Prevalence and morphometric analysis of three-rooted mandibular first molars in a Brazilian subpopulation

ABSTRACT The knowledge of the internal anatomy of three-rooted mandibular molars may help clinicians to diagnose and plan the root canal treatment in order to provide adequate therapy when this variation is present. Objectives: To determine the prevalence of three-rooted mandibular molars in a Brazilian population using cone beam computed tomography (CBCT) and to analyze the anatomy of mandibular first molars with three roots through micro-CT. Material and Methods: CBCT images of 116 patients were reviewed to determine the prevalence of three-rooted first mandibular molars in a Brazilian subpopulation. Furthermore, with the use of micro-CT, 55 extracted three-rooted mandibular first molars were scanned and reconstructed to assess root length, distance between canal orifices, apical diameter, Vertucci's classification, presence of apical delta, number of foramina and furcations, lateral and accessory canals. The distance between the orifice on the pulp chamber floor and the beginning of the curvature and the angle of canal curvature were analyzed in the distolingual root. Data were compared using the Kruskal-Wallis test (α=0.05). Results: The prevalence of three-rooted mandibular first molars was of 2.58%. Mesial roots showed complex distribution of the root canal system in comparison to the distal roots. The median of major diameters of mesiobuccal, mesiolingual and single mesial canals were: 0.34, 0.41 and 0.60 mm, respectively. The higher values of major diameters were found in the distobuccal canals (0.56 mm) and the lower diameters in the distolingual canals (0.29 mm). The lowest orifice distance was found between the mesial canals (MB-ML) and the highest distance between the distal root canals (DB-DL). Almost all distal roots had one root canal and one apical foramen with few accessory canals. Conclusions: Distolingual root generally has short length, severe curvature and a single root canal with low apical diameter.

Experimental Calcium Silicate-Based Cement with and without Zirconium Oxide Modulates Fibroblasts Viability

The aim of this study was to verify whether the use of zirconium oxide as a radiopacifier of an experimental calcium silicate-based cement (WPCZO) leads to cytotoxicity. Fibroblasts were treated with different concentrations (10 mg/mL, 1 mg/mL, and 0.1 mg/mL) of the cements diluted in Dulbecco's modified Eagle's medium (DMEM) for periods of 12, 24, and 48 h. Groups tested were white Portland cement (WPC), white Portland cement with zirconium oxide (WPCZO), and white mineral trioxide aggregate Angelus (MTA). Control group cells were not treated. The cytotoxicity was evaluated through mitochondrial-activity (MTT) and cell-density (crystal violet) assays. All cements showed low cytotoxicity. In general, at the concentration of 10 mg/mL there was an increase in viability of those groups treated with WPC and WPCZO when compared to the control group (p<0.05). A similar profile for the absorbance values was noted among the groups: 10 mg/mL presented an increase in viability compared to the control group. On the other hand, smaller concentrations presented a similar or lower viability compared to the control group, in general. A new dental material composed of calcium silicate-based cement with 20% zirconium oxide as the radiopacifier showed low cytotoxicity as a promising material to be exploited for root-end filling.

Resumo O objetivo deste estudo foi verificar se o uso do óxido de zircônia como radiopacificador de um cimento experimental à base de silicato de cálcio (WPCZO) levou a citotoxicidade. Os fibroblastos foram tratados com diferentes concentrações (10 mg/mL, 1 mg/mL e 0,1 mg/mL) dos cimento diluídos em meio Eagle modificado por Dulbecco (DMEM) durante períodos de 12, 24, e 48 horas. Os grupos testados foram: cimento Portland (WPC), cimento Portland branco com óxido de zircônio (WPCZO) e MTA Angelus branco (MTA). No grupo controle as células não foram tratadas. A citotoxicidade foi avaliada por meio da mitocondrial-atividade (MTT) e ensaio de densidade celular (cristal violeta). Todos os cimentos apresentaram baixa citotoxicidade. Em geral, na concentração de 10 mg/mL, houve um aumento na viabilidade desses grupos tratados com WPC e WPCZO quando comparado com o grupo controle (p <0,05). Um perfil semelhante para os valores de absorvância foi observado entre os grupos: 10 mg/mL apresentaram um aumento da viabilidade em relação ao grupo controle. Por outro lado, as concentrações menores apresentaram uma viabilidade semelhante ou inferior em comparação com o grupo controle, em geral. Um novo material odontológico composto de cimento à base de silicato de cálcio com 20% de óxido de zircônio, como o radiopacificador, apresentou baixa citotoxicidade e pode ser explorado como um material promissor para retrobturações.

Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances

The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG),Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract fromCasearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide paste promoted the highest inflammatory response.

Rat subcutaneous tissue response to calcium silicate containing different arsenic concentrations

Objective: To evaluate the response of rat subcutaneous tissue in implanted polyethylene tubes that were filled with GMTA Angelus and Portland cements containing different arsenic concentrations. Material and Methods: Atomic absorption spectrophotometry was utilized to obtain the values of the arsenic concentration in the materials. Thirty-six rats were divided into 3 groups of 12 animals for each experimental period. Each animal received two implants of polyethylene tubes filled with different test cements and the lateral of the tubes was used as a control group. After 15, 30 and 60 days of implantation, the animals were killed and the specimens were prepared for descriptive and morphometric analysis considering: inflammatory cells, collagen fibers, fibroblasts, blood vessels and other components. The results were analyzed utilizing the Kuskal-Wallis test and the Dunn's Multiple test for comparison (p<0.05). Results: The materials showed, according to atomic absorption spectrophotometry, the following doses of arsenic: GMTA Angelus: 5.01 mg/kg, WPC Irajazinho: 0.69 mg/kg, GPC Minetti: 18.46 mg/kg and GPC Votoran: 10.76 mg/kg. In a 60-day periods, all specimens displayed a neoformation of connective tissue with a structure of fibrocellular aspect (capsule). Control groups and MTA Angelus produced the lower amount of inflammatory reaction and GPC Minetti, the highest reaction. Conclusions: There was no direct relationship between the concentration of arsenic present in the composition of the materials and the intensity of the inflammatory reactions. Higher values, as 18.46 mg/kg of arsenic in the cement, produce characteristics of severe inflammation reaction at the 60-day period. The best results were found in MTA angelus. .

Shaping ability of Reciproc and TF Adaptive systems in severely curved canals of rapid microCT-based prototyping molar replicas

Objective: To evaluate the shaping ability of Reciproc and Twisted-File Adaptive systems in rapid prototyping replicas. Material and Methods: Two mandibular molars showing S-shaped and 62-degree curvatures in the mesial root were scanned by using a microcomputed tomography (μCT) system. The data were exported in the stereolitograhic format and 20 samples of each molar were printed at 16 µm resolution. The mesial canals of 10 replicas of each specimen were prepared with each system. Transportation was measured by overlapping radiographs taken before and after preparation and resin thickness after instrumentation was measured by μCT. Results: Both systems maintained the original shape of the apical third in both anatomies (P>0.05). Overall, considering the resin thickness in the 62-degree replicas, no statistical difference was found between the systems (P>0.05). In the S-shaped curvature replica, Reciproc significantly decreased the thickness of the resin walls in comparison with TF Adaptive. Conclusions: The evaluated systems were able to maintain the original shape at the apical third of severely curved mesial canals of molar replicas. .

Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

Objectives: To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods: White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05). Results: The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05). Conclusions: The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated. .

Influence of the Method in Root Canal Filling Using Active Lateral Compaction Techniques

The aim of this study was to evaluate, by stereomicroscopy and confocal laser microscopy, the influence of different lateral compaction methods for the obturation quality, as well as the time spent for the procedure. Thirty root canals of freshly extracted single-rooted human teeth were prepared with the ProTaper system up to F5 instrument and filled with gutta-percha and AH Plus sealer by the lateral compaction technique. The teeth were divided into 3 groups (n=10) in accordance with the method used for the lateral compaction, as follows: Manual, Mechanical and Ultrasonic. The sealers were stained with rhodamine B dye in a proportion of 0.1% per gram in weight to allow for the analysis under a confocal microscope. During the root filling procedure, the time spent was recorded with a stopwatch. The specimens were stored at 37 °C for 48 h, and then sectioned at 2, 4 and 6 mm from the apex. The percentage of gutta-percha, sealer and void areas were evaluated using a stereomicroscope and sealer penetration perimeter by confocal laser microscope. Statistical analyses were performed using the Kruskall-Wallis and Dunn tests (p<0.05). The mechanical method required a shorter time for the lateral compaction than the manual method (p<0.05). There were no significant differences (p>0.05) for the perimeter of the dentin with sealer penetration among all groups. The mechanical method showed a higher (p<0.05) percentage of gutta-percha and less sealer at the 4 mm section in comparison with the manual method. The ultrasonic group showed intermediate values. The void areas found in the root filling were similar (p>0.05) between the three methods. In conclusion, the fastest lateral compaction was achieved with the mechanical method, and all the methods showed void areas in the root filling.

