Efetividade do EDTA 17% na remo??o da smear layer e da medica??o intracanal de hidr?xido de c?lcio das paredes dos canais radiculares: parte II / Effect of 17% EDTA on removal of canal wall smear layer and calciumhydroxide dressing: part II

Objective: the aim of this study was to evaluate, by scanning electron microscopy, the effectiveness of 17% EDTA on removal of canal wall smear layer and calcium hydroxide dressing in different thirds of root canal. Methods: Ttwenty-four premolars were instrumented in the cervical and middle thirds using Gates-Glidden drills. At the working length, the canal was widened up to # 35 file, followed by scaling up to file # 50. After instrumentation, the teeth were divided into four groups according to the treatment received: GI - irrigation performed with 5 ml of NaOCl 2.5 % ; GII - irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15, followed by irrigation with 5 ml of 2.5% NaOCl ; GIII - irrigation with 5 ml of NaOCl 2.5% , drying , application of temporary dressing of Ca (OH )2 with propylene glycol and sealing. After 5 days , removing the sealing irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15, followed by a final flush with 5 ml of 2.5% NaOCl ; GIV - irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15 , followed by irrigation with 5 ml of 2.5% NaOCl , drying and after use of the medication in Ca (OH )2 with the sealing and propylene glycol which was removed after 5 days performing the irrigation with 5 ml of 17% EDTA for 2 and a half minutes , submitted to agitation with file # 15, followed by using 5 ml 2.5% NaOCl . Next, the teeth were prepared and taken to the scanning electron microscope. Results: The images revealed: Group I - a marked presence of smear layer in all three thirds, Group II - removal of almost all of the smear layer in the cervical third and removal of large quantity in the middle third, whereas in the apical third a large quantity of smear layer still remained however, in comparison with the other groups, this was shown to be cleaner; Group III - in the three thirds, the presence of smear layer was observed, which was shown to be much less compacted than that observed in Group 1; Group IV- in all the thirds there was reduction of smear layer and Ca(OH)2-based medication, and presence of several unobstructed dentinal tubules could be observed, demonstrating the second best result observed. Conclusion: It could be concluded that the use of 17% EDTA favored removal of the smear layer and intracanal medication residues in all thirds of the root canal.

Objetivo: Avaliar atrav?s de Microscopia Eletr?nica de Varredura, a efic?cia do EDTA a 17% na remo??o da smear layer e da medica??o de hidr?xido de c?lcio nos diferentes ter?os do canal radicular. M?todos: Vinte e quatro pr?-molares foram instrumentados nos ter?os cervical e m?dio utilizando-se brocas Gates-Glidden. No comprimento de trabalhorealizou-se o alargamento at? a lima #35 seguido do escalonamento at? a lima #50. Ap?s, os dentes foram divididos em quatro grupos de acordo como tratamento recebido: GI - irriga??o realizada com 5 ml de hipoclorito de s?dio a 2,5%; GII - irriga??o com 5 ml de EDTA 17%, durante 2 minutose meio, submetidos a agita??o com a lima #15, seguidos de uma irriga??o com 5 ml de NaOCl a 2,5%; GIII - irriga??o com 5 ml de hipoclorito des?dio a 2,5%, secagem, aplica??o de medica??o intracanal de Ca(OH)2 associado ao propilenoglicol e selamento, ap?s 5 dias, remo??o do selamento, irriga??o com 5 ml de EDTA 17%, durante 2 minutos e meio, submetidos a agita??o com a lima #15, seguida de irriga??o final com 5 ml de NaOCl a 2,5%; GIV - irriga??o com 5 ml de EDTA 17%, durante 2 minutos e meio, submetidos a agita??o com a lima #15, seguidos de uma irriga??o com 5 ml de NaOCl a 2,5%, secagem e ap?s o uso da medica??o intracanal de Ca(OH)2 associado ao propilenoglicol e selamento que foi removido ap?s 5 dias realizando-se a irriga??o com 5 ml de EDTA 17%, durante 2 minutos e meio, submetidos a agita??o com a lima #15, seguida da utiliza??o de 5 ml de NaOCl a 2,5%. A seguir, os dentes foram preparados e levados ao microsc?pio eletr?nico de varredura. Resultados: As imagens revelaram: grupo I - presen?a marcante de smear layer nos tr?s ter?os; grupo II - nota-se a menor quantidade de smear layer no ter?ocervical e m?dio enquanto no apical h? presen?a mais marcante; grupo III- no ter?o cervical e apical h? presen?a de smear layer compactada nas paredes do canal e o aspecto mais disperso da medica??o enquanto no ter?o m?dio nota-se presen?a da medica??o no interior dos canal?culos; grupo IV- em todos os ter?os houve redu??o da smear layer e da medica??o e a presen?a de v?rios canal?culos dentin?rios desobstru?dos.Conclus?o: Pode-se concluir que o uso do EDTA a 17% favoreceu a remo??o da lama dentin?ria e dos res?duos da medica??o intracanal em todos os ter?os do canal radicular.

