MRI Evaluation Of Anterior Disc Displacement Without Reduction With Stabilization Splint Therapy

Objective:To study the influence of the shape of the disc,the vertical distance from the posterior inferior edge of the disc to the top of the condyle,and the thickness of the ligament in the posterior region of the disc on the change of the disc position after stabilization splint intervention treatment.Methods:Retrospective select 50 patients(72 sides)with temporomandibular joint disorder(Anterior disc displacement without reduction)diagnosed in our hospital from June 2018 to June 2019 and treated with splint,including 6 males and 44 females,age 12～33 years old,average age(18.3±4.5)years old.Patients with temporomandibular joint disc perforation and systemic diseases,such as rheumatoid,rheumatoid and severe mental and psychological diseases,were excluded according to the clinical situation and relevant imaging examination.By observing and comparing the MRI data of the patients before and after splint therapy,the patients were divided into 2 groups according to the changes of the disc position.Reset/improved group and unchanged/recombined group.The shape of the disc,the vertical distance from the posterior lower edge of the disc to the top of the condyle,and the thickness of the ligament in the posterior region were measured before treatment.Analyze and compare the data difference between the two groups.Results:After 6 months of treatment with SS,patients with ADDwoR on 72 sides were 21reductions and 9 improvements,and a total of 30 were included in reset/improved group,37 were unchanged and 5 aggravated,a total of 42 sides were included in unchanged/recombined group.1.There was no significant difference between the two groups byχ~2test.The results showed that disc shape had no effect on the change of disc position.In this study,6 sides of the discs were completely deformed,and no reduction or improvement was found after half a year’s treatment with SS,indicating that the reduction effect of the fully deformed disc after SS treatment was not good.2.The vertical distance data of the posterior inferior margin of the articular disc to the top of the condyles in the two groups were statistically significant by independent sample t test(P<0.05),the mean vertical distance of the reduction/improvement group was 2.9mm,which matched the thickness of the stable occlusal plate,less than the mean value of no change/reconstruction(4.8mm),indicating that patients whose vertical distance from the posterior inferior edge of the disc to the top of the condyle is less than the thickness of the SS have a better prognosis.3.There was no significant difference in the results of independent sample t test between the data of the thickness of the ligament in the posterior region of the discs between the two groups(P>0.05),indicating that the thickness of ligament in the posterior region of the disc could not be used as an index to predict the change of the position of the disc.Conclusions:The shape of the normal and slightly deformed disc had no effect on the change of the position of the disc after the patients received the intervention of the SS,and it is unlikely that a completely deformed joint disc will be reset after splint therapy;The vertical distance from the posterior lower edge of the posterior disc to the top of the condyle is less than the thickness of the stable bite plate,which is a favorable condition for the reduction of the disc;The thickness of the ligament in the posterior region of the disc has no effect on the position of the disc.