Response of the Mandibular Joint to Loss of Incisal Function in the Rat

Hinton, Robert J.; Carlson, David S.

doi:10.1159/000146153

Cited by 48 publications

(39 citation statements)

References 30 publications

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“…no type 1 fibres) in the superficial masseter of rats, which is in general agreement with the findings of previous studies of small mammals (Hiraiwa, 1978;Maier, 1979;Akagawa et al, 1983;Rokx et aI., 1984;Lindman et al, 1986;Nemeth, 1987;Oudet et al, 1988;Easton & Carlson, 1990). Easton & Carlson (1990) suggested that the predominance of type 2 fibres in the superficial masseter muscle reflects the gnawing activity that is typical of rodents (Carlson eta/., 1980;Hinton & Carlson, 1986;Nemeth, 1987) and that the high oxidative capacity of these muscles, as determined by the large percentage of type 2A fibres, indicates considerable capacity for more sustained or chronic phasic activity (Maxwell et al, 1973).…”

Section: Lesser Diameter and Fibre Proportionsupporting

confidence: 91%

Automated cytometry of fibre size and spatial distribution in the superficial masseter muscle of the rat at three ages

Zukowski

Roels

1994

Histochem J

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An image cytometry program was applied to sections of the superficial masseter muscle of female and male 21-, 42- and 105-day-old rats. Lesser diameter and spatial distribution of more than 6000 muscle fibres were automatically measured in digital images from muscle sections stained for myofibrillar ATPase activity. In this muscle, only type 2A, 2B and 2C fibres were observed. At the three ages and in both sexes, 2A fibres were found to have the largest diameter and were the most frequent (> 54%). In the 21-day-old animals, females presented larger diameters than did males; in contrast, in the 105-day-old animals, the three fibre types were larger in males than in females. At all ages and in both sexes, type 2A occupied 32 to 80% more cross-sectional area than type 2B. Most images (98%) showed a random spatial distribution of their fibre types. All fibre types grew in diameter with age. The coefficient of variation of the diameter was age-independent and remained under 23%. The finding of an age-independent variable could have a practical application: an increase of the coefficient of variation (> 25%) can be considered as pathological, even without a perfect age-matched control.

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Section: Lesser Diameter and Fibre Proportionsupporting

confidence: 91%

Automated cytometry of fibre size and spatial distribution in the superficial masseter muscle of the rat at three ages

Zukowski

Roels

1994

Histochem J

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“…Differences between the values for control and soft-diet animals were tested by the Wilcoxon signed-rank test. I II III IV V Age N M SD M SD M SD M SD M Bouvier and Hylander (1984) in rats fed a soft diet and of Hinton and Carlson (1986) after clipping the incisors of rats, that the thicknesses of the proliferating cell layer and whole condylar cartilage were reduced as compared with controls. Accelerated maturation of the condylar cartilage leads to its enhanced replacement with bone via erosion, resulting in a reduced thickness of the cartilage.…”

Section: Discussionmentioning

confidence: 95%

Effect of Mechanical Forces on Chondrocyte Maturation and Differentiation in the Mandibular Condyle of the Rat

1994

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The effects of mechanical factors on the growth of the mandibular condyle were studied by monitoring the maturation of the mesenchymal cells in 55 rats. Thirty-five animals were fed normal pellet food, and 20 were fed a soft diet and their incisors were cut regularly. 3H-thymidine was injected intraperitoneally three days before death at 18, 23, or 33 days. Histologic sections showed the most advanced 3H-thymidine-labeled cells to occur deep in the cartilage, in the lower hypertrophic cell layer in anterior and posterior regions of the condyle, and in the upper hypertrophic cell layer in the superior region at the age of 18 days. A distinct difference in the maturation state of the labeled cells could also be observed between these regions. In animals fed a soft diet, maturation was slower in the superior region of the condyle and faster in the posterior region than in the normal rats. The rate at which cells stepped out of the proliferating cell pool was measured by use of monoclonal antibodies against proliferating cell nuclear antigen. The ratio between labeled cells in the proliferating cell layer and the number of labeled cells beneath it was greater in control animals than in the soft-diet animals. The rate of differentiation and maturation of mesenchymal cells into chondrocytes seems to be controlled by mechanical factors.

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“…Mechanical stress on the condyle seems to be relevant to the increase in width of the trabecular bone . In this regard, Hinton and Carlson [17] reported that after feeding with a soft diet for 26 days, the trabecular bone of the young rat condyle was smaller and less dense than that of controls . Therefore, the mechanical stress placed on the condyle must be considered an important factor in the increase of trabecular bone .…”

Section: Discussionmentioning

confidence: 99%

Age-related histological changes in rat mandibular condyle

et al. 1995

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: The effect of aging on rat mandibular condyle was histologically assessed using 1-, 4-, 9-, and 16-month-old male Fischer rats (Eight rats of each group) . The medial and anterior portions of the condyle protruded with age . The hypertrophic cell layer of the condylar cartilage occurring up to 4 months was no longer observable at 9 months, after which calcification of the cartilage layer with a tidemark was featured . The chondrocytes in the calcified cartilage layer were reduced in size and intensely stained by toluidine blue . A mineralizing front was formed parallel to, and migrated toward, the condyle surface . At 9 months, osteon-like osteogenesis occurred around blood vessels on the border between the calcified cartilage and the subchondral bone . Condyles of 16-month-old rats exhibited osteosclerotic changes. The calcified cartilage of the middle portion of the condyle formed a remarkably thick layer . The increased volume of the trabecular bone appears to lead to enhanced osteosclerotic changes of the condyle . The aging-related protrusion of the anterior and medial portions of the condyle could be the result of a combination of mechanical forces, e .g ., occlusion and mastication . Further, our study revealed that the turnover from cartilage to bone occurring in rat condyle through the process of aging involved an osteon-like bone formation around the blood vessels on the border between the calcified cartilage layer and the bone . This process differs from the endochondral ossification process observed in younger rats .

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Response of the Mandibular Joint to Loss of Incisal Function in the Rat

Cited by 48 publications

References 30 publications

Automated cytometry of fibre size and spatial distribution in the superficial masseter muscle of the rat at three ages

Automated cytometry of fibre size and spatial distribution in the superficial masseter muscle of the rat at three ages

Effect of Mechanical Forces on Chondrocyte Maturation and Differentiation in the Mandibular Condyle of the Rat

Age-related histological changes in rat mandibular condyle

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