Marília Pacífico Lucisano

MyD88 knockout mice develop initial enlarged periapical lesions with increased numbers of neutrophils.

AIM To characterize the formation and progression of experimentally induced periapical lesions in teeth of MyD88 knockout (MyD88 KO) mice compared with wild-type (WT) mice. METHODOLOGY Periapical lesions were induced in the mandibular first molars of 30 WT and 30 MyD88 KO mice. After 7, 21 and 42 days, the animals were euthanized and the mandibles were subjected to histotechnical processing. Histological sections were stained with haematoxylin and eosin (HE), TRAP histoenzymology, Brown and Brenn staining and immunohistochemistry (RANK, RANKL, OPG). Data were subjected to statistical analysis by the nonparametric Mann-Whitney and Kruskal-Wallis tests and the Dunn post-test, using the SPSS software, version 17.0 (α = 0.05). RESULTS Regarding the periapical lesion size, the MyD88 KO group had significantly higher values than the WT group in the periods of 7 (P = 0.001) and 21 days (P = 0.05). A larger number of neutrophils in the MyD88 KO group were observed (P = 0.01 at 7 days, P = 0.004 at 21 days and P < 0.001 at 42 days). Regarding the number of osteoclasts, no statistically significant difference was observed between the groups at any of the experimental periods (P = 0.884 at 7 days, P = 0.506 at 21 days and P = 0.211 at 42 days). CONCLUSIONS In the absence of MyD88, the animals had larger periapical lesions, with a severe inflammatory infiltrate and a significantly larger number of neutrophils.

Systemically Alendronate was Incorporated Into Dental Tissues but did not Cause Morphological or Mechanical Changes in Rats Teeth

This study evaluated the effect of the systemic use of sodium alendronate in rats in vivo. Forty‐five Wistar rats aged 36 to 42 days and weighing 200 to 230 g were randomly assigned to a control group (n = 20), which received distilled water, and an experimental group (n = 25), which received 2 weekly doses of 1 mg/kg of chemically pure sodium alendronate. The animals were killed after 60 days of treatment. The tibias were removed for analysis of bone mineral density by dual‐energy X‐ray absorptiometry (DXA). Then, the maxillary incisors were extracted for analysis of the mineralized dental tissues using fluorescence spectroscopy (FS), scanning electron microscopy (SEM), bright field microscopy (BFM), and cross‐sectional microhardness (CSMH) testing. DXA and CSMH data were subjected to statistical analysis by Kruskal‐Wallis test (5% significance level). The experimental group presented higher bone mineral density than the control group by DXA. FS analysis revealed presence of alendronate in the mineralized dental tissues of the specimens of the experimental group. Significant morphological differences were not found by SEM and BFM. Enamel and dentin (100 and 300 μm from the dentinoenamel junction) CSMH data did not show significant difference between the control and experimental groups. Based on the obtained results, we conclude that while alendronate increased the bone mineral density and was incorporated into the mineralized dental tissues it did not cause significant alterations in the morphology and microhardness of rat incisor enamel and dentin. Microsc. Res. Tech. 75:1265–1271, 2012.

Furcation Perforation: Periradicular Tissue Response to Biodentine as a Repair Material by Histopathologic and Indirect Immunofluorescence Analyses

Introduction: The purpose of this study was to evaluate the in vivo response of periradicular tissues after sealing of furcation perforations with Biodentine, mineral trioxide aggregate (MTA), and gutta‐percha by means of histopathologic and indirect immunofluorescence analyses. Methods: Thirty teeth of 3 dogs were divided into 3 groups: Biodentine (n = 14 teeth), MTA (negative control, n = 10 teeth), and gutta‐percha (positive control, n = 6 teeth). After endodontic treatment, perforations were made on the center of the pulp chamber floor and filled with the materials. After 120 days, the animals were killed, and blocks containing the teeth and periradicular tissues were processed histotechnically for histopathologic semiquantitative (new mineralized tissue formation and bone resorption at the perforation site) and quantitative (thickness and area of newly formed mineralized tissue and number of inflammatory cells) analyses and RUNX2 immunofluorescence assay. Data were analyzed by χ2, Fisher exact test, Mann‐Whitney test, one‐way analysis of variance, Kruskal‐Wallis test, and Dunn posttest (&agr; = 0.05). Results: MTA and Biodentine induced the formation of significantly more new mineralized tissue (P < .0001) than gutta‐percha, which did not induce the formation of mineralized tissue in any case. Complete sealing of the perforations was more frequent with MTA, which formed mineralized tissue with greater thickness and area. Biodentine and MTA exhibited no bone resorption in the furcation region, fewer inflammatory cells, and greater RUNX2 immunostaining intensity than gutta‐percha. Conclusions: Although MTA presented higher frequency of complete sealing and greater thickness and area of newly formed mineralized tissue, Biodentine also had good histopathologic results and can be considered as an adequate furcation perforation repair material. HighlightsThis is the first study that demonstrated the histopathologic response of periradicular tissues to Biodentine for sealing furcation perfurationsBiodentine induced new mineralized tissue formation after furcation perfurations.Biodentine could be an option for furcation perfuration repair.

