Xylitol concentrations in artificial saliva after application of different xylitol dental varnishes

Xylitol associated or not with fluoride: Is the action the same on de- and remineralization?

OBJECTIVES

This study evaluated the effect of xylitol combined or not with fluoride (F) on reduction of demineralization and increase of remineralization of shallow and deep artificial enamel lesions.

METHODS

Bovine enamel samples were allocated to the following solutions groups: no xylitol (negative control), 5% xylitol, 10% xylitol, 20% xylitol, 500 ppm F (as NaF), 5% xylitol+F, 10% xylitol+F or 20% xylitol+F (n = 12-15). For the demin study, a pH-cycling model (demineralization-6 h, pH 4.7/remineralization 18 h, pH 7.0) was employed for 7 days. Treatments were applied 2 × 1 min. In the remin study, specimens were pre-demineralized for 2, 5 or 10 days. Afterwards, a pH-cycling protocol was conducted (2 h demineralizing and 22 h remineralizing solution/day for 8 days) and the same treatments were done. The response variables were percentage surface hardness loss (%SHL) and transverse microradiography. Data were analyzed by RM ANOVA/Tukey or Kruskal-Wallis/Dunn (p < 0.05) RESULTS: F and Xylitol combined with F reduced the %SHL (23-30%) compared to the negative control (61.5%). The integrated mineral loss and the lesion depth were not reduced by any treatment. Surface hardness recovery was seen only for shallow lesions in case of 20% xylitol+F compared to negative control. No lesion depth recovery, but significant mineral recovery was seen for F (2-days and 10-days lesion).

CONCLUSIONS

All concentrations of xylitol+F reduced enamel surface demineralization, while only 20% xylitol+F improved surface remineralization of shallow lesions in vitro.

CLINICAL SIGNIFICANCE

Our results suggest that while F or any concentration of xylitol + F reduces surface demineralization, only 20% xylitol+F improves surface remineralization of shallow lesions in vitro. Therefore, xylitol may be added into oral products, combined to F, to control dental caries.

Effect of xylitol varnishes on enamel remineralization of immature teeth: in vitro and in situ studies

BACKGROUND

We evaluated the efficacy of xylitol varnishes on the remineralization of newly erupted permanent and deciduous teeth in vitro and in situ. Human enamel specimens were randomly allocated to 8 groups (n = 15/group). Artificial caries lesions were produced and enamel alterations were quantified by surface/subsurface hardness and transverse microradiography. The blocks were then treated with the following varnishes: DuraphatTM; 20 wt% xylitol (146 μm) varnish; 20 wt% milled xylitol (80 μm) varnish, and placebo varnish, and removed after 6 h of immersion in artificial saliva. The blocks were subjected to pH-cycles for 8 days.

CONCLUSIONS

fifteen subjects wore palatal appliances containing four pre-demineralized and treated enamel specimens, for 5 days. Data were statistically analyzed by ANOVA/Tukey and Kruskal-Wallis/Tukey's test (p < 0.05). The %SHR in both studies was significantly increased by xylitol and Duraphat™ varnishes when compared to placebo. Considering subsurface remineralization, only the xylitol varnishes were able to significantly reduce the enamel lesion. Xylitol varnishes can be promising alternatives to promote enamel remineralization of newly erupted permanent and deciduous teeth.

Evaluation of the preventive effect of two concentrations of xylitol varnish versus fluoride varnish on enamel demineralization around orthodontic brackets: a randomized controlled trial

BACKGROUND

The highly prevalent white spot lesions around orthodontic brackets necessitate introducing preventive materials without relying on patient compliance.

OBJECTIVE

To evaluate the antidemineralizing effect of two concentrations of xylitol varnish.

TRIAL DESIGN

Triple-blind, four-arm, parallel-group, single-center, randomized controlled clinical trial.

METHODS

A total of 120 orthodontic patients were randomly assigned to four groups (n = 30), using a computer-generated randomized block list. The treatment groups were: 10% xylitol, 20% xylitol, 5% fluoride, and placebo. Tooth demineralization was measured with DIAGNOdent at T1 (before treatment), followed by varnish application. At T2 (third month), the varnish was re-applied, and at the third (T2) and sixth (T3) months, and after treatment (T4), the demineralization was measured. The white spot lesion frequency was assessed visually after treatment. The participants, the clinician, and data assessors were all blinded to group assignments.

