Effect Of Different Clean Methods For Removable Partial Denture On The Surface Topography Of The Casting Stent

Objective:This in vitro study aimed to evaluate the effect of different clean methods for removab le partial denture on the surface topography of the casting stent that simulated 180 days of cleaning.Methods:Thirty-five centrifugal casting co-cr alloy metal samples 、 thirty-five pure titanium metal samples and thirty-five centrifugal casting Vitallium 2000+ alloy metal samples(15mm ×10 mm × 1 mm)were prepared and highly polished.Every metal samples were randomly divided into five groups.The black control group A was immersed in distilled water.B,C,D and E groups were experimental groups as follows.Group B was brushed with distilled water.Group C was brushed with a dentifrice.Group D was immersed in Polident solution.Group E was brushed with Polident solution,simulating to use 180 days.A surface analyzer was used to measure the roughness(Ra)of samples before and after treatment.The samples among the five groups were subjected to scanning electron microscopy before and after treatment.Results:1.Co-cr alloy metal samples:(1)the mean roughness of A and D groups comparing pre and post-treatment were:(0.003784±0.0019954/0.004186±0.0012747)、(0.005100±0.0016733/0.005043±0.0013963),No significant differences were seen after treatment(p>0.05).the mean roughness of B,C and E groups comparing pre and post-treatment were:(0.003714±0.0010172/ 0.037614 ±0.0032555)、(0.004329 ±0.0008341 /0.185243±0.0536375)、(0.005514± 0.0014041/0.014530±0.00122613),significant differences were seen after treatment(p<0.01).(2)the mean roughness were compared between groups:There was no statistically significant difference between groups before treatment(P>0.05).The mean roughness of the five groups were not all the same after different ways of treatment.Compared with group A(control group),the mean roughness of group D was slightly increased,there was no statistically significant difference after treatment(P>0.05).The mean roughness of B,C and E groups were significant difference after treatment(P<0.05).There were significant differences between Group B,Group C and Group E.(3)The SEM observation of A,B,D and E groups of sample surface had not obvious scratch after different treatment,The surface of C group was obviously scratched compared with per-treatment.2.Pure titanium metal samples:(1)The mean roughness of A group comparing pre-treatment and post-treatment were: 0.0573 ± 0.0101/0.0584 ± 0.0095,No significant differences were seen after treatment(p > 0.05).The mean roughness of B,C,D and E groups comparing pre-treatment and post-treatment were:(0.0576 ± 0.0063/0.1480 ±0.0112)、(0.0566±0.0084/0.2590±0.0322)、(0.0580±0.0090/0.0996±0.0146)、(0.0571±0.0105/0.1530±0.0126),significant differences were seen after treatment(P< 0.05).(2)The mean roughness were compared between groups: There was no statistically significant difference between groups before treatment(P>0.05).The mean roughness of the five groups were not all the same after different ways of treatment.Compared with group A(control group),the mean roughness of B,C,D and E groups was increased,there was statistically significant difference after treatment(P>0.05).The mean roughness of B and E groups were no significant difference after treatment(P < 0.05).There were significant differences between other groups after treatment(P>0.05).(3)The SEM observation of A and D groups of sample surface had not obvious scratch after different treatment.The sample surface of B and E groups had slight scratch.The sample surface of C group was obviously scratched compared with per-treatment.3.Vitallium2000+ alloy metal samples:(1)The mean roughness of A group comparing pre-treatment and post-treatment were: 0.0045 ± 0.0011/0.0047 ± 0.0010,No significant differences were seen after treatment(p > 0.05).The mean roughness of B,C,D and E groups comparing pre-treatment and post-treatment were:(0.0049 ± 0.0011/0.0168 ±0.0025)、(0.0048±0.0013/0.0322±0.0064)、(0.0051±0.0011/0.0072±0.0012)、(0.0052 ± 0.0011/0.0198 ± 0.0032),significant differences were seen after treatment(P<0.05).(2)The mean roughness were compared between groups: There was no statistically significant difference between groups before treatment(P>0.05).The mean roughness of the five groups were not all the same after different ways of treatment.Compared with group A(control group),the mean roughness of group D was slightly increased,there was no statistically significant difference after treatment(P>0.05).The mean roughness of B,C and E groups were significant difference after treatment(P<0.05).There were significant differences between Group B,Group C and Group E.(3)The SEM observation of A and D groups of sample surface had not obvious scratch after different treatment.The sample surface of B and E groups had slight scratch.The sample surface of C group was obviously scratched compared with per-treatment.Conclusion:1.The way of immersing in Polident solution would slightly increase the surface roughness but no scratch.2.The way of brushing with distilled water or Polident solution would slightly increase the surface roughness and would slightly produce scratch.3.The way of brushing with dentifrice would obviously increase the surface roughness and produce obviously scratch.