Influence of photodynamic therapy on bond strength and adhesive interface morphology of MTA based root canal sealer to different thirds of intraradicular dentin.

BACKGROUND: Photodynamic therapy (PDT) is used as an adjunct to endodontic treatment to enhance microbial reduction in the root canal system. However, studies evaluating the impact of PDT on the bond strength of the canal sealer to intraradicular dentin are scarce. Thus, this in vitro study aimed to evaluate the influence of photodynamic therapy with methylene blue (MB) photosensitizer (PS) on the bond strength and morphology of the interface between mineral trioxide aggregate (MTA) based endodontic sealer and different thirds of intraradicular dentin. METHODS: Fifty-five bovine incisors were used to simulate experimental endodontic treatments. Biomechanical instrumentation was performed in all root canals and teeth were divided into 5 groups (n = 11): deionized water (control), methylene blue 50 mg/L (MB50WL), methylene blue 100 mg/L (MB100WL), methylene blue 50 mg/L + red laser (MB50L), and methylene blue 100 mg/L + red laser (MB100L). The push-out bond strength of canal sealer to intraradicular dentin was measured using a universal testing machine (n = 8). Representative scanning electron microscopy images were obtained to qualify the fracture patterns. Images of the adhesive interface morphology were obtained using confocal laser scanning microscopy (n = 3). The Kruskal-Wallis test was used to compare data on bond strength between groups, and the Friedman test between thirds (α = 0.05). RESULTS: When comparing root thirds for the MB group with the higher concentration activated by red laser, higher bond strength values was found for the apical third than for the middle third (P = 0.0302). MB in different concentrations, activated by red laser or not, had no influence on the bond strength of distinct thirds of the intraradicular dentin (P > 0.05). As for the adhesive interface morphology, the MB100L group showed a lower qualitatively sealer penetration into the intraradicular dentin. CONCLUSIONS: PDT with MB PS at 50 mg/L had no negative impact on the bond strength of MTA Fillapex canal sealer to intraradicular dentin, being a suitable antisepsis protocol for endodontic treatments.

Reduced bone resorption and inflammation in apical periodontitis evoked by dietary supplementation with probiotics in rats.

AIM: To evaluate the relationship between systemic administration of probiotics and inflammation/resorption processes associated with apical periodontitis (AP) in a rat model. METHODOLOGY: Twenty-four male Wistar rats were used. AP was induced in the mandibular left/right first molars. The animals were arranged into three groups: Control, Lactobacillus rhamnosus and L. acidophilus. Probiotics were orally administered via gavage (109 colony-forming units (CFU) diluted in 5 mL of water) for 30 days during the development of AP. On the 30th day, blood was collected to analyse the calcium, phosphorus and alkaline phosphatase concentrations in plasma. Then, the animals were euthanized and the jaws removed for micro-computed tomography and immune-histopathological analysis for receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG) and tartrate-resistant acid phosphatase (TRAP). After the Shapiro-Wilk test of normality, the Kruskal-Wallis followed by Dunn's test was performed for nonparametric data, and analysis of variance followed by the Tukey test was performed for parametric data (P < 0.05). RESULTS: There was no significant difference in the calcium and phosphorus levels in plasma amongst the groups (P > 0.05). The level of alkaline phosphatase was significantly higher in the groups that consumed probiotics (P < 0.05). A significantly lower volume of bone resorption was observed in groups that consumed probiotics (P < 0.05). The inflammatory infiltrates and the immunolabelling for RANKL and TRAP were significantly lower in probiotic groups when compared to the control (P < 0.05). Also, the OPG was significantly more immunolabelled in the L. acidophilus group than in the L. rhamnosus and control groups (P < 0.05). CONCLUSION: Probiotic supplementation through gavage (L. rhamnosus and L. acidophilus) had a significant effect on the reduction of inflammation and bone resorption in apical periodontitis development in rats.

Systemic administration of probiotics reduces the severity of apical periodontitis.

