Influence of the gutta-percha taper and finger spreader on lateral consensation effectiveness

Introduction: Lateral condensation effectiveness may be influenced by the gutta-percha and finger spreader taper used during root canal obturation. Objective: To evaluate the penetration ability of finger spreader into simulated root canals prepared using MTwo rotary system and filled with different gutta-percha and finger spreader tapers. Material and methods: Resin blocks with curved root canals had the apical diameter enlarged up to #25.06 and distributed into groups (n = 6) according to the gutta-percha taper (#25.02, #25.04, and #25.06) and the finger spreader (#30 and #35 NiTi, and stainless steel B) used to perform cold lateral condensation. After applying a load of 1.5 Kg over the finger spreaders’ head, the distance between the finger spread tip and the apical limit of the root canal preparation were obtained. The data were submitted to Anova and Tukey-Krammer’s test, with 5% of significance. Results: The gutta-percha cones with 0.02 taper enabled higher finger spreader penetration when compared to 0.04 and 0.06 tapers (p < 0.05), which were similar between each other (p > 0.05), regardless of the type and diameter of the finger spreader used. When different finger spreaders were compared among themselves, stainless steel B showed higher penetration ability (p < 0.05). Conclusion: It was concluded that the stainless-steel finger spreaders showed superior penetration ability and gutta-percha with lower tapers enabled a more effective lateral condensation at the apical third.

Fracture resistance of simulated immature teeth after different intra-radicular treatments

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

Effect of pre-flaring and file size on the accuracy of two electronic apex locators

Objective: This ex vivo study evaluated the effect of pre-flaring and file size on the accuracy of the Root ZX and Novapex electronic apex locators (EALs). Material and methods: The actual working length (WL) was set 1 mm short of the apical foramen in the palatal root canals of 24 extracted maxillary molars. The teeth were embedded in an alginate mold, and two examiners performed the electronic measurements using #10, #15, and #20 K-files. The files were inserted into the root canals until the "0.0" or "APEX" signals were observed on the LED or display screens for the Novapex and Root ZX, respectively, retracting to the 1.0 mark. The measurements were repeated after the pre-flaring using the S1 and SX Pro-Taper instruments. Two measurements were performed for each condition and the means were used. Intra-class correlation coefficients (ICCs) were calculated to verify the intra-and inter-examiner agreement. The mean differences between the WL and electronic length values were analyzed by the three-way ANOVA test (p<0.05). Results: ICCs were high (>0.8) and the results demonstrated a similar accuracy for both EALs (p>0.05). Statistically significant accurate measurements were verified in the pre-flared canals, except for the Novapex using a #20 K-file. Conclusions: The tested EALs showed acceptable accuracy, whereas the pre-flaring procedure revealed a more significant effect than the used file size.

Topography of four different endodontic rotary systems, before and after being used for the 12th time

Root canal preparation may damage NiTi instruments resulting in wear and deformation. The aim of this study was to make a comparative evaluation of the surface topography of the cervical third of four different rotary systems, before and after being used twelve times, in 1.440 resin blocks with simulated root canals with standardized 45 degrees curvatures, and analyzed by atomic force microscopy AFM. The blocks were divided into four groups and prepared according to the manufacturers recommendations: Group 1 - K3 (R); Group 2 - Protaper Universal (R); Group 3 - Twisted Files (R) and Group 4 - Biorace (R). After each preparation, the instruments were washed and autoclaved. A total of 240 instruments were selected, being 30 new instruments and 30 after having been used for the 12th time, from each group. These instruments were analyzed by AFM and for quantitative evaluation, the mean RMS (Root mean square) values of the cervical third of the specimens from the four groups were used. The result showed that all the rotary files used for the 12th time suffered wear with change in the topography of the cervical region of the active portion of the file (ANOVA p < 0.01). Classifying the specimens in increasing order, from the least to the greatest wear suffered, Group 3 (2.8993 nm) presented the least wear, followed by Group 4 (12.2520 nm), Group 1 (36.0043 nm) and lastly, Group 2 (59.8750 nm) with the largest amount of cervical surface wear. Microsc. Res. Tech. 75:97-102, 2012. (c) 2011 Wiley Periodicals, Inc.

