The effect of a bioglass paste on enamel exposed to erosive challenge

Protecting primary teeth from dental erosion through bioactive glass

OBJECTIVES

The present study aimed to evaluate the effectiveness of bioactive glass (BAG) in preventing dental erosion in primary teeth.

METHODS

Enamel and dentin specimens (2 × 2 × 2 mm) were obtained from extracted primary teeth, which were randomly divided into the following groups based on the pretreatments (n = 12): DW (deionized water), NaF (2 % sodium fluoride), 2BAG (2 % BAG), 4BAG (4 % BAG), 6BAG (6 % BAG), and 8BAG (8 % BAG). The specimens were immersed in the respective solutions for 2 min and subjected to in vitro erosive challenges (4 × 5 min/d) for 5 d. The erosive enamel loss (EEL), erosive dentin loss (EDL), and the thickness of the demineralized organic matrix (DOM) were measured using a contact profilometer. The surface microhardness (SMH) was measured, and the percentage of SMH loss (%SMHL) was calculated. The surface morphology and mineral composition were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively.

RESULTS

After the erosive challenges, the EEL, EDL, and%SMHL of the 2BAG, 4BAG, 6BAG, and 8BAG groups significantly reduced, with the greatest reduction was observed in the 6BAG (EEL: 6.5 ± 0.2 μm;%SMHL in enamel: 12.8 ± 2.6; EDL: 7.9 ± 0.3 μm; %SMHL in dentin: 22.1 ± 2.7) and 8BAG groups (EEL: 6.4 ± 0.4 μm;%SMHL in enamel: 11.0 ± 1.9; EDL: 7.8 ± 0.5 μm; %SMHL in dentin: 22.0 ± 2.5) (P < 0.05). With increasing BAG concentrations, the number of surface deposits containing Ca, P, and Si increased.

CONCLUSIONS

6BAG was the most effective for preventing dental erosion in primary teeth and showed a particularly strong potential for dentin erosion prevention.

CLINICAL SIGNIFICANCE

Bioactive glass, especially at a 6 % concentration, has proven effective in reducing erosive tooth wear and surface microhardness loss while also protecting demineralized organic matrix in primary dentin.

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 1 h. After demineralization, the specimens were immersed in milk and artificial saliva for 3 h. 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 1 h 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.

Effect of air-abrasion pretreatment with three desensitizing agents on efficacy of in-office tooth bleaching

OBJECTIVE

To evaluate the influence of air-abrasion of enamel with three different desensitizing powders on the whitening effect of a bleaching gel containing 40% H2O2, which was used for in-office tooth bleaching.

MATERIALS AND METHODS

Forty human incisors, extracted and prepared, were acquired for this study and subsequently randomized into four groups (n = 10). The control group specimens underwent no pretreatment prior to the bleaching procedure, whereas the remaining three groups underwent air abrasion using distinct desensitizing powders; (a) Sylc, which contains bioglass 45S5; (b) BioMinF, which contains calcium phospho-fluoro-silicate glass; and (c) MI Pearls, which contains nano-hydroxyapatite, 1 h preceding the Opalescence Boost PF 40% bleaching procedure. Color measurements were conducted using a double-beam UV-Vis spectrophotometer at four distinct time points (prior to bleaching, 24 h, 15 days, and 30 days post-bleaching).

RESULTS

Tooth color change outcomes revealed that there were no statistically significant results with respect to the interaction of the two criteria (treatments and time) (p = 0.990). Additionally, there were no statistically significant results with respect to the main effects of treatments (p = 0.385), while there were statistically significant effects with respect to the time criterion (p = 0.013).

CONCLUSIONS

The use of the tested desensitizing powders prior the bleaching procedure did not affect the tooth color change induced by the tested bleaching agent.

CLINICAL SIGNIFICANCE

Tooth color change and whiteness are not affected by air-abrasion desensitizing treatments when applied prior to in-office bleaching procedures.

Comparative evaluation of remineralization potential of novel bioactive agents on eroded enamel lesions: A single-blinded in vitro study

Objective

The escalating prevalence of noncarious tooth wear stands as a critical concern in the backdrop of evolving lifestyles and dietary patterns. Dental erosion, a progressive condition induced by both endogenous and exogenous acidic influences, directly impacts enamel integrity, resulting in surface loss. The contemporary surge in carbonated beverage consumption further exacerbates this erosive milieu, underscoring the urgency for dental practitioners to adopt meticulous treatment strategies. Existing literature underscores a noteworthy 94% reduction in tooth erosion risk for individuals abstaining from sweetened soft beverages, emphasizing the imperative for a well-devised remineralization protocol to counter demineralized surfaces.

Methodology

Seventy-three enamel specimens were taken. Forty samples were subjected to pre-operative hardness testing, and five samples were subjected to baseline EDX evaluation followed by grouping of samples (Group 1 = control Group; Group 2 = casein phosphopeptide-amorphous calcium phosphate fluoride [CPP-ACPF] Group; Group 3 = Biomin F Group; and Group 4 = self-assembling peptide [SAP] P-114 Group). A demineralization-remineralization cycle was carried out for 5 days followed by testing through Vickers Microhardness Tester, EDX Evaluation, and Scanning Electron Microscopy (SEM) Imaging. Statistical analysis was performed using one-way analysis of variance followed by intergroup analysis using Tukey's post hoc test with SPSS software 25.0 version.

Results

The mean percentage change in microhardness values was 30.05% in Group 1, 24.21% in Group 2, 18.85% in Group 3, and 12.08% in Group 4. The mean Ca/P ratio of samples tested through EDAX was 2.20 at baseline, 1.40 in Group 1 (Control Group), 1.62 in Group 2 (CPP-ACPF), 1.82 in Group 3 (Biomin F), and 2.01 in Group 4 (SAP-P114). Postintervention values were statistically significant from baseline values in both parameters.

Conclusion

Curodont Protect exhibits superior efficacy, offering valuable insights for future in vivo studies and clinical applications. The multifaceted evaluation, encompassing microhardness testing, SEM analysis, and EDXS assessment, contributes to a nuanced interpretation of the agents' impact, paving the way for informed decisions in clinical practice and future research endeavors.

Ultrastructural investigation of the effect of toothpastes containing different remineralizing agents on demineralized enamel

OBJECTIVE

The present study aimed to evaluate the effect of remineralizing agents on demineralized enamel intended for use as fluoride substitutes or supplements for oral hygiene applications.

METHODOLOGY

Enamel samples were obtained from 30 bovine teeth. The enamel blocks were stored in 20 mL of demineralization solution for 72 h. They were then brushed with the following toothpaste for the remineralization protocol: NaF, NaF/SnF2 combination, NovaMin, or nano-hydroxyapatite. SEM/EDX examinations and microhardness measurements of the samples were performed to investigate the remineralization efficacy of the studied toothpaste. One-way analysis of variance (ANOVA) with post hoc Tukey's HSD test was used to analyze the change in microhardness values in different remineralization protocols (p < 0.05).

RESULTS

Differences in the mean remineralization (%RP) and hardness recovery (%HR) were determined between the groups (p < 0.05). Groups 1 and 4 showed significant differences in %RP (p < 0.05). In the SEM/EDX examinations, the samples treated with n-HAp showed an accumulation of crystal deposits on the enamel surface, although at a lower density than those treated with NaF and NaF/SnF2 combination.

CONCLUSION

The remineralization strategy in toothpaste plays an important role in enamel remineralization. NovaMin-containing toothpaste showed positive effects on the enamel surface with better Ca/P ratio. Toothpastes containing n-HAp triggered less change in the increase of microhardness values compared to other toothpastes. The use of SnF2 in toothpaste in combination with NaF significantly increased the binding of fluoride to demineralized enamel compared to toothpaste containing NaF alone.

Comparative Evaluation on the Effect of Different Remineralizing Agents on Enamel-Bracket Shear Bond Strength: An In Vitro Study

AIM

 This study aimed to compare the effects of applying various remineralizing agents before and after acid etching on the enamel-bracket shear bond strength (SBS) in vitro. These agents included silver diamine fluoride (SDF), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and 5% sodium fluoride (5% NaF).

MATERIALS AND METHODS

All the selected teeth were divided equally into six subgroups depending on before and after acid etching and one separate control group for the in vitro study design. Eighty-four extracted premolar teeth (12 teeth in each group x seven groups, including the control group). Before acid etching, teeth in groups A1, B1, and C1 were given SDF, CPP-ACP paste, and 5% NaF, respectively. Following acid etching, all of the teeth in Groups A2, B2, and C2 received the same preventative treatments. After that, the SBS of the bonded brackets to the enamel was evaluated.

