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This paper utilizes a coupled chemomechanical model that integrates chemical reactions, diffusion, and mechanical deformation to describe the high-temperature interfacial reactions and stress evolution within an enamel coating/Ni-based super-alloy system. Through finite element simulation, we conduct a comprehensive analysis of multiple reactions and processes at the interface. Experimental characterization of the concentration distribution of various elements is employed to verify the accuracy of the proposed chemomechanical model. Additionally, the simulation reveals that the interface region experiences compressive circumferential stress, which can potentially lead to interfacial failure due to buckling. On the other hand, the enamel coating undergoes tensile circumferential stress, resulting in the formation of vertical surface cracks. These findings hold practical implications for the development of advanced coatings with enhanced durability and performance. Future research can further optimize coating design and enhance the reliability of high-temperature applications based on these results. [ABSTRACT FROM AUTHOR]

Purpose: This paper describes previously unknown details about the discovery of resin adhesion to acid-etched human enamel. Materials and Methods: A literature review was performed through manual assessments. Primary sources revealing the discovery of resin curing on etched enamel were analyzed considering the research objectives and methodological procedure during that era, including the type of teeth used, preparatory measures, acid-etching process, type of resin and its application, and follow-up observations. Additionally, the political and economic contexts were examined. Results: In 1949, acid etching was found to promote adhesion with acrylic resin, a finding described again in 1955. The 1949 studies utilized nitric acid for enamel etching and the acrylate resin Paladon from the Kulzer company (Germany). Conversely, the 1955 investigations employed phosphoric acid and an unnamed acrylate, likely a self-curing resin supported by Kulzer in the late 1930s. Disparities in the 1949 and 1955 findings can be ascribed to varying objectives and test conditions amidst a turbulent political backdrop, significantly impacting the Kulzer company. Conclusion: The discovery of resin adhesion to acid-etched enamel, approaching its 75th anniversary in 2024, is a landmark in 20th-century adhesive dentistry. Paladon represents a pioneering compound, exemplifying the influence of political, ideological, and economic factors on scientific advancements during that period. [ABSTRACT FROM AUTHOR]

ABSTRACT Linear enamel hypoplasias (LEHs) are development defects appearing as lines or grooves on enamel surfaces. Forming when physiological stressors disrupt developing teeth, LEHs provide retrospective insight into stress experienced in early development. Here, LEHs in Cayo Santiago rhesus macaques (Macaca mulatta) were observed with respect to decade of birth, whether an individual was transferred from the free‐ranging colony to the captive facility during probable crown formation periods, and matriline of birth. It was hypothesized that later decades would exhibit higher prevalence than earlier decades as climatic conditions in Puerto Rico worsened over time. Transfer was expected to affect LEH formation because the process of transfer, and subsequent restriction to captivity, is thought to be stressful. Matriline membership was hypothesized to relate to LEH formation because there is some evidence of a genetic influence on susceptibility to form LEH and because offspring of matrilines of different dominance ranks are known to experience different levels of aggression. Lower third premolars with minimal enamel surface wear were scored for LEH using a digital microscope, while a follow‐up analysis of the two matrilines with the most extreme differences in LEH frequency was conducted using enamel surface profiles. Results were: (1) individuals born during the 1990s had significantly greater LEH prevalence than those born in the 1960s, (2) transferred individuals exhibited weak evidence of greater LEH prevalence than nontransferred comparison groups, and (3) matrilines did not differ in LEH expression in the initial or follow‐up analysis. Although sample sizes were small for some comparisons, these results suggest that not all decades saw an equal prevalence of LEH, that there might be a small effect of transfer from free‐ranging to captive conditions on LEH prevalence that is difficult to detect, and that the matriline into which an individual is born is not related to LEH expression. [ABSTRACT FROM AUTHOR]

Background: Bleaching is a conservative treatment option to deliver esthetic smile makeover for discoloured tooth. Various concentration of bleaching agents can influence the bonding of the restoration to the tooth. Aims and Objectives: The aim of the study was to determine the effect of glutathione on bond strength of composite resin to enamel following extra coronal bleaching at two different time intervals. Materials and Methods: Forty molars were randomly assigned into four groups of ten each. Group A: Bleaching followed by immediate composite build up and no antioxidant application. Group B: bleaching followed by application of 20% Glutathione and immediate composite built-up was done. Group C: Bleaching followed by composite restoration after one week. Group D: Bleaching followed by application of 20% Glutathione before composite build up after one week. Shear bond strength was tested using a universal testing machine and fracture analysis was done using scanning electron microscope (SEM). Data were analyzed by one-way ANOVA and Post Hoc test with 95% level of significance (p<0.05). Results: Group D, which was treated with glutathione and restored after one week, revealed the highest shear bond strength compared to group B which was immediately restored following treatment with glutathione. Conclusion: Addition of 20% Glutathione as an antioxidant increased the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. [ABSTRACT FROM AUTHOR]

This study primarily focused on the acid erosion of enamel and dentin. A detailed examination of the X-ray diffraction data proves that the products of the acid-caused decay of enamel belong to the family of isomorphic bioapatites, especially calcium-deficient hydroxyapatites. They are on a trajectory towards less and less crystallized substances. The increase in Bragg's parameter d and the decrease in the energy necessary for the changes were coupled with variability in the pH. This was valid for the corrosive action of acid solutions with a pH greater than 3.5. When the processes of natural tooth aging were studied by X-ray diffraction, a clear similarity to the processes of the erosion of teeth was revealed. Scarce data on osteoporotic bones seemed to confirm the conclusions derived for teeth. The data concerning the bioapatite decays were confronted with the cycles of apatite synthesis/decay. The chemical studies, mainly concerning the Ca/P ratio in relation to the pH range of durability of popular compounds engaged in the synthesis/decay of apatites, suggested that the process of the formation of erosion under the influence of acids was much inverted in relation to the process of the formation of apatites, starting from brushite up to apatite, in an alkaline environment. Our simulations showed the shift between the family of bioapatites versus the family of apatites concerning the pH of the reaction environment. The detailed model stoichiometric equations associated with the particular stages of relevant processes were derived. The synthesis processes were alkalization reactions coupled with dehydration. The erosion processes were acid hydrolysis reactions. Formally, the alkalization of the environment during apatite synthesis is presented by introducing Ca(OH)2 to stoichiometric equations. [ABSTRACT FROM AUTHOR]

Objectives Materials and Methods Results Conclusions Clinical Significance To evaluate the influence of preheating and water storage on color, whiteness, and translucency of one‐shaded, group‐shaded, and multi‐shaded resin‐based composites.A total of 270 samples were fabricated from one‐shaded (Omnichroma), group‐shaded (Optishade MD), and multi‐shaded (Enamel Plus HRI) resin‐based composites and divided into six groups: no heating (control) and 1–5 heatings (test) (n = 15). The CIE L*, a*, b*, C*, and h° color coordinates were registered over white, black, and gray backgrounds with a spectrophotometer before and after 24, 72, 144 h water storage. Kruskal–Wallis test was used to evaluate differences in the color coordinates, whiteness index, and translucency parameter (α = 0.05). The Mann–Whitney U test was performed with a Bonferroni correction (p < 0.001) for pairwise comparisons. CIEDE2000 color, whiteness, and translucency differences between groups and subgroups were evaluated using their respective 50%:50% perceptibility and acceptability thresholds.Preheating influenced color coordinates, whiteness index, and relative translucency parameters (p < 0.001). Although color differences were below the acceptability threshold for all materials, translucency differences were above the acceptability threshold for Omnichroma. Water storage significantly influenced the whiteness index of Optishade MD (p < 0.001).Preheating had a more considerable effect on the color, whiteness, and translucency of one‐shaded resin‐based composite, while water storage influenced group‐shaded resin‐based composite more importantly.Preheating influences the color, whiteness level, and translucency of the resin‐based composites, but the variations remain generally clinically acceptable; however, practitioners should be aware that the modifications in translucency for one‐shaded resin‐based composites could be more important than for group‐shaded and multi‐shaded resin‐based composites. [ABSTRACT FROM AUTHOR]

