Bond Strength of Dental Adhesive Systems Irradiated with Ionizing Radiation

Purpose: The aim of the present paper was to determine the effect of different types of ionizing radiation on the bond strength of three different dentin adhesive systems. Materials and Methods: One hundred twenty specimens of 60 human teeth (protocol number: 032/2007) sectioned mesiodistally were divided into 3 groups according to the adhesives systems used: SB (Adper Single Bond Plus), CB (Clearfil SE Bond) and AP (Adper Prompt Self-Etch). The adhesives were applied on dentin and photo-activated using LED (Lec 1000, MMoptics, 1000 mW/cm(2)). Customized elastomer molds (0.5 mm thickness) with three orifices of 1.2 mm diameter were placed onto the bonding areas and filled with composite resin (Filtek Z-250), which was photo-activated for 20 s. Each group was subdivided into 4 Subgroups for application of the different types of ionizing radiation: ultraviolet radiation (UV), diagnostic x-ray radiation (DX), therapeutic x-ray radiation (TX) and without irradiation (control group, CG). Microshear tests were carried out (Instron, model 4411), and afterwards the modes of failure were evaluated by optical and scanning electron microscope and classified using 5 scores: adhesive failure, mixed failures with 3 significance levels, and cohesive failure. The results of the shear bond strength test were submitted to ANOVA with Tukey`s test and Dunnett`s test, and the data from the failure pattern evaluation were analyzed with the Mann Whitney test (p = 0.05). Results: No change in bond strength of CB and AP was observed after application of the different radiation types, only SB showed increase in bond strength after UV (p = 0.0267) irradiation. The UV also changed the failure patterns of SB (p = 0.0001). Conclusion: The radio-induced changes did not cause degradation of the restorations, which means that they can be exposed to these types of ionizing radiation without weakening the bond strength.

Microbiopsies of Surface Dental Enamel as a Tool to Measure Body Lead Burden

Lead (Pb) poisoning is preventable but continues to be a public health problem in several countries. Measuring Pb in the surface dental enamel (SDE) using microbiopsies is a rapid, safe, and painless procedure. There are different protocols to perform these microbiopsies, but the reliability of dental enamel lead levels (DELL) determination is dependent upon biopsy depth (BD). It is established that DELL decrease from the outermost superficial layer to the inner layer of dental enamel. The aim of this study was to determine DELL obtained by two different microbiopsy techniques on SDE termed protocol I and protocol II. Two consecutive enamel layers were removed from the same subject group (n = 138) for both protocols. Protocol I consisted of a biopsied site with a diameter of 4 mm after the application of 10 l HCl for 35 s. Protocol II involved a biopsied site of 1.6 mm diameter after application of 5 l HCl for 20 s. The results demonstrated that there were no significant differences for BD and DELL between homologous teeth using protocol I. However, there was a significant difference between DELL in the first and second layers using both protocols. Further, the BD in protocol II overestimated DELL values. In conclusion, SDE analyzed by microbiopsy is a reliable biomarker in protocol I, but the chemical method to calculate BD in protocol II appeared to be inadequate for measurement of DELL. Thus, DELL could not be compared among studies that used different methodologies for SDE microbiopsies.

Presence of bacteria in dentinal tubules

This study demonstrated that a significant number of bacteria is present. in the radicular dentinal tubules of periodontally diseased human teeth. Ten periodontally diseased teeth were prepared and stained by Brown and Brenn technique for histological examination. Bacteria were detected in all teeth. It is suggested that bacteria may invade dentinal tubules exposed to periodontal pocket and are very hard to be eliminated by conventional mechanical and chemical periodontal therapy. Contaminated dentinal tubules of periodontally diseased teeth can thus act as active bacterial reservoirs to promote recolonization of mechanically treated root surfaces, which could interfere with the periodontal healing and progression of the disease.

