Biological investigation of resinous endodontic sealers containing calcium hydroxide.

The purpose of this study was to evaluate, in vivo, the biocompatibility, biomineralization, collagen maturation and the in vitro antibacterial and cytotoxicity of resinous endodontic sealers containing calcium hydroxide. Forty rats were implanted with polyethylene tubes containing Sealer 26, Sealer Plus, Dia-ProSeal and an empty tube, examined after 7, 15, 30 and 60 days. Antimicrobial activity was evaluated against Enterococcus faecalis by Agar Diffusion Test (ADT) through inhibition zones. For cytotoxicity, undifferentiated pulp cells (OD-21) were cultured and assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, exposed to dilution of serial extracts at 6, 24, 48h. Cytotoxicity was analyzed by two-way ANOVA and Bonferroni correction. Kruskal-Wallis test followed by Dunn test was performed for nonparametric data (p<0.05). MTT assay revealed cell proliferation affected by sealers extract in all periods (p<0.0001), except for Dia-Proseal and Sealer Plus ⅛ dilution. Subcutaneous analysis showed at day 7th moderate inflammatory infiltration. After 30 days, Sealer 26 still showed moderate inflammatory infiltrate compared to mild inflammation from control and Dia-ProSeal (p = 0.006). At day 60th, all groups showed similar mild inflammatory infiltrate (p>0.05). Sealer 26 induced more biomineralization than other sealers in all periods. At 7 and 15 days, all sealers had significant percentage of immature collagen fibers. After 60 days Sealer 26 showed more mature fibers compared to other sealers (p<0.001). All sealers had a smaller zone of inhibition than chlorhexidine, but with no significant difference among any group (p>0.05). All sealers showed satisfactory biological responses with in vitro/in vivo biocompatibility and antimicrobial activity against planktonic bacteria. Sealer 26 induced more biomineralization than Sealer Plus and Dia-ProSeal.

Proteomic analysis of infected root canals with apical periodontitis in patients with type 2 diabetes mellitus: A cross-sectional study.

AIM: This study aimed to quantitatively and qualitatively determine the proteomic profile of apical periodontitis (AP) in type 2 diabetes mellitus (T2DM) patients in comparison with systemically noncompromised patients and to correlate the protein expression of both groups with their biological functions. METHODOLOGY: The sample consisted of 18 patients with asymptomatic AP divided into two groups according to the presence of T2DM: diabetic group-patients with T2DM (n = 9) and control group-systemically healthy patients (n = 9). After sample collection, the root canal samples were prepared for proteomic analysis using reverse-phase liquid chromatography-mass spectrometry. Label-free quantitative proteomic analysis was performed by Protein Lynx Global Service software. Differences in protein expression between groups were calculated using t-test (p < .05). Biological functions were analysed using the Homo sapiens UniProt database. RESULTS: A total of 727 human proteins were identified in all samples. Among them, 124 proteins common to both groups were quantified, out of which 65 proteins from the diabetic group showed significant differences compared with the control: 43 upregulated (p < .05) and 22 downregulated (p < .05) proteins. No significant differences in protein expression were seen for the remaining 59 proteins (p > .05). Most proteins with differences in expression were related to immune/inflammatory response. Neutrophil gelatinase-associated lipocalin, Plastin-2, Lactotransferrin and 13 isoforms of immunoglobulins were upregulated. In contrast, Protein S100-A8, Protein S100-A9, Histone H2B, Neutrophil defensin 1, Neutrophil defensin 3 and Prolactin-inducible protein were downregulated. CONCLUSIONS: Quantitative differences were demonstrated in the expression of proteins common to diabetic and control groups, mainly related to immune response, oxidative stress, apoptosis and proteolysis. These findings revealed biological pathways that provide the basis to support clinical findings on the relationship between AP and T2DM.

The use of omega-3 fatty acids in the treatment of oral diseases.

