Delayed tooth replantation after root surface treatment with sodium hypochlorite and sodium fluoride: Histomorphometric analysis in rats

In cases of delayed tooth replantation, non-vital periodontal ligament remnants have been removed with sodium hypochlorite in an attempt to control root resorption. Nevertheless, reports of its irritating potential in contact with the alveolar connective tissue have been described. Therefore, this study evaluated the healing process on delayed replantation of rat teeth, after periodontal ligament removal by different treatment modalities. Twenty-four rats, assigned to 3 groups (n=8), had their upper right incisor extracted and left on the workbench for desiccation during 60 min. Afterwards, the teeth in group I were immersed in saline for 2 min. In group II, root surfaces were scrubbed with gauze soaked in saline for 2 min; and in group III, scrubbing was done with gauze soaked in 1% sodium hypochlorite solution. Thereafter, root surfaces were etched with 37% phosphoric acid and immersed in 2% acidulate-phosphate sodium fluoride solution, at pH 5.5. Root canals were filled with a calcium hydroxide-based paste and the teeth were replanted. The animals were sacrificed 60 days postoperatively and the pieces containing the replanted teeth were processed and paraffin- embedded. Semi-serial transversally sections were obtained from the middle third of the root and stained with hematoxylin and eosin for histomorphometric analysis. Data were analyzed statistically using Kruskal-Wallis and Dunn's tests. The results showed that root structure and cementum extension were more affected by resorption in group III (p<0.05). All groups were affected by root resorption but the treatment performed in group III was the least effective for its control. The treatment accomplished in groups I and II yielded similar results to each other.

Polishing methods of an alumina-reinforced feldspar ceramic

The purpose of this study was to test the hypothesis that mechanical polishing methods of ceramic surfaces allow similar superficial roughness to that of glazed surfaces. Twenty-five Vitadur Alpha ceramic discs (5 mm x 2 mm) were prepared according to the manufacturer's specifications. All specimens were glazed and randomly assigned to 5 groups (n=5), according to finishing and polishing protocols: G1: glazed (control); G2: diamond bur finishing; G3: G2 + silicon rubber tip polishing; G4: G3 + felt disc/diamond polishing paste; G5: G3 + felt disc impregnated with fine-particle diamond paste. Next, surface roughness means (Ra - μm) were calculated. Qualitative analysis was made by scanning electron microscopy. Surface roughness data were submitted to ANOVA and Tukey's test at 5% significance level. G1 and G4 were statistically similar (p>0.05). G2 presented the highest roughness means (p<0.05) followed by groups G3, G5, G4 and G1 in a decreasing order. The hypothesis was partially confirmed as only the mechanical polishing (G4) produced similar superficial roughness to that of surface glazing, although finishing and polishing are technically critical procedures.

Resistência à compressão do concreto autoadensável: Influência da atividade pozolânica do calcário e do basalto

This research studies the influence of the pozzolanic activity of the calcareous and basalt in the resistence behavior of the compressive strength of high performance self-compacting concrete (HPSCC). The selected aditives are the calcareous filler and basalt filler, for they are industrial residues helping that way the sustainable development. The paste of this concrete type is constituted of cement, silica fume, calcareous filler or basalt filler, water and superplasticizer additive. In this research the relationships water/cement are fixed in 0,40 kg/kg, silica fume/cement of 0,10 kg/kg and the relationships filler/cement and superplasticizer/cement are determined through of Marsh́s cone and mini-slump tests. The granular skeleton is gotten from a composition between quartzous sand and brita of basalt that presents the lesser index of emptinesses. The results show that the HPSCC with the addition of calcareous filler has greater compressive strength than what the HPSCC with addition of basalt filler in the ages of 7, 28 and 63 days. It is explained by the fact that the calcareous filler presents greater index of pozzolanic activity than the basalt filler. Besides that the relation water/fine for the HPSCC with calcareous filler is 0,27 l/kg whereas the HPSCC with basalt filler is of 0,29 l/kg.