Effectiveness of EDTA 17% in the removal of smear layer and calcium hydroxide dressing from the root canal walls / Efetividade do EDTA 17 porcentos na remoção da smear layer e da medicação intracanal de hidróxido de cálcio das paredes dos canais radiculares

Objective: To evaluate the effectiveness of EDTA 17% on the removal of the smear layer and the calcium hydroxide dressing in different thirds of the root canal. Methods: Forty canines were instrumented in the cervical and middle thirds using Gates-Glidden drills. In the working length, enlargements were carried out with files up to #35 followed by scaling up to #50. After instrumentation, the teeth were divided into four groups according to the type of final irrigation: Group I - irrigation with 5 ml NaOCl 2.5%, Group II - irrigation with 5 ml EDTA 17% followed by irrigation with 5 ml NaOCl 2.5%; Group III - irrigation with 5 ml NaOCl 2.5%; Group IV - irrigation with 5ml EDTA 17% followed by one with NaOCl 2.5%. The teethwere filled and radiographed. The teeth were then submitted to the clearing technique and photographed by means of a camera coupled toa stereomicroscope. Results: The images showed: Group I - the presence of smear layer in the three thirds and fewer accessory canals filled; group II - the smaller amount of smear layer on the cervical, middle and apical third and filling of the accessory canals; group III - there are residues from the dressing in the cervical, middle and apical third, and group IV - in all of the thirds there was a reduction in the presence of dressing remnants and the largest number of filled accessory canals.Conclusion: It can be concluded that the use of EDTA 17% favored the removal of the smear layer and the remnants of the intracanal dressing in all thirds of the root canal.

Objetivo: Avaliar a eficácia do EDTA a 17% na remoção da smear layer e da medicação de hidróxido de cálcio nos diferentes terços do canal radicular. Métodos: Quarenta caninos inferiores foram instrumentados nos terços cervical e médio utilizando-se brocas Gates-Glidden. No comprimento de trabalho realizou-se o alargamento até a lima #35 seguido do escalonamento até a lima #50. Após os dentes foram divididos em quatro grupos de acordo com a irrigação final: grupo I - irrigação com 5ml de NaOCl 2,5%; grupo II - irrigação com 5 ml de EDTA 17% seguidos de5ml de NaOCl 2,5%; grupo III - irrigação com 5ml de NaOCl 2,5%; grupo IV - irrigação com 5ml de EDTA 17% seguidos de NaOCl 2,5%. Os dentes foram obturados e radiografados. Posteriormente os dentes foram diafanizados e fotografados por meio de máquina fotográficaacoplada em lupa estereoscópica. Resultados: As imagens revelaram: grupo I - presença de smear layer nos três terços e o menor número de canais acessórios preenchidos; grupo II - nota-se a menor quantidade de smear layer no terço cervical, médio e apical e a obturação de canais acessórios; grupo III - há presença de resíduos da medicação no terço cervical, médio e apical; grupo IV - em todos os terços houve redução da presença de resíduos da medicação e o maior número de canais acessórios preenchidos. Conclusão: Pode-se concluir que o uso do EDTA a 17% favoreceu a remoção dos resíduos da medicação intracanal do canal radicular.

