Publications by authors named "Vicente Castelo Branco Leitune"

75 Publications

Physicochemical and biological evaluation of a triazine-methacrylate monomer into a dental resin.

J Dent 2021 Sep 21;114:103818. Epub 2021 Sep 21.

Department of Dental Materials, School of Dentistry, Federal University of Rio Grande do Sul. Ramiro Barcelos Street, 2492, Rio Branco, 90035-003, Porto Alegre, RS, Brazil. Electronic address:

Objectives: This study aimed to (1) formulate blend resins with 2.5 or 5 wt.% of the methacrylate monomer 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT), and (2) to evaluate the blend resins regarding the physicochemical and biological properties.

Methods: The base resin was formulated mixing 60 wt.% of bisphenol A glycol dimethacrylate and 40 wt.% of triethylene glycol dimethacrylate with photoinitiator/co/initiator system. TAT was added at 2.5 (G) or 5 (G) wt.%, and a group without TAT was used as control (G). The resins were analyzed for degree of conversion (DC), Knoop hardness (KHN), softening in solvent (ΔKHN), ultimate tensile strength (UTS), contact angle, surface free energy (SFE), antibacterial activity against Streptococcus mutans biofilm formation, and cytotoxicity against human keratinocytes.

Results: There was no difference for the DC (p = 0.676). The addition of TAT at 5 wt.% induced higher KHN (p<0.001), higher resistance against softening in solvent (p<0.001), and higher UTS (p = 0.04). There were no statistically significant differences for contact angle with water (p = 0.106), α-bromonaphtalene (p = 0.454), and SFE (p = 0.172). The higher the TAT concentration, the higher the antibacterial activity (p<0.001). G showed no cytotoxicity compared to G (p>0.05), and G induced lower cell viability (p<0.05).

Conclusions: The addition of 2.5 wt.% of TAT is suitable for conveying antibacterial activity for dental resins without changing the physicochemical properties or impairing the cytotoxic effect.

Clinical Relevance: Methacrylate monomers that decrease bacterial viability and copolymerize with the resin matrix are exciting approaches to developing therapeutic materials. TAT showed promising properties to may hamper and prevent carious lesions when incorporated into dental materials. Further evaluations with higher cariogenic challenges will be carried to analyze the formulated materials.
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http://dx.doi.org/10.1016/j.jdent.2021.103818DOI Listing
September 2021

Microshear bond strength of dual-cure resin cement in zirconia after different cleaning techniques: an study.

J Adv Prosthodont 2021 Aug 26;13(4):237-245. Epub 2021 Aug 26.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Ramiro Barcelos, Rio Branco, Porto Alegre, RS, Brazil.

Purpose: This study aimed to compare the microshear bond strength (µSBS) of dual-cure resin cement in CAD-CAM zirconia after different cleaning techniques.

Materials And Methods: Fifty discs of zirconia-based ceramic from Ivoclar Vivadent were embedded in acrylic resin. The discs were divided into five groups according to the cleaning methods used: Group 1: drying with spraying + sandblasting with AlO; Group 2: washed with water and dried with spraying + sandblasting with AlO; Group 3: washed with distilled water and dried with spraying + sandblasting with AlO + zirconium oxide (Ivoclean); Group 4: washed with distilled water and dried with spraying + sandblasting with AlO + potassium hydroxide (Zirclean); and Group 5: washed with distilled water and dried with spraying + sandblasting with AlO + 1% NaClO. All of the groups were contaminated with artificial saliva for 1 minute and then cleaned. Statistical analyses were performed using ANOVA and Tukey's tests.

Results: There were statistically significant differences among all groups for µSBS ( < .05). The group treated with zirconium oxide (Group 3) showed the highest µSBS (18.75 ± 0.23 MPa).

Conclusion: When applied to zirconia, the cleaning methods affected the bonding with resin cement differently.
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http://dx.doi.org/10.4047/jap.2021.13.4.237DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8410303PMC
August 2021

The golden proportion concept: smile makeover with an 18-month follow-up.

Int J Esthet Dent 2021 05;16(2):216-230

Department of Esthetic and Restorative Dentistry, School of Dentistry, Universidad Científica del Sur, Lima, Peru

Aim: The altered size, shape or position of the teeth affect their proper alignment, the harmony of the smile, and the dentofacial composition. The aim of this article is to describe a minimally invasive approach to improve the esthetics of a patient through the golden proportion (GP) concept with the use of direct composite resin stratification.

Materials And Methods: A 26-year-old female complained about the appearance of her smile due to the existing spaces between her anterior teeth; her small, peg-shaped lateral incisors; the wear of her canines; and the color of her teeth. The clinical examination confirmed diastemas in the anterior teeth, peg-shaped maxillary lateral incisors, and incisal wear of the canines. Treatment with dental whitening followed by composite restorations was performed in line with the current conservative approach in dentistry. The patient was followed up for 18 months.

Conclusion: The use of the additive technique with composite for the closure of diastemas under the GP concept illustrates an example of viable management to restore esthetic harmony through a minimally invasive approach, with reliability over time and the advantages of being less laborious, less time consuming, and less expensive than other approaches. The treatment plan was acceptable to the patient.
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May 2021

Polybutylene-adipate-terephthalate and niobium-containing bioactive glasses composites: Development of barrier membranes with adjusted properties for guided bone regeneration.

Mater Sci Eng C Mater Biol Appl 2021 Jun 19;125:112115. Epub 2021 Apr 19.

Dental Materials Laboratory, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address:

This study aimed to develop bioactive guided bone regeneration (GBR) membranes by manufacturing PBAT/BAGNb composites as casting films. Composites were produced by melt-extrusion, and BAGNb was added at 10 wt%, 20 wt%, and 30 wt% concentration. Pure PBAT membranes were used as a control (0wt%BAGNb). FTIR and thermogravimetric analysis characterized the composites. Barrier membranes were produced by solvent casting, and their mechanical and surface properties were assessed by tensile strength test and contact angle analysis, respectively. The ion release and cell behavior were evaluated by pH, cell proliferation, and mineralization. Composites were successfully produced, and the chemical structure showed no interference of BAGNb in the PBAT structure. The addition of BAGNb increased the stiffness of the membranes and reduced the contact angle, increasing the roughness in one side of the membrane. Sustained pH increment was observed for BAGNb-containing membranes with increased proliferation and mineralization as the concentration of BAGNb increases. The incorporation of up to 30 wt% of BAGNb into PBAT barrier membranes was able to maintain adequate chemical-mechanical properties leading to the production of materials with tailored surface properties and bioactivity. Finally, this biomaterial class showed outstanding potential and may contribute to bone formation in GBR procedures.
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http://dx.doi.org/10.1016/j.msec.2021.112115DOI Listing
June 2021

Ionic liquid-loaded microcapsules doped into dental resin infiltrants.

Bioact Mater 2021 Sep 12;6(9):2667-2675. Epub 2021 Feb 12.