Comparative analysis of root surface smear layer removal by different etching modalities or erbium:yttrium-aluminum-garnet laser irradiation. A scanning electron microscopy study

The purpose of this study was to evaluate the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mu m) irradiation on the removal of root surface smear layer of extracted human teeth and to compare its efficacy with that of citric acid, ethylenediamine tetra-acetic acid (EDTA), or a gel containing a mixture of tetracycline hydrochloride (HCl) and citric acid, using scanning electron microscopy (SEM). Thirty human dentin specimens were randomly divided into six groups: G1 (control group), irrigated with 10 ml of physiologic saline solution; G2, conditioned with 24% citric acid gel; G3, conditioned with 24% EDTA gel; G4, conditioned with a 50% citric acid and tetracycline gel; G5, irradiated with Er:YAG laser (47 mJ/10 Hz/5.8 J/cm(2)/pulse); G6, irradiated with Er:YAG laser (83 mJ/10 Hz/10.3 J/cm(2)/pulse). Electron micrographs were obtained and analyzed according to a rating system. Statistical analysis was conducted with Kruskal-Wallis and Mann-Whitney tests (P < 0.05). G1 was statistically different from all the other groups; no statistically significant differences were observed between the Er:YAG laser groups and those undergoing the other treatment modalities. When the two Er:YAG laser groups were compared, the fluency of G6 was statistically more effective in smear layer removal than the one used in G5 (Mann-Whitney test, P < 0.01). Root surfaces irradiated by Er:YAG laser had more irregular contours than those treated by chemical agents. It can be concluded that all treatment modalities were effective in smear layer removal. The results of our study suggest that the Er:YAG laser can be safely used to condition diseased root surfaces effectively. Furthermore, the effect of Er:YAG laser irradiation on root surfaces should be evaluated in vivo so that its potential to enhance the healing of periodontal tissues can be assessed.

The influence of time interval between bleaching and enamel bonding

Objectives: the purpose of this study was to investigate the penetration of a conventional adhesive material into enamel bleached with 16% carbamide peroxide and 38% hydrogen peroxide using optical light microscopy.Methods: Extracted human teeth were randomly divided into eight experimental groups with six specimens each, according to the bleaching material and time interval after bleaching and before the bonding procedure. Groups were designated as follows: control group, restorations in unbleached teeth; restorations performed immediately after bleaching; restorations performed 7 days after bleaching; restorations performed 14 days after bleaching; and restorations performed 30 days after bleaching. The length of resin tags was measured with an Axiophot photomicroscope at 400x magnification for the calculation of the proportion of tags of study groups compared to the respective control groups. Analysis of variance was applied for comparison between groups; data were transformed into arcsine (p < 0.05).Results: the specimens of experimental groups, in which restorations were performed 7, 14, and 30 days after bleaching, showed better penetration of adhesive material into enamel than specimens restored immediately after bleaching. There was no statistically significant difference between the bleaching materials employed or in the interaction between bleaching agent and time interval.Conclusions: This suggests that a time interval of at least 7 days should be allowed between enamel bleaching and placement of adhesive bonding agents for accomplishment of composite resin restorations.

Estudo in vivo e in vitro com e sem termociclagem, da resistência ao cisalhamento de braquetes colados com fonte de luz halógena

OBJETIVO: avaliar a resistência de braquetes metálicos colados em dentes humanos com resina polimerizada com luz halógena por meio de ensaios mecânicos de cisalhamento. METODOLOGIA: para este estudo foram realizados ensaios in vivo com dinamômetro portátil digital e in vitro com máquina de ensaios mecânicos universal com e sem termociclagem, complementado pelo Índice de Adesivo Remanescente (IAR). Braquetes Edgewise Standard (Abzil) foram colados utilizando adesivo Transbond Plus Self Etching Primer (SEP) e Resina Transbond XT. Foram formados 3 grupos com 10 dentes em cada um deles. No GI os braquetes foram colados nos segundos pré-molares dos pacientes. Nos GII e GIII utilizaram-se primeiros pré-molares extraídos por motivos ortodônticos. Os ensaios mecânicos do GI foram realizados 24 horas após a polimerização diretamente na boca dos pacientes com dinamômetro portátil digital. No GII os corpos-de-prova foram armazenados em água destilada e levados à estufa a 37ºC durante 24 horas e, posteriormente, submetidos à termociclagem, com 1000 ciclos a 5 e 55ºC. No GIII os corpos-de-prova foram armazenados em água destilada em temperatura ambiente por 24 horas e posteriormente submetidos aos ensaios mecânicos. RESULTADOS: os valores médios da resistência ao cisalhamento em Megapascal foram de: GI = 4,39; GII = 7,11 e GIII = 7,35. Após a descolagem foram realizadas fotografias das áreas de colagem, tanto dos dentes submetidos a testes in vivo quanto in vitro e ampliadas 5x para facilitar a visualização. As imagens obtidas foram analisadas, classificadas de acordo com o IAR e, por meio de gráficos de dispersão, foi verificada a relação entre a resistência ao cisalhamento e este índice. CONCLUSÃO: a média dos ensaios mecânicos realizados in vivo foi estatisticamente menor em relação aos ensaios in vitro. Não houve diferenças na resistência ao cisalhamento in vitro entre o grupo termociclado e o não-termociclado. Não houve relação entre tensão de ruptura e tipo de falha.

