Does Achievement of Hemostasis After Pulp Exposure Provide an Accurate Assessment of Pulp Inflammation?

PURPOSE: The purpose of this study was to determine in primary molars with carious exposures whether hemostasis at the exposure site and pulp orifice reflected inflammatory status of the pulp at the canal orifice based on cytokine levels. METHODS: Forty mandibular primary molars with deep caries were included in the study. Teeth were divided into two groups: group A had teeth where hemostasis at the exposure site was achieved within five minutes, and group B had teeth where hemostasis at the exposure site could not be achieved within five minutes. Blood samples were harvested from the exposure sites and canal orifices. Cytokine levels for IL-1ß, IL-2, IL-6, IL-8, IL-10, TNF-α, and PGE2 were measured using ELISA for all sample sites. RESULTS: The IL-6 levels at the exposure sites were found to be significantly higher in group A when compared to group B, but there was no statistically significant differences in any of the cytokine levels at the canal orifices between the two groups. CONCLUSIONS: Controlling bleeding at the exposure site or canal orifices does not provide accurate assessment of inflammation at the canal orifice and may be misleading for diagnosing vital pulp treatment in primary teeth with a carious pulp exposure.

Pulpal Tissue Inflammatory Reactions after Experimental Pulpal Exposure in Mice.

INTRODUCTION: The purpose of this study was to establish a stable experimental mice pulpal inflammatory model and to evaluate inflammatory reactions of pulpal tissue after pulpal exposure. METHODS: Pulpal inflammation was induced in 80 C57BL/6 mice by occlusal exposure of the pulp of the maxillary first molar. The mice were sacrificed randomly at 0, 1, 6, 12, 24, 48, and 72 hours after pulpal exposure. Mice without pulpal exposure served as controls. Maxillary teeth were obtained and prepared for histologic analyses and real-time polymerase chain reaction analyses. RESULTS: As the duration of pulpal exposure increases, the inflammatory reaction is exacerbated. Within 6 to 12 hours after pulpal exposure, pulp tissues experienced red blood cell extravasation to the destruction of the odontoblast layer. After 24 hours, necrosis was observed in the pulpal tissue; until 72 hours, necrosis spread to the whole coronal pulpal tissue, and a large number of inflammatory cells were found in the radicular pulpal tissue. The results of histomorphologic scores have the same trend; samples from the 72-hour group possessed the highest score followed by samples from other groups (P < .01). The expression levels of inflammatory cytokines increased over the 72 hours, and there was a high rate of inflammatory cytokine expression at 6 and 12 hours after pulpal exposure. CONCLUSIONS: Our study represents a stable mice model for studying pulpal inflammation in vivo. Mouse pupal inflammation progresses rapidly, with dramatic changes evident in just a few hours.

Histochemical localization of Dickkopf-1 in induced rat periapical lesions.

INTRODUCTION: The purpose of this study was to evaluate the expression of Dickkopf-1 (DKK-1), a secreted antagonist of the Wnt (wingless)/beta-catenin signaling pathway, during the development of periapical lesions in rats. METHODS: Periapical lesions were induced in Wistar rats by occlusal exposure of the pulp of their mandibular first molars. The animals were sacrificed randomly at 0, 7, 14, 21, and 28 day after pulpal exposure. Jaws containing the first molar were obtained and routinely prepared for histologic, immunohistochemical, and enzyme histochemical double immunofluorescence analyses. Data were analyzed using 1-way analysis of variance and Pearson correlation test. RESULTS: The expansion of the area of periapical lesions was visible from days 7-21 and slowed down thereafter. A few DKK-1- and receptor activator of nuclear factor kappa B ligand (RANKL)-positive cells and osteoclasts were observed on day 7. All positive samples peaked in number on day 14. The expression levels of DKK-1 and RANKL and the number of osteoclasts decreased on days 21 and 28. DKK-1 expression was positively correlated with RANKL expression and osteoclast number from days 7-28. CONCLUSIONS: DKK-1 expression was up-regulated during periapical lesion development. DKK-1 may be associated with the inflammatory response and bone resorption in periapical lesions.

Blood profile and histology in oral infections associated with diabetes.