Residual antibacterial activity of chlorhexidine digluconate and camphorated p-monochlorophenol in calcium hydroxide-based root canal dressings

The purpose of this study was to evaluate the residual antibacterial activity of several calcium hydroxide [Ca(OH) 2]-based pastes, placed in root canals of dogs' teeth with induced chronic periapical lesions. Root canals were instrumented with the ProFile rotary system and filled with 4 pastes: G1 (n=16): Ca(OH) 2 paste + anesthetic solution; G2 (n=20): Calen® paste + camphorated pmonochlorophenol (CMCP); G3 (n=18): Calen®; and G4 (n=18): Ca(OH) 2 paste + 2% chlorhexidine digluconate. After 21 days, the pastes were removed with size 60 K-files and placed on Petri plates with agar inoculated with Micrococcus luteus ATCC 9341. Pastes that were not placed into root canals served as control. After pre-diffusion, incubation and optimization, the inhibition zones of bacterial growth were measured and analyzed by Mann-Whitney U test at 5% significance level. All pastes showed residual antibacterial activity. The control samples had larger halos (p<0.05). The mean residual antibacterial activity halos in G1, G2, G3 and G4 were 7.6; 10.4; 17.7 and 21.4 mm, respectively. The zones of bacterial growth of G4 were significantly larger than those of G1 and G2 (p<0.05). In conclusion, regardless of the vehicle and antiseptic, all Ca(OH) 2-based pastes showed different degrees of measurable residual antibacterial activity. Furthermore, unlike CMCP, chlorhexidine increased significantly the antibacterial activity of Ca(OH) 2.

In vitro assessment of pulp chamber temperature of different teeth submitted to dental bleaching associated with LED/laser and halogen lamp appliances

This study sought to assess the pulp chamber temperature in different groups of human teeth that had been bleached using hydrogen peroxide gel activated with halogen lamps or hybrid LED/laser appliances. Four groups of ten teeth (maxillary central incisors, mandibular incisors, mandibular canines, and maxillary canines) were used. A digital thermometer with a K-type thermocouple was placed inside pulp chambers that had been filled with thermal paste. A 35% hydrogen peroxide-based red bleaching gel was applied to all teeth and photocured for a total of three minutes and 20 seconds (five activations of 40 seconds each), using light from an LED/laser device and a halogen lamp. The temperatures were gauged every 40 seconds and the data were analyzed by three-way ANOVA, followed by Tukey's test. Regardless of the light source, statistically significant differences were observed between the groups of teeth. The mean temperature values (±SD) were highest for maxillary central incisors and lowest for mandibular canines. The halogen lamp appliance produced more pulp chamber heating than the LED/laser appliance. The increase in irradiation time led to a significant increase in temperature.

Root surface treatment with vitamin C in tooth replantation: microscopic study in rats

AIM: Late tooth replantation is a worthy procedure, especially in growing patients, being the best option for tooth avulsion. This study evaluated the effects of root surface treatment with 2% acidulated phosphate sodium fluoride and effervescent vitamin C (Redoxon) in late replantation. METHODS: Twenty rat teeth (Rattus norvegicus, albinus, Wistar) were extracted and left on a table for 6 h. Then, the dental papilla and enamel organ were sectioned and the pulp was removed through the apex. After removal of the periodontal ligament with a blade, the animals were divided into 2 groups: Group I teeth were immersed in 2% acidulated phosphate sodium fluoride solution for 10 min and obturated with Ca(OH)(2) paste. Group II teeth were immersed in effervescent vitamin C solution (Redoxon 2 g) for 10 min and obturated as for Group I. After these procedures, teeth were replanted and animals were killed after 60 days. RESULTS: The study revealed a larger amount of replacement resorption in Group I and larger amount of ankylosis in Group II, with statistically significant difference and absence of inflammatory resorption. CONCLUSION: The substances used for root surface treatment were unable to prevent replacement resorption and ankylosis, which are expected when the periodontal ligament has been lost.

