Biochemical and autoradiographical evidence that anterior mandibular displacement in the young growing rat does not stimulate cell proliferation or matrix formation at the mandibular condyle

doi:10.1016/0003-9969(88)90052-0

Archives of Oral Biology

Volume 33, Issue 2, 1988, Pages 99-107

https://doi.org/10.1016/0003-9969(88)90052-0 Get rights and content

Abstract

A removable bite plate was used to induce forward mandibular displacement in four-week-old rats for 10h/day for 1, 3, 7, 11 and 14 days. The animals were killed and the condylar explants pulsed in vitro for 6 h with either [³H]-thymidine or [³H]-proline or ³⁵SO₄²⁻. The specific activity of radio-isotope incorporation was expresed as dis/min per μg DNA, dis/min per mg protein and dis/min per μg sulphated glycosaminoglycans (GAG). [³H]-thymidine autoradiography was also used in a 14-day experiment to establish a radioactive index (labelled cells per 1000 cells counted) for the anterior, middle and posterior regions of the condyle. There was no significant alteration in either cell proliferation (dis/min per μg DNA and radioactive index) or matrix formation (dis/min per mg protein and dis/min per μg GAG) at any point in the time scale.

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Cited by (27)

Changes in condylar cartilage after anterior mandibular displacement in juvenile pigs
2012, Archives of Oral Biology
Citation Excerpt :
Dannhauer proposes that these changes are preceded by increased water binding in the cartilage matrix.8 However, other studies show no changes of cell proliferation or matrix synthesis in the mandibular condyle after anterior displacement.9 Additional research on the histological level has also shown changes in the animal TMJ associated with mandibular advancement.2,10,11
Adaptive remodelling of the mandibular condyle in response to mandibular advancement is the mechanism exploited by orthodontic forward displacement devices.
This work investigated the expression of collagens, matrix metalloproteinases and vascular endothelial growth factor during this process.
Twenty juvenile pigs were randomly divided into two experimental groups, where the treatment group was fitted with mandibular advancement splints, and the control group was not. Changes in the mRNA content of condylar cartilage tissue was then were measured by real-time PCR using specific primers after 4 weeks of treatment.
The temporal pattern of the expression of Col1 and MMP13 during condylar adaptation coincided with that during natural condylar growth. The amount of the expression of Col10 during condylar adaptation was significantly lower (p < 0.05), whereas the expression of Col2, MMP8 and VEGF was significantly higher compared to natural growth (p < 0.05).
It is suggested that condylar adaptation in growing pigs triggered by mandibular forward positioning results not only from passive adaptation of cartilage, but also involves growth affected processes. Our results showed that mechanical strain produced by mandibular advancement induced remodelling and revascularization in the posteriocranial mandibular condyle. These results are mostly consistent with former published histological and histomorphometrical analyses.
The molecular markers for condylar growth: Experimental and clinical implications
2009, Orthodontic Waves
The outpour of new research has led to the identification of several factors that play an important role in condylar growth. The objectives of this review are to present the molecular markers that regulate the growth of different cells in the mandibular condyle and their impact on clinical use of functional appliance. The proliferative layer in the mandibular condyle houses a great number of undifferentiated mesenchymal cells that provide the pool of chondrogenic cells. Therefore, it is important to understand the factors that regulate the cell cycle of these replicating mesenchymal cells as well as the factors that control their differentiation to chondroblasts. These chondroblasts in turn are engaged in cartilage matrix synthesis. Therefore, it is critical to present the factors that regulate matrix formation.
The process of maturation of chondrocytes into hypertrophic chondrocytes directly impacts the number of cell replication cycles and indirectly affects growth. Therefore, it is of great importance to review the factors that regulate chondrocytes maturation. Hypertrophic chondrocytes secrete hypertrophic matrix with its type X collagen that marks the onset of endochondral ossification.
Angiogenesis is regulated by vascular endothelial growth factor (VEGF), and the new blood vessels are rich depository of mesenchymal cells. Factors that regulate the differentiation of these cells into osteogenic cells are critical to growth of the condyle.
Understanding of these markers and their levels of expression provides the basis for application of different treatment modalities in the area of growth modification. Furthermore, the identification of factors critical to condylar growth provides us with candidate genes for future gene therapy.
Histological and histomorphometric investigation of the condylar cartilage of juvenile pigs after anterior mandibular displacement
2007, Annals of Anatomy
The condylar cartilage of the mandible is considered a secondary growth center and represents a joint cartilage different from other cartilage structures regarding its histological structure, its histochemical and immunohistochemical properties and its growth pattern. This study aimed to histologically and histomorphometrically investigate the condylar cartilage after anterior mandibular displacement similar to functional orthopedic treatment.
