Effects of different degrees of acidity and concentration of bleaching agents on human enamel mineral content and surface morphology over time / Efeitos de diferentes graus de acidez e concentração de agentes clareadores no conteúdo mineral e morfologia superficial do esmalte humano ao longo do tempo

Objective: The aim of this study was to evaluate the effect of pH and concentration of bleaching agents on the mineral content and surface morphology of human dental enamel for 14 days. Material and Methods: Eighty human central incisors were randomly divided into 8 groups (n=10): G1-7.5% hydrogen peroxide/ pH=9.0; G2­9.5% hydrogen peroxide/pH=9.0; G3- 7.5% hydrogen peroxide/pH=7.0; G4-9.5% hydrogen peroxide/pH=7.0; G5-10% carbamide peroxide/ pH=5.0; G6-16% carbamide peroxide/pH=5.0; G7- 37% phosphoric acid 15s (positive control); G8-no treatment (negative control). The mineral analysis of the bleaching gel collected was assessed by ICP-AES and surface morphology was observed by SEM. Results: Friedman and Dunn's statistical test demonstrated significant differences among the proposed treatments (p0.01). However, the latter groups showed significantly higher values as compared to groups G1, G2, G3 and G4 (p<0.01). Conclusion: Alteration in enamel mineral content may not be influenced by concentration when bleaching agents with the same pH are compared. The most apparent alterations in mineral content and surface morphology may be noted when more acidic products are used. The daily mineral content measurement may not be influenced by repeated applications of bleaching agents. (AU)

Objetivo: Este estudo avaliou o efeito do pH e da concentração de agentes clareadores no conteúdo mineral e na morfologia da superfície do esmalte dental humano durante 14 dias. Material e Métodos: Oitenta incisivos centrais humanos foram aleatoriamente divididos em 8 grupos (n = 10): G1-peróxido de hidrogênio 7.5% /pH = 9.0; G2 - peróxido de hidrogênio 9.5%/pH = 9,0; G3 - peróxido de hidrogênio 7.5%/pH = 7,0; G4-de peróxido de hidrogênio 9.5% / pH = 7,0; G5 - Peróxido de carbamida 10% / pH = 5.0; G6 - peróxido de carbamida 16%/pH = 5.0; G7- ácido fosfórico 37% (controle positivo); G8 - sem tratamento (controle negativo). A análise mineral do gel clareador coletado foi avaliada por ICP-AES e a morfologia da superfície foi observada por MEV. Resultados: Os testes estatísticos de Friedman e Dunn demonstraram diferenças significativas entre os tratamentos propostos (p<0,01). Nenhuma diferença significativa foi encontrada entre os grupos tratados com peróxido de hidrogênio (G1, G2, G3 e G4) ou entre os grupos G5, G6 e G7 (p>0,01), no entanto, os estes grupos apresentaram valores significativamente maiores em relação aos grupos G1, G2, G3 e G4 (p <0,01). Conclusão: Alterações no conteúdo mineral do esmalte não foram influenciadas pela concentração dos agentes clareadores quando os mesmos pH são comparados. As alterações mais significativas no conteúdo mineral e na morfologia da superfície foram notadas quando clareadores mais ácidos foram utilizados. A mensuração diária do conteúdo mineral não foi influenciada por repetidas aplicações de agentes clareadores. (AU)

Bonding efficiency and durability: current possibilities.

Bonding plays a major role in dentistry nowadays. Dental adhesives are used in association with composites to solve many restorative issues. However, the wide variety of bonding agents currently available makes it difficult for clinicians to choose the best alternative in terms of material and technique, especially when different clinical situations are considered. Moreover, although bonding agents allow for a more conservative restorative approach, achieving a durable adhesive interface remains a matter of concern, and this mainly due to degradation of the bonding complex in the challenging oral environment. This review aims to present strategies that are being used or those still in development which may help to prevent degradation. It is fundamental that professionals are aware of these strategies to counteract degradation as much as possible. None of them are efficient to completely solve this problem, but they certainly represent reasonable alternatives to increase the lifetime of adhesive restorations.

Bonding efficiency and durability: current possibilities

Abstract Bonding plays a major role in dentistry nowadays. Dental adhesives are used in association with composites to solve many restorative issues. However, the wide variety of bonding agents currently available makes it difficult for clinicians to choose the best alternative in terms of material and technique, especially when different clinical situations are considered. Moreover, although bonding agents allow for a more conservative restorative approach, achieving a durable adhesive interface remains a matter of concern, and this mainly due to degradation of the bonding complex in the challenging oral environment. This review aims to present strategies that are being used or those still in development which may help to prevent degradation. It is fundamental that professionals are aware of these strategies to counteract degradation as much as possible. None of them are efficient to completely solve this problem, but they certainly represent reasonable alternatives to increase the lifetime of adhesive restorations.

