Comparative Study Of The Phosphate Expansion With Three Different Heating Methods For Ager

Objective: By using three heating methods including microwave, traditional waterbath and agar melting machine, we do a comparative study about the phosphateexpansion of these heating methods for ager. And explore that if there any differencebetween the phosphate models’ expansion after they solidified1hour and24hourslater. Thus searching for the best way to heating agar and provide the theoretical basisfor the heating method and best casting time.（Method: Choosing6inner cores of standard10ml glass syringes and divide theminto groups A, B and C, each group with2inner cores. Stabilize them onto three plasticbox which have holes in them with the same parallel distances, the inner cores shouldbe kept in touch with the bottom of the box. Three groups of agar melted bymicrowave method, water bath method and agar melting machine method, and intoeach of the three boxes. Put the6inner core syringes heading down into the box, andtake the inner core syringes out after the agar getting cold. Mixing phosphate powderand distilled water according to the factories’ proportion, then put the phosphate intothe agar molds. After1hour later, take the phosphate models out. Each group repeatedthe experiment20times. Measure all the phosphate material mold samples by usingthe micrometer. Measure the samples again after24hours later. Record the agar weightbefore and after each use, compared the1～20times solidification phosphate sampleexpansion in each group and compared the phosphate sample expansion between thethree groups. Explore the difference between the phosphate model expansion after theysolidified1hour and24hours later. The testing result will be analyzed by SPSS19.0 statistics software.Result: The new agar in each group has used for20times, and the water loss isabout69%in microwave method group, the water loss is about30.25%in water bathmethod group, and the water loss is about27.8%in agar melting machine group. In the20times, when the agar was used1～7times, the three groups of phosphate modelexpansion has no significant difference(P＞0.05). And when they used8～20times,the three groups of phosphate model expansion has obvious difference(P＜0.05),among these results, the agar melting machine group has no difference with the waterbath group((P＞0.05), the microwave method group has obvious difference with thewater bath group and the agar melting machine group((P＜0.05).The phosphate modelexpansion after they solidified1hour and24hours has no significant difference(P＞0.05).Conclusion: Among the three kinds of heating methods of agar, the microwavemethod group has the largest water loss. When the agar was used less than7times, thethree methods have no difference between each other, starting from the8th times, thephosphate model expansion in the microwave method group has obvious differencewith the other two groups, but the phosphate model expansion in water bath group andin agar melting machine group have no difference from each other. Microwave methodhas a greater impact of the phosphate model expansion than the other methods, so theagar should be avoid to continue to use when using7times or so, but this method ismore convenient than other two methods, and can be used in emergency situations. Thephosphate model expansion after solidified1hour and24hours has no significantdifference. The Phosphate’s setting time doesn’t have great effect on its settingexpansion and hydroscopic expansion.