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Biomedical subjects

G H Schumacher

Publications and source records attributed to G H Schumacher.

At least 19 recordsLinked to original sources
PubMed1999

Regulative and adaptive factors in craniofacial growth.

Generally speaking, the animal experimental models described here are of theoretical importance. They fall naturally into the area of formulating general trends. Following elucidation of a series of concerns in the future, theoretical growth research will be able to provide more directly clinically applicable tools. Since no experimental animals of the masticatory type analogous to humans exist, results from animal experiments should be considered as statements on the biological reactions of analogous biological systems. Last but not least, biomechanical model representations point to the growth controlling functions of the bony and muscular head system components. These may provide an example for the analysis of degenerative changes in other parts of the body and serve as a theoretical basis for targeted therapeutic measures.

Animals↗
PubMed1997

The course of the mandibular canal in the growing miniature pig.

Miniature pigs are extensively used as laboratory animals in studies concerning craniofacial growth and adaptation. However, in contrast to the vast amount of literature regarding the overall growth pattern of the pig's mandible, little is known about the internal structures of the mandible such as the mandibular canal. In order to investigate the position of the mandibular canal (MC) and the thickness of its buccal and lingual walls, a cross-sectional study was performed on female miniature pigs MINI-LEWE covering the period from newborn to adult. The position of the MC was analyzed at bony segments that were obtained by cutting the drys mandibles interdentally. At each segment a central point of the MC was defined and its relation to the buccal and lingual margin of the mandible was measured. Located at the lower part of the mandibular corpus, the MC runs in the form of an arch within the sagittal plane in anterior direction, getting enlarged into the form of an ampulla in the molar and premolar region. Whereas during the primary dentition the biggest size of the MC was found behind the third deciduous molar, during the secondary dentition the biggest size of the MC was seen in the region of the first and second permanent molar. With regard the buccolingual aspect, the central point of the MC was found mainly in the center of the mandibular corpus. Between the 2nd and 5th month as well as at the beginning of the 18th month the thickest canal wall existed on the buccal side. In the period of the eruption of the succedaneous teeth, however, the lingual wall was thicker than the buccal wall. Results suggest that the definite course of the MC achieves relatively early in the miniature pig with the completion of the primary dentition. There were no major changes of the position of the MC in the postnatal period suggesting that the age factor has only a minor effect on the location of the MC.

Age Factors↗
PubMed1994

Morphometric studies on the facial skeleton of humans and pongids based on CT-scans.

The changes of the skull, which we can observe during the anthropogenesis, are reflected especially in the different skull proportions. We carried out metric measurements at the median level on 10 adult skulls each of humans, chimpanzees and gorillas as well as 11 skulls of orangutans. All skulls were scanned with a CT at the median level. We measured the lines and angles of the scans and the means and the standard deviations were calculated. We carried out a correlation analysis to observe the relation of their characteristics. We showed that there is a relation between the length of the skull base and the facial length in all species. From the results of the correlation analysis, we can also conclude that a relation exists between the degree of prognathism and the different length measurements of the facial skeleton. We also found a bending of the facial skeleton in relation to the cranial base towards the ventral side, also known as klinorhynchy, in all observed species. The highest degree of klinorhynchy was found in humans and the lowest in orangutans. We will discuss the different definition of the term klinorhynchy and its importance in the evolution of the hominoids.

Animals↗
PubMed1994

On the postnatal growth of the canalis mandibulae in the miniature pig.

The shape and the growth of the canalis mandibulae in female miniature pigs, MINI-LEWE, were analysed in 11 postnatal age steps. The lower jaw halves were cut frontally in a defined position and the heights and widths of the canalis mandibulae were measured. Changes in the shape of the canalis mandibulae in the frontal saw cuts were observed with regard to the dentition. After the eruption of the deciduous teeth there was no further change in shape. Growth curves of the mandibular canal's measures reached a peak during the eruption of the deciduous teeth and the first molar, decreasing significantly afterwards. A close correlation was observed between the measures of canal height and canal width. On the other hand there was only a slight correlation with the external measures of the mandible, which suggests that there are different growth processes.

Aging↗
PubMed1991

Stimulating effect of tongue on craniofacial growth.

The influence of the tongue on craniofacial growth was studied in 96 Mini-Lewe miniature pigs. The animals were partially glossectomized at different ages and slaughtered at various intervals after operation. The skulls were macerated for biometric analysis. Mandibular growth was significantly reduced lengthwise in animals glossectomized at age 12 weeks. The role played by the tongue in orofacial growth was also indicated by the reduced width of the lower jaw. In pigs partially glossectomized at age 12 weeks, lateral growth of the entire lower jaw was reduced after eight weeks. In animals glossectomized at age six weeks, lateral growth of the lower jaw was reduced in the region of the 1st deciduous molars and the canines after glossectomy. Partial glossectomy had no significant effects on vertical growth of the lower jaw, growth of the upper jaw or overall skull growth. Shortening of the tongue in miniature pigs six weeks old resulted in no measurable jaw changes 23 weeks after surgery.

