Analysis of the mandibular molars root canals morphology. Study by computed tomography.

This study aimed to analyze the root and root canal morphology of mandibular first and second molars using CBCT images. A total of 2,400 mandibular molars exams were selected from 600 patients aged between 18 and 75 years. The number of roots, number of root canals, and root canal configuration according to the Vertucci classification were verified. Overall, 94.92% of mandibular first molars and 90.17% of mandibular second molars had two separate roots. Among the biradicular molars, the first molars showed a greater incidence of type IV canals in the mesial root and type I in the distal root. In the second molars, the most common canal form was type IV in the mesial root and type I in the distal root. In the triradicular molars, the type IV and type I configurations were the most common in the mesial root of the first molar and second molar, respectively. In both triradicular molars, there was a prevalence of type I canal in the distal and DL roots. Statistical analysis was performed at a significance level of 0.05. The number of roots was correlated with gender (Spearman test), and the canal's configuration with gender and bilaterality (Wilcoxon test). The subpopulation studied has a high incidence of bilateral symmetry and mandibular molars with two roots with two distinct mesial canals and one distal canal. The bilateral configuration is possible to estimate the number of canals, especially in images that are difficult to visualize, such as atresic canals.

Analysis of the mandibular molars root canals morphology. Study by computed tomography

Abstract This study aimed to analyze the root and root canal morphology of mandibular first and second molars using CBCT images. A total of 2,400 mandibular molars exams were selected from 600 patients aged between 18 and 75 years. The number of roots, number of root canals, and root canal configuration according to the Vertucci classification were verified. Overall, 94.92% of mandibular first molars and 90.17% of mandibular second molars had two separate roots. Among the biradicular molars, the first molars showed a greater incidence of type IV canals in the mesial root and type I in the distal root. In the second molars, the most common canal form was type IV in the mesial root and type I in the distal root. In the triradicular molars, the type IV and type I configurations were the most common in the mesial root of the first molar and second molar, respectively. In both triradicular molars, there was a prevalence of type I canal in the distal and DL roots. Statistical analysis was performed at a significance level of 0.05. The number of roots was correlated with gender (Spearman test), and the canal's configuration with gender and bilaterality (Wilcoxon test). The subpopulation studied has a high incidence of bilateral symmetry and mandibular molars with two roots with two distinct mesial canals and one distal canal. The bilateral configuration is possible to estimate the number of canals, especially in images that are difficult to visualize, such as atresic canals.

Detection of the internal anatomy of lower anterior teeth using cone-beam computed tomography.

Morphology study of root canal systems is essential for a correct diagnosis, therapy and prognosis of root canal treatment. This study aimed to analyse the dental anatomy of the lower anterior teeth, using cone-beam computed tomography (CBCT). Lower anterior teeth were classified in terms of type, number and location of root canals, evaluating the bilaterality of anatomical occurrences and determining whether the gender and age influence the findings. We analysed 749 CBCT of patients attending the School of Dentistry for different reasons. Spearman's correlations and Wilcoxon signed-rank test were used to analyse data (α = 0.05). There was no significant correlation between gender (male and female) and anatomy of the canals 33 (P = 0.162), 32 (P = 0.815), 31 (P = 0.708), 41 (P = 0.422), 42 (P = 0.382) and 43 (P = 0.063). There was a significant correlation between age and anatomy of the canals 33 (P = 0.045), 32 (P = 0.033), 31 (P = 0.022), 41 (P = 0.000), 42 (P = 0.037) and 43 (P = 0.037). There was no significant correlation between gender and patients' age (P = 0.325). There was no anatomical difference between the bilateral pairs (right and left homologous teeth) (P > 0.05). The most common anatomical configuration was single-canal teeth (85.29%), followed by the configuration in which one canal leaves the chamber, divides into two and unite again (12.88%). Anatomy of the lateral incisors and lower canines does not change with the gender of patients. However, as age rises, single canals and the incidence of division into two canals ending in a single foramen also increases.

