Preheated acid associated with silane and electric current in the adhesion of the resin cement to ceramic

Abstract This study verified the effect of the combination of preheated hydrofluoric acid/silane/electric current in the adhesion of the resin cement to ceramic. IPS E.max Press ceramic discs embedded in PVC rigid tubes were divided into four groups associating preheated hydrofluoric acid and silane applied with electrical current (n=10): Ha+S (Heated acid + silane); Ha+S+Ec (Heated acid + silane + electrical current); A+S (Acid + silane) and A+S+Ec (Acid + silano + electrical current). Resin cement/ceramic samples were stored in water at 37°C for 24h. After storage, they were submitted to the microshear test, fracture analysis, and contact angle at 24h or after thermocycling (10,000 cycles/5-55ºC). Bond strength data were evaluated by two-way ANOVA. For comparison between evaluation times (24h or thermocycling) was applied unpaired t-test. A significance post-hoc test of p=0.05 was assumed for analyses and graphs (GraphPad Prism 9.0 software). At 24h, the microshear strength showed similar values between Ha+S, Ha+S+Ec, and A+S+Ec groups, while A+S showed the lowest value with a statistical difference. After thermocycling, Ha+S and Ha+S+Ec were similar, as well as A+S and A+S+Ec. There was a significant difference in all groups comparing 24h (highest value) with after thermocycling (lowest value). Adhesive fracture was predominant in all groups and evaluation times. Ha+S and A+S groups showed higher contact angle values compared to the Ha+S+Ec and A+S+Ec with lower values. In conclusion, the association of preheated hydrofluoric acid/silane applied or not with electric current promoted different microshear strength values, fracture types, and contact angles in the resin cement/ceramic bond.

Resumo Este estudo verificou o efeito da combinação ácido fluorídrico pré-aquecido/silano/corrente elétrica na adesão do cimento resinoso à cerâmica. Os discos cerâmicos IPS E.max Press embutidos em tubos rígidos de PVC foram separados em quatro grupos associando ácido fluorídrico pré-aquecido e silano aplicado com corrente elétrica (n=10): Ha+S (ácido aquecido + silano); Ha+S+Ec (Ácido aquecido + silano + corrente elétrica); A+S (Ácido + silano) e A+S+EC (Ácido + silano + corrente elétrica). Amostras de cimento resinoso/cerâmica foram armazenadas em água a 37°C por 24 horas. Após o armazenamento foram submetidas ao ensaio de micro cisalhamento, análise de fratura e ângulo de contato no período de 24 horas ou após termociclagem (10.000 ciclos/5-55ºC). Os dados de resistência de união foram avaliados por ANOVA dois fatores. Para comparação entre os tempos de avaliação (24 horas ou termociclagem) foi aplicado o teste t não pareado. Foi assumida significância de 5% para análises e gráficos (software GraphPad Prism 9.0). Em 24 horas, a resistência ao micro cisalhamento apresentou valores similares entre os grupos Ha+S, Ha+S+Ec e A+S+Ec, enquanto A+S apresentou menor valor com diferença estatística. Após a termociclagem, Ha+S e Ha+S+Ec foram similares, assim como A+S e A+S+Ec. Houve diferença significativa em todos os grupos comparando 24 horas (maior valor) com após termociclagem (menor valor). A fratura adesiva foi predominante em todos os grupos e tempos de avaliação. Os grupos Ha+S e A+S apresentaram maiores valores de ângulos de contato comparados aos grupos Ha+S+Ec e A+S+Ec com valores menores. Em conclusão, a associação ácido fluorídrico pré-aquecido/silano aplicado com corrente elétrica promoveu diferentes valores de resistência ao micro cisalhamento, tipos de fratura e ângulos de contato na adesão do cimento resinoso à cerâmica.

Evaluation the stress distribution in root canals by 3D finite element analysis after the materials used in reattaching the vertically root fractured fragments

Abstract The aim was to evaluate the effect of stress distribution on vertical, horizontal, and oblique forces on the tooth model after reattaching the fragments of the maxillary incisor with vertical root fracture (VRF) using different materials, by 3D finite element analysis (FEA). Tooth with a root canal, spongious, and cortical bone models were designed. VRF was modeled on a tooth with 4 different re-attachment models: Group 1: dual-cure cement (DC)+fiber reinforced composite (FRC), Group 2: DC+polyethylene fiber, Group 3: DC+glass fiber, and Group 4:DC. 100 N force was applied in 3 different directions. Maximum principal stresses (σmax) of dentin, and re-attachment materials were evaluated on colored images. The highest σmax values ​​were on the repair materials under vertical forces for Groups 1 and 4, respectively; Groups 2 and 3 showed similarity. The highest σmax values in repair materials under horizontal and oblique forces were observed in Group 3 however the lowest σmax values in repair materials under oblique and horizontal forces were observed in Group 1. The stress values ​​on repair materials gradually increased respectively starting from horizontal to vertical. As the elasticity modulus of the repair materials increased, the stress values ​​on root dentin increased. Through all force directions, except vertical forces, lower stress values were observed with FRC. The fracture resistance was bigger when using solely FRC or dual-cure resin cement in comparison to fiber-supported designs. Adding polyethylene fiber to re-restorations decreased stress values ​​compared to glass fiber addition. Therefore, when adding fibers, polyethylene fiber will be advantageous.