Department of Dental Materials, School of Dentistry, Federal University of Rio Grande do Sul, Ramiro Barcelos Street, 2492, Rio Branco, 90035-003, Porto Alegre, RS, Brazil.

Resin infiltrants have been effectively applied in dentistry to manage non-cavitated carious lesions in proximal dental surfaces. However, the common formulations are composed of inert methacrylate monomers. In this study, we developed a novel resin infiltrant with microcapsules loaded with an ionic liquid (MC-IL), and analyzed the physical properties and cytotoxicity of the dental resin. First, the ionic liquid 1--butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf) was synthesized. BMI.NTf has previously shown antibacterial activity in a dental resin. Then, MC-IL were synthesized by the deposition of a preformed polymer. The MC-IL were analyzed for particle size and de-agglomeration effect via laser diffraction analysis and shape via scanning electron microscopy (SEM). The infiltrants were formulated, and the MC-IL were incorporated at 2.5%, 5%, and 10 wt%. A group without MC-IL was used as a control. The infiltrants were evaluated for ultimate tensile strength (UTS), contact angle, surface free energy (SFE), and cytotoxicity. The MC-IL showed a mean particle size of 1.64 (±0.08) μm, shriveled aspect, and a de-agglomeration profile suggestive of nanoparticles' presence in the synthesized powder. There were no differences in UTS among groups (p > 0.05). The incorporation of 10 wt% of MC-IL increased the contact angle (p < 0.05), while the addition from 5 wt% reduced the SFE in comparison to the control group (p < 0.05). The human cell viability was above 90% for all groups (p > 0.05). The incorporation of microcapsules as a drug-delivery system for ionic liquids may be a promising strategy to improve dental restorative materials.
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http://dx.doi.org/10.1016/j.bioactmat.2021.02.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7895677PMC
September 2021

Incorporation of amoxicillin-loaded microspheres in mineral trioxide aggregate cement: an study.

Restor Dent Endod 2020 Nov 7;45(4):e50. Epub 2020 Oct 7.

Department of Dental Materials, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.

Objectives: In this study, we investigated the potential of amoxicillin-loaded polymeric microspheres to be delivered to tooth root infection sites via a bioactive reparative cement.

Materials And Methods: Amoxicillin-loaded microspheres were synthesized by a spray-dray method and incorporated at 2.5% and 5% into a mineral trioxide aggregate cement clinically used to induce a mineralized barrier at the root tip of young permanent teeth with incomplete root development and necrotic pulp. The formulations were modified in liquid:powder ratios and in composition by the microspheres. The optimized formulations were evaluated for physical and mechanical eligibility. The morphology of microspheres was observed under scanning electron microscopy.

Results: The optimized cement formulation containing microspheres at 5% exhibited a delayed-release response and maintained its fundamental functional properties. When mixed with amoxicillin-loaded microspheres, the setting times of both test materials significantly increased. The diametral tensile strength of cement containing microspheres at 5% was similar to control. However, phytic acid had no effect on this outcome ( > 0.05). When mixed with modified liquid:powder ratio, the setting time was significantly longer than that original liquid:powder ratio ( < 0.05).

Conclusions: Lack of optimal concentrations of antibiotics at anatomical sites of the dental tissues is a hallmark of recurrent endodontic infections. Therefore, targeting the controlled release of broad-spectrum antibiotics may improve the therapeutic outcomes of current treatments. Overall, these results indicate that the carry of amoxicillin by microspheres could provide an alternative strategy for the local delivery of antibiotics for the management of tooth infections.
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http://dx.doi.org/10.5395/rde.2020.45.e50DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7691264PMC
November 2020

Niobium silicate particles as bioactive fillers for composite resins.

Dent Mater 2020 12 29;36(12):1578-1585. Epub 2020 Sep 29.

Dental Materials Laboratory, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address:

Objectives: This study aimed to evaluate the influence of niobium silicate (SiNb) particles in the physicomechanical and biological properties of an experimental composite resin.

Methods: The SiNb particles were incorporated (50 wt%) into a polymeric matrix formulated with 70 wt% Bisphenol A-Glycidyl Methacrylate and 30 wt% Triethylene Glycol Dimethacrylate to formulate an experimental composite resin. A control group was formulated with barium silicate glass (SiBa) as filler for the same polymeric matrix. The composite resins were tested for their refractive index, polymerization kinetics, flexural strength, radiopacity, softening in solvent, pH, cytotoxicity and mineral deposition.

Results: The SiBa group presented refractive index results between 1.50 and 1.52 and the SiNb between 1.43-1.45. No statistically significant difference in the degree of conversion, flexural strength, and softening in solvent was observed between different groups. Radiopacity was lower for SiNb, while the addition of these particles increased cell viability. The pH was increased for all groups after immersion. The mineral deposition analysis resulted in increased deposition above specimens after the immersion in SBF.

Significance: Niobium silicate particles may be used as an alternative inorganic filler to achieve an adequate balance between physical-chemical and biological properties for the development of bioactive composite resins.
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http://dx.doi.org/10.1016/j.dental.2020.09.010DOI Listing
December 2020

Zinc-based particle with ionic liquid as a hybrid filler for dental adhesive resin.

J Dent 2020 11 17;102:103477. Epub 2020 Sep 17.

Department of Dental Materials, School of Dentistry, Federal University of Rio Grande do Sul, Ramiro Barcelos Street, 2492, Rio Branco, 90035-003, Porto Alegre, RS, Brazil. Electronic address:

Objectives: The aim of this study was to evaluate the effect of a zinc-based particle with ionic liquid as filler for an experimental adhesive resin.

Methods: The ionic liquid 1-n-butyl-3-methylimidazolium chloride (BMI.Cl) and zinc chloride (ZnCl) were used to synthesize 1-n-butyl-3-methylimidazolium trichlorozincate (BMI.ZnCl), which was hydrolyzed under basic conditions to produce the simonkolleite (SKT) particles. SKT was analyzed by scanning electron microscopy and transmission electron microscopy. An experimental adhesive resin was formulated and SKT was incorporated at 1, 2.5, or 5 wt.% in the adhesive. One group without SKT was a control group. The antibacterial activity against Streptococcus mutans, cytotoxicity, degree of conversion (DC), ultimate tensile strength (UTS), softening in solvent, and microtensile bond strength (μ-TBS) were investigated.

Results: SKT prepared from the ionic liquid BMI.ZnCl presented a hexagonal shape in the micrometer scale. SKT addition provided antibacterial activity against biofilm formation of S.mutans and planktonic bacteria (p < 0.05). There were no differences in pulp cells' viability (p > 0.05). The DC ranged from 62.18 (±0.83)% for control group to 64.44 (±1.55)% for 2.5 wt.% (p > 0.05). There was no statistically significant difference among groups for UTS (p > 0.05), softening in solvent (p > 0.05), and 24 h or 6 months μ-TBS (p > 0.05).

