Daily exposure to fluoride mouthrinse produces sustained fluoride release from orthodontic adhesives in vitro

Effect of Fluoride Release on Enamel Demineralization Adjacent to Orthodontic Brackets

INTRODUCTION AND AIM

This study aimed to evaluate the ability of fluoride-releasing adhesives to inhibit enamel demineralization surrounding orthodontic brackets.

METHODS

Two groups of 40 sound human premolars were sectioned mesio-distally. The halves were varnished, and orthodontic brackets were bonded with different adhesive materials. An area 1 mm wide surrounding the brackets was left exposed. Each specimen was immersed daily in a pH cycle for 28 days. In the second group, the specimens were exposed daily to a fluoride solution (250 ppm F-) at 37°C. The fluoride release from different groups was measured. Quantitative light-induced fluorescence (QLF) was used to quantify fluorescence loss of enamel surfaces adjacent to the brackets. Results were statistically analyzed using ANOVA at (p<0.05).

RESULTS

Fluoride released from the three fluoride-releasing adhesives was significantly higher (p<0.001) in the group with daily fluoride exposures than in the group without fluoride exposures. Enamel adjacent to brackets bonded with Fuji Ortho LC, Ketac Cem, and Dyract Cem showed significantly less (p<0.001) changes in (ΔQ) value (less demineralization) than enamel bonded with Transbond, the control adhesive material.

CONCLUSIONS

Using fluoride-releasing adhesives significantly reduced the level of demineralization adjacent to orthodontic brackets.

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.

Determination of chemical species of fluoride during uptake mechanism of glass-ionomer cements with NMR spectroscopy

OBJECTIVE

The aim of the present study was to determine the chemical species formed inside glass-ionomer cements after fluoride uptake and to investigate the depth of penetration of fluoride ions within the cement matrix.

METHODS

An experimental fluoride-free glass with composition 2SiO₂-AlO₃-CaO was produced. The glass powder was mixed with aqueous poly(acrylic acid) (PAA), and allowed to set. The resulting specimens were stored in 20ml KF solution with 1000ppm fluorine for 24h and then placed into the same amount of water as for 24h. A fluoride selective electrode was used to give the F concentration of the respective solutions. ¹⁹F MAS-NMR spectra were recorded on powdered cement specimens using a Bruker AVANCE-NEO 600 spectrometer. In addition, SEM observation and EDX chemical analysis were conducted on the cross-section of a carefully fractured specimen.

RESULTS

Fluoride was shown to be mainly present in the surface layers of the specimen after placement in the KF solution, and only a small fraction was re-released into water. ¹⁹F NMR spectroscopy showed that AlF complexes were formed within the cement.

SIGNIFICANCE

The fluoride taken up by a free-fluoride glass ionomer cement mostly occupies surface layers and is retained because it bonds to aluminum within the matrix. This finding explains why the majority of fluoride taken up by conventional glass ionomer cements is retained.

Effect of fluoride exposure on cariostatic potential of orthodontic bonding agents: anin vitroevaluation

AIMS

The aims of this in vitro study were to compare the cariostatic potential of a resin modified glass ionomer cement (Fuji Ortho LC) to that of a resin control (Transbond) for bracket bonding and to compare the effect of extrinsic fluoride application on the cariostatic potential of each material.

SETTING

Ex vivo study.

MATERIALS AND METHODS

Orthodontic brackets were bonded to 40 extracted premolars, 20 with Fuji Ortho LC and 20 with Transbond. The teeth were subjected to pH cycling, pH 4.55, and pH 6.8, over a 30-day period. Ten teeth bonded with each material were immersed in a 1000 ppm fluoride solution for 2 minutes each day. Fluoride release was measured throughout the study from all teeth. After 30 days, the teeth were assessed visually for signs of enamel decalcification.

RESULTS

Significant differences in decalcification existed macroscopically between all four groups of teeth, with the exception of those bonded with Fuji Ortho LC alone compared with Transbond alone (P = 0.22), and Fuji Ortho LC alone compared with Transbond with added fluoride (P = 0.3). Fluoride release from Fuji Ortho LC alone fell to minimal values, but with the addition of extrinsic fluoride the levels fell initially and then followed an upward trend. There was minimal fluoride release, from Transbond alone, but with daily addition of extrinsic fluoride, subsequent fluoride release was increased. Significant differences existed in the amount of fluoride released between all groups, except comparing Fuji Ortho LC alone and Transbond with added fluoride.

CONCLUSIONS

The results of this study have indicated that with an in vitro tooth-bracket model, the creation of white spot inhibition could best be achieved by the use of a resin-modified glass ionomer cement, supplemented with fluoride exposure. The least protection was afforded by the composite control. The resin-modified glass ionomer cement alone and the composite with added fluoride demonstrated equivalent protection.

