Maíra do Prado

Effect of Different Irrigation Protocols on Resin Sealer Bond Strength to Dentin

INTRODUCTION The aim of this study was to evaluate the influence of different irrigation protocols on resin-based sealer bond strength to dentin and the associated failure pattern. METHODS One hundred eighty single-rooted premolars were used. Roots were divided into 18 groups according to the irrigation protocol used and instrumented using 5.25% NaOCl or 2% chlorhexidine (CHX) gel as chemical auxiliary substances and 17% EDTA or 37% phosphoric acid for smear layer removal. Finally, CHX solution was used as the final irrigant in some groups. Root canals were filled with either gutta-percha and AH Plus (Dentsply, Petropolis, RJ, Brazil) (GP/AH) or Resilon/Real Seal SE (SybronEndo, Orange, CA). Bond strength was measured by the push-out test. Additionally, failure patterns were classified as adhesive, cohesive, and mixed. Data were statistically analyzed by Kruskal-Wallis and Mann-Whitney U tests. RESULTS In the GP/AH groups, high bond strength values were obtained when NaOCl was associated with phosphoric acid with (6.9 ± 3.9) and without (7.4 ± 3.8) a final flush with CHX. However, when CHX gel was used, the association with EDTA with (7.5 ± 3.2) and without (6.0 ± 2.3) a final flush with CHX solution showed better results. The GP/AH groups mainly showed a cohesive failure pattern. Evaluation of Resilon/Real Seal SE showed that higher bond strength values were reached when CHX was associated with phosphoric acid with (5.2 ± 3.0) and without (4.2 ± 2.0) a final flush with CHX solution. The failure patterns were mainly adhesive. CONCLUSIONS Irrigation protocols influenced the bond strength of resin sealers to dentin.

Interactions between Irrigants Commonly Used in Endodontic Practice: A Chemical Analysis

INTRODUCTION The aim of this work was to characterize the by-products formed in the associations between the most commonly used irrigants in endodontic practice through electrospray ionization quadrupole time-of-flight mass spectrometry analyses. METHODS Sodium hypochlorite (NaOCl) (0.16%, 1%, 2.5%, and 5.25%) was associated with 2% chlorhexidine (CHX) solution and gel, 17% EDTA, 10% citric acid, 37% phosphoric acid, saline solution, ethanol, and distilled water. CHX solution and gel were also associated with all above mentioned irrigants. The solutions were mixed in a 1:1 ratio, and electrospray ionization quadrupole time-of-flight mass spectrometry was used to characterize the precipitates when formed. RESULTS CHX produced an orange-brown precipitate when associated with NaOCl from 1%-5.25% and an orange-white precipitate when associated with 0.16% NaOCl. When associated with EDTA, CHX produced a white milky precipitate, and when associated with saline solution and ethanol, a salt precipitation was produced. No precipitation was observed when CHX was associated with citric acid, phosphoric acid, or distilled water. In the NaOCl associations, precipitation occurred only when CHX was present. CONCLUSION The orange-brown precipitate observed in the association between CHX and NaOCl occurs because of the presence of NaOCl, an oxidizing agent causing chlorination of the guanidino nitrogens of the CHX. The precipitates formed in the reaction of CHX with EDTA, saline solution, and ethanol were associated with acid-base reactions, salting-out process, and lower solubility, respectively. NaOCl associated with EDTA, citric acid, and phosphoric acid leads mainly to chlorine gas formation. Intermediate flushes with distilled water seem to be appropriate to prevent or at least reduce formation of by-products.

Evaluation of the interaction between endodontic sealers and dentin treated with different irrigant solutions.