Conclusions: The physicochemical properties of adhesives were not affected by SKT incorporation, and the filler provided antibacterial activity against S. mutans without changes in the pulp cells' viability. This hybrid zinc-based particle with ionic liquid coating may be a promising filler to improve dental restorations.

Clinical Relevance: A filler based on a zinc-derived material coated with ionic liquid was synthesized and added in dental adhesives, showing antibacterial activity and maintaining the other properties analyzed. SKT may be a promising filler to decrease the biofilm formation around resin-based restorative materials.
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http://dx.doi.org/10.1016/j.jdent.2020.103477DOI Listing
November 2020

Niobium silicate as a filler for an experimental photopolymerizable luting agent.

J Prosthodont Res 2021 Feb 9;65(1):25-30. Epub 2020 Sep 9.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492/4th floor, Porto Alegre, RS.

Purpose: To synthesize niobium silicate particles (SiNb) and incorporate into resin-based luting agents.

Methods: SiNb particles were synthesized and characterized by x-ray diffraction, FTIR spectroscopy, particle size, and specific surface area. Luting agents were formulated with 50 wt% BisGMA, 30 wt% TEGDMA and 20 wt% UDMA. BAPO was used as a photoinitiator in 1mol%. The SiNb particles were incorporated into the agents at concentrations of 50 wt% (SiNb50%) or 65% wt% (SiNb65%). Barium glass particles at the same concentrations were used as controls (SiBa50% and SiBa65%). Refractive index, degree of conversion (DC), polymerization kinetics, softening in solvent, radiopacity, film thickness, color stability, flexural strength (FS) and micro shear bond strength (µSBS) were evaluated.

Results: SiNb particles were successfully synthesized with an adequate structure to be applied as inorganic fillers. SiNb groups had higher DC, lower %ΔKHN, greater film thickness and greater radiopacity than the SiBa groups. Color stability was greater for SiNb50% and SiNb65% after six months of storage, as demonstrated by ΔE00. ΔWID values were lower for the SiBa groups. FS results decreased over time, and lower values were found for SiNb. In µSBS, the values of SiNb65% were higher at 24 h (45.22 MPa) and at six months (36.83 MPa), with statistically differences from values for the SiBa groups.

Conclusions: SiNb particles were successfully synthesized using the sol-gel method, and their incorporation into luting agents at a concentration of up to 65% improved the physicomechanical characteristics and color stability of these agents.
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http://dx.doi.org/10.2186/jpr.JPOR_2019_420DOI Listing
February 2021

Wollastonite as filler of an experimental dental adhesive.

J Dent 2020 11 12;102:103472. Epub 2020 Sep 12.

Department of Dental Materials, School of Dentistry, Federal University of Rio Grande do Sul. Ramiro Barcelos Street, 2492, Rio Branco, 90035-003, Porto Alegre, RS, Brazil. Electronic address:

Objective: The aim of this study was to formulate experimental dental adhesives with wollastonite and evaluate the physical, chemical, and bioactivity properties of the resins.

Methods: Wollastonite was characterized by Fourier transform infrared spectroscopy, X-ray and laser diffraction analyses, and scanning electronic microscopy. An experimental adhesive resin was formulated, and wollastonite was used as filler at 0 (control group), 0.5, 1, or 2 wt.%. Radiopacity, degree of conversion (DC%), microhardness, softening in solvent, ultimate tensile strength (UTS), 24 h- and 1 year- microtensile bond strength (μTBS), mineral deposition, and color of the adhesives were evaluated.

Results: Wollastonite particles showed a needle-like shape, a mean diameter of 70 (± 30) μm, characteristic chemical peaks, and pure crystalline β-CaSiO phase. There were no significant differences (p > 0.05) for radiopacity, softening in solvent, and color change. The group with 2 wt.% of wollastonite showed higher microhardness and UTS in comparison to the control group (p < 0.05). After one year, the control group showed reduced μTBS compared to the immediate value (p < 0.05). The groups with wollastonite presented stable μTBS after one year in comparison to the immediate μTBS (p > 0.05). Wollastonite induced mineral deposition on the adhesive surface over the time of storage in simulated body fluid.

Conclusion: The addition of wollastonite improved the mechanical behavior of the adhesive without changing the analyzed chemical properties. The adhesives with this filler presented mineral deposition and acceptable clinical color. Moreover, dentin treated with wollastonite-doped adhesives showed higher bonding stability after one year of aging.

Clinical Significance: Wollastonite, a silicate-based material, provided bioactivity for the adhesives, which assists in producing therapeutic tooth-restoration interfaces. Moreover, the incorporation of this mineral improOfiller to improve the biological properties of adhesives and assist in dentin-restoration stability.
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http://dx.doi.org/10.1016/j.jdent.2020.103472DOI Listing
November 2020

Chemical, Mechanical and Biological Properties of an Adhesive Resin with Alkyl Trimethyl Ammonium Bromide-loaded Halloysite Nanotubes.

J Adhes Dent 2020 ;22(4):399-407

Purpose: The aim of this study was to evaluate the chemomechanical properties, antibacterial activity, and cytotoxicity of an experimental adhesive resin containing halloysite nanotubes (HNT), doped with alkyl trimethyl ammonium bromide (ATAB).

Materials And Methods: A filler of HNT doped with ATAB was obtained (ATAB:HNT) and incorporated (5 wt%) into a resin blend made of bisphenol A glycerolate dimethacrylate, 2-hydroxyethyl methacrylate and a photoinitiator/co-initiator system (GATAB:HNT). The same resin blend without ATAB:HNT was used as control (Ctrl). The ATAB:HNT filler was assessed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The two tested adhesives were evaluated for degree of conversion (DC) in vitro and in situ, softening in alcohol, dentin microtensile bond strength (µTBS), antibacterial activity, and cytotoxicity (n = 5).

Results: SEM showed that the nanotubes had a characteristic tubular-needle morphology, while the TEM analysis confirmed the presence of ATAB inside the lumens of HNT. The incorporation of ATAB:HNT induced no reduction (p > 0.05) of the DC either in situ or in vitro. No difference was encountered after the softening challenge test (p > 0.05) and no difference was found in µTBS between the two adhesives, both at 24 h (p > 0.05) and after 6 months of storage in distilled water (p > 0.05). However, ATAB:HNT reduced Streptococcus mutans viability (p < 0.05) without a cytotoxic effect on pulp cells (p > 0.05).

Conclusions: GATAB:HNT adhesive demonstrated appropriate polymerization without significant differences in softening after solvent immersion, while concomitantly maintaining reliable bond strength after 6 months of water aging. Moreover, the ATAB:HNT filler can provide antibacterial activity to the adhesive resin without affecting pulp cell viability.
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http://dx.doi.org/10.3290/j.jad.a44871DOI Listing
July 2020

Does use of silane-containing universal adhesive eliminate the need for silane application in direct composite repair?

Braz Oral Res 2020 May;34:e045

Universidade Federal do Rio Grande do Sul - UFRS, School of Dentistry , Post-Graduate Program in Pediatric Dentistry , Porto Alegre , RS , Brazil .