Análise in vitro da anatomia interna de pré-molares inferiores inseridos em mandíbulas humanas por meio de exame radiográfico e tomografia computadorizada Cone Beam / In vitro analysis of the internal anatomy of lower premolars inserted in human mandibles through radiographs and Cone Beam computed tomography

Objetivo: Analisar a anatomia radicular interna de pré-molares inferiores por meio dos exames radiográfico e tomográfico. Métodos: A amostragem constitui-se de dez pré-molares inferiores, inseridos em quatro mandíbulas humanas, provenientes do acervo da disciplina de Anatomia da Universidade Federal do Espírito Santo. As mandíbulas foram primeiramente fotografadas. Em seguida os dentes foram submetidos ao exame radiográfico pela técnica periapical. As imagens obtidas foram digitalizadas, armazenadas em arquivo de computador e analisadas por três examinadores. As tomografias computadorizadas dos espécimes foram realizadas pela técnica Cone Beam. Resultados: Os resultados evidenciaram que as médias das avaliações pelo exame radiográfico foram de 50%, 43% e 7% para um canal, dois canais e três canais, respectivamente. E pelo exame tomográfico foi encontrado em 40% dos dentes avaliados um único canal radicular (tipo I) e em 60% dos dentes, canais do tipo V, ou seja, canais que começam unitários no nível de câmara pulpar e, antes de alcançarem o ápice, sofrem uma bifurcação.Conclusão: Conclui-se que a imagem tridimensional proporcionada pela tomografia computadorizada Cone Beam representa um grande avanço, como método auxiliar, para se estabelecer o diagnóstico endodôntico.

Objective: The aim of this study was to analyze the root anatomy of lower pre-molars through X-ray and computed tomography scan (cone well).Methods: The sample comprised ten premolars embedded in four human mandibles from the collection of the Anatomy section of the Federal University of Espírito Santo. The jaws were first photographed and the teeth were then submitted to radiographic examination via the periapical technique. The images were digitized, stored on computer files and analyzed by three examiners. The computed tomography-scanning of the specimens was made using the cone beam technique. Results: The results showed that the mean ratings of the radiographic examination were 50%, 43% and 7% for one, two and three root canals, respectively. The computed tomography scan detected one single root canal (type I) in 40% of teeth assessed and V-type root canals in 60% of the teeth. In other words, root canals starting out as one at the level of the pulp chamber split before reaching the apex. Conclusion: The conclusion is that the three-dimensional image provided by the the cone beam technique represents a major advance as a method of establishing endodontic diagnosis.

Shear bond strength of self-etching and total-etch adhesive systems to Er:YAG laser-irradiated primary dentin.

PURPOSE: The purpose of this study was to assess in vitro the shear bond strength of self-etching and total-etch adhesive systems to Er:YAG laser-irradiated primary dentin. METHODS: Forty crowns of primary canines were embedded in acrylic resin and mechanically ground to expose a flat dentin surface. The specimens were randomly assigned to 2 groups (N=20), according to the adhesive system: (A) Single Bond (SB); and (B) Adper Prompt (AP). Each group was divided into 2 subgroups (N=10), depending on the surface treatment: (1) conventional bonding protocol, as recommended by the manufacturers; and (2) irradiation of the dentin site with a 2.94-microm wavelength Er:YAG laser, with a 300-mJ pulse energy and a 2-Hz repetition rate followed by the bonding protocol. In both groups, a 3-mm diameter dentin bonding site was demarcated, the adhesive systems were applied, and resin composite cylinders were bonded. After 24 hours in distilled water, shear bond strength was tested at a crosshead speed of 0.5 mm/minute. RESULTS: Means (in MPa) were: group A1=14.14(+/-1.7); group A2=8.41(+/-1.04); group B1=6.88(+/-1.12); and group B2=4.19(+/-0.7). Data were submitted to statistical analysis using 2-way analysis of variance and t test at 5% significance level. CONCLUSION: Irradiation of primary dentin with the Er:YAG laser decreased the bond strength of total-etch and self-etching adhesive systems.

Effect of different bleaching systems on the ultrastructure of bovine dentin.