Phosphorylated Pullulan Coating Enhances Titanium Implant Osseointegration in a Pig Model.

PURPOSE: To investigate the effect of coating a titanium implant surface with a phosphorylated exopolysaccharide, pullulan, on the peri-implant bone formation and implant osseointegration. MATERIALS AND METHODS: Implants were placed in the skull bone of 12 domestic pigs and healed for 1 or 3 months. Osseointegration of (un)coated implants was evaluated by quantitative histology (peri-implant bone fraction [BF] and bone-to-implant-contact [BIC]). The Wilcoxon-Mann-Whitney test with α = .05 was used to statistically compare BF and BIC of the coated and uncoated implants. RESULTS: Significantly more BF was observed surrounding pullulan-coated implants compared with uncoated implants (P < .05) and for both healing periods (P < .05). BIC was positively affected by the exopolysaccharide coating, with significantly more BIC after the 3-month healing period compared with the uncoated implant (P < .05). Furthermore, BIC remained stable over time for the coated implants, while it significantly decreased for the uncoated ones (P < .05). CONCLUSION: These findings reveal the capacity of functionalizing the titanium implant surface with phosphorylated pullulan to improve the mineralization of the implant-bone interface.

Dentin-smear remains at self-etch adhesive interface.

OBJECTIVE: The bonding potential of 'mild' self-etch adhesives may be compromised due to smear interference, as they may not dissolve/penetrate the smear layer effectively due to their relatively low acidity. We observed that the thickness of the dentin smear layer differed depending on the surface-preparation methodology used. METHODS: The interaction of an (ultra-)mild self-etch adhesive (Clearfil S3 Bond, Kuraray Noritake) with human dentin, prepared either using a medium-grit diamond bur ('thick', clinically relevant smear layer) or 600-grit SiC-paper ('thin' smear layer), or just fractured (smear-free), was evaluated using high-resolution transmission electron microscopy (TEM). Non-demineralized/demineralized 30-100nm interfacial cross-sections were prepared following common TEM-specimen processing and diamond-knife ultra-microtomy. RESULTS: The adhesive did not dissolve the bur-cut, nor the SiC-ground smear layer, but impregnated it. Within this 'resin-smear complex', hydroxyapatite was abundantly present. At fractured dentin, this complex was not present, while the actual layer of interaction of the adhesive was limited to about 100nm. Non-demineralized 'ultra-thin' (30-50nm) sections confirmed the interfacial ultra-structure to differ for the three surface-preparation methods. An electron dense band was consistently disclosed at the adhesive interface, most likely representing the documented chemical interaction of the functional monomer 10-MDP with Ca. SIGNIFICANCE: The dentin surface-preparation method significantly affects the nature of the smear layer and the interaction with the ultra-mild self-etch adhesive.

3D-microleakage assessment of adhesive interfaces: exploratory findings by µCT.

OBJECTIVES: To explore the feasibility of a 3D-microleakage protocol for the evaluation of various configurations of adhesive-tooth interfaces. METHODS: Three different kinds of specimens were prepared: (1) a Class-I composite restoration placed without any bonding to maximize gap formation at the interface; (2) a glass-fiber post cemented with a self-adhesive composite cement into a prepared root canal; and (3) inlay MOD composite restorations placed with either a 1-step self-adhesive or a 2-step etch-and-rinse composite cement. After silver-nitrate (AgNO3) infiltration, the specimens were scanned using a Skyscan 1172 X-ray microtomograph (µCT; Skyscan Bruker) at 100kV, 100µA and 7.8-9.5µm resolution. Projection images were reconstructed, after which maximum-intensity projections (MIPs) and 3D-volumetric renderings were produced. For the inlays, an additional conventional stereomicroscopic (SM) microleakage evaluation was accomplished after specimen sectioning. RESULTS: MIPs and 3D-renderings from specimens (1) and (2) revealed strongly varying microleakage patterns along the marginal gap/interface. For the specimens of setup (3), the high radiopacity of the 2-step composite cement hindered evaluation of the MIPs. MIP-microleakage patterns along the enamel margin of the restoration cemented with the 1-step composite cement corresponded well to the stereomicroscopic images. SIGNIFICANCE: The reported µCT-protocol revealed good sensitivity to detect AgNO3 infiltration at the adhesive-tooth interface when considerable microleakage was present. When microleakage was less apparent and spread in a more diffuse pattern, evaluation with µCT was less sensitive compared to stereomicroscopic evaluation.

