Endodontic treatment during the COVID-19 pandemic - perception and behaviour of dental professionals / Tratamento endodôntico durante a pandemia de COVID-19 - Percepçao e comportamento dos profissionais de odontologia

ABSTRACT This study evaluated the impact of COVID-19 on the endodontic treatment routine. It was a cross-sectional study using an online questionnaire applied to endodontists to collect information about practical modifications during endodontic treatment to protect professionals and patients against the COVID-19 outbreak. A total 1105 participants from Brazil participated in the survey. More than 90% of respondents identify the high risk of COVID-19 infection to dentists and the need to change some clinical practices. Most respondents (60.1%) are partially following social isolation. The need for a change in Personal Protective Equipment (PPE) during dental appointments was mentioned by 97.1% of respondents. The use of minimal adequate PPE during the pandemic period was associated with the area of residence and marital status of participants. Only 30% of respondents say they use the minimal adequate PPE. Most respondents will change cavity access preparation to reduce virus dissemination. Other changes in endodontic appointments were described in the survey: greater attention to biosafety measures, duration of dental appointments, and duration of intervals between appointments. Endodontists still need to identify the best arrangement for performing their procedures safely during the COVID-19 pandemic. Specific guidelines require detailed information for each specialty and its procedures.

RESUMO Este estudo transversal foi realizado por meio de um questionário online. O questionário foi aplicado a endodontistas e coletou informagoes sobre modificagoes práticas durante o tratamento endodontico para combater o surto de COVID-19 e proteger profissionais e pacientes. Um total de 1105 participantes do Brasil participaram da pesquisa. Mais de 90% dos entrevistados identificam o alto risco de infecgao por COVID-19 para os dentistas e a necessidade de mudar algumas práticas clínicas. A maioria dos entrevistados (60,1%) segue parcialmente o isolamento social. A necessidade de mudangas dos Equipamentos de Protegao Individual (EPIs) durante as consultas odontológicas foi referida por 97,1% dos entrevistados. O uso de EPIs mínimos adequados durante o período pandémico foi associado á área de residencia e ao estado civil dos participantes. Apenas 30% dos participantes afirmou usar os EPIs mínimos durante a pandemia. A maioria dos entrevistados mudará a preparagao do acesso á cavidade para reduzir a disseminagao do virus. Outras mudangas nas consultas endodonticas foram descritas na pesquisa: maior atengao ás medidas de biosseguranga, duragao das consultas odontológicas e intervalos entre as consultas. Os endodontistas ainda precisam distinguir a melhor maneira para realizar seus procedimentos com seguranga, durante a pandemia de COVID-19. Diretrizes específicas requerem informagoes detalhadas para cada especialidade e seus procedimentos.

Avaliação da descontaminação de cones de guta-percha usando diferentes métodos de desinfecção / Evaluation of gutta-percha points decontamination through different disinfection methods

A suscetibilidade ao crescimento bacteriano em cones de guta-percha (GP) e a forma de descontaminação desses cones usando quatro diferentes substâncias químicas foram avaliadas. Seis cones de GP foram selecionados de um ambiente clínico e levados com pinça estéril para um meio de cultura de Brain Heart Infusion (BHI), para avaliação de crescimento bacteriano. Outros doze cones foram divididos em quatro grupos experimentais de três cones, sendo: Grupo 1, hipoclorito de sódio a 2,5%; Grupo 2, álcool a 70%; Grupo 3, clorexidina gel a 2%; e Grupo 4, clorexidina líquida a 0,12%, onde cada cone ficou submerso na substância por um minuto, foi seco por meio de esfregaço com gaze estéril e inserido em meio de cultura BHI, para se avaliar a presença ou não de contaminação. Os resultados encontrados mostraram que os cones de guta-percha não apresentavam contaminação, independentemente de serem submetidos ou não a um processo de descontaminação. Dessa forma, conclui-se que não há necessidade de descontaminação dos cones de guta-percha, contanto que seja respeitada a cadeia asséptica do tratamento endodôntico.

