Using artificial intelligence to predict the final color of leucite-reinforced ceramic restorations.

OBJECTIVES: The aim of this study was to evaluate the accuracy of machine learning regression models in predicting the final color of leucite-reinforced glass CAD/CAM ceramic veneer restorations based on substrate shade, ceramic shade, thickness and translucency. METHODS: Leucite-reinforced glass ceramics in four different shades were sectioned in thicknesses of 0.3, 0.5, 0.7, and 1.2 mm. The CIELab coordinates of each specimen were obtained over four different backgrounds (black, white, A1, and A3) interposed with an experimental translucent resin cement using a calibrated spectrophotometer. The color change (CIEDE2000) values, as well as all the CIELab values for each one of the experimental groups, were submitted to 28 different regression models. Each regression model was adjusted according to the weights of each dependent variable to achieve the best-fitting model. RESULTS: Different substrates, ceramic shades, and thicknesses influenced the L, a, and b of the final restoration. Of all variables, the substrate influenced the final ceramic shade most, followed by the ceramic thickness and the L, a, and b of the ceramic. The decision tree regression model had the lowest mean absolute error and highest accuracy to predict the shade of the ceramic restoration according to the substrate shade, ceramic shade and thickness. CLINICAL SIGNIFICANCE: The machine learning regression model developed in the study can help clinicians predict the final color of the ceramic veneers made with leucite-reinforced glass CAD/CAM ceramic HT and LT when cemented with translucent cements, based on the color of the substrate and ceramic thicknesses.

Microshear bond strength of resin cement to glass-ceramics after intaglio surface staining.

STATEMENT OF PROBLEM: Applying stains to the intaglio surface of computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic ceramic restorations has been proposed as an option to help mask darkened substrates. However, little is known about the effects of this procedure on the adhesion between the resin cement and the ceramic. PURPOSE: The purpose of this in vitro study was to evaluate the effect of intaglio surface staining on the microshear bond strength between 2 CAD-CAM ceramics and a resin cement. MATERIAL AND METHODS: Lithium disilicate (Gmax) and leucite-reinforced (Gpress) ceramic blocks were sectioned, crystalized when indicated, and polished. They received either none, 1, or 2 layers of ceramic stains and a glaze liquid mixture followed by a firing cycle. The surfaces of groups Gmax0, Gmax1, and Gmax2 were etched with 9% hydrofluoric acid etching (HF) for 20 seconds, and those of groups Gpress0 and Gpress1 were etched for 60 seconds. After rinsing and drying, a ceramic primer was applied and air-dried. Resin cement rods (n=24 per group) were built from a silicone mold. Specimens were stored in distilled water for 24 hours before microshear bond testing. Failure mode was observed under a digital microscope. Data were analyzed by using the Kruskal-Wallis and Mann-Whitney nonparametric tests (α=.05). RESULTS: Intaglio staining negatively affected the microshear bond strength for both ceramics. A significant difference was observed between Gmax1 (3.5 ±1.73 MPa) and Gmax2 (3.7 ±2.1 MPa) when compared with Gmax0 (14.2 ±4.4 MPa) and also between GPress0 (25.7 ±5.1 MPa) and Gpress1 (1.8 ±2.7 MPa). No difference was observed between 1 and 2 stain layers for Gmax. Most failures were adhesive for Gmax0, mixed for Gpress, and cohesive within the stain layer for experimental groups. CONCLUSIONS: Intaglio surface staining with a stain and glaze mixture caused a significant reduction in bond strength between resin cement and both ceramics tested.

Progression of non-carious cervical lesions: 3D morphological analysis.

OBJECTIVES: This longitudinal study aimed to investigate morphologically and quantitatively the progression of non-carious cervical lesions (NCCLs) using a confocal laser scanning microscope (CLSM) and replica models. MATERIALS AND METHODS: The samples examined comprised sets of replicas annually obtained from 83 lesions in 16 participants over 3 to 5 years. All lesions were visually categorized as wedge-shaped, saucer-shaped, or mixed-shaped lesions. CLSM images of the replicas were analyzed in terms of axial depth, occlusogingival width (height) in the buccolingual cross-section, and estimated volume using a custom code of the image analysis software to estimate the progression of the NCCLs over time. The morphological characteristics of the NCCLs were also objectively divided into three groups according to the depth to height ratio (D/H ratio). Fisher's exact test and the Cochran-Armitage trend test were used for statistical analysis. RESULTS: Saucer-shaped lesions progressed mainly in height, whereas wedge-shaped lesions increased both in height and depth. Annual progression in depth and volume significantly increased as the D/H ratio increased. More than half of the NCCLs with a small D/H ratio progressed 50 µm or more in height, whereas none of them progressed more than 50 µm in depth. Annual progression in depth significantly increased as the lesion depth at baseline increased. CONCLUSIONS: Progression patterns significantly differed between NCCLs of different shapes. Most NCCLs progressed slowly in depth regardless of their shape. Moreover, NCCLs may progress through active and inactive stages.

