In vivo effect of a resin-modified glass ionomer cement on enamel demineralization around orthodontic brackets

Fluoride exchange by glass-ionomer dental cements and its clinical effects: a review

The topic of fluoride release and uptake by glass-ionomer (glass polyalkenoate) dental cements is reviewed. The study was based on a literature search carried out using PubMed. The main key words used were glass-ionomer and fluoride, and further refinements were made by adding the keywords anti-microbial, anti-caries and remineralization. Papers were selected from the initial search, which concentrated on fundamental aspects of fluoride release, including kinetics and the influence of the cement composition, and resulting clinical performance against caries. Other relevant papers were cited where they added useful and relevant data. From these published papers, it was possible to explain the detailed mechanism of fluoride release by glass-ionomer cements and also its uptake. Fluoride release has been shown to be a two-step process. In neutral solutions, the steps can be divided into early wash-out and long-term diffusion. In acid conditions, the early wash-out remains, though with greater amounts of fluoride released, and the long-term release becomes one of slow dissolution. The effect of fluoride on the viability of oral micro-organisms has been described, and glass-ionomers have been shown to release sufficient fluoride to reduce the size and viability of adjacent populations of oral bacteria. The effect of low levels of fluoride on the remineralization of tooth tissue has been considered. Levels needed to increase remineralization are much lower than those needed to adversely affect oral bacteria, from which we conclude that glass-ionomers release sufficient fluoride to promote remineralization. Despite this, there remains uncertainty about their overall contribution to sound oral health, given the widespread use of other sources of fluoride, such as toothpastes.

Bonding durability and remineralizing efficiency of orthodontic adhesive containing titanium tetrafluoride: an invitro study

BACKGROUND

Titanium tetrafluoride has been shown to protect tooth enamel from demineralization. This study investigated the effect of incorporating different concentrations of TiF4 (1, 2 and 3 Wt.%) into an orthodontic primer on the shear bond strength of orthodontic brackets and the enamel microhardness after cariogenic challenges.

METHODS

Three different TiF4 concentrations (1, 2 and 3 Wt.%) were prepared and added to the etch and rinse orthodontic primer. Ninety freshly extracted premolars were randomly divided into five groups according to the experimental primers and ageing conditions: TF0, TF0C, TF1C, TF2C, and TF3C. The TF0C group had no TiF4 in the primer, while TF1C, TF2C, and TF3C had 1, 2 and 3 Wt.% TiF4 in the primer, respectively. In the TF0 group, specimens were immersed in deionized water for 24 h as a control group, while all other groups were immersed in a demineralizing solution for 28 days. Each of the five groups was divided into two subgroups: The first group was subjected to shear bond strength and adhesive remnant index testing (N = 50 teeth, 10/group), while the second group was subjected to enamel surface microhardness testing (N = 25 teeth, 50 tooth halves, 10 tooth halves/group). Fifteen teeth (N = 15 teeth, n = 3/group) representing the five groups were subjected to SEM and microelemental analysis (EDX). SBS, ARI, microhardness, and Ca/P ratio were measured, and the data were analyzed using ANOVA and Tukey's tests.

RESULTS

The TF2C group had the highest SBS value (9.93 ± 1.23), while the TF0C (5.24 ± 0.65) and TF3C (5.13 ± 0.55) had the lowest SBS values. The enamel microhardness in the TF0C group was significantly reduced (p < .001). Enamel microhardness values were significantly (p < .001) higher in groups TF1C, TF2C, and TF3C than in TF0C. The highest Ca/P ratio was significantly recorded for the TF2C group (2.65 ± 0.02).

CONCLUSIONS

Incorporation of 1 and 2 Wt.% TiF4 into the orthodontic primers showed adequate bond strength and better remineralization effect. However, 1 Wt.% TiF4 showed lower ARI values than 2 Wt.% TiF4.

White Spots: Prevention in Orthodontics-Systematic Review of the Literature

Early-stage dental demineralization, called white spots (WS), get their name from the characteristic colour that enamel takes on due to the acid attack of salivary cariogenic bacteria. They are often associated with fixed orthodontic therapy (FOT) and, if left untreated, evolve into caries with repercussions on oral health and dental aesthetics. This review aims to identify the most effective prophylaxis strategies to prevent WS during FOT. The search for the reviewed studies was conducted on the Pubmed, Scopus, and Web of Science databases, selecting English-only articles published in the 5 years from January 2018 to January 2023. The keywords used were "WS" and "fixed orthodontic*", using "AND" as the Boolean operator. A total of 16 studies were included for qualitative analysis. Prevention begins with maintaining proper oral hygiene; fluoride in toothpaste, mouthwashes, gels, varnishes, and sealants can be added to prophylaxis and used regularly. Using a laser in combination with fluoride helps prevent the occurrence of WS and assists in the repair processes of initial lesions. Further studies are needed to establish international guidelines for preventing WS in orthodontically treated patients.

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.

Efficacy of Fluoride Varnish with Casein Phosphopeptide and Amorphous Calcium Phosphate vs Fluoride Varnish in Prevention of White Spots Lesion in fixed Orthodontic Patients: In Vivo Study

AIM

The aim of the study is to compare the in vivo efficiency of Michigan (MI) varnish containing casein phosphopeptide (CPP) and amorphous calcium phosphate (ACP) and Fluoritop containing sodium fluoride (5% NaF) in the prevention and remineralization of white spot lesions (WSLs) around orthodontic brackets at days 28 and 56 after bonding.

MATERIALS AND METHODS

A total of 30 patients were selected and divided into two groups I (MI varnish) II (Fluoritop varnish) of 15 patients in each group. All the patients were bonded and then varnish was applied around the brackets. Right-side upper and lower first premolar teeth were taken as the control group and left-side upper and lower first premolar teeth as the experimental group. Also, 14, 24 teeth were extracted on day 28 after bonding and 34, 44 teeth after day 56 of bonding. Samples were collected and sent to laboratory for evaluation of surface microhardness (SMH).

RESULTS

Based on the statistics results, there was a significant decrease in demineralization and an increase in remineralization of WSLs after the application of varnish. No statistical significance was found between the effectiveness of MI varnish and Fluoritop except in the cervical region.

CONCLUSION

Through our study, we concluded that no statistical significance was found between the effectiveness of MI varnish and Fluoritop except in the cervical region where MI varnish was found to be more effective than Fluoritop in preventing WSLs.

CLINICAL SIGNIFICANCE

The results from the above study concluded that CPP-ACP varnish can be an effective method in preventing WSLs in patients undergoing fixed orthodontic treatment.

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.