AIM: To evaluate the effect of systemic administration of probiotics on the severity of apical periodontitis (AP). METHODOLOGY: Twenty-four male Wistar rats were used. AP was induced in the maxillary left/right first molars. The animals were arranged into groups: Control, Lactobacillus rhamnosus, and Lactobacillus acidophilus. Probiotics were administered orally for gavage (109 colony-forming units diluted in 5 mL of water for 30 days) during the development of AP. After 30 days, cardiac puncture was performed to analyse the complete blood count. Moreover, microbiological analysis of the root canal contents and saliva was performed. Then, the animals were euthanized and the jaw removed for histopathological and IL-10, IL-1ß and IL-6 immunolabeling analyses. After the Shapiro-Wilk test of normality, the Kruskal-Wallis followed by Dunn's test was performed for nonparametric data, and analysis of variance followed by the Tukey test was performed for parametric data (P < 0.05). RESULTS: No significance difference was observed in the blood profiles and in the counts of microorganisms from the saliva samples among the groups (P > 0.05). Total microorganism counts in the root canal, the inflammatory infiltrate and the immunostaining for IL-1ß and IL-6 in AP were significantly lower in the probiotic groups when compared with the control group (P < 0.05). IL-10 was significantly more immunolabled in the probiotic groups than in the control group (P < 0.05). CONCLUSION: Supplementation with probiotics (Lactobacillus rhamnosus and Lactobacillus acidophilus) had a significant effect on the severity of apical periodontitis in rats, demonstrating the anti-inflammatory effect of probiotics on the development of apical periodontitis.

The presence of osteocalcin, osteopontin and reactive oxygen species-positive cells in pulp tissue after dental bleaching.

AIM: To analyse the influence of H2 O2 on pulp repair through osteocalcin and osteopontin immunolabelling and in cellular defence by using the antireactive oxygen species (ROS) antibody. METHODOLOGY: The maxillary molars of 50 rats were treated with 35% H2 O2 (Ble groups) or placebo gel (control groups). At 0 h and 2, 7, 15 and 30 days (n = 10 hemimaxillae), the rats were killed and pulp tissue was evaluated using inflammation and immunolabelling scores (osteocalcin/osteopontin); ROS-positive cells were counted. Paired t-test and Wilcoxon signed-rank test were used (P < 0.05). RESULTS: The Ble group had necrosis in the coronal pulp at 0 h and in the occlusal third of the coronal pulp at 2 days; at 7, 15 and 30 days, no inflammation was noted similar to the controls (P > 0.05). Osteocalcin was absent in the Ble at 0 h, moderate at 2 days and increased thereafter, differing from the controls at all two periods (P < 0.05). Osteopontin was higher principally at 7 and 15 days in Ble groups, but differing with control groups from 2 days after bleaching (P < 0.05). The Ble group had more ROS-positive cells in the pulp at 7 and 15 days (P < 0.05). Tertiary dentine was observed at 7 days, increasing thereafter (P < 0.05). CONCLUSIONS: Post-bleaching pulp repair was associated with increased osteocalcin over time. Osteopontin also participated in this process, and anti-ROS was involved in cellular defence against H2 O2 .

Chronic alcohol consumption increases inflammation and osteoclastogenesis in apical periodontitis.

AIM: To investigate the effect of chronic alcohol consumption on apical periodontitis in rats. METHODOLOGY: Thirty-two male Wistar rats were arranged into four groups: Control (C): without apical periodontitis and nonalcoholic diet; (AL): without apical periodontitis and alcoholic diet; (AP): with apical periodontitis and nonalcoholic diet; and (AP + AL): with apical periodontitis and alcoholic diet. The alcoholic solution at 20% was given to the AL and AP + AL groups as the sole source of hydration throughout the experiment. AP was induced in the mandibular left first molars at the end of the 4th week. Weight changes and the amount of solid and liquid foods were recorded for 8 weeks. At the end, the animals were euthanized and the jaws removed followed by histological processing for histopathological and RANKL, OPG, TRAP and HIF-1α analyses. The Mann-Whitney test was used for nonparametric data, and anova followed by the Tukey test was performed for parametric data, with P < 0.05. RESULTS: Animals that received the alcoholic diet had a lower weight gain than the other groups (P < 0.05). Control and AL groups did not have an inflammatory response in the periapical tissues. The median score of inflammatory infiltrate was significantly higher in the AP + AL group (2.5) compared to the AP group (1.5; P < 0.05). In the same comparison, AP + AL was associated with score 3 for RANKL and HIF-1α versus score 2 for AP group (P < 0.05). Moreover, the values for TRAP were 3.88 ± 0.70 cells mm-1 for the AP + AL group and 2.43 ± 0.94 cells mm-1 for the AP group (P < 0.05). CONCLUSION: In rats, an alcoholic diet had a significant effect on the severity of apical periodontitis, exacerbating the inflammatory response and osteoclastogenesis.