Moist vs over-dried etched dentin: FE-SEM/TEM and bond strength evaluation of resin-dentin interfaces produced by universal adhesives.

OBJECTIVE: To evaluate the influence of the degree of dentin moisture on interfacial ultramorphology and bond strength (µTBS) of universal adhesives. MATERIALS AND METHODS: Futurabond U (FBU), Scotchbond Universal (SBU), Adhese Universal (ADU), and Prime&Bond active (PBA) were used. After acid-etching, moist or over-dried dentin surfaces were tested. Teeth were restored for scanning and transmission electron microscopy (n = 3) and µTBS evaluation (n = 5). µTBS results were analyzed by two-way ANOVA and Tukey. RESULTS: For moist dentin, a well-formed hybrid layer (HL) was observed. However, when applied to over-dried dentin, remarkable differences were observed. Defects, gaps, and reduced HL thickness were observed mainly for ADU and FBU. When applied to wet dentin, µTBS values were similar for all adhesives, except for FBU, which was significantly lower. When applied to over-dried dentin, PBA presented the highest µTBS values, followed by SBU, ADU, and FBU. ADU presented significantly lower µTBS when applied to over-dried dentin. CONCLUSION: PBA, SBU, and FBU µTBS values were not sensitive to the degree of moisture. Even though application to over-dried dentin revealed defects, gaps and reduced HL thickness for SBU, ADU, and FBU, µTBS analysis only revealed a significant reduction for ADU. CLINICAL SIGNIFICANCE: Universal adhesives can be applied in either self-etching or etch-and-rinse mode. However, clinicians are not aware which universal adhesives should be strictly applied on a moist dentin for bonding in the etch-and-rinse mode.

Cytotoxicity of universal, self-etching and etch-and-rinse adhesive systems according to the polymerization time.

This in vitro study evaluated in fibroblast cultures the direct cytotoxicity of universal, self-etching and etch-and-rinse adhesive systems according to the polymerization time. Paper discs were impregnated with adhesives and light-cured (10, 20 or 40 s). The discs were then immersed in culture medium to obtain the eluates for the experimental groups (A1-Single Bond 2; A2-Scotchbond Multi-purpose; A3-Clearfil SE Bond; A4 Scotchbond Universal). As a negative control, paper discs were immersed in culture medium only. After 24 h or 7 days, the eluate obtained was applied on fibroblast culture. Cell viability, cell morphology, membrane damage and the presence of residual monomers were evaluated by MTT assay, SEM, flow cytometry and high-performance liquid chromatography (HPLC), respectively. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (=0.05). All adhesive systems significantly reduced 33-51% cell metabolism when compared to the negative control, regardless of polymerization time, storage period and adhesive system. Moreover, the adhesives caused intense morphological alterations and cell membrane damage. Toxicity was directly related to the presence of residual monomers in the eluates. Residual monomers and additional components are capable of reducing mitochondrial activity, causing morphological alterations and disruption of the cell membrane in fibroblasts, regardless of the polymerization time. This study highlights that despite the more complex composition of the universal adhesive system, its biological response was not more toxic when compared with other systems, even when the shortest polymerization time was tested in cell culture.

