Effect of glide path instruments in cyclic fatigue resistance of reciprocating instruments after three uses

The present study aims to evaluate the effect of different glide path instruments on the cyclic fatigue resistance of reciprocating endodontic instruments after three uses in mandibular molars. Eighteen Wave One Gold Primary reciprocating instruments were selected and randomly divided into three groups according to the glide path instrument: G1 - manual file K #15, G2 - Wave One Glider reciprocating instrument, and G3 (control group) - glide path was not performed. The reciprocating instruments were tested on mandibular molars and subdivided into three other groups: a new instrument, an instrument with a previous single-use, and an instrument with two previous uses. After the endodontic instrumentation, the instruments were subjected to the cyclic fatigue resistance test using an appropriate tool. The data were submitted to the Shapiro-Wilk test, and subsequently the Kruskal-Wallis test with a significance level of 5%. The results showed no statistical difference between the groups. Thus, it was concluded that the creation of a glide path did not affect the cyclic fatigue resistance of the reciprocating instrument. In addition, the reuse of final preparation instruments up to two times proved to be safe since no fractures were observed in the tested instruments.

Apical root canal cleaning after preparation with endodontic instruments: a randomized trial in vivo analysis

Objectives

This study aimed to evaluate vital pulp tissue removal from different endodontic instrumentation systems from root canal apical third in vivo.

Materials and Methods

Thirty mandibular molars were selected and randomly divided into 2 test groups and one control group. Inclusion criteria were a positive response to cold sensibility test, curvature angle between 10 and 20 degrees, and curvature radius lower than 10 mm. Root canals prepared with Hero 642 system (size 45/0.02) (n = 10) and Reciproc R40 (size 40/0.06) (n = 10) and control (n = 10) without instrumentation. Canals were irrigated only with saline solution during root canal preparation. The apical third was evaluated considering the touched/untouched perimeter and area to evaluate the efficacy of root canal wall debridement. Statistical analysis used t-test for comparisons.

Results

Untouched root canal at cross-section perimeter, the Hero 642 system showed 41.44% ± 5.62% and Reciproc R40 58.67% ± 12.39% without contact with instruments. Regarding the untouched area, Hero 642 system showed 22.78% ± 6.42% and Reciproc R40 34.35% ± 8.52%. Neither instrument achieved complete cross-sectional root canal debridement. Hero 642 system rotary taper 0.02 instruments achieved significant greater wall contact perimeter and area compared to reciprocate the Reciproc R40 taper 0.06 instrument.

Conclusions

Hero 642 achieved higher wall contact perimeter and area but, regardless of instrument size and taper, vital pulp during in vivo instrumentation is not entirely removed.

Effect of At-Home Bleaching on Oxygen Saturation Levels in the Dental Pulp of Maxillary Central Incisors

The present study assessed oxygen saturation (SaO2) levels before, during, and after at-home bleaching treatment in the pulps of healthy maxillary central incisors. SaO2 levels were measured in 136 healthy maxillary central incisors using a pulse oximeter. The bleaching protocol consisted of 10% carbamide peroxide gel placed in individual trays and used for four hours daily for 14 days. SaO2 levels were assessed before bleaching (T0), immediately after the first session (T1), on the 7th day of treatment (T2), on the 15th day (the day following the last session) (T3), and 30 days after completion of the bleaching protocol (T4). Data were statistically analyzed using generalized estimating equations (GEE), Student's t test (p<0.05) and Pearson's correlation. Mean pulp SaO2 levels were 85.1% at T0, 84.9% at T1, 84.7% at T2, 84.3% at T3, and 85.0% at T4. Gradual reductions in SaO2 levels were observed, with significant differences (p<0.001) during the course of home bleaching treatment. However, 30 days after the end of the bleaching protocol, SaO2 levels returned to baseline levels. Home bleaching caused a reversible transient decrease in SaO2 levels in the pulps.