Resumo O objetivo foi avaliar o efeito da distribuição de estresse nas forças verticais, horizontais e oblíquas no modelo de dente após a recolocação dos fragmentos do incisivo superior com fratura radicular vertical (FRV) usando diferentes materiais, por meio da análise de elementos finitos (FEA) em 3D. Métodos: Foram projetados modelos de dentes com canal radicular, osso esponjoso e cortical. A FRV foi modelada em um dente com 4 modelos diferentes de reataque, como Grupo 1: cimento de cura dupla (DC) + compósito reforçado com fibra (FRC), Grupo 2: DC + fibra de polietileno, Grupo 3: DC + fibra de vidro e Grupo 4: DC. Foi aplicada uma força de 100 N em 3 direções diferentes. As tensões principais máximas (σmax) da dentina e os materiais de recolocação foram avaliados em imagens coloridas. Resultados: Os valores mais altos de σmax foram registrados nos materiais de reparo sob forças verticais para os Grupos 1 e 4, respectivamente; os Grupos 2 e 3 apresentaram semelhança. Os valores mais altos de σmax nos materiais de reparo sob forças horizontais e oblíquas foram observados no Grupo 3; no entanto, os valores mais baixos de σmax nos materiais de reparo sob forças oblíquas e horizontais foram observados no Grupo 1. Os valores de tensão nos materiais de reparo aumentaram gradualmente, respectivamente, começando da holizontal para a vertical. À medida que o módulo de elasticidade dos materiais de reparo aumentava, os valores de tensão na dentina da raiz aumentavam. Em todas as direções de força, exceto nas forças verticais, foram observados valores de tensão mais baixos com o FRC. Conclusões: a resistência à fratura foi maior quando se utilizou apenas FRC ou cimento resinoso de cura dupla em comparação com os designs com suporte de fibra. A adição de fibra de polietileno às restaurações diminuiu os valores de tensão em comparação com a adição de fibra de vidro. Portanto, ao adicionar fibras, a fibra de polietileno será vantajosa.

Impact of Access Cavity Design on Fracture Resistance of Endodontically Treated Maxillary First Premolar: In Vitro

Abstract This study was designed to investigate the impact of access cavity designs on fracture resistance of endodontically treated maxillary first premolars. The study sample consisted of 72 intact maxillary first premolars, randomly divided into six groups (n = 12). A standardized proximal cavity preparation was prepared for all samples using standard bur. Groups I: control group with only standard proximal cavity and no endodontic access, group II: Truss access cavity, group III: Separated access to buccal and palatal canals without removal of dentine in between, group IV: Access to buccal and palatal canals with removal of dentine in between, group V: Traditional access cavity, group VI: Mesio-occlusal-distal cavity (MOD). For groups I and VI, only composite restoration was used to restore the proximal cavity, while for groups II- V, the access was prepared and endodontic treatment was performed on all teeth, then composite restoration was placed. The root canals were instrumented using nickel-titanium files, irrigated with sodium hypochlorite, and filled with AH plus sealer and gutta-percha using warm vertical condensation. All samples were then placed in an acrylic mold and underwent thermal aging for 10,000 cycles between 5 and 55°C. The samples were fixed in a universal testing machine with the long axis of the roots positioned at 20° to a load applied at a crosshead speed of 1 mm/min using a stainless steel semi-spherical indenter (Ø = 3 mm) until fracture occurred to determine the fracture resistance force in Newton. The normality test (Shapiro-Wilk) showed that data are normally distributed. Group II exhibited the highest mean fracture resistance, and group VI was the least likely to resist the fracture. No statistically significant differences between tested groups (p-value = 0.237). The MOD group showed a more unfavorable mode of fracture compared to other groups. No significant difference in fracture resistance between conservative and traditional access cavities. The missing marginal ridges, such as in MOD cavities played an important role in decreasing the fracture resistance of endodontically treated teeth.

Resumo O objetivo deste estudo foi investigar o impacto do design da cavidade de acesso na resistência à fratura de primeiros pré-molares superiores tratados endodonticamente. MÉTODOS: A amostra do estudo consistiu em 72 primeiros pré-molares superiores intactos, divididos aleatoriamente em seis grupos (n = 12). Um preparo padronizado da cavidade proximal foi realizado para todas as amostras usando broca padrão. Grupos I: grupo de controle com apenas cavidade proximal padrão e sem acesso endodôntico, grupo II: cavidade de acesso Truss, grupo III: acesso separado aos canais vestibular e palatino sem remoção de dentina entre eles, grupo IV: acesso aos canais vestibular e palatino com remoção de dentina entre eles, grupo V: cavidade de acesso tradicional, grupo VI: cavidade mesio-oclusal-distal (MOD). Para os grupos I e VI, apenas a restauração de compósito foi usada para restaurar a cavidade proximal. Já nos grupos II e V, o acesso foi preparado e o tratamento endodôntico foi realizado em todos os dentes e, em seguida, foi colocada a restauração de resina composta. Os canais radiculares foram instrumentados com limas de níquel-titânio, irrigados com hipoclorito de sódio e preenchidos com AH plus sealer e guta-percha usando condensação vertical quente. Todas as amostras foram então colocadas em molde de acrílico e submetidas a envelhecimento térmico por 10.000 ciclos entre 5 e 55°C. As amostras foram fixadas em uma máquina de teste universal com o eixo longo das raízes posicionado a 20° para uma carga aplicada a uma velocidade de cruzeta de 1 mm/min usando indentador semiesférico de aço inoxidável (Ø = 3 mm) até que ocorresse a fratura para determinar a força de resistência à fratura em Newton. RESULTADOS: O teste de normalidade (Shapiro-Wilk) mostrou que os dados são normalmente distribuídos. O grupo II apresentou a maior resistência média à fratura, e o grupo VI foi o menos propenso a resistir à fratura. Não houve diferenças estatisticamente significativas entre os grupos testados (p-valor = 0,237). O grupo MOD apresentou um modo de fratura mais desfavorável em comparação com os outros grupos. CONCLUSÕES: Não houve diferença significativa na resistência à fratura entre as cavidades de acesso conservador e tradicional. A ausência de cristas marginais, como nas cavidades MOD, desempenhou um papel importante na diminuição da resistência à fratura dos dentes tratados endodonticamente.

