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Dental tissue stem cells (DTSCs) are well known for their multipotent capacity and regenerative potential. They also play an important role in the immune response of inflammatory processes derived from caries lesions, periodontitis, and gingivitis. These oral diseases are triggered by toxins known as lipopolysaccharides (LPS) produced by gram-negative bacteria. LPS present molecular patterns associated with pathogens and are recognized by Toll-like receptors (TLRs) in dental stem cells. In this review, we describe the effect of LPS on the biological behavior of DTSCs. We also focus on the molecular sensors, signaling pathways, and emerging players participating in the interaction of DTSCs with lipopolysaccharides. Although the scientific advances generated provide an understanding of the immunomodulatory potential of DTSCs, there are still new reflections to explore with regard to their clinical application in the treatment of oral inflammatory diseases.

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The dental pulp can be affected by thermal, physical, chemical, and bacterial phenomena that stimulate the inflammatory response. The pulp tissue produces an immunological, cellular, and vascular reaction in an attempt to defend itself and resolve the affected tissue. The expression of different microRNAs during pulp inflammation has been previously documented. MicroRNAs (miRNAs) are endogenous small molecules involved in the transcription of genes that regulate the immune system and the inflammatory response. They are present in cellular and physiological functions, as well as in the pathogenesis of human diseases, becoming potential biomarkers for diagnosis, prognosis, monitoring, and safety. Previous studies have evidenced the different roles played by miRNAs in proinflammatory, anti-inflammatory, and immunological phenomena in the dental pulp, highlighting specific key functions of pulp pathology. This systematized review aims to provide an understanding of the role of the different microRNAs detected in the pulp and their effects on the expression of the different target genes that are involved during pulp inflammation.

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The aims of this study were to investigate if Toll-like receptor 4 (TLR4) is expressed in the medullary dorsal horn (MDH) and if medullary application of a TLR4 antagonist (lipopolysaccharides from Rhodobacter sphaeroides, LPS-RS) can attenuate changes in nociceptive sensorimotor responses or TLR4 expression that might be evoked by mustard oil (MO) application to the right maxillary first molar tooth pulp. Of 41 adult male Sprague-Dawley rats used in the study, 23 received intrathecal application of the TLR4 antagonist LPS-RS (25 µg/10 µl; LPS-RS group) or isotonic saline (10 µl; vehicle control group) 10 min before pulpal application of MO (95%; 0.2 µl). Bilateral electromyographic (EMG) activities of the anterior digastric and masseter muscles were recorded continuously before and until 15 min after the MO application to the pulp. In 6 of these 23 rats and an additional 18 rats, the caudal medulla containing the ipsilateral and contralateral MDH was removed after euthanasia for subsequent Western Blot analysis of TLR4 expression in LPS-RS (n = 8) and vehicle (n = 8) groups and a naïve group (n = 8). The % change from baseline in the MO-evoked EMG activities within the anterior digastric muscles were significantly smaller in the LPS-RS group than the control group (two-way ANOVA, post hoc Bonferroni, P < 0.0001). Western Blot analysis revealed similar levels of TLR4 expression in the caudal medulla of the naïve, vehicle and LPS-RS groups. These novel findings suggest that TLR4 signaling in the caudal medulla may mediate MO-induced acute dental inflammatory pain in rats.

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OBJECTIVES: MI Paste Plus remineralizer (Rem) strengthens dental structures after bleaching. We investigated the effect of Rem on the penetration of hydrogen peroxide (H2O2), bleaching effectiveness, and pulp inflammation after bleaching. MATERIALS AND METHODS: Bovine disks were grouped as follows (n = 10): control (untreated), bleached (Ble; 35% H2O2, 30 min), Ble-Rem (H2O2 followed by Rem, 30 min), Rem-Ble (Rem followed by H2O2), Rem-Ble-Rem (Rem before and after H2O2), and Ble+Rem (mixture of Rem with H2O2, 1:1, 30 min). The penetration of H2O2 was quantified and bleaching efficacy was analyzed. Upper rat molars (n = 10) received the same treatments at random. The rats were euthanized after two days and 30 days, and their jaws were removed for histological analysis. Statistical tests were performed (P < 0.05). RESULTS: The bleached groups, except Ble+Rem (P > 0.05), showed significant H2O2 penetration compared with control (P < 0.05). Color alteration analysis showed that ΔL and ΔE were significantly higher in the bleached groups than those in control (P < 0.05); the Δb of the bleached groups differed from that of control at 24 h (P < 0.05). At two days, necrosis or inflammation was observed in the bleached groups compared with control (P < 0.05), except Ble+Rem, which was similar to control (P > 0.05). At 30 days, tertiary dentin formation was significant in the bleached groups (P < 0.05), except Ble+Rem (P > 0.05). CONCLUSION: The mixture of MI Paste Plus and bleaching gel reduces H2O2 penetration and pulp damage and maintains bleaching effectiveness. CLINICAL RELEVANCE: Because bleaching can damage dental tissues, we studied a new bleaching protocol that reduces damage to the pulp tissue while maintaining bleaching efficiency: a single application of 30 min of MI Paste Plus mixed with 35% H2O2 bleaching gel (1:1).

