VALENCIA, Spain – An acrylic dental splint that is gradually adjusted over a long treatment period can accelerate mandibular growth in children with temporomandibular joint involvement in juvenile idiopathic arthritis, lengthening the affected side and normalizing jaw appearance and function.
“We found that we were able to speed up the metabolic growth rate of the affected side more than the unaffected side,” when the splint was used, Peter Stoustrup, D.D.S., reported at the congress of the Pediatric Rheumatology European Society. “We have also seen that this splint treatment seems to exert a protective effect on the inflamed joint, which can reduce soft-tissue damage and pain.”
He reported results of a series of 22 patients with JIA that was complicated by TMJ arthritis. Their mean age at disease onset was 7.5 years, and the mean treatment time was 57 months, although this varied widely (1-11 years).
The primary outcomes, as determined by baseline and final radiographs, were changes in the ratio between the unaffected and affected sides in condylar height, vertical ramus length, and total vertical mandibular height.
At the end of the study, the ratio of condylar height between the affected and unaffected sides was reduced from 1.18 to 1.14, which was not a significant change.
The ratio for vertical ramus length did change significantly, from 1.11 to 1.03. The ratio for total vertical mandibular height also significantly improved, dropping from 1.12 to 1.06.
The treatment was deemed successful in 19 (86%) of the patients. Three did not have satisfactory results and were referred for surgery.
TMJ arthritis occurs in about 62% of children with JIA, at least as confirmed by radiologic studies, said Dr. Stoustrup of the school of dentistry at Aarhus (Denmark) University. However, he noted, contrast-enhanced MRI suggests that the disorder could be even more common.
TMJ arthritis can lead to mandibular growth deviation resulting in micrognathia and shortened ramus length, an external rotation of the joint, open mandibular angle, cystic bone in the joint, and pain during chewing. The asymmetric growth can also result in a very specific appearance to the lower face. This facial deformity, often referred to as “bird face,” gives the lateral profile a reduced mandibular projection, with mandibular retrognathia, an open anterior bite, lower incisor crowding, and incisal protrusion.
“This is very difficult to correct orthodontically,” Dr. Stoustrup said. Most children are eventually referred for surgical correction.
The acrylic temporomandibular splint was first described by Dr. Thomas Pedersen in 1995 (Eur. J. Orthod. 1995;17:385-94). The splint covers the occlusal surfaces of the teeth in the lower dental arch and is worn 24 hours a day. The splint’s posterior height is adjusted slightly upward every 8-10 weeks on the affected side. “This normalizes dentoalveolar vertical development,” Dr. Stoustrup said.
What does this mean clinically for children who were successfully treated? Dr. Stoustrup described the case of a 13-year-old boy whose left TMJ arthritis was beginning to manifest as mandibular asymmetry. A frontal facial photo before treatment showed that the patient’s chin had deviated to the side of the affected joint, because of shortening of the mandible. He also displayed an open mandibular angle and posterior joint rotation pattern.
“We treated him with the distraction splint for 1.5 years, " Dr. Stoustrup said. At the end of treatment, the patient showed a much more anterior joint rotation pattern “because the mandible angle was increased.” The associated soft-tissue appearance was also much improved; the final facial photos showed that his chin was much more centered because of symmetrical jaw lengths.
Dr. Stoustrup did not disclose any financial conflicts.