Late discolouration of root-treated teeth and subsequent restorative retreatment: three case reports.

Root-filled teeth that receive ceramic veneers may experience subsequent coronal discolouration, which will likely negatively affect the quality of life of patients and their relationship with the clinician. This manuscript describes three cases of this undesirable aesthetic consequence in anterior teeth of young patients and the subsequent restorative reintervention, with satisfactory results. In all three reports, the root canal filling was performed using cements containing bismuth oxide that likely disassociated into reduced metallic crystals when in contact with LED light. The discolouration observed after veneer cementation was most likely caused by the accumulation of these bismuth metallic crystals. These cases highlight the importance of preventing this undesirable complication, which may also result in the potential subsequent further sacrifice of sound coronal dental structure, and the role of recall in aesthetically demanding clinical cases.

Cone Beam Computed Tomography Assessment of the Volume of Dental Tissue Removed During Endodontic Access.

Introduction: The purpose of this study was to determine the volume of dental tissue removed during endodontic access preparation with cone-beam computed tomography (CBCT) comparing two different software. Methods and Materials: CBCT images of 20 teeth were obtained before and after endodontic access performed with spherical and conical diamond burs. The images were taken with i-CAT Precise system with 0.25 mm voxel size. Digital Imaging and Communications in Medicine (DICOM) images were loaded on two different software programs (Materialise® and InVersalius®), and a 3D reconstruction of the CBCT images was performed on both programs. The baseline volume (BV), and the final volume (FV) were obtained, and the lost tissue volume (LV) was calculated using the formula: LV=BV-FV. The t-test was used to compare initial and final volumes and also to compare the two programs, using a significance level of 5%. Results: The volumetric data calculated for the Materialise  and the InVesalius  programs were, respectively: BV-mean of 441.79±85.08 mm3 and 442.01±84.83 mm3; FV-mean of 426.75±83.88 mm3 and 426.94±83.75 mm3; LV-mean of 15.04±4.32 mm3 and 15.07±4.16 mm3. No statistically significant difference was found in the volumes calculated by either program for initial, final, or removed tissue (P>0.05). However, there was a significant difference between the BV and LV calculated on the same program (P<0.05). Conclusion: Our in vitro study showed that CBCT was able to determine the volume of dental tissue removed in the endodontic access preparation of extracted human teeth, regardless of the software program used.

Avaliação por TCFC do Transporte do Canal Radicular após o Uso de Diferentes Sistemas Rotatórios de NiTi / CBCT Assessment of the Root Canal Transportation After the Use of Different NiTi Rotary Systems

Objetivo: o objetivo do estudo foi avaliar a ocorrência de transporte do canal radicular após o preparo com instrumentos de níquel-titânio (NiTi) de rotação contínua, por meio do exame de tomografia computadorizada de feixe cônico (TCFC). Material e método: Canais mesiovestibulares e mesiolinguais de vinte molares inferiores humanos foram distribuídos aleatoriamente em dois grupos experimentais (n=10), de acordo com o sistema rotatório de NiTi: Grupo 1 ­ BioRace; e Grupo 2 - ProTaper Next. Imagens de TCFC foram obtidas antes do preparo do canal radicular (TCFC 1) e após o uso dos instrumentos BR2 (#25/.04) e X2 (#25/.06) (TCFC 2) e BR5 (#40/.04) e X4 (#40/.06) (TCFC 3). Dois examinadores avaliaram todas as imagens determinando a ocorrência ou não de transporte do canal radicular. Foram estabelecidos 3 níveis para a mensuração nas imagens: 1-2 mm aquém do vértice radicular (terço apical); 3-4 mm aquém do vértice radicular (terço médio); 4- 2 mm abaixo da furca (terço cervical). Os dados foram analisados utilizando o teste de Kruskal-Wallis com pós-teste de Dunn para comparações múltiplas. O nível de significância foi de 5%. Resultados: Os canais radiculares preparados com o sistema BioRace não apresentaram transporte (P<0,05). Foi observado transporte apenas no terço apical do canal mesiovestibular após o uso do instrumento ProTaper Next X4 (#40/.06) (P<0,05). Conclusão: O sistema BioRace permitiu a ampliação dos canais mesiovestibular e mesiolingual de molares inferiores até o diâmetro cirúrgico 40 sem resultar em transporte do canal.

