Enamel Surface Research Articles

Is the whitening effect of charcoal-based dentifrices related to their abrasive potential or the ability of charcoal to adsorb dyes?

ObjectivesTo evaluate if tooth color alteration of activated charcoal-based dentifrices may be attributed to the dye adsorption potential of charcoal (chemical action - C - slurry only) or to the association of dye adsorption with abrasion (chemo-mechanical action - CM- slurry/toothbrushing). Potential adverse effects in surface roughness, gloss, and wear were also assessed. MethodsBovine enamel/dentin specimens were randomly allocated into the groups according to treatments and test model (n = 15): deionized water (negative control- NC); Colgate Maximum Anticaries Protection (conventional toothpaste- positive control- PC); Colgate Luminous White Activated Charcoal (LW); Oral-B 3D White Therapy Charcoal (WT); Curaprox Black is White (BW); Dermavita Whitemax (Activated charcoal powder- WP). Specimens were exposed to the C or CM models, in 28-day staining-treatment cycling. Color change (ΔE00), whiteness index (ΔWID), percentage of alteration of surface roughness (%Raalt), and gloss (%GUalt) were calculated. Additional specimens (n = 9) were indented with a Knoop diamond and subjected to 100,000 abrasion cycles. Enamel wear was determined by calculating the decrease in indentations geometry. Data were analyzed by ANOVA/Tukey tests (α = 0.05). ResultsThe CM-model produced lower color change (staining) than C (p = 0.0001). PC, LW, WT, BW, and WP showed similar color results for both models, differing from NC (p < 0.05).%Ra and%GU did not differ among the C-model groups (p > 0.05) and WP exhibited the highest variation (%Ra and%GU) under CM-model. Enamel wear values were lowest in the NC and PC groups, intermediate for LW, WT, BW, and highest for the WP (p < 0.05). ConclusionActivated charcoal-based dentifrices have a similar ability to minimize tooth staining as the conventional toothpaste, with increased enamel wear potential in the long term (after 100,000 cycles). The activated charcoal powder damaged the enamel surface, showing a higher deleterious effect on enamel roughness, gloss, and wear. Clinical significanceDentifrices containing activated charcoal do not provide superior results to minimize tooth staining compared to conventional toothpaste. Charcoal powder should be used with caution because it promotes higher superficial alterations on the enamel surface.

Effects of 35% Versus 10% Carbamide Peroxide At-Home Bleaching Agents with or without MI Paste Plus on Enamel Properties

This study compared the effects of 35% with 10% carbamide peroxide (CP) home used bleaching agents on enamel color change, microhardness, and surface changes in association with MI paste plus (CPP -ACPF). Forty buccal and lingual enamel samples from twenty human third molars were prepared and divided into four groups (n=10). The groups were bleached for two weeks according to different bleaching regimens as follow; G1 bleached with 10%CP, G2 bleached with 35%CP, G3 bleached with a mixture of 10%CP and MI paste plus, and G4 bleached with a mixture of 35%CP and MI paste plus. Color change was recorded with a colorimeter before and after bleaching and total color differences (ΔE*) was calculated. Vickers microhardness test was recorded for all the samples before and after treatment. One sample from each group was evaluated for surface changes by scan electron microscopy (SEM). The data were analyzed with repeated measure of variance and student's t-test at p&lt;0.05. No significant difference in ΔE* was recorded among the four groups (p&gt;0.05). Significant reduction in enamel microhardness was only recorded for G2 (p=0.003). SEM for G3 and G4 showed obvious mineral deposition. Similar teeth color whitening can be resulted after two weeks of bleaching with both 10%CP and 35%CP when used as recommended by the manufacturer with and without the addition of MI paste plus. Using 35%CP decreased enamel microhardness significantly, whereas MI paste plus when mixed with both bleaching agents could compensate for the microhardness reduction.