Evaluation of enamel roughness after the removal of brackets bonded with different materials: In vivo study

The aims of this in vivo study were to evaluate the effect of bonding with resin-modified glass ionomer cement (RMGIC) and to assess enamel surface roughness before and after the removal of brackets bonded with composite or RMGIC from the maxillary central incisors. Fifteen orthodontic patients were selected for the study. For each patient, the teeth were rinsed and dried, and brackets were bonded with composite (Transbond XT) and RMGIC (Vitremer Core Buildup/Restorative). At the conclusion of orthodontic treatment, their brackets were removed. Dental replicas were made of epoxy resin in initial conditions (before bonded) and after polishing with an aluminum oxide disc system. Adhesive remnant index (ARI) and surface roughness was measured on the dental replicas and data were evaluated statistically by Mann-Whitney and paired t-test, respectively. No bracket debonding occurred during patients' treatment periods. It was verified that the ARI values of the two maxillary central incisors were similar (p = 0.665). For both bonding materials, the ARI value of 3 was predominant. After polishing, surface roughness was similar in the composite and RMGIC groups (0.245 μm and 0.248 μm, respectively; p = 0.07). In both groups, enamel surface roughness values were significantly lower after polishing compared with the initial condition (p < 0.001). RMGIC promoted efficiency in cementing brackets without fail during treatment; the choice of composite or RMGIC materials was not a factor that influenced the roughness of the enamel surface, however, polishing led to smoother surfaces than those found at the beginning of the treatment.

Evaluation of Change in Surface Enamel Microhardness in Patients Undergoing Fixed Orthodontic Appliance Therapy - A Randomized Control Trial

Aim:

This study aims at determining the amount of enamel decalcification in terms of microhardness.

Materials and Methods:

Twenty patients requiring treatment by extraction method for Class I malocclusion with bimaxillary protrusion were selected for the study. Twenty patients were randomly divided into control group and experimental group. In the control group (n = 40), extraction of permanent first premolars was done on day 1 of bonding to assess the Vickers hardness number (VHN) of enamel surface, and in the experimental group (n = 40), extraction of the contralateral premolars was done on the 28^th day after bonding to assess the VHN of enamel surface. The values are tabulated and analyzed by SPSS software.

Results:

There is significant surface enamel dissolution of enamel crystals in the experimental group compared to the control group, and a statistically significant difference in VHN is evident between the control and experimental groups. The surface enamel dissolution (VHN) is not significant difference noted between mandibular and maxillary premolars of the control and experimental groups.

Conclusion:

The present study has demonstrated a higher level of surface enamel dissolution in the experimental group. There is a marked difference in the VHN between the control and experimental groups, which is statistically significant. The scanning electron microscopy study also confirms the presence of surface enamel demineralization following orthodontic bonding.

Bioactive Materials for Direct and Indirect Restorations: Concepts and Applications

Currently, minimally invasive restorations could be made in dentistry applying adhesive materials and adhesion principles to the dental structures. Following this philosophy, endodontic interventions have been avoided largely, preserving hard tissues, and maintaining dental vitality. Advances in biologically favorable bioactive materials enabled clinicans to induce repair and regeneration of dental tissues. Such materials are primarily used for pulp protection and cementation of indirect restorations. This review highlights current bioactive materials available, principles of bioactivity and their mechanisms of action.

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.

Efficacy of fluoride associated with nano-hydroxyapatite in reducing enamel demineralization adjacent to orthodontic brackets: in situ study

Objective:

To assess in situ the effect of fluoride associated with nano-hydroxyapatite for the prevention of demineralization of the enamel adjacent to orthodontic brackets.

Material and Methods:

Eight volunteers wore palatal devices prepared with 6 bovine enamel blocks (5x5x2 mm) with bonded brackets. The volunteers used the devices in two different moments of 14 days each. During the first 14 days, a product containing fluoride + nano-hydroxyapatite was applied twice (experimental group, GNH, n = 48), and for the other 14 days no prevention product was applied (control group, CG, n = 48). In both groups, along the experiment, the blocks were dripped with 20% sucrose eight times daily. After the experiment, all the specimens were sectioned and examined for lesion depth analysis (µm) under polarized light microscopy, and for enamel longitudinal microhardness (measured under the bracket, at 30 µm and at 130 µm from the margin), at seven different depths (10, 20, 30, 50, 70, 90, and 110 µm).

Results:

Under polarized light, group GNH presented significantly less demineralization depth (X¯= 15.01 µm, SD = 33.65) in relation to CG (X¯= 76.43 µm, SD = 83.75). Enamel longitudinal microhardness demonstrated significantly higher microhardness for group GNH when compared to CG.

Conclusion:

Fluoride + nano-hydroxyapatite can be an alternative preventive procedure for demineralization of the enamel adjacent to orthodontic brackets.

Fluorides for preventing early tooth decay (demineralised lesions) during fixed brace treatment

BACKGROUND

Early dental decay or demineralised lesions (DLs, also known as white spot lesions) can appear on teeth during fixed orthodontic (brace) treatment. Fluoride reduces decay in susceptible individuals, including orthodontic patients. This review compared various forms of topical fluoride to prevent the development of DLs during orthodontic treatment. This is the second update of the Cochrane Review first published in 2004 and previously updated in 2013.

OBJECTIVES

The primary objective was to evaluate whether topical fluoride reduces the proportion of orthodontic patients with new DLs after fixed appliances. The secondary objectives were to examine the effectiveness of different modes of topical fluoride delivery in reducing the proportions of orthodontic patients with new DLs, as well as the severity of lesions, in terms of number, size and colour. Participant-assessed outcomes, such as perception of DLs, and oral health-related quality of life data were to be included, as would reports of adverse effects.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 1 February 2019), the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 1) in the Cochrane Library (searched 1 February 2019), MEDLINE Ovid (1946 to 1 February 2019), and Embase Ovid (1980 to 1 February 2019). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

Parallel-group, randomised controlled trials comparing the use of a fluoride-containing product versus a placebo, no treatment or a different type of fluoride treatment, in which the outcome of enamel demineralisation was assessed at the start and at the end of orthodontic treatment.

DATA COLLECTION AND ANALYSIS

At least two review authors independently, in duplicate, conducted risk of bias assessments and extracted data. Authors of trials were contacted to obtain missing data or to ask for clarification of aspects of trial methodology. Cochrane's statistical guidelines were followed.

