Prevention of demineralization around orthodontic brackets in vitro

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

BACKGROUND

We investigated the effect of bioactive glass and zinc oxide nanoparticles on enamel remineralization, as well as their antimicrobial effect on cariogenic microbes. This is the first study that investigated the properties of bioactive glass and zinc oxide nanoparticles with mixed materials.

METHODS

Fluoride gel (F), bioactive glass microparticles (µB), bioactive glass nanoparticles (nB), zinc oxide nanoparticles (Z), and a mixed suspension of nB and Z (nBZ) were prepared and characterized by scanning and transmission electron microscopy, zeta potential measurement, X-ray diffraction, and acid buffering capacity testing. Further, we performed a remineralization cycle test of 28 days, and nanoindentation testing was carried out during the immersion period, and then the enamel surfaces were examined using scanning electron microscopy. Additionally, the antimicrobial effects of the sample suspensions were evaluated by measuring their minimum microbicidal concentrations against various cariogenic microbes.

RESULTS

Our results revealed that nB had a near-circular shape with an amorphous structure and a considerably large specific surface area due to nanoparticulation. Additionally, nB possessed a rapid acid buffering capacity that was comparable to that of μB. In the remineralization test, faster recovery of mechanical properties was observed on the enamel surface immersed in samples containing bioactive glass nanoparticles (nB and nBZ). After remineralization, demineralized enamel immersed in any of the samples showed a rough and porous surface structure covered with mineralized structures. Furthermore, nBZ exhibited a broad antimicrobial spectrum.

CONCLUSIONS

These results demonstrated that bioactive glass and zinc oxide nanoparticles have superior demineralization-suppressing and remineralization-promoting effects.

Clinical assessment of various imaging systems for dental plaque scoring after the use of 3 different toothpastes

Purpose

This study was conducted to compare dental plaque scores obtained through clinical examinations and various imaging techniques, as well as to assess the effectiveness of herbal and conventional toothpastes for plaque removal.

Material and Methods

Thirty volunteers were divided into 3 groups. Each group was given a different toothpaste (from 2 herbal toothpastes and a conventional toothpaste) with which to brush their teeth for 21 days. Both initially and after brushing, dental plaque samples were collected, and plaque on the buccal surfaces of anterior teeth was scored using several imaging systems after staining with a disclosing agent. Specifically, digital dental photography, intraoral digital scanning, and FluoreCam imaging were employed to capture intraoral images. The Turesky Modified Quigley-Hein Plaque Index was used for clinical examination and image analysis. Quantitative polymerase chain reaction analyses and correlational assessments between clinical examination and imaging scores were conducted before and after toothpaste use. The Shapiro-Wilk test and Pearson correlations were utilized.

Results

The lowest mean value was observed in the clinical examination without staining, while the highest was obtained using the FluoreCam method. No significant change was found in the level of any microorganism assessed following toothpaste use (P<0.05), with the exception of a decrease in S. mutans levels after using conventional toothpaste (P<0.05).

Conclusion

Herbal toothpaste demonstrated plaque-removal effectiveness comparable to that of conventional toothpaste. The use of imaging methods for measuring plaque index has been suggested as a means to educate patients about plaque control and promote ongoing oral care.

Application of laser on enamel surface with three types of bioactive glasses-based resin infiltrants: An in vitro study

OBJECTIVE

The study aimed to evaluate and compare the surface micro-hardness, roughness, color, and morphology of enamel after Er,Cr:YSGG laser irradiation, followed by application of three types of bioactive glasses-based resin infiltrants, and the samples groups were challenged with the pH cycle.

METHODOLOGY

Experimental photoactivated resin infiltrants were synthesized using dimethacrylate resins, whereby three different types of bioactive glasses (BGs), i.e., 45S5, fluoridated-BG (F-BG), and borosilicate-BG (B-BG), were incorporated into the resin system. Initially, white spot lesions were created artificially on the toosth enamel surface, then irradiated with Er,Cr:YSGG laser. Then, the resin-only and BG-based resins were infiltrated on the enamel surface. All samples were pH challenged for 14 days, and the micro-hardness, surface roughness, surface morphology, and color stability (ΔE) analyses were conducted before and after the 14 days pH challenge.

RESULTS

After laser irradiation, the micro-hardness was significantly high with 45S5 group compared to resin-only (p = 0.021), F-BG (p = 0.042), and B-BG (p = 0.001) groups. After the pH challenge, the micro-hardness values for all groups were reduced significantly (p ≤ 0.05). The surface roughness was least with the resin-only group and showed a non-significant difference with F-BG (p = 0.34) and significant differences with both B-BG (p = 0.005), and 45S5 (p = 0.010) groups. After the pH cycle, the roughness of all groups was increased significantly (p ≤ 0.05), except B-BG group showed a non-significant difference (p = 0.528). The B-BG group showed significantly high ΔE between day 0 and baseline compared to resin-only (p = 0.0008), F-BG (p = 0.017), and 45S5 (p = 0.029), whereas between day 14 and baseline, the lowest ΔE value was observed for B-BG (14.2 ± 2.10) and maximum for the resin-only (20.57 ± 2.47) group. The SEM images showed pitting on the surface of all resin infiltrant groups after 14 days of pH challenge.

CONCLUSION

The morphological difference was observed after the laser irradiation on the enamel surface. The differences in micro-hardness, surface roughness, and color were observed after the application of experimental resin infiltrants and significant differences were observed after the pH challenge.

Effect of self-assembling peptide and other remineralizing agents on preventing initial enamel lesions around orthodontic brackets: An in vitro comparative study

OBJECTIVE

To investigate and compare the effect of self-assembling peptide SAP (P_11-4), casein phosphopeptide-amorphous calcium phosphate fluoride paste (CPP-ACPF), and fluoride varnish (FV) on preventing enamel demineralization around orthodontic brackets.

MATERIAL AND METHODS

Orthodontic brackets were bonded to the buccal surfaces of 80 freshly extracted human maxillary premolars. Teeth were randomly assigned to four groups (n=20) according to the remineralizing agent used as follows: SAP (P_11-4) group (Curodont™ Protect/Credentis), CPP-ACPF group (MI Paste Plus®/Recaldent™), fluoride varnish group (Profluoride varnish®/VOCO), and control group. All products were applied according to the manufacturer's instructions. Specimens were cycled in daily refreshed demineralizing and remineralizing solutions for 8h and 16h, respectively, for 28 days. The calcium/phosphorus ratio (Ca/P) and surface microhardness (SMH) were evaluated at baseline and at two and four weeks. Two-way ANOVA (analysis of variance), one-way ANOVA and repeated measures ANOVA were used for statistical analysis.

RESULTS

Two-way ANOVA demonstrated significant differences between remineralizing agents and time points. After 4 weeks, the SAP (P_11-4) group had had significantly higher Ca/P ratio and SMH (1.68±0.11 and 346.47±55.38) compared to other groups, followed by CPP-ACPF (1.52±0.19 and 283.53±64.75), FV (1.37±0.14 and 262.80±82.98), and the control group (1.31±0.10 and 213.00±41.95). Significantly higher Ca/P ratio and SMH were observed at 2 weeks in the control group (1.44±0.10 and 269.63±57.37) and FV group (1.52±0.09 and 321.17±55.24) compared to 4 weeks. No significant differences were found regarding Ca/P ratio and SMH at 2 weeks in the CPP-ACPF (1.55±0.15 and 295.14±53.88) and SAP P_11-4 groups (1.64±0.10 and 320.18±58.04) compared to 4 weeks.

CONCLUSION

SAP (P_11-4) had the greatest remineralizing efficacy compared to FV and CPP-ACPF. Moreover, extended period of time improved the preventive efficacy of SAP (P_11-4) compared to the other regimens.