Quantity and diameter of dentinal tubules of human teeth and teeth of experimental animals according to scanning electron microscopy data

Insight into the interrelation between the structure and mechanical properties of dentin of a tooth is crucial for prevention and treatment of oral cavity diseases. The study of the structure of dental dentin is important for understanding the pathogenetic mechanisms of the spread of cariogenic microflora in progressive dental caries to the pulp and periodontium, as well as for the interpretation of the results of studies of dental dentin-adhesive materials. The in vitro research presented here involved the examination of coronal dentin in 46 intact teeth from rats, cats, dogs, and humans at various distances from the pulp chamber, with a focus on the quantity and diameter of dentinal tubules. The calculations were based on the analysis of 155 scanning electron microscope photographs of the enamel surface and pulp chamber wall. The researchers calculated the quantity and diameter of dentinal tubules per unit area, which they measured at various distances from the pulp chamber. It was found that dentinal tubules are the widest near the pulp chamber wall, where the average diameter ranged from 1.7 to 2.8 µm. The highest values were found in premolars of young humans and the lowest - in the incisors of rats. In the middle portion of the dentin, the diameter of dentinal tubules ranged from 1.0 to 13.3 µm, while at the periphery, it was 0.6–0.9 µm. The highest density of dentinal tubules per unit area was found closest to the pulp horn, and the lowest was in the enamel region. Near the pulp chamber wall, the average density of dentinal tubules ranged from 50 000 to 90 000/mm², in the middle of the dentin, it ranged from 37 000 to 50 000/mm², and at the periphery, it ranged from 10 000 to 25 000/mm². All examined teeth exhibited straight dentinal tubules, except for the rats’ incisors, which showed local irregularities. A comparison was made based on the quantity and width of dentinal tubules in the examined animals and humans.

The Distribution and Biogenic Origins of Zinc in the Mineralised Tooth Tissues of Modern and Fossil Hominoids: Implications for Life History, Diet and Taphonomy.

Zinc is incorporated into enamel, dentine and cementum during tooth growth. This work aimed to distinguish between the processes underlying Zn incorporation and Zn distribution. These include different mineralisation processes, the physiological events around birth, Zn ingestion with diet, exposure to the oral environment during life and diagenetic changes to fossil teeth post-mortem. Synchrotron X-ray Fluorescence (SXRF) was used to map zinc distribution across longitudinal polished ground sections of both deciduous and permanent modern human, great ape and fossil hominoid teeth. Higher resolution fluorescence intensity maps were used to image Zn in surface enamel, secondary dentine and cementum, and at the neonatal line (NNL) and enamel-dentine-junction (EDJ) in deciduous teeth. Secondary dentine was consistently Zn-rich, but the highest concentrations of Zn (range 197-1743 ppm) were found in cuspal, mid-lateral and cervical surface enamel and were similar in unerupted teeth never exposed to the oral environment. Zinc was identified at the NNL and EDJ in both modern and fossil deciduous teeth. In fossil specimens, diagenetic changes were identified in various trace element distributions but only demineralisation appeared to markedly alter Zn distribution. Zinc appears to be tenacious and stable in fossil tooth tissues, especially in enamel, over millions of years.

The Influence of Indirect Bonding Technique on Adhesion of Orthodontic Brackets and Post-Debonding Enamel Integrity-An In Vitro Study.

The increasing demand for orthodontic treatments due to the high prevalence of malocclusion has inspired clinicians and material scientists to investigate innovative, more effective, and precise bonding methods with reduced chairside time. This study aimed at comparing the shear bond strength (SBS) of metal and ceramic brackets bonded to enamel using the indirect bonding technique (IDB). Victory Series metal brackets (Metal-OPC, Metal-APC) and Clarity™ Advanced ceramic brackets (Ceramic-OPC) (3M Unitek, Monrovia, CA, USA) were bonded indirectly to extracted human premolars through the etch-and-rinse technique. A qualitative assessment of the enamel surface using microscopic methods was performed, and the amount of residual adhesive was reported as per the adhesive remnant index (ARI). Moreover, the bracket surface was evaluated with SEM-EDS. The highest SBS mean values were observed in the Ceramic-OPC group (16.33 ± 2.01 MPa), while the lowest ones were obtained with the Metal-OPC group (11.51 ± 1.40 MPa). The differences between the Metal-AOPC vs. Metal-APC groups (p = 0.0002) and the Metal-OPC vs. Ceramic-OPC groups (p = 0.0000) were statistically significant. Although the Ceramic-OPC brackets bonded indirectly to the enamel surface achieved the highest SBS, the enamel damage was significantly higher compared to that of the other groups. Thus, considering the relatively high bond SBS and favourable debonding pattern, Metal-APC brackets bonded indirectly may represent the best choice.