Effect of Er : YAG and diode lasers on the adhesion of blood components and on the morphology of irradiated root surfaces

Objectives: the aim of this study was to evaluate in vitro, by scanning electron microscopy (SEM), the adhesion of blood components on root surfaces irradiated with Er:YAG (2.94 mu m) and GaAlAs Diode (808 nm) lasers and the effects on the morphology of irradiated root surfaces.Methods: One hundred samples of human teeth were obtained. They were previously planed and scaled with manual instruments and divided into five groups of 20 samples each: G1 (control group) - absence of treatment; G2 - Er:YAG laser (7.6 J/cm(2)); G3 - Er:YAG laser (12.9 J/cm(2)); G4 - Diode laser (90 J/cm(2)) and G5 - Diode laser (108 J/cm(2)). After these treatments, 10 samples of each group received a blood tissue but the remaining 10 did not. After laboratory treatments, the samples were obtained by SEM, the photomicrographs were analysed by the score of adhesion of blood components and the results were statistically analysed (Kruskall-Wallis and Mann-Whitney test).Results: In relation to the adhesion of blood components, the study showed no significant differences between the control group and the groups treated with Er:YAG laser (p = 0.9633 and 0.6229). Diode laser radiation was less effective than control group and Er:YAG laser radiation (p < 0.01).Conclusion: None of the proposed treatments increased the adhesion of blood components in a significant way when compared to the control group. Although the Er:YAG laser did not interfere in the adhesion of blood components, it caused more changes on the root surface, whereas the Diode laser inhibited the adhesion.

Effect of Er,Cr:YSGG and Er:YAG laser irradiation on the adhesion of blood components on the root surface and on root morphology

The aim of this study was to conduct an in vitro evaluation, by scanning electron microscopy (SEM), of the adhesion of blood components on root surfaces irradiated with Er,Cr:YSGG (2.78 mu m) or Er:YAG (2.94 mu m) laser, and of the irradiation effects on root surface morphology. Sixty samples of human teeth were previously scaled with manual instruments and divided into three groups of 20 samples each: G1 (control group) - no treatment; G2 - Er,Cr:YSGG laser irradiation; G3 - Er:YAG laser irradiation. After performing these treatments, blood tissue was applied to 10 samples of each group, whereas 10 samples received no blood tissue application. After performing the laboratory treatments, the samples were observed under SEM, and the resulting photomicrographs were classified according to a blood component adhesion scoring system and root morphology. The results were analyzed statistically (Kruskall-Wallis and Mann Whitney tests, alpha = 5%). The root surfaces irradiated with Er:YAG and Er,Cr:YSGG lasers presented greater roughness than those in the control group. Regarding blood component adhesion, the results showed a lower degree of adhesion in G2 than in G1 and G3 (G1 x G2: p = 0.002; G3 x G2: p = 0.017). The Er:YAG and Er,Cr:YSGG laser treatments caused more extensive root surface changes. The Er:YAG laser treatment promoted a greater degree of blood component adhesion to root surfaces, compared to the Er,Cr:YSGG treatment.

Effect of alternative photostimulable phosphor plates erasing times on subjective digital image quality

Objective: To evaluate the influence of alternative erasing times of DenOptix (R) (Dentsply/Gendex, Chicargo, IL) digital plates oil subjective image quality and the probability of double exposure image not Occurring.Methods: Human teeth were X-rayed with phosphor plates using tell different erasing times. Two observers evaluated the images for subjective Image quality (sharpness, brightness, contrast, enamel definition, dentin definition and dentin-enamal Junction definition) and for the presence or absence of double exposure image. Spearman's correlation analysis and ANOVA was performed to verify the existence ora linear association between the subjective image quality parameters and the alternative erasing times. A contingency table was constructed to evaluate the agreement among the observers, and a binominal logistic regression was performed to verify the correlation between the erasing time and the probability of double exposure image not occurring.Results: All 6 parameters or image quality were rated high by the examiners for the erasing times between 25 s and 130 s. The same erasing time range, from 25 to 130 s, was considered a safe erasing time interval, with no probability of a double exposure image Occurring.Conclusions: The alternative erasing times from 25 s to 130 s showed high quality and no probability of double image Occurrence. Thus, it is possible to reduce the operating time or the DenOptix (R) digital system Without jeopardizing the diagnostic task.Dentomaxillofacial Radiology (2010) 39, 23-27. doi: 10.1259/dmfr/49065239.

