The Experience Of Using MBA For Repair The Porcelain Fracture Of Porcelain-fused-to-metal On Lip Or Buccal Associated With Metal Exposure

Objective: To study the clinical effect and the indication of MBA for repair theporcelain fracture of porcelain-fused-to-metal on lip or buccal associated with metalexposure through the clinical application and the results of experiment’s date analysis.Materials and Methods: There are22cases during march2010to may2012.Using the Panavia-F special composite resins (11) and MBA(11) randomly in thesimilar condition cases which is Completed by the same physician, and follow-up everythree months. The step: Panavia-F: to make collapse porcelain surface roughen withdiamond burs and to expand along the edge of the cracked porcelain slightly, and tomake the edges regular and clear. That will increase the bond area and good for thenatural transition edge of filling the resin and effectively improve the marginal seal andaesthetics. Polish by a “井”grooves on the surface of exposed metal with the high-speedbladed diamond burs. The length of grooves will be extended to the junction ofmetal-ceramic with the depth of approximately0.2mm. Rinsing and drying. Contrastingthe color to determine the repair resin’s one. then to coat the exposed metal surface withmetal treatment agent, standing and drying for10s. Then coat it with opaque layer,lighting for40s. Coating the porcelain surface with the mixture of porcelain treatmentagent and adhesive treatment agent which is the same amount for5s and drying it.Using composite resin filling layer by layer and shaping, each layer lights for40s. atlast to trim the shape. Polishing, washing and drying it. MBA: The mechanicalprocessing of the porcelain and exposed metal surfaces is as above. Then to clean thehandle surface for5s.After drying, heap the metal surface with the completed MBA.The thickness is appropriate for covering the color of metal. After about10min, weuniform coating enamel adhesive on MBA and trimmed porcelain surface, and lighting for40S. Then filling and shaping the composite resin layer by layer, coating the enamelbinder to close the edge of the filled resin after the light40S. Production metal columnof ceramic alloy which bonding area diameter are3.4mm、5.8mm and4.0mm in thelaboratory. Then shaping2.0mm porcelain in the metal column of4.0mm outer edgeevenly, in order to mimic3specimens of the clinical collapse porcelain interface(metal-ceramic area ratio is about1:3). Using the Silicone rubber to produce thenegative model mold of the same diameter as the specimen (in order to ensure theaccuracy of bonding area of the specimen. Panavia-F and MBA were used to bond the3specimens in the mold respectively. Fixing the samples in a special metal fixture, theloading head is close to the bonding interface, the shear direction is parallel to thebonding surface, the loading speed is1mm/min. The loading direction is vertical load.Until the bonding interface is damaged, the computer automatically records the shearstrength at this time. The above experimental data will be statistically analyzed byspss11.5. We will have A and B groups of clinical patch results and experimental resultsalso the comparative analysis of results according to the aesthetic effect and the bondingstrength.Results: The clinical observation to the22cases for1-2years shows that group Aand group B can both restore the aesthetic effect. The expulsion rate of group A is36.7%,the cases are almost the patients with exposed metal of larger area. The expulsionrate of group B is9.1%, the patients are mostly exposed metal of smaller area. Duringthe vitro experiments, the shear stress of group A is equivalent to group B whenbonding the exposed metal column of3.4mm. But the shear stress of group B issignificant greater than that of group A when bonding the exposed metal column of5.8mm. When bonding the model of the metal-ceramic area ratio is1:3, the shear stress ofgroup B is significant greater than that of group A.Conclusion: MBA have a good result both in clinical repair effect and laboratorydata for the porcelain repairing. It is more applicable to exposed metal with the largerarea. If we choose the correct indications, porcelain repairing of MBA has not onlygood glue effect but also the color of repairing coordinate with adjacent porcelain andthe effect is more durable.