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) have been reported to exert important roles in the inflammatory response. There are many inflammatory diseases in dentistry which support the administration of ω-3 PUFAs as an adjunct therapy during the treatment of these diseases. The aim of this review was to evaluate the use of ω-3 PUFAs as an adjuvant therapy during the treatment of buccal diseases. The review showed that supplementation with ω-3 PUFAs was used for treatment of gingivitis, periodontal diseases, apical periodontitis, stomatitis, and orthodontic tooth movement. The results indicate that ω-3 PUFAs decreased the number of pro-inflammatory mediators in the gingival tissues of individuals with gingivitis and periodontitis. In apical periodontitis, the supplementation suppressed bone resorption and promoted bone formation in the periapical area of rats. During orthodontic movement, the supplementation showed a decrease of bone resorption in rats. It also showed that painful symptoms of recurrent aphthous stomatitis were alleviated in supplemented patients. In conclusion, the ω-3 PUFAs may be used as an adjuvant therapy in the treatment of inflammatory diseases that affect the oral cavity. However, more studies are required to elucidate the role of ω-3 PUFAs in decreasing oral cavity inflammatory processes.

Antibiofilm activity of laser ablation with indocyanine green activated by different power laser parameters compared with photodynamic therapy on root canals infected with Enterococcus faecalis.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) is used as an adjunct to endodontic treatment to enhance microbial reduction in the root canal system. However, studies evaluating the impact of laser ablation with Indocyanine Green (ICG) are scarce. Thus, this in vitro study aimed to evaluate the efficiency of laser ablation with ICG using different laser parameters compared with aPDT using photosensitizer methylene blue (MB) and curcumin (CUR) on the reduction of E. faecalis biofilms on root canals. METHODS: Forty-nine human premolars were used after biomechanical instrumentation for standardization. The root canals were contaminated with E. faecalis for 10 days to form biofilms, and divided into 7 groups (n = 7): 0.01% MB activated by red laser - MB+RL; 0.05% CUR activated by blue LED - CUR+BL; 0.05% ICG activated by infrared diode laser (2.5 W power, 30 ms interval, and 30 ms duration) - ICG+DL 2.5/30/30; 0.05% ICG activated by infrared diode laser (2.5 W power, 300 ms interval, and 100 ms duration) - ICG+DL 2.5/300/100; 0.05% ICG activated by infrared diode laser (3 W power, 300 ms interval, and 100 ms duration) - ICG+DL 3/300/100; sterile saline solution (negative control) - NC; and 2.5% NaOCl (positive control) - PC. Root canal sampling was performed prior to and immediately after the different treatment protocols. Data were submitted to One- and Two-Way ANOVA, followed by Student-Newman-Keuls test or Fisher LSD's test (α = 0.05). RESULTS: All aPDT protocols promoted significant CFU reductions compared with the NC; the highest CFU reduction was observed for PC (p < 0.05). Among the protocols the highest CFU reduction was promoted by laser ablation with ICG+DL 3/300/100 (p < 0.05) except compared with aPDT using CUR+BL (p > 0.05). CONCLUSIONS: Laser ablation protocol using ICG+DL proved to be efficient in reducing E. faecalis biofilms, especially when activated at 3/300/100 configuration.

Oral prosthetic microbiology: aspects related to the oral microbiome, surface properties, and strategies for controlling biofilms.

The oral cavity is an environment that allows for the development of complex ecosystems; the placement of prosthetic devices as a consequence of partial or total tooth loss may alter the diversity of microbial communities. Biofilms on the surface of materials used in dental prostheses can promote important changes in the mechanic and aesthetic properties of the material itself and may cause local and systemic diseases for the prosthetic wearer. This review presents the main features of the oral microbiome associated with complete or partial dentures and dental implants. The main diseases associated with microbial colonization of prosthetic surfaces, factors that may affect biofilm formation on prosthetic materials, as well as novel alternative therapies aiming to reduce biofilm formation and/or to eradicate biofilms formed on these materials are also explored.