Dental findings and special care in patients with Angelman syndrome: a report of three cases

Angelman syndrome (AS) is a neurogenetic disorder, characterized by intellectual disability, movement or balance disorders, specific abnormal behaviors, and severe speech and language limitations. Due to its low incidence and the nonspecifity of developmental problems in newborns and young children, AS is not easily identified by clinical pediatricians. The aim of this paper is to present three cases of AS, reporting the orofacial characteristics and requisite dental care in these patients. Interestingly, this investigation found that certain typical features of mouth breathing syndrome, such as long and narrow faces, open mouth, shortened upper lip, lowered mandible position, shadows under the eyes (infraorbital cyanosis), muscular hypotonia, and enlarged and anteriorized tongue, were present in the three studied AS patients.

Radiodensitometric and DXA analyses for the measurement of bone mineral density after systemic alendronate therapy

Precise techniques for the measurement of maxillary bone mineral density (BMD) are useful for the early diagnosis of systemic diseases. The aim of this study was to compare in vivo the efficacy of dual-energy x-ray absorptiometry (DXA) and radiographic densitometry for the measurement of BMD after systemic administration of sodium alendronate. Wistar rats were randomly allocated to a control group (n = 5), which received distilled water, and a sodium alendronate group (n = 8), which received two doses of chemically pure sodium alendronate (1 mg/kg) per week. After 8 weeks, the animals were euthanized, the tibias were removed, and the BMD of the proximal tibial metaphysis was analyzed radiographically and by DXA. The data were subjected to statistical analysis by the Kruskal-Wallis test at a significance level of 5%. Both of the techniques revealed that the alendronate-treated group had a significantly higher BMD (p < 0.05) than the control group after 8 weeks of treatment. Comparing the groups with and without alendronate therapy revealed increases of 14.9% and 29.6% in BMD, as detected radiographically and by DXA, respectively. In conclusion, both of the methods were able to detect an increase in BMD of the proximal tibial metaphysis after alendronate therapy.

Microbial contamination and disinfection methods of pacifiers

Objectives To evaluate the microbial contamination of pacifiers by Mutans Streptococci (MS) and the efficacy of different methods for their disinfection. Methods Twenty-eight children were assigned to a 4-stage changeover system with a 1-week interval. In each stage, children received a new pacifier and the parents were instructed to maintain their normal habits for 1 week. After this time, the pacifiers were subjected to the following 4 disinfection methods: spraying with 0.12% chlorhexidine solution, Brushtox® or sterile tap water, and immersion in boiling tap water for 15 minutes. Microbiological culture for MS and Scanning Electron Microscopy (SEM) were performed. The results were analyzed statistically by Friedman’s non-parametric test (a=0.05). Results The 0.12% chlorhexidine spray was statistically similar to the boiling water (p>0.05) and more effective than the Brushtox® spray and control (p<0.05). The analysis of SEM showed the formation of a cariogenic biofilm in all groups with positive culture. Conclusions Pacifiers become contaminated by MS after their use by children and should be disinfected routinely. Spraying with a 0.12% chlorhexidine solution and immersion in boiling water promoted better disinfection of the pacifiers compared with a commercial antiseptic toothbrush cleanser (Brushtox®).

Stepwise Excavation Allows Apexogenesis in Permanent Molars with Deep Carious Lesions and Incomplete Root Formation

This study evaluated the stepwise excavation technique in 138 permanent molars with deep carious lesions and incomplete root formation within a 24-month clinical and radiographic follow-up period. In 96.7% of the cases, success was observed (no pain, integrity of restoration margins, absence of radiographic alterations and apexogenesis). The cases of failure (3.3%) were due to the loss of the temporary restoration. In conclusion, the stepwise excavation is a promising technique for permanent teeth with deep carious lesions and incomplete root formation as a minimally invasive approach because it allows the preservation of pulp vitality and occurrence of apexogenesis.

Radiotherapy Activates and Protease Inhibitors Inactivate Matrix Metalloproteinases in the Dentinoenamel Junction of Permanent Teeth

The objectives of this study were to investigate changes in the activity and expression of matrix metalloproteinase (MMP)-2 and MMP-9 in permanent teeth with or without exposure to radiotherapy, and the role of proteinase inhibitors in their inactivation. In situ zymography and immunofluorescence assays were performed to evaluate the activity and expression of two key gelatinases (MMP-2 and MMP-9) in sections of permanent molars, assigned to irradiated and nonirradiated subgroups. Dental fragments were exposed to radiation at a dose of 2 Gy fractions for 5 consecutive days until a cumulative dose of 60 Gy was reached. To evaluate the effect of protease inhibitors on MMPs, teeth were immersed in 0.5 mL of 0.12% chlorhexidine digluconate (CHX), 0.05% sodium fluoride (NaF), 400 μM polyphenol epigallocatechin-3-gallate (EGCG), or distilled water (control) for 1 h. Fluorescence in the dentinoenamel junction (DEJ) was evaluated in 3 areas of the tooth: cervical, cuspal, and pit. These regions were photographed using a fluorescence microscope at 1.25× and 5× magnifications. Results were analyzed using the D’Agostino-Person normality test, and the Kruskal-Wallis, Dunn, and Wilcoxon tests for intergroup and paired comparisons (α = 0.05). The fluorescence intensity/mm2 in the DEJ at the three regions studied was higher in the irradiated teeth (p < 0.05) than in the nonirradiated teeth, revealing regions of expression of MMP-2 and MMP-9 by immunofluorescence. Postradiotherapy treatment with different solutions (CHX, NaF, and EGCG) led to lower fluorescence intensity/mm2 in irradiated teeth than in the control group (distilled water; p < 0.05), as a result of MMP inactivation. In conclusion, irradiation increased gelatinase activity in all regions of the DEJ. Treatment with 0.12% CHX, 0.05% NaF, and 400 μM polyphenol EGCG postradiotherapy inactivated enzyme activity.

Ovariectomy Exacerbates Apical Periodontitis in Rats with an Increase in Expression of Proinflammatory Cytokines and Matrix Metalloproteinases

Introduction: The aim of this study was to evaluate the gene expression of proinflammatory cytokines, matrix metalloproteinases (MMPs), and cathepsin K in apical periodontitis (AP) and the volume of lesions in ovariectomized and sham‐operated rats. Methods: Twenty 12‐week‐old female Wistar rats were subjected to ovariectomy (OVX) or sham surgery. After 9 weeks, access cavities were prepared in the maxillary and mandibular first molars, pulp tissue was removed, and canals were exposed to the oral environment during 21 days for the induction of AP. The groups were as follows: sham, OVX, sham+AP, and OVX+AP. Animals were euthanized, and blocks containing the maxillary first molar and the surrounding bone were removed for quantification of proinflammatory cytokines cathepsin K and MMP genes by real‐time polymerase chain reaction. The hemimandibles containing the mandibular first molars were used for analysis of the AP lesion volume by micro–computed tomographic imaging. Results: AP in OVX rats showed an increased expression of interleukin 1 beta, tumor necrosis factor alpha, interleukin 6, MMP‐8, and MMP‐13 (P < .05). OVX alone, without AP induction, did not affect the expression of the evaluated genes. Additionally, AP induced an increase in cathepsin K expression, without significant differences between AP in the sham and OVX groups (P > .05). Micro–computed tomographic imaging showed a significantly greater AP lesion mean volume in OVX compared with sham animals (P < .05). Conclusions: AP lesions in ovariectomized rats are larger and have an increased expression of proinflammatory cytokines and MMPs, indicating that the infection combined with ovariectomy has an important role in the regulation of these signaling molecules and enzymes during the development of AP. Based on that, it may be assumed that the hypoestrogenic condition aggravates inflammation and degradation of extracellular matrix components in AP, which may provide insight into understanding the development of AP in female postmenopausal patients. HIGHLIGHTSFew studies evaluated apical periodontitis (AP) in OVX animals; none evaluated AP volume.Little attention has been given to the mediators that regulate this process.No study has assessed the role of matrix metalloproteinases (MMPs).This study was the first to evaluate proinflammatory cytokines and MMPs in AP of OVX rats.The hypoestrogenic condition aggravates inflammation and MMP expression in AP.Insight was provided into understanding AP in female postmenopausal patients.

MMP2 and MMP9 are Associated with Apical Periodontitis Progression and Might be Modulated by TLR2 and MyD88

The aim of this study was to evaluate the expression of MMP2 and MMP9 during apical periodontitis (AP) progression in TLR2 (TLR2 KO) and in MyD88 (MyD88 KO) knockout mice compared to wild type (WT) mice. AP was induced in mandibular first molars of TLR2 KO (n= 18), MyD88 KO (n= 18), and WT mice (n= 18). After 7, 21, and 42 days, the animals were euthanized and the jaws were dissected and subjected to histotechnical processing. Subsequent sections were stained by immunohistochemistry and evaluated for detection of MMP2 and MMP9. Statistical analysis of the semi-quantitative analysis of immunohistochemistry was performed using chi-square test (α = 0.05). In the initial periods of AP progression, an increased expression of MMP9 in the TLR2 KO and MyD88 KO mice was observed. In the final periods of AP progression, a reduction of MMP2 expression and an increase of MMP9 expression in the TLR2 KO mice were observed. MMP2 and MMP9 production was modulated for TLR2 and MyD88 during apical periodontitis progression.