Tooth Enamel Research Articles

Effects of experimental in-office bleaching gels incorporated with co-doped titanium dioxide nanoparticles on dental enamel physical properties.

To evaluate the physical properties of enamel submitted to hydrogen peroxide (HP) incorporated with titanium dioxide nanoparticles (NP) co-doped with nitrogen and fluorine and irradiated with violet LED light (LT). Enamel-dentin disks were randomly allocated (T0) into groups, according to HP (HP6, HP15, or HP35) and NP (no NP, 5NP, or 10NP) concentrations, and irradiated or not with LT. A negative control (NC) group was set. After three bleaching sessions (T1, T2, and T3), specimens were stored in saliva for 14days (T4). Enamel surface microhardness number (KHN), surface roughness (Ra), cross-sectional microhardness (ΔS), energy-dispersive spectroscopy (EDS), scanning electron (SEM), and polarized light (PLM) microscopies were performed. Surface KHN was significantly influenced by NP over time, independently of LT irradiation. At T3 and T4, gels with 5NP and 10NP exhibited no KHN differences compared to NC and baseline values, which were not observed under the absence of NP. NP incorporation did not statistically interfere with the ΔS and Ra. PLM images exhibited surface/subsurface darkening areas suggestive of demineralizing regions. SEM demonstrated some intraprismatic affection in the groups without NP. EDS reported a higher enamel calcium to phosphorus ratio following 10NP gels applications. Gels with NP maintained the enamel surface microhardness levels and seemed to control surface morphology, upholding the mineral content. None of the proposed experimental protocols have negatively influenced the enamel surface roughness and the cross-sectional microhardness.

Limosilactobacillus reuteri and Its Probiotic Potential against Cariogenic Bacteria

Bacteriotherapy is a promising option in addressing dental caries, a persistent global public health challenge with multifactorial origin, including dysbiosis. Despite the exploration of various probiotics, outcomes remain inconclusive. Objective: This study aimed to assess the inhibitory potential of L. reuteri and other potential probiotics like S. salivarius and S. oralis on the growth, adhesion, colonization, and viability of major cariogenic pathogens, comparing their probiotic efficacy. Methods: An in vitro experimental study was conducted, encompassing direct competition assays in solid and liquid co-culture tests and the characterization of adhesion to dental enamel and cell viability by life or death assay. Results: L. reuteri exhibited the significant inhibition of S. sobrinus and S. mutans growth in both solid and liquid cultures, with statistically notable differences. Scanning electron microscopy and confocal microscopy demonstrated reduced cariogenic biofilm formation when combined with L. reuteri, corroborated by diminished bacterial viability and decreased dental enamel coverage. These findings underscore L. reuteri’s potential as an effective agent in caries prevention. Conclusion: The study suggests L. reuteri could serve as an effective probiotic in bacteriotherapy against dental caries. It displayed substantial inhibitory activity in vitro against cariogenic bacteria, impeding biofilm formation and adhesion, thereby impacting cell viability.

Oral Health and Caries Prevention: How Tongue Hygiene Helps Maintain Balance of Microbiota and Overall Health in Pediatric Patients.

The tongue harbors about two-thirds of the microorganisms present in the mouth; the stable bacterial population consists mainly of aerobic and facultative anaerobic streptococci. These bacterial colonies, found more frequently on the tongue than on the outside of the hard part of the dental enamel in children younger than 18 months, suggest that the tongue is a potential bacterial reservoir. The aim of this review is to examine the scientific literature to clarify whether the mechanical removal of bacterial biofilm on the tongue can have a positive effect on caries prevention, with the reduction in colony-forming unit (CFU) of salivary streptococcus and the whole-mouth plaque index (FMPS). An open literature search was conducted by using PubMed (MEDLINE), Cochrane Library and Google Scholar. The most studied age range was 9 to 12 years, with groups of children with no caries and groups with a minimum number of two teeth that were reconstructed, decayed and/or missing (DMFS/dmfs > 2) who experienced different tongue hygiene methods for the first time. Four randomized trials met the search criteria and were included in this review. The results obtained suggest that specific tongue hygiene protocols, combined with a healthy diet and lifestyle, could be considered the gold standard to enable more effective primary prevention and improve the health of pediatric patients. This review improves the understanding of the impact of tongue hygiene in controlling the bacteria responsible for the onset of carious disease and its systemic correlates; however, further research with more data is needed to further confirm the findings of this research.