Optimization of Functional Toothpaste Formulation Containing Nano-Hydroxyapatite and Birch Extract for Daily Oral Care.

This research work aims to develop functional toothpastes with combined enamel remineralization and antibacterial effects using nano-hydroxyapatites (nHAPs) and birch extract. Eleven toothpastes (notated as P1-P11) were designed featuring different concentrations of birch extract and a constant concentration of pure nHAPs or substituted nHAPs (HAP-5%Zn, HAP-0.23%Mg-3.9%Zn-2%Si-10%Sr, and HAP-2.5%Mg-2.9%Si-1.34%Zn). In vitro assessments involved treating artificially demineralized enamel slices and analyzing surface repair and remineralization using Atomic Force Microscopy (AFM). The Agar Disk Diffusion method was used to measure antibacterial activity against Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis, Streptococcus mutans, and Staphylococcus aureus. Topographic images of enamel structure and surface roughness, as well as the ability of nHAP nanoparticles to form self-assembled layers, revealed excellent restorative properties of the tested toothpastes, with enamel nanostructure normalization occurring as soon as 10 days after treatment. The outcomes highlighted enamel morphology improvements due to the toothpaste treatment also having various efficacious antibacterial effects. Promising results were obtained using P5 toothpaste, containing HAP-5%Zn (3.4%) and birch extract (1.3%), indicating notable remineralization and good antibacterial properties. This study represents a significant advancement in oral care by introducing toothpaste formulations that simultaneously promote enamel health through effective remineralization and bacterial inhibition.

CAD/CAM leucite-reinforced glass-ceramic for simulation of attrition in human enamel in vitro

ObjectiveInvestigate attrition simulation using CAD/CAM leucite-reinforced glass-ceramic antagonists on occlusal vs. buccal enamel. MethodsThree dental materials with known wear rates (resin-modified glass-ionomer, micro-filled, and fine particle composites) validated the wear simulator (CAD/CAM glass-ceramic antagonists, 200 cycles, 80 N load, deionised water irrigation, 0.7 mm sliding movement). Following this, human molars were sectioned into paired occlusal and buccal polished samples (n = 8/gp). Exposed 1.5 mm Ø enamel areas were subjected to attritional wear with and without pre-immersion in citric acid (5 min, 0.3%, pH 3.8). Profilometry measured step-height enamel wear and surface microhardness at different depths was calculated using Vickers indentation at 0.1 N and 0.5 N loads. ResultsDental material wear using the CAD/CAM antagonists showed consistency with previous data: mean (SD) resin-modified glass ionomer material loss of 177.77 (16.89) µm vs. 22.15 (1.30) µm fine particle hybrid composite resin wear vs. 13.63 (1.02) µm micro filled composite resin wear (P < 0.001). The coefficient of variation was less than 10%. Following validation, enamel sample wear was significantly increased when attrition was introduced (P < 0.001) independent of buccal vs. occlusal sample location (P < 0.05). Attrition resulted in occlusal wear of 26.1 ± 4.5 µm vs. buccal 26.3 ± 1.2 µm and attrition/erosion resulted in occlusal wear of 26.05 ± 4.46 µm vs. buccal 25.27 ± 1.16 µm. Whereas erosion-alone resulted in occlusal wear of 1.65 ± 0.13 µm and buccal 1.75 ± 0.03 µm. Microhardness testing at different loads revealed significantly greater hardness reductions in occlusal enamel vs. buccal enamel for 0.1 KgF indentations (P < 0.001) whereas in contrast 0.5 KgF indentations showed no differences. SignificanceWear simulation with CAD/CAM glass ceramic antagonists produced consistent wear in dental materials and human enamel, regardless of enamel surface origin. Lighter (0.1 KgF) hardness testing of occlusal vs. buccal origin revealed damage to the mechanical integrity of the superficial worn enamel.

