the modified self-curing acrylic resin Dencor Lay - Clássico^®. The surface hardness and compressive strength were examined. The specimens were prepared according to the percentage of β-AgVO₃ (0%-control, 0.5%, 1%, 2.5%, 5%, and 10%), with a sample size of 9x2 mm for surface hardness and antimicrobial activity tests, and 8x4 mm for the compression test. The values of the microbiologic analysis were compared and evaluated using the Kruskal-Wallis test (α=0.05); the mechanical analysis used the Shapiro-Wilk''s tests, Levene''s test, ANOVA (one-way), and Tukey''s test (α=0.05).

Results

The addition of 10% β-AgVO₃ promoted antimicrobial activity against all strains. The antimicrobial effect was observed at a minimum concentration of 1% for P. aeruginosa, 2.5% for S. aureus, 5% for C. albicans, and 10% for S. mutans. Surface hardness and compressive strength increased significantly with the addition of 0.5% β-AgVO₃ (p<0.05). Higher rates of the nanomaterial did not alter the mechanical properties of the resin in comparison with the control group (p>0.05).

Conclusions

The incorporation of β-AgVO₃ has the potential to promote antimicrobial activity in the acrylic resin. At reduced rates, it improves the mechanical properties, and, at higher rates, it does not promote changes in the control.     

Correlation between nitric oxide concentration (NO2 + NO3) in saliva and CD4+ count in HIV infected adult individuals of Mangalore,Karnataka, India

AimsTo investigate the correlation between nitric oxide concentration (NO₂ + NO₃) in saliva and CD4+ count in HIV infected individuals.Study designA cross-sectional study was carried out among 60 proven HIV-positive patients selected randomly from the ART centres.MethodologyTwo groups – Control (n = 30) and study group (n = 60). The study group was divided into Group I (CD4+ count >200/cu.mm) and Group II (CD4+ count<200/cu.mm). Unstimulated saliva was collected and nitric oxide (NO₃+ NO₃) was estimated by Griess method. Statistical analysis was performed using One-way ANOVA and Tukey's Multiple Comparison Test.ResultsThe mean level of nitric oxide (NO₂ + NO₃) in control group was 43.95 ± 3.64 and in Group I with CD4 >200/cu.mm and Group II with CD4 <200/cu.mm was 51.98 ± 4.08 and 59.78 ± 4.18 respectively. ‘p’ value was statistically significant (P < 0.0001). The mean difference between Control and Group I was −7.937 (P < 0.001), Control and Group II was −15.80 (P < 0.001) and Group I and Group II was −7.867 (P < 0.001) from Tukey's Multiple Comparison Test.ConclusionsFrom our study it is now evident that salivary nitric oxide (NO₂ + NO₃) can serve as an indicator of HIV replication and saliva shows a strong potential to perform tests that are done currently in blood.     

Three-dimensional development of the palate in bilateral orofacial cleft newborns 1 year after early neonatal cheiloplasty: Classic and geometric morphometric evaluation