Estudo in vitro da influência de diferentes plugs coronários sobre o remanescente da obturação, após preparo para pino, na retenção de pinos metálicos fundidos / In vitro assessment of the influence of different protection plugs over obturation remnant space, after post preparation, on the retention of cast metal posts

Objetivo: Avaliar a influência de diferentes plugs de proteção, acomodados sobre o remanescente da obturação após preparo para pino, na retenção de pinos metálicos fundidos. Métodos: Cinquenta dentes bovinos foram decoronados, manualmente instrumentados até a lima manual Kerr #80 e obturados. A desobturação parcial de 10mm do conduto foi realizada com uma broca Largo e os grupos foram divididos de acordo com os diferentes materiais utilizados como plugs (n=10): Grupo I (Controle, sem plug); Grupo II (plug de Coltosol®); Grupo III (plug, em consistência de massa, de Sealapex® + óxido de zinco); Grupo IV (plug de etil-cianoacrilato); e Grupo V (plug de fosfato de zinco). Uma camada de 1mm de espessura dos diferentes plugs (Grupos II, III, IV ou V) foi acomodada sobre a obturação remanescente. Os espécimes foram selados e armazenados em 100% de umidade, por 7 dias. Após moldagem do conduto, foram confeccionados pinos metálicos fundidos e cimentados com fosfato de zinco. Os espécimes permaneceram em câmara úmida por 45 dias antes do teste de tração, realizado em uma máquina universal de ensaios. Os valores foram expressos em Mega pascal (MPa) e submetidos aos testes ANOVA e Tukey (p<0,05). Resultados: O etilcianoacrilato diminuiu a retenção dos pinos metálicos fundidos (p<0,01). Não houve diferença entre os outros grupos (p>0,05), semelhante- mente ao controle. Conclusão: A proteção da obturação com plugs confeccionados com etil-cianoacrilato prejudica a retenção de pinos metálicos fundidos cimentados com fosfato de zinco, enquanto Sealapex® acrescido de óxido de zinco, fosfato de zinco endurecido ou Coltosol® não interferem na adesividade (AU).

Comparative Analysis of the Proteomic Profile of the Dental Pulp in Different Conditions. A Pilot Study.

This study aimed to quantitatively compare the difference in protein expression in the progression of pulp pathogenesis, as well as to describe the biological functions of proteins identified in pulp tissue. Samples were obtained from six patients treated at the Araçatuba School of Dentistry and were divided into three groups: normal pulp - from teeth extracted for orthodontic indication; inflamed pulp and necrotic pulp - from patients diagnosed with irreversible pulpitis and chronic apical periodontitis, respectively. After previous proteomic preparation, dental pulp samples were processed for label-free quantitative proteomic analysis in a nanoACQUITY UPLC-Xevo QTof MS system. The difference in expression between the groups was calculated using the Protein Lynx Global Service software using the Monte Carlo algorithm. A total of 465 human proteins were identified in all groups. The most expressed proteins in the inflamed pulp group in relation to the normal pulp group were hemoglobin, peroxiredoxins and immunoglobulins, whereas the less expressed were the tubulins. Expression levels of albumins, immunoglobulins and alpha-2-macroglobulin were higher in the necrotic pulp group than in the inflamed pulp group. As for the qualitative analysis, the most prevalent protein functions in the normal pulp group were metabolic and energetic pathways; in the inflamed pulp group: cellular communication and signal transduction; and regulation and repair of DNA/RNA, while in the necrotic pulp group proteins were associated with the immune response. Thus, proteomic analysis showed quantitative and qualitative differences in protein expression in different types of pulp conditions.

Comparison of two rotary systems in bacteria/lps removal from endodontic infections: randomized clinical trial.

This clinical study compared the effectiveness of two rotary systems: HyFlex CM (Coltene-Whaledent, Altstetten, Switzerland) and ProTaper Next (Dentsply Sirona, Ballaigues, Switzerland) on the removal of cultivable bacteria and endotoxins from primarily infected root canals. This study was designed as a randomized single-blinded, 2-arm, clinical trial. Twenty-four primarily infected root canals were selected and randomly divided into 2 groups: HyFlex CM (n = 12); and ProTaper Next (n = 12). Samples were collected before and after the biomechanical preparation and inoculated in specific flasks. Irrigation was performed using 2.5% sodium hypochlorite. A kinetic turbidimetric lysate assay of limulus amoebocytes was used to quantify endotoxins. Microbiological culture technique was used to determine the count of bacterial colony forming units (CFU/mL). Data collected were statistically analyzed using SigmaPlot 12.0 for Windows. The Two-Way ANOVA statistical test was performed and the level of significance was 5%. In the samples before the biomechanical preparation, cultivable bacteria and endotoxins were evidenced in 100% of the cases. The culture analysis revealed that there was no statistically significant difference in the bacterial reduction between the two instrumentation systems. Endotoxins were present in 100% of the canals after instrumentation and there was no statistical difference between the two systems in endotoxin reduction. Thus, it was concluded that both instrumentation systems were effective in reducing root canal bacteria and endotoxins with primary endodontic infection and that there was no statistical difference between them. However, no system was able to eliminate 100% of the bacteria and their by-products.