Evaluation of shear bond strength and enamel remineralizing effect of experimental orthodontic composite containing nano-hydroxyapatite: An in vitro study

OBJECTIVE

The purpose of this study was to prepare an orthodontic composite containing hydroxyapatite nanoparticles to prevent demineralization and create a suitable environment for mineral deposition around orthodontic brackets, and to investigate the mechanical and remineralizing properties of the experimental adhesive composite.

METHODS

Experimental orthodontic composite were formulated using varying percentages of nano-hydroxyapatite particles. Assessments were based on four groups: a control group (3M™ Transbond™ XT) and experimental composites containing 2% (HA2), 5% (HA5) and 10% (HA10) hydroxyapatite. Vickers Microhardness test was performed to investigate the remineralizing effect in 3 stages: initial stage, after demineralization and after 4 weeks of exposure to artificial saliva. Scanning electron microscopy with energy dispersive X-ray spectroscopy analyser (SEM/EDAX) was used to evaluate hydroxyapatite precipitation and elemental composition of enamel surface. Shear Bond Strength tests were carried out using a universal testing machine and the debonding pattern was assessed using Adhesive Remnant Index (ARI).

RESULTS

All groups showed clinically acceptable SBS values. The highest SBS was achieved in the HA2 group, followed by Transbond™ XT, HA5 and HA10. There was no significant difference in the ARI scores. In terms of microhardness properties, HA5 and HA10 demonstrated a significant increase after 4 weeks. The results of SEM analysis showed the precipitation of hydroxyapatite crystals and EDAX analysis indicated the increase of calcium and phosphate ion peaks compared to the demineralized sample. The data were analysed using one-way ANOVA and Tukey's Post-hoc test.

CONCLUSIONS

Addition of hydroxyapatite nanoparticles to orthodontic composite can increase the mineral content and microhardness of the adjacent enamel. However, increasing the amount of nanoparticles reduces shear bond strength in a decreasing trend. The above-mentioned findings showed that incremental increase of nanoparticles of HA can be incorporated in composite to a certain extent and limitations are determined by mechanical properties (SBS) required for bracket bonding.

An ex vivo evaluation of physico-mechanical and anti-biofilm properties of resin-modified glass ionomer containing ultrasound waves-activated nanoparticles against Streptococcus mutans biofilm around orthodontic bands

BACKGROUND

The present study evaluated the physico-mechanical and antimicrobial properties of ultrasound waves-activated modified-resin glass ionomer containing nanosonosensitizers such as nano-curcumin (n-Cur), nano-emodin (n-Emo), and nano-quercetin (n-Qct) against Streptococcus mutans biofilm on the surface of modified-resin glass ionomer bonded orthodontic bands.

MATERIALS AND METHODS

A total of 50 human molar teeth were used in this study. The shear bond strength (SBS), adhesive remnant index (ARI), setting time, and fluoride release of modified orthodontics cement containing different concentrations of n-Cur, n-Emo, and n-Qct (0, 2, 5, and 10%) were measured. The antimicrobial effectiveness was assessed against S. mutans by the biofilm inhibition test, and the Log₁₀ colony-forming unit (CFU)/mL was evaluated.

RESULTS

SBS and setting time of modified glass ionomer decreased compared with the control group. 5% n-Emo, 2% n-Qct, and 5% n-Cur were the highest concentrations that had an insignificant difference in comparison with Transbond XT (P = 0.647, 0.819, and 0.292, respectively). The groups were not significantly different in terms of ARI score (P > 0.05). The highest and lowest setting time belonged to the control and 5% n-Emo groups, respectively; this difference in setting time was significant (P < 0.05). Ultrasound waves and 0.2% CHX significantly reduced S. mutans biofilms compared with the control group (P < 0.001), and minimum S. mutans colony count was shown in 0.2% CHX and 5% n-Emo groups. The addition of nanosonosensitizers to the glass ionomer did not compromise the fluoride release of the glass ionomer.

CONCLUSION

It could be concluded that resin-modified glass ionomer containing ultrasound waves-activated 5% n-Emo reduces S. mutans biofilm around orthodontic bands with no adverse effect on SBS, ARI, and its application in the clinic.

Evaluating changes in the color and luminosity of dental enamel after orthodontic treatment: A clinical study

The aims of this clinical study were to evaluate the Color change - ΔE (based on spectrophotometry and visual analysis) and luminosity - L* (based on spectrophotometry) of dental enamel surface (after orthodontic treatment) around the area where orthodontic brackets were fixed, based on different cementing materials such as a resin (R group) and resin-modified glass ionomer cement (RMGIC group). The split-mouth study initially comprised 14 patients. Orthodontic brackets were fixed to the upper central incisors with resin or RMGIC. The color of the buccal surface of each tooth was measured through spectrophotometry and visual examination before the bracket-fixation process. Four individuals were excluded during the follow-up; thus 10 patients were evaluated (n=10). Brackets were removed after 12 months of orthodontic treatment, tooth color measurement and visual examination were performed again, and Adhesive Remaining Index (ARI) was also measured. ΔE and L* results were subjected to Student's t-test and by repeated-measures analysis of variance, respectively (α=0.05). ARI data were analyzed in percentages. There was statistically significant difference in ΔE between groups; the R group showed statistically higher values of L* after orthodontic treatment. ARI of 2 and 3 prevailed in the RMGIC group, whereas the R group presented 0 and 1. After orthodontic treatment, the RMGIC group presented smaller changes in ΔE, and the increase in the white scale was observed on the enamel surface around the area where brackets were fixed in the R group. The visual analysis did not show color change on the evaluated teeth.

Study on the role of nano antibacterial materials in orthodontics (a review)

Nanoparticles (NPs) are insoluble particles with a diameter of fewer than 100 nanometers. Two main methods have been utilized in orthodontic therapy to avoid microbial adherence or enamel demineralization. Certain NPs are included in orthodontic adhesives or acrylic resins (fluorohydroxyapatite, fluorapatite, hydroxyapatite, SiO2, TiO2, silver, nanofillers), and NPs (i.e., a thin layer of nitrogen-doped TiO2 on the bracket surfaces) are coated on the surfaces of orthodontic equipment. Although using NPs in orthodontics may open up modern facilities, prior research looked at antibacterial or physical characteristics for a limited period of time, ranging from one day to several weeks, and the limits of in vitro studies must be understood. The long-term effectiveness of nanotechnology-based orthodontic materials has not yet been conclusively confirmed and needs further study, as well as potential safety concerns (toxic effects) associated with NP size.

Effect of topical fluoride gel and fluoride varnish in the prevention of white spot lesions in patients undergoing fixed orthodontic treatment: An in vivo study

Objectives:

Our primary objective was to establish the efficacy of fluoride gel and fluoride varnish in the prevention of white spot lesions (WSLs) development during fixed orthodontic treatment.

Materials and Methods:

The study sample consisted of 60 adult patients in a prospective split-mouth study design. Interventions, that is, topical fluoride gel and topical fluoride varnish were assigned at the time of bonding to either the right or left halves of the dentition. In all subjects, repeated evaluation of demineralization was done on the facial surfaces of sample teeth in each quadrant. Evaluation using laser fluorescence and by direct visual observation under magnification was carried out at bonding (T0), 3 months (T1), and 6 months (T2).