This in vitro study aimed to evaluate the effect of a silane-containing universal adhesive used with or without a silane agent on the repair bond strength between aged and new composites. Forty nanohybrid composite resin blocks were stored in distilled water for 14 d and thermo-cycled. Sandpaper ground, etched, and rinsed speciments were randomly assigned into four experimental groups: silane + two-step etch-and-rinse adhesive system, two-step etch-and-rinse adhesive system, silane + silane-containing universal adhesive system, and silane-containing universal adhesive system. Blocks were repaired using the same composite. After 24 h of water storage, the blocks were sectioned and bonded sticks were submitted to microtensile testing. Ten unaged, non-repaired composite blocks were used as a reference group to evaluate the cohesive strength of the composite. Two-way ANOVA and Tukey's tests were used to analyze average µTBS. One-way ANOVA and Dunnet post-hoc tests were used to compare the cohesive strength values and bond strength obtained in the repaired groups (α = 0.05). The µTBS values were higher for the silane-containing universal adhesive compared to the two-step etch-and-rinse adhesive system (p = 0.002). Silane application improved the repair bond strength (p = 0.03). The repair bond strength ranged from 39.3 to 65.8% of the cohesive strength of the reference group. Using universal silane-containing adhesive improved the repair bond strength of composite resin compared to two-step etch-and-rinse adhesive. However, it still required prior application of a silane agent for best direct composite resin repair outcomes.
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http://dx.doi.org/10.1590/1807-3107bor-2020.vol34.0045DOI Listing
May 2020

Dental Sealant Empowered by 1,3,5-Tri Acryloyl Hexahydro-1,3,5-Triazine and α-Tricalcium Phosphate for Anti-Caries Application.

Polymers (Basel) 2020 Apr 12;12(4). Epub 2020 Apr 12.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492, Rio Branco, Porto Alegre RS 90035-003, Brazil.

Quaternary ammonium compounds and calcium phosphates have been incorporated into dental materials to enhance their biointeractivity and preventive effects. This study aimed at evaluating the physical and chemical properties and effects against of a dental sealant containing 1,3,5-tri acryloyl hexahydro-1,3,5-triazine (TAT) and α-tricalcium phosphate (α-TCP). A methacrylate-based dental sealant was initially formulated. α-TCP and TAT (G) were added to the experimental sealant at 2 wt.% each. One group was formulated without α-TCP and TAT and used as control (G). All tested resins were analyzed for polymerization kinetics and degree of conversion (DC %), Knoop hardness (KHN), softening in solvent (∆KHN%), ultimate tensile strength (UTS), the contact angle with water or with α-bromonaphthalene, surface free energy (SFE) and antibacterial activity against in biofilm and in planktonic cells. The polymerization kinetic was different between groups, but without statistical differences in the DC % (p<0.05). KHN and ΔKHN% did not change between groups (p>0.05), but G presented greater UTS compared to G (p<0.05). No differences were found for contact angle (p>0.05) or SFE (p>0.05). G showed greater antibacterial activity in comparison to G (p<0.05). The formulation of dental sealants containing TAT and α-TCP can be characterized by improved mechanical and antibacterial properties.
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http://dx.doi.org/10.3390/polym12040895DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240744PMC
April 2020

Guanidine derivative inhibits C. albicans biofilm growth on denture liner without promote loss of materials' resistance.

Bioact Mater 2020 Jun 21;5(2):228-232. Epub 2020 Feb 21.

Dental Materials Laboratory, Postgraduate Program in Dentistry, School of Dentistry, Federal University of Rio Grande Do Sul, Rua Ramiro Barcelos, 2492, Rio Branco, 90035-003, Porto Alegre, RS, Brazil.

To reduce the burden of denture stomatitis and oral candidiasis, an aqueous solution containing polyhexamethylene guanidine hydrochloride (PHMGH) was investigated as an antifungal disinfectant against the leading cause of these oral conditions, . The solutions formulated with concentrations ranging from 0.125 to 0.50 wt% enabled increasing disinfection at the initial 5min-contact with 72h-mature candida biofilms formed on denture liner specimens. After 10 min-contact, the solution at lower concentration has reached total fungal elimination. The results also indicated that the denture liners preserved their mechanical property after the maximum contact time with the solution at the highest tested concentration. The PHMGH aqueous solutions at 0.125 wt% could be applied to promote interim denture liner disinfection without promoting the loss of materials' mechanical property.
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http://dx.doi.org/10.1016/j.bioactmat.2020.02.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7036732PMC
June 2020

Myristyltrimethylammonium Bromide (MYTAB) as a Cationic Surface Agent to Inhibit Grown over Dental Resins: An In Vitro Study.

J Funct Biomater 2020 Feb 15;11(1). Epub 2020 Feb 15.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, 90035-003 Porto Alegre-RS, Brazil.

This in vitro study evaluated the effect of myristyltrimethylammonium bromide (MYTAB) on the physical, chemical, and biological properties of an experimental dental resin. The resin was formulated with dental dimetacrylate monomers and a photoinitiator/co-initiator system. MYTAB was added at 0.5 (G), 1 (G), and 2 (G) wt %, and one group remained without MYTAB and was used as the control (G). The resins were analyzed for the polymerization kinetics, degree of conversion, ultimate tensile strength (UTS), antibacterial activity against , and cytotoxicity against human keratinocytes. Changes in the polymerization kinetics profiling were observed, and the degree of conversion ranged from 57.36% (±2.50%) for G to 61.88% (±1.91%) for G, without a statistically significant difference among groups ( > 0.05). The UTS values ranged from 32.85 (±6.08) MPa for G to 35.12 (±5.74) MPa for G ( > 0.05). MYTAB groups showed antibacterial activity against biofilm formation from 0.5 wt % ( < 0.05) and against planktonic bacteria from 1 wt % ( < 0.05). The higher the MYTAB concentration, the higher the cytotoxic effect, without differences between G e G ( > 0.05). In conclusion, the addition of 0.5 wt % of MYTAB did not alter the physical and chemical properties of the dental resin and provided antibacterial activity without cytotoxic effect.
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http://dx.doi.org/10.3390/jfb11010009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151596PMC
February 2020

Cerium Dioxide Particles to Tune Radiopacity of Dental Adhesives: Microstructural and Physico-Chemical Evaluation.

J Funct Biomater 2020 Feb 11;11(1). Epub 2020 Feb 11.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos 2492, Rio Branco, Porto Alegre, RS 90035-003, Brazil.

