Infiltration of natural caries lesions with experimental resins differing in penetration coefficients and ethanol addition.
Abstract
Resin infiltration of enamel caries lesions requires materials optimized for penetration into the capillary structures of the lesion body. With increasing penetration coefficients (PC), improved penetration and caries-inhibiting properties of low-viscosity resins (infiltrants) could be observed in artificial caries lesions. The aim of the present in vitro study was to compare the ability of experimental resins varying in PC and ethanol addition to penetrate into natural caries lesions using this technique.
Extracted human molars and premolars showing proximal white spot lesions (International Caries Detection and Assessment System: code 2) were etched for 2 minutes, using 15% hydrochloric acid gel. After drying, the lesions were stained with tetramethylrhodamine isothiocyanate, and 1 of 4 experimental resins (PC63; PC185; PC204; PC391) was applied for 5 minutes. The materials consisted of bisphenol-A-glycidyl-methacrylate (B), tri-ethylene-glycol-dimethacrylate (T) and ethanol (E) in ratios (B:T:E) of PC63: 25:75:0; PC185: 20:60:20; PC204: 0:100:0; PC391: 0:80:20. Excess material was removed before light curing. The teeth were sectioned perpendicularly to the lesion surfaces, and unbound dye was bleached by immersion in hydrogen peroxide. The remaining lesion pores were stained with fluorescein solution. Confocal microscopy (n = 60) was used to analyze lesion and penetration depths. Compared to PC63 and PC391 (P < .05; Mann-Whitney test), the percentage penetration of PC204 was significantly higher at deep lesion sites, but only slightly higher than PC185 (P > .05). It can be concluded that materials with high PC (infiltrants) are capable of penetrating almost completely into enamel parts of natural caries lesions in vitro. A solvent-free resin consisting mainly of triethylene glycol dimethacrylate seems to be preferable.
Commentary
In this past year, a novel technique using resin infiltration for the treatment of white-spot carious lesions has been introduced. Compared to sealants, the use of resin to treat white-spot lesions provides significant challenges, because there is no way to bond predictably to the demineralized enamel surface. This study presents the development of a resin infiltrate for the treatment of this porous enamel. The porous enamel layer is removed and etched with a 15% hydrochloric acid gel for 2 minutes, then a specially designed enamel penetrating resin infiltrate is placed that works better than conventional dental resins. For clinicians, this means a therapeutic regimen that will inhibit the progression of smooth-surface white-spot lesions in oral hygiene and preventive protocols for non-compliant patients. This is an especially useful treatment of initial non-cavitated caries lesions on proximal surfaces. A resin infiltrate to treat proximal surfaces is available using a specialized device (Icon, DMG America LLC, www.dmg-america.com) to create proximal separation combined with a pressure infuser of the resin.
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