Longitudinal bond strength of a universal adhesive and chemical dentin characterization under different acid etching protocols

Abstract Objective This study aimed to analyze the longitudinal bond strength of a universal adhesive and chemically characterize the dentin substrate under different acid etching protocols. Methodology Dentin samples were etched with polyacrylic acid 25% (PAA) for 10 seconds (n=3) and phosphoric acid 32% (PA) for 15 seconds (n=3) and analyzed by Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) before and after treatment. For collagen degradation, samples (n=12) were divided into 3 groups: PAA, PA, and Deionized water (control), and analyzed by the quantity of solubilized type I collagen C-terminal cross-linked telopeptides and solubilized C-terminal peptide in relation to total protein concentration (ICTPtp and CTXtp) and by their ultimate tensile strength (UTS). For the adhesive interface analysis, dentin samples (n=72) were divided into 3 groups: PAA, PA, and Self-etch (SE), and subdivided into 2 groups: 24 h (baseline) and 1 year. The following tests were performed: microtensile bond strength (μTBS) (n=48), scanning electron microscopy (SEM) (n=12), and nanoleakage (n=12). Results The FTIR of PAA showed lower reduction of the peaks in the phosphate group when compared to PA. For ICTPtp, PA showed a significantly higher value. For CTXtp, PA and PAA groups failed to statically differ from each other. UTS was significantly lower for PA. For μTBS, storage time significantly affected bond strength. The results were unaffected by the etching protocol. For SEM, after 1 year, PA had little evidence of degradation in the upper third of the adhesive interface in comparison to the other groups. Nanoleakage showed no considerable silver impregnation after 1 year in the SE group. Conclusion The use of PAA prior to a universal adhesive (when compared to PA) represents a less aggressive type of etching to dentin. However, self-etching still seems to be the best option for universal adhesive systems that have functional monomers in their composition.

Application of proanthocyanidin in the treatment and repair of deep caries / 口腔疾病防治

@#Proanthocyanidin (PA), as a kind of natural plant polyphenol, have a variety of biological functions, such as promoting remineralization, inducing collagen cross-linking, inhibiting protease activity and inhibiting bacteria. Therefore, PA could be broadly used in the clinical application of treatment and repair of deep caries in the future; for example, PA could promote dentin remineralization, improve resin-dentin bonding durability and improve the dentin acid erosion effect. This application potential of PA arises from several features, firstly, PA can not only promote dentin remineralization on its own or with other remineralizers but also exhibits antibacterial effects, which can inhibit acid production while reducing the formation of cariogenic pathogens and their biofilms. Based on the above features, PA can reduce the incidence of caries disease; thus, PA improves deep caries and long-term effects after treatment. In addition, PA added to adhesives or etch agents can improve the etching and bonding effect of dentin by inducing collagen cross-linking and inhibiting protease activity, thus achieving the ultimate goal of improving the bonding performance of deep caries. This paper summarizes recent progress of research on PA for the treatment and repair of deep caries, including the promotion of dentin remineralization and antibacterial activity as well as the improvement in dentin bonding and acid etching effect, to provide a more comprehensive reference for treating and restoring deep caries in clinical practice.

Bonding performance of universal adhesives with concomitant use of silanes to CAD/CAM blocks / Associação de adesivos universais com silanos na adesão em blocos de CAD/CAM

ABSTRACT Objective: This study assessed whether the use of a silane coupling agent influence the bond strength of two universal adhesives to ceramic or resin CAD/CAM blocks. Methods: Forty-eight samples were obtained from each resin nano-ceramic hybrid block (RCBs) and lithium disilicate ceramic blocks (LD). Samples were treated with silane with MDP (Monobond - S-MDP), silane without MDP (Prosil - PS), and no silane application (Control - Ctr) followed by universal adhesive with silane (UAS) and without silane (UA) (n=8). Three polyurethane tubes (1.5 mm of internal diameter) were positioned in each sample treated surface and filled with a dual cured resin cement. Bond strength was assessed by microshear bond strength test and failure analysis was performed for all samples. Results: For the RCBs, UAS presented the highest bond strength values (p=0.004). Silane application was not significant in bond strength values (p=0.444). For LD, silane application was significant in bond strength values (p<0.001), but the adhesive was not (p=0.066). Failure analysis showed high prevalence of adhesive failures for both substrates. Conclusion: A silane-containing universal adhesive promoted the best bond strength results to the resin nano-ceramic hybrid block. For bonding to a glass-ceramic CAD/CAM material, additional silane (without MDP) application presented the best results.

RESUMO Objetivo: Este estudo avaliou se o uso de um agente de união silano influencia na resistência de união de dois adesivos universais a blocos CAD/CAM cerâmicos ou resinosos. Métodos: Quarenta e oito amostras foram obtidas de blocos resinosos (RCBs) e cerâmicos de dissilicato de lítio (LD). As amostras foram tratadas com silano contendo: MDP (Monobond - S-MDP), silano sem MDP (Prosil - PS) ou sem aplicação de silano (Control - Ctr) seguido de adesivo universal com silano (UAS) ou sem silano (UA) (n=8). Três tubos de poliuretano (1,5 mm de diâmetro interno) foram posicionados em cada superfície tratada da amostra e preenchidos com um cimento resinoso dual. A resistência de união foi avaliada pelo teste de microcisalhamento e a análise de falha foi realizada para todas as amostras. Resultados: Para os RCBs, UAS apresentou os maiores valores de resistência de união (p=0,004). A aplicação de silano não foi significativa nos valores de resistência adesiva (p=0,444). Para LD, a aplicação de silano foi significativa nos valores de resistência de união (p<0,001), mas o adesivo não (p=0,066). A análise de falhas mostrou alta prevalência de falhas adesivas para ambos os substratos. Conclusão: O adesivo universal contendo silano promoveu os melhores valores de resistência adesiva ao bloco de resina. Para o bloco cerâmico, a aplicação adicional de silano (sem MDP) apresentou melhores resultados.

