Publications by authors named "Evandro Piva"

117 Publications

In vitro Streptococcus mutans adhesion and biofilm formation on different esthetic orthodontic archwires.

Angle Orthod 2021 Jun 10. Epub 2021 Jun 10.

Objectives: To evaluate the ability of different esthetic archwires to retain oral biofilms in vitro.

Materials And Methods: Seven different brands of coated orthodontic archwires were tested: two epoxy coated, two polytetrafluoroethylene coated, two rhodium coated, and one silver plus polymer coated. Conventional uncoated metallic archwires were used as controls. Streptococus mutans adherence to archwires was quantified by colony count following 24 hours of biolfilm growth, and total wire-associated biofilm was measured using a crystal violet staining assay. For both tests, two conditions were used: 0% sucrose and 3% sucrose. For statistical analysis, P < .05 was considered as statistically significant.

Results: For S. mutans colony forming units per biofilm, there were no statistically significant differences among the various archwires (P = .795 for 0% sucrose; P = .905 for 3% sucrose). Regarding total biofilm formed on archwires in the 3% sucrose condition, there were statistically significant differences in crystal violet staining only for the comparison between Niti Micro Dental White and Copper Ni-Ti wires (P < .05).

Conclusions: The clinical use of esthetic-coated orthodontic wires may be considered to have similar risks as uncoated archwires for biofilm retention.
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http://dx.doi.org/10.2319/121220-998.1DOI Listing
June 2021

Retentive efficacy, antimicrobial and cytotoxicity comparisons between different types of commercial and experimental denture adhesives with antifungal action.

Dent Mater J 2021 Apr 22. Epub 2021 Apr 22.

Department of Restorative Dentistry, Faculty of Dentistry, Federal University of Pelotas.

The effect of the addition of nystatin and an alternative antifungal derived from pyrazoles in different commercial denture adhesives on their retentive efficacy, cytotoxicity and antimicrobial activity against Candida albicans was evaluated. Commercial denture adhesives were prepared with the inclusion of nystatin and 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamide (pyrazole) in three concentrations: 23.78 %w/w, 3.02 %w/w, and 0.31 %w/w (0.015 g, 0.0015 g, and 0.00015 g, respectively). The retentive efficacy was tested observing the influence of the medium, type of commercial denture type and the test condition (dipping). The antifungal action through disk diffusion and direct contact tests at 1, 4, 8 and 12 h and cytotoxic activity was evaluated in mouse fibroblasts (NIH/3T3) by the MTT reduction colorimetric assay. The addition of pyrazole and nystatin in commercial denture adhesives did not affect retentive efficacy rates and enhanced antifungal actions against Candida albicans. Results show a possibility of using denture adhesives as a delivery system for commercial antifungals (Nystatin) or pyrazole, with the second concentration (1,560 µg-3.02 %w/w) as the most efficient.
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http://dx.doi.org/10.4012/dmj.2020-262DOI Listing
April 2021

Bond strength of self-adhesive flowable composite resins to dental tissues: A systematic review and meta-analysis of in vitro studies.

J Prosthet Dent 2021 Apr 7. Epub 2021 Apr 7.

Associate Professor, Academic Are of Dentistry, Autonomous University of the State of Hidalgo, San Agustín Tlaxiaca, Hidalgo, Mexico. Electronic address:

Statement Of Problem: Although the clinical use of self-adhesive flowable composite resins is convenient, the decision to use flowable or conventional composite resin remains controversial.

Purpose: The purpose of this systematic review and meta-analysis was to assess the in vitro bond strength of self-adhesive flowable composite resins to enamel or dentin compared with conventional composite resins using etch-and-rinse or self-etch adhesive systems.

Material And Methods: Two independent reviewers performed searches in the PubMed (MEDLINE), Cochrane Wiley, Web of Science, Scopus, and Google Scholar databases for studies reporting on the bond strength of self-adhesive flowable and conventional composite resins to enamel and dentin published from January 2010 up to September 2020. A meta-analysis software program was used for the meta-analysis. Comparisons were conducted using standardized mean differences considering the random-effects model (α=.05).

Results: Twenty-two studies were considered for the meta-analysis. Immediate and long-term bond strength to enamel was improved when a conventional composite resin was used in combination with an adhesive system (P<.001). Bond strength to dentin was improved by using an adhesive system in combination with a conventional composite resin (P<.001).

Conclusions: The bond strength of self-adhesive flowable composite resins is lower than that of conventional composite resins, indicating limited ability to bond to enamel and dentin.
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http://dx.doi.org/10.1016/j.prosdent.2021.02.020DOI Listing
April 2021

Biological and mechanical characterization of commercial and experimental periodontal surgical dressings.

Braz Oral Res 2021 3;35:e045. Epub 2021 Mar 3.

Aarhus University , Department of Dentistry and Oral Health , Section of Periodontology, Aarhus , Denmark .

The objective of this study was to evaluate the biocompatibility and mechanical properties of two commercially available and one experimental periodontal dressing materials. The cytotoxicity of Periobond ® , Barricaid ® and one experimental periodontal dressing based on Exothane ® 8 monomer was tested on 3T3/NIH mouse fibroblast. Genotoxicity was assessed by micronuclei formation, and cell alterations were analyzed using light microscopy. Both biological assays were performed using the eluate obtained from specimens after 24, 72, or 168 hours of incubation. Mechanical characterization was assessed through the ultimate tensile strength and the water sorption and solubility tests. The significance level of α = 0.05 was used for all statistical analyses. All the materials promoted a cell viability lower than 60% in all evaluated times. In general, the cell viability was significantly reduced after 72 and 168h of specimens' incubation. Considering the factor material, there were not statistical differences in the cell viability (p = 0.156). The genotoxicity was not statistically significant among the groups in the different periods of time (p > 0.05). Differences in the ultimate tensile strength values were not statistically significant different among the groups (p = 0.125). Periobond ® showed the higher water sorption values (p < 0.001). Regarding solubility, there were no statistical differences between the groups (p = 0.098). All the periodontal dressing materials evaluated in this study exerted a cytotoxic effect against mouse fibroblasts, and their toxicity became more evident over time. Among the materials evaluated, the experimental light-cure type has shown overall similar properties to the commercial references.
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http://dx.doi.org/10.1590/1807-3107bor-2021.vol35.0045DOI Listing
March 2021

In vitro efficacy of commercial and experimental proteolytic enzyme-based whitening dentifrices on enamel whitening and superficial roughness.

J Esthet Restor Dent 2020 Dec 5. Epub 2020 Dec 5.

Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.