Influence of curcumin photosensitizer in photodynamic therapy on the mechanical properties and push-out bond strength of glass-fiber posts to intraradicular dentin.

BACKGROUND: The effects of using curcumin as photosensitizer on the mechanical properties of intraradicular dentin and on the bond strength of glass-fiber posts are unknown. Thus, this in vitro study evaluated the influence of using curcumin as photosensitizer during photodynamic therapy on the Martens hardness, elastic modulus, and bond strength of glass-fiber posts luted to intraradicular dentin, in different tooth root thirds. METHODS: Eighty bovine teeth were divided into 5 groups according to the concentration of curcumin applied, with or without blue LED light activation: Control-deionized water; Curcumin 500 mg/L; Curcumin 500 mg/L + blue LED; Curcumin 1000 mg/L; and Curcumin 1000 mg/L + blue LED. Mechanical properties were measured in different thirds of the radicular dentin using an ultramicrohardness tester (n = 8). A universal testing machine was used to evaluate the push-out bond strength (n = 8). Mechanical properties were compared across groups with the Kruskal-Wallis test, and across regions with the Friedman test. Bond strength data were subjected to ANOVA, followed by Tukey's test (α = 0.05). Scanning electron microscopy was used to analyze the failure mode of the specimens. RESULTS: The use of curcumin photosensitizer, with or without blue LED light, improved mechanical properties compared to those of the control group (P < 0.05), and promote no statistically significant difference in bond strength values (P > 0.05). Overall, there was no difference among the intraradicular thirds for Martens hardness and push-out bond strength values (P > 0.05). CONCLUSIONS: Curcumin photosensitizer, with or without photodynamic therapy, changed the mechanical properties of intraradicular dentin; however, the Martens hardness and bond strength values did not differ with the depth of the dentin.

Omega 3 Fatty Acids Reduce the Triglyceride Levels in Rats with Apical Periodontitis.

The aim of this study was to evaluate the influence of the prophylactic and therapeutic supplementation with omega 3 polyunsaturated fatty acids (w-3 PUFAs) on the lipid profile and periapical bone resorption in rats with apical periodontitis. Forty male rats were divided into groups: control rats (C), rats treated with w-3 PUFAs (C+O), rats with pulp exposure-induced apical periodontitis (AP), and rats with AP treated with w-3 PUFAs (AP+O). The administration of w-3 PUFAs was carried out orally once a day for 15 days before pulp exposure and, subsequently, for an additional 30 days after pulp exposure. AP was induced by exposing pulpal tissues to the oral environment. The samples were collected after 30 days. Triglycerides and cholesterol levels were enzymatically measured using the Trinder method. The jaws were collected and submitted for histological analysis. Two-way analysis of variance and Kruskal-Wallis tests were used for statistical analysis, and the significance was set at p<0.05. The triglyceride levels of the AP group were significantly higher than those of the C, C+O and AP+O groups (p<0.05). However, the difference in the cholesterol levels among the groups was not significant (p>0.05). Rats with AP showed larger areas of bone resorption as well as higher inflammatory intensity compared with rats with AP supplemented with w-3 PUFAs. It may be concluded that the presence of multiple AP foci increased the triglyceride levels. In addition, omega 3 supplementation might reduce these levels in rats with AP, as well as the bone resorption areas of periapical tissues.

