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A functional TMJ model
j m LETTERS
TO
a
THE
EDITOR
JADA devotes this section to comment by readers on topics of current interest to dentistry. T he editor reserves the right to edit all com m unications to fit available space and requires that all letters be typed, double-spaced, and signed. No more than ten references should be given with each letter. Printed com m u nications do not necessarily reflect the opinion or official policy of the Association. Your participation in this section is invited.
A functional TMJ model □ E ditor’s note: In this short article, we
break with JADA policy and describe a com mercial product designed by Dr. Jam es Quinn through L ou isian a State Univer sity’s M edical Technology Transfer Com mittee and contracted to the manufacturer. M any dental practices treat patients w h o have p ain fu l dysfun ction al T M problem s. E x p la in in g the cause of their “c lick in g ” or com p lete condylar b lo ck in g (closed lock) sym ptom s resu ltin g in pain and lim ita tio n of m o tio n is m ost h elp fu l to the p atien ts’ understanding of the problem and indicated therapy. T h e fu n ction al T M J capsule and artic ular disk m odel (F ig 1, left) show s a threed im en sion al dem onstration o f norm al and abnorm al fu n ction o f the TM J. T h e m odel uses an anatom ically correct plastic skull w ith the “jo in t” com posed o f an anterior and posterior capsule (the lateral capsule is left op en for visibility) and an articular disk w ith the posterior band at the correct “ 12 o ’clo ck ” condylar p o sitio n and a Vtin tape “pterygoid m uscle.” It duplicates
the articular disk and condylar relation sh ip in h in g e and translatory m ovem ents that occur in the superior and inferior jo in t spaces respectively (F ig 1, right). T h e cap su le is m ade o f a p lastic rubber m aterial as is the articular disk. T h e disk closely duplicates the norm al h u m an disk in structure and texture. T h e capsule is attached anteriorly and posteriorly from the fossa to the neck of the condyle to a llo w easy v iew in g o f the disk-condylar m ove m ents. T h e red '4-in tape representing the p te r y g o id m u s c le is a tta c h e d to the articular disk so that the disk can be m oved in to a partially displaced anterior p o sitio n to dem onstrate “p o p p in g or click in g ” as the condyle snaps anteriorly and p oste riorly over the thick posterior lip of the disk in o p en in g and c lo sin g translation. T h e disk can also be m oved in a com pletely anterior p o sitio n to the condyle to produce the condylar block (closed lock) co n d ition that prevents translation and com plete o p e n in g o f the m outh. C om pression o f the retrodiskal tissue rich in b lood vessels and nerves can be dem onstrated to the patient to indicate on e of the primary causes of p a in in the joint. T o m an ip u late the T M J m odel, righthanded in d ivid u als can h o ld the skull betw een the chest and base of the left hand. T h e thum b o f the right hand is placed o n the righ t ram us o f the m andible w ith the fingers of the right hand on the left body of the m andible (F ig 1). In this p o sitio n , the left thum b and index finger can grasp the “pterygoid m u scle” tape attached to the disk and m ove it gradually
forward to illustrate partial or com plete d isk d is p la c e m e n t a n d the r e s u ltin g condylar-disk dysfunction. O nly one jo in t sh o u ld be m oved at a tim e to d em on stra te th e j o in t fu n c t io n s m o o th ly . M o v in g b o th jo in ts to g eth er u su a lly r e s u lts in an u n c o o r d in a te d j o in t m ovem ent. In addition, the m odel can be used to dem onstrate the norm al h in g e and trans latory condylar-disk m ovem ents o f m an dibular o p e n in g and closin g; abnorm al d y sfu n ction al anterior disk displacem ent w ith the resultant sym ptom s of “click in g an d p o p p in g ”; and com plete disk d islo ca tio n p rod u cin g “condylar b lock” (closed lo c k ) w ith in a b ility to tran slate and p a in fu l com pression and stretching o f the sensitive retrodiskal tissue. T reatm ent m odalities can be d em on strated: anterior rep o sitio n in g splints to “recapture” a m obile, m in im al to m od erately d isplaced disk; fixed anteriorly disp laced disks incapable of “recapture” by use o f anteriorly rep o sitio n in g splints; arthroscopic TM J d iagn osis and surgical te c h n iq u e s; a n d o p e n jo in t su r g ic a l techniques. U se of this fu n ction al TM J capsular and articular disk m odel sh ou ld be of con sid erable assistance in illu stratin g rapidly the causes o f T M J dysfunction and p a in and the various treatment m odalities available to correct these problem s. JAMES H. QUINN, DDS LOUISIANA STATE UNIVERSITY Dr. Q uinn is professor, department of oral and m axillofacial surgery, Louisiana State University School of Dentistry. T he manufacturer is Medical Plastic Laboratory, Highway 116, Gatesville, T X 76528.