Introduction: This in situ study investigated the protective effect of a solution containing statherin-derived peptide (StatpSpS) against enamel intrinsic erosion (ERO). Methods: Fifteen volunteers wore appliances containing 2 bovine specimens. The samples were subjected to ERO with HCl, mimicking dental ERO by intrinsic acid. The volunteers participated in 3 phases (double-blind and crossover): (1) deionized water (negative control); (2) commercial solution containing SnCl2/NaF/AmF (800 ppm Sn+2, 500 ppm F−, pH 4.5) (positive control); (3) solution containing 1.88 × 10−5m StatpSpS. Four times a day, the volunteers administered one drop of the solutions (50 μL, 1 min) on each specimen. After the treatment, erosive challenges were performed extraorally with 0.01 m HCl (pH 2.0, 4 times/day, 1 min, 150 mL). Enamel wear was assessed by profilometry. Data were analyzed by one-way RM-ANOVA/Bonferroni’s tests (p < 0.05). Results: In terms of the treatments, both the commercial solution (SnCl2/NaF/AmF) and StatpSpS significantly reduced the wear when compared to the negative control (p < 0.01), without significant differences between them (p > 0.05). Conclusion: The solution containing StatpSpS demonstrated protection against enamel intrinsic erosive wear. This study marks a significant advancement in the prevention of intrinsic erosive wear, utilizing StatpSpS in acquired pellicle engineering procedures. [ABSTRACT FROM AUTHOR]

Purpose: To compare the impact of four effervescent vitamin tablets on the surface roughness, microhardness, and color of human enamel and contemporary composite resins. Material and Methods: Sixty enamel and a total of 240 anterior (Gradia Direct Anterior), posterior (Gradia Direct Posterior), and universal composite resin (Filtek Ultimate) specimens (n = 60 per group) were fabricated. Each group was subdivided into five subgroups (n = 12, per subgroup). The specimens were subsequently immersed in YOUPLUS, Redoxon, Sunlife Immuvit, and Sambucol effervescent vitamin solutions for 2 min per day over 30 days. Distilled water was used as control. Subsequently, surface roughness (Ra) was detected using a profilometer, and microhardness (VHN) was measured using a microhardness tester. A spectrophotometer device was used to record the L,a,b color coordinates of the specimens after 24 h, 7 days, and 30 days, and the color changes (ΔE00) of the groups were calculated. The data were analyzed by ANOVA, two‐way ANOVA, Kruskal‐Wallis, Levene's, and Fisher's least significant difference (LSD) tests (p < 0.05). SEM analysis was conducted on one randomly selected specimen per group (×1000). Results: In terms of surface roughness, material X vitamin interactions were found significant (p < 0.05). The increase in Ra from 24 h to 30 days was found significant (p < 0.05) except for Gradia Direct Anterior X Redoxon, Sunlife Immuvit and Sambucol, Filtek Ultimate X Sunlife Immuvit and Sambucol, and all control groups. Ra changes were also concluded by SEM. Regarding VHNs, material X vitamin interactions were significant (p < 0.005), except for all Filtek Ultimate subgroups. The changes in VHNs of the groups from 24 h to 30 days were significant for all enamel and Gradia Direct Anterior X YOUPLUS, Gradia Posterior X YOUPLUS, Sunlife Immuvit, and Sambucol groups (p < 0.05). In terms of ΔE00, significant differences were observed between the 7 days and 30 days in the enamel (p = 0.047), Gradia Direct Anterior (p = 0.019), and Gradia Direct Posterior groups (p = 0.038). Conclusions: Daily consumption of effervescent vitamin tablets can increase surface roughness, decrease microhardness, and influence the color of human enamel and contemporary anterior, posterior, and universal composite resins after a 30‐day period. [ABSTRACT FROM AUTHOR]

This study investigated the effects of different solutions (artificial saliva, Listerine Cool Mintalcohol containing and Colgate Plax-alcohol free) on the nanohardness, elastic modulus and surface roughness of enamel surface and composite materials (Admira Fusion, Clearfil Majesty Esthetic and Mosaic Universal). Specimens of 2 mm depth and 5 mm diameter were stored in solutions for 12 h at 37°C. Baseline and final measurements were obtained using a HYSITRON TI 950 TriboIndenter testing machine. The applied force to each specimen increased from 0 to 1000 µN. For SEM images, one sample in each group was covered with a thin layer of mix of gold and palladium using a sputter coater (Quorum Q150R ES, UK). Scanning electron microscopy (SEM) images were taken at 5000× magnifications to evaluate the surface morphology. Statistical analysis for hardness, elastic modulus and roughness was performed by Two-way ANOVA, Benferroni and Tukey HSD at a significance level 0.05. The results of this study showed that the highest value of surface roughness and lowest hardness and elastic modulus were presented by Admira (p<0.001). Listerine caused significantly increased surface roughness (p<0.001) and decreased hardness and elastic modulus parameters (p<0.001). The mouthrinse containing alcohol caused more significant changes in the nanohardness, elastic modulus, surface roughness values of enamel and composite surfaces. [ABSTRACT FROM AUTHOR]

(1) Background: This study aimed to establish the effect of calcium lactate enamel pretreatment related to different fluoride types and concentrations on the enamel uptake of alkali-soluble fluorides. (2) Materials: In a blind and randomized in vitro study, a total of 60 teeth are used. The first 30 teeth were cut and randomly allocated into one of the following treatments: (A) calcium lactate pretreatment followed by three different fluoride solutions; (B) the "Fluoride only" group, with slabs treated with three different fluoride solutions; (C) the "Calcium only" group, with slabs treated with calcium lactate solution; (D) slabs treated with deionized water (negative control group). The next 30 teeth underwent all the above described group procedures but were treated with lower fluoride concentrations. Fluoride was extracted from enamel using 1 M KOH solution and analyzed using a fluoride ion-specific electrode. (3) Results: The findings revealed that slabs treated with NaF following calcium lactate pretreatment exhibited significantly greater enamel uptake of alkali-soluble fluoride compared to other substrates. This significant effect was not observed at lower fluoride concentrations. (4) Conclusion: The study demonstrates that pretreatment with calcium lactate followed by treatment with NaF at 226 ppm F significantly enhances the uptake of alkali-soluble fluoride in enamel compared to other fluoride types. [ABSTRACT FROM AUTHOR]

We present portable X‐ray fluorescence data on the composition of body, glaze and enamels of several Meissen porcelain objects associated with the Hoym–Lemaire Affair (1728–1731). In 1728, the French merchant Rodolphe Lemaire convinced the Meissen Porcelain Manufactory into making copies of Japanese Kakiemon porcelain for sale as originals in Paris, a dubious enterprise that depended on the development of additional pigments closely emulating the Kakiemon palette. We shall illustrate how the color formulations for these objects, designed to imitate Japanese porcelain, differ from those on earlier porcelain from 1723–24, as well as later (mid‐18th century) objects. In all cases, the colorant chemistry can be related to special recipes introduced by Johann Gregorius Höroldt specifically for this purpose and preserved in the Meissen archives. A surprising observation is the absence of antimony or tin in the yellow colorant. As an ancillary finding, we have confirmed analytically for the first time that unmarked, undecorated Meissen porcelain in storage since prior to 1725 was decorated around 1730 and became part of the Hoym–Lemaire shipment. [ABSTRACT FROM AUTHOR]