RESULTS

A total of 115 patients underwent per-protocol analyses. At T2, the mean DIAGNOdent numbers in the fluoride and 10% xylitol groups were significantly lower than the placebo group (P = 0.00), with a mean difference of 0.63 (95% CI, 0.15-1.10) and 0.5 (95% CI, 0.04-0.95), respectively. At T3, the fluoride and 10% xylitol groups had significantly lower mineral loss than the placebo group (P=0.046) with a mean difference of 0.52 (95% CI, 0.14-0.89) in the fluoride and 0.45 (95% CI, 0.03-0.86) in the 10% xylitol groups, respectively. However, at T4, only the mean for the 10% xylitol group was significantly different (P=0.049) from the placebo group, with a mean difference of 1.18 (95% CI, 0.42-1.93). Visual assessment showed that after treatment, the prevalence of white spot lesions in the fluoride (P=0.03) and 10% xylitol (P=0.00) groups was less than the placebo group with the odds ratio of 0.67 (95% CI, 0.46-0.96) and 0.43 (95% CI, 0.28-0.64), respectively.

CONCLUSION

The 10% xylitol varnish short-term effects on caries control were significantly greater than 20% xylitol varnish and placebo but similar to fluoride varnish. However, the 10% xylitol long-term effect was almost better than fluoride varnish.

TRIAL REGISTRATION

The protocol was registered at IRCT.ir under the code IRCT20180913041032N1.

Prevention of non-cavitated lesions with fluoride and xylitol varnishes during orthodontic treatment: a randomized clinical trial

OBJECTIVE

Fixed orthodontic appliances impair oral hygiene increasing the risk of non-cavitated lesions (NCLs) and tooth decay. The aim of this study was to compare the outcomes of fluoride and xylitol varnishes in preventing NCLs during comprehensive orthodontic treatment.

MATERIALS AND METHODS

The sample comprised 55 volunteers from 15 to 20 years of age under orthodontic treatment that were randomly divided into three groups: Fluoride Group (FG; n=17), Xylitol Group (XG; n=19), and Placebo Group (PG; n=19). The patients in each group received two applications of the following varnishes: Duraphat^TM (5% NaF), 20% xylitol, and placebo (no F/Xylitol) in the three groups, respectively. The varnishes were applied in the first appointment (T0) and 3 months later (T1). Clinical examinations were carried out at T0 and 6 months after (T2) using the ICDAS index and the QLF system (fluorescence difference). The intergroup comparisons were performed by ANOVA/Tukey's or Kruskal-Wallis/Dunn's tests (P<0.05).

RESULTS

There was no significant intergroup difference regarding ICDAS index changes from T0 to T2. Fluoride varnish produced significantly greater increase in fluorescence of NCLs (mean change of -0.65 +0.78 and -0.56 +0.83, for maxilla and mandible, respectively) in comparison to the other groups. The majority of non-cavitated lesions improved in the fluoride and xylitol varnish groups.

CONCLUSIONS

Fluoride varnish produced significantly greater increase in enamel fluorescence compared to xylitol and placebo varnishes. In short term, both fluoride and xylitol varnishes produced remineralization of NCLs in orthodontic patients.

CLINICAL RELEVANCE

Non-cavitated lesions can be effectively controlled in high-risk orthodontic patients by means of fluoride varnishes.

CLINICAL TRIAL REGISTRATION

ReBEC Identifier: RBR-6mdxfq; Date of Register: March 19th, 2020. Retrospectively Registered.

Selective hydrolysis of hemicellulose from wheat straw by a nanoscale solid acid catalyst

A nanoscale catalyst, solid acid SO4(2-)/Fe2O3 with both Lewis and Brønsted acidity was found to effectively hydrolyze hemicellulose while keeping cellulose and lignin inactive, and selective hydrolysis of hemicellulose from wheat straw by this catalyst was also confirmed. The factors that significantly affected hydrolysis process were investigated with response surface methodology, and the optimum conditions for time, temperature, and ratio of wheat straw to catalyst (w/w) were calculated to be 4.10h, 141.97°C, and 1.95:1, respectively. A maximum hemicellulose hydrolysis yield of 63.5% from wheat straw could be obtained under these conditions. In addition, the catalyst could be recycled six times with high activity remaining.