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Biomedical subjects

J Stutzmann

Publications and source records attributed to J Stutzmann.

At least 37 records · Page 2Linked to original sources
PubMed1984

Time-dependent effects of a 'functional'-type orthopedic appliance on the rat mandible growth.

The modus operandi and the time-dependent variations in the effects of the LSU-activator, an orthopedic appliance currently used in human orthodontic therapy, was experimentally analyzed in growing rats. This appliance causes a forward positioning of the lower jaw and a restriction of mandibular motility. After a 4-week treatment, the following changes were observed: (i) the growth rate of the condylar cartilage was accelerated, this growth-promoting effect being more pronounced when the LSU-activator was worn during the animal's rest span. (ii) the direction of condylar growth became more backward-oriented; no significant difference between day and night treatment, i.e. during the rest and activity spans could be detected; (iii) the supplementary lengthening of the mandible was greater in rats treated during rest than in rats treated during waking and (iv) the number of serial sarcomeres in the lateral pterygoid muscle was smaller. This growth retardation of the muscle was greater in rest-time than in waking-time treated individuals. The LSU-type activator's action implies a two-step effect: during the time of wearing the appliance, the more forward positioning of the mandible causes a reduced growth of the lateral pterygoid muscle; during the time the LSU-type activator is not worn, the mandible is functioning in a more forward position such a way that it stimulates the growth rate of the condylar cartilage and the subperiosteal ossification of the posterior border of the ramus. It is therefore essential, for a few hours every day, that the mandible be allowed to move freely from the appliance in a more forward position.

Activity Cycles↗
PubMed1980

[Growth hormone: mode of action on different varieties of cartilage (author's transl)].

1) The growth of epiphyseal cartilages of long bones, of spheno-occipital synchondrosis of the cranial base, of the cartilage of the nasal septum, of lateral cartilaginous masses of the ethmoid, of cartilage between body and greater wings of the sphenoid (all stemming from the primary cartilaginous skeleton of the organism), is subject to general extrinsic factors and, more specifically, to the growth hormone (STH) and somatomedin. In this case, orthopedic devices can alterate the direction but not the amount of growth. 2) The growth of condylar, coronoid and angular cartilages of the mandible, of the cartilage of the midpalatal suture, and of the cartilage in some cranial sutures (all of secondary formation during phylogenesis and ontogenesis) is subject to local extrinsic factors as well as to growth hormone and somatomedin. In this case, appropriate orthopedic devices may modulate both the direction and the amount of growth. 3) Our cybernetic models attempt to account for the mechanisms of facial growth. By intensifying the forward growth of the nasal septum cartilage, the STH and somatomedin stimulate the forward growth of the upper jaw, i.e. the forward positioning of the superior dental arch (the position of which is the "constantly changing reference input" of the servosystem). The "operation of confrontation" between the position of the upper and lower occlusal surfaces (the position of the lower dental arch is the "controlled variable" of the servosystem) gives then rise to a "deviation signal" (originating from detectors of occlusal adjustment) whose "reduction" is made possible by a supplementary postural activity of the lateral pterygoid muscle resulting, extemporaneously, in an appropriate forward positioning of the mandible and, with time, in a supplementary growth of the condylar cartilage. By intensifying the outward growth of lateral cartilaginous masses of the ethmoid and of the cartilage between the body and greater wings of the sphenoid, the STH and somatomedin bring about a lateralization of both the left and right sides of the upper jaw and, in this way, stimulate the growth of the secondary cartilage of the midpalatal suture.

Animals↗
PubMed1980

[Intrinsic regulation of the condylar cartilage growth rate (author's transl)].

The experimental results reported above, strongly suggest the existence of an intrinsic regulatory mechanism of the condylar cartilage growth rate. The cell density as such cannot account, at least not completely, for the findings. In other words, there must be a "negative feed-back signal" originating from the proximal part of the chondroblastic zone and exerting a restraining effect on the prechondroblastic multiplication rate. The concept of an intrinsic regulation of the condylar cartilage growth rate can help to explain the effects of some orthopaedic or orthodontic appliances as well as of a hormone, thyroxine. The earlier commencement of chondroblastic hypertrophy and the subsequent decrease in the prechondroblast restraining signal appear to be an important intermediary step in the growth-stimulating effect of the mandibular postural hyperpropulsor. The acceleration of the chondroblastic maturation rate is, in a similar way, an intermediary step for the growth-rate stimulating effect of thyroxine.

Animals↗