Acid-Base Resistant Zone in Teeth with the Direct Restoration Using Different Adhesive System Generations: A Systematic Review

ABSTRACT Objective: To find out what the acid-base resistant zone (ABRZ) is and the mechanism of its formation. Material and Methods: This systematic review was based on the search of laboratory studies in which selfetching adhesive systems were used. The electronic database PubMed was used for the search. The search began on August 2021 and ended on June 2022. We have analyzed the materials and methods of each research and entered them in the appropriate tables to give a clearer assessment of the obtained results. Results: This systematic review included 15 full-text articles published from 2011 to 2019. The ABRZ is formed on both dentine and enamel. On dentine, the ABRZ is formed only when using self-etching adhesive systems; on the enamel, on the contrary, the step of preliminary etch and rinse contributes to the formation of a thicker ABRZ. The functional monomer MDP and fluorine increase the thickness of the ABRZ and provide a hybrid layer /ABRZ boundary without defects and erosions. Conclusion: Self-etching adhesive systems ensure the creation of an ABRZ resistant to acid-base tests. This phenomenon can provide the resistance of tooth tissues to demineralization, and therefore increase their resistance to caries.

Survival rate and stability of surface-treated and non-surface-treated orthodontic mini-implants: a randomized clinical trial

ABSTRACT Objectives: This clinical trial was conducted to evaluate the stability and failure rate of surface-treated orthodontic mini-implants and determine whether they differ from those of non-surface-treated orthodontic mini-implants. Trial Design: Randomized clinical trial with a split-mouth study design. Setting: Department of Orthodontics, SRM Dental College, Chennai. Participants: Patients who required orthodontic mini-implants for anterior retraction in both arches. Methods: Self-drilling, tapered, titanium orthodontic mini-implants with and without surface treatment were placed in each patient following a split-mouth design. The maximum insertion and removal torques were measured for each implant using a digital torque driver. The failure rates were calculated for each type of mini-implant. Results: The mean maximum insertion torque was 17.9 ± 5.6 Ncm for surface-treated mini-implants and 16.4 ± 9.0 Ncm for non-surface-treated mini-implants. The mean maximum removal torque was 8.1 ± 2.9 Ncm for surface-treated mini-implants and 3.3 ± 1.9 Ncm for non-surface-treated mini-implants. Among the failed implants, 71.4% were non-surface-treated mini-implants and 28.6% were surface-treated mini-implants. Conclusion: The insertion torque and failure rate did not differ significantly between the groups, whereas the removal torque was significantly higher in the surface-treated group. Thus, surface treatment using sandblasting and acid etching may improve the secondary stability of self-drilling orthodontic mini-implants. Trial registration: The trial was registered in the Clinical Trials Registry, India (ICMR NIMS). Registration number: CTRI/2019/10/021718

RESUMO Objetivos: Este ensaio clínico foi conduzido para avaliar a estabilidade e a taxa de falha de mini-implantes ortodônticos com superfície tratada, e determinar se elas diferem das dos mini-implantes ortodônticos sem superfície tratada. Desenho do estudo: Ensaio clínico randomizado com desenho de boca dividida. Instituição: Department of Orthodontics, SRM Dental College, Chennai/India. Participantes: Pacientes que necessitavam de mini-implantes ortodônticos para retração anterior em ambas as arcadas. Métodos: Mini-implantes ortodônticos autoperfurantes, cônicos, de titânio com ou sem tratamento de superfície, foram colocados em cada paciente, seguindo um desenho de boca dividida. Os torques máximos de inserção e de remoção foram medidos para cada mini-implante, usando um torquímetro digital. As taxas de falha foram calculadas para cada tipo de mini-implante. Resultados: O valor médio do torque máximo de inserção foi de 17,9 ± 5,6 Ncm para mini-implantes com superfície tratada e 16,4 ± 9,0 Ncm para mini-implantes sem superfície tratada. O valor médio do torque máximo de remoção foi de 8,1 ± 2,9 Ncm para mini-implantes com superfície tratada e 3,3 ± 1,9 Ncm para mini-implantes sem superfície tratada. Entre os implantes que falharam, 71,4% eram mini-implantes sem superfície tratada e 28,6% eram mini-implantes com superfície tratada. Conclusão: O torque de inserção e a taxa de falha não diferiram significativamente entre os grupos; porém, o torque de remoção foi significativamente maior no grupo com superfície tratada. Assim, o tratamento de superfície com jateamento e condicionamento ácido pode melhorar a estabilidade secundária dos mini-implantes ortodônticos autoperfurantes. Registro do estudo: Esse estudo foi registrado no Clinical Trials Registry, Índia (ICMR NIMS). Número de registro: CTRI/2019/10/021718

Uso de adhesivo universal con pregrabado y autograbado en tejidos duros del diente / Use of universal adhesive with pre-etch and self etch strategies on hard tooth tissues

RESUMEN Introducción: Buscando satisfacer la demanda con procedimientos adhesivos más rápidos, menos sensibles a la técnica y facilidad de uso, se han desarrollado los adhesivos universales, que brindan al profesional la opción de seleccionar la estrategia de adhesión con diferentes modos de grabado, ya sea con grabado y enjuague, autograbado o grabado selectivo. Debido a la poca información existente, se han generado dudas sobre el rendimiento, propiedades y la aplicación de una técnica adhesiva adecuada sobre los tejidos dentales. Objetivo: Determinar el nivel de adhesión con el uso de adhesivos universales en modo de grabado y enjuague y autograbado. Métodos: Se realizó una revisión de la literatura, a través de la búsqueda electrónica en las bases de datos: SciELO, Scopus, PubMed, Springer y EBSCO. Inicialmente se seleccionaron por título y resumen, artículos duplicados se consideraron solo una vez, se incluyeron artículos de acceso libre y pagos, escritos en idioma español e inglés, publicados desde el año 2015, de los cuales 39 artículos fueron seleccionados para el estudio. Conclusiones: El uso de adhesivos universales sobre dentina presenta un nivel de adhesión mayor cuando se aplica en modo de autograbado. La aplicación activa del adhesivo universal en esmalte mejora la fuerza y resistencia de unión. El nivel de adhesión en el esmalte es mayor cuando se aplica en modo de grabado y enjuague. La resistencia inicial y por fatiga del adhesivo, no mejora con los tiempos prolongados del grabado ácido.

