Orthodontic resins loaded with niobium silicate particles: Impact of filler concentration on the physicochemical and biological properties.

OBJECTIVES: White spot lesions (WSL) are prevalent in patients using orthodontic appliances. The presence of ion-releasing compounds in the tooth-appliance interface may limit enamel demineralization to control WSL incidence. Thus, this study aims to evaluate the mineral formation on SiNb-containing experimental orthodontic resins and the influence of these fillers on the physicochemical and biological properties of developed materials. MATERIALS AND METHODS: The SiNb particles were synthesized via the sol-gel route and characterized by their molecular structure and morphology. Photopolymerizable orthodontic resins were produced with a 75 wt% Bis-GMA/25 wt% TEGDMA and 10 wt%, 20 wt%, or 30 wt% addition of SiNb. A control group was formulated without SiNb. These resins were tested for their degree of conversion, softening in solvent, cytotoxicity in fibroblasts, flexural strength, shear bond strength (SBS), and mineral deposition. RESULTS: The addition of 10 wt% of SiNb did not impair the conversion of monomers, cytotoxicity, and flexural strength. All groups with SiNb addition presented similar softening in solvent. The presence of these particles did not affect the bond strength between metallic brackets and enamel, with SBS values ranging from 16.41 to 18.66 MPa. The mineral deposition was observed for all groups. CONCLUSION: The use of niobium silicate as filler particles in resins may be a strategy for the adhesion of orthodontic appliances. The 10 wt% SiNb concentration resulted in a material with suitable physicochemical and biological properties while maintaining the bond strength to tooth enamel and promoting mineral deposition.

Synthesis of silver core-shell nanoparticles and their influence on an experimental resin endodontic sealer: An in vitro analysis.

AIM: To avoid root canal recontamination and endodontic treatment failure, endodontic sealers with antibacterial activity could be an alternative. Silver nanoparticles have antibacterial activity and this study aimed to synthesize Ag@SiO2 nanoparticles, incorporate them into an experimental endodontic resin sealer and evaluate their influence on physicochemical and biological properties. METHODOLOGY: Ag@SiO2 nanoparticles were produced using the sol-gel process, based on the Stöber method. The particles were characterized in terms of their chemical structure by Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-Vis spectral analysis, scanning electron microscopy, and transmission electron microscopy, where the particle morphology and diameter were analysed. A dual-cured experimental endodontic resin sealer was formulated using 70 wt% UDMA, 15 wt% GDMA, and 15 wt% BisEMA. The photoinitiators were added separately in two pastes. The Ag@SiO2 nanoparticles were incorporated into the endodontic sealer at the concentrations of 2.5 wt%, 5 wt%, and 10 wt%, and a control group without nanoparticles was also formulated. The endodontic sealers were evaluated for their flow, film thickness, degree of conversion, softening in solvent, radiopacity, cytotoxicity and antibacterial activity immediately and after 9 months in water storage. RESULTS: Silver was detected in the chemical characterization of Ag@SiO2 that presented a spheric regular shape and average 683.51 nm ± 93.58 diameter. Sealers presented adequate flow and film thickness while radiopacity values were below the ones required by ISO 6876. All groups underwent softening after immersion in a solvent. The 10 wt% groups showed a higher loss of subsurface hardness (∆KHN%). No reduction in cell viability was observed. Enterococcus faecalis viability in biofilm was reduced in 10 wt% groups after 24 h and 9 months. CONCLUSION: The addition of 10 wt% Ag@SiO2 reduced E. faecalis viability at immediate and longitudinal analysis while maintaining the physicochemical properties of developed sealers.

Three-dimensional (3D) printing in dental practice: Applications, areas of interest, and level of evidence.

OBJECTIVES: The aim of this review to overview three-dimensional (3D) printing technologies available for different dental disciplines, considering the applicability of such technologies and materials development. MATERIALS AND METHODS: Source Arksey and O'Malley's five stages framework using PubMed, EMBASE, and Scopus (Elsevier) databases managed this review. Papers focusing on 3D printing in dentistry and written in English were screened. Scientific productivity by the number of publications, areas of interest, and the focus of the investigations in each dental discipline were extracted. RESULTS: Nine hundred thirty-four studies using 3D printing in dentistry were assessed. Limited clinical trials were observed, especially in Restorative, endodontics, and pediatric dentistry. Laboratory or animal studies are not reliable for clinical success, suggesting that clinical trials are a good approach to validate the new methods' outcomes and ensure that the benefits outweigh the risk. The most common application for 3D printing technologies is to facilitate conventional dental procedures. CONCLUSIONS: The constantly improving quality of 3D printing applications has contributed to increasing the popularity of these technologies in dentistry; however, long-term clinical studies are necessary to assist in defining standards and endorsing the safe application of 3D printing in dental practice. CLINICAL RELEVANCE: The recent progress in 3D materials has improved dental practice capabilities over the last decade. Understanding the current status of 3D printing in dentistry is essential to facilitate translating its applications from laboratory to the clinical setting.