Bone tissue response to implant surfaces functionalized with phosphate-containing polymers.

OBJECTIVES: Inorganic polyphosphates are said to stimulate the activity of osteoblast-like cells in vitro. The purpose of this study was to evaluate in vivo bone regeneration around implants treated with polyphosphoric acid (PPA) and phosphorylated pullulan (PPL). MATERIAL AND METHODS: Two types of implants with different surface roughness (R1: Sa ≈ 0.23 µm; R2: Sa ≈ 1.35 µm) were treated with three solutions (distilled water, 10%wt PPA, or 10%wt PPL) prior to implantation in both tibia of twelve female white rabbits. Each animal received six implants randomly positioned according to their surface roughness and treatment: R1 + water; R1 + PPA; R1 + PPL; R2 + water; R2 + PPA; R2 + PPL. Animals were sacrificed after 1 or 4 weeks, and samples were prepared for histological and histomorphometrical analysis. Bone regeneration areas were evaluated for bone-to-implant contact (BIC) and bone fraction (BF) in areas 100 and 500 µm remote from the implant surface. Data were statistically analyzed by means of Friedman and Wilcoxon matched-pair tests (P < 0.05). RESULTS: After 1 week, bone tissue was rarely formed in the regeneration areas. After 4 weeks, implants treated with PPA presented higher ratios of BIC (R1 = 52.3 ± 13.1; R2 = 54.6 ± 11.0) than the ones treated with water (R1 = 24.1 ± 15.1; R2 = 32.4 ± 13.0). On the other hand, around the implant surface (100 µm), PPL-treated implants induced higher BF (R1 = 78.3 ± 34.1; R2 = 71.2 ± 21.8) as compared with the water-treated ones (R1 = 46.1 ± 22.0; R2 = 49.6 ± 21.0). At 500 µm, however, no statistically significant differences in BF were found among the groups evaluated (P > 0.05). Surface roughness influenced neither BIC nor BF. CONCLUSIONS: Implant surface treatment with phosphate-containing polymers may positively influence osseointegration.

Bond durability of self-adhesive composite cements to dentine.

OBJECTIVES: Clinically, the most easy-to-use composite cements are the so-called self-adhesive composite cements (SAC's). Hardly any data is however today available on the long-term bonding effectiveness of such luting composites. The purpose of this study was to evaluate the bond durability of different composite cements used to lute feldspathic ceramic blocks onto dentine. METHODS: Four SAC's (Clearfil SA Cement, Kuraray; G-CEM, GC; SmartCem2, Dentsply; Unicem 3M ESPE), one 'self-etch' (Clearfil Esthetic Cement, Kuraray) and one 'etch-and-rinse' (Variolink ll, Ivoclar-Vivadent) multi-step composite cement were used to lute feldspathic ceramic blocks (Vita Mark II, Vita) onto dentine surfaces. Teeth were distributed randomly in 24 experimental groups according to two different surface-preparation techniques ('SMEAR-COVERED' versus 'SMEAR-FREE') and storage conditions ('IMMEDIATE' versus 'AGED'). Failure patterns were evaluated with a stereomicroscope, and afterwards imaged using Feg-SEM. Two additional specimens were processed for cement-dentine interfacial analysis using TEM. RESULTS: A linear mixed effects statistical model revealed significant differences for the variables 'composite cement', 'surface preparation' and 'ageing'. All self-adhesive composite cements, except Unicem (3M ESPE), did bond less favourably to fractured dentine. TEM revealed an ultra-structurally different interaction of the composite cements with 'SMEAR-COVERED' and 'SMEAR-FREE' dentine. CONCLUSION: All SAC's suffered most when luted to 'SMEAR-FREE' (fractured) dentine, fortunately of no clinical relevance and most likely due to enhanced water sorption through the open tubules. When luted to 'SMEAR-COVERED' dentine, all SACs appeared equally effective and durable as the 'etch-and-rinse' and 'self-etch' multi-step composite cements. Solely the SAC SmartCem2 (Dentsply) appeared clearly less favourable and consistent.

In vitro and in vivo investigation of the potential of amorphous microporous silica as a protein delivery vehicle.