ABSTRACT Introduction: universal adhesives have been developed to satisfy the demand with faster adhesive procedures, less sensitive to the technique and ease of use, which offer the professional the option of selecting the adhesion strategy with different etching modes, either with etch-and-rinse, self-etch or selective etching ones. Doubts have been generated about the performance, properties and application of an adequate adhesive technique on dental tissues due to the little existing information. Objective: to determine the level of adhesion with the use of universal adhesives in etch-and-rinse and self-etch modes Methods: an electronic search of the literature was carried out in SciELO, Scopus, PubMed, Springer and EBSCO databases. Initially, articles were selected by title and abstract, duplicate ones were considered only once, free and paid access articles, written in Spanish and English and published since 2015 were included; 39 of them were selected for the study. Conclusions: the use of universal adhesives on dentin presents a higher level of adhesion when applied in self-etch mode. The active application of the universal adhesive improves the enamel bond strength. The level of adhesion on the enamel is higher when applied in etch-and-rinse. The initial fatigue resistance of the adhesive does not improve with prolonged acid etching times.

Influence of laser deproteinization of acid-etched dentin on marginal microleakage of class V composite restoration

Aim: Recent reports indicate that deproteinization of acid-etched dentin surface can extend penetration depth of adhesive agents. The main goal of the present research was to investigate the deproteinization effect of Nd:YAG and diode 940 lasers on acid-etched dentin and microleakage grade in class V composite restorations. Methods: 36 extracted human premolar teeth were selected to make standard buccal and lingual class V cavities. These samples were randomly split into three sub-groups: 1.Control group, in which composite was applied for restoration after etch and bonding process without deproteinization; 2.Nd:YAG laser group, in which the teeth were deproteinized with Nd:YAG laser after etching and painting internal surfaces of cavities with Van Geison stain and then composite restorations applied just as control group; 3.Diode laser group, in which the process was similar to Nd:YAG laser group, but instead, diode 940 laser was irradiated. The teeth were bisected into two equal longitudinal buccal and lingual halves. Marginal microleakage of samples was scored by using a stereomicroscope. Kruskal- Wallis, Mann-Whitney U and Fisher's statistical tests were employed for analysis of the obtained data. Results: A significant reduction in marginal microleakage was observed for both groups treated with laser (Nd:YAG and diode 940)compared to control (p=0.001 & p=0.047). There was no significant difference in marginal microleakage between Nd:YAG laser and diode 940groups (P = 0.333). Conclusion: Nd:YAG and diode 940 laser deproteinization of acid-etched dentin decreased the marginal microleakage of in-vitro class V resin composite restorations

Research progress on bracket bonding for dental fluorosis / 口腔疾病防治

@#Bonding of brackets to dental fluorosis has always been a difficult problem for clinicians. At present, clinical research has adopted several methods to facilitate bracket bonding, including prolonging etching time, enamel microabrasion, enamel ground, using adhesion promoter and laser etching. Prolonging etching time is suitable for mild-to-moderate dental fluorosis with easy chair-side operation; however, over-etching may cause severe tooth damage. Microabrasion can be applied to mild dental fluorosis while removing pigment deposition simultaneously; however, rubber dam protection is needed. Enamel ground can improve the bond strength to all kinds of dental fluorosis at the price of removing a relatively large amount of superficial enamel. Adhesion promoters might improve the bond strength of moderate to severe dental fluorosis; however, the current results conflict with one another. This needs further verification using larger-sample clinical trials. Laser etching has no effect on improving bond strength; however, it can remove pigment without destroying tooth enamel, which is worth further modification and enhancement.

Three-year evaluation of different adhesion strategies in non-carious cervical lesion restorations: a randomized clinical trial

Abstract: Objective: To evaluate non-carious cervical lesions (NCCLs) restored with different adhesion strategies. Methodology: This is a prospective, randomized, double-blind, split-mouth study. An adhesive restorative system (Single Bond Universal/Filtek Z350XT - SBU) was evaluated both without and with selective enamel conditioning (E-SBU), resin-modified glass-ionomer cements (Vitremer; RMGIC), and ethylenediaminetetraacetic acid pretreatment (EDTA; E-RMGIC). In total, 200 restorations, placed in 50 patients, were evaluated at baseline and at a 3-year follow-up using the modified United States Public Health Service (USPHS) criteria. Data were analyzed using the two-proportion equality test, multinomial logistic regression, Wilcoxon test, and Kaplan-Meier survival curves. Results: In total, 42 (84%) patients returned for the 3-year follow-up. SBU showed restoration losses statistically different from RMGIC. Retention was also statistically different in SBU between baseline and the 3-year follow-up. Marginal defects and surface texture were statistically significant for all groups in the period studied, except for the surface texture of SBU and the marginal integrity in E-RMGIC. We observed no statistically significant difference in wear, secondary caries, anatomical form, surface staining, and color over time. Recession degree was the only factor to influence retention rates. Cumulative survival (%) was 89, 98, 98, and 95.3, for SBU, SE-SBU, RMGIC, and E-RMGIC, respectively, without significant differences among them. There was a statistically significant difference between survival curves; however, multiple comparison procedures found no statistical differences. Conclusion: Selective enamel etching affected the retention of non-carious cervical restorations. Adhesion using EDTA and resin-modified glass-ionomer cements delayed marginal defects over time. The degree of gingival recession influenced retention rates. Resin composite restorations showed initial marginal defects, and ionomer restorations, reduced surface luster. EDTA pre-treatment followed by resin-modified glass-ionomer cements may be a promising adhesion strategy for NCCL restorations.

