Serum levels of inflammatory markers and HbA1c in patients with type 2 diabetes and apical periodontitis: Preliminary findings.

This pilot study assessed the glycaemic control and the serum levels of inflammatory mediators in type 2 diabetes (T2DM) patients with apical periodontitis (AP). Thirty individuals were divided into four groups: Healthy (H); with AP (AP); with T2DM (T2DM); and with T2DM and AP (T2DM-AP). Demographic and pharmacological data were registered. The body mass index (BMI) and the levels of glycated haemoglobin (HbA1c) and IL-1ß, IL-6, IL-10, CCL3 and CCL4 were evaluated. AP areas were determined radiographically. Mean age was 64 ± 12 years, with 63% females. Most T2DM patients were under treatment with metformin and antihypertensives. BMI and H1bAc were significantly higher in T2DM patients in relation to H and AP groups. The AP areas were larger in the T2DM-AP group, compared with the AP group. These preliminary findings suggest no influence of AP on glycaemic control or inflammatory levels amongst T2DM patients, although T2DM increased the AP severity.

Clinical fracture incidence of rotary and reciprocating NiTi files: A systematic review and meta-regression.

This systematic review was registered in PROSPERO (CRD42017075917) and aimed to investigate whether the available clinical evidence supports the hypothesis that reciprocating motion results in a lower incidence of nickel-titanium files fracture compared to continuous rotation. Clinical studies that reported the incidence of fracture of engine-driven nickel-titanium files were included. The main exposure was the kinematics, and the primary outcome was the incidence of files fracture. The overall incidence of files fracture was 2.27%, with a trend for higher incidence with rotary motion (2.43%) than with reciprocating (1.0%), though without significant differences. Multiple meta-regression models revealed that the use of nickel-titanium files in more than four teeth and less proficient operators were associated with a higher incidence of file fracture. There was no difference in the clinical incidence of fracture of nickel-titanium instruments between reciprocating and rotary motions; however, other factors were identified.

Dendritic cells and their relation to apical peridontitis.

The purpose of this manuscript was to re-discuss apical periodontitis, apical biofilm, and its possible relationship with dendritic cells (DC). DCs are potent regulators of the immune system and their function is divided into three categories that involve the presentation of antigens: the presentation of antigens and activation of T cells; a not well established category suggested that DCs induce and maintain immunological tolerance; and the maintenance of the immune memory in conjunction with B cells. DCs in periapical inflammatory lesions are composed of at least two subpopulations that can be distinguished on the basis of ultrastructure and phenotype. These populations might differ in lineage, state of maturation, differentiation, activation, and/or function. The authors hereby analyzed the root apexes of teeth under SEM, after performing apicoectomy due to the failure of conventional endodontic treatment. Microbial biofilm with multispecies and areas of resorption with the presence of Howship lacunae, and images suggestive of denditric cells could be observed. The presence of DCs in periapical lesion could be an indication of the severity of the lesion, with a constant presence of antigen in the periradicular region.

Cell migration, viability and tissue reaction of calcium hypochlorite based-solutions irrigants: An in vitro and in vivo study.

OBJECTIVE: This study aimed to analyze in vitro cytotoxicity to cultured 3T3 fibroblasts and in vivo inflammatory reaction in rats by calcium hypochlorite (Ca(OCl)2) solutions compared with sodium hypochlorite (NaOCl) solutions. DESIGN: Cultured 3T3 fibroblasts were exposed to different concentrations of (Ca(OCl)2) and NaOCl solutions, and a scratch assay was performed. The viability rate was analyzed with trypan blue assay. Both solutions of 1% and 2.5% concentrations were injected into the subcutaneous tissue of 18 male Wistar rats aged 18 weeks. The inflammatory tissue reaction was evaluated at 2h, 24h, and 14days after the injections. The samples were qualitatively analyzed using a light microscope. Statistical analysis was performed with ANOVA and Tukey post hoc tests for in vitro assays and Kruskal-Wallis and Dunn post hoc tests for in vivo assays (α=0.05). RESULTS: In the scratch assay, Ca(OCl)2 showed no significant difference compared with the control group (culture medium) at 24h (p<0.05). Solutions of 0.0075% and 0.005% NaOCl and Ca(OCl)2 concentrations presented similar results compared with those in the positive control group (hydrogen peroxide) (p>0.05) in the trypan blue assay. In the in vivo assay, 1% Ca(OCl)2 group showed a significant decrease in neutrophils at 2h and 24h (p=0.041) and 2h and 14days (p=0.017). There was no statistically significant difference for lymphocyte/plasmocyte and macrophage counts among the different concentration groups. CONCLUSIONS: Ca(OCl)2 showed favorable results of viability and induced a low-level inflammatory response. Ca(OCl)2 presented acceptable cytotoxicity and biocompatibility as an irrigant solution.