Omega 3 fatty acids reduce the triglyceride levels in rats with apical periodontitis

Abstract The aim of this study was to evaluate the influence of the prophylactic and therapeutic supplementation with omega 3 polyunsaturated fatty acids (w-3 PUFAs) on the lipid profile and periapical bone resorption in rats with apical periodontitis. Forty male rats were divided into groups: control rats (C), rats treated with w-3 PUFAs (C+O), rats with pulp exposure-induced apical periodontitis (AP), and rats with AP treated with w-3 PUFAs (AP+O). The administration of w-3 PUFAs was carried out orally once a day for 15 days before pulp exposure and, subsequently, for an additional 30 days after pulp exposure. AP was induced by exposing pulpal tissues to the oral environment. The samples were collected after 30 days. Triglycerides and cholesterol levels were enzymatically measured using the Trinder method. The jaws were collected and submitted for histological analysis. Two-way analysis of variance and Kruskal-Wallis tests were used for statistical analysis, and the significance was set at p<0.05. The triglyceride levels of the AP group were significantly higher than those of the C, C+O and AP+O groups (p<0.05). However, the difference in the cholesterol levels among the groups was not significant (p>0.05). Rats with AP showed larger areas of bone resorption as well as higher inflammatory intensity compared with rats with AP supplemented with w-3 PUFAs. It may be concluded that the presence of multiple AP foci increased the triglyceride levels. In addition, omega 3 supplementation might reduce these levels in rats with AP, as well as the bone resorption areas of periapical tissues.

Resumo O objetivo deste estudo foi avaliar a influência da suplementação profilática e terapêutica com os ácidos graxos ômega-3 no perfil lipídico e na reabsorção óssea, em ratos com periodontite apical. Quarenta ratos machos foram divididos em grupos: ratos controle (C), ratos tratados com ácidos graxos ômega-3 (C+O), ratos com periodontite apical induzida por meio de exposição pulpar (PA), ratos com PA tratados com ácidos graxos ômega-3 (PA+O). A administração do ômega-3 foi realizada oralmente, uma vez ao dia durante 15 antes da exposição pulpar e, subsequentemente, por mais 30 dias depois da exposição pulpar. A PA foi induzida por meio da exposição do tecido pulpar ao ambiente oral. Após 30 dias, os ratos foram mortos e os níveis de triglicérides e colesterol foram mensurados pelo método enzimático de Trinder. As mandíbulas foram coletadas e submetidas à análise histológica. Análise de variância de dois fatores e teste de Kruskal-Wallis foram utilizados para análise estatística, e o nível de significância foi de p < 0,05. Os níveis de triglicérides do grupo PA foram significativamente maiores que dos grupos C, C+O e PA+O (p<0,05). Entretanto, não houve diferença significativa nos níveis de colesterol entre os grupos (p>0,05). Ratos com PA apresentaram maior área de reabsorção óssea bem como maior intensidade no infiltrado inflamatório comparados aos ratos com PA suplementados com ômega-3. Pode-se concluir que a presença de múltiplos focos de PA aumentou os níveis de triglicérides. Além disso, a suplementação com ômega-3 pode reduzir estes níveis em ratos com PA, bem como a área de reabsorção óssea dos tecidos periapicais.

Mixing failures of endodontic sealers: an in vivo biocompatibility study / Falhas durante espatulação de cimentos endodônticos: um estudo de biocompatibilidade in vivo

Objectives: Evaluate, in vivo, the influence of mixing failures on endodontic sealers. Material and Methods: To alveolus analysis, 80 rats were divided into Sealapex® and AH Plus® groups. Within each group, the sealer was subjected to either partial (incomplete homogenization­ simulating handling failures) or total mixing (complete homogenization) over two periods of 7 and 30 days (n = 20). The maxillary incisor was extracted and a polyethylene tube containing the sealer was inserted. To quantify edema, 40 male rats were divided into four groups (n = 10). The animals received 2% Evans Blue intravenously, and either AH Plus® or Sealapex® was injected subcutaneously. The rats were euthanized after 3 or 6 hours and analyzed in a spectrophotometer (630 ƞm). To analyze the subcutaneous tissue, 20 rats received polyethylene tube implants with the sealers in the dorsal area (n=10), then euthanized after either 7 or 30 days, and inflammation was evaluated according to an inflammatory cells score. Results: In the alveolar 7-day group, control group presented an inflammation score 1, while all other groups presented a score 2, except AH plus® total mix group (3). After 30 days, all groups presented a score 1. The edemogenic test showed less edema in Sealapex® groups (p < 0.5). In subcutaneous 7-day period, all groups presented score 2. In 30 days, all groups revealed score 1, except AH Plus® partial mix group (2). Conclusion: Regarding mixing of the sealers, there were no significant differences among the groups (AU)

