Daiana Elisabeth Böttcher

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.

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.

Effect of calcium hydroxide dressing on the long-term sealing ability of two different endodontic sealers: An in vitro study

OBJECTIVE The aim of this in vitro study was to evaluate the long-term sealing ability of Real Seal system and Endofill after calcium hydroxide (CH) dressing, by using a fluid filtration model. STUDY DESIGN Four randomized groups of single-rooted teeth (N=110) were prepared using a crown-down technique to a size 50 file. Two groups (1 and 2) received CH dressing before filling. Roots were filled with gutta-percha and Endofill (groups 2 and 4) or Resilon and Real Seal (groups 1 and 3). Leakage was measured by using the fluid filtration method after 90 days and determined as microL/min.10 psi. RESULTS Statistical analysis by Kruskal-Wallis and Mann-Whitney tests indicated that CH dressing groups showed higher leakage values than those where CH was not used (P=.001). CONCLUSION It may be concluded that the use of CH as an intracanal dressing material affected the sealing ability of both Real Seal and Endofill sealers.

Evaluation of bone tissue response to a sealer containing mineral trioxide aggregate.

INTRODUCTION This study analyzed bone tissue reactions to MTA Fillapex (Ângelus Industria de Produtos Odontológicos Ltda, Londrina, Brazil) compared with an epoxy resin-based material in the femur of Wistar rats. METHODS Bone tissue reactions were evaluated in 15 animals after 7, 30, and 90 days (n = 5 per period). Three surgical cavities were prepared on the femur and filled with 0.2 mL MTA Fillapex, AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany), or no sealer (negative control). By the end of each experimental period, 5 animals were randomly euthanized. The samples were histologically processed and analyzed using a light microscope. The presence of inflammatory cells, fibers, and hard tissue barrier formation was evaluated. Differences among the groups and between the 3 experimental periods were evaluated by using 2-way analysis of variance followed by the Bonferroni post hoc test (P ≤ .05). RESULTS MTA Fillapex scored significantly higher for neutrophils at 7 days than at 90. At 7 days, the same occurred when comparing MTA Fillapex with AH Plus. The presence of lymphocytes/plasmocytes significantly decreased over time in all groups. Macrophages, giant cells, eosinophils, and fiber condensation presented no differences among groups and periods. Within 90 days, all groups presented complete hard tissue barrier formation. CONCLUSIONS The presence of mineral trioxide aggregate in MTA Fillapex composition did not improve the bone tissue repair. The presence of sealers provided the re-establishment of the original bone tissue structure and the inflammatory response decreased over time, so they can be considered biocompatible.

Evaluation of the Effect of Enterococcus faecalis Biofilm on the 2% Chlorhexidine Substantivity: An In Vitro Study

INTRODUCTION The aim of this study was to correlate the bacterial viability and the presence of 2% chlorhexidine (CHX) solution on dentin by means of confocal laser scanning microscopy and high-performance liquid chromatography for 48 hours, 7 days, and 30 days. METHODS One hundred twenty-three extracted human teeth were used. Samples were divided into 4 groups according to the solution (CHX or saline) and the presence of Enterococus faecalis biofilm. Samples were kept in contact with 5 mL of the solution for 5 minutes. Each group was divided into 3 subgroups according to the evaluation period (n = 10). Statistical analysis was performed by using the Kruskal-Wallis test, the Mann-Whitney U test (P < .05), and the Spearman rank correlation coefficient (P < .01). RESULTS There was a negative correlation between the percentage of live cells and the amount of remaining CHX (P = .000). CHX significantly reduced the percentage of viable cells compared with saline after 48 hours (P = .007). Differences were maintained in the 7-day evaluation period (P = .001). After 30 days, the CHX group presented an increase of viable cells, thereby becoming similar to saline (P = .623). Simultaneously, the remaining CHX was significantly reduced in the 30-day specimens (P = .000). CONCLUSIONS The results of this study indicate that 2% CHX solution was detected for 48 hours and 7 days with a low percentage of viable cells. The presence of microorganisms on human dentin did not affect 2% CHX maintenance.

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.