Biocompatibility and immunohistochemical evaluation of a new calcium silicate-based cement, Bio-C Pulpo.

AIM: To evaluate the inflammatory response and ability to induce mineral deposition through histological and immunohistochemical analysis for osteocalcin (OCN), osteopontin (OPN) and bone sialoprotein (BSP) of a new calcium silicate-based cement, Bio-C Pulpo (Angelus), compared to white mineral trioxide aggregate (White MTA-Ang) (Angelus). METHODOLOGY: Polyethylene tubes containing Bio-C Pulpo and White MTA-Ang as well as empty tubes were implanted into the dorsal connective tissue of 30 Wistar rats, which were arranged in five groups according to the period of analysis: 7, 15, 30, 60 and 90 days. After each experimental period, the tubes with surrounding tissue were removed and histologically processed to be analysed using haematoxylin-eosin and immunohistochemistry for the detection of OCN, OPN and BSP. The data were statistically analysed (Friedman's test) at a 5% significance level. RESULTS: The inflammatory response observed with Bio-C Pulpo and White MTA-Ang was greater after 7 and 15 days and decreased from 30 days onwards. No significant difference was found between the control, Bio-C Pulpo and White MTA-Ang at the different periods of analysis (P > 0.05). The immunolabelling for OCN, OPN and BSP was more intense for Bio-C Pulpo and White MTA-Ang after 60 and 90 days, but there was no difference between Bio-C Pulpo and White MTA-Ang at the different periods of analysis (P > 0.05). CONCLUSION: Bio-C Pulpo is biocompatible and induces immunolabelling of osteogenic markers such as OCN, OPN and BSP similar to White MTA-Ang.

Systemic bone marker expression induced by grey and white mineral trioxide aggregate in normal and diabetic conditions.

AIM: To investigate the relationship between diabetes mellitus and local/systemic effects of both grey and white mineral trioxide aggregate (MTA) Angelus on bone marker expression. METHODOLOGY: Wistar rats were divided into two groups: healthy and diabetic (Alloxan induced), which were further divided into three subgroups (control, GMTA Angelus and WMTA Angelus). Polyethylene tubes filled with MTA materials or empty tubes were implanted in dorsal connective tissue. On days 7 and 30, blood samples were collected for calcium, phosphorus and ALP measurement. The animals were euthanized; implanted tubes were removed and processed for immunohistochemical analysis of osteocalcin (OCN) and osteopontin (OPN). Kruskal-Wallis followed by Dunn's multiple comparison test was performed for nonparametric data, and anova followed by Tukey's test for parametric data. RESULTS: No difference in systemic serum calcium levels between both groups was observed. On day 7, serum phosphorus levels within the WMTA healthy group were higher than that of the diabetic group. On day 30, healthy rats exhibited lower phosphorus levels than diabetic ones. At both time points, the diabetic group was associated with more ALP activity than the healthy group. Immunohistochemical analyses of the healthy group revealed OCN- and OPN-positive cells in the presence of both MTA materials. However, under diabetic conditions, both OCN and OPN were absent. CONCLUSION: Both MTA materials were associated with an increase in serum calcium, phosphorus and ALP, suggesting a potential systemic effect, along with triggered differentiation of OCN- and OPN-positive cells. Moreover, in diabetic conditions, an inhibitory effect on MTA-induced differentiation of OCN- and OPN-positive cells was detected.

Concentration-dependent effect of bleaching agents on the immunolabelling of interleukin-6, interleukin-17 and CD5-positive cells in the dental pulp.