Objetivo: Avaliar, in vivo, a influência das falhas de espatulação de cimentos endodônticos. Material e Métodos: Para análise alveolar, 80 ratos foram divididos nos grupos Sealapex® e AH Plus®. Em cada grupo, o cimento foi espatulado de forma parcial (homogeneização incompleta, simulando falhas) ou total (homogeneização completa) em dois períodos de 7 e 30 dias (n=20). O incisivo superior foi extraído e um tubo de polietileno contendo o cimento foi inserido. Para quantificar edema, 40 ratos foram divididos em quatro grupos (n = 10). Os animais receberam Azul de Evans 2% intravenoso, e AH Plus® ou Sealapex® injetados no tecido subcutâneo. Após 3 ou 6 horas foram eutanasiados e analisados em espectrofotômetro (630 ƞm). Para analisar a resposta subcutânea, 20 ratos receberam implantes de tubo de polietileno com os cimentos na região dorsal (n = 10), eutanasiados após 7 ou 30 dias, e a inflamação foi avaliada de acordo com um escore de células inflamatórias. Resultados: Na análise alveolar em 7 dias, o grupo controle apresentou escore 1 de inflamação, enquanto que todos os outros grupos apresentaram 2, com exceção do AH plus® espatulação total (3). Após 30 dias, todos os grupos apresentaram escore 1. O teste edemogênico mostrou menor edema nos grupos Sealapex® (p < 0,5). No período subcutâneo de 7 dias, todos os grupos apresentaram escore 2. Em 30 dias, todos os grupos revelaram escore 1, exceto AH Plus® espatulação parcial (2). Conclusão: Não houve diferença estatística significante entre os cimentos quanto à espatulação. (AU)

Evaluation of an experimental rat model for comparative studies of bleaching agents.

Dental materials in general are tested in different animal models prior to the clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents, by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats' vital teeth. Material and Methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals were untreated (control). The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated through histomorphometric analysis with inflammatory cell count in the coronal and radicular thirds of the pulp. Fibroblasts were also counted. Scores were attributed to odontoblastic layer and vascular changes. Tertiary dentin area and pulp chamber central area were measured histomorphometrically. Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the coronal pulp occlusal third up to the 15-min application groups of each bleaching gel. In the groups exposed to each concentration for 30 and 45 min, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, reduction on the pulp chamber central area and enlargement of the tertiary dentin area were observed, without the detection of inflammation areas. Conclusion The rat model of extracoronal bleaching showed to be adequate for studies of bleaching protocols, as it was possible to observe alterations in the pulp tissues and tooth structure caused by different concentrations and application periods of bleaching agents.

Evaluation of an experimental rat model for comparative studies of bleaching agents

ABSTRACT Dental materials in general are tested in different animal models prior to the clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents, by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and Methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals were untreated (control). The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated through histomorphometric analysis with inflammatory cell count in the coronal and radicular thirds of the pulp. Fibroblasts were also counted. Scores were attributed to odontoblastic layer and vascular changes. Tertiary dentin area and pulp chamber central area were measured histomorphometrically. Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the coronal pulp occlusal third up to the 15-min application groups of each bleaching gel. In the groups exposed to each concentration for 30 and 45 min, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, reduction on the pulp chamber central area and enlargement of the tertiary dentin area were observed, without the detection of inflammation areas. Conclusion The rat model of extracoronal bleaching showed to be adequate for studies of bleaching protocols, as it was possible to observe alterations in the pulp tissues and tooth structure caused by different concentrations and application periods of bleaching agents.

Evaluation of an experimental rat model for comparative studies of bleaching agents.