O objetivo deste estudo foi avaliar a influência de diferentes técnicas de condensação lateral em relação a qualidade da obturação por meio de estereomicroscopia e microscopia confocal, bem com o tempo gasto para realizar o referido procedimento. Trinta canais radiculares de dentes humanos unirradiculares foram modelados com o sistema ProTaper, finalizando com o instrumento F5. Em seguida os canais foram obturados com guta percha e cimento AH Plus por meio da técnica de condensação lateral. Os espécimes foram divididos em 3 grupos (n=10) de acordo com o método de condensação lateral utilizado, sendo: Manual, Mecânico, Ultrassônico. Os cimentos foram manipulados com rodamina B na proporção de 0.1% de peso para permitir a análise com microscopia confocal. O tempo gasto para realizar cada procedimento de obturação foi registrado com o uso de um cronômetro. Os espécimes foram armazenados a 37 °C durante 48 h, para em seguida serem seccionados a 2, 4 e 6 mm a partir do ápice radicular. A porcentagem da área de guta percha, cimento e vazios foram avaliados com estereomicroscópio. A penetração de cimento foi avaliada por meio de microscópio confocal. A análise estatística foi realizada utilizando os testes de Kruskall-Wallis e Dunn (P < 0.05). O método mecânico exigiu menos tempo para realizar a condensação lateral em comparação com o método manual (p<0.05). Não foi encontrada diferença (p>0.05) em relação ao perímetro de penetração de cimento nos túbulos dentinários entre todos os grupos avaliados. O método mecânico apresentou maior (p<0.05) porcentagem de guta percha e menos cimento no nível de 4 mm quando comparado com o método manual. O grupo do ultrassom apresentou resultados intermediários. Áreas de vazios encontradas foram similares (p>0.05) entre os grupos. Foi possível concluir que o método mecânico foi mais rápido para a técnica de condensação lateral, mas todos os métodos de obturação estudados apresentaram espaços vazios na massa obturadora.

Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement

The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC) was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO), determined by weight. Mineral trioxide aggregate (MTA) was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ΔE, Δa, Δb and ΔL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (p < 0.05). The cements in which bismuth oxide was added showed radiopacity corresponding to the ISO recommendations ( > 3 mm equivalent of Al). The MTA group was statistically similar to the CSC / 30% BO group (p > 0.05). In regard to color, the increase of bismuth oxide resulted in a decrease in the ΔE value of the calcium silicate cement. The CSC group presented statistically higher ΔE values than the CSC / 50% BO group (p < 0.05). The comparison between 24 hours and 7 days showed higher ΔE for the MTA group, with statistical differences for the CSC / 15% BO and CSC / 50% BO groups (p < 0.05). After 30 days, CSC showed statistically higher ΔE values than CSC / 30% BO and CSC / 50% BO (p < 0.05). In conclusion, the increase in radiopacity provided by bismuth oxide has no relation to the color alteration of calcium silicate-based cements.

Biocompatibility and setting time of CPM-MTA and white Portland cement clinker with or without calcium sulfate

Objective: To evaluate the biocompatibility and the setting time of Portland cement clinker with or without 2% or 5% calcium sulfate and MTA-CPM. Material and Methods: Twenty-four mice (Rattus norvegicus) received subcutaneously polyethylene tubes filled with Portland cement clinker with or without 2% or 5% calcium sulfate and MTA. After 15, 30 and 60 days of implantation, the animals were killed and specimens were prepared for microscopic analysis. For evaluation of the setting time, each material was analyzed using Gilmore needles weighing 113.5 g and 456.5 g, according to the ASTM specification Number C266-08 guideline. Data were analyzed by ANOVA and Tukey's test for setting time and Kruskal-Wallis and Dunn test for biocompatibility at 5% significance level. Results: Histologic observation showed no statistically significant difference of biocompatibility (p>0.05) among the materials in the subcutaneous tissues. For the setting time, clinker without calcium sulfate showed the shortest initial and final setting times (6.18 s/21.48 s), followed by clinker with 2% calcium sulfate (9.22 s/25.33 s), clinker with 5% calcium sulfate (10.06 s/42.46 s) and MTA (15.01 s/42.46 s). Conclusions: All the tested materials showed biocompatibility and the calcium sulfate absence shortened the initial and final setting times of the white Portland cement clinker.