RESULTS

The CPP-ACP group, control group, and SDF group had the highest values for SBS prior to acid etching.The 5% NaF group had the weakest bonds, and the difference between the groups was statistically significant. The CPP-ACP group had the highest SBS following acid etching, followed by the 5% NaF group. The least bond strength was seen in the SDF group, and the difference between the three groups was significant.

CONCLUSION

When it comes to bonding orthodontic brackets, the CPP-ACP pretreatment is superior to fluoride pretreatment in terms of effectiveness. The use of these remineralizing agents resulted in favorable values that did not have any effect on the SBS and were therefore safe to use with orthodontic brackets.

Efficiency of Various Tubular Occlusion Agents in Human Dentin after In-Office Tooth Bleaching

The aim of this laboratory study was to investigate and compare the impact of five desensitizing techniques as a treatment fortooth sensitivity on the exposed dentin after an in-office tooth bleaching procedure. Thirty intact human molars were collected for this investigation. The specimens were obtained by transversely cutting 2.5 mm of the crowns, leading to exposure of the dentin. The specimens were cleaned in an ultrasonic bath and treated initially with EDTA gel 15% for 4 min and then with Opalescence Boost bleaching gel (40% H2O2) for two sets of 20 min. Then, the samples were randomly divided into six groups (n = 5) and received one of the following treatments: Group 1 (no treatment-control group), Group 2 (Emofluor gel-0.4% SnF2), Group 3 (MI Paste-CPP-ACPF), Group 4 (BioMinF paste-calcium phospho-fluoro-silicate), Group 5 (air-abrasion with ProSylc-Bioglass 45S5), and Group 6 (Er,Cr:YSGG laser). Subsequently, each sample was observed utilizing scanning electron microscopy (SEM) in order to detect the rate of occlusion of dentin tubules. SEM-EDS analysis revealed no occlusion of the dentin tubules in the control group, while Groups 2, 4, and 5 presented high effectiveness (>95% percentage of occluded tubules), and Groups 3 and 6 presented lower values (21.6 and 26.8%, respectively). It was concluded that althoughall the tested groups presented higher percentages of occlusion of the dentinal tubules compared to the control group, there were differences in effectiveness among them. The most effective treatments were the daily use of BioMinF paste and SnF2-containing gel, as well as air-abrasion with ProSylc powder.

Comparative analysis of the effect of Bioactive Glass 45S5 on enamel erosion progression in human dentitions (in vitro study)

OBJECTIVES

The aim of the present study was to compare the surface morphology alterations, mineral content, and surface roughness of eroded enamel surface versus eroded enamel surface which was preceded by Bioactive Glass 45S5 (BAG45S5) application in both primary and permanent human dentitions.

MATERIALS AND METHODS

Fifty-two primary teeth and fifty-two permanent teeth were selected. Teeth were randomly divided into 4 groups of twenty-six teeth each. Groups A1 and B1 underwent erosion with 1% citric acid, while groups A2 and B2 were subjected to application of BAG45S5 powder followed by the same erosive conditions as A1 and B1. Measurements were performed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and surface profilometry. They were used to examine the surface morphology alterations, mineral content, and surface roughness, respectively.

RESULTS

SEM of enamel which received BAG45S5 showed smoother surface in primary teeth post erosion. EDX analysis showed that enamel exhibited crucial resistance to mineral loss in the group which received BAG45S5 prior to inducing erosion as compared to the induced erosion-only group. This was significant (p < 0.005) in both human dentitions. Erosion-only groups showed significantly less surface roughness in permanent teeth (p < 0.045). A marked decrease in surface roughness was observed in surfaces receiving BAG45S5, primary teeth (p < 0.001), and permanent teeth (p < 0.001).

CONCLUSIONS

Bioactive Glass 45S5 proved successful against erosive conditions in both primary and permanent teeth with better performance in the permanent teeth so it can be regarded as a means of prevention.

CLINICAL RELEVANCE

Bioactive Glass 45S5 powder could be used not only to remove stains but also as a prophylactic preventive measure against the multiple episodes of acidic food and beverage consumption in children.

Development and Characterization of Novel Orthodontic Adhesive Containing PCL-Gelatin-AgNPs Fibers

Enamel demineralization around brackets is a relatively common complication of fixed orthodontic treatment, which seriously affects the aesthetics of teeth. In this study, a novel orthodontic adhesive containing polycaprolactone−gelatin−silver nanoparticles (PCL−gelatin−AgNPs) composite fibers was prepared to prevent enamel demineralization of orthodontic treatment. First, PCL−gelatin−AgNPs fibers film prepared by electrospinning was made into short fibers and added to traditional orthodontic adhesives (Transbond XT, 3M Unitek) in three different ratios to design a series of composite adhesives containing antibacterial materials. The antimicrobial performance of the control product and the three samples were then evaluated by bacterial live/dead staining, colony-forming unit (CFU) counts, tensile bond strength (TBS), and adhesive residue index (ARI) scores. The composite adhesives’ antimicrobial properties increased with the increasing content of PCL−gelatin−AgNPs short fibers. The addition of complex antimicrobial fibers to 3M Transbond XT adhesive can significantly reduce the CFU of bacterial biofilms (p < 0.05). The bacterial survival rate on the surface of the specimen decreased with the increase of PCL−gelatin−AgNPs short fibers (p < 0.05). The TBS and ARI values (n = 10) indicated that adding PCL−gelatin−AgNPs short fibers had no significant adverse effect on adhesion. Therefore, adding PCL−gelatin−AgNPs short fibers makes it possible to fabricate orthodontic adhesives with strong antibacterial properties without compromising the bonding ability, which is essential for preventing enamel demineralization around the brackets.

EFFICACY OF NOVEL BIOACTIVE GLASS IN THE TREATMENT OF ENAMEL WHITE SPOT LESIONS: A RANDOMIZED CONTROLLED TRIAL✰

OBJECTIVES

to evaluate the efficacy of 2 types of bioactive glass (45S5) compared to casein-phosphopeptide stabilized-amorphous calcium phosphate (CPP-ACP) in the treatment of orthodontically-induced white spot lesions (WSLs).

METHODS

Sixty post-orthodontic WSLs (ICDAS II score 2) were randomly allocated to a double blind randomized controlled trial with 3 parallel arms (n = 20). Test group I (Bio-BAG) received BiominF slurry and toothpaste, and test group II (N-BAG) received Novamin slurry and toothpaste. While the positive control group (CPP-ACP) received Recaldent paste. Products were applied daily in-office during week 1, and boosted by self-administered home application for 4 weeks (week 1-4). Standard oral hygiene care was performed by all participants twice daily during months 2-6. All patients were assessed for change in WSL dimensions using computer assisted analysis based on standardized digital intraoral photographs in addition to laser fluorescence DIAGNOdent assessment before treatment (T0) and at 1 week (T1), 1 month (T2), 3 months (T3,) and 6 months (T4) follow up periods.

RESULTS

Kruskal Wallis test was used (P < .05 for all). At T4, a statistically significant (P < .001) regression of WSL was disclosed in all 3 groups compared to baseline, and a highly significant lesion size percent reduction in Bio-BAG group compared to the control group (P < .001). The mean area of the lesions decreased by 64.8%, 32.2%, and 31.6% for groups I, II and III respectively (P = .001). DIAGNOdent findings largely reflected the clinical scores (Mean scores at baseline/T4 for groups I, II, and III respectively; 16.57/3.62, 16.93/7.90, 21.95/19.27). No adverse effects were reported.

CONCLUSIONS

The combined in-office and home-application of BiominF paste for 4 weeks resulted in greater esthetic improvements of post-orthodontic WSLs compared to Novamin and CPP-ACP. In addition, BiominF showed a significant reduction in fluorescence intensity which indicates potential lesion remineralization.

CLINICAL RELEVANCE

Post-orthodontic WSLs can be diminished using bioactive glass remineralization therapy.

Synthesis and characterization of nano bioactive glass for improving enamel remineralization ability of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)

OBJECTIVE

Nanomaterials with superior properties such as high surface area over volume ratio are widely used in dentistry and medicine. This in vitro study was performed to synthesize and characterize nano bioactive glass (nBG) and to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) containing nBG (CPP-ACP@nBG) on enamel remineralization by its application to pH-cycled, synthetically demineralized enamel surfaces.