The aim of this study was to evaluate in vitro the effect of different in-office bleaching systems on the surface morphology of bovine dentin. Thirty tooth fragments measuring 4 x 4mm, containing enamel and dentin, were obtained from the crowns of extracted bovine incisors. Samples were subjected to simulated intracoronal bleaching techniques using conventional (Opalescence Endo and Whiteness Super Endo) and light-activated systems (Opalescence Xtra) and Whiteness HP Maxx). Controls were treated with either sodium perborate mixed with 10% hydrogen peroxide or no bleaching agent. The samples were observed under SEM and the recorded images were evaluated for topographic alterations. The ultrastructural alterations of dentin observed in this study varied greatly between groups according to the products used. Higher pH products (Whiteness HP Maxx) and Opalescence Xtra) associated with in-office techniques yielded better maintenance of dentin ultrastructure. Apparently, both low pH and hydrogen peroxide oxidation play a role in altering the ultrastructure of dentin during internal dental bleaching. The use of alkaline products with reduced time of application (in-office techniques) may decrease such morphological alterations.

Influence of cervical preflaring on apical file size determination in maxillary lateral incisors.

The purpose of this study was to investigate the influence of cervical preflaring on determination of the initial apical file in maxillary lateral incisors. Forty human lateral incisors with complete root formation were used. After standard access cavities, a size 06 K-file was inserted into each canal until the apical foramen was reached. The WL (WL) was set 1 mm short of the apical foramen. Four groups (n=10) were formed at random, according to the type of cervical preflaring performed. Group 1 received the initial apical instrument without previous preflaring of the cervical and middle root canal thirds. Group 2 had the cervical and middle root canal thirds enlarged with nickel-titanium Orifice Opener instruments. Group 3 had the cervical and middle root canal thirds enlarged with Gates-Glidden drills. Titanium-nitrite treated, stainless steel LA Axxess burs were used for preflaring the cervical and middle root canal thirds of group 4. Each canal was sized using manual K-files, starting with size 08 files with passive movements until the WL was reached. File sizes were increased until a binding sensation was felt at the WL, and the instrument size was recorded for each tooth. The apical region was then observed under a stereoscopic magnifier, images were recorded digitally and the differences between root canal and maximum file diameters were recorded (in mm) for each sample. Significant differences were found between the groups regarding the anatomical diameter at the WL and the first file to bind the canal (p = 0.01). The major discrepancy was found when no preflaring was performed (0.1882 mm average). Canals preflared with Orifice Opener instruments (0.0485 mm average) and Gates-Glidden drills (0.1074 mm average) also showed great discrepancy. The LA Axxess burs produced the smallest differences between anatomical diameter and first file to bind (0.0119 mm average). Instrument binding technique for determining anatomical diameter at WL was not accurate. Preflaring of the cervical and middle thirds of the root canal improved anatomical diameter determination; the instrument used for preflaring played a major role on determination of the anatomical diameter at the WL. Canals preflared with LA Axxess burs created a more accurate relationship between file size and anatomical diameter.

Shear bond strength to primary enamel: influence of Er:YAG laser irradiation distance.

PURPOSE: The purpose of this study was to evaluate in vitro the influence of Er:YAG laser irradiation distance on the shear bond strength of an adhesive restorative system to primary enamel. METHODS: Fifty buccal surfaces of extracted human canines were ground and divided into 5 groups (N=10). The control group was etched with 35% phosphoric acid (CA). In the lased groups, the enamel surface treatment was performed with the Er:YAG laser (80mJ/2Hz) by varying the irradiation distance (12, 14, 16, and 17 mm), followed by acid etching. An adhesive agent (Single Bond) was applied on the bonding sites, and resinous cylinders (Filtek Z250) were prepared. Shear bond strength tests were performed in a universal testing machine (0.5 mm/minute). Failure mode was assessed using a X40 magnification stereomicroscope. Data were submitted to statistical analysis by analysis of variance. RESULTS: The means in MPa were: (1) CA=18.76 (+/-6.68); (2) 12 mm=12.73 (+/-5.46); (3) 14 mm=15.9 (+/-6.81); (4) 16 mm=20.1 (+/-6.94); and (5) 17 mm=15.15 (+/-6.81). There was no statistically significant difference (P<.05) among the tested groups. CONCLUSION: The different Er:YAG laser distance irradiations did not influence the adhesive resistance of the resinous system to enamel, even when compared with the control group (acid etching solely).