Influence of root-surface conditioning with acid and chelating agents on clot stabilization

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Antibacterial effectiveness of several irrigating solutions and the Endox Plus system - an ex vivo study

Aim To compare the ex vivo antibacterial effectiveness of the Endox Plus system and sodium hypochlorite (NaOCl) in combination with BioPure MTAD (Tulsa Dental, Tulsa, OK, USA) or with EDTA in Enterococcus faecalis-contaminated root canals.Methodology After initial preparation, the root canals of 70 single-rooted human teeth were inoculated with E. faecalis (ATCC 29212) and incubated for 21 days. Specimens were divided into five groups: Endox Plus/saline; 2.5% NaOCl/MTAD; 2.5% NaOCl/EDTA; saline (positive control); negative control (root canals not prepared, nor irrigated). Samples were collected using paper points. Microbiological analysis evaluated the number of CFUs. Data were analysed by anova and Tukey tests at 0.05 significance.Results All specimens had bacterial growth after the incubation period, with similar CFU per mL counts (P > 0.05). After chemo-mechanical preparation, the number of bacteria in all groups reduced, except for the negative control. No significant differences were observed between 2.5% NaOCl/MTAD and 2.5% NaOCl/EDTA, but these groups had lower CFU counts than the other groups (P < 0.05). In the final samples, an increase in the bacterial counts was observed for Endox Plus/saline, 2.5% NaOCl/MTAD, 2.5% NaOCl/EDTA and saline (P < 0.05) with no significant differences between these groups.Conclusions This ex vivo study revealed that the Endox Plus system was associated with a reduced antibacterial effectiveness compared with conventional irrigation using 2.5% NaOCl/MTAD and 2.5% NaOCl/EDTA. All irrigation procedures allowed recovery of bacteria 7 days after treatment, demonstrating persistence of contamination within the root canal system.

Bond strength of different endodontic sealers to dentin: push-out test

Objective: The aim of this in vitro study was to evaluate the bond strength of different root canal sealers to dentin. Material and Methods: Forty extracted single-rooted human teeth were examined and the coronal and middle thirds of the canals were prepared with a 1.50 mm post drill (FibreKor Post System, Pentron). The teeth were allocated in two experimental groups, irrigated with 2.5% NaOCl+17% EDTA or saline solution (control group) and instrumented using Race rotary files (FKG) to a size #40 at the working length. Then, the groups were divided into four subgroups and filled with Epiphany sealer (Group 1), EndoREZ (Group 2), AH26 (Group 3) and Grossman's Sealer (Group 4). After 2 weeks of storage in 100% humidity at 37 degrees C, all teeth were sectioned transversally into 2-mm-thick discs. Push-out tests were performed at a cross-head speed of 1 mm/min using a universal testing machine. The maximum load at failure was recorded and expressed in MPa. Results: Means (+/- SD) in root canals irrigated with 2.5% NaOCl and 17% EDTA were: G1 (21.6 +/- 6.0), G2 (15.2 +/- 3.7), G3 (14.6 +/- 4.5) and G4 (11.7 +/- 4.1). Two-way ANOVA and Tukey's test showed the highest bond strength for the Epiphany's group (p < 0.01) when compared to the other tested sealers. Saline solution decreased the values of bond-strength (p < 0.05) for all sealers. Conclusion: Epiphany sealer presented higher bond strength values to dentin in both irrigating protocols, and the use of 2.5% NaOCl and 17% EDTA increased the bond strength values for all sealers.

Effectiveness of calcium hydroxide-based intracanal medicaments against Enterococcus faecalis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bacterial leakage in root canals filled with conventional and MTA-based sealers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antibacterial efficacy of endodontic irrigating solutions and their combinations in root canals contaminated with Enterococcus faecalis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)