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Abstract Background This 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 methods Enamel 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. Result The 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. Conclusion ER,CR: YSGG laser irradiation promotes enamel remineralization after treatment with nano HA.

Background: This 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 methods: Enamel 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. Result: The 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. Conclusion: ER,CR: YSGG laser irradiation promotes enamel remineralization after treatment with nano HA. [ABSTRACT FROM AUTHOR]

Background: To evaluate the preventive and therapeutic effects of CO2 laser and MI paste plus on intact and demineralized enamel surfaces and their impact on bacterial adhesion. Methods: 160 enamel slabs were prepared and randomly allocated into two main groups; sound and demineralized enamel (n = 80 per group), in which specimens were immersed in a demineralizing solution (50 mM acetic acid, pH 4.5) for 72 h at 37 °C. Each group was further divided into four subgroups (n = 20); the control (un treated surfaces), surfaces treated by CO2 laser, MI paste plus (Recaldent™, GC corporation/Germany), and those received a combination of CO2 and MI paste plus. Streptococcus Mutans biofilm was isolated, quantified, and then applied on treated enamel surfaces and incubated anaerobically for 24 h and then quantified by colony-forming unit (CFU). Meanwhile, surface changes were assessed by Vickers microhardness and Scanning Electron Microscope combined with Energy-Dispersive X-Ray Spectroscopy (SEM-EDX). Results: The combined use of CO2 laser followed by MI paste plus significantly (p

Resin infiltration (RI) is used to mask enamel opacities. There are three recommended etching cycles. However, anecdotal evidence suggests that favorable esthetics outcomes can be obtained by increasing the etching cycles. This study aimed to evaluate the effects of repeated etching cycles during RI application on esthetic changes and surface roughness of demineralized enamel at multiple treatment stages. Artificial demineralization was prepared on the buccal surface of ninety sound extracted premolars. The teeth were divided into nine groups (n = 10); with each consecutive group having one additional etching cycle up to nine etching cycles. Resin infiltrant was performed twice, first for 3 min (Resin 1) and again for 1 min (Resin 2). Surface roughness and esthetic changes were assessed using a profilometer (Ambios XP-200) and Minolta spectrophotometer, respectively, at baseline (sound enamel), etching, resin 1, resin 2, 7 days, and 28 days post resin applications. Data were analyzed with two-way ANOVA (p < 0.05). There was a significant interaction between the different stages and various groups of etching cycles on surface roughness, F(48, 126) = 3.48, p < 0.001. There was a significant interaction between the different stages and various groups of etching cycles on color changes, F(4, 126) = 1.177, p = 0.045. The surface roughness of demineralized enamel infiltrated with RI was less than that of sound enamel (baseline). There is a significant difference in color changes between resin 1 and resin 2 (p < 0.05). After five etching cycles, RI improved the esthetic of the color of teeth similar to the baseline. Surface roughness and color changes remained constant for 28 days. RI can be considered an effective and predictable treatment option for the restoration of early enamel lesions owing to its better surface characteristics and reliable masking effects. The color stability and surface roughness stay unaltered for up to 28 days. [ABSTRACT FROM AUTHOR]