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Introdução: O uso do laser infravermelho (LIV) através da fotobiomodulação, tem demonstrado efeitos benéficos aos tecidos. Objetivos: Avaliar a influência do LIV sobre o processo inflamatório, por meio da imunomarcação da interleucina próinflamatória IL-23, e sobre a angiogênese, por meio da imunomarcação do fator induzível por hipóxia-1 alfa (HIF-1α), no tecido pulpar de dentes clareados. Materiais e métodos: Quarenta ratos Wistar foram distribuídos aleatoriamente em 4 grupos de 20 hemi-maxilas cada: Grupo Controle ­ recebeu o tratamento com o gel placebo; Grupo Cla - recebeu 30 minutos do gel clareador H2O2 a 35%; Grupo LIV ­ recebeu uma aplicação de LIV (808 nm, 30 segundos, 3J); Grupo Cla-LIV ­ imediatamente após a aplicação do H2O2 a 35%, recebeu uma aplicação de LIV, como descrito no grupo LIV. Após 2 e 30 dias (n = 10), os animais foram eutanasiados e as maxilas removidas e processadas para avaliação histológica (H.E.) e imunoistoquímica. Forma de análise: Os cortes teciduais seriados e com espessura de 5 µm corados em H.E. foram avaliados por escores atribuídos à inflamação, e a análise imunoistoquímica foi realizada através de escores atribuídos à imunomarcação. Os dados foram submetidos aos testes de Wilcoxon e Mann Whitney (p < 0,05). Resultados: Aos 2 dias, houve inflamação severa e necrose nos terços oclusal e médio do tecido pulpar no grupo Cla, diferente do grupo Cla-LIV com inflamação leve à moderada (p < 0,05). No terço cervical, houve inflamação moderada a severa no grupo Cla, e leve no grupo Cla-LIV (p < 0,05). Aos 30 dias, houve ausência de inflamação e os grupos clareados apresentaram deposição de dentina terciária. Em relação à IL-23, aos 2 dias foi observada imunomarcação severa no grupo Cla e moderada no grupo Cla-LIV (p < 0,05); aos 30 dias, houve redução na imunomarcação de IL-23 nos grupos clareados, onde o grupo Cla apresentou imunomarcação moderada, e o grupo Cla-LIV leve imunomarcação, sem diferença significante (p > 0,05). HIF-1α foi mais presente aos 2 dias no grupo Cla, sem diferença significativa com Cla-LIV (p > 0,05). Foi observada diferença entre os grupos clareados e seus respectivos controles, que não apresentaram imunomarcação (p < 0,05); aos 30 dias, o grupo Cla apresentou redução na imunomarcação para HIF-1α, enquanto o grupo Cla-LIV apresentou aumento da imunomarcação, mas a diferença permaneceu apenas entre os grupos clareados e seus controles (p > 0,05). Conclusão: O laser infravermelho minimizou o infiltrado inflamatório e a imunomarcação de IL-23 no tecido pulpar após a clareação dentária, mas não influenciou a imunomarcação de HIF-1α(AU)