Animals↗
PubMed1989

[Morphofunctional studies of the masticatory apparatus].

Biophysical studies of the orofacial system require a profound knowledge of the development and morphology of the skull. The skull is the result of phylogenetic and ontogenetic evolution. A great number of multifarious factors have effects on the growth of the skull. In animal experiments the effects of some of these factors on pre- and postnatal craniofacial growth as well as the resulting maintenance of the functional balance have been analyzed. These basic research findings will be a contribution to our understanding of the factors influencing and controlling maxillocranial growth and will aid us in evaluating their inherent laws.

Adaptation, Biological↗
PubMed1989

[The temporomandibular joint--structure and function during the course of development].

The temporomandibular joint is one of the most complicated articulations of our body. Its relative stability of function is in contrast to the apparent instability of some structures enclosed. The paper summarizes some thoughts about this joint and it should be stressed the especial difficulty in teaching the joint in the stomatological anatomy.

Humans↗
PubMed1989

Innervation pattern in jaw muscles of various mammalian chewing types.

The intramuscular nerve branches of the masticatory muscles were investigated in different mammalian species such as Canis familiaris, Capreolus capreolus, Capra hircus africans, Bos primigenius forma taurus, Myocastor coypus MOLINA 1782, Sus scrofa domestica, Pan troglodytes, Homo sapiens. The ramifications of the nerves form a specific pattern that is adapted to the specialised muscle structures in all mammalian chewing type. The innervation pattern is fully consistent with the infrastructures of the muscles which are already fixed at birth. Differences between the ramification pattern in comparable muscles in different chewing types are only minor, not fundamental.

Animals↗
PubMed1988

[The tongue as a factor in craniofacial growth. 4. Results of animal experiments].

Post-natal craniofacial growth in the miniature pig MIN-LEWE is influenced by the tongue in various ways. Periodic and locally differentiated intensive craniofacial growth explains why the tongue has a measurable effect on jaw growth only at certain times. This is the situation in animals glossectomized at an age of 12 weeks. Shortening of the tongue in miniature pigs aged six weeks resulted in no measurable changes in the jaw after a prolonged post-surgical interval (23 weeks), which indicates that the capacity of the orofacial system during post-natal development is considerable.

Animals↗
PubMed1988

Historical documents concerning craniopagi and conjoined twins.

The occurrence of congenital malformations had been documented by the Assyrian and Babylonians about 2,800 B.C. Historically, a significant source of information concerning conjoined twins were the so called "fugitive sheets" which following the introduction of printing served to disseminate news. The first sonographs with descriptions of congenital defects in human and animals appeared during the 17th century. Teratology became established during the 19th century as a result of the fundamental discoveries in embryology. Significant impetus was given to teratological research in this century following the discovery of GREGG (1941), from observations of the children born to pregnant women who were exposed to the atomic bombs, as well as the thalidomide catastrophe.

Abnormalities, Severe Teratoid↗
PubMed1988

[Craniofacial growth under the influence of blood supply. 13. Local biomechanical aspects of bone morphogenesis].

The origin of formative forces is to be sought in genetically controlled growth processes. The forces generated by various system components are analyzed. The forces acting in mutual opposition can be illustrated by considering the brain as an intracranial force factor and the temporalis muscle as an external force factor. Apposition and resorption of bone is governed by the interaction between the stresses. The skull's primary growth centres such as the basicranial synchondroses must, like epiphyses of tubular bones, exert growth forces to overcome the restraining forces stemming from surrounding tissues. Growth can be suppressed by excessive counter-pressure, diverted by asymmetrically acting forces, and encouraged by the removal of suppressive forces.

Biomechanical Phenomena↗
PubMed1988

[The tongue as a factor in craniofacial growth. 1. Modification of the linear dimensions of the lower jaw].

The influence of the tongue on craniofacial growth was studied in 96 miniature pigs MINI-LEWE. The animals were partially glossectomized at different ages and slaughtered at various post-operative intervals. The skulls were macerated for biometric analysis. Mandibular growth in length was significantly reduced in the animals glossectomized at an age of 12 weeks. Both the overall length and that of the tooth-bearing portion were affected.

Animals↗
PubMed1988

[Craniofacial growth under the influence of the blood supply. 14. Theoretical deductions and clinical conclusion].

After eliminating the masticatory muscles as a growth factor in our animal model is was possible to analyze the blood supply to the skull in sufficient detail. The animal organism and its parts may be regarded as self-regulating, self-optimizing and self-adapting systems. Open systems exchange energy and material with their surroundings. This is typical of all organisms and, since growth is one of their properties, to growth. The processes of ossification and growth of the rat skull are therefore comparable in principle with those taking place in the human. The specific features of the chewing mechanism, in contrast, are not comparable. The clinical conclusions drawn from our model studies illustrate the importance of the blood supply for craniofacial growth while simultaneously demonstrating the compensation ability and adaptability of arteries and bones.

Animals↗