Cytotoxicity of Universal, Self-Etching and Etch-and-Rinse Adhesive Systems According to the Polymerization Time

This in vitro study evaluated in fibroblast cultures the direct cytotoxicity of universal, self-etching and etch-and-rinse adhesive systems according to the polymerization time. Paper discs were impregnated with adhesives and light-cured (10, 20 or 40 s). The discs were then immersed in culture medium to obtain the eluates for the experimental groups (A1-Single Bond 2; A2-Scotchbond Multi-purpose; A3-Clearfil SE Bond; A4 Scotchbond Universal). As a negative control, paper discs were immersed in culture medium only. After 24 h or 7 days, the eluate obtained was applied on fibroblast culture. Cell viability, cell morphology, membrane damage and the presence of residual monomers were evaluated by MTT assay, SEM, flow cytometry and high-performance liquid chromatography (HPLC), respectively. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (=0.05). All adhesive systems significantly reduced 33-51% cell metabolism when compared to the negative control, regardless of polymerization time, storage period and adhesive system. Moreover, the adhesives caused intense morphological alterations and cell membrane damage. Toxicity was directly related to the presence of residual monomers in the eluates. Residual monomers and additional components are capable of reducing mitochondrial activity, causing morphological alterations and disruption of the cell membrane in fibroblasts, regardless of the polymerization time. This study highlights that despite the more complex composition of the universal adhesive system, its biological response was not more toxic when compared with other systems, even when the shortest polymerization time was tested in cell culture.

O presente estudo in vitro avaliou a citotoxicidade direta dos sistemas adesivos convencionais, autocondicionantes e universais de acordo com o tempo de polimerização em cultura de fibroblastos. Discos de papel foram impregnados com adesivos e fotoativados (10, 20 e 40 s). Os discos foram posteriormente imersos em meio de cultura para obtenção dos eluatos dos grupos experimentais (A1-Single Bond 2; A2-Scotchbond Multi-purpose; A3-Clearfil SE Bond; A4 Scotchbond Universal). Para o controle negativo, os discos de papel foram imersos somente em meio de cultura. Após 24 h ou 7 dias, o eluato obtido foi aplicado na cultura de fibroblastos. O metabolismo celular, morfologia, dano de membrana e presença de monômeros residuais foram avaliados por teste de MTT, MEV, citometria de fluxo e HPLC, respectivamente. Os dados foram analisados estatisticamente por Kruskal-Wallis e Mann-Whitney. Todos os sistemas adesivos reduziram significativamente o metabolismo celular em 33 a 51% quando comparados ao grupo controle, independente do tempo de polimerização, período de armazenamento e tipo de sistema adesivo. O eluato do adesivos causou ainda intensas alterações morfológicas e danos à membrana celular. A toxicidade foi diretamente relacionada à presença de monômeros residuais nos eluatos experimentais. Monômeros residuais e componentes adicionais dos sistemas adesivos foram capazes de reduzir a atividade mitocondrial, causar alterações morfológicas e danos à membrana citoplasmática de fibroblastos, independente do tempo de polimerização. Esse estudo evidencia que apesar de uma composição mais complexa do sistema adesivo universal, sua resposta biológica não apresentou maior toxicidade quando comparado aos demais sistemas, mesmo no menor tempo de polimerização quando testados em cultura celular.

One-year water sorption and solubility of "all-in-one" adhesives.

The aim of this study was to evaluate the water sorption and solubility of different adhesives. Adper Easy Bond, Adper Single Bond Plus, Bond Force, Clearfil SE Bond (bonding resin only), and Xeno IV were the materials evaluated. Ten disks of each adhesive were made in Teflon molds and evaporation of any volatile components was allowed. The disks were weighed daily in an analytical balance until a constant mass was obtained (m1). Disks were then immersed in water for 12 months when their wet weight was recorded (m2). The disks were again weighed daily until a constant mass was obtained and the final weight recorded (m3). Water sorption and solubility (percentages) were calculated using the recorded mass values. Kruskal-Wallis tests were used to compare the average water sorption and solubility among the different adhesives. Mann-Whitney tests with a Bonferroni correction were used to determine the pairwise differences between adhesives in water sorption and solubility. The level of significance was set at 0.05. Water sorption and solubility were significantly different among the groups (p<0.05). Pairwise comparisons showed no significant differences (p>0.05) between Adper Single Bond Plus and Bond Force, or between Clearfil SE Bond and Xeno IV in either water sorption or solubility. Xeno IV did not differ from Adper Easy Bond in water sorption (p>0.05). Water sorption and solubility of all-in-one adhesives increased with time, and the rates of increase were composition-dependent. The results suggest that monomers other than HEMA contribute to water sorption and solubility of adhesive systems from different categories.

Effect of dentin biomodification using naturally derived collagen cross-linkers: one-year bond strength study.