Non-thermal plasma for surface treatment of inorganic fillers added to resin-based cements.

OBJECTIVES: This study aims to evaluate the effect of non-thermal plasma (NTP) surface treatment in two composite inorganic fillers and evaluate their impact on the chemical-mechanical properties and bond strength ability of experimental resin cements. MATERIALS AND METHODS: Ytterbium fluoride (YF) and barium silicate glass (BS) were characterized and submitted to different surface treatments: non-thermal plasma (NTP); non-thermal plasma and 3-(trimethoxysilyl) propyl methacrylate silanization; and 3-(trimethoxysilyl) propyl methacrylate silanization. Untreated fillers were used as a control. The fillers were incorporated at 65wt% concentration into light-cured experimental resin cements (50wt% BisGMA; 25wt% UDMA; 25wt% TEGDMA; 1mol% CQ). The degree of conversion, the flexural strength, and the microshear bond strength (µSBS) were evaluated to characterize developed composites. RESULTS: YF and BS were successfully cleaned with NTP treatment. Nor NTP neither the silanization affected the degree of conversion of resin cements. The NTP predicted an increase in YF-containing resin cements flexural strength, reducing the storage impact in these materials. NTP treatment did not affect the µSBS when applied to YF, while silanization was effective for BS-containing materials. CONCLUSION: NTP treatment of inorganic particles was possible and was shown to reduce the amount of organic contamination of the particle surface. YF surface treatment with NTP can be an alternative to improve the organic/inorganic interaction in resin composites to obtain materials with better mechanical properties. CLINICAL RELEVANCE: Surface cleaning with NTP may be an alternative for particle surface cleaning to enhance organic-inorganic interaction in dental composites resulting in improved mechanical strength of experimental resin cements.

Physicochemical and biological properties of experimental dental adhesives doped with a guanidine-based polymer: an in vitro study.

OBJECTIVES: The objective of this study is to formulate experimental dental adhesives with different polyhexamethylene guanidine hydrochloride concentrations (PHMGH) and evaluate their physical, chemical, and biological properties. MATERIALS AND METHODS: The experimental adhesives were formulated with 0 (control, GCTRL), 0.5 (G0.5%), 1 (G1%), or 2 (G2%) wt.% into the adhesive. The adhesives were analyzed for degree of conversion (DC%), softening in solvent (ΔKHN%), ultimate tensile strength (UTS), microtensile bond strength (µTBS) immediately and after 1 year of aging, antibacterial activity, and cytotoxicity. RESULTS: There were no differences among groups for DC%, ΔKHN%, and UTS (p > 0.05%). There were no differences between each PHMGH-doped adhesive compared to GCTRL in the immediate µ-TBS (p > 0.05). Adhesives with at least 1 wt.% of PHMGH presented better stability of µ-TBS. PHMGH-doped adhesives showed improved longitudinal µ-TBS compared to GCTRL (p < 0.05). Lower Streptococcus mutans biofilm formation was observed for PHMGH-doped adhesives (p < 0.05). There was lower viability of planktonic S. mutans in the media in contact with the samples when at least 1 wt.% of PHGMGH was incorporated (p < 0.05). The formulated adhesives showed no cytotoxicity against pulp cells (p > 0.05). CONCLUSIONS: The adhesive with 2 wt.% of PHMGH showed the highest antibacterial activity, without affecting the physicochemical properties and cytotoxicity, besides conferring stability for the dental adhesion. CLINICAL RELEVANCE: PHMGH, a positively charged polymer, conveyed antibacterial activity to dental adhesives. Furthermore, it did not negatively affect the essential physicochemical and biocompatibility properties of the adhesives. More importantly, the incorporation of PHMGH provided stability for the µ-TBS compared to the control group without this additive.

