The effectiveness of fluoride in caries prevention has been convincingly proven. In recent years, researchers have investigated the preventive effects of different fluoride formulations on erosive ...tooth wear with positive results, but their action on caries and erosion prevention must be based on different requirements, because there is no sheltered area in the erosive process as there is in the subsurface carious lesions. Thus, any protective mechanism from fluoride concerning erosion is limited to the surface or the near surface layer of enamel. However, reports on other protective agents show superior preventive results. The mechanism of action of tin-containing products is related to tin deposition onto the tooth surface, as well as the incorporation of tin into the near-surface layer of enamel. These tin-rich deposits are less susceptible to dissolution and may result in enhanced protection of the underlying tooth. Titanium tetrafluoride forms a protective layer on the tooth surface. It is believed that this layer is made up of hydrated hydrogen titanium phosphate. Products containing phosphates and/or proteins may adsorb either to the pellicle, rendering it more protective against demineralization, or directly to the dental hard tissue, probably competing with H+ at specific sites on the tooth surface. Other substances may further enhance precipitation of calcium phosphates on the enamel surface, protecting it from additional acid impacts. Hence, the future of fluoride alone in erosion prevention looks grim, but the combination of fluoride with protective agents, such as polyvalent metal ions and some polymers, has much brighter prospects.
Controversial results showing that deciduous teeth are more susceptible to erosion than permanent teeth might be related to study designs. We investigated how different conditions (pH: 3.0, 4.0, 5.0; ...acid agitation: gentle or vigorous; acid exposure times: 1-5 min) affect the susceptibility of both teeth to erosion. Enamel specimens (90 deciduous, 90 permanent) were distributed into groups (n = 15 permanent, n = 15 deciduous) according to acid pH (pH 5, 4 or 3) and agitation (gentle or vigorous) during erosive challenge. Both milder (less incubation time, gentle agitation, and higher pH) and more severe (longer incubation times, vigorous shaking, and lower pH) conditions were used. Demineralization was measured by relative surface microhardness (rSMH) and calcium released to the acid. Demineralization increased gradually for both teeth with increasing incubation time, agitation (gentle or vigorous), and with decreasing acid pH. The differences between deciduous and permanent teeth depended on the protocol design and assessment method. Under milder conditions, demineralization was better detectable with rSMH. Under more severe conditions, differences were more perceptible with calcium analyses. Differences exist in the susceptibility to erosion between deciduous and permanent teeth, but they are only distinguishable when the appropriate assessment method is used for the specific erosive condition.
Abstract Objectives To investigate the influence of increment thickness on Vickers microhardness (HV) and shear bond strength (SBS) to dentin of a conventional and four bulk fill resin composites. ...Methods HV and SBS were determined on specimens of the conventional resin composite Filtek Supreme XTE (XTE) and the bulk fill resin composites SDR (SDR), Filtek Bulk Fill (FBF), x-tra fil (XFIL), and Tetric EvoCeram Bulk Fill (TEBF) after 24 h storage. HV was measured either as profiles at depths up to 6 mm or at the bottom of 2 mm/4 mm/6 mm thick resin composite specimens. SBS of 2 mm/4 mm/6 mm thick resin composite increments was measured to dentin surfaces of extracted human molars treated with the adhesive system OptiBond FL, and the failure mode was stereomicroscopically determined at 40× magnification. HV profiles and failure modes were descriptively analysed whereas HV at the bottom of resin composite specimens and SBS were statistically analysed with nonparametric ANOVA followed by Wilcoxon rank sum tests ( α = 0.05). Results HV profiles (medians at 2 mm/4 mm/6 mm): XTE 105.6/88.8/38.3, SDR 34.0/35.5/36.9, FBF 36.4/38.7/37.1, XFIL 103.4/103.9/101.9, TEBF 63.5/59.7/51.9. HV at the bottom of resin composite specimens (medians at 2 mm/4 mm/6 mm): XTE ( p < 0.0001) 105.5 > 85.5 > 31.1, SDR ( p = 0.10) 25.8 = 21.9 = 26.0, FBF ( p = 0.16) 26.6 = 25.3 = 28.9, XFIL ( p = 0.18) 110.5 = 107.2 = 101.9, TEBF ( p < 0.0001) 63.0 > 54.9 > 48.2. SBS (MPa, medians at 2 mm/4 mm/6 mm): XTE ( p < 0.0001) 23.9 > 18.9 = 16.7, SDR ( p = 0.26) 24.6 = 22.7 = 23.4, FBF ( p = 0.11) 21.4 = 20.3 = 22.0, x-tra fil ( p = 0.55) 27.0 = 24.0 = 23.6, TEBF ( p = 0.11) 21.0 = 20.7 = 19.0. The predominant SBS failure mode was cohesive failure in dentin. Significance At increasing increment thickness, HV and SBS decreased for the conventional resin composite but generally remained constant for the bulk fill resin composites.