Interfacial adaptation of an epoxy-resin sealer and a self-etch sealer to root canal dentin using the System B or the single cone technique

The aim of this laboratory study was to compare the interfacial adaptation of an epoxy-resin and a self-etch sealer in mesial root canals of mandibular molars filled using the System-B/Elements Obturation Unit. Sixty mesial root canals of mandibular molars were prepared using the K3 rotary system up to 35.04 instrument and then filled with the aid of the System-B/Elements Obturation Unit using either gutta-percha/ThermaSeal Plus (n=15) or Resilon/Real Seal SE (n=15). The single cone technique using both materials was used as control. The sealers were stained with Rhodamine B dye and the teeth were filled and sectioned at 2, 4 and 6 mm from the apex. The interfacial marginal adaptation of sealers was evaluated using confocal microscopy. Statistical analyses were performed by the Kruskall-Wallis test (α=0.05). In general, microscopic analysis showed a quite regular gap distribution pattern at sealer-dentin interfaces, mainly for the two groups filled with Real Seal SE. This means that both nonbonding root-filling groups (ThermaSeal Plus) showed significantly higher amount of gap-free regions regardless of the filling technique (p<0.05). Better marginal adaptation was obtained with gutta-percha and epoxy resin-based sealer using either the system B or the single cone technique.

O objetivo deste estudo laboratorial foi avaliar comparativamente a adaptação na interface obturação/dentina em canais mesiais de molares inferiores obturados com System B, tanto com guta percha/ThermaSeal Plus como com Resilon/Real Seal SE. Os canais mesiais de 60 molares inferiores foram modelados utilizando o sistema rotatório K3, realizando o batente apical com o instrumento 35,04. Em seguida os canais foram obturados com guta percha/ThermaSeal Plus (n=15) e com Resilon/Real Seal SE (n=15) por meio do System B. Obturações com a técnica do cone único utilizando os dois materiais foram empregadas como controle. Os cimentos foram corados com Rodamina B e os dentes obturados foram seccionados a 2, 4 e 6 mm do ápice. A adaptação da interface marginal foi avaliada utilizando a microscopia confocal. A análise estatística foi realizada empregando o teste Kruskall-Wallis (p<0,05). De modo geral, a análise microscópica mostrou um padrão regular na distribuição de fendas na interface cimento-dentina, principalmente para os dois grupos com cimento Real Seal SE. Sendo que os outros dois grupos (com ThermaSeal Plus), apresentaram uma quantidade significativamente menor de áreas com fendas, independentemente da técnica de obturação (p<0,05). A melhor adaptação marginal foi observada quando se utilizou guta percha e o cimento à base de resina epóxica, tanto com o System B como com cone único.

Effects of Gates-Glidden, LA Axxess and orifice shaper burs on the cervical dentin thickness and root canal area of mandibular molars

This study evaluated the increase of the instrumented area and dentin thickness in the mesial and distal aspects of mesial canals of mandibular molars after the use of Gates Glidden (GG), LA Axxess (LA) and Orifice Shaper (OS) instruments. A total of 53 canals from 27 mandibular molars were embedded in resin and divided into 3 groups. The roots were sectioned 3 mm below the cementoenamel junction and the images were captured before and after instrumentation. The increase of the instrumented area in terms of percentages and the remaining dentin thickness, in mm, at the mesial and furcal aspects were calculated using the Image tools software. Data were analyzed using the Kruskal-Wallis and Dunn's test. The significance level was set at 5 percent. All instruments promoted cervical flaring with different amounts of dentin removal at the mesial and distal aspects of the root canals. Statistically significant difference (p<0.05) was found between LA and all other instruments after using the first instrument. Regarding dentin thickness, no significant difference (p>0.05) was found between the mesial and distal walls in all groups. It may be concluded that LA 35.06 and GG 3 burs produced the thinnest dentin walls, and thus their use in mesial canals of mandibular molars should be done with caution.