Influence of cervical preflaring on apical file size determination in maxillary lateral incisors

The purpose of this study was to investigate the influence of cervical preflaring on determination of the initial apical file in maxillary lateral incisors. Forty human lateral incisors with complete root formation were used. After standard access cavities, a size 06 K-file was inserted into each canal until the apical foramen was reached. The WL (WL) was set 1 mm short of the apical foramen. Four groups (n=10) were formed at random, according to the type of cervical preflaring performed. Group 1 received the initial apical instrument without previous preflaring of the cervical and middle root canal thirds. Group 2 had the cervical and middle root canal thirds enlarged with nickel-titanium Orifice Opener instruments. Group 3 had the cervical and middle root canal thirds enlarged with Gates-Glidden drills. Titanium-nitrite treated, stainless steel LA Axxess burs were used for preflaring the cervical and middle root canal thirds of group 4. Each canal was sized using manual K-files, starting with size 08 files with passive movements until the WL was reached. File sizes were increased until a binding sensation was felt at the WL, and the instrument size was recorded for each tooth. The apical region was then observed under a stereoscopic magnifier, images were recorded digitally and the differences between root canal and maximum file diameters were recorded (in mm) for each sample. Significant differences were found between the groups regarding the anatomical diameter at the WL and the first file to bind the canal (p = 0.01). The major discrepancy was found when no preflaring was performed (0.1882 mm average). Canals preflared with Orifice Opener instruments (0.0485 mm average) and Gates-Glidden drills (0.1074 mm average) also showed great discrepancy. The LA Axxess burs produced the smallest differences between anatomical diameter and first file to bind (0.0119 mm average). Instrument binding technique for determining anatomical diameter...

Avaliou-se a influência do pré-alargamento cervical na determinação do instrumento apical inicial em incisivos laterais superiores. Foram selecionados quarenta incisivos laterais superiores com completa formação radicular. Concluída cirurgia de acesso, uma lima tipo K #06 foi inserida em cada canal até atingir o forame apical. A partir desse comprimento foi reduzido 1 mm e determinou-se o comprimento de trabalho. Os dentes foram divididos em cinco grupos (n=10), de acordo com o tipo de alargamento cervical realizado: Grupo 1: sem alargamento; Grupo 2: instrumentos Orifice Opener; Grupo 3: brocas Gates-Glidden; Grupo 4: LA Axxess. Os canais foram explorados com lima do tipo K inserindo-se passivamente a lima 08 no comprimento de trabalho. A seguir, limas de maiores diâmetros foram sucessivamente introduzidas no canal radicular, até se obter a sensação de travamento no comprimento de trabalho. O diâmetro desse instrumento foi registrado, e este foi fixado em posição no canal com cianoacrilato de metila. Secções transversais realizadas no comprimento de trabalho foram observadas em lupa estereoscópica com auxílio de máquina fotográfica acoplada e as imagens foram digitalizadas. A diferença entre o menor diâmetro do canal e o diâmetro do instrumento apical inicial foi calculada para cada amostra (em mm). A análise estatística indicou diferença estatisticamente significante entre os grupos experimentais (p=0.01). A maior discrepância foi representada pelo grupo que não recebeu o pré-alargamento (média: 0,1882 mm). O grupo no qual o pré-alargamento foi realizado com instrumentos Orifice Opener também apresentou elevada discrepância entre o diâmetro anatômico e o instrumento apical inicial (média: 0,0485 mm), seguido pelo grupo que se utilizou Gates-Glidden (média: 0,1074 mm). As brocas LA Axxess promoveram a menor diferença entre o diâmetro anatômico no comprimento de trabalho e o instrumento apical inicial (média: 0,0119 mm). Pode-se concluir...