Pulpotomia na rede pública em municípios da região norte do Rio Grande do Sul

Objetivo: Avaliar a decisão dos cirurgiões-dentistas frente à utilização da pulpotomia na rede pública em 16 municípios do Rio Grande do Sul, RS. Métodos: O estudo possui desenho transversal, quantitativo, com delineamento descritivo. A amostra não-probabilística, de conveniência, foi formada por 40 cirurgiões-dentistas. A coleta de dados se fez pelo envio de questionários aos profissionais da rede pública, com questões relacionadas à técnica de pulpotomia, e perguntas de relação social. Resultados: os resultados demonstraram que 92,5% (n=37) dos profissionais relataram não realizar tratamento endodôntico no serviço de atendimento público. Em relação à pulpotomia, 52,5% (n=21) realizam a técnica e quanto à técnica ser empregada no serviço público, 77,5% (n=31) relatam que deveria ser empregada. Mais da metade dos profissionais, 67,5% (n=27), responderam que consideram provisória a técnica de pulpotomia. No serviço público em que atuam 57,5% (n=23) não utilizam raio-x. Conclusões: Concluiu-se que um pouco mais da metade dos cirurgiões-dentistas pesquisados realizam a técnica de pulpotomia na rede pública, mesmo sem às vezes possuir as condições ideais para tal, como a ausência de raio-x. Utilizam como substância irrigadora o soro fisiológico e capeamento pulpar o hidróxido de cálcio e acreditando ser viável, porém com caráter provisório.

Prevalência de fraturas de instrumentos endodônticos de NiTi durante o tratamento endodôntico

A limpeza do sistema de canais radiculares é realizada com instrumentos de aço inoxidável e mais recentemente com instrumentos de níquel-titânio (NiTi), estes possuem maior flexibilidade e resistência. Porém, durante este processo pode ocorrer a separação dos instrumentos no interior dos canais radiculares. O presente trabalho objetivou avaliar por meio das anotações e radiografias periapicais dos prontuários quais elementos dentários, raízes e terços radiculares são mais susceptíveis para ocorrência de fratura de instrumentos rotatórios ou reciprocantes de NiTi. Para tanto, procedeu-se análise de dados recolhidos junto a 500 prontuários em atendimento odontológico no curso de especialização em Endodontia da IMED cujas radiografias foram avaliadas e quando visualizado um fragmento de instrumento este era identificado e registrado em planilha específica. Sobre o total de 500 prontuários atendidos 5,2% dos molares tratados apresentaram fratura de instrumento de NiTi, destes, 1,2% pertence a molares superiores e 4,0% a molares inferiores. Em relação ao canal radicular mais envolvido com a fratura do instrumento, nos molares superiores foi o mésio-vestibular (MV) com 83,33% e nos molares inferiores o mésio-lingual (ML) em 70% dos casos, em ambos os casos o terço apical foi o mais envolvido: 66,67% nos superiores e 80% nos inferiores. Desta forma os molares inferiores representaram o grupo dentário mais envolvido com fratura de instrumentos onde no seu canal mésio-lingual foi registrado a maior incidência de fraturas e o terço apical representou a totalidade da posição da fratura dentro do canal radicular.

Regaining Apical Patency with Manual and Reciprocating Instrumentation during Retreatment

Introduction:

Different techniques have been proposed to help achieving apical patency during endodontic treatment and retreatment. The objective of this in vitro study was to compare reestablishment of apical patency in teeth previously subjected to root canal treatment using manual and reciprocating instruments.

Methods and Materials:

A total of 40 single-rooted extracted human mandibular incisors were selected and prepared using the Hero 642 sequence to 45/0.02 and obturated using Tagger’s hybrid technique to 1 mm short of the apex. Teeth were divided into two groups according to the type of instrument used to regain patency: group 1, hand K-files and group 2, reciprocating WaveOne Primary files (25/0.08). Fisher’s exact test was used in the statistical analysis. Result: In group1, apical patency was regained in 9 of the 20 teeth tested (46%), compared to 20 teeth (100%) in group 2. The difference between the groups was significant (P<0.0001).

Conclusion:

Our study shows that reciprocating instrumentation is more successful in regaining apical patency in single-rooted, previously treated teeth.