To comparatively evaluate the amount of wear of natural enamel against a glazed full coverage monolithic zirconia crown and a polished monolithic zirconia crown at 6 and 12 months. Materials and Methods: Thirty subjects within the age range of 18 to 35 years participated in this study. The subjects received a total of 60 single crowns, which were divided into two groups: (1) 30 glazed monolithic zirconia crowns opposed by natural enamel (group A); and (2) 30 polished monolithic zirconia crowns opposed by natural enamel (group B). Each subject received a crown from both groups, placed bilaterally in endodontically treated maxillary or mandibular first molars. An impression was made of the opposing arch at 24 hours, 6 months, and 12 months. The resulting casts were scanned with a 3D optical scanner. The recall scans were superimposed and compared to baseline scans using 3D AutoCAD software. A control group was included to compare the wear values to natural enamel against natural enamel. Results: No significant difference (P = .855) was found in enamel wear between groups A (42.80 µm) and B (42.50 µm) after 6 months of use. However, a significant difference (P < .05) in enamel wear was found between group A (81.87 µm) and group B (71.43 µm) after 12 months of use. Conclusion: Glazed monolithic zirconia crowns cause more wear to the opposing enamel than polished monolithic zirconia crowns after 12 months of clinical use. [ABSTRACT FROM AUTHOR]

To compare the effect of office, home, and internal bleaching on the shear bond strength (SBS) of enamel to porcelain laminate veneers. Materials and Methods: A total of 36 extracted maxillary central incisors were randomly assigned to four groups: (1) no bleaching (control); (2) office bleaching with 40% hydrogen peroxide (HP); (3) home bleaching with 15% carbamide peroxide; and (4) intracoronal bleaching with sodium perborate (SP) using the walking bleaching technique. All teeth were separately immersed in artificial saliva for 14 days. The enamel surface was then reduced by 0.5 mm, and IPS e.max Press ceramic discs were bonded using a resin cement. After 24 hours, all specimens were thermocycled (5,000 cycles, 5°C to 55°C). The SBS was measured using a universal testing machine, and the failure mode was determined using a stereomicroscope. One-way ANOVA and Tukey honest significant difference tests were used for data analysis (P < .05). Results: A significant difference was noted among the groups (P < .001). The highest SBS was noted in the control group (15.71 ± 5.39 MPa). The mean SBS in the office bleaching group (12.30 ± 4.64 MPa) was almost the same as the control. The lowest mean SBS belonged to the home bleaching group (5.39 ± 3.99 MPa). The mode of failure was adhesive in all four groups. Conclusion: If bleaching is intended to be followed by porcelain veneers, the office bleaching technique with 40% HP is recommended. Delaying the bonding procedure for 2 weeks does not appear to be effective with home or intracoronal bleaching. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the microleakage of light-cured and self-cured adhesives on enamel surfaces selectively etched with Er, Cr: YSGG laser or 35% phosphoric acid. A total of 60 class V cavities were prepared 1 mm above the cemento-enamel junction (CEJ). The specimens were randomly divided into six groups. Group 1: Clearfil SE Bond with no conditioning, Group 2: Tokuyama Universal Bond with no conditioning, Group 3: Clearfil SE Bond conditioned with 35% phosphoric acid, Group 4: Tokuyama Universal Bond conditioned with 35% phosphoric acid, Group 5: Clearfil SE Bond conditioned with Er, Cr: YSGG laser and Group 6: Tokuyama Universal Bond conditioned with Er, Cr: YSGG laser. Microleakage was evaluated qualitatively (visually) and quantitatively (ImageJ). The data were analyzed using IBM SPSS V23 and submitted to Kruskal–Wallis and Wilcoxon tests. The significance level was set at p < 0.05. In all evaluation methods, the microleakage scores exhibit significant differences (p*<0.001). Group 1 and Group 3 exhibited similar and lower microleakage values than the Group 5. In the occlusal margin, the microleakage values were similar in Group 2, Group 4, and Group 6, whereas in the gingival margin Group 4 showed significantly lower leakage compared to Group 2. Regardless of the etching protocols and adhesive systems used, less microleakage was observed on the occlusal surface than on the gingival surface. Phosphoric acid etching provides better results than laser etching for enamel surface treatment on both occlusal and gingival surfaces. [ABSTRACT FROM AUTHOR]

Objectives: To compare the effect of bleaching agents based on carbamide peroxide in different concentrations on the microhardness of bovine enamel. Material and Methods: In vitro study. 60 samples of bovine enamel were used, divided into two groups according to the assigned agent: carbamide peroxide (Opaslescense PF, Ultradent), at 35% and 15%. Next, the bleaching agent was applied to the samples, according to the manufacturer's instructions. The surface microhardness of enamel was evaluated by Vickers microhardness test, before and after application of the bleaching agent. The relationship between variables was evaluated using Student's t-test. Results: The study found no significant differences between the microhardness groups treated with 15% and 35% carbamide peroxide, both at the beginning and after the application of the bleaching agent (p:0.160 and p:0.584 respectively). However, when considering the concentrations separately, both bleaching agents caused a decrease in the microhardness of the enamel (p<0.001 in both cases). Conclusions: Both bleaching agents caused a decrease in the superficial microhardness of the enamel, the effect was similar for both concentrations. [ABSTRACT FROM AUTHOR]

The paper discusses the formation of an enamel defect in the crown of a cave bear (Ursus spelaeus sensu lato) left maxillary second molar (M2), based on macroscopic and microscopic analysis. The tooth belongs to a cranium recovered from the Cerovac caves in Croatia that exhibits a partially healed, depressed lesion in the left squama frontalis and a further lesion in the left maxilla associated with loss of the M1. Microscopic inspection demonstrated an accentuated incremental line in both enamel and dentin of the left M2. It is suggested that in the defect area the outer enamel had been posteruptively lost along the accentuated line in the enamel that constituted a zone of reduced mechanical resistance. Presence of enamel hypoplasia in both M2 indicated that these developmental lesions reflect a systemic stress event during crown formation of the teeth. The underlying cause of this stress is assumed to have been a trauma to the skull that caused the lesion in the left squama frontalis. It is further suggested that a later trauma to the left maxilla had led to the loss of the left M1 and the flaking‐off of enamel along the accentuated incremental line in the left M2. The defect in the left M2 is thus diagnosed as the result of a developmental lesion during crown formation, related to systemic stress due to a skull trauma, followed by posteruptive damage from a second traumatic impact. In addition to reconstructing the formation of the defect in the crown of the left M2, the paper, for the first time, describes daily and subdaily incremental markings in ursid enamel and provides preliminary information on enamel secretion rate in a cave bear molar. [ABSTRACT FROM AUTHOR]

Objectives: Among low‐latitude apes, developmental defects of enamel often recur twice yearly, linkable to environmental cycles. Surprisingly, teeth of Homonaledi from Rising Star in South Africa (241–335 kya), a higher latitude site with today a single rainy season, also exhibit bimodally distributed hypoplastic enamel defects, but with uncertain timing and etiology. Newly determined Retzius periodicities for enamel formation in this taxon enable a reconstruction of the temporal patterning of childhood stress. Methods: Using high resolution casts of 31 isolated anterior teeth from H. naledi, 82 enamel defects (linear enamel hypoplasia [LEH]) were identified. Seventeen teeth are assigned to three individuals. Perikymata in the occlusal wall of enamel furrows and between the onsets of successive LEH were visualized with scanning electron microscopy and counted. Defects were measured with an optical scanner. Conversion of perikymata counts to estimates of LEH duration and inter‐LEH interval draws upon Retzius periodicities of 9 and 11 days. Results: Anterior teeth record more than a year of developmental distress, expressed as two asymmetric intervals centered on 4.5 and 7.5 months bounded by three LEH. Durations, also, show bimodal distributions, lasting 3 or 12 weeks. Short duration LEH are more severe than long duration. Relative incisor/canine rates of formation are indistinguishable from modern humans. Discussion: We invoke a disease and dearth model, with short episodes of distress reflecting onset of disease in young infants, lasting about 3 weeks, followed by a season of undernutrition, possibly intensified by secondary plant compounds, spanning about 12 weeks, inferably coincident with austral winter. [ABSTRACT FROM AUTHOR]

