Enamel Microhardness Research Articles

Comparative evaluation of surface microhardness of bleached enamel subjected to erosion after using Remin Pro and NovaMin: An in vitro study

Aim and Objective: The aim of the study was to evaluate and compare the surface microhardness of bleached enamel subjected to erosion after using Remin Pro and NovaMin. Methodology: Thirty human maxillary premolars were selected and decoronated. Enamel blocks were obtained from these teeth and subjected to three phases of treatment: bleaching phase, remineralizing phase, and erosive phase. Samples were divided into four groups with 15 samples each. Group I: subjected to erosion without application of bleaching and remineralizing agent, Group II: treatment with 35% carbamide peroxide without application of remineralizing agent, Group III: treatment with 35% carbamide peroxide, followed by application of Remin Pro, and Group IV: treatment with 35% carbamide peroxide followed by application of NovaMin. Initial and final surface microhardness was analyzed using Vickers microhardness. Results: There was a statistically significant difference between control and experimental groups. The percentage of surface hardness loss (%SHL) value was significantly higher in Group II in comparison with the other groups of treatment. However, Group IV and Group III showed the lowest %SHL compared to GI. Conclusion: Within the limitations of this present in vitro study, NovaMin has better-remineralizing potential than Remin Pro and demonstrated increased microhardness of bleached enamel.

Concentration-dependent effect of carboxymethyl chitosan amorphous calcium phosphate on the surface hardness of primary tooth enamel.

To compare the effects of gels containing 2.5% and 5% carboxymethyl chitosan amorphous calcium phosphate (CMC-ACP) on the microhardness of primary tooth enamel. Twenty-four tooth specimens were demineralized with 37% phosphoric acid and divided into four groups: an untreated control group, a positive control group treated with casein phosphopeptide amorphous calcium phosphate, and two groups treated with 2.5% and 5% CMC-ACP gel, respectively. The enamel surface hardness was then measured with a Vickers hardness tester. In terms of Vickers Hardness Number (VHN), the degree of alteration in tooth surface microhardness was 77.83 ± 13.44 in the 5% CMC-ACP group and 52 ± 6.93 in the 2.5% CMC-ACP group (P = 0.002). The inter-group difference in the surface hardness change was significant (P < 0.05). The 5% CMC-ACP gel increased the hardness of primary tooth enamel to a greater degree than the 2.5% CMC-ACP gel.

In vitro evaluation of the effect of ozonated olive oil containing dentifrice on enamel color change and microhardness

In vitro evaluation of the effect of ozonated olive oil containing dentifrice on enamel color change and microhardness

Microhardness change of human dental enamel due to power bleaching with different gels.

Since the introduction of bleaching treatments in the office, different lights have been suggested to accelerate the bleaching reaction. This study aimed to evaluate the microhardness of tooth enamel after office bleaching using different materials.

The effect of minimally invasive treatments on enamel microhardness and resistance to further demineralization

Objectives: The present study aimed to compare microhardness of inactive proximal lesions treated by resin infiltration, Er:YAG laser + resin infiltration and Bioactive glass, and investigate the resistance of treated lesions to further demineralization challenge.&#x0D; Methods: In this in-vitro study, 30 human molars with inactive proximal lesions were selected and randomly divided into three groups of 10. In group 1 (resin infiltration), the lesions were treated by a resin infiltrant (Icon). In group 2, the surface was conditioned by an Er:YAG laser prior to resin infiltration. The specimens in group 3 were remineralized by bioactive glass. The treated specimens were kept in artificial saliva for 1 week and then immersed in a demineralization solution for 8 weeks. Surface microhardness was measured at baseline (T0), after remineralization (T1) and after exposure to the demineralization solution (T2), and the difference in microhardness between time points (ΔVHN) was calculated.&#x0D; Results: Microhardness after demineralization (T2) was significantly lower than those of other intervals (P0.05). The statistical analysis revealed no significant difference either in ΔVHNT1-T0 or in ΔVHNT2-T1 among the study groups (P&gt;0.05)&#x0D; Conclusion: Pretreatment by the Er:YAG laser prior to resin infiltration was more effective that other treatments in enhancing microhardness and protecting the tooth against acidic challenge. However, the difference between groups did not reach a statistical significance, implying the need for further studies to achieve more conclusive results.