Results:

The distribution of mean DIAGNOdent score at T1 (3.14 ± 1.00 vs. 2.81 ± 0.852) and T2 (4.17 ± 1.41 vs. 3.51 ± 1.13) was observed which is significantly higher in the Gel group compared to the Varnish group. In the Gel group, the distribution of mean DIAGNOdent score at T1 (3.14 ± 1.00) and T2 (4.17 ± 1.41) is significantly higher compared to mean DIAGNOdent score at baseline T0 (2.07 ± 0.66). In the Varnish group, the distribution of mean DIAGNOdent score at T1 (2.81 ± 0.852) and T2 (3.51 ± 1.13) is significantly higher compared to the mean DIAGNOdent score at T0 (2.07 ± 0.66). Visual scores also correlated with DIAGNOdent scores.

Conclusion:

Fluoride varnish is more efficacious than fluoride gel in reducing enamel demineralization. Initial application of fluoride varnish around the orthodontic bracket at bonding appointment can offer significant protection against WSLs.

Therapeutic properties of glass-ionomer cements: Their application to orthodontic treatment

Fluoride has been shown to be an effective agent in the prevention of caries during orthodontic treatment. Resin-modified glass-ionomer cements possess therapeutic anticariogenic properties acting as a fluoride reservoir and releasing fluoride into the environment, particularly at low pH where there is a threat of enamel demineralisation and white spot lesions (WSL's). Patient compliance to instructions in standard oral hygiene measures limits the success of caries prevention and the routine use of glass-ionomer cements can mitigate the lack of compliance, although RMGIC's are not a panacea against WSL's. The adhesion of GIC's to the enamel surface is a physicochemical bond rather than a mechanical bond which reduces the risk of iatrogenic damage to the enamel when bonding and debonding attachments. RMGIC's can be recommended as a bonding adhesive for all attachments but one needs to be selective when bonding molar attachments to avoid occlusal interferences as masticatory forces can be high in these areas.

Effects of desensitizer containing fluoroaluminocalciumsilicate glass nanoparticles on remineralization of root dentin subsurface lesions in vitro

We investigated the remineralization effects of Nanoseal (NS) dentin desensitizer on demineralized root dentin. Baseline lesion specimens prepared from bovine root dentin were immersed in artificial saliva (AS) or deionized water (DW) after treatment with NS or fluoride-free Nanoseal (NS(-)). Treatment and control groups comprised: 1, AS; 2, NS/AS; 3, NS(-)/AS; 4,NS/DW; 5, NS(-)/DW; and 6, baseline demineralization. Integrated mineral loss (IML) and lesion depth (LD) were determined by transverse microradiography. Fluoride concentrations in the immersion solutions were measured. AS, NS/AS and NS(-)/AS showed higher mineral volume % at the surface and lesion body than did other groups. NS/AS showed significantly lower IML than did AS. There was no significant difference in IML between NS/AS and NS(-)/AS. The highest concentration of fluoride was in the NS/AS immersion solution. The findings suggest Nanoseal facilitated remineralization of demineralized root dentin, and fluoride and other ions included may have contributed to this effect.

Effects of polishing with paste containing surface pre-reacted glass-ionomer fillers on enamel remineralization after orthodontic bracket debonding

Surface pre-reacted glass-ionomer (S-PRG) technology allows for the release of multiple ions. This study was performed to investigate the remineralization of etched enamel after removal of the bracket using a novel paste containing S-PRG filler. Surfaces of polished enamel were etched with phosphoric acid and then subdivided into two regions. Bracket bonding resin was thinly applied to one region. After 24-hr immersion in artificial saliva, the bonding resin on the enamel surfaces was removed by grinding with tungsten carbide bur at low-speed, followed by polishing with one of four different polishing systems: (a) nonfluoridated paste (NF); (b) fluoridated paste (F); (c) S-PRG filler-containing paste (S-PRG); or (d) nonfluoridated plus S-PRG filler-containing paste (NF + S-PRG) (n = 15). The polished specimens were then immersed in an artificial saliva solution for 7 days. Nanoindentation testing of enamel surfaces was performed and their mechanical properties were compared. Representative specimens were examined with scanning electron microscope. In all specimens, the mechanical properties of the enamel surfaces were markedly degraded by acid etching. However, the mechanical properties of both regions (etched and resin-infiltrated enamels) showed recovery after polishing and 7-day immersion. Polishing with NF + S-PRG paste led to significant recovery of mechanical properties compared to polishing with NF or S-PRG paste alone, and remineralization was equivalent to that seen with F paste. Porous etched enamel surfaces were filled with a remineralization layer after each polishing procedure and 7-day immersion in all polishing groups. Polishing using NF + S-PRG paste can facilitate enamel remineralization after bracket removal.

Antimicrobial Effect of Orthodontic Materials on Cariogenic Bacteria Streptococcus mutans and Lactobacillus acidophilus

BACKGROUND White spot lesions (WSLs) are a common complication after orthodontic treatment. The aim of this study was to characterize and compare the antimicrobial properties of selenium-containing vs. fluoride-containing orthodontic materials. MATERIAL AND METHODS Antibacterial efficacy of orthodontic materials (SeLECT Defense bonding agent, Adhesive agent, Band Cement, Transbond Plus SEP bonding agent, Transbond Plus Adhesive agent, Fuji I Band cement, Fuji Ortho LC Adhesive agent, Ortho Solo Bonding agent, Transbond XT bonding agent, and Transbond XT primer) was tested with the inhibition of 2 bacterial strains: S. mutans (ATCC 10449) and L. acidophilus (ATCC 4356). The antimicrobial efficacy of the materials was measured by agar diffusion test. The diameters of inhibition zones around each disk were measured in millimeters (mm). RESULTS Materials containing selenium and fluoride showed significant differences from the negative control (both p<0.001). Orthodontic materials containing fluoride as a potential antimicrobial agent showed larger zones of inhibition in total (9.1±2.6 mm), the selenium group was the second-most effective (4.7±4.9 mm), and the group without any potential antimicrobial agent showed the least antimicrobial effect (0.9±1.0 mm). Materials from the group with no antibacterial agent were not significantly different from the negative control group (p>0.05). CONCLUSIONS Materials containing selenium carried the most significance when comparing microorganisms with the agent, since they were the only ones showing difference between the 2 microorganisms. They showed statistically significant difference in efficacy against S. mutans, and poor antimicrobial effect against L. acidophilus. These data suggest that orthodontic materials containing selenium might have the potential to prevent WSLs due to their antimicrobial properties.

A comparison of antibacterial inhibitory effect on Streptococcus mutans and tensile strength between chitosan-based bonding adhesives and commercial products

Background

Adhesive bonding is the material used to attach a bracket to the enamel surface of the tooth. Streptococcus mutans contributes to enamel demineralization during orthodontic treatment.

Objectives

To analyze the antimicrobial inhibitory effect of Streptococcus mutans bacteria and tensile strength of chitosan and CaCO₃-based adhesive bonding material.

Materials and Methods

The investigation constituted laboratory experimental research featuring analytical observation and a random sampling method. The antibacterial inhibitory effect of chitosan and CaCO₃-based adhesive bonding against Streptococcus mutans involved six groups: two control groups using commercial light cure and self-cure adhesive bonding products and four groups using adhesive bonding consisting of 75% CaCO₃ + 17.6% Bis-GMA + 22.4% MMA with various percentages of chitosan composition (A1: 25%, A2: 50%, A3: 75%, and A4: 100%) each group consisting of two samples (n = 12). A diametric test was conducted consisting of three samples (n = 15) to measure the tensile strength of each group. Data were analyzed by a combination of one-way analysis of variance and least significant difference tests.

Result

The antibacterial inhibitory effect showed significant differences between groups (A1: 2.9467 ± 0.4163, A2: 3.6500 ± 0.6245, A3: 5.1267 ± 0.2517, A4: 4.7267 ± 0.9238; P = 0.0000; P < 0.05). A diametric tensile strength test confirmed significant differences between groups (A1: 7.2733 ± 5.0046, A2: 6.7667 ± 4.4346, A3: 6.4533 ± 2.9994, A4: 1.0058 ± 1.0058, K1: 15.6167 ± 3.1250; P = 0.009; P < 0.05).

