The impact of long-term storage conditions on the development of experimental dentinal microcracks.

This study evaluated the impact of long-term storage conditions (medium and time) on the development of experimental dentinal microcracks through micro-computed tomography. Sixty freshly extracted premolars were stored in formalin, water, or dry conditions (n = 20) and scanned after 72 h, 30 days, 6 months and 3 years of extraction. The effect of the storage medium and time on the occurrence of dentinal defects was statistically evaluated. A total of 211 000 images were screened revealing the existence of 11 519 slices with dentinal defects. Dry conditions significantly contributed to the development of new defects in all time points. During the 3-year follow-up period, no new defects were detected in the teeth that were stored in water and, in a single tooth, in the formalin group, after 6 months of storage.

Os primeiros passos para a implementação de um banco de dentes humanos na Faculdade de Odontologia UFF / The first steps to implement a human teeth bank at Faculty of Dentistry - UFF

O Banco de Dentes Humanos (BDH) é uma instituição sem fins lucrativos, vinculada a uma faculdade, universidade ou instituição com o propósito de suprir as necessidades acadêmicas, através do fornecimento de dentes humanos para estudo e treinamento laboratorial dos alunos dos cursos de graduação e pós-graduação. Assim, o presente trabalho teve como objetivo relatar os métodos utilizados para captação, tratamento, seleção, preservação, armazenamento e reutilização de dentes humanos extraídos, realizados por alunos da Faculdade de Odontologia (FO) da Universidade Federal Fluminense (UFF) através de dois projetos deferidos junto a PROAES-UFF. Para isso, foram realizadas campanhas de conscientização e programas de divulgação para a doação de dentes humanos extraídos permanentes e decíduos tanto para a comunidade científica odontológica como para a comunidade leiga. Após 24 meses, foram captados um total de 2.536 dentes, sendo 346 molares superiores, 279 molares inferiores, 262 pré-molares superiores, 418 pré-molares inferiores, 343 caninos, 296 incisivos superiores e 592 incisivos inferiores. As campanhas e ações dos projetos da PROAES-UFF foram eficientes para coletar dentes humanos, suprindo as atividades laboratoriais de diversas disciplinas na graduação e também servindo de estoque para a futura implementação do BDH da FO-UFF.

The Human Teeth Bank (HTB) is a non-profit institution, linked to a college, university or institution with the purpose of meeting academic needs, through the provision of human teeth for study and laboratory training of undergraduate and postgraduate students. Thus, this study aimed to report the methods of capture, treatment, selection, preservation, storage and reuse of extracted human teeth, carried out by students from the Faculty of Dentistry (FO) of Universidade Federal Fluminense (UFF) through two projects approved by PROAES-UFF. To this end, awareness campaigns and outreach programs were carried out for the donation of human teeth extracted, permanent and deciduous, both for the dental scientific community and for the lay community. After 24 months, a total of 2,536 teeth were captured, with 346 upper molars, 279 lower molars, 262 upper premolars, 418 lower premolars, 343 canines, 296 upper incisors and 592 lower incisors. The campaigns and actions of PROAES-UFF projects were efficient in collecting human teeth, supplying the laboratory activities of several disciplines during graduation and also serving as a stock for a future implementation of the HTB of FO-UFF.

Does sodium thiosulphate avoid the formation of the brown-coloured precipitate as an intermediate irrigant between NaOCl and chlorhexidine?

This study evaluated the efficacy of sodium thiosulphate (ST) as an intermediate irrigant between sodium hypochlorite (NaOCl) and chlorhexidine (CHX) to avoid the formation of the brown-coloured precipitate. The in vitro experiment used microtubes to test the mixture of 2.5% NaOCl, 2% CHX and 5% ST solutions, varying their order and time of addition. In the ex vivo experiment, 10 bovine teeth were divided into two groups according to the intermediate irrigant used: distilled water (control) and 5% ST (experimental). Colour change occurred in all microtubes after interaction between solutions. While the precipitate was not observed in the experimental group, it was seen in all specimens of the control group. The 5% ST was able to prevent the formation of the brown-coloured precipitate in the ex vivo experiment, whereas it only prevented its in vitro formation when the waiting time for adding CHX was 10, 15 and 20 min.

Is canal overinstrumentation able to produce apical root dentinal microcracks in extracted teeth?