UNLABELLED: Dental materials, in general, are tested in different animal models prior to their clinical use in humans, except for bleaching agents. OBJECTIVES: To evaluate an experimental rat model for comparative studies of bleaching agents by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats' vital teeth. MATERIAL AND METHODS: The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals (control) were untreated. The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated by histomorphometric analysis with inflammatory cell counting in the coronal and radicular thirds of the pulp. The counting of fibroblasts was also performed. Scores were attributed to the odontoblastic layer and to vascular changes. The tertiary dentin area and the pulp chamber central area were histomorphometrically measured. Data were compared by the analysis of variance and the Kruskal-Wallis test (p<0.05). RESULTS: After 2 days, the amount of inflammatory cells increased in the occlusal third of the coronal pulp until the time of 15 min for both concentrations of bleaching gels. In 30 and 45 min groups of each concentration, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, a reduction in the pulp chamber central area and an enlargement of tertiary dentin area were observed without the detection of inflammation areas. CONCLUSION: The rat model of extra coronal bleaching showed to be adequate for bleaching protocols studies, as it was possible to observe alterations in the pulp tissues and in the tooth structure caused by different concentrations and periods of application of bleaching agents.

Evaluation of an experimental rat model for comparative studies of bleaching agents

ABSTRACT Dental materials, in general, are tested in different animal models prior to their clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals (control) were untreated. The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated by histomorphometric analysis with inflammatory cell counting in the coronal and radicular thirds of the pulp. The counting of fibroblasts was also performed. Scores were attributed to the odontoblastic layer and to vascular changes. The tertiary dentin area and the pulp chamber central area were histomorphometrically measured. Data were compared by the analysis of variance and the Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the occlusal third of the coronal pulp until the time of 15 min for both concentrations of bleaching gels. In 30 and 45 min groups of each concentration, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, a reduction in the pulp chamber central area and an enlargement of tertiary dentin area were observed without the detection of inflammation areas. Conclusion The rat model of extra coronal bleaching showed to be adequate for bleaching protocols studies, as it was possible to observe alterations in the pulp tissues and in the tooth structure caused by different concentrations and periods of application of bleaching agents.

Effect of a surfactant on the antimicrobial activity of sodium hypochlorite solutions.

The objective of the present study was to evaluate the antimicrobial activity of sodium hypochlorite (NaOCl) associated with a surfactant. Seventy single-rooted extracted human teeth were inoculated with Enterococcus faecalis, and incubated for 21 days (37 °C). The groups were distributed according to the irrigation solution used during root canal preparation: 5%, 2.5% and 1% NaOCl; 5%, 2.5% and 1% Hypoclean®, a solution containing a surfactant (cetrimide) associated with NaOCl. Three microbiological samples were collected from each tooth: S1 - before instrumentation; S2 - immediately after instrumentation; and S3 - after a seven-day period. Data were submitted to ANOVA and Tukey test with 5% significance level. The results showed that immediately after root canal preparation (S2), E. faecalis was eliminated in all the experimental groups. However, after 7 days (S3), only the groups in which Hypoclean was used, remained contamination-free, including Hypoclean associated with 1% NaOCl, while the root canals irrigated with 1% NaOCl only, presented the highest percentage of bacterial growth. In conclusion, the addition of surfactant increased the antimicrobial activity of 1% NaOCl to levels similar to 5% NaOCl.

Effect of a Surfactant on the Antimicrobial Activity of Sodium Hypochlorite Solutions

The objective of the present study was to evaluate the antimicrobial activity of sodium hypochlorite (NaOCl) associated with a surfactant. Seventy single-rooted extracted human teeth were inoculated with Enterococcus faecalis, and incubated for 21 days (37 °C). The groups were distributed according to the irrigation solution used during root canal preparation: 5%, 2.5% and 1% NaOCl; 5%, 2.5% and 1% Hypoclean(r), a solution containing a surfactant (cetrimide) associated with NaOCl. Three microbiological samples were collected from each tooth: S1 - before instrumentation; S2 - immediately after instrumentation; and S3 - after a seven-day period. Data were submitted to ANOVA and Tukey test with 5% significance level. The results showed that immediately after root canal preparation (S2), E. faecalis was eliminated in all the experimental groups. However, after 7 days (S3), only the groups in which Hypoclean was used, remained contamination-free, including Hypoclean associated with 1% NaOCl, while the root canals irrigated with 1% NaOCl only, presented the highest percentage of bacterial growth. In conclusion, the addition of surfactant increased the antimicrobial activity of 1% NaOCl to levels similar to 5% NaOCl.

