Effect of antioxidants on adhesive bond strength to bleached enamel.

OBJECTIVE: To evaluate the influence of antioxidants (ATX) resveratrol, winter's bark, green tea and yerba mate on the bond strength between bleached enamel and the nanohybrid composite resin. METHODOLOGY: Bovine incisor crowns (n = 132) were randomly divided into 22 groups (n = 6) according to the application times (5, 10, 15, 30, and 60 min) of each antioxidant. Teeth restored without previous bleaching or ATX constituted the non-bleached control group (NB Ctrl) (n = 6), and teeth restored after bleaching and without ATX represented the bleached control group (B Ctrl) (n = 6). The 35 % hydrogen peroxide was applied for 45 min (3 application of 15 min) to the buccal enamel surface. ATX was used after bleaching for the specified time of each group and removed with air-water spray. The enamel was etched with 37 % phosphoric acid (30 s) and rinsed with air-water spray. The adhesive resin was applied to the enamel dry surface. Teeth were restored using 1 mm composite resin increments (10 × 10 × 3 mm) and sectioned in test specimens of 6 mm in length and 1 mm2 in cross-sectional area submitted to microtensile bond strength test (0.5 mm/min). The load (N) at failure was recorded, and the bond strength (σt) was calculated (MPa). The fracture area was analyzed under optical microscopy, and failures were classified as cohesive, mixed, or adhesive. Data was evaluated by Kruskal-Wallis and Dunn tests (p ≤ 0.05). RESULTS: B Ctrl group presented lower σt than NB Ctrl (p < 0.001). Applying resveratrol for 5 or 10 min, winter's bark for 10 or 15 min, green tea for less than 15 min, and yerba mate for 15 min provided similar σt between bleached enamel and nanohybrid composite to the control group. CONCLUSION: Restorative procedures performed immediately after tooth bleaching compromises adhesion. Experimental antioxidants applied to bleached enamel can increase the immediate bond strength of restorations performed directly after bleaching, with similar values to those observed in unbleached enamel. CLINICAL SIGNIFICANCE: This study presents promising results to support the use of antioxidants on the recently bleached enamel to allow adhesive tooth restorations. The immediate bonding obtained using antioxidants was similar to the one achieved in non-bleached enamel in brief application times. Green tea extract and resveratrol were able to restore the bond strength to bleached enamel in a short application time of 5 min. The reduction in the required application time holds the potential to decrease the overall duration of the clinical section, offering clinical advantages and improving the feasibility of using antioxidants on the bleached enamel prior to adhesive procedures.

Shear Bond Strength and Film Thickness of a Naturally Antimicrobial Modified Dental Luting Cement.

Although several natural plants and mixtures have been known and used over the centuries for their antibacterial activity, few have been thoroughly explored in the field of dentistry. Thus, the aim of this study was to enhance the antimicrobial activity of a conventional glass ionomer cement (GIC) with natural plant extracts. The effect of this alteration on the bond strength and film thickness of glass ionomer cement was evaluated and related to an 0.5% chlorohexidine modified GIC. Olive leaves (Olea europaea), Fig tree (Ficus carica), and the leaves and roots of Miswak (Salvadora persica) were used to prepare an alcoholic extract mixture. The prepared extract mixture after the evaporation of the solvent was used to modify a freeze-dried glass ionomer cement at three different extracts: water mass ratios 1:2, 1:1, and 2:1. An 0.5% chlorhexidine diacetate powder was added to a conventional GIC for the preparation of a positive control group (CHX-GIC) for comparison. The bond strength to dentine was assessed using a material-testing machine at a cross head speed of 0.5 mm/min. Failure mode was analyzed using a stereomicroscope at 12× magnification. The cement film thickness was evaluated in accordance with ISO standard 9917-1. The minimum number of samples in each group was n = 10. Statistical analysis was performed using a Kruskal-Wallis test followed by Dunn's post hoc test for pairwise comparison. There was a statistically insignificant difference between the median shear bond strength (p = 0.046) of the control group (M = 3.4 MPa), and each of the CHX-GIC (M = 1.7 MPa), and the three plant modified groups of 1:2, 1:1, 2:1 (M = 5.1, 3.2, and 4.3 MPa, respectively). The CHX-GIC group showed statistically significant lower median values compared to the three plant-modified groups. Mixed and cohesive failure modes were predominant among all the tested groups. All the tested groups (p < 0.001) met the ISO standard of having less than 25 µm film thickness, with the 2:1 group (M = 24 µm) being statistically the highest among all the other groups. The plant extracts did not alter either the shear bond strength or the film thickness of the GIC and thus might represent a promising additive to GICs.