Delivering growth factors (GFs) at bone/implant interface needs to be optimized to achieve faster osseointegration. Amorphous microporous silica (AMS) has a potential to be used as a carrier and delivery platform for GFs. In this work, adsorption (loading) and release (delivery) mechanism of a model protein, bovine serum albumin (BSA), from AMS was investigated in vitro as well as in vivo. In general, strong BSA adsorption to AMS was observed. The interaction was stronger at lower pH owing to favorable electrostatic interaction. In vitro evaluation of BSA release revealed a peculiar release profile, involving a burst release followed by a 6 h period without appreciable BSA release and a further slower release later. Experimental data supporting this observation are discussed. Apart from understanding protein/biomaterial (BSA/AMS) interaction, determination of in vivo protein release is an essential aspect of the evaluation of a protein delivery system. In this regard micropositron emission tomography (µ -PET) was used in an exploratory experiment to determine in vivo BSA release profile from AMS. Results suggest stronger in vivo retention of BSA when adsorbed on AMS. This study highlights the possible use of AMS as a controlled protein delivery platform which may facilitate osseointegration.

Potential smear layer interference with bonding of self-etching adhesives to dentin.

PURPOSE: To evaluate the effect of smear-layer interposition on the bonding effectiveness of self-etching adhesives with different etching potential. MATERIALS AND METHODS: Bur-cut dentin specimens were obtained from 25 human molars after preparation of the dentin surface with a medium-grit diamond bur (bur-cut). An additional 25 molars were fractured at the midcoronal dentin to create a smear-layer-free surface (smear-free dentin). The prepared teeth were assigned to 5 groups, according to the adhesive to be applied: a strong one-step self-etching adhesive (PLP, Adper Prompt L-Pop, 3M ESPE, pH = 0.8); two ultra-mild one-step self-etching adhesives (C3S, Clearfil Tri-S Bond, Kuraray, pH = 2.7; AEB, Adper Easy Bond, 3M ESPE; pH = 2.7 ); as the self-etching control, a mild two-step self-etching adhesive (CSE, Clearfil SE Bond, Kuraray, pH of primer = 1.9); and as the etch-and-rinse control, a three-step etch-and-rinse adhesive (OFL, Optibond FL, Kerr). After composite buildups were made, all specimens were stored in distilled water (24 h/37°C) prior to microtensile bond strength testing (µTBS). The failure mode was determined with a stereomicroscope at 50X magnification. Representative µTBS specimens were processed for analysis in a Feg-SEM. The Kruskal-Wallis test was performed to determine statistical differences (p < 0.05). RESULTS: Except for the strong one-step self-etching adhesive, all other self-etching adhesives (mild and ultramild) revealed a significantly lower bond strength to bur-cut dentin than to smear-free dentin. The etch-and-rinse adhesive presented the highest µTBS, which was not significantly different when bonded to bur-cut or smear-free dentin. Fracture analysis demonstrated a prevalence of adhesive failures for the self-etching adhesives, while OFL revealed more mixed failures. SEM revealed that smear debris remained part of the adhesive interfacial complex produced by the ultra-mild one-step self-etching adhesive C3S when applied on bur-cut dentin. CONCLUSION: Smear debris interferes with the interaction of mild and ultra-mild self-etching adhesives with dentin.

Bone tissue response to BMP-2 adsorbed on amorphous microporous silica implants.

AIM: To evaluate bone regeneration potential of bone morphogenetic protein-2 (BMP-2) adsorbed on amorphous microporous silica (AMS). MATERIALS & METHODS: Four implants [titanium as control (CTR); AMS-coated titanium (AMS), BMP-2 adsorbed on titanium (CTR+BMP) and AMS (AMS+BMP)] were implanted randomly in the tibiae of 20 New Zealand white rabbits. Bone specimens with implants were retrieved 2/4 weeks post implantation and analysed histologically and histomorphometrically. Bone fraction was measured in initial bone-free area (bone regeneration area, BRA) and in the area with initial bone-implant contact [bone adaptation area (BAA)] (BF(BRA) & BF(BAA) ). Bone-implant contact was measured in BRA (BIC(BRA) ). In vitro BMP-2 release profiles were determined to evaluate the impact of the carrier surface. Mixed models were used for statistical analysis. RESULTS: BMP-2 release profiles were different for CTR+BMP and AMS+BMP. BIC(BRA) and BF(BRA) were significantly increased after 4 weeks compared to 2 weeks for AMS, CTR+BMP and AMS+BMP. However, no differences between the implant types were observed within both healing periods. BF(BAA) for CTR+BMP was smaller than that for CTR and AMS+BMP after 4 weeks. Despite slower BMP-2 release, AMS+BMP did not stimulate bone regeneration. CTR+BMP caused bone resorption at the bone-implant interface. CONCLUSIONS: BMP-2 functionalized implant surfaces failed to stimulate bone regeneration and osseointegration.