Voltammetry of mercury (II) based on an organo-clay modified graphite electrode

Organo-clay complex of ligand-hexadecyltrimethylammonium with montmorillonite was made for the purpose of application as a preconcentration agent in a chemically modified carbon paste electrode for determination of mercury (II) in aqueous solution. It was found out that the adsorption of Hg(II) by organo-clay complex is independent of the pH of the solution. It was also found out that the adsorption of the remaining metals Cd(II), Ps(II), Cu(II), Zn(II), and Ni(II) was dependent on the changes in pH solutions and increased when it varies from 1 to 8. The resultant material was characterized by cyclic and differential pulse anodic voltammetry using a modified graphite paste electrode in different supporting electrolytes. The mercury response was evaluated with respect to pH, electrode composition, preconcentration time, mercury concentration, possible interferences and other variables.

Antimicrobial activity of endodontic sealers based on calcium hydroxide and MTA.

The aim of this study was to evaluate the antimicrobial activity of a new root canal sealer containing calcium hydroxide (Acroseal) and the root canal sealer based on MTA (Endo CPM Sealer), in comparison with traditional sealers (Sealapex, Sealer 26 and Intrafill) and white MTA-Angelus, against five different microorganism strains. The materials and their components were evaluated after manipulation, employing the agar diffusion method. A base layer was made using Müller-Hinton agar (MH) and wells were made by removing agar. The materials were placed into the wells immediately after manipulation. The microorganisms used were: Micrococcus luteus (ATCC9341), Staphylococcus aureus (ATCC6538), Pseudomonas aeruginosa (ATCC27853), Candida albicans (ATCC 10231), and Enterococcus faecalis (ATCC 10541). The plates were kept at room temperature for 2 h for prediffusion and then incubated at 37 degrees C for 24 h. The results showed that Sealapex and its base paste, Sealer 26 and its powder, Endo CPM Sealer and its powder, white MTA and its powder all presented antimicrobial activity against all strains. Intrafill and its liquid presented antimicrobial activity against all strains except P. aeruginosa and Acroseal was effective only against M. luteus and S. aureus.

The influence of the mixing time in the rheological behavior of cement pastes

Rheology has the purpose to study the flux and deformation of materials when submitted to some tension or outer mechanical solicitation. In practice, the effective scientific field broached by rheology is restricted only to the study of homogeneous fluids behavior, in which are included eminent liquids, particles suspensions, and emulsions. The viscosity (η) and the yield stress (τ 0) are the two basic values that define the fluids' behavior. The first one is the proportionality constant that relates the shear rate (γ) with the shear stress (τ) applied, while the second indicates the minimal tension for the flowage beginning. The fluids that obey the Newton's relation - Newtonians fluids - display the constant viscosity and the null yield stress. It's the case of diluted suspensions and grate amount of the pure liquids (water, acetone, alcohol, etc.) in which the viscosity is an intrinsic characteristic that depends on temperature and, in a less significant way, pressure. The suspension, titled Cement Paste, is defined as being a mixture of water and cement with, or without, a superplasticizer additive. The cement paste has a non-Newtonian fluid behavior (pseudoplastic), showing a viscosity that varies in accord to the applied shear stress and significant deformations are obtained from a delimited yield stress. In some cases, systems can also manifest the influence of chemical additives used to modify the interactions fluid/particles, besides the introduced modifications by the presence of incorporated air. To the cement paste the rheometric rehearsals were made using the rheometer R/S Brookfield that controls shear stress and shear rate in accord to the rheological model of Herschel-Bulkley that seems to better adapt to this kind of suspension's behavior. This paper shows the results of rheometrical rehearsals on the cement paste that were produced with cements HOLCIM MC-20 RS and CPV-ARI RS with the addition of superplasticizer additives based of napthaline and polycarboxilate, with and without a constant agitation of the mixture. The obtainment of dosages of superplasticizer additives, as well as the water/cement ratio, at the cement at the fluidify rate determination, was done in a total of 12 different mixtures. It's observed that the rheological parameters seem to vary according to the cement type, the superplasticizer type, and the methodology applied at the fluidity rate determination.