Morphology and microhardness of dentin at the furcation area of mandibular molars.

INTRODUCTION: This study evaluated dentin morphology and microhardness at the furcation area of mandibular molars. METHODS: Tooth segments of mandibular molars were embedded in resin blocks and bisected longitudinally (n = 20), and the furcation area was delimited by tracing 2 orthogonal lines from the most concave point of the outer surface of the furcation toward the mesial and distal canal entrances. In half of the specimens, Knoop microhardness was measured in 2 directions in the furcation area: vertically, parallel to the orthogonal lines and the bisector of the angle formed by them; and horizontally, in the outer (close to the pulp chamber floor), inner (close to the cementum), and middle dentin layers. Data were analyzed statistically by one-way analysis of variance and Tukey-Kramer test (α = 0.05). The other half of the specimens were examined by scanning electron microscopy to evaluate dentin morphology and trajectory of the tubules. RESULTS: No statistically significant difference (P > .05) was found among the mesial (46.5 ± 6.4), central (47.3 ± 8.1), and distal (49.7 ± 6.5) orthogonal lines. The inner dentin layer (51.7 ± 2.5) was statistically similar to the middle (46.3 ± 2.9) (P > .05), which was similar to the outer layer (41.4 ± 2.4) (P > .05). The inner layer was significantly harder than the outer layer (P < .05). The morphologic analysis revealed a tendency of calcification of the tubules from the outer toward the inner layer. CONCLUSIONS: Dentin microhardness at the furcation area is uniform in its 3 vertical axes, but the inner dentin layer is harder than the outer layer. The dentinal tubules follow a centripetal direction toward the inner layer, in which dentin is much more mineralized.

Effect of chelating solutions on the microhardness of root canal lumen dentin.

INTRODUCTION: The greatest reduction in microhardness of the most superficial layer of dentin of the root canal lumen is desired. The use of chelating agents during biomechanical preparation of root canals removes smear layer, increasing the access of the irrigant into the dentin tubules to allow adequate disinfection, and also reduces dentin microhardness, facilitating the action of endodontic instruments. This study evaluated the effect of different chelating solutions on the microhardness of the most superficial dentin layer from the root canal lumen. METHODS: Thirty-five recently extracted single-rooted maxillary central incisors were instrumented, and the roots were longitudinally sectioned in a mesiodistal direction to expose the entire canal extension. The specimens were distributed in seven groups according to the final irrigation: 15% EDTA, 10% citric acid, 5% malic acid, 5% acetic acid, apple vinegar, 10% sodium citrate, and control (no irrigation). A standardized volume of 50 µL of each chelating solution was used for 5 minutes. Dentin microhardness was measured with a Knoop indenter under a 10-g load and a 15-second dwell time. Data were analyzed statistically by one-way analysis of variance and Tukey-Kramer multiple-comparison test at 5% significance level. RESULTS: EDTA and citric acid had the greatest overall effect, causing a sharp decrease in dentin microhardness without a significant difference (p > .05) from each other. However, both chelators differed significantly from the other solutions (p < .001). Sodium citrate and deionized water were similar to each other (p > .05) and did not affect dentin microhardness. Apple vinegar, acetic acid, and malic acid were similar to each other (p > .05) and presented intermediate results. CONCLUSION: Except for sodium citrate, all tested chelating solutions reduced microhardness of the most superficial root canal dentin layer. EDTA and citric acid were the most efficient.