The insufficient radiopacity of dental adhesives applied under composite restorations makes the radiographic diagnosis of recurrent caries challenging. Consequently, the misdiagnosis may lead to unnecessary replacement of restorations. The aims of this study were to formulate experimental dental adhesives containing cerium dioxide (CeO) and investigate the effects of different loadings of CeO on their radiopacity and degree of conversion for the first time. CeO was characterized by X-ray diffraction analysis, Fourier transforms infrared spectroscopy, and laser diffraction for particle size analysis. Experimental dental adhesives were formulated with CeO as the inorganic filler with loadings ranging from 0.36 to 5.76 vol.%. The unfilled adhesive was used as a control. The studied adhesives were evaluated for dispersion of CeO in the polymerized samples degree of conversion, and radiopacity. CeO presented a monoclinic crystalline phase, peaks related to Ce-O bonding, and an average particle size of around 16 µm. CeO was dispersed in the adhesive, and the addition of these particles increased the adhesives' radiopacity ( < 0.05). There was a significant decrease in the degree of conversion with CeO loadings higher than 1.44 vol.%. However, all materials showed a similar degree of conversion in comparison to commercially available adhesives. CeO particles were investigated for the first time as a promising compound to improve the radiopacity of the dental adhesives.
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http://dx.doi.org/10.3390/jfb11010007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7151632PMC
February 2020

Nanoneedle-like zinc oxide as a filler particle for an experimental adhesive resin.

Indian J Dent Res 2019 Sep-Oct;30(5):777-782

Department of Conservative Dentistry, Dental Materials Laboratory - LAMAD, School of Dentistry, Federal University of Rio Grande do Sul, RS, Brazil.

Aim: The aim of this study was to develop an experimental adhesive resin with nanoneedle-like zinc oxide (N-ZnO), an inorganic filler, that could avoid particle agglomeration and lead to a homogeneous stress distribution within the material and characterize it.

Materials And Methods: N-ZnO particles obtained by a thermal evaporation technique were characterized regarding size and surface area and added at 0 (control), 1, 2, 5, and 10 wt%, to an experimental adhesive resin. The following experimental adhesive resins' properties were assessed: radiopacity, contact angle to conditioned enamel and dentin, color, degree of conversion, flexural strength, resistance to degradation, and cytotoxicity. Statistical analysis was performed using one-way ANOVA and Tukey's post hoc test and paired Student's t-test.

Results: Particles presented a mean particle size of 40 nm and a specific surface area of 16 m/g. N-ZnOshowed an increased radiopacity when compared to N-ZnO. Contact angles were significantly higher for N-ZnOat enamel and N-ZnO, N-ZnO, and N-ZnOat dentin. All groups showed color change when compared to N-ZnO. Higher the N-ZnO concentration, lower the degree of conversion. There were no significant differences between the groups for flexural strength and resistance to degradation. The addition of N-ZnO showed no difference in cytotoxicity when compared to positive control, N-ZnO, and all groups showed higher values than negative control.

Conclusions: N-ZnO possibly exceeded potential limitations due to particles' agglomeration and improved the transference and distribution of stress within the material. It could be effectively used as a filler for adhesive resins.
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http://dx.doi.org/10.4103/ijdr.IJDR_779_16DOI Listing
December 2019

Niobium containing bioactive glasses as remineralizing filler for adhesive resins.

Dent Mater 2020 02 30;36(2):221-228. Epub 2019 Nov 30.

Dental Materials Laboratory, School of Dentistry, Universidade Federal do Rio Grande do Sul, Brazil. Electronic address:

Objective: The aim of this study was to incorporate sol-gel-derived bioactive glass as filler into experimental adhesive resins and evaluate the influence of glass composition on the physicochemical and biological properties of the developed adhesives.

Materials And Methods: Sol-gel particles were produced with or without the addition of niobium (BAGNb or BAG, respectively). The produced particles were incorporated (2wt%) into experimental adhesive resins formulated with 66wt% bisphenol A-glycidyl methacrylate and 33wt% hydroxyethyl methacrylate. Ethyl dimethyl-4-aminobenzoate and camphorquinone were used as photoinitiator system. Two experimental groups were produced: A and A The adhesive without particles was used as control (A). The materials were tested for their degree of conversion, softening in solvent, and cytotoxicity. The mineral deposition was analyzed by Raman spectroscopy. Flexural strength and immediate and 1-year microtensile bond strength were evaluated.

Results: No statistical difference was found in degree of conversion. A showed reduced softening and higher mineral deposition than A and A after 28 days. A and A resulted in higher cell viability and lower flexural strength when compared to A. After 1-year, A and A presented statistically significant lower μTBS values.

Significance: Sol-gel-derived bioactive glasses promoted increased mineral deposition and cell viability for experimental adhesives with increased phosphate content and longitudinal μTBS values for the A group. These results suggest the potential of the studied particles to be applied as bioactive fillers for dental adhesives. Reductions in longitudinal μTBS and flexural strength, however, were observed for both glasses compositions and must be considered.
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http://dx.doi.org/10.1016/j.dental.2019.11.014DOI Listing
February 2020

Synthesis of sol-gel derived calcium silicate particles and development of a bioactive endodontic cement.

Dent Mater 2020 01 26;36(1):135-144. Epub 2019 Nov 26.

Dental Materials Laboratory, School of Dentistry, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, Brazil. Electronic address:

Objective: The aim of this study is to produce sol-gel derived calcium silicate particles (CS) and evaluate the influence of different concentration of calcium tungstate in the physical, chemical, mechanical and biological properties of developed cements.

Methods: Sol-gel route were used to synthesize calcium silicate particles that were characterized with x-ray difraction, Fourier transformed infrared spectroscopy, scanning electron microscopy, laser diffraction and nitrogen absorption. Cements were formulated with the addition of different concentrations of calcium tungstate (CaWO), resulting in four experimental groups according to the CS:CaWO ratio: CS (100:0), CS (90:10), CS (80:20), CS (70:30). The setting time, radiopacity, compressive strength, pH, calcium release, cell proliferation and cell differentiation were used to characterize the cements.

Results: CS particles were succesfully sinthesized. The addition of CaWO increased the radiopacity and did not influenced the setting time and the mechanical properties of cements. The pH of distilled water was increased for all groups and the CS and CS groups presented incresed calcium release. Reduced cell viability was found for CS while CS and CS presented higher ALP activity and % of mineralized nodules after 21 days.

Significance: Sol-gel derived CS particles were sucssfully developed with potential to applied for the production of bioactive ceramic cements. The addition of 10% of CaWO resulted in cements with adequate properties and bioactivity being an alternative for regenerative endodontic treatments.
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http://dx.doi.org/10.1016/j.dental.2019.11.004DOI Listing
January 2020

Mineral deposition promoted by resin-based sealants with different calcium phosphate additions.

Braz Oral Res 2019 25;33:e101. Epub 2019 Nov 25.

Universidade Federal do Rio Grande do Sul - UFRGS, School of Dentistry, Dental Materials Laboratory, Porto Alegre, RS, Brazil.