AIM: To evaluate lymphocyte-like cell activation (CD5-positive cells) and the expression of interleukin (IL)-6 and IL-17 in the pulp after tooth bleaching with two concentrations of hydrogen peroxide (H2 O2 ). METHODOLOGY: The right and left maxillary molars from 40 rats were treated randomly with bleaching gel with 20% H2 O2 (BLUE group, 1 application of 50 min), 35% H2 O2 (MAXX group, three applications of 15 min), or placebo gel (control). After 2 and 30 days, the rats were killed (n = 10), and the jaws were processed for histological and immunohistochemistry analysis of the pulp tissue. The scores of inflammation and immunolabelling (IL-6/IL-17) were submitted to Mann-Whitney and Kruskal-Wallis followed Dunn tests, respectively; anova tests were used for comparisons of number of CD5-positive cells and pulp chamber area values (P < 0.05). RESULTS: At 2 days, 60% of specimens of the BLUE group were associated with moderate inflammation in pulp horns, and in the MAXX group with necrosis (P < 0.05). At 30 days, the pulp was organized, and tertiary dentine was formed. The MAXX group had superior immunolabelling of IL-17 at 2 days differing significantly from other groups (P < 0.05). At 2 days, 90% of the specimens of the BLUE group had moderate immunolabelling of IL-6, and 50% of the MAXX group had severe immunolabelling, both significantly different from the control (P < 0.05). There was no significant difference between the groups at 30 days (P > 0.05). CD5-positive cells were present at 2 and 30 days, particularly in the bleached groups (P < 0.05), without significant difference between time periods (P > 0.05). CONCLUSIONS: IL-6 and IL-17 participated in inflammation in the pulp tissue of rats after tooth bleaching, particularly at 2 days. The immunolabelling was greater with increasing H2 O2 concentration. This process was accompanied by the prolonged activation of CD5-positive cells.

The effect of dental bleaching on pulpal tissue response in a diabetic animal model: a study of immunoregulatory cytokines.

AIM: To evaluate the influence of tooth bleaching on immunoregulatory cytokines production (IL-6, Tumour necrosis factor (TNF)-α and IL-17) in the pulp tissue of normoglycaemic and diabetic rats. METHODOLOGY: Twenty-eight rats were divided into normoglycaemic and diabetic rats (n = 14). Diabetes mellitus (DM) was induced with a single dose of alloxan diluted in citrate buffer via intramuscular injection. After DM confirmation, all rats were sedated and tooth bleaching was performed using 35% hydrogen peroxide on the right maxillary molars for 30 min. Left molars were used as controls. Bleaching resulted in four hemimaxillae groups: normoglycaemic (N), N-bleached (NBle), diabetic (D) and D-bleached (DBle). After 2 and 30 days, rats were euthanized and hemimaxillae processed for analysis by haematoxylin and eosin and immunohistochemistry. Results within and between animals were submitted to Wilcoxon signed-rank and Mann-Whitney tests (P < 0.05). RESULTS: At 2 days, the NBle group had mild, and the DBle had severe inflammatory infiltration in the pulpal tissue (P < 0.05). TNF-α and IL-6 cytokines were associated with increased immunolabelling in the bleached groups compared to nonbleached (P < 0.05). However, IL-17 had increased immunolabelling in the NBle compared to the N and DBle group (P < 0.05). At 30 days, reactionary dentine was observed in the coronal pulp of all bleached teeth and no inflammation was present (P > 0.05). TNF-α cytokines had increased immunolabelling in the DBle group compared to the D group (P < 0.05). However, for IL-6 and IL-17, no difference was observed in this period (P > 0.05). CONCLUSIONS: Tooth bleaching increased IL-6 and TNF-α in the pulp tissue regardless of diabetes mellitus; however, diabetic rats had higher TNF-α levels for longer periods. Tooth bleaching influenced the increase in IL-17 in the early periods in normoglycaemic rats.

RUNX-2, OPN and OCN expression induced by grey and white mineral trioxide aggregate in normal and hypertensive rats.

