Effect Of Penetrability Of Resin Infiltration On Laser Treatment For White Spot Lesions

Objectives: The aims of this study were to investigate an alternative pretreatment method for resin infiltration using Er, Cr: YSGG laser to evaluate the penetration effect of the infiltrant for masking the natural white spot lesions(WSLs) in human teeth. Methods: Twenty-four extracted human molars and pre-molars with non-cavitated WSLs were collected. These teeth met criteria of ICDAS code 2, and were cut in paired halves, and each piece were randomly numbered group 1 or group 2, those were the A(A1, A2), B(B1, B2). Group A1 and B1 were etch groups(control groups) and these specimens were treated with 15% HCl gel applied for 120 s. Group A2 and B2 were was laser groups(experimental groups) and these specimens were irradiated by 1.75 W Er, Cr: YSGG(A2), 2.0W Er, Cr: YSGG(B2). Also, to evaluate the penetration effect of the infiltrant by pretreatment, the specimens were treated with the Icon-Infiltrant. Micro-morphological changes of teeth surface were observed by Environmental scanning electron microscope(ESEM). The Infiltrated depth and was evaluated by laser scanning confocal microscope(LSCM). Results: 1. After 1.75 W and 2.0W Er, Cr:YSGG laser irradiation, the ESEM images show that, the ablated surface was honeycomb-like and pebble-like appearance because of dissolved central part of in some enamel prism and dissolved periphery of in other enamel prism. However, the images of etch group shows honeycomb image because of dissolved central part of enamel prism. 2. In the LSCM images, laser group and etch group have good permeability, the effect of resin infiltration was significant. 3. The Infiltrated depth revealed that applying 1.75 W or 2.0W Er, Cr: YSGG laser for 15 s could obtain good permeability. The effect of resin infiltration was similar to the control group which was pretreated 15% HCl gel for 120 s in vitro study(P >0.05). Conclusions: Irradiating the surface of natural WSLs with 1.75 W or 2.0W Er, Cr: YSGG laser for 15 s could produced a pattern similar to a etched pattern produced by acid etching. Moreover, the effects of resin infiltration was similar to the control group which was pretreated 15% HCl gel for 120 s in vitro study.