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Objective Acidic diets are advocated as main risk factor for tooth erosion, which could be prevented, or at least controlled, if patients were early advised. It is important to identify, hence, if possible dietary constituents regionally consumed on large scale, such as tucupi, a low-pH yellowish-green color and strong flavor delicacy made from the juice of a bitter cassava, may explain its occurrence in specific patient groups. This cross-over in situ / ex vivo study evaluated tucupi's ability to promote erosion of bovine enamel by assessing its percentage of surface microhardness change (%SMHC), taking a cola-based soft drink and human saliva as positive and negative controls. Design For three 7-days spaced out legs of 7 days each, nine volunteers wore palatal devices with three bovine enamel blocks, which were challenged with one of the following solutions: TUC—tucupi ( n = 27); COL—cola-based soft drink ( n = 27); SAL—saliva ( n = 27). Erosive challenges were performed extra-orally (4×/day) by dropping TUC or COL at room temperature on specimens. After 5 min, palatal devices were replaced into the mouth. SAL permanently acted as the negative control while volunteers solely wore the device. One-way ANOVA followed by Tukey’s post-hoc tests ( α = 0.05) were applied. Results TUC promoted an enamel %SMHC (−21.56 ± 10.08 a ) similar than that promoted by COL (−18.19 ± 12.99 a ; p = 0.275), which were both significantly higher than that promoted by SAL (−1.86 ± 13.65 b ; p < 0.0001). Conclusions Besides the most worldwide appreciated cola-based soft drink, the greatly consumed Amazonian delicacy tucupi can be considered a potential risk factor for tooth erosion. [ABSTRACT FROM AUTHOR] more...

Abstract: Objective: The aims of the present laboratory study were twofold: a) to investigate the suitability of Knoop and Vickers surface microhardness (SMH) in comparison to transverse microradiography (TMR) to investigate early enamel caries lesion formation; b) to compare the kinetics of caries lesion initiation and progression between human and bovine enamel. Design: Specimens (90×bovine and 90×human enamel) were divided into six groups (demineralization times of 8/16/24/32/40/48h) of 15 per enamel type and demineralized using a partially saturated lactic acid solution. SMH was measured before and after demineralization and changes in indentation length (ΔIL) calculated. Lesions were characterized using TMR. Data were analyzed (two-way ANOVA) and Pearson correlation coefficients calculated. Results: ΔIL increased with increasing demineralization times but plateaued after 40h, whereas lesion depth (L) and integrated mineral loss (ΔZ) increased almost linearly throughout. No differences between Knoop and Vickers SMH in their ability to measure enamel demineralization were observed as both correlated strongly. Overall, ΔIL correlated strongly with ΔZ and L but only moderately with the degree of surface zone mineralization, whereas ΔZ and L correlated strongly. Bovine demineralized faster than human enamel (all techniques). Conclusions: Lesions in bovine formed faster than in human enamel, although the resulting lesions were almost indistinguishable in their mineral distribution characteristics. Early caries lesion demineralization can be sufficiently studied by SMH, but its limitations on the assessment of the mineral status of more demineralized lesions must be considered. Ideally, complementary techniques to assess changes in both physical and chemical lesion characteristics would be employed. [Copyright &y& Elsevier] more...

Objectives: Most in vitro studies investigate the erosive process using relatively simple roughness parameters such as roughness average (Ra). In isolation, Ra may misrepresent the surface features. Further, few studies report baseline surface characteristics after sample preparation. This study aimed to test the hypothesis that measuring the bearing area parameters in addition to Ra may be useful when qualifying the surface of enamel at baseline and after an erosive challenge. The null hypothesis for this study was that the bearing area parameters provide no more useful information than Ra alone, when qualifying the surface of enamel at baseline and after an erosive challenge. Methods: Enamel slabs (n = 20) were prepared from human (n = 2) and bovine (n = 4) incisor teeth and polished with 0.05 μm paste. Roughness average (Ra) and bearing parameters (MR1, MR2, Rpk, Rk, Rvk) were used to record baseline characteristics. Specimens were subjected to erosion with 1% citric acid solution for 1 min. Profilometric characteristics were recorded post- erosion, along with the maximum height changes within the profile. T-tests were carried out in order to compare baseline surface characteristics between tissue types. Post-erosion, analysis of variance (ANOVA) was used to test the effects of tissue type (bovine or human). Results: There was no significant difference in Ra between human and bovine incisor enamel at baseline (human 0.11 μm, bovine 0.12 μm P > 0.05), and no significant difference was observed post-erosion (human 0.23 μm, bovine 0.20 μm P > 0.05). There were significant differences in bearing parameters at baseline and post-erosion that were not identified by the Ra measurement alone. Conclusions: The results suggest that if Ra alone is measured, important differences in surface characteristics may be missed. The null hypothesis is rejected, and the recommendation is made that bearing parameters are included within profile measurements in order to further triangulate the results of surface analysis studies. Clinical relevance: In isolation, Ra may misrepresent the surface features of a profile. These results have shown that the bearing parameters are an important and informative set of measurements. The recommendation is made that bearing parameters are included within profile measurements at baseline and post-erosion, in order to further triangulate the results of surface analysis studies. [ABSTRACT FROM AUTHOR] more...