MAIN RESULTS

This update includes 10 studies and contains data from nine studies, comparing eight interventions, involving 1798 randomised participants (1580 analysed). One report contained insufficient information and the authors have been contacted. We assessed two studies as at low risk of bias, six at unclear risk of bias, and two at high risk of bias. Two placebo (non-fluoride) controlled studies, at low risk of bias, investigated the professional application of varnish (7700 or 10,000 parts per million (ppm) fluoride (F)), every six weeks and found insufficient evidence of a difference regarding its effectiveness in preventing new DLs (risk ratio (RR) 0.52, 95% confidence interval (CI) 0.14 to 1.93; 405 participants; low-certainty evidence). One placebo (non-fluoride) controlled study, at unclear risk of bias, provides a low level of certainty that fluoride foam (12,300 ppm F), professionally applied every two months, may reduce the incidence of new DLs (12% versus 49%) after fixed orthodontic treatment (RR 0.26, 95% CI 0.11 to 0.57; 95 participants). One study, at unclear risk of bias, also provides a low level of certainty that use of a high-concentration fluoride toothpaste (5000 ppm F) by patients may reduce the incidence of new DLs (18% versus 27%) compared with a conventional fluoride toothpaste (1450 ppm F) (RR 0.68, 95% CI 0.46 to 1.00; 380 participants). There was no evidence for a difference in the proportions of orthodontic patients with new DLs on the teeth after treatment with fixed orthodontic appliances for the following comparisons: - an amine fluoride and stannous fluoride toothpaste/mouthrinse combination versus a sodium fluoride toothpaste/mouthrinse, - an amine fluoride gel versus a non-fluoride placebo applied by participants at home once a week and by professional application every three months, - resin-modified glass ionomer cement versus light-cured composite resin for bonding orthodontic brackets, - a 250 ppm F mouthrinse versus 0 ppm F placebo mouthrinse, - the use of an intraoral fluoride-releasing glass bead device attached to the brace versus a daily fluoride mouthrinse. The last two comparisons involved studies that were assessed at high risk of bias, because a substantial number of participants were lost to follow-up. Unfortunately, although the internal validity and hence the quality of the studies has improved since the first version of the review, they have compared different interventions; therefore, the findings are only considered to provide low level of certainty, because none has been replicated by follow-up studies, in different settings, to confirm external validity. A patient-reported outcome, such as concern about the aesthetics of any DLs, was still not included as an outcome in any study. Reports of adverse effects from topical fluoride applications were rare and unlikely to be significant. One study involving fluoride-containing glass beads reported numerous breakages.

AUTHORS' CONCLUSIONS

This review found a low level of certainty that 12,300 ppm F foam applied by a professional every 6 to 8 weeks throughout fixed orthodontic treatment, might be effective in reducing the proportion of orthodontic patients with new DLs. In addition, there is a low level of certainty that the patient use of a high fluoride toothpaste (5000 ppm F) throughout orthodontic treatment, might be more effective than a conventional fluoride toothpaste. These two comparisons were based on single studies. There was insufficient evidence of a difference regarding the professional application of fluoride varnish (7700 or 10,000 ppm F). Further adequately powered, randomised controlled trials are required to increase the certainty of these findings and to determine the best means of preventing DLs in patients undergoing fixed orthodontic treatment. The most accurate means of assessing adherence with the use of fluoride products by patients and any possible adverse effects also need to be considered. Future studies should follow up participants beyond the end of orthodontic treatment to determine the effect of DLs on patient satisfaction with treatment.

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.

Effects of Polyacrylic Acid Pre-Treatment on Bonded-Dentine Interfaces Created with a Modern Bioactive Resin-Modified Glass Ionomer Cement and Subjected to Cycling Mechanical Stress

OBJECTIVES

Resin-modified glass ionomer cements (RMGIC) are considered excellent restorative materials with unique therapeutic and anti-cariogenic activity. However, concerns exist regarding the use of polyacrylic acid as a dentine conditioner as it may influence the bonding performance of RMGIC. The aim of this study was to evaluate the effect of different protocols for cycling mechanical stress on the bond durability and interfacial ultramorphology of a modern RMGIC applied to dentine pre-treated with/without polyacrylic acid conditioner (PAA).

METHODS

The RMGIC was applied onto human dentine specimens prepared with silicon-carbide (SiC) abrasive paper with or without the use of a PAA conditioner. The specimens were immersed in deionised water for 24 h then divided in 3 groups. The first group was cut into matchsticks (cross-sectional area of 0.9 mm2) and tested immediately for microtensile bond strength (MTBS). The second was first subjected to load cycling (250,000 cycles; 3 Hz; 70 N) and then cut into matchsticks and tested for MTBS. The third group was subjected to load cycling (250,000 cycles; 3 Hz; 70 N), cut into matchsticks, and then immersed for 8 months storage in artificial saliva (AS); these were finally tested for MTBS. The results were analysed statistically using two-way ANOVA and the Student⁻Newman⁻Keuls test (α = 0.05). Fractographic analysis was performed using FE-SEM, while further RMCGIC-bonded dentine specimens were aged as previously described and used for interfacial ultramorphology characterisation (dye nanoleakage) using confocal microscopy.

RESULTS

The RMGIC applied onto dentine that received no pre-treatment (10% PAA gel) showed no significant reduction in MTBS after load cycling followed by 8 months of storage in AS (p > 0.05). The RMGIC⁻dentine interface created in PAA-conditioned SiC-abraded dentine specimens showed no sign of degradation, but with porosities within the bonding interface both after load cycling and after 8 months of storage in AS. Conversely, the RMGIC⁻dentine interface of the specimens with no PAA pre-treatment showed no sign of porosity within the interface after any of the aging protocols, although some bonded-dentine interfaces presented cohesive cracks within the cement after prolonged AS storage. However, the specimens of this group showed no significant reduction in bond strength (p < 0.05) after 8 months of storage in AS or load cycling (p > 0.05). After prolonged AS storage, the bond strength value attained in RMGIC⁻dentine specimens created in PAA pre-treated dentine were significantly higher than those observed in the specimens created with no PAA pre-treatment in dentine.

CONCLUSIONS

PAA conditioning of dentine prior to application of RMGIC induces no substantial effect on the bond strength after short-term storage, but its use may increase the risk of collagen degradation at the bonding interface after prolonged aging. Modern RMGIC applied without PAA dentine pre-treatment may have greater therapeutic synergy with saliva during cycle occlusal load, thereby enhancing the remineralisation and protection of the bonding interface.

Shear Bond Strength of Orthodontic Brackets Luted with RMGIC After Er:YAG Laser Etching with Two Pulse Modes Using a Digitally Controlled "X-Runner" Handpiece

OBJECTIVE

To compare the shear bond strength (SBS) values of orthodontic brackets luted using a resin-modified glass ionomer cement (RMGIC) on enamel surfaces etched using either an Er:YAG laser in two different working modes, or a conventional etching protocol, including phosphoric acid.

MATERIALS AND METHODS

Sixty healthy human premolars were randomly allocated to three experimental groups (n = 20) and etched with: Group 1: Er:YAG laser in super-short pulse (SSP) mode (100 mJ, 20 Hz, 2 W); Group 2: Er:YAG laser in quantum square pulse mode (120 mJ, 10 Hz, 1.2 W) using a digitally controlled handpiece ("X-Runner"); Group 3 (control): 5.25% sodium hypochlorite pretreatment, then 37% phosphoric acid for 15 sec. Stainless steel brackets were bonded using light-curing RMGIC for orthodontic bonding. After term cycling (1800 cycles), SBS testing was performed using a universal testing machine. After debonding, both enamel and bracket surfaces were examined to determine the amount of RMGIC still present on the surfaces.