Prevalência de Lesões Periapicais Observadas em Radiografias Panorâmicas

O presente trabalho teve como objetivo fazer um levantamento epidemiológico da prevalência de lesões periapicais radiolúcidas numa amostra de 107 radiografias panorâmicas, de pacientes atendidos no Curso de Graduação em Odontologia da Faculdade Meridional/IMED. Foram incluídos pacientes que possuíam radiografias panorâmicas realizadas no ano de 2015 e com o termo de Consentimento Livre e Esclarecido devidamente assinado. A coleta de dados foi feita através dos prontuários bem como, laudos e radiografias panorâmicas. Os critérios avaliados foram: presença de lesão periapical visível radiograficamente, gênero do paciente, idade, número total de dentes, elemento dentário, arcada e número de tratamentos endodônticos. Os dados foram organizados e comparados. Os resultados demonstraram que 53,3% dos laudos radiográficos apresentaram lesão periapical. A maioria das lesões encontrava-se em maxila, com 58,5% das ocorrências e os elementos dentários mais acometidos foram o 22 e 26. Concluiu-se que as lesões periapicais foram mais frequentes em mulheres na arcada superior e nos dentes incisivos laterais e primeiros molares superiores. 

Patência apical nos canais radiculares dos primeiros molares superiores

Objetivos: O objetivo deste estudo foi avaliar, ex vivo, a porcentagem da obtençãode patência apical nos canais radiculares dos primeiros molares superiores permanentese a influência da ampliação cervical nesta verificação.Método: Foram analisados 73 primeiros molares superiores permanentes, selecionadosatravés de exame visual e radiográfico. Para a execução do estudo, os dentesforam previamente abordados e os canais radiculares localizados. A patênciaapical foi verificada utilizando-se instrumentos de aço inoxidável #08 ou #10, deacordo com o diâmetro de cada canal radicular. Quando não se conseguia a patênciaapical, o terço cervical foi ampliado, com brocas de Gates-Glidden #1 e #2,seguidas de brocas LA Axxess #20 e a tentativa de obtenção de patência, executadanovamente.Resultados: Os resultados obtidos, com relação à presença de patência apical, foramde 79,45% para os canais radiculares mesiovestibulares, 29,62% para os canaisradiculares mesiopalatinos, 72,60% para os canais radiculares distovestibulares e84,93% para os canais radiculares palatinos.Conclusão: Pode-se concluir que a ampliação do terço cervical aumentou em 8,42%a obtenção de patência apical em todos os canais radiculares.

Avaliação da infiltração marginal dos materiais MTA, Cimento de Portland e Ionômero de Vidro empregados em obturações retrógadas

Objetivos. Avaliar o selamento apical promovido pelo MTA, cimento de Portland e ionômero de vidro em retrocavidades de dentes incisivos centrais superiores humanos.Método. Trinta incisivos centrais superiores foram tratados endodonticamente e tiveram sua porção apical seccionada, cavidades retrógadas foram preparadas e em seguida divididas em três grupos de dez dentes cada, da seguinte forma: Grupo1 – MTA; Grupo 2 – cimento de Portland; e Grupo 3 – ionômero de vidro. Dois dentes ainda foram utilizados, um como controle positivo e outro como controle negativo. Após a imersão no corante rodamina B a 0,2% por 48h a 37ºC as raízes foram clivadas e o padrão de infiltração foi mensurado. Os dados foram analisados utilizando-se ANOVA seguido pelo Teste Post Hoc de Bonferroni (p<0,05).Resultados. Os resultados mostraram que o grupo retrobturado com o ionômero de vidro obteve os melhores resultados (p< 0,05) quando comparados com os outros dois grupos experimentais. Os grupos dos cimentos MTA e Portland não tiveram diferenças estatisticamente significativas entre si (p> 0,05).Conclusão. Segundo a metodologia empregada, concluiu-se que o material que proporcionou o melhor selamento apical em retrobturações endodônticas foi o ionômero de vidro.