Avaliação da microinfltração coronária de três materiais utilizados na restauração provisória da cavidade endodôntica: estudo in vitro. / Coronal leakage of three materials used for temporary restoration of endodontic access cavities: an in vitro study

O objetivo deste trabalho foi avaliar a capacidade seladora de um material restaurador provisório, Villevie, e de uma resina composta, Tetric Ceram, associada a dois tipos de sistema adesivos, XENO III e Single Bond. Quarenta incisivos inferiores unirradiculares foram distribuídos em três grupos de dez dentes cada e cinco dentes para cada grupo controle, positivo e negativo. Os espécimes, após a cirurgia de acesso, foram preparados por meio de sistema de instrumentação rotatória e irrigados com água destilada e deionizada. A porção externa dos dentes foi impermeabilizada até 2 mm aquém da margem externa da cirurgia de acesso. Colocou-se no interior do canal radicular um cone de papel seguido de uma pensa de algodão impregnados com solução alcoólica de dimetilglioxima 1%. A cavidade endodôntica foi selada de acordo com os seguintes grupos: GA- sistema adesivo autocondicionante XENO III + resina composta; GB- sistema adesivo Single Bond + resina composta; e GC- selador provisório. Os espécimes foram imersos em recipientes contendo solução de sulfato de níquel 5% e submetidos à ciclagem térmica por 72h. Os testes de Kruskal-Wallis e Dunn foram utilizados para análise dos resultados com nível de 5% de signifcância. O menor nível de microinfltração foi observado no grupo do restaurador provisório (GC), com diferença estatística signifcante em relação aos demais grupos (P<0,001). Os grupos A e B mostraram-se semelhantes ao controle positivo (P>0,05), com os maiores índices de microinfltração. Concluiu-se que nenhum dos materiais avaliados foi capaz de impedir a microinfltração coronária.

The purpose of this study was to evaluate the sealing capacity of a temporary restorative material (Villevie) and a composite resin, Tetric Ceram, associated with two adhesive systems (XENO III and Single Bond). Forty single-rooted mandibular incisors were distributed into three experimental groups of 10 teeth each, and two control groups (positive and negative) of 5 teeth each. After preparation of the access cavities, the canals were instrumented with a rotary system and irrigated with distilled deionized water. The external surfaces of the teeth were rendered water-proof up to 2 mm from the external margins of the access cavities. A paper point and a coton mesh impregnated with an alcoholic 1% dimethylglyoxime were placed inside the root canals, and the endodontic access cavities were sealed according to the following groups: GA- XENO III self-etch adhesive system + composite resin; GB- Single Bond etch-and-rinse adhesive system + composite resin; and GC- temporary restorative material. The specimens were immersed in receptacles containing a 5% nickel sulfate solution and subjected to a thermal cycling regimen during 72 h. The Kruskal-Wallis and Dunn's tests were used for statistical analysis of the results at 5% signifcance level. The group restored with the temporary restorative material (GC) presented statistically signifcant less coronal leakage than the other groups (p<0.001). GA and GB were statistically similar to the positive control (p>0.05), showing the highest levels of coronal leakage. None of the tested materials was able to prevent the occurrence of coronal leakage.

Avaliação do efeito do EDTA, CDTA e EGTA sobre a microdureza da dentina radicular humana: estudo in vitro. / valuation of the effect of EDTA, CDTA and EGTA on the microhardness of human root dentine: in vitro study.

Objetivo: Estudou-se a ação das soluções de EDTA 17%, CDTA 17% e EGTA 17% sobre a microdureza da dentina radicular. Material e métodos: Foram utilizados cinco dentes incisivos centrais superiores humanos, recém-extraídos, os quais tiveram suas coroas seccionadas na junção cemento-esmalte e posteriormente desprezadas. As raízes foram incluídas em acrílico de rápida polimerização, adaptadas à máquina de corte e seccionadas transversalmente de um em um milímetro. O primeiro corte foi desprezado e o segundo dividido em quatro quadrantes. Cada quarto de dentina foi colocado sobre um disco de resina acrílica, obtendo-se quatro corpos-de-prova para cada raiz. Cinqüenta microlitros da solução a ser testada foram depositados sobre o corpo-de-prova por meio de uma pipeta micrométrica, permanecendo por cinco minutos. A medição da microdureza da dentina foi obtida em um aparelho de dureza Vickers com peso de cinqüenta gramas de carga e tempo de quinze segundos de aplicação. Resultados: Após análise estatística, os resultados mostraram que todas as soluções testadas foram efetivas quanto à redução da microdureza dentinária, mas estatisticamente diferentes entre si (p<0.05). A solução de EGTA 17% promoveu maior redução, seguida pela solução de CDTA 17%. A solução de EDTA 17% foi a menos efetiva. Conclusão: Pode-se concluir que as soluções quelantes testadas no experimento foram efetivas quanto à redução da microdureza dentinária.

