Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

Simplified dentin-bonding systems are clinically employed for most adhesive procedures, and they are prone to hydrolytic degradation. Objective This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC), water sorption (WS), and water solubility (WSB) of these bonding systems in an attempt to improve their physico-mechanical resistance. Material and Methods Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB)] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU)]. Square-shaped specimens were prepared and assigned into 4 groups (n=5): SB and SU (control groups – no laser irradiation) and SB-L and SU-L [SB and SU laser (L) – irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5) of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10) were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm), irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2). Results Laser irradiation immediately before photopolymerization increased the DC (%) of the tested adhesives: SB-L>;SB>;SU-L>;SU. For WS/WSB (μg/mm3), only the dentin bonding system (DBS) was a significant factor (p;SU. Conclusion Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility

Evaluation of an Experimental Gel Containing Euclea natalensis: An In Vitro Study

Objective. To evaluate the effect of an experimental gel containing Euclea natalensis extract on dentin permeability. Methods. Thirty-six dentin discs, 1-mm-thick. The discs were prepared from the coronal dentin of extracted human third molars that were divided into 3 groups (n = 10). The dentin discs in each group were treated with the groups following experimental materials: (FG): 1.23% fluoride gel, pH 4.1; (EG): Euclea natalensis extract gel, pH 4.1; (CG): control gel, pH 4.1. The gels were applied to the occlusal slide of the dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. The hydraulic conductance (HC) of each condition was determined four times using a fluid flow apparatus (Flodec). The data were analyzed using Two-way ANOVA and Tukey's test (P < 0.05). Results. The greatest mean reduction in HC was produced in group EG dentin discs (61.2%; P < 0.05). Even after acid challenge with 6% citric acid the great reduction occurred in group EG (66.0%; P < 0.05) than other groups (CG-77.1%, FG-90.8%). Conclusion. E. natalensis gel not only reduced dentin permeability, but also resisted posttreatment citric acid challenge without changing its permeability. Further research has to confirm this promising result in the clinical situation.FAPESPFAPESP [2009/16079-0, 2010/09951-0

Efeito da irradição do laser de Er, Cr: YSGG nas propriedades físicas de sistemas adesivos aplicados sobre a dentina