Introduction: The use of infrared laser (IRL) through photobiomodulation has shown beneficial effects on tissues. Objectives: To evaluate the influence of LLL on the inflammatory process, by immunolabeling IL-23 pro-inflammatory interleukin, and on angiogenesis, by immunolabeling hif-1 alpha inducible factor (HIF-1α) in the pulp tissue of bleached teeth (HIF-1α). Materials and methods: Forty Wistar rats were randomly divided into 4 groups of 20 hemimaxilla each: control group - received treatment with placebo gel; Ble group - received 30 minutes of 35% H2O2 bleaching gel; IRL group - received one application of IRL (808 nm, 30 seconds, 3 J); Ble-IRL group - immediately after application of 35% H2O2, received an application of IRL, as described in the IRL group.. After 2 and 30 days (n = 10), the rats were euthanized and the jaws removed and processed for histological evaluation (H.E.) and immunohistochemistry. Form of analysis: Serial tissue sections with thickness of 5 µm stained in H.E. were evaluated by scores attributed to inflammation, and immunohistochemical analysis was performed by scores attributed to immunolabeling. The data were submitted to the Wilcoxon and Mann Whitney tests (P < 0.05). Results: At 2 days, there was a severe inflammation and the presence of necrosis in the occlusal and middle thirds of the pulp tissue in the Ble group, different compared to the Ble-IRL group with moderate to mild inflammation (P < 0.05). In the cervical third, there was moderate to severe inflammation in the Ble group, and mild in the Ble-IRL group (P < 0.05). At 30 days, there was absence of inflammation and bleached groups had an extensive deposition of tertiary dentin. Regarding IL-23, at 2 days was observed severe immunolabeling in the Ble group and moderate in the Ble-IRL group (P < 0.05); at 30 days, there was a reduction in IL-23 immunolabeling in the bleached groups, where Ble group had moderate immunolabeling, and Ble-IRL group had mild immunolabeling, without significant difference (P > 0.05). HIF-1α was more evident at 2 days in the Ble group, without significant difference with Ble-IRL (P > 0.05). The difference was observed between the bleached groups and their respective controls, which had no immunolabeling (P < 0.05); at 30 days, the Ble group had a reduction in HIF-1α immunolabeling, while the Ble-IRL group had an increase in immunolabeling from moderate to severe; however, the difference remained only between the bleached groups and their controls (P > 0.05). Conclusion: Infrared laser minimized the inflammatory infiltrate and IL-23 immunolabeling in the pulp tissue after dental bleaching, but did not influenced HIF-1α immunolabeling(AU)

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ABSTRACT Objective: This study investigated the presence of inflammatory response in the dental pulp of rats showing hypersensitive dentin, induced by erosive episodes. Methods: Sixteen Wistar rats were fed with commercial sucrose-free pellet diet for 12 hours; whereas the food was removed during the remainder of the day, and the animals received mineral water or a lemon-based sucrose-free soft drink, according to the group to which they belonged. Eight animals consumed the soft drink to induce hypersensitivity, while the other 8 animals received mineral water (control). After six weeks, the animals were euthanized, the mandible was removed and subjected to a median incision in the sagittal plane, to obtain right and left hemimandibles. The slides stained with hematoxylin-eosin were analyzed using light microscopy. Results: Histological evaluation of the control and experimental groups revealed no inflammatory process in the pulp tissue, and the presence of inflammatory cells, such as lymphocytes, plasma cells, eosinophils and macrophages, was not observed. In addition, there was no edema or dilated and congested blood vessels. The Mann-Whitney test showed no significant difference (p = 1.000) between the experimental and the control groups. Conclusion: In the animal model used, dentin hypersensitivity does not trigger dental pulp inflammatory response.

RESUMO Objetivo: Este estudo investigou a presença de resposta inflamatória na polpa dentária de ratos apresentando hipersensibilidade dentinária induzida por episódios erosivos. Métodos: Dezesseis ratos Wistar foram alimentados com ração peletizada isenta de sacarose por 12 horas; enquanto a dieta estava ausente no restante do período diário, os animais receberam água mineral ou um refrigerante dietético à base de limão, de acordo com o grupo ao qual pertenciam. Oito animais consumiram o refrigerante para a indução do quadro de hipersensibilidade, enquanto os demais receberam água mineral (controle). Após seis semanas, realizou-se a eutanásia dos animais, os quais tiveram suas mandíbulas removidas e seccionadas medialmente no plano sagital, a fim de serem obtidas hemimandíbulas direita e esquerda. Lâminas coradas com hematoxilina-eosina foram analisadas sob microscopia óptica. Resultados: A avaliação histológica dos grupos controle e experimental revelou ausência de processo inflamatório no tecido pulpar e também não foi observada a presença de células inflamatórias como linfócitos, plasmócitos, eosinófilos ou macrófagos. Em adição, não houve edema ou vasos sanguíneos dilatados e congestos. O teste de Mann-Whitney demonstrou inexistência de diferença significativa (p = 1,000) entre os grupos experimental e controle. Conclusão: No modelo animal adotado, a hipersensibilidade dentinária não desencadeou resposta inflamatória na polpa dentária.