α-Mangostin and lawsone methyl ether in tooth gel synergistically increase its antimicrobial and antibiofilm formation effects in vitro

Objectivesα-Mangostin (α-MG) and lawsone methyl ether (LME) show antimicrobial and anti-biofilm activities. The objectives of this study were to develop a herbal tooth gel containing α-MG and LME plus fluoride and determine its antimicrobial, anti-biofilm formation, anti-cancer, anti-inflammatory, wound healing, and enamel microhardness effects.MethodsAntimicrobial assays against Streptococcus mutans, Porphyromonas gingivalis, and Candida albicans were performed. The microbes’ ultrastructural morphology was assessed using Transmission Electron Microscopy. The effect on microbial biofilm formation was tested by a broth microdilution. Cell viability was assessed with MTT assay. The anti-inflammatory effect was investigated by measuring inhibition of nitric oxide production. Enamel microhardness was measured via Vickers microhardness testing. The enamel chemical composition was investigated with Fourier Transform Spectrometer. The enamel surface morphology and fluoride content were examined by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy.ResultsThe results show synergistic effects of α-MG and LME on antimicrobial activity and antibiofilm formation without cytotoxicity at a therapeutic dose. At a higher dose, the tooth gel inhibited proliferation of cancer cell line. Enamel microhardness was increased after brushing with the tooth gel plus fluoride. A large amount of fluoride was detected on the enamel surface.ConclusionThe tooth gel containing α-MG and LME synergized its antimicrobial activity and antibiofilm formation and inhibited oral cancer cell proliferation. Incorporating fluoride into the tooth gel increased enamel microhardness. Thus, the herbal tooth gel containing α-MG and LME plus fluoride may be useful for preventing dental caries and promoting oral health.

Color stability of bleached tooth enamel brushed with different stain-removing toothpastes.

The effects of four toothpastes on the color stability of in-office bleached tooth specimens were determined. We evaluated an experimental toothpaste (EXP) and three commercially available toothpastes: Colgate Optic White (OPW), Aquafresh White & Protect (AWP), and Crest 3D White (CDW). OPW, AWP, and CDW contained inorganic abrasives, whereas EXP and AWP contained sodium polyphosphate. Forty-eight randomly selected human-extracted maxillary central incisors were bleached and brushed twice daily over 30 days. We analyzed the final color difference (ΔE*ab, ΔE00 , ΔWID ), arithmetic average surface roughness (Ra) of the enamel measured on days 0 and 30, and scanning electron microscopy images of enamel surfaces and toothpastes. ΔE*ab, ΔE00 , ΔWID , and Ra were analyzed using one-way analysis of variance and Tukey's test (α = 0.05). ΔE*ab and ΔE00 values were significantly lower after toothbrushing with EXP, OPW, and CDW than with AWP. OPW induced the greatest positive ΔWID . Ra was significantly increased by OPW and CDW, but slightly increased by AWP, with cube-like particles, and EXP, with no particle-like structures. Only EXP stabilized the color of bleached teeth without increasing the enamel surface roughness. Sodium polyphosphate with approximately 10 phosphate groups was effective at removing stains. The effect of toothpaste on the color stability of bleached teeth depends on the constituting abrasives and chemical components. Polyphosphoric acid has different stain-removal effects depending on its degree of polymerization. Additionally, although certain types of abrasives may be effective for color stability, they also increase the surface roughness of the enamel.

The Effect of Hydrogen Peroxide Colloidal-Ag Used in Dental Unit Waterline on Shear Bond Strength of Orthodontic Brackets.