Flexibility of K3 and ProTaper universal instruments

This study used a mechanical test to evaluate the flexibility of instruments from the K3 (conicity 0.04) and the ProTaper Universal systems when they were new and after 5 uses in simulated canals. Five sets of instruments of each system were tested: K3 (15, 20, 25, 30, 35, 40 and 45) and ProTaper Universal (S1, S2, F1, F2, F3, F4 and F5). Each set of instruments was used to prepare a simulated canal and the same set of instruments was used 5 times (50 canals). The number of each subgroup represented the number of uses: 0 (control), 1, 3 and 5 uses. Before and after each use, the instruments were submitted to a mechanical flexibility test performed in a Versat 502 universal testing machine. Interactions between the instrument and the number of uses were analyzed by ANOVA and Tukey's test at a 5% level of significance. Instruments from both systems presented lower flexibility after the third use compared to the flexibility obtained after uses 0 and 1 (p<0.05), and maintained the same flexibility after the fifth use. The flexibility of instruments from the K3 system decreased with the increase of diameter, irrespective of the number of uses. Among the instruments from the ProTaper Universal system, the shaping files presented greater flexibility than the finishing files. F2 and F3 were the least flexible instruments, and F4 and F5 presented flexibility values similar to those of F1.

CT evaluation of apical canal transportation associated with stainless steel hand files, oscillatory technique and pro taper rotary system

This study used computed tomography (CT) to compare apical canal transportation in mesiobuccal canals of maxillary molars prepared with different techniques. Sixty teeth were assigned to 3 groups (n=20), according to the technique used for root canal instrumentation: hand instrumentation with K-Flexofiles, K-Flexofiles activated by an oscillatory system and ProTaper NiTi rotary system. Pre and post-instrumentation CT images were obtained 3 mm short of the apical foramen and were superimposed to compare canal transportation. Data were analyzed statistically by ANOVA and Tukey's test using the SPSS software (α=0.05). In the buccal direction, the manual technique produced significantly less canal transportation than the oscillatory technique (p<0.05) and both were similar to the rotary technique (p>0.05). In the distal and distopalatal directions, the oscillatory technique produced more canal transportation (p<0.05). In the mesiopalatal direction, the oscillatory technique produced more canal transportation than the manual technique (p<0.05), and both were similar to the rotary technique (p>0.05). In conclusion, all techniques produced canal transportation, and the oscillatory technique produced the greatest removal of root dentin toward the innerside of the root curvature.

Radiographic evaluation of furcal perforations sealed with different materials in dogs' teeth

OBJECTIVE

The objective of this work was to evaluate, using radiographic images, the behavior of four materials used to repair root perforations in dogs' teeth.

MATERIAL AND METHODS

Second and third premolars of 6 dogs were used. The 48 teeth were randomly divided into 4 groups (n=12) and the perforations were sealed with one of the following materials: MTA, AH Plus, Vitremer and gutta-percha. Dogs were submitted to general anesthesia, teeth were radiographed and pulp was accessed. Perforations were done, at the maximum curve of the pulp floor, sealed and the accessed coronal cavity was filled with glass ionomer cement (Vidrion R). After 90 days, the dogs were sacrificed and the last x-ray image was taken. Images were analyzed for the presence/absence of periodontal lesions at the perforation region. Data were analyzed statistically by chi-square test at 5% significance level.

RESULTS

There were no statistically significant differences (p>0.05) among AH Plus, Vitremer and gutta-percha groups. MTA produced the smallest number of periodontal lesions (p<0.05).

CONCLUSIONS

It may be concluded that none of the tested materials was able to preserve the integrity of the periodontal tissues in the furcation region, and the use of MTA resulted in the least formation of adjacent periodontal bone lesions revealed by the radiographic comparisons.

In vivo evaluation of the sealing ability of two endodontic sealers in root canals exposed to the oral environment for 45 and 90 days

This in vivo study evaluated the sealing ability of a resin-based sealer (AH Plus) and a zinc oxide-eugenol sealer (Endofill) in dogs' teeth, exposed to the oral environment for 45 and 90 days. Forty eight lower incisors from 8 dogs were endodonticaly treated. A stratified randomization determined the sealer use in each root canal. All canals were filled using the lateral condensation technique. The excess filling material at the cervical portion of the root canal was sectioned, leaving a 10-mm obturation length inside the canal. Teeth were provisionally sealed with glass ionomer cement for 24 h and the canals were exposed to the oral environment for either 45 or 90 days. Therefore, the experimental groups were as follows: A45- AH Plus for 45 days; A90- AH Plus for 90 days; E45- Endofill for 45 days; and E90- Endofill for 90 days (n=12). After the experimental period, the dogs were killed and the lower jaw was removed. The incisors were extracted and the roots were covered with two coats of nail varnish. The teeth were immersed in India ink for 96 h and submitted to diaphanization. Dye leakage (in mm) was measured using stereomicroscopy (10x magnification). The results were statistically analyzed using two-way ANOVA and Tukey test for multiple comparisons (á = 0.05). Group E90 (2.03+/-0.94) showed significantly higher mean leakage value than all other groups (p<0.001). None of the sealers, in both study conditions, were able to prevent dye leakage.

