Influence of root canal sealer on the radiographic appearance of filling voids in maxillary single-rooted teeth

Objective: This study compared the influence of three epoxy resin-based sealers with distinct radiopacities on the observers' ability to detect root canal filling voids during radiographic analysis. Material and methods: The root canals of 48 extracted maxillary canines were prepared and divided into three groups. Each group was laterally condensed with one sealer (AH Plus (TM), Acroseal (R) or a non-radiopaque sealer), and a longitudinal void was simulated in half of the specimens from each group (n = 8). Buccolingual radiographs were obtained and randomly interpreted for voids by a radiologist and an endodontist in a blinded fashion. Teeth were cut and inspected under a microscope to confirm the position of void. Differences in sensitivity and specificity between groups and examiners were compared using the Fisher's Exact and McNemar tests, respectively (alpha = 0.05). Results: Significantly lower sensitivity levels (p<0.05) were observed in the coronal portion of fillings performed with both radiopaque sealers. Specificity values for Acroseal (R) were significantly higher (p<0.05) in the coronal and apical portions of fillings. Conclusion: The type of root canal sealer can affect the observers' ability to detect root canal filling voids during radiographic analysis of upper single-rooted teeth.

Optimizing endodontic irrigation: advantages of negative apical pressure technology

FAPESP #2010/16002-4

The antimicrobial effect of new and conventional endodontic irrigants on intra-orally infected dentin

Objectives. To evaluate if the incorporation of antimicrobial compounds to chelating agents or the use of chelating agents with antimicrobial activity as 7% maleic acid and peracetic acid show similar disinfection ability in comparison to conventional irrigants as sodium hypochlorite or iodine potassium iodide against biofilms developed on dentin. Materials and methods. The total bio-volume of live cells, the ratio of live cells and the substratum coverage of dentin infected intra-orally and treated with the irrigant solutions: MTAD, Qmix, Smear Clear, 7% maleic acid, 2% iodine potassium iodide, 4% peracetic acid, 2.5% and 5.25% sodium hypochlorite was measured by using confocal microscopy and the live/dead technique. Five samples were used for each irrigant solution. Results. Several endodontic irrigants containing antimicrobials as clorhexidine (Qmix), cetrimide (Smear Clear), maleic acid, iodine compounds or antibiotics (MTAD) lacked an effective antibiofilm activity when the dentin was infected intra-orally. The irrigant solutions 4% peracetic acid and 2.5–5.25% sodium hypochlorite decrease significantly the number of live bacteria in biofilms, providing also cleaner dentin surfaces (p < 0.05). Conclusions. Several chelating agents containing antimicrobials could not remove nor kill significantly biofilms developed on intra-orally infected dentin, with the exception of sodium hypochlorite and 4% peracetic acid. Dissolution ability is mandatory for an appropriate eradication of biofilms attached to dentin.

Evaluation of apically extruded debris during endodontic retreatment

Introduction: A growing interest to preserve teeth into the mouth by patients resulted in the increasing number of endodontic retreatments, and when these happen, many different types of irritants are extruded through the foramen. Objective: This study analyzed in vitro the amount of debris extruded through the foramen using four instrumentation techniques during endodontic retreatment. Material and methods: Forty mesial-buccal roots of first molars were selected, instrumented with anatomical diameter up to size #30 ISO file and then obturated with gutta-percha and grossman sealer by lateral condensation. After, they were separated and randomly allocated into four groups with 10 teeth each for the endodontic retreatment procedure: G1 – conventional technique + solvent, G2 – conventional technique without solvent, G3 – ProTaper retreatment + solvent, G4 – ProTaper retreatment without solvent. In all groups, gutta-percha in the coronal portion was removed by using size 1-3 Gates Glidden drills. All teeth were irrigated with distilled water. The debris extruded through the foramen were collected and weighed by an analytical balance. Results: Group 4 had the lowest average for material extrusion through the foramen followed by groups 2, 3 and 1. When Tukey test for statistical analysis was applied, no significant difference among groups were found (p = 0.5664). Conclusion: We conclude that all instrumentation techniques used in this study produced debris which goes beyond the foramen.

Removal of fractured endodontic instruments using an Nd:YAG laser.