RESULTS

Group 3 surfaces gave the lowest mean SBS (10.6104 ± 2.66196 MPa), whereas Group 1 provided the highest 1 (13.1795 ± 3.37904 MPa), which was significantly different from the control (Group 3, p = 0.0226). Group 2 provided intermediate values (11.8486 ± 0.59832 MPa) nonsignificantly different from the control or from SSP (p = 0.4215 and p = 0.3082, respectively).

CONCLUSIONS

Er:YAG laser treatment in SSP mode of enamel surfaces for orthodontic bonding provided higher SBS and a shear behavior of the luting material similar to the conventional acid-etching procedures, making it a viable alternative to acid etching.

Improvement of the mechanical, tribological and antibacterial properties of glass ionomer cements by fluorinated graphene

OBJECTIVE

The aim of this study was to improve the mechanical properties, wear resistance and antibacterial properties of conventional glass ionomer cements (GICs) by fluorinated graphene (FG), under the premise of not influencing their solubility and fluoride ion releasing property.

MATERIALS AND METHODS

FG with bright white color was prepared using graphene oxide by a hydrothermal reaction. Experimental modified GICs was prepared by adding FG to the traditional GICs powder with four different weight ratios (0.5wt%, 1wt%, 2wt% and 4wt%) using mechanical blending. Compressive and flexural strength of each experimental and control group materials were investigated using a universal testing machine. The Vickers microhardness of all the specimens was measured by a Vicker microhardness tester. For tribological properties of the composites, specimens of each group were investigated by high-speed reciprocating friction tester. Fluoride ion releasing was measured by fluoride ion selective electrode methods. The antibacterial effect of GICs/FG composites on selected bacteria (Staphylococci aureus and Streptococcus mutans) was tested with pellicle sticking method.

RESULTS

The prepared GICs/FG composites with white color were successfully fabricated. Increase of Vickers microhardness and compressive strength and decrease of friction coefficient of the GICs/FG composites were achieved compared to unreinforced materials. The colony count against S. aureus and S. mutans decreased with the increase of the content of FG. And the antibacterial rate of S. mutans can be up to 85.27% when the FG content was 4wt%. Additionally, fluoride ion releasing property and solubility did not show significant differences between unreinforced and FG reinforced GICs.

SIGNIFICANCE

Adding FG to traditional GICs could not only improve mechanical and tribological properties of the composites, but also improve their antibacterial properties. In addition, the GICs/FG composites had no negative effect on the color, solubility and fluoride ion releasing properties, which will open up new roads for the application of dental materials.

In vivo effect of antibacterial and fluoride-releasing adhesives on enamel demineralization around brackets: A micro-CT study

OBJECTIVES

The aim of this in vivo study was to investigate the preventive effect of two different adhesives on enamel demineralization and compare these adhesives with a conventional one.

MATERIALS AND METHODS

Fifteen patients requiring the extraction of their first four premolars for orthodontic treatment were included in the study. One premolar was randomly selected, and an antibacterial monomer-containing and fluoride-releasing adhesive (Clearfil Protect Bond, Kuraray Medical, Okayama, Japan) was used for orthodontic bracket bonding. Another premolar was randomly selected, and a fluoride-releasing and recharging orthodontic adhesive (Opal Seal, Ultradent Products, South Jordan, Utah) was used. One premolar was assigned as a control, and a conventional adhesive (Transbond XT, 3M Unitek, Monrovia, Calif) was used. The teeth were extracted after 8 weeks, and the demineralization areas of the 45 extracted teeth were analyzed using microcomputed tomography with software.

RESULTS

There was no significant difference between the white spot lesion (WSL) rates of the adhesives (P > .05). The volumes of the WSLs varied from 0 to 0.019349 mm³. Although Opal Seal showed the smallest lesion volumes, there was no significant difference in volumetric measurements of the lesions among the groups (P > .05).

CONCLUSIONS

The findings indicated no significant differences between the preventive effects of the adhesives used in this in vivo study over 8 weeks.

Evaluation of the anti-cariogenic potential and bond strength to enamel of different fluoridated materials used for bracket bonding

Abstract Objective To evaluate the in vitro and in situ anti-cariogenic potential and bond strength to enamel of materials containing fluoride (F), used for bracket bonding: Transbond XT (GT, negative control), Transbond Plus Color Change (GTF), Transbond-Self-Etching Primer (GSAF) and Vitremer (GV, positive control). Material and method In the in vitro study, the specimens were premolars with bonded brackets (n=12/group). After pH cycling, the F release, bond strength, fracture mode and presence of white spot lesions were assessed. In the in situ study, the specimens were enamel fragments with bonded brackets (n=12/group). Twelve volunteers wore palatal appliances in 4 phases, with cariogenic challenge. Bond strength, fracture mode and change in surface hardness (%SH) were determined. Result Relative to the in vitro study, F release (ppm) was: GT=0.257±0.068c; GTF=0.634±0.100b; GSAF=0.630±0.067b; GV=2.796±1.414a. Only GV showed no white spot lesions. Bond strength values (MPa) were GT=7.62±7.18a; GTF=5.15±6.91ab; GSAF=3.42±2.97bc; GV=2.87±2.09c. Adhesive fracture was the most frequent type, except for GTF. In the in situ study, %SH was: GT=-56.0±18.3a; GTF=-57.6±11.9a; GSAF=-57.1±11.3a; GV=-52.4±25.8a. Bond strength values were GT=9.5±4.4a; GTF=11.1±5.9a; GSAF=13.2± 6.6a; GV=6.6±4.0a. Cohesive fracture in material was the most frequent type, except for GTF. Conclusion Vitremer (GV) showed the highest anti-cariogenic potential in the in vitro study. However, it was not confirmed by the in situ study. Regarding bond strength values from the in situ study, all materials were shown to be adequate for clinical practice.

Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics

Glass ionomer cements (GICs) are being used for a wide range of applications in dentistry. In order to overcome the poor mechanical properties of glass ionomers, several modifications have been introduced to the conventional GICs. Nanotechnology involves the use of systems, modifications or materials the size of which is in the range of 1–100 nm. Nano-modification of conventional GICs and resin modified GICs (RMGICs) can be achieved by incorporation of nano-sized fillers to RMGICs, reducing the size of the glass particles, and introducing nano-sized bioceramics to the glass powder. Studies suggest that the commercially available nano-filled RMGIC does not hold any significant advantage over conventional RMGICs as far as the mechanical and bonding properties are concerned. Conversely, incorporation of nano-sized apatite crystals not only increases the mechanical properties of conventional GICs, but also can enhance fluoride release and bioactivity. By increasing the crystallinity of the set matrix, apatites can make the set cement chemically more stable, insoluble, and improve the bond strength with tooth structure. Increased fluoride release can also reduce and arrest secondary caries. However, due to a lack of long-term clinical studies, the use of nano-modified glass ionomers is still limited in daily clinical dentistry. In addition to the in vitro and in vivo studies, more randomized clinical trials are required to justify the use of these promising materials. The aim of this paper is to review the modification performed in GIC-based materials to improve their physicochemical properties.

