Kamila Rosamilia Kantovitz

Effect of sodium hypochlorite on dentine mechanical properties. A review.

OBJECTIVES The aim of this study was to carry out a review on the effect of sodium hypochlorite (NaOCl) on the mechanical properties of root dentine. DATA/SOURCES The authors searched the Cochrane Library, Embase, PubMed and the Web of Science for papers published from 1984 to 2008. The main search terms used were: dentine, root canal dentine, sodium hypochlorite, mechanical analysis, elastic modulus, hardness, roughness, flexural strength, compressive strength. STUDY SELECTION The inclusion criteria were studies that evaluated the effect of NaOCl solution, used as an irrigant in endodontics, on the mechanical properties of root dentine. Those studies that were considered to be unrelated to the question addressed, that had investigated NaOCl as a deproteinizing agent, had not evaluated the effect of NaOCl on the mechanical properties of dentine, and that indirectly verified the effect of NaOCl on endodontically treated teeth were excluded. The selected papers were assigned to a score (A-C), according to predetermined criteria. A total of 16 papers were selected, and nine papers were included in the critical appraisal. Five papers were classified as grade A, 4 as grade B, and no paper was classified as grade C. CONCLUSIONS Based on this review, the authors suggest that there is strong evidence showing that sodium hypochlorite adversely alters the mechanical properties of root dentine, when used as an endodontic irrigant.

Inhibition of mineral loss at the enamel/sealant interface of fissures sealed with fluoride- and non-fluoride containing dental materials in vitro

Objective. In this in vitro study we evaluated the enamel mineral loss effect of fluoride-containing and non-fluoride-containing materials at different distances from the sealant margin, and verified the fluoride-releasing capability of these materials. Material and methods. Extracted molars were randomly assigned into nine groups (n=12): Concise (C), FluroShield (F), Helioseal Clear Chroma (H), Vitremer (V), Fuji II-LC (FII), Ketac Molar (KM), Fuji IX (FIX), Single Bond (SB), and Clearfil Protect Bond (CF). All groups were subjected to thermo and pH cycling. Enamel mineral loss was evaluated by cross-section micro-hardness analysis at distances: −100 µm, 0 µm, 100 µm, 200 µm. The mineral loss data were analyzed using a multi-factor ANOVA with split-plot design, and fluoride-released data were submitted to ANOVA and Tukey tests. Results. FIX demonstrated a lower mineral loss than C, F, and H, but did not differ from the SB, CF, V, FII, and KM groups, which also demonstrated no difference among them. C, F, H, and V presented the highest mineral loss, with no difference among them. V did not differ from the other groups (p>0.05). Regarding the different distances from the sealant margin, −100 µm presented the lowest mineral loss. FIX showed the highest fluoride release on the 7th and 14th days of evaluation, while CF showed high fluoride release only on the 7th day. Conclusion. Resin sealant did not prevent enamel mineral loss, contrary to glass-ionomer cement, which showed the highest capacity for fluoride release. It is not exclusively the presence of fluoride in a materials composition that indicates its capability to interfere with the development of enamel caries-like lesions.OBJECTIVE In this in vitro study we evaluated the enamel mineral loss effect of fluoride-containing and non-fluoride-containing materials at different distances from the sealant margin, and verified the fluoride-releasing capability of these materials. MATERIAL AND METHODS Extracted molars were randomly assigned into nine groups (n = 12): Concise (C), FluroShield (F), Helioseal Clear Chroma (H), Vitremer (V), Fuji II-LC (FII), Ketac Molar (KM), Fuji IX (FIX), Single Bond (SB), and Clearfil Protect Bond (CF). All groups were subjected to thermo and pH cycling. Enamel mineral loss was evaluated by cross-section micro-hardness analysis at distances: -100 microm, 0 microm, 100 microm, 200 microm. The mineral loss data were analyzed using a multi-factor ANOVA with split-plot design, and fluoride-released data were submitted to ANOVA and Tukey tests. RESULTS FIX demonstrated a lower mineral loss than C, F, and H, but did not differ from the SB, CF, V, FII, and KM groups, which also demonstrated no difference among them. C, F, H, and V presented the highest mineral loss, with no difference among them. V did not differ from the other groups (p > 0.05). Regarding the different distances from the sealant margin, -100 microm presented the lowest mineral loss. FIX showed the highest fluoride release on the 7th and 14th days of evaluation, while CF showed high fluoride release only on the 7th day. CONCLUSION Resin sealant did not prevent enamel mineral loss, contrary to glass-ionomer cement, which showed the highest capacity for fluoride release. It is not exclusively the presence of fluoride in a materials composition that indicates its capability to interfere with the development of enamel caries-like lesions.