Evaluation of apical microleakage of teeth sealed with four different root canal sealers

OBJECTIVES: to compare the apical sealing ability of four root canal sealers. MATERIAL AND METHODS: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with gutta-percha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal. RESULTS: AH Plus (0.02 mm ± 0.07), Epiphany (0.00 mm ± 0.00) and EndoREZ (0.32 mm ± 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73) and was statistically different from the other sealers (p<0.01). CONCLUSION: the resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.

OBJETIVOS: comparar a capacidade de selamento apical de quatro cimentos endodônticos. MÉTODOS: quarenta caninos superiores humanos extraídos foram instrumentados 1 mm aquém do ápice anatômico e distribuídos aleatoriamente em quatro grupos (n=10), de acordo com o cimento endodôntico utilizado para a obturação: Endofill, AH Plus, EndoREZ e Epiphany. Os canais radiculares foram obturados pela técnica da condensação lateral com os cimentos e com cones de guta-percha, exceto o grupo do Epiphany, no qual os cones de resina (Resilon) foram utilizados. Os dentes foram imersos em nanquim por sete dias e submetidos ao processo de diafanização e, então, clarificados empregando-se o salicilato de metila. A extensão de penetração via apical do corante foi medida por meio de um microscópio de mensuração em todas as faces do terço apical. RESULTADOS: AH Plus (0,02 mm ± 0,07), Epiphany (0,00 mm ± 0,00) e EndoREZ (0,32 mm ± 0,62) não diferiram estatisticamente entre si (p>0,01). EndoFill apresentou a maior média de penetração do corante (0,83 mm ± 0,73) e diferiu estatisticamente dos demais (p<0,01). CONCLUSÕES: os três cimentos resinosos apresentaram menor microinfiltração que o cimento à base de óxido de zinco e eugenol, porém, promoveram selamento apical semelhante entre si.

Evaluation of apical microleakage of teeth sealed with four different root canal sealers%Avaliação da microinfiltração apical em dentes obturados com quatro diferentes cimentos endodônticos

OBJETIVOS: comparar a capacidade de selamento apical de quatro cimentos endodônticos. MÉTODOS: quarenta caninos superiores humanos extraídos foram instrumentados 1 mm aquém do ápice anatômico e distribuídos aleatoriamente em quatro grupos (n=10), de acordo com o cimento endodôntico utilizado para a obturação: Endofill, AH Plus, EndoREZ e Epiphany. Os canais radiculares foram obturados pela técnica da condensação lateral com os cimentos e com cones de guta-percha, exceto o grupo do Epiphany, no qual os cones de resina (Resilon) foram utilizados. Os dentes foram imersos em nanquim por sete dias e submetidos ao processo de diafanização e, então, clarificados empregando-se o salicilato de metila. A extensão de penetração via apical do corante foi medida por meio de um microscópio de mensuração em todas as faces do terço apical. RESULTADOS: AH Plus (0,02 mm ± 0,07), Epiphany (0,00 mm ± 0,00) e EndoREZ (0,32 mm ± 0,62) não diferiram estatisticamente entre si (p>0,01). EndoFill apresentou a maior média de penetração do corante (0,83 mm ± 0,73) e diferiu estatisticamente dos demais (p<0,01). CONCLUSÕES: os três cimentos resinosos apresentaram menor microinfiltração que o cimento à base de óxido de zinco e eugenol, porém, promoveram selamento apical semelhante entre si.

Evaluation of apical microleakage of teeth sealed with four different root canal sealers.

OBJECTIVES: To compare the apical sealing ability of four root canal sealers. MATERIAL AND METHODS: Forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with gutta-percha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal. RESULTS: AH Plus (0.02 mm +/- 0.07), Epiphany (0.00 mm +/- 0.00) and EndoREZ (0.32 mm +/- 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm +/- 0.73) and was statistically different from the other sealers (p<0.01). CONCLUSION: The resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.