Effect of acid etching on bond strength of nanoionomer as an orthodontic bonding adhesive

AIMS

A new Resin Modified Glass Ionomer Cement known as nanoionomer containing nanofillers of fluoroaluminosilicate glass and nanofiller 'clusters' has been introduced. An in-vitro study aimed at evaluating shear bond strength (SBS) and adhesive remnant index (ARI) of nanoionomer under etching/unetched condition for use as an orthodontic bonding agent.

MATERIAL AND METHODS

A total of 75 extracted premolars were used, which were divided into three equal groups of 25 each: 1-Conventional adhesive (Enlight Light Cure, SDS, Ormco, CA, USA) was used after and etching with 37% phosphoric acid for 30 s, followed by Ortho Solo application 2-nanoionomer (Ketac(™) N100, 3M, ESPE, St. Paul, MN, USA) was used after etching with 37% phosphoric acid for 30 s 3-nanoionomer was used without etching. The SBS testing was performed using a digital universal testing machine (UTM-G-410B, Shanta Engineering). Evaluation of ARI was done using scanning electron microscopy. The SBS were compared using ANOVA with post-hoc Tukey test for intergroup comparisons and ARI scores were compared with Chi-square test.

RESULTS

ANOVA (SBS, F = 104.75) and Chi-square (ARI, Chi-square = 30.71) tests revealed significant differences between groups (P < 0.01). The mean (SD) SBS achieved with conventional light cure adhesive was significantly higher (P < 0.05) (10.59 ± 2.03 Mpa, 95% CI, 9.74-11.41) than the nanoionomer groups (unetched 4.13 ± 0.88 Mpa, 95% CI, 3.79-4.47 and etched 9.32 ± 1.87 Mpa, 95% CI, 8.58-10.06). However, nanoionomer with etching, registered SBS in the clinically acceptable range of 5.9-7.8 MPa, as suggested by Reynolds (1975). The nanoionomer groups gave significantly lower ARI values than the conventional adhesive group.

CONCLUSION

Based on this in-vitro study, nanoionomer with etching can be successfully used as an orthodontic bonding agent leaving less adhesive remnant on enamel surface, making cleaning easier. However, in-vivo studies are needed to confirm the validity of present findings.

Fluoride release/uptake from different orthodontic adhesives: a 30-month longitudinal study

The aim of this study was to test the null hypothesis that there is no difference in fluoride release between resin-modified glass ionomer cements (RMGICs) and composites in the long term. The materials were divided into 5 groups: a nonfluoride-releasing composite - Group TXT (Transbond XT), a fluoride-releasing composite - Group QC (Quick-Cure), and three RMGICs - Groups FOLC, FOB and MC (Fuji Ortho LC, Fuji Ortho Band, and Multi-Cure). Fluoride release was measured at time intervals of 1 h, 1, 7, 14, 21 and 29 days, followed by further evaluations performed at 6, 12, 18, 24 and 30 months using selective ion electrodes connected to an ionic analyzer. Fluoride releasing and re-releasing experiments were analyzed using the Kruskal-Wallis test and Mann-Whitney test with the Bonferroni correction. The amount of fluoride released by FOB was larger in comparison with the other adhesives (p=0.01). In the long-term, FOLC and MC had a similar performance (p>0.05). The composites presented a low fluoride release, but fluoride ion uptake and re-release capacity of QC was statistically significant (p<0.05) during the experiment. In conclusion, the null hypothesis was rejected, the RMGIC Fuji Ortho Band and the composite Quick-Cure presented greater fluoride release and re-release capacity when recharged.

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.

Fluorides, orthodontics and demineralization: a systematic review

OBJECTIVES

To evaluate the effectiveness of fluoride in preventing white spot lesion (WSL) demineralization during orthodontic treatment and compare all modes of fluoride delivery.

DATA SOURCES

The search strategy for the review was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for RCTs or CCTs: Cochrane Clinical Trials Register, Cochrane Oral Health Group Specialized Trials Register, MEDLINE and EMBASE. Inclusion and exclusion criteria were applied when considering studies to be included. Authors of trials were contacted for further data.

DATA SELECTION

The primary outcome of the review was the presence or absence of WSL by patient at the end of treatment. Secondary outcomes included any quantitative assessment of enamel mineral loss or lesion depth.

DATA EXTRACTION

Six reviewers independently, in duplicate, extracted data, including an assessment of the methodological quality of each trial.

DATA SYNTHESIS

Fifteen trials provided data for this review, although none fulfilled all the methodological quality assessment criteria. One study found that a daily NaF mouthrinse reduced the severity of demineralization surrounding an orthodontic appliance (lesion depth difference -70.0 microm; 95% CI -118.2 to -21.8 microm). One study found that use of a glass ionomer cement (GIC) for bracket bonding reduced the prevalence of WSL (Peto OR 0.35; 95% CI 0.15-0.84) compared with a composite resin. None of the studies fulfilled all of the methodological quality assessment criteria.

CONCLUSIONS

There is some evidence that the use of a daily NaF mouthrinse or a GIC for bonding brackets might reduce the occurrence and severity of WSL during orthodontic treatment. More high quality, clinical research is required into the different modes of delivering fluoride to the orthodontic patient.

An in Vitro Evaluation of Remineralization Potential of Novamin(®) on Artificial Enamel Sub-Surface Lesions Around Orthodontic Brackets Using Energy Dispersive X-Ray Analysis (EDX)

OBJECTIVE

To evaluate and compare the Ca/P ratio of enamel samples around the orthodontic brackets for time periods of 0, 2 and 10 days in two groups (control group and study group).

MATERIALS AND METHODS

Forty extracted teeth were randomly divided into control group and study group. All samples were demineralized and incubated in artificial saliva at 37°C for a period of 10 days after demineralization. During this phase the enamel samples in the study group were treated with remineralizing paste (NuproNusolution containing Novamin®-Dentsply) for 10 days. At the end of the incubation period, Ca/P ratios were analyzed for both the groupsby EDX analysis. Data obtained was subjected to statistical analysis using student t-test for paired samples and Student t- test for individual samples (p ≤ 0.05).

RESULTS

It was found that the mean Ca/P ratio was significantly lower for the control group as compared to the study group (p-value < 0.05) after 10 d of incubation.

CONCLUSION

Novamin(®) containing remineralization toothpaste showed significant remineralizing potential in inhibition of artificial enamel sub-surface lesion around bracket after 10 days of remineralization phase. EDX element analysis was found to be an efficient method to quantify the changes in mineral content of a sample during in vitro caries studies.

Effect of enamel protective agents on shear bond strength of orthodontic brackets

BACKGROUND

This paper aimed to study the effect of two enamel protective agents on the shear bond strength (SBS) of orthodontic brackets bonded with conventional and self-etching primer (SEP) adhesive systems.