Evaluation of the antimicrobial activity and compressive strength of a dental cement modified using plant extract mixture.

Literature lacks sufficient data regarding addition of natural antibacterial agents to glass ionomer cement (GICs). Hence, the aim of the study was to increase the antimicrobial properties of GICs through its modification with mixture of plant extracts to be evaluated along with an 0.5% chlorohexidine-modified GIC (CHX-GIC) with regard to biological and compressive strength properties. Conventional GIC (freeze-dried version) and CHX were used. Alcoholic extract of Salvadora persica, Olea europaea, and Ficus carcia leaves were prepared using a Soxhlet extractor for 12 h. The plant extract mixture (PE) was added in three different proportions to the water used for preparation of the dental cement (Group 1:1 PE, 2:1 PE, and 1:2 PE). Specimens were then prepared and tested against the unmodified GIC (control) and the 0.5% CHX-GIC. Chemical analysis of the extract mixture was performed using Gas chromatography-mass spectrometry. Antimicrobial activity was evaluated using agar diffusion assay against Micrococcus luteus and Streptoccocus mutans. Compressive strength was evaluated according to ISO 9917-1:2007 using a Zwick testing machine at a crosshead speed of 0.5 mm/min. Antimicrobial activity against Streptoccocus mutans was significantly increased for all the extract-modified materials compared to the unmodified cement, and the highest concentration was comparable to the CHX-GIC mixture. The activity against Micrococcus luteus was also significantly increased, but only for the material with the highest extract concentration, and here the CHX-GIC group showed statistically the highest antimicrobial activity. Compressive strength results revealed that there was no statistically significant difference between the different mixtures and the control except for the highest tested concentration that showed the highest mean values. The plant extracts (PEs) enhanced the antimicrobial activity against S. mutans and also against M. luteus in the higher concentration while compressive strength was improved by addition of the PE at higher concentrations.

Influence of grape seed extract in adhesion on dentin surfaces conditioned with Er,Cr:YSGG laser.

The proanthocyanidin (PA)-rich grape seed extract (GSE) is a collagen cross-linking agent that can perform a chemical bond with the dentin's collagen. The objective of this study was to evaluate the influence on shear bond strength (SBS) of the pre-conditioning of GSE, on human dentin surfaces conditioned with Er,Cr:YSGG laser. The sample consisted of 64 non-carious human teeth, divided into eight groups, four groups conditioned with Er,Cr:YSGG laser (4.5 W, 50 Hz, 50 µs, 70% air, 90% water) and four prepared with conventional methods (control). In both groups, a GSE solution was applied before using the two adhesives tested: Clearfil™ SE Bond (CSE) and Scotchbond™ Universal (SU). Subsequently, a SBS test, a scanning electron microscopy, and a statistical analysis were performed. In the laser groups, the best SBS mean (20.08 ± 4.01 MPa) was achieved in the group treated with GSE and CSE. The control group with the application of CSE showed the highest SBS mean (24.27 ± 10.28 MPa), and the group treated with laser and SU showed the lowest SBS mean (12.94 ± 6.51 MPa). Between these two groups there was a statistically significant difference (p = 0.05). However, this was not observed among the laser or control groups. The type of dentin surface preparation can influence the SBS. The CSE showed better SBS in laser and control groups. The presence of GSE did not improve the adhesion on surfaces conditioned with laser, but more studies should be carried out in the future to confirm this conclusion.

Physico-mechanical and antimicrobial properties of an orthodontic adhesive containing cationic curcumin doped zinc oxide nanoparticles subjected to photodynamic therapy.