Clinical effectiveness of a one-step self-etch adhesive in non-carious cervical lesions at 2 years.

A 2-year randomized, controlled prospective study evaluated the clinical effectiveness of a one-step self-etch adhesive and a "gold-standard" three-step etch-and-rinse adhesive in non-carious Class-V lesions. The null hypothesis tested was that the one-step self-etch adhesive does perform clinically equally well as the three-step etch-and-rinse adhesive. A total of 161 lesions in 26 patients were restored with Clearfil AP-X (Kuraray). The restorations were bonded either with the "all-in-one" adhesive Clearfil S3 Bond (Kuraray) or with the three-step etch-and-rinse adhesive Optibond FL (Kerr). The restorations were evaluated at baseline and after 6 months, 1 and 2 years, regarding their retention, marginal adapation, marginal discoloration, caries occurrence, preservation of tooth vitality and post-operative sensivity. Retention loss, severe marginal defects and/or discoloration that needed intervention (repair or replacement) and the occurrence of caries were considered as clinical failures. The recall rate at 2 years was 93.8%. Only one Clearfil S3 Bond restoration was lost at the 2-year recall. All other restorations were clinically acceptable. The number of restorations with defect-free margins decreased severely during the 2-year study period (to 6.7% and 25.3% for Clearfil S3 Bond and Optibond FL, respectively). The Clearfil S3 Bond restorations presented significantly more small marginal defects at the enamel side than the Optibond FL restorations (Clearfil S3 Bond: 93.3%; Optibond FL: 73.3%; p = 0.000). Superficial marginal discoloration increased in both groups (to 53.3% and 36% for Clearfil S3 Bond and Optibond FL, respectively) and was also more pronounced in the Clearfil S3 Bond group (p = 0.007). After 2 years, the simplified one-step self-etch adhesive Clearfil S3 Bond and the three-step etch-and-rinse adhesive Optibond FL were clinically equally successful, even though both adhesives were characterized by progressive degradation in marginal integrity. Clearfil S3 Bond exhibited more small enamel marginal defects and superficial marginal discolorations.

Bone tissue response to porous and functionalized titanium and silica based coatings.

BACKGROUND: Topography and presence of bio-mimetic coatings are known to improve osseointegration. The objective of this study was to evaluate the bone regeneration potential of porous and osteogenic coatings. METHODOLOGY: Six-implants [Control (CTR); porous titanium coatings (T1, T2); thickened titanium (Ti) dioxide layer (TiO(2)); Amorphous Microporous Silica (AMS) and Bio-active Glass (BAG)] were implanted randomly in tibiae of 20-New Zealand white rabbits. The animals were sacrificed after 2 or 4 weeks. The samples were analyzed histologically and histomorphometrically. In the initial bone-free areas (bone regeneration areas (BRAs)), the bone area fraction (BAF) was evaluated in the whole cavity (500 µm, BAF-500), in the implant vicinity (100 µm, BAF-100) and further away (100-500 µm, BAF-400) from the implant. Bone-to-implant contact (BIC-BAA) was measured in the areas where the implants were installed in contact to the host bone (bone adaptation areas (BAAs)) to understand and compare the bone adaptation. Mixed models were used for statistical analysis. PRINCIPAL FINDINGS: After 2 weeks, the differences in BAF-500 for different surfaces were not significant (p>0.05). After 4 weeks, a higher BAF-500 was observed for BAG than CTR. BAF-100 for AMS was higher than BAG and BAF-400 for BAG was higher than CTR and AMS. For T1 and AMS, the bone regeneration was faster in the 100-µm compared to the 400-µm zone. BIC-BAA for AMS and BAG was lower after 4 than 2 weeks. After 4 weeks, BIC-BAA for BAG was lower than AMS and CTR. CONCLUSIONS: BAG is highly osteogenic at a distance from the implant. The porous titanium coatings didn't stimulate bone regeneration but allowed bone growth into the pores. Although AMS didn't stimulate higher bone response, it has a potential of faster bone growth in the vicinity compared to further away from the surface. BIC-BAA data were inconclusive to understand the bone adaptation.