METHODS

The two protective agents used were resin infiltrate (ICON) and Clinpro; the two adhesive systems used were self-etching primer system (Transbond Plus Self Etching Primer + Transbond XT adhesive) and a conventional adhesive system (37% phosphoric acid etch + Transbond XT primer + Transbond XT adhesive ). Sixty premolars divided into three major groups and six subgroups were included. The shear bond strength was tested 72 h after bracket bonding. Adhesive remnant index scores (ARI) were assessed. Statistical analysis consisted of a one-way ANOVA for the SBS and Kruskal-Wallis test followed by Mann-Whitney test for the ARI scores.

RESULTS

In the control group, the mean SBS when using the conventional adhesive was 21.1 ± 7.5 MPa while when using SEP was 20.2 ± 4.0 MPa. When ICON was used with the conventional adhesive system, the SBS was 20.2 ± 5.6 MPa while with SEP was 17.6 ± 4.1 MPa. When Clinpro was used with the conventional adhesive system, the SBS was 24.3 ± 7.6 MPa while with SEP was 11.2 ± 3.5 MPa. Significant differences in the shear bond strength of the different groups (P = .000) was found as well as in the ARI scores distribution (P = .000).

CONCLUSION

The type of the adhesive system used to bond the orthodontic brackets, either conventional or self-etching primer, influenced the SBS, while the enamel protective material influenced the adhesive remnant on the enamel surface after debonding.

Effects of the addition of fluoride to a 4-META/MMA-TBB-based resin adhesive on fluoride release, acid resistance of enamel and shear bond strength in vitro

This study investigated fluoride release, acid resistance and shear bond strength (SBS) of new 4-META/MMA-TBB-based fluoride-containing resin adhesive (Super-Bond/F3). Super-Bond, Transbond Plus and Fuji Ortho LC were selected for comparison. Fluoride release into distilled water during 6-month period was measured using disk-shaped specimens. Brackets were bonded to human premolars with each material and then the specimens for the nanoindentation test were subjected to alternating immersion (demineralizing and remineralizing solutions); the hardness and elastic modulus of the enamel around bracket were determined. Rest of the specimens was subjected to examine the SBS. Super-Bond/F3 and Fuji Ortho LC showed significantly greater fluoride release compared with the other materials. The reductions in hardness and the elastic modulus for Super-Bond/F3 and Fuji Ortho LC were lower than those for the other materilas. Super-Bond and Super-Bond/F3 showed significantly greater SBS than Fuji Ortho FC. In conclusion, Super-Bond/F3 showed high fluoride-release, cariostatic potential and equivalent SBS.

Fluorides for the prevention of early tooth decay (demineralised white lesions) during fixed brace treatment

BACKGROUND

Demineralised white lesions (DWLs) can appear on teeth during fixed brace treatment because of early decay around the brackets that attach the braces to the teeth. Fluoride is effective in reducing decay in susceptible individuals in the general population. Individuals receiving orthodontic treatment may be prescribed various forms of fluoride treatment. This review compares the effects of various forms of fluoride used during orthodontic treatment on the development of DWLs. This is an update of a Cochrane review first published in 2004.

OBJECTIVES

The primary objective of this review was to evaluate the effects of fluoride in reducing the incidence of DWLs on the teeth during orthodontic treatment.The secondary objectives were to examine the effectiveness of different modes of fluoride delivery in reducing the incidence of DWLs, as well as the size of lesions. Participant-assessed outcomes, such as perception of DWLs, and oral health-related quality of life data were to be included, as would reports of adverse effects.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 31 January 2013); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 12); MEDLINE via OVID (1946 to 31 January 2013); and EMBASE via OVID (1980 to 31 January 2013).

SELECTION CRITERIA

We included trials if they met the following criteria: (1) parallel-group randomised clinical trials comparing the use of a fluoride-containing product versus placebo, no treatment or a different type of fluoride treatment, in which (2) the outcome of enamel demineralisation was assessed at the start and at the end of orthodontic treatment.

DATA COLLECTION AND ANALYSIS

At least two review authors independently, in duplicate, conducted risk of bias assessments and extracted data. Authors of trials were contacted to obtain missing data or to ask for clarification of aspects of trial methodology. The Cochrane Collaboration's statistical guidelines were followed.

MAIN RESULTS

For the 2013 update of this review, three changes were made to the protocol regarding inclusion criteria. Fourteen studies included in the previous version of the review were excluded from this update for the following reasons: five previously included studies were quasi-randomised, a further five were split-mouth studies, three measured outcomes on extracted teeth only and in one, the same fluoride intervention was used in each intervention group of the study.Three studies and 458 participants were included in this updated review. One study was assessed at low risk of bias for all domains, in one study the risk of bias was unclear and in the remaining study, the risk of bias was high.One placebo-controlled study of fluoride varnish applied every six weeks (253 participants, low risk of bias), provided moderate-quality evidence of an almost 70% reduction in DWLs (risk ratio (RR) 0.31, 95% confidence interval (CI) 0.21 to 0.44, P value < 0.001). This finding is considered to provide moderate-quality evidence for this intervention because it has not yet been replicated by further studies in orthodontic participants.One study compared two different formulations of fluoride toothpaste and mouthrinse prescribed for participants undergoing orthodontic treatment (97 participants, unclear risk of bias) and found no difference between an amine fluoride and stannous fluoride toothpaste/mouthrinse combination and a sodium fluoride toothpaste/mouthrinse combination for the outcomes of white spot index, visible plaque index and gingival bleeding index.One small study (37 participants) compared the use of an intraoral fluoride-releasing glass bead device attached to the brace versus a daily fluoride mouthrinse. The study was assessed at high risk of bias because a substantial number of participants were lost to follow-up, and compliance with use of the mouthrinse was not measured.Neither secondary outcomes of this review nor adverse effects of interventions were reported in any of the included studies.

AUTHORS' CONCLUSIONS

This review found some moderate evidence that fluoride varnish applied every six weeks at the time of orthodontic review during treatment is effective, but this finding is based on a single study. Further adequately powered, double-blind, randomised controlled trials are required to determine the best means of preventing DWLs in patients undergoing orthodontic treatment and the most accurate means of assessing compliance with treatment and possible adverse effects. Future studies should follow up participants beyond the end of orthodontic treatment to determine the effect of DWLs on participant satisfaction with treatment.

Effect of different concentrations of papain gel on orthodontic bracket bonding

Background

The objective of this study was to verify the hypothesis that enamel deproteinization with papain gel at concentrations of 2%, 4%, 6%, 8%, and 10% increases shear bond strength as concentration increases.

Methods

A total of 180 bovine mandibular permanent incisors were used, divided into six groups (n = 30), and denominated as follows: group 1 is the control group (CG) in which brackets are bonded with resin-modified glass ionomer cement (RMGIC) according to the manufacturer's recommendations and groups 2, 3, 4, 5, and 6 have brackets bonded with RMGIC after enamel deproteinization with papain gel at concentrations of 2%, 4%, 6%, 8%, and 10%, respectively. After bonding, teeth were immersed in artificial saliva and kept at a temperature of 37°C for 24 h. Mechanical tests were then performed in a universal mechanical test machine EMIC DL 5000 (Sao Jose dos Pinhais, Brazil). Values obtained were submitted to analysis of variance and then to Tukey's test (p < 0.05).

