IM0410

I research _ dental surfaces 18 I implants4_2010 initial baseline measurement the amount of enamel wear that occurred during the experiment (in mi- crons) was determined. A custom jig made from an aluminium block with a locking set-screw ensured that the abrader rod (and enamel sample) could be repositionedinthesamelocationonthetableofthe digital micrometer (Fig. 9) when taking measure- ments. This meant all enamel measurements were made with the cross-hair marks on the abrader rod in the same focal plane for both the baseline and post-wear measurements. At each measurement “reference position 1” was lined up with the locking set screw on the custom jig so all measurements were completed in the same clockwise sequence. All measurements were completed by the same ob- server to avoid inter-observer error and each meas- urement for each reference position was made five times (arithmetic mean determined) to ensure all readings were accurate. Each enamel sample was held perpendicular to the test substrate to ensure uniform wear. Enamel samples were initially run in the wear machine against 600 micron grit silicon carbide paper in the artificial saliva medium to produce a smooth, uni- form flat surface with at least 0.5 mm thickness of enamel remaining. The sample was then removed from the wear machine and baseline enamel length figures were recorded as outlined above. The test block was then placed in the water bath filled with saliva substitute and positioned on the wear ma- chine. Enamel specimens were then passed through the rotating drum in the holding sleeve and lined up ontheappropriatetestsample.Anunloadedtestcy- cle (1 revolution) was carried out to ensure the enamel was abrading around the centre of the test specimen. The test block was then secured to the wear machine by means of two C-clamps. The 500g loadwasappliedtotheabraderrodandthewearma- chinewasactivatedataspeedof65rpmandrunfor exactly 10,000 cycles. The process was repeated for each test sample in each test group (Figs. 10 & 11). The amount of wear experienced by the test sur- face after being abraded by human enamel was also determined. This was achieved by using a laser videography procedure that involved scanning the samplesurface(preandpostenamelabrasion)tode- terminehowmuchwearthetestsurfaceexperienced from abrasion by human enamel. Thus the total amountofwearinmicronsthatoccurredwithinthis two-body wear system—enamel plus substrate— wasdetermined.Thiswasequalto100%ofthetotal wear occurring in that sample group. By converting the micron loss figures to a ratio the percentage enamel wear figures were determined. The data ob- tained was analyzed using a 0ne-way ANOVA sta- tisticalanalysiswithasignificancelevelofP=0.05. Fig. 11_Enamel wear micron loss zirconia vs gold. Fig. 12_Enamel wear percentage loss zirconia vs gold. Fig. 13_Enamel wear wear micron loss polished surface finish. Fig. 14_Enamel wear percentage loss polished surface finish. Fig. 13 Fig. 14 Fig. 11 Fig. 12