Summary Objectives To evaluate if depth of cure DISO determined by the ISO 4049 method is accurately reflected with bulk fill materials when compared to depth of cure Dnew determined by Vickers ...microhardness profiles. Methods DISO was determined according to “ISO 4049; Depth of cure” and resin composite specimens ( n = 6 per group) were prepared of two control materials (Filtek Supreme Plus, Filtek Silorane) and four bulk fill materials (Surefil SDR, Venus Bulk Fill, Quixfil, Tetric EvoCeram Bulk Fill) and light-cured for either 10 s or 20 s. For Dnew , a mold was filled with one of the six resin composites and light-cured for either 10 s or 20 s ( n = 22 per group). The mold was placed under a microhardness indentation device and hardness measurements (Vickers hardness, VHN) were made at defined distances, beginning at the resin composite that had been closest to the light-curing unit (i.e. at the “top”) and proceeding toward the uncured resin composite (i.e. toward the “bottom”). On the basis of the VHN measurements, Vickers hardness profiles were generated for each group. Results DISO varied between 1.76 and 6.49 mm with the bulk fill materials showing the highest DISO. Dnew varied between 0.2 and 4.0 mm. Dnew was smaller than DISO for all resin composites except Filtek Silorane. Conclusions For bulk fill materials the ISO 4049 method overestimated depth of cure compared to depth of cure determined by Vickers hardness profiles.
Abstract Statement of problem Because of the different composition of resin-ceramic computer-aided design and computer-aided manufacturing (CAD-CAM) materials, their polishability and their ...micromechanical properties vary. Moreover, depending on the composition of the materials, their surface roughness and micromechanical properties are likely to change with time. Purpose The purpose of this in vitro study was to investigate the effect of artificial toothbrushing and water storage on the surface roughness (Ra and Rz) and the micromechanical properties, surface hardness (Vickers VHN) and indentation modulus (EIT ), of 5 different tooth-colored CAD-CAM materials when polished with 2 different polishing systems. Material and methods Specimens (n=40 per material) were cut from a composite resin (Paradigm MZ100; 3M ESPE), a feldspathic ceramic (Vitablocs Mark II; Vita Zahnfabrik), a resin nanoceramic (Lava Ultimate; 3M ESPE), a hybrid dental ceramic (Vita Enamic; Vita Zahnfabrik), and a nanocomposite resin (Ambarino High-Class; Creamed). All specimens were roughened in a standardized manner and polished either with Sof-Lex XT discs or the Vita Polishing Set Clinical. Surface roughness, VHN, and EIT were measured after polishing and after storage for 6 months (tap water, 37°C) with periodic, artificial toothbrushing. The surface roughness, VHN, and EIT results were analyzed with a nonparametric ANOVA followed by Kruskal-Wallis and exact Wilcoxon rank sum tests (α=.05). Results Irrespective of polishing system and of artificial toothbrushing and storage, Lava Ultimate generally showed the lowest surface roughness and Vitablocs Mark II the highest. As regards micromechanical properties, the following ranking of the CAD-CAM materials was found (from highest VHN/EIT to lowest VHN/EIT ): Vitablocs Mark II > Vita Enamic > Paradigm MZ100 > Lava Ultimate > Ambarino High-Class. Irrespective of material and of artificial toothbrushing and storage, polishing with Sof-Lex XT discs resulted in lower surface roughness than the Vita Polishing Set Clinical ( P ≤.016). However, the polishing system generally had no influence on the micromechanical properties ( P >.05). The effect of artificial toothbrushing and storage on surface