The quality of the water passing through the water lines is crucial to dental procedures. Studies on bracket adhesion of hydrogen peroxide colloidal-Ag, which is widely used to prevent biofilm formation, are limited in the literature. To determine whether disinfecting the dental units' waterlines (DUW) with hydrogen peroxide colloidal-Ag has any effect on the shear bond strength (SBS) of orthodontic brackets bonded to enamel. Sixty premolar teeth were divided randomly into two groups. The study and control groups consists of 30 teeth that were etched for 30 seconds with 37% phosphoric acid. Study groups washed with hydrogen peroxide colloidal-Ag water and the control group washed with municipal water. Transbond XT adhesive system was used to bond stainless steel brackets on all the teeth. A 300-g force was applied using a tension gauge to ensure a uniform adhesive thickness and light cured with 6 seconds. The SBS was quantified by means of a universal testing machine. The residual adhesive on the enamel surface was evaluated after debonding using the adhesive remnant index (ARI). The t-test results indicated that there were no significant differences in the SBS. The comparison of the results of ARI scores was found statistically insignificant. It has been found that hydrogen peroxide colloidal-Ag, which is used to reduce the amount of biofilm in DUW, does not have a negative effect on the adhesion of the brackets.

Dental microwear texture analysis reveals a likely dietary shift within Late Cretaceous ornithopod dinosaurs

AbstractDinosaurs were the dominant megaherbivores during the Cretaceous when angiosperms, the flowering plants, emerged and diversified. How herbivorous dinosaurs responded to the increasing diversity of angiosperms is largely unknown due to the lack of methods that can reconstruct diet directly from body fossils. We applied dental microwear texture analysis (DMTA), an approach that quantifies microtopography of diet‐induced wear marks on tooth surfaces, to ornithopods, the dinosaur clade that includes taxa with the most sophisticated masticatory system. We found that Late Cretaceous ornithopods have significantly rougher dental microwear texture (DMT) compared to pre‐Late Cretaceous ornithopods, and DMT variation increased in hadrosaurids, a derived Late Cretaceous ornithopod clade. These changes indicate a likely temporal dietary shift towards more abrasive foodstuffs within ornithopods, probably due to the increased ingestion of phytoliths (amorphous silica bodies in plants). Phytoliths are a main source of rough DMT in modern herbivores, along with exogenous dust and grit, and were generally more concentrated in Late Cretaceous angiosperms than in other major plant groups. Our results show that DMTA of the occlusal enamel surface can be used to reconstruct the diets of herbivorous dinosaurs, with a resolution superior to conventional methods.

Synthesis and characterization of hydroxyapatite nanoparticles and their effects on remineralization of demineralized enamel in the presence of Er,Cr: YSGG laser irradiation

BackgroundThis study aims to synthesize and characterize hydroxyapatite nanoparticles (nano-HA) and evaluate their effects on the remineralization of demineralized enamel in the presence to Er,CR: YSGG laser irradiation.Materials and methodsEnamel specimens from 44 human molars were divided into four groups: control, demineralized enamel, demineralized enamel treated with nano-HA, and demineralized enamel treated with nano-HA followed by Er,Cr:YSGG laser irradiation (0.5, 20 Hz, 60 µs, 20 s). Vickers microhardness test was used to evaluate the enamel surface hardness. The morphology and chemistry of enamel surfaces were assessed using scanning electron microscopy (SEM) and Raman spectroscopy, respectively.ResultThe result of this study showed that the application of Er,CR: YSGG laser irradiation to demineralized enamel treated with nano-HA had the highest impact on its microhardness.ConclusionER,CR: YSGG laser irradiation promotes enamel remineralization after treatment with nano HA.

Effects of topical fluoride on primary tooth enamel microhardness after diode laser treatment

ObjectivesTooth decay is controlled and prevented using fluorides. Specifically, a combination of laser irradiation and topical fluoride application can improve fluoride absorption. Although laser irradiation is recommended in traditional technology for caries prevention, little is known about the efficacy of caries-inhibiting laser diodes. Further, most studies have focused on permanent teeth. The objective of this study was to explore the effect of laser diode radiation mixed with topical fluoride on the enamel surface microhardness of primary teeth. Material and methodThe 60 primary teeth were divided into 60 plates. Baseline Vickers microhardness was established for each enamel surface. The samples were then divided into three groups. 4 % NaF varnish (group A) and 4 % NaF varnish using diode 2 and 3 W lasers (groups B and C, respectively). The final microhardness was measured and statistically evaluated using SPSS version 16. ANOVA was used to compare the means of the tested groups, which had a P-value of 0.05, indicating significance. ResultThe mean and standard deviation of microhardness for the different groups was tested. Group C (4 % NaF with a diode laser at 3 W) showed a higher average Vickers hardness (VHN) than Group B (4 % NaF with a diode laser at 2 W), whereas group A showed the lowest average VHN. There was a significant difference in microhardness between groups (P 0.05). ConclusionThis study explored the effect of laser mixed with topical fluoride on enamel surface microhardness of primary teeth. The use of a diode laser (Quanta System, Italy) with a fluoride varnish applied to the enamel surface has a greater effect on the resistance of the enamel to caries.