Conclusion

Chitosan-based adhesive bonding with good tensile strength has an antibacterial inhibitory effect against Streptococcus mutans.

Oral probiotics reduce halitosis in patients wearing orthodontic braces: a randomized, triple-blind, placebo-controlled trial

Orthodontic braces can impede oral hygiene and promote halitosis. The aim of the study was to investigate the effect of the oral probiotic Streptococcus salivarius M18 on oral hygiene indices and halitosis in patients wearing orthodontic braces. The study was a prospective, randomized, triple-blind, placebo-controlled trial. Patients undergoing fixed orthodontic treatment were randomly allocated to a probiotic group (n = 32) and a placebo group (n = 32). Patients consumed 2 lozenges d^-1 for one month. Assessments were taken at baseline, at the end of the intervention, and at a 3 month follow-up. The outcome measures were plaque index (PI), gingival index (GI) and halitosis-causing volatile sulfur compound (VSC) levels. The dental biofilms before and after the intervention were analyzed utilizing next-generation sequencing of bacterial 16S rRNA genes. PI and GI scores were not significantly influenced by the probiotic intervention (intervention × time: p > 0.05). The level of VSCs decreased significantly in both the probiotic group (VSC reduction = -8.5%, 95%CI = -7.4% to -9.1%, p = 0.015) and the placebo group (-6.5%, 95%CI = -6.0% to -7.4%, p = 0.039) after 1 month intervention. However, at the 3 month follow-up, the VSC levels in the placebo group returned to baseline levels whereas those in the probiotic group decreased further (-10.8%, 95%CI = -10.5% to -12.9%, p = 0.005). Time, but not treatment, was associated with the decrease in microbial community alpha diversity and a modest effect on beta diversity. Oral probiotic S. salivarius M18 reduced the level of halitosis in patients with orthodontic braces, but had minimal effects on PI, GI and dental biofilm microflora.

Prevention of white spot lesions using three remineralizing agents: An in vitro comparative study

Background. Enamel demineralization around orthodontic brackets is an important clinical problem. This study sought to compare the efficacy of sodium fluoride (NaF), casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACP-F; MI Paste Plus) and a water-based cream (Remin Pro), which contains hydroxyapatite and fluoride for prevention of enamel demineralization.

Methods. Fifty-six sound human premolars extracted for orthodontic purposes were collected. After cleaning, the crowns were mounted in acrylic resin and all the surfaces were coated with nail varnish except for a 3×4-mm window on the buccal surface. The samples were randomly divided into four groups of 14 and subjected to pH cycling for 14 days, during which the teeth were immersed in artificial saliva for 21 hours and in demineralizing agent for three hours daily. Before transferring the samples from the saliva to the demineralizing solution, the remineralizing agent (0.05% NaF, MI Paste Plus or Remin Pro Paste, depending on the group) was applied on the samples once a day for five minutes. No remineralizing agent was used in the control group. Surface microhardness of samples was measured by Vickers microhardness tester at baseline and after the intervention. The data were analyzed using one-way ANOVA, ANCOVA, Bonferroni test and Tukey test. Statistical significance was set at P<0.05.

Results. The mean microhardness was significantly different between the test and control groups (P<0.0001). Other differences were not significantly different (P>0.05).

Conclusion. The results showed that 0.05% NaF was more efficient than Remin Pro and MI Paste Plus for prevention of white spot lesions (WSLs). Remin Pro and MI Paste Plus were not significantly difference from the control group in this regard.

Anti-demineralization effect of desensitizer containing copolymer and sodium fluoride on root dentin - a transverse microradiographic study

Objective: To evaluate anti-demineralization effects of dentin desensitizer containing sodium fluoride and methacrylate-co-p-styrene sulfonic acid (MS polymer) on root dentin using transverse microradiography (TMR).

Material and methods: Twenty-four dentin specimens were divided into four groups: MSO (no fluoride), MSF (3000 ppm F), FJL (9000 ppm F), and Control. In MSO and MSF, each desensitizer was rubbed into the dentin surfaces for 10 s then left for 20 s. In FJL, paste containing 9000 ppm F was applied onto the surface for 30 s. All specimens, including the Controls, were rinsed with deionized water, dried and an area of their surface exposed to pH 5.0 acidic solution, refreshed every 24 h, for 4 days. Sections 300-µm-thick were assessed by TMR. Mineral profiles and integrated mineral loss (IML) of lesions were analyzed by dedicated software. IML was analyzed with one-way ANOVA and Tukey’s test.

Results: MSF and FJL specimens showed high mineral volume % at the surface and in lesions, and significantly lower IML than the other groups (p < .05).

Conclusion: Dentin desensitizer containing 3000 ppm fluoride and MS polymer has the same anti-demineralization effect as does a fluoride paste containing 9000 ppm F.

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.

Enamel Demineralization Adjacent to Orthodontic Brackets Bonded with ACTIVA BioACTIVE-RESTORATIVE

Introduction

Enamel demineralization adjacent to orthodontic brackets has been shown to be a consequence during orthodontic treatment. Fluoride-releasing resin-modified glass ionomer cements (RMGICs) have been shown to protect the enamel from white spot lesions, but their bond strength has been proven inadequate. The purpose of this study was to evaluate ACTIVA BioACTIVE-RESTORATIVE, a bioactive material with strength superior to RMGICs, for inhibition of enamel demineralization surrounding orthodontic brackets.

Materials and Methods

Fifteen human teeth were sectioned and divided into two groups. One group was the control and had orthodontic brackets bonded with Transbond XT, while the second group had orthodontic brackets bonded with ACTIVA. The teeth were varnished within 2 mm of the bracket margins and immersed in an artificial caries solution for 3 days to create carious lesions. The teeth were sectioned and viewed under polarized light microscopy for the detection of enamel demineralization adjacent to the bracket, and then, the lesion areas were measured with a computer imaging system.

Results

There was a statistically significant difference (P≤ 0.001) that ACTIVA had less enamel demineralization adjacent to the bracket when compared to the control group.

Conclusions

The results of this study have demonstrated that ACTIVA, a fluoride-releasing bioactive restorative material, inhibits demineralization of enamel adjacent to orthodontic brackets when compared to a nonfluoride-releasing control.

Effect of CPP-ACP paste with and without CO2 laser irradiation on demineralized enamel microhardness and bracket shear bond strength

Introduction:

Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments. The aim of this in vitro study was to evaluate the effect of CPP-ACP paste and CO₂ laser irradiation on demineralized enamel microhardness and shear bond strength of orthodontic brackets.

Methods:

Eighty caries-free human premolars were subjected to a demineralization challenge using Streptococcus mutans. After demineralization, the samples were randomly divided into five equal experimental groups: Group 1 (control), the brackets were bonded without any surface treatment; Group 2, the enamel surfaces were treated with CPP-ACP paste for 4 minutes before bonding; Group 3, the teeth were irradiated with CO₂ laser beams at a wavelength of 10.6 µm for 20 seconds. The samples in Groups 4 and 5 were treated with CO₂ laser either before or through CPP-ACP application. SEM photomicrographs of a tooth from each group were taken to observe the enamel surface. The brackets were bonded to the buccal enamel using a conventional method. Shear bond strength of brackets and ARI scores were measured. Vickers microhardness was measured on the non-bonded enamel surface. Data were analyzed with ANOVA and Tukey test at the p< 0.05 level.