Contaminación de la dentina con diferentes técnicas de secado / Contamination of dentin with different drying techniques

El secado es uno de los factores clave para lograr una adhesión micromecánica exitosa en la dentina con los sistemas adhesivos de grabado independiente. El objetivo de este trabajo fue comparar los residuos remanentes luego de cuatro procedimientos diferentes de secado en preparaciones ex vivo en dentina. Se utilizaron cinco terceros molares ex-vivo, en cada uno de los cuales se realizó una preparación dentinaria en piso y paredes con al menos un socavado. Las unidades experimentales fueron almacenadas en solución fisiológica durante 7 días. Las distintas técnicas de secado (G1- G8) se aplicaron, luego de que las preparaciones fueron tratadas con gel de ácido fosfórico al 37% (Blue Gel etch Megadental) durante 15s y lavadas con jeringa y agua a presión durante 15s (Técnica de Grabado Ácido o TGA), de la siguiente manera: algodón común (Condesa) (G1), papel tisú (Achiss) cortado a mano (G2) y con tijera (G3), esponja (Sharpys) (G4), papel tisú (Simplicity) cortado a mano (G5)(AU)

Evaluation of Internal bleaching with 35% hydrogen peroxide in dentin conditioned with 37% phosphoric acid and 17% EDTA / Evaluación del blanqueamiento interno con peróxido de hidrógeno al 35% en dentina acondicionada con ácido fosfórico al 37% y EDTA al 17%

Introduction: This study aimed to evaluate the effect of dentin surface treatment with 37% phosphoric acid or 17% ethylenedia-minetetraacetic acid (EDTA) before Internal Bleaching with 35% hydrogen peroxide using the walking bleach technique. Material and Methods: This experimental in vitro study used 66 human premolars extracted for orthodontic reasons, which were debrided, endodontically prepared, and pigmented with chromogens derived from blood decomposition. The samples were randomly divided into three groups (n=22). Group A: bleaching agent without dentin conditioning; group B: bleaching agent in dentin conditioned with phosphoric acid 37%; group C: bleaching agent in dentin conditioned with 17% EDTA. 4 applications of bleaching agent were used with a separation of 4 days between each session. The initial color (baseline) and after each application was determined by spectrophotometry, recording the CIE L*a*b* values and the total color variation between the initial parameters and the different evaluation times. Results: Data were statistically analyzed with the Wilcoxon test. This showed statistically significant differences for the total variation of the color between the study groups, with the control group in no case inferior to the rest. Conclusion: The application of 37% phosphoric acid increased the effectiveness of the bleaching agent when compared to 17% EDTA. However, these did not increase the effectiveness compared to the application of the bleaching agent without a previous dentin surface treatment.

Introducción: El objetivo de este estudio fue evaluar el efecto del tratamiento de superficie dentinaria con ácido fosfórico al 37% o EDTA al 17% previo al blanqueamiento Interno con peróxido de hidrógeno al 35% por medio de la técnica Walking Bleach. Material y Métodos:Para este estudio experimental in vitro, se utilizaron 66 premolares humanos extraídos por indicación ortodóncica, los cuales fueron desbridados, preparados endodónticamente, y pigmentados con cromógenos derivados de la descomposición sanguínea. Las muestras fueron divididas aleatoriamente en 3 grupos (n=22). Grupo A: agente blanqueador sin acondicionamiento dentinario, grupo B: agente blanqueador en dentina acondicionada con ácido fosfórico 37% y grupo C: agente blanqueador en dentina acondicionada con EDTA 17%. Se utilizaron 4 aplicaciones de agente blanqueador con una separación de 4 días entre cada sesión. El color inicial (baseline) y tras cada aplicación fue determinado mediante espectrofotometría, registrando los valores CIE L*a*b* y la variación total de color entre los parámetros iniciales y los diferentes tiempos de evaluación. Resultados: Los datos fueron analizados estadísticamente con la prueba de Wilcoxon, arrojando diferencias estadísticamente significativas para la variación total del color entre los grupos de estudio, siendo en ningún caso el grupo control inferior al resto. Conclusión: La aplicación de ácido fosfórico al 37% aumenta la eficacia del agente blanqueador al compararlo con el EDTA 17%, sin embargo, no aumentan la eficacia respecto a la aplicación del agente blanqueador sin un tratamiento de superficie dentinaria previo.

