The effects of fractional CO2 laser, Nano-hydroxyapatite and MI paste on mechanical properties of bovine enamel after bleaching

Abstract

BackgroundThis study investigated the effect of post bleaching treatments to the change of enamel elastic modulus and microhardness after dental bleaching in- vitro.Material and MethodsFifty bovine incisor slab were randomly assigned into five groups (n=10). The samples were bleached for three times; 20 minutes each time, by 40% hydrogen peroxide. Next it was applied fractional CO2 laser for two minutes, Nano- hydroxy apatite (N-HA) and MI-paste for 7 days and 2 minutes per day. The sound enamel and bleached teeth without post treatment remained as control groups. The elastic modulus and microhardness were measured at three times; 24 hours, 1 and 2 months. Data were statistically analyzed by two-way analysis of variance with 95% confidence level.ResultsDifferent methods of enamel treatment caused a significant increase in elastic modulus compared to bleached group (P<0.05). Modulus was significantly increased in 1 and 2 months (P<0/001: bleach, P= 0/015: laser, P= 0/008: NHA, P=0/010: MI paste) but there were no significantly difference between 1 and 2 months (P>0.05). There was any significance difference for hardness among treated and control groups, but hardness increased significantly by increasing storage time (P<0.05).ConclusionsThe use of the protective tested agents can be useful in clinical practice to reduce negative changes of enamel surface after whitening procedures. Key words:Bleaching enamel, CO2 laser, MI pastes, Nano-hydroxy apatite, Microhardness, Elastic modulus.

Topic: Complications and side effects of dental whitening procedures

“…On each bleached tooth, regardless of the bleaching technique applied, there is a reduced potential for temporary bonding between the bond and the composite.Residual oxygen from peroxide residues prevents the xation of the bonding bond. 5,6,23,35,57,78,89,112 This is prevented by performing all conservative therapeutic dental restorations, 1 week after the last teeth whitening procedure, ie 1 week after the whitening is completed.…”

“…For internal whitening, in teeth previously treated with endodontic treatment, the literature reports 1% chance of cervical resorption especially in cases of whitening with thermocatalytic techniques.This percentage is signi cantly reduced by the application of calcium hydroxide mixed with distilled water in paste form, to the ori ce of teeth that have undergone internal teeth whitening treatment.Although, it is worth mentioning that the thermocatalytic technique is a procedure that is no longer recommended, in terms of the evolution of internal bleaching techniques. 7,12,23,26,28,45,47,57,76,78,89,110 Whitening of vital teeth in the conditions of the dental clinic as a side effect is mentioned the change of color and loss of integrity of the restorative material of polymethyl methacrylate PMMA during exposure with peroxide ofcarbamide.Therefore, temporary crowns are best modeled with bis-acrylics. 9,32,63,105 Moderate-grade sensitivity to teeth whitening procedure in dental clinic conditions is known to occur posttreatment, as hydrogen peroxide has ability to pass easily through enamel and dentin but does not cause pulp damage.For this sensitivity, it is indicated to give light analgesics to the patient, as it is yesterday which lasted a maximum of 24 hours after bleaching.…”

Efecto del uso de dentífricos aclaradores sobre la estructura y superficie del esmalte dental

“…En este estudio observamos cambios en la superficie del esmalte los cuales parecen indicar son debido al tiempo de exposición de las pastas blan- queadoras las cuales afectan la estructura y dureza adamantina y generan diferencias significativas en la microdureza del tejido adamantino aumentándola a los 28 días de exposición y cepillado dental no así en tiempos menores. Moosavi y col. estudiaron el efecto de los tratamientos posteriores al blanqueamiento y microdureza del esmalte dental in vitro; examinaron, con un microscopio electrónico de barrido, las superficies del esmalte de modelos dentales bovinos mediante diferentes tratamientos e identificaron cambios en la superficie del esmalte el cual mostraba porosidades, depresiones y alteraciones de diversos grados en su superficie, relacionando la dureza del esmalte con la eliminación del contenido mineral del mismo (16). En el presente estudio se utilizaron órganos dentarios humanos sanos extraídos, se analizaron en el microscopio electrónico de barrido y se observó con el uso de pastas blanqueadoras abrasión, patrones de grabado (por el tipo de dentífrico) y desmineralización del tejido adamantino, probablemente por el uso de agentes de remineralización así como agentes de relleno y abrasivos que conducen a estas diferencias.…”

Raman Analyses of Laser Irradiation-Induced Microstructural Variations in Synthetic Hydroxyapatite and Human Teeth

“…The biocompatible white layer applied as a thin surface cover on tooth enamel could adhere to the tooth surface without affecting or chemically altering the deeper tooth tissue, but assumed to reflect more light than the more transparent natural enamel to achieve the whitening effect [ 11 ]. Hydroxyapatite coatings can be achieved by laser irradiation, suggesting that this method may be used for repairing the damaged enamel surface after power bleaching [ 12 , 13 ]. Despite that, it has been known that both the organic component and the inorganic minerals in tooth enamel can be affected by the marked rise of local temperature induced by laser irradiation [ 14 ].…”