OBJECTIVE Fractured endodontic instruments inhibit optimal cleaning and filling of dental root canals, which may result in a less favorable prognosis for the tooth. Several techniques are available to remove fractured instruments; however, healthy tooth substance often must be destroyed in the process. This study was intended to evaluate Nd:YAG laser treatment as a method to remove fractured stainless steel instruments without destroying healthy tooth substance. METHOD AND MATERIALS Stainless steel endodontic instruments were fractured in 33 unprocessed root canals of mandibular central and lateral incisors and premolars in vitro. A brass tube charged with solder was placed at the coronal end of the fractured instrument and laser energy was used to melt the solder, connecting the fractured instrument with the brass tube. The success rates of connecting and removal of fractured instruments from the root channel were recorded for each case. RESULTS Connecting was achieved in every case in which more than 1.5 mm of the fractured instrument was tangible (22 out of 22). In cases where less than 1.5 mm was tangible, the rate for successful connection decreased to 4 out of 11 (36.4%). Fractured endodontic instruments were removed successfully in 17 out of 22 cases (77.3%) in which more than 1.5 mm was tangible. If less than 1.5 mm was tangible, the removal success rate decreased to 3 out of 11 cases (27.3%). CONCLUSION Our data support Nd:YAG laser-mediated connecting of a brass tube to a fractured endodontic instrument as a feasible and tissue conserving removal approach when more than 1.5 mm of the instrument is tangible.

Aferição das dificuldades/competências na área da Endodontia percepcionadas pelos alunos do 4º e 5º anos da FCS-UFP

Introdução: Com uma consciencialização cada vez maior das populações para a preservação dos dentes naturais, a Endodontia tem assumido uma importância crescente, tendo por objectivo principal a manutenção de dentes funcionais, sem prejudicar a saúde dos pacientes. Estes devem beneficiar de um tratamento segundo o “standard of care”, proporcionado por profissionais competentes. Vários estudos demonstram que a Endodontia é considerada uma área difícil e stressante para os estudantes, exibindo um sentimento de menor confiança na prática clínica, sobretudo no que diz respeito a procedimentos mais complexos, nomeadamente, no tratamento de dentes posteriores. Em 2010, na tentativa de homogeneizar as competências adquiridas pelos Médicos Dentistas (MD), a Associação para a Educação Dentária Europeia (AEDE) definiu critérios para a sua formação pré-graduada, indicando que o MD recém-graduado deve ter adquirido competências e capacidades técnicas que lhe permita começar a sua prática clínica de forma independente. Objectivos: Analisar os conhecimentos adquiridos e as dificuldades sentidas na área da Endodontia pelos alunos do 4º e 5º anos do Mestrado Integrado em Medicina Dentária da Faculdade de Ciências de Saúde (FCS) da Universidade Fernando Pessoa (UFP), fazendo, igualmente, uma abordagem ao ensino ministrado na área da Endodontia face aos resultados obtidos. Materiais e Métodos: Este trabalho está dividido em duas partes: revisão bibliográfica e investigação científica. A revisão bibliográfica do tema engloba o ensino graduado em Medicina Dentária, o uso de isolamento absoluto (IA) na prática clínica de Endodontia, a instrumentação manual versus rotatória, a influência no sucesso do tratamento endodôntico (TE) da sua execução por estudantes do 4º e 5º ano, as Guidelines para o TE e o ensino de Endodontia na UFP. A pesquisa bibliográfica foi efectuada através da base de dados PubMed, tendo sido utilizadas, em diferentes combinações, as seguintes palavras-chave: ”Endodontics”, “teaching”; “pre-clinical”; “undergraduate”; “Clinical”; “treatment” e “Europe”. O trabalho de investigação consistiu na elaboração, aprovação pela Comissão de Ética da UFP e posterior aplicação de um questionário destinado aos alunos do 4º e 5º ano do Mestrado Integrado em Medicina Dentária da FCS-UFP. A população estimada de alunos do 4º ano foi de 190 alunos e a de 5º ano de 150 alunos, o que perfaz um total de 340 alunos. Dos inquéritos respondidos, apenas foram considerados 338, uma vez que dois foram anulados pois continham respostas inválidas. Resultados: A “condição socioeconómica do paciente” foi considerada a causa menos relevante para avaliar um caso endodôntico, tendo sido apontada por 34,3% dos alunos. Assinala-se que 92% dos alunos de 4º ano e 93,3% dos alunos de 5º ano consideram que os molares superiores são os dentes mais difíceis de tratar, sendo a visibilidade uma das principais razões para esta opinião. O grau de dificuldade para a colocação do IA é definido como “Elevado” para a maioria dos alunos de 4º ano. A maior parte dos alunos de 5º ano considera que o grau de dificuldade para a “Determinação do tipo de reconstrução/prótese fixa mais indicada” é “Elevado”. O passo do TE onde os alunos do 4º ano se sentem mais confiantes é no “Diagnóstico de cárie”, sendo que os alunos do 5º ano se sentem mais confiantes ao realizar o “TE em dentes com 1 ou 2 canais”. O “Conteúdo leccionado nas aulas teóricas” foi considerado o principal aspecto positivo do ensino endodôntico. Por outro lado, o “Número de actos clínicos realizados” foi considerado o principal aspecto negativo, tanto para alunos de 4º como de 5º ano. Em ambos os anos, os principais pontos que os alunos acham que devem ser melhorados são o “Número de pacientes nas aulas clínicas” e a “Aprendizagem da técnica de instrumentação mecanizada/obturação termoplástica”. As principais preocupações referidas, tanto por alunos de 4º como de 5º anos, foram a “Insegurança na prática clínica” e a “Dificuldade em encontrar ofertas profissionais”. Relativamente à qualidade dos seus TE existe um número significativo de alunos do 5º ano que já se auto-avaliam como “Bons” (33,6%), por comparação com os do 4º ano (21,2%), sendo a auto-avaliação de “Razoável” dominante em ambos os anos de formação. Conclusões: Conclui-se que na disciplina de Endodontia na FCS-UFP, são seguidas as Guidelines da European Society of Endodontology (ESE), sendo que estas indicam o protocolo mais correcto a seguir durante o Tratamento Endodôntico Não-Cirúrgico (TENC). Contudo, o reduzido número de actos clínicos e a consequente falta de prática faz com que os alunos se sintam pouco confiantes ao iniciar a sua actividade profissional.