BACKGROUND: Potential complications on the crown level during fixed orthodontic procedures are white spot, enamel demineralization and tooth decay. This study evaluated the antimicrobial properties of an orthodontic adhesive incorporating cationic curcumin doped zinc oxide nanoparticles (cCur/ZnONPs), which can have the highest concentration of cCur/ZnONPs and shear bond strength (SBS) value simultaneously, against cariogenic bacteria including Streptococcus mutans, Streptococcus sobrinus, and Lactobacillus acidophilus. MATERIALS AND METHODS: Following synthesis and confirmation of cCur/ZnONPs, SBS and adhesive remnant index (ARI) of the test adhesives containing cCur/ZnONPs (1.2, 2.5, 5, 7.5, and 10% wt.) were measured using universal testing machine and stereomicroscope, respectively. After continuously rinsed (up to 180 day), the residual antimicrobial ability of modified adhesives which can have the highest concentration of cCur/ZnONPs and SBS value simultaneously were determined by disc agar diffusion (DAD), biofilm formation inhibition, and metabolic activity assays following photo-activation using light-emitting diode (LED) for 5 min against multispecies cariogenic biofilm-producing bacteria. RESULTS: Adhesive with 7.5% wt. cCur/ZnONPs showed the highest concentration of cCur/ZnONPs and SBS value (14.89 ± 3.26 MPa, P < 0.05) simultaneously. No significant differences in ARI scores were found between the modified adhesive and control (Transbond XT without the cCur/ZnONPs). 7.5% wt. cCur/ZnONPs following photo-activation was not colonized by the test microorganisms and suppressed 100% metabolic activity of the test microorganisms up to 90 day compared to the control group (cCur/ZnONPs free LED irradiation; P < 0.05). In DAD assay, the reduction of photodynamic disinfection of the 7.5% wt. cCur/ZnONPs against test bacteria was positively associated to the time, in such a way that it was decreased significantly after 60 day. From days 120 onwards, microbial biofilm formation and metabolic activity was progressively increased on 7.5% wt. cCur/ZnONPs adhesive discs compared to the control group (cCur/ZnONPs free LED irradiation). CONCLUSIONS: Our findings highlight the photo-activated 7.5% wt. cCur/ZnONPs can serve as an orthodontic adhesive additive to control the cariogenic multispecies biofilm, and also to reduce their metabolic activity.

Antimicrobial effect of bioceramic cements on multispecies microcosm biofilm: a confocal laser microscopy study.

OBJECTIVES: To assess the viability of multispecies microcosm biofilm after contact with NeoMTA Plus, Biodentine, and MTA Angelus. MATERIALS AND METHODS: Fifty-four human dentin blocks (4 × 5 × 4 mm) were allocated to Hawley retainers, worn by six volunteers for 72 h. The blocks were then individually incubated in BHI broth for 21 days at 37 °C. At the end of experimental time for biofilm growth, the samples were randomly divided into four groups (n = 12): NeoMTA Plus, Biodentine, MTA Angelus, and negative control. The materials were placed in contact with the blocks. All samples were placed in cell-culture plate wells and incubated in BHI broth for 7 days at 37 °C. One sample from each volunteer (n = 6) was analyzed by SEM to describe the biofilm morphology. CLSM was performed to determine the percentage of viable biofilm biovolume. The data were statistically analyzed by one-way ANOVA and Tukey's multiple comparison test (α = 5%). RESULTS: SEM showed biofilm formed by spherical and rod-shaped bacteria surrounded by an extracellular matrix. No material was able to kill all biofilm cells, and all groups had more than 50% of viable bacteria. NeoMTA Plus was significantly different from the negative control group (P < .05). CONCLUSIONS: All tested materials were not effective against multispecies microcosm biofilm. CLINICAL RELEVANCE: NeoMTA Plus, Biodentine, and MTA Angelus were not effective against multispecies microcosm biofilm. It is essential to understand that these bioceramic cements are indicated for infected clinical situations. Thus, complementary disinfection procedures should be conducted prior to filling with these materials.

Ph-activated nano-amorphous calcium phosphate-based cement to reduce dental enamel demineralization.

Enamel demineralization is destructive, esthetically compromised, and costly complications for orthodontic patients. Nano-sized amorphous calcium phosphate (NACP) has been explored to address this challenge. The 20% NACP-loaded ortho-cement notably exhibited favorable behavior on reducing demineralization of enamel around brackets in a caries model designed to simulate the carious attack. The 20% NACP-loaded ortho-cement markedly promotes higher calcium and phosphate release at a low pH, and the mineral loss was almost two fold lower and carious lesion depth decreased the by 1/3. This novel approach is promising co-adjuvant route for prevention of dental caries dissemination in millions of patients under orthodontic treatment.

Laser phototherapy enhances mesenchymal stem cells survival in response to the dental adhesives.