INTRODUCTION Dentin surface treatment with different substances might cause alterations in chemical and structural compositions of the human dentin. The aim of this study was to investigate the wettability of endodontic sealers in contact with dentin treated with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) in the presence or absence of smear layer. METHODS Thirty-six dentin slices were used. They were irrigated with NaOCl and washed with distilled water (DW) to simulate irrigation during chemomechanical preparation. After this procedure, the samples were divided into 6 groups: group 1, DW (control); group 2, NaOCl + DW; group 3, CHX + DW; group 4, ethylenediaminetetraacetic acid (EDTA) + DW; group 5, EDTA + DW + NaOCl + DW; group 6, EDTA + DW + CHX + DW. The Ramé-Hart goniometer was used to measure the contact angle between the dentin surfaces and the AH Plus and Real Seal SE sealers. Data were statistically analyzed. RESULTS With regard to the contact angle between AH Plus and treated surfaces, the values of contact angle were lower when CHX was used, regardless of the presence or absence of smear layer. When Real Seal SE was evaluated, in the absence of smear layer, CHX presented lower values of contact angle. In the presence of smear layer, the use of NaOCl and CHX did not favor the spread of the sealer. CONCLUSIONS The present study has revealed that smear layer removal and final flush with CHX favor the wettability of AH Plus and Real Seal SE sealers.

Effect of disinfectant solutions on the surface free energy and wettability of filling material.

INTRODUCTION Gutta-percha (GP) and Resilon (Res) cones are usually disinfected by the use of solutions such as sodium hypochlorite (NaOCl) and chlorhexidine (CHX). The aims of this study were to evaluate the surface free energy of GP and Res cones after disinfection procedures and to investigate the wettability of endodontic sealers in contact with these surfaces. METHODS GP and Res flat smooth surfaces were prepared. Thirty-six samples of each material were used. The samples were divided into 6 groups as follows: Control group GP, immersed in Milli-Q water (MQW); CHX group GP, immersed in 2% CHX solution and then washed with MQW; NaOCl group GP, immersed in 5.25% NaOCl and then washed with MQW; Control group Res, immersed in MQW; CHX group Res, immersed in 2% CHX solution and then washed with MQW; and NaOCl group Res, immersed in 5.25% NaOCl and then washed with MQW. Samples were analyzed first with a goniometer to measure the contact angle between the test surfaces and 3 solutions (water, ethylene glycol, and diiodomethane) to determine the surface free energy. Then the contact angle between surfaces and each one of the sealers tested, AH Plus and Real Seal SE, was measured. Data were statistically analyzed. RESULTS The results showed that when disinfectant solutions were used, the surface free energy was greater. When evaluating the interaction between materials and sealers, the use of CHX presented lower values of contact angle, followed by NaOCl. CONCLUSIONS It was concluded that the solutions used in decontamination increase the surface free energy, promoting high interaction between GP/Res and sealers.

Evaluation of different irrigation protocols concerning the formation of chemical smear layer.

The aim of this work was to evaluate, by means of scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS), the different irrigation protocols concerning the formation of chemical smear layer (CSL). Fifty‐five teeth were instrumented by using distilled water (DW) as irrigant. Next, the teeth were submitted to a protocol for removal of the mechanical smear layer produced. The teeth were divided into 11 groups, according to irrigation regimen. Then, the teeth were prepared and analyzed with SEM and EDS. Only in Group 1 [1 mL sodium hypochlorite (NaOCl) + 10 mL DW + 1 mL chlorhexidine (CHX) solution], Group 2 [1 mL NaOCl + 10 mL DW + 1 mL ethylenediaminetetraacetic acid (EDTA) + 10 mL DW + 1 mL CHX solution], and Group 3 [1 mL NaOCl + 10 mL DW + 1 mL citric acid (CA) + 10 mL DW + 1 mL CHX solution], the formation of CSL was observed. In the groups where CHX gel was used alone or in association with EDTA, CA, phosphoric acid (PA), and CHX solution, no formation of CSL was observed. According to the results found in the cases in which one wants to associate NaOCl with CHX, the protocol using PA (1 mL NaOCl + 10 mL DW + 1 mL PA + 10 mL DW + 1 mL CHX solution) did not induce formation of CSL. Microsc. Res. Tech., 2013.