INTRODUCTION: We aimed to investigate the relationship between blood profile and histologic findings in both apical periodontitis (AP) and periodontal disease (PD) associated with diabetes. METHODS: Wistar rats (N = 80) were assigned to the following 8 groups: control, AP, PD, AP associated with PD, diabetes, diabetes with AP, diabetes with PD, and diabetes with AP and PD. Diabetes mellitus (DM) was induced with streptozotocin, AP was induced by exposure to the oral environment, and PD was induced using periodontal ligature. After 30 days, blood samples were collected, and the rats were euthanized. Subsequently, the maxillae were processed for light microscopy. Hematologic examinations were conducted to determine the total number of erythrocytes and leukocytes, erythrocyte constant, and blood glucose level. One-way analysis of variance and Kruskal-Wallis tests were used for statistical analysis, and the significance was set at P < .05. RESULTS: A significant correlation was found between the histologic findings and blood parameters. CONCLUSIONS: In conclusion, diabetes accelerated the development and progression of AP and PD in the rats and caused an increase in the average erythrocyte volume as well as the leukocyte and neutrophil counts. Oral infections increase the total number of leukocytes, the number of neutrophils and lymphocytes, and blood glucose concentrations in DM rats.

MMP9 deficiency increased the size of experimentally induced apical periodontitis.

INTRODUCTION: Apical periodontitis is an inflammation and destruction of periapical tissues. Matrix metalloproteinase-9 (MMP-9) is thought to be involved in periapical lesion formation and progression. The aim of this study was to evaluate the lesion progression in MMP-9 knockout (KO) mice compared with that in control mice (wild type [WT]). METHODS: The pulps of mouse mandibular first molars were exposed; animals were killed at 0, 7, 14, 21, and 28 days after surgery. Hematoxylin-eosin-stained sections were observed for the description of pulpal, apical, periapical features, and the periapical lesion size. The periapical lesion size was further measured with micro-computed tomographic imaging. The number of osteoclasts was also counted by tartrate-resistant acid phosphatase histoenzymology. Real-time polymerase chain reaction and immunohistochemistry were used to analyze the expression levels of receptor activator of NF-κB (RANK), receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), interleukin-1 beta (IL-1ß), tumor necrosis factor alpha (TNF-α), MMP-2, and MMP-8. RESULTS: There was a significant difference (P < .05) between the 2 types of animals regarding the periapical lesion size, which was larger in MMP-9 KO animals. No significant differences (P > .05) were found between WT and MMP-9 KO mice related to the osteoclast number as well as the pulpal, apical, and periapical features. More neutrophil cells were observed in MMP-9 KO animals than WT mice (P < .05). The expression levels of RANK, RANKL, OPG, IL-1ß, TNF-α, MMP-2, and MMP-8 were found up-regulated in MMP-9 KO mice (P < .05). CONCLUSIONS: MMP-9 KO animals developed larger periapical lesions with greater inflammatory response, indicating an important role of MMP-9 in the host's immune and inflammatory response to root canal and periradicular infection.

Imbalance of interleukin-17+ T-cell and Foxp3+ regulatory T-cell dynamics in rat periapical lesions.

INTRODUCTION: Interleukin (IL)-17(+) T-helper (Th17) cells and Foxp3(+) regulatory T (Treg) cells are CD4(+) T-helper cells with reciprocal functions in immunology and bone metabolism. The present study aimed to investigate the expression dynamics of Th17 and Treg cells in rat periapical lesions as well as their correlation with bone resorption. METHODS: Experimental pulp exposures were made in the lower first molars of 28 Wistar rats to induce periapical lesions. Rats were killed on days 0, 7, 21, and 35. Mandibles were prepared for micro-computed tomography scanning, histologic observation, immunohistochemistry, enzyme histochemistry, and double immunofluorescence analysis. RESULTS: Through 3-dimensional and 2-dimensional measurements, the volume and area of periapical lesions visibly increased from day 7 to day 21 and then expanded slowly between days 21 and 35. IL-17-positive cells markedly increased from day 7 to day 35. However, Foxp3-positive cells remained at low levels until day 21 and then dramatically increased by day 35. The IL-17(+)/Foxp3(+) ratio and number of osteoclasts simultaneously increased from day 7 to day 21 and then decreased on day 35. Finally, the distinct distribution of CD4(+)/IL-17(+) Th17 and CD4(+)/Foxp3(+) Treg cells was observed on days 7 and 35. CONCLUSIONS: Our findings imply the imbalance of IL-17(+) T cell and Foxp3(+) Treg cell dynamics in induced periapical lesions, which may play an important role in periapical lesion progression.