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OBJECTIVES: This systematic review (PROSPERO register: CRD42016053140) investigated the influence of different types of light on the pulp tissue during dental bleaching. MATERIALS AND METHODS: Two independent authors conducted a systematic search and risk of bias evaluations. An electronic search was undertaken (PubMed/Medline, Embase, The Cochrane Library, and other databases) until May 2017. The population, intervention, comparison, outcomes (PICO) question was: "Does the light in dental bleaching change the response of the pulp to the bleaching procedure?" The intervention involved pulp tissue/cells after bleaching with light, while the comparison involved pulp tissue/cells after bleaching without light. The primary outcome was the inflammation/cytotoxicity observed in pulp after bleaching. RESULTS: Out of 2210 articles found, 12 articles were included in the review; four were in vivo studies (one study in dogs/others in human), and eight were in vitro studies (cell culture/with artificial pulp chamber or not). The light source used was halogen, light-emitting diode (LED), and laser. Only one in vivo study that used heat to simulate light effects showed significant pulp inflammation. Only two in vitro studies demonstrated that light influenced cell metabolism; one using halogen light indicated negative effects, and the other using laser therapy indicated positive effects. Given that animal and in vitro studies have been identified, there remain some limitations for extrapolation to the human situation. Furthermore, different light parameters were used. CONCLUSIONS: The effects of dental bleaching on the pulp are not influenced by different types of light, but different light parameters can influence these properties. CLINICAL RELEVANCE: There is insufficient evidence about the influence of different types of light on inflammation/cytotoxicity of the pulp.

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Introducción: la mayoría de las urgencias estomatológicas se debe a enfermedades pulpares y periapicales. En nuestro país son pocos los estudios realizados en relación con la prevalencia de estas lesiones en la población, lo que motivó la realización de este trabajo. Objetivo: determinar el comportamiento de las lesiones pulpares y periapicales en pacientes de 19 a 59 años. Material y Método: se realizó un estudio descriptivo y transversal a pacientes comprendidos entre 19 y 59 años de edad quienes asistieron a la consulta de Urgencia Estomatológica de la clínica "Felipe Soto", del municipio Boyeros, de febrero del 2010 a junio del 2011. El universo fue de 250 pacientes a los que se realizó un examen clínico-estomatológico, de los cuales solo 154 presentaron este tipo de lesiones; se analizaron variables como edad, sexo, grupo dentario y causa de la enfermedad. Resultados: el grupo dentario más afectado fue el de los molares, la caries dental fue la principal causa relacionada con la aparición de dichas patologías. Conclusiones: el sexo femenino fue el predominante y el grupo de edad más afectado fue el de 19-34 años, el grupo dentario más afectado por lesiones pulpares y periapicales fue el de los molares, seguido de las bicúspides y las principales causas relacionadas con la aparición de estas enfermedades fueron la caries dental y las obturaciones defectuosas.

Introduction: most of emergency in the Cuban stomatological clinics are due to dental pulp diseases. In our country, there are only a few studies performed on this topic in relation to the prevalence of these injuries in the population. That's why we were motivated to work on this matter. Objective: to determine pulp and periapical lesions conduct in patients from 19 to 59 years old. Material and Methods: a descriptive and cross-sectional study was done in patients between 19 and 59 years old who attended to stomatological emergency services at "Felipe Soto" clinic from Boyeros Municipality, from February 2010 to June 2011. A stomatological clinical exam was done to a population of 250 patients and the sample was of 154 patients who presented dental pulp injuries, some variables were analyzed such as age, sex, dental group and causes of the disease. Results: the more affected teeth groups were the molars. As identified causes, the dental caries were the main related to the appearance of these pathologies. Conclusions: female sex predominant and the most affected age group was the one between 19 and 34 years old. The most affected dental group due to pulp and periapical lesions was that of molars fallowed by bicuspids and the main causes related to the appearing of these sicknesses were dental caries and faulty obturations.

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ABSTRACT Objective: The aim of this study was to compare the production of the chemokines CCL3 and CXCL12 by cultured dental pulp fibroblasts from permanent (PDPF) and deciduous (DDPF) teeth under stimulation by Porphyromonas gingivalis LPS (PgLPS). Material and Methods: Primary culture of fibroblasts from permanent (n=3) and deciduous (n=2) teeth were established using an explant technique. After the fourth passage, fibroblasts were stimulated by increasing concentrations of PgLPS (0 – 10 µg/mL) at 1, 6 and 24 h. The cells were tested for viability through MTT assay, and production of the chemokines CCL3 and CXCL12 was determined through ELISA. Comparisons among samples were performed using One-way ANOVA for MTT assay and Two-way ANOVA for ELISA results. Results: Cell viability was not affected by the antigen after 24 h of stimulation. PgLPS induced the production of CCL3 by dental pulp fibroblasts at similar levels for both permanent and deciduous pulp fibroblasts. Production of CXCL12, however, was significantly higher for PDPF than DDPF at 1 and 6 h. PgLPS, in turn, downregulated the production of CXCL12 by PDPF but not by DDPF. Conclusion: These data suggest that dental pulp fibroblasts from permanent and deciduous teeth may present a differential behavior under PgLPS stimulation. .

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