Objective: To evaluate the whiteness index (W ) and surface roughness (Ra) of bovine enamel after simulated tooth brushing with different commercial and experimental whitening dentifrices.

Materials And Methods: Cylindrical enamel bovine specimens were acid etched, stained, and divided in nine groups (n = 8): Colgate® Optic White®, Crest® Baking Soda and Peroxide, Arm and Hammer® Advanced White™ Extreme Whitening, Rembrandt® Deeply White® + Peroxide, Close up® White Attraction Natural Glow, Hinode Prowhite, and experimental dentifrice containing papain (PP), bromelain (PB), or papain and bromelain (PPB). Ra and W were obtained initially and after 600, 1200, and 3,600 cycles of simulated tooth brushing. Data were analyzed using two-way analysis of variance test (α = 0.05).

Results: Ra was significantly influenced by both dentifrice (p = 0.043) and period of tooth-brushing simulation (p < 0.001). Except for PP and PPB, all groups showed a statistically significant increase in Ra after simulated tooth brushing. After staining and brushing, none of the materials tested increased the initial W .

Conclusions: The effect of commercial whitening dentifrices may be related to their high abrasiveness. Experimental formulations tested provided a similar effect without undesired wear of enamel. Whitening dentifrices only act through an abrasive effect rather than bleaching the tooth structures. When used, special care must be taken for avoid undesired wear of enamel. Experimental dentifrices provided similar removal of extrinsic stains without undesired abrasiveness; however, this effect may be due to the use of less aggressive abrasives in their formulations.
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http://dx.doi.org/10.1111/jerd.12690DOI Listing
December 2020

Development of an antibacterial and anti-metalloproteinase dental adhesive for long-lasting resin composite restorations.

J Mater Chem B 2020 12 10;8(47):10797-10811. Epub 2020 Nov 10.

Department of Conservative Dentistry, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS 90035-003, Brazil.

Despite all the advances in adhesive dentistry, dental bonds are still fragile due to degradation events that start during application of adhesive agents and the inherent hydrolysis of resin-dentin bonds. Here, we combined two outstanding processing methods (electrospinning and cryomilling) to obtain bioactive (antimicrobial and anti-metalloproteinase) fiber-based fillers containing a potent matrix metalloproteinase (MMP) inhibitor (doxycycline, DOX). Poly(ε)caprolactone solutions containing different DOX amounts (0, 5, 25, and 50 wt%) were processed via electrospinning, resulting in non-toxic submicron fibers with antimicrobial activity against Streptococcus mutans and Lactobacillus. The fibers were embedded in a resin blend, light-cured, and cryomilled for the preparation of fiber-containing fillers, which were investigated with antibacterial and in situ gelatin zymography analyzes. The fillers containing 0, 25, and 50 wt% DOX-releasing fibers were added to aliquots of a two-step, etch-and-rinse dental adhesive system. Mechanical strength, hardness, degree of conversion (DC), water sorption and solubility, bond strength to dentin, and nanoleakage analyses were performed to characterize the physico-mechanical, biological, and bonding properties of the modified adhesives. Statistical analyses (ANOVA; Kruskal-Wallis) were used when appropriate to analyze the data (α = 0.05). DOX-releasing fibers were successfully obtained, showing proper morphological architecture, cytocompatibility, drug release ability, slow degradation profile, and antibacterial activity. Reduced metalloproteinases (MMP-2 and MMP-9) activity was observed only for the DOX-containing fillers, which have also demonstrated antibacterial properties against tested bacteria. Adhesive resins modified with DOX-containing fillers demonstrated greater DC and similar mechanical properties as compared to the fiber-free adhesive (unfilled control). Concerning bonding performance to dentin, the experimental adhesives showed similar immediate bond strengths to the control. After 12 months of water storage, the fiber-modified adhesives (except the group consisting of 50 wt% DOX-loaded fillers) demonstrated stable bonds to dentin. Nanoleakage was similar among all groups investigated. DOX-releasing fibers showed promising application in developing novel dentin adhesives with potential therapeutic properties and MMP inhibition ability; antibacterial activity against relevant oral pathogens, without jeopardizing the physico-mechanical characteristics; and bonding performance of the adhesive.
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http://dx.doi.org/10.1039/d0tb02058cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7744429PMC
December 2020

Novel in-office peroxide-free tooth-whitening gels: bleaching effectiveness, enamel surface alterations, and cell viability.

Sci Rep 2020 06 22;10(1):10016. Epub 2020 Jun 22.

Graduate Program in Dentistry, Pelotas Dental School, UFPel-Federal University of Pelotas, Gonçalves Chaves 457, Pelotas, 96015-560, Rio Grande do Sul, Brazil.

To evaluate the bleaching ability, the effect on enamel surface and cytotoxicity of novel tooth-whitening formulations containing papain, ficin, or bromelain. Forty bovine dental discs (6 cm ×4 cm) were pigmentated and randomly allocated into the following groups (n = 10): Group 1, 20 wt% carbamide peroxide (control); group 2, 1% papain-based whitening; group 3, 1% ficin-based whitening; and group 4, 1% bromelain-based whitening. The whitening gels were prepared and applied on the enamel three times per day once a week, for 4 weeks. Color measurement was obtained by CIEDE2000. Enamel Knoop microhardness and roughness were evaluated. The WST-1 assay was used to evaluate the cell viability of mouse fibroblast cells (L929). Data were statistically analyzed by one-way analysis of variance (ANOVA) and Student Newman Keuls's post hoc test at α = 0.05 significance level. Bromelain, ficin-based, and carbamide peroxide bleaching gels showed a similar color change (p < 0.001). Higher enamel hardness decrease and higher enamel roughness were caused by the carbamide peroxide (p < 0.05). The experimental whitening gels did not affect cell viability. Tooth bleaching gels containing bromelain, papain, or ficin have substantial clinical potential to be used in the development of peroxide-free tooth whitening gels.
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http://dx.doi.org/10.1038/s41598-020-66733-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7308351PMC
June 2020

Anti-biofilm activity of a novel pit and fissure self-adhesive sealant modified with metallic monomers.

Biofouling 2020 03 24;36(3):245-255. Epub 2020 Apr 24.

Biofilm Research Labs, Levy Center for Oral Health, Department of Orthodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA.