Alkyl trimethyl ammonium bromide for the formulation of antibacterial orthodontic resins.

OBJECTIVES: This study aimed at formulating antibacterial orthodontic resins containing alkyl trimethyl ammonium bromide (ATAB) and evaluating their physicochemical and biological properties. MATERIALS AND METHODS: The chemical composition and microstructure of ATAB was characterized through FTIR and SEM, respectively. Experimental orthodontic BisGMA/TEGDMA-based resins were formulated, and the ATAB filler was incorporated at 1wt%, 5wt%, and 10wt%, along with colloidal silica (5wt%). The degree of conversion, softening in solvent, and flexural strength of the experimental resins were analyzed. Biological properties were also assessed through cytotoxicity and antibacterial analyses. RESULTS: The incorporation of ATAB, due to the presence of ⎯N+(CH3)3 alkyl groups, had no adverse effect on the degree of conversion of the resins (p > 0.05). The %ΔKHN values at 5wt% and 10wt% were comparable to those of the control group, while the flexural strength was reduced at all concentrations of ATAB. The viability of the gingival fibroblast was reduced with the addition of ATAB (p < 0.05). The viability of biofilm and planktonic bacteria was reduced when ATAB was incorporated at 5wt% and 10wt%. CONCLUSIONS: The addition of ATAB at 5wt% resulted suitable for the formulation of orthodontic resins with the ability to control the biofilm formation and planktonic activity of S.mutans, without jeopardizing some specific physicochemical properties. CLINICAL RELEVANCE: White spot lesions in orthodontic patients may be controlled by preventive treatments. Non-patient-dependent strategies, such as the use of orthodontic resins containing ATAB, may avoid accumulation of bacteria, especially in those areas surrounding orthodontic appliances.

Biological Activity of Copaiba in Damage to the Alveolar Bone in a Model of Periodontitis Induced in Rats.

Several studies have investigated the effects of natural products in the treatment of diseases. Traditional Amazonian populations commonly use copaiba due to its well-known anti-inflammatory, antibacterial, and healing properties. In this study, we aimed to investigate the effects of systemic administration of copaiba oleoresin (Copaifera reticulata Ducke) on ligature-induced periodontitis in rats. To do so, 21 adult rats were divided into three groups (n = 7 each): a control group, ligature-induced periodontitis group, and ligature-induced periodontitis group treated with copaiba oleoresin (200 mg/kg/day). The ligature remained from day 0 to 14, and the copaiba oleoresin was administered via oral gavage during the last seven days. On day 14, the animals were euthanized, and mandibles were collected for histopathological evaluation and microcomputed tomography analysis. Our data showed that the administration of copaiba considerably reduced the inflammatory profile. Moreover, copaiba oleoresin limited alveolar bone loss, increased trabecular thickness and bone-to-tissue volume ratio, and decreased the number of trabeculae compared with those of the untreated experimental periodontitis group. Our findings provide pioneering evidence that supports the potential of copaiba oleoresin in reducing periodontitis-induced alveolar bone damage in rats.

Binge-Like Exposure During Adolescence Induces Detrimental Effects in Alveolar Bone that Persist in Adulthood.

BACKGROUND: Alcohol (EtOH) intake during adolescence has become an important public health issue. Although the detrimental effects of EtOH intake on the musculoskeletal system are well known, only a few studies have investigated its impact on the stomatognathic system of adolescents. This study aimed to investigate the effect of EtOH binge drinking on the alveolar bone and the long-term consequences after abstinence. METHODS: Adolescent female Wistar rats (35 days old) were exposed to 4 cycles of EtOH binge drinking (3 g/kg/d; 3 days On-4 days Off) or distilled water (control group). Alveolar bone micromorphology and vertical bone distance were evaluated at 1, 30, and 60 days after that last EtOH intake through X-ray computed microtomography. The mineral:matrix ratio was assessed through Raman spectroscopy. RESULTS: A decrease in both trabecular thickness and volume ratio, and an increase in trabecular separation were observed at the 1-day evaluation (immediate withdrawal). After 30 and 60 days, the alveolar bone parameters were found similar to control, except for the mineral:matrix ratio in the long-term abstinence. CONCLUSIONS: EtOH binge drinking during adolescence results in alveolar bone damage that may persist in adulthood, even after abstinence.

Use of flowable resin composite as an intermediate layer in class II restorations: a systematic review and meta-analysis.

