Quantitative analysis of temporomandibular joint adaptations to protrusive function

Abstract

M uch has been published in the clinical and basic science literature on the growth of the temporomandibular joint. An area of significant controversy is the question of whether the growth of the temporomandibular joint, and of the mandibular condyle in particular, can be influenced to any significant degree through therapeutic or experimental intervention. Despite the number of clinical and experimental studies of this question, no universal agreement has been reached regarding the potential for adaptation in response to an alteration of the structural or functional environment by means of growth and/or remodeling of the temporomandibular joint. Part of the reason for this lack of agreement stems from the fact that competing dogmas exist concerning the growth and adaptability of the temporomandibular joint. A precise definition of the mechanisms by which condylar growth takes place also has been hindered, in many cases, by inadequate clinical and experimental samples and by incomparability of treatment plan or experimental design. Numerous persons have undertaken experimental investigations of temporomandibular joint growth in animal models. An evaluation of the findings from these studies reveals that the age or developmental stage of the animals used in these experiments is a critical factor in determining the potential for temporomandibular joint adaptability. There is little experimental evidence demonstrating that any significant adaptations can occur in the adult temporomandibular joint,13, 16, li, 34 and pathologic changes have been reported to occur in some instances. 6 In contrast, other studies have shown that the temporomandibular joint region, particularly the mandibular condyle of young, growing animals, can be a primary site of craniofacial adaptation to altered occlusal function.', 2. s, *L 28-33, 35 We lhave experimentally studied temporomandibular joint adaptability to alteration of the biomechanical environment, using the rhesus monkey (Macaca mulatta) as our animal From the Departments of Anatomy and Anthropology and the Center for Human Growth and Development, The University of Michigan.

Mandibular changes produced by functional appliances in Class II malocclusion: A systematic review

“…4,5 A wide range of functional appliances aimed to stimulate mandibular growth by forward posturing of the mandible is available to correct this type of skeletal and occlusal disharmony. 5 Although many studies in animals have demonstrated that skeletal mandibular changes can be produced by posturing the mandible forward, [6][7][8] the effects on humans are more equivocal and controversial. Many treatment protocols, sample sizes, and research approaches have led to disparate outcomes in studies on human subjects.…”

<b>Histological and morphological evaluation of condylar cartilage of young rats in response to stimulation of mandibular protrusion

“…Various experimental models that have evaluated mandibular growth in response to advancement have been published (Carlson, 1999;Mcnamara & Bryan, 1987;Mcnamara & Carlson, 1979;Meikle, 2007). Analyses were made by means of radiographic (Liu et al, 2007a), histological (Liu et al, 2007b), and immunohistochemicalstudies (Sato et al, 2006), comparison of different consistencies of food (Bresin & Kiliaridis, 2002;Maki, Nishioka, Shioiri, Takahashi, & Kimura, 2002), calcium restriction (Watanabe, Imamura, Uchikanbori, Fujita, & Maki, 2008), Type X collagen expression (Rabie & Hägg, 2002;Rabie, Xiong, & Hägg, 2004;Shen, Zhao, Kaluarachchi, & Rabie, 2006), Type II collagen expression Tuominen et al, 1996), transcription factor Sox 9 (Papadopoulou et al, 2007;Rabie, She & Hägg, 2003a) and vascular endothelial growth factor -VEGF (Rabie & Hägg, 2002;Rabie, Shum, & Chayanupatkul, 2002b).…”

Biological basis for functional appliance therapy

“…Further studies by McNamara et al [27][28][29] in Macaque monkeys incorporating tantalum implants have identified similar changes and highlighted the relevance of treatment timing of the treatment, based on reported changes in the electromyographic (EMG) activity in the lateral pterygoid muscles. Observation was made of the length of time required to produce additional bone rather than cartilage, with the latter being a less permanent structure.…”