Dental plaque is a biofilm composed of a complex oral microbial community. The accumulation of plaque in the pit and fissures of dental elements often leads to the development of tooth decay (dental caries). Here, potent anti-biofilm materials were developed by incorporating zinc methacrylates or di-n-butyl-dimethacrylate-tin into the light-curable sealant and their physical, mechanical, and biological properties were evaluated. The data revealed that 5% di-n-butyl-dimethacrylate-tin (SnM 5%) incorporated sealant showed strong anti-biofilm efficacy against various single-species ( or or ) and - cross-kingdom dual-species biofilms without either impairing the mechanical properties of the sealant or causing cytotoxicities against mouse fibroblasts. The findings indicate that the incorporation of SnM 5% in the experimental pit and fissure self-adhesive sealant may have the potential to be part of current chemotherapeutic strategies to prevent the formation of cariogenic oral biofilms that cause dental caries.
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http://dx.doi.org/10.1080/08927014.2020.1748603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7270982PMC
March 2020

Injectable MMP-Responsive Nanotube-Modified Gelatin Hydrogel for Dental Infection Ablation.

ACS Appl Mater Interfaces 2020 Apr 25;12(14):16006-16017. Epub 2020 Mar 25.

Department of Cariology, Restorative Sciences and Endodontics, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109, United States.

A photocrosslinkable gelatin methacryloyl (GelMA) hydrogel has been widely examined in regenerative engineering because of its good cell-tissue affinity and degradability in the presence of matrix metalloproteinases. A halloysite aluminosilicate nanotube (HNT) is a known reservoir for the loading and sustained delivery of therapeutics. Here, we formulate injectable chlorhexidine (CHX)-loaded nanotube-modified GelMA hydrogel that is cytocompatible and biodegradable and provides sustained release of CHX for infection ablation while displaying good biocompatibility. The effects of HNTs and CHX on hydrogel degradability and mechanical properties, as well as on the kinetics of CHX release, and on the antimicrobial efficacy against oral pathogens were systematically assessed. Cytocompatibility in stem cells from human exfoliated deciduous teeth and inflammatory response using a subcutaneous rat model were determined. Our hydrogel system, that is, (CHX)-loaded nanotube-modified GelMA showed minimum localized inflammatory responses, supporting its ability for drug delivery applications. Moreover, we showed that the incorporation of CHX-loaded nanotubes reduces the mechanical properties, increases the swelling ratio, and diminishes the degradation rate of the hydrogels. Importantly, the presence of CHX-loaded nanotubes inhibits bacterial growth with minimal cell toxicity. Our findings provide a new strategy to modify GelMA hydrogel with chlorhexidine-loaded nanotubes for clinical use as an injectable drug delivery strategy for dental infection ablation.
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http://dx.doi.org/10.1021/acsami.9b22964DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7370252PMC
April 2020

Cytotoxicity of Chelating Agents Used In Endodontics and Their Influence on MMPs of Cell Membranes.

Braz Dent J 2020 Jan-Feb;31(1):32-36

Department of Oral Sciences, UNIC - Universidade de Cuabá, Cuiaba, MT, Brazil.

This study evaluated the cytotoxic effect and the ability to inhibit matrix metalloproteinases (MMP-2 and MMP-9) of 0.2% chitosan (CH) and 1% acetic acid (AA) compared with 17% ethylenediaminetetraacetic acid (EDTA). Cell viability assay was performed according to ISO 10993-5 with mouse fibroblasts (L929). The culture was exposed to 0.2% CH, 1% AA, and 17% EDTA. The chelating agents were evaluated immediately after contact with the cells and after 6 h, 12 h, and 24 h of incubation. Cell viability was analyzed using the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Inhibition of the gelatinolytic activity of MMP-2 and MMP-9 was evaluated by gelatin zymography. Different concentrations of CH were evaluated: 50 mM, 5 mM, 0.5 mM, and 0.05 mM. EDTA (0.5 mM) was used as a positive control. The results demonstrated that CH and AA had an initial cytotoxic effect, which decreased after 6 h, 12 h, and 24 h, being statistically similar to EDTA (P > 0.05). Additionally, CH at concentrations of 50 mM, 5 mM, and 0.5 mM had an inhibitory effect on MMP-2 and MMP-9, similar to that of the control with EDTA. The chelating agents had no cytotoxic effects after 24 h. MMP-2 and MMP-9 were inhibited by the experimental solutions.
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http://dx.doi.org/10.1590/0103-6440202002812DOI Listing
March 2020

Bonding Strength of Universal Adhesives to Indirect Substrates: A Meta-Analysis of in Vitro Studies.

J Prosthodont 2020 Apr 5;29(4):298-308. Epub 2020 Mar 5.

Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas, Goncalves Cháves 457, Pelotas, RS, 96015-560, Brazil.

Purpose: To evaluate the in vitro bond strength of universal adhesive systems to indirect substrates.

Material And Methods: Two reviewers performed a literature search up to March 2018 in seven databases: PubMed, Web of Science, SciELO, Scopus, LILACS, IBECS, and BBO. The review included studies that compared the bond strength of universal adhesives and well-established material-specific primers to indirect substrates: lithium disilicate ceramic, yttrium-stabilized zirconium dioxide ceramic, leucite-reinforced ceramic, feldspathic porcelain, polymer infiltrated ceramic material, resin composite or metal alloys. Analyses were carried out using RevMan 5.3.5. A global comparison was performed with the standardized mean difference using a random-effects models at a significance level of p < 0.05.

Results: A total of 45 studies were included in the qualitative analysis, and the meta-analysis was performed with 42 studies. Bond strength to glass-based ceramics and alloys was improved with the use of a specific-primer as separate step before the bonding procedures (lithium disilicate, p < 0.001; alloys, p < 0.001). The bond strength to zirconium substrates was improved with the use of universal adhesives (p < 0.001). For bond strength to composite resin as indirect substrate, universal adhesives performed in a manner similar to that of the material-specific primer (p = 0.11).

Conclusions: The clinical procedure of luting zirconia and resin composite restorations could be simplified by using single-bottle universal adhesives. However, the ability of universal adhesives to achieve an adequate and durable bond to glass-based ceramics and alloys appears to be limited.
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http://dx.doi.org/10.1111/jopr.13147DOI Listing
April 2020

Efficacy of natural, peroxide-free tooth-bleaching agents: A systematic review, meta-analysis, and technological prospecting.

Phytother Res 2020 May 16;34(5):1060-1070. Epub 2019 Dec 16.

Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, Brazil.