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

The purpose of this study was to investigate the influence of cervical preflaring on the determination of the first file that binds at working length (WL) in buccal roots of maxillary premolars. Five groups (n=10) were formed at random and, after standard access cavities, the WL was determined 1 mm short from the apex. In group 1, the initial apical file was inserted without preflaring of cervical and middle thirds of the root canals. In groups 2 to 5, the cervical and middle thirds were enlarged with sizes 90 and 110 Gates-Glidden drills, K(3) Orifice Opener instruments, ProTaper instruments and LA Axxess burs, respectively. Canals were sized manually with K-files, starting with No. 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 instrument was recorded. Transversal sections of the WL regions were examined under scanning electron microscopy and the discrepancies between the canal diameter and first file to bind at the WL were assessed. Significant differences (p<0.001) were found between the groups. The major discrepancy was found without preflaring (mean 157.8 microm). LA Axxess burs produced the smallest discrepancy (mean 0.8 microm). Gates-Glidden drills and K(3) Orifice Opener instruments showed no significant differences (p>0.05) between their results (83.2 microm and 73.6 microm, respectively). The discrepancy for ProTaper instruments was 35.4 microm on average. In conclusion, the instrument binding technique for determination of the anatomical diameter at the WL was not precise. Preflaring of the cervical and middle thirds improved the determination of the anatomical diameter at the WL, and the type of instrument played a major role. Canals preflared with LA Axxess burs showed a more accurate binding of the files to anatomical diameter.

Influence of gutta-percha points on the filling of simulated lateral canals

O objetivo deste estudo foi avaliar in vitro o percentual de preenchimento de canais laterais artificiais em dentes obturados com cones de guta-percha TP medium e estandardizados. Vinte caninos inferiores humanos foram preparados com os instrumentos LA Axxess (SybronEndo) e o sistema rotatório K3 Endo (SybronEndo) até a lima #50, de acordo com a técnica Free Tip Preparation. Durante a instrumentação, os canais radiculares foram alternadamente irrigados com solução de hipoclorito de sódio a 1% e EDTA a 17%. Seis canais laterais artificiais foram confeccionados no terço apical de cada dente. Os dentes foram então divididos em dois grupos (n=10): Grupo 1 - obturados com cones de guta-percha principais TP médium (Dentsply, Mailleffer), Grupo 2 - obturados com cones de guta-percha principais estandardizados (Dentsply, Mailleffer). A obturação do canal radicular foi complementada com o cimento obturador AH Plus (Dentsply, Mailleffer) e cones de guta-percha acessórios (Dentsply, Mailleffer), de acordo com a técnica clássica. Os dentes foram radiografados e as imagens digitalizadas. Realizou-se a mensuração do percentual de obturação dos canais laterais em cada grupo por meio do software Image Tool 2.02. A análise estatística dos dados por meio do teste não paramétrico Mann-Whitney U evidenciou diferença significante (p<0.01) entre os grupos experimentais. O grupo obturado com cones TP medium promoveu maior percentual de preenchimento dos canais laterais. Pode-se concluir que a utilização de cones de guta-percha principais com maior conicidade resultou obturação mais efetiva dos canais laterais artificiais, quando comparada ao emprego de cones de guta-percha estandardizados.

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

O objetivo deste estudo foi avaliar a influência do pré-alargamento cervical na determinação do instrumento apical inicial em raízes vestibulares de pré-molares superiores. Foram selecionados 50 primeiros pré-molares superiores apresentando duas raízes. Após a cirurgia de acesso e determinação do comprimento de trabalho 1mm aquém do ápice, os dentes foram divididos aleatoriamente em 5 grupos distintos, de acordo com o tipo de alargamento realizado no terço cervical e médio de cada canal: Grupo 1- sem alargamento cervical; Grupo 2 — brocas Gates-Glidden (90, 110); Grupo 3 — instrumentos K3 Orifice Openers; Grupo 4 — instrumentos ProTaper; Grupo 5 — brocas LA Axxess. Os canais foram explorados com uma lima tipo K inserindo-se passivamente uma lima 08 no comprimento de trabalho. Limas de diâmetros maiores foram sucessivamente introduzidas no canal radicular até obter a sensação de travamento no comprimento de trabalho, e o diâmetro desse instrumento foi registrado. As secções transversais realizadas no comprimento de trabalho foram observadas por microscopia eletrônica de varredura e a diferença entre o menor diâmetro do canal e o diâmetro do instrumento apical inicial foi calculada para cada amostra. Houve diferença estatisticamente significante entre os grupos experimentais (p<0,001). A maior discrepância foi revelada pelo grupo em que não realizou-se o pré-alargamento (média: 157.8 µm). As brocas LA Axxess proporcionaram a menor diferença entre o diâmetro anatômico e o instrumento apical inicial (média: 0.8 µm). As brocas Gates-Glidden e os instrumentos Orifice Opener foram estatisticamente semelhantes (média: 83.2 µm e média: 73.6 µm, respectivamente). Os instrumentos ProTaper apresentaram uma média de 35.4 µm para os valores de discrepância. Pode-se concluir que a técnica de determinação do instrumento apical inicial não é precisa. O pré-alargamento dos terços cervical e médio do canal torna mais fiel a determinação do diâmetro anatômico no comprimento de trabalho. O pré-alargamento do canal realizado com brocas LA Axxess evidenciaram maior precisão do travamento das limas no diâmetro anatômico.