Assessing apical transportation in curved canals: comparison between cross-sections and micro-computed tomography

The aim of this study was to compare two methods of assessing apical transportation in curved canals after rotary instrumentation, namely, cross-sections and micro-computed tomography (mu CT). Thirty mandibular molars were divided into two groups and prepared according to the requirements of each method. In G1 (cross-sections), teeth were embedded in resin blocks and sectioned at 2.0, 3.5, and 5.0 mm from the anatomic apex. Pre- and postoperative sections were photographed and analyzed. In G2 (mu CT), teeth were embedded in a rubber-base impression material and scanned before and after instrumentation. Mesiobuccal canals were instrumented with the Twisted File (TF) system (SybronEndo, Orange, USA), and mesiolingual canals, with the Endo Sequence (ES) system (Brasseler, Savannah, USA). Images were reconstructed, and sections corresponding to distances 2.0, 3.5, and 5.0 mm from the anatomic apex were selected for comparison. Data were analyzed using Mann-Whitney's test at a 5% significance level. The TF and ES instruments produced little deviation from the root canal center, with no statistical difference between them (P > 0.05). The canal transportation results were significantly lower (0.056 mm) in G2 than in G1 (0.089 mm) (p = 0.0012). The mu CT method was superior to the cross-section method, especially in view of its ability to preserve specimens and provide results that are more closely related to clinical situations.

Análise biomecânica de resistência à fratura em dentes caninos artificiais de cães, com restauração metálica fundida e retentores intrarradiculares retos e curvos com núcleo - Estudo comparativo com análise por elementos finitos

Os cães, por fatores diversos, acabam por apresentar dentes fraturados com ou sem exposição de polpa. Estas fraturas basicamente são identificadas como fraturas recuperáveis não complicadas, recuperáveis complicadas ou irrecuperáveis. As fraturas recuperáveis (localizadas apenas no esmalte e dentina) são tratadas com dentística restauradora. As recuperáveis complicadas (com lesões em esmalte, dentina e exposição do canal radicular) passam por tratamento endodôntico, podendo ser seguidas de restaurações metálicas. Os dentes mais comumente acometidos são os dentes caninos, superiores ou inferiores. Este trabalho em dentes artificiais simulando considerável destruição de sua porção coronal objetivou testar, após a adaptação da restauração metálica fundida, a resistência às fraturas no dente canino. Os dentes artificiais foram padronizados com uma técnica de replicação de raízes artificiais em molde de resina acrílica quimicamente ativada. Oitenta réplicas iguais de resina composta fotopolimerizável, padronizadas em tamanho e forma, foram construídas a partir desta técnica. Antes da reconstrução protética, aplicou-se o tratamento endodôntico, desobturação, preparo do canal radicular e moldagem. Proteticamente, um pino intrarradicular reto e outro curvo, ambos com núcleo para sustentar a coroa metálica fundida foram cimentados na porção coronal de cada raiz-réplica. Os núcleos e coroa metálica foram ambos ferulados ou estojados. Avaliou-se os dois tipos de restauração com pino intrarradicular curvos ou retos cimentados com cimento de fosfato de zinco ou resinoso para identificar o melhor conjunto restaurador. Os testes de resistência biomecânica de 80 raízes-réplicas foram divididos em 4 grupos com 20 corpos de prova para cada um dos grupos. Grupo 1: das raízes-réplicas com pino intrarradicular curvo cimentados com cimento resinoso. Grupo 2: das raízes-réplicas com pino intrarradicular curvo cimentados com cimento de fosfato de zinco. Grupo 3: das raízes-réplicas com pino intrarradicular reto cimentados com cimento resinoso. Grupo 4: das raízes-réplicas com pino intrarradicular reto cimentados com cimento de fosfato de zinco. Estes grupos foram submetidos a teste de força com pré-carga de 1,5 N, com velocidade de avanço constante de 0,05 mm por minuto em ponto pré- determinado (mésio-lateral vestibularizada) até ocorrência de fratura do conjunto ou parte dele em uma Máquina Universal Kratos. Com a avaliação biomecânica e estudo estatístico de Kruskall-Wallis, identificou-se que os dados obtidos não seguiram distribuição normal. Esta diferença mostrou-se com o p<0,05 na interpretação do teste. No caso de dados não paramétricos o post-hoc do Kruskal-Wallis foi o teste de U de Mann-Withney. Paralelamente, um estudo com análise de elementos finitos comparou os resultados obtidos. Não houve diferença significativa sobre o tipo de cimento utilizado ou que favorecesse o uso do pino reto ou do pino curvo, recaindo a escolha para o operador decidir de acordo com a melhor indicação para cada caso clínico

In vivo microbiological evaluation of the effect of biomechanical preparation of root canals using different irrigating solutions

The aim of this study was to evaluate the antimicrobial effect of biomechanical preparation using different irrigating solutions. Seventy-eight root canals from premolars of four dogs were used. After experimental induction of periapical lesions, the root canals were prepared using the following solutions for irrigation: Group 1) 2.5% sodium hypochlorite (NaOCl); Group 2) 2% chlorhexidine (CHX); Group 3) saline solution and Group 4) control group with no biomechanical preparation. The microbiological evaluation of the root canals was performed by counting the colony forming units (CFUs) using different culture mediums. Two absorbent paper cones were used in each root canal in order to collect the microbiological samples before, and thirty days after the biomechanical preparation. The culture plates were incubated in aerobic, anaerobic and microaerophilic environment. Statistical evaluation was carried out using analysis of variance, Tukey and Student tests. The results demonstrated that there was reduction in the number of microorganisms in the NaOCl and CHX groups (p<0.05). There was greater effectiveness in the chlorhexidine group. The group that used saline solution and the control group presented an increased number of microorganisms. It can be concluded that the use of antimicrobial irrigating solutions during biomechanical preparation promotes the reduction of endodontic microbiota. However, a considerable number of microorganisms were still observed.