Expression and regulation of a disintegrin and metalloproteinase-8 and -17 in development of rat periradicular lesion.

INTRODUCTION: A disintegrin and metalloproteinases (ADAMs) are a family of transmembrane proteins that share a common domain structure. However, little is known about the possible involvement of ADAM-8 and ADAM-17 in the development of periradicular lesions. Here we demonstrated the expression of ADAM-8 and ADAM-17 in rat periradicular lesions. METHODS: We induced experimentally periradicular lesions in rats. The animals were killed at 0, 2, 4, 6, and 8 weeks after pulp exposure. The left molars underwent immunofluorescence analysis for both ADAMs and for neutrophil elastase, and right molars were used for reverse transcription-polymerase chain reaction analysis of ADAM-8 and ADAM-17. The areas of these lesions were measured histometrically, and the numbers of all antigen-positive cells in the periapical portion were counted per unit area. RESULTS: The area of the periradicular lesions gradually expanded from 0 to 4 weeks, showing a large increase from week 2 to week 4. Both ADAM-8-positive and ADAM-17-positive cells gradually increased in number from 0 to 4 weeks and then decreased from 4 to 8 weeks. There were more ADAM-17-expressing cells than ADAM-8-expressing ones at all experimental periods except at 4 weeks. The highest expression of ADAM-8 mRNA was observed at 4 weeks, and there were significant differences between 0 and 2 weeks and between 4 and 6 weeks. The expression of ADAM-17 mRNA increased from 0 to 4 weeks and subsequently decreased from 4 to 8 weeks, with a significant difference between 4 and 6 weeks. CONCLUSIONS: Our results suggest that ADAM-8 and ADAM-17 may be related to the development of rat periradicular lesions.

Periapical lesions decrease insulin signal and cause insulin resistance.

INTRODUCTION: Inflammatory cytokines are associated with decreased insulin signal transduction. Moreover, local oral inflammation, such as that accompanying periodontal disease, is associated with insulin resistance and type 2 diabetes mellitus. The aim of this study was to evaluate the effect of periapical lesions (PLs) on insulin signaling and insulin sensitivity in rats. We hypothesized that PLs alter systemic insulin signaling and insulin sensitivity via elevated plasmatic tumor necrosis factor α (TNF-α). METHODS: Wistar rats were divided into control (CN) and PL groups. PLs were induced by exposing pulpal tissue to the oral environment. After 30 days, insulin sensitivity was measured using the insulin tolerance test. After euthanization, maxillae were processed for histopathology. Plasmatic concentrations of tumor necrosis factor α (TNF-α) were determined via the enzyme-linked immunosorbent assay. Insulin signal transduction was evaluated using insulin receptor substrate tyrosine phosphorylation status and serine phosphorylation status in periepididymal white adipose tissue via Western blotting. For insulin signaling and insulin tolerance tests, the analyses performed were analysis of variance followed by the Tukey post hoc test. For TNF-α analysis, the Student's t test was used. In all tests, P < .05 was considered significant. RESULTS: The rats with PLs showed higher plasmatic TNF-α, lower constant rate for glucose disappearance values, and reduced pp185 tyrosine phosphorylation status but no change in serine phosphorylation status in white adipose tissue after insulin stimulation. CONCLUSIONS: PLs can cause alterations to both insulin signaling and insulin sensitivity, probably because of elevation of plasmatic TNF-α. The results from this study emphasize the importance of the prevention of local inflammatory diseases, such as PLs, with regard to the prevention of insulin resistance.

A non-invasive model for measuring nociception after tooth pulp exposure.