Results:

The mean shear bond strength and microhardness of the laser group were higher than those in the control group and this difference was statistically significant (p< 0.05). All groups showed a higher percentage of ARI score 4.

Conclusion:

CO₂ laser at a wavelength of 10.6 µm significantly increased demineralized enamel microhardness and enhanced bonding to demineralized enamel.

Influence of CO2 Laser Irradiation and CPPACP Paste Application on Demineralized Enamel Microhardness

Introduction: It has been suggested that the application of casein phosphopeptide-amorphous calcium phosphate paste (CPP-ACP) and CO2 laser irradiation on enamel could increase the resistance of enamel to caries and acid attacks. The aim of the current study was to compare the influence of CPP-ACP paste application and irradiation of CO2 laser on microhardness of demineralized enamel. Methods: Thirty sound maxillary extracted premolars were selected. The crowns were cut at the cervical line and were split into facial and palatal halves. Specimens were mounted in selfcure acrylic blocks in such way that the enamel surface was exposed to 4×4 mm. After a pH cycling of the specimens, they were randomly divided into 4 groups (n=15), as follows: CG: Control group, LAS: CO2 laser, CP: CPP-ACP and LASCP: laser combined CPP-ACP treatment. The Vickers microhardness of the specimens was measured (500 g load, 5 seconds, 3 points). Data were analyzed using one-way ANOVA and post hoc Tukey tests (α =0.05). Results: The lowest mean Vickers microhardness value was observed in CG group (192.57±50.87 kg/mm2 ) and the highest in LASCP group (361.86±22.22 kg/mm² ). There were significant differences between groups (P<0.001). The pairwise comparison of the groups revealed that there were significant differences between these groups: CG versus LAS, CP, LASCP (P<0.05) and LASCP versus LAS and CP (P<0.05). No significant difference between LAS group versus CP group (P>0.05) was observed. Conclusion: The results of the current study revealed that CO2 laser and CCP-ACP were effective for improvement of enamel hardness value after demineralization. Incorporation of CO2 laser irradiation and CCP-ACP paste application provides additional remineralizing potential for demineralized enamel.

The effect of fluoride varnish in preventing enamel demineralization around and under orthodontic bracket

AIM

The aim of this study was to evaluate in vitro the effectiveness of fluoride Vanish™ in preventing enamel demineralization around and under orthodontic brackets, using a laser fluorescence monitoring device on a group of teeth, using a laser fluorescence monitoring device on a group of extracted teeth with bonded brackets.

METHODS

Orthodontic brackets were bonded to 32 extracted premolars. Buccal surfaces of teeth were divided into two halves: mesial and distal, fluoride Vanish™ (3M Unitek, Monrovia, CA, USA) was applied only on the distal half while the mesial one served as control half. Teeth were subjected to two demineralization cycles in standard demineralization solution. Enamel demineralization was measured on both varnished and non-varnished halves at baseline, after first and second demineralization cycles and under the brackets after debonding using laser fluorescence device Diagnodent pen. Data were analyzed using Friedman test followed by Wilcoxon test. Differences were considered statistically significant at P<0.001.

RESULTS

Statistically significant differences were observed between the varnished and non-varnished halves after the first and second demineralization cycles at P<0.001. No significant difference was found between baseline readings and under the brackets in both halves.

CONCLUSION

Fluoride varnish application is effective in preventing enamel demineralization around orthodontic brackets. Fluoride varnish has insignificant effect on enamel mineral content under orthodontic brackets.

Effect of CO2 Laser and Fluoride Varnish Application on Microhardness of Enamel Surface Around Orthodontic Brackets

Introduction: Orthodontic treatment has many advantages such as esthetic improvement and self-esteem enhancement; yet it has some disadvantages such as increasing the risk of formation of white spot lesions, because it makes oral hygiene more difficult. It is rational to implement procedures to prevent these lesions. The present study was aimed to assess the effect of CO₂ laser and fluoride varnish on the surface of the enamel surface microhardness around the orthodontic braces. Methods: Eighty extracted premolar teeth were selected, scaled, polished with nonfluoridated pumic and metal brackets were bonded to them. Then, they were randomly allocated to 5 groups: control (neither fluoride nor laser is used on enamel surfaces), fluoride (4 minutes fluoride varnish treatment of the enamel surfaces), CO₂ laser (10.6 µm CO₂ laser irradiation of the teeth), laserfluoride (fluoride application after laser irradiation) and fluoride-laser (fluoride was applied and then teeth were irradiated with laser). After surface treatment around brackets on enamel, the samples were stored in 0.1% thymol for less than 5 days and then they were exposed to a 10-day microbiological caries model. Microhardness values of enamel were evaluated with Vickers test. One sample of each group (5 teeth from 80 samples) was prepared for SEM (scanning electron microscopy) and the data from 75 remaining teeth were analyzed with analysis of variance (ANOVA) and chi-square tests (α =0.05). Results: Microhardness mean values from high to low were as follow: fluoride-laser, laser-fluoride, laser, fluoride and control. Microhardness in fluoride-laser group was significantly higher compared with that of the control group. Distribution adhesive remnant index (ARI) scores were significantly different between groups and most of bond failures occurred at the enamel-adhesive interface in groups 2 to 5 and at the adhesive-bracket interface in the control group. Conclusion: Combination of fluoride varnish and CO2 laser irradiation can reduce enamel demineralization around orthodontic brackets.

Effects of toothpastes on white spot lesions around orthodontic brackets using quantitative light-induced fluorescence (QLF) : An in vitro study

AIM

The aim of this study was to investigate the effects of toothpastes with different contents on the remineralization of white spot lesions around orthodontic brackets by quantitative light-induced fluorescence (QLF).

MATERIALS AND METHODS

A total of 45 freshly extracted human mandibular first molars were selected. Artificial caries lesions were created on enamel surfaces using an acidified gel system for 7 days. Initial relative fluorescence loss was calculated as the pretreatment (baseline) fluorescence value by QLF device. Molar tubes were bonded using light-cured resin composite cement. The specimens were randomly divided into three experimental groups (n = 15). Different toothpastes were applied to demineralized enamel: (1) fluoride-containing toothpaste (Colgate Total^®), (2) Novamin-containing toothpaste (Sensodyne^® Repair and Protect), (3) probiotic-containing toothpaste (GD Probiotic Toothpaste^®). After 2 weeks of treatment, fluorescence loss and lesion area were measured with QLF. To determine fluorescence changes, intergroup comparisons were performed with a multivariate analysis of variance, followed by Tukey's test at a probability value of p < 0.05.

RESULTS

Significant differences were observed between initial and posttreatment QLF measurements of the demineralized enamel specimens treated with the various agents (p < 0.05). In all experimental groups, significant fluorescence radiance increase and decrease of the lesion area (p = 0.000) was found.

CONCLUSION

Novamin-containing toothpaste provided more increase of fluorescence compared to fluoride- and probiotic-containing toothpastes.

Remineralizing potential of a 60-s in vitro application of Tooth Mousse Plus

BACKGROUND

No published studies exist on the remineralizing potential of Tooth Mousse Plus^® (TMP) when applied for less than 3 min.

AIM

To evaluate (i) the remineralizing potential of TMP on artificial carious lesions, when applied thrice daily for 60 s, and (ii) the benefit of using a fluoridated dentifrice prior to TMP application.

DESIGN

Carious lesions, 120-200 μm deep, were produced by placing molars in demineralizing solution for 96 h, and sections 100-150 μm thick were then randomly assigned to four groups. Specimens were treated thrice daily with a non-fluoridated (Group A), or 1000 ppm F dentifrice (Group B), or TMP (Group C), or a 1000 ppm F dentifrice followed by TMP application (Group D), and then subjected to a 10-day pH cycling model. Lesion evaluation involved polarizing light microscopy and microradiography.