AIM: To investigate whether hypertension affects mineralization associated with white and grey mineral trioxide aggregate (MTA Angelus® ) implanted subcutaneously into rats by assaying osteoblastic biomarkers. METHODOLOGY: Polyethylene tubes containing grey MTA Angelus® , white MTA Angelus® , intermediate restorative material (IRM; positive control) or an empty tube (negative control) were implanted into the dorsal connective tissue of spontaneous hypertensive (n = 12) and Wistar (normotensive; n = 10) rats. Half of the rats in each group were killed after 7 days, and the remaining after 30 days. Tubes with surrounding tissue were removed, and immunostaining was performed to detect RUNX-2, OPN and OCN proteins. The normality of data was analysed using the Shapiro-Wilk test. Comparison of two independent groups was performed using the Mann-Whitney U-test, to detect a significant difference. A post hoc test accounting for multiple comparisons was performed following Tukey's test (P < 0.05). RESULTS: Under hypertensive conditions after 30 days, both MTA materials were associated with immunolabelling for RUNX-2 from low to moderate, which was less than that observed at normal blood pressure and the 7-day groups (P < 0.05). The expression of OPN and OCN proteins under both MTA conditions was considered low after both 7 and 30 days for the hypertensive condition, and was less than that in animals with normal blood pressure after 30 days (P < 0.05). No immunostaining for any biomarkers in the control and IRM groups was observed (P < 0.05). CONCLUSION: Hypertension decreased the immunostaining of RUNX-2, OPN and OCN biomarkers in response to MTA. Thus, hypertension can jeopardize the mineralization ability of MTA and may have a negative impact on endodontic treatment outcomes.

Mineral trioxide aggregate improves healing response of periodontal tissue to injury in mice.

BACKGROUND AND OBJECTIVE: Mineral trioxide aggregate (MTA) is a biomaterial used in endodontic procedures as it exerts beneficial effects on regenerative processes. In this study, we evaluate the effect of MTA on healing of periodontal ligament (PDL) and surrounding tissue, following injury, in a transgenic mouse model and on the differentiation of murine mesenchymal progenitor cells in vitro. MATERIAL AND METHODS: We used an inducible Cre-loxP in vivo fate mapping approach to examine the effects of MTA on the contributions of descendants of cells expressing the αSMA-CreERT2 transgene (SMA9+ ) to the PDL and alveolar bone after experimental injury to the root furcation on the maxillary first molars. Col2.3GFP was used as a marker to identify mature osteoblasts, cementoblasts and PDL fibroblasts. The effects of MTA were examined 2, 17 and 30 days after injury and compared histologically with sealing using an adhesive system. The effects of two dilutions of medium conditioned with MTA on proliferation and differentiation of mesenchymal progenitor cells derived from bone marrow (BMSC) and periodontal ligament (PDLC) in vitro were examined using the PrestoBlue viability assay, alkaline phosphatase and Von Kossa staining. The expression of markers of differentiation was assessed using real-time PCR. RESULTS: Histological analyses showed better repair in teeth restored with MTA, as shown by greater expansion of SMA9+ progenitor cells and Col2.3GFP+ osteoblasts compared with control teeth. We also observed a positive effect on differentiation of SMA9+ progenitors into osteoblasts and cementoblasts in the apical region distant from the site of injury. The in vitro data showed that MTA-conditioned medium reduced cell viability and osteogenic differentiation in both PDLC and BMSC, indicated by reduced von Kossa staining and lower expression of osteocalcin and bone sialoprotein. In addition, cultures grown in the presence of MTA had marked decreases in SMA9+ and Col2.3GFP+ areas as compared with osteogenic medium, confirming reduced osteogenesis. CONCLUSION: MTA promotes regeneration of injured PDL and alveolar bone, reflected as contribution of progenitors (SMA9+ cells) into osteoblasts (Col2.3GFP+ cells). In vitro, MTA-conditioned medium fails to promote osteogenic differentiation of both PDLC and BMSC.

The effect of dental bleaching on pulpal tissue response in a diabetic animal model.