ObjectivesThe aim of this study was to assess palatal growth in newborns with complete bilateral cleft lip and palate (cBCLP) and bilateral cleft lip and palate with tissue bridges (BCLP + B) 1 year after early neonatal cheiloplasty (ENC).Material and methodsThe methodology was based on classic and morphometric analysis of dental models of newborns with cBCLP or BCLP + B. These analyses included metric analysis, coherent point drift-dense correspondence analysis, superprojection methods, and multivariate statistics. Dental casts were observed in two age categories, which were compared with each other. The first cast was obtained from each patient before ENC (T0, 5 ± 5 days) and the second one prior to palatoplasty (T1, 12 ± 6 months).ResultsFifty-two dental models obtained from 26 newborns with cBCLP and BCLP + B were evaluated. The results showed that over the 12-month period, alveolar clefts were narrowed in both cleft types due to anterior growth combined with the formative effect of suturing. This was confirmed by decreases in the dimensions of the right (T0 9.93 ± 2.80 mm, T1 6.64 ± 2.43 mm; p ≤ 0.003) and left (T0 10.71 ± 4.13 mm, T1 6.69 ± 4.29 mm; p ≤ 0.003) alveolar clefts in cBCLP patients. Similar reductions in alveolar cleft widths occurred on the left side (T0 11.69 ± 4.75 mm, T1 4.34 ± 2.97 mm; p ≤ 0.001) of BCLP + B patients, while on the right side, which was connected by a combined tissue bridge, there was non-significant narrowing of the alveolar cleft (T0 1.61 ± 1.34 mm, T1 1.04 ± 0.70 mm; p = 0.120). The ENC did not restrict posterior palatal growth, meaning that intertuberosity width was extended in cBCLP (T0 32.80 ± 3.15 mm, T1 35.86 ± 2.80 mm; p ≤ 0.001) and in BCLP + B neonates (T0 34.01 ± 2.15 mm, T1 36.21 ± 2.14 mm; p ≤ 0.004). Width and length measurements in the observed groups showed growth tendencies equivalent to those in noncleft or LOP patients. Palatal variability was greater in neonatal cBCLP, but was reduced during the monitored period, approximating that for BCLP + B. Regions with the most notable palatal growth were located primarily at the premaxilla and at the anterior and partially posterior ends of the maxillary segments.ConclusionEarly neonatal cheiloplasty had no negative effect on palatal growth in any direction. There was no reduction in the length or width of the palate during the first year of life, nor was there narrowing of the dentoalveolar arch. The formative effect of the operated lip on the anterior part of the palate was confirmed. This, in combination with the favorable growth, lead to closure of the alveolar cleft.     

Novel mechanically strong and antibacterial dimethacrylate copolymers based on quaternary ammonium urethane-dimethacrylate analogues

ObjectivesThis study assumed that the quaternary ammonium urethane-dimethacrylate derivative (QAUDMA-m, where m was 8, 10, 12, 14, 16, 18, and corresponded to the number of carbon atoms in the N-alkyl substituent) can be used to achieve copolymers with high mechanical performance and antibacterial activity.MethodsPhotocured copolymers of bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt%, QAUDMA-m 40 wt%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt% (BG:QAm:TEG) were characterized by the degree of conversion (DC), flexural strength (FS), flexural modulus (E), hardness (HB), and antibacterial properties (the number of bacteria colonies adhered to copolymer surfaces and inhibition zone diameter (IZD)) against Staphylococcus aureus and Escherichia coli. Reference copolymers of Bis-GMA, urethane-dimethacrylate monomer (UDMA), and TEGDMA (BG:TEG and BG:UD:TEG) were also characterized.ResultsThe DC of BG:QAm:TEGs ranged from 0.59 to 0.68, HB from 83.84 to 153.91 MPa, FS from 50.81 to 74.47 MPa, and E from 1986.74 to 3716.68 MPa. The number of S. aureus and E. coli bacteria adhered to BG:QAm:TEG surfaces was from 0 (no bacteria observed) to 6.47 and 4.99 log(CFU/mL), respectively. IZD was from 10 and 5 mm (no inhibition zone) to 23 and 21 mm, respectively. Three copolymers: BG:QA8:TEG, BG:QA10:TEG, and BG:QA12:TEG had similar or better mechanical properties than the reference copolymers, but unlike them, they showed high antibacterial activity against both bacteria strains.SignificanceThe obtained copolymers can offer a good, mechanically efficient, bioactive alternative to BG:TEG and BG:UD:TEG copolymers. The use of such materials can help to make progress in dental health care.     