Aim: This study evaluated root canal transportation after root canal instrumentation with two nickel-titanium (NiTi) rotary systems, by using cone beam computed tomography (CBCT) imaging. Material and Methods: Mesiobuccal and mesiolingual root canals of twenty human mandibular molars were randomly divided into two experimental groups (n = 10), according to the NiTi rotary system: Group 1 ­ BioRace; and Group 2 ­ ProTaper Next. CBCT scans were obtained before the root canal instrumentation (CBCT 1) and after the use of BR2 (#25/.04) and X2 (#25/.06) instruments (CBCT 2) and after the use of BR5 (#40/.04) and X4 (#40/.06) instruments (CBCT 3). Two examiners evaluated the occurrence or not of transportation. Measurements were made at 3 different points: 1-2 mm from the apex (apical third); 3-4 mm from the apex (middle third); 4- 2 mm below furcation (cervical third). The Kruskal-Wallis and Dunn tests were used for statistical analysis. The level of significance was set at 5%. Results: Root canals instrumented with BioRace instruments showed no transportation (P<0.05). Transportation was observed only in the apical third of the mesiobuccal root canal after the use of ProTaper Next X4 instrument (#40/.06) (P<0.05). Conclusions: The BioRace system allowed the widening of mesiobuccal and mesiolingual root canals of mandibular molars up to apical diameter 40 without resulting in root canal transportation.

Estudo Comparativo do Preparo Transversal Produzido pelo Emprego de Instrumentos de NiTi e Manual em Molares Inferiores / Comparative Study of the Transversal Preparation Carried Out by NiTi and Manual Instruments in Lower Molars

Objetivo: avaliar o desgaste dentinário promovido por instrumentação rotatória com diferentes sistemas de NiTi e instrumentação manual em raízes mesiais de molares inferiores. Material e Métodos: Foram selecionados 60 molares inferiores extraídos que foram divididos em 6 grupos (n=10). Nos grupos A, B, C e D os canais radiculares foram preparados utilizando-se os sistemas de NiTi ProFile®, ProTaper Universal®, K3® e Race®, respectivamente. No grupo E, os canais radiculares foram preparados com limas manuais do tipo K Flexofile®, e no grupo F os canais radiculares não foram preparados (controle). Após os preparos, foram realizados dois cortes perpendiculares ao longo eixo da raiz mesial, sendo um no terço cervical e outro no terço apical. As imagens dos cortes foram capturadas por meio de microscópio e analisadas através de software. Para cada corte, foram realizadas três medidas correspondentes à menor espessura da parede dentinária, sendo obtida uma média de cada espécime. As comparações entre os grupos das medidas obtidas foram realizadas pelo teste t, com nível de significância de 5%. Resultados: Tanto no terço cervical quanto apical houve diferença significante entre o grupo E (Flexofile) e os grupos de sistemas de NiTi, bem como entre o grupo controle. No terço apical foi observada diferença significante entre o grupo A (Profile®) e o grupo D (Race®) em comparação ao grupo controle. Conclusões: Pôde-se concluir que as técnicas que utilizaram instrumentos de NiTi preservaram mais estrutura dentinária quando comparados à técnica que se utilizou de limas manuais.

Objective: to evaluate dentinal wear promoted by rotary instrumentation with different NiTi systems and manual instrumentation in mesial roots of lower molars. Material and Methods: Sixty extracted lower molars were selected and divided into 6 groups (n = 10). In groups A, B, C and D the root canals were prepared using the NiTi ProFile®, ProTaper Universal®, K3® and Race® systems, respectively. In group E, the root canals were prepared with manual files of type K Flexofile®, and in group F the root canals were not prepared (control). After the preparation, two perpendicular cuts were made along the axis of the mesial root, one in the cervical third and the other in the apical third. The images of the cuts were captured by means of a microscope and analyzed through software. For each cut, three measurements were made corresponding to the lowest thickness of the dentin wall, obtaining an average of each specimen. The comparisons between the groups of measures obtained were performed by the t test, with a significance level of 5%. Results: In both the cervical and apical thirds there was a significant difference between the group E (Flexofile) and the groups of NiTi systems, as well as between the control group. In the apical third, a significant difference was observed between group A (Profile®) and group D (Race®) compared to the control group. Conclusions: It could be concluded that the techniques that used NiTi instruments preserved more dentin structure when compared to the technique used of manual files.

Avaliação da composição química e radiopacidade de diferentes pastas de hidróxido de cálcio / Evaluation of chemical composition and radiopacity of different calcium hydroxide pastes