Este estudo avaliou o aumento da área do canal e a espessura de dentina na parede mesial e distal dos canais mesiais de molares inferiores após o uso de Gates Glidden (GG), La Axxess (LA), Orifice Shaper (OS). Um total de 53 canais mesiais de 27 molares inferiores foram incluídos em resina e divididos em 3 grupos. As raízes foram seccionados 3 mm abaixo da junção cemento-esmalte e as imagens foram capturadas antes e depois da instrumentação. O aumento da área do canal em percentagem e a espessura da dentina remanescente nas paredes mesial e furca foram calculados utilizando o software Image Tools. Os dados foram analisados utilizando o Kruskal-Wallis e teste de Dunn. O Nível de significância foi de 5 por cento. Todos os instrumentos promoveram o aumento da área cervical, com diferentes quantidades de remoção da dentina nas paredes mesial e distal do canal radicular. Diferença estatística (p<0,05) foi encontrada entre LA e todos os outros instrumentos após o uso do primeiro instrumento. Quanto à espessura da dentina, não houve diferença significativa (p>0,05) entre as paredes mesial e distal de todos os instrumentos analisados. O LA 35.06 e GG 3 mostraram a menor espessura da parede e sua utilização em canais mesiais de molares inferiores deve ser feito com cuidado.

The antimicrobial effect of iodine-potassium iodide after cleaning and shaping procedures in mesial root canals of mandibular molars

The aim of this study was to evaluate the antibacterial activity of 2% iodine potassium iodide (IKI) used as a final rinse after the cleaning and shaping procedures in mesial root canals of mandibular molars infected with Enterococcus faecalis. Seventy two mandibular first molars were used. The root canals were infected with Enterococcus faecalis for 30 days. After the infection procedures, the root canals were cleaned and shaped by using the ProTaper rotary system and manual files. The teeth were randomly assigned to four experimental groups (N=18). In group 1, the root canals were irrigated with sterile distilled water (control). In group 2, the root canals were irrigated with 1% Sodium hypochlorite (NaOCl) during instrumentation. In group 3, root canals were irrigated with 1% NaOCl during instrumentation and a five minute final irrigation using 2 % IKI. In group 4, the root canals were irrigated with 1% NaOCl during instrumentation and a 15 minutes final irrigation with 2 % IKI. Bacteria colony-forming units (CFU) from root canals were semi-quantified and the presence of negative cultures among the groups was compared using Fisher’s test (p < 0,05). The order of effectiveness was: 1% NaOCl plus 2% IKI for 15 minutes (95%), 1% NaOCl plus 2% IKI for 5 minutes (44%), 1% NaOCl (17%) and sterile distilled water (0%). Fisher’s exact test showed a significant difference among the groups (p<0.05). It was concluded that under in vitro conditions, IKI was able to eliminate the Enterococcus faecalis from infected dentin significantly in a 15-minute time frame after the cleaning and shaping procedures.

El objetivo del presente trabajo fue determinar el efecto in vitro del yoduro de potasio yodado al 2% posterior a la preparacion quimiomecanica en conductos radiculares infectados con Enterococcus faecalis. Para este estudio, se emplearon 72 primeras molares inferiores permanentes de humanos, los cuales fueron infectados con Enterococcus faecalis ATCC 29212. Los conductos fueron preparados mediante instrumentacion rotatoria y distribuidos de manera aleatoria en cuatro grupos de acuerdo al irrigante empleado: Grupo 1, agua destilada esteril; Grupo 2, NaOCl al 1%; Grupo 3: NaOCl al 1% IKI al 2% durante cinco minutos; y, Grupo 4: NaOCl al 1% mas IKI al 2% durante 15 minutos. Se tomaron muestras pre y postoperatorias de los conductos y se realizo la semicuantificacion microbiologica de las unidades formadoras de colonias de las bacterias. Fue comparada la presencia de cultivos negativos en los grupos mediante el test de Fisher utilizando un nivel de significancia de p < 0.05. El orden de efectividad para la desinfeccion de los conductos radiculares de mayor a menor fue: NaOCl al 1 % mas IKI al 2% durante 15 minutos (95%), NaOCl al 1% mas IKI al 2% durante 5 minutos (44%), NaOCl al 1% (17%) y agua destilada (0%). Se concluye, que bajo las condiciones in vitro de este estudio, el yoduro de potasio yodado empleado despues de la instrumentacion fue capaz de eliminar significativamente a la bacteria Enterococcus faecalis en un tiempo de 15 minutos.