Evaluation of the shear bond strength of various adhesives on the surface of enamel irradiated with various doses of radiotherapy

We aimed to compare the shear bond strength (SBS) forces on the enamel surface with 2 adhesives after treatment with various radiation doses. A total of 120 premolars were included in the study. The teeth were randomly divided into 5 main groups (n= 24): negative control (without aging), positive control (with aging), 40 Gy, 60 Gy, and 70 Gy radiation. The 40 Gy, 60 Gy, and 70 Gy groups underwent conventional radiotherapy 5 days a week with a dose of 2 Gy each day. After the radiotherapy, all samples except the negative control group were subjected to thermal cycle aging. In all 5 groups, the specimens were divided into 2 subgroups, and half were bonded using 2 adhesives. After bonding, the universal Shimadzu test device was used to analyze the SBS. After the test, the tooth surfaces were examined under a stereomicroscope to determine the adhesive remnant index. When adhesives were compared, Biofix adhesive's bond strength value was statistically higher in the 40 Gy group than in the Transbond XT group (P= 0.001). The SBS value was higher in all irradiated groups than in nonirradiated groups (P= 0.001). When the adhesive remnant index score was analyzed, no significant difference was found among the groups. The SBS increased in irradiated teeth compared with unirradiated teeth, and the SBS values of both adhesives were within the acceptable limits in all radiation groups.

Impact of citric acid exposures on the erosion susceptibility and microhardness of anatomically different enamel surfaces

ObjectiveTo determine the indentation-load dependency of the observed changes in surface microhardness of occlusal and buccal enamel polished surfaces before and after a dietary acid exposure. MethodsEnamel specimens (n = 20) were obtained from previously extracted human molars. The samples were divided into two groups, buccal and occlusal (n = 10). Both groups were exposed to 0.3% citric acid at pH 2.7 over different time periods. The mean 3D step-heights defined by ISO 5436–1 standard of the erosion scar was calculated using a white light profilometer. Vickers microhardness testing was carried out to discriminate the surface mechanical changes and different loading regimens used to provide an estimate of depth related changes to the enamel sub-surface. Differences between groups were assessed using two-way ANOVA and post-hoc Sidak’s multiple comparisons tests at α = 0.05. ResultsA two-way ANOVA identified that erosion duration significantly influenced step-height (p < 0.01). The factorial analysis also identified a significant increase in step-height on occlusal surfaces compared to buccal surfaces (p < 0.01). At 5 min the mean 3D step-heights µm ± (SD) on the occlusal surface was 3.6 ± (0.65) and on the buccal surface was 3.1 ± (0.60) which increased after 60 mins to 32.9 ± (3.43) and 30.1 ± (3.34), respectively. In contrast to the non-eroded surface, increasing the indentation load on eroded enamel resulted in a significantly increased HV (p < 0.01) suggesting a significant modification to the enamel's response to an increasing indentation load. SignificanceOcclusal surfaces following acid exposure were more prone to erosion scar relative to buccal surfaces in vitro. Different loading regimens estimated the hardness of the erosive lesion from the outermost surface through the unaffected enamel.