Efeitos provocados pelos irrigantes endodônticos na estrutura do canal radicular

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

Effect of calcium hydroxide-based materials on periapical tissue healing and orthodontic root resorption of endodontically treated teeth in dogs

This study evaluated periapical tissue healing and orthodontic root resorption of endodontically treated teeth sealed with calcium hydroxide in dogs. The sample consisted of three contralateral pairs of maxillary incisors and two contralateral pairs of mandibular incisors in each of two dogs using a split mouth design. After biomechanical preparation of the teeth in the first group (n = 10), a Ca(OH)(2) dressing was placed for 14 days before root canal filling with Ca(OH)(2)-based sealer (Sealapex) and gutta-percha points. In the second group (n = 10), root canals were obturated immediately after the mechanical preparation with gutta-percha points and zinc oxide and eugenol (ZOE)-based sealer (Endofill). After completion of endodontic treatment, the teeth were moved with an orthodontic appliance with a calibrated force of 200 g, reactivated every 21 days. After 105 days, the animals were killed and the teeth were removed upon completion of active treatment, without a period of recovery, and prepared for histomorphological analysis. All sections of each tooth were graded subjectively on a scale from one to four to obtain the average of the 16 histomorphological parameters analysed. Evaluation of the differences between the two treatment protocols was made with Mann-Whitney U-test. It was observed that the teeth treated with Ca(OH)(2)-based materials provided better outcomes (P = 5%), with complete repair of all root resorption areas, high rate of biological closure of the main canal and apical accessory canals by newly formed cementum, less intense and extensive chronic inflammatory infiltrate, and better organization of the periodontal ligament. Under the tested conditions, Ca(OH)(2)-based materials had a favourable action on periapical tissue healing and repair of orthodontic root resorption in endodontically treated dogs' teeth.

Healing process of dog teeth after post space preparation and exposition of the filling material to the oral environment

Foi propósito deste estudo analisar a influência da infiltração marginal coronária no comportamento dos tecidos periapicais de dentes de cães após obturação de canal e preparo para pino. Quarenta canais de dentes de cães foram instrumentados e obturados pela técnica da condensação lateral com cones de guta percha e os cimentos Roth e Sealer 26. Após preparo para pino, o remanescente da obturação foi protegido ou não com um plug do cimento temporário Lumicon. Após exposição ao meio oral por 90 dias, os animais foram sacrificados e as peças preparadas para análise histomorfológica. A técnica de Brown e Brenn mostrou 70% de casos com infiltração de microrganismos para o cimento Roth e 20% com o Sealer 26. Quando um plug de Lumicon foi empregado ocorreu 30% de casos de infiltração de microrganismos com o cimento Roth e 0,0% com o cimento Sealer 26. Reação inflamatória crônica foi mais freqüentemente observada com o cimento Roth do que com o Sealer 26. Foi concluído que o plug de Lumicon é eficiente no controle da infiltração coronária (p=0.05) e que o Sealer 26 foi mais biocompatível e selou melhor os canais radiculares do que o cimento Roth (p=0.01).

Er : YAG laser: Antimicrobial effects in the root canals of dogs' teeth with pulp necrosis and chronic periapical lesions

Objective: Our goal in this study was to evaluate the antimicrobial effect of Er:YAG laser applied after biomechanical preparation of the root canals of dog's teeth with apical periodontitis. Background Data: Various in vitro studies have reported effective bacterial reduction in infected root canals using Er:YAG laser. However, there is no in vivo research to support these results. Methods: Forty root canals of dogs' premolar teeth with pulp necrosis and chronic periapical lesions were used. An initial microbiological sample was taken, and after biomechanical preparation was carried out, a second microbiological sample was taken. The teeth were divided into two groups: Group I-biomechanical preparation was taken of root canals without Er:YAG laser application; Group II-biomechanical preparation was taken of root canals with Er:YAG laser application using 140-mj input, 63-mJ output/15 Hz. After coronal sealing, the root canals were left empty for 7 days at which time a third microbiological sample was taken. The collected material was removed from the root canal with a #40 K file and placed in transport media. It was serially diluted and seeded on culture dishes selective for anaerobes, aerobes, and total streptococci. Colony-forming units per milliliter (CFU/mL) were counted. Results: Groups I and II showed an increase of CFU/mL for all microorganisms 7 days after treatment, being statistically significant for anaerobes in Group I and for anaerobes and total streptococci in Group II. When comparing CFU/mL of Groups I and II, there was a statistically significant increase after 7 d for total streptococci in Group II. Conclusion: Er:YAG laser applied after biomechanical preparation did not reduce microorganisms in the root canal system.