MATERIALS AND METHODS

nBG particles were prepared by sol-gel method. X-ray diffraction pattern (XRD), Fourier-transform infrared spectroscopy (FTIR) and transmittance electron microscopy (TEM) were used for nBG characterization. Synthetic CPP-ACP paste was prepared and nBG particles were added to it. To evaluate the degree of remineralization, 32 healthy human premolars were selected. The samples were randomly divided into 4 groups as: Group 1: Commercial CPP-ACFP (MI paste plus), Group 2: Synthetic casein phosphopeptide-amorphous calcium phosphate containing fluoride (CPP-ACP@F), Group 3: Synthetic CPP/ACP containing nBG (CPP-ACP@nBG), and Group 4: Control (received no treatment). The pastes were then applied on the tooth surfaces for 28 days. The Vickers microhardness of enamel surfaces was evaluated, and enamel surface morphology was assessed using scanning electron microscopy (SEM).

RESULTS

X-Ray diffraction pattern (XRD) of the synthesized nBG show its crystalline nature with the Larnite crystalline mode. Transmittance electron microscope (TEM) microimage of the synthesized nBG shows its formation as less that 100 nm spherical nanoparticle with partial agglomeration. Fourier transform infrared spectroscopy (FTIR) confirm the success formation of nBG with high purity. The results of this study showed that microhardness of the experimental groups was significantly higher than the control group (p ≥ 0.05). SEM images showed a layer of hydroxyapatite in the CPP-ACP@nBG, synthetic and commercial CPP-ACP@F remineralized groups.

CONCLUSION

The results of this study demonstrated that CPP-ACP@F and CPP-ACP@nBG remineralize the surface of the demineralized enamel. Microhardness of the remineralized enamel in the CPP-ACP@nBG group was higher than synthetic and commercial CPP-ACP@F groups.

Effect of citric acid erosion on enamel and dentin and possible protection by a novel bioactive borate adhesive system

OBJECTIVES

This study examined the ability of a borate adhesive to protect enamel/dentin surfaces from acidic erosion and its effect on the shear bond strength (SBS) of enamel/dentin to resin composite.

MATERIALS AND METHODS

180 human enamel/dentin specimens were utilized. Enamel buccal surfaces were etched with phosphoric-acid then divided into: (EBG) borate glass adhesive group; (ERS) resin-adhesive system group; (EF) fluoride gel 1.23% group, and enamel control (EC) group; followed by bonding to orthodontic-buttons. The dentin specimens were conditioned by EDTA (Ethylene-diamine-tetra-acetic acid) and divided into: (DBG) borate glass resin, (DRS) resin adhesive; (DDA) group had a dentin-desensitizing agent VivaSens (VivaDent, Liechtenstein) and (DC) control group. The treated enamel/dentin specimens had their SBS to composite. The enamel/dentin specimens were exposed to 1% citric acid (18 min). Enamel/dentin specimens were examined by (SEM/EDS) scanning-electron-microscope equipped with electron-dispersive-spectroscopy and (FTIR/ATR). Analysis-of-Variance (ANOVA) was used to compare the SBS and Wilcoxon-signed-rank test was used to compare the enamel/dentin areas protected by the applied agents before/after erosion (p = 0.05).

RESULTS

There was no significance difference in SBS among all groups except for (DDA) group that showed significant decrease p < 0.05. (EBG) and (DBG) groups were the only groups significantly protected enamel and dentin from erosion p < 0.05. FTIR/ATR showed that erosion altered the chemical structure of (DRS), (DDA), and (DC) groups but did not affect the other enamel/dentin groups. Degree of conversion of the borate-adhesive system was acceptable.

CONCLUSION

The Borate adhesive system released calcium and phosphate compounds that decreased the erosive activity of the citric acid resulting in protecting simulated dentin-hypersensitive areas and enamel from erosion without affecting the SBS to resin-composite.

CLINICAL SIGNIFICANCE

A Borate adhesive system can be adopted as a therapeutic agent in a fully integrated program for protecting dentin-hypersensitive areas and in enamel next to orthodontic fixed appliances.

Effect of air-abrasion pretreatment with three bioactive materials on enamel susceptibility to erosion by artificial gastric juice

OBJECTIVE

The purpose of the study was to investigate the protective effect of three in-office preventive treatments with bioactive materials against enamel erosion induced by artificial gastric juice similar to that found in gastroesophageal reflux disease (GERD) patients. The treatments included air-abrasion of enamel with a fluoride-containing bioactive glass (BioMinF®), Bioglass 45S5 (ProSylc) and nano-hydroxyapatite (MI Pearls) to test enamel susceptibility following an erosive challenge.

METHODS

Enamel surface loss was evaluated using confocal microscopy, while changes in enamel surface roughness and morphology were also investigated after the treatments. SEM and EDS were used to observe formation of apatite crystals on enamel and to detect alterations in mineral composition. In Group 1 (negative control) the specimens did not receive any treatment; Group 2 specimens (positive control) treated with 0.4 % SnF₂, while in Groups 3-5 enamel was air-abraded with BioMinF®, ProSylc and MI Pearls, respectively.

RESULTS

All the experimental groups reduced significantly enamel surface loss compared to the negative control group (p < 0.05), except for the MI Pearls treatment (p > 0.05). The most protective behavior against erosion presented the treatment with SnF₂. BioMinF induced the larger amount of apatite crystals on the enamel surface, followed by ProSylc.

SIGNIFICANCE

BioMinF and ProSylc treatments may be beneficial against dental erosion induced by gastric juice in GERD patients, while MI Pearls treatment may not suitable for this indication. Both materials promote formation of apatite crystals on enamel in acidic conditions protecting the surface from the erosion. The tested treatments may be useful in GERD patients who cannot comply with at-home therapies with SnF₂.

Experimental pastes containing niobophosphate and 45S5 bioactive glasses for treatment of dentin hypersensitivity: dentin permeability and tubule obliteration

OBJECTIVES

This study tested the ability of bioactive pastes containing niobophosphate and 45S5 glasses to reduce dentin permeability and to obliterate dentinal tubules, as a mean of reducing human dentin hypersensitivity.

MATERIALS AND METHODS

Experimental pastes with concentrations of 10, 20, and 30 wt% of two bioactive glasses (45S5 or niobophosphate [NbG]) were formulated. A paste without bioactive glass (placebo) and a commercial paste (Nano P, FGM) were used as controls. Forty dentin disc specimens were obtained from caries-free extracted third human molars and divided in 8 groups (n = 5). Percentage of permeability (%Lp) was assessed in a dental permeability machine considering hydraulic conductance, immediately after pastes application and at day 7, day 14, and day 21. The precipitates formed on the surface of the dentin discs (and dentinal tubules) were analyzed by SEM/EDS and micro-Raman spectra. Data of dentin permeability (%) 2-way repeated-measures (ANOVA) and Holm-Sidak post-tests (α = 0.05). Dentinal tubule obliteration was visually (and elemental) evaluated and descriptively reported.

RESULTS

The experimental bioactive glass pastes containing NbG and 45S5, regardless of the concentration, reduced dentin permeability in comparison with pastes without bioactive glasses (P < 0.05). The formulated placebo and commercial paste did not reduce permeability over time (P < 0.05). SEM/EDS and micro-Raman analyses showed that both type of bioactive pastes (NbG or 45S5-based) presented mineral precipitates obliterating the dentinal tubules at day 21. NbG seems to offer a better initial effect than 45S5, while at 21 days there is no difference between both glasses.

CONCLUSION

Experimental bioactive pastes containing NbG and 45S5 (at concentrations of 10%, 20%, or 30%) have potential to reduce dentin permeability (over time) in comparison with pastes without bioactive glasses; and this occurs on behalf of obliteration of dentinal tubules by microparticle and precipitate formation.

CLINICAL RELEVANCE

Bioactive pastes containing NbG and 45S5 may benefit patients presenting dentin hypersensitivity, because these pastes can start acting fast after application and maintain their action up to 21 days.

Effects of incorporating 45S5 bioactive glass into 30% hydrogen peroxide solution on whitening efficacy and enamel surface properties

OBJECTIVES

This study aimed to evaluate the effects of 30% hydrogen peroxide (HP) solution containing various contents of 45S5 bioactive glass (BAG) on whitening efficacy and enamel surface properties after simulating the clinical bleaching procedure.