Results

The results demonstrated that groups 5 and 6 showed the highest shear bond strength, differing statistically from the other groups (p < 0.05). CG with no papain gel used showed the lowest value and in turn showed no differences for groups 2, 3, and 4. As regards adhesive remnant index, CG showed statistical differences from the others. Groups 2, 3, 4, 5, and 6, in which papain gel was used, presented no statistical differences among them (p > 0.05).

Conclusions

It was concluded that enamel deproteinization with 8% and 10% papain gel increases shear bond strength of orthodontic brackets bonded with RMGIC.

Influence of topical fluoride application on mechanical properties of orthodontic bonding materials under pH cycling

OBJECTIVE

To evaluate in vitro the influence of topical fluoride application on the mechanical properties of orthodontic cements containing fluoride under pH cycling conditions.

MATERIALS AND METHODS

Edgewise brackets for maxillary central incisors were bonded to 192 bovine incisors using Transbond XT (G1), Transbond Plus Color Change (G2), and Fuji Ortho LC (G3) (n  =  64 for each group). The specimens of each group were subdivided (n  =  16) into different subgroups. Subgroup A received no topical fluoride application during pH cycling, while the experimental subgroups received topical fluoride treatments as follows: B, application three times per day of fluoride dentifrice (1450 ppm F); C, application one time per day of fluoride mouth rinse (250 ppm F); and D, combination of fluoride dentifrice and fluoride mouth rinse. After 14 days of pH cycling, the shear bond strength and Adhesive Remnant Index were evaluated statistically.

RESULTS

Polarized light microscopy showed that pH cycling induced mineral loss in all specimens. The topical application of fluoride did not have an influence on shear bond strength, although the association of fluoride dentifrice and mouth rinse increased the shear bond strength of the resinous cement without fluoride (P < .01). Regarding the Adhesive Remnant Index, no statistical differences were found within the groups G1 (P  =  .23), G2 (P  =  .47), and G3 (P  =  .74).

CONCLUSION

Topical fluoride treatments improved the shear bond strength of resinous cement, regardless of the material's fluoride-releasing capacity, and reached the adhesive fractures.

Comparison of the effect of three cements on prevention of enamel demineralization adjacent to orthodontic bands

Background and aims

This in vitro study was designed to compare enamel demineralization depths adjacent to bands cemented with zinc polycarboxylate, glass ionomer (GI) and resin-modified glass ionomer (RMGI), in order to achieve minimal enamel demineralization during orthodontic treatment.

Materials and methods

Sixty fully developed extracted third molars were randomly divided into three testgroups each containing 20 samples, used to cement orthodontic bands with zinc polycarboxylate, GI and RMGI. All samples were demineralized using White method using hydroxyapatite, latic acid and Carbapol for in vitro caries simulation, and then, immersed in 10% solution of methylene blue. The mean depth of dye penetration was assessed up to 0.1 millimeter, reflect-ing the depth of enamel demineralization. One way ANOVA and LSD statistical tests were employed to evaluate significant differences among groups.

Results

The highest dye penetration depth was seen in zinc polycarboxylate group, followed by GI, and RMGI groups, respectively, with significant differences among each two groups (P < 0.05).

Conclusion

The use of RMGI cement seems to present significantly better prevention of enamel demineralization adja-cent to orthodontics bands.

Effects of bonding materials on the mechanical properties of enamel around orthodontic brackets

OBJECTIVE

To determine if the enamel around orthodontic brackets is significantly altered after demineralization followed by application of adhesives with and without fluoride-releasing ability.

MATERIALS AND METHODS

One hundred eight noncarious human premolars were divided into six groups of 18 each and exposed to a demineralization solution. Stainless steel brackets were bonded using two conventional composite resin etch-and-rinse systems, three self-etching primer (SEP) composite resin systems, and one resin-modified glass ionomer cement (RMGIC) system. One conventional and one SEP composite resin adhesive did not have fluoride-releasing ability, which was claimed for the other four adhesives. The elastic modulus and hardness of the enamel were determined with a nanoindenter at 10 equidistant depths ranging from 1-46 µm and at four regions: control (not exposed) enamel surface, under the adhesive, and at 50 µm and 100 µm from the bracket edges. Using the Kruskal-Wallis and Mann-Whitney U-tests (P < .0125 for statistical significance), these properties were compared at different regions.

RESULTS

The same behavior was observed for values of elastic modulus and hardness. Significant differences were found within approximately 21 µm of the enamel surface for etching with 35% phosphoric acid or priming with SEP, but only minimal changes occurred for the SEP adhesive. Increases in near-surface elastic modulus and hardness of enamel were found with the SEP adhesive and RMGIC with fluoride-releasing ability.

CONCLUSIONS

Clinical use of the fluoride-releasing adhesives investigated may prevent demineralization of enamel around brackets during orthodontic treatment.

Bracket bond strength and cariostatic potential of an experimental resin adhesive system containing Portland cement

OBJECTIVE

To determine if a new experimental resin-based material containing Portland cement (PC) can help prevent enamel caries while providing adequate shear bond strength (SBS).

MATERIALS AND METHODS

Brackets were bonded to human premolars with experimental resin-based adhesive pastes composed of three weight rations of resin and PC powder (PC 30, 7:3; PC 50, 5:5; PC 70, 3:7; n  =  7). Self-etching primer (SEP) adhesive (Transbond Plus) and resin-modified glass ionomer cement (RMGIC) adhesive (Fuji Ortho FC Automix) were used for comparison. All of the bonded teeth were subjected to alternating immersion in demineralizing (pH 4.55) and remineralizing (pH 6.8) solutions for 14 days. The SBS for each sample was examined, and the Adhesive Remnant Index (ARI) score was calculated. The hardness and elastic modulus of the enamel were determined by a nanoindenter at 20 equidistant depths from the external surface at 100 µm from the bracket edge. Data were compared by one-way analysis of variance and a chi-square test.

RESULTS

PC 50 and PC 70 showed significantly greater SBS than Fuji Ortho FC Automix, although Transbond Plus showed significantly greater SBS than other bonding systems. No significant difference in the ARI category was observed among the five groups. For specimens bonded with PC 50 and PC 70, the hardness and elastic modulus values in most locations were equivalent to those of Fuji Ortho FC Automix.

CONCLUSIONS

Experimental resin-based bonding material containing PC provides adequate SBS and a caries-preventive effect equivalent to that of the RMGIC adhesive system.

Efficacy of light-activated sealant on enamel demineralization in orthodontic patients: an atomic force microscope evaluation

OBJECTIVE

The purpose of this study was to investigate the efficacy of (Pro Seal) sealant in preventing enamel decalcification in-vivo and compare its effect with fluoride varnish and unfilled sealant using atomic force microscopy.