The relationship between chronological age,dental age,and salivary alkaline phosphatase in Indonesian children aged 8–14 years: A cross-sectional study

BackgroundInability to predict dental age accurately has long been the Achilles heel of pediatric dentistry. Whilst dental age has an important aspect in clinical practice, saliva can be one of the most practically important diagnostic tools to estimate biological age.AimsThis study aimed to analyze a correlation between chronological age, dental age, and salivary alkaline phosphatase in Indonesian children aged 8–14 years.MethodsThis study was an observational study with cross-sectional design. Twenty healthy children (10 boys and 10 girls) were selected by consecutive sampling. Chronological age was assessed by recording date of birth. Dental age was assessed by orthopantamogram following Demirjian's method. Salivary samples were collected by passive drool method and estimation of alkaline phosphatase was done by autoanalyzer.ResultsNormality test was assessed using Kolmogorov-Smirnov and Shapiro-Wilk test. Statistical analyses were assessed using Spearman's rank-order correlation coefficients. Results are presented as mean ± standard deviation (SD). Mean chronological age was 10.504 ± 1.895 years, mean Demirjian's score was 91.74 ± 5.972, and mean salivary alkaline phosphatase was 291.563 ± 115.135 pg/ml. There is a very strong positive correlation between chronological age and dental age (r = +0.804; p < 0.001). On the contrary, levels of salivary alkaline phosphatase was negatively correlated to dental age (r = −0.780; p < 0.001) and chronological age (r = −0.508; p = 0.022).ConclusionsThis study showed strong correlation between dental age, chronological age, and salivary alkaline phosphatase; hence, estimation of dental age and salivary alkaline phosphatase in Indonesian children during early and late childhood has significant meaning to chronological age.     

Functional outcome of two different grafting techniques in the surgical management of oral submucous fibrosis: a comparative evaluation

Objective

To evaluate the functional efficacy of two different grafting techniques following the fibrotomy among subjects with oral submucous fibrosis (OSMF).

Design

Forty consecutively treated OSMF subjects between 20 and 40 years who had grades 3 and 4a OSMF and mouth opening?<?15 mm were included in the present study. All the subjects were randomly divided into two groups. In Group I, all the subjects received a buccal pad of fat sandwiched with a nasolabial flap following fibrotomy. In contrast, Group II subjects received a buccal pad of fat combined with a collagen graft. The effect of two different surgical protocols on mouth opening was evaluated clinically before the surgery (T₀) and 1 month (T₁), 6 months (T₂), and 12 months (T₃) after the surgery.

Results

In Group I subjects, the mouth opening increased significantly (P?<?0.001) from 10.90?±?1.971 mm at T₀ to 34.25?±?3.127 mm at T₁, but reduced marginally to 32.15?±?3.422 mm at T₂, and 31.30?±?3.358 mm at T₃. In Group II, the mouth opening increased significantly (P?<?0.001) from 10.85?±?1.725 mm at T₀ to 28.90?±?3.059 mm, 29.10?±?2.808 mm, and 28.20?±?2.285 mm at T₁, T₂, and T_3, respectively. At the end of 12 months of follow-up, the mean value improvement in the mouth opening (T₀–T₃) was 20.4?±?3.5 mm and 17.3?±?2.9 mm in Groups I and II, respectively, and the difference was statistically significant (P?=?0.006).

Conclusion

The buccal pad of fat sandwiched with a nasolabial flap for the reconstruction following fibrotomy had a slightly better beneficial effect on the postoperative mouth opening among OSMF subjects.

     

PEG-CL/LA膜负载甲硝唑药物的体外缓释及抗菌性能研究

目的 研究以聚乙二醇-聚己内酯-丙交酯（PEG-CL/LA）为聚合物载体的甲硝唑缓释膜的体外抗菌和药物释放性能,旨在研制一种新型的具有抗菌作用的药物缓释膜。方法 用紫外分光光度法测定5wt%、8wt%及10wt%甲硝唑药膜中药物的体外释放度;选用牙周可疑致病菌具核梭杆菌（Fn）和致龋菌变异链球菌（Sm）,采用抑菌圈法研究3种药膜对厌氧菌和兼性厌氧菌的抗菌性能。结果（1）药膜在载药量为5wt%~10wt%时具有较好的缓释性能,药物释放时间随着甲硝唑含量的增加而缩短,3种比例的载药膜的药物释放时间均可达7天以上,其中,5wt%药膜可达10天。（2）随着药物含量增加,抗菌作用逐渐增强,5wt%载药膜对Sm和Fn的抑菌圈直径分别为（8.00±0.16） mm和（8.07±0.09） mm;8wt%载药膜为（10.13±0.19） mm和（11.13±0.09） mm;10wt%载药膜为（12.07±0.09） mm和（19.33±0.94） mm。该药膜对具核梭杆菌的抑制作用强于对变异链球菌的抑制作用。结论 PEG-CL/LA载药膜对牙周致病菌的抑制作用效果明显,且具有良好的药物缓释性能,是一种有望用来辅助治疗牙周疾病的药物膜。     