The aim of this study is to analyze the efficacy of natural bleaching agents and the current technological development in this research field. Two reviewers performed a literature search up to July 2019 in 15 databases. Five laboratory studies and 25 patents were included. Data regarding natural bleaching agent used, application protocol, and the main findings of studies were analyzed. Laboratory studies that evaluated natural bleaching agents' peroxide-free or associated to peroxides and patents related to natural bleaching agents were included. The studies evaluated papain, bromelain, chlorine dioxide, sodium chloride plus vinegar and sodium bicarbonate as peroxide-free agents; and sweet potato extract, lactoperoxidase, and peroxidase associated to peroxide used were included. Twenty-five patents were included; among the most cited are the papain and the chlorine. The addition of non-peroxide agents into peroxide showed improvement in bleaching effect with the incorporation of these non-peroxide agents (p < .05). On the other hand, peroxide-free agents did not show an improvement in bleaching effect (p < .05). The evidence in literature suggested that natural bleaching agents incorporated to peroxide may improve the bleaching. Therefore, the current literature does not support the use of natural agents as dental bleaching.
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http://dx.doi.org/10.1002/ptr.6590DOI Listing
May 2020

Evaluation of alternative photoinitiator systems in two-step self-etch adhesive systems.

Dent Mater 2020 02 9;36(2):e29-e37. Epub 2019 Dec 9.

Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas, Gonçalves Chaves st. 457, Pelotas, RS, 96015-560, Brazil. Electronic address:

Objective: The aim of this study was to evaluate the effect of different photoinitiator systems on the cell viability and physico-chemical properties of an experimental adhesive resin of a two-step self-etch adhesive system.

Methods: Eight photoinitiators and coinitiators were evaluated, camphorquinone (CQ); ethyl-dimethylamino benzoate (EDAB); diphenyliodonium hexafluorophosphate (DPIHFP); 1,3-benzodioxole (BDO); piperonyl alcohol (AP); 1,3-diethyl-2-thiobarbituric acid (TBA); bisphenyl phosphinic oxide (BAPO); and diphenyl phosphinic oxide (TPO). Seven experimental adhesive resins (Bis-GMA:TEGDMA - 1:1 by wt%) were formulated by varying the initiation systems: R (control), R, R, R, R, R and R. The cell viability of the different photoinitiators in their isolated form and after being incorporated into the adhesive resins was evaluated using the MTT assay. The degree of conversion within the hybrid layer (DC in situ) was evaluated by micro-Raman spectroscopy; the polymerization kinetics, by FTIR spectroscopy. The water sorption (Wsp) and solubility (Wsl) were calculated by using percentage of gain and loss of mass. Data were analyzed using One-way ANOVA and Kruskal-Wallis tests (α=0.05).

Results: When evaluated in their isolated form, the DPIHFP was considered cytotoxic in all concentrations evaluated. When incorporated into and adhesive resin, R presented higher cell viability values than control and the highest values of DC in situ (p<0.05). Additionally, the use of CQ+TBA showed a higher cell viability when compared with the conventional CQ+EDAB system.

Significance: The pair CQ+TBA could be potentially useful in the development of materials with improved biocompatibility.
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http://dx.doi.org/10.1016/j.dental.2019.11.008DOI Listing
February 2020

Experimental Resin-Based Monoblock Endodontic Obturation System.

Biomed Res Int 2019 7;2019:3512606. Epub 2019 Nov 7.

University of Cuiaba, Cuiaba, Brazil.

Objective: The aim of the present study was to characterize a novel resin-based monoblock endodontic obturation system consisting of a polymeric cone and a resin-based endodontic sealer.

Methods: The preliminary tests performed for the experimental cone were as follows: cohesive strength, dimensional stability, standardization of the diameter and taper, calcium ion release, and radiopacity, for the characterization of the experimental sealer, film thickness and flow tests were performed. Tests were performed according to the American National Standards Institute/American Dental Association (ANSI/ADA) Standards Nos. 57 and 78. The experimental cone was compared to gutta-percha, whereas the experimental sealer was compared to AH Plus. Data were analyzed by Student's -test ( = 0.05).

Results: The experimental cone had superior values for cohesive strength and dimensional stability compared to gutta-percha. Regarding calcium ion release, the experimental system continued to release calcium ions after 30 days. Film thickness was similar for both endodontic sealers; conversely, the experimental resin-based sealer achieved higher values for flow compared to AH Plus.

Conclusion: The experimental resin-based monoblock obturation system fully met the requirements of the ANSI/ADA Standard No. 78 and the ANSI/ADA Standard No. 57, except for radiopacity. Considering this, further studies are still needed to evaluate other radiopacifiers and the effect of their incorporation on the physicochemical properties of this novel resin-based monoblock endodontic obturation system.
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http://dx.doi.org/10.1155/2019/3512606DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6877987PMC
April 2020

Repair bond strength of bulk-fill resin composite: Effect of different adhesive protocols.

Dent Mater J 2020 Mar 13;39(2):236-241. Epub 2019 Nov 13.

Academic Area of Dentistry, Autonomous University of Hidalgo State.

This study evaluated the effect of different adhesive protocols on the shear bond strength (SBS) of bulk-fill resin composite repaired with bulk-fill or conventional composite. Cylindrical bulk-fill resin composite specimens were prepared and allocated into groups according to the bonding strategy: no treatment, Silane+Scotch Bond Multipurpose (S+SBMP), Tetric N Bond Universal, and Single Bond Universal. Following bonding strategy, bulk-fill or conventional composite buildups were performed. After 24 h of storage in distilled water at 37°C, shear force was applied to the interface using a universal testing machine. The data were analyzed by two-way ANOVA and Tukey test (α=0.05). SBS was influenced by the bonding strategy and the composite used (p<0.001). Irrespective of the composite used, the group S+SBMP yielded the highest SBS values (p<0.001). Repair bond strength of bulk-fill composites can be improved by using a silane coupling agent followed by a hydrophobic resin.
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http://dx.doi.org/10.4012/dmj.2018-291DOI Listing
March 2020

Impact of shelf-life simulation on bonding performance of universal adhesive systems.

Dent Mater 2019 09 19;35(9):e204-e219. Epub 2019 Jun 19.

Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas. Gonçalves Cháves 457, Pelotas, RS 96015-560, Brazil. Electronic address:

Objectives: To evaluate the micro-tensile bond strength to dentin (μTBS), the degree of conversion (DC) and nanoleakage expression (NL) of eight dental adhesives considering their expiry date (as-received, half-life and or end of shelf-life) after shelf-life simulation.

Methods: Five universal adhesives (Single Bond Universal, SBU; Tetric Bond Universal, TBU; OneCoat Universal, OCU; OptiBond Universal, OBU; and Prime&Bond Elect, P&B), two two-step self-etch adhesives (Clearfil SE, CSE; and AdheSE, ASE) and one two-step etch-and-rinse adhesive (Adper Singlebond 2, ASB) were evaluated. Shelf-life was simulated by storing the materials in an acclimatization chamber for different periods of time. The μTBS was tested in accordance with ISO/TS 11,405. DC was evaluated by means of FTIR spectroscopy. NL was evaluated after ammoniacal silver challenge. The significance level of α=0.05 was used for all statistical analyses.