Both the corrosion resistance and bond strength of silica particle-modified enamel (SPME)-coated steel bars are experimentally investigated, and uncoated and pure enamel (PE)-coated bars are also prepared for comparison. The microstructure of SPME coating is analyzed by using scanning electron microscopy (SEM), and the corrosion performance in simulated concrete pore solutions is assessed by using a series of electrochemical techniques. Pull-out tests were conducted to obtain the bond behavior with concrete. SEM images show that silica particles are completely embedded in the enamel matrix. The corrosion resistance of SPME-coated smooth and deformed steel bars is 68 and 28 times lower, respectively, than that of the uncoated bars. The bond strength, bond stiffness, bond ductility, and bond toughness of SPME-coated smooth steel bars are 4.33, 4.61, 35.86, and 20.66 times greater than those of the uncoated bars, while they are 1.29, 4.72, 2.21, and 1.24 times greater than those of the uncoated ones for the deformed steel bars. SPME-coated steel bars can be used to enhance the seismic performance of reinforced concrete structures in earthquake-prone zones, while also improving corrosion resistance. [ABSTRACT FROM AUTHOR]

Enamel formation is a highly complex and regulated process. However, specific genetic mutations can cause dysregulation, resulting in defects in the enamel quantity, structure and composition. Inherited disorders such as amelogenesis imperfecta exclusively affect the formation of enamel. Nevertheless, enamel defects can also present as a feature of many inherited systemic diseases and syndromes. The defects present in a spectrum of mild to severe enamel pitting, mottling and loss of email, causing psychological and functional concerns for patients. Early diagnosis and intensive caries prevention along with a multidisciplinary specialist input are required in most cases. In this paper, we provide a comprehensive discussion of inherited enamel defects. [ABSTRACT FROM AUTHOR]

Enamel coatings, showing advantages in material durability, aesthetics, hardness, corrosion resistance, and high-temperature tolerance, are widely used for corrosion protection of metallic substrate. Recently, a new type of aluminophosphate-based low temperature enamel (LTE) coating was developed to avoid the strength degradation of steel substrate, which was also applicable to relatively low-melting metal and was more environmentally friendly with reduced energy consumption. LTE coating might suffer the corrosion of acids or alkalis in some special cases like kitchen utensils, petroleum pipelines, and reinforcing bars. In this study, the chemical corrosion behavior of aluminophosphate-based LTE was investigated in H 2 SO 4 and NaOH solutions with varying pHs of 1∼13. Results indicated that after 30 days of immersion, LTE survived at pHs 3–10, but severely deteriorated at pHs 1, 2, 12, and 13, with the corroded layer presenting a loose structure, completely losing mechanical strength, and even peeling off. For pH 11, the color changed slightly whereas the mass loss was negligible. Specially, LTE suffered selective corrosion in strong acid and alkali conditions, that is, H 2 SO 4 corroded the Ca-compounds (Ca 5 (PO 4) 3 F and CaF 2) phases to generate CaSO 4 ·2H 2 O and H 3 PO 4 , whereas NaOH corroded the LTE matrix (AlPO 4) to generate soluble Na 3 PO 4 and NaAlO 2. The findings of this study confirmed the acid and alkali tolerance range of LTE and clarified the corrosion mechanism of LTE under both acid and alkaline environments, which guides the further composition design and application of LTE coatings. [ABSTRACT FROM AUTHOR]

Background: To evaluate the effect of the low-viscosity Icon resin infiltrate application on the color change of white spot enamel lesions (WSLs) over 3-, 6-, and 12-m follow-up periods. Methods: Ninety-six teeth diagnosis with WSLs using the ICDAS scoring system in 49 participants were assessed for their color change using the Icon resin infiltration technique. The Icon kit was applied to WSLs as instructed by the manufacturer. Icon-Etch (15% hydrofluoric acid) was applied to the lesions for 2 min, and then, it was rinsed off with copious amount of water for 30 s. Then, Icon-Dry (99% ethanol) was applied to the etched lesions for 30-s followed by the application of the Icon resin infiltrate that was light cured for 40 s. Color change assessment was performed using Vita Easyshade V spectrophotometer at baseline and immediately after Icon resin infiltration, then at 3-, 6-, and 12-m follow-up periods. Analysis of the data was performed using the test of repeated measure ANOVA and the paired sample t test. Results: There was a statistically significant difference in ∆E between the different follow-up periods at immediate, 3-m, 6-m, and 12-m. The highest mean value was found in the immediate follow-up period, while the lowest mean value was found in 12-m follow-up period. Conclusions: Low-viscosity Icon resin infiltration has the ability for immediate diffusion into the WSLs giving an immediate improvement in the esthetic outcome of the WSLs. However, its long-term outcomes might not be consistent for the color change of the WSLs. [ABSTRACT FROM AUTHOR]

To evaluate and compare the bond strength of bulk fill composite when bonded to enamel or dentin pretreated with different concentrations of fluoride (F) compounds using a universal adhesive. A total of 120 teeth were used, including 40 enamel specimens and 80 dentin specimens. Enamel specimens were ground flat, while dentin specimens were prepared by cutting until mid-coronal dentin. The teeth were divided into four groups (n = 30) to test the F-based agents: 1.23% acidulated phosphate fluoride (APF), 1.1% neutral sodium fluoride (NSF), 0.4% stannous fluoride (SF), and a control group without F pretreatment. Each agent was applied for 30 s and rinsed before bonding. Enamel specimens underwent phosphoric acid etching (ER), while dentin specimens were bonded using either ER or self-etch (SE) protocols. Microtensile bond strength testing (μTBS) was performed after 24 h or 10,000 thermal cycles, and failure patterns were assessed. The study variables did not significantly affect μTBS values of enamel specimens. However, all study variables had a significant effect on μTBS values of dentin specimens. The ER protocol, after both control and SF pretreatment, exhibited the highest μTBS values. Pretreatment of enamel with different concentrations of F prior to bonding appears to be safe in terms of bond durability. However, pretreatment with F concentrations higher than 1000 ppm adversely affected bonding to dentin. Pretreating tooth structure with F-based agents at concentrations below 1000 ppm prior to bonding shows promise as a viable option without compromising bond durability. [ABSTRACT FROM AUTHOR]