In vitro effectiveness evaluation of different substances in decontamination of intracanal metallic

Introduction: The intracanal metallic post, for many years, was the most used intracanal retainer and the best choice to restore endodontically treated teeth, showing until today high rates of success scientifically proven, good adaptation at the configuration of the root canal and resistance. Objective: The purpose of this study was to evaluate the effectiveness of some chemical substances in the decontamination of these intracanal metallic posts. Material and methods: Twenty intracanal metallic posts were divided into 6 experimental groups and 1 control group with 3 specimens each. The groups were divided into G1 (apple cider vinegar), G2 (0.12% chlorhexidine liquid), G3 (2% chlorhexidine gel), G4 (70° ethyl alcohol), G5 (2.5% sodium hypochlorite), and G6 (2% glutaraldehyde). For the control group was used saline solution. Each intracanal metallic post was submerged in your respective substance for 3 minutes and subjected to a smear dried sterile gauze. Immediately after this procedure the specimens were individually placed into tubes containing culture medium broth Brain Heart Infusion (BHI). The set of tubes containing the intracanal metallic post submerged in BHI were taken to the dry out machine and kept there at 37ºC for 48 hours. Results: The tubes that showed turbidity of BHI broth were considered positive, or contaminated. Conclusion: The methodology used in this study showed that all the disinfectants substances utilized were effective in decontaminating of the metallic post.

Accuracy evaluation of three electronic apex locators in teeth with immature apices

Introduction and Objective: The aim of this randomized controlled study was to evaluate the accuracy of Root ZX, iPex and YS-RZ-A apex locators in tooth with incomplete apices. Material and methods: Thirty human mandibular pre-molars without dental caries, fracture and with 1-3mm apical diameter and ¾ of root development stage were used. After coronal access, tooth length was determined with the visualization of a K-file, compatible with the root canal diameter, at the apex. To determine the root canal length using electronic methods, the teeth were included in alginate. The 30 teeth were measured with the three apex locators until achieving the apex foramen. During the measurement, the canals were inundated with 1% sodium hypochlorite. Statistical analysis was performed using Qui-square test (p < 0.05). Results: The Root ZX apex locator showed the higher accuracy (53.3%), with statistical difference in relation to iPex apex locator (33.3%) and YS-RZ-A apex locator (26.7%) (p < 0.05). Regarding the security limit of ±1 mm, the Root ZX apex locator did not show statistical difference in comparison with iPex apex locator (p > 0.05), but both were statistically different in relation to YS-RZ-A apex locator (p < 0.05). Conclusion: The results showed that all the studied apex locators were efficient in determining the root canal length in tooth with incomplete apex, considering the tolerance of ±1 mm. The Root ZX apex locator showed the highest accuracy with 100% of agreement.

Prevalência de lesão endodôntica em pacientes diabéticos / Prevalence of apical periodontitis in diabetic patients / Prevalencia de lesión endodóntica de pacientes diabéticos

Investigar a prevalência de lesões endodônticas em pacientes diabéticos e não diabéticos. Métodos: Em estudo transversal, exames radiográficos (panorâmica e seriografia) de 80 pacientes, sendo 40 diabéticos tipo II e 40 não diabéticos, receberam avaliação, por meio de um índice de escores periapicais, das regiões perioendodônticas de todos os elementos dentais presentes. Os dados foram analisados pelo programa BioEstat 5.3®. Resultados: Encontrou-se pelo menos 1 dente apresentando lesão apical em 90% (n=32) dos pacientes diabéticos e 52% (n=21) dos pacientes não diabéticos (p=0,0001). Quanto aos dentes tratados endodonticamente, nos pacientes diabéticos, foram encontrados 44% (n=51) com lesões endodônticas, e apenas 17% (n=17) (p=0,0004) no grupo controle. Os pacientes diabéticos apresentaram maior quantidade de lesões endodônticas em relação aos pacientes não diabéticos (p=0,0189). Conclusão: De acordo com esses resultados, podese concluir que a Diabetes Mellitus tipo II está associada ao aumento da prevalência de lesões endodônticas...

To investigate the prevalence of apical periodontitis (AP) in diabetic and nondiabetic patients. Methods: Cross-sectional study, in which the radiographic records (panoramic and full-mouth periapical radiographs) of 80 patients, being 40 type II diabetic patients and 40 nondiabetic subjects, had the periapical and endodontic regions of all teeth present evaluated by means of the periapical index score. Data was analyzed through BioEstat 5.3TM software. Results: At least one tooth was found with apical periodontitis in 90% (n=32) of the diabetic patients and in 52% (n=21) of nondiabetic subjects (p=0.0001). Regarding root-filled teeth, 44% (n=51) presented AP amongst the diabetic patients, whereas only 17% (n=17) (p=0.0004) were affected in the control group. Conclusion: According to these results, type 2 Diabetes Mellitus is associated with an increase in the prevalence of apical periodontitis...