BACKGROUND: We investigated the influence of laser phototherapy (LPT) on the survival of human mesenchymal stem cells (MSCs) submitted to substances leached from dental adhesives. METHOD: MSCs were isolated and characterized. Oral mucosa fibroblasts and osteoblast-like cells were used as comparative controls. Cultured medium conditioned with two adhesive systems was applied to the cultures. Cell monolayers were exposed or not to LPT. Laser irradiations were performed using a red laser (GaAlAs, 780 nm, 0.04 cm(2), 40 mW, 1 W/cm(2), 0.4 J, 10 seconds, 1 point, 10 J/cm(2)). After 24 h, cell viability was assessed by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide reduction assay. Data were statistically compared by ANOVA followed by Tukey's test (P < 0.05). RESULTS: Different cell types showed different viabilities in response to the same materials. Substances leached from adhesives were less cytotoxic to MSCs than to other cell types. Substances leached from Clearfil SE Bond were highly cytotoxic to all cell types tested, except to the MSCs when applied polymerized and in association with LPT. LPT was unable to significantly increase the cell viability of fibroblasts and osteoblast-like cells submitted to the dental adhesives. CONCLUSION: LPT enhances mesenchymal stem cells survival in response to substances leached from dental adhesives.

Interfacial characteristics of Biodentine and MTA with dentine in simulated body fluid.

OBJECTIVES: Newer tricalcium silicate cements (TSC) may offer biocompatibility with improved working properties. This study aimed to evaluate: (1) the occurrence of mineral deposition at the interface between dentine and two TSC (ProRoot(®) MTA and Biodentine(®)) in simulated body fluid, and (2) to investigate the nature of interfacial layer. METHODS: Six root dentine segments of 1.5mm thickness were obtained from extracted human teeth and were instrumented with Gates-Glidden drills. The specimens were then randomly filled with either MTA or Biodentine. The specimens were placed in the simulated body fluid containing the same phosphate concentration as blood plasma. After 4 weeks, the specimens were examined with Scanning Electron Microscope (SEM) and Energy Disperse X-ray Spectroscopy (EDX) to measure the thickness of the interfacial layer and Ca/P ratio. Transmission Electron Microscope (TEM) and Selective Area Electron Diffraction (SAED) were conducted to examine the interface ultramicroscopically and to determine the nature of the crystalline structure within interfacial layer. RESULTS: The thickness of interfacial layer was significantly higher in the MTA group (14.5 µm vs 4.8 µm) (p<0.001). However, there was no significant difference between MTA and Biodentine in Ca/P ratio of interfacial layer (4.1 vs 2.7) (p>0.05). From TEM examination, amorphous calcium phosphate (ACP) was observed in the interface along with the surface of dentine. CONCLUSIONS: As an alternative to MTA, Biodentine displayed bioactivity by producing an interfacial layer on the root canal dentine even though its thickness was significantly lower than MTA. ACP was observed in the interfacial layer of both biomaterials. CLINICAL SIGNIFICANCE: Biodentine could be considered as an alternative to MTA due to comparable bioactivity which creates interfacial layer between root canal dentin and Biodentine.

The effect of low-level laser therapy (810 nm) on root development of immature permanent teeth in dogs.

Traumatic injuries and dental caries can be a big challenge to immature teeth. In these cases, the main purpose of treatment is to maintain the pulp vitality. The purpose of this study was to investigate the effect of low-level laser therapy on accelerating the rate of dentinogenesis in pulpotomy of immature permanent teeth (apexogenesis). Three dogs, 4-6 months old, were used in this study. One jaw in each dog was randomly assigned to laser irradiation group. All selected teeth were pulpotomized with mineral trioxide aggregate (MTA) and restored with amalgam. In the laser group, the Ga-Al-As laser (810 nm, 0.3 W, 4 J/cm(2), 9 s) was used on buccal and lingual gingiva of each tooth in 48 h intervals for 2 weeks. In order to observe the newly formed dentine, tetracycline was injected on the 1st, 3rd, 7th, and 14th day after the operation. Then, ground sections of teeth were observed under a fluorescence microscope. The data was analyzed with Generalized Estimating Equations (GEE) test. The mean distance between the lines of tetracycline formed on the 1st and 14th day was significantly higher in the laser group (P = 0.005). Within the limitation of this study, irradiation of Ga-Al-As laser (810 nm) can accelerate the rate of dentinogenesis in apexogenesis of immature permanent teeth with MTA in dogs.

In vitro evaluation of the minimum bactericidal concentrations of different root-end filling materials.

