Roberta Kochenborger Scarparo

Dentin Bond Strength of Two Mineral Trioxide Aggregate–based and One Epoxy Resin–based Sealers

INTRODUCTION This study aimed at evaluating the bond strength to root dentin of 2 mineral trioxide aggregate (MTA)-based sealers (Endo-CPM sealer and MTA Fillapex) and of 1 epoxy resin-based sealer (AH Plus sealer). METHODS Forty-five extracted human teeth with single roots were prepared by using the step-back technique. Irrigation with 2.5% NaOCl and a final rinse with 17% ethylenediaminetetraacetic acid and distilled water were performed. Canals were filled by using Endo-CPM sealer, MTA Fillapex, or AH Plus sealer by means of the gutta-percha lateral condensation technique. After 7 days, the roots were sectioned perpendicularly to its long axis, and the push-out test was carried out. The data were analyzed by using the Kruskal-Wallis and Dunn post hoc tests. RESULTS Endo-CPM sealer showed the highest values of bond strength to root dentin (8.265 MPa) (P < .05). The values of push-out test were similar for MTA Fillapex (2.041 MPa) and AH Plus (3.034 MPa). CONCLUSIONS On the basis of the findings presented herein and within the limitations of this study, Endo-CPM sealer presented advantages when a post preparation was required. MTA Fillapex presented acceptable resistance to dislodgement, which was similar to that observed in samples filled with AH Plus sealer.

Mineral Trioxide Aggregate–based Sealer: Analysis of Tissue Reactions to a New Endodontic Material

INTRODUCTION The aim of this study was to evaluate the subcutaneous connective tissue reaction to mineral trioxide aggregate (MTA)-based sealer (Endo CPM Sealer; CPM Sealer; EGEO SRL, Buenos Aires, Argentina), MTA, and an epoxy resin-based sealer (AH Plus; Dentsply HERO Indústria e Comércio Ltda, Petrópolis, RJ, Brazil). METHODS Polyethylene tubes containing the test materials and empty tubes (control group) were implanted in the subcutaneous tissue of 18 rats. After 7, 30, and 60 days, observations were made for cellular inflammatory components, fibrous condensation, and abscess formation. Comparisons between groups and periods of time were made using the Friedman test and the Kruskall-Wallis test. RESULTS Lymphocytes and plasmacytes were more intensely observed in the reaction to AH Plus sealer after 30 days (p < 0.05). MTA and the Endo CPM Sealer presented a behavior similar to that of the control group throughout the whole experiment. CONCLUSION The Endo CPM Sealer presented biological potential. Characteristics of the inflammatory reaction were equivalent to those produced by MTA.

Response to Intracanal Medication in Immature Teeth with Pulp Necrosis: An Experimental Model in Rat Molars

INTRODUCTION The present study aimed at developing an experimental model in rat molars for evaluating treatment strategies in necrotic immature teeth. METHODS To define the periods to be adopted in the experimental procedures and to confirm induction of periapical lesions and interruption of root embryogenesis, the left lower first molars of 4-weeks-old Wistar rats underwent pulpectomy and were left open to the oral environment. Comparisons with the right lower first molars (vital teeth) were performed in animals with ages of 7, 10, 13, and 16 weeks. In another group of animals the teeth were left open for 3 weeks, and then interventions for disinfection including the use of an antibiotic paste were carried out. Root formation was then assessed after 3 and 6 weeks on the basis of radiographic and histologic evaluation. RESULTS Vital teeth showed increase of root length and hard tissue thickness throughout the experimental periods. On the other hand, induction of necrosis arrested root formation. Teeth subjected to disinfection with sodium hypochlorite associated with the triple antibiotic paste showed significant reduction of periapical lesions, gain in root length, and increased wall thickness compared with the control (P < .05). CONCLUSIONS The root canal disinfection protocol used was able to reduce periapical lesion size and improve root development. The experimental model presented should contribute to studies that aim at improving therapeutic strategies for necrotic immature teeth by using a rat model.

Apical periodontium response to enamel matrix derivative as an intracanal medication in rat immature teeth with pulp necrosis: radiographic and histologic findings.