Influence of environmental conditions on properties of ionomeric and resin sealant materials

Objectives: The aim of this study was to determine the effect of environmental conditions on the degradation of ionomeric and resin sealant materials. Material and Methods: FluroShield, Vitremer, and Ketac Molar disc-shaped specimens (n=18/material) were prepared, polished, subjected to initial hardness and roughness readings. Six discs of each material were randomly assigned to one of three different storage solutions: 0.3% citric acid (CA), demineralization solution (DE), and remineralization solution (RE). The specimens were individually immersed in 3 mL of the test solutions, which were daily changed. After 15 days of storage, new surface roughness and hardness readings were done. Fluoride release in the solutions was measured within 15 days. Data were analyzed by ANOVA and Tukeys and Contrast tests (α=0.05). Results: The storage in CA increased the roughness of Vitremer and Ketac Molar. A significant reduction in hardness was observed for all materials after storage in all solutions. For all materials, the greatest amounts of fluoride release occurred during the 1st day. FluroShield presented the same patterns of fluoride release in all solutions. Ketac Molar and Vitremer released the highest amounts of fluoride in the CA solution. Conclusions: Ionomeric materials are more susceptible to degradation than resin-based materials under acidic conditions. Acidic conditions lead to a higher fluoride release from ionomeric materials.

Impact of smoking on experimental gingivitis. A clinical, microbiological and immunological prospective study.

OBJECTIVE The present study assessed the effect of smoking on clinical, microbiological and immunological parameters in an experimental gingivitis model. MATERIAL AND METHODS Twenty-four healthy dental students were divided into two groups: smokers (n = 10); and nonsmokers (n = 14). Stents were used to prevent biofilm removal during brushing. Visible plaque index (VPI) and gingival bleeding index (GBI) were determined 5- on day -7 (running phase), baseline, 21 d (experimental gingivitis) and 28 d (resolution phase). Supragingival biofilm and gingival crevicular fluid were collected and assayed by checkerboard DNA-DNA hybridization and a multiplex analysis, respectively. Intragroup comparison was performed by Friedman and Dunns multiple comparison tests, whereas the Mann-Whitney U-test was applied for intergroup analyses. RESULTS Cessation of oral hygiene resulted in a significant increase in VPI, GBI and gingival crevicular fluid volume in both groups, which returned to baseline levels 7 d after oral hygiene was resumed. Smokers presented lower GBI than did nonsmokers (p < 0.05) at day 21. Smokers had higher total bacterial counts and higher proportions of red- and orange complex bacteria, as well as lower proportions of Actinomyces spp., and of purple- and yellow-complex bacteria (p < 0.05). Furthermore, the levels of key immune-regulatory cytokines, including interleukin (IL)-8, IL-17 and interferon-γ, were higher in smokers than in nonsmokers (p < 0.05). CONCLUSION Smokers and nonsmokers developed gingival inflammation after supragingival biofilm accumulation, but smokers had less bleeding, higher proportions of periodontal pathogens and distinct host-response patterns during the course of experimental gingivitis.

Effect of gamma irradiation on fluoride release and antibacterial activity of resin dental materials

This study evaluated the effect of gamma irradiation on fluoride release and antibacterial activity of FluroShield (FS) and Clearfil Protect Bond (CPB). Four groups were formed: G1-FS + gamma; G2-FS without gamma; G3-CPB + gamma; G4-CPB without gamma. For fluoride release analysis, 12 disks of each material were prepared and covered with nail polish, except for one side (50.4 mm(2) area). G1 and G3 were sterilized with a 14.5 KGy dose at 27 degrees C for 24 h, while G2 and G4 (controls) were not sterilized and were maintained under the same time and temperature conditions. Fluoride release measurements were made in duplicate (n=6) by an ion specific electrode. The antibacterial activity of the CPB and FS against Streptococcus mutans after gamma sterilization was evaluated by the agar-disc diffusion method. The diameter of the zones of microbial growth inhibition was recorded after 48 h. Data were analyzed statistically by ANOVA and Tukeys test (alpha=5%). Gamma sterilization decreased the fluoride release of FS by approximately 50%, while CPB was not affected. There was no statistically significant difference (p>0.05) in the antibacterial effect of CPB between gamma and non-gamma sterilization groups. FS presented no antibacterial activity. Gamma irradiation decreased the fluoride release of FS, but did not affect the antibacterial activity of the studied materials.