Investigar la prevalencia de lesiones endodónticas de pacientes diabéticos e no diabéticos. Métodos: Estudio transversal con pruebas radiológicas (panorâmica y seriografía) de 80 pacientes, siendo 40 diabéticos tipo II y 40 no diabéticos que recibieron evaluación a través del índice de puntuaciones periapicales de las regiones perioendodónticas de todos los elementos dentales presentes. Los datos fueron analizados con el programa BioEstat 5.3. Resultados: Se encontró por lo menos un diente con lesión apical en el 90% (n=32) de los pacientes diabéticos y el 52% (n=21) de los no diabéticos (p=0,0001). Respecto a los dientes tratados endodónticamente, el 44% (n=51) de los pacientes diabéticos presentó lesiones endodónticas y solamente el 17% (n=17) (p=0,0004) en el grupo control. Los pacientes diabéticos presentaron más lesiones endodónticas que los no diabéticos (p=0,0189). Conclusión: A partir de los resultados se concluye que la Diabetes Mellitus tipo II está asociada con el aumento de la prevalencia de lesiones endodónticas...

Efficacy of gutta-percha solvents used in endodontic retreatments

Introduction and Objective: The aim of this study was to evaluate the effectiveness of four different solvents and classify them according to their potential of action. Material and methods: Four solvents were tested: xylene, eucalyptol, orange oil and chloroform. Twelve gutta-percha points (medium-large), sectioned at 10 mm were used and divided into four groups, resulting in three samples for each solvent. The gutta-percha points were weighed on an analytical balance before being subjected to the action of solvents and subsequently put onto watch glasses that were immersed into the solutions for the following times: 1, 2, 3, 4 and 5 minutes. The percentage of mass loss was registered through weighing after every minute of action of the solvent on the points. Results: All solvents showed the first minute of action as the period of greatest power of dissolution because they act only on the gutta-percha itself and not on the other components of the point, suggesting that at the remaining minutes there would be a lower percentage of dissolution because there was a smaller amount of gutta-percha within the points. Conclusion: Chloroform and xylene showed similar results regarding the rate of dissolution of gutta-percha, yet they were statistically significant higher than eucalyptol and orange oil from 1 to 5 minutes.

Endodontic treatment for necrotic immature permanent teeth using MTA and calcium hydroxide: A retrospective study

Introduction: Endodontic treatment of young permanent teeth with incomplete root formation and necrotic pulp has been a challenge for the dentist. It is necessary to induce the formation of apical barrier (apical plug), enabling the complete root canal filling. Objective: This retrospective clinical study compared the protocols for treatment of teeth with incomplete root formation, using calcium hydroxide (CH) or mineral trioxide aggregate (MTA). Material and methods: 28 patients with incomplete root formation have undergone root canal treatments in the period from 2000 to 2009 were selected. The procedures for cleaning, shaping and intracanal medication (CH paste) were performed in a standardized manner. In 13 patients, after using the CH paste (14 days), apical plugs with MTA were made. In the remaining 15 teeth monthly exchanges with CH paste were executed until it was observed radiographically the formation of the apical barrier. In all cases the canals were filled conventionally with gutta-percha and sealer. Initially, follow-ups were made on a quarterly and semiannually at the end of first year. Results: All apical lesions showed apical healing between 4 and 13 months after starting treatment. There was not noted the continuing process of root formation. Conclusion: It was concluded that the treatment of teeth with incomplete root formation and necrotic pulp with the use of MTA as apical plug has the same clinical results compared with the use of CH, with the advantage of less clinical time.

