The Influence Of Gilding To The Retention Of The Complete Metal Crowns

Objectives: This study aims was to gild in different part of tissue surface of metal complete crown,to make a lamellar gold cover to the tissue surface of the crown,to improve the biologic efficiency of metal complete crown.Measured the retention size of common metal complete crown and gilt metal complete crown, to get the message of chang information of the retention,to get reference for clinicist alternative to use gilding no-precious- metal-ceramic crown.Methods: Choosed a normal appearance maxillary first premolar,chipping the dental root,to make its length remains 8mm,the dental axial ray was at equal pace with tooth axial ray. To make the root embed in backing of self-made circular cylinder selfcuring acrylic resin,dental crown axial ray was at equal pace with circular cylinder axial ray and vertical with horizontal plane,the diameter of the backing was 8mm,the height of the backing was 10mm.To embed 2mm below the abutment cervical margin. Uniformity strippinged 2mm on occlusal surface,grinded 900 shoulder with dental beveller,the width of the shoulder was 0.80mm,the degree of polymerization was 50 . To get the tooth model with methyl silicone rubber,to make teeth wax pattern,got a Co-Cr alloy metal die with casting,abrator it.To make metal complete crown wax pattern on the metal die with a round ring on wax pattern occlusal surface,and tip of the ring passed the crown axial ray.Getting Ni-Cr alloy metal complete crown with embedding and casting,all the crowm abrator.There were sixty metal complete crowns,they were randomly divided to 3 groups,each group has twenty crowns:crowns in first group were common metal complete crowns;crowns in second group were gilding in the tissue surface of 1/3 cervical margin; crowns in third group were gilding in all the tissue surface,the gilding thickness was 2μm.The metal complete crowns were cementation in the metal die with glass ion luting agent,with 10kg pressure 10 minutes,then they were aqueous bath 24 hours in 37oC water. To measure the crowns` retention off the metal die with Instron almighty mechanics measurement equitment,each crown only measured once.The metal die cleared 15 minutes in the ultrasonator after experiment,to blow dry so as to next erperiment.Results:1 The retention of the crowns grow down after gilding,but the retention keeped high level. 2 Comparred to the commocn metal complete crowns, the retention had no statistically significant of crowns which gilding in the tissue surface of 1/3 cervical margin . 3 Comparred to the commocn metal complete crowns, the retention had statistically significant of crowns which gilding in all the tissue surface.Conclusions: 1 The retention of the crowns grow down after gilding,but the amount degresing wasn`t much,hintly that the retention of metal complete crowns after gilding could still satisfied clinically request. 2 Comparred to the crowns which gilding in all tissue surface of the crown, the retention of crowns which gilding in the tissue surface of 1/3 cervical margin degressed more little,hintly that it could get superperformance but also decreessed gilding district,get much rentention.