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Context and Aims: This study evaluated the effect of calcium silicate and sodium phosphate (CSSP) dentifrice and serum on the surface of enamel bleached with hydrogen peroxide (H2O2). Materials and Methods: A total of 160 bovine enamel slabs were bleached with 35% H2O2 and treated with sodium fluoride (NaF) dentifrice-GI, CSSP dentifrice-GII; CSSP dentifrice + CSSP serum-GIII, or NaF dentifrice + NaF gel-GIV. The dentifrices were applied using a brushing machine three times daily for 7 days. After brushing, sodium phosphate gel and CSSP serum were applied. The microhardness (KNH, n = 14), surface roughness (Ra, n = 14), energy dispersive spectroscopy (n = 6), and scanning electron microscopy (n = 6) were assessed at t0 (before bleaching), t1 (after bleaching), and t2 (after postbleaching treatments). Statistical Analysis Used: The data were subjected to a two-way analysis of variance and Bonferroni's test. Results: The KNH decreased at t1 (P < 0.001) but recovered at t2 for all treatments, although only GII showed restored baseline values (P = 0.0109). The surface roughness increased at t1 (P < 0.001) and reduced at t2 (P < 0.001) for all groups, with no significant differences among groups. Enamel composition and morphology did not differ after the treatments, except for silicon accumulation in GIII. Conclusions: Postbleaching treatment with CSSP dentifrice and serum yielded superior remineralizing effects on bleached enamel. [ABSTRACT FROM AUTHOR]

Enamel remineralization, which attempts to generate a mineral layer structurally similar to native enamel and restore its mechanical properties, remains a significant challenge. Here, rationally designed peptide amphiphile (PA) molecules bind to amorphous calcium phosphate (ACP) particles via electrostatic interactions, imparting anisotropic properties that drive PA‐modified ACP to form spindle‐shaped aggregates. Furthermore, some residual PA molecules may further regulate crystallization and facilitate the formation of well‐aligned hydroxyapatite bundles. Additionally, the involvement of PA can mediate the ordered deposition and fusion of ACP on the enamel surface, and construct the crystalline‐amorphous mineralization front with a continuous structure. This mineralization front ensures epitaxially oriented growth of enamel crystals and achieves a structurally ordered mineral layer similar to that of native enamel, while the mechanical performance is effectively restored. More significantly, the thickness of the newly formed mineral layer can be augmented through cyclic remineralization, benefitting the design of products intended for practical enamel repair. [ABSTRACT FROM AUTHOR]

Objectives: A modern pattern (rate and duration) of dental development occurs relatively recently during human evolution. Given the temporal overlap of Homonaledi with the first appearance of fossil Homo sapiens in Africa, this small‐bodied and small‐brained hominin presents an opportunity to elucidate the evolution of enamel growth in the hominin clade. Here we conduct the first histological study of two permanent mandibular canines and one permanent maxillary first molar, representing three individuals attributed to H. naledi. We reconstruct the rate and duration of enamel growth and compare these findings to those reported for other fossil hominins and recent humans. Materials and Methods: Thin sections of each tooth were produced using standard histological methods. Daily and longer period incremental markings were measured to reconstruct enamel secretion and extension rates, Retzius periodicity, canine crown and molar cusp formation time. Results: Daily enamel secretion rates overlapped with those from recent hominins. Canine crown formation time is similar to that observed in recent Europeans but is longer than canine formation times reported for most other hominins including Australopithecus and H. neanderthalensis. The extended period of canine formation appears to be due to a relatively tall enamel crown and a sustained slow rate of enamel extension in the cervical portion of the crown. A Retzius periodicity of 11 days for the canines, and nine days for the molar, in H. naledi parallel results found in recent humans. An 11‐day periodicity has not been reported for Late Pleistocene Homo (H. erectus, H. neanderthalensis) and is rarely found in Australopithecus and Paranthropus species. Discussion: Enamel growth of H. naledi is most similar to recent humans though comparative data are limited for most fossil hominin species. The high Retzius periodicity values do not follow expectations for a small‐brained hominin. [ABSTRACT FROM AUTHOR]

Anterior teeth restoration represents a challenge for dentists, who often rely on the dental technician's wax-up. The proposed Stratified Stamp Technique (SST) allows for clinically reproducing the wax-up in a quick and easy way. A patient with fractures and discoloration on the upper central incisors was treated with resin-based composite direct restorations. Using SST, a 1 mm thick thermoformed polyethylene-terephthalate-glycol (PETG) template, based on the technician's wax-up, was produced. Enamel Selective Area Reduction (SAR) was performed to guarantee adequate space for the restorations, and the fracture margins were rounded and finished. Traditional layering procedures according to the five color dimensions of teeth were performed, except for the final labial layer, which was realized with warm composite loaded inside the template and polymerized through it, in order to ensure accurate tooth morphology reproduction. SST offers a reliable method for transferring technician's wax-up morphology to direct composite restorations in anterior teeth. Compared with other methods, SST allows for better isolation with a rubber dam and permits traditional layering with multiple composite shades, thus leading to satisfactory esthetic outcomes. [ABSTRACT FROM AUTHOR]

Evaluate the ability of strontium fluoride on bond strength and enamel integrity after incorporation within orthodontic adhesive system as a delivery vehicle. Experimental orthodontic adhesive system Transbond™ XT were modified with 1% Sr2+, 0.5% SrF 2 , 1% strontium, 0.5% Sr2+, 1% F-, 0.5% F-, and no additions were control. Mixing of formulation was monitored using Fourier transform infrared spectroscopy. Small-molecule drug-discovery suite was used to gain insights into Sr2+, F-, and SrF 2 binding. Shear bond testing was performed after 6-months of ageing. Enamel blocks were cut, and STEM pictures were recorded. Specimens were indented to evaluate elastic modulus. Raman microscope was used to collect Raman spectra and inspected using a scanning electron microscope. Crystal structural analysis was performed using X-ray diffraction. Effect of material on cellular proliferation was determined. Confocal was performed to evaluate the effect of formulation on biofilms. FTIR of modified adhesives depicted peak changes within range due to various functional groups existing within samples. TEM represented structurally optimized hexagonal unit-cell of hydroxyapatite. Mean shear bond strength is recorded highest for Transbond XT with 1% SrF2. Dead bacterial percentage appeared higher in 0.5% SrF 2 and 1% F- specimens. Crystal lengths showed an increase in 0.5% and 1% SrF 2 specimens. Phase contrast within TEM images showed a union of 0.5% SrF 2 crystal with enamel crystal with higher elastic modulus and highly mineralized crystalline hydroxyapatite. Intensity of ν1 PO 4 3- and ν1 CO 3 2- along with carbonate - / ν1PO 4 3- ratio displayed good association with strontium fluoride. The formulation showed acceptable cell biocompatibility (p < 0.353). All specimens displayed characteristic diffraction maxima of different apatite angles within XRD. Experimental results suggested good biocompatibility, adequate mechanical strength, and far-ranging crystallization ability. This would provide a new strategy to overcome the two major challenges of fixed orthodontics, biofilm growth, and demineralization of enamel. [ABSTRACT FROM AUTHOR]

Adhesive dentistry is an essential component in the delivery of direct and indirect restorations. Ongoing discussions among scientists and clinicians have focused on whether or not current self-etch and universal adhesives adequately prepare enamel surfaces to achieve optimal bond strengths. To address these concerns, a selective enamel etch technique has been recommended. The definition of a selective enamel etch technique is as its name suggests. The clinician selectively etches the enamel of a cavity preparation by applying phosphoric acid etchant to the enamel surfaces of the preparation while refraining from applying the etchant to the dentin. This article explores the current research to help guide clinicians to achieve ideal outcomes when using dental adhesives. With few exceptions, the current scientific evidence recommends a selective enamel etch technique in conjunction with the clinician’s adhesive system of choice. [ABSTRACT FROM AUTHOR]

Enamel interproximal reduction (IPR), also known as stripping, is an orthodontic procedure used by many clinicians, especially in non-extraction cases. It aims to reduce the mesiodistal diameter of teeth by removing interproximal enamel. This therapeutic option allows to obtain space in the dental arch to achieve tooth alignment, in case of mild or moderate crowding, and to preserve the papilla avoiding the onset of black triangles. IPR is an irreversible procedure, and it requires an accurate case examination to avoid damage, such as demineralization of the enamel or periodontal complications, that can compromise both aesthetics and oral health. When performing IPR, orthodontists can change the contact point between the teeth and move it closer to the alveolar crest, thus improving esthetics by reducing the black triangles. However, there is also a risk for worsening periodontal health due to root proximity although, according to the literature, periodontal indices, such as clinical attachment loss (CAL) and bleeding on probing (BOP), seem to be not significantly affected by IPR. [ABSTRACT FROM AUTHOR]