A total of 12 pigs (sus scrofa domesticus) aged 10 weeks were divided into an experimental group and a control group comprising 6 animals each. The experimental animals were provided bilaterally with synthetic occlusal build-ups in the posterior area which induced anterior displacement of the mandible in terminal occlusion. After 4 weeks, the temporomandibular structures were removed en bloc and the condylar cartilage was analyzed histologically and histomorphometrically.
As a result, the experimental animals displayed a significantly increased total cartilage thickness of the posterocranial mandibular condyle which was primarily caused by an increase in thickness of the hypertrophic and chondogenic layers. Similarly, the proliferative layer showed a significant increase, whereas significant differences in thickness were absent in the articular layer. Increased cell proliferation was not observed in the experimental animals as compared to the controls. The changes found in the condylar cartilage area suggest that the zonal structure of the conylar cartilage may be modified by an altered spatial relationship between the mandibular condyle and the glenoid fossa.
Conservative treatment of unilateral condylar fractures in children: A long-term clinical and radiologic follow-up of 55 patients
1999, International Journal of Oral and Maxillofacial Surgery
The purpose of this prospectively designed study was the long-term clinical and radiological evaluation of conservatively treated unilateral condylar fractures in children. Fifty-five children aged between 2 1/2 and 9 3/4 years, presenting with a singular unilateral fracture of the mandibular condyle, were treated in a nonsurgical-functional way using an intraoral myofunctional appliance. In the follow-up period, patients were investigated by standardized clinical examination and by evaluation of panoramic radiographs taken immediately post-traumatically, after 6, 12, 24, 48 and 72 weeks, and then yearly through the period of growth. With a satisfactory clinical course in all patients, there was no instance of functional disturbance or mandibular asymmetry after the respective follow-up periods. The radiographs showed a fairly good shape of the condyle (no or only slight condylar deformity) in the 47 patients of the 2–6 year age group. In the eight patients of the 7–10 year age group presenting with a class II or III condylar fracture, healing was characterized by incomplete condylar regeneration, resulting in a moderate condylar deformity in two cases, a definite reduction in condylar neck height in two cases, and a hypertrophic condylar deformity in four cases. The positive results of this study confirm the concept of a nonsurgical-functional approach in children presenting with various types of unilateral fractures of the mandibular condyle. Condylar remodeling was the mode of fracture healing in instances of displaced and dislocated condylar fractures.
A rationale for a simplified occlusal design in restorative dentistry: Historical review and clinical guidelines
1995, The Journal of Prosthetic Dentistry
An occlusal contact pattern in which the number of occlusal contacts has been substantially reduced as compared with traditional schemes is described. Concepts that may have had a justification in balanced occlusions have been needlessly transferred to anterior disclusion mechanics. No natural dentition presents occlusal contacts as described in many texts and yet stability is established. The temporomandibular joint does present structural changes that should be accounted for when an occlusal anatomy is designed. The forve vectors that are active on teeth are not directed along the longitudinal axes of the roots only, and thus occlusal contact locations will not determine the direction of functional forces. The stability of the teeth on the arch depends primarily on the forces of eruption from the periodontium and the balance between the resting pressures of the muscles of the cheeks and the tongue. The mechanics of the stomatognathic system are not as accurate as their counterpart on an articulator. The variability of the guiding surfaces inherent to the temporomandibular joints should be incorporated into an occiusal design. Occlusal contacts that do not fulfill a justifiable purpose may be eliminated, and the number of contacts may be reduced to one per tooth.
The burden of proof: A critical review of orthodonticclaims made by some general practitioners
1994, American Journal of Orthodontics and Dentofacial Orthopedics
The increased demand for orthodontic treatment in the developed countries has led to a recentproliferation of “motel courses” that are specifically designed for general practitioners. Most of the techniques presented are only those that have long been available for selection by discerning orthodontists. However, when they are applied exclusively and indiscriminately by inexperienced clinicians, this may result in either prolonged, unnecessary treatment or failure through instability. Therefore some of the claims that are made will be examined and discussed with a review of the literature.

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^∗: Present address: Department of Orthodontics, Guy's Hospital, St Thomas' Street, London SE1 9RT, England, U.K.

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Biochemical and autoradiographical evidence that anterior mandibular displacement in the young growing rat does not stimulate cell proliferation or matrix formation at the mandibular condyle

Abstract

Archs oral Biol.

Oral Surg.

Analyt. Biochem.

Am. J. Orthod. Oral Surg.

Am. J. Orthod.

Am. J. Orthod.

Am. J. Orthod.

J. biol. Chem.

Am. J. Orthod.

Am. J. Orthod.

Am. J. Orthod.

Am. J. Orthod.

Am. J. Orthod.

Am. J. Orthod.

Am. J. Orthod.

A study of the conditions and mechanisms of the diphenylamine reaction for the colorimetric estimation of deoxyribonucleic acid

Biochem. J.