Results: The μTBS to dentin of TBU, P&B, ASE, and ASB adhesive systems remained stable throughout the shelf-life periods evaluated, while for SBU, OCU, OBU, and CSE, decreased significantly after evaluation in the 'half-life' or 'end of shelf-life' condition (p<0.05). Except for P&B, ASE and OBU, the degree of conversion significantly decreased after the shelf-life simulation (p<0.05). OCU, ASE, and CSE showed significantly increased percentage of silver deposition within the adhesive layer (p<0.05).

Significance: Storing conditions and progressively longer storage time affect the performance of universal adhesives systems.
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http://dx.doi.org/10.1016/j.dental.2019.05.023DOI Listing
September 2019

Bond Strength of Methacrylate-based Blends Containing Elastomeric Monomers and Alternative Initiators after Thermomechanical Cycling.

J Adhes Dent 2019 ;21(3):281-286

Purpose: To evaluate the bond strength to dentin produced by experimental adhesives formulated with an elastomeric methacrylate monomer (EMM) and an alternative initiator system based on a Thioxanthone derivative (QTX).

Materials And Methods: A self-etching primer was used. For the bonding resin, a model adhesive (G1) was formulated containing bis-GMA/TEG-DMA/HEMA (co-monomeric blend) + CQ/EDAB (initiator system). The other groups were formulated by adding to this formulation: EMM only (G2), QTX (G3), or EMM and QTX (G4). Clearfil SE Bond was used as the commercial control group. Fifty bovine teeth (n = 5) were restored with each one of the five adhesives. After restorative procedures, half of the specimens were stored in distilled water at 37°C for 24 h. The other half was fixed on a metal stub and subjected to 200,000 mechanical (50 N loading at 2 Hz frequency) and 1000 thermal cycles (5°C and 55°C). Afterwards, specimens were serially sectioned into beams and tested in tension until fracture. Bond strengths were statistically analyzed by two-way ANOVA and Tukey's test (α = 5%).

Results: After 24 h, significantly higher µTBS was observed for the formulation containing EMM and QTX (G4) when compared to Clearfil SE Bond (p < 0.05). No significant differences in µTBS were detected among the experimental groups after 24 h (p>0.05). After thermomechanical cycling, no significant differences were observed among groups.

Conclusion: The addition of EMM and QTX can be considered as possible alternative in dental adhesive formulations.
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http://dx.doi.org/10.3290/j.jad.a42549DOI Listing
October 2019

New generation bulk-fill resin composites: Effects on mechanical strength and fracture reliability.

J Mech Behav Biomed Mater 2019 08 27;96:214-218. Epub 2019 Apr 27.

Department of Dentistry, Health Science Institute, Federal University of Juiz de Fora, Governador Valadares, Brazil; BioMat Group, Materials Applied to Biosystems, Federal University of Juiz de Fora, Governador Valadares, Brazil; Graduate Program in Dental Clinic, Federal University of Juiz de Fora, Juiz de Fora, Brazil. Electronic address:

Purpose: To investigate the mechanical performance and fracture reliability of new generation, bulk-fill resin composites of different viscosities.

Methods: Forty sound maxillary premolars were prepared into Class I cavities comprised of 5 mm width × 5 mm length × 5 mm thickness. The teeth were randomly allocated into four groups (n = 10) according to the restorative material: Negative control - without restoration; Positive control - conventional resin composite (Opallis; FGM) was applied using increments of up to 2.0 mm-thick; Bulk-Regular - bulk-fill resin composite of regular viscosity (Opus Bulk Fill; FGM) was applied using a single increment of 5 mm-thick; and Bulk-Flow - a low-viscosity bulk-fill resin composite (Opus Bulk Fill Flow; FGM) was applied as the first increment with ∼3.5 mm-thick, followed by two final increments of Opallis (∼1.5 mm-thick). The teeth were stored at 37 °C, for 24 h, and submitted to a mechanical testing machine (DL500; EMIC) under a compressive loading. Work of fracture (W) was also obtained. All data were analyzed using ANOVA and Tukey (α = 5%). Reliability of restorations and probability of failure were analyzed by Weibull analysis.

Results: The non-restored teeth showed the weakest behavior of the study. All the restored groups demonstrated similar mechanical properties to each other (p ≥ 0.242). The positive and negative controls failed exclusively within the cohesiveness of enamel/dentin, whereas the bulk-fill-based restorations showed a mixture of cohesive and mixed failures. The restored groups showed an overall similar reliability, although the Bulk-Regular group demonstrated greater characteristic strength than the positive control.

Conclusion: The novel bulk-fill resin composites of low and regular viscosities show promising application in the restoration of Class I cavities in premolars, demonstrating similar mechanical performance and reliability as compared with restorations prepared using conventional resin composites. From the bulk-fill materials, the version with regular viscosity presented the greatest compliant behavior of the study.
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http://dx.doi.org/10.1016/j.jmbbm.2019.04.046DOI Listing
August 2019

Bonding Performance of Universal Adhesives: An Updated Systematic Review and Meta-Analysis.

J Adhes Dent 2019 ;21(1):7-26

Purpose: To evaluate through a systematic review and meta-analysis whether the immediate and long-term bonding performance of universal adhesives would be improved by prior acid etching.

Materials And Methods: Two reviewers performed a literature search up to April 2018 in eight databases: PubMed, Web of Science, Cochrane Library, SciELO, Scopus, LILACS, IBECS, and BBO. Only studies that evaluated the dentin or enamel bond strength of universal adhesives using a self-etch or etch-and-rinse strategy were included. Analyses were carried out using RevMan 5.3.5 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). A global analysis comparing self-etch or etch-and-rinse strategies and the influence of aging on bonding performance was performed with random-effects models at a significance level of p < 0.05.

Results: A total of 59 in vitro studies were included in the meta-analysis. The enamel bond strength of universal adhesives was improved by the etch-and-rinse approach (p < 0.05). In dentin, this effect was observed for ultra-mild and intermediately strong universal adhesives (p < 0.05). Irrespective of the strategy employed, intermediately strong adhesives showed a decrease in bond strength after all types of aging. This effect was also observed for ultra--mild universal adhesives used in the etch-and-rinse approach (p < 0.05). Mild universal adhesives showed bond strength stability in both strategies (p > 0.05).