Influence of different methods of cervical flaring on establishment of working length

Objective:

to investigate the influence of three different rotary systems for cervical flaring on establishment of the real working length. Material and methods: Thirty mandibular first molars were submitted to conventional endodontic access and initial working length measurement, followed by irrigation/suction of the pulp chamber with 5% sodium hypochlorite. Teeth were randomly divided into 3 groups (n=10) and cervical flaring of the mesiobuccal canals were performed using one of the following instrument systems: Group 1 – Gates-Glidden burs; Group 2 – Orifice Openers; Group 3 – La Axxess system. Two subsequent numbers of instruments of each rotary system were used and the final working length was recorded. A digital calyper was used to record the working length, in millimeters, to investigate a possible discrepancy between initial and final measurements.

Results:

Analysis of variance (Anova) na Tukey test revealed statistical difference between Group 1 and Groups 2 and 3 (p£ 0.05).

Conclusions:

all groups presented shorter working length after cervical flaring; groups prepared with instruments La Axxes and Orifice Opener presented the best results among the systems studied.

Influence of ProTaper finishing files and sodium hypochlorite on cleaning and shaping of mandibuldar central incisors--a histological analysis

Objective:

This study investigated the influence of the last apical instrument of the ProTaper system with and without 2.5% sodium hypochlorite for cleaning mandibular central incisors.

Material and Methods:

Thirty two mandibular central incisors were divided into six study groups: Group I – F1 instrument with 2.5% sodium hypochlorite; Group II – F1 and F2 with 2.5% sodium hypochlorite; Group III – F1, F2 and F3 with 2.5% sodium hypochlorite; Group IV – F1 with distilled water; Group V – F1 and F2 with distilled water; Group VI – F1, F2 and F3 with distilled water. The two remaining teeth comprised the negative control group. The specimens were prepared following the principles of the technique suggested by the manufacturer and then submitted to histological preparation and morphometric analysis. Data were analyzed statistically by the Kruskal Wallis test at 1% significance level.

Results:

There was statistically significant difference (p<0.01) between all study groups, except between Groups I and VI.

Conclusions:

It was concluded that no technique allowed complete cleaning of the root canals. However, the technique of finishing preparation of the apical third with the F3 instrument with 2.5% sodium hypochlorite irrigation was the most effective.

In vitro comparative study of manual and mechanical rotary instrumentation of root canals using computed tomography

This in vitro study compared, using computed tomography (CT), the amount of dentin removed from root canal walls by manual and mechanical rotary instrumentation techniques. Forty mandibular incisors with dental crown and a single canal were selected. The teeth were randomly assigned to two groups, according to the technique used for root canal preparation: Group I - manual instrumentation with stainless steel files; Group II - mechanical instrumentation with RaCe rotary nickel-titanium instruments. In each tooth, root dentin thickness of the buccal, lingual, mesial and distal surfaces in the apical, middle and cervical thirds of the canal was measured (in mm) using a multislice CT scanner (Siemens Emotion, Duo). Data were stored in the SPSS v. 11.5 and SigmaPlot 2001 v. 7.101 softwares. After crown opening, working length was determined, root canals were instrumented and new CT scans were taken for assessment of root dentin thickness. Pre- and post-instrumentation data were compared and analyzed statistically by ANOVA and Tukey's post-hoc test for significant differences (p=0.05). Based on the findings of this study, it may be concluded that regarding dentin removal from root canal walls during instrumentation, neither of the techniques can be considered more effective than the other.