Influence of a Brazilian wild green propolis on the enamel mineral loss and Streptococcus mutans’ count in dental biofilm

ObjectiveThis study investigated the anti-demineralizing and antibacterial effects of a propolis ethanolic extract (EEP) against Streptococcus mutans dental biofilm.DesignBlocks of sound bovine enamel (n = 24) were fixed on polystyrene plates. S. mutans inoculum (ATCC 25175) and culture media were added (48 h–37 °C) to form biofilm. Blocks with biofilm received daily treatment (30 μL/1 min), for 5 days, as following: G1 (EEP 33.3%); G2 (chlorhexidine digluconate 0.12%); G3 (ethanol 80%); and G4 (Milli-Q water). G5 and G6 were blocks without biofilm that received only EEP and Milli-Q water, respectively. Final surface hardness was evaluated and the percentage of hardness loss (%HL) was calculated. The EEP extract pH and total solids were determined. S. mutans count was expressed by log₁₀ scale of Colony-Forming Units (CFU/mL). One way ANOVA was used to compare results which differed at a 95% significance level.ResultsG2 presented the lowest average %HL value (68.44% ± 12.98) (p = 0.010), while G4 presented the highest (90.49% ± 5.38%HL) (p = 0.007). G1 showed %HL (84.41% ± 2.77) similar to G3 (87.80% ± 6.89) (p = 0.477). Groups G5 and G6 presented %HL = 16.11% ± 7.92 and 20.55% ± 10.65; respectively (p = 0.952). G1 and G4 differed as regards to S. mutans count: 7.26 ± 0.08 and 8.29 ± 0.17 CFU/mL, respectively (p = 0.001). The lowest bacterial count was observed in chlorhexidine group (G2 = 6.79 ± 0.10 CFU/mL) (p = 0.043). There was no difference between S. mutans count of G3 and G4 (p = 0.435). The EEP showed pH 4.8 and total soluble solids content = 25.9 Brix.ConclusionThe EEP seems to be a potent antibacterial substance against S. mutans dental biofilm, but presented no inhibitory action on the de-remineralization of caries process.     

Fabrication of color-graded feldspathic dental prosthetics for aesthetic and restorative dentistry

ObjectiveFeasibility investigation of natural teeth shades replication on dental prosthetics fabricated via functionally graded additive manufacturing (FGAM) using combination of feldspathic porcelain (FP) and yttrium aluminum garnet cerium (Y₃Al₅O_12:Ce, YAG:Ce) as a promising esthetic restoration option.MethodsColor-graded feldspathic crown fabrication parameter through FGAM method was comprehensively examined from the slurry rheology, cure depth, debinding to sintering temperature. Effect of light absorbent also checked towards overcuring reaction during UV exposure by the shape comparison. Lastly, the flexural bending strength measured following ISO 6872:2015 to assure the applicability. Applying the studied parameter, natural teeth shades then imitated and investigated by alteration of FP and FP + 0.1 wt% YAG:Ce (Y-FP). Generated color across the structure captured through mobile camera, interpreted through the CIELAB coordinate and the gradation confirmed by the color differences (ΔE₀₀) calculated using CIEDE2000 formula.ResultParameter study indicated that 70 wt% of FP slurry with 3 wt% dispersant and 0.2 wt% light absorbent is favored. It produces excellent flowability in our FGAM system with less overcuring justified by edge margin reduction from 95.65° to 90.00° after UV exposure on rectangle shapes masking. The obtain structure also offers adequate flexural bending strength of 106.26 MPa (FP) and 101.36 MPa (Y-FP) after sintering at 780 °C. This validated the materials as class 2 dental prosthetics citing ISO 6872:2015. Color gradation was verified by the yellow b* value reduction (14.8 to −3.33) as it shifted from cervical to incisal area while ΔE₀₀ further affirmed the differences from each segment in comparison with the FP and Y-FP.SignificanceColor gradation was successfully replicated by FP and YAG:Ce composition shift via FGAM technique. This result highlights the potential of FGAM as an alternative for fabricating dental prosthetics with high efficiency and improved esthetic appeal.     