To assess color and translucency change (∆E00 and ∆TP) of 3D-printed (Varseosmile crown plus, VS) and milled resin-ceramic hybrid material (Cerasmart, CS) compared to enamel (E) when immersed in distilled water (DW) and coffee (C). Sixty VS, CS, and E specimens were immersed in DW and C for 30 days. Statistics analysis using t-test and one-way ANOVA at p≤0.05. ∆E00 of VS, CS, and E significantly increased when immersed in coffee (p<0.001, p<0.001 and p=0.01, respectively). E has more ∆E00 than VS and CS (p<0.001). The translucency of VS and CS was reduced after water and coffee immersion. The translucency of E was increased after immersion in water and coffee. ∆TP of VS, CS, and E were not different between immersion in water and coffee at p=0.08, p=0.43 and p=0.72, respectively. Therefore, DW and C have distinct effects on the ∆E00 and ∆TP among VS, CS and E. [ABSTRACT FROM AUTHOR]

The article investigates the wear and friction properties of oscillating strips used for interproximal enamel reduction (IPR) to validate the importance of a standardized sequence for preserving efficiency and lifetime. Topics discussed include the mechanical and tribological evaluation of the strips, qualitative and quantitative assessments of wear patterns, and the impact of prolonged usage on strip performance.

Aims: Minimal enamel loss during bonding and debonding operations is ideal for preserving the enamel surface in fixed orthodontic treatment. This study aimed to assess the enamel surface after debonding conventional and self-ligating metal and ceramic brackets and compare their enamel damage index (EDI) and adhesive remnant index (ARI) using scanning electron microscopy (SEM). Materials and Methods: Thirty-two maxillary first premolar teeth were divided into four equal groups of eight teeth each. According to the type of brackets used, the teeth were set on acrylic blocks that were color-coded: Conventional metal brackets (ORMCO MINI 2000), Self-ligating metal brackets (ORMCO DAMON Q), conventional ceramic brackets (ORMCO SYMETRI CLEAR), and self-ligating Ceramic brackets (ORMCO DAMON CLEAR). After debonding was done using a straight debonding plier, the tooth surfaces were examined by SEM. The ARI and EDI were then evaluated. The Kruskal-Wallis test was used in inferential statistics to determine differences between the groups. The association between the ARI and the EDI was determined using the Pearson correlation test. Results: The ARI revealed lower values for teeth bonded with traditional ceramic brackets, along with higher scores in the EDI. This suggests that the enamel-resin interface was the primary site of bond failure, potentially leading to iatrogenic tooth surface damage from ceramic bracket debonding. Conversely, self-ligating stainless-steel brackets had the lowest EDI scores and higher ARI values, suggesting that the resin-bracket interface was the primary site of bond failure. Additionally, this group showed minimal to no enamel damage, with only a few enamel cracks observed. Conclusion: Self-ligating metal brackets showed the highest ARI scores and lowest EDI scores, whereas conventional ceramic brackets presented with lowest ARI scores and highest EDI scores. The enamel surfaces attached with ceramic brackets showed greater enamel cracks upon SEM analysis. [ABSTRACT FROM AUTHOR]

This systematic review examines studies focusing on tooth bleaching and its effects on healthy enamel or incipient caries and bacterial adhesion. The aim is to explore the impact of different bleaching agents on incipient caries lesions and healthy enamel. Clinical studies, in vitro studies, and observational studies that compared at least two groups were included. A search strategy was used to select studies from the MEDLINE via Pubmed and Scopus databases. Two evaluators performed data extraction, screening, and quality assessment independently. Only studies written in English were included. From 968 initial records, 28 studies were selected for a full-text evaluation. Of these, 7 studies were classified as cluster 1 (bacterial adherence on teeth), 12 studies as cluster 2 (no bacteria involved), 4 studies as cluster 3 (no teeth deployment), and 5 clinical studies were cluster 4. Of the selected studies, 6 (21.4%) supported increased bacterial attachment capacity and cariogenic dynamics, 4 (14.3%) decreased adhesion and cariogenic activity, 7 (25%) showed no difference, and 11 (39.3%) followed a different methodological approach and could not be categorized. The risk of bias appeared to be high, mainly because of the different methodologies in the studies, so we cannot reach a confident conclusion. Nevertheless, as far as carbamide peroxide bleaching is concerned, there does not seem to be a clinically significant alteration, neither in microorganism counts nor in enamel microstructure. [ABSTRACT FROM AUTHOR]

This study aims to investigate whether toothbrushes with fluoride-infused bristles have any (re)mineralisation effects on bovine enamel. Bovine incisors (N = 160) were extracted, and the buccal side of the crown was cut into dimensions of ~5 mm × 5 mm with a low-speed saw. These specimens were randomly allocated into four groups: half (80 teeth) were stored in demineralising solution (DM), and the other half were stored in deionised water (DW) for 96 h. Then, they were brushed with a force of 2.0 ± 0.1 N for five min with a manual toothbrush with either fluoride-infused (TF) or regular (TR) bristles. Microhardness (Vickers), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were used to investigate the surfaces of the bovine enamel specimens before and after brushing. Two-way ANOVA was used to analyse the hardness data, and the pairwise comparison method was used to analyse the Ca/P ratio, for each group at α = 0.05. The results show that brushing with either of these toothbrushes increased the Vickers microhardness on DM and DW enamel (p < 0.001), whereas hydroxyapatite was revealed in all groups by XRD. The DM samples showed a significant increase (p < 0.05) in the Ca/P ratios after brushing with TR and TF. Conversely, under DW conditions, these ratios decreased significantly after brushing. In terms of the F atomic%, TF increased significantly. SEM revealed mineral deposition in the DM groups after toothbrushing. To conclude, toothbrushing effectively induces the microhardness of sound and demineralised enamel, while fluoride-infused bristles might be able to retain fluoride on the enamel surface. [ABSTRACT FROM AUTHOR]

To investigate the in vivo and in situ effect of different types of lasers in prevention of enamel demineralization in high caries risk cases (around orthodontic brackets, around restoration and in caries susceptible pits and fissures). PubMed was searched using the following keyword sequence; (Laser therapy OR laser irradiation OR laser application) AND (enamel caries prevention OR enamel demineralization OR enamel remineralization OR early enamel caries OR early-enamel caries OR enamel resistance OR enamel decalcification OR white spot lesions WSLs OR incipient lesion OR enamel decay OR enamel Dissolution OR enamel microhardness) AND (clinical trial OR Randomized clinical trial OR In situ study). The latest literature search was ended by "30 January 2023". PubMed was used as a primary data base for study selection. Scopus, EBSCO, and Google scholar are checked in our study after results of systematic search on PubMed. Only duplicates were found. Two meta-analyses were carried out. The first, clinical meta-analysis on incidence of white spot lesions (WSLs) following CO2 laser irradiation of enamel. The second meta-analysis on ex-vivo/in situ effect of CO2 laser on microhardness of enamel. In each meta-analysis three studies were included. Risk of bias was assessed. The search identified eight studies (four ex-vivo and four clinical trials). Regarding the clinical meta-analysis, the overall standardized mean difference was 0.21 [ 95% confidence interval (CI): 0.15–0.30, p < 0.00001]. This indicates that the incidence of new WSLs in patients who received low power CO2 laser treatment was highly significantly lower than placebo groups. The heterogeneity was considerable (I2 = 71%). In the second meta-analysis, the overall standardized mean difference was 49.55 [ 95% confidence interval (CI): 37.74, 61.37, p < 0.00001]. This indicates that microhardness of enamel receiving low power (0.4–5 W) CO2 laser irradiation is highly significantly lower than control untreated enamel. The heterogeneity was substantial (I2 = 48%). Within the limitations of this study, Low level laser therapy concept with CO2 laser seems to be effective in preventing enamel caries. Prospero registration number: CRD42023437379 [ABSTRACT FROM AUTHOR]