In vitro analysis of the pH alteration of the dentine after using different calcium hydroxide-based pastes

Introduction: To analyze the pH increase at the external root surface after the use of different calcium hydroxide pastes (Calen, calcium hydroxide associated with 2% chlorhexidine gel, calcium hydroxide associated with saline) with and without EDTA as chelating agent before the topical application of the intracanal medication. Material and methods: One-hundred single-rooted extracted teeth were cleaned and shaped. They were randomly divided into six experimental groups (n = 15) and one control group (n = 10), according to the medication to be used. The teeth were kept immersed in saline solution and the pH measurements were weekly verified with the aid of a pH meter. Results: It was verified the pH increasing at the first week in almost all groups. Only the groups in which Ca(OH)2 was associated with 2% chlorhexidine gel exhibited a significant evolution in the pH increasing over time (p = 0.0116). The use of EDTA did not result in higher pH values (p = 0.2278). Conclusion: i) the pH increased in all associations used; ii) 2% chlorhexidine gel allowed the gradual pH increasing over time; iii) the smear layer removal did not influence on the pH increasing.

Evaluation of apically extruded debris during endodontic retreatment

Introduction: A growing interest to preserve teeth into the mouth by patients resulted in the increasing number of endodontic retreatments, and when these happen, many different types of irritants are extruded through the foramen. Objective: This study analyzed in vitro the amount of debris extruded through the foramen using four instrumentation techniques during endodontic retreatment. Material and methods: Forty mesial-buccal roots of first molars were selected, instrumented with anatomical diameter up to size #30 ISO file and then obturated with gutta-percha and grossman sealer by lateral condensation. After, they were separated and randomly allocated into four groups with 10 teeth each for the endodontic retreatment procedure: G1 - conventional technique + solvent, G2 - conventional technique without solvent, G3 - ProTaper retreatment + solvent, G4 - ProTaper retreatment without solvent. In all groups, gutta-percha in the coronal portion was removed by using size 1-3 Gates Glidden drills. All teeth were irrigated with distilled water. The debris extruded through the foramen were collected and weighed by an analytical balance. Results: Group 4 had the lowest average for material extrusion through the foramen followed by groups 2, 3 and 1. When Tukey test for statistical analysis was applied, no significant difference among groups were found (p = 0.5664). Conclusion: We conclude that all instrumentation techniques used in this study produced debris which goes beyond the foramen.

Two root canals in maxillary central incisor

Introduction and objective: The success of endodontic treatment requires the knowledge of tooth morphology and its variations. Case report: This clinical article reports an unusual root canal configuration that was detected in a maxillary central incisor with two root canals, demonstrated by radiographic and computerized tomography exams. Conclusion: Knowledge of endodontic anatomy as well as the obtainment of both preoperative radiographs and tomography is important to detect abnormal tooth morphology.

Evaluation of the dentin remaining after flaring using Gates Glidden drills and Protaper rotary files

INTRODUCTION: The application of rotary instruments for root canal preparation requires a safe, not harming procedure to the root structure remaining. OBJECTIVES: The purpose of this study was to analyze the root thickness in 28 mesial canals of lower permanent first molars before and after flaring using two rotary instruments: Gates-Glidden drills and ProTaper rotary files. MATERIAL AND METHODS: Teeth were embedded into a muffle system. Samples were obtained by cutting 2mm below the furcation. The images were captured by a digital video system (8X and 12X magnification). For image analysis and processing, Pro-Image Plus 4.1 software was used. Each image captured by the computer was gauged, eliminating any possible distortion. Gates-Glidden drills were used in decreasing order of size (GG#4, GG#3, GG#2). ProTaper was used according to the manufacturer's recommendations, with hand-piece powered by an electric motor with low torque. 5.25 percent sodium hypochlorite was utilized as irrigant. RESULTS: The average thickness between the canal and furcation before and after use of rotary instruments were: 0.857 mm and 0.561 mm for Gates-Glidden drills, and 0.858 mm and 0.486 mm for ProTaper, respectively. No statistical differences were found in the root thickness of specimens shaped with ProTaper rotary files and Gates Glidden drills. CONCLUSION: The use of Gates-Glidden drills is as safe as ProTaper rotary files with respect to danger of perforation on the distal side of the mesial roots of lower molars.