MATERIALS AND METHODS

Eight orthodontic patients who were candidates for extraction of all first premolars for orthodontic treatment were recruited to this study. Thirty two premolars (upper and lower) were randomly divided into four groups (n=8) for each group, 4 maxillary and 4 mandibular); Control (no -treatment); Fluoride varnish, Unfilled sealant (Light Bond) and filled sealant (Pro-Seal). After two months the brackets were debonded and the teeth were extracted and prepared for Atomic force microscopic scanning. Each sample was scanned twice at two different scan areas 50 and 10µm at the buccal cervical third of the crown. Images were recorded with slow scan rate and resolution and the mean roughness height and total surface area were calculated for each scan area. Comparison between groups was performed using one way analysis of variance test with level of significance was set to be 0.05.

RESULTS

Pro Seal treated samples show the lowest roughness height and total surface area.

CONCLUSION

Pro Seal was the most effective prophylaxis technique in preventing enamel demineralization during orthodontic treatment.

Determinants of enamel decalcification during simulated orthodontic treatment

OBJECTIVE

To determine the relative effects that phosphoric acid etching, metal brackets, composite resin adhesives, and filled resin sealants have on enamel decalcification.

MATERIALS AND METHODS

One hundred and fifty teeth were randomly divided into six groups to test the effects of acid etching, brackets, and a composite resin adhesive. The right side of each tooth was sealed. The teeth were submitted to a simulated carious challenge by Streptococcus mutans in a nutritive media for 42 days. Scanning electron photomicrographs (SEMs) were used to qualitatively evaluate the tooth surfaces. DIAGNOdent laser fluorescence was used to quantify the decalcification changes that occurred.

RESULTS

SEMs showed normal enamel on the control teeth, etching patterns on the acid-etched teeth, surface degradation on the teeth that had resin, and sealant tags on the sealed side. The untreated control group showed significantly less decalcification (P ≤ .05) than did all groups except the no etch+bracket group. The no etch+bracket group showed significantly less decalcification than did the etch+bracket, no etch+resin, and the etch+resin groups. Acid-etched teeth demonstrated significantly more decalcification (34%) than did those that were not etched. The teeth with resin showed significantly more decalcification (24%) than did those without resin. There was no significant difference between teeth that did and did not have brackets. The unsealed side of the teeth showed small amounts of--but significantly more--decalcification (5%) compared to the sealed side.

CONCLUSIONS

Acid etching and composite resin adhesives increase enamel decalcification in vitro, while brackets do not. Filled resin sealants protect the teeth from decalcification.

Effect of antibacterial monomer-containing adhesive on enamel demineralization around orthodontic brackets: an in-vivo study

INTRODUCTION

The aims of this study were to evaluate the effect of an antibacterial monomer-containing self-etching adhesive in reducing enamel demineralization around orthodontic brackets in vivo and to compare it with the conventional adhesive system quantitatively.

METHODS

Fourteen orthodontic patients were randomly divided into 2 equal groups; they received brackets fitted to all their teeth, bonded with either Clearfil Protect Bond (Kuraray Medical, Okayama, Japan) (experimental group) or Transbond XT (3M Unitek, Monrovia, Calif) (control group). Block randomization to obtain equal numbers in each group was used. After 30 days, all first premolars were extracted with orthodontic indications and longitudinally sectioned. Demineralization was assessed by cross-sectional microhardness. Determinations were made at the bracket edge cementing limits and at occlusal and cervical points 100 and 200 μm away from the edge. In all of these positions, 6 indentations were made at depths of 10 to 90 μm from the enamel surface. Analysis of variance (ANOVA) and the Tukey post-hoc test were used. The statistical significance level was set at P <0.05.

RESULTS

ANOVA showed statistically significant differences for adhesive type, position, depth, and their interactions (P <0.05). The multiple comparison test showed that the antibacterial monomer-containing adhesive was significantly more efficient than the conventional adhesive system, reducing enamel demineralization in almost all evaluations (P <0.05).

CONCLUSIONS

The results indicated that using antibacterial monomer-containing adhesive for bonding orthodontic brackets successfully inhibited caries in vivo. This cariostatic effect was localized at the area around the brackets and was significant after 30 days.

Evaluation of cytotoxicity and degree of conversion of glass ionomer cements reinforced with resin

The objective of the present study was to evaluate the cytotoxicity and degree of monomer conversion of resin-reinforced glass ionomer cements (RGIC) over different time periods. Four RGICs: Fuji Ortho LC (FOLC), Fuji Ortho Band (FOB), Orthoglass (OGL), and Multicure Glass Ionomer (MCI) were evaluated for cytotoxicity in fibroblastic L929 cells and for their degree of monomer conversion over different time periods. Three control groups were also analysed: positive control (C+), consisting of Tween 80 cell detergent; negative control (C-), consisting of phosphate-buffered saline; and cell control (CC), consisting of cells exposed to any material. To evaluate the cytotoxicity, the dye-uptake technique was used and the degree of conversion was evaluated using infrared spectroscopy. The data obtained were analysed by analysis of variance and the Tukey's test. The results showed cytotoxicity of the RGICs at 1 and 24 hours; the viability values of these materials were statistically different from the C- and CC groups (P < 0.05). After 48 hours, the FOLC group was statistically similar to the CC and C- groups but different from the others. At 1 hour, there was no difference in the degree of conversion between the FOLC and OGL groups (P > 0.05) or between the FOB and MCI (P < 0.05) groups. However, at 48 hours, the FOLC group had greater conversion values than the other groups (P < 0.05). There is a direct relationship between the degree of conversion and RGIC cytotoxicity. Following initial polymerization, cytotoxicity decreases and, consequently, the degree of conversion of the material increases.

Mechanical properties of one and two-step fluoridated orthodontic resins submitted to different pH cycling regimes

The aim of this study is to assess the in vitro shear bond strength and adhesive remnant index (ARI) of one and two-step fluoridated orthodontic resins under conditions that simulate high cariogenic challenge. Edgewise brackets for maxillary central incisors were randomly bonded to 80 bovine incisors, using either Transbond Plus Color Change orthodontic resin and a self-etching primer adhesive (G1; n = 40) or Orthodontic Fill Magic with a conventional acid-etch technique (G2; n = 40). Each group of resin (n = 10) was divided into: immediate shear (A- pre-cycling control), immersion in artificial remineralizing saliva (neutral saliva) for 14 days (B- post-cycling control) and pH cycling with high cariogenic challenge (C- acid saliva with pH 5.5 and D- acid saliva with pH 4.5). After 14 days of pH cycling, the shear bond strength and ARI were evaluated. Considering the shear bond strength, Transbond Plus Color Change resin was stronger than Orthodontic Fill Magic when it was submitted to high cariogenic challenge (p < 0.05). Also Transbond Plus Color Change resin showed better adhesion to enamel than Orthodontic Fill Magic, in all situations evaluated (p < 0.05). It could be concluded that Transbond Plus Color Change resin presented better shear bond strength and adhesive remnant index when submitted to high cariogenic challenge, in comparison with Orthodontic Fill Magic.