Inflammatory profile of apical periodontitis exacerbated by cigarette smoke inhalation: Histological and immunohistochemical analysis in rats.

AIM: The aim of this study was to evaluate the effects of cigarette smoke inhalation (CSI) on inflammation, pro-inflammatory mediators and haematological parameters in rats with induced apical periodontitis (AP). METHODOLOGY: Thirty-two 3-month-old male Wistar rats were divided into four experimental groups (n = 8): C-Control; S-rats with CSI; AP-rats with AP; and SAP-rats with CSI + AP. Animals in groups S and SAP inhaled cigarette smoke by remaining inside a smoking chamber for 8 min, three times daily, for 50 days. After 20 days of smoke inhalation, animals in AP and SAP groups had the pulps of the lower right first molar exposed to oral environment for 30 days to induce AP. In these subsequent 30 days, animals in group S and SAP continued with CSI. On Day 50, animals were euthanized and mandibles were histologically processed to assess inflammatory infiltrate, immunohistochemical interleukins (IL-1ß, IL-6 and TNF-α), and blood samples collected for laboratory analysis. The Mann-Whitney test was performed for non-parametric data and the pairwise analyses of Student's t-test for parametric data, with a significance level of p < .050. RESULTS: Inflammatory infiltrate was moderate in AP group and more severe in the SAP (p = .010). The interleukins IL-6, IL-1ß and TNF-α were higher in SAP group (p < .001) when compared to the AP group. A greater number of red blood cells (p = .010), haemoglobin (p = .007) and neutrophils (p = .014) were observed in the SAP group in comparison with the AP group. CONCLUSION: Cigarette smoke inhalation induced a more severe inflammatory infiltrate, with increased levels of pro-inflammatory cytokines and changes in haematological parameters in rats with induced AP. Thus, CSI aggravated AP, exacerbating the inflammatory response.

Effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats.

OBJECTIVE: To evaluate the effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats. METHODOLOGY: In total, 32 male Wistar rats were divided into four groups (n = 8): AP-induced apical periodontitis; S-cigarette smoke inhalation; APS-induced AP and cigarette smoke inhalation; and C (control)-neither AP nor cigarette smoke inhalation. To induce cigarette smoke inhalation, the animals were kept in a chamber filled with tobacco smoke for 8 min thrice a day for 50 days. AP was induced 20 days after inhalation initiation by exposing their coronary pulp to their oral environment for 30 days. After animals were euthanized, their right hemimaxillae were removed for histopathological, semi-quantitative and immunohistochemical (F4/80, CD206 and iNOS) analyses. RESULTS: Quantitative data showed a moderate number of inflammatory infiltrates in AP and an intense number in APS (p < .05). Comparing F4/80+ cells showed no statistically significant differences among groups, but we found more CD206+ cells in AP than in C and S (p > .05). INOS+ immunostaining showed a significant increase in AP and APS, when compared with C and S (p < .05). APS had more iNOS+ cells than AP (p < .05). CONCLUSION: Cigarette smoke inhalation worsened AP, leading to a predominantly pro- inflammatory profile in our experimental model.

Bone Resorption in Apical Periodontitis Enhanced by Cigarette Smoke Inhalation: Histometric, Immunohistochemical, and Microtomographic Analysis in Rats.

INTRODUCTION: This study evaluated the effects of cigarette smoke inhalation (CSI) on apical periodontitis (AP) induced in rats by histometric, immunohistochemical, and microtomographic analysis. METHODS: A total of 32 male Wistar rats were divided into 4 experimental groups (n = 8): control, CSI, AP, and CSI + AP. Rats in the CSI and CSI + AP groups inhaled cigarette smoke by remaining inside a smoking chamber for 8 minutes 3 times a day for 50 days. After 20 days of smoke inhalation, rats in the AP and CSI + AP groups had the pulp of their first right lower molar exposed to induce AP. Blood was collected on day 50 to evaluate nicotine and serum cotinine levels. The animals' mandibles were removed for histologic processing to evaluate bone resorption by histometric, immunohistochemical (receptor activator of nuclear factor kappa B ligand/osteoprotegerin), and microtomographic analysis. The Student t test was applied. RESULTS: Histometric analysis showed a larger area of bone resorption (P < .05) and microtomographic analysis found greater resorption volume (P < .001) for the CSI + AP group compared with the AP group. The CSI + AP group presented a high RANKL immunostaining pattern compared with the AP group (P < .001). CONCLUSIONS: CSI increased bone resorption caused by AP.

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.

Lack of 5-lipoxygenase in intramembranous and endochondral 129Sv mice skeleton and intramembranous healing.

OBJECTIVE: To analyze the lack of 5-lipoxygenase (5LO) on dental socket healing and post-natal phenotype of intramembranous and endochondral bones. DESIGN: Wild type (WT) 129/SvEv (n = 20) and 5LO knockout (5LOKO) (n = 20) male mice underwent tooth extraction of the upper right incisor and were euthanized after 7, 14, and 30 day time points for the evaluation of dental socket healing and histological phenotyping of intramembranous (IM) and endochondral (EC) bones. Microscopic analysis of alveolar sockets included histopathological description, histomorphometry, and immunohistochemistry for 5LO, cyclooxygenase 2 (COX2), and tartrate resistant acid phosphatase (TRAP). RESULTS: Histological phenotyping revealed thicker cortical bone in EC bones (femur and vertebra) of 5LOKO mice compared to WTs, with no differences in collagenous content. Although dental socket healing was similarly observed in both groups, WT mice revealed increased numbers of COX-2+ and 5LO+ cells during bone maturing stage, with a decrease of TRAP+ cells at day 30. On the other hand, an increased quantity of fibroblasts was observed at day 7 in 5LOKO group, as well as increased inflammatory infiltrate and significantly decreased TRAP+ cells at final stages of alveolar socket healing in comparison to WTs. CONCLUSIONS: The lack of 5LO in 5LOKO mice resulted in thicker cortical of EC, but not of IM post natal bones. Furthermore, genetic deletion of 5LO in the 5LOKO mice directly affected the inflammatory response during socket healing, influencing initial and late phases of bone repair in a model of post-tooth extraction in 129Sv WT and 5LOKO mice.