Avaliação da resistência à tração e do índice de remanescente de adesivo de duas marcas de bráquetes metálicos colados em pré-molares humanos com dois diferentes sistemas de adesão / Shear bond strength and adhesive remnant index evaluation of two different metallic brackets bonded in human pre molars with two different bonding systems

Introdução: Levando-se em conta que atualmente estão disponíveis aos ortodontistas diferentes materiais para colagem de acessórios ortodônticos e várias marcas comerciais de bráquetes, decidiu-se avaliar, por meio de ensaios mecânicos: 1) A capacidade de retenção, por meio de testes de tração, de bráquetes metálicos das marcas Ormco Orthodontics e Morelli Ortodontia; 2) A resistência adesiva de dois materiais para colagem: sistema adesivo ortodôntico Enlight (Resina Enlight com resina fluída Ortho Solo) e um sistema não específico para ortodontia, formado pela resina composta fotopolimerizável Charisma associada ao adesivo Single Bond; 3) Índice de Remanescente de Adesivo (IRA) presente nas superfícies dentárias após os testes de tração em microscopia ótica. Métodos: Foram utilizados sessenta primeiros pré-molares humanos superiores do lado direito, divididos aleatoriamente em quatro grupos de quinze dentes cada. Os testes de tração foram realizados em máquina de ensaios Instron. Resultados e Conclusão: De acordo com a metodologia empregada e após análise estatística através do programa GMC 2002 (Testes de Kruskal Wallis) e discussão dos resultados obtidos, pôde-se concluir que: os bráquetes Ormco Orthodontics colados com o sistema Enlight apresentaram os maiores valores de resistência à tração, seguidos pelos bráquetes Morelli Ortodontia colados com a mesma resina, bráquetes Ormco Orthodontics colados com a resina Charisma e, por último, bráquetes Morelli Ortodontia colados com resina Charisma. Em relação ao Índice de Remanescente de Adesivo, não houve diferença estatística entre os grupos analisados e a maior parte da resina ficou aderida ao esmalte dentário após as descolagens

Introduction: Taking into account that currently are available to orthodontists different systems for orthodontic bonding of accessories and various trademarks of brackets, we decided to evaluate, through mechanical tests: 1) The bond strength, through tensile tests, of two trademarks of metal brackets: Ormco Orthodontics (Glendora, CA) and Morelli Orthodontics (Sorocaba, SP), 2) The bond strength of two bonding systems: orthodontic adhesive Enlight (Ormco Orthodontics, Glendora, CA) and a system not specific to orthodontics, composed by the composite resin Charisma (Heraeus Kulzer) associated with the adhesive Single Bond (3M ESPE, Monrovia, USA), 3) Adhesive Remnant Index (ARI) in the tooth surfaces after the tensile tests in optical microscope. Methods: Sixty first human upper right premolars were used, all from the right side, which were divided into two groups of thirty teeth, one for each brand of bracket. Each of these has been divided into two groups, one for each composite resin, resulting in four groups of samples: Brackets Ormco Orthodontics (Glendora, CA) associated with Enlight and Ortho Solo (Ormco Orthodontics, Glendora, CA); brackets Ormco Orthodontics (Glendora, CA) associated with Charisma (Heraeus Kulzer) and adhesive Single Bond (3M ESPE); brackets Morelli Orthodontia (Sorocaba, SP) associated with Enlight and Ortho Solo (Ormco Orthodontics, Glendora, CA) and brackets Morelli Orthodontia (Sorocaba, SP) with Charisma (Heraeus Kulzer) and adhesive Single Bond (3M ESPE). The tests were performed in the Instron tensile testing machine. Results and Conclusion: According to the methodology employed and after statistical analysis using the program 2002 GMC (Kruskal Wallis tests) and discussion of the results, we could conclude that the Ormco Orthodontics brackets bonded with Enlight (Ormco Orthodontics) associated with Ortho Solo fluid resin (Ormco Orthodontics) had the highest values of tensile strength, followed by brackets Morelli Orthodontia bonded with the same resin, brackets Ormco Orthodontics bonded with Charisma resin (Heraeus Kulzer) associated with adhesive Single Bond (3M ESPE), and finally, brackets Morelli Orthodontia bonded with Charisma composite resin associated with Single Bond, which submitted the lowest values of tensile. For the Adhesive Remnant Index (ARI), there was no statistical difference between the groups analyzed and most of the composite resin was attached to the tooth enamel after the debonding

Current concepts and techniques for caries excavation and adhesion to residual dentin.

The advent of "Adhesive Dentistry" has simplified the guidelines for cavity preparation enormously. The design and extent of the current preparations are basically defined by the extent and shape of the caries lesion, potentially slightly extended by bevelling the cavity margins in order to meet the modern concept of minimally invasive dentistry. New caries excavation techniques have been introduced, such as the use of plastic and ceramic burs, improved caries-disclosing dyes, enzymatic caries-dissolving agents, caries-selective sono/air abrasion and laser ablation. They all aim to remove or help remove caries-infected tissue as selectively as possible, while being minimally invasive through maximum preservation of caries-affected tissue. Each technique entails a specific caries-removal endpoint and produces residual dentin substrates of different natures and thus different receptiveness for adhesive procedures. This paper reviews the newest developments in caries excavation techniques and their effect on the remaining dentin tissue with regard to its bonding receptiveness.