INTRODUCTION The aim of this study was to evaluate the enamel matrix derivative (EMD) biomaterial in nonvital immature teeth. METHODS To arrest root development, pulpectomies were performed in the lower first molars of 36 4-week-old rats; the cavities were left exposed to the oral environment for 3 weeks. Then, chemical disinfection was performed, and triple antibiotic paste (TAP) or EMD was applied in the root canals. A control group did not receive any treatment. Radiographic and histological data were evaluated after 3 and 6 weeks. RESULTS At 3 weeks, TAP promoted a milder inflammatory response and increased root lengths compared with the control group. At 6 weeks, root development and reduced periapical lesions could be observed in both test groups, mainly because of the deposition of a cementum-like tissue. EMD promoted narrower canals compared with TAP (P < .05). CONCLUSIONS EMD deserves attention as a potential tool in the treatment of nonvital immature teeth. The ingrowth of cementum-like tissues into canal spaces favored dental wall thickness and may contribute to tooth resistance and support.

Effect of betamethasone on the pulp after topical application to the dentin of rat teeth: vascular aspects of the inflammation

Objective: This study investigated the pulpal effect of topically applied betamethasone to the dentin of rat molars in the vascular phase of inflammation. Material and Methods: Deep cavities were prepared on the occlusal face of the maxillary right and left 1st molars with non-refrigerated inverted-cone steel burs at low speed. Three groups were formed: Group I was composed of right 1st molars; Group II was composed of left 1st molars that received the application of a drop of betamethasone on dentin surface for 5 min; and Group III (control) was composed of right 2nd molars that received no cavity preparation or betamethasone application. Changes in the vascular characteristics of the pulp tissue were checked by calculating the pulp vascular area in relation to its total area and the number of blood vessels per unit area. Data were subjected to ANOVA and Tukeys test (α=0.05). Results: Group I presented a significantly larger number of vessels (p<0.05) than Group II. Regarding the vascular/total area ratio (%), Group I presented statistically significantly higher values (p=0.01) than Groups II and III. Conclusion: Betamethasone applied on the dentin of rat teeth proved to reduce the vascular phase of pulp inflammation regarding vessel diameter and number of blood vessels.

Histologic evaluation and immunohistochemical localization of STRO-1 and BMP-4 in rat immature teeth: A comparison between vital and induced pulp necrosis

OBJECTIVE To assess histological features and the expression of STRO-1 and BMP-4 in dental pulp and periapical tissues in vital or necrotic rat immature teeth. DESIGN The lower left first molars of male Wistar rats ageing four weeks (n=24) had their pulps exposed to the oral environment for 3, 6, 9 and 12 weeks (animals ageing 7, 10, 13 and 16 weeks-old, respectively; n=24). The right lower first molars served as control untouched teeth. After sample harvesting the jaws were dissected and processed for histology and immunodetection of STRO-1 and BMP-4. RESULTS Necrotic teeth had root development arrested, while control animals showed development of dental tissues. Immunohistochemistry showed that detection of BMP-4 was restricted to vital pulps. For both groups, STRO-1 expression was evident around blood vessels walls. Neither BMP-4 nor STRO-1 was observed in the apical papilla region. CONCLUSION STRO-1-positive precursor cells were not detected in the apical papilla. BMP-4 expression has not been detected during infection.

Microflora associated with primary endodontic infections: Correlations among sem evaluation, clinical features, and radiographic findings

The aim of the present study was to characterize, by means of SEM, primary endodontic infections and to correlate with clinical and radiographic findings. Twelve (12) human extracted teeth (19 roots) presenting primary endodontic infection were examined. SEM qualitative observations of bacterial and defense cells, their features and distribution within the root canal lumen and root dentine were recorded for association with clinical and radiographic tabled data. Although a direct correlation between biofilm composition and clinical/radiographic findings was not established, structural organization and distribution of the biofilm, as well as the characteristics of host response, could be easily related to those features. Bacterial biofilm was predominant at the apical third. Symptomatic apical periodontitis was related to presence of bacterial biofilm all thirds. Defense cells could be seen in the apical third of some samples. These cells were present in all thirds in some of the cases with open cavities. The correlations performed in this study allowed a better understanding of the picture of primary endodontic infection, host response and relevant clinical features. The combined use of scanning electron microscopy with clinical and radiographic evaluation has the potential to overcome some limits of the current knowledge related to pulpal and periapical diseases, providing important insights for improving treatment strategies. Microsc. Res. Tech., 2012.

Effect of the pro-resolution lipid mediator Resolvin E1 (RvE1) on pulp tissues exposed to the oral environment.