Spray-drying-assisted fabrication of CaF2/SiO2 nanoclusters for dental restorative composites

ObjectiveThe objective of this study is to develop novel CaF₂/SiO₂ nanoclusters (NCs) fillers, which can endow the dental resin composites (DRCs) with excellent mechanical properties, stable and sustained fluoride ion release, and good antibacterial activity.MethodsThe CaF₂/SiO₂ NCs were efficiently fabricated by assembling CaF₂/SiO₂ nanoparticles (NPs) as building blocks with a spray-drying technology. CaF₂/SiO₂ NCs with different SiO₂ coating amounts (20 wt%, 50 wt% and 80 wt%) were incorporated into the DRCs at the filler content of 55 wt% for the measurement of mechanical properties including flexural strength, flexural modulus, compressive strength, and hardness. The effect of the filling amount of CaF₂/50SiO₂ NCs (50 represents 50 wt% SiO₂ coating amount) in the DRCs was investigated, while CaF₂/50SiO₂ NPs were adopted as comparison group. The fluoride ion release and antibacterial activity of the DRCs with the optimal mechanical performances were evaluated. Furthermore, the statistical analyses were performed for mechanical properties.ResultsSpherical CaF₂/50SiO₂ NCs with an average size of 2.4 µm were obtained at the feed rate of 7.4 mL/min and the CaF₂/50SiO₂ NPs solid content of 2 wt% in the suspension. The optimum comprehensive performances of the DRCs can be achieved by filling 55 wt% CaF₂/50SiO₂ NCs. Compared with CaF₂/50SiO₂ NPs, the filling amount of CaF₂/50SiO₂ NCs was increased by 5 wt% (50–55 wt%), and under the same filling amount of 50 wt%, the flexural strength, flexural modulus, compressive strength, and hardness of the DRCs containing CaF₂/50SiO₂ NCs were improved by 9.8%, 17.7%, 7.5% and 69.8%, respectively. Furthermore, the DRCs filled with 50 wt% CaF₂/50SiO₂ NCs exhibited more cumulative F-release by 126% and more stable F-release rate than the counterpart filled with 50 wt% CaF₂/50SiO₂ NPs after immersed for 1800 h. And 55 wt% CaF₂/50SiO₂ NCs filled DRCs could inhibit the growth of S. mutans, reaching an antibacterial ratio of 93%.SignificanceThe spray-dried CaF₂/50SiO₂ NCs are promising fillers for the development of high-performance multifunctional DRCs.     

Comparison of Oxygen Saturation Between Nasal High-Flow Oxygen and Conventional Nasal Cannula in Obese Patients Undergoing Dental Procedures With Deep Sedation: A Randomized Crossover Trial