Comparative in vivo analysis of the sealing ability of three endodontic sealers in dog teeth after post-space preparation

This study compared the sealing ability of RoekoSeal, AH Plus and EndoRez in dog premolars after post-space preparation and exposure to the oral environment. Seventy-four root canals were cleaned, shaped and filled with gutta-percha and one of the sealers. Post spaces were prepared with about 4-mm root canal filling remaining in the apex. Teeth were sealed for 24 h for sealer setting. Teeth were exposed to the oral environment for 45 days. The dogs were killed and root canals were soaked in India ink and sealed for 96 h. The teeth were cleared, and leakage was measured under stereoscopy. The Kruskal-Wallis test was used for analysis. A significant difference was found between EndoRez and RoekoSeal groups (P < 0.05). EndoRez had lower leakage values than RoekoSeal after 45-day exposure to the oral environment. No statistic difference was found in the comparison of AH Plus with the other sealers under study.

Evaluation of two methods of measuring the absorbing capacity of paper points

OBJECTIVE

This study analyzed two methods of measuring the absorbing capacity of paper points (PP), testing the hypothesis that there is a positive correlation between the results from the percentage of increase mass (PIM) and the linear dye penetration (LDP) methods.

METHODS

The initial dry weight (IDW) of each PP was recorded using a digital balance before 1-mm introduction into one of the dye solutions, 1% methylene blue (MB) or 1% rodamine B (RB), for 10s. The PP's were removed from the solution and weighed (final weight - FW). PIM was calculated from the difference between FW and IDW (n=50). The LDP was measured using a stereomicroscope and a ruler (n=50). Data was statistically analyzed using the Pearson correlation and Student's t tests.

RESULTS

Moderate positive correlations between LDP and PIM methods were found using methylene blue (r=0.6356) and rodamine B (r=0.7743), partially confirming the study hypothesis, and suggesting that results from these two methods should be confronted carefully.

SIGNIFICANCE

The results of this study suggest that the most reliable method of measuring the absorbing capacity of paper points is the PIM and investigators should be aware of differences between the two research protocols when comparing results from these two methods (PIM and LDP).

Microbial leakage and apical inflammatory response in dog's teeth after root canal filling with different sealers, post space preparation and exposure to the oral environment

Coronal leakage is an important factor affecting the outcome of endodontic therapy. This study evaluated the microbial leakage (ML) and the apical inflammatory response (AIR) in dog’s teeth after root canal filling with three endodontic sealers, post preparation and exposure to the oral environment, testing the hypothesis that there is a positive correlation between these two histological parameters (ML and AIR). Sixty-four root canals of 8 mongrel dogs were cleaned, shaped and randomly distributed into groups according to the sealer to be used: Sealer 26 (n=18); AH Plus (n=18); RoekoSeal (n=19); no sealer – control group (n=9). Root canals were filled by the lateral condensation technique. Post space preparation left 4 mm of filling material in the apical root third, and specimens were exposed to the oral environment for 90 days. The dogs were killed and jaw blocks were histologically processed using Brown & Brenn and HE staining techniques. ML and AIR were scored from 1 to 4. Results were analyzed statistically using ANOVA, Duncan’s post-hoc test and Spearman’s correlation. ML and AIR score means were: Sealer 26 - 2.44±0.98 and 2.50±0.70; AH Plus - 2.50±0.78 and 2.22±0.54; RoekoSeal - 1.84±0.95 and 2.63±0.83; Control - 2.56±1.23 and 3.11±0.60. Statistically significant differences in AIR scores were found between the AH Plus and control groups (p<0.05). Although RoekoSeal had the lowest ML means, and AH Plus, the lowest AIR means after 90-day exposure to the oral environment, no statistically significant differences were found between the three sealers under study, and no correlation was found between ML and AIR.

Canal Transportation after Root Canal Instrumentation: A Comparative Study with Computed Tomography

This in vitro study used computed tomography (CT) to compare the occurrence of canal transportation in the apical third of mesiobuccal canals in maxillary molars instrumented with 3 techniques. Sixty teeth were assigned to 3 groups (n = 20), and the root canals were instrumented as follows: Group 1, hand instrumentation with K-files; Group 2, K-files coupled to an oscillatory system powered by an electric engine; Group 3, ProTaper NiTi rotary system powered by an electric engine. To compare the canal transportation produced by the different techniques, preinstrumentation and postinstrumentation 3-dimensional CT images were obtained from root cross-sections of the region located 3 mm short of the apical foramen of each root canal. The CT scans were exported to Adobe Photoshop software, and the initial and final images were superimposed to detect the root canal wall differences between them. Canal transportation was measured by the distance between the prepared canal center and the anatomic canal center. The manual technique produced lesser canal transportation (0.10 mm) than the oscillatory and rotary techniques (0.37 and 0.22 mm, respectively); this difference was statistically significant (P=.021). All studied techniques produced canal transportation.