Comparison of curved root canals preparation using reciprocating, continuous and an association of motions.

The aim of this study was to compare the rotary ProTaper Universal system, the single-file reciprocating WaveOne system and an association of motions assessing shaping ability, cleanliness, preparation time and instrument failures after preparation of curved root canals. Sixty root canals of extracted human molar teeth, with curvatures ranging between 20° and 40°, were divided into three groups, according with preparation system. Canals were prepared until apical size 25 using the ProTaper Universal system (G1), WaveOne (G2), or a hybrid technique (G3) associating reciprocating preparation with rotary glide path and cervical pre-enlargement. Teeth were scanned pre and post-operatively using computed tomography. Direction of transportation and centering ability of canals were measured using a computer image analysis program, and the results were analyzed statistically using one-way ANOVA. Preparation time was analyzed by one-way ANOVA and the Tukey post hoc test. Instrument failures were recorded. The amounts of debris and smear layer were quantified based on a numerical evaluation scale by scanning electron microscopy and were analyzed statistically using the Kruskal-Wallis test. No difference in transportation and centering ratio was found between the systems. Instrumentation with WaveOne was significantly faster than with other instruments (p < 0.05). During preparation, no instruments fractured and three suffered deformations. For debris removal and remaining smear layer, the results for the three groups were similar. The single-file reciprocating instrument was capable of providing faster root canal preparation with similar transporting, centralization and cleaning ability when compared with continuous and an association of motions in curved canals. SCANNING 38:462-468, 2016. © 2016 Wiley Periodicals, Inc.

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.

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.

Thermocompaction decreases long-term push-out bond strength of methacrylate-based sealers.

PURPOSE: The purpose of this study was to evaluate the immediate and long-term bond strengths to root dentin of Epiphany/Resilon and AH Plus/gutta-percha fillings, after using either lateral condensation or Tagger's hybrid thermomechanical compaction techniques. MATERIALS AND METHODS: Eighty human single-rooted teeth were used. The root canals were prepared by means of hand crown-down technique up to a #45 K-file and irrigation with 1% sodium hypochlorite was performed. Samples were randomly divided into eight (n=10) experimental groups divided according to filling material (gutta-percha/AH Plus and Resilon/Epiphany), obturation technique (Lateral compaction and Tagger's hybrid thermomechanical compaction) and storage time (24 h and 6 months). During storage, the samples were kept at 37°C and 100% humidity. After the two experimental periods, each root was sectioned perpendicular to its long axis into three serial slices and push-out tests were carried out using a universal testing machine. Statistical significant differences were set by ANOVA and Tuckey post-hoc (p<0.05). RESULTS: Using thermocompaction technique, the samples filled with Epiphany/Resilon decreased significantly the bond strength after a 6 months storage-period (p<0.05) and the ones filled with AH Plus/gutta-percha presented a tendency to lower values of the push-out test, although not statistically significant. For both materials, dentin bond strength of the specimens filled by means of lateral condensation remained stable throughout the experimental periods. CONCLUSION: Under the limitations of the current study, it can be concluded that the thermocompaction technique and the storage time can influence push-out bond strength when used with methacrylate-based 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.

Resin-based sealer penetration into dentinal tubules after the use of 2% chlorhexidine gel and 17% EDTA: in vitro study

Aim: To evaluate, by confocal laser scanning microscopy (CLSM), the influence of 17% EDTA final irrigation on the penetration of an endodontic resin-based sealer into dentinal tubules after use of 2% chlorhexidine gel. Methods: Forty extracted bovine incisors were instrumented according to the groups: G1 - root canal preparation with 2% chlorhexidine gel (n=10); G2 - root canal preparation with 2% chlorhexidine gel and final irrigation with 17% EDTA (n=10); G3 - root canal preparation with saline and final irrigation with 17% EDTA (n=10); G4 - root canal preparation with saline (n=10). The samples were filled with gutta-percha using AH Plus sealer with rhodamine B fluorescent dye. After seven days, the teeth were sectioned at the coronal, middle, and apical thirds and viewed under confocal microscope. The most representative area of penetration depth was measured in each group. Statistical significance for the sealer penetration area was determined among groups using one-way ANOVA followed by Tuckey test. For thirds comparison, in each group, data were statistically analyzed using Friedman test (p<0.05). Results: The maximum penetration was provided by G2 - 2% chlorhexidine + EDTA (p=0.000). According to this criterion, no differences were found among the other groups and among thirds within the same group. Conclusions: Based on these results, the use of 17% EDTA should be indicated after root canal preparation with 2% chlorhexidine gel for smear layer removal, enhancing the AH Plus sealer penetration.

Intracanal delivery of Resolvin E1 controls inflammation in necrotic immature rat teeth.