AIM To evaluate the effects of topical Resolvin E1 (RvE1) application on infected dental pulps. METHODOLOGY Forty-two male Wistar rats (n = 6 per three groups/and two time periods) were used. To induce inflammation, pulps in mandibular right first molars were accessed and then left exposed to the oral environment for 24 h. After this period, topical medication with a corticosteroid/antibiotic blend, or RvE1, or its vehicle (Ethanol 0.1%) was directly applied onto the pulp tissue and teeth were restored with silver amalgam. The effects of the protocols were evaluated histologically and compared with control pulps not exposed to the oral environment. The inflammatory changes after 24 and 72 h were assessed through a scoring method and analysed using the Kruskal-Wallis test followed by Dunns. Differences were considered significant if P < 0.05 (CI = 95%). RESULTS Ethanol and corticosteroid/antibiotic treatment were not effective in arresting severe inflammatory alterations of exposed pulps at 24 and 72 h (P < 0.05, CI = 95%). At both time periods, RvE1 treatment led to a reduction of tissue cellularity and extent of inflammation, whose changes were not different from control pulps (P > 0.05, CI = 95%). CONCLUSIONS A protective role for RvE1 in pulp inflammation was observed even in the presence of contamination, suggesting that it may be a candidate for a novel therapeutic strategy for conservative dental pulp treatment.

SEM evaluation of thermoplastic endodontic materials alterations after disinfection: A new experimental model

This study assessed a new experimental model to analyze the effects of sodium hypochlorite solution 2.5% for 10 min and chlorhexidine 2% for 15 s on cones surface alterations. Twenty five gutta‐percha and 25 thermoplastic synthetic polymer‐based cones had their last 1 mm from the tapered end examined by scanning electron microscopy (SEM) before and after being exposed to the disinfectant solutions. To allow the surfaces to be compared, the samples were not metalized, a voltage of 1 kV was used and the images were captured within standardized angles. The samples were immersed on the test solutions. The comparison of the alterations of the cones was performed using the software program Adobe Photoshop CS. A measurement was taken of the standard deviations of the pixel intensity in this area, higher standard deviations represent more irregular areas. Differences in standard deviation before and after disinfection for each cone were compared between groups by means of analysis of variance supplemented by the Tukey test. Gutta‐percha cones showed higher standard deviations than Resilon cones (P < 0.001). In the gutta‐percha cones, sodium hypochlorite generated more irregular areas than chlorhexidine and the control group (P < 0.001). The present study has demonstrated the feasibility of using a modified SEM method. This opens opportunities to the use of new and precise tools for evaluating a sample in different moments. Microsc. Res. Tech. 74:109‐112, 2011.

QMix® irrigant reduces lipopolysacharide (LPS) levels in an in vitro model

The presence of endotoxin inside the root canal has been associated with periapical inflammation, bone resorption and symptomatic conditions. Objectives To determine, in vitro, the effect of QMix® and other three root canal irrigants in reducing the endotoxin content in root canals. Material and Methods Root canals of single-rooted teeth were prepared. Samples were detoxified with Co-60 irradiation and inoculated with E. coli LPS (24 h, at 37°C). After that period, samples were divided into 4 groups, according to the irrigation solution tested: QMix®, 17% EDTA, 2% chlorhexidine solution (CHX), and 3% sodium hypochlorite (NaOCl). LPS quantification was determined by Limulus Amebocyte Lysate (LAL) assay. The initial counting of endotoxins for all samples, and the determination of LPS levels in non-contaminated teeth and in contaminated teeth exposed only to non-pyrogenic water, were used as controls. Results QMix® reduced LPS levels, with a median value of 1.11 endotoxins units (EU)/mL (p<0.001). NaOCl (25.50 EU/mL), chlorhexidine (44.10 EU/mL) and positive control group (26.80 EU/mL) samples had similar results. Higher levels were found with EDTA (176.00 EU/mL) when compared to positive control (p<0.001). There was no significant difference among EDTA, NaOCl and CHX groups. Negative control group (0.005 EU/mL) had statistically significant lower levels of endotoxins when compared to all test groups (p<0.001). Conclusion QMix® decreased LPS levels when compared to the other groups (p<0.001). 3% NaOCl, 2% CHX and 17% EDTA were not able to significantly reduce the root canal endotoxins load.