OBJECTIVE: To investigate the influence of an intermediate layer of a flowable resin composite in class II resin composite restorations. MATERIALS AND METHODS: The authors searched MEDLINE via PubMed, Scopus, LILACS, Embase, and Web of Science electronic databases, and the ClinicalTrials.gov website to identify laboratory and clinical studies that evaluated class II cavities with resin composite restorations with or without an intermediate layer of flowable resin composite. Two authors independently selected the studies, extracted the data, and assessed the risk of bias and the quality of the evidence. Meta-analyses were performed using RevMan5.3 with fixed-effects model comparing bond strength (MPa), fracture strength (Newton), and clinical (number of failures) outcomes between restorative techniques (with or without flowable resin composite as an intermediate layer). RESULTS: From 1707 potentially eligible studies, 140 in vitro studies and 14 clinical studies were selected for full-text analysis, and 11 were included in the systematic review, being 7 in vitro and 4 clinical studies. There was no statistically significant difference between the restorative techniques considering the outcomes evaluated. The heterogeneity found was null. The risk of bias was classified as medium for in vitro studies and unclear in most clinical studies. The quality of the evidence of the clinical studies was low. CONCLUSION: The use of flowable resin composite as an intermediate layer does not improve the effectiveness of the class II restorations based on laboratory and clinical outcomes. CLINICAL RELEVANCE: Flowable resin composite as an intermediate layer may be used for class II restorations; however, this technique does not improve the effectiveness of the class II restorations.

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

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.% (G2.5%) and 5 wt.% (G5%) into the experimental resin-based sealant, and one group remained without METAC as control (GCTRL). 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 G5% (p < 0.05). G2.5% and G5% 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). G2.5% and G5% presented immediate and long-term antibacterial activity (p < 0.05) without cytotoxicity compared to GCTRL (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.

Blood Oxidative Stress Modulates Alveolar Bone Loss in Chronically Stressed Rats.

We aimed to investigate the effects of chronic stress (CS) on experimental periodontitis (EP) in rats. For this, 28 Wistar rats were divided into four groups: control, ligature-induced experimental periodontitis (EP), chronic stress (CS; by physical restraint model) and CS+EP (association of chronic stress and ligature-induced periodontitis). The experimental period lasted 30 days, including exposure to CS every day and ligature was performed on the 15th experimental day. After 30 days, the animals were submitted to the behavioral test of the elevated plus maze (EPM). Next, rats were euthanized for blood and mandible collection in order to evaluate the oxidative biochemistry (by nitric oxide (NO), reduced-glutathione activity (GSH), and thiobarbituric acid reactive substance levels (TBARS)) and alveolar bone characterization (by morphometric, micro-CT, and immunohistochemistry), respectively. The behavioral parameters evaluated in EPM indicated higher anxiogenic activity in the CS and CS+EP, groups, which is a behavioral reflex of CS. The results showed that CS was able to change the blood oxidative biochemistry in CS and CS+EP groups, decrease GSH activity in the blood, and increase the NO and TBARS concentrations. Thus, CS induces oxidative blood imbalance, which can potentialize or generate morphological, structural, and metabolic damages to the alveolar bone.

Calcium phosphates as fillers for methacrylate-based sealer.

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% (GOCP) to 50.74% (Gcontrol) and no statistical difference were observed (p < 0.05). GAHplus 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 GHAp, GOCP, and Gα-TCP (p < 0.05). Calcium deposition values were higher for GHAp 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 Ca2+ release. CLINICAL RELEVANCE: Phosphate fillers improve the performance of endodontic sealers after 28 days of simulated body fluid.

Physical and mechanical properties of dual functional cements-an in vitro study.