Ozone and microstructural morphological changes of tooth enamel.

The paper aims to study the impact of ozone (O3) treatment on the microstructural changes of the tooth enamel after the treatment at different time intervals. The ozonation was performed with gaseous O3 produced by HealOzone X4, the demineralization level was measured with the DiagnoDent Pen 2190 device, and the microstructure changes of enamel surface were observed using scanning electron microscopy (SEM) analysis. The results showed the exposure to O3 for 40-50 seconds enhanced enamel micro-hardness and ensures a rate of remineralization between 96.82-97.38%. In conclusion, in search of new minimally invasive solutions in the treatment of caries and to offer antimicrobial support of the oral cavity, the use of O3 as an alternative therapy to classical solutions may be a viable solution in dentistry.

Effect of highly concentrated bleaching gels on enamel microhardness and superficial morphology, and the recovery action of four remineralizing agents

BackgroundDental bleaching is a common clinical practice. The aim of this study is to investigate the effect of 35% hydrogen peroxide (HP) bleaching gel on the morphology and microhardness of enamel, and to analyze the effect of four remineralizing agents.MethodsOne hundred blocks were prepared. The enamel surfaces were bleached with 35% HP in one session. The specimens were divided into four remineralization treatment groups (n = 25). G1: Tooth Mousse, G2: Remin-Pro, G3: Colgate Pro-Relif, G4: Mirafluor. The remineralizing protocol was applied 3 min per day for one week. Vickers microhardness (HV) measurements and SEM observations were performed at baseline, after bleaching, and after remineralizing treatment in all groups. Statistical analyses were performed using the paired t-test and ANOVA.ResultsAfter bleaching, SEM showed an increase of irregularities on the surface of the samples. Enamel microhardness decreased a mean of 47.7 HV, equivalent to a mean decrease of 18.3% (p < 0.05). After remineralization, the HV increased in all groups between 16 and 33% (p < 0.01), recovering the initial microhardness of enamel samples. SEM images revealed a higher quantity of superficial mineral deposits in groups 1 and 2 compared to the rest of the groups.ConclusionsThe application of remineralizing products generates a significant increase in enamel microhardness. Tooth Mousse-treated samples showed a greater microhardness recovery, followed by Remin Pro. The superficial morphology of the samples reflects the results obtained in the HV tests.

Effect of Sucrosomial® Iron and Iron Drop Diluted with Natural Fruit Juice on Microhardness of Primary Enamel.

Objectives: Considering the high prevalence of consumption of iron drops, and the resultant reduction in microhardness of primary enamel, this in vitro study aimed to assess the effects of Sucrosomial® iron and iron drop diluted with natural fruit juice on microhardness of primary enamel. Materials and Methods: This in vitro, experimental study evaluated 45 extracted sound primary anterior teeth, that were randomly assigned to three groups (n=15) of Sideral, Irofant, and Irofant + natural apple juice. The titratable acidity and pH of solutions were measured. After measuring the baseline microhardness by a Vickers hardness tester, the teeth in the three groups were exposed to the respective iron drop solutions at 37°C for 5 minutes. They were then rinsed with distilled water, and their secondary microhardness was measured. Data were analyzed using the dependent Student t-test, ANOVA, and ANCOVA (alpha=0.05). Results: Irofant had the lowest pH and the highest titratable acidity among the tested solutions. A reduction in enamel microhardness occurred in all groups after exposure to iron drops (P=0.0001). The reduction in microhardness was significantly greater in Irofant group compared with Irofant + natural apple juice (P=0.0001). Also, the reduction in microhardness was significantly greater in Irofant + natural apple juice compared with Sideral iron drop group (P=0.0001). Conclusion: Sideral iron drop with Sucrosomial iron has minimal adverse effect on microhardness of primary enamel. Also, dilution of iron drops with natural apple juice can be suggested as an effective strategy to decrease their adverse effects on microhardness of primary enamel.