Background: Dental enamel was treated with laser irradiation and fluoride compounds as a method to enhance fluoride absorption by the enamel, which resulted in a rise in the mineral content of the enamel and a significant boost in its resistance to acid demineralization. Objective: The purpose of this research was to look into the effects of Titanium tetra Fluoride (TiF4) with or without diode laser on the demineralized enamel. Material and methods: The sample consisted of 65 premolars teeth: 5 teeth remained sound for energy dispersive spectroscopy (EDS) analysis where 60 teeth were divided into 6 groups by treatment (N=10): (1) control negative (deionized water), (2) control positive (acidulated phosphate fluoride gel (APF)), (3) 6% Titanium tetra fluoride (TiF4) solution, (4) diode laser (810 nm, 0.5W, 60 s), (5) Laser then TiF4, and (6) Tif4 then Laser. Microhardness was measured before and after demineralization then after treatments. Five samples from each group were selected randomly for EDS analysis. Results: Microhardness increased significantly after all treatments (p<0.05). Results revealed a significant difference for all treatment groups (p<0.05). EDS analysis revealed that fluoride content was greater in 6%TIF4 then Tif4 with Laser groups, while the calcium content was greater in control positive followed by TiF4 groups. Conclusion: TiF4 alone or in combination with laser enhancing demineralized enamel microhardness and fluoride content. Diode laser before or after TiF4 had minimal extra impact on remineralization. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to evaluate the effectiveness of topical fluoride application and diode laser-irradiation on the hardness of demineralized enamel and to evaluate the esthetic improvement of the white spot lesions (WSLs) using a visual analog scale (VAS). Materials and Methods: Artificial WSLs (3x3 mm) were created on the enamel surface of 45 human third molars. The teeth were randomly assigned into three groups (n = 15): group A, fluoride only; group B, combined therapy of fluoride and diode laser; and group C, control. Vicker’s hardness number (VHN) was measured at baseline, after demineralization and after treatment. To evaluate the esthetic improvement after treatment, 14 raters evaluated each group’s photographs using a 100-millimeter VAS. A one-way ANOVA or Brown-Forsythe and Games-Howell post hoc procedure were performed for statistical analysis. The level of significance was set at α = 0.05 for all tests. Results: Group A mean VHN was significantly higher than groups B and C, and group B was significantly higher than group C (P

Resin infiltration (RI) is used to mask enamel opacities. There are three recommended etching cycles. However, anecdotal evidence suggests that favorable esthetics outcomes can be obtained by increasing the etching cycles. This study aimed to evaluate the effects of repeated etching cycles during RI application on esthetic changes and surface roughness of demineralized enamel at multiple treatment stages. Artificial demineralization was prepared on the buccal surface of ninety sound extracted premolars. The teeth were divided into nine groups (n = 10); with each consecutive group having one additional etching cycle up to nine etching cycles. Resin infiltrant was performed twice, first for 3 min (Resin 1) and again for 1 min (Resin 2). Surface roughness and esthetic changes were assessed using a profilometer (Ambios XP-200) and Minolta spectrophotometer, respectively, at baseline (sound enamel), etching, resin 1, resin 2, 7 days, and 28 days post resin applications. Data were analyzed with two-way ANOVA (p < 0.05). There was a significant interaction between the different stages and various groups of etching cycles on surface roughness, F(48, 126) = 3.48, p < 0.001. There was a significant interaction between the different stages and various groups of etching cycles on color changes, F(4, 126) = 1.177, p = 0.045. The surface roughness of demineralized enamel infiltrated with RI was less than that of sound enamel (baseline). There is a significant difference in color changes between resin 1 and resin 2 (p < 0.05). After five etching cycles, RI improved the esthetic of the color of teeth similar to the baseline. Surface roughness and color changes remained constant for 28 days. RI can be considered an effective and predictable treatment option for the restoration of early enamel lesions owing to its better surface characteristics and reliable masking effects. The color stability and surface roughness stay unaltered for up to 28 days.

Purpose: To investigate the influence of pretreating demineralized enamel with a caries infiltrant on the margin integrity of Class V composite restorations bonded with different adhesives. Materials and Methods: A total of 60 specimens from bovine incisors were demineralized (21 days, acid buffer, pH 4.95) to create artificial enamel lesions, and circular Class V cavities were prepared. Cavities of half of the specimens were treated with either an unfilled etch-and-rinse adhesive (Syntac Classic; Ivoclar Vivadent), a filled etch and-rinse adhesive (Optibond FL; Kerr), or a self-etch adhesive (iBond Self Etch; Heraeus Kulzer) (n = 10 per group). Demineralized enamel of the other half of the specimens was pretreated with a caries infiltrant (Icon; DMG) prior to adhesive application. All cavities were restored with a nanofilled composite material and thermocycled (5000 ×, 5°C-55°C). Margin integrity was evaluated using scanning electron microscopy, and the percentage of continuous margin was statistically analyzed (p < 0.05). Results: The significantly highest margin integrity was observed for Optibond FL, whether or not demineralized enamel was pretreated with the infiltrant. Pretreatment of demineralized enamel with the infiltrant resulted in a significant increase in margin integrity when the unfilled etch-and-rinse adhesive (Syntac Classic) or the self-etch adhesive (iBond Self Etch) was subsequently applied, but showed no significant improvement in combination with the filled etch-and-rinse adhesive (Optibond FL). Conclusion: Application of a caries infiltrant can improve margin integrity of composite fillings in demineralized enamel when used in combination with the examined self-etch and unfilled adhesives. [ABSTRACT FROM AUTHOR]