Effect of sputter-coating on cracking of root-end surfaces after ultrasonic retrograde preparation: A SEM study of resected root apices and their respective impressions

The aim of this study was to evaluate in vitro the effect of sputter- coating for SEM analysis on the formation of cracks on root-end surfaces after retrograde cavity preparation with ultrasonic tips. Root-end cavities were prepared with either Satelec S12/90oD diamond-coated or S12/90o non-coated stainless steel retrotips. Impressions were taken before and after retrograde cavity preparation. The resected root apices and their respective impressions were examined using a scanning electron microscope, and the presence, extension and numbers of cracks were recorded after each procedure. The number of cracks observed directly on the ultrasonically prepared root-end surfaces was larger than that observed in their respective impressions taken after root-end cavity preparation, which suggests that cracking was mostly produced by the sputtercoating process required for SEM analysis. Impressions of the root-end cavities prepared with non-coated ultrasonic stainless steel retrotips showed a greater incidence of cracks (3/10 impressions) than those that replicated cavities prepared with diamond-coated retrotips (1/10 impressions). No statistical difference was found between the diamond and stainless steel retrotips.

El objetivo del presente estudio fue evaluar in vitro el efecto del proceso de metalizacion de la dentina, necesaria para la observacion al microscopio electronico de barrido, sobre la formacion de fracturas dentinarias en retropreparaciones apicales realizadas con ultrasonido. Se realizaron retropreparaciones apicales en 20 piezas dentarias utilizando puntas ultrasonicas diamantadas Satelec S12/90° D (N=10) o puntas no diamantadas Satelec S12/90°. Se tomaron impresiones con silicona antes y despues de que fueran realizadas las retropreparaciones. Los apices radicu - lares y sus respectivas impresiones fueron metalizados y examinadas utilizando un microscopio electronico de barrido. La presencia, extension y numero de fracturas en la dentina fue registrada despues de cada procedimiento. El numero de fracturas observados en la dentina en las retropreparaciones fue mayor que el observado en las impresiones tomadas despues de realizado el procedimiento ultrasonico, lo cual indica que gran cantidad de fracturas en la dentina fueron producidas por el proceso de metalizacion requerido para el analisis al microscopio electronico de barrido y no por el procedimiento ultrasonico. El analisis de las impresiones mostro una mayor incidencia de fracturas cuando se utilizaron las puntas ultrasonicas no diamantadas (3/10) que cuando se utilizaron las puntas ultrasonicas diamantadas (1/10). Sin embargo, la diferencia no fue estadisticamente significativa (p>0.05).

Evaluation of single root canals filled using the lateral compaction, tagger's hybrid, microseal and guttaflow techniques

The aim of this study was to determine the percentage of voids, gutta-percha and root canal sealer using 4 different filling techniques. Fifty-two extracted maxillary lateral incisors were prepared using the crown-down pressureless technique. The teeth were randomly divided in 4 groups (n=13): Lateral compaction (LC), Tagger's hybrid (TH), MicroSeal (MS) and GuttaFlow (GF) techniques. Horizontal cross-sections were made at the 2, 10 and 15 mm levels from the apex. Digital images of the root canal areas were acquired using a stereomicroscope and examined using the Image Tool 3.0 software. Statistical analysis was performed using the Kruskal-Wallis test (α=0.05). In general, a significant decrease in the gutta-percha filled area and increase of sealer area were observed at the apical level for all the evaluated techniques (p<0.05). With regard to the presence of voids, no significant difference was found. MS and TH techniques showed a larger gutta-percha filled area than LC and GF techniques at the coronal and middle third level (p<0.05). From the results of the present study, it may be concluded that the gutta-percha filled area of fillings decrease at the apical level, regardless of the filling technique used.

O objetivo do estudo foi determinar a porcentagem de espaços vazios, guta-percha e cimento após a obturação por 4 diferentes técnicas. Cinquenta e dois incisivos laterais superiores humanos extraídos foram instrumentados pela técnica coroa-ápice sem pressão. Os dentes foram randomicamente divididos em 4 grupos (n=13): Condensação lateral (LC), Técnica híbrida de Tagger (TH), MicroSeal (MS) e GuttaFlow (GF). Foram feitas secções horizontais a 2, 10 e 15 mm do ápice. Imagens digitais foram obtidas dos canais por meio de estereomicroscópio e analisadas no programa Image Tool 3.0. A análise estatística foi feita utilizando o teste de Kruskal-Wallis (α=0,05). Em geral foi observado um significante decréscimo na área de guta-percha e um aumento na área de cimento para todas as técnicas analisadas (p<0,05). Com relação à presença de espaços vazios, não houve diferença estatística entre as técnicas (p>0,05). As técnicas MS e TH apresentaram área de guta-percha maior que as técnicas LC e GF nos terços médio e cervical (p<0,05). Após análise dos resultados foi possível concluir que a área de guta-percha nas obturações diminui em sentido apical, independente da técnica utilizada.