Influence of Bleaching Agent Containing Bioactive Glass on Color and Microhardness of Bovine Enamel

Influence of Bleaching Agent Containing Bioactive Glass on Color and Microhardness of Bovine Enamel

Erosive effect of beverages on surface hardness and ultra-structure of deciduous teeth enamel

To assess the erosive potential of commonly used beverages on the surface micro-hardness and ultra-structure of deciduous teeth enamel. A total of 52 human extracted deciduous molars were subjected to erosive challenge by cyclic immersion in four beverages: G1: artificial saliva , G2: strawberry-flavored milk, G3: orange juice, and G4: carbonated drink-Pepsi, for a 28- day pH cycling protocol. The enamel surface micro-hardness (SMH), and surface topography using a scanning electron microscope (SEM) were assessed at baseline, after two- and four-weeks of the erosive challenge. The SMH findings were statistically analyzed using the SPSS program at p ≤ 0.05 significance. The pH of G4 and G3 showed significantly highly acidic pH. Both G4 and G3 showed the lowest SMH by four-week erosive challenge. By two-week erosive challenge, groups were ranked according to SMH as follows; G4 <G3 <G2 <G1. However, SMH of both G4 and G3 yielded significantly lower values compared to G2 and G1 by four weeks. The SEM of G4 and G3 depicted advanced alteration of surface enamel with increased erosive challenge exposure time. Carbonated soft drink (Pepsi) and orange juice showed high erosive potentiality affecting the enamel surface of deciduous teeth while milk-based beverage showed no difference from the artificial saliva.

Water as Veneering Modeling Liquid Affects Microhardness of Glassy Matrix Veneering Ceramic.

To evaluate the effect of different veneering liquids used for modeling on microhardness, fracture toughness and biaxial flexural strength of a glass-veneering ceramic. The manufacturer recommended modeling liquid (ML), distilled water (DW), isopropyl alcohol (IA), 0.5% (P05), 1% (P1), and 2% (P2) polyethylene glycol solutions were mixed with feldspathic ceramic powder to form disc-shaped samples (n=20, 15 mm × 1.2 mm). After sintering, samples were mirror-polished and subjected to Vickers indentation (n=5) for measurement of microhardness and fracture toughness. The remaining 15 samples from each group were subjected to biaxial flexural strength. Data were subjected to one-way ANOVA and Weibull analysis. The microhardness was affected by veneering liquid (p=0.002): DW promoted higher microhardness values than ML and IA. Fracture toughness (p=0.301) and flexural strength (p=0.930) were not affected by the veneering liquid but Weibull parameters were affected. All groups presented surface pores under high magnification. Even though the use of DW led to higher values of surface microhardness than the ML, all obtained values are inside the range of enamel microhardness values reported in the literature. Such parameters may affect antagonist wear and should be reported in clinical trials.

In vitro assessment of activated charcoal-based dental products.

Assess the effects of activated charcoal-based products on whitening and changes on dental enamel surface. Fifty-two blocks of bovine dental enamel were randomly distributed in four groups (n=13): brushing with activated charcoal-based powder (PW); brushing with activated charcoal-based dentifrice (AC); brushing with a conventional dentifrice containing 1450 ppm of fluoride (CD); and whitening with 10% carbamide peroxide (CP). Color, microhardness, and surface alteration were analyzed at baseline and after 14 days of treatment. Three samples per group were randomly selected and examined using scanning electron microscopy (SEM) to analyze the morphology. PW exhibited greater color change for the ΔE00 , ΔWID, Δb* and ΔL* parameters than other groups (p < 0.05). After treatment, microhardness decreased in AC and CP groups (p < 0.05). Also, PW and AC groups showed more surface alteration than CD and CP (p < 0.001). Changes in the morphology of dental enamel were observed by SEM in PW and AC groups. Activated charcoal-based products showed a lower whitening effect than 10% carbamide peroxide. These products also influenced dental enamel microhardness, resulting in greater surface alteration. Activated charcoal-based products promoted minimum whitening effects with significant enamel surface alteration. The 10% carbamide peroxide was more effective for whitening and caused slight enamel surface alteration.

A novel dental infiltration resin based on isosorbide-derived dimethacrylate with high biocompatibility, hydrolysis resistance, and antibacterial effect.

