The effect of layered double hydroxide on fluoride release and recharge from a commercial and an experimental resin varnish.

OBJECTIVES: Layered Double Hydroxide (LDH) is capable of fluoride anion exchange and release. This study investigated the effects of incorporating ZnAl-LDH in commercial and experimental dental varnishes, on fluoride release and re-release after charging in NaF. METHODS: Five discs of each material (commercial ClinproXT varnish and experimental light cured resin varnish), with and without 9%ZnAl-LDH were immersed and agitated in deionised water (DW) at 37 °C. A fluoride ion selective electrode measured fluoride release in DW daily over two-weeks. At 3, 6, 9 and 12 days the discs were recharged in 15 ml 0.05 M NaF solution (37 °C) for five minutes followed by immersion in DW. Energy dispersive X-ray spectra (EDS), weight changes and SEMs were performed on discs, before and after each cycle. RESULTS: Evidence of ZnAl-LDH was confirmed by the presence of peaks for zinc and aluminium in EDS spectra. Cumulative fluoride and mean fluoride released between Clinpro, Clinpro + LDH and resin were significantly different (ANOVA, Tukey's HSD post-hoc test, p < 0.001) except between the resin and resin + LDH. Mean fluoride concentrations differed significantly after every recharge between Clinpro, Clinpro + LDH and resin, but not between the resin and resin + LDH (p < 0.01). The weights and SEMs of the experimental resins +/-LDH, appeared to be stable whilst the weights of Clinpro samples +/-LDH, fluctuated and fragmented. SIGNIFICANCE: ClinproXT and experimental resin containing ZnAl-LDH recharged with fluoride did not significantly increase fluoride release compared to the unmodified materials. However, all LDH-F incorporated materials demonstrated fluoride recharging properties which appear beneficial to dentistry and thus further work is required to improve these properties.

Direct Composite Resin for the Management of Tooth Wear: A Systematic Review.

BACKGROUND: This study systematically reviewed survival of direct composite to restore worn teeth. MATERIALS AND METHODS: A comprehensive electronic search of databases sourced from Medline-PubMed, Embase, Cochrane Central, Scopus, Google scholar was performed on literature published between January 1990 and December 2018. Grey literature was also reviewed. Data extraction included sample size, number of composite restorations, operators, composite type, mean or total follow-up time and success rate expressed as either percent of successful restorations or median survival time (MST). Methodological quality was rated using the Joanna Briggs Institute appraisal checklist for case series. Studies on children, non-carious cervical lesions, cast and all-ceramic restorations, case reports and case series with <5 participants were excluded. RESULTS: A total of 1563 studies were identified and 1472 were screened. Sixty-two full-text papers were assessed for eligibility which resulted in 10 studies that met inclusion criteria. These were mainly case series and assessed 3844 direct composite restorations placed in 373 patients mostly in hospital settings. Survival ranged from 50% to 99.3%. Methodological quality improved from the earlier studies and was rated low to moderate in 7 studies and good in 3. The funnel plot showed a low risk of publication bias but there was considerable heterogeneity (I2=97.7%). There was a non-significant weak negative association between age and survival (Spearman's rho=-0.12). CONCLUSION: Qualitative evaluation of the studies proved difficult because of the nature of case series but reporting improved in the later studies. Despite the generally short duration of studies, small sample sizes in terms of patient numbers and composite restorations, the survival rates of direct hybrid composite resin in the short to medium term are acceptable and support their application for the restoration of worn teeth.