Temporomandibular arthritis will lengthen a rodent's meal duration. We hypothesized that meal duration would also lengthen after tooth pulp exposure, suggesting that this behavior could be used to measure tooth nociception. To test this hypothesis, we placed rats in feeding units and subjected 4 anterior mandibular molars to pulp exposure, with and without pre-treatment with the analgesic buprenorphine-HCl. In the first study, male Sprague-Dawley rats were placed in computerized sound-attenuated feeding modules, the pulp of 4 molars on the mandible were exposed, and meal duration was measured for 13 days. In a second study, rats were injected with either the analgesic buprenorphine-HCl or saline every 12 hrs; injections were started one day before pulp exposure. Meal duration was determined before and after treatment. In the first study, pulp exposure significantly increased daily meal duration for 8 days. In the second study, pulp exposure lengthened daily meal duration, but the group that was treated with buprenorphine-HCl showed no significant difference compared with control rats without pulp exposure. Evidence supports that a lengthening in meal duration is a response to tooth nociception and that this nociception can be measured for over a week.

Expression of angiogenic factors in rat periapical lesions.

INTRODUCTION: Angiogenic factors such as VEGFR2 (vascular endothelial cell growth factor receptor 2), Bcl-2 (a prosurvival and proangiogenic signaling molecule), and chemokine (C-X-C motif) ligand 1 (CXCL1) (a proangiogenic chemokine) may have critical roles in enhancing the establishment of apical periodontitis. To understand the role of these factors in the pathogenesis of apical periodontitis, we conducted immunohistochemical and molecular biological analysis. METHODS: Apical periodontitis was induced in the lower first molars of Wistar rats by making unsealed pulp exposures. After, 14, 21, and 28 days, the molars were retrieved, embedded as frozen sample blocks, and cut in a cryostat. Normal lower first molars served as controls. Immunostaining for CD31 (a marker for endothelial cells), Bcl-2, and real-time polymerase chain reaction analysis of VEGFR2, Bcl-2, CXCL1, and CXCR2 messenger RNA were performed. In the real-time polymerase chain reaction analysis, messenger RNA was extracted from CD31-stained endothelial cells that were retrieved with laser capture microdissection. For statistical analysis of immunohistochemistry, the immunostained area was plotted, and pixel counts were determined. Then, the percentage of the immunostained area in the total area was calculated. RESULTS: The density of the CD31-stained area increased until 21 days after pulp exposure. On the other hand, Bcl-2-stained area showed the highest density at 14 days (active lesion expanding phase) and then decreased until 28 days (lesion stability phase). VEGFR2, Bcl-2, CXCL1, and CXCR2 messenger RNA expression in endothelial cells showed the highest levels at 14 days and then decreased until 28 days. CONCLUSIONS: The increase in microvascular density and the up-regulation of VEGFR2, Bcl-2, CXCL1, and CXCR2 messenger RNA expression in endothelial cells took place coincidently with the expanding phase of experimentally induced periapical lesions. These data suggest that these angiogenic factors play a role in the lesion development.

Combination injuries 1. The risk of pulp necrosis in permanent teeth with concussion injuries and concomitant crown fractures.

BACKGROUND: The reported risk of pulp necrosis (PN) is low in teeth with concussion injuries. A concomitant crown fracture may affect the risk of PN. AIM: To analyze the influence of a crown fracture (with and without pulp exposure) on the risk of PN in teeth with concussion injury. MATERIAL: The study included 469 permanent incisors with concussion from 358 patients (226 male, 132 female). Among these, 292 had a concomitant crown fracture (70 with and 222 without pulp exposure). All teeth were examined and treated according to standardized protocol. STATISTICAL ANALYSIS: The risk of PN was analyzed by the Kaplan-Meier method and Cox regression. Risk factors included in the analysis: gender, age, stage of root development, type of crown fracture, and response to electric pulp test (EPT) at the initial examination. The level of significance was set at 5%. RESULTS: The risk of PN was low in teeth with immature root development [1.1%, 95% confidence intervals (CI): 0-3.4]. The following factors significantly increased the risk of PN in teeth with mature root development: crown fracture without pulp exposure [hazard ratio 4.1 (95% CI: 1.4-11.9), P = 0.01] and no response to EPT at the initial examination [hazard ratio 30.7 (95% CI: 7.7-121), P < 0.0001]. The overall risk of PN increased from 3.5% (95% CI: 0.2-6.8) to 11.0% (95% CI: 5.2-16.7) when a concomitant crown fracture without pulp exposure was present. If the tooth had both a crown fracture and gave no response to EPT, the risk further increased to 55.0% (95% CI: 34.3-75.8). CONCLUSION: No response to EPT at the initial examination or a concomitant crown fracture significantly increased the risk of PN in teeth with concussion injury and mature root development. If both risk factors were present there was a synergetic effect.