Surface Roughness of Er, Cr: YSGG Laser Etched Enamel Compared to Acid Etching: An In Vitro Study

Objectives: Erbium-based lasers have been used in dentistry with different parameters for enamel conditioning with controversial results on the optimum parameter. This study aims to compare the surface roughness of enamel after conditioning by erbium, chromium-doped: Yttrium scandium-gallium-garnet (Er, Cr: YSGG) laser or 37% phosphoric acid and after remineralization, using a scanning electron microscope (SEM). Materials and Methods: Forty-five extracted premolars for orthodontic purposes were divided into three groups according to the conditioning technique. Group 1 conditioning by Er, Cr: YSGG laser 4.5 watts/30 Hz, Group 2 conditioning by Er, Cr: YSGG laser 4.5 watts/ 20 Hz, and Group 3 conditioning by 37% phosphoric acid. Surface roughness was measured using SEM after conditioning and after remineralization using Recaldent GC MI Paste Plus. Statistical analysis was done by one-way analysis of variance ANOVA test used to compare between groups, followed by Tukey’s post hoc test. Results: Enamel surface conditioned by Er, Cr: YSGG 4.5 watts/20 Hz laser had significantly less surface roughness than 37% phosphoric acid conditioned. After remineralization both the laser groups produced significantly lower surface roughness compared to acid conditioning. Conclusion: Er, Cr: YSGG laser conditioning of enamel surfaces (with 4.5 watts and 20 Hz/ 30 Hz frequency) produced less surface roughness which could be used as a promising alternative for acid conditioning. Clinical Relevance: laser conditioning of enamel using Er, Cr: YSGG with 4.5 watts could be a promising alternative for acid conditioning since it produces less surface roughness, less plaque accumulation on the surface, and less bacterial adhesion.

Synthesis and Characterization of Bioactive Glass and Zinc Oxide Nanoparticles with Enamel Remineralization and Antimicrobial Capabilities.

We investigated the effect of bioactive glass and zinc oxide nanoparticles on enamel remineralization, as well as their antimicrobial effect on cariogenic microbes. This is the first study that investigated the properties of bioactive glass and zinc oxide nanoparticles with mixed materials. Fluoride gel (F), bioactive glass microparticles (µB), bioactive glass nanoparticles (nB), zinc oxide nanoparticles (Z), and a mixed suspension of nB and Z (nBZ) were prepared and characterized by scanning and transmission electron microscopy, zeta potential measurement, X-ray diffraction, and acid buffering capacity testing. Further, we performed a remineralization cycle test of 28 days, and nanoindentation testing was carried out during the immersion period, and then the enamel surfaces were examined using scanning electron microscopy. Additionally, the antimicrobial effects of the sample suspensions were evaluated by measuring their minimum microbicidal concentrations against various cariogenic microbes. Our results revealed that nB had a near-circular shape with an amorphous structure and a considerably large specific surface area due to nanoparticulation. Additionally, nB possessed a rapid acid buffering capacity that was comparable to that of μB. In the remineralization test, faster recovery of mechanical properties was observed on the enamel surface immersed in samples containing bioactive glass nanoparticles (nB and nBZ). After remineralization, demineralized enamel immersed in any of the samples showed a rough and porous surface structure covered with mineralized structures. Furthermore, nBZ exhibited a broad antimicrobial spectrum. These results demonstrated that bioactive glass and zinc oxide nanoparticles have superior demineralization-suppressing and remineralization-promoting effects.

Effect of ER: YAG Laser Treatment on the Bond Strength of Self-adhesive Resin Cements on Contaminated and Non-contaminated Dentin Surface

Background: Nowadays, lasers are used to modify the surface of dentin and enamel and improve the surface bond with resin cement while contamination weakens this bond. Objective: This study aimed to evaluate the effect of different contamination types on the microshear bond strength (μSBS) of two self-adhesive resin cements to dentin with/without laser treatment. Methods: One-hundred and twenty molar teeth were prepared and randomly divided into three groups: blood, saliva, and control. In the blood group, blood was applied to the samples for 10 seconds; in the saliva group, saliva was applied to the samples for 10 seconds; and in the control group, distilled water was applied to the samples. Each group was further divided into two subgroups; in one, the Er: YAG laser was applied to samples for 5 seconds, and in the other, no laser treatment was performed. Next, TheraCem and Embrace WetBond cements were placed on each sample. μSBS was measured using a universal testing machine. Results: In Embrace WetBond, μSBS was not affected by contamination type regardless of laser treatment. In TheraCem, μSBS was not affected by contamination type when the laser was not used. In contrast, with laser treatment, blood contamination decreased μSBS compared to control and saliva. After laser treatment in the presence of blood, μSBS of Embrace WetBond was significantly higher than that of TheraCem, while without laser treatment, no significant difference was observed between the two cements. Conclusion: Dentin conditioning with an erbium laser can increase the cement bond strength to dentin if proper isolation is achievable. If proper isolation cannot be obtained, dentin conditioning with erbium laser followed by application of Embrace WetBond cement can increase the microshear bond strength of cement to dentin.