Effects of quercetin on the dentin resistance to erosion / 中华口腔医学杂志

Objective@#To evaluate the effects of quercetin on dentin resistance to erosion and provide evidence-based recommendations for the prevention and therapy of dental erosion.@*Methods@#One hundred and twenty-eight dentin samples were prepared from 50 extracted human wisdom teeth (collected from Department of Oral Surgery, School and Hospital of Stomatology). Ninety-six samples were randomly divided into 8 groups using the following different soaking solutions: deionized water, ethanol (control groups), 12.300 mg/L sodium fluoride, 0.120 mg/L chlorhexidine, 0.183 mg/L epigallocatechin gallate (EGCG), and 0.075, 0.150 and 0.300 mg/L quercetin. In each group, twelve specimen was prepared. Before daily acid challenge, the samples were immersed in the respective solutions for 2 min, rinsed with deionized water, and immersed in artificial saliva for 2 h. The samples were then subjected to 4 cycles of in vitro acid challenges. This protocol was applied for 7 d. The surface microhardness (SMH) and surface profiles were measured before and after erosion using the surface microhardness tester and contact profilometry, respectively. The change in surface profiles and reduction in SMH were used to calculate the substance loss and reduction percentage of SMH (SMH%) respectively. Scanning electron microscope (SEM) images were taken to observe the surface morphology of the samples. Additionally, another thirty two samples were divided into 8 groups (n=4) as mentioned above. The specimens were treated with 10% phosphoric acid and desiccated, immersed in the respective solutions for 2 min, rinsed, and immersed in the artificial saliva at 37 ℃ for 7 d. The content of cross-linked carboxyterminal telopeptide of type Ⅰ collagen (ICTP) in the soaking solutions were measure quantitatively.@*Results@#Compared with the control groups, the application of chlorhexidine, quercetin, and EGCG were effective in preventing the surface softening and substance loss of human dentin after erosion. More specifically, the specimens treated with 0.300 mg/L quercetin exhibited the lowest SMH% [(8.75±4.95)%], the lowest surface substance loss [(2.26±1.16) μm], and the lowest contents of ICTP in the soaking solution [(5.72±0.88) ng], showing significant differences to the chlorhexidine and EGCG treated samples (P<0.05). No significant differences were found in the substance loss and ICTP contents in the three soaking solutions with different concentrations of quercetin(P>0.05). However, the specimens treated with 0.300 mg/L quercetin exhibited significantly lower SMH% than those treated with the other two concentrations of quercetin (P<0.05).@*Conclusions@#Within the limitations of the current study, immersion in the quercetin solution is effective in improving the dentin resistance to erosion by inhibiting the dentinal MMP. Among all the concentrations tested, 0.300 mg/L quercetin showed the best performance.

Shortening of etching time of the dentin in primary teeth restorations: a randomized clinical trial

Abstract The aim of this study was to investigate the influence of shortening of etching time for dentin on the restoration survival after selective carious tissue removal in primary molars. This two-arm randomized clinical trial included sixty-two subjects (5-8 year-old) and 100 primary molars presenting moderate dentin carious lesions on occlusal surface. The sample was randomly assigned into groups previously to adhesive application (Adper Single Bond 2; 3M ESPE): etching time recommended by manufacturer (15 s) or reduced (7 s). Resin composite (Filtek Bulk Fill Posterior Restorative; 3M ESPE) was inserted in a single increment for all restorations. Restorations were evaluated at 1, 6, 12, and 18 months using FDI criteria. Survival estimates for restorations' longevity were evaluated with Kaplan-Meier method. Multivariate Cox regression analysis with shared frailty was used to assess the factors associated with failures (p < 0.05). The etching time did not influence the restorations' survival (HR 0.35 95%CI 0.11-1.12; p = 0.06). Mean estimated time of survival was 17.6 months (95%CI, 17.2-17.9). The survival rates at the 18-month follow-up were 75.7% and 91.4% (AFR: 16.9% and 5.7%) when primary dentin was acid etched for 15 and 7 s, respectively (log-rank p = 0.06). In conclusion, the etching time for dentin did not influence the clinical behavior of adhesives restorations. However, there was a tendency for better clinical outcome when using etching time of 7 s.

Marginal filling and adhesive resistance of bulk fill resin applying 18% edta gel compared with 37% phosphoric acid gel in vitro dental conditioning / Sellado marginal y resistencia adhesiva de resina bulk fill aplicando gel de edta al 18% comparado con el gel de ácido fosfórico al 37% en el acondicionamiento dental in vitro

Objective. To evaluate the degree of marginal sealing and adhesive strength in Bulk-Fill resin by applying 18% EDTA gel compared to 37% phosphoric acid gel in dental conditioning. Materials and methods. The study was transversal, experimental comparative, and applied. The sample group consisted of 60 teeth with Class I cavities, which were later subjected to conditioning. This was carried out separately with phosphoric acid gel for 15 seconds, and 18% EDTA gel within two different time frames: 60 and 90 seconds. All samples were incubated at 37ºC for a period of 24 hours and thermocycled between 5 to 55ºC for 500 cycles. To assess microfiltration, they were immersed in methylene blue at 37ºC for 4 hours, and were later sectioned and observed through a stereomicroscope. In order to perform the traction, the conventional testing machine was used at a speed of 0.75mm/min until the screw with the resin detached. Results: Samples conditioned with 37% phosphoric acid showed a greater degree 1 microfiltration and a mean adhesive resistance of 7.97 MPa. The same number of microfiltration grades 1 and 2 was found when using EDTA gel for 60 seconds, with a mean tensile strength of 8.8 MPa. On the other hand, applying EDTA gel for 90 seconds showed mostly grade 1 microfiltrations, and to a lesser extent, grade 0 and 2, with a mean resistance of 9.2 MPa. Conclusion: There are no statistically significant differences regarding adhesive strength between the two gels; however, better marginal filling was observed when samples were conditioned with 18% EDTA gel for 90 seconds.

Objetivo. Evaluar el grado de sellado marginal y resistencia adhesiva en resina Bulk ­ Fill aplicando gel de EDTA al 18% en comparación al gel de ácido fosfórico al 37% en el acondicionamiento dental. Materiales y métodos. El tipo de estudio fue transversal, comparativo, de nivel aplicativo y diseño experimental. La muestra estuvo conformada por 60 dientes con cavidades clase I; se realizó el acondicionamiento con gel de ácido fosfórico, gel del EDTA al 18% en 60 segundos y 90 segundos. El total de las muestras fueron incubados a 37°C por 24 horas, se termocicló con 500 ciclos entre 5 a 55ºC. Para evaluar microfiltración, fueron sumergidos en azul de metileno a 37ºC por 4 horas, fueron seccionadas y observados al estereomicroscopio, para realizar la tracción se empleó la máquina de ensayos universales a una velocidad de 0.75mm/min hasta que se desprendiera el tornillo con la resina. Resultados. Las muestras acondicionadas con ácido fosfórico al 37% presenta mayor microfiltración grado 1 y el promedio de su resistencia adhesiva es de 7.97Mpa, la microfiltración obtenida con EDTA en 60 segundos presenta equidad entre grado 1 y 2; promedio de resistencia a la tracción de 8.8 Mpa y el EDTA 90 segundos presentó mayor microfiltración grado 1 y el resto 0 y 2; el promedio de resistencia fue 9.2 Mpa. Conclusión. No existen diferencias estadísticamente significativas al comparar los acondicionantes para la prueba de resistencia adhesiva, sin embargo se observó mejor sellado marginal cuando se acondicionó con gel de EDTA al 18 % por 90 segundos.