An in-vitro assessment of weekly cumulative fluoride release from three glass ionomer cements used for orthodontic banding

OBJECTIVES

To compare the in-vitro Weekly Cumulative Fluoride Release (WCFR) of three Glass Ionomer Cements (GICs) used for orthodontic banding.

MATERIALS AND METHODS

The GICs tested were Granitec (Confi-Dental, Louisville, CO, USA), Bandtite (American Orthodontics, Sheboygan, WI, USA) and Ariadent (Apadana Tak Co, Tehran, Iran). Fifteen discs of each GIC were constructed (6mm diameter and 1.5mm depth). Specimens were immersed in 5 ml of deionised water and the WCFR was measured at weekly intervals, on days 1, 8, 15, 22 and 29 after immersion in deonised water, using the potentiometery device and single junction saturated calomel electrode technique (Jenway, England, UK). To compare the WCFR profile of 3 GICS, data were subjected to the one-way analysis of variance (ANOVA), and were appropriate, the Scheffe or Tamhane multiple comparison tests (post-hoc). For assessing the longitudinal changes of average WCFRs in 3 GICs, the repeated measures ANOVA were used. Post hoc tests using the Bonferroni correction was also used to compare the average WCFRs at different time-points.

RESULTS

One-way ANOVA and post-hoc multiple comparison tests revealed significant differences in WCFR among 3 GICs at five time-points (p<0.05). The post-hoc multiple comparison test revealed Bandtite cement had consistently higher WCFR at all time-points, compared to Granitec and Ariadent cements (p<0.05). The one-way ANOVA test revealed significant differences in WCFR at different time-points for all GIC groups (p<0.05). The day 8 exhibited the highest WCFR for all GICs. The repeated measures ANOVA test revealed significant differences in WCFR at different time-points for all GIC groups (p<0.0005). Reviewing average WCFR on days 22 and 29, these values for Granitec, Bandtite and Ariadent GICs, were higher (p<0.05), not different (p>0.05), and significantly lower (p<0.05) than the day 1 values, respectively.

CONCLUSIONS

Bandtite followed by Granitec showed higher WCFR compared to Ariadent.

Fluoride release and cariostatic potential of orthodontic adhesives with and without daily fluoride rinsing

INTRODUCTION

In this study, we aimed to evaluate the fluoride-release profiles and caries lesion development in an enamel model with brackets cemented with 4 orthodontic adhesives with and without daily fluoride exposure.

METHODS

Four orthodontic adhesives (Ketac Cem mu, 3M ESPE, Seefeld, Germany; Fuji Ortho LC, GC Corporation, Tokyo, Japan; Light-Bond, Reliance Orthodontic Products, Itasca, Ill; and Transbond XT, 3M Unitek, Monrovia, Calif) were used. Brackets were bonded on bovine enamel with each adhesive (n = 10) and subjected to alternate cycles of demineralizing (pH 4.55) and remineralizing (pH 6.8) solutions. Unbracketed enamel samples served as a reference. Five samples from each group were immersed in a fluoride mouth rinse (250 ppm fluoride) for 1 minute each day (test groups). Fluoride release was measured at regular intervals over 28 days. The mineral distribution of peribracket enamel after 28 days was quantified by transversal microradiographs.

RESULTS

Fluoride-release profiles of Ketac Cem mu, Fuji Ortho LC, and Light-Bond were high for the first 24 hours and reached a constant level after 2 weeks. Fuji Ortho LC released significantly more fluoride than did the other adhesives in both the control and test groups (P <0.01, repeated measures ANOVA and Bonferroni test). Enamel bonded with Fuji Ortho LC had significantly shallower lesions and less mineral loss (P <0.01, 2-way ANOVA, and Tukey HSD).

CONCLUSIONS

Bonding of orthodontic brackets with Fuji Ortho LC resulted in less peribracket enamel demineralization with and without daily fluoride rinsing, mainly due to its better fluoride-release profile. In contrast, Transbond XT and Light-Bond offered few cariostatic effects to the enamel.

Kinetics of fluoride release from and reuptake by orthodontic cements

INTRODUCTION

The purposes of this in-vitro study were to compare the fluoride-release profiles and the fluoride release, reuptake, and rerelease characteristics of orthodontic cements before and after topical fluoride treatment.

METHODS

The orthodontic cements tested were 2 resin-modified glass ionomers (Vitremer [3M Dental Products, St Paul, Minn] and Fuji Ortho LC [GC Dental, Tokyo, Japan]), a glass ionomer (Ketac-Cem [Espe-Premier Dental Products, Norristown, Pa]), and a composite (Concise [3M Dental Products]). Fifteen specimens of each material were stored in plastic vials containing deionized water at 37 degrees C. Fluoride release was measured daily for the first 15 days and then weekly for a 57-day period. After initial elusion, specimens were exposed to 1.23% acidulated phosphate fluoride gel, and the fluoride release was monitored daily for 7 consecutive days. The fluoridation/elution procedure was repeated once, and the specimen surfaces were then examined with a scannning electron microscope.