Abstract: Objectives: This study was conducted to compare the remineralization effects of five regimens on the loss of fluorescence intensity, surface microhardness, roughness and microstructure of bovine enamel after remineralization. We hope that these results can provide some basis for the clinical application of these materials. Methods: One hundred bovine incisors were prepared and divided into the following five groups, which were treated with distinct dental materials: (1) Clinpro™ XT varnish (CV), (2) F-varnish (FV), (3) Tooth Mousse (TM), (4) Fuji III LC® light-cured glass ionomer pit and fissure sealant (FJ) and (5) Base Cement® glass polyalkenoate cement (BC). Subsequently, they were detected using four different methods: quantitative light-induced fluorescence, microhardness, surface 3D topography and scanning electron microscopy (SEM). Results: The loss of fluorescence intensity of CV, BC and FJ groups showed significant decreases after remineralization (p <0.05). The microhardness values of the BC group were significantly higher than those of the other groups (p <0.05) after 6 weeks of remineralization. The CV group''s surface roughness was significantly lower than those of the other groups after 6 weeks of remineralization (p <0.05). Regarding microstructure values, the FV group showed many round particles deposited in the bovine enamel after remineralization. However, the other four groups mainly showed needle-like crystals. Conclusions: Glass ionomer cement (GIC)-based dental materials can promote more remineralization of the artificial enamel lesions than can NaF-based dental materials. Resin-modified GIC materials (e.g., CV and FJ) have the potential for more controlled and sustained release of remineralized agents. The effect of TM requires further study. [Copyright &y& Elsevier] more...

Abstract: Objectives: This study evaluated possible differences regarding the remineralization of predemineralized enamel after exposure to fluoridated or non-fluoridated bleaching gels. Methods: 120 enamel specimens were prepared from sixty bovine incisors; before and after demineralization (37°C; pH 4.95; 10d), one-quarter of each specimen''s surface was covered with nail varnish (control sound/demineralized). Subsequently, the specimens were stored for 16h daily in a remineralizing solution (pH 7.0; 14d), while for the remaining time (8h) various bleaching gels were applied: (1) no treatment (control), (2) Opalescence regular (O, Ultradent), (3) Opalescence PF (O-PF), (4) Nite White ACP (NW-ACP, Discus Dental) and (5) Nite White ACPF (NW-ACPF). Following, half of the bleached parts were nail-varnished and stored for another 3-weeks period in a remineralizing solution. Differences in mineral losses (ΔΔZ) and lesion depths (ΔLD) before and after treatment/remineralization period were evaluated from microradiographs. ΔΔZ surface values (mineral loss of the outer 18μm of the lesion) were calculated. Results: After 2 and 5 weeks ΔΔZ/ΔLD values of the bleaching groups did not differ significantly from the controls. Treatment with NW-ACPF for 2 weeks resulted in significantly lower ΔΔZ values compared to NW-ACP (p =0.032) and NW-ACPF in higher values than Opalescence regular (p =0.006). Two weeks treatment with O and O-PF resulted in decreased ΔΔZ surface values compared to control (p <0.0005), whereas with NW-ACPF no significant differences could be observed (p =0.062). Application of NW-ACP induced significantly increased ΔΔZ surface values compared to control (p =0.001). Conclusions: No supporting influence of fluoride-containing bleaching gels on remineralization could be observed. [Copyright &y& Elsevier] more...

Abstract: Objectives: The present study evaluated the effects of various calcium and phosphate concentrations and ratios of carboxymethylcellulose (CMC)-based solutions on the mineral loss of predemineralised bovine enamel in vitro. Methods: Bovine enamel specimens were prepared, polished and partly covered with nail varnish, thus serving as control of sound enamel. After demineralisation (37°C; pH 5.0; 14 days) the specimens were exposed to CMC-based solutions (20g/l) with various saturations with respect to apatites containing 0.1mM NaF, CaCl2 (0–32mM) and KH2PO4 (0–52mM) at two different pH values (5.5 or 6.5). A fluoride-free solution served as control, and four commercially available products were tested as well. The differences in mineral loss (ΔΔZ) between the values prior to (ΔZ Demin) and after storage (ΔZ Effect) in the various solutions were evaluated from microradiographs of thin sections (100μm). Results: The general linear model revealed a significant dependency for ΔΔZ on ‘calcium’ (p <0.001), ‘phosphate’ (p =0.023), ‘fluoride’ (p =0.002) and ‘pH’ (p <0.001). With increasing calcium and phosphate concentrations an increase in ΔΔZ could be observed up to the solution containing the third highest saturation with respect to octacalciumphosphate (3.2), showing a significant remineralisation (p <0.05; t-test). The commercially available products as well as the control groups revealed significantly reduced ΔΔZ values compared to this group (p <0.01; Bonferroni). Conclusions: A saturation with respect to octacalciumphosphate of 3.2 and a pH of 6.5 enables CMC-based solutions to remineralise bovine enamel in vitro. [Copyright &y& Elsevier] more...

Summary: Objectives: Enamel erosion results in the formation of a softened layer that is susceptible to disruption by mechanical factors such as brushing abrasion, tongue friction and attrition. The aim of this study was to investigate the individual contribution of those mechanical insults to the enamel loss caused by dental erosion. Methods: Forty two bovine enamel samples were randomly divided into seven groups (n=6 per group) that were submitted to 3cycles of one of the following regimes: erosion and remineralization (er/remin); toothbrush abrasion and remineralization (abr/remin); erosion, toothbrush abrasion and remineralization (er/abr/remin); attrition and remineralization (at/remin); erosion, attrition and remineralization (er/at/remin); simulated tongue friction and remineralization (tg/remin); erosion, simulated tongue friction and remineralization (er/tg/remin). Erosion took place in a demineralization solution (50mM citric acid, pH 3) for 10min under agitation. Brushing abrasion, tongue friction and attrition were simulated for 1min using a home-made wear device. Remineralization was carried out in artificial saliva for 2h. Enamel loss was quantified using optical profilometry. Results: One-way ANOVA indicated a significant difference between the amounts of enamel lost due to the different wear regimes (p≤0.001). Multiple comparisons with Bonferroni procedure showed that the wear depths found for the er/at/remin (p≤0.001) and er/tg/remin (p≤0.001) were significantly higher than the amount found for the er/remin group (4.4±0.7μm). This was not the case for er/abr/remin group (p=0.075). Conclusions: The results suggest that the three forms of mechanical insults remove to varying extent the softened layer formed by the erosion challenges. [Copyright &y& Elsevier] more...

Summary: Sealing of approximal enamel lesions by infiltration with low viscous resins seems to be a promising approach in non-operative dentistry and should bear advantages compared to remineralization or invasive treatment. Objective: The aim of this in vitro study was to evaluate the penetration ability of five dental adhesives and a fissure sealant into initial enamel lesions for an application time of either 15s or 30s. Methods: In each of 54 specimens of bovine enamel, three windows were demineralized for 14 days. Subsequently, two windows were etched with phosphoric acid for 5s in order to degrade the surface layer, whereas one window served as untreated control. The specimens were randomly divided into six groups and a fissure sealant as well as five different adhesives were applied onto the subsurface lesions and allowed to penetrate for either 15 or 30s. Overlying material was wiped away and the resins were light cured. To visualize the penetrated resins and the remaining pore structures, the specimens were infiltrated with a low viscous fluorescent resin and studied using a Confocal Laser Scanning Microscope (CLSM). Results: For Helioseal, Heliobond, Resulcin Monobond, and Excite an application time of 30s resulted in significantly higher (p<0.05; t-test) penetration depths (47–105μm) compared to 15s (29–49μm). Significance: Helioseal, Heliobond, Resulcin Monobond, and Excite are suitable for sealing artificial subsurface enamel lesions in vitro. After an application time of 30s a significant deeper penetration could be observed for these materials. [Copyright &y& Elsevier] more...