PurposeIn anesthetic management, it is widely accepted that obese patients are more likely to suffer airway obstructions and reductions in arterial oxygen saturation (SpO₂). Therefore, it is important to take special measures to prevent oxygen desaturation during the deep sedation of obese patients. This clinical study examined whether the use of nasal high-flow systems (NHFS) keep higher SpO₂ and reduced hypoxemia than conventional nasal cannula during the deep sedation of obese patients with intellectual disabilities for dental treatment.Materials and MethodsEighteen obese patients (body mass index: >25) with intellectual disabilities who underwent dental sedation were enrolled. In each case, sedation was induced using propofol and maintained at a bispectral index of 50 to 70. The subjects were randomly assigned to the control oxygen administration (5 L/min via a nasal cannula) or NHFS (40% O₂, 40 L/min, 37 °C) arm in alternate shifts as a crossover trial. The primary endpoint was the minimum SpO₂ value, and the incidence of hypoxemia during dental treatment was also evaluated.ResultsThe mean minimum SpO₂ value was significantly higher in the NHFS arm than in the control arm (95.8 ± 2.1 % vs 93.6 ± 4.1 %, P = 0.0052, 95% confidence interval: 0.608-3.947). Hypoxemic episodes (SpO₂: ≤94%) occurred 3 cases (16.7%) in the NHFS arm and 11 cases (61.1%) in the control arm (P = 0.0076, odds ratio: 0.127, 95% confidence interval 0.0324 - 0.630).ConclusionNHFS resulted in higher minimum SpO₂ and reduced hypoxemia than nasal cannula in obese patients during deep sedation for dental treatment.     

Mineral trioxide aggregate enriched with iron disulfide nanostructures: an evaluation of their physical and biological properties

The purpose of this study was to characterize mineral trioxide aggregates (MTA) enriched with iron disulfide (FeS₂) nanostructures at different concentrations, and to investigate their storage modulus, radiopacity, setting time, pH, cytotoxicity, and antimicrobial activity. Iron disulfide nanostructures [with particle size of 0.357 ± 0.156 μm (mean ± SD)] at weight ratios of 0.2, 0.4, 0.6, 0.8, and 1.0 wt% were added to white MTA (wMTA). The radiopacity, rheological properties, setting time, and pH, as well as the cytotoxicity (assessed using the MTT assay) and antibacterial activity (assessed using the broth microdilution test) were determined for MTA/FeS₂ nanostructures. The nanostructures did not modify the radiopacity values of wMTA (~6 mm of aluminium); however, they reduced the setting time from 18.2 ± 3.20 min to 13.7 ± 1.8 min, and the storage modulus was indicative of a good stiffness. Whereas the wMTA/FeS₂ nanostructures did not induce cytotoxicity when in contact with human pulp cells (HPCs) and human gingival fibroblasts (HGFs), they showed bacteriostatic activity against Staphylococcus aureus, Escherichia coli, and Enterococcus faecalis. Adding FeS₂ nanostructures to MTA might be an option for improving the root canal sealing and antibacterial effects of wMTA in endodontic treatments.     

Influence of microcapsule parameters and initiator concentration on the self-healing capacity of resin-based dental composites

ObjectiveFracture is one of the main causes for failure of resin-based composite restorations. To overcome this drawback, self-healing resin-based composites have been designed by incorporation of microcapsules. However, the relationship between their self-healing capacity and microcapsule and resin parameters is still poorly understood. Therefore, the objective of this study was to systematically investigate the effect of initiator concentration (in the resin) and microcapsule size and concentration on the self-healing performance of commercially available flowable resin-based composites.MethodsPoly(urea-formaldehyde) (PUF) microcapsules containing acrylic healing liquid were synthesized in small (33 ± 8 μm), medium (68 ± 21 μm) and large sizes (198 ± 43 μm) and characterized. Subsequently, these microcapsules were incorporated into a conventional flowable resin-based composite (Majesty Flow ES2, Kuraray) at different contents (5–15 wt%) and benzoyl peroxide (BPO) initiator concentrations (0.5–2.0 wt%). Fracture toughness (K_IC) of test specimens was tested using a single edge V-notched beam method. Immediately after complete fracture (K_IC-initial), the two fractured parts were held together for 72 h to allow for healing. Subsequently, fracture toughness of the healed resin-based composites (K_IC-healed) was tested as well.ResultsThe fracture toughness of healed dental composites significantly increased with increasing microcapsule size and concentration (2 wt% BPO, p < 0.05). The highest self-healing efficiencies (up to 76%) were obtained with microcapsules sized 198 ± 43 um.Significancecommercially available resin-based composites can be rendered self-healing most efficiently by incorporation of large microcapsules (198 ± 43 μm). However, long-term tests on fatigue and wear behavior are needed to confirm the clinical efficacy.