Purpose. This study investigated the long-term resin-dentin bond strength of dentin biomodified by proanthocyanidin-rich (PA) agents. Materials and Methods. Forty molars had their coronal dentin exposed, etched, and treated for 10 minutes with 6.5% grape seed extract (GSE), 6.5% cocoa seed extract ethanol-water (CSE-ET), 6.5% cocoa seed extract acetone-water (CSE-AC), and distilled water (CO). Samples were restored either with One-Step Plus (OS) or Adper Single-Bond Plus (SB). Bond strength test was performed immediately or after 3, 6, and 12 months. Results. Higher µ TBS were observed for GSE immediately (SB- 62.9 MPa; OS- 51.9 MPa) when compared to CSE-ET (SB- 56.95 MPa; OS- 60.28 MPa), CSE-AC (SB- 49.97 MPa; OS- 54.44 MPa), and CO (SB- 52.0 MPa; OS- 44.0 MPa) (P < 0.05). CSE outcomes were adhesive system and solvent dependant. After 12 months storage SB results showed no difference among treatment types (GSE- 57.15 MPa; CSE/ET- 54.04 MPa; CSE/AC- 48.22 MPa; CO- 51.68 MPa; P = 0.347),while OS results where treatment dependent (GSE- 42.62 MPa; CSE/ET- 44.06 MPa; CSE/AC- 41.30 MPa; CO- 36.85 MPa; P = 0.036). Conclusions. GSE and CSE-ET agents provided enhanced immediate adhesion and stabilization to demineralized dentin after long-term storage, depending on adhesive system.

One-Year Water Sorption and Solubility of All-in-One Adhesives

The aim of this study was to evaluate the water sorption and solubility of different adhesives. Adper Easy Bond, Adper Single Bond Plus, Bond Force, Clearfil SE Bond (bonding resin only), and Xeno IV were the materials evaluated. Ten disks of each adhesive were made in Teflon molds and evaporation of any volatile components was allowed. The disks were weighed daily in an analytical balance until a constant mass was obtained (m1). Disks were then immersed in water for 12 months when their wet weight was recorded (m2). The disks were again weighed daily until a constant mass was obtained and the final weight recorded (m3). Water sorption and solubility (percentages) were calculated using the recorded mass values. Kruskal-Wallis tests were used to compare the average water sorption and solubility among the different adhesives. Mann-Whitney tests with a Bonferroni correction were used to determine the pairwise differences between adhesives in water sorption and solubility. The level of significance was set at 0.05. Water sorption and solubility were significantly different among the groups (p<0.05). Pairwise comparisons showed no significant differences (p>0.05) between Adper Single Bond Plus and Bond Force, or between Clearfil SE Bond and Xeno IV in either water sorption or solubility. Xeno IV did not differ from Adper Easy Bond in water sorption (p>0.05). Water sorption and solubility of all-in-one adhesives increased with time, and the rates of increase were composition-dependent. The results suggest that monomers other than HEMA contribute to water sorption and solubility of adhesive systems from different categories.

O objetivo deste estudo foi avaliar a absorção de água e a solubilidade de diferentes sistemas adesivos: Adper Easy Bond, Adper Single Bond Plus, Bond Force, Clearfil SE Bond (apenas a resina adesiva) e Xeno IV. Foram fabricados 10 discos de cada material em moldes de Teflon e foi permitida a evaporação de todos os componentes voláteis. Os discos foram pesados diariamente em balança analítica até atingir massa seca constante (m1). Após esta mensuração, os discos foram imersos em água por 12 meses e seu peso úmido foi anotado (m2). Os discos foram novamente pesados diariamente até obter-se massa constante (m3). As percentagens de absorção de água e solubilidade foram calculadas utilizando os valores de massa registrados. A comparação das médias de absorção de água e solubilidade entre os diversos adesivos foi feita com o teste Kruskal-Wallis. As diferenças de absorção de água e solubilidade entre os pares de adesivos foram determinadas pelo testes Mann-Whitney com correção de Bonferroni. O nível de significância adotado foi de 0,05. Absorção de água e solubilidade apresentaram diferenças estatisticamente significantes entre os grupos (p<0,05). As comparações pareadas dos adesivos não mostraram diferenças significantes (p>0,05) entre Adper Single Bond Plus e Bond Force nem entre Clearfil SE Bond e Xeno IV para absorção de água e solubilidade. Xeno IV apresentou diferença significante do Adper Easy Bond quanto à absorção de água (p>0,05). A absorção de água e solubilidade dos adesivos “all-in-one” aumentaram com o tempo e as taxas de aumento mostraram-se dependentes da composição do material. Os resultados sugerem que outros monômeros além do HEMA contribuem para a absorção de água e solubilidade dos diversos sistemas de adesivos.