AIM: To assess the impact of mechanical overinstrumentation of root canals in extracted teeth on the development of dentinal microcracks in the apical portion of the root by means of micro-computed tomographic (micro-CT) analysis. Root canal preparation short of the canal terminus and at the apical foramen (AF) were used as controls. METHODOLOGY: Twenty 2-rooted maxillary premolars with two canals were selected, scanned in a micro-CT device and the root canals prepared sequentially using Reciproc M-Wire R25 instruments to working lengths: 1 mm short of the AF (AF - 1 mm), at the AF (AF), and overinstrumentation (AF + 1 mm). A micro-CT scan of each specimen was performed after each time point. After reconstruction and co-registration procedures, the images were screened from the cementoenamel junction to the apex (n = 55 352) to identify the presence of dentinal microcracks in the apical third of the root. RESULTS: After the analyses of 55 352 slices, dentinal microcracks were visualized in 12.45% of the images (6892 slices), with 5.73% (3174 slices) in the cervical, 3.57% (1976 slices) in the middle and 3.15% (1740 slices) in the apical third. All dentinal microcracks observed at all time points (AF - 1 mm, AF and AF + 1 mm) were already present in the corresponding images before canal instrumentation. Therefore, no new microcracks were detected, regardless of the working length used for canal instrumentation. CONCLUSION: Reciprocating root canal preparation either short, at or beyond the AF (overinstrumentation) did not create dentinal microcracks in the roots of extracted 2-rooted maxillary premolars.

Análise comparativa dos cimentos MTA cinza e branco associados ao álcool isopropílico / Comparative analysis of gray and white MTA associated with isopropyl alcohol

O objetivo deste estudo ex vivo foi investigar e comparar os efeitos antibacterianos, a citotoxicidade, a adaptação marginal e a capacidade seladora do agregado trióxido mineral (MTA), branco e cinza (Angelus, Londrina, Brasil), quando combinados com água destilada ou álcool isopropílico. Os efeitos antibacterianos de ambas as formulações foram avaliados através do teste de difusão em agar utilizando Staphylococcus aureus (ATCC25923) e Pseudomonas aeruginosa (ATCC27853) para a seleção da concentração de escolha. A geração das espécies reativas do oxigênio (ERO) foi analisada, primeiramente, utilizando cepas de Escherichia coli proficiente (AB1157) e triplo mutante (BW535), deficiente nos mecanismos de reparo. A geração de ERO também foi analisada através da degradação plasmidial (método de eletroforese) e com a utilização da sonda DCF. A geração das espécies reativas do nitrogênio (ERN) foi avaliada através da sonda DAF. A citotoxicidade dos eluatos dos cimentos foi avaliada pelo MTT, com células L929. A adaptação marginal foi feita através da microscopia eletrônica de varredura (MEV). A capacidade seladora foi realizada através de ensaios de infiltração bacteriana. Os resultados mostraram que a incorporação do isopropanol ao MTA aumentou os halos de inibição no modelo Gram-positivo (S. aureus-ATCC25923) (P <0.05). A adição de isopropanol 70% aos cimentos de MTA branco e cinza aumentou a atividade antimicrobiana para E. coli selvagem (AB1157) e triplo mutante (BW535) (P <0.0001). Não ocorreu a total degradação do DNA plasmidial para as amostras de MTA branco e cinza manipuladas com isopropanol 70%. As amostras de MTA branco e cinza manipuladas de acordo com o fabricante geraram significativamente mais espécies reativas do oxigênio (sonda DCF) (P <0.0001 e P =0.0002) e do nitrogênio (sonda DAF) (P =0.0002 e P =0.0003) do que as manipuladas com isopropanol 70%. Os cimentos manipulados com água destilada foram mais citotóxicos do que a associação com solução de isopropanol 70% (P <0.05). A análise ao MEV mostrou melhor adaptação ao preparo nas amostras com o isopropanol 70%, entretanto o ensaio de infiltração bacteriana ex vivo com Enterococcus faecalis (ATCC29212), não mostrou diferença estatística para as amostras manipuladas com isopropanol ou com água (P >0.05). Podemos concluir que a manipulação com isopropanol melhorou a atividade antimicrobiana do MTA tornando-o menos citotóxico, sem alterar a capacidade seladora.