RESULTS

Post-treatment maximum mineral content at the surface zone (V_max ) was significantly increased and lesion depth (LD) significantly decreased in Group C, while only the V_max increased in Group D. Increase in LD was observed in Group B; however, no significant differences were noted in percentage LD changes between groups B, C, and D (P > 0.05).

CONCLUSIONS

TMP applied for 60 s significantly remineralized the artificial carious lesions. No additional benefit was evident when TMP was preceded by treatment with 1000 ppm F dentifrice.

The effect of fluoride-containing oral rinses on the corrosion resistance of titanium alloy (Ti-6Al-4V)

OBJECTIVE

The purpose of this study was to examine the effect of commercially available fluoride-containing oral rinses on the corrosion behavior of titanium alloys, which are the main components of orthodontic miniscrews.

METHODS

Four commercially available oral rinses (solution A, pH 4.46/260 ppm fluoride; solution B, pH 4.41/178 ppm fluoride; solution C, pH 6.30/117 ppm fluoride; and solution D, pH 4.17/3.92 ppm fluoride) were tested on titanium alloy (Ti-6Al-4V) circular plates, and saline was used as the control. The open-circuit potential and potentiodynamic polarization of these materials were measured. Thereafter, all samples were evaluated under a field-emission scanning electron microscope.

RESULTS

Among the tested oral rinses, except solution D, the more the fluoride content was, the greater was the corrosion potential downtrend; the corrosion resistance of the titanium alloy sample was also lowered significantly (p < 0.05). Field-emission scanning electron microscopic analysis of the surface morphology of the titanium alloy samples revealed that all samples had some defects, crevices, or pitting after exposure to the oral rinses than before treatment. In particular, the samples in solution A showed the most changes.

CONCLUSIONS

Commercially available oral rinses having a high fluoride concentration and a low pH may reduce the corrosion resistance of titanium alloys used in dental appliances such as orthodontic titanium miniscrews and brackets.

The effects of single application of pastes containing ion-releasing particles on enamel demineralization

We investigated single application of pastes containing a surface reaction-type pre-reacted glass-ionomer (S-PRG) filler on enamel demineralization. Human enamel blocks were polished using pastes containing S-PRG filler (0, 5, and 30%) and immersed in demineralizing solution for 5 days with daily change of solutions. The pH measurement and nanoindentation testing was carried out during the immersion period, and the enamel surfaces were examined using scanning electron microscopy and atomic force microscopy. A non-fluoride paste and a hydroxyapatite-containing paste were used for comparison. The specimens polished with the S-PRG filler-containing paste exhibited acid-neutralizing properties, which became stronger with an increasing S-PRG filler content. Following immersion in the demineralizing solution, specimens polished with the S-PRG filler-containing paste exhibited significantly greater hardness and elastic modulus values than those polished with the other pastes and exhibited a smoother surface than did the other specimens. Pastes containing S-PRG filler inhibits the demineralization of enamel.

Novel multifunctional dental cement to prevent enamel demineralization near orthodontic brackets

OBJECTIVES

White spot lesions due to biofilm acid-induced enamel demineralization are prevalent in orthodontic treatments. The aim of this study was to develop a novel bioactive multifunctional cement with protein-repellent, antibacterial and remineralizing capabilities, and investigate the effects on enamel hardness and lesion depth in vitro for the first time.

MATERIALS AND METHODS

2-Methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM), and nanoparticles of amorphous calcium phosphate (NACP) were incorporated into a resin-modified glass ionomer (RMGI). Extracted human premolars had brackets bonded via four groups: (1) Transbond XT (TB), (2) RMGI (GC Ortho LC), (3) RMGI+MPC+DMAHDM, (4) RMGI+MPC+DMAHDM+NACP. Demineralization was induced via a dental plaque microcosm biofilm model. Samples were tested using polarized light microscopy (PLM) for lesion depth. Enamel hardness was tested for different groups.

RESULTS

Incorporating MPC, DMAHDM and NACP did not affect enamel bond strength. "RMGI+MPC+DMAHDM+NACP" group had the least lesion depth in enamel (p<0.05). Groups with NACP had the highest enamel hardness (p<0.05). Mineral loss (ΔS) in enamel for NACP group was about one third that for RMGI control. "RMGI+MPC+DMAHDM" had greater effect on demineralization-inhibition, compared to RMGI and TB controls. "RMGI+MPC+DMAHDM+NACP" was more effective in protecting enamel prisms from dissolution by biofilm acids, compared to RMGI and TB control groups.

CONCLUSION

The Novel "RMGI+MPC+DMAHDM+NACP" cement substantially reduced enamel demineralization adjacent to orthodontic brackets, yielding much less lesion depth and greater enamel hardness under biofilm acid attacks than commercial controls. The clinical significance is that the novel multi-agent (RMGI+MPC+DMAHDM+NACP) method is promising for a wide range of preventive and restorative applications to combat caries.

Prevention of Enamel Adjacent to Bracket Demineralization Following Carbon Dioxide Laser Radiation and Titanium Tetra Fluoride Solution Treatment: An In Vitro Study

Introduction: The aim of this study was to assess the caries-preventive potential of carbon dioxide (CO₂) laser application in conjunction with the use of titanium tetra fluoride solution on the enamel adjacent to bracket. Methods: Seventy-five freshly extracted bovine incisors were used. In order to attach the brackets, the area of examination was covered with adhesive tape to limit acid etching of the entire enamel surface. Metal orthodontic brackets for upper central were bonded to all the teeth following the manufacturer's instruction. Then all the teeth were painted with 2 layers of acid-resistant nail varnish on all surfaces except the boxes area cervical to the brackets. The teeth were then randomly divided into five groups (n = 15): control group (C); laser group (L); titanium group (T); laser-titanium group (LT) and titanium-laser group (TL). The laser-titanium group was first irradiated with CO₂ laser (same as the L group) then TiF4 solution was applied on the enamel (same as the T group). Samples in the TL group were first treated with TiF4 solution (same as the T group) and then irradiated with CO₂ laser on the surface (same as the L group). Then, the teeth were immersed in pH-cycling solutions. After that, the amount of calcium released into the two solutions (de- and re-mineralization) was measured with an atomic absorption spectroscopy. The data were analyzed by one-way Analysis of var-iance (ANOVA) and Tukey test. Results: Calcium loss in LT, TL and T groups were significantly lower than those in the L and C groups (P < 0.05). Conclusion: The application of Titanium tetra fluoride 4% solution on enamel can inhibit as much as 87% of subsequent caries like lesion progression.

Biofilm formation in Haas palatal expanders with and without use of an antimicrobial agent: an in situ study

Orthodontic appliances causes specific alterations in oral environment, including reduction of pH, increase of dental biofilm and elevation of salivary microbial levels, causing an increased risk for dental caries. This study evaluated, using microbial culture and scanning electron microscopy (SEM), the in situ contamination by mutans streptococci (MS) of different surfaces of Haas palatal expanders with and without use of chlorhexidine gluconate mouthrinses (CHX). Thirty-four patients were randomly assigned to two groups (n = 17/group), using placebo (Group I) and 0.12% CHX (Group II-Periogard^® ) mouthrinses twice a week. After 4 months, appliances were submitted to microbiological processing and after fragments were analyzed by SEM. Mann-Whitney U test (α = 5%) was used to assess differences between groups on the appliances' different surfaces and to compare the contamination on the free and nonfree surfaces of these components. There was no difference (p = 0.999) between groups regarding the number of MS colonies/biofilms on the nonfree surfaces, which showed intense contamination. However, free surfaces of Group II presented less contamination (p < 0.001) than those of Group I in all appliances' components. Results of the microbial culture were confirmed by SEM. Use of 0.12% CHX was effective in reducing the formation of MS colonies/biofilms on free surfaces of Haas expanders, in situ.