Morphometrical analysis of cleaning capacity of a hybrid instrumentation in mesial flattened root canals

The cleaning capacity of hybrid and rotary instrumentation techniques in mesial flattened canals of mandibular first molars was evaluated by morphometrical analysis in this study. Twenty human mandibular first molars were randomly assigned into two groups, according to instrumentation technique, as follows: group 1, instrumentation with ProTaper Starter Kit (Dentsply/Maillefer) rotary system; group 2, manual instrumentation using K files (Dentsply/Maillefer) by crown-down technique in middle and apical thirds, cervical preparation with Gates-Glidden #1 and #2 (Dentsply/Maillefer) burs, and to finalise the preparation, ProTaper F2 and F3 rotary files. Serial transverse cross-sections (5 mu m) of the apical third, stained with hematoxylin and eosin, were analysed at 100 x original magnification. The images were submitted to morphometrical analysis with an integration grid to determine the percentage of root canal area with debris. Statiscal analysis (t-Student, P < 0.05) showed significant difference between the techniques (P < 0.05), although neither completely cleaned the root canal.

In vitro evaluation of the action of irrigating solutions associated with intracanal medications on Escherichia coli and its endotoxin in root canals

Objective: The purpose of this study was to evaluate the efficacy of auxiliary chemical substances and intracanal medications on Escherichia coli and its endotoxin in root canals. Material and Methods: Teeth were contaminated with a suspension of E. coli for 14 days and divided into 3 groups according to the auxiliary chemical substance used: G1) 2.5% sodium hypochlorite (NaOCl); G2) 2% chlorhexidine gel (CLX); G3) pyrogen-free solution. After, these groups were subdivided according to the intracanal medication (ICM): A) Calcium hydroxide paste (Calen (R)), B) polymyxin B, and C) Calcium hydroxide paste+2% CLX gel. For the control group (G4), pyrogen-free saline solution was used without application of intracanal medication. Samples of the root canal content were collected immediately after biomechanical preparation (BMP), at 7 days after BMP, after 14 days of intracanal medication activity, and 7 days after removal of intracanal medication. The following aspects were evaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the limulus Amebocyte lysate test (LAL). Results were analyzed by the kruskal-wallis and Dunn's tests at 5% significance level. Results: The 2.5% NaOCl and CLX were able to eliminate E. coli from root canal lumen and reduced the amount of endotoxin compared to saline. Conclusions: It was concluded that 2.5% NaOCl and CLX were effective in eliminating E. coli. Only the studied intracanal medications were to reduce the amount of endotoxin present in the root canals, regardless of the irrigant used.

In vitro evaluation of the effectiveness of irrigants and intracanal medicaments on microorganisms within root canals

Aim To evaluate in vitro the effectiveness of sodium hypochlorite (NaOCl). chlorhexidine (CHX) and live intracanal medicaments on microorganisms within root canals.Methodology Ninety-six human single-rooted extracted teeth were used. After removing the crowns, canal preparation was completed and the external root Surfaces were coated with epoxy resin. Following sterilization. The teeth were contaminated with Candida albicans and enterococcus faecalis. and were incubated at 37 +/- 1 degreesC for 7 days. The teeth were divided according to the irrigant solution or intracanal medicament: group 1. sterile physiologic solution (SPS) and calcium hydroxide (Ca(OH)(2)) paste: group 2. SPS and camphorated paramonochlorophenol (CPMC): group 3.SPS and tricresol formalin: group 4, SPS and CaOH2 + CPMC paste: group 5, SPS and PMC furacin; group 6.2.5%, NaOCl without intracanal medication: group 7, 2.0% CHX without intracanal medication and group 8, SPS Without intracanal medication (control group). Microbiological samples were collected with sterile paper points, and bacterial growth was determined. The data were submitted to the analysis of variance (ANOVA. P = 0.05).Results For C. albicans, groups 3 and S were statistically less effective than groups 1, 2. 4 and 5 (Kruskal-Wallis (K-W) = 65.241; gl = 7; P = 0.001). For E. faecalis, groups 6 and 8 were statistically less effective than groups 1-4 and 7 (K-W = 61.048; gl = 7; P = 0.001).Conclusions Ca(OH)(2) + CPMC paste was the most effective intracanal medicament for the elimination of the two microorganisms; 2.0% CHX solution was more effective than 2.5% NaOCl against E. faecalis.