AIM: To evaluate pulpal tissue response after dental bleaching in normal and alloxan-induced diabetic rats. METHODOLOGY: Twenty-eight rats were divided into two groups of normoglycaemic and diabetic rats (n = 14). Diabetes mellitus (DM) was induced with alloxan. After DM confirmation, all rats were anaesthetized and dental bleaching was performed with 35% hydrogen peroxide (H2 O2 ) on the right maxillary molars for 30 min. Left molars were used as controls. Bleaching resulted in four hemimaxillae groups: normoglycaemic (N), N-bleached (NBle), diabetic (D) and D-bleached (DBle). After 2 or 30 days, the animals were euthanized and the hemimaxillae were removed, processed for histopathological analysis and stained with haematoxylin-eosin (HE), Masson's trichrome (MT) and picrosirius red (PSR). Results obtained within animals (normoglycaemic or diabetic rats) were submitted to Wilcoxon or paired t-tests, and between animal (normoglycaemic and diabetic rats), to Mann-Whitney test or t-tests. RESULTS: At 2 days, the NBle group had a mild inflammatory infiltration in the pulpal tissue, whilst the DBle had severe inflammation or necrosis (P < 0.05). At 30 days, no inflammation was present. However, a significant difference in pulp chamber area reduction by reactionary dentine deposition was found between the NBle and DBle groups (P < 0.05). At 2 days, fewer immature collagen fibres and more mature collagen fibres were noted in the NBle, D and DBle groups; this was significantly different when compared to the N group (P < 0.05). At 30 days, significantly fewer immature collagen fibres and more mature collagen fibres were noted in NBle compared with DBle group (P < 0.05). CONCLUSIONS: The inflammatory tissue response in rats' teeth after dental bleaching was greater in diabetic rats. Additionally, the increase in reactionary dentine deposition and mature collagen fibres observed in diabetic rats needs further evaluation to confirm the present results.

Raloxifene modulates regulators of osteoclastogenesis and angiogenesis in an oestrogen deficiency periapical lesion model.

AIM: To analyse the local regulatory mechanisms of osteoclastogenesis and angiogenesis during the progression of periapical lesions in female rats with oestrogen deficiency and treatment with raloxifene (RLX). METHODOLOGY: Female Wistar rats were distributed into groups: SHAM-veh, subjected to sham surgery and treated with a vehicle; OVX-veh, subjected to ovary removal and treated with a vehicle; and OVX-RLX, subjected to ovary removal and treated with RLX. Vehicle or RLX was administered orally for 90 days. During treatment, the dental pulp of mandibular first molars was exposed to the oral environment for induction of periapical lesions, which were analysed after 7 and 30 days. After the experimental periods, blood samples were collected for measurement of oestradiol, calcium, phosphorus and alkaline phosphatase. The rats were euthanized and the mandibles removed and processed for immunohistochemical detection of receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), hypoxia-inducible factor-1 alpha (HIF-1α) and bone-specific alkaline phosphatase (BALP). Data were compared using Kruskal-Wallis followed by Dunn test (nonparametric values) and anova followed by the Tukey's test (parametric values). RESULTS: The plasma concentration of oestradiol showed hypo-oestrogenism in the rats subjected to ovary removal. On day 7, alkaline phosphatase activity, calcium and phosphorus were higher in the OVX-RLX group than in the OVX-veh group (P < 0.001), but immunolabelling for RANKL and HIF-1α was lower in OVX-RLX group (P < 0.001). On day 30, the OVX-veh group had higher immunolabelling for RANKL than the OVX-RLX group (P < 0.05). There were no significant differences in the immunoreactivity of OPG and BALP between any groups at either time-point (P > 0.05). CONCLUSION: RLX therapy reversed the increased levels of the local regulators of both osteoclastogenesis and angiogenesis induced by oestrogen deficiency.

The role of IL-6 on apical periodontitis: a systematic review.

The aim of this review was to examine current knowledge of the role of interleukin-6 (IL-6) in apical periodontitis (AP) pathogenesis as an inflammatory or pro-inflammatory cytokine. It also looked at whether IL-6 could serve as a measure for differential diagnosis or as a biomarker that can further predict the progression of bone resorption. A systematic review relating to AP and IL-6 was made via PubMed, BIOSIS, Cochrane, EMBASE and Web of Science databases using keywords and controlled vocabulary. Two independent reviewers first screened titles and abstracts and then the full texts. The reference lists of the identified publications were examined for additional titles. Eighteen papers were studied in total. In vitro studies (n = 6) revealed that IL-6 is present in AP, and its levels are proportional to the size of the periapical lesions. Neutrophils and macrophages resident in these lesions can produce IL-6 in vitro after a bacterial stimulus. Animal studies (n = 5) showed that IL-6 is present in AP and that osteoblasts can produce IL-6 in vivo. On the other hand, two studies using IL-6 knockout mice revealed larger periapical lesions when compared with control groups, demonstrating IL-6's role as an anti-inflammatory cytokine. In human studies (n = 7), IL-6 was identified in AP, and its levels were higher in symptomatic, epithelialized and large lesions than in asymptomatic and small lesions. These data lead to the conclusion that IL-6 may play a pro-inflammatory role, increasing its levels and reabsorbing bone in the presence of infections. When IL-6 is not present, other cytokines such as IL-1 and TNF-α induce bone resorption. Further studies about the relationship between AP development and the cytokine network must be performed to establish the exact role of each cytokine in the inflammatory process.