In the present paper, the effects of polyacrylic acid (PAA) conditioning on the morphology and chemistry of bovine enamel surface and the resulting interfacial reactions are being investigated using photometric, microscopic (SEM, AFM), electron spectroscopic (XPS) and staining methods (neutral red dye). The results are compared to two reference surfaces obtained by simple grinding and by etching with a phosphoric acid solution. It is shown that PAA conditioning leads to the leaching of calcium and phosphorus ions, to the smoothening of the surface and probably to the formation of a polymeric film at the surface. A mechanism by which a preliminary PAA conditioning of the enamel leads to the reported higher bonding strength between enamel and glass ionomer cements is proposed. [Copyright &y& Elsevier] more...

[Display omitted] • Except chemical composition, the microstructure of enamel is also involved in its surface corrosion. • The HAP nanocrystallite orientation changes acid permeability into the enamel surface. • Transversal crystallites result in zigzagged permeation channels to prevent acid penetration. • Longitudinal crystallites endue enamel with better wear resistance than transversal crystallites. Due to the complexity of the oral environment, understanding the relationship between the enamel microstructure and corrosion behavior of mammalian teeth is important for the development and bionic design of novel dental materials with corrosion resistance. In this paper, enamel microstructure and its influence on corrosion and tribocorrosion behavior of bovine and human molars are studied using focused ion beam & scanning electronic microscopy (FIB-SEM), transmission electron microscope (TEM), nanoindentation, and wear testing. It was found that the regions with transversal HAP nanocrystallites have better corrosion resistance than those with longitudinal crystallites. Apart from the chemical composition, the microstructure of enamel also involves in its surface corrosion. HAP nanocrystallite orientation changes the acid permeability into the enamel surface. Transversal nanocrystallites result in zigzagged acid permeation channels to increase the difficulty of acid penetration and then improve the corrosion resistance of enamel surface. The higher the fraction of transversal nanocrystallites on a surface, the better is the corrosion resistance. These findings extend our understanding of the corrosion/wear mechanisms of dental enamel with different microstructures. [ABSTRACT FROM AUTHOR] more...

• Bovine and human enamel are similar in composition and structure. • Human and bovine enamels show similar hardness. • Bovine enamel has higher fracture toughness than human enamel. The purpose of this investigation was to establish microstructure, microhardness, fracture toughness, chemical composition, and crack repair of bovine enamel and to compare these features with their human counterparts. Bovine enamel fragments were prepared and optical microscopy and atomic force microscopy were used to establish microstructure; Raman spectroscopy was used to estimate composition and microindentation using Vickers testing was performed to evaluate hardness. A strong dependence between indentation load and microhardness values was observed, as was the case in human enamel. Similar microstructure and chemical composition between bovine and human enamel, 7.89% lower microhardness and 40% higher fracture toughness values for bovine enamel were found. From a structural and mechanical standpoint, bovine enamel is a suitable alternative to human enamel for in vitro testing of dental products. [ABSTRACT FROM AUTHOR] more...

Abstract: Objectives: MDP (10-methacryloyloxydecyl dihydrogenphosphate) has been proven to possess chemical bonding ability to tooth hard tissues, but its contribution to the enamel bond strength has not been recognized. The aim of this study was to investigate the contribution of chemical bonding to the short- and long-term bovine enamel micro-tensile bond strengths (μTBS). Methods: The acid-etched enamel surfaces were treated without any primer (control) or with one of three MDP-containing primers (containing different ratio of MDP/HEMA/Bis-GMA, Kuraray Co.) for 5s, water-sprayed and air-dried. Subsequently, the pretreated enamel surfaces were applied with an etch-and-rinse adhesive Durafill Bond (Heraeus Kulzer) and placed with composite resin Durafill VS (Heraeus Kulzer). The specimens were prepared for μTBS tests after 24-h or 1-yr water storage. The etched enamel surfaces treated with or without MDP-containing primers were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results: The acid-etched enamel treated with the MDP-primers for a very short time could produce the greater enamel μTBS than the control did (p <0.05), and change enamel micromorphology. No significant different μTBS were found between 24-h and 1-yr water storage (p >0.05). The chemical bonding of MDP on the enamel surfaces was re-confirmed by XPS. Significance: The additional chemical bonding of MDP around the enamel crystallites of the etched enamel substrate could significantly increase the short- and long-term enamel μTBS, and their μTBS surpass those of the etch-and-rinse adhesive alone. [Copyright &y& Elsevier] more...