Release of fluoride from orthodontic adhesives and penetration into enamel

OBJECTIVE

The purpose of this work was to compare fluoride release from three orthodontic adhesives and fluoride penetration into the enamel surface.

MATERIALS AND METHODS

A total of 156 extracted human premolar teeth were randomly assigned to three experimental groups and one control group (without bonding) with 39 teeth per group. Brackets were bonded to teeth using Fuji Ortho LC^®, Illuminate^®, or Light Bond^®. The amount of fluoride released (ppm) into artificial saliva was measured by a fluoride ion-selective electrode connected to an ion analyzer on days 1, 3, 7, and 30. Fluoride penetration was investigated after 1, 2, and 3 months; 13 teeth of each group were randomly selected at every period of study and sectioned across the center of the bracket. The surface of the cross-section was studied under the scanning electron microscope, and the fluoride concentration (weight%) at 1, 2, and 3 µm below the outer enamel surface was determined by energy-dispersive X-ray microanalysis.

RESULTS

On days 1, 3, 7, and 30, the mean cumulative fluoride release from the three orthodontic adhesives were significantly different (p < 0.05). Illuminate^® released the greatest fluoride, followed by Fuji Ortho LC^® and Light Bond^®. After 1, 2, and 3 months, fluoride penetration into enamel was only found from Fuji Ortho LC^®. The fluoride concentration decreased with depth but there were no significant differences (p > 0.05) over time at all depths.

CONCLUSIONS

The in vitro study indicated that fluoride release is a common property of the three fluoride-releasing orthodontic adhesives: Illuminate^®, Fuji Ortho LC^®, and Light Bond^®. However, detectable fluoride penetration is a specific property of Fuji Ortho LC^®. Further clinical studies should be undertaken to investigate the benefit of the two adhesives Illuminate^® and Fuji Ortho LC^® on protection of enamel demineralization.

Comparative evaluation of the efficacy of fluoride varnish and casein phosphopeptide - Amorphous calcium phosphate in reducing Streptococcus mutans counts in dental plaque of children: An in vivo study

AIM

To assess the comparative efficacy of fluoride varnish and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) complex visa viz. Streptococcus mutans in plaque, and thereby the role that these two agents could play in the prevention of dental caries.

MATERIALS AND METHODS

A cluster sample of 120 caries inactive individuals belonging to moderate and high caries risk group were selected from 3-5-year-old age group based on the criteria given by Krassee and were randomized to four groups, namely, fluoride varnish - Group I, CPP-ACP complex - Group II, mixture of CPP-ACP complex -Gourp III, and fluoride and routine oral hygiene procedures as control - Group IV. The results thus obtained were analyzed using Statistical Package for the Social Sciences (SPSS) version 16.

RESULTS

A statistically significant difference in the pre and post-application scores of S. mutans (P < 0.01) count was observed in all the groups with CPP-ACP plus fluoride group being the most proficient.

CONCLUSION

Materials such as fluoride varnish, CPP-ACP, and CPP-ACP plus fluoride protects the tooth structure, preserving the integrity of primary dentition, with the most encouraging results being with CPP-ACP plus fluoride.

Deproteinization of tooth enamel surfaces to prevent white spot lesions and bracket bond failure: A revolution in orthodontic bonding

Orthodontic treatment success is jeopardized by the risk of development of white spot lesions (WSLs) around orthodontic brackets. Unfortunately, the formation of WSLs still remains a common complication during treatment in patients with poor oral hygiene. Nearly 75% of orthodontic patients are reported to develop enamel decalcification because of prolonged plaque retention around brackets. It is the orthodontist’s responsibility to minimize the risk of patients having enamel decalcifications as a consequence of orthodontic treatment. This can be achieved by using hybrid, fluoride-releasing, glass ionomer cement to bond brackets, with deproteinization of the enamel surface before phosphoric acid etching.

Remineralizing potential of CPP-ACP creams with and without fluoride in artificial enamel lesions

BACKGROUND

This study evaluated the effect of pastes containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) with and without fluoride on enamel demineralization.

METHODS

Human enamel blocks were used and after incipient caries-like lesions were formed, they were assigned to four groups: G1 - saliva; G2 - MI Paste (Recaldent^TM ); G3 - MI Paste Plus (Recaldent^TM 900 ppm as NaF); and G4 - Crest^™ (1.100 ppm as NaF). The specimens were soaked in demineralizing solution for 6 hours and remineralized in artificial saliva for 18 hours alternatively for 10 days. The dentifrice was prepared with deionized water in a 1:3 proportion (w/w) or applied undiluted in the case of the CPP-ACP formula. Demineralized enamel changes were analysed by surface microhardness (SMH), 3D-profilometry and SEM. Data were analysed by non-parametric Kruskal-Wallis and Mann-Whitney test comparisons and one-way ANOVA and Tukey's HSD post hoc test (α = 0.05).

RESULTS

The SMH values observed in the G2 (47.8 ± 28.5) and G3 (53.6 ± 27.6) groups were different from that of G4 (90.2 ± 17.1), which were significantly higher than that found in G1 (39.4 ± 14.2). The %SMH was significantly lower in G4 when compared to G1 (p < 0.001) and G3 (p < 0.05).

CONCLUSIONS

MI Paste Plus demonstrated a greater protective effect against demineralization than MI Paste and showed smoother surfaces.

Crystal growth on bioactive glass sputter-coated alumina in artificial saliva

In this work, a bioactive glass was deposited on the alumina disk specimens by radio-frequency magnetron sputtering to study crystal formation ability in artificial saliva. Bioactive glass-coated specimens were immersed in artificial saliva for 1 week and 6 months. The specimens were observed with a scanning electron microscope (SEM) and the composition was determined by energy dispersive spectroscopy (EDS). The crystals that formed on the specimens were analyzed by Raman spectroscopic analysis and Micro-X-ray diffraction. SEM photomicrographs showed the formation of needle-like structures after immersion for 1 week, and tabular structures formed on the surface of the specimen for 6 months. EDS showed that both the needle-like and tabular structures were enriched with Ca and P. Raman and Micro-XRD spectra for the tabular structure showed peaks that may correspond to calcium phosphate. Thus, when immersed in artificial saliva, bioactive glass-coated alumina produced a crystal which might be calcium phosphate.

Effects of CO2 laser irradiation combined with fluoride application on the demineralization, mechanical properties, structure, and composition of enamel

We investigated the effects of CO2 laser irradiation combined with acidulated phosphate fluoride (APF) application on the demineralization of enamel. APF gel was applied to the buccal enamel of human premolars and CO2 laser was applied. After the specimens were immersed in demineralization solution for 72 h, they were subjected to depth-dependent micro-CT and nanoindentation analyses. Micro-X-ray diffraction and X-ray photoelectron spectroscopy were performed to analyze the surfaces. Some surface regions of the enamel in specimens that were laser-irradiated with low output and APF-treated showed significantly higher values of MD and hardness than specimens treated with APF alone. A higher fluoride concentration in the enamel surface was observed in specimens treated with CO2 laser irradiation plus APF gel application. In conclusion, CO2 laser irradiation with low output is preferable to improve acid resistance.

Effects of different pre-treatment methods on the shear bond strength of orthodontic brackets to demineralized enamel

OBJECTIVE

To compare the effects of different treatment methods used for the enamel damage, on the shear bond strength (SBS) and fracture mode of orthodontic brackets.

