The Experimental Study On The Application Of Modified PLA Film In Repairing Chronic Tympanic Membrane Perforation

1 Objective1.1 To discuss how to obtain valuable micro-imaging data of the middle ear for guinea pig by using common digital camera and endoscope.1.2 To discuss the methods for constructing an animal model about persistent tympanic membrane(TM) perforation.1.3 To observe the efficiency of PLA and modified PLA film in repairing Chronic Tympanic Membrane Perforation.2 Methods2.1 The middle ears were investigated and photographed with common digital camera and endoscope in five healthy adult guinea pigs.2.2 Thirty Guinea pigs were divided into two groups randomly.Subtotal tympanic membrane perforations in the pars tensa were created by myringectomy combined with infolding of tympanic Membrane perforation rim in the control group,and the experimental group were treated with myringectomy tube a week.The residual perforations were examined weekly after the operation for 2 months,and persistent perforations without healing tendency after 2 month were regard as successful models.photoes acqurired by endoscope were analysed by using the software photoshop,the area proportion of the tympanic memberane perforation was calculated.2.3 Ammonia low-temperature plasma was used to modify PLA film.Subtotal tympanic membrane perforations in the pars tensa were created by myringectomy combined with infolding of tympanic Membrane perforation rim and treating with myringectomy tube a week in 45 Guinea pigs.The residual perforations were examined weekly after the operation in 2 months,and persistent perforations without healing tendency after 2 months were regard as successful models;Chronic Tympanic Membrane Perforations were divided into three groups randomly.The three groups were repaired with PLA film,modified PLA film and nothing respectively.The residual perforations were examined every day after the operation in 30 days.3 Results3.1 Collecting micro-imaging data includes images of tympanic membrane, ossicular chain,oval window,round window,facial nerve of the middle ear in the guinea pigs,etc,and all photos of the structures of the middle ear in the guinea pig are all clear.3.2 Creation of stable TM perforations was successful in 25 of 29 ears(86.21%)in the experimental group,otherwise,in the control group,12 of 29 ears(41.38%) were successful.Statistical significance was observed between these two groups in the tympanic perforation rate(P＜0.05).The area proportion of the experimental group was 0.32±0.03,the control group was 0.31±0.04(P＞0.05).3.3 Creation of stable TM perforations was successful in 75 of 90 ears.The cure rates among the three groups were 88.0%,52.0%and 16.0%respectively.Statistical significance was observed between these two groups in the tympanic perforation rate(P＜0.05).4 Conclusions4.1 The digital camera have legerity,portable,simple and convenient operating excellence,and have a function of revising,repeatable recording and managing images in computer in time.Because it takes images straight contacting with endoscope,so other digital imaging systems and optics cameras can not substitute it Completely.4.2 The ideal animal model of persistent tympanic membrane perforation can be successfully obtained through myringectomy tube combined with TM perforation rim infolded. 4.3 The ideal animal model of persistent tympanic membrane perforation can be successfully obtained through myringectomy tube combined with TM perforation rim infolded.PLA and modified PLA film is effective in enhancing closure of chronic tympanic membrane perforations in the guinea pig model,and stimulates healing of TM perforations.modified PLA film will become an new ideal gratf of repairing tympanic membrane perforation probably.