MATERIALS AND METHODS

A total of 60 bovine enamel specimens discolored with black tea were divided into five groups treated with distilled water (DW), HP, 0.01 wt.% BAG + HP, 1.0 wt.% BAG + HP, and 20.0 wt.% BAG + HP (n = 12). The pH change was observed for 20 min immediately after mixing the experimental solutions, which were applied for 20 min/week, at 37 °C over 21 days. Color, gloss, roughness, microhardness, and micromorphology measurements were conducted before and after bleaching treatment.

RESULTS

All groups containing BAG experienced an increase in pH from 3.5 to 5.5 in less than 1 min, and the final pH increased as the BAG content increased. The ΔE of all experimental groups was significantly higher than that of the DW group (p < 0.05), but there were no significant differences between different BAG contents (p > 0.05). Gloss significantly decreased in all experimental groups compared to the DW group, and the increased BAG content had significantly affected the decrease in gloss (p < 0.05). There was no statistical difference in surface roughness (p > 0.05), but hardness increased significantly with BAG content after bleaching treatment (p < 0.05).

CONCLUSIONS

HP containing 45S5 BAG showed efficacy in tooth whitening. Also, the pH value of the HP remained acidic near 3.5 for 20 min, while the HP containing the 45S5 BAG showed an increase in pH, which inhibited the demineralization of the enamel surface, and maintained the surface morphology.

CLINICAL RELEVANCE

These novel materials are promising candidates to minimize enamel surface damage caused by HP during bleaching procedure in dental clinic.

Efficacy of a Novel Bioactive Glass-Polymer Composite for Enamel Remineralization following Erosive Challenge

Introduction

Dental caries is the most common cause of tooth loss. However, it can be stopped by enhancing remineralization. Fluoride and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) are among the most important remineralizing agents. Recent studies have used bioactive glass as a remineralizing agent in different forms. This study aimed to assess the efficacy of a composite paste (prepared by mixing urethane polypropylene glycol oligomer with bioactive glass powder for easier application).

Materials and Methods

Enamel disks were cut out of the buccal surface of extracted sound third molars. The samples were randomly divided into 3 groups of 15 and underwent Vickers microhardness test. X-ray diffraction (XRD) and field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FESEM/EDS) were performed. All samples were immersed in a demineralizing solution for 14 days. The tests were then repeated. Next, bioactive glass paste, fluoride, and CPP-ACP were applied on the surface of the samples and they were then stored in an artificial saliva for 14 days. The tests were repeated again. The microhardness values were analyzed using repeated measures ANOVA followed by one-way ANOVA and Tukey's post hoc test (P < 0.05).

Results

The microhardness of the bioactive glass group was significantly higher than that of other groups (P < 0.05). XRD revealed an enamel structure more similar to sound enamel in the bioactive glass and CPP-ACP groups compared with the fluoride group. FESEM/EDS revealed higher hydroxyapatite deposition in the bioactive glass group than in the other two groups.

Conclusions

All three remineralizing agents caused remineralization, but bioactive glass paste had a greater efficacy.

A Bioactive Enamel Sealer Can Protect Enamel during Orthodontic Treatment: An In Vitro Study

Background: This study aimed to evaluate the effectiveness of an experimental bioactive enamel resin sealer in protecting the enamel adjacent to orthodontic brackets against erosion. Methods: Orthodontic brackets (n = 50) were bonded to freshly extracted, sound maxillary premolars using Transbond™ XT Primer (3M Unitek, Monrovia, CA, USA) and Transbond Plus Color Change adhesive (3M Unitek, USA). Five experimental groups (n = 10) had the following treatments applied: a resin bioactive sealer with 45S5 bioglass, 35% by weight; a resin sealer without bioactive glass; fluoride; the orthodontic sealer, Opal Seal (Opal-Orthodontics, South Jordan, UT, USA); and, in the control group, an untreated surface. All the specimens were stored for 18 min in 1% citric acid. All the specimens were examined by SEM and electron dispersive spectroscopy (EDS). The Wilcoxon signed-rank test was used to compare the enamel surfaces covered by the sealers before and after the acid challenge. Attenuated total reflectance Fourier transform infrared spectroscopy detected the degree of the experimental resins’ conversion to verify their suitability for clinical use. Results: The percentage of the bioactive resin sealer and Opal Seal groups’ protection against enamel erosion was 100%, which was significantly more than the other groups, p < 0.05. The degree of conversion for the bioactive and unfilled resins was 42.4% ± 3.6% and 48.57% ± 5%, respectively. Conclusion: The bioactive resin sealer and the Opal Seal both protected the enamel from erosion.

Brushing Effect on the Properties of Glass Ionomer Cement Modified by Hydroxyapatite Nanoparticles or by Bioactive Glasses

This study evaluated the physical and mechanical properties of glass ionomer cement (GIC) associated with 5% hydroxyapatite nanoparticles (NPHAps) and 10% bioactive glass (BAG) 45S5 before and after brushing at different storage times. Surface roughness was evaluated using a rugosimeter, Vickers hardness using a microdurometer, and mass variation measured in an analytical balance at 1, 7, 15, 30, and 60 days before and after the brushing test, with the aid of toothbrushing simulator and soft bristle toothbrushes. Nonnormal distribution was observed, and the nonparametric Wilcoxon and Kruskal–Wallis tests followed by Dunn's were performed, with a significance level of 5%. We observed higher values for mass loss on the first day for all groups. The surface roughness was lower in the control and NP groups, 30 days after brushing. Higher values for hardness were found in the control group and lower ones for NP, after brushing. The control and BAG groups presented a decrease in hardness over time. The NP group presented the highest values before brushing, while the control group had the highest values after brushing. The association of NPHPa with the GIC is the most promising combination, since it presented satisfactory values for surface hardness. However, conventional GIC not associated with NPHPa or BAG is still an option, since it is available in the market and the most economically viable option.

Effect of Novel Bioactive Glass-Containing Dentin Adhesive on the Permeability of Demineralized Dentin

This study aimed to evaluate the effect of a novel bioactive glass (BAG)-containing dentin adhesive on the permeability of demineralized dentin. Bioactive glass (85% SiO₂, 15% CaO) was fabricated using the sol-gel process, and two experimental dentin adhesives were prepared with 3 wt% silica (silica-containing dentin adhesive; SCA) or BAG (BAG-containing dentin adhesive; BCA). Micro-tensile bond strength (μTBS) test, fracture mode analysis, field-emission scanning electron microscopy (FE-SEM) analysis of adhesive and demineralized dentin, real-time dentinal fluid flow (DFF) rate measurement, and Raman confocal microscopy were performed to compare SCA and BCA. There was no difference in μTBS between the SCA and BCA (p > 0.05). Multiple precipitates were evident on the surface of the BCA, and partial occlusion of dentinal tubules was observed in FE-SEM of BCA-approximated dentin. The DFF rate was reduced by 50.10% after BCA approximation and increased by 6.54% after SCA approximation. Raman confocal spectroscopy revealed an increased intensity of the hydroxyapatite (HA) peak on the dentin surface after BCA application. The novel BAG-containing dentin adhesive showed the potential of both reducing dentin permeability and dentin remineralization.

Enamel erosion control by strontium-containing TiO2- and/or MgO-doped phosphate bioactive glass

OBJECTIVES

To evaluate the effect of strontium-containing titanium- and/or magnesium-doped phosphate bioactive glass on the control of dental erosion.

MATERIALS AND METHODS

Fifty fragments of human enamel were divided into five groups: negative control, 45S5 bioglass, strontium-containing Ti-doped phosphate bioactive glass (PBG-Ti), strontium-containing Mg-doped phosphate bioactive glass (PBG-Mg), and strontium-containing Ti- and Mg-doped phosphate bioactive glass (PBG-TiMg). The specimens underwent cycles of erosive challenge twice daily for 5 days with 1 mL of citric acid for 2 min followed by 1 mL of the suspension with bioactive substances for 3 min. After the cycles, profilometry, roughness and microhardness testing, and scanning electron microscopy (SEM) were performed. The following statistical tests were used: one-way ANOVA (profile, roughness, and surface microhardness (%VMS) data variation), Tukey's HSD (%VMS), Games-Howell test (profilometry), Student's t test (roughness), and Pearson's correlation between the variables.

RESULTS

The lower loss of enamel surface and lower %VMS was observed in the PBG-Mg and PBG-TiMg groups, and only the PBG-Mg group showed similar roughness between baseline and eroded areas (p > 0.05). On SEM micrographs, PBG-Ti and PBG-Mg groups showed lower apparent demineralization.

CONCLUSION

All bioactive materials protected the enamel against erosion. However, strontium-containing phosphate bioactive glasses showed lower enamel loss, and the presence of Mg in these bioactive glasses provided a greater protective effect.