Objectives: The available infiltration resin has raised biosafety and treatment stability concerns because of the cytotoxicity of the main component, TEGDMA, and its susceptibility to hydrolysis in the oral environment. This study aimed to develop a TEGDMA-free infiltration resin to overcome these drawbacks. Methods: Using the synthetic bioderived monomer bis(methacrylate) isosorbide (IBM) and the zwitterionic compound 2-methacryloyloxyethyl phosphorylcholine (MPC), a novel infiltrant IBMA was developed and preferentially selected. We investigated the performance of the IBMA resin regarding cytotoxicity, antibiofilm adhesion, and hydrolysis resistance and further verified its ability to restore the demineralized enamel and stability of the infiltrated area under artificial aging conditions. Results: Compared with the commercial TEGDMA-based infiltration resin ICON, IBMA not only demonstrated similar enamel morphologic and esthetic restorative effects in chalky lesions but also exhibited favorable cell viability, durable Streptococcus mutans UA159 biofilm-repellent performance, and higher enamel microhardness (204.0 ± 5.12HV) of the infiltrated enamel. Specifically, because of the high crosslink density [(47.77 ± 5.76) ×103mol/mm3] and low water sorption [12.79 ± 2.56µg/mm3] of the polymer network, the IBMA resin was more resistant to hydrolysis than ICON, which prevents the disruption of the infiltrant's micropore-blocking effect after aging. Enamel lesions treated with IBMA demonstrated good color stability after the tea-staining challenge, which was significantly better than that in the ICON group. Conclusion: Based on these findings, the IBMA resin exhibits favorable cell viability, hydrolysis resistance, and biofilm-repellent properties, which alleviates the defects of traditional TEGDMA systems. Therefore, it is a better alternative for microinvasive treatment involving early caries and enamel whitish discoloration.

Effect of Eggshell Powder and Nano-Hydroxyapatite on the Surface Roughness and Microhardness of Bleached Enamel.

The aim of the study was to evaluate the remineralizing potential of prepared solutions of eggshell powder (ESP) and nano-hydroxyapatite (nHA) on the surface roughness and microhardness of bleached enamel. Fifty bovine anterior teeth were selected and cleaned then bleached using a chemically activated in-office bleaching agent then the teeth were randomly allocated into five groups (n = 10) according to the tested remineralizing agents (10% ESP solution, 10% nHA solution, and MI Paste Plus) into; control, bleached, bleached + ESP solution, bleached + nHA solution, and bleached + MI Paste Plus groups. Then, the teeth were tested for surface roughness and microhardness of the bleached enamel, respectively. There was a statistically significant difference in the surface roughness and microhardness values of the tested groups. The highest surface roughness mean value was found in bleached enamel group, while the least mean value was found in the control group. The highest mean microhardness value was found in the bleached enamel + ESP solution group, while the least mean value was found in the bleached enamel group. The application of the tested remineralizing agents following the bleaching procedure had improved the surface roughness and microhardness of the bleached enamel. ESP and nHA present promising and potent remineralizing agents.

Influence of toothpastes containing tricalcium phosphate on dental enamel microhardness, color, and topography

The aim of this study was to evaluate the effect of using dentifrices containing tricalcium phosphate (β-TCP) on microhardness, enamel color, and topography before bleaching treatment with 35% hydrogen peroxide (HP). Fifty bovine incisor enamel/dentin blocks (4 × 4 × 2 mm) were randomized into five groups (n=10): (C) negative control (no treatment), positive control (35% HP), Colgate Total 12 then 35% HP (CT 12 + 35% HP), Elmex Sensitive then 35% HP (ES + 35% HP), and Bianco Pro Clinical then 35% HP (BPC + 35% HP). Knoop microhardness (KHN) and scanning electron microscopy (SEM) were performed. The color was evaluated using CIELAB (∆Eab*) and CIEDE 2000 (∆E00) in 3 times: initial time (T0), 24 hours after exposure to dentifrice (T1), and 24 hours after bleaching treatment (T2). Data for microhardness, ∆Eab*, and ∆E00 data were analyzed using generalized linear models, considering the model’s group effect. The ∆L, ∆a, and ∆b data were analyzed using Kruskal–Wallis and Dunn’s nonparametric tests. A significance of 5% was used. KHN was significantly higher in the BPC + 35% HP and ES + 35% HP groups than in the C and 35% HP groups (p=0.0295). ∆L was greater in the groups that received 35% HP than in the C group 24 hours after bleaching (p=0.0001). There was no significant difference between groups in ∆Eab* (p=0.0679) and ∆E00 (p=0.1463) 24 hours after bleaching. Using dentifrices containing β-TCP before bleaching treatment with 35% HP increases enamel microhardness but does not significantly alter tooth color. Clinical Significance: Dentifrices containing β-TCP in their formulation increase enamel microhardness without interfering with substrate color when used with previous in-office tooth bleaching.