Aim: Dental erosion is a chemical-mechanical process that leads to the loss of dental hard tissues. This study aimed to investigate the effect of pomegranate juice on the enamel. Methods: Enamel blocks were randomly divided into three groups: deionized water, cola, and pomegranate juice. The blocks were immersed in the solutions four times a day for 14 days, and stored in artificial saliva for the remaining period. The surface hardness was measured on days 7 and 14. The surface structures of the demineralized blocks were observed via scanning electron microscopy (SEM), and the depth of demineralization was observed via confocal laser scanning microscopy (CLSM). The pH, calcium, and phosphorus levels of the three solutions were analyzed. Results: The microhardness values of the blocks in the pomegranate juice and cola groups decreased with the increase in the demineralization time. The blocks in the pomegranate juice group exhibited large fractures in the enamel column, whereas those in the cola group had pitted enamels with destruction of the interstitial enamel column. Compared with cola group, fluorescent penetration increased in pomegranate juice (P < 0.01). The pH of cola (2.32 ± 0.09) was lower than that of pomegranate juice (3.16 ± 0.16). Furthermore, the calcium content in pomegranate juice was significantly higher than that in cola (P < 0.01). Alternatively, the concentration of phosphorous in cola was significantly higher than that in pomegranate juice (P < 0.01). Conclusion: These findings indicate that pomegranate juice can cause enamel demineralization with an erosive potential comparable to that of cola. [ABSTRACT FROM AUTHOR]

Dental microwear is a common and wellestablished technique which allows the short-term reconstruction of the dietary behaviour in extinct and extant vertebrates, allowing inferences about daily, seasonal, or regional variations in diets. However, the use of this method may be limited because taphonomic processes can affect enamel surfaces and modify or obliterate dietary microwear features. Considering the substantial number of agents which can impact the archaeological record, dental microwear alteration processes are poorly known, producing a potential bias in dietary interpretations. In this study, the effect of trampling on dental occlusal surfaces, one of the most common processes recorded in archaeological assemblages, has been experimentally investigated for the first time. The results allowed us to (1) distinguish taphonomic and dietary marks; (2) assess the impacts of trampling on occlusal surfaces; and (3) infer the agents which modified the dental microwear from the teeth obtained from the archaeological sites. The importance of this work lies in the specific guidelines it offers to discriminate trampling marks from microwear features, improving the reliability of dietary interpretations. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to compare the 2-year clinical performance of a bulk-fill composite resin and a nano-hybrid-filled composite resin in 6-12-year-old children in a split-mouth design. Materials and methods: This randomized, split-mouth, and double-blind study was conducted on 89 patients aged 6–12 years with caries on bilateral mandibular first molars. In a split-mouth design, restorations of mandibular permanent molars were completed with nano-hybrid organically modified ceramic (ORMOCER)-based bulk-fill composite resin Admira Fusion x-tra (Voco GmbH, Cuxhaven, Germany) and nano-hybrid composite Grandio (Voco, Cuxhaven, Germany). Futurabond U single dose (Voco, Cuxhaven, Germany) was used with selective enamel etching. The clinical success of the restorations was evaluated using USPHS and FDI criteria at 6, 12, and 24-month follow-up controls. Results: In the 2-year follow-up, all restorations were clinically acceptable. Grandio was significantly worse than Admira Fusion x-tra in terms of surface luster and superficial change (p < 0.05). Surface staining and color match scores increased in Admira Fusion x-tra compared with Grandio significantly (p < 0.05). Conclusions: Although both materials showed acceptable clinical performance over 2 years, a significant difference was observed between the surface luster, surface staining, marginal adaptation, and staining of the nano-hybrid composite placed with the incremental technique and the bulk-fill ORMOCER-based composite resin. Clinical relevance: As an alternative to nano-hybrid composite resins, using bulk-fill restorative materials, which can be indicated in the proper case, may contribute to shortening treatment procedures and increasing patient and physician comfort, leading to clinical success. [ABSTRACT FROM AUTHOR]

Aim: The current study's aim was to evaluate the potential of various fluoride varnishes to remineralize artificial enamel lesions on primary teeth. Materials and Methods: For the study, 90 deciduous molar teeth that were implicated for extraction were taken. A window region with a size of 3 × 3 mm was located in the middle of the tooth's coronal surface. The remaining portion was given a coat of nail polish and given time to dry. A demineralizing solution was used to create the artificial enamel lesion. The samples were randomized into three experimental groups at random, with 30 samples in each group. Group 1: Application of Clinpro White Varnish, Group 2: Application of Duraphat Varnish, and Group 3: Application of MI Varnish. After 14 days, samples from each group were examined under scanning electron microscopy at a magnification of 1000× to determine whether remineralization had occurred. Microhardness was also determined using a microhardness tester. Result: Before the intervention, the mean demineralized enamel lesion in the Clinpro White Varnish group was 134.44 ± 0.04, in the Duraphat Varnish group was 133.76 ± 0.12, and in the MI Varnish group was 133.89 ± 0.08. After intervention, the maximum remineralized area was found in the MI Varnish group (82.74 ± 0.18) followed by the Clinpro White Varnish group (101.43 ± 0.16) and the Duraphat Varnish group (104.11 ± 0.10). After the intervention, there was a statistically significant difference found between the groups. After the intervention, the maximum microhardness mean value improved in the MI Varnish group (257.03 ± 1.09 to 261.18 ± 1.20) followed by Clinpro White Varnish (258.78 ± 1.64 to 260.10 ± 1.22) and Duraphat Varnish group (255.24 ± 1.51 to 258.02 ± 0.89). Conclusion: According to the findings of the current investigation, all of the varnishes utilized in this in vitro experiment are capable of correcting early enamel defects on primary teeth. However, MI Varnish group was very effective compared to the Clinpro White Varnish group and the Duraphat Varnish group. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate how tluoride- or chitosan-based toothpaste used during at-home bleaching affects enamel roughness, tooth color, and staining susceptibility. Methods: Bovine enamel blocks were submitted to a 14-day cycling regime considering a factorial design (bleaching agent x toothpaste, 2 x 3), with n= 10: (1) bleaching with 16% carbamide peroxide (CP) or 6% hydrogen peroxide (HP), and (2) daily exposure of a fluoride (1,450 ppm F-NaF) toothpaste (FT). chitosan-based toothpaste (CBT), or distilled water (control). Then, 24 hours after the last day of bleaching procedure the samples were exposed to a coffee solution. Color (AE.,b, AEoo, L: a*, b*) and roughness (Ra, kim) analyses were performed to compare the samples initially (baseline), after bleaching, and after coffee staining. The results were evaluated by linear models for repeated measures (L: a: b: and Ra), 2-way ANOVA (AE.,b and AEoo) and Tukey's test (a= 0.05). Results: After the at-home bleaching procedure (toothpaste vs. time, P< 0.0001), the toothpaste groups presented a statistically lower Ra than the control (CBT 0.05). After coffee exposure, CBT presented lower AEat, and AEoo values in the H P groups (toothpaste, P< 0.0001), and lower b* and a* values in the CP groups (toothpaste vs. time, P= 0 .004). [ABSTRACT FROM AUTHOR]