CLINICAL RELEVANCE

Experimental strontium-containing phosphate bioactive glasses are effective in controlling enamel erosion. The results obtained in this study will guide the development of new dental products.

Role of bioglass in enamel remineralization: Existing strategies and future prospects-A narrative review

Enamel, once formed, loses the ability to regenerate due to the loss of the formative ameloblasts. It is subjected to constant damaging events due to exposure to external agents and oral microbiomes. An enamel remineralization process targets to replenish the lost ionic component of the enamel through a multitude of methods. Enamel remineralization is highly challenging as it has a complex organized hierarchical microstructure. Hydroxyapatite nanocrystals of the enamel vary in size and orientation along alignment planes inside the enamel rod. The inability of the enamel to remodel unlike other mineralized tissues is another substantial deterrent. One of the well-known biomaterials, bioglass (BG) induces apatite formation on the external surface of the enamel in the presence of saliva or other physiological fluids. Calcium, sodium, phosphate, and silicate ions in BG become responsive in the presence of body fluids, leading to the precipitation of calcium phosphate. Studies have also demonstrated the bactericidal potential of BG against Streptococcus mutans biofilms. The anticariogenicity and antibacterial activity were found to be enhanced when BG was doped with inorganic ions such as F, Ag, Mg, Sr, and Zn. Due to the versatility of BG, it has been combined with a variety of agents such as chitosan, triclosan, and amelogenin to biomimic remineralization process. Key strategies that can aid in the development of contemporary enamel remineralization agents are also included in this review.

Effect of Bioactive Glass-Containing Light-Curing Varnish on Enamel Remineralization

This study aimed to evaluate the effect of novel experimental light-curing bioactive glass (BAG)-containing varnish on enamel remineralization. An experimental light-curing, BAG-containing varnish and two commercial varnishes (Nupro White Varnish; Dentsply International, York, PA, USA and Tooth Mousse; GC Corporation, Tokyo, Japan) were used. Microhardness tests (n = 3), field emission scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray spectroscopy (EDS) (n = 5), and X-ray diffraction (XRD) analysis (n = 5) were performed to compare the remineralization effect of three varnishes with and without ultrasonication. The data of microhardness test were analyzed using one-way ANOVA and Tukey's post hoc comparison (P < 0.05). Microhardness of demineralized enamel increased after the application of three varnishes (P < 0.05). The experimental BAG-containing varnish showed the highest microhardness among the three varnishes (P < 0.05). Ultrasonication decreased microhardness of Tooth Mousse and BAG-containing varnish groups (P < 0.05). FE-SEM and XRD revealed precipitates of hydroxyapatite (HAP) or fluorapatite (FAP) crystals of three varnishes. The novel experimental BAG-containing varnish may be a promising clinical strategy for the remineralization of early carious lesions or demineralized enamel surfaces.

Novel Bioactive Glass-Modified Hybrid Composite Resin: Mechanical Properties, Biocompatibility, and Antibacterial and Remineralizing Activity

Secondary caries seriously limits the lifetime of composite resin. However, integrating all desirable properties (i.e., mechanical, antibacterial, bioactivity, and biocompatibility) into one composite resin is still challenging. Herein, a novel bioactive glass (BAG)-modified hybrid composite resin has been successfully developed to simultaneously achieve excellent mechanical properties, good biocompatibility, and antibacterial and remineralizing capabilities. When the mass fractions of BAG particles were added from 8 to 23 wt %, the original mechanical properties of the composite resin, including flexural strength and compressive strength, were not obviously affected without compromising the degree of conversion. Although the BAG incorporation of mass fractions of 16 wt % to 23 wt % in composite resins reduced cell viability, the viability could be recovered to normal by adjusting the pH value. Moreover, the BAG-modified composite resins that were obtained showed good antibacterial effects against Streptococcus mutans and enhanced remineralizing activity on demineralized dentin surfaces with increasing incorporation of BAG particles. The possible mechanisms for antibacterial and remineralizing activity might be closely related to the release of bioactive ions (Ca²⁺, Si⁴⁺), suggesting that its antibacterial and biological properties can be controlled by modulating the amounts of bioactive ions. The capability to balance the mechanical properties, cytotoxicity, antibacterial activity, and bioactivity makes the BAG-modified composite resin a promising prospect for clinical application. Our findings provide insight into better design and intelligent fabrication of bioactive composite resins.

Mesoporous Silica-Bioglass Composite Pellets as Bone Drug Delivery System with Mineralization Potential

For decades, local bone drug delivery systems have been investigated in terms of their application in regenerative medicine. Among them, inorganic polymers based on amorphous silica have been widely explored. In this work, we combined two types of amorphous silica: bioglass and doxycycline-loaded mesoporous silica MCM-41 into the form of spherical granules (pellets) as a bifunctional bone drug delivery system. Both types of silica were obtained in a sol-gel method. The drug adsorption onto the MCM-41 was performed via adsorption from concentrated doxycycline hydrochloride solution. Pellets were obtained on a laboratory scale using the wet granulation-extrusion-spheronization method and investigated in terms of physical properties, drug release, antimicrobial activity against Staphylococcus aureus, mineralization properties in simulated body fluid, and cytotoxicity towards human osteoblasts. The obtained pellets were characterized by satisfactory mechanical properties which eliminated the risk of pellets cracking during further investigations. The biphasic drug release from pellets was observed: burst stage (44% of adsorbed drug released within the first day) followed by prolonged release with zero-order kinetics (estimated time of complete drug release was 19 days) with maintained antimicrobial activity. The progressive biomimetic apatite formation on the surface of the pellets was observed. No cytotoxic effect of pellets towards human osteoblasts was noticed.

Characterization of a novel enamel sealer for bioactive remineralization of white spot lesions

OBJECTIVES

45S5 Bioglass is a bioactive glass capable of releasing ions that can interact with dental hard tissues. The current study aimed at examining the effectiveness of 45S5 Bioglass in remineralizing enamel white spot lesion (WSL) as well as its effect on the bond strength of orthodontic brackets bonded to demineralized enamel.

MATERIALS AND METHODS

WSLs were induced in the buccal surfaces of 135 human extracted teeth by storage in acid solution pH 4.5 for four days. The specimens were then equally divided into three groups; Demineralized group, Bioglass group (BG), and control group (intact enamel). The groups were chemically analyzed using (FTIR/ATR) Fourier-transform infrared spectroscopy/attenuated total reflectance, (XRD) X-ray diffraction, and (SEM/EDS) scanning electron microscope equipped with electron-dispersive-spectroscopy. Moreover, 10 specimens from each group were tested using Transverse Micro Radiography (TMR) technique, and 15 specimens from each group were bonded with metal orthodontic brackets and tested for shear bond strength test (SBS). The data were analyzed statistically using One way ANOVA p < 0.05.

RESULTS

TMR study showed that bioglass group samples recorded lesion depth of 70.19 ± 29.21 μm and Δ Z (mineral loss) 732.15 ± 210.16 vol% μm which was significantly lower than the demineralized specimens having lesion depth of 115.75 ± 19.98 μm and Δ Z (mineral loss) 3472.69 ± 738.38 vol%μm, moreover, bioglass specimens recorded 14.15 ± 2.35 Mpa which was significantly higher than demineralized specimens 6.82+1.83 Mpa but less than the control specimens 20.5 + 6.1 MPa (p < 0.05). FTIR/ATR, XRD, and SEM/EDS tests showed that bioglass paste formed a layer of brushite crystals onto the treated enamel surface.

CONCLUSION

45S5 bioglass paste may serve as an effective remineralizing agent for demineralized enamel.

The Efficiency of Fluoride Bioactive Glasses in Protecting Enamel Surrounding Orthodontic Bracket

Objectives

The aim of this study was to evaluate the protective effect of using four different fluoride bioactive enamel sealers against an acidic erosion challenge.

Materials and Methods

A sample of 50 freshly extracted sound upper premolars had their buccal surface bonded to 50 orthodontic brackets using Transbond PLUS color change adhesive; the first four groups had four compositions of fluoride bioactive glasses based on 37 mol% SiO₂, 43.9-53.9 mol% CaO, 6.1 mol% P₂O₅ and CaF₂, and 0-10 mol% of Na₂O applied to their surfaces and the fifth group served as control (which was not treated by any bioactive sealer). All specimens were challenged by 1% citric acid for 18 minutes which was stirred by a magnetic stirrer. The enamel surfaces next to the orthodontic brackets were examined by SEM. The Wilcoxon signed-rank test was used to compare the area covered by the fluoride bioactive pastes before/after erosion (p < 0.05). Samples from the layer formed on top of the examined teeth were tested before/after erosion to be examined by the attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR/ATR).