Objetivo: Avaliar a composição química e a radiopacidade de diferentes pastas de hidróxido de cálcio. Material e métodos: Foram avaliadas três pastas comerciais: Ultracal XS®; Hydropast® e Callen®. O hidróxido de cálcio P.A. foi utilizado como controle. Para avaliar a composição química dos materiais, uma amostra de cada pasta foi avaliada por análise termogravimétrica, e a massa de hidróxido de cálcio presente foi obtida por meio de cálculos estequiométricos a partir da decomposição térmica de suas moléculas. Para avaliar a radiopacidade, foram analisadas 03 amostras para cada grupo. A radiopacidade foi avaliada com um sistema de radiografia digital indireta Express™ e equipamento de raios X Focus™. As imagens obtidas foram analisadas quanto aos padrões do valor de cinza por meio do software ImageJ. Resultados: Os percentuais de massa de hidróxido de cálcio obtidos para cada material foram: hidróxido de cálcio P.A.: 87,12%; Ultracal XS®: 36,38%; Hydropast®: 30,66%; Callen®: 50,54%. Os valores de cinza das pastas foram de: 63,41 para o hidróxido de cálcio P.A.; 126,35 para Ultracal XS®; 106,73 para Hydropast®, e 72,23 para Callen®. Na mesma análise, a escala de alumínio apresentou os valores: Al 1mm: 53,50; Al 4 mm: 98,06; Al 8mm: 162,14; Al 12mm: 205,4. Conclusões: Houve diferenças em todas as pastas entre a quantidade de hidróxido de cálcio informada pelo fabricante e a quantidade encontrada nas análises termogravimétricas. As pastas comerciais testadas apresentaram maior radiopacidade que o grupo controle. A Ultracal XS® foi o material com maior radiopacidade, seguido da Hydropast e Callen.

Objective: To evaluate and compare the chemical composition and radiopacity of different calcium hydroxide pastes. Material and methods: Three commercial pastes were evaluated: Ultracal XS®; Hydropast® and Callen®. Calcium hydroxide P.A. was used as control. To evaluate the chemical composition of the materials, a sample of each paste was evaluated by thermogravimetric analysis and the mass of calcium hydroxide presented was obtained through stoichiometric calculations from the thermal decomposition of its molecules. To evaluate the radiopacity were analyzed 03 samples for each group. Radiopacity was evaluated with an Express™ indirect digital radiography system and Focus™ X-ray equipment. The images were analyzed as gray value standards using ImageJ software. Results: The percentages of mass of calcium hydroxide obtained for each material were: calcium hydroxide P.A.: 87.12%; Ultracal XS®: 36.38%; Hydropast ®: 30.66%; Callen®: 50.54%. The gray values of the pastes were: 63.41 for the calcium hydroxide P.A.; 126.35 for Ultracal®; 106.73 for Hydropast®, and 72.23 for Callen®. In the same analysis, the aluminum scale presented in values: Al 1mm: 53,50; Al 4 mm: 98.06; Al 8mm: 162.14; Al 12mm: 205.4. Conclusions: There were differences in all pastes between the amount of calcium hydroxide reported by the manufacturer and the amount found in the thermogravimetric analyzes. The commercial pastes tested showed higher radiopacity than the control group. Ultracal XS® was the material with the highest radiopacity, followed by Hydropast ® and Callen®.

Análise da precisão do exame de tomografia computadorizada de feixe cônico na determinação do comprimento de trabalho durante a terapia endodôntica / Analysis of the accuracy of cone beam computed tomography exam in determining the work length during root canal treatment

Objetivo: Avaliar a precisão do exame de Tomografia Computadorizada de Feixe Cônico (TCFC) na determinação do comprimento de trabalho (CT) em 24 dentes humanos unirradiculares. Material e Método: Após a realização dos procedimentos de abertura coronária, exploração do canal radicular e preparo dos terços cervical e médio os dentes tiveram seus comprimentos de trabalho determinados pelos métodos direto, eletrônico e tomográfico. No método direto, o CT foi determinado visualmente com o auxílio de uma lima do tipo K-File #20, enquanto que nos métodos eletrônico e tomográfico, as odontometrias foram estabelecidas, respectivamente, com a utilização de um localizador eletrônico foraminal da marca Root ZX II e em imagens de TCFC obtidas em um tomógrafo Prexion 3D. Os dados foram analisados por meio do teste ANOVA ao nível de 5% de significância Resultados: Ao todo foram realizadas 72 mensurações. Não foram observadas diferenças estatisticamente significantes entre as medidas obtidas pelos diferentes métodos empregados. Conclusões: O exame de TCFC revelou ser uma alternativa eficaz para a obtenção do CT durante a terapia endodôntica.

Aim: To evaluate the accuracy of Cone Beam Computed Tomography (CBCT) in work length (WL) determination in twentyfour single-rooted human Material and Methods: After performing the procedures of coronary opening, root canal exploration and cervical preflaring, the teeth had their work lengths determined by direct, electronic and tomographic methods. In the direct method, the WL was determined visually, using a #20 KFile instrument. In the electronic and tomographic methods, the WLs were determined using the Root ZX II locating device and TCFC images, respectively. The data were analyzed statistically by the ANOVA test at 5% significance level. Results: A total of 72 measurements were performed. No statistical difference was observed between the measurements obtained by the different methods. Conclusions: The CBCT proved to be an effective alternative for WL determination during root canal treatment.