Combination injuries 3. The risk of pulp necrosis in permanent teeth with extrusion or lateral luxation and concomitant crown fractures without pulp exposure.

AIM: To analyze the influence of a crown fracture without pulp exposure on the risk of pulp necrosis (PN) in teeth with extrusion or lateral luxation. MATERIAL AND METHODS: The study included 82 permanent incisors with extrusion from 78 patients (57 male, 21 female) and 179 permanent incisors with lateral luxation from 149 patients (87 male, 62 female). A total of 25 teeth with extrusion and 33 teeth with lateral luxation had suffered a concomitant crown fracture (infraction, enamel fracture or enamel-dentin-fracture). All the teeth were examined and treated according to a standardized protocol. STATISTICS: The risk of PN was analyzed separately for teeth with immature and mature root development by the Kaplan-Meier method, the log-rank test and Cox regression (lateral luxation only). The level of significance was set at 5%. Risk factors included in the analysis were gender, age, crown fracture, and response to electric pulp test at the initial examination. RESULTS: A concomitant crown fracture significantly increased the risk of PN in teeth with lateral luxation. For teeth with immature root development (hazard ratio: 10 [95% confidence interval (CI): 1.1-100] P = 0.04), the overall risk increased from 4.7% (95% CI: 0-10.8) to 40% (95% CI: 2.8-77.2). For teeth with mature root development [hazard ratio: 2.4 (95% CI: 1.4-4.2) P < 0.001], the overall risk increased from 65.1% (95% CI: 55.2-75.1) to 93% (95% CI: 85.5-100). In teeth with extrusion and mature root development, the overall risk of PN increased from 56.5% (95% CI: 37.7-75.4) to 76.5% (95% CI: 58.9-94) in case of a concomitant crown fracture, but the difference was not statistically significant (P > 0.05). CONCLUSION: A concomitant crown fracture without pulp exposure significantly increased the risk of PN in teeth with lateral luxation. This risk factor may be used to identify teeth at increased risk of PN following lateral luxation injury.

Effects of the antioxidant agent tempol on periapical lesions in rats with doxorubicin-induced cardiomyopathy.

INTRODUCTION: Cardiovascular diseases have been associated with increased risk of endodontic complications. This study evaluated the effects of the antioxidant agent tempol on periapical lesions in rats with doxorubicin-induced cardiomyopathy in comparison with control animals. METHODS: Forty male Wistar rats were divided into 4 groups: (1) naïve rats orally treated with saline solution (10 mL/kg, during 21 days after periapical lesion induction); (2) naïve rats treated with tempol (30 and 50 mg/kg, during 21 days after periapical lesion induction) by oral pathway; (3) rats with doxorubicin-induced cardiomyopathy treated with saline solution by oral route (10 mL/kg, from day 3 to day 10 after initiating treatment with doxorubicin); and (4) rats with doxorubicin-induced cardiomyopathy orally treated with tempol (30 and 50 mg/kg, from day 3 to day 10 after initiating treatment with doxorubicin). Periapical lesions were induced on the first right mandibular molar tooth. After 21 days of apical periodontitis induction, the animals were killed, and the mandibles were collected for radiographic and histologic analysis. RESULTS: The oral administration of tempol (50 mg/kg) was able to significantly prevent the establishment of periapical lesions in either control animals or rats submitted to the model of doxorubicin-induced cardiomyopathy, according to radiographic and histologic evaluation. Nevertheless, the protective effects of tempol were virtually greater in control animals in comparison with doxorubicin-treated rats, as indicated by histologic inflammatory assessment, which might be related to the increased production of free radicals under cardiomyopathy. CONCLUSIONS: We provide novel evidence on the beneficial systemic effects of the antioxidant tempol on apical periodontitis in both control animals and rats with doxorubicin-elicited cardiomyopathy.