Purpose: The demand for esthetic dentistry has led to the development of new treatments for white spot lesions (WSLs). Microinvasive therapies, such as resin infiltration, have been used to treat demineralized enamel. Recently, resin infiltration using the active ingredient triethylene glycol dimethacrylate (TEGDMA), has been used to restore WSLs. The purpose of this narrative review is to evaluate the evidence on TEGDMA, an innovative resin that has been introduced, as an alternative dental material for treating WSLs. Methods: A review of the literature was conducted using key words pertaining to WSLs and resin infiltration including cosmetic dentistry; dental caries; dental materials; general dentistry; sealants; technology for patient care. Evidence was incorporated from biomedical data bases including PubMed and the Cochrane Library, which formed the framework for the review. Results: Based on the synthesis of the evidence, resin infiltration using TEGDMA is an effective alternative treatment option for WSLs. Studies suggest that the outcomes for micro-invasive procedures using resin infiltration may vary depending on the depth of the lesion. Conclusion: Resin infiltration, using TEGDMA, removes minimal amounts of enamel and preserves the hard tissue surrounding the WSLs. Additionally, TEGDMA restores the natural fluorescence, hardness, and texture of intact enamel. Future studies are needed to assess the long-term clinical effects of resin infiltration using this material on both permanent and primary dentition. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess the effect of application time on the microshear bond strength (μSBS) of three universal adhesives in demineralized and sound enamel before and after aging. Materials and methods: Bovine teeth (192) were prepared where buccal surfaces were ground and divided into two groups (sound enamel and demineralized enamel). The specimens in each group were divided into 12 subgroups by combining 3 adhesive agents (All-Bond Universal, Scotchbond Universal, and Tokuyama Universal Bond) × 4 adhesion strategy. Each adhesive was applied with either prolonged (PA) or reduced (RA) application time in etch-and-rinse or self-etch mode. Bonded composites were subjected to μSBS testing after 24-h or 2-year water storage. The results were evaluated using four-way ANOVA and Tukey's post-hoc test (α = 0.05). Results: The μSBS of adhesives to sound enamel in both etching modes was mostly similar to demineralized enamel, regardless of application time and aging time. At 24-h, all adhesives with PA in self-etch mode showed higher μSBS when compared with RA, except Tokuyama Universal Bond, but after 2-year aging, no significant difference was found in μSBS between RA and PA. The μSBS of adhesives with PA in etch-and-rinse mode depended on used adhesive and enamel condition compared to RA, regardless of μSBS testing time. Conclusions: PA of adhesives did not reveal a significant difference in μSBS to enamel, regardless of substrate type and etching mode. Clinical relevance: After 2-year aging, the bond strength of universal adhesives presented no significant difference between PA and RA treatments. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effectiveness of topical fluoride application and diode laser-irradiation on the hardness of demineralized enamel and to evaluate the esthetic improvement of the white spot lesions (WSLs) using a visual analog scale (VAS). Artificial WSLs (3x3 mm) were created on the enamel surface of 45 human third molars. The teeth were randomly assigned into three groups (n = 15): group A, fluoride only; group B, combined therapy of fluoride and diode laser; and group C, control. Vicker's hardness number (VHN) was measured at baseline, after demineralization and after treatment. To evaluate the esthetic improvement after treatment, 14 raters evaluated each group's photographs using a 100-millimeter VAS. A one-way ANOVA or Brown-Forsythe and Games-Howell post hoc procedure were performed for statistical analysis. The level of significance was set at α = 0.05 for all tests. Group A mean VHN was significantly higher than groups B and C, and group B was significantly higher than group C (P < 0.05). However, the mean VAS rating for the combined therapy group (B) was significantly higher than that for groups A and C (P < 0.05). Combination therapy significantly improved the esthetic appearance of WSLs compared to the fluoride only group. However, there was less enamel hardness versus treatment with fluoride only. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of experimental composites containing quaternary ammonium monomers (QAM) at different concentrations and alkyl chains on demineralization at enamel-composite margins after cariogenic challenge. Standardized 4 × 4 mm cavities were cut into 35 bovine enamel blocks, which were randomly divided into seven groups (n = 5) and restored with the following experimental composites and commercial materials: (G12.5) – 5% dimethylaminododecyl methacrylate (DMADDM) with a 12-carbon alkyl chain (G12.10) – 10% DMADDM, (G16.5) – 5% dimethylaminohexadecyl methacrylate (DMAHDM) with a 16-carbon alkyl chain (G16.10) – 10% DMAHDM, (CG) – control group (without QAM), (GZ250) – commercial composite (Filtek Z250®), and (GIC) – glass ionomer cement (Maxxion R®). After restorative procedures, initial microhardness was measured and experimental composites were subjected to Streptococcus mutans biofilm formation for 48 h. After cariogenic challenge, the samples were washed and microhardness was reassessed. A 3D non-contact profilometer was used to determine surface roughness and enamel demineralization was assessed by micro-CT. Microhardness results were analyzed by the Kruskal–Wallis and Mann-Whitney tests and micro-CT results were analyzed by Tukey's HSD test (95% confidence interval). None of the materials could prevent mineral loss at the enamel-restoration margins. The addition of 10% DMAHDM yielded the lowest, albeit statistically significant, mineral loss (p < 0.05). 3D non-contact profilometry showed enamel surface roughness modification after biofilm exposure. The CG had the highest roughness values. Micro-CT analysis revealed mineral loss, except for GIC. The addition of 10% QAM with a 16-carbon chain in experimental composites reduced mineral loss at the enamel-restoration margins after cariogenic challenge. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate margin integrity of Class V composite restorations in demineralized and sound enamel after bonding with different etch-and-rinse and self-etch adhesive systems. Out of a total of 60 specimens from bovine incisors, 30 specimens were demineralized (21 days, acid buffer, pH 4.95) to create artificial enamel lesions. Circular Class V cavities were prepared in all 60 specimens and treated with either an unfilled etch-and-rinse adhesive (Syntac Classic; Ivoclar Vivadent), a filled etch-and-rinse adhesive (Optibond FL; Kerr), or a self-etch adhesive (iBond Self Etch; Heraeus) (n = 10 per group). The cavities were restored with a nanofilled resin composite and thermocycled (5000×, 5–55 °C). Scanning electron microscopy was used to evaluate margin integrity of the composite restorations, and the percentage of continuous margin was statistically analyzed (α = 0.05). Demineralized enamel led to a significantly lower margin integrity when the self-etch adhesive iBond Self Etch was applied, but did not affect margin integrity when the etch-and-rinse adhesives Optibond FL (filled) or Syntac Classic (unfilled) were used. No significant differences in margin integrity in sound and demineralized enamel were observed between the different adhesives. Demineralized enamel reduces margin integrity of composite restorations when bonded with a self-etch adhesive, but does not affect margin integrity when an etch-and-rinse approach is used. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the microshear bond strength of five universal adhesives for use with demineralized enamel, with and without pre-etching. Using five universal adhesives (Single Bond Universal (SBU), Clearfil Universal (CU), Prime&Bond Elect Universal (PBU), Bisco All Bond Universal (ABU), Gluma Bond Universal (GU)), composite cylinders were bonded to the labial surfaces of extracted upper incisor teeth, with or without pre-etching. A micro-shear bond strength test was performed. The debonding surfaces were evaluated with the use of SEM. The data was analyzed using one-way ANOVA and Tukey's Post-hoc tests. SBU, ABU, and PBU increased the bond strength statistically when used in etch&rinse mode (p < 0.05). GU and CU did not change the bond strength statistically with the use of pre-etching (p > 0.05). The bond strength of universal adhesives on demineralized enamel, with and without initial acid etching, depends on the type of adhesive system used. [ABSTRACT FROM AUTHOR]