AIM: The aim of this study was to evaluate the minimum bactericidal concentrations (MBC) of root-end filling materials ProRoot MTA, MTA Angelus and IRM. MATERIALS AND METHODS: Macrodilution broth method was used. Microorganisms used were: Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212) and Streptococcus mutans. Serial two-fold dilutions of root-end filling samples were prepared in macrodilution tubes with concentrations ranging from 1/2 to 1/512. The samples dilutions were incubated for 24 hours. After incubation, 0.1 ml of diluted culture was inoculated onto the surface of supplemented sheep blood agar (Merck, Germany) and all plates were incubated at 37°C in aerobic condition for 24 hours. The MBC was defined as the lowest concentration of root-end filling samples where no growth was recorded. RESULTS: MBC of both mineral trioxide aggregate (MTA) products against S. aureus were recorded as 15.62 mg/ml and for IRM 31.25 mg/ml MBC for both MTA groups against E. faecalis were recorded as 31.25 mg/ml and for IRM 62.5 mg/ml. MBC of all root-end filling samples against S. mutans were recorded as 62.5 mg/ml. CONCLUSION: All tested root-end filling materials showed acceptable MBC against S. aureus and E. faecalis. CLINICAL SIGNIFICANCE: All tested materials can be used safely for filling of a root-end cavity.

Mineral trioxide aggregate and Portland cement promote biomineralization in vivo.

INTRODUCTION: Mineral trioxide aggregate (MTA) and Portland cement have been shown to be bioactive because of their ability to produce biologically compatible carbonated apatite. This study analyzed the interaction of MTA and white Portland cement with dentin in vivo. METHODS: Seventy-two human dentin tubes were filled with MTA Branco, MTA BIO, and white Portland cement + 20% bismuth oxide (PC1) or PC1 + 10% of calcium chloride (PC2) and implanted subcutaneously in 18 rats at 4 sites from the dorsal area. Empty dentin tubes, implanted in rats of a pilot study, were used as control. After 30, 60, and 90 days, the animals were killed, and the dentin tubes were retrieved for scanning electron microscope analysis. RESULTS: In the periods of 30 and 60 days, the mineral deposition in the material-dentin interface (interfacial layer) and in the interior of dentinal tubules was detected in more tubes filled with MTA Branco and MTA BIO than in tubes filled with PC1 and PC2. After 90 days, the interfacial layer and intratubular mineralization were detected in all tubes except for 3 and 1 of the tubes filled with PC2, respectively. CONCLUSIONS: It was concluded that all the cements tested were bioactive. The cements released some of their components in the tissue capable of stimulating mineral deposition in the cement-dentin interface and in the interior of the dentinal tubules. MTA BIO and MTA Branco were more effective in promoting the biomineralization process than Portland cements, mainly after 30 and 60 days.

Effect of silane coupling agents and alloy primers on adhesion to titanium.

AIM: Titanium-ceramic adhesion is known to be not ideal yielding to ceramic fractures especially in extensive implant reconstructions. Intraoral repair actions could be performed chairside using adhesion promoters. This study evaluated the adhesion of resin composite to titanium alloy using different silane coupling agents and alloy primers in combination with surface conditioning methods after aging. METHODS: Titanium alloy disks were embedded in PMMA and wet polished to 1200 grit silicon carbide abrasive. Silanes and alloy primers used in combination with surface conditioning methods were as follows: 1) Al2O3 (50 µm) and Alloy Primer (Kuraray); 2) Al2O3 (50 µm) and V-Primer (Sun Medical); 3) SiO2 (30 µm) and Silane (ESPE-Sil) (CoJet System, 3M ESPE); 4) Al2O3 (50 µm) and Silane (ESPE-Sil); 5) Al2O3 (50 µm) and Cesead II Opaque Primer (Kuraray); 6) Al2O3 (50 µm) and Alloy Primer and Clearfil SE Bond Primer and Clearfil Porcelain Bond Activator (Clearfil Repair System, Kuraray). A thin layer of Sinfony opaquer was then applied, polymerized and a direct resin composite (Quadrant Photoposterior, Cavex) was adhered onto the conditioned titranium surfaces using polyethylene molds. After thermocycling (6000 cycles at 5-55 °C), specimens were submitted to shear loading in the Universal Testing Machine (crosshead speed: 1 mm/min). Failure types were classified as adhesive, cohesive in resin and a combination of adhesive and cohesive failures (mixed) after debonding. The data (MPa) were analyzed statistically using One-way ANOVA and Tukey's tests. RESULTS: Significant difference was observed between the groups (P<0.05) (1-way ANOVA). Significantly higher results were obtained from Groups 1 (25.4±7) and 6 (26.3±5) than those of other groups (11.4±3 - 22.6±9) (P<0.05) (Tukeys' test). Group 2 presented the lowest mean bond strength among all groups (11.4±3) (P<0.05). While Group 1 showed mainly cohesive (4 out of 10) and mixed failures (6 out of 10) and no adhesive failures, other groups presented mainly adhesive and mixed failures. CONCLUSION: Conditioning titanium surfaces with 50 µm Al2O3 followed by Alloy Primer or silane mixture of Clearfil Repair system delivered the most stable repair bond strength of the resin composite to titanium compared to other alloy primers and silanes tested.