The analysis of some properties is necessary to better understand the mechanism by which an increase of bond strength values occurs when the dentin / adhesive complex is irradiated with laser. Thus, this study evaluated some physical properties of dentin bonding system [DBS] applied on dentin that were irradiated with Er: YSGG laser. The present study was a 2-level factor: treatment in 2 sub-levels (without laser [C] and Er: YSGG [L] laser) and DBS in 4 sub-levels: 3-step total etch Adper Scotchbond Multi-Purpose [MP], total etch 2-step Adper SingleBond 2 [SB], 2-step self-etch Clearfil SE Bond [CSE], 1-step self-etch Adper Single Bond Universal [SU]. The response variables were water sorption [WS] and water solubility [WSB] of DBS in dentin (n = 10) that were measured by gain and mass loss. The degree of conversion [DC] \"in situ\" (n = 3) was evaluated by Micro-Raman spectroscopy obtaining through the ratio of the polymerized / unpolymerized sample spectra. Infrared thermography analyzed the superficial temperature [TS] and the ceiling of the pulp chamber temperature [TC] during irradiation through a thermographic camera (n = 8). In addition, the characteristics of the resulting hybrid layer (n = 3) were also evaluated by scanning electronic microscopy (SEM). The bond strength (n = 10) was measured by the microtensile [MS] test with an area of approximately 0.64mm2 of irradiated dentin and submitted to aging for 1 year. The data were analyzed according to the distribution and homogeneity of the values, and then, WS/WSB, DC and MS were submitted to ANOVA 2 criteria and TS / TC tests submitted to ANOVA 1 criterion, followed by Tukey test (p < 0.05). For the WS/WSB, the group L presented smaller values, whereas for the SB, L presented higher values than the non-irradiated group. In DC, a significant difference was noted only for the DBS factor. In infrared thermography it was observed that L promoted a high increase of TS, but with low propagation to pulp chamber to TC. For the SEM, the conventional DBSs presented a great depth of adhesives penetration into the dentine than the self-etching systems, especially when irradiated with laser. For MS, the lowest values for L were observed, except for SUL. In the fracture analysis, it was observed that the most prevalent failure mode for all groups was adhesive and mixed. t was concluded that the irradiation with the Er, Cr: YSGG laser with the parameters used in the present study does not present clinical benefits, since it undermined most of the tested properties.A análise de algumas propriedades é necessária para melhor compreender o mecanismo pelo qual o aumento nos valores de resistência de união acontece quando o complexo dentina/adesivo é irradiado com laser. Dessa forma, este estudo avaliou algumas propriedades físicas de sistemas adesivos [SA] aplicados sobre a dentina que foram irradiados com laser de Er:YSGG. O presente estudo foi fatorial em 2 níveis: tratamento em 2 subníveis (sem laser [C] e com laser de Er:YSGG[L]) e sistema adesivo em 4 subníveis: convencional de 3 passos AdperScotchbond Multi- Purpose [MP], convencional de 2 passos Adper SingleBond 2 [SB], autocondicionante de 2 passos Clearfil SE Bond [CSE], autocondicionate de 1 passo Adper Single Bond Universal [SU]. As variáveis de respostas foram a sorção [SO] e solubilidade [SB] em dentina de sistemas adesivos (n=10) que foram mensuradas pelo ganho e perda de massa. O grau de conversão [GC] in situ (n=3) foi avaliado por meio da espectroscopia Micro-Raman obtendo através da relação dos espectros de amostras polimerizadas/ não polimerizadas. A termografia infravermelho analisou a temperatura superficial [TS] e do teto câmara pulpar [TC] através de uma câmera termográfica (n=8). Além disso, também foram avaliadas as características da camada híbrida (n=3) por meio da microscopia eletrônica de varredura [MEV]. A Resistência de união [RA] (n=10) foi mensurada pelo teste de microtração com área de aproximadamente 0,64mm2 e submetida ao envelhecimento 1 ano. Os dados foram analisados, de acordo com a distribuição e homogeneidade dos valores, e então, SO, SB, GC e RA foram submetidos ao teste ANOVA 2 critérios e TS/TC submetidos ao teste ANOVA 1 critério, seguido de teste Tukey (p<0,05). Para a SO/SB, o grupo L apresentou menores valores significativos, já para a SB o L apresentou valores maiores que o grupo não irradiado. No GC, notou-se uma diferença significativa apenas para o fator SA. Na termografia infravermelho observou que o L promoveu um aumento de alta TS, mas com baixa propagação no TC. Para o MEV, os SAs convencionais apresentaram grande profundidade de penetração dos adesivos na dentina do que os sistemas autocondicionantes, especialmente quando irradiados com laser. Para RA, foram observados os menores valores para o L com exceção do SUL. Na análise de fratura observou que o modo de falha mais predominante para todos os grupos foi adesivo e misto. Concluiu-se que a irradiação com o laser Er, Cr: YSGG com os parâmetros do utilizados no presente estudo não apresentou benefícios clínicos, visto que prejudicou a maioria das propriedades testadas

Efeito da irradição do laser de Er, Cr: YSGG nas propriedades físicas de sistemas adesivos aplicados sobre a dentina

