Morphologic changes in the TMJ following splint wear

Abstract

Intraoral splints are a commonly used dental treatment for a variety of conditions. Because such splints alter the condyle-disc-fossa relationship, they probably change the loading status of the temporomandibular joint (TMJ), including the TMJ disc. Collagen, a major constituent of the disc, acts to resist tensile loading, and it is presumed that the fiber orientations of the individual disc bands reflect their functional loading. Therefore, the purpose of this study was to examine effects of intraoral splint wear on TMJ morphology in general, and collagen orientation of the intra-articular disc in particular. Young adult, female miniature pigs were divided into three groups: open-bite splint, protrusive-bite splint, and unsplinted control. Splints were worn for 2 months, after which the TMJ discs were harvested for histological examination and stereological analysis, and the skulls were cleaned. Although the splints had no effect on skull dimensions, changes were seen in the TMJs. The discs of the protrusively-splinted group showed an increased thickness of the posterior band (P Ͻ 0.015) and minor changes in collagen orientation of the anterior band. The most striking change was the presence of a degenerative osseous defect on the medial side of the mandibular condyle in half of the splinted animals. These results indicate that prolonged splint wear can induce remodeling and even injury of TMJ tissues. Anat Key words: temporomandibular joint disc; porcine; morphology; intraoral splints; collagenIntraoral splints are used in dentistry to treat a variety of conditions, such as occlusal malalignments, temporomandibular joint (TMJ) dysfunctions, and sleep apnea (Bondemark, 1999;Carels and van der Linden, 1987;Gianelly et al., 1970;Grim, 1995;Johal and Battagel, 1999;Kimmel, 1994;Major and Nebbe, 1997;Nitzan, 1994;Wright et al., 1995). All splints change the occlusal relationship of the teeth and, hence, the spatial relationship of the TMJ components, although the precise effect varies with the splint (Ito et al., 1986). Additionally, splint wear must affect disc structure, as indicated by studies showing changes in shape (Ferrari and Herring, 1995) and glycosaminoglycan (GAG) content (Mao et al., 1998;Sindelar et al., 2000). However, detailed morphology has not previously been assessed.The TMJ disc is composed of approximately 80% water (Sindelar et al., 2000); the remaining 20% is mostly collagen. Prior studies on the human, bovine, dog, rabbit, monkey, sheep, and rat TMJ disc have shown that the fibers of the intermediate zone are oriented predominantly in the anterior-posterior (AP) direction, while the fibers of the anterior and posterior bands are more multidirectional or "basket-woven"

High-resolution magnetic resonance imaging and diffusion tensor imaging of the porcine temporomandibular joint disc

“…[34][35][36] Our quantitative results encourage the use of DTI for comparison of similar measurements obtained from the TMJ discs of experimentally induced disease or inflammation in animal models such as the miniature pig model that correlates degenerative joint disease following intraoral splint wear described by Sindelar and coworkers. 37,38 In regards to the use of DTI, a much higher magnetic field strength than is currently approved for clinical studies was used. The use of this high field strength provided increased signal-to-noise ratio and resolution necessary in the case of this study; however, it leaves the question open as to whether this technique would be feasible for human use.…”

Temporomandibular joint in miniature pigs: Anatomy, cell replication, and relation to loading

“…2A and 4A). The anterior and posterior bands feature dense interwoven collagen fibers oriented predominantly mediolaterally, whereas the crimped collagen fibers of the intermediate zone run anteroposteriorly (Sindelar et al, 2002). Elastic fibers are abundant and multidirectional in the anterior and especially the posterior bands, infrequent and aligned anteroposteriorly in the intermediate zone (Christensen, 1975).…”

Chronic temporomanudibular joint dysfunction: an area of debate

“…Failure of occlusal splint therapy to resolve symptoms, particularly pain, may be related to psychological implications 59 . Prolonged splint wear may induce remodelling and even TMJ injury, as indicated in a study involving miniature pigs 99 . Therefore, splints can be constructed as an initial form of therapy 60 .…”

“…Treatment with anti-depressants cannot be expected to give immediate pain relief because of the delayed onset of their action which usually takes 4-6 weeks 110 . Corticosteroids can be injected or applied topically in cases of condylar erosion, myalgia and trismus with relatively positive therapeutic results 99,111 . A randomized controlled trial did not support the use of botulinum toxin A in patients with moderate to severe chronic muscular type of pain, concluding that these patients had less wide jaw opening compared with a placebo group 112 .…”