Neuropilin Controls Endothelial Differentiation by Mesenchymal Stem Cells From the Periodontal Ligament

BACKGROUND Periodontal ligament (PDL) has been reported to be a source of mesenchymal stem cells (MSCs).New vascular networks from undifferentiated cells are essential for repair/regeneration of specialized tissues, including PDL. The current study aims to determine potential of CD105(+)-enriched cell subsets of periodontal ligament cells (PDLSCs) to differentiate into endothelial cell (EC)-like cells and to give insights into the mechanism involved. METHODS CD105(+)-enriched PDLSCs were induced to EC differentiation by endothelial growth medium 2 (EGM-2) for 3, 7, 14, and 21 days, with mRNA/protein levels and functional activity assessed by: 1) real-time polymerase chain reaction; 2) Western blotting; 3) fluorescence-activated cell sorting; 4) immunohistochemistry; 5) immunofluorescence; 6) matrigel; and 7) small interfering RNA assays. RESULTS Data analyses demonstrated that EGM-2 treated PDLSCs presented increased expression of EC markers, including: 1) CD105; 2) kinase domain-containing receptor; and 3) Ulex europaeus agglutinin 1, and were able to form cord/tube-like structures. Gene and protein expression analysis showed that neuropilin 2 (NRP2), a key factor for vascular development, was significantly downregulated during EC differentiation. NRP2 was constitutively expressed in mouse PDL tissues by immunohistochemistry analysis, and NRP2 knockdown in CD105(+)-enriched PDLSCs resulted in increased cord/tube-like structures in a matrigel assay. CONCLUSION These findings demonstrated the potential of CD105(+)-enriched PDLSCs to support angiogenesis, and NRP2 as a pivotal factor regulating this process.

Skin fibroblasts from individuals with Chediak-Higashi Syndrome (CHS) exhibit hyposensitive immunogenic response

BackgroundChediak-Higashi Syndrome (CHS) is a rare autosomal recessive disease characterized by immunodeficiency, oculocutaneous albinism, neurological dysfunction, and early death. Individuals with CHS present with increased susceptibility to infections of the skin, upper-respiratory tract, gastrointestinal tract, and oral tissues. Classical CHS is caused by mutations in the gene encoding lysosomal trafficking regulator (LYST). Although defects in cytotoxic T cell lytic secretory granule secretion and neutrophil phagocytosis are suggested to contribute to the immunodeficiency in CHS, the underlying molecular mechanisms are unknown. We hypothesized that skin fibroblasts from CHS subjects exhibit impaired immune response due to defective trafficking of inflammatory factors.Methods and resultsPrimary skin fibroblasts from CHS subjects or healthy controls were assessed for genes encoding inflammatory response factors using PCR array. At baseline, we found CD14, IL1R1 and TLR-1 were down-regulated significantly (≥2 fold change) and the genes encoding TLR-3, IL-1β and IL-6 were up-regulated in CHS cells compared to control cells. When challenged with E. coli lipopolysaccharide (LPS), CHS cells were less responsive than control cells, with only 8 genes significantly up-regulated (3–68 fold change) compared to baseline values, whereas 28 genes in control cells were significantly up-regulated at a much higher magnitude (3–4,629 fold change). In addition, 50% of the genes significantly up-regulated in LPS-treated control cells were significantly lower in LPS-treated CHS cells. IL-6, a fibroblast-derived proinflammatory cytokine essential for fighting infections was significantly lower in culture media of CHS cells with or without LPS. Furthermore, Western blot and immunofluorescent staining revealed that TLR-2 and TLR-4 were diminished on cell membranes of CHS cells and dissociated from Rab11a.ConclusionsFor the first time, results from our study indicate defective trafficking of TLR-2 and TLR-4 contributes to the hyposensitive response of CHS skin fibroblasts to immunogenic challenge, providing a potential therapeutic target for clinical intervention in CHS.