Two-year bond strengths of "all-in-one" adhesives to dentine.

OBJECTIVES: To test the long-term in vitro bonding performance of "all-in-one" self-etch adhesives to dentine. METHODS: Adper Prompt (3M ESPE), Bond Force (Tokuyama), Brush & Bond (Parkell), iBond Self Etch (Heraeus Kulzer), OptiBond All-In-One (Kerr), and Xeno IV (Dentsply Caulk) were tested. The two-step self-etch adhesive Clearfil SE Bond (Kuraray) served as the control. Extracted human teeth were assigned to groups after creation of smear layer on occlusal dentine. Adhesives were applied according to manufacturers' instructions, and resin composite (Filtek Z250, 3M ESPE) build-ups were placed. The bonded specimens were sectioned into beams after 24h of storage in water. Microtensile bond strengths (µTBS) was determined at baseline, and following one and two years of water storage using an EZ-Test device (Shimadzu). Representative specimens were examined under field emission scanning electron microscope. Fracture mode was recorded. The data were analyzed using linear mixed effects and least square means analyses. The significance level was set at 0.01 for the pairwise comparisons and at 0.05 for the overall model effects. RESULTS: The mean µTBS decreased significantly over time for Adper Prompt, iBond Self Etch, and OptiBond All-In-One. After two years of water ageing, Bond Force, Brush & Bond, OptiBond All-In-One, and Xeno IV had mean µTBS values not statistically different from Clearfil SE Bond. CONCLUSIONS: After two years of water ageing, Clearfil SE Bond outperformed two of six all-in-one adhesives. That indicates that the composition of the adhesives rather than their application approach is accountable for their performance. CLINICAL SIGNIFICANCE: Despite the data available suggesting that most all-in-one adhesives are severely affected by hydrolytic degradation, results of the present in vitro study suggest that some may perform as well as the clinically proven Clearfil SE Bond in the longer term.

Spotlight on bond strength testing--unraveling the complexities.

The variability in methods and outcomes of bond strength testing reports is well documented in the dental literature. Many studies lack important information, which impairs the ability to reproduce them as well as to compare them to other studies in the literature. In order to critically discuss the important issues around bond strength testing methods, and to move closer to at least standardizing the reporting of such studies, the Academy of Dental Materials held a conference in 2009 entitled Adhesion in Dentistry-Analyzing Bond Strength Testing Methods, Variables, and Outcomes. Short synopses of the presentations are presented in this article. This article also provides a list of the variables that should be reported in bond strength studies, regardless of testing methods, to be used by authors conducting future studies, as well as journal reviewers and editors. The goal is to provide guidance and a rationale for what should be included in a study so that reporting might be more standardized and to enhance the possibility that more meaningful comparisons and conclusions may be drawn across studies. The table lists detailed descriptions covering all aspects of testing procedures, including variables related to tooth substrate, restorative material, specimen preparation, pre-testing conditions, testing methods, data reporting and analysis.

Em restaurações diretas de resina composta, classes I e II, prefere utilizar sistema adesivo autocondicionante ou convencional (de duas ou três etapas clínicas?) / In direct restorations shrinkage, classes I and II prefere using etching system or conventional (of two or three clinical stages)

A aplicação clínica dos sistemas adesivos em dentes posteriores ainda divide opiniões. Tal fato pode ser resultado do grande número de sistemas adesivos atualmente encontrados na Odontologia, bem como da rápida mudança que ocorre com esses materiais, e pela falta de trabalhos conclusivos sobre a longevidade clínica comparando os diversos sistemas adesivos em dentes posteriores. ...

Effects of water-storage on the physical and ultramorphological features of adhesives and primer/adhesive mixtures.