Theobromine for Remineralization of White Spot Lesions on Dental Enamel: A Systematic Review and Meta-analysis.

This systematic review and meta-analysis evaluated theobromine's (Theobroma cacao) potential in remineralizing white spot lesions in dental enamel. Methods: This study is reported according to the PRISMA checklist and was registered in PROSPERO (CRD42023414371). In vitro tests that evaluated the remineralizing potential of theobromine compared to fluoride ion after demineralization for the formation of white spot lesions on enamel were selected, with no limitation on the year of publication. Electronic searches were performed in PubMed/MEDLINE, Scopus, and Web of Science by two independent researchers. Thirty articles were received of which six were selected according to the inclusion criteria. The selected studies evaluated the Enamel Surface Microhardness (SMH), Vickers or Knoop, before and after treatment with theobromine and fluoride solutions. For the SMH Vickers, there were no differences between groups at baseline (p=1.00; mean difference: -0.00; CI: -11.36 to 11.36) and after treatment (p=0.51; mean difference: 4.12; CI: -8.16 to 16.41). The results of SMH Knoop showed differences between groups at baseline, favoring the experimental group (p=0.002; mean difference: 9.84; CI: 3.65 to 16.02) and after treatment favoring the control group (p=0.00001; mean difference: -5.45; CI: -7.62 to -3.27). The use of theobromine increases the microhardness of dental enamel subjected to a demineralization process, thus being effective in the remineralization of this tissue with success equivalent to that obtained with the use of fluoride.

The Potential Effect of Bisphosphonate on Teeth Enamel and Dentin Formation in Both Normal and Osteoporotic Albino Rats

The Potential Effect of Bisphosphonate on Teeth Enamel and Dentin Formation in Both Normal and Osteoporotic Albino Rats

The Application of Resin Infiltration Combined with Nano-Hydroxyapatite in the Treatment of Post-Orthodontic White Spot Lesions

This study aims to investigate whether the combination of resin infiltration and nanohydroxyapatite (nHA) can provide a synergistic treatment for post-orthodontic white spot lesions (WSL), thus establishing an experimental basis for its treatment. For this study, a total of 60 bicuspid teeth that required extraction due to orthodontics were collected. Orthodontic models were established for each tooth sample, and demineralization staining was conducted using Coca-Cola. The dental samples were randomly divided into 4 groups: control group, nHA group, resin infiltration group, and resin infiltration+nHA group. The demineralized samples were remineralized with 10% nHA and Icon resin infiltration, respectively. The samples were subjected to color difference observation, microhardness test, energy-dispersive X-ray spectrum analysis, and surface roughness detection. The results showed that the tooth surface of the control group was rough and dull after demineralization. The area around the bracket exhibited a brown color, greatly contrasting with the color of the surrounding tooth enamel. After the remineralization treatment with nHA and resin infiltration, the color difference decreased significantly and the microhardness increased. A significant difference was observed between the nHA group and the resin infiltration group (P < 0.05). However, the combination of resin infiltration and nHA exhibited superior staining resistance and improved WSL microhardness value. Additionally, nHA was found to enhance the mass ratio and molar ratio of calcium to phosphorus in WSL samples, while also reducing the surface roughness Ra, demonstrating a greater effectiveness compared to resin infiltration. The use of nHA following resin infiltration led to a significant improvement in mineral deposition and a substantial reduction in surface roughness. In conclusion, both resin infiltration and nHA play a crucial role in promoting enamel remineralization, offering their respective advantages in reducing color difference, increasing microhardness and calcium and phosphorus content, and reducing surface roughness in WSL samples. Remarkably, the combined application of resin infiltration and nHA enables resin infiltration to improve the remineralization and anti-coloring ability in WSL, while preserving its aesthetic effects. This combination demonstrates a positive application outcome.