OBJECTIVES: The aim of this study was to evaluate the physical and mechanical properties of different dual functional cements. MATERIALS AND METHODS: Three dual functional cements (Allcem Core (FGM), Rebilda DC (VOCO), and LuxaCore Z (DMG)), a luting resin cement (Rely X ARC (3 M ESPE)), and a Core Buildup composite resin GrandioSo (VOCO) were used. Flexural strength (n = 10) and film thickness (n = 6) were evaluated according to ISO 4049:2009. Flow (n = 6) was evaluated according to ISO 6876:2001. Degree of conversion (DC) was assessed immediately and 24 h after polymerization (n = 5). For resistance to dislodgment (RD) analysis, bovine teeth were prepared to receive fiber glass posts, and a push-out test (n = 12) was used. RESULTS: Luxacore Z presented lower flexural strength when compared to GrandioSo (p < 0.001). No statistical difference was found between cements for film thickness (p = 0.66). Reduced flow values were found for Allcem Core (p = 0.006). No statistical difference was found for immediate DC for different cements (p > 0.05). After 24 h, DC increased for all groups, except for Luxacore Z (p = 0.054). The RD did not differ from the control Rely X ARC, regardless of the root third (p > 0.05). Luxacore Z showed lower mean values in the apical third compared to the coronal third (p = 0.046). CONCLUSIONS: The dual functional cements (Allcem Core and Rebilda DC) possessed similar physical and mechanical properties of luting resin cement (RelyX ARC) and Core Buildup composite resin (GrandioSo). Hence, they could be used for one-stage post and core buildup restorations. CLINICAL RELEVANCE: The dual functional cements could be used for one-stage post and core buildup restorations since they possess similar physical and mechanical properties of luting resin cements and Core Buildup composite resin.

Effect of nanostructured zirconium dioxide incorporation in an experimental adhesive resin.

OBJECTIVES: The aim of this study was to evaluate the influence of nanostructured zirconium dioxide incorporation in an experimental adhesive resin. METHODS: ZrO2 particles were characterized by X-ray diffraction (XRD), micro-Raman spectroscopy and Brunauer-Emmett-Teller (B.E.T). Experimental adhesive resins were formulated with 0, 0.5, 1, 4.8, and 9.1% ZrO2 in weight. The adhesives were evaluated based on degree of conversion (DC), radiopacity, softening in solvent and microtensile bond strength (µTBS) 24 h and after 1 year of aging. Mineral deposition at the hybrid layer was assessed with micro-Raman spectroscopy at the baseline and after 14 days. RESULTS: XRD showed monoclinic and tetragonal phases of ZrO2.particles. B.E.T data revealed a surface area of 37.41 m2/g, and typical chemical groups were shown on the Raman spectra. The addition of ZrO2 did not influence the radiopacity. The addition of 4.8% and 9.1 wt.% ZrO2 showed higher initial hardness with increased softening in solvent (P < 0.05) and promoted mineral deposition at the dentin interface. DC was significantly increased in the group with 1% ZrO2 (P < 0.05). The µTBS test showed difference on the group with 9.1 wt.% of ZrO2, with a significant reduction after aging. CONCLUSION: The incorporation of ZrO2 promoted mineral deposition on the adhesive interface and the addition of 1 wt.% caused a significant increase on the DC without compromising the other physicochemical characteristics, which may prove promising for the development of new dental adhesive systems. CLINICAL RELEVANCE: The mineral deposition on the hybrid layer can result in a longer stability of the adhesive, thus delaying the hydrolytic degradation.

Influence of Different Calcium Phosphates on an Experimental Adhesive Resin.

PURPOSE: To formulate adhesive resins with 2 wt% of hydroxyapatite (HAp), α-tricalcium phosphate (α-TCP), or octacalcium phosphate (OCP) and to compare these groups with an unfilled adhesive regarding the degree of conversion, polymerization rate, microshear bond strength and mineral deposition. MATERIALS AND METHODS: The experimental adhesive resin was formulated mixing 66.6 wt% bisphenol A glycol dimethacrylate (bis-GMA), 33.3 wt% 2-hydroxyethyl methacrylate (HEMA), and a photoinitiator system. OCP, α-TCP, or HAp were added in concentrations of 2 wt% to the adhesive, and a group without additional filler was used as the control. Calcium-phosphate particle sizes were determined using a laser-diffraction particle-size analyzer. The degree of conversion (DC) of the adhesives was determined with FTIR-ATR. The polymerization rate (Rp) was determined using differential scanning calorimetry equipped with a photocalorimetric accessory. Adhesive bonding was evaluated using the microshear bond strength test in sound bovine mandibular incisors. Mineral deposition in human third molars affected by caries was evaluated using micro-Raman spectroscopy after selective removal of carious dentin. Data were analyzed by one-way ANOVA and Tukey's test (α = 0.05). RESULTS: HAp presented the highest mean particle size (26.7 nm), while that of α-TCP was 6.03 nm and OCP was 4.94 nm. The DC of all groups was above 50%. The OCP group showed the fastest Rp, with no difference from the control group (p > 0.05). The α-TCP group presented the highest microshear bond strength (p = 0.005) and mineral deposition at the interface. CONCLUSION: Incorporation of α-TCP nanofiller into adhesive resins can improve bond strengths and may be a promising strategy to achieve therapeutic remineralization at the composite-dentin interface.