Background: Enamel mineral density is dependent on a balanced dynamic process of demineralization and remineralization. Objective: We evaluated the remineralization potential of experimental calcium- containing primer (CaP) application on enamel subsurface lesions. Methods: Demineralized enamel samples obtained from bovine incisor teeth were prepared and cut buccolingually. All samples were divided into 4 main groups according to the type of primer: CLEARFIL SE BOND 2 Primer (SEP), experimental calcium-containing primer (CaP) and bond: CLEARFIL SE BOND 2 Bond (SEB), CLEARFIL Protect Bond (PBB) treatment: (1) SEP-SEB (2) SEP-PBB (3) CaP-SEB (4) CaP-PBB. Each group was subdivided according to storage time in artificial saliva: immediately, 1 month and 6 months. Then, the samples were analyzed using transverse micro radiography (TMR). Additionally, the samples treated with each primer were prepared for scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) observation. Two-way ANOVA was used for the statistical analysis of mineral loss (ΔZ: vol%·µm). Results: CaP-PBB had the significantly lowest ΔZ at all storage times, while SEP-SEB had the highest ΔZ (p < 0.05). SEM observations revealed that new crystals were formed on the surface after 6 months, and the ratio of calcium on the enamel increased in the EDS analysis. Conclusion: Experimental calcium-containing primer can provide additional mineral deposition, with even further deposition when combined with a fluoride-containing bond.