A new low temperature synthesis route of fraipontite (Zn,Al)3(Si,Al)2O5(OH)4

A low temperature synthesis method based on the decomposition of urea at 90°C in water has been developed to synthesise fraipontite. This material is characterised by a basal reflection 001 at 7.44 Å. The trioctahedral nature of the fraipontite is shown by the presence of a 06l band around 1.54 Å, while a minor band around 1.51 Å indicates some cation ordering between Zn and Al resulting in Al-rich areas with a more dioctahedral nature. TEM and IR indicate that no separate kaolinite phase is present. An increase in the Al content however, did result in the formation of some SiO2 in the form of quartz. Minor impurities of carbonate salts were observed during the synthesis caused by to the formation of CO32- during the decomposition of urea.

Raman spectroscopic characteristics of phthalocyanine and naphthalocyanine in sandwich-type phthalocyaninato and porphyrinato rare earth complexes Part 5. – Raman spectroscopic characteristics of naphthalocyanine in mixed [tetrakis(4-tert-butylphenyl)porphyrinato]-(naphthalocyaninato) rare earth double-deckers

Raman spectra were recorded in the range 400–1800 cm−1 for a series of 15 mixed \[tetrakis(4-tert-butylphenyl)porphyrinato](2,3-naphthalocyaninato) rare earth double-deckers M(TBPP)(Nc) (M = Y; La–Lu except Pm) using laser excitation at 632.8 and 785 nm. Comparisons with bis(naphthalocyaninato) rare earth counterparts reveal that the vibrations of the metallonaphthalocyanine M(Nc) fragment dominate the Raman features of M(TBPP)(Nc). When excited with radiation of 632.8 nm, the most intense vibration appears at about 1595 cm−1, due to the naphthalene stretching. These complexes exhibit the marker Raman band for Nc•− as a medium-intense band in the range 1496–1507 cm−1, attributed to the coupling of pyrrole and aza stretching, while the marker Raman band of Nc2− in intermediate-valence Ce(TBPP)(Nc) appears as a strong band at 1493 cm−1 and is due to the isoindole stretchings. By contrast, when excited with radiation of 785 nm that is in close resonance with the main Q absorption band of the naphthalocyanine ligand, the ring radial vibrations at ca 680 and 735 cm−1 for MIII(TBPP)(Nc) are selectively intensified and are the most intense bands. For the cerium double-decker, the most intense vibration also acting as the marker Raman band of Nc2− appears at 1497 cm−1 with contributions from both pyrrole CC and aza CN stretches. The same vibrational modes show weak to medium intensity scattering at 1506–1509 cm−1 for MIII(TBPP)(Nc) and this is the marker Raman band of Nc•− when thus excited. The scatterings due to the Nc breathings, ring radial vibration, aza group stretchings, naphthalene stretchings, benzoisoindole stretchings and the coupling of pyrrole CC and aza CN stretchings in MIII(TBPP)(Nc) are all slightly blue shifted along with the decrease in rare earth ionic radius, confirming the effects of increased ring–ring interactions on the Raman characteristics of naphthalocyanine in the mixed ring double-deckers.