Objective: In this work the action of 17 % EDTA solution, CDTA 17 % solution and EGTA 17% solution had been studied on human radicular dentin microhardness. Material and methods: Five freshly extracted human maxillary incisors were transversely sectioned at the cement-enamel junction; the crowns were discarded. The roots were embedded in blocks of resin polymerization rapidly, which were adaptated in the cut machine and seccionated transversely in 1 to 1 milimeter. The first cut was discarded and the second divided into four quadrants. Each quarter of dentin was placed on a disc of acrilic resin, resulting in four samples for each root. Fifty microliters of the tested solutions were deposited on the specimen using a micrometer pipete, staying for five minutes. The measurement of dentin microhardness was in a unit of Vickers hardness with 50 grams of weight and load time of 15 s of application. Results: After statistical analysis, results showed that all solutions were efective in reducting dentin microhardness, but statistically diferent from each other (p<0.05). The 17 % EGTA solution was more efective, followed by 17 % CDTA solution. 17 % EDTA solution was the less efective. Conclusion: It was possible to conclude that all the chelants solutions were efective in reduction of the radicular dentin microhardness.

Evaluation of the effect of EDTA, EGTA and CDTA on dentin adhesiveness and microleakage with different root canal sealers.

The effect of chelating solutions EDTA, EGTA and CDTA on human dentin adhesiveness and microleakage with 4 sealers (Sealer 26, Sealapex, N-Rickert and Endofill) was evaluated in vitro. Whether or not there was a mathematical correlation between the tests of adhesiveness and microleakage was also evaluated. A total of eighty maxillary and mandibular molars were used to test adhesiveness. After wearing of the occlusal surface to obtain a flat surface, the sealer was placed with an aluminum cylinder (10 mm x 6 mm). Adhesiveness was evaluated with a 4444 Instron universal testing machine. Microleakage was evaluated in 160 maxillary canines after root canal instrumentation, obturation and clearing. The penetration of India ink in the apical region was measured with a measurescope. The teeth were divided into 4 groups: group 1, distilled water, group 2, EDTA; group 3, EGTA; group 4, CDTA. Sealer 26 and EDTA had the best results (p<0.01) for adhesiveness and microleakage. There was no correlation between the test for adhesiveness and microleakage.

Evaluation of the effect of EDTA, EGTA and CDTA on dentin adhesiveness and microleakage with different root canal sealers

The effect of chelating solutions EDTA, EGTA and CDTA on human dentin adhesiveness and microleakage with 4 sealers (Sealer 26, Sealapex, N-Rickert and Endofill) was evaluated in vitro. Whether or not there was a mathematical correlation between the tests of adhesiveness and microleakage was also evaluated. A total of eighty maxillary and mandibular molars were used to test adhesiveness. After wearing of the occlusal surface to obtain a flat surface, the sealer was placed with an aluminum cylinder (10 mm x 6 mm). Adhesiveness was evaluated with a 4444 Instron universal testing machine. Microleakage was evaluated in 160 maxillary canines after root canal instrumentation, obturation and clearing. The penetration of India ink in the apical region was measured with a measurescope. The teeth were divided into 4 groups: group 1, distilled water, group 2, EDTA; group 3, EGTA; group 4, CDTA. Sealer 26 and EDTA had the best results (p<0.01) for adhesiveness and microleakage. There was no correlation between the test for adhesiveness and microleakage.