Inorganic Phosphate Effect in a Hydrogen Peroxide-based Bleaching Agent: Physicochemical, Mechanical, and Morphological Properties of Dental Enamel.

This in vitro study aimed to assess the impact of incorporating calcium glycerophosphate (CaGP) and sodium fluoride (NaF) in addition to 35% hydrogen peroxide concerning the enamel mechanical and morphological properties. Specimens of bovine enamel were chosen based on their initial surface hardness (SHi) and subsequently divided into five gel groups (n=12): 1) 35% Hydrogen Peroxide (HP) Gel; 2) HP + 0.1% NaF Gel (HP/NaF); 3) HP + 0.25% CaGP Gel (HP/CaGP); 4) HP + 0.1% NaF + 0.25% CaGP Gel (HP/NaF/CaGP) and 5) HP Blue 35% Gel (HP Blue). The bleaching gels were applied thrice, for 40 min, at intervals of 7 days each. After 21 days, the final surface hardness (SHf), integrated hardness (IH), Polydispersity Index (PdI) and Zeta Potential (Zp), surface roughness (Ra, after and before), and surface/structural analysis by Scanning Electron Microscopy (SEM) were determined. The data were submitted to ANOVA (one-way and two-way) followed by the Student-Newman-Keuls test (α=0.05). The addition of NaF to HP reduced demineralization by 11.5% in relation to HP (p<0.05). The NaF/CaGP association reduction is 22.8 and 20% higher in comparison to HP/NaF/CaGP and HP Blue, respectively. The IH when the PH/NaF/CaGP bleaching gel was applied, was 14% higher compared to HP and HP Blue groups. It can be concluded that the association of NaF and CaGP with the 35% hydrogen peroxide gel (HP/NaF/CaGP) significantly changed tooth enamel demineralization in terms of surface, depth, roughness, and enamel morphology.

Evaluation of Antimicrobial Efficiency, Shear Bond Strength, and Adhesive Remnant Index of TiO2 Infiltrated Orthodontic Adhesive - An In Vitro Study.

Enamel demineralization is an unavoidable adverse effect encountered with bonding brackets in orthodontic therapy. Introducing nanoparticles into the composite adhesive paste can prevent enamel demineralization. Titanium dioxide (TiO2) is known to exhibit direct antimicrobial efficiency. This study aimed to assess the antibacterial efficiency and shear bond strength (SBS) of an orthodontic bonding composite infiltrated with TiO2 nanoparticles. This in vitro study evaluated the efficiency of TiO2 nanoparticle-incorporated light-curing orthodontic composite paste (ENLIGHT, ORMCO). Twenty extracted premolars were randomly and equally allocated to the two study groups, N = 10. While a conventional composite was utilized for the bonding brackets in Group I, a TiO2-incorporated composite was used in Group 2. The adhesive remnant index (ARI) scores given by Artun and Bergland et al. and SBS were determined. Furthermore, the antimicrobial efficiency was estimated using the minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) and agar well diffusion assay for six composite disc specimens. The results were statistically analyzed using the chi-square test and Student's t test, at P < 0.05. After 24 h of curing, no statistical mean difference was observed between the two groups in terms of ARI or SBS scores (P > 0.05). However, there was a significant increase in the antimicrobial efficiency of Group II when compared with Group I (P < 0.05). TiO2 nanoparticle-incorporated orthodontic composites improve the antimicrobial efficiency with no significant change in the SBS. The ARI scores indicate the presence of 50% remnant orthodontic composite on the tooth enamel surface post debonding.