Good margin integrity with a tight seal of the adhesive interface is considered one of the key factors for the clinical success of composite restorations. This study investigated the effect of enamel etching with phosphoric acid on the margin integrity of self-etch bonded composite restorations in demineralized enamel. Crowns of bovine incisors were assigned into 14 groups (n = 10 per group) of which ten groups (groups 1–5 and 8–12) were demineralized (21 days, acid buffer, pH 4.95) to create artificial carious lesions. Standardized Class V cavities were prepared in all specimens. Demineralized groups were either etched with phosphoric acid for 10, 30, 60, or 120 s (groups 2–5 and 9–12), or no etching was performed (groups 1 and 8). The non-demineralized (sound) groups were etched for 10 s (groups 7 and 14) or remained non-etched (groups 6 and 13). Resin composite restorations were then placed using either a one-step (iBond Self Etch, groups 1–7) or two-step self-etch adhesive (Clearfil SE Bond, groups 8–14). Margin integrity of the restorations was assessed after thermocycling (5000×, 5–55 °C) using scanning electron microscopy, and the percentage of continuous margins (%CM) was statistically analyzed (α = 0.05). Phosphoric acid etching significantly increased %CM in both demineralized and sound enamel. For iBond Self Etch, a significant increase in %CM in demineralized enamel was observed with increased etching times. All etched groups treated with Clearfil SE Bond and those etched for 60 or 120 s and treated with iBond Self Etch showed similar %CM in demineralized enamel as in etched sound enamel, and significantly higher %CM than in non-etched sound enamel. In conclusion, enamel etching with phosphoric acid improves margin integrity of composite restorations in demineralized enamel when bonded with the examined adhesives.