Análise da espessura da linha de cimento após o uso de diferentes técnicas de obturação de canais radiculares / Evaluation of the film thickness of a root canal sealer following different filling techniques

Introdução: O objetivo deste estudo foi realizar uma análise quantitativa da espessura da linha de cimento endodôntico formada após o uso de três diferentes técnicas de obturação. Materiais e método: Foram utilizados sessenta pré-molares inferiores. Após os procedimentos de limpeza e modelagem, os dentes foram distribuídos aleatoriamente em três grupos, de acordo com a técnica de obturação a ser empregada: Grupo I - Compressão hidráulica; Grupo II - Condensação lateral; Grupo III - Híbrida de Tagger. Foi utilizado no experimento um cimento a base de óxido de zinco eugenol. Os espécimes foram analisados em quatro cortes: 12 mm, 9 mm, 6 mm e 3 mm aquém do ápice radicular. As imagens dos cortes transversais foram capturadas e a espessura de cimento foi mensurada utilizando-se o programa Image Tool 3.0. A análise estatística foi executada utilizando-se o teste de Wilcoxon (SPSS 12.0). Resultados: A técnica de Tagger foi superior às demais, seguida pela compressão hidráulica e condensação lateral, com os resultados mostrarando-se estatisticamente diferentes entre todos os grupos (p = 0,0109). Conclusões: Em geral, as menores espessuras de cimento foram obtidas para o Grupo III, sendo piores os resultados obtidos para o grupo da condensação lateral.

Avaliação in vivo da dor pós-operatória em dentes vitais após o alargamento do forame apical / In vivo evaluation of post operative pain in vital pulps after the foramen enlargement

Objetivo: O objetivo do presente trabalho foi avaliar a dor pós-operatória em dentes vitais uni ou birradicularessubmetidos ou não ao alargamento foraminal até a lima # 30. Métodos: Quarenta dentes foram selecionados e divididos randomicamente em dois grupos. No Grupo I (experimental) foi preconizada ampliação foraminal até a lima # 30 e comprimento de trabalho 1 a2 mm aquém do forame. No Grupo II (de controle) foi preconizado limite de trabalho de 1 a 2 mm aquém do ápice e manutenção do remanescente pulpar. Todos os procedimentos foram realizados pelo mesmo operador. A vitalidade foi analisada com base em aspectos clínicos e radiográficos. Todos os dentes foram tratados em sessão única e o localizador apical Root ZX® foi utilizado para a determinação do comprimento de trabalho, conjuntamente com a comprovação radiográfica. A dor foi avaliada por um período de 24 e 48h. Resultados e Conclusão: Com base nos resultados relatados pelos pacientes, não foi observada diferença estatística entreos dois grupos, ou seja, o alargamento do forame apical não aumentou a incidência de dor

Seal capability of interim post and core crown with temporary cements

The purpose of the present study was to evaluate the in vitro seal capability of interim post and core crown restorations. Eighty teeth were selected and divided into 8 groups. Four experimental groups received interim posts and core crowns. Half of each group was decoronated at the cementum-enamel junction, groups PCCH and PCZO. The other half was sectioned 2 mm coronal to the cementum-enamel junction, groups PCrZO and PCrCH. The interim post and core crowns were luted with Rely X Temp NE, groups PCrZO and PCZO; Hydro C was used for Groups PCrCH and PCCH. The control groups, PC and PCr, received uncoated post and core crowns; groups OTg and OT were left without interim post and core crowns and were totally open. Infiltration was accessed by dye exposure followed by demineralization of the teeth. The length of the infiltration was measured using digital images taken from the specimens. The images were inserted into the Image Tool 3.0 software. Kruskal-Wallis analysis of variance and Dunn's multiple comparison method were used to test for significant differences among test groups (P < .05). Groups PCrZO and PCrCH showed the least dye penetration, followed by groups PCZO and PCCH. Teeth restored with interim post and core crowns will be subject to leakage. Ethics Committee: 095/2008.

Ex vivo evaluation of coronal and apical microbial leakage of root canal - Filled with gutta-percha or Resilon/Epiphany root canal filling material.