Influence of gutta-percha points on the filling of simulated lateral canals.

The aim of this study was to investigate, in vitro, the percentage of filling of simulated lateral canals in teeth obturated with TP medium and standardized gutta-percha points. Twenty human mandibular canines were prepared with LA Axxess (SybronEndo) and K³ Endo rotary system (SybronEndo) up to a #50 file, according to the Free Tip Preparation Technique. During instrumentation, the root canals were alternately irrigated with 1% sodium hypochlorite and 17% EDTA. Six artificial lateral canals were prepared at the apical third of each tooth. Then, the teeth were assigned to two groups (n=10): Group 1 - filled with TP medium master gutta-percha points (Dentsply, Mailleffer); Group 2 - filled with standardized master gutta-percha points (Dentsply, Mailleffer). Root canal filling was complemented with AH Plus sealer (Dentsply, Mailleffer) and accessory gutta-percha points (Dentsply, Mailleffer), according to the classic technique. The teeth were radiographed and the images obtained were digitized. Linear measurements of the percentage of filling of the artificial lateral canals in each group were accomplished on the Image Tool 2.02 software. Statistical analysis of the data using Mann-Whitney U non-parametric test evidenced significant difference (p<0.01) between the experimental groups. The group obturated with TP medium points yielded higher percentage of filling of the lateral canals. It may be concluded that the use of master gutta-percha points with larger taper resulted in better filling of the simulated lateral canals, as compared to the use of standardized master gutta-percha points.

Shear bond strength of pit-and-fissure sealants to saliva-contaminated and noncontaminated enamel.

PURPOSE: The purpose of this study was to investigate the shear bond strength of 2 resin-based pit-and-fissure sealants--Clinpro and Fluroshield--to saliva-contaminated and noncontaminated enamel. METHODS: Forty buccal halves of permanent molar crowns were individually embedded in polyester resin and ground with wet silicone carbide papers to obtain flat enamel surfaces. The specimens were randomly assigned to 2 groups: (A) without contamination; and (B) contaminated with 0.01 ml of fresh human saliva. Each group was divided into 2 subgroups (N=10), according to the sealant applied: (1) Clinpro; and (2) Fluroshield. Shear bond strength was tested at a crosshead speed of 0.5 mm/min. Failure mode was assessed. RESULTS: Means (MPa) were: (1) A1=7.66 +/- 3.12; A2=12.39 +/- 4.34; (2) B1=5.05 +/- 1.44; B2=10.44 +/- 2.35. Data were submitted to analysis of variance and Scheffé's statistical test (P<.05). There was a statistically significant difference (P<.05) between both the sealants and the experimental conditions analyzed. Fluroshield provided higher bond strength and was different from Clinpro (P<.05) in the absence of contamination. Within the saliva-contaminated group, however, no statistically significant difference (P>.05) was observed between the tested materials. CONCLUSIONS: It may be concluded that, under dry conditions, the filled pit-and-fissure sealant (Fluroshield) yielded better bonding performance. Salivary contamination undermined the adhesion of both materials to enamel and resulted in lower bond strengths.