Efeito de um quelante de cálcio, um detergente e da lecitina de soja sobre a qualidade do sêmen caprino congelado-descongelado

The aim of this paper was verifying the effect of the Equex STM Paste and EDTA addition to a Tris-egg yolk extender, on the postthaw goat sperm viability. Nine semen samples of two adult goats were collected by artificial vagina and cryopreserved. It was also objective of this study, to evaluate the utilization of a soybean lecithin based commercial extender (Bioexcell® - IMV, L'Aigle, French) for the goat semen freezing. They were formed five experimental groups: TRIS; TRIS+EDTA; TRIS+EQUEX; TRIS+EDTA+EQUEX e Bioexcell. After evaluation, the semen was diluted in the five extenders and packed in 0.25mL straws with 100 million of motile spermatozoa. The samples were cooled at 0,46°C/min to 5°C, submitted at 75min of equilibration time and frozen in liquid nitrogen vapour. The thawing was accomplished in 37°C water bath for 50s. There were no differences (P>0,05) on the means of post-thaw total and progressive sperm motility among the groups TRIS, TRIS+EQUEX and TRIS+EQUEX+EDTA. The Bioexcell group obtained the least (P<0,05) percentage of post-thawing total and progressive sperm motility. After the thermotolerance test, it was observed the greatest (P<0,05) rates of total and progressive sperm motility in the Equex STM groups (TRIS+EQUEX and TRIS+EQUEX+EDTA). Thus, it can be affirmed that the Equex addition promotes better maintenance rates in the pos-thaw sperm viability, when compared with the extenders that did not contain it.

Streptococcus mutans attachment on a cast titanium surface

This study examined by means of scanning electron microscopy (SEM), the attachment of Streptococcus mutans and the corrosion of cast commercially pure titanium, used in dental dentures. The sample discs were cast in commercially pure titanium using the vacuum-pressure machine (Rematitan System). The surfaces of each metal were ground and polished with sandpaper (#300-4000) and alumina paste (0.3 μm). The roughness of the surface (Ra) was measured using the Surfcorder rugosimeter SE 1700. Four coupons were inserted separately into Falcon tubes contained Mueller Hinton broth inoculated with S. mutans ATCC 25175 (109 cuf) and incubated at 37 °C. The culture medium was changed every three days during a 365-day period, after which the falcons were prepared for observations by SEM. The mean Ra value of CP Ti was 0.1527 μm. After S. mutans biofilm removal, pits of corrosion were observed. Despite the low roughness, S. mutans attachment and biofilm formation was observed, which induced a surface corrosion of the cast pure titanium.

Effects of mandibular fixed implant-supported prostheses on masticatory and swallowing functions in completely edentulous elderly individuals

Purpose: To evaluate the effect of oral rehabilitation with immediately loaded fixed implant-supported mandibular prostheses on chewing and swallowing in elderly individuals. Materials and Methods: Fifteen completely edentulous patients aged more than 60 years (10 women and rive men), wearing removable dentures in both arches, had a mandibular denture replaced by an implant-supported prosthesis. All individuals were evaluated before surgery and again 3, 6, and 18 months later with regard to mastication and swallowing conditions. Examinations entailed an interview, evaluation of tactile sensitivity of the face, and observation of food intake, masticatory type, formations of bolus, and pain during mastication. The swallowing evaluation comprised observation of clinical signs related to the oral and pharyngeal stages of swallowing, as well as the presence of oral residue. The findings of different evaluations before and 3, 6, and 18 months after the surgical-prosthetic procedure were statistically compared by analysis of variance for repeated measurements at a significance level of 5%. Results: The questionnaire revealed a reduction in complaints of masticatory and swallowing disturbances, a decreased need for liquid ingestion, and reduced choking and coughing. Clinical evaluations showed improved oral function and bolus propulsion for both solid and paste-consistency foods; pain during mastication was also resolved. Conclusion: Treatment with mandibular implant-supported dentures had positive effects on the clinical aspects of mastication and swallowing in elderly individuals.