Relationships between oral infections and blood glucose concentrations or HbA1c levels in normal and diabetic rats.

AIM: To measure glycosylated haemoglobin (HbA1c) in a diabetic model as a means of investigating apical periodontitis and periodontal disease for their effects on both blood glucose concentrations and long-term glycaemic control. METHODOLOGY: Wistar rats (n = 80) were assigned to one of eight groups (10 animals/group): control (G1), apical periodontitis (G2), periodontal disease (G3), apical periodontitis and periodontal disease (G4), diabetic (G5), diabetic with apical periodontitis (G6), diabetic with periodontal disease (G7) and diabetic with apical periodontitis and periodontal disease (G8). A diabetic state was induced with streptozotocin. Apical periodontitis was induced by dental exposure to the oral environment. Periodontal disease was induced by periodontal ligature. Blood glucose concentrations were measured at 0, 6, 30 and 60 days. After euthanization, rat maxillae were excised and processed for histopathology and for measurement of HbA1c levels by ion exchange chromatography. Data were tabulated and subject to statistical analysis (P < 0.05). RESULTS: The inflammatory infiltrate and alveolar bone resorption were more severe in diabetic rats (P < 0.05). Diabetic rats exhibited higher levels of HbA1c independent of apical periodontitis or periodontal disease (P < 0.05). However, the presence of oral infections in diabetic rats was associated with increased blood glucose concentrations (P < 0.05). CONCLUSIONS: Oral infections affect glycaemic conditions in diabetic rats and increase HbA1c levels in normoglycaemic or diabetic rats.

Histological evaluation of MTA as a root-end filling material.

AIM: To assess the histological response associated with grey mineral trioxide aggregate (GMTA) and zinc oxide eugenol (ZOE) as root-end filling materials in teeth where the root canals were not filled and the coronal access cavities were not restored. METHODOLOGY: Periapical lesions were developed in 24 premolar teeth in three dogs. The root canals were prepared and half of them were dried, filled and the coronal access restored (closed). The remaining teeth were not root filled and no coronal restoration was placed (open). Apical root-end resections were performed 3 mm from the apex, and root-end cavities were prepared with ultrasonic tips. These were randomly filled with either ZOE or GMTA in the same number of specimens using MAPSYSTEM device. After 180 days the animals were killed and blocks of tissues removed and processed for histological examination. Periradicular tissue reaction was evaluated, including severity of inflammation and cementum formation. Statistical analysis was performed using anova analysis and Tukey's test. RESULTS: A significant difference was found between the levels of inflammation in the periradicular tissues of the GMTA/closed group, compared with the ZOE/open and ZOE/closed groups (P < 0.05) but not between GMTA/closed and GMTA/open groups. Cementum formation was not found over any ZOE specimens but over MTA in all specimens. No microorganisms were found in the interface between the material and the dentinal walls. CONCLUSIONS: GMTA was associated with less periapical inflammation and tissue response when used as a root-end filling material, even when no root filling or coronal restoration was present.

Glycol methacrylate: an alternative method for embedding subcutaneous implants.

The aim of this investigation was to study the use of glycol methacrylate (GMA) as an embedding material for rat subcutaneous tissue, which received implants of tubes with endodontic sealer. After fixation, the specimens were dehydrated in a growing alcohol series up to 95%, immersed in infiltration GMA solution and then in embedding solution. The blocks were cut into 3.0 microm sections and stained with hematoxylin-eosin. The quality of cell definition and staining allowed a quantitative analysis of the cells infiltrated in the end of the tubes. It was also possible to identify each type of inflammatory cell. Moreover, it was possible to distinguish clearly chronic from acute inflammatory cells. The GMA technique is easy to execute and reproducible, and provides a better definition of tissue cells, thus permitting definition of the degree of the inflammatory process. Therefore, it is an excellent alternative for the evaluation of the biocompatibility of endodontic sealers.