Dynamic versus static bond-strength testing of adhesive interfaces.

UNLABELLED: A static bond-strength test is often regarded as clinically less relevant, since such abrupt loading of the adhesive-tooth bond clinically never occurs. Therefore, dynamic fatigue testing is often claimed to better predict the clinical effectiveness of adhesives. OBJECTIVES: To measure the micro-tensile fatigue resistance (µTFR) of adhesives bonded to dentin, and to compare their µTFR to their micro-tensile bond strength (µTBS). METHODS: The bonding effectiveness (including fracture analysis) of three adhesives (OptiBond FL, Kerr: 3-step etch-and-rinse adhesive or 3-E&Ra; Clearfil SE, Kuraray: 2-step self-etch adhesive or 2-SEa; G-Bond, GC: 1-step self-etch adhesive or 1-SEa) was measured by means of both a dynamic µTFR and a static µTBS approach. Preparation and test set-up of the micro-specimens were identical for both tests. In fatigue, specimens were tested with a wide range of selected loads at 2Hz and at 10Hz until failure, or until 10(4) cycles were reached. At 2Hz, the µTFR was also measured after 3-month water storage. The µTFR was determined using a logistic regression model. Two-way ANOVA and Tukey HSD multiple comparisons test were used to determine statistical differences in µTBS. RESULTS: The 1-SEa recorded significantly lower values in µTFR at 10Hz and in µTBS than the 2-SEa and 3-E&Ra. The 1-SEa and the 2-SEa performed significantly lower in µTFR than the 3-E&Ra, when tested at 2Hz after 3-month water storage. Fatigue testing at 2Hz after 1-week water storage did not reveal any differences in µTFR between the three adhesives. SIGNIFICANCE: The 3-E&Ra performed best in terms of bonding effectiveness, irrespective of the experimental condition or test used. The µTBS test proved once more to be a reliable laboratory test in ranking contemporary adhesives on their bonding effectiveness.

Towards a better understanding of the adhesion mechanism of resin-modified glass-ionomers by bonding to differently prepared dentin.

OBJECTIVES: The purpose of this study was to evaluate the bonding effectiveness of a resin-modified glass-ionomer (RMGI) to differently prepared dentin and how this restorative material interacts with these distinct substrates. Also the potential adhesion-promoting role of a polyalkenoic-acid conditioner was assessed. METHODS: Forty-eight dentin surfaces were prepared from sound human molars and randomly distributed among 6 experimental groups. Fuji II LC (GC) was applied on bur-cut (100 µm diamond), fractured and Er:YAG laser-irradiated (200mJ, 10Hz, 31.4J/cm(2)) dentin with or without the beforehand application of the aqueous polyalkenoic-acid conditioner, Cavity Conditioner (GC). After 7 days of storage in water at 37 °C, specimens were prepared for microtensile bond strength testing (µTBS), as well as for TEM characterization of the resultant RMGI-dentin interface. Statistical analysis of the µTBS results was performed using ANOVA and Tukey's test (p<0.05). RESULTS: The use of conditioner resulted in a significantly higher bond strength only when dentin was prepared by diamond bur (p<0.05). Laser irradiation induced micro-cracks on the dentin surface and led to the lowest bond strength, irrespective of the use of conditioner (p<0.05). Fuji II LC was able to partially demineralise (up to 2.0µm) and infiltrate bur-cut and fractured dentin, but no evident interaction was observed at the interface between the RMGI and laser-irradiated dentin. CONCLUSIONS: Laser-induced surface modifications impaired the interaction of the RMGI with dentin, thereby negatively influencing its bonding effectiveness. The use of a polyalkenoic-acid conditioner remains crucial for the RMGI to bond effectively to bur-cut dentin.

Apatite formation on bioactive calcium-silicate cements for dentistry affects surface topography and human marrow stromal cells proliferation.