INTRODUCTION: Pulp necrosis in immature teeth and the resulting periodontal apical inflammation negatively affect root formation. Resolvin E1 (RvE1) is a lipid-derived endogenous pro-resolution molecule that controls inflammation. The aim of this investigation was to evaluate the impact of RvE1 applied as an intracanal medication on root formation in nonvital immature teeth. METHODS: To arrest root development, pulpectomy was performed in the lower first molars of 4-week-old Wistar rats. After 3 weeks, irrigation with 2.5% sodium hypochlorite and 0.9% sterile saline was performed, and either a triple antibiotic paste (TAP) or RvE1 in saline was applied into the root canals. In the control group, access openings drilled into molars were left exposed to the oral environment. Root development and periapical repair were evaluated radiographically and histologically at 3 and 6 weeks after treatment. RESULTS: RvE1 reduced periapical lesion size compared with the control at 3 weeks, which was similar to TAP. Inflammatory response in the RvE1-treated group was markedly reduced compared with both TAP and control specimens. At 6 weeks, root development was observed in both groups, but RvE1 treatment produced less cellularity with more regular calcified tissue deposition. CONCLUSIONS: RvE1 and TAP had a positive impact on reducing inflammation and promoting root formation. RvE1 was more effective in reducing inflammation at earlier stages. RvE1 has potential to be used as root canal dressing to control inflammation in endodontically compromised teeth before complete root formation. Stability of RvE1 within the root canal and its delivery are issues to be addressed before its clinical use.

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.

Tissue reactions to a new mineral trioxide aggregate-containing endodontic sealer.

INTRODUCTION: The purpose of this study was to analyze the connective tissue reactions to MTA Fillapex (Ângelus Indústria de Produtos Odontlógicos Ltda, Londrina, Brazil) compared with a zinc oxide-based sealer (EndoFill; Dentsply Indústria e Comérico Ltda, Petrópolis, Brazil) and an epoxy resin-based material (AH Plus; Dentsply DeTrey GmbH, Konstanz, Germany) in Wistar rats. METHODS: Polyethylene tubes containing the test materials and empty polyethylene tubes (control) were implanted in the subcutaneous tissue of 12 rats. Empty tubes were used as a negative control. After 7 and 60 days (n = 6 per period), observations were made for cellular inflammatory components, fibrous condensation, and abscess formation. Comparisons among the groups and between the experimental periods were made using 2-way analysis of variance and the Bonferroni post hoc test (P < .05). RESULTS: At the end of the 7-day experimental period, all sealers scored higher than the control group for the variable lymphocytes, and MTA Fillapex presented lower fiber condensation compared with empty tubes. After 60 days, macrophages and lymphocytes scored significantly higher for MTA Fillapex and EndoFill compared with the negative control, and AH Plus showed similar results related to the empty tubes. Comparing the materials' responses at the end of the 2 evaluated periods, for EndoFill samples the variable neutrophils was detected less after 60 days. Both EndoFill and MTA Fillapex presented increased fiber condensation after 60 days. CONCLUSIONS: Although none of the sealers promoted ideal tissue responses, AH Plus presented the best outcomes. Although MTA Fillapex contains MTA powder, it presented no biocompatibility advantages when compared with AH Plus and EndoFill.

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.

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.

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.

Calcium hydroxide removal: effectiveness of ultrasonic and manual techniques / Remoção de hidróxido de cálcio: Eficácia das técnicas ultrassônica e manual

PURPOSE: Different techniques have been proposed to improve the removal of calcium hydroxide. The purpose of this in vitro study was to compare the effectiveness of ultrasound and manual techniques in the removal of calcium hydroxide from root canals. METHODS: Thirty-eight single-rooted teeth were divided into two groups of 19 teeth each. The teeth were prepared using the crown-down technique with an apical master file #50. After shaping, the canals were radiographed and dressed with calcium hydroxide. After 14 days, the calcium hydroxide was removed with the ultrasound technique in group I and through manual filing in group II. The teeth were then radiographed again to evaluate the removal of the paste. To assess the calcium hydroxide removal, the radiographs were scanned and analyzed based on the gray levels. The independent samples and Student's t-tests (α=0.05) were used for each group to compare the efficacy of calcium hydroxide removal between the groups and among thirds (cervical, middle and apical). RESULTS: There was no difference between ultrasound and manual techniques in the removal of calcium hydroxide from root canals. There were no statistical differences among the thirds analyzed. CONCLUSION: Neither manual nor ultrasonic techniques completely removed calcium hydroxide from the root canal.