Root perforations treatment using mineral trioxide aggregate and Portland cements.

PURPOSE: Clinical, radiological and histological evaluation of root perforations treated with mineral trioxide aggregate (MTA) or Portland cements, and calcium sulfate barrier. METHODS: One molar and 11 premolar teeth of a male mongrel dog received endodontic treatment and furcations were perforated with a high-speed round bur and treated with a calcium sulfate barrier. MTA, Portland cement type II (PCII) and type V (PCV), and white Portland cement (WPC) were used as obturation materials. The teeth were restored with composite resin and periapical radiographs were taken. The animal was euthanized 120 days post-surgery for treatment evaluation. RESULTS: Right lower first premolar (MTA), right lower third premolar (PCV), left lower second premolar (MTA), and right lower second premolar (WPC): clinically normal, slightly radio-transparent area on the furcation, little inflammatory infiltrate, and new-bone formation. Left lower third premolar (PCII), right upper first premolar (WPC), right upper third premolar (PCII), and left upper first molar (PCV): clinically normal, radiopaque area on the furcation, and new-bone formation. Right upper second premolar (MTA), left upper second premolar (WPC), left upper third premolar (PCII): presence of furcation lesion, large radiolucent area, and intense inflammatory infiltrate. CONCLUSION: All obturation materials used in this study induced new-bone formation.

Root perforations treatment using mineral trioxide aggregate and Portland cements / Cimentos de agregado trióxido mineral e Portland no tratamento de perfurações radiculares

PURPOSE: Clinical, radiological and histological evaluation of root perforations treated with mineral trioxide aggregate (MTA) or Portland cements, and calcium sulfate barrier. METHODS: One molar and 11 premolar teeth of a male mongrel dog received endodontic treatment and furcations were perforated with a high-speed round bur and treated with a calcium sulfate barrier. MTA, Portland cement type II (PCII) and type V (PCV), and white Portland cement (WPC) were used as obturation materials. The teeth were restored with composite resin and periapical radiographs were taken. The animal was euthanized 120 days post-surgery for treatment evaluation. RESULTS: Right lower first premolar (MTA), right lower third premolar (PCV), left lower second premolar (MTA), and right lower second premolar (WPC): clinically normal, slightly radio-transparent area on the furcation, little inflammatory infiltrate, and new-bone formation. Left lower third premolar (PCII), right upper first premolar (WPC), right upper third premolar (PCII), and left upper first molar (PCV): clinically normal, radiopaque area on the furcation, and new-bone formation. Right upper second premolar (MTA), left upper second premolar (WPC), left upper third premolar (PCII): presence of furcation lesion, large radiolucent area, and intense inflammatory infiltrate. CONCLUSION: All obturation materials used in this study induced new-bone formation.

OBJETIVO: Avaliar clínica, radiológica e histologicamente perfurações radiculares tratadas com MTA e cimentos Portland, com barreira de sulfato de cálcio. MÉTODOS: A amostra foi constituída por 11 dentes pré-molares e um molar de cão macho, sem raça definida. Após tratamento endodôntico realizaram-se perfurações nas furcas com broca esférica de alta rotação e barreira de sulfato de cálcio. Foram utiliados os cimentos MTA, Portland tipo II (CPII), Portland tipo V (CPV) e Portland branco estrutural (CPB). Os dentes foram restaurados com resina composta e submetidos a radiografias periapicais. O animal foi confinado por 120 dias e submetido à eutanásia para avaliações. RESULTADOS: Primeiro pré-molar inferior direito (MTA), terceiro pré-molar inferior direito (CPV), segundo pré-molar inferior esquerdo (MTA) e segundo pré-molar inferior direito (CPB): clinicamente normal; leve área radiotransparente na furca; pequeno infiltrado inflamatório e neoformação óssea. Terceiro pré-molar inferior esquerdo (CPII), primeiro pré-molar superior direito (CPB), terceiro pré-molar superior direito (CPII) e primeiro molar superior esquerdo (CPV): clinicamente normal; área radiopaca na furca; neoformação óssea. Segundo pré-molar superior direito (MTA), segundo pré-molar superior esquerdo (CPB) e terceiro pré-molar superior esquerdo (CPII): clinicamente com lesão na furca; intensa área radiolucida; infiltrado inflamatório intenso. CONCLUSÃO: Todos os cimentos induziram a neoformação óssea.