Comparative Assessment of Enamel Microhardness Using Various Remineralising Agents on Artificially Demineralized Human Enamel.

Various remineralizing agents can be used to remineralize initial carious lesions. The study aims to compare and evaluate the remineralizing efficiency of Remin Pro (VOCO GmbH,Cuxhaven, Germany), tricalcium phosphate, and HealOzone (CurOzone USA Inc., Ontario, Canada) by measuring the microhardness of enamel. Forty-five mandibular premolars were collected and divided into three groups (A, B, and C). After sectioning mesiodistally, they were subdivided into the control and test groups. The test group was further subdivided into demineralized (A2a, B2a, and C2a) and remineralized (A2b, B2b, and C2b) groups. All test group samples were demineralized by immersing in demineralizing solutions for 24 hours. Afterwards, A2b, B2b, and C2b samples were remineralized by remineralizing agents (Remin Pro, tricalcium phosphate, and HealOzone) for three minutes (twice a day) for 14 days, and then Vickers microhardness testing (VHN) was performed. The microhardness values of the demineralized group were lower compared to the samples of the control groups. In the remineralized group, the mean microhardness values were maximum for HealOzone (293.22 kgmm-2), followed by Remin Pro (287.5660 kgmm-2) and then tricalcium phosphate (282.4660 kgmm-2). The application of remineralizing paste proved potent in improving the remineralization in the demineralized enamel surface.

Effect of sodium fluoride plus tricalcium phosphate with and without CO2 laser on remineralization of white spot lesions

ObjectivesThe aim of this in vitro study was to evaluate the effect of NaF plus TCP with and without CO2 laser irradiation on management of demineralized enamel using microhardness test and digital microscopy. MethodsEighty intact extracted human premolar teeth were randomly divided into 4 groups (20/each). Each group was subjected to a demineralizing solution to create white spot lesion. Group 1 was treated with 3M Vanish™. Group 2 was irradiated with CO2 laser. Group 3 was subjected to CO2 laser followed by 3M Vanish™. Group 4 was treated by 3M Vanish™ then CO2 laser. The teeth were immersed in artificial saliva. Surface microhardness was measured for each tooth before demineralization at base line (M1 as a control), after demineralization (M2) and after management (M3). Comparison of microhardness values between groups was performed using one way ANOVA test with significant level (0.05) followed by multiple comparisons post-hoc Tukey test between groups. Enamel surface was photographed by digital microscope. ResultsAll intervention methods used in the current study significantly increased microhardness values of demineralized enamel (P < 0.001). Little improvement of enamel appearance was observed in all groups meanwhile using CO2 laser on demineralized enamel directly led to signs of white and black dots affecting the appearance of enamel surface. SignificanceThe most effective intervention regarding microhardness was group 2 followed by group 3, group 4 and group 1. Coating the enamel surface with 3M Vanish™ before CO2 laser irradiation acted as a protective layer from the undesirable effects of laser on the teeth with increasing enamel microhardness values more than using Vanish alone. So the promising intervention method regarding both microhardness and appearance was group 4.