The aim of this study was to evaluate the influence of different calcium phosphates (CaPs) on the physical, biological, and remineralizing properties of experimental resin-based sealants (RBSs). Triethylene-glycol dimethacrylate (90wt%) and bisphenol A-glycidyl methacrylate (10wt%) were used to produce resin-based sealants. Hydroxyapatite (SHAp), α-tricalcium phosphate (Sα-TCP) and octacalcium phosphate (SOCP) were added to the sealants in a 10wt% concentration. One group without CaPs was used as the control group (SCG). The degree of conversion (DC) was assessed with Fourier-transformed infrared spectroscopy, whereas cytotoxicity was tested with the HaCaT keratinocyte cell line. The ultimate tensile strength (UTS) was used to assess the mechanical strength of the experimental RBSs. Sealed enamel was used for colorimetric assay. Mineral deposition was assessed with Raman spectroscopy after 7, 14, and 28 days of sample immersion in artificial saliva. Scanning electron microscopy was used to analyze the surface morphology after 28 days of immersion. The addition of 10wt% of fillers significantly reduced the DC of sealants. SOCP groups showed reduced cell viability. Higher UTS was found for Sα-TCP and SHAp. The color analysis showed that SGC and demineralized teeth presented higher mismatches with the sound tissue. Mineral deposition was observed for SHAp and Sα-TCP after 7 days, with increased phosphate content and mineral deposits for SHAp after 28 days. RBS with the addition of 10% HAp promoted increased mineralization in vitro after 28 days, and did not affect cell viability, DC, mechanical properties, or RBS color in the enamel.
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http://dx.doi.org/10.1590/1807-3107bor-2019.vol33.0101DOI Listing
December 2019

Influence of N-(2-hydroxyethyl)acrylamide addition in light- and dual-cured resin cements.

J Dent 2019 11 7;90:103208. Epub 2019 Oct 7.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492, Rio Branco, 90035-003, Porto Alegre, RS, Brazil. Electronic address:

Objective: To develop experimental light-cured (L) and dual-cured (D) resin cements containing N-(2-hydroxyethyl)acrylamide and evaluate the physicochemical and optical properties.

Methods: Experimental resin cements were formulated using bisphenol A-glycidyl dimethacrylate (70%) and 2-hydroxyethyl methacrylate (30%), in the control groups, and, bisphenol A-glycidyl dimethacrylate (70%) and N-(2-hydroxyethyl)acrylamide (30%). Polymerization kinetics were evaluated by differential scanning calorimetry (n = 3), softening in solvent (ΔKHN) evaluated by the difference of Knoop microhardness before (KHN) and after (KHN) ethanol solution immersion (n = 5), radiopacity in mmAl (n = 5), film thickness (n = 3) and color stability were evaluated. Mechanical properties as ultimate tensile strength (UTS) and micro-shear bond strength (μSBS) were analyzed immediately and after 6 months. Results were analyzed using ANOVA, Tukey's test and Student's t-test (α = 0.050).

Results: The L group had no statistical difference from the control group regarding polymerization kinetics, KHN, ΔKHN and color stability (p > 0.050). In dual-cured cements, the acrylamide groups presented a lower degree of conversion and higher ΔKHN than the D group, which obtained a higher rate of polymerization (p < 0.050). There was no statistical difference in radiopacity and film thickness (p > 0.050). Dual-cured cements with N-(2-hydroxyethyl)acrylamide showed higher color change than methacrylates. Immediate mechanical properties were lower for acrylamide groups (p < 0.050), with higher hydrolytic stability.

Conclusions: The addition of N-(2-hydroxyethyl)acrylamide negatively affected the properties of the dual-cured resin cements. LHEAA1 did not differ in physicochemical and optical properties from the control, with higher hydrolytic stability.

Clinical Significance: The results of the study indicate that acrylamides increased mechanical properties over time independently of the curing system mode, with more hydrolytic stability. The clinical performance of experimental resin cements should be evaluated.
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http://dx.doi.org/10.1016/j.jdent.2019.103208DOI Listing
November 2019

Bone healing with niobium-containing bioactive glass composition in rat femur model: A micro-CT study.

Dent Mater 2019 10 9;35(10):1490-1497. Epub 2019 Aug 9.

Dental Materials Laboratory, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. Electronic address:

Objective: The aim of this study is to investigate bone healing ability of niobium-containing bioactive glasses in rat femur model with quantitative and qualitative measurements through x-ray computed microtomography.

Methods: Niobium-containing bioactive powders and scaffolds were produced by sol-gel route (BAGNb). Glasses without niobium addition were produced as well (BAG). Five groups were used: BAGNb powders, BAG powders, BAGNb scaffolds, BAG scaffolds and, as a control group, autogenous bone was used. Materials were implanted in the femur of male rats (Wistar Lineage n=10) and the healing was observed after 15, 30 and 60 days. After the post-operative times, samples were scanned by X-ray microcomputed tomography where morphometric measurements and the mineral density were assessed in image software.

Results: No postoperative complications were observed after surgery. BAGNb glasses presented higher mineral deposition, which was observed in the relative volume of bone and the mineral density when compared BAG groups. In these parameters, no statistical difference was found between BAGNb and autogenous bone. The BAGNb powders presented a higher amount of mineralized tissue when compared to BAGNb scaffolds. The analysis of trabecular structure showed lower trabecular formation in synthetic materials when compared to autogenous bone.

Significance: Niobium-containing bioactive glasses promoted bone formation comparable to that of the autogenous bone without compromising the quality of the formed bone.
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http://dx.doi.org/10.1016/j.dental.2019.07.012DOI Listing
October 2019

CAD/CAM or conventional ceramic materials restorations longevity: a systematic review and meta-analysis.

J Prosthodont Res 2019 Oct 11;63(4):389-395. Epub 2019 Jul 11.

Department of Conservative Dentistry, Dental Materials Laboratory, School of Dentistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil. Electronic address:

Purpose: This systematic review and meta-analysis aimed to evaluate the difference in longevity of tooth-supported ceramic prostheses designed by conventional and computer-aided design/computer-aided manufacturing (CAD/CAM) techniques.

Study Selection: Two reviewers searched the Web of Science, PubMed, SCOPUS and LILACS databases between 1966 and October 2017. Clinical studies that compared the survival rate of CAD/CAM against conventional restorations were included.

Results: Eleven randomized controlled trials and three prospective studies were included, n=14. Three types of tooth-supported restorations were searched in the included studies: single crown, multiple-unit and partial ceramic crown. The follow-up of patients in the studies ranged from 24 to 84 months. A total of 1209 restorations had been placed in 957 patients in the included trials, and failures were analyzed by type and material restoration. From a total of 72 restoration failures, the CAD/CAM system resulted in a 1.84 (IC95%: 1.28-2.63) higher risk than conventional manufacturing of ceramic restoration. Nevertheless, when drop-outs were included as a failure risk, the CAD/CAM system resulted in a risk of 1.32 (IC95%: 1.10-1.58). Multilevel analysis of tooth-supported ceramic restorations, considering drop-outs as successes, resulted in rates of 1.48 and 2.62 failures per 100 restoration-years for the controls and CAD/CAM groups, respectively. Considering drop-outs as failures, we found rates of 4.23 and 5.88 failures per 100 restoration-years for the controls and CAD/CAM groups, respectively.