RESULTS

Kinetic release profiles of the test materials were deduced. All materials except Concise had similar fluoride-release profiles. Vitremer demonstrated the highest fluoride release, followed by Fuji Ortho LC and then Ketac-Cem in the time period of the study (P <.01). All glass-ionomer cements, but especially Fuji Ortho LC, showed enhanced uptake and release on repeated exposure to the topical fluoride treatment. Nevertheless, Vitremer showed the greatest surface degradation after refluoridation.

CONCLUSIONS

All resin-modified and conventional glass ionomers studied exhibited the capacity for fluoride release and reuptake after fluoridation, but the subsequent fluoride release was transitory. Thus, the benefit from fluoride reuptake in these orthodontic cements should be balanced with the risk of weakening them after repeated fluoridation.

Linear regression modeling to compare fluoride release profiles of various restorative materials

OBJECTIVES

The aim of this study was to compare the released fluoride profiles of various restorative materials by using linear regression analysis.

METHODS

Specimens were prepared using a cylindrical Teflon mold with a height of 2 mm and a radius of 8 mm. After being prepared, specimens were immediately placed into artificial saliva which was replaced at various times during 6 weeks. These released intrinsic fluoride amounts were measured by using an ion selective electrode. Then, data obtained cumulatively were statistically analyzed, and the released profiles were compared.

RESULTS

It was observed that the materials released fluoride at different levels of concentration and the largest fluoride release was obtained from the conventional glass ionomer cement. This was followed by resin modified glass ionomer cement, polyacid modified composite resin, and fluoride releasing composite resin, respectively. Although the released fluoride amounts of the materials were different, their release profiles were found to be similar in that the release was initially fast and then it became steady as time passed.

SIGNIFICANCE

The statistical modeling of the release profiles helps to compare the fluoride release behavior of materials and also to predict fluoride release amounts for the future. In literature, for these purposes, separate nonlinear statistical models have extensively been utilized. However, the single linear statistical modeling approach has numerous advantages such as providing estimators having good statistical properties, exact results, precise inference and simplicity in calculation. Therefore, this study was conducted to introduce the use of single linear regression modeling to compare release profiles statistically.

Efficacy of subgingival irrigation using herbal extracts on gingival inflammation

BACKGROUND

The aim of the present study was to investigate the efficacy of an herbal-based mouthrinse in combination with an oral irrigator in reducing gingival inflammation.

METHODS

A total of 89 patients (45 females, 44 males; mean age 49.1 +/- 1.31 years) were included in this prospective, randomized, double-blind clinical study and allocated to 3 treatment groups: group 1 (n = 34), treated with an oral irrigator with subgingival tips and an herbal-based mouthrinse; group 2 (n = 29), the oral irrigator was applied in combination with a conventional mouthwash; and group 3 (n = 26), treated with the conventional mouthwash without subgingival irrigation. Data collected at baseline and after 4, 8, and 12 weeks included gingival index (GI), sulcus bleeding index (SBI), plaque index (PI), and probing depth (PD).

RESULTS

Over a period of 3 months, GI decreased from 1.80 +/- 0.04 to 1.56 +/- 0.04 in group 1; from 1.79 +/- 0.05 to 1.68 +/- 0.04 in group 2; and remained nearly constant in group 3 (from 1.79 +/- 0.05 to 1.81 +/- 0.04). Differences between the groups were significant (analysis of variance, P < 0.05). SBI values in group 1 were reduced from 2.51 +/- 0.06 to 2.13 +/- 0.06 after 3 months and were significantly lower than in group 2 (P = 0.001) and 3 (P = 0.002), with SBIs of 2.44 +/- 0.06 and 2.42 +/- 0.07, respectively, after 12 weeks. A reduction in PI was noted for all 3 groups throughout the follow-up period, with no statistically significant differences. Probing depths were not reduced significantly in any group.

CONCLUSION

Subgingival irrigation with an herbal-based mouthrinse led to a significant reduction in both SBI and GI. This regimen can, therefore, be recommended as an adjunctive procedure to reduce gingival inflammation.

Fluoride-releasing restorative materials and secondary caries

Secondary caries are responsible for 60% of all replacement restorations in the typical dental practice. Risk factors for secondary caries are similar to those for primary caries development. Unfortunately, it is not possible to predict accurately which patients are at risk for restoration failure. Fluoride-releasing dental materials provide for improved resistance against primary and secondary caries in coronal and root surfaces and have become a part of the dentist's armamentarium. This article discusses the improvement in the properties of dental materials with the ability to release fluoride. It is anticipated that in the near future, the vast majority of restorative procedures will employ fluoride-releasing dental materials as bonding agents, cavity liners, luting agents, adhesives for orthodontic brackets, and as definitive restoratives.