Objective: This ex vivo study compared coronal and apical microleakage of root canals filled with Resilon/Epiphany (RE) or gutta-percha/Grossman sealer (GP), using either lateral condensation (LC) or System B (SB) technique. Materials and Methods: Specimens in eight experimental groups were obturated using the following materials and techniques: Groups 1 and 3 - GP and LC; groups 2 and 4 - GP and SB; groups 5 and 7 - RE and LC; groups 6 and 8 - RE and SB. Apical and coronal leakages were tested using bacterial methods. For coronal analysis, the number of days required for complete contamination of the root canals was recorded according to observation of the brain heart infusion broth turbidity for 15 weeks. For apical analysis, the teeth were cleaved and the leakage was measured at 30 days. Data were collected for each sample and analyzed statistically with the Chi-square and ANOVA tests. Results: Leakage was found in all groups. The difference between filling materials, obturation techniques, and median time of leakage was not statistically significant for coronal ( P=0.847) and apical ( P=0.5789) leakages. Conclusion: There were no differences between the different filling materials (gutta-percha/Grossman sealer and Resilon/Epiphany) and obturation techniques (lateral condensation and system B technique) in coronal or apical leakages.

Three root canals in the maxillary second premolar.

In this study, we report an endodontic treatment of the maxillary second premolar with three root canals and distinct foramens. The possibility of three root canals in this tooth is quite small; however, it must be taken into account in clinical and radiographic evaluation during endodontic treatment. Many times, their presence is noticed only after canal treatment due to continuing post-operative discomfort.

Regeneração tecidual guiada em defeito periapical. Relato de caso clínico / Guided tissue regeneration in periapical defect. Case report

O objetivo do tratamento endodôntico é remover a causa da doença pulpar, limitando o efeito nos tecidos perirradiculares. A terapia endodôntica cirúrgica é o tratamento de escolha quando os dentes não respondem adequadamente ao tratamento convencional ou não podem ser tratados apropriadamente pela abordagem não-cirúrgica. Os autores apresentam um caso clínico em que a técnica de regeneração tecidual guiada (RTG) foi utilizada no tratamento de um defeito periapical largo e profundo, demonstrando uma completa regeneração óssea após cinco anos e seis meses de acompanhamento.

The objective of root canal treatment is to remove the cause or potencial cause of the pulp space disease in order to limit the effect on periradicular tissues. Surgical endodontic therapy is the treatment of choice when teeth have responded poorly to conventional treatment or when they cannot be treated appropriately by nonsurgical means. The authors present a case report in which the guided tissue regeneration technique was used in the treatment of a deep/large periapical defect, showing a complete healing after five years and six months.

Cleaning ability of chlorhexidine gel and sodium hypochlorite associated or not with EDTA as root canal irrigants: a scanning electron microscopy study

The aim of this study was to evaluate the cleaning efficacy of 2 percent chlorhexidine gluconate gel (CHX) compared to 2.5 percent sodium hypochlorite solution (NaOCl) associated or not with 17 percent EDTA used as irrigants during the biomechanical preparation. Fifty freshly extracted single-rooted human teeth with complete apex formation were randomly divided into five groups: G1 - sterile saline, G2 - 2.5 percent NaOCl, G3 - 2 percent CHX, G4 - 2.5 percent NaOCl + EDTA and G5 - 2 percent CHX + EDTA. The specimens of G1 were subdivided into two control groups. The teeth were decoronated and the coronal and middle root thirds were prepared with Gates-Glidden burs, and the apical third was reserved to manual instrumentation. All procedures were performed by a single operator. In all groups, 2 mL of irrigant was delivered between each file change. The teeth were sectioned and prepared for analyses under scanning electron microscopy (SEM). SEM micrographs were graded according to a score scale by two examiners. Data were analyzed statistically by Kruskal-Wallis and Dunn tests at 1 percent significance level. The best results were obtained in the groups in which the irrigant was used followed by the chelating agent. No statistically significant difference was observed among G4, G5 and the positive control group (p<0.01). The groups G2 and G3 were significantly different from the others, presenting the worst cleaning capacity. In conclusion, the use of the chelating agent is necessary to obtain clean canal walls, with open tubules and no heavy debris. The use of 2 percent chlorhexidine gluconate gel alone is not able to remove the smear layer.

Brazilian gutta-percha points. Part II: thermal properties

This study was undertaken to explore the effect of heating on gutta-percha, analyzing the occurrence of endothermic peaks corresponding to the transformation that occurs in the crystalline structure of the polymer during thermal manipulation. This study also seeked to determine the temperature at which these peaks occur, causing a transformation from the beta- to the alpha-form, and from the alpha- to the amorphous phase. Eight nonstandardized gutta-percha points commercially available in Brazil (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP, Dentsply FM) and pure gutta-percha (control) were analysed using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The transition temperatures were determined and analysed. With the exception of Dentsply 0.04 and Dentsply 0.06, the majority of the products showed thermal behaviour typical of beta-gutta-percha, with two endothermic peaks, exhibiting two crystalline transformations upon heating from ambient temperature to 130°. Upon cooling and reheating, few samples presented two endothermic peaks. It was concluded that heating dental gutta-percha to 130°C causes changes to its chemical structure which permanently alter its physical properties.