Conclusions: The meta-analysis results suggest that the longevity of a tooth-supported ceramic prostheses made by CAD/CAM manufacturing is lower than that of crowns mad by the conventional technique.
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http://dx.doi.org/10.1016/j.jpor.2018.11.006DOI Listing
October 2019

Quaternary ammonium compound as antimicrobial agent in resin-based sealants.

Clin Oral Investig 2020 Feb 1;24(2):777-784. Epub 2019 Jun 1.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2492, Rio Branco, Porto Alegre, RS, 90035-003, Brazil.

Objectives: The aim of this study was to evaluate the influence of [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC) in the physico-chemical properties, antibacterial activity and cytotoxicity of an experimental resin-based sealant.

Materials And Methods: An experimental resin-based sealant was formulated with dimethacrylates and a photoinitiator system. METAC was added at 2.5 wt.% (G) and 5 wt.% (G) into the experimental resin-based sealant, and one group remained without METAC as control (G). The resin-based sealants were analysed for polymerization behaviour and degree of conversion (DC), Knoop hardness (KHN) and softening in solvent (ΔKHN), ultimate tensile strength (UTS), contact angle, surface free energy (SFE), immediate and long-term micro-shear bond strength (μ-SBS) and antibacterial activity and cytotoxicity against human keratinocytes.

Results: The experimental resin-based sealants presented different polymerization behaviours without significant differences in the DC (p > 0.05). There was no significant difference for initial KHN (p > 0.05). The ΔKHN ranged from 51.62 (±3.70)% to 62.40 (±4.14)%, with higher values for G (p < 0.05). G and G had decreased μ-SBS between immediate and long-term tests (p < 0.05) without significant differences among groups in the immediate and long-term analyses (p > 0.05). There were no significant differences for UTS, contact angle and SFE among groups (p > 0.05). G and G presented immediate and long-term antibacterial activity (p < 0.05) without cytotoxicity compared to G (p > 0.05).

Conclusion: The addition of METAC provided antibacterial activity to the experimental resin-based sealant.

Clinical Relevance: METAC is an effective quaternary ammonium compound as an antibacterial agent for resin-based sealants without cytotoxic effects against human keratinocytes.
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http://dx.doi.org/10.1007/s00784-019-02971-4DOI Listing
February 2020

Ionic liquid as antibacterial agent for an experimental orthodontic adhesive.

Dent Mater 2019 08 23;35(8):1155-1165. Epub 2019 May 23.

Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Ramiro Barcelos Street, 2492, Rio Branco, Porto Alegre, RS, 90035-003, Brazil. Electronic address:

Objective: The aim of this study was to formulate and evaluate experimental orthodontic adhesives with different concentrations of 1-n-butyl-3-methylimidazoilium bis(trifluoromethanesulfonyl)imide (BMIM.NTf).

Methods: The experimental orthodontic adhesives were formulated with methacrylate monomers, photoinitiators and silica colloidal. The ionic liquid BMIM.NTf was synthesized and characterized. BMIM.NTf was added at 5 (G), 10 (G) and 15 (G) wt.%. One group contained no BMIM.NTf to function as control (G). The adhesives were evaluated for polymerization kinetics, degree of conversion (DC), Knoop hardness and softening in solvent, ultimate tensile strength (UTS), shear bond strength (SBS), thermogravimetric analysis (TGA), antibacterial activity and cytotoxicity.

Results: BMI.NTf showed the characteristic chemical peaks. The polymerization kinetics were different among the groups. G and G showed higher DC (p < 0.05). G and G had no differences for softening in solvent (p > 0.05). There were no differences for UTS (p > 0.05) and SBS (p > 0.05). TGA showed one different peak for G. All groups with BMIM.NTf showed antibacterial activity compared to G (p < 0.05) without cytotoxicity (p > 0.05).

Significance: To reduce biofilm formation around brackets and to prevent demineralization at susceptible sites, materials have been developed with antibacterial properties. In this study, a new experimental orthodontic adhesive was formulated with an imidazolium ionic liquid (BMIM.NTf) as antibacterial agent. The incorporation of 5 wt.% of ionic liquid decreased biofilm formation without affecting the physico-chemical properties and cytotoxicity of an experimental orthodontic resin.
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http://dx.doi.org/10.1016/j.dental.2019.05.010DOI Listing
August 2019

Boron Nitride Nanotubes as Filler for Resin-Based Dental Sealants.

Sci Rep 2019 05 22;9(1):7710. Epub 2019 May 22.

Dental Materials Laboratory, School of Dentistry. Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.

The aim of this study was to evaluate the influence of boron-nitride nanotubes (BNNTs) on the properties of resin-based light-curing dental sealants (RBSs) when incorporated at different concentration. RBSs were formulated using methacrylate monomers (90 wt.% TEGDMA, 10 wt.% Bis-GMA). BNNTs were added to the resin blend at 0.1 wt.% and 0.2 wt.%. A Control group without filler was also designed. Degree of conversion, ultimate tensile strength, contact angle, surface free energy, surface roughness and color of the RBSs were evaluated for the tested materials. Their cytotoxicity and mineral deposition ability (Bioactivity) were also assessed. A suitable degree of conversion, no effect in mechanical properties and no cytotoxic effect was observed for the experimental materials. Moreover, the surface free energy and the surface roughness decreased with the addition of BNNTs. While the color analysis showed no difference between specimens containing BNNTs and the control group. Mineral deposition occurred in all specimens containing BNNTs after 7d. In conclusion, the incorporation of BNNTs may provide bioactivity to resin-based dental sealants and reduce their surface free energy.
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http://dx.doi.org/10.1038/s41598-019-44246-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531453PMC
May 2019

Calcium phosphates as fillers for methacrylate-based sealer.

Clin Oral Investig 2019 Dec 13;23(12):4417-4423. Epub 2019 Apr 13.

Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.

Objectives: The aim of this study was to evaluate the mineral deposition, push-out bond strength, radiopacity, the degree of conversion, film thickness, flow, calcium ion release, and pH of experimental endodontic sealers containing hydroxyapatite (HAp), aflfa-ticalcium phosphate (α-TCP), or octacalcium phosphate (OCP) particles.

Materials And Methods: Fifty single straight root human premolars were instrumented and divided into five groups (n = 10). Experimental endodontic sealers were formulated by 70 wt% urethane dimethacrylate (UDMA), 15 wt% of glycerol-1,3-dimethacrylate (GDMA), 15 wt% of ethoxylated bisphenol A glycol dimethacrylate (BISEMA), camphorquinone (CQ), N,N-dihydroxyethyl-para-toluidine (DHEPT), and benzoyl-peroxide. 10 wt% of each HAp, α-TCP, or OCP were added to the resin and its properties were assessed.

Results: After 7 days, the degree of conversion ranged from 44.69% (G) to 50.74% (G) and no statistical difference were observed (p < 0.05). G showed the highest push-out bond strength 4.91 (± 2.38) MPa at 28 days of analysis (p < 0.05). Film thickness and pH were not statistically different (p > 0.05). Statically lower values of flow were found for G, G, and G (p < 0.05). Calcium deposition values were higher for G at 28 days.