Antibacterial activity of restorative dental biomaterials in vitro.

This study investigated the antibacterial effects against Streptococcus mutans of a fine-hybrid resin composite (FH-RC; Tetric ceram), an ion-releasing resin composite (Ariston pHc), a self-curing glass ionomer cement (SC-GIC; Ketac-Molar), a resin-modified GIC (RM-GIC; Photac-Fil), and a zinc oxide eugenol cement (ZOE; IRM). In a novel assay, bacterial suspensions were placed into narrow 20-microl conical cavities within the materials. After 0, 4, 8, 24, 48 h and 1 week of incubation, the suspensions were removed from the restoratives and the numbers of viable bacteria were determined. After incubation periods of 8 h or more, all restorative materials except the FH-RC showed significant growth inhibition when compared with controls. The strongest antibacterial activity was observed with ZOE. The inhibitory effect of Ariston pHc was similar to that of the SC-GIC and the RM-GIC. In the second assay, growth inhibition was evaluated in liquid cultures by incubating eluates of the materials with suspensions of S. mutans. Bacterial growth was determined up to 6 h by measuring absorption at 600 nm. The most marked inhibitory effect was again observed with ZOE. The SC-GIC caused a significant inhibition at all time intervals but the FH-RC, the RM-GIC and Ariston pHc exhibited no significant antibacterial effects. It is recommended to employ more than one method for assessing the antibacterial potential of restorative materials. Long-term clinical trials are necessary to determine whether the antimicrobial effects of dental materials are able to reduce the risk of secondary caries formation.

The effect of adhesive luting agent-dentinal surface interactions on compressive strength of two types of all-ceramic crowns.

This research compared the compressive strength of two types of all-ceramic crown (Hi-Ceram and Duceram) as affected by selected luting cements (Zn phosphate, glass ionomer and composite resin cement). Thirty crowns of similar size and shape were constructed (15 crowns of each tested material) to fit a standard posterior tooth preparation. Five crowns from each material were cemented by one of the tested cements. The cemented crowns were loaded until catastrophic failure. A two-way analysis of variance was performed and showed that the type of utilized cement had a significant effect on the compressive strength being that Panevia Ex. resin cement the most effective one followed by glass ionomer and then finally zn phosphate cement. Statistical analysis also showed that Hi-Ceram crowns were more resistant to occlusal load than Duceram.

Odontoblast-like cytodifferentiation of human dental pulp cells in vitro in the presence of a calcium hydroxide-containing cement.

The cement produced microcrystals of calcite by reaction with culture medium supplemented with calf serum. Human dental pulp cells seeded on such a substrate preferentially adhered and aggregated around the microcrystals. Immunofluorescence and immunogold labelling revealed a high affinity of serum fibronectin molecules for the calcite crystals. At 4 weeks in culture, the cells had various features of differentiated odontoblasts, notably nuclear polarization, typical appearance of the Golgi apparatus, synthesis of type I collagen and absence of type III, and apical accumulation of actin and vimentin. These cells also elaborated a collagenous extracellular matrix which did not mineralize.

[Dentin bonding with tooth-colored adhesive MOD immediate inlays made of composites]. / Dentinhaftung bei zahnfarbenen adhäsiven MOD-Sofortinlays aus Komposit.

Without the use of highly effective dentinal adhesives, the cervical margins of tooth-colored adhesive inlays localized in dentin are poorly adapted. It was the purpose of this study to optimize these margins with the help of the Gluma-Clearfil combination. This goal was achieved, but the results indicated, that the success depended on the choice of the luting composite. Perfectly adapted cervical dentinal margins of tooth-colored adhesive inlays are achievable. For routine use, the system has to be simplified.