Este estudo teve como objetivo analisar, através da Calorimetria Diferencial de Varredura (DSC) e Análise Termogravimétrica (TGA), os efeitos do aquecimento sobre o polímero guta-percha, bem como explorar a ocorrência de picos endotérmicos, os quais correspondem às transformações cristalinas do polímero guta-percha, o que é traduzido em transições de fases (fase beta para alfa e fase alfa para amorfa). Foram utilizadas 8 marcas comerciais de cones de guta-percha não-estandardizados disponíveis no mercado brasileiro (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP, Dentsply FM), além da guta-percha pura (controle). As temperaturas de transição foram determinadas e analisadas. Com exceção das amostras Dentsply 0.04 e Dentsply 0.06, todas as demais apresentaram duas transformações cristalinas de fase quando submetidas ao aquecimento da temperatura ambiente até 130°C, comportamento típico de guta-percha em fase beta. Ao serem resfriadas e reaquecidas, poucas amostras apresentaram dois picos endotérmicos. É possível concluir que o aquecimento a 130°C causa danos na estrutura química do polímero guta-percha, o qual altera de forma definitiva suas propriedades físicas.

Clinical relevance of trans 1.4-polyisoprene aging degradation on the longevity of root canal treatment

This in vivo study investigated the time of degradation of root filling material (trans 1,4-polyisoprene) retrieved from endodontically treated teeth and correlated the occurrence of degradation with the longevity of endodontics. Thirty-six root-filled teeth with different filling times (2 to 30 years) and with and without periapical lesions were selected. All teeth presented clinical indication for root canal retreatment. The association among filling time, presence of periapical lesion and root filling material degradation was investigated. Root filling samples were retrieved from the root canals using a Hedströ m file without solvent. The trans 1,4-polyisoprene was isolated by root filling solubilization in chloroform followed by filtration and centrifugation. GPC and FT-IR were the analytical techniques utilized. Degradation of trans 1,4-polyisoprene occurred with time, as a slow process. It is an oxidative process, and production of carboxyl and hydroxyl groups in the residual polymer were observed. Statistically significant decrease of molar mass was observed after 5 (p=0.0001) and 15 (p=0.01) years in teeth with and without periapical lesion, respectively. Bacteria participated in polymer degradation. Gutta-percha aging was proven an important factor for the long-term success of endodontic treatment. The findings of the present study showed that, after 15 years, polymer weight loss may decrease the capacity of the filling mass to seal the root canal space and prevent re-infection, thus compromising significantly the longevity of root canal therapy.

Este estudo in vivo avaliou a degradação do material obturador e a influência deste fator na longevidade do tratamento endodôntico. Foram selecionados 36 pacientes (3-30 anos) com canais tratados endodonticamente, com e sem lesões periapicais, e indicação de retratamento endodôntico. Foi investigada a associação entre o tempo de tratamento, presença de lesão periapical e a degradação do material obturador. O material obturador foi removido com uma lima Hedströ em sem uso de solvente. O polímero trans 1,4- poliisopreno foi isolado do material obturador através de solubilização em clorofórmio, seguido de filtragem e centrifugação. GPC e FT-IR foram os métodos analíticos utilizados. A degradação do trans 1,4- poliisopreno foi observada com o tempo, sendo um processo lento e oxidativo, com formação de grupos carboxílicos e hidroxilas no polímero residual. Após 5 (p=0,0001) e 15 (p=0,01) anos, em dentes com e sem lesões periapicais, respectivamente, houve decréscimos significantes na massa molar do material obturador. A infecção bacteriana participa no processo de degradação do polímero. O envelhecimento da guta-percha é um fator que influencia o sucesso a longo prazo do tratamento endodôntico. Após 15 anos, a longevidade do tratamento pode ser significantemente afetada pela redução da capacidade de selamento causada pela perda de massa molar do polímero, permitindo a reinfecção do sistema de canais radiculares.