The Comparative Study On Improvement Of Masticatory Efficiency With Four Kinds Of Removable Partial Dentures Restoration For The Bilateral Free End Deletion

In the recent years,along with the economic and culturalimprovement,there are more and more patients who accept denturerestoration. More new restorative procedures are adopted, forexample the precision attachment.As a particular removeble partialdenture, it has many advantages such as small base, slight foreignbody sensation,comfortable wearing ,and so on. However, itsdomestic clinical application for free end deletion restoration isrestricted to some extent because of its disadvantages, such ascomplex manufacture technology, fragility and high price. Inaddition,implant denture restoration is time consuming andexpensive so that its clinical application is limited.At present, the removable partial denture (RPD) is most widelyused for the bilateral free end deletion of dentition and its technologyis maturing gradually. According to manufacture methods, the RPDconsists of bending RPD and casting RPD. According to material,the RPD is composed of titanium alloy casting RPD and ordinarymetal casting RPD. According to sources of artificial tooth,the RPDconsists of finished product artificial tooth RPD and wax patternsartificial tooth RPD. Among the total, bending cast RPD has beenused for a long time and very commonly, especially when undercutof abutment is large. Its advantages are simple manufacture, lowprice and wide indication. ordinary metal casting RPD has beenapplied for a good many patients because of its strong retaining force,good stabilization, thin base plate and moderate price. Titanium alloycasting RPD has been gradually accepted by patients for its smallsize, thin base plate ,good biocompatibility,but its price is a littlehigh. The design of large supporting frame can endue titanium alloycasting RPD with favourable retention and stabilization. Afterexquisite manufacture,titanium alloy cast RPD is increasinglyaccepted and long-term follow-ups and feedbacks indicate that thedegree of the satisfaction of patients keeps on rising.The finished product artificial tooth RPD is frequently used.The finished product artificial tooth has fine appearance ,such asdistinct cusps and fossas and big apex cuspid obliquity. However,cusps and fossas are usually flatten out after adjusting occlusion,which could result in bad occlusal relation and vertical distancerestoration difficulty. In our study,one group of patients received waxpatterns artificial tooth RPD restoration,which can avoid somedrawback of the finished product artificial tooth.The manducation is one of major functions. The masticatoryfunction will decrease in case of defect of dentition, especially forthe missing of posterior teeth, because these teeth are key onesexerting masticatory function. Masticatory efficacy refers to thegrinding degree of food that is chewed and grinded by one withinunit time and represents the actual effect of masticatory movement.Masticatory efficiency equals to the percentage of masticatoryefficacy . Masticatory efficacy reflects the masticatory capability ofpatients and is an important index of masticatory function,whilemasticatory efficiency indicates the magnitude of masticatoryefficacy. The value of masticatory efficiency is one of objectiveindexes to weigh the impaired masticatory function of defectivedentition and is one of main evidence to evaluate restoration effect.Masticatory efficacy is another useful and objective index to assessrestoration effect.There are all kinds of measuring methods of masticatoryefficiency clinically,such as spectrophotometer. The spectrophot-ometer can mesure the optical density directly, conveniently andexactly. Peanuts can be used to determine masticatory efficiencywhen peanuts are masticated and grinded into small grain by patientsand normal individual. The smaller grain of peanuts is, the higher theturbidance of solution is, the greater the value of optical density is ,the higher masticatory efficiency of individual is. Influential factorsof masticatory efficiency include: age ,sex , masticatory frequency,condition of cusps, ridges, fissure and fossas in occlusal surface ofteeth, health of supporting tissue of teeth. After RPD restoration ,theimprovement of masticatory efficiency is affected by the followingfactors: retention and stabilization of denture, suitability, masticatoryfrequency, occlusal stability, manufacturing methods of artificialteeth, manufacturing process of dentures .In the experiment,alldentures were fabricated by the same technician staff,then try-in andocclusal adjustment were finished by the same dentist. In order toavoid the effect of interferential factors, optional masticatoryfrequency was adopted. According to manufacturing methods ofartificial teeth, suitability and manufacturing process of dentures, theselected cases were divided into groups.The design, processing andtry-in of detures were finished and masticatory efficiency ofindividual were measured. Finally the comparative study was carriedout between aforementioned factors.The aim of this experiment is that through restoring the bilateralfree end deletion with four methods, masticatory efficiency of thesepatients were tested after one month respectively, then themasticatory efficiency of the four groups were compared.We wouldevaluate the restorative effect of the four prosthetic methods after thestatistical processing and data analysis,so that we can guide theclinical work more effectively.In this experiment,we selected the patients who suffer from thebilateral free end deletion in the Stomatology Department of theThird Hospital attached to Jilin University and divided them intofour groups at random after screening: one group was for bendingclasp RPD restoration, the other group for ordinary alloy castingRPD restoration, the third group for titanium alloy casting largesupporting frame RPD restoration and the final group for waxpatterns artificial tooth titanium alloy casting RPD restoration. Untilpatients had worn the dentures for one month, We tested themasticatory efficiency of each respectively by 721A spectroph-otometer and finished the data analysis statistically.Through this experiment, the conclusions we can draw asfollows:for the patients who suffer from the bilateral free enddeletion, 1) the masticatory efficiency is higher in the group ofordinary alloy casting RPD than in the group of bending clasp RPDone month after restoration. 2) the masticatory efficiency is higher inthe group of titanium alloy casting large supporting frame RPDthan in the group of ordinary alloy casting RPD one month afterrestoration. 3) the masticatory efficiency is higher in the group ofwax patterns artificial tooth titanium alloy casting large supportingframe RPD than in the group of the finished product artificial toothtitanium alloy casting RPD one month after restoration. 4) for therestoration of defect of dentition,the group of titanium alloy castinglarge supporting frame RPD can achieve the best result, while thegroup of bending clasp RPD can achieve the worst result .