Flexural Strength, Elastic Modulus and Remineralizing Abilities of Bioactive Resin-Based Dental Sealants

Objective: To assess the remineralizing abilities and compare the flexural strength and elastic modulus of different bioactive pit and fissure sealants. Materials and Methods: Human enamel samples were randomly and blindly sealed with one of the following bioactive materials: BioCoat (Bc), ACTIVA KIDS (Av) and BeautiSealant (Bu). Seal-it (Si) was used as a non-bioactive sealant beside a control blank (B) group with no sealant. The sealed samples were subjected to a pH-cycling model (7 days of demineralization–remineralization cycles). The enamel surface hardness change (SHC), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and polarized light microscopy were used to assess the remineralizing abilities of the studied sealants. Flexural strength and elastic modulus were also assessed following the ISO 4049 protocols. One-way analysis of variance (ANOVA) was used to analyze the results. Results: Bc sealant showed the highest FS and EM (p < 0.05). The contact with Bc and Bu sealants showed significantly lower %SHL (p < 0.05) in comparison to the other. These findings were supported by the results of SEM-EDX and polarized imaging by showing higher percentages of calcium and phosphate ions with the former sealants and thinner demineralized enamel bands. Conclusion: In this study, Bc showed the highest flexural strength. Bc and Bu sealants outperformed the other studied sealants in terms of their remineralization abilities.

Physical/Mechanical and Antibacterial Properties of Orthodontic Adhesives Containing Calcium Phosphate and Nisin

Enamel demineralization around orthodontic adhesive is a common esthetic concern during orthodontic treatment. The aim of this study was to prepare orthodontic adhesives containing monocalcium phosphate monohydrate (MCPM) and nisin to enable mineralizing and antibacterial actions. The physicomechanical properties and the inhibition of S. mutans growth of the adhesives with added MCPM (5, 10 wt %) and nisin (5, 10 wt %) were examined. Transbond XT (Trans) was used as the commercial comparison. The adhesive containing a low level of MCPM showed significantly higher monomer conversion (42–62%) than Trans (38%) (p < 0.05). Materials with additives showed lower monomer conversion (p < 0.05), biaxial flexural strength (p < 0.05), and shear bond strength to enamel than those of a control. Additives increased water sorption and solubility of the experimental materials. The addition of MCPM encouraged Ca and P ion release, and the precipitation of calcium phosphate at the bonding interface. The growth of S. mutans in all the groups was comparable (p > 0.05). In conclusion, experimental orthodontic adhesives with additives showed comparable conversion but lesser mechanical properties than the commercial material. The materials showed no antibacterial action, but exhibited ion release and calcium phosphate precipitation. These properties may promote remineralization of the demineralized enamel.

The study of the calcium and phosphorus metabolism impact on the development of demineralized enamel areas in adolescents

Relevance. The article presents the current data on the impact of calcium and phosphorus metabolism on the development of demineralized enamel areas in adolescents. The level of vitamin D3, osteocalcin, bone alkaline phosphatase isoenzyme and parathyroid hormone (PTH) in mixed saliva appeared to reflect the risk of the cariogenic situation in the oral cavity and the risk of enamel demineralization development, which are relevant in pediatric dentistry. Purpose – to reveal the relationship between the localized enamel demineralization and the calcium and phosphorus metabolism in teenagers.Materials and methods. In 45 adolescents, the study examined the vulnerability of hard dental tissues, including initial lesions and the mixed saliva mineral metabolism in teenagers. We formed the following groups to study the caries intensity level. Group 1 consisted of 12 adolescents with a DMF index of 3.8. 11 adolescents comprised group 2 and 11 adolescents – group 3 with DMF indices of 4.9 and 6.8, respectively; group 4 contained adolescents without caries.Results. The analysis of caries intensity and permanent enamel demineralization areas in adolescents and the main markers of mixed saliva mineralization revealed a correlation between the activity of the initial carious lesions and the calcium and phosphate metabolism.Conclusions. Evaluating the principal markers of calcium and phosphorus metabolism is relevant for the risk assessment of the cariogenic situation or enamel demineralization development in adolescents and preventive treatment planning.

The use of hydroxyapatite toothpaste to prevent dental caries

Dissolution of hydroxyapatite from the tooth structure at low pH can lead to the irreversible destruction of enamel and dentin, which if left untreated can result in pain and tooth loss. Hydroxyapatite toothpastes contain hydroxyapatite particles in micro- or nanocrystalline form that have been shown to deposit and restore demineralized enamel surfaces. As such, they are currently being explored as a fluoride-free anti-caries agent. This narrative review article aims to summarize the recent findings of the research investigating the remineralization potential of HAP toothpaste in vitro, in situ and in vivo, as well as some other applications in dentistry.

Effect of Amelogenin Solution in the Microhardness of Remineralized Enamel and Shear Bond Strength of Orthodontic Brackets

Objectives. To evaluate the microhardness of tooth enamel remineralized with enamel matrix protein solution as well as the shear bond strength of orthodontic brackets bonded to this surface. Materials and Methods. In total, 24 human premolars were selected and divided into 3 experimental groups (n = 8): SE—sound enamel, DE—demineralized enamel, and TE—demineralized enamel treated with amelogenin solution. Samples from DE and TE groups were subjected to pH cycling to induce initial artificial caries lesion. TE group was treated with amelogenin solution. Samples were placed in artificial saliva for 7 days. Knoop microhardness was measured before any intervention (T0), after pH cycling (T1) and after amelogenin solution treatment application (T2). Twenty-four hours after ceramic orthodontic brackets were bonded, samples were subjected to shear test in a universal testing machine. Microhardness and shear measurement distributions were subjected to Kolmogorov–Smirnov normality test, which was followed by parametric tests (α = 0.05): 2-way analysis of variance (factors: enamel condition × treatment) and Tukey posttest for all three groups (SE, DE, and TE) in T0 and T2 for microhardness; analysis of variance and Tukey’s test, for shear bond strength test. Results. Means recorded for Knoop microhardness in T2, for the SE (366.7 KHN) and TE (342.8 KHN) groups, were significantly higher than those recorded for the DE group (263.5 KHN). The shear bond strength of the SE (15.44 MPa) and TE (14.84 MPa) groups statistically differed from that of the DE group (11.95 MPa). Conclusion. In vitro demineralized enamel treatment with amelogenin solution was capable of taking samples’ hardness back to levels similar to those observed for sound enamel. The shear bond strength on the enamel subjected to this treatment was similar to that observed for healthy enamel and higher than that observed for demineralized enamel.

The Effects of Three Remineralizing Agents on the Microhardness and Chemical Composition of Demineralized Enamel

This study aimed to determine the effects of three different varnish materials (containing casein phosphopeptide-amorphous calcium phosphate, nano-hydroxyapatite, and fluoride) on enamel. Thirty-three extracted human third molars were used for specimen preparation. These were demineralized using phosphoric acid. Three experimental groups (n = 11) were treated with 3M™ Clinpro™ White Varnish, MI Varnish®, and Megasonex® toothpaste, respectively, every twenty-four hours for fourteen days. Analysis of the microhardness of the specimens’ enamel surfaces was carried out via the Vickers method, and by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Analysis was performed at three stages: at baseline value, after demineralization, and after the period of remineralization. Data were subjected to Scheffe’s post hoc test. The mean microhardness values (HV0.1) obtained for the group of samples treated with MI Varnish® were higher compared with the other two groups (p = 0.001 for both comparisons), while the first and third groups did not differ significantly from each other (p = 0.97). SEM analysis showed uneven patterns and porosities on all samples tested. EDS results showed an increase in the mineral content of the examined samples, with the highest mineral content observed in the MI Varnish® group. It can be concluded that MI Varnish® use has a better remineralization effect on enamel than the other two materials.

Orthodontic brackets’ shear bond strengths after applying remineralizing agents

Aim: The aim of this in vitro study was to measure the effects of white spot lesions treatment agents on the shear bond strengths (SBSs) and adhesive residual indexes (ARIs) of orthodontic brackets. Methodology: This study used 100 human premolar teeth randomly divided into five groups. Group 1 comprised those with intact enamel, Group 2 comprised those with demineralized enamel and Groups 3–5 comprised those demineralized enamel that was treated with casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACPF), fluoride varnish and a resin infiltrant, respectively. Brackets were bonded to the teeth using the conventional method, then the samples were thermocycled and tested for SBS using a universal testing machine. The adhesive remnant indexes (ARI) of the brackets were also evaluated. One-way ANOVA and post-hoc Tukey tests were used to compare the groups’ SBSs and the Kruskal–Wallis test was used to evaluate the groups’ ARI scores. Results were considered statistically significant if p was less than 0.05. Results: Statistically significant differences were found between the groups (F was 6.895 and p was less than 0.001). The SBSs of the brackets in Group 4 were significantly lower than those of the other groups (the mean was 13.44 ± 6.37 MPa). Group 5 had the highest mean SBS value (22.11 ± 6.56 MPa). Additionally, the ARI scores of the four groups were significantly different (p was less than 0.001). Conclusion: Resin infiltration and CPP-ACPF applications can improve bonds to demineralized enamel, while fluoride varnish applications are not recommended for such enamel. How to cite this article: Özant Y, Ay Ünüvar Y. Orthodontic brackets’ shear bond strengths after applying remineralizing agents. Int Dent Res 2021;11(2):67-74. https://doi.org/10.5577/intdentres.2021.vol11.no2.3 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Quantitative analysis of Protective Role of salivary protein on demineralization of enamel

Objective: The aim of this study was to analyze the effect of salivary proteins (statherin and histatin-1) on demineralized enamel surface and to study changes in texture, magnitude and direction of crystallites and changes in prismatic structure of enamel respectively. Material & Methods: Synchrotron x-ray diffraction technique to determine the variation in degree of crystal orientation (texture). Incisors were demineralized and sectioned to 300-500 microns, rinsed with salivary protein solutions of statherin and histatin separately and in combination with short and full-lengths. A beam spot size of 20μm × 20μm was used to obtain 2D diffraction patterns to distinguish orientation of crystallites. Results: The contour maps as well as the SEM analysis present similar surface properties of the sample treated with STN-21 and the controlled PBS sample. Therefore, STN-21 was found potent in preventing demineralization and restoring surface enamel texture followed by STN-21+HTN-21 and STN43+HTN38. HTN-21 and HTN-38 showed similar demineralization pattern as the controlled demineralized sample. Conclusion: Ranking of demineralization among samples was found to be controlled demineralized > HTN-21 = HTN-38 > STN-43+HTN-38 > STN-21+HTN-21 > STN-21. Developing STN-21 as a therapeutic against dental caries and erosion. Keywords: Enamel, Demineralization, salivary proteins.