roughness depended on the material and the polishing system: Ambarino High-Class was most sensitive to storage, Lava Ultimate and Vita Enamic were least sensitive. Artificial toothbrushing and storage generally resulted in a decrease in VHN and EIT for Paradigm MZ100, Lava Ultimate, and Ambarino High-Class but not for Vita Enamic and Vitablocs Mark II. Conclusions Tooth-colored CAD-CAM materials with lower VHN and EIT generally showed better polishability. However, these materials were more prone to degradation by artificial toothbrushing and water storage than materials with higher VHN and EIT.
This study aimed at analysing the erosive potential of 30 substances (drinks, candies, and medicaments) on deciduous enamel, and analyse the associated chemical factors with enamel dissolution. We ...analysed the initial pH, titratable acidity (TA) to pH 5.5, calcium (Ca), inorganic phosphate (Pi), and fluoride (F) concentration, and degree of saturation ((pK -pI)HAP, (pK -pI)FAP, and (pK-pI)CaF2) of all substances. Then, we randomly distributed 300 specimens of human deciduous enamel into 30 groups (n = 10 for each of the substances tested. We also prepared 20 specimens of permanent enamel for the sake of comparison between the two types of teeth, and we tested them in mineral water and Coca-Cola®. In all specimens, we measured surface hardness (VHN: Vickers hardness numbers) and surface reflection intensity (SRI) at baseline (SH baseline and SRI baseline), after a total of 2 min (SH2 min) and after 4 min (SH4 min and SRI4 min) erosive challenges (60 ml of substance for 6 enamel samples; 30°C, under constant agitation at 95 rpm). There was no significant difference in SH baseline between deciduous and permanent enamel. Comparing both teeth, we observed that after the first erosive challenge with Coca-Cola®, a significantly greater hardness loss was seen in deciduous (-90.2 ± 11.3 VHN) than in permanent enamel (-44.3 ± 12.2 VHN; p = 0.007), but no differences between the two types of teeth were observed after two challenges (SH4 min). After both erosive challenges, all substances except for mineral water caused a significant loss in relative surface reflectivity intensity, and most substances caused a significant loss in surface hardness. Multiple regression analyses showed that pH, TA and Ca concentration play a significant role in initial erosion of deciduous enamel. We conclude that drinks, foodstuffs and medications commonly consumed by children can cause erosion of deciduous teeth and erosion is mainly associated with pH, titratable acidity and calcium concentration in the solution.
Our understanding of erosive tooth wear and its contributing factors has evolved considerably over the last decades. New terms have been continuously introduced, which frequently describe the same ...aspects of this condition, whereas other terms are being used inappropriately. This has led to unnecessary confusion and miscommunication between patients, professionals, and researchers. A group of 15 experts, selected by the European Organization for Caries Research (ORCA) and the Cariology Research Group of the International Association for Dental Research (IADR), participated in a 2-day workshop to define the most commonly used terms in erosive tooth wear. A modified Delphi method was utilized to reach consensus. At least 80% agreement was achieved for all terms discussed and their definitions related to clinical conditions and processes, basic concepts, diagnosis, risk, and prevention and management of erosive tooth wear. Use of the terms agreed on will provide a better understanding of erosive tooth wear and intends to enable improved communication on this topic.