Influence of Application Method on Shear Bond Strength and Microleakage of Newly Developed 8th Generation Adhesive in Primary Teeth / 대한소아치과학회지

The purpose of this study was to evaluate the effect of application time and phosphoric acid etching of 8th generation adhesives containing functional monomer on adhesive performance in primary teeth.80 extracted non-carious human primary teeth were selected and divided into 8 groups based on 3 factors: (1) adhesive: G-Premio bond and Single bond universal; (2) application time: shortened time and manufacture's instruction; (3) acid etching mode: self-etching and total-etching. Shear bond strength was measured using a universal testing machine, and fractured surface were observed under scanning electron microscope. Microleakage was evaluated by dye penetration depth.G-Premio bond were not significant different in shear bond strength and microleakage depending on application time of adhesive and acid etching mode. In Single bond universal, shear bond strength of short application time was significantly lower than that of long adhesive application time (p = 0.014). Clinically applicable shear bond strength values (> 17 MPa) were identified in all groups.These results suggested that G-Premio bond be used clinically for a short application time without phosphoric acid etching.

Comparison of influence in enamel during acid etching etching between sodium hypochlorite and acohol dsinfection / 吉林大学学报(医学版)

Objective: To investigate the influence of sodium hypochlorite and alcohol disinfection in the enamel during acid etching, and to provide reference for the orthodontic treatment. Methods: Sixty extracted permanent teeth were selected and randomly divided into two groups (group A and group B), with 30 teeth in each group. The teeth in group A were pretreated with 5. 25% sodium hypochlorite and the teeth in group B were pretreated with 75% alcohol. After pretreatment, group Aand group B were randomly divided into three groups (groups A0 , A1, A2, B0, B1, and B2), with 10 teeth in each group and the teeth were etched with 37% phosphoric acid for 0, 15 and 30 s. Forty extracted deciduous teeth were selected and randomly divided into 2 groups (group C and D), with 20 teeth in each group. In group C, the teeth were pretreated with 5. 25% sodium hypochlorite; in group D, the teeth were pretreated with 75% alcohol. After pretreatment, group C and group D were randomly divided into two groups (groups C0 , C1, D0, and D1) with 10 teeth in each group, and the teeth were etched with 37% phosphoric acid for 0 and 30 s. The morphology of enamel was observed by scanning electron microscope (SEM) after the extracted teeth were cleaned with ultrasound; the pore diameters of enamel surface were detected and the shear strength of samples in each group was detected. Results: The differences in pore diameters between various groups were statistically significant (P < 0.01) . In the permanent teeth test group, the pore diameter in group A2 was the maximum (P < 0.01), the surface protein residues were less, and the enamel was fully exposed, and the shear strength was the highest (P < 0.01) . The pore diameter in group B1 was the minimum (P < 0.01), the surface protein residues were more, and the shear strength was the lowest (P < 0.01) . In the deciduous teeth test group, the pore diameter in group CI was the maximum (P < 0.01), the surface protein residues were less, and the shear strength was the highest (P < 0.01) . The pore diameter in group D1 was the minimum, and the surface protein residues were more, and the shear strength was the lowest (P < 0.01) . Conclusion: Compared with the traditional alcohol disinfection method, pretreatment of 5. 2 5 % sodium hypochlorite in tooth enamel for 30 s can significantly increase the surface roughness and cleanliness of enamel, and enhance the shear strength of orthodontic bracket.

Effect of two kinds of materials on the prevention of early erosive enamel wear / 中华口腔医学杂志

Objective@#To investigate the preventive effect of resin infiltration and adhesive on early erosive enamel wear.@*Methods@#Orthodontic reduction premolars collected from Central Laboratory of Nanjing Stomatological Hospital, Medical School of Nanjing University were used to prepare 70 specimens. Forty samples were divided into eight groups (n=5) and treated with different conditions (pH=1.6, 2.4, 3.2 or 4.0 hydrochloric acid solution, etching time was 30 or 60 s), and the conditions for obtaining early erosive enamel samples were selected. Based on this procedure, thirty early erosive enamel samples were made and divided into three groups: control group, resin infiltration group, and adhesive group. And the treatment of 30 days acid abrasion cycle was carried out. Confocal microscopy was used to measure the thickness changes of enamel or material before and after cycle.@*Results@#Early erosive enamel samples was obtained when pH was 4.0 and etching time was 60 s. After 30 days cycle, the wear of enamel was (29.71±6.72) μm in control group, (5.60±2.24) μm in resin infiltration group and (2.89±1.03) μm in adhesive group. In infiltration group and adhesive group, lower enamel was not affected by the cycle, and the material loss ratios of the infiltration resin group and adhesive group were 0.41±0.14 and 0.29±0.13, respectively. The ratio of material loss was not significantly different (P>0.05). But infiltration group lost (12.95±2.22) μm of enamel during the application of the material.@*Conclusions@#Resin infiltration and adhesive have the same short-term protective effect against early erosive enamel wear. Adhesive has less damage to enamel and better effect.