Effect of ER: YAG Laser Treatment on the Bond Strength of Self-adhesive Resin Cements on Contaminated and Non-contaminated Dentin Surface

Background: Nowadays, lasers are used to modify the surface of dentin and enamel and improve the surface bond with resin cement while contamination weakens this bond. Objective: This study aimed to evaluate the effect of different contamination types on the microshear bond strength (μSBS) of two self-adhesive resin cements to dentin with/without laser treatment. Methods: One-hundred and twenty molar teeth were prepared and randomly divided into three groups: blood, saliva, and control. In the blood group, blood was applied to the samples for 10 seconds; in the saliva group, saliva was applied to the samples for 10 seconds; and in the control group, distilled water was applied to the samples. Each group was further divided into two subgroups; in one, the Er: YAG laser was applied to samples for 5 seconds, and in the other, no laser treatment was performed. Next, TheraCem and Embrace WetBond cements were placed on each sample. μSBS was measured using a universal testing machine. Results: In Embrace WetBond, μSBS was not affected by contamination type regardless of laser treatment. In TheraCem, μSBS was not affected by contamination type when the laser was not used. In contrast, with laser treatment, blood contamination decreased μSBS compared to control and saliva. After laser treatment in the presence of blood, μSBS of Embrace WetBond was significantly higher than that of TheraCem, while without laser treatment, no significant difference was observed between the two cements. Conclusion: Dentin conditioning with an erbium laser can increase the cement bond strength to dentin if proper isolation is achievable. If proper isolation cannot be obtained, dentin conditioning with erbium laser followed by application of Embrace WetBond cement can increase the microshear bond strength of cement to dentin.

Evaluation of Dentin Tubule Occlusion Using Pre-Treatment with No-Ozone Cold Plasma: An In Vitro Study

Dentin hypersensitivity is a common disease of the oral cavity, which renders the tooth extremely sensitive to stimuli. These symptoms usually result from the exposure of the dentinal tubules to the external environment. There is a need for a treatment for dentinal hypersensitivity that can overcome the shortcomings of the existing agents. This study thus aimed to assess the therapeutic efficacy of no-ozone cold plasma (NCP), which was developed for safe use in the oral cavity, in conjunction with 1.23% acidulated phosphate fluoride (APF) and hydroxyapatite (HA), which are widely used conventional treatments of hypersensitivity. The fluoride content was evaluated using electron probe micro-analyzer (EPMA) analysis. Moreover, we confirmed the effect of NCP pre-treatment on the dentinal tubule occlusion by APF and HA as follows: scanning electron microscopy and energy dispersive X-ray spectrometry were employed to analyze the exposed dentinal tubules, and the calcium and phosphorus content were measured. Furthermore, an additional experiment was conducted using a metal mesh to analyze the working elements of NCP. All experimental results were analyzed by one-way analysis of variance and then by using the Turkey test as a post hoc test. EPMA analysis confirmed that the fluoride content of the APF and NCP group was significantly higher than that of the APF group (p &lt; 0.001). The fluoride content of the group treated with APF and NCP equipped with a metal mesh was significantly lower than that in the group treated with APF and NCP and the group treated with APF and NCP equipped with a cotton mesh (p &lt; 0.01). Moreover, the group treated with NCP pre-treated with HA and APF exhibited significantly greater dentinal tubule occlusion than the other groups (p &lt; 0.05). The same result was confirmed by calculating the calcium/phosphorus ratio (p &lt; 0.05). Pre-treatment of the enamel and dentin surfaces with plasma improved hypersensitivity by enhancing fluoride deposition with APF and dentinal tubule occlusion with HA.