Background: To evaluate the preventive and therapeutic effects of CO 2 laser and MI paste plus on intact and demineralized enamel surfaces and their impact on bacterial adhesion. Methods: 160 enamel slabs were prepared and randomly allocated into two main groups; sound and demineralized enamel (n = 80 per group), in which specimens were immersed in a demineralizing solution (50 mM acetic acid, pH 4.5) for 72 h at 37 °C. Each group was further divided into four subgroups (n = 20); the control (un treated surfaces), surfaces treated by CO 2 laser, MI paste plus (Recaldent™, GC corporation/Germany), and those received a combination of CO 2 and MI paste plus. Streptococcus Mutans biofilm was isolated, quantified, and then applied on treated enamel surfaces and incubated anaerobically for 24 h and then quantified by colony-forming unit (CFU). Meanwhile, surface changes were assessed by Vickers microhardness and Scanning Electron Microscope combined with Energy-Dispersive X-Ray Spectroscopy (SEM-EDX). Results: The combined use of CO 2 laser followed by MI paste plus significantly (p < 0.000) enhanced surface microhardness of sound and demineralized enamel with a significant reduction in bacterial counts. However, each technique alone was beneficial as they exhibited higher microhardness with lower bacterial viability in comparison to the control. The treatment of demineralized enamel surfaces with MI paste significantly reduced the number of bacterial colonies with the presence of dispersed mineral deposits over the surface., Conclusions: The combined use of CO 2 laser and MI paste plus was effective as a preventive and/or therapeutic measures in enhancing surface properties of enamel and reducing the bacterial viability., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

The aim was to evaluate the effect of fluoride varnish on the shear bond strength (SBS) on polished and non-polished intact and demineralized enamel. Bovine incisors (half demineralized) were used. Bifluorid 12™ was applied. Bonding was made with Futurabond®M + and GrandioSO, 24 h and 7 days after varnishing. In some groups, varnish was removed by polishing before bonding. SBS was measured. Fracture type was determined by stereomicroscopy and scanning electron microscope (SEM) observations of the enamel surface were made. Between-group differences were determined by one-way ANOVA and the Tukey test. Associations between study factors and fracture modes were analysed using contingency tables and Pearson’s chi-squared test. For intact enamel, SBS on varnished enamel at 24 h was significantly less than in the other groups. SBS recovered 7 days after varnishing. Varnish elimination after 24 h significantly increased the SBS. However, removal at 7 days did not modify SBS. SBS on demineralized enamel groups was significantly less than in intact enamel, except for demineralized enamel varnished and removed at 7 days. Demineralized enamel was associated with cohesive enamel fractures and intact enamel with cohesive fractures of the composite and adhesive fractures. SEM of varnish surfaces showed a homogenous layer scattered with amorphous precipitate. In conclusion, on intact enamel fluoride varnish had a negative effect on SBS at 24 h, which disappeared after 7 days. On demineralized enamel, varnish did not reduce SBS at either time. Polishing the varnished enamel surface showed a similar SBS to intact enamel after 7 days. [ABSTRACT FROM AUTHOR]

This study investigated the combining effect of cold plasma and bioglass-phosphoric acid paste on demineralized enamel. Fifty bovine incisors' enamel specimens were challenged by a demineralization solution of pH 4.47 for 72 h. Specimens were divided into five groups: (I) Control, demineralized enamel (C); (II) Demineralized enamel treated with fluoride varnish (F); (III) Cold plasma application to demineralized enamel (P); (IV) Demineralized enamel treated with bioglass paste (B); (V) Application of bioglass paste to cold plasma-treated demineralized enamel (PB). Specimens were then immersed in remineralizing solution for 24 h, before being examined with micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and cross-sectional micro-hardness measurement. The results showed that; treating demineralized enamel with cold plasmas before bioglass application ensued a significant high mineral volume recovery and micro-hardness of demineralized region. It can be concluded that cold plasmas may improve the remineralization of bioglass on demineralized enamel. [ABSTRACT FROM AUTHOR]