Effects of Chemical Agents on Physical Properties and Structure of Primary Pulp Chamber Dentin

This study evaluated the effects of chemical agents on the physical properties and structure of primary pulp chamber dentin using surface roughness, microhardness tests, and scanning electron microscopy (SEM). Twenty‐five primary teeth were sectioned exposing the pulp chamber and were divided into five groups (n = 5): NT, no treatment; SH1, 1% sodium hypochlorite (NaOCl); SH1U, 1% NaOCl + Endo‐PTC®; SH1E, 1% NaOCl + 17% EDTA; and E, 17% EDTA. After dentin treatment, the specimens were submitted to roughness, microhardness testing, and SEM analysis. Roughness and microhardness data were submitted to one‐way ANOVA and Tukeys test (P < 0.05). The SH1E group showed the highest roughness, followed by the E group (P < 0.05) when compared with the NT, SH1, and SH1U groups. Microhardness values of SH1 and SH1U showed no significant difference as compared to the NT (control) group (P > 0.05). Microhardness values could not be obtained in the EDTA groups (SH1E and E). The presence of intertubular dentin with opened dentin tubules was observed in the NT, SH1, and SH1U groups. SH1E showed eroded and disorganized dentin with few opened tubules and the intertubular/peritubular dentin was partially removed. Considering the physical and structural approaches and the chemical agents studied, it can be concluded that NaOCl and NaOCl associated with Endo‐PTC® were the agents that promoted the smallest changes in surface roughness, microhardness, and structure of the pulp chamber dentin of primary teeth. Microsc. Res. Tech. 77:52–56, 2014.

Computational analysis for GNAQ mutations: New insights on the molecular etiology of Sturge-Weber syndrome

Somatic activating mutations in the GNAQ have been recently associated with several congenital genetic disorders and tumors; however, the molecular mechanism/etiology that leads to GNAQ somatic mosaic mutation are unknown. Here, we reported a case of Sturge-Weber Syndrome (SWS) manifesting cutaneous vascular malformations (hemifacial Port-wine stain), cerebral and ocular vascular abnormalities (including epilepsy and glaucoma) and harboring a c.548G>A (p.R183Q) somatic mosaic mutation in GNAQ. Computational modeling studies were performed to assistant with the comprehension of the functional impact of p.R183Q and p.Q209L mutations in GNAQ, which encodes a G protein subunit alpha q (Gαq). The p.R183Q mutation was predicted to abolish hydrogen bonds between R183 residue and GDP molecule, destabilizing the inactive GDP-bound conformation of the Gαq mutants. Furthermore, replacement of R183 by Q183 residue was predicted to promote conformation changes in protein surface features affecting the switch I region, a key region that undergoes conformational changes triggered by receptor binding during signal transduction. In addition, replacement of Q209 by L209 residue was predicted to affect the molecular interaction between Gαq and Gβ subunit, impairing formation of the inactive heterotrimeric complex. These findings, in association with PPI network analysis, indicate that p.R183Q and p.Q209L mutations result in the over-activation of different downstream effectors, which in turn will determine the distinct cell responses and phenotype. These findings bring new insights on molecular etiology of vascular malformations associated to SWS and on different mechanisms underlying hyperactivation of downstream pathways to Gαq.

Influence of Different Enamel Substrates on Microtensile Bond Strength of Sealants After Cariogenic Challenge

PURPOSE To evaluate the microtensile bond strength (μTBS) of resin sealer on enamel substrates after cariogenic challenge. MATERIALS AND METHODS Enamel blocks were obtained from human third molars and randomly divided into 6 groups (n = 10) according to enamel substrates (S: sound, CL: caries-like lesion, or CLTF: caries-like lesion + topical fluoride application) and sealant material (F: FluroShield, or H: Helioseal Clear Chroma). Sealants were placed on enamel surfaces, stored in 100% humidity (24 h, 37°C), and longitudinally sectioned into hourglass shapes. According to the groups, pH cycling was applied and the μTBS test was performed. The fracture patterns were assessed by SEM. RESULTS Regarding substrates, the highest μTBS values in MPa were observed for CLTF enamel (26.0 ± 7.6), followed by S (22.0 ± 7.4) and CL (15.5 ± 4.9). A significant interaction was found between material and pH cycling (p = 0.0395). F (23.9 ± 7.6) showed higher μTBS values than H (18.3 ± 7.5) when submitted to pH cycling. The majority of samples presented mixed failure. CONCLUSIONS Enamel substrate significantly affected μTBS, with the highest values for remineralized caries-like enamel lesions. Furthermore, μTBS values were dependent on both materials and pH cycling.