The aims of this study were to evaluate the ultimate tensile strength (UTS) and elastic modulus (E) of adhesives, and primer/adhesive mixtures after aging for 6 months in water or oil; and to compare silver uptake patterns under the TEM. A one-step self-etching adhesive (One-up Bond F: OB), two two-step self-etching primers (SE Bond: SE and Protect Bond: CP), and two etch-and-rinse systems (Single Bond: SB and Prime&Bond NT: PB) were used. Bonding and primer solutions of self-etching systems were also mixed (SE+P and CP+P). Most adhesives presented decreased UTS after water-storage. Similar or increased UTS was observed after oil storage. Except for SB, E values did not change after water-storage, but they increased after storage in oil. OB, CP+P and SE+P presented more silver uptake. The effects of water-storage were material-dependent, and significantly affected the mechanical properties and silver uptake patterns of adhesives.

Solubility study of phytochemical cross-linking agents on dentin stiffness.

OBJECTIVES: The effects of interactions between cross-linking proanthocyanidins (PA) in polar solvents and type-I collagen of demineralized dentin were investigated. METHODS: Three PA-rich extracts, two from grape seed (GSEP and GSES) and one from cocoa (COE), were dissolved (water, ethanol:water and acetone:water) and analyzed for their ability to increase the modulus of elasticity of demineralized dentin. Sound dentin beams (0.5mmx1.7mmx7mm) were fully demineralized and divided into 12 groups according to the type of cross-linking agent and solvents used. Specimens were immersed in the respective solutions and tested at baseline, 10, 30, 60, 120 and 240min. RESULTS: The elastic modulus (EM) of dentin was significantly increased by the PA treatment regardless of time (p<0.05 for all times). The extracts showed different solubility in different solvents. GSEP showed the highest increase in EM when diluted in distilled water and acetone at all exposure times. Both GSEs showed superior results when diluted in distilled water and after 4h of treatment, while COE produced strongest enhancement when dissolved in ethanol:water. CONCLUSIONS: The results indicates that herbal extraction process and other pharmacognostic parameters have an important influence on extract solubility as well as constitution and, consequently, on the PA-dentin matrix interaction.

Fluoride-containing adhesive: durability on dentin bonding.

OBJECTIVES: To evaluate (1) the influence of fluoride-containing adhesive on microtensile bond strength (microTBS) and (2) in vitro secondary caries inhibition at the resin-dentin interface after 24 h and 3 months water-storage and (3) the degree of conversion of different adhesives after 24h 1 month. METHODS: Flat surfaces of human teeth were ground and randomly assigned to six groups: (SBMP-24) Scotchbond Multi-Purpose control [SBMP], 24 h; (SE-24) SBMP etch and primer+Clearfil SE Bond adhesive [SE], 24h; (PB-24) SBMP etch and primer+Clearfil Protect Bond adhesive [PB], 24h; (SBMP-3) SBMP, 3 months; (SE-3) SBMP+SE, 3 months; and (PB-3) SBMP+PB, 3 months. To evaluate the effect of the adhesive resin alone, all teeth were etched with 35% phosphoric acid and primed with SBMP primer prior to applying the adhesive resin. Bonded assemblies were prepared for microTBS and stored in distilled water at 37 degrees C for 24h and 3 months. Sections of restored teeth of each group were exposed to an acid challenge. The specimens were sectioned, polished, and then observed with polarized light microscopy (PLM). Also, the degree of conversion (DC) of the adhesives was measured using Fourier Transform-Infrared spectroscopy (FTIR) at 24 h and 1 month, after polymerization. RESULTS: microTBS values obtained in MPa (24h/3m) were: (MP) 61.5+/-10.5/52.9+/-8.9, (SE) 55.5+/-11.8/55.6+/-13, and (PB) 50.3+/-9.9/61.0+/-13.6. For interface analysis by PLM, an inhibition zone (IZ) adjacent to the hybrid layer was created only when the fluoride-containing adhesive (PB) was used. The DC in percentage (24 h, 1 month) were: (MP) 60.5+/-2.8/61.3+/-0.6, (SE) 69.6+/-1.3/70.7+/-0.05, and (PB) 53.1+/-0.4/58.3+/-1.6. SIGNIFICANCE: The fluoride-containing adhesive demonstrated significant increase of bond strength values after water-storage. This material was also able to create an acid inhibition zone in dentin. There was a significant increase of degree of conversion after 1 month only for PB.

Long-term bond strengths to dentin treated with different re-wetting solutions.