Conclusions: The in vitro evidence suggests that bonding performance of mild universal adhesives can be improved by using the selective enamel-etch strategy. Mild universal adhesives seem to be the more stable materials, in both etch-and-rinse or self-etch strategies.
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http://dx.doi.org/10.3290/j.jad.a41975DOI Listing
October 2019

Addition of phosphates and chlorhexidine to resin-modified MTA materials.

J Biomed Mater Res B Appl Biomater 2019 08 14;107(6):2195-2201. Epub 2019 Jan 14.

Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.

To evaluate the properties of experimental mineral trioxide aggregate (MTA) resin-modified materials for root-end filling procedures, varying their compositions regarding the addition of hydroxiapatite (HA) or dicalcium phosphate dihydrate, with or without chlorhexidine digluconate. White MTA (Angelus, Londrina, Brazil) was used as a reference material. Degree of conversion (DC) was evaluated by Fourier transformed infrared (FTIr) spectroscopy (n = 5). Flowability (n = 3) and radiopacity (n = 3) were evaluated following ISO 6876:2001 methods. For splitting tensile strength analysis, cylindrical samples (n = 10) were subjected to compressive load using a universal testing machine (Instron Corporation, Norwood, MA). Water sorption and solubility tests were performed according to ISO 4049:2009 methods. Calcium ion release and pH analysis (n = 10) were evaluated using a pH meter (Orion, Watsonville, CA). Cytotoxicity (n = 8) of materials extracts was evaluated as cell viability percentage. Statistical analysis was performed using Kolmogorov-Smirnov for normal distribution and data was subjected to one-way ANOVA and Tukey test (α = 0.05). Addition of chlorhexidine digluconate reduced DC mean values for experimental materials (<50%). White MTA demonstrated lower flowability (5.3 mm) and higher radiopacity (9.8 mm Al), splitting tensile strength (9.1 MPa), solubility (8.2 μg/mm ), calcium ion release (~26.5 ppm), cytotoxicity (55.2%), and pH mean values (10.8), when compared to experimental materials. All groups demonstrated a decrease in calcium release (<85%) and pH (<13%). Formulation containing HA demonstrated similar pH values after 28 days when compared to white MTA. Evaluated experimental resin-modified MTA based materials without chlorhexidine digluconate showed satisfactory results for all physico-chemical properties tested and cytotoxicity. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2195-2201, 2019.
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http://dx.doi.org/10.1002/jbm.b.34315DOI Listing
August 2019

Physical and Biological Properties of a High-Plasticity Tricalcium Silicate Cement.

Biomed Res Int 2018 27;2018:8063262. Epub 2018 Nov 27.

Faculty of Dentistry, Federal University of Pelotas, Pelotas, Brazil.

Introduction: Mineral Trioxide Aggregate (MTA) is a tricalcium-based silicate, dicalcium silicate matrix. Despite its good biologic properties, some clinicians still claim to have difficulties in handling MTA after its preparation due to its sandy consistency. The aim of the present study was to evaluate the physicochemical properties and cytotoxicity of MTA Repair HP (Angelus, Londrina, PR, Brazil) compared with MTA Angelus (Angelus, Londrina, PR, Brazil).

Materials And Method: The properties assessed were particle size, setting time, flow, film thickness, radiopacity, water solubility, compressive strength, and cytotoxicity. Statistical analysis was performed considering p < 0.05 as statistically significant.

Results: For radiopacity, water absorption and solubility MTA Repair HP were statistically similar to MTA Angelus. The MTA Angelus had statistically different film thickness values, higher than MTA Repair HP (p < 0.05). Besides, MTA Angelus showed a lower and statistically different compressive strength after 28 days than MTA Repair HP (p<0.05). Additionally, MTA Repair HP set more slowly (p < 0.05). Relative to cell viability, MTA Repair HP was statistically similar to MTA Angelus after 24 and 48 h in cell viability.

Conclusions: The MTA Repair HP presented similar cell viability, lower film thickness, higher flow, setting time, and compressive strength values after 28 days than MTA Angelus. In general, the MTA Repair HP presented physicochemical and biological properties similar to the MTA Angelus.
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http://dx.doi.org/10.1155/2018/8063262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288567PMC
April 2019

Development and characterization of a novel bulk-fill elastomeric temporary restorative composite.

J Appl Oral Sci 2018 Dec 10;27:e20180183. Epub 2018 Dec 10.

Universidade Federal de Pelotas, Faculdade de Odontologia, Programa de Pós-Graduação em Odontologia (PPGO), Pelotas, Rio Grande do Sul, Brasil.

Objectives: This study investigated the physical and mechanical properties, antibacterial effect and biocompatibility of novel elastomeric temporary resin-based filling materials (TFMs) containing zinc methacrylate (ZM).

Material And Methods: Experimental TFMs were prepared by mixing the zinc methacrylate with monomer, co-monomer, photoinitiator and fillers. A ZM concentration of 0 (control), 0.5% (Z0.5); 1% (Z1), 2% (Z2), or 5% (ZM5) wt% was added to the TFMs. Fermit-N (F) was used for comparison with the experimental material. Microleakage, water sorption/solubility, degree of conversion, depth of cure, ultimate tensile strength, and hardness were determined and compared. A modified direct contact test (DCT) with Enterococcus faecalis and a Streptococcus mutans' biofilm accumulation assay was carried out to evaluate the antimicrobial effect and cytotoxicity of the assay. Statistical comparisons were performed (α=5%).

Results: The results showed that the physical and mechanical properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference and some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values. TFMs with ZM killed E. faecalis only after 1 h. Biofilm development of S. mutans was not affected by the inclusion of ZM in the experimental TFMs.

Conclusions: The present findings suggest that the physical, mechanical and biological properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference. However, some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values.
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http://dx.doi.org/10.1590/1678-7757-2018-0183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6296286PMC
December 2018

Efficacy of rhBMP-2 in Cleft Lip and Palate Defects: Systematic Review and Meta-analysis.

Calcif Tissue Int 2019 02 26;104(2):115-129. Epub 2018 Oct 26.

Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, Brazil.