Influence of cervical preflaring on determination of apical file size in maxillary molars: SEM analysis

The purpose of this study was to investigate the influence of cervical preflaring on determination of the initial apical file in mesiobuccal roots of maxillary molars. Fifty first molars with degree of curvature of the mesiobuccal root between 10° and 15° were utilized. After standard access opening and removal of pulp tissue, the working length (WL) was determined at 1 mm from the root apex. Five groups (n=10) were formed at random, according to the type of cervical preflaring performed. In group 1, the size of the initial apical file was determined without cervical preflaring. In groups 2 to 5, the cervical and middle thirds of the canals were preflared with Gates-Glidden drills, K3 Orifice Opener instruments, ProTaper instruments and LA Axxess burs, respectively. Canals were sized manually with K-files, starting with size 08 K-files, inserted passively up to the WL. File sizes were increased until a binding sensation was felt at the WL and the size of the file was recorded. The binding instruments were fixed into the canals at the WL with methylcyanacrylate. Cross-sections of the WL region were examined under scanning electron microscopy and the discrepancies between the canal diameter and the diameter of first file to bind at the WL were calculated using UTHSCSA ImageTool software. Data were analyzed statistically by ANOVA and multiple comparisons were done by Tukey's HSD post-hoc test. Significant differences (p<0.001) were found among the groups. The major discrepancy was observed for the group without preflaring (mean 0.1543 mm ± 0.0216). Cervical preflaring with LA Axxess burs produced the least discrepancies between the canal size and the diameter of the initial apical instrument (mean 0.026 mm ± 0.0037), followed by ProTaper files (mean 0.0567 mm ± 0.0354). Canals preflared with Gates-Glidden drills and K3 Orifice Opener instruments showed statistically similar discrepancy results to each other (p>0.05) (means 0.1167 mm ± 0.0231 and 0.1313 mm ± 0.0344, respectively). In conclusion, preflaring of the cervical and middle thirds improved the determination of the initial apical instrument. Canals preflared with LA Axxess burs showed a more accurate binding of the files to the anatomical diameter at the WL in the mesiobuccal roots of maxillary first molars.

In vitro evaluation of the presence of apical deviation with employment of automated handpieces with continuous and alternate motion for root canal preparation

The present study conducted an in vitro evaluation of the presence of apical deviation on the root canal preparation of the mesiobuccal roots of human maxillary molars employing automated handpieces with continuous motion, the Pow R system (Moyco Union Broach), and alternate motion, the M4 system (Kerr). Analysis of the presence of apical deviation was carried out by means of radiographs obtained on a radiographic desk fabricated for the study. The results demonstrated the lack of statistically significant differences between the two systems as to the evaluation of the presence of apical deviation. There was no correlation between the degree of curvature of the roots and the degree of apical deviation for the continuous motion system. However, there was a statistic difference for the alternate motion system, with a direct correlation of moderate degree.

Apical displacement produced by rotary nickel-titanium instruments and stainless steel files