PURPOSE: To evaluate the microtensile bond strengths (microTBS) of two etch-and-rinse one-bottle adhesive systems to air-dried dentin re-wet with different agents. METHODS: 48 bovine teeth were ground flat to 600-grit and were assigned for treatment with either Single Bond or One-Step adhesives. Each group had three subgroups of re-wetting agents: water, Gluma Desensitizer and Aqua-Prep F. The teeth were acid-etched, air-dried for 5 seconds and re-wet with water, Gluma Desensitizer or Aqua-Prep F for 30 seconds and blot dried. Control specimens were prepared using a moist bonding technique. The adhesives were applied and the teeth were restored with Filtek Z250 or Renew composite. After 24 hours in distilled water at 37 degrees C, the teeth were sectioned into 0.7 mm-thick slabs, trimmed, and immediately tested for microTBS or stored for 6 months or 1 year prior to testing. Fracture sites were examined under scanning electron microscope (SEM). Data were evaluated by one- and three-way ANOVA, and Fisher's PLSD test (P<0.05). RESULTS: Except for Aqua-Prep F, the microTBS in the control, water and Gluma Desensitizer subgroups did not change significantly after 1-year for both Single Bond and One-Step groups. SEM analysis showed no specific pattern of fracture in the Single Bond specimens. One-Step had the majority of the fractures at the interface at baseline, and becoming a mixture of fractures at the interface and within the adhesive resin after 1 year.

Effect of resin adhesive systems on root caries formation in vitro.

OBJECTIVE: To evaluate the capability of different adhesive systems to inhibit in vitro caries formation. METHOD AND MATERIALS: Four materials were tested: Gluma Comfort Bond (GL; Heraeus Kulzer), Gluma Comfort Bond + Desensitizer (GL+; Heraeus Kulzer), iBond (iB; Heraeus Kulzer), and One-up Bond F (OUB; Tokuyama). Bovine roots were ground to obtain flat mesial and distal dentin surfaces. Nail varnish was applied to the entire root surface except for two 10 mm X 2 mm windows on the flattened surfaces. The adhesives were applied to the exposed areas according to the manufacturers' instructions. The roots were incubated at 37 degrees C for 1 week in a suspension of StreptococcuS mutans and Lactobacillus acidophilus. Control groups either received no root surface treatment or were etched with 37% phosphoric acid (without immersion in the bacterial suspension). Specimens were sectioned perpendicular to the long axis of the roots, stained for 24 hours with Rhodamine B, and analyzed with confocal laser microscopy. The data were analyzed by 1-way ANOVA and Fisher's PLSD test at 95% confidence level. RESULTS: Lesions in the OUB, iB, and GL+ groups were significantly shallower than those in the no-treatment group. Acid etching did not produce any measurable lesions. Mean lesion depth in the GL group was similar to that in the no-treatment group. There was no significant difference between mean lesion depths in the GL+, GL, and iB groups. CONCLUSION: Fluoride- and glutaraldehyde-containing adhesive systems might be an aid in root caries prevention.

The effect of load cycling on nanoleakage of deproteinized resin/dentin interfaces as a function of time.

OBJECTIVES: To evaluate the effects of cyclic loading on nanoleakage as a function of time at resin-dentin interfaces with and without removal of collagen. METHODS: Bovine flat mid-coronal dentin received one of the following surface treatments: (1) acid-etch or (2) acid etched+5% NaOCl for 2m. The teeth were then bonded with Single Bond (3M ESPE), Scotchbond Multi-Purpose (3M ESPE), One-Step Plus (Bisco) or All-Bond 2 (Bisco) adhesive systems and restored with Z250 composite. Half of the bonded teeth were randomly assigned to receive 200,000 cycles of loading at 50 N. Teeth were sectioned into 1 mm x 1 mm thick slices and stored in distilled water for 24h and 6 months. After water storage, beams were prepared for nanoleakage evaluation and observed under the SEM. Data were statistically analyzed using three-way ANOVA and Fisher's PLSD test (p<0.05). RESULTS: Use of NaOCl did not affect nanoleakage at the interface of all adhesive systems (p>0.05) when compared to their respective controls. After 6 months of immersion in water, except for One Step Plus, collagen-depleted groups and control groups presented similar leakage values. After cyclic loading, the deproteinized group revealed a higher degree of silver nitrate deposits when compared to the control group (p<0.05). All four adhesive systems presented a high degree of silver nitrate deposits after 6 months of water storage. SIGNIFICANCE: The hybrid layer is important as a stress-absorbing layer and it may not represent the weak link for initiation of the nanoleakage phenomenon.