The aim of this study was to investigate and compare the antibacterial effects, cytotoxicity, marginal adaptation and sealing ability of mineral trioxide aggregate (MTA), white and gray (Angelus, Londrina, Brasil), when combined with distilled water or isopropyl alcohol. The antibacterial effects of both formulations were evaluated by agar diffusion method using Staphylococcus aureus (ATCC25923) and Pseudomonas aeruginosa (ATCC27853) for selecting the suitable concentration of isopropyl alcohol. The antimicrobial mechanism by the generation of reactive oxygen species (ROS) was first analyzed using Escherichia coli strains: proficient (AB1157) and triple mutant (BW535), deficient in the repair mechanisms. The ROS generation was also analyzed by degradation of DNA plasmid (electrophoresis method) and with the DCF probe. The generation of reactive nitrogen species (RNS) was assessed by DAF probe. The cytotoxicity of the eluates was assessed by MTT test, with L929 cells. The marginal adaptation was evaluated by scanning electron microscopy (SEM). The sealing ability was performed using bacterial leakage assay. The results showed that the incorporation of isopropanol to MTA increased the inhibitory haloes in Gram-positive model (S. aureus-ATCC25923) (P <0.05). Adding 70% isopropanol to white and gray MTA cements increased antimicrobial activity against both E. coli wild (AB1157) and triple-mutant (BW535) strains (P <0.0001). The DNA plasmid was not completely degraded for the samples of white and gray MTA manipulated with 70% isopropanol. The white and gray MTA samples, handled according to the manufacturer, generated significantly more ROS (DCF probe) (P <0.0001 e P =0.0002) and RNS (DAF probe) (P =0.0002 e P =0.0003) than that manipulated with 70% isopropanol. The cements handled with distilled water were more cytotoxic than when associated with isopropanol solution 70% (P <0.05). The SEM analysis showed better adaptation to the cavity prepares when the samples were filled with MTA with 70% isopropanol, however the ex vivo bacterial infiltration test with Enterococcus faecalis (ATCC29212), was not statistically different from samples manipulated with isopropanol or water (P >0.05). We can conclude that the manipulation with isopropanol improved the antimicrobial activity of the MTA rendering less citotoxicity, without altering the sealing ability.

Banco de dentes humanos na percepção dos acadêmicos da faculdade de odontologia da Universidade Federal Fluminense / Dentistry students' knowledge about the human tooth bank of Universidade Federal Fluminense

O objetivo desta pesquisa foi avaliar o nível de informação dos alunos dos 4º, 5º e 6º períodos da Faculdade de Odontologia da Universidade Federal Fluminense (FO-UFF) acerca da importância do Banco de Dentes Humanos (BDH) e sua funcionalidade. Foram entrevistados 95 alunos, utilizando questionário com perguntas fechadas. Os resultados indicaram que 100% dos alunos tem consciência da existência do BDH na FO-UFF e que 71,3% tem conhecimento de sua finalidade. Esse conhecimento é diferenciado em função do período que o aluno esteja cursando (x2), sendo a proporção de alunos do 4º período significativamente menor (p<0,05). Os autores concluíra, que há necessidade de um maior trabalho de divulgação na população de alunos estudada sobre a importância do BDH.

This research’s goal was to evaluate the level of information known by the 4th, 5th and 6th terms’ students from the Dental School at Universidade Federal Fluminense (FO-UFF) about the importance of the Human Teeth Bank (BDH) and its functionality. There were 95 students in the research, and it was used an objective assessment. The results indicated that 100% of the students know about UFF´s Dental School teeth bank, and that 71,3% knowm it’s purpose. This knowledge depends on the term the student’s on (x2), and the proportion of students who are on their 4th term is highly smaller (p<0,05). The authors concluded that there’s a need to inform more the 4th, 5th and 6th terms’ students about the importance of BDH.

MTA no reparo das perfurações endodônticas: relato de dois casos / MTA for repair of endodontic perforations: two case reports

O MTA possui propriedades físicas, químicas e biológicas que lhe conferem biocompatibilidade, capacidade indutora da osteogênese, da cementogênese, e efeito antimicrobiano. As evidências científicas acerca do uso deste aglomerado sustentam o seu emprego no reparo das perfurações endodônticas. Com o objetivo de avaliar a efetividade do MTA, o presente estudo se propôs a relatar dois casos clínicos. No primeiro procedeu-se o tratamento cirúrgico do elemento dentário 21 que apresentava radiograficamente uma rarefação óssea lateral tendo como etiologia uma perfuração radicular e no segundo um tratamento não cirúrgico de uma perfuração de furca no elemento dentário 46. em ambos os casos o MTA foi utilizado como material reparador. Nas condições de uso aqui relatadas o Agregado Trióxido Mineral demonstrou ser eficiente na eliminação dos sinais e sintomas clínicos bem como no reparo das lesões constatado radiograficamente.