Long-term sequential receptor activator of NF-κB ligand (RANKL) and osteoprotegrin (OPG) expression in lipopolysaccharide-induced rat periapical lesions.

BACKGROUND: Long-term sequential expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegrin (OPG) in lipopolysaccharide (LPS)-induced rat periapical lesions has not been studied. MATERIALS: Seventy-two 4-week-old Wistar rats were divided into eight experimental groups and one control group (eight animals in each). METHODS: Lipopolysaccharide-induced periapical lesions were produced in rats by occlusal exposure of the pulp of their lower first molars in all experimental groups but not the control group. The extent of periapical destruction was measured by radiographic imaging. RANKL and OPG mRNA were measured in all tissue sections containing the periapical lesions as well as the control group every week from week 1 to week 8 by real-time quantitative reverse transcription polymerase chain reaction. RANKL and OPG protein were determined by immunohistochemistry. Osteoclasts were identified by enzyme histochemistry. RESULTS: The sequential changes in the mRNA and protein expression of RANKL and OPG were largely compatible with the occurrence of osteoclasts histologically and enzymes histochemically, as well as the mean areas of the periapical lesions radiographically during long-term observation of the LPS-induced rat periapical lesions. CONCLUSION: This study may be the first to demonstrate the long-term RANKL and OPG expression every week from week 1 to week 8 using LPS to produce periapical infection in a Wistar rat model. The long-term findings of high expressions of RANKL and OPG further extend the potential application of the Wistar rat model for future experimental trials using RANKL inhibitor to evaluate the treatment outcome for LPS-induced rat periapical lesions.

Use of aminoguanidine, a selective inducible nitric oxide synthase inhibitor, to evaluate the role of nitric oxide in periapical inflammation.

The purpose of this study was to evaluate the effects of aminoguanidine (AG) as a selective inhibitor of inducible nitric oxide synthase (iNOS) on the degree of inflammatory response in periapical lesions in the canine teeth of cats. Root canals from 52 cat canine teeth were exposed to the oral cavity and sealed after 7 days. One day before pulp exposure, cats were administered either AG (experimental group) or normal saline (control group), which was continued on a daily basis until the day of sacrifice. Animals were sacrificed at 28 days after pulp exposure. Inflammatory response in the periapical zones was analyzed histologically. The degree of periapical inflammation in the AG group was significantly lower than that in the control group (P < 0.05). Selective iNOS inhibitors such as AG thus reduce the intensity of inflammatory responses in periapical lesions.

Endodontic treatment completion following emergency pulpectomy.

AIM: Emergency pulpectomy is frequently performed to relieve pain experienced by patients following acute episodes of endodontic pain, or to limit the risks of infection or possible root resorption following traumatic pulpal exposures. The aim of this study was to examine subsequent patient attendance for completion of root canal treatment following pulpectomy procedures in a dental emergency unit. METHODS: The treatment records of 574 patients who had each received an emergency pulpectomy at the Casualty Clinic of the University Dental School and Hospital, Cork, Ireland were reviewed. The influence of age, gender, etiology, tooth type, and month in which the pulpectomy was performed on subsequent completion of endodontic treatment was examined. RESULTS: Of 574 patients, 39% (n = 224) returned to have endodontic treatment completed, 11% (n = 63) returned to have the tooth extracted, and 50% (n = 287) did not return for completion of the endodontic treatment. Cases were monitored up to five years following pulpectomy. Using a multinomial regression model, tooth type, etiology, and month in which the treatment was performed were found to be statistically significant predictors (p < 0.05) of endodontic treatment completion in the Cork University Dental School and Hospital. CONCLUSIONS: Proper patient selection and pre-treatment counseling are important considerations when planning emergency pulpectomies to avoid inappropriate use of resources and manpower.

Protective effects of follicle-stimulating hormone inhibitor on alveolar bone loss resulting from experimental periapical lesions in ovariectomized rats.