To investigate the effect of some polyphenol-rich plant extracts on the protection of dentine against demineralization, both acting on the dentine and on the salivary pellicle. Dentine specimens (n = ...180) were randomly distributed into 6 experimental groups (n = 30/group): Control (deionized water), Açaí extract, Blueberry extract, Green tea extract, Grape seed extract, and Sn
/F
(mouthrinse containing stannous and fluoride). Each group was further divided into two subgroups (n = 15), according to the site of action of the substance: on the dentine surface (D) or on the salivary pellicle (P). The specimens were submitted to 10 cycles: 30 min incubation in human saliva (P) or only in humid chamber (D), 2 min immersion in experimental substances, 60 min of incubation in saliva (P) or not (D), and 1 min erosive challenge. Dentine surface loss (DSL), amount of degraded collagen (dColl) and total calcium release were analyzed. Green tea, Grape seed and Sn
/F
showed significant protection, with least DSL and dColl. The Sn
/F
showed better protection on D than on P, whereas Green tea and Grape seed showed a dual mode of action, with good results on D, and even better on P. Sn
/F
showed the lowest values of calcium release, not differing only from Grape seed. Sn
/F
is more effective when acting directly on the dentine surface, while Green tea and Grape seed have a dual mode of action: with a positive effect on the dentine surface itself, but an improved efficacy in the presence of the salivary pellicle. We further elucidate the mechanism of action of different active ingredients on dentine erosion, where Sn
/F
acts better on the dentine surface, but plant extracts have a dual mode of action, acting on the dentine itself as well as on the salivary pellicle, improving the protection against acid demineralization.
Dental erosion is often described solely as a surface phenomenon, unlike caries where it has been established that the destructive effects involve both the surface and the subsurface region. However, ...besides removal of the surface, erosion shows dissolution of mineral within the softened layer - beneath the surface. In order to distinguish this process from the carious process it is now called 'near surface demineralization'. Erosion occurs in low pH, but there is no fixed critical pH value concerning dental erosion. The critical pH value for enamel concerning caries (pH 5.5-5.7) has to be calculated from calcium and phosphate concentrations of plaque fluid. In the context of dental erosion, the critical pH value is calculated from the calcium and phosphate concentrations in the erosive solution itself. Thus, critical pH for enamel with regard to erosion will vary according to the erosive solution. Erosive tooth wear is becoming increasingly significant in the management of the long-term health of the dentition. What is considered as an acceptable amount of wear is dependent on the anticipated lifespan of the dentition and is, therefore, different for deciduous compared to permanent teeth. However, erosive damage to the teeth may compromise the patient's dentition for their entire lifetime and may require repeated and increasingly complex and expensive restorations. Therefore, it is important that diagnosis of the tooth wear process in children and adults is made early and that adequate preventive measures are undertaken. These measures can only be initiated when the risk factors are known and interactions between them are present.
The aim was to investigate dentin bond strength of two resin-ceramic materials and five cements after 24 h and six months storage. Cylinders (n=15/group) of Lava Ultimate (3M ESPE) and VITA ENAMIC ...(VITA Zahnfabrik) were cemented to mid-coronal dentin of 300 extracted human molars with RelyX Ultimate (3M ESPE), PANAVIA F2.0 (Kuraray), Variolink II (Ivoclar Vivadent), els cem (Saremco Dental), or Ketac Cem Plus (3M ESPE). Shear bond strength (SBS) was measured after 24 h or six months storage (37°C, 100% humidity) and statistically analyzed (significance level: α=0.05). SBS varied markedly between Lava Ultimate and VITA ENAMIC, between the five cements, and between storage of either 24 h or six months. After six months, SBS was highest when Lava Ultimate was cemented with RelyX Ultimate and when VITA ENAMIC was cemented with RelyX Ultimate or with Variolink II. Lava Ultimate was somewhat more sensitive to storage than was VITA ENAMIC.
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