The aim of this study was to evaluate the apical displacement produced by different rotary nickel-titanium instruments, testing the hypothesis that rotary systems with nickel-titanium instruments produce lower mean values of apical displacement than stainless steel hand instruments. A total of 100 maxillary permanent first molars were selected for the study. The mesiobuccal roots were sectioned at the top cervical third and embedded in blocks of self-curing resin. The specimens were randomly divided into 5 groups and the root canals were prepared using the following nickel-titanium instruments: Group 1 - Quantec system 2000 (Analytic Endodontics, Mexico); Group 2 - Pro-File T.0.04 (Dentsply/Maillefer, Switzerland); Group 3 - Pro-File Series 29 T.0.04 (Dentsply Tulsa, Switzerland); Group 4 - Pow-R T.0.02 (Moyco-Union Broach, USA). Specimens in Group 5 were prepared using stainless steel hand instruments Flexofile (Dentsply/Maillefer, Switzerland). All root canals were previously submitted to cervical preparation using Orifice Shaper instruments #1, 2, 3 and 4 (Dentsply/Maillefer, Switzerland). After odontometry, the remaining root canal was shaped employing increasingly larger instruments, so that the final instrument corresponded to Quantec #9, Pro-File Series 29 #6, and #35 for the other groups. Specimens in Groups 1 to 4 were prepared using an electric handpiece with 16:1 reduction at 350 rpm. The specimens in Group 5 were manually prepared. Apical displacement was measured and recorded by means of radiographic superimposition on a specific desk. Statistical analysis (ANOVA) of the results revealed that all groups presented apical displacements. Considering only the nickel-titanium instruments, Group 4 showed the lowest mean value while Groups 2 and 3 produced the highest mean apical displacement values (p<0.001).

Comparative in vivo analysis of the sealing ability of three endodontic sealers in post-prepared root canals

AIM

To compare the sealing ability of the endodontic sealers AH Plus, Sealer 26 and Endofill in premolar teeth of dogs exposed to the oral cavity after post-preparation.

METHODOLOGY

Forty teeth with two canals each underwent root canal cleaning and shaping. Before filling, the canals were randomly distributed into three groups according to the sealer to be used: Group 1 - AH Plus; Group 2 - Sealer 26; and Group 3 - Endofill (Dentsply, Indústria e Comércio Ltda.). Immediately after filling, the gutta percha and sealer were partially removed from the canals, leaving material only in the apical third of the root. The teeth were temporarily sealed with glass ionomer sealer for 72 h to ensure setting. The coronal seal was then removed and the canals were exposed to the oral cavity for 45 days. The animals were euthanased and their mandibles and maxillae were removed. After abundant irrigation with distilled water, the canals were dried and filled with India ink. The teeth were sealed again for 96 h before extraction. The roots of the extracted premolars were separated and stored in labelled test tubes. The roots were cleared and the extent of dye penetration was measured with a 20x stereoscopic magnifying lens.

RESULTS

Statistical analysis revealed that there were significant differences between the sealers studied (P < 0.001). Means for the extent of dye penetration for AH Plus, Endofill and Sealer 26 were, respectively, 0.13, 2.27 and 3.08 mm.

CONCLUSIONS

After 45 days exposure to the oral cavity, none of the sealers was capable of preventing leakage and coronal dye penetration. There were significant differences between the sealers studied, in terms of mean dye penetration.

In vivo analysis of post space sealing with different adhesive materials

This in vivo study analyzed the sealing ability of two adhesives in post spaces, cyanoacrylate (Super Bonder® - Henkel Loctite Adesivos Ltda., Itapevi, SP, Brazil) and ScotchbondTM Multi-Purpose (3M Dental Products, St. Paul, MN, USA), testing the hypothesis that their use would result in a decreased leakage through the remaining filling material. Forty extracted premolars (80 root canals) of dogs were used. The root canals were cleaned, shaped and filled by the lateral condensation technique using Sealer 26TM. The post space was created removing two thirds of the filling material within the root canal. The canals were randomly divided in three groups, which were treated as follows: Group A received the ScotchbondTM Multi-Purpose adhesive system; for Group B the cyanoacrylate adhesive, Super BonderTM, was employed; and no adhesive was applied into the post space for Group C (control group). A glass ionomer provisional restoration was placed allowing the sealer to set for 72 hours. Then the restoration was removed and the root canal was exposed to the oral environment for 45 days. The dogs were then killed and their jaws were removed. The post spaces were filled with India ink and the teeth were restored for 96 hours. Afterwards, the teeth were extracted and the roots were sectioned at the furcation for allocation to their specific groups. The teeth were turned transparent and the quantitative analysis of leakage was performed using light microscopy. The results showed no significant differences between groups, rejecting the initial hypothesis. Leakage occurred in a great extent in all specimens. Therefore, sealing post spaces with the adhesives used in this study was not an effective method to prevent microleakage.