INTRODUCTION: The direct effect of follicle-stimulating hormone (FSH) on bone resorption has been demonstrated recently. The aim of this study was to evaluate the effect of FSH inhibitor leuprorelin (LE) on alveolar bone loss resulting from experimental periapical lesions in ovariectomized (OVX) rats. METHODS: Twenty-seven female rats were randomly assigned into 4 groups and subjected to ovariectomy or sham surgery (1.6 mg/kg body weight LE or vehicle was injected immediately). One week after surgery, the pulp of each rat's bilateral lower first molars was exposed to the oral environment. Three weeks after pulpal exposure, all the animals were killed, and bilateral mandibles were extracted for histologic processing. Radiographic and histologic examination for periapical bone loss area, enzyme histochemical examination for tartrate-resistant acid phosphatase (TRAP), and immunohistochemical examination for FSH receptor (FSHR) were performed. RESULTS: LE significantly decreased the alveolar bone loss area and osteoclast occurrence compared with non-LE treatment ovariectomized rats (P < .05), and the number of FSHR-positive cells was significantly correlated with alveolar bone loss area (r = 0.796, P < .01). CONCLUSIONS: LE has protective effects on alveolar bone loss resulting from experimental periapical lesions in OVX rats.

Long term histological response of hemisectioned exposed primary pulps. An in vivo study.

UNLABELLED: THE AIM of this study was to analyze the pulp behavior 17 hemisectioned primary second mandibular molars, exposed into the oral environment. The mesial crown and root portions were extracted after 8 months and analyzed histologically. RESULTS: The cardinal signs such as pain, sensitivity and necrosis were not found in any of these teeth with the exception of one case which had a previous restoration. The formation of pulp polyps, pulp calcifications and pulp obliteration were seen as a normal physio-pathological response. CONCLUSIONS: Exposed pulps, reacted forming pulp polyps and in a similar fashion to exfoliating primary teeth but in an accelerated manner.

Immunolocalization of matrix metalloproteinases-2 and -9 during apical periodontitis development.

OBJECTIVE: The objective of this study was to determine the expression of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) during apical periodontitis development. METHODS: Using an experimental design of induced periapical lesions in rats and immunohistochemistry assay as investigative tool, the MMP-2 and MMP-9 expression and distribution were evaluated at 3, 7, 14, 21, 30, 60 and 90 days after coronary access and pulp exposure of the first left mandibular molar to the oral environment. Two blind observers scored the immunoreactivity. A semi-quantitative analysis was performed. RESULTS: Except at day 3, MMP-2 and MMP-9 immunostaining was observed in all experimental periods. The MMP-2 (p=0.004) and MMP-9 (p=0.005) immunostaining was higher in the period between 7 and 21 days. They were mainly observed in cells surrounding the apical foramen and adjacent periapical areas. Cells into the hypercementosis areas were strongly stained while both osteoblasts and osteoclasts presented discrete staining along of this study. No staining was observed on epithelial walls. At 30, 60 and 90 days, the subjacent connective tissue presented intense MMP-2 and MMP-9 immunostaining in mononuclear cells (suggestive of fibroblasts, macrophages, infiltrating neutrophils and lymphocytes). CONCLUSION: The results observed in this study suggest that MMP-2 and MMP-9 play a critical role in the development of inflammatory periapical lesions, probably involved in the extracellular matrix (ECM) degradation during the initial phase of the lesion development.

MTA pulpotomy of human permanent molars with irreversible pulpitis.

The histological success of mineral trioxide aggregate (MTA) pulpotomy for treatment of irreversible pulpitis in human teeth as an alternative treatment was investigated in this study. Fourteen molars which had to be extracted were selected from patients 16-28 years old. The selection criteria include carious pulp exposure with a history of lingering pain. After isolation, caries removal and pulp exposure, MTA was used in pulpotomy treatment. Patients were evaluated for pain after 24 h. Two patients were lost from this study. Twelve teeth were extracted after 2 months and were assessed histologically. Recall examinations confirmed that none of the patients experienced pain after pulpotomy. Histological observation revealed that all samples had dentin bridge formation completely and that the pulps were vital and free of inflammation. Although the results favour the use of MTA as a pulpotomy material, more studies with larger samples and a longer recall period are suggested to justify the use of MTA for treatment of irreversible pulpitis in human permanent teeth.