Fairy tales can come true □ T h e “ Letters to the Editor” section (January) sh o u ld be required reading for every p ractition er and student in the country. W hen I first scanned this section, the last letter seem ed u n u su al, if n ot d o w n right p ecu liar—a fairy tale? I returned to 234 ■ JA DA, Vol. 120, M arch 1990
TO
a
THE
EDITOR
JADA devotes this section to comment by readers on topics of current interest to dentistry. T he editor reserves the right to edit all com m unications to fit available space and requires that all letters be typed, double-spaced, and signed. No more than ten references should be given with each letter. Printed com m u nications do not necessarily reflect the opinion or official policy of the Association. Your participation in this section is invited.
A functional TMJ model □ E ditor’s note: In this short article, we
break with JADA policy and describe a com mercial product designed by Dr. Jam es Quinn through L ou isian a State Univer sity’s M edical Technology Transfer Com mittee and contracted to the manufacturer. M any dental practices treat patients w h o have p ain fu l dysfun ction al T M problem s. E x p la in in g the cause of their “c lick in g ” or com p lete condylar b lo ck in g (closed lock) sym ptom s resu ltin g in pain and lim ita tio n of m o tio n is m ost h elp fu l to the p atien ts’ understanding of the problem and indicated therapy. T h e fu n ction al T M J capsule and artic ular disk m odel (F ig 1, left) show s a threed im en sion al dem onstration o f norm al and abnorm al fu n ction o f the TM J. T h e m odel uses an anatom ically correct plastic skull w ith the “jo in t” com posed o f an anterior and posterior capsule (the lateral capsule is left op en for visibility) and an articular disk w ith the posterior band at the correct “ 12 o ’clo ck ” condylar p o sitio n and a Vtin tape “pterygoid m uscle.” It duplicates
the articular disk and condylar relation sh ip in h in g e and translatory m ovem ents that occur in the superior and inferior jo in t spaces respectively (F ig 1, right). T h e cap su le is m ade o f a p lastic rubber m aterial as is the articular disk. T h e disk closely duplicates the norm al h u m an disk in structure and texture. T h e capsule is attached anteriorly and posteriorly from the fossa to the neck of the condyle to a llo w easy v iew in g o f the disk-condylar m ove m ents. T h e red '4-in tape representing the p te r y g o id m u s c le is a tta c h e d to the articular disk so that the disk can be m oved in to a partially displaced anterior p o sitio n to dem onstrate “p o p p in g or click in g ” as the condyle snaps anteriorly and p oste riorly over the thick posterior lip of the disk in o p en in g and c lo sin g translation. T h e disk can also be m oved in a com pletely anterior p o sitio n to the condyle to produce the condylar block (closed lock) co n d ition that prevents translation and com plete o p e n in g o f the m outh. C om pression o f the retrodiskal tissue rich in b lood vessels and nerves can be dem onstrated to the patient to indicate on e of the primary causes of p a in in the joint. T o m an ip u late the T M J m odel, righthanded in d ivid u als can h o ld the skull betw een the chest and base of the left hand. T h e thum b o f the right hand is placed o n the righ t ram us o f the m andible w ith the fingers of the right hand on the left body of the m andible (F ig 1). In this p o sitio n , the left thum b and index finger can grasp the “pterygoid m u scle” tape attached to the disk and m ove it gradually
forward to illustrate partial or com plete d isk d is p la c e m e n t a n d the r e s u ltin g condylar-disk dysfunction. O nly one jo in t sh o u ld be m oved at a tim e to d em on stra te th e j o in t fu n c t io n s m o o th ly . M o v in g b o th jo in ts to g eth er u su a lly r e s u lts in an u n c o o r d in a te d j o in t m ovem ent. In addition, the m odel can be used to dem onstrate the norm al h in g e and trans latory condylar-disk m ovem ents o f m an dibular o p e n in g and closin g; abnorm al d y sfu n ction al anterior disk displacem ent w ith the resultant sym ptom s of “click in g an d p o p p in g ”; and com plete disk d islo ca tio n p rod u cin g “condylar b lock” (closed lo c k ) w ith in a b ility to tran slate and p a in fu l com pression and stretching o f the sensitive retrodiskal tissue. T reatm ent m odalities can be d em on strated: anterior rep o sitio n in g splints to “recapture” a m obile, m in im al to m od erately d isplaced disk; fixed anteriorly disp laced disks incapable of “recapture” by use o f anteriorly rep o sitio n in g splints; arthroscopic TM J d iagn osis and surgical te c h n iq u e s; a n d o p e n jo in t su r g ic a l techniques. U se of this fu n ction al TM J capsular and articular disk m odel sh ou ld be of con sid erable assistance in illu stratin g rapidly the causes o f T M J dysfunction and p a in and the various treatment m odalities available to correct these problem s. JAMES H. QUINN, DDS LOUISIANA STATE UNIVERSITY Dr. Q uinn is professor, department of oral and m axillofacial surgery, Louisiana State University School of Dentistry. T he manufacturer is Medical Plastic Laboratory, Highway 116, Gatesville, T X 76528.
Fairy tales can come true □ T h e “ Letters to the Editor” section (January) sh o u ld be required reading for every p ractition er and student in the country. W hen I first scanned this section, the last letter seem ed u n u su al, if n ot d o w n right p ecu liar—a fairy tale? I returned to 234 ■ JA DA, Vol. 120, M arch 1990