The measurement of degradation and wear of three glass ionomers following peroxide bleaching.
OBJECTIVE
To investigate, for three glass ionomer dental materials, the effects of a hydrogen peroxide solution on the elution of key elements, and the effects of a novel 6% hydrogen peroxide tooth whitening gel on subsequent wear rates with a toothpaste slurry.


METHODS
Discs specimens of three glass ionomers (ChemFlex, Fuji II and Ketac-Fil) were prepared. One set of discs was exposed to either 6% hydrogen peroxide in phosphate buffer, phosphate buffer, water, a carbonated beverage or 38% orthophosphoric acid for 60 min. The ions eluted from the discs were determined by inductively coupled plasma-optical emmision spectroscopy. A second set of discs were conditioned with either a 6% hydrogen peroxide gel (30 min), water (30 min), a carbonated beverage (2 min) or 38% orthophosphoric acid gel (2 min) followed by a three-body abrasive wear treatment (2 min) with a toothpaste slurry. Changes in height of the samples were measured with a digital comparitor. The conditioning and abrasive cycles were repeated thirteen times.


RESULTS
For the elution study, the solutions gave only minor release of sodium except orthophosphoric acid which showed increased elution levels of aluminium, silicon and sodium ions. For the wear study, the orthophosphoric acid gave the highest level of wear whilst for the other treatments there were no statistical significant differences in the level of wear (one-way ANOVA).


CONCLUSIONS
A 6% hydrogen peroxide solution did not cause significant dissolution, and a novel 6% hydrogen peroxide tooth whitening gel did not significantly increase the three-body wear rate of any of the materials tested.
Mair
Lawrence
L
Dental Department of Clinical Dental Sciences, Liverpool Dental School, University of Liverpool, UK. l.h.mair@liv.ac.uk
Joiner
Andrew
A
D000535:Aluminum / Q000737:chemistry; D000704:Analysis of Variance; D002253:Carbonated Beverages; D019554:Dental Restoration Wear; D005782:Gels; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008298:Maleates / Q000737:chemistry; D008422:Materials Testing; D016877:Oxidants / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014073:Tooth Bleaching; D014100:Toothpastes / Q000737:chemistry; D014867:Water / Q000737:chemistry
C410563:ChemFlex; D005782:Gels; D005899:Glass Ionomer Cements; D008298:Maleates; D016877:Oxidants; D010710:Phosphates; D010756:Phosphoric Acids; D014100:Toothpastes; D014867:Water; C084541:Fuji glass-ionomer lining cement; C040964:Ketac-Fil; D012964:Sodium; D006861:Hydrogen Peroxide; D000535:Aluminum; D012825:Silicon