The enamel of mammalian teeth is a highly mineralized tissue that must endure a lifetime of cyclic contact and is inspiring the development of next-generation engineering materials. Attempts to implement enamel-inspired structures in synthetic materials have had limited success, largely due to the absence of a detailed understanding of its microstructure. The present work used synchrotron phase-contrast microCT imaging to evaluate the three-dimensional microstructure of enamel from four mammals including Lion, Gray Wolf, Snow Leopard, and Black Bear. Quantitative results of image analysis revealed that the decussation pattern of enamel consists of discrete diazone (D) and parazone (P) bands of rods organized with stacking arrangement of D+/P/D-/P in all mammals evaluated; the D+ and D- refer to distinct diazone bands with juxtaposed rod orientations from the reference plane. Furthermore, the rod orientations in the bands can be described in terms of two principal angles, defined here as the pitch and yaw. While the pitch angle increases from the outer enamel to a maximum (up to ≈ 40°) near the dentin enamel junction, minimal spatial variations are observed in yaw across the enamel thickness. There are clear differences in the decussation parameters of enamel across species that are interpreted here with respect to the structural demands placed on their teeth. The rod pitch and band width of enamel are identified as important design parameters and appear to be correlated with the bite force quotient of the four mammals evaluated. The multi-functionality of tooth enamel requires both hardness and resistance to fracture, properties that are generally mutually exclusive. Ubiquitous to all mammalian teeth, the enamel is expected to have undergone adaptations in microstructure to accommodate the differences in diet, body size and bite force across animals. For the first time, we compare the complex three-dimensional microstructure of enamel from teeth of multiple mammalian species using synchrotron micro-computed tomography. The findings provide new understanding of the "design" of mammalian enamel microstructures, as well as how specific parameters associated with the decussation of rods appear to be engineered to modulate its fracture resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

INTRODUCTION: The most mineralized and rigid tissue in the human body is tooth enamel. Enamel, the outermost covering of teeth, is made of hydroxyapatite, which is arranged in a well-organized prism structure to absorb loads. De-mineralization occurs when the most widely available and soluble material is removed from the enamel rods' periphery and it is exposed to acids, increasing the enamel's surface porosity, and allowing more acids to diffuse into the tissue and lose mineral ions. OBJECTIVES: To evaluate whether an electrophoresis-aided system improved re-mineralization of de-mineralized enamel more than a traditional technique in rabbits with initial enamel lesions using different re-mineralizing agents. MATERIAL AND METHODS: Initial enamel lesion was produced through acid etching, and three re-mineralizing agents, such as nano-hydroxyapatite, casein phospho-peptide amorphous calcium phosphate, and bioactive glass, were applied to labial surface using traditional or electrophoresis-aided techniques. Surface topography and chemical composition were evaluated using environmental scanning electron microscope/energy dispersive X-ray spectrometer at baseline, after de-mineralization, and after re-mineralization, at different time periods, such as 2 weeks and 5 weeks for a traditional technique, and 3 hours and 5 hours for an electrophoresis-aided technique. RESULTS: Environmental scanning electron microscope showed that re-mineralizing agents enhanced re-mineralization of surface topography following different application periods. Energy dispersive X-ray spectrometer results revealed that for the traditional technique, there was no statistically significant difference between mean Ca : P ratio values of the three materials at 2 and 5 weeks. For the electrophoresis-aided technique, nano-hydroxyapatite showed the highest effect, with the most insignificant effect demonstrated in bioactive glass at both 3 and 5 hours. CONCLUSIONS: Applying different re-mineralizing agents significantly influences enamel topography and chemical composition, and accelerate the effect of re-mineralizing agents. Moreover, the dynamics of re-mineralizing agents might be accelerated by electrophoresis. [ABSTRACT FROM AUTHOR]

This paper reports the influence of hydrolytic aging on the rupture voltage of copper wire enameled with polyestermide reinforced by a polyamide imide layer. A large population of samples was put in a climatic chamber regulated at 40°C and 93% relative humidity. The wet aging was carried out until 15000h. Every time of 500h, 80 samples were taken from the climatic chamber and submitted to AC breakdown test. A statistic investigation of breakdown voltage values was done using Weibull model. Scale parameter, shape parameter and confidence intervals are presented. The breakdown voltage changes in function of aging time. The raise is ascribed to the arrangement in the structure of the polymer. While its lowering is assigned to the diminution in the viscosity causing a raise of mean free path of charge carriers. The shape parameter changes versus aging time. The shortening is due to the increase in the size of defects. Whereas its raise is allotted to the arrangement in the structure. TGA shows a variation of the onset temperature and the residue during the aging. The FTIR tests show a weak modification of the spectra. There is no degradation of the insulation, however a change in molecular conformation occurs. The results are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Background: The world of esthetic dentistry is constantly making efforts toward the management of tooth staining. Laser-assisted bleaching is needed before adhesive restorations and has become common and advantageous as it accelerates bleaching action, reduces postoperative sensitivity, and promotes recrystallization of enamel. Aim: The study aimed to evaluate and compare the bond strength of diode (Biolace: EpicX) and neodymium-doped:yttrium aluminum garnet (Nd:YAG) (LightWalker, Fotona, Slovenia) assisted bleached (Pola Office, SDI) enamel with nanofilled composite (GC Solare Sculpt). Materials and Methods: The samples were divided into three groups (n = 11): Group A - Conventionally bleached enamel, Group B - Diode laser-assisted bleached enamel, Group C - Nd:YAG laser-assisted bleached enamel. After storing samples in Artificial Saliva for 2 weeks, bonding was performed, and nanofilled composite resin was applied through an incremental method. Samples were subjected to shear bond strength (SBS) analysis. Conclusion: The use of Nd:YAG laser on bleached enamel significantly increases the bond strength with nanofilled composite resin. [ABSTRACT FROM AUTHOR]

Context: White spot lesion is the first clinical sign of a caries lesion and represents mineral loss from the enamel subsurface. Aim: The aim of this study was to evaluate the penetration depth (PD) of Icon resin infiltrant into artificially demineralized enamel lesions using confocal laser scanning microscope (CLSM) analysis in dual fluorescence mode. Settings and Designs: The design of the study was an in vitro study. Materials and Methods: 22 extracted human permanent maxillary central incisor teeth were collected, and enamel sections were obtained from the coronal middle third. All enamel specimens were exposed to demineralization and remineralization solutions for 14 days. On positive confirmation of enamel demineralization by scanning electron microscope analysis, 20 specimens were then subjected to Icon resin infiltration following manufacturer instructions. Specimens were processed with indirect staining technique using rhodamine B and sodium fluorescein dyes and examined under CLSM at ×10 magnification in dual fluorescence mode using ImageJ software to evaluate PD of resin infiltrant into demineralized enamel lesions. Statistical Analysis Used: Obtained data were analyzed using an independent t-test. P =0.05 was considered statistically significant. Results: The maximum depth of demineralized enamel lesion was 590 µm, and the mean depth was 290.78 ± 14.80 µm. The maximum depth of resin infiltrant penetration was 580 µm, and the mean depth was 279.08 ± 13.88 µm; P = 0.006. The percentage penetration of resin infiltrant was 95.99%. Conclusion: Icon resin infiltrant was highly effective in its depth of penetration into demineralized enamel lesions. The use of indirect staining and CLSM analysis in dual fluorescence mode is more reliable and accurate technique to evaluate the PD of resin infiltrant. [ABSTRACT FROM AUTHOR]