MATERIALS AND METHODS

Freshly-extracted 140 premolars were randomly allocated to seven groups: Group I was considered as the control of other groups. The remaining groups were exposed to demineralization. In group II, brackets were directly bonded to the demineralized enamel surface. CPP-ACP paste (GC Tooth Mousse), fluoride varnish (Bifluorid 12), microabrasion with a mixture prepared with 18% hydrochloric acid and fine pumice powder, microabrasion with an agent (Opalustre) and resin infiltrant (Icon®) were applied in Groups III, IV, V, VI and VII, respectively. The specimens were tested for SBS and bond failures were scored according to the Adhesive Remnant Index (ARI). Analysis of variance and Tukey tests were used to compare the SBS of the groups. ARI scores were compared with G-test. The statistical significance was set at p < 0.05 level.

RESULTS

Statistically significant differences were found among seven groups (F = 191.697; p < 0.001). The SBSs of groups I (mean = 18.8 ± 2.0 MPa) and VII (mean = 19.1 ± 1.4 MPa) were significantly higher than the other groups. No statistically significant difference was found between groups IV (mean = 11.5 ± 1.2 MPa) and V (mean = 12.6 ± 1.5 MPa). The differences in ARI scores of the groups were statistically significant (p < 0.01).

CONCLUSIONS

All demineralization treatment methods improve bonding to demineralized enamel. Resin infiltrant application after demineralization showed similar bond strength values as intact enamel.

The effect of recommending a CPP-ACPF product on salivary and plaque pH levels in orthodontic patients: a randomized cross-over clinical trial

OBJECTIVE

Along with their re-mineralizing capacity, calcium phosphopeptide-amorphous calcium phosphate products combined with fluoride (CPP-ACPF) could also be beneficial by neutralizing acidic salivary and plaque pH. The purpose was to evaluate the effect of CPP-ACPF on salivary and plaque pH in orthodontic patients.

MATERIALS AND METHODS

As a triple-blind, cross-over randomized trial, 30 orthodontic patients with fixed appliances (age range = 15.70 ± 4.08 years) were recruited and randomly assigned to two groups. A CPP-ACPF paste (MI Paste Plus, GC America, Alsip, IL) was used by group 1 (n = 15) and a placebo by group 2 (n = 15) for 1 month. After a 1 month washout period, patients used the alternative paste for another month. Plaque and salivary pH levels were measured at all before and after periods.

RESULTS

By applying MI Paste Plus, the plaque pH increased from 5.81 ± 0.45 to 6.60 ± 0.38 (p < 0.05), whereas the before and after salivary pH recordings, which were 6.72 ± 0.43 and 6.71 ± 0.38, respectively, remained statistically unchanged (p > 0.05).

CONCLUSION

MI Paste Plus can be clinically beneficial in increasing plaque pH levels, but has no effect on the salivary pH.

Nanoparticles in orthodontics, a review of antimicrobial and anti-caries applications

Nanoparticles (NPs) are insoluble particles smaller than 100 nm in size. In order to prevent microbial adhesion or enamel demineralization in orthodontic therapy, two broad strategies have been used. These are incorporating certain NPs into orthodontic adhesives/cements or acrylic resins (nanofillers, silver, TiO2, SiO2, hydroxyapatite, fluorapatite, fluorohydroxyapatite) and coating surfaces of orthodontic appliances with NPs (i.e. coating bracket surfaces with a thin film of nitrogen-doped TiO2). Although the use of NPs in orthodontics can offer new possibilities, previous studies investigated the antimicrobial or physical characteristic over a short time span, i.e. 24 hours to a few weeks, and the limitations of in vitro studies should be recognized. Information on the long-term performance of orthodontic material using nanotechnology is lacking and necessitates further investigation and so do possible safety issues (toxicity), which can be related to the NP sizes.

Does acid etching enhance remineralisation of arrested white spot lesions?

AIM

To investigate the effect of acid etching procedure on the remineralisation of white spot lesions (WSL) which had undergone an initial phase of arrest, and to compare between the effect of fluoride and/or CPP-ACP on remineralisation before and after acid etching.

STUDY DESIGN

In vitro study.

METHODS

WSL were prepared in vitro on 130 human enamel slabs which were allocated into four experimental groups (N = 30) and one control group (N = 10). Changes in mineral content were registered weekly by Quantitative Light Induced Fluorescence QLF. When changes had arrested (after 8 weeks), the enamel surface of 20 slabs in each group were acid etched. The remineralisation process was continued until it slowed down again (after 5 weeks).

RESULTS

Mean fluorescence gain was 13.7 ± 0.9% in the fluoride group, 16.5 ± 1.1% in the CPP-ACP group, and 11.4 ± 1.2% in the combination of fluoride and CPP-ACP group.

CONCLUSIONS

There was a tendency toward better remineralisation after acid etching but this did not reach a significant level; the effect of etching was more pronounced in the presence of fluoride. Although CPP-ACP seemed to give a steadier rate of remineralisation over time when compared with fluoride, the overall remineralisation in the regimens was similar. In this model, combined treatment of fluoride and CPP-ACP did not have an extra benefit over the fluoride or CPP-ACP alone.

The effect of zinc-carbonate hydroxyapatite versus fluoride on enamel surfaces after interproximal reduction

The aim of this study was to qualitatively investigate the effects of a zinc-carbonate hydroxyapatite (Zn-CHA) containing toothpaste on stripped enamel morphology in a pH cycling model in vitro and to compare the efficacy of this toothpaste versus fluoride one which still represent the gold standard to remineralize early enamel lesions. Twenty-one extracted lower incisors underwent to interproximal enamel reduction with metal strips (Horico 80 µm) on both mesial and distal surfaces. They were then sliced into mesial and distal halves and the 42 samples obtained were randomly assigned to 3 groups of 14 enamel specimens each. For 8 days, teeth were placed in lactic acid solution for 2 h three times a day with 2 h distilled water preservation in between. After each demineralization bath, samples of Group A were brushed with Zn-CHA containing toothpaste while samples of Group B were brushed with 1,400 ppm fluoride dentifrice for 5 min before immersion into water. Group C of untreated samples served as control. All the samples were then prepared for scanning electron microscopy (SEM) analysis. A score rating system was used to perform a non-parametric statistical analysis. No statistically significant differences were found between the samples brushed with fluoride toothpaste and those untreated (Groups B and C) where the highest grade of damage was found, while the lowest grade was recorded in the samples brushed with Zn-CHA (Group A) and there was a statistically significant difference between this group and the other two groups.

Influence of fluoride-containing acidic artificial saliva on the mechanical properties of Nickel-Titanium orthodontics wires

OBJECTIVE

This study aimed to investigate the influence of fluoride and an acidic environment on the mechanical properties of NiTi orthodontic wires (NiTiW) in artificial saliva.

DESIGN

A prospective laboratory investigation.

SETTING

Department of Stomatology, First Affiliated Hospital, Zhejiang University, Hangzhou, China.

MATERIALS AND METHODS

Commercial, round 0.016-inch NiTiW were immersed in 0% or 0.05% Natrium-Fluoride-containing artificial saliva at a pH of 4 or 6 for one or three days, respectively. NiTiW were examined with a three-point bending test, Vickers' microhardness tests and surface morphology observation (SEM).

RESULTS

A pH of 4 increased microhardness and decreased the three-point bending strength significantly (P≤0.05), whereas immersion time and fluoride concentration had no significant influence on the microhardness or on the three-point bending strength (P>0.05). When examining the test group NiTiWs after three days of immersion at a pH of 4 the SEM revealed a rough surface morphology, a damaged oxide layer and signs of corrosion.

CONCLUSIONS

The most influential factor for decreasing the unloading force and increasing the hardness seems to be the pH value, whereas immersion time and NaF addition do not have a major influence.