Biocompatibility of acetazolamide pastes in the subcutaneous tissue of rats

This aim of this study was to investigate the biocompatibility of two experimental acetazolamide (AZ)-based pastes in the subcutaneous tissue of rats. Both pastes contained AZ as the main component in similar concentration. The vehicle in experimental paste 1 was saline, while experimental paste 2 was prepared with propylene glycol. Sixty polyethylene tubes were sealed at one end with gutta-percha (GP), which served as a control. Half of the tubes were flled with paste 1 and half with paste 2. The tubes were implanted in the subcutaneous tissue of 15 rats, being 4 tubes for each animal. The animals were killed 7, 15 and 45 days after surgery and the specimens were processed in laboratory. The histological sections were stained with hematoxylin and eosin and were analyzed by light microscopy. Scores were assigned to level of infammatory process: 1- none; 2- mild; 3- moderate; 4- severe. The data were analyzed statistically by the Kruskal-Wallis test (p≤0.05). Paste 1 produced an infammatory process at 7 days. However, the intensity of this infammation decreased with time and was nearly absent at 45 days. No statistically signifcant difference (p>0.05) was observed between the control (GP) and paste 1. However, paste 2 produced infammatory response at all study periods and differed signifcantly (p<0.05) from the control. In conclusion, in the present study, the experimental AZ-based paste 1 was considered as biocompatible as the control matrial (GP), while experimental paste 2 was irritating to rat subcutaneous tissue.

Evaluation of the diffusion capacity of calcium hydroxide pastes through the dentinal tubules

This study aimed to evaluate the diffusion capacity of calcium hydroxide pastes with different vehicles through dentinal tubules. The study was conducted on 60 extracted single-rooted human teeth whose crowns had been removed. The root canals were instrumented and divided into 4 groups according to the vehicle of the calcium hydroxide paste: Group I - distilled water; Group II - propylene glycol; Group III - 0.2% chlorhexidine; Group IV - 2% chlorhexidine. After placement of the root canal dressings, the teeth were sealed and placed in flasks containing deionized water. After 1, 2, 7, 15, 30, 45 and 60 days, the pH of the water was measured to determine the diffusion of calcium hydroxide through the dentinal tubules. The data were recorded and statistically compared by the Tukey test. The results showed that all pastes presented a similar diffusion capacity through dentin. Group IV did not present difference compared to group I. Group II presented difference compared to the other groups, as did Group III. In conclusion, groups I and IV presented a better diffusion capacity through dentin than groups II and III; 2% chlorhexidine can be used as a vehicle in calcium hydroxide pastes. © 2009 Sociedade Brasileira de Pesquisa Odontológica.

The effect of chloride ions and A. ferrooxidans on the oxidative dissolution of the chalcopyrite evaluated by electrochemical noise analysis (ENA)

It is believed that the dissolution of chalcopyrite (CuFeS2) in acid medium can be accelerated by the addition of Cl- ions, which modify the electrochemical reactions in the leaching system. Electrochemical noise analysis (ENA) was utilized to evaluate the effect of the Cl- ions and Acidithiobacillus ferrooxidans on the oxidative dissolution of a CPE-chalcopyrite (carbon paste electrode modified with chalcopyrite) in acid medium. The emphasis was on the analysis of the admittance plots (Ac) calculated by ENA. In general, a stable passive behavior was observed, mainly during the initial stages of CPE-chalcopyrite immersion, characterized by a low passive current and a low dispersion of the Ac plots, mainly after bacteria addition. This can be explained by the adhesion of bacterial cells on the CPE-chalcopyrite surface acting as a physical barrier. The greater dispersions in the Ac plots occurred immediately after the Cl- ions addition, in the absence of bacteria characterizing an active-state. In the presence of bacteria the addition of Clions only produced some effect after some time due to the barrier effect caused by bacteria adhesion. © (2009) Trans Tech Publications.