The analysis of some properties is necessary to better understand the mechanism by which an increase of bond strength values occurs when the dentin / adhesive complex is irradiated with laser. Thus, this study evaluated some physical properties of dentin bonding system [DBS] applied on dentin that were irradiated with Er: YSGG laser. The present study was a 2-level factor: treatment in 2 sub-levels (without laser [C] and Er: YSGG [L] laser) and DBS in 4 sub-levels: 3-step total etch Adper Scotchbond Multi-Purpose [MP], total etch 2-step Adper SingleBond 2 [SB], 2-step self-etch Clearfil SE Bond [CSE], 1-step self-etch Adper Single Bond Universal [SU]. The response variables were water sorption [WS] and water solubility [WSB] of DBS in dentin (n = 10) that were measured by gain and mass loss. The degree of conversion [DC] \"in situ\" (n = 3) was evaluated by Micro-Raman spectroscopy obtaining through the ratio of the polymerized / unpolymerized sample spectra. Infrared thermography analyzed the superficial temperature [TS] and the ceiling of the pulp chamber temperature [TC] during irradiation through a thermographic camera (n = 8). In addition, the characteristics of the resulting hybrid layer (n = 3) were also evaluated by scanning electronic microscopy (SEM). The bond strength (n = 10) was measured by the microtensile [MS] test with an area of approximately 0.64mm2 of irradiated dentin and submitted to aging for 1 year. The data were analyzed according to the distribution and homogeneity of the values, and then, WS/WSB, DC and MS were submitted to ANOVA 2 criteria and TS / TC tests submitted to ANOVA 1 criterion, followed by Tukey test (p < 0.05). For the WS/WSB, the group L presented smaller values, whereas for the SB, L presented higher values than the non-irradiated group. In DC, a significant difference was noted only for the DBS factor. In infrared thermography it was observed that L promoted a high increase of TS, but with low propagation to pulp chamber to TC. For the SEM, the conventional DBSs presented a great depth of adhesives penetration into the dentine than the self-etching systems, especially when irradiated with laser. For MS, the lowest values for L were observed, except for SUL. In the fracture analysis, it was observed that the most prevalent failure mode for all groups was adhesive and mixed. t was concluded that the irradiation with the Er, Cr: YSGG laser with the parameters used in the present study does not present clinical benefits, since it undermined most of the tested properties.A análise de algumas propriedades é necessária para melhor compreender o mecanismo pelo qual o aumento nos valores de resistência de união acontece quando o complexo dentina/adesivo é irradiado com laser. Dessa forma, este estudo avaliou algumas propriedades físicas de sistemas adesivos [SA] aplicados sobre a dentina que foram irradiados com laser de Er:YSGG. O presente estudo foi fatorial em 2 níveis: tratamento em 2 subníveis (sem laser [C] e com laser de Er:YSGG[L]) e sistema adesivo em 4 subníveis: convencional de 3 passos AdperScotchbond Multi- Purpose [MP], convencional de 2 passos Adper SingleBond 2 [SB], autocondicionante de 2 passos Clearfil SE Bond [CSE], autocondicionate de 1 passo Adper Single Bond Universal [SU]. As variáveis de respostas foram a sorção [SO] e solubilidade [SB] em dentina de sistemas adesivos (n=10) que foram mensuradas pelo ganho e perda de massa. O grau de conversão [GC] in situ (n=3) foi avaliado por meio da espectroscopia Micro-Raman obtendo através da relação dos espectros de amostras polimerizadas/ não polimerizadas. A termografia infravermelho analisou a temperatura superficial [TS] e do teto câmara pulpar [TC] através de uma câmera termográfica (n=8). Além disso, também foram avaliadas as características da camada híbrida (n=3) por meio da microscopia eletrônica de varredura [MEV]. A Resistência de união [RA] (n=10) foi mensurada pelo teste de microtração com área de aproximadamente 0,64mm2 e submetida ao envelhecimento 1 ano. Os dados foram analisados, de acordo com a distribuição e homogeneidade dos valores, e então, SO, SB, GC e RA foram submetidos ao teste ANOVA 2 critérios e TS/TC submetidos ao teste ANOVA 1 critério, seguido de teste Tukey (p<0,05). Para a SO/SB, o grupo L apresentou menores valores significativos, já para a SB o L apresentou valores maiores que o grupo não irradiado. No GC, notou-se uma diferença significativa apenas para o fator SA. Na termografia infravermelho observou que o L promoveu um aumento de alta TS, mas com baixa propagação no TC. Para o MEV, os SAs convencionais apresentaram grande profundidade de penetração dos adesivos na dentina do que os sistemas autocondicionantes, especialmente quando irradiados com laser. Para RA, foram observados os menores valores para o L com exceção do SUL. Na análise de fratura observou que o modo de falha mais predominante para todos os grupos foi adesivo e misto. Concluiu-se que a irradiação com o laser Er, Cr: YSGG com os parâmetros do utilizados no presente estudo não apresentou benefícios clínicos, visto que prejudicou a maioria das propriedades testadas

Evaluation of water sorption/solubility and conversion degree of the adhesive systems irradiated with diode laser