Defluoridation of drinking water by using low cost point of use treatment technologies: A review

Fluoride is an anionic pollutant found in surface or ground water in large quantities due to various human activities, for examples, disposal of industrial wastewater or geochemical reactions. The presence of fluoride in drinking water above certain limits has intense effects on human health. It strengthens the tooth enamel to a small level (1.0-1.5 mg/L). In drinking water, the presence of fluoride in the range of 1.5 to 4.0 mg/L may give rise to dental fluorosis at initial the stage, while the continuous exposure to high fluoride concentrations (4.0-10.0 mg/L) leads to skeletal fluorosis. In many countries of the world, including Pakistan, fluoride exists in ground water in high concentration, reaching above 30.0 mg/L on a large scale. The objective of writing this article is to offer accurate information on the efforts of a number of scholars who worked on fluoride removal from drinking water. The fluoride removal techniques have been categorized into two parts dealing with coagulation/precipitation and adsorption. Lime and alum (Nalgonda technique) and chitin have been discussed under coagulation technologies, while adsorption deals with a number of adsorbents, i.e., activated carbon, activated alumina, saw dust, bone char, rice husk ash, bauxite, tea-ash, and kaolin. Each technique discussed can remove fluoride under certain conditions. Each treatment technology has its limitations, and since there is no technology that can achieve its purpose in diverse conditions, the choice of fluoride removal techniques should be according to a specific site, depending on fundamental conditions and the needs of the local area.

A novel FAM83G variant from palmoplantar keratoderma patient disrupts WNT signalling via loss of FAM83G-CK1α interaction.

Palmoplantar keratoderma (PPK) is a multi-faceted skin disorder characterized by the thickening of the epidermis and abrasions on the palms and soles of the feet. Among the genetic causes, biallelic pathogenic variants in the FAM83G gene have been associated with PPK in dogs and humans. Here, a novel homozygous variant (c.794G>C, p.Arg265Pro) in the FAM83G gene, identified by whole exome sequencing in a 60-year-old female patient with PPK, is reported. The patient exhibited alterations in the skin of both hands and feet, dystrophic nails, thin, curly and sparse hair, long upper eyelid eyelashes, and poor dental enamel. FAM83G activates WNT signalling through association with ser/thr protein kinase CK1α. When expressed in FAM83G-/- DLD1 colorectal cancer cells, the FAM83GR265P variant displayed poor stability, a loss of interaction with CK1α and attenuated WNT signalling response. These defects persisted in skin fibroblast cells derived from the patient. Our findings imply that the loss of FAM83G-CK1α interaction and subsequent attenuation of WNT signalling underlie the pathogenesis of PPK caused by the FAM83GR265P variant.

Differnts Effectiveness of 10,600 nm Carbon Dioxide Laser on Enamel Surface

Besides having a modest penetration depth, a carbon dioxide laser operating at 10,600 nm has a strong absorption affinity for water. It's useful for coagulation of bleeding and soft-tissue surgery. Also, its absorption properties are consistent with hydroxyapatite, a mineral found in tooth enamel and dentin. This article examines the current research on the impacts of 10,600 nm Carbon Dioxide Laser on enamel surfaces. When compiling this review's data, we restricted our attention to articles that were made available online. For this study, we utilized the following search terms on "Google Scholar" and "PubMed" websites: CO2 Laser (10,600 nm), Demineralized enamel, Microhardness, enamel erosion, remineralization, fluoride. Only publications written in English from 2005 through June 2023 were included in this review. Priority was given to original articles and clinical research. Conclusion: The 10,600 nm CO2 laser is widely accepted in caries prevention. CO2 lasers have been the subject of much research but have yet to be used in therapeutic settings. Effective laser energy transmission to enamel allows for the transformation of carbonated hydroxyapatite into the purer hydroxyapatite of enamel. The laser enhances fluorides and other caries-preventive ingredients' effectiveness. As a result, resin bonds better to tooth enamel.

일부 비알코올 맥주의 우식활성능 비교

The growing popularity of non-alcoholic beer in society demands an investigation of their potential impact on oral health. This study compared the dental caries activity of commercially available non-alcoholic beer with that of their alcoholic counterparts, focusing on factors that influence demineralization. We measured the pH and buffering capacity of both beer types since they directly affect tooth enamel erosion. Streptococcus mutans was cultured on agar media containing the experimental beverages to assess biofilm formation. The results indicated that the pH of all non-alcoholic beer were below the critical level (5.5) for enamel demineralization. Furthermore, their buffering capacities were significantly lower than those of their alcoholic counterparts. Biofilm formation by S. mutans was higher in non-alcoholic beer (P&lt;0.001). These findings highlight the potential risk of dental cariesassociated with specific non-alcoholic beer, emphasizing the need for a broader assessment across various non-alcoholic beer types, considering the factors influencing dental caries and real oral conditions. Further research is warranted to comprehensively understand their impact on dental health.

Testing the Sample Preparation Method and Oxygen Isotopic Analysis of Tooth Enamel for the Reconstruction of the Birth Seasonality of Ovicaprines (the Case of Teeth from Istykskaya Cave, Eastern Pamir)

Cyclic variations of δ18O along the growth line of M2 and M3 molars provide information about the seasonality of enamel formation and thereby about reproductive seasonality in animals, taking into account the time of tooth eruption and full enamel maturation. Determination of birth seasonality of small ruminants is relevant to the reconstruction of pastoralist strategies. Two peaks of reproductive activity per year are one of the most reliable indicators of human control of the small ruminants. As part of this work, for the first time in Russia, a method of sample preparation and analysis of oxygen isotope ratios in the tooth enamel of small ruminants is proposed. Traditionally, breeding seasonality was evaluated by the isotopic analysis of carbonates, the content of which in dental enamel is only 4 %. According to a new approach, oxygen from a sample is converted to gaseous CO by the interaction of enamel with carbon in a helium flow under 1300 °С, enabling one to measure δ18O in all components of the dental enamel, including phosphates, which make up 90 % of enamel mass and are resistant to diagenesis. In this study, four sample preparation protocols depending on the degree of preservation of teeth and their age were tested: (A) cleaning and sampling of enamel, (B) treatment by H2O2, (C) treatment by NaOCl and CH3COOH, and (D) extraction of Ag3PO4. Results show that for assessing seasonality breeding, it suffices to evaluate the lowest and the highest δ18O along the tooth growth line. If the preservation of sample is good, minimal chemical treatment is enough to observe these extremes.

Development and effect of orodispersible film incorporated with Biosilicate for remineralization of dental enamel subjected to cariogenic and erosive challenge.

The objective of this in vitro study was to assess the efficiency of incorporating Biosilicate particles (30 and 50 mg) into an experimental orodispersible film and its efficacy in the remineralization process of bovine dental enamel under cariogenic and erosive challenges. Ninety-nine intact incisors, devoid of cracks or fractures, yielding 198 samples (6 × 6 × 2 mm) via vestibular sectioning using a low-speed diamond disc under water cooling. After flattening the enamel surface with 600, 1200, and 2000 grit sandpaper, the samples were divided into two groups based on the challenges they underwent: cariogenic (0.1 M lactic acid at pH 5.0) or erosive (0.05 M citric acid solution at pH 2.3). Samples from each challenge were further categorized into 11 groups (n = 9) according to the duration of cariogenic (3, 7, and 14 days) or erosive (3, 7, and 10 days) challenge, along with positive control groups (fragments untreated with challenges and treated with different Biosilicate concentrations) and negative controls (fragments treated with artificial saliva for the same periods established for cariogenic and erosive challenges). Treatments with orodispersible films containing Biosilicate (30 and 50 mg) were administered for 2 min per day for 15 days. The highest remineralizing potential was observed in samples treated with Biosilicate after 14 days of cariogenic challenge, irrespective of the concentration tested. For samples subjected to erosive challenge, erosion time did not affect Biosilicate's remineralizing potential. Biosilicate shows promise in terms of remineralizing potential in enamel subjected to cariogenic challenge due to its ability to form hydroxycarbonapatite in mineralized tissues.