Conclusions: Bond strength, degree of conversion, and film thickness of endodontic sealers with phosphates showed similar results compared with AHplus, but displayed higher amounts of Ca release.

Clinical Relevance: Phosphate fillers improve the performance of endodontic sealers after 28 days of simulated body fluid.
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http://dx.doi.org/10.1007/s00784-019-02898-wDOI Listing
December 2019

Antibacterial, chemical and physical properties of sealants with polyhexamethylene guanidine hydrochloride.

Braz Oral Res 2019 Mar 18;33:e019. Epub 2019 Mar 18.

Universidade Federal do Rio Grande do Sul - UFRGS, School of Dentistry, Dental Materials Laboratory, Porto Alegre, RS, Brazil.

The aim of this study was to evaluate the influence of polyhexamethylene guanidine hydrochloride (PHMGH) in the physico-chemical properties and antibacterial activity of an experimental resin sealant. An experimental resin sealant was formulated with 60 wt.% of bisphenol A glycol dimethacrylate and 40 wt.% of triethylene glycol dimethacrylate with a photoinitiator/co-initiator system. PHMGH was added at 0.5 (G0.5%), 1 (G1%), and 2 (G2%) wt.% and one group remained without PHMGH, used as control (GCTRL). The resin sealants were analyzed for degree of conversion (DC), Knoop hardness (KHN), and softening in solvent (ΔKHN), ultimate tensile strength (UTS), contact angle (θ) with water or α-bromonaphthalene, surface free energy (SFE), and antibacterial activity against Streptococcus mutans for biofilm formation and planktonic bacteria. There was no significant difference for DC (p > 0.05). The initial Knoop hardness ranged from 17.30 (±0.50) to 19.50 (± 0.45), with lower value for GCTRL (p < 0.05). All groups presented lower KHN after immersion in solvent (p < 0.05). The ΔKHN ranged from 47.22 (± 4.30) to 57.22 (± 5.42)%, without significant difference (p > 0.05). The UTS ranged from 54.72 (± 11.05) MPa to 60.46 (± 6.50) MPa, with lower value for G2% (p < 0.05). PHMGH groups presented no significant difference compared to GCTRL in θ (p > 0.05). G2% showed no difference in SFE compared to GCTRL (p > 0.05). The groups with PHMGH presented antibacterial activity against biofilm and planktonic bacteria, with higher antibacterial activity for higher PHMGH incorporation (p < 0.05). PHMGH provided antibacterial activity for all resin sealant groups and the addition up to 1 wt.% showed reliable physico-chemical properties, maintaining the caries-protective effect of the resin sealant over time.
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http://dx.doi.org/10.1590/1807-3107bor-2019.vol33.0019DOI Listing
March 2019

Evaluation of an antibacterial orthodontic adhesive incorporated with niobium-based bioglass: an in situ study.

Braz Oral Res 2019 Mar 18;33:e010. Epub 2019 Mar 18.

Universidade Federal do Rio Grande do Sul - UFRGS, School of Dentistry, Dental Materials Laboratory, Porto Alegre, Rio Grande do Sul, Brazil.

This in situ study aimed to evaluate the antibacterial and anti-demineralization effects of an experimental orthodontic adhesive containing triazine and niobium phosphate bioglass (TAT) around brackets bonded to enamel surfaces. Sixteen volunteers were selected to use intra-oral devices with six metallic brackets bonded to enamel blocks. The experimental orthodontic adhesives were composed by 75% BisGMA and 25% TEGDMA containing 0% TAT and 20% TAT. Transbond XT adhesive (TXT) was used as a control group. Ten volunteers, mean age of 29 years, were included in the study. The six blocks of each volunteer were detached from the appliance after 7 and 14 days to evaluate mineral loss and bacterial growth including total bacteria, total Streptococci, Streptococci mutans, and Lactobacilli. Statistical analysis was performed using GLM model - univariate analysis of variance for microhardness and 2-way ANOVA for bacterial growth (p<0.05). The 20% TAT adhesive caused no difference between distances from bracket and the sound zone at 10-µm deep after 7 and 14 days. After 14 days, higher mineral loss was shown around brackets at 10- to 30-µm deep for TXT and 0% TAT adhesives compared to 20% TAT. S. mutans growth was inhibited by 20% TAT adhesive at 14 days. Adhesive with 20% TAT showed lower S. mutans and total Streptococci growth than 0% TAT and TXT adhesives. The findings of this study show that the adhesive incorporated by triazine and niobium phosphate bioglass had an anti-demineralization effect while inhibiting S. mutans and total Streptococci growth. The use of this product may inhibit mineral loss of enamel, preventing the formation of white spot lesions.
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http://dx.doi.org/10.1590/1807-3107bor-2019.vol33.0010DOI Listing
March 2019

Halloysite nanotubes loaded with alkyl trimethyl ammonium bromide as antibacterial agent for root canal sealers.

Dent Mater 2019 05 1;35(5):789-796. Epub 2019 Mar 1.

Departamento de Odontología, Facultad de Ciencias de la Salud, Universidad CEU-Cardenal Herrera, C/Del Pozos/n, Alfara del Patriarca, 46115 Valencia, Spain. Electronic address:

Objective: This study aimed at evaluating the effects of experimental endodontic sealers containing halloysite nanotubes (HNT) doped with alkyl trimethyl ammonium bromide (ATAB).

Methods: An experimental dual-cure resin sealer was formulated and used as control material. This resin was also filled with ATAB and HNT at different ratios (GATAB:HNT 1:1; 1:2; 2:1) generate three experimental resin sealers. The ATAB:HNT filler was characterized through transmission electron microscopy (TEM). While, the experimental and control sealers were evaluated for degree of conversion, softening ration, radiopacity, flow, film thickness, antibacterial activity for biofilm and planktonic bacteria and cytotoxicity in human pulpal cells.

Results: GATAB:HNT significantly increased the immediate DC (p < 0.05), although no difference was encountered between the groups after 24 h (p > 0.05). All the experimental cements (ATAB/HNT) showed relatively low initial Knoop hardness (p < 0.05), but with no significant reduction (p > 0.05) after storage in ethanol (softening ratio). The radiopacity of all groups achieved at least 3 mm of aluminum. All groups showed more than 17 mm of flow, with a film thickness lower than 50 μm (ISO 6876:2012). All the experimental ATAB:HNT cements showed antibacterial activity against E. faecalis; the higher the ATAB ratio, the greater the antibacterial activity (p < 0.05). Cell viability was higher than 70% with no significant difference between the groups (p > 0.05).

Significance: The incorporation of ATAB/HNT into the experimental resin sealers induced antibacterial activity against biofilm and planktonic E. faecalis without affecting the pulp cell viability or the chemo-mechanical properties.
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http://dx.doi.org/10.1016/j.dental.2019.02.018DOI Listing
May 2019
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