Results

The FTIR/ATR test showed that fluoride bioactive pastes' applications resulted in the formation of a hydroxyapatite-rich layer; the SEM analysis showed that the aforementioned layer significantly resisted erosion challenge when compared to the control group (p < 0.05).

Conclusions

Fluoride bioactive pastes can efficiently protect the enamel surfaces next to orthodontic brackets from acidic erosion challenges.

Silica-Based Bioactive Glasses and Their Applications in Hard Tissue Regeneration: A Review

Regenerative medicine is a field that aims to influence and improvise the processes of tissue repair and restoration and to assist the body to heal and recover. In the field of hard tissue regeneration, bio-inert materials are being predominantly used, and there is a necessity to use bioactive materials that can help in better tissue-implant interactions and facilitate the healing and regeneration process. One such bioactive material that is being focused upon and studied extensively in the past few decades is bioactive glass (BG). The original bioactive glass (45S5) is composed of silicon dioxide, sodium dioxide, calcium oxide, and phosphorus pentoxide and is mainly referred to by its commercial name Bioglass. BG is mainly used for bone tissue regeneration due to its osteoconductivity and osteostimulation properties. The bioactivity of BG, however, is highly dependent on the compositional ratio of certain glass-forming system content. The manipulation of content ratio and the element compositional flexibility of BG-forming network developed other types of bioactive glasses with controllable chemical durability and chemical affinity with bone and bioactivity. This review article mainly discusses the basic information about silica-based bioactive glasses, including their composition, processing, and properties, as well as their medical applications such as in bone regeneration, as bone grafts, and as dental implant coatings.

Li-doped bioglass® 45S5 for potential treatment of prevalent oral diseases

OBJECTIVES

Despite the excellent properties of both pure bioglasses (BG) and BG doped with therapeutic ions (such as Li) in hard tissue applications, there is not enough information about their role in the remineralization and bacterial-growth in oral diseases. The aim of this contribution is to evaluate the effect of both pure BG and BG doped with 5-wt% of Li (BGLi) on both the remineralization of in vitro demineralized human-teeth and the antimicrobial behavior against strains from caries and periodontitis.

METHODS

Bioglass® 45S5 (BG) and BGLi were synthesized by the sol-gel method. The remineralization tests were carried out using in vitro demineralized enamel teeth and evaluated by Electron Microscopy (SEM) and Vickers micro-hardness (HV). The antimicrobial behavior of the particles was evaluated against S. mutans, A. actinomycetemcomitans, and P. gingivalis, representing pathogens from caries and periodontitis.

RESULTS

Enamel lesion was partially remineralized when both bioglasses (BG and BGLi) were applied on its surface with micro-hardness recoveries around 45 %. They further inhibited the growth of S. mutans and P. gingivalis, at 50 and 200 mg/mL, respectively. BGLi presented a higher toxicity against A. actinomycetemcomitans than BG, with inhibition concentrations of 20 mg/mL and 100 mg/mL, respectively.

CONCLUSIONS

Bioglasses could be used in the treatment of two of the most prevalent oral diseases: caries and periodontitis, promoting the remineralization of the teeth and killing the main pathogens. The presence of Li did not affect the bioactivity of the bioglass and improved the antibacterial effect over A. actinomycetemcomitans strain.

Effect of fluoride, casein phosphopeptide-amorphous calcium phosphate and sodium trimetaphosphate combination treatment on the remineralization of caries lesions: An in vitro study

OBJECTIVE

To evaluate the effects of combination of treatments with fluoridated toothpastes supplemented with sodium trimetaphosphate (TMP) and casein phosphopeptide-amorphous calcium phosphate (MI Paste Plus®), on the remineralization of dental enamel.

DESIGN

Enamel blocks with artificial caries were randomly allocated into six groups (n = 12), according to the toothpastes: 1) without F-TMP-MI Paste Plus® (Placebo); 2) 1100 ppm F (1100 F), 3) MI Paste Plus®, 4) 1100 F + MI Paste Plus® (1100 F-MI Paste Plus®), 5) 1100 F + 3% TMP (1100 F-TMP) and 6) 1100 F-TMP + MI Paste Plus® (1100 F-TMP-MI Paste Plus®). Blocks were treated 2×/day with slurries of toothpastes (1 min). Furthermore, groups 4 and 6 received the application of MI Paste Plus® for 3 min. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); profile analysis and lesion depth subsurface through polarized light microscopy (PLM), confocal laser scanning microscopy (LSCM), scanning electron microscopy (SEM), fluoride (F), calcium (Ca), phosphorus (P) concentrations in the enamel were determined. The data were analyzed by ANOVA (1-criterion) and Student-Newman-Keuls test (p < 0.001).

RESULTS

1100 F-TMP-MI Paste Plus® group showed the best results of %SHR, ΔKHN and PLM (p < 0.001). F concentration was similar between the 1100 F, 1100 F-MI Paste Plus®, and 1100 F-TMP-MI Paste Plus® groups (p > 0.001). 1100 F-TMP-MI Paste Plus® group showed the highest concentration of Ca and P in the enamel (p < 0.001).

CONCLUSION

The association of 1100 F-TMP and MI Paste Plus® led to a significant increase in the remineralization of initial carious lesions.

Fluoride bioactive glass paste improves bond durability and remineralizes tooth structure prior to adhesive restoration

OBJECTIVE

The current study aimed at examining a fluoride containing bioactive glass (BiominF®) paste as a temporary filling material capable of remineralizing the demineralized enamel or dentin, and its ability to decrease a simulated dentinal fluids pressure on the resin/dentin interface, without affecting the shear bond strength of a universal bonding agent to enamel and dentin.

METHODS

60 premolars were utilized for the acid resistance, trans-microradiography (TMR) and shear bond strength (SBS) experiments. Enamel and dentin discs were demineralized for 4 days to create a subsurface demineralized zone followed by applying BiominF® paste, 1.23% acidulated phosphate fluoride, or a temporary filling material for 24 h. 30 extracted human non-carious third molars were utilized for the pulpal pressure experiment in which direct communication to the pulp chamber was created by cutting at a level approximately 1 mm below the cemento-enamel junction while the coronal enamel was ground to expose mid coronal dentin. The dentin surface was exposed to a simulated pulpal pressure. The dentin surfaces had BiominF® paste, an oxalate desensitizing agent, or temporary filling material followed by application of a universal adhesive system.

RESULTS

One way ANOVA showed that BiominF® paste remineralized effectively the demineralized enamel or dentin, did not affect the bond strength of the enamel and dentin surfaces to the tested adhesive system p < 0.05, and improved the acid resistance of the demineralized enamel and dentin against a secondary erosive challenge. Moreover, BiominF® paste decreased the nanoleakage expression in the dentin/adhesive interface exposed to a simulated pulpal pressure.

SIGNIFICANCE

BiominF® paste may serve as a temporary filling material that may improve the longevity of adhesive restorations and help to conserve tooth structures by preserving the demineralized enamel and dentin form cutting during cavity preparation.

Biomimetic Aspects of Oral and Dentofacial Regeneration

Biomimetic materials for hard and soft tissues have advanced in the fields of tissue engineering and regenerative medicine in dentistry. To examine these recent advances, we searched Medline (OVID) with the key terms “biomimetics”, “biomaterials”, and “biomimicry” combined with MeSH terms for “dentistry” and limited the date of publication between 2010–2020. Over 500 articles were obtained under clinical trials, randomized clinical trials, metanalysis, and systematic reviews developed in the past 10 years in three major areas of dentistry: restorative, orofacial surgery, and periodontics. Clinical studies and systematic reviews along with hand-searched preclinical studies as potential therapies have been included. They support the proof-of-concept that novel treatments are in the pipeline towards ground-breaking clinical therapies for orofacial bone regeneration, tooth regeneration, repair of the oral mucosa, periodontal tissue engineering, and dental implants. Biomimicry enhances the clinical outcomes and calls for an interdisciplinary approach integrating medicine, bioengineering, biotechnology, and computational sciences to advance the current research to clinics. We conclude that dentistry has come a long way apropos of regenerative medicine; still, there are vast avenues to endeavour, seeking inspiration from other facets in biomedical research.