EFFICACY OF OPTIMIZED REMINERALIZING THERAPY IN POST-COVID-19 PATIENTS: EVALUATION OF RESULTS

Data from Ukrainian researchers confirm that the prevalence of dental caries, even among young people, remains too high, reaching 95-98%. Fortunately, dental caries is reversible in the early stages of the disease, and it is possible to slow down the demineralization of enamel and dentin by inhibiting the formation of biofilm and the action of protective factors of saliva. The most interesting macronutrients that attracted our attention during the study were calcium and phosphorus, which play a key role in the mineralizing function of saliva and are the main structural elements of enamel hydroxyapatites. The results of our study indicate that the enamel mineralization processes are disturbed in patients with COVID-19. To correct the identified disorders and prevent the occurrence and development of carious lesions, we applied an improved algorithm of prophylaxis of dental enamel diseases using remineralizing therapy. Objective: to evaluate the effectiveness of the optimized method of remineralization by studying the dynamics of dental parameters in patients after 6 and 12 months. Materials and methods. To achieve this goal, 84 patients were monitored and divided into two equivalent groups: the main group, which included 42 patients who used our proposed preventive method, and the comparison group, which also consisted of 42 patients who were prescribed conventional preventive measures. Research results and discussion. The results obtained after one year of observation of patients with COVID-19 showed significant effectiveness of our proposed method. The increase in caries intensity in the main group after 6 months was 0.39±0.06, and after 12 months 0.44±0.06, while the corresponding index of the comparison group was higher both after 6 months (0.58±0.07) and after 12 months (0.78±0.05). Decrease in caries intensity allowed to establish a significant improvement in oral health in patients in all subgroups. The most significant values were observed after 12 months (66.67%, 37.18%, 28.21% for each subgroup, respectively). The study of oral hygiene using the OHI-S index showed the following results: after 12 months, the patients of the first and second subgroups had corresponding values of 0.67±0.05 and 0.69±0.06, which, according to the interpretation, referred to good hygiene; the patients of the third subgroup were distinguished by the transition to satisfactory hygiene (1.17±0.09) from the initial data of unsatisfactory hygiene (2.46±0.08). Evaluation of enamel resistance according to the TER test revealed a significant migration of indicators towards high and medium resistance: it should be noted that enamel caries resistance in patients with a history of severe form underwent significant changes and decreased to 6.48±0.24 points (from baseline 8.63±0.38), while in patients diagnosed with mild to moderate severity was 2.52±0.19 points (from baseline 4.15±0.22) and 4.68±0.25 (from baseline 6.29±0.31). Conclusions. The results of the analysis of patients' examination during one year of Tooth Mousse gel application for the prevention of dental caries with the use of individual mouth guards confirm the effectiveness of the conducted measures among patients with COVID-19 of different severity.

Posteruptive Loss of Enamel Proteins Concurs with Gain in Enamel Hardness.