In vitro antibacterial and remineralizing effect of adhesive containing triazine and niobium pentoxide phosphate inverted glass.

OBJECTIVES: White spot lesions are still a concern for orthodontic patients. The objective of this study was to assess the remineralizing and antibacterial effect of a newly developed orthodontic adhesive. METHODS: The compounds 1,3,5-tryacryloylhexahydro-1,3,5-triazine (TAT) and phosphate invert glass containing 10 mol% of niobium pentoxide (PIG-Nb) were added at 20 and 5 wt%, respectively, to an experimental adhesive (75 wt% BisGMA, 25 wt% TEGDMA, 5 wt% fummed silica, and photo-initiator system), called TPN. A group without the addition of these compounds was used as Control and the orthodontic adhesive Transbond XT (TXT) was used for comparison. Antibacterial activity was evaluated through surface biofilm formation, mineral deposition, and degree of conversion (DC) through Raman microscopy, Knoop hardness after softening in solvent, and bracket dislodgement (BD). RESULTS: TPN group presented a reduction in bacterial growth when compared to Control and TXT. Mineral deposits were observed on the surface of TPN adhesive after 14 and 28 days of immersion in artificial saliva. There was an increase in DC after 28 days, whereas TPN group presented the highest DC. All groups underwent some degree of softening. No significant changes were observed in BD after 28 days of immersion in artificial saliva. CONCLUSION: The newly developed orthodontic adhesive, with addition of 20 wt% TAT and 5w% PIG-Nb, exhibited antibacterial activity and was capable to induce mineral deposition on its surface in vitro. CLINICAL SIGNIFICANCE: The orthodontic adhesive developed in this study with antibacterial activity and mineral deposition could be a reliable choice for brackets adhesion.

Effect of indomethacin-loaded nanocapsules incorporation in a dentin adhesive resin.

OBJECTIVES: The aim of this study was to produce indomethacin-loaded nanocapsules (IndOH-NCs) and evaluate the influence of their incorporation into an adhesive resin. MATERIALS AND METHODS: Indomethacin was encapsulated by the deposition of preformed polymer. IndOH-NCs were characterized by laser diffractometry, Fourier transformed infrared spectrometry, transmission electron microscopy (TEM), scanning electron microscopy, high-performance liquid chromatography (HPLC), and MTT assay. Nanocapsules (NCs) were incorporated into an adhesive in concentrations of 1, 2, 5, and 10 %. The addition was visualized by TEM and drug release was evaluated by HPLC until 120 h of immersion in simulated body fluid (SBF). Drug diffusion through dentin was tested using a Franz diffusion cell apparatus and quantified by HPLC. The degree of conversion (DC), softening in ethanol, and microtensile bond strength (µTBS) were evaluated to determine whether the nanocapsules influenced the adhesive. Data were analyzed using one-way ANOVA and Tukey's post hoc test for DC, softening in ethanol, µTBS, and cytotoxicity, and paired t test for comparison between the initial and final Knoop microhardness. RESULTS: IndOH-NCs, with a spherical shape and a mean diameter of 165 nm, were incorporated into an adhesive. Indomethacin content was 7 mg drug/g powder. IndOH-NCs maintained high cell viability. At 120 h, an amount of 13.83 % of indomethacin was released, and after 7 days, 7.07 % of this drug was diffused through dentin for an adhesive containing 10 % of nanocapsules. No alteration in the DC, softening in ethanol, and µTBS resulted from NC addition. CONCLUSIONS: IndOH-NCs may be incorporated into adhesive systems, without compromising properties, to add an anti-inflammatory drug controlled release for restorative procedures in deep cavities. CLINICAL SIGNIFICANCE: Here is the first step toward the goal of providing agents to act at an inflammatory process of pulp tissue through dental adhesives via encapsulation of drug.

Influence of an iodonium salt on the properties of dual-polymerizing self-adhesive resin cements.