The effect of ageing in phosphate-containing solution of bioactive calcium-silicate cements on the chemistry, morphology and topography of the surface, as well as on in vitro human marrow stromal cells viability and proliferation was investigated. A calcium-silicate cement (wTC) mainly based on dicalcium-silicate and tricalcium-silicate was prepared. Alpha-TCP was added to wTC to obtain wTC-TCP. Bismuth oxide was inserted in wTC to prepare a radiopaque cement (wTC-Bi). A commercial calcium-silicate cement (ProRoot MTA) was tested as control. Cement disks were aged in DPBS for 5 h ('fresh samples'), 14 and 28 days, and analyzed by ESEM/EDX, SEM/EDX, ATR-FTIR, micro-Raman techniques and scanning white-light interferometry. Proliferation, LDH release, ALP activity and collagen production of human marrow stromal cells (MSC) seeded for 1-28 days on the cements were evaluated. Fresh samples exposed a surface mainly composed of calcium-silicate hydrates CSH (from the hydration of belite and alite), calcium hydroxide, calcium carbonate, and ettringite. Apatite nano-spherulites rapidly precipitated on cement surfaces within 5 h. On wTC-TCP the Ca-P deposits appeared thicker than on the other cements. Aged cements showed an irregular porous calcium-phosphate (Ca-P) coating, formed by aggregated apatite spherulites with interspersed calcite crystals. All the experimental cements exerted no acute toxicity in the cell assay system and allowed cell growth. Using biochemical results, the scores were: fresh cements>aged cements for cell proliferation and ALP activity (except for wTC-Bi), whereas fresh cements

TEM characterization of a silorane composite bonded to enamel/dentin.

OBJECTIVES: The low-shrinking composite composed of combined siloxane-oxirane technology (Filtek Silorane, 3M ESPE, Seefeld, Germany) required the development of a specific adhesive (Silorane System Adhesive, 3M ESPE), in particular because of the high hydrophobicity of the silorane composite. The purpose of this study was to characterize the interfacial ultra-structure at enamel and dentin using transmission electron microscopy (TEM). METHODS: Non-demineralized/demineralized 70-90 nm sections were prepared following common TEM specimen processing procedures. RESULTS: TEM revealed a typical twofold build-up of the adhesive resin, resulting in a total adhesive layer thickness of 10-20 microm. At bur-cut enamel, a tight interface without distinct dissolution of hydroxyapatite was observed. At bur-cut dentin, a relatively thin hybrid layer of maximum a few hundreds of nanometer was formed without clear surface demineralization. No clear resin tags were formed. At fractured dentin, the interaction appeared very superficial (100-200 nm). Distinct resin tags were formed due to the absence of smear plugs. Silver-nitrate infiltration showed a varying pattern of both spot- and cluster-like appearance of nano-leakage. Traces of Ag were typically detected along some part of the enamel-adhesive interface and/or between the two adhesive resin layers. Substantially more Ag-infiltration was observed along the dentin-adhesive interface of bur-cut dentin, as compared to that of fractured dentin. CONCLUSIONS: The nano-interaction of Silorane System Adhesive should be attributed to its relatively high pH of 2.7. The obtained tight interface at both enamel and dentin indicates that the two-step self-etch adhesive effectively bridged the hydrophilic tooth substrate with the hydrophobic silorane composite.

Immediate bonding effectiveness of contemporary composite cements to dentin.

The objective of this study was to compare the one-week bonding effectiveness of nine contemporary composite cements used to lute ceramic to dentin and to determine an appropriate processing method for pretesting failures. The microtensile bond strengths (µTBS) of different luting agents including five self-adhesive cements (Unicem, 3 M ESPE; Maxcem, Kerr; Monocem, Shofu; G-Cem, GC; and Multilink Sprint, Ivoclar-Vivadent), two self-etch cements (Panavia F2.0 and Clearfil Esthetic Cement, Kuraray), and two etch-and-rinse cements (Calibra, Dentsply, and Variolink II, Ivoclar-Vivadent) were measured using a standardized protocol. As control, a two-step self-etch adhesive combined with a restorative composite (Clearfil SE+Clearfil APX, Kuraray) were included as luting material. Depending on the processing of the pretesting failures, two groups of cements could be distinguished: (1) those with low bond strength and many pretesting failures and (2) those with relatively high bond strength and few pretesting failures. Nevertheless, the control luting procedure involving a self-etch adhesive combined with a restorative composite presented with a significantly higher µTBS. The µTBS was clearly product-dependent rather than being dependent on the actual adhesive approach. Fracture analysis indicated that failure usually occurred at the dentin-cement interface especially for the cements with low bond strength and many pretesting failures. Depending on the cement system, an adequate immediate ceramic-to-dentin bond strength can be obtained, even with self-adhesive cements that do not use a separate dental adhesive. Yet, the self-etch adhesive Clearfil SE combined with the restorative composite revealed a superior bonding performance and should therefore be preferred in clinical situations where the restoration transmits light sufficiently.