ผลของความหนาและวิธีการบูรณะต่อความแข็งผิวระดับจุลภาคของเรซินมอดิฟายด์กลาสไอโอโนเมอร์ซีเมนต์ / ชุติมา ศรีวณิชชากร = Effects of thickness and restorative techniques on microhardness of resin-modified glass-ionomer cements / Chutima Srivanichakorn
Resin-modified glass-ionomer cements (RMGIs) is a restorative material that is suitable for use in patients with high caries risk and deciduous teeth. The cavities in these cases are deep and progress easily. The purpose of this study was to evaluate the effects of RMGIs, the thickness and the restorative techniques on the microhardness numbers. The materials (Fuji II LC® , Vitremer® and Ketac N100® ) were placed in different thicknesses (2, 3, 4, and 5 mm.) on 4 mm-in-diameter stainless steel molds using bulk and increment techniques . For the bulk technique, each specimen was photopolymerized after the exact thickness of the material was created. For the incremental technique, the specimen was photopolymerized every 2 mm. Each specimen was photopolymerized according to the manufacturers’ instructions. The microhardness of all specimens was tested by Knoop hardness indenter at 15 minutes, 1 day, 1 week and 1 month after fabrication on the top and bottom surfaces. Results showed that the average microhardness numbers in the bulk groups were significantly different between the top and the bottom surfaces. RMGIs, restorative techniques and thickness showed effects on the microhardness numbers. In order to obtain the fully polymerization of the RMGIs which is based on acid-base reaction and light initiation, the incremental technique is recommended in case of more than 2 mm. in thickness of the material is to be placed.