ABSTRACT Physiological oral mechanical forces may play a role on the progression of enamel carious lesions to cavitation. Thus, the aim of this study was to describe, by 3D finite element analysis, stress, and strain patterns in sound and carious enamel after a simulated occlusal load. Micro-CT based models were created and meshed with tetrahedral elements (based on an extracted third molar), namely: a sound (ST) and a carious tooth (CT). For the CT, enamel material properties were assigned according to the micro-CT gray values. Below the threshold corresponding to the enamel lesion (2.5 g/cm3) lower and isotropic elastic modulus was assigned ( E = 18 GPa against E1 = 80 GPa, E2 = E3 = 20 GPa for sound enamel). Both models were imported into a FE solver where boundary conditions were assigned and a pressure load (500 MPa) was applied at the occlusal surface. A linear static analysis was performed, considering anisotropy in sound enamel. ST showed a more efficient transfer of maximum principal stress from enamel to the dentin layer, while for the CT, enamel layer was subjected to higher and concentrated loads. Maximum principal strain distributions were seen at the carious enamel surface, especially at the central fossa, correlating to the enamel cavity seen at the original micro-CT model. It is possible to conclude that demineralized enamel compromises appropriate stress transfer from enamel to dentin, contributing to the odds of fracture and cavitation. Enamel fracture over a dentin lesion may happen as one of the normal pathways to caries progression and may act as a confounding factor during clinical diagnostic decisions. Microsc. Res. Tech. 78:865-872, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Remineralization might be hampered by various polymers used in saliva substitutes. Thus, the present study evaluated the effects of various calcium and phosphate concentrations of linseed-based solutions on the mineral loss of pre-demineralized bovine enamel in vitro. A commercially available saliva substitute (Salinum®) based on linseed was tested as well. Enamel specimens were prepared from bovine incisors and embedded in epoxy resin. One-third of each sample was covered with nail varnish (control of sound enamel). After demineralization (37 °C; pH 5.0; 14 days) another third of the samples was nail-varnished again. Subsequently, the specimens ( n = 10) were exposed to 12 linseed-based solutions (Ca2+ addition 0–2 mM; PO − addition 0–3.2 mM) at pH 5.5 and 6.5 as well as to Salinum® for 14 days (37 °C). The differences in mineral loss between the values prior to and after the storage in the various solutions were evaluated from microradiographs of thin sections (100 μm). The general linear model revealed a significant dependency for the mineral loss on ‘calcium’ ( P = 0.003), but not on ‘pH’ ( P = 0.397) and ‘phosphate’ ( P = 0.094). Salinum® induced a significant greater mineral loss compared with equivalently saturated solutions ( P < 0.05;anova, Bonferroni). The solution with the highest calcium and phosphate concentration showed the greatest mineral gain ( P = 0.033; paired t-test). The addition of calcium and phosphate seems to have a positive effect on the remineralizing qualities of linseed-based saliva substitutes. [ABSTRACT FROM AUTHOR]