The aim of this study was to analyze the efficacy of using rhBMP-2 (recombinant human morphogenetic protein-2) in the treatment of patients with cleft lip and palate defects (CLPD). Seven databases were screened: PubMed (Medline), Lilacs, Ibecs, Web of Science, BBO, Scopus, and The Cochrane Library. Clinical trials that evaluated the use of bioactive treatment with rhBMP-2 in the treatment of patients with CLPD were included. Statistical analyses were performed by comparing the standardized mean difference of bone formation volume and bone filling percentage (p = 0.05). Ten studies compared the use of rhBMP-2 and iliac crest bone graft (ICBG). The global analysis for bone formation volume and bone filling percentage showed that bioactive materials were similar to ICBG with a standardized mean difference of respectively 0.07 (95% CI - 0.41 to 0.56) and 0.24 (95% CI - 0.32 to 0.80). The available literature suggested that use of rhBMP-2 presented similar bone formation results to those of ICBG in secondary alveolar bone grafting for patients with CLPD.
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http://dx.doi.org/10.1007/s00223-018-0486-1DOI Listing
February 2019

Long-term bonding efficacy of adhesives containing benzodioxioles as alternative co-initiators.

Braz Oral Res 2018 Oct 11;32:e104. Epub 2018 Oct 11.

Universidade Federal de Pelotas - UFPel, Graduate Program in Dentistry, Pelotas, RS, Brazil.

This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives - 1,3-benzodioxole (BDO) and piperonyl alcohol (PA) - as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or ethyl 4-dimethylamino benzoate (EDAB - amine). An experimental self-etch primer was used to complete the two-step, self-etch adhesive system. Clearfil SE Bond (CSE) was used as commercial reference. Bond strength to human dentin was assessed by microtensile bond strength (µTBS) test, and failure mode was classified. Morphology of the dentin bonding interface was assessed via scanning electron microscopy (SEM). Irrespective of the dental adhesives evaluated, µTBS was higher after 24 hours compared with that after 1.5 and 3 years (p ≤ 0.001). However, adhesives with BDO and PA as co-initiators showed significantly higher bond strength than the bonding resin with EDAB (p ≤ 0.002), independent of the time evaluated. The commercial adhesive CSE showed similar bond strength compared with the other groups (p ≥ 0.05). Mixed failures were mainly observed after 24 hours, while adhesive failures were more frequently observed after 1.5 and 3 years. No notable differences in homogeneity and continuity along the bonded interfaces were detected among the materials in the SEM analysis. In conclusion, benzodioxole derivatives are feasible alternative co-initiators to tertiary amine in camphorquinone-based self-etching dental adhesive formulations.
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http://dx.doi.org/10.1590/1807-3107bor-2018.vol32.0104DOI Listing
October 2018

Piperonyl methacrylate: Copolymerizable coinitiator for adhesive compositions.

J Dent 2018 12 22;79:31-38. Epub 2018 Sep 22.

Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. Electronic address:

Objectives: This study describes the synthesis of piperonyl methacrylate (PipM) and evaluates its effect when used as coinitiator in the photoinitiated radical polymerization of experimental adhesive resins.

Methods: PipM was synthetized through an esterification reaction and characterized by FTIR and H NMR spectroscopy. Adhesive resins containing camphorquinone as photoinitiator and PipM or ethyl-4-dimethyl amine benzoate (EDAB) as coinitiators were formulated. Scotchbond Multipurpose (SBMP) adhesive was used as commercial reference. All materials were analyzed for polymerization kinetics, flexural strength, elastic modulus, water sorption/solubility, shear bond strength to bovine enamel and dentin, characterization of hybrid layer by scanning electron microscopy (SEM), microbiological direct contact test, and cytotoxicity.

Results: The adhesive with PipM presented higher degree of conversion and lower sorption/solubility when compared with other groups. Shear bond strength to enamel and dentin were similar for PipM and EDAB materials. The percentage of cellular viability was close to 100% and similar in the experimental groups and the commercial reference.

Conclusions: PipM presented similar or superior performance to the tertiary amine used as control, representing a potential alternative coinitiator for photopolymerizable dental materials.

Clinical Significance: PipM could be potentially useful in the formulations of adhesive systems with enhanced chemical properties, which could mean improvement in the longevity of composite resin restorations.
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http://dx.doi.org/10.1016/j.jdent.2018.09.006DOI Listing
December 2018

Evaluation of physical-mechanical properties, antibacterial effect, and cytotoxicity of temporary restorative materials.

J Appl Oral Sci 2018 20;26:e20170562. Epub 2018 Aug 20.

Departamento de Odontologia Restauradora,, Faculdade de Odontologia, Universidade Federal de Pelotas, Pelotas, RS, Brasil.

The objective of this study was to compare selective physical-mechanical properties, antibacterial effects and cytotoxicity of seven temporary restorative materials (TRM): five resin-based materials [Bioplic (B), Fill Magic Tempo (FM), Fermit inlay (F), Luxatemp LC (L) and Revotek LC (R)], and zinc oxide-eugenol cement (IRM) and glass ionomer cement (GIC) as the controls. Material and methods The physical-mechanical properties were evaluated by determining microleakage (ML), ultimate tensile strength (UTS) and Shore D hardness (SDH). In addition, the polymerization rate (Pr-1), depth of cure (DC), water sorption and solubility (WS/SL) were evaluated. The antimicrobial effects of the materials were assessed by biofilm accumulation of Streptococcus mutans (BT) and the direct contact test (DCT) by exposure to Enterococcus faecalis for 1 and 24 h, and cytotoxicity by MTT assay. The data were analyzed by ANOVA or Kruskall-Wallis tests, and a complementary post-hoc method (p<0.05). Results Group B, followed by FM and GIC had significantly lower percentages of microleakage in comparison with the other groups; Groups FM and L showed the highest WS, while Groups R and FM showed the significantly lowest SL values (p<0.05). Group R showed the statistically highest UTS mean and the lowest DC mean among all groups. Group F showed the lowest S. mutans biofilm accumulation (p=0.023). Only the Group L showed continued effect against E. faecalis after 1 h and 24 h in DCT. The L showed statistically lower viability cell when compared to the other groups. Conclusions These findings suggest the antibacterial effect of the temporary materials Fill Magic and Bioplic against S. mutans, while Luxatemp showed in vitro inhibition of S. mutans biofilm accumulation and E. faecalis growth. Regarding the cell viability test, Luxatemp was the most cytotoxic and Fill Magic was shown to be the least cytotoxic.
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http://dx.doi.org/10.1590/1678-7757-2017-0562DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6110458PMC
September 2018

Synthesis of an allyl carbonate monomer as alternative to TEGDMA in the formulation of dental composite resins.

J Mech Behav Biomed Mater 2018 11 30;87:148-154. Epub 2018 Jul 30.

Laboratorio de Polímeros, Instituto de Ciencias Básicas e Ingeniería, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo Km. 4.5 Colonia Carboneras, Mineral de la Reforma Hidalgo, C.P. 42184, Mexico. Electronic address:

Over the past years, significant effort has been dedicated to synthesizing low-shrinking formulations, however, development of dental composites with low volumetric shrinkage continues to be challenging. The purpose of this study was to synthesize a bisphenol allylic derivate (BPhADAC) and evaluate its inclusion in the formulation of a photopolymerizable dental composite resin, as a BisGMA diluent. Experimental (BisGMA/BPhADAC) and control (BisGMA/TEGDMA) photopolymerizable composites were prepared. Double bond conversion, polymerization kinetics, volumetric shrinkage, water sorption, solubility, and flexural properties were investigated. The experimental composite showed higher degree of conversion values, less volumetric shrinkage and less water sorption than the control composite (p < 0.05). In addition, flexural strength between the materials was found to be similar. The overall properties prove that the allylic monomer BPhADAC could be potentially useful in the formulation of low-shrinking dental composite resins.
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http://dx.doi.org/10.1016/j.jmbbm.2018.07.016DOI Listing
November 2018

Polymerization shrinkage stress of resin-based dental materials: A systematic review and meta-analyses of composition strategies.

J Mech Behav Biomed Mater 2018 06 23;82:268-281. Epub 2018 Mar 23.

Department of Restorative Dentistry and Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, Brazil. Electronic address:

Purpose: A systematic review was conducted to determine whether there were composition strategies available to reduce and control polymerization shrinkage stress development in resin-based restorative dental materials.

Data Sources: This report was reported in accordance with the PRISMA Statement. Two reviewers performed a literature search up to December 2016, without restriction of the year of publication, in seven databases: PubMed, Web of Science, Scopus, SciELO, LILACS, IBECS, and BBO.

Study Selection: Only laboratory studies that evaluated polymerization shrinkage stress by direct testing were included. Pilot studies, reviews and in vitro studies that evaluated polymerization shrinkage stress by indirect methods (e.g., microleakage or cuspal deflection measurements), finite elemental analysis, or theoretical and mathematical models were excluded. Of the 6113 eligible articles, 62 studies were included in the qualitative analysis, and the meta-analysis was performed with 58 studies. The composition strategy was subdivided according to the modified part of the material: filler phase, coupling agent, or resin matrix. A global comparison was performed with random-effects models (α = 0.05). The only subgroup that did not show a statistical difference between the alternative strategy and the control was 'the use of alternative photo-initiators' (p = 0.29).

Conclusion: Modification of the resin matrix made the largest contribution to minimizing stress development. The technology used for decreasing stress in the formulation of low-shrinkage and bulk-fill materials was shown to be a promising application for reducing and controlling stress development.
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http://dx.doi.org/10.1016/j.jmbbm.2018.03.019DOI Listing
June 2018

Polymerization shrinkage stress of resin-based dental materials: A systematic review and meta-analyses of technique protocol and photo-activation strategies.

J Mech Behav Biomed Mater 2018 06 8;82:77-86. Epub 2018 Mar 8.

Department of Restorative Dentistry and Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, Brazil. Electronic address:

Purpose: A systematic review was conducted to determine whether there were any alternative technique or additional step strategies available to reduce and control polymerization shrinkage stress development in dental resin-based restorative materials.

Data Sources: This report followed the PRISMA Statement. A total of 36 studies were included in this review. Two reviewers performed a literature search up to December 2016, without restriction of the year of publication, in seven databases: PubMed, Web of Science, Scopus, SciELO, LILACS, IBECS, and BBO.

Study Selection: Only in vitro studies that evaluated polymerization shrinkage stress by direct testing were included. Pilot studies, reviews and in vitro studies that evaluated polymerization shrinkage stress by indirect methods (e.g., microleakage or cuspal deflection measurements), finite elemental analysis or mathematical models were excluded. Of the 6.113 eligible articles, 36 studies were included in the qualitative analysis, and the meta-analysis was performed with 25 studies. A global comparison was performed with random-effects models (α = 0.05). The strategies were subdivided as follows: the use of an alternative technique protocol of placing the material inside the tooth cavity; the modification of the irradiation intensity or total energy delivered to the material; the use of an alternative light-curing source; or the use of an alternative photo-activation mode. All alternative strategies showed statistically significant differences when compared with their respective controls (p < 0.05).

Conclusion: The use of alternative light-curing sources contributed more to minimizing stress development than placing the material by means of an alternative technique protocol or by modifying the irradiant intensity or total energy delivered to the material during photo-activation. Moreover, the use of an alternative photo-activation mode (intermittent light, exponential, soft-start or pulse delay modes) was shown to be an effective strategy for reducing and controlling stress development in resin-based dental materials.
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http://dx.doi.org/10.1016/j.jmbbm.2018.03.004DOI Listing
June 2018

Evaluation of long-term bond strength and selected properties of self-adhesive resin cements.

Braz Oral Res 2018 Mar 1;32:e15. Epub 2018 Mar 1.

Universidade Federal de Pelotas - UFPel, Materials Engineering School, Department of Organic Chemistry, Pelotas, SC, Brasil.

This study evaluated the shear bond strength (SBS) of self-adhesive resin cements (SARCs) to dentin and their physical-chemical properties. Five commercial SARCs were evaluated [SmartCem®2 - DENTSPLY (SC2); BisCem® - Bisco (BC); SeT PP® - SDI (SeT); Relyx U100® - 3M ESPE (U100) and YCEM® SA - Yller (YCEM)]. The SARCs were evaluated for SBS to dentin (n = 10) after 24 h, 6 months, and 12 months. The dentin demineralization caused by acidic monomers was observed by SEM, and pH-neutralization of eluate was observed for 24 h. Degree of conversion (DC), rate of polymerization (Rp), flexural strength (FS), and elastic modulus (E) were evaluated. Immediate SBS of SC2, SET, U100, and YCEM were statistically higher than that of BC (p < 0.001). After 12 months, all SARCs showed reduced SBS values and U100 showed values similar to those of SET and YCEM, and higher than those of BC and SC2 (p = 0.001). Demineralization pattern of SARCs was similar. At 24h, all SARCs showed no differences in the pH-value, except BC and U100 (p < 0.001). YCEM showed the highest Rp. U100, YCEM, and SC2 showed statistically higher FS (p<0.001) and E (p < 0.001) when compared with SET and BC. U100 and YCEM showed the best long-term bonding irrespective of the storage period. A significant reduction in SBS was found for all groups after 12 months. SBS was not shown to be correlated with physical-chemical properties, and appeared to be material-dependent. The polymerization profile suggested that an increased time of light activation, longer than that recommended by manufacturers, would be necessary to optimize DC of SARCs.
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http://dx.doi.org/10.1590/1807-3107bor-2018.vol32.0015DOI Listing
March 2018