Response of E. faecalis biofilms to different associations of auxiliary substances during root canal preparation: A confocal laser microscopy analysis

Objective: This in vitro study evaluated the effect of different endodontic auxiliary chemical substances over Enterococcus faecalis (Ef) biofilm through confocal laser scanning microscopy (CLSM). Methods: Forty‐five bovine incisors were infected with Ef for 21 days. Teeth were divided into five groups: group 1: 2.5% NaOCl + EDTA, group 2: 2% CHX gel + EDTA, group 3: 2% CHX liquid + EDTA, group 4: 2.5% NaOCl + 2% CHX gel + EDTA, group 5: 2.5% NaOCl + 2% CHX liquid + EDTA and a negative and a positive control group (NCG; PCG). The samples were stained with SYTO9 and propidium iodide and analyzed by CLSM. Bacterial viability was quantitatively analyzed by the proportions of dead and live bacteria in the biofilm remnants. Scores were standardized according to the total bacterial load (TBL)—1: ≤25%, 2: >25 ≤50%, 3: >50 ≤75%, 4: >75% and debris—1: absence of debris; 2: presence of debris. Statistical analysis was carried out through the Kruskal–Wallis and the Fischer exact tests (P = 0.05). Results: No statistical differences were observed to CFU, debris and bacterial viability. Conclusion: None of the tested substances could completely eliminate Ef from the root canal space. Microsc. Res. Tech. 76:658–662, 2013.

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.

Confocal microscopy evaluation of the effect of irrigants on Enterococcus faecalis biofilm: An in vitro study

The purpose of this study was to evaluate in vitro the effectiveness of two endodontic irrigants and their association against Enterococcus faecalis (E. faecalis) by confocal laser scanning microscope (CLSM). Twenty-four bovine incisors were inoculated in a monoculture of E. faecalis for 21 days. After this period, the teeth were divided into three test groups (n = 5) according to the chemical used. Group 1: 2.5% sodium hypochlorite (NaOCl), group 2: 2% chlorhexidine gel (CHX), group 3: 2.5% NaOCl + 2% CHX gel, and two control groups (n = 3): negative control group (NCG)-sterile and without root canals preparation and positive control group (PCG)-saline. Then, the samples were stained with SYTO9 and propidium iodide and subjected to analysis by CLSM. Bacterial viability was quantitatively analyzed by the proportions of dead and live bacteria in the biofilm remnants. Statistical analysis was performed by the One-way ANOVA test (p = 0.05). No statistical differences were observed to bacterial viability. According to CLSM analysis, none of the tested substances could completely eliminate E. faecalis from the root canal space. Until now, there are no irrigant solutions able to completely eliminate E. faecalis from the root canal. In this regard, the search for irrigants able to intensify the antimicrobial action is of paramount importance.

Calcium hydroxide removal: Effectiveness of ultrasonic and manual techniques

OBJETIVO: Diferentes tecnicas sao propostas para melhorar a remocao da pasta de hidroxido de calcio. O objetivo do presente estudo in vitro foi comparar a efetividade das tecnicas ultrassonica e manual para a remocao do hidroxido de calcio do canal radicular. METODOLOGIA: Trinta e oito dentes monorradiculares foram divididos em dois grupos de 19 dentes cada. Os dentes foram preparados atraves da tecnica de coroa-apice ate o instrumento memoria #50. Apos o preparo, os canais foram radiografados e, entao, preenchidos com hidroxido de calcio. A remocao da pasta no grupo I foi feita com o uso do ultrassom enquanto que no grupo II, a pasta foi removida atraves da tecnica manual. Os dentes foram radiografados novamente para avaliar a remocao do hidroxido de calcio. As radiografias foram digitalizadas e os tercos avaliados de acordo com os niveis de cinza para quantificar a remocao do hidroxido de calcio. Os testes para amostras independentes e o t de Student (α=0.05) foram aplicados para comparar a remocao da pasta entre os grupos e entre os tercos do canal. RESULTADOS: Nao houve diferenca entre as tecnicas ultrassonica e manual para a remocao do hidroxido de calcio do canal radicular. Nao houve diferencas estatisticas na comparacao ente os tercos avaliados. CONCLUSAO: Nem a tecnica manual nem a ultrassonica removeram completamente o hidroxido de calcio do canal radicular.