Tooth enamel maturation requires the removal of proteins from the mineralizing enamel matrix to allow for crystallite growth until full hardness is reached to meet the mechanical needs of mastication. While this process takes up to several years in humans before the tooth erupts, it is greatly accelerated in in the faster developing pig. As a result, pig teeth erupt with softer, protein-rich enamel that is similar to hypomineralized human enamel but continues to harden quickly after eruption.Proteins, such as albumin, that bind to enamel crystals and prevent crystal growth and enamel hardening have been suggested as cause for hypomineralized human enamel that does not naturally harden after eruption. However, albumin is abundant in pig enamel. It is unclear whether fast posteruptive enamel hardening in pigs occurs despite the high protein content or requires a facilitated protein loss to allow for crystal growth. This study asked how the protein content in porcine enamel changes after eruption in relation to saliva. Based on previous data demonstrating the high albumin content in erupted porcine enamel, we hypothesize that following pre-eruptive maturation, enamel and saliva derived enzymes facilitate protein removal from porcine enamel after eruption. We analyzed enamel and the saliva proteome at three critical timepoints: at the time of tooth eruption, 2 weeks after eruption, and enamel 6 weeks after eruption. We used only fourth deciduous premolars and saliva samples from animals sacrificed at the respective time points to determine the organic content in tooth enamel, saliva, and saliva proteins within enamel. We found a decrease in the number of proteins and their abundancy in enamel with posteruptive time, including a decrease in serum albumin within enamel. The rapid decrease in the first two weeks is in line with previously reported rapid increase in mineral density of porcine enamel after eruption. In addition to the enamel proteases KLK-4 and MMP-20, we identified serine-, cysteine-, aspartic-, and metalloproteases. Some of these were only identified in enamel, while almost half of the enzymes are in common with saliva at all timepoints. Our findings suggest that the fast posteruptive enamel maturation in the porcine model coincides with saliva exchange and influx of saliva enzymes into porous enamel.

Shear Bond Strength of Orthodontic Brackets Bonded with Thermo-Cured Glass-Based Materials-An In Vitro Study.

The results of orthodontic therapy largely depend, among other factors, on the preparation of the tooth enamel itself and the choice of material used to bond orthodontic brackets. The aim of this in vitro study was to determine the shear bond strength (SBS) and adhesive remnant index (ARI) score of thermo-cured glass-ionomers on different pretreated enamel, in comparison with the commonly used composite cement. Three commercially available nano-ionomer or highly viscous glass-ionomer cements (EQUIA Forte® Fil, EQUIA Fil, Ketac Universal) and two types of compo-sites (Heliosit Orthodontic, ConTec Go!) were investigated in this study. The research involved two hundred human premolars. The teeth were cleaned and polished, then randomly divided into five groups according to the enamel preparation method and the type of material. The enamel was treated in three different ways: polyacrylic acid, phosphoric acid, 5% NaOCl + etching with phosphoric acid, and a control group without treatment. Glass-ionomer cement was thermo-cured with heat from a polymerization unit during setting. Statistical analysis was performed using a Chi-square test and one-way ANOVA for independent samples. Spearman's Rho correlation coefficient was used to examine the relationship. Regardless of the material type, the results indicated that the weakest bond between the bracket and tooth enamel was found in samples without enamel pretreatment. The majority of the materials stayed on the brackets in samples without enamel preparation, according to ARI scores. The study's findings demonstrated that the strength of the adhesion between the bracket and enamel is greatly influenced by enamel etching and glass-ionomer thermo-curing. Clinical investigations would be required to validate the outcomes.

Rebonding of orthodontic metallic brackets: Comparative analysis of shear bond strength using different sandblasting particles

IntroductionThis study aimed to evaluate the effect of two different sandblasting particles on the shear bond strength of rebonded metallic brackets to dental enamel. MethodsForty-eight metallic orthodontic brackets were divided into 4 experimental groups (n = 12) according to the surface treatment they received at their bases: positive control group (Metal), negative control group (MetalU), sandblasted with Rocatec Soft (MetalRoc) and sandblasted with Glass beads (MetalGlas). An elementary and topographic analysis of the base of the brackets was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after the surface treatment. The brackets rebonded to dental enamel were tested for their shear bond strength. The obtained data were subjected to statistical analysis one-way ANOVA and Tukey's test (α = 0.05). The fracture surfaces of the specimens after the mechanical test were analyzed using optical microscopy to classify the failure mode. ResultsSEM photomicrographs for the MetalRoc and MetalGlas groups showed efficient removal of the remaining resin composite. In both sandblasting treatments, the presence of silicon (Si) and oxygen (O) at the base of the brackets were verified by means of the EDS, suggesting the occurrence of silica coating. MetalGlas group showed greater bond strength (9.38 ± 2.78 MPa) compared to the MetalU group (5.31 ± 1.2Mpa). Metal (8.82 ± 4.14 MPa) and MetalRoc (8.29 ± 3.95 MPa) groups showed similar bond strengths. The failure mode predominantly found in the sandblasted groups was the totally adhesive failure between resin composite and tooth. SignificanceThe sandblasting treatment using the glass beads was efficient in removing the remaining resin composite of recycled brackets and generated fewer surface defects and topographic changes in the bracket bases.