MTA presents appreciable physical, chemical and biological properties. It’s biocompatible material, which induces the deposition of hard tissue and also presents some antibacterial effects. Clinical and scientific reports regarding this aggregate support the use of this material for sealing and repairing endodontic perforations. The aim of the present study was to evaluate the effectiveness of MTA in two case reports. The first case was a surgical treatment of a lateral root perforation and the over was a nonsurgical therapy in a furcal perforation. In both cases MTA was used to repair the perforations . The mineral trioxide aggregate showed to be efficient, allowed bone healing and elimated clinical symptoms.

Comparative SEM evaluation of three solvents used in endodontic retreatment: an ex vivo study.

This study compared, by scanning electron microscopy (SEM), the efficacy of three solvents on the removal of filling materials from dentinal tubules during endodontic retreatment. Forty human maxillary canines with straight canals were prepared according to a crown-down technique and enlarged to a#30 apical file size, before obturation with gutta-percha and a zinc-oxide-eugenol based sealer. The samples were stored for 3 months before being randomly assigned to four groups: chloroform (n=10), orange oil (n=10), eucalyptol (n=10) and control (n=10). Solvents were applied to a reservoir created on the coronal root third using Gates Glidden drills. The total time for retreatment using the solvents was 5 minutes per tooth. Following retreatment the roots were split longitudinally for SEM evaluation. SEM images were digitized, analyzed using Image ProPlus 4.5 software, and the number of dentinal tubules free of filling material from the middle and apical thirds was recorded. No significant difference was found among the solvent groups regarding the number of dentinal tubules free of root filling remnants in the middle and apical root thirds (p>0.05). However, the control group had fewer dentinal tubules free of filling material (p<0.05). Under the tested conditions, it may be concluded that there was no significant difference among the solvents used to obtain dentinal tubules free of filling material remnants.

Comparative sem evaluation by of three solvents used in endodontic retreatment: an ex vivo study

This study compared, by scanning electron microscopy (SEM), the efficacy of three solvents on the removal of filling materials from dentinal tubules during endodontic retreatment. Forty human maxillary canines with straight canals were prepared according to a crown-down technique and enlarged to a#30 apical file size, before obturation with gutta-percha and a zinc-oxide-eugenol based sealer. The samples were stored for 3 months before being randomly assigned to four groups: chloroform (n=10), orange oil (n=10), eucalyptol (n=10) and control (n=10). Solvents were applied to a reservoir created on the coronal root third using Gates Glidden drills. The total time for retreatment using the solvents was 5 minutes per tooth. Following retreatment the roots were split longitudinally for SEM evaluation. SEM images were digitized, analyzed using Image ProPlus 4.5 software, and the number of dentinal tubules free of filling material from the middle and apical thirds was recorded. No significant difference was found among the solvent groups regarding the number of dentinal tubules free of root filling remnants in the middle and apical root thirds (p>0.05). However, the control group had fewer dentinal tubules free of filling material (p<0.05). Under the tested conditions, it may be concluded that there was no significant difference among the solvents used to obtain dentinal tubules free of filling material remnants.

Avaliação de alguns cimentos endodônticos quanto à obstrução dos túbulos dentinários / Evaluation of some endodontic sealers regarding the obstruction in dentin tubules

Um dos objetivos do tratamento endodôntico é a completa vedação do sistema de canais radiculares. Com essa finalidade, o material mais utilizado é o cone de guta-percha associado a um cimento endodôntico, que tem seu papel relevante na prevenção da percolação ou reinfecção dos canais radiculares. O objetivo desta pesquisa foi avaliar a capacidade de obstrução dos túbulos dentinários pelos seguintes cimentos: Tubliseal, AH Plus, Sealapex e Sealer Plus. Utilizaram-se 20 dentes humanos que, após o preparo químico-cirúrgico, foram divididos aleatoriamente em quatro grupos para serem obturados pela técnica da condensação lateral com os diferentes cimentos endodônticos. Em seguida, as amostras foram clivadas e analisadas no microscópio eletrônico de varredura. Após o processamento das imagens, procederam-se à leitura e avaliação no Prisme-Graph Pad. De posse dos resultados, realizou-se a análise estatística pelo teste Kruskal-Wallis. Os autores concluíram que no terço médio não houve diferença estatisticamente significante no tocante à obstrução dos túbulos dentinários dos cimentos obturadores testados. No entanto, em relação à obstrução dos cimentos nos túbulos do terço apical, houve uma significativa diferença entre Sealapex e Sealer Plus, assim como Sealapex e AH Plus, sendo que Sealapex e Tubliseal foram os que apresentaram melhor capacidade de obstrução de túbulos dentinários.