O objetivo da presente pesquisa foi avaliar a atividade antimicrobiana de hipoclorito de sódio (NaOCl), associado a um tensoativo. Setenta dentes humanos monorradiculares extraídos foram inoculados com Enterococcus faecalis e incubados durante 21 dias (37 °C). Os grupos foram distribuídos de acordo com a solução irrigadora utilizada no preparo do canal: hipoclorito de sódio a 5%, 2,5% e 1%; Hypoclean(r) a 5%, 2,5% e 1% - uma solução contendo um surfactante (cetrimida) associado com NaOCl. Três amostras microbiológicas foram coletadas de cada dente: S1 - antes de instrumentação; S2 - imediatamente após a instrumentação; e S3 - após um período de sete dias. Os dados foram submetidos à análise de variância e teste de Tukey com 5% de nível de significância. Os resultados mostraram que imediatamente após o preparo do canal radicular (S2), o E. faecalis foi eliminado em todos os grupos experimentais. No entanto, após 7 dias (S3), apenas os grupos em que se utilizou Hypoclean permaneceram livres de contaminação, incluindo Hypoclean 1%, enquanto que os canais radiculares irrigados apenas com hipoclorito de sódio 1% apresentaram a mais elevada percentagem de crescimento bacteriano. Em conclusão, a adição de surfactante aumentou a atividade antimicrobiana de 1% de NaOCl a níveis semelhantes aos do NaOCl 5% .

Cast metal vs. glass fibre posts: a randomized controlled trial with up to 3 years of follow up.

OBJECTIVE: This randomized controlled trial compared the survival of glass fibre and cast metal dental posts used to restore endodontically treated teeth with no remaining coronal wall. METHODS: Fifty-four participants (45 women) and 72 teeth were evaluated during a follow-up period of up to 3 years. Teeth were randomly allocated to the glass-fibre and cast-metal post groups. All teeth were restored with single metal-ceramic crowns. Survival probabilities were analyzed using Kaplan-Meier statistics (p≤0.05). RESULTS: The 3-year recall rate was 92.3% and the survival rates of glass fibre and cast metal posts were similar (97.1% and 91.9%, respectively; p=0.682). Four failures were observed: two glass fibre posts in a premolar and anterior tooth debonded, one glass fibre post in a premolar debonded in association with root fracture, and one root fracture occurred in a molar with a cast metal post. CONCLUSIONS: Glass fibre and cast metal posts showed similar clinical performance in teeth with no remaining coronal wall after 3 years. CLINICAL SIGNIFICANCE: Posts are used to restore most endodontically treated teeth with no remaining coronal wall. This randomized controlled trial, one of few to compare glass fibre and cast metal posts in such teeth, showed that post type did not significantly influence the survival of restorations. These results can help dentists respond to the important question of how best to rehabilitate endodontically treated teeth with no remaining coronal wall.

Avaliação da infiltração marginal de três cimentos endodônticos após preparo para retentor de acordo com o momento do preparo

Objetivo: o objetivo desse estudo in vitro foi avaliar a infiltração marginal coronária após o preparo para retentor em dentes obturados com três diferentes cimentos,de acordo com o período entre a obturação do canal radicular e o preparo para retentor. Métodos: Noventa dentes humanos recentemente extraídos foram limpos e instrumentados e, então, obturados com Sealapex, Endométhasone ou TopSeal. Brocas Gates-Glidden foram utilizadas para o preparo imediato de 10 dentes de cada cimento até manter 5mm de obturação remanescente.Sessenta raízes obturadas foram incubadas a 37°C emmeio úmido por 30 e 60 dias para serem, depois, preparadas para os retentores como descrito anteriormente.A superfície externa de cada raiz foi coberta com Araldite. Os espécimes foram imersos em corante azul de metileno a 2% sob vácuo por 24h, para então poderem ser analisados. A infiltração foi mensurada pelo software Sigma Scan da parte superior da obturação à porção apical alcançada pelo corante. Resultado: o Sealapexe o TopSeal apresentaram menor infiltração após o preparo para retentor do que o Endométhasone. O preparo imediato para o retentor apresentou menor infiltração do que o preparo para o retentor após 30 e 60 dias da obturação do canal radicular