Examining enamel-surface demineralization upon exposure to acidic solutions and the remineralization potential of milk and artificial saliva.

The enamel surface may undergo demineralization due to exposure to acidic substances and the remineralization of the etched enamel is crucial to regain or maintain integrity. This study aimed to investigate the erosive effect of 10 acidic solutions on tooth enamel and the remineralization capacity of milk and artificial saliva by measuring surface roughness (Ra), enamel depth, and microhardness. A total of 80 bovine incisor enamel specimens were immersed in 10 different acidic solutions, including four different acidic drinks, three different citric acid solutions, and three different citric acid buffer solutions, for 1h. After demineralization, the specimens were immersed in milk and artificial saliva for 3h. Surface roughness, enamel abraded depth, and microhardness were measured before demineralization, in-between time intervals and after remineralization. Data were analyzed using Friedman and Kruskal-Wallis tests (p < 0.05). The results indicate a significant difference in surface roughness between the measurements taken at different time intervals, particularly between the baseline and after 1h demineralization. Also, the specimens immersed in CAB1 exhibited greatest increase in Ra among other acidic solutions (Δ: 0.18 ± 0.07). Moreover, only the microhardness increased after remineralization (p < 0.05). Enamel demineralization using various acidic solutions revealed increased Ra and enamel abraded depth, and decreased microhardness. The use of remineralization agents, milk and artificial saliva, demonstrated an increase in microhardness. This study provides insights into the effects of different acidic solutions and potential remineralization agents on tooth enamel.

Evaluation of Ilex guayusa and Piper marginatum Extract Cytotoxicity on Human Dental Pulp Mesenchymal Stem Cells.

Amelogenesis imperfecta is a hereditary disorder affecting dental enamel. Among its phenotypes, hypocalcified AI is characterized by mineral deficiency, leading to tissue wear and, consequently, dental sensitivity. Excessive fluoride intake (through drinking water, fluoride supplements, toothpaste, or by ingesting products such as pesticides or insecticides) can lead to a condition known as dental fluorosis, which manifests as stains and teeth discoloration affecting their structure. Our recent studies have shown that extracts from Colombian native plants, Ilex guayusa and Piper marginatum, deposit mineral ions such as phosphate and orthophosphate into the dental enamel structure; however, it is unknown whether these extracts produce toxic effects on the dental pulp. To assess cytotoxicity effects on human dental pulp stem cells (hDPSCs) exposed to extracts isolated from I. guayusa and P. marginatum and, hence, their safety for clinical use. Raman spectroscopy, fluorescence microscopy, and flow cytometry techniques were employed. For Raman spectroscopy, hDPSCs were seeded onto nanobiochips designed to provide surface-enhanced Raman spectroscopy (SERS effect), which enhances their Raman signal by several orders of magnitude. After eight days in culture, I. guayusa and P. marginatum extracts at different concentrations (10, 50, and 100 ppm) were added. Raman measurements were performed at 0, 12, and 24 h following extract application. Fluorescence microscopy was conducted using an OLIMPUS fv1000 microscope, a live-dead assay was performed using a kit employing a BD FACS Canto TM II flow cytometer, and data analysis was determined using a FlowJo program. The Raman spectroscopy results showed spectra consistent with viable cells. These findings were corroborated using fluorescence microscopy and flow cytometry techniques, confirming high cellular viability. The analyzed extracts exhibited low cytotoxicity, suggesting that they could be safely applied on enamel for remineralization purposes. The use of nanobiochips for SERS effect improved the cell viability assessment.