Abstract
A 45-year-old woman with a chief complaint of opening limitation was referred to Iwate Medical University Dental Hospital, in 1994. She reported that intermittent locking in the right temporomandibular joint (TMJ) occurred several times a day, which she managed to unlock by herself. The active opening range was 22 mm between the upper and lower incisal edges during the TMJ locked condition. MR images showed her right TMJ to be in anterior disc displacement with reduction, while the left TMJ showed normal findings. The mandibular position was altered to an anterior therapeutic position of 2 mm in front of the intercuspal position, by use of a removable partial denture (RPD), in 1995. Alternation of the occlusal position maintained the normal disc position, to increase her jaw opening range to as wide as 52 mm. Neither clinical examination nor MR images showed any problems in terms of mandibular function or disc position in 1996. When she lost her RPD in 1997, a second RPD was designed so that the intercuspal position was the same as her present occlusal position. However, her right disc began to displace again in 1998, except this time it was an articular disc displacement without reduction. Although her opening range increased from 28 to 35 mm after pumping manipulation therapy, her right disc stayed displaced without reduction.
Discussion: Since the patient's mandibular positioning when adjusted to the intercuspal position caused a recurrence of disc displacement, the anterior therapeutic position should have been maintained in this patient.
Conclusion: The anterior therapeutic position may be preferable in patients with long-lasting intermittent locking due to anterior disc displacement with reduction.