Effect of Disinfection Solutions on the Adhesion Force of Root Canal Filling Materials

INTRODUCTION Sodium hypochlorite (NaOCl) and chlorhexidine (CHX) are usually used to disinfect gutta-percha (GP) and Resilon (Res) cones. This study investigated the adhesion force (Fad) between root canal sealers and GP and Res cones following different disinfection protocols by using atomic force microscopy. METHODS Nine flat surfaces of each material were obtained with medium points of GP and Res. The samples were divided into 6 groups (n = 3): control group GP, immersion in distilled water (DW); NaOCl group GP, immersion in 5.25% NaOCl and then washing with DW; CHX group GP, immersion in 2% CHX and then washing with DW; control group Res, immersion in DW; NaOCl group Res, immersion in 5.25% NaOCl and then washing with DW; and CHX group Res, immersion in 2% CHX and then washing with DW. Atomic force microscopy tips containing AH Plus sealer were used to obtain force versus distance curves regarding GP surfaces. Fad was calculated from the force curves. The same procedure was performed with Real Seal SE and Res surfaces. Data were statistically analyzed. RESULTS A higher Fad between solid filling materials (GP and Res) and root canal sealers was found when CHX solution was used. Treatment with NaOCl solution did not show influence on the Fad values. CONCLUSIONS The decontamination of GP and Res with 2% CHX resulted in higher Fad values. The use of CHX in the disinfection process of GP and Res cones might be a better option before root canal obturation.

Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants

Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. Objectives : The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. Material and Methods : The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Results : Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Conclusion : Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution).

Correlation between Endodontic Infection and Periodontal Disease and Their Association with Chronic Sinusitis: A Clinical-tomographic Study

Introduction The proximity of the roots of maxillary posterior teeth to the maxillary sinus floor can be associated with the development of chronic maxillary sinusitis (CMS). Therefore, this study evaluated the correlation between the presence of endodontic infection and periodontal disease in maxillary posterior teeth and the presence of CMS. Methods A total of 83 patients (159 maxillary sinuses) were selected and underwent clinical dental examination to assess tooth mobility and pulp condition. In addition, cone‐beam computed tomography was performed to evaluate the presence of periapical lesion and periodontal bone loss, and measure the distance from the root apex to the cortical of the maxillary sinus. The maxillary sinuses were divided into 2 groups: CMS and no maxillary sinusitis. Data were analyzed using χ2 test and binary logistic regression analysis (P < .05). Results Periodontal disease was positively associated with CMS, leading to a 3.45‐fold higher association between these disorders (P < .05). CMS was significantly more common in patients with periodontal disease or endodontic infection in close proximity with the maxillary sinus. Periodontal disease or endodontic infection that was more distant from the maxillary sinus was more common in patients with no maxillary sinusitis (P < .05). To the extent that the tooth is more distant from the maxillary sinus floor, the chance of presenting CMS is reduced up to 2.5‐fold (P < .05). Conclusion Periodontal disease and proximity to the maxillary sinus are more common in cases of CMS, requiring a dental assessment and cone‐beam computed tomography evaluation in patients with CMS with ineffective treatment.

Effect of Intermediate Flush Using Different Devices to Prevent Chemical Smear Layer Formation

This study compared the effect of intermediate flush with distilled water delivered by conventional irrigation, EndoVac microcannula or Self-Adjusting File (SAF) system in the prevention of chemical smear layer (CSL) formation. Thirty human premolars were used. Canals were prepared with Reciproc system and 5.25% NaOCl. After chemomechanical preparation, samples were divided in 3 groups (n=10) according to the intermediate irrigation protocol with distilled water using: conventional irrigation, EndoVac microcannula or SAF. A final flush with 2% chlorhexidine solution was used and scanning electron microscopy was performed to assess protocol effectiveness. Two calibrated evaluators attributed scores according the presence or absence of CSL on the surface of the root canal walls at the coronal, middle and apical thirds, as follows: (1) no CSL; (2) small amounts of CSL; (3) moderate CSL; and (4) heavy CSL. Differences between protocols were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Friedman and Wilcoxon signed rank tests were used for comparison between each root canal third. SAF resulted in less formation of CSL when compared with the conventional irrigation and EndoVac microcannula (p<0.05). When root canal thirds were analyzed, conventional irrigation and EndoVac groups showed less CSL formation at coronal and middle thirds in comparison to the apical third (p<0.05). In SAF group, there was no difference among the thirds (p>0.05). It may be concluded that an intermediate flush of distilled water, delivered by the SAF system resulted in a better reduction of CSL formation during chemomechanical preparation.