STATEMENT OF PROBLEM: Dual-polymerizing self-adhesive resin cements present mechanical properties that may adversely affect the clinical performance of luted fiber-reinforced posts. PURPOSE: The purpose of this in vitro study was to evaluate the properties of dual-polymerizing self-adhesive resin cements after the addition of an onium salt. MATERIAL AND METHODS: The experimental groups were set according to the molar concentration of diphenyliodonium hexafluorphosphate (DPIHFP) (0.5, 1, and 2 mol%). The resin cements were submitted to a push-out bond strength test and assessed for flexural strength (ISO 4049/2009), degree of conversion (Fourier-transformed infrared spectroscopy), depth of polymerization, swelling coefficient, and degradation in solvent. The data were statistically analyzed by ANOVA, Tukey test, Kruskal-Wallis test, Dunn multiple comparison, and paired Student t test (α=.05). RESULTS: All the RelyX U100 groups with onium salt showed the highest degree of conversion after 24 hours and 7 days (P<.001). However, no statistical difference was found among the BisCem groups (P=.054). The addition of 0.5 mol% DPIHFP increased the push-out bond strength and microhardness of RelyX U100 and promoted less degradation after immersion in solvent. The BisCem control group did not present a statistical difference from the experimental groups in terms of bond strength; the control group and the 0.5 mol% group showed no degradation in solvent. For swelling coefficient and flexural strength, no difference was found between the BisCem groups (P=.067 and P=.173), and the RelyX U100 2 mol% group presented the lower value (P<.001 and P=.048). Depth of polymerization was not statistically different in the experimental groups for either resin cement (P=.999). CONCLUSIONS: The addition of 0.5 mol% DPIHFP improved the physical properties of dual-polymerizing self-adhesive resin cements.

Thermocompaction decreases long-term push-out bond strength of methacrylate-based sealers.

PURPOSE: The purpose of this study was to evaluate the immediate and long-term bond strengths to root dentin of Epiphany/Resilon and AH Plus/gutta-percha fillings, after using either lateral condensation or Tagger's hybrid thermomechanical compaction techniques. MATERIALS AND METHODS: Eighty human single-rooted teeth were used. The root canals were prepared by means of hand crown-down technique up to a #45 K-file and irrigation with 1% sodium hypochlorite was performed. Samples were randomly divided into eight (n=10) experimental groups divided according to filling material (gutta-percha/AH Plus and Resilon/Epiphany), obturation technique (Lateral compaction and Tagger's hybrid thermomechanical compaction) and storage time (24 h and 6 months). During storage, the samples were kept at 37°C and 100% humidity. After the two experimental periods, each root was sectioned perpendicular to its long axis into three serial slices and push-out tests were carried out using a universal testing machine. Statistical significant differences were set by ANOVA and Tuckey post-hoc (p<0.05). RESULTS: Using thermocompaction technique, the samples filled with Epiphany/Resilon decreased significantly the bond strength after a 6 months storage-period (p<0.05) and the ones filled with AH Plus/gutta-percha presented a tendency to lower values of the push-out test, although not statistically significant. For both materials, dentin bond strength of the specimens filled by means of lateral condensation remained stable throughout the experimental periods. CONCLUSION: Under the limitations of the current study, it can be concluded that the thermocompaction technique and the storage time can influence push-out bond strength when used with methacrylate-based sealers.

Effect of methacrylated-based antibacterial monomer on orthodontic adhesive system properties.

INTRODUCTION: Antibacterial adhesives were developed to reduce the incidence of white spot lesions in orthodontic patients. Compounds that contain triazine are known as effective antibacterial agents. The aims of this study were to develop an experimental orthodontic adhesive containing 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT) and to characterize it. METHODS: TAT was added in 3 concentrations (10%, 15%, and 20%) to the experimental orthodontic adhesive. Antibacterial activity was assayed by brain-heart infusion broth dilution against Streptococcus mutans. The degree of conversion was measured using Fourier transform infrared spectroscopy, and solvent degradation was evaluated by Knoop microhardness before and after immersion in ethanol for 2 hours. The shear bond strength of metal brackets bonded to bovine enamel surface was assessed. RESULTS: All experimental adhesives reduced bacterial growth. The addition of 15% and 20% TAT increased the degree of conversion compared with the control group (0%) and the 10% group. All groups showed a decrease in hardness after ethanol immersion, and there was also a decrease in the percentage of variation of Knoop hardness in the experimental adhesives containing TAT, whereas the shear bond strength increased. CONCLUSIONS: Orthodontic adhesives containing TAT are promising antibacterial materials, especially those with 15% and 20% TAT.