Synergetic Effect of 2-Methacryloyloxyethyl Phosphorylcholine and Mesoporous Bioactive Glass Nanoparticles on Antibacterial and Anti-Demineralisation Properties in Orthodontic Bonding Agents

2-methacryloyloxyethyl phosphorylcholine (MPC) is known to have antibacterial and protein-repellent effects, whereas mesoporous bioactive glass nanoparticles (MBN) are known to have remineralisation effects. We evaluated the antibacterial and remineralisation effects of mixing MPC and MBN at various ratios with orthodontic bonding agents. MPC and MBN were mixed in the following weight percentages in CharmFil-Flow (CF): CF, 3% MPC, 5% MPC, 3% MPC + 3% MBN, and 3% MPC + 5% MBN. As the content of MPC and MBN increased, the mechanical properties of the resin decreased. At 5% MPC, the mechanical properties decreased significantly with respect to CF (shear bond strength), gelation of MPC occurred, and no significant difference was observed in terms of protein adsorption compared to the control group. Composition 3% MPC + 5% MBN exhibited the lowest protein adsorption because the proportion of hydrophobic resin composite decreased; CF (91.8 ± 4.8 μg/mL), 3% MPC (73.9 ± 2.6 μg/mL), 3% MPC + 3% MBN (69.4 ± 3.6 μg/mL), and 3% MPC + 5% MBN (55.9 ± 1.6 μg/mL). In experiments against S. mutans and E. coli, addition of MPC and MBN resulted in significant antibacterial effects. In another experiment, the anti-demineralisation effect was improved when MPC was added, and when MBN was additionally added, it resulted in a synergetic effect. When MPC and MBN were added at an appropriate ratio to the orthodontic bonding agents, the protein-repellent, antibacterial, and anti-demineralisation effects were improved. This combination could thus be an alternative way of treating white spot lesions.

Bioactivity assessment of bioactive glasses for dental applications: A critical review

OBJECTIVE

In the context of minimally invasive dentistry and tissue conservation, bioactive products are valuable. The aim of this review was to identify, clarify, and classify the methodologies used to quantify the bioactive glasses bioactivity.

METHODS

Specific search strategies were performed in electronic databases: PubMed, Embase, Cochrane Library, and Scopus. Papers were selected after a review of their title, abstract, and full text. The following data were then examined for final selection: BAG investigated, objectives, criteria, methods, and outcomes.

RESULTS

Sixty-one studies published from 2001 to 2019, were included. The bioactivity of BAG can be evaluated in vitro in contact with solutions, enamel, dentin, or cells. Other studies have conducted in vivo evaluation by BAG contact with dentin and dental pulp. Studies have used various analysis techniques: evaluation of apatite with or without characterization or assessment of mechanical properties. Reprecipitation mechanisms and pulp cell stimulation are treated together through the term 'bioactivity'.

SIGNIFICANCE

Based on these results, we suggested a classification of methodologies for a better understanding of the bioactive properties of BAG. According to all in vitro studies, BAG appear to be bioactive materials. No consensus has been reached on the results of in vivo studies, and no comparison has been conducted between protocols to assess the bioactivity of other bioactive competitor products.

The Effect of Remineralizing Agents With/Without CO2 Laser Irradiation on Structural and Mechanical Properties of Enamel and its Shear Bond Strength to Orthodontic Brackets

Introduction: Remineralizing agents may be used for the treatment of white spot lesions (WSLs) prior to bracket bonding. However, some concerns exist regarding their possible interference with the etching and bonding process, negatively affecting the bond strength. This study aimed to assess the effect of two remineralizing agents with/without CO₂ laser irradiation on the mechanical properties and shear bond strength (SBS) of demineralized enamel to the orthodontic bracket. Methods: This study evaluated 60 premolar teeth in 6 groups (n=10) as follows: (I) sound enamel, (II) demineralized enamel, (III) Nupro remineralizing agent (N), (IV) Nupro and CO₂ laser (N/L), (V) Teethmate remineralizing agent (T), and (VI) Teethmate and CO₂ laser (T/L). The remineralizing agents were applied to the enamel surfaces after their immersion in a demineralizing solution for 5 days. In groups IV and VI, the CO₂ laser with a 10.6 μm wavelength, 10 ms pulse duration, a 50 Hz repetition rate, 0.3 mm beam diameter and 0.7 W power was irradiated after applying the remineralizing agents. Brackets were bonded to the enamel surfaces and SBS was measured by a universal testing machine. For the assessment of enamel microhardness, 20 sections of molar teeth were divided into 4 groups (n=5; N, N/L, T, T/L) and their microhardness was measured before demineralization, after demineralization and after remineralization. X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM) and energy-dispersive spectrometry (EDS) were carried out to assess the formation of hydroxyapatite. The atomic percentages of the C, O, P, Ca, Na, Si, F and Ca/P ratio were determined by EDS analysis. Results: The SBS significantly decreased in group II (P<0.001). There was no significant difference among the groups I, III, IV, V and VI (P<0.05). This finding was similar to the microhardness results, which showed an increase in microhardness after remineralization (P<0.05), with no difference among the remineralizing agents. The Ca/P ratio was the highest in the Nupro group and the lowest in the demineralized group. Conclusion: Remineralizing agents can significantly improve the microhardness and structural properties of demineralized enamel to a level similar to that of sound enamel with no adverse effect on SBS to orthodontic brackets.

Effect of air-abrasion pre-treatment with bioactive glass 45S5 on enamel surface loss after erosion/abrasion challenge

OBJECTIVES

The aim of this in vitro study was to evaluate the effect of air-abrasion surface pre-treatment with bioactive glass (BAG) 45S5 on enamel surface loss after erosion/abrasion challenge.

METHODS

Twenty-four sound bovine incisors were used for this study. Four experimental groups (n=12) were assigned as follows: Group 1 was the negative control group, Group 2 specimens were treated with a SnF₂ gel (positive control group), Group 3 specimens were air-abraded with BAG 45S5 (ProSylc) and Group 4 received both treatments. The specimens were submitted to erosion/abrasion challenge using a common soft drink. Enamel surface loss was evaluated using an optical profilometer. Additionally, surface roughness (VSI method) and surface microhardness (Vickers method) changes were evaluated, as well as SEM and EDS analyses were performed on enamel surface. The data were statistically analyzed using one-way ANOVA and Tukey's post-hoc test at a level of significance a=0.05.

RESULTS

Surface pre-treatment with BAG 45S5 reduced surface loss in comparison with negative control group (p<0.001), which exhibited the highest surface loss of the experimental groups (p<0.05). The positive control group (SnF₂ treatment) and Group 4 specimens, which received both air-abrasion pre-treatment and SnF₂ treatment, presented the lowest surface loss (p<0.05), but did not show significant differences to each other (p=0.65).

SIGNIFICANCE

Air-abrasion pre-treatment with BAG 45S5 may be beneficial as an in-office preventive method for the limitation of enamel erosive wear induced by excessive consumption of soft drinks. The clinical significance of the results regarding this preventive method should be confirmed by clinical studies.

The efficacy of a bioglass (45S5) paste temporary filling used to remineralize enamel surfaces prior to bonding procedures

OBJECTIVES

The efficacy of using a 45S5 Bioglass paste as a remineralizing temporary filling material was compared to fluoride gel (1.23% acidulated-phosphate-fluoride, Gelato Gel, NJ, USA) applied for 24 h and for 4 min and to a temporary filling material (Caviton; GC, Tokyo, Japan).

METHODS

66 extracted human premolars were used. All specimens were sectioned mesio-distally. All specimens were challenged by a demineralization solution (pH4.5) for 4 days. The specimens were divided into 4 groups: (Bioglass), (Fluoride 4-minutes), (Fluoride 24-Hours), and (Temp) (n = 33). 10 specimens were examined by TMR (Transversal Microradiography)to test remineralization capacity of each agent. 8 specimens were assigned to determine the acid resistance of a bonded resin-enamel interface after the various treatment methods. 15 samples were assigned to determine the effect of each agent on the shear bond strength of a single bottle self-etch adhesive system. One way ANOVA was used to compare the obtained results (p < 0.05).

RESULTS

Specimens treated with 45S5 bioglass showed statistically significant reductions in (delta z) values when compared to the other three groups (p < 0.05). Treatment of demineralized enamel by fluoride prior to bonding significantly decreased shear bond strength values, however 45S5 bioglass treatment did not affect the shear bond strength of adhesive system to enamel (p < 0.05). The acid-resistance of the interface between resin-enamel was significantly improved when fluoride or bioglass were applied onto the enamel surface prior to demineralization.