O LASER tem sido utilizado previamente a polimerização de sistemas adesivos em dentina como uma estratégia para melhorar as suas propriedades. O objetivo deste estudo foi investigar o efeito do LASER de diodo na sorção (SB), solubilidade e grau de conversão das principais categorias de sistemas adesivos. Quatro sistemas adesivos foram testados: convencional de 3 passos (Adper&#x2122; Scotchbond&#x2122; Multi-Purpose-MP), convencional de 2 passos (Adper&#x2122; Single Bond 2-SB), autocondicionante de 2 passos (Clearfil&#x2122; SE Bond-SE) e o sistema universal (Adper&#x2122; Single Bond Universal-SU). O adesivo fluido foi dispensado numa matriz de teflon (6.0 x 6.0 x 1 m),irradiado com laser de diodo com 970 nm e polimerizado com luz LED. Para o teste de sorção e solubilidade foram preparados espécimes em uma matriz de teflon quadrada (n=10): MP, SB, SE e SU (sem irradiação) e MP-L, SB-L, SE-L e SU-L (grupos com irradiação). Essa mensuração foi monitorando a mudança de massa depois dos ciclos de armazenamento de desidratação/ água. Para o grau de conversão, espécimes similares eram preparados e divididos 8 grupos iguais (n=5), utilizando a espectroscopia infravermelho transformada de Fourrrier (FTIR) com reflectância total atenuada (ATR). Cada espécime era comprimido contra o cristal do ATR (diamante/ZnSe) com um pressão micrométrica. As amostras não polimerizadas (&#x2248;3.0&#x3BC;L, n=5) de cada adesivo era escaneada para calcular o grau de conversão. Para sorção (&#x3BC;g/mm3) houve diferença estatisticamente significante para ambos os fatores (p SU> MP> SE. Para a solubilidade (&#x3BC;g/mm3), somente o fator adesivo foi significante (pSU>MP=SE. A irradiação do LASER antes da polimerização aumentou o grau de conversão dos sistemas adesivos SBL> MP-L> SE-L> MP> SB> SE> SU-L> SU. A irradiação aumentou a sorção, mas não afetou a solubilidade dos sistemas adesivos. Além disso, a irradiação com LASER de diodo melhorou o grau de conversão de três sistemas adesivos testados.Laser irradiation has been used over the dentin bonding systems (DBS) prior to polymerization as a strategy to improve their properties. The aim of this study was to investigate the effect of diode laser on water sorption (WS), solubility (WSB) and conversion degree (DC) of main categories of DBS. Four bonding agents were tested: 3-step total-etch (Adper&#x2122; Scotchbond&#x2122; Multi-Purpose-MP), 2-step total-etch (Adper&#x2122; Single Bond 2-SB), 2-step self-etch Clearfil&#x2122; SE Bond-SE) and universal system (Adper&#x2122; Single Bond Universal-SU). The fluid DBSs were dispensed into Teflon molds (6.0 x 6.0 x 1mm), irradiated with a 970 nm diode laser and then polymerized with a LED curing unit. For WS/WSB tests, square-shaped DBS were prepared (n=10): MP, SB, SE and SU (control groups/ no laser irradiation) and MP-L, SB-L, SE-L and SU-L (laser irradiated groups). WS/WSB were measured by monitoring the mass changes after dehydration/water storage cycles. For DC tests, similar square-shaped specimens were prepared and assigned into eight similar groups (n=5), using Fourier transform infrared spectroscopy (FT-IR) with attenuated total reflectance (ATR). Each cured specimen was compressed against the ATR crystal (diamond/ZnSe) with a micrometric, low-pressure clamp. Uncured resin samples (&#x2248;3.0&#x3BC;L, n=5) of each adhesive were also scanned for DC calculation. For WS (&#x3BC;g/mm3), both factors were statistically significant (pSU>MP>SE. For WSB (&#x3BC;g/mm3), only DBS was a significant factor (pSU>MP=SE. Laser irradiation immediately before photopolymerization has increased the DC (%) of the tested adhesives: SB-L> MPL> SE-L> MP> SB> SE> SU-L> SU. Irradiation with diode laser improved the conversion degree of all tested dentin bonding systems. Furthermore the diode laser increased the sorption, but did not affect their water solubility

Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

Abstract Simplified dentin-bonding systems are clinically employed for most adhesive procedures, and they are prone to hydrolytic degradation. Objective This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC), water sorption (WS), and water solubility (WSB) of these bonding systems in an attempt to improve their physico-mechanical resistance. Material and Methods Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB)] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU)]. Square-shaped specimens were prepared and assigned into 4 groups (n=5): SB and SU (control groups – no laser irradiation) and SB-L and SU-L [SB and SU laser (L) – irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5) of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10) were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm), irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2). Results Laser irradiation immediately before photopolymerization increased the DC (%) of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (μg/mm3), only the dentin bonding system (DBS) was a significant factor (pSU. Conclusion Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility