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Growth activity of the mandibular condylar cartilage in the rat
222
Reviews
and abstracts
application, at a rate of 1 to 2 per cent per minute, is accomplished in the Instron Universal Testing instrument utilizing their most sensitive load cell. the B cell. Stress-strain and stress-relaxation curves are graphed via chart recorder interfaced to the Instron. Fiber stress-strain curves are not affected by incubation at 37” C. in pure human parotid amylase, leech hyaluronidase, or chondroitinase ABC. During strain application. the specimens are surrounded by appropriate salt solutions at 25” C. Calculations of Young’s modulus for these fibers vary within the range 1.O-3 x lOlo dynes per centimeter. (This work was supported by grand DE 04015-Ol Al from the National Institute of Dental Research .)
Growth
Activity
of the Mandibular
Condylar
CartHage
in the Rat
Errol Stein University
of the Wimatersrand,
Johannesburg,
South Africa
Maximal growth rate occurred during the first 10 days after birth, continued at a reduced rate until the thirty-fifth day, and was still further reduced until it stopped at the forty-ninth day. The new bone formed by the condylar cartilage during this period of growth is rapidly remodeled, complete substitution of new bone appearing to occur within a period of 4 to 7 days. Mandibular growth involves many growth sites and mechanisms, all of which are closely integrated. The present study indicates that the area beneath the mandibular condylar cartilage is an active growth site during the growth period occurring between 3 and 10 weeks after birth in rats. A review of the literature on condylar growth in animals and human beings is included.
A Longitudinal Ceph8lomMric r Reposltlonlng of the Lower Face of the Growing Memoa Anthony Louis Maganrini Farleigh
Dickinson
University
Three young, growing rhesus monkeys (Macaca mulatta) were used in a longitudinal cephalometric study of altered mandibular growth and remodeling. It was the major premise of this study that the morphology of developing bones could be extrinsically affected by muscle position. Eleven angular and linear variables were measured on each lateral cephalogram while posteroanterior radiographs were utilized to clarify and conl%m changes in vertical and mediolateral directions. Computations of intra- and inter-tester reliability were made to ascertain the acceptability of the head film as a discriminate tool for quantitative measure. The two main conclusions were (1) that a reversal in directional growth expression occurred in the Macaw mulatta when the pterygomasseteric sling was anteriorly repositioned and (2) that this growth reversal manifested itself mainly in the lower face (below the palatal plane). The posibility exists that skeletal open-bite, close-bite, and retrognathic and prognathic growth potentials could be altered by muscle repositioning during a period of active mandibular morphologic development.
Reviews
and abstracts
application, at a rate of 1 to 2 per cent per minute, is accomplished in the Instron Universal Testing instrument utilizing their most sensitive load cell. the B cell. Stress-strain and stress-relaxation curves are graphed via chart recorder interfaced to the Instron. Fiber stress-strain curves are not affected by incubation at 37” C. in pure human parotid amylase, leech hyaluronidase, or chondroitinase ABC. During strain application. the specimens are surrounded by appropriate salt solutions at 25” C. Calculations of Young’s modulus for these fibers vary within the range 1.O-3 x lOlo dynes per centimeter. (This work was supported by grand DE 04015-Ol Al from the National Institute of Dental Research .)
Growth
Activity
of the Mandibular
Condylar
CartHage
in the Rat
Errol Stein University
of the Wimatersrand,
Johannesburg,
South Africa
Maximal growth rate occurred during the first 10 days after birth, continued at a reduced rate until the thirty-fifth day, and was still further reduced until it stopped at the forty-ninth day. The new bone formed by the condylar cartilage during this period of growth is rapidly remodeled, complete substitution of new bone appearing to occur within a period of 4 to 7 days. Mandibular growth involves many growth sites and mechanisms, all of which are closely integrated. The present study indicates that the area beneath the mandibular condylar cartilage is an active growth site during the growth period occurring between 3 and 10 weeks after birth in rats. A review of the literature on condylar growth in animals and human beings is included.
A Longitudinal Ceph8lomMric r Reposltlonlng of the Lower Face of the Growing Memoa Anthony Louis Maganrini Farleigh
Dickinson
University
Three young, growing rhesus monkeys (Macaca mulatta) were used in a longitudinal cephalometric study of altered mandibular growth and remodeling. It was the major premise of this study that the morphology of developing bones could be extrinsically affected by muscle position. Eleven angular and linear variables were measured on each lateral cephalogram while posteroanterior radiographs were utilized to clarify and conl%m changes in vertical and mediolateral directions. Computations of intra- and inter-tester reliability were made to ascertain the acceptability of the head film as a discriminate tool for quantitative measure. The two main conclusions were (1) that a reversal in directional growth expression occurred in the Macaw mulatta when the pterygomasseteric sling was anteriorly repositioned and (2) that this growth reversal manifested itself mainly in the lower face (below the palatal plane). The posibility exists that skeletal open-bite, close-bite, and retrognathic and prognathic growth potentials could be altered by muscle repositioning during a period of active mandibular morphologic development.