The Abrasive and Remineralising Efficacy of Coturnix Eggshell

The objective of this research was to determine the abrasive and remineralising efficacy of quail eggshell (Coturnix coturnix) incorporated into a new experimental toothpaste. An experimental study was designed to compare the surface microhardness of the dental enamel of bovine lateral incisors exposed to different toothpastes. In relation to microroughness (abrasive efficiency), the unit of analysis was each specimen with 16 polymethylmethacrylate (PMMA) blocks. For the remineralisation variable, the unit of analysis was each bovine lateral incisor tooth. A sample size of 16 was determined for each group. The unpolished PMMA specimens presented the highest mean surface microroughness with a mean of 4.60 ± 1.47 µm, whilst the quail paste, universal polishing paste, control paste, and Diamond Excel Paste showed a mean of 1.16 ± 0.40 µm, 0.63 ± 024 µm, 0.45 ± 0.22 µm, and 0.43 ± 0.17 µm, respectively, presenting significant differences (P < .001). When comparing the surface microhardness of bovine lateral incisor dental enamel exposed to different toothpastes, the universal polishing paste presented the lowest microhardness, with 192.43 ± 56.21 kg/mm2, whilst the quail paste presented the greatest remineralising effect, with the highest average of 272 ± 21.18 kg/mm2, followed by the control paste with 244 ± 41.43 kg/mm2 and the Diamond Excel Paste with 228.72 ± 43.72 kg/mm2. These differences were statistically significant (P < .001). Significant differences were found in the surface abrasive efficiency (microroughness) of PMMA subjected to different toothpastes. The quail toothpaste presented statistically significant results compared to the control pastes, the Diamond Excel Paste, and the universal polishing paste.

Enamel biomineralization under the effects of indomethacin and celecoxib non-steroidal anti-inflammatory drugs

The aim of this study was to explore the effects of nonsteroidal anti-inflammatory drugs on biomineralization of enamel. Sixty C57Bl6 male mice were used, which were assigned into three groups: celecoxib (n = 20) or indomethacin (n = 20) treatment for a period of 28 days or received no medication (control group, n = 20). Visual inspection and microcomputed tomography were used to analyze enamel morphology. Scanning electron microscopy–Energy dispersive X-ray and Knoop microhardness test were used to quantify chemical element content (Ca, P, C, O) and enamel microhardness, respectively. Tissues were collected to investigate the synthesis, activity or nuclear translocation of metalloproteinase-20, transcription factor Runx2, dentin sialoprotein and cyclooxygenase-2 enzyme by means of immunohistochemistry, in situ zymography and indirect immunofluorescence. Treatment with indomethacin and celecoxib reduced the Ca and P content, microhardness and mineral density in enamel. Treatment with nonsteroidal anti-inflammatory drugs caused an accumulation of metalloproteinase-20 and overall increased enzymatic activity in enamel matrix, while the synthesis of the transcription factor Runx2 was inhibited by these drugs. Interestingly, indomethacin inhibited Runx2 translocation to the nucleus whereas celecoxib did not. Those findings show that non-steroidal anti-inflammatory drugs impact the enamel biomineralization and could be involved in the etiology tooth enamel defects if used during the period of tooth formation and mineralization.

Evaluation of Remineralizing Effects of CPP-ACP and Nanohydroxyapatite on Erosive Lesions of Enamel in Deciduous Teeth After Exposure to Acetaminophen Syrup: An in vitro Study

Background: Oral pediatric liquid medications are commonly used in children who suffer from chronic diseases. Due to acid components in their formulations, these medications may possess a high erosive potential to dental tissues. Erosion is one of the major causes of degradation and demineralization of the enamel. If demineralization causes are not inhibited, it progresses and completely degrades the enamel. So, the dentin is exposed, and, finally, the pulp will be engaged in the process. Aim: This study aimed to evaluate the remineralizing properties of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and nanohydroxyapatite on erosive lesions caused by acetaminophen syrup intake in vitro. Methods: The microhardness of 34 healthy human primary molars was determined prior to and following a seven-day, three-times-a-day, one-minute exposure to acetaminophen syrup. The teeth were then randomly divided into four groups and were immersed in artificial saliva, fluoride gel, nano-hydroxyapatite, and CPP-ACP for 10 minutes. Then, their final microhardness was measured, and repeated-measures ANOVA analyzed the data. Results: Enamel microhardness in two groups decreased after exposure to acetaminophen syrup and increased after applying remineralization agents, CPP-ACP, and nano-hydroxyapatite. The two groups did not show significant differences in terms of microhardness increase (p-value=0.141). Conclusions: According to the findings of this study, CPP-ACP and nano-hydroxyapatite can improve the microhardness of enamel, which has been reduced as a result of exposure to medicinal syrups.