OBJETIVO: Diferentes técnicas são propostas para melhorar a remoção da pasta de hidróxido de cálcio. O objetivo do presente estudo in vitro foi comparar a efetividade das técnicas ultrassônica e manual para a remoção do hidróxido de cálcio do canal radicular. METODOLOGIA: Trinta e oito dentes monorradiculares foram divididos em dois grupos de 19 dentes cada. Os dentes foram preparados através da técnica de coroa-ápice até o instrumento memória #50. Após o preparo, os canais foram radiografados e, então, preenchidos com hidróxido de cálcio. A remoção da pasta no grupo I foi feita com o uso do ultrassom enquanto que no grupo II, a pasta foi removida através da técnica manual. Os dentes foram radiografados novamente para avaliar a remoção do hidróxido de cálcio. As radiografias foram digitalizadas e os terços avaliados de acordo com os níveis de cinza para quantificar a remoção do hidróxido de cálcio. Os testes para amostras independentes e o t de Student (α=0.05) foram aplicados para comparar a remoção da pasta entre os grupos e entre os terços do canal. RESULTADOS: Não houve diferença entre as técnicas ultrassônica e manual para a remoção do hidróxido de cálcio do canal radicular. Não houve diferenças estatísticas na comparação ente os terços avaliados. CONCLUSÃO: Nem a técnica manual nem a ultrassônica removeram completamente o hidróxido de cálcio do canal radicular.

Avaliação histológica e imunolocalização de STRO-1 e BMP-4 em molares de ratos com polpa vital ou necrose pulpar induzida durante o desenvolvimento radicular / STRO-1 and BMP-4 expression in developing teeth: study in rats

Objetivo: O objetivo do presente estudo foi avaliar morfologicamente os tecidos pulpar e periapical de molares de ratos com a polpa vital e expostos ao meio bucal durante o desenvolvimento radicular, além de detectar a localização do STRO-1 e do BMP4 nos mesmos. Métodos: Foram utilizados 24 ratos machos da linhagem Wistar com quatro semanas de idade. A fim de induzir a necrose, foi realizada a exposição pulpar dos primeiros molares inferiores esquerdos em condições não-assépticas e deixando a polpa exposta ao ambiente oral (grupo teste). Os molares inferiores do lado direito não sofreram intervenção e serviram como grupo controle. A eutanásia dos animais foi realizada nos tempos de 7, 10, 13 e 16 semanas de vida (o equivalente a 3, 6, 9 e 12 semanas após a intervenção). Após, as mandíbulas foram dissecadas e processadas para a análise histológica através de Hematoxilina-Eosina e Imunohistoquímica. Foram comparadas, entre os grupos, em cada um dos períodos, a reação inflamatória periapical, as características do tecido pulpar (células inflamatórias, vascularização, odontoblastos, degeneração, destruição tecidual), fechamento do forame e presença de reabsorções. Resultados: Todos os dentes do grupo teste apresentaram necrose pulpar e a interrupção do desenvolvimento radicular. Enquanto isso, os dentes do grupo controle apresentaram o desenvolvimento normal dos tecidos dentários. Quanto à imunohistoquímica, foi constatada a marcação pelo BMP-4 no tecido pulpar dos dentes do grupo controle. Não houve, no entanto, marcação nos dentes do grupo teste. Para o STRO-1, a marcação foi mais evidente na região dos vasos sanguíneos, tanto no grupo controle, quanto no grupo teste. Para nenhum dos anticorpos, foi constatada marcação na região da papila apical. Conclusão: No presente estudo, a técnica imunohistoquímica não foi suficiente para a avaliação da presença de células-tronco na região da papila de dentes com rizogênese incompleta e necrose pulpar. É possível que...

Objective: the aim of this study was to characterize the features of live and necrotic dental pulps of molar teeth in rats with developing roots, and to assess the expression of STRO-1 and BMP-4. Methods: twenty-four 4-month-old male Wistar rats were used. To induce necrosis, the pulps of the first lower left molars were exposed to the oral environment. The lower right molars served as the control non-operated group. Euthanasia of animals was carried out at 7, 10, 13 and 16 weeks and the jaws were dissected and processed for histological analysis by hematoxylin-eosin and immunohistochemistry. The periapical inflammatory reaction, the characteristics of the pulp tissue (inflammatory cells, vascularity, odontoblasts, degeneration, tissue destruction), closure of the foramen and presence of resorptions were described at each period. Results: all teeth from the test group presented pulp necrosis, occurring discontinuation of root development. Meanwhile, the teeth of the control group showed normal development of dental tissues. BMP-4-positive cells were detected in the pulp of teeth from the control group. However, there was no expression in teeth of the test group. For STRO-1, expression was more evident in the blood vessels, both for the control group and for the test group. Apical papilla evidenced no BMP-4 nor STRO-1 expression. Conclusion: Immunohistochemistry was not sufficient to evaluate the presence of stem cells in the apical papilla region of nonvital immature teeth. It is possible that the inflammatory process has blocked the expression of STRO-1 and BMP-4., Probably, infection has negatively modulated this expression.

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.