CONCLUSIONS

45S5 bioglass paste has high potential to be used as a remineralizing temporary filling material.

Effects of Poly(Amidoamine) Dendrimer-Coated Mesoporous Bioactive Glass Nanoparticles on Dentin Remineralization

Dentin hypersensitivity (DH) is one of the most common clinical conditions usually associated with exposed dentinal surfaces. In this study, we identified the effectiveness of poly(amidoamine) (PAMAM) dendrimer-coated mesoporous bioactive glass nanoparticles (MBN) (PAMAM@MBN) on DH treatment, examining the ion-releasing effect, dentin remineralization, and the occluding effect of dentinal tubules. We synthesized MBN and PAMAM@MBN. After soaking each sample in simulated body fluid (SBF), we observed ion-releasing effects and dentin remineralization effects for 30 days. Also, we prepared 30 premolars to find the ratio of occluded dentinal tubules after applying MBN and PAMAM@MBN, respectively. The results showed that PAMAM did not disrupt the calcium ion-releasing ability or the dentin remineralization of MBN. The PAMAM@MBN showed a better occluding effect for dentinal tubules than that of MBN (p < 0.05). In terms of dentinal tubule occlusion, the gap between MBN was well occluded due to PAMAM. This implies that PAMAM@MBN could be effectively used in dentinal tubule sealing and remineralization.

45S5 Bioglass paste is capable of protecting the enamel surrounding orthodontic brackets against erosive challenge

OBJECTIVES:

This study aimed at evaluating the effect of using a 45S5 bioglass paste and a topical fluoride as protective agents against acidic erosion (resembling acidic beverage softdrinks intake) for enamel surrounding orthodontic brackets.

MATERIALS AND METHODS:

Sample of 21 freshly extracted sound incisor and premolar teeth was randomly divided into three equal groups: a bioglass group (Bioglass) (NovaMin, 5-mm average particle, NovaMin Technology), a Fluoride group (Fluoride) (Gelato APF Gel, Keystone Industries), and a control group (Control). Orthodontic brackets were bonded to the utilized teeth usingMIP (Moisture Insensitive Primer) and Transbond PLUS color change adhesive. All specimens were challenged by 1% citric acid for 18 min. The top enamel surfaces next to the orthodontic brackets were examined by SEM-EDS. Wilcoxon Signed-Rank test was used to compare the area covered by the 45S5 bioglass paste before/after erosion P < 0.05.

RESULTS:

45S5 bioglass paste application resulted in the formation of an interaction layer that significantly resisted erosion challenge P < 0.05. The fluoride and control specimens showed signs of erosion of the enamel next to the orthodontic brackets (P < 0.05).

CONCLUSION:

45S5 bioglass paste can efficiently protect the enamel surfaces next to orthodontic brackets for acidic erosion challenges.

A Novel Fluoride Containing Bioactive Glass Paste is Capable of Re-Mineralizing Early Caries Lesions

White-spot-lesions (WSL) are a common complication associated with orthodontic treatment. In the current study, the remineralization efficacy of a BiominF^® paste was compared to the efficacy of a fluoride gel. Methods: Orthodontic brackets were bonded to 60 human premolars buccal surfaces, which were covered with varnish, except a small treatment area (3 mm²). All specimens were challenged by a demineralization solution for 4 days. Specimens were assigned into 4 groups: BiominF^® paste, Fluoride (4-min application), fluoride (twenty four hours application), and the control (n = 15). After cross-sectioning, enamel slabs having a thickness of approximately 100–120 μm were obtained. A TMR (Transverse Micro Radiography) technique was used to observe the sub-surface enamel lesions’ depth and mineral density, and their response to the remineralization protocols. One way ANOVA was used to analyze the results (α = 0.05). The top and the cross-sectional surfaces were observed using SEM/EDS. Results: Specimens treated with BiominF^® paste showed significant decrease in delta z values, however lesion depth showed no significant difference when compared to the other three groups (p < 0.05). SEM/EDS observation showed the formation of crystal like structures on top of enamel demineralized surfaces, when treated with BiominF^® paste. In conclusion BiominF^® paste can be considered an effective remineralizing agent for white spot Lesions.

Enamel Remineralization with Novel Bioactive Glass Air Abrasion

Enamel demineralization or white spot lesions (WSLs) are a frequent complication associated with fixed appliance–based orthodontic treatment. The remineralization potential of a novel fluoride-containing bioactive glass (QMAT3) propelled via an air abrasion system was compared with Sylc glass and artificial saliva on artificially induced WSLs. Thirty extracted human premolars were randomly assigned into 3 groups ( n = 10) per method of treatment and scanned with optical coherence tomography and noncontact profilometer in the 4 enamel states: sound, demineralized, after glass propulsion, and after immersion in artificial saliva. Knoop hardness testing was also performed. Twenty additional prepared teeth samples were also randomly selected for examination by scanning electron microscopy and energy-dispersive X-ray spectroscopy (2 teeth per technique) under each of the 4 enamel conditions. 19F MAS-NMR (magic angle spinning–nuclear magnetic resonance) was also used to detect the type of apatite formed on the enamel surface. Significant enamel remineralization with surface roughness and intensity of light backscattering similar to that of sound enamel was observed following treatment with QMAT3. In addition, mineral deposits were detected on the remineralized enamel surfaces, forming a protective layer and improving its hardness. This layer was rich in calcium, phosphate, and fluoride; 19F MAS-NMR confirmed the formation of fluorapatite. This finding is particularly beneficial since fluorapatite is more chemically stable than hydroxyapatite and has greater resistance to acid attack. Hence, a promising fluoride-containing bioactive glass for enamel remineralization has been developed, although further clinical evaluation and refinement is required.

Increasing the efficiency of CPP-ACP to remineralize enamel white spot lesions

OBJECTIVES

To compare the remineralization efficacy of using the MI paste plus according to manufacturer's instructions to MI varnish and to using a modified method of MI-paste plus application.

MATERIALS AND METHODS

100 enamel specimens were obtained from the buccal and lingual surfaces of 50 extracted human non-caries third molars. All specimens were challenged by a buffered demineralization solution for 4 days, and were divided in 4 groups with 25 specimens in each group. 25 demineralized specimens had MI paste plus applied for 4 min and then wiped out (MI), 25 specimens had MI paste applied followed by application of SE-bonding agent (MI + Bond), 25 specimens had MI Varnish applied according to manufacturer instructions (MI Varnish) the rest of specimens served as controls (C). All specimens were stored for 7 days in artificial saliva. All specimens had their surface hardness (SH) measured by micro-hardness tester before/after the acidic challenge and after the treatment procedures. After the SH test all specimens were crosssectioned to obtain 100-150 micron thickness specimens to observe the lesion depth before/after treatment by the TMR (Transverse Micro Radiography) technique.

RESULTS

TMR experiment showed that (MI + Bond) and (MI varnish) groups recorded significant decrease in lesion depth and mineral loss of the tested subsurface lesion p < 0.05. (MI + Bond) group scored the highest significant regain of surface micro hardness results p < 0.05.

CONCLUSION

(MI varnish) and the modified application of MI paste are methods that can increase the efficacy of CPP-ACP in remineralizing the enamel surface lesions.

Novel evaluation and treatment techniques for white spot lesions. An in vitro study

OBJECTIVE

White spot lesions (WSLs) are commonly seen during and after orthodontic treatment. Therefore, the objective of this in vitro study was to assess the effect of 45S5-bioglass in remineralizing WSLs using cross-polarization optical coherence tomography (CP-OCT) and confirm the findings by micro-hardness test.

METHODS

Ceramic orthodontic brackets were bonded to the buccal surface of 45 human premolars with Transbond XT primer followed by Transbond PLUS according to the manufacturer's instructions. Then, all specimens were varnished excluding the area of interest (AOI) around the bonded brackets, immersed in demineralizing solution and divided into three groups: BG, REM and CONT. In BG group, 15 specimens were treated with bioglass paste for 24 hours. REM group had 15 specimens stored in remineralization solution for 24 hours. CONT group had the remaining 15 specimens with no treatment. All specimens were examined under CP-OCT and tested using cross-sectional micro-hardness techniques.

RESULTS

CP-OCT analysis showed that the maximum pixel value after bioglass application was significantly increased at AOI when compared to CONT and REM groups (P>.05), which was confirmed by the cross-sectional micro-hardness results (P>.05).

CONCLUSION

Early enamel demineralization and remineralization can be easily and non-invasively monitored with CP-OCT. Bioglass is a potent remineralizing agent.