Background: Enamel mineral density is dependent on a balanced dynamic process of demineralization and remineralization. Objective: We evaluated the remineralization potential of experimental calcium- containing primer (CaP) application on enamel subsurface lesions. Methods: Demineralized enamel samples obtained from bovine incisor teeth were prepared and cut buccolingually. All samples were divided into 4 main groups according to the type of primer: CLEARFIL SE BOND 2 Primer (SEP), experimental calcium-containing primer (CaP) and bond: CLEARFIL SE BOND 2 Bond (SEB), CLEARFIL Protect Bond (PBB) treatment: (1) SEP-SEB (2) SEP-PBB (3) CaP-SEB (4) CaP-PBB. Each group was subdivided according to storage time in artificial saliva: immediately, 1 month and 6 months. Then, the samples were analyzed using transverse micro radiography (TMR). Additionally, the samples treated with each primer were prepared for scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) observation. Two-way ANOVA was used for the statistical analysis of mineral loss (ΔZ: vol%·µm). Results: CaP-PBB had the significantly lowest ΔZ at all storage times, while SEP-SEB had the highest ΔZ (p < 0.05). SEM observations revealed that new crystals were formed on the surface after 6 months, and the ratio of calcium on the enamel increased in the EDS analysis. Conclusion: Experimental calcium-containing primer can provide additional mineral deposition, with even further deposition when combined with a fluoride-containing bond. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effects of remineralizing agents on the shear bond strength (SBS) of orthodontic brackets bonded to intact and demineralized enamel., Material and Methods: In this in-vitro study, 160 human premolars were divided into 8 groups, including group 1 with intact enamel as the positive control, group 2 with demineralized enamel as the negative control, groups 3-5 treated with fluoride varnish, Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) and resin infiltrant on intact enamel, and groups 6-8 treated with the same agents on demineralized enamel. Brackets were bonded using the conventional method, and the samples were thermocycled. SBS of the brackets was measured using a universal testing machine, and the adhesive remnant index (ARI) was assessed. Data were analysed with one-way ANOVA and post hoc statistical test at the significance level of 0.05., Results: SBS of the brackets in all groups with intact enamel was higher than that of their counterparts on demineralized enamel, which was only significantly different between groups 1 and 2 (P-value<0.001). SBS values of groups 7 and 8 were not significantly different from group 1 (P-value=1), yet the application of fluoride varnish on both intact (P-value=0.091) and demineralized enamel (P-value<0.001) created less SBS than in group 1., Conclusions: All pre-treatment methods increased SBS of the brackets bonded to demineralized enamel, yet only the resin infiltrant and CPP-ACP produced SBS similar to that of intact enamel. Also, the use of fluoride varnish on intact enamel significantly reduced SBS., (Copyright © 2021 CEO. Published by Elsevier Masson SAS. All rights reserved.)

The self-made demineralized teeth samples treated with preamble resin to seal or not were observed under electron microscopy and tested microhardness value to show surface structure and hardness of demineralized enamel.The experimental results showed that the permeable resin formed longer resin tags on the surface of the enamel and a lot of cracks in the deep part which has a higher microhardness value than ordinary enamel. [ABSTRACT FROM AUTHOR]

Good margin integrity with a tight seal of the adhesive interface is considered one of the key factors for the clinical success of composite restorations. This study investigated the effect of enamel etching with phosphoric acid on the margin integrity of self-etch bonded composite restorations in demineralized enamel. Crowns of bovine incisors were assigned into 14 groups (n = 10 per group) of which ten groups (groups 1–5 and 8–12) were demineralized (21 days, acid buffer, pH 4.95) to create artificial carious lesions. Standardized Class V cavities were prepared in all specimens. Demineralized groups were either etched with phosphoric acid for 10, 30, 60, or 120 s (groups 2–5 and 9–12), or no etching was performed (groups 1 and 8). The non-demineralized (sound) groups were etched for 10 s (groups 7 and 14) or remained non-etched (groups 6 and 13). Resin composite restorations were then placed using either a one-step (iBond Self Etch, groups 1–7) or two-step self-etch adhesive (Clearfil SE Bond, groups 8–14). Margin integrity of the restorations was assessed after thermocycling (5000×, 5–55 °C) using scanning electron microscopy, and the percentage of continuous margins (%CM) was statistically analyzed (α = 0.05). Phosphoric acid etching significantly increased %CM in both demineralized and sound enamel. For iBond Self Etch, a significant increase in %CM in demineralized enamel was observed with increased etching times. All etched groups treated with Clearfil SE Bond and those etched for 60 or 120 s and treated with iBond Self Etch showed similar %CM in demineralized enamel as in etched sound enamel, and significantly higher %CM than in non-etched sound enamel. In conclusion, enamel etching with phosphoric acid improves margin integrity of composite restorations in demineralized enamel when bonded with the examined adhesives. [ABSTRACT FROM AUTHOR]

Aims: This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel., Materials and Methods: The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups., Results: There were significant differences in the color change between T2 and T3 (ΔE T2-T3) and T2 and T4 (ΔE T2-T4) stages among the study groups (p<0.05). Pairwise comparison by Duncan test revealed that both ΔET2-T3 and ΔET2-T4 were significantly greater in demineralized teeth submitted to laser-assisted in-office bleaching (group 1) as compared to the other groups (P< 0.05)., Conclusion: Laser-assisted in-office bleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth.