Biomedical subjects

O Rönning

Publications and source records attributed to O Rönning.

At least 19 recordsLinked to original sources

PubMed1992

Craniofacial growth in shunt-treated hydrocephalics: a four-year roentgenocephalometric follow-up study.

The craniofacial growth of 24 shunt-treated hydrocephalics aged 5-15 years was evaluated over a 4-year period, by comparing changes in linear and angular cephalometric variables with those of an age- and sex-matched control group. The main findings were increased calvarial thickness, increased cranial base flexure, superior displacement of the sella, and a tendency for the gonial angle to remain more obtuse in the shunt-treated patients. As craniofacial growth in the latter differed only slightly from that observed in the controls, the deviations in facial morphology observed in a previous cross-sectional study of shunt-treated hydrocephalics can be taken to represent a long-term effect of the shunt treatment.

Adolescent↗

PubMed1992

Weaning and the histology of the mandibular condyle in the rat.

Eighty-eight Long Evans/Turku rats were used in the study. The effect of the articulatory function on the mandibular condyle was observed histologically during normal growth, when the rat is changing its diet from milk to whole pellets as a part of weaning. Six animals each were killed at the age of 10, 15, 20, 25, 30, 35, 40 and 50 days for histological tissue processing. For further information, 30 animals were fed a soft diet (6 animals each were killed at the age of 25, 30, 35, 40 and 50 days), and 10 animals were fed hardened pellets (2 animals each were killed at the ages of 25, 30, 35, 40 and 50 days). An even and regular transition from mesenchymal cells via immature chondroblasts into mature chondroblasts and hypertrophied chondrocytes was found at 10, 15 and 20 days during normal growth and also at 25, 30, 35, 40 and 50 days when animals were fed a soft diet. This maturing process appeared to be disturbed at the age of 25, 30, 35 and 40 days in the superior aspect of the condyle in animals fed ordinary pellets. The density of the mesenchymal cell layer was decreased, and the amount of intercellular matrix seemed to be evaluated in mesenchymal and intermediate cell layers. These features were later manifest deeper in the cartilage as acellular regions and as cell clusters. The changes were similar but more severe when the animals were fed hardened pellets.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Growth potential of the rat mandibular condyle as an isogeneic transplant traversing the interparietal suture.

The mandibular condyle of 5-, 10- or 20-day inbred male rats was transplanted across the interparietal suture of male litter-mates and the transverse dimension of the neurocranium was measured from dry skulls at 25 or 35 days. The width of the neurocranium had increased significantly from days 5 or 10 to 25 in the rats with the transplants, whereas the difference from controls was small or non-existent by 35 days. Histological examination showed that the cartilaginous zone was reduced in the transplants at 25 days but that there were still layers of chondrocytes at 35 days. It is suggested that the rat mandibular condyle is endowed with a tissue-separating, interstitial growth potential that, to some extent, is unrelated to mobility, and essentially effected by chondrocyte hypertrophy.

Animals↗

PubMed1991

Growth potential of the rat clavicle.

An experiment was performed to determine whether the clavicle, which is capped with secondary cartilage at both ends, is endowed with a tissue-separating quality or is only adaptive to forces exerted by the surrounding structures. The medial end of the clavicle from 10-day-old male rats was transplanted across the interparietal suture into an opening in the adjoining parietal bones corresponding to the outline of the transplant. The transverse dimensions of the neurocranium when measured at 25 and 35 days of age were greater in the animals with transplants than in the untreated controls. Histologic examination showed that although the cartilaginous component of the transplants was reduced, the zonal arrangements was comparable to that in situ. It was concluded that the medial end of the clavicle has a potential for separating skeletal components and that preservation of the basic structure is dependent on mechanical resistance.

Animals↗

PubMed1991

Interrelationship between size and tissue-separating potential of costochondral transplants.

The aim was to determine whether the reportedly unpredictable outcome of the use of costochondral grafts in reconstructive surgery is related to variation in growth potential between the transplanted cartilages. A rib fragment including the costochondral junction was transplanted across the interparietal suture in 10-day-old rats. The transplants contained either a short, intermediate, or long cartilaginous end and a constant length of bone. The animals were killed 25 days later and the width of the neurocranium was measured from dry skulls. The neurocranium was wider the longer the cartilaginous end of the transplant. It is concluded that costochondral transplants have an intrinsic potential for separating skeletal components and that this capacity is closely related to the amount of cartilage in the transplant.

Animals↗

PubMed1991

Cartilage, function and craniofacial morphogenesis.

While primary cartilage of the craniofacial complex is a derivative of the chondroskeleton, secondary cartilage develops in close association with membrane bone. Mobile function, motility, is not always a prerequisite for the genesis of secondary cartilage but seems necessary for its maintenance as also, evidently, is mechanical load. Both primary and secondary cartilage have active morphogenetic potentials. For the primary cartilage this potential is essentially instrinsic, as has been demonstrated with transgenic mice, for instance. Consequently, primary cartilage is less adaptive to external influences than secondary cartilage. Analysis of the factors controlling the growth of the cartilaginous structures renders their utilization in reconstructive surgery more predictable.

Animals↗

PubMed1990

Mandibular condyle lesions, jaw movements, and occlusal status in 15-year-old children with juvenile rheumatoid arthritis.

The purpose was to determine the number and severity of lesions in the temporomandibular area and their association with occlusal status and mandibular movements in 15-yr-old children afflicted with juvenile rheumatoid arthritis (JRA). The series comprised 121 JRA children, 78 girls and 43 boys, and a control group of 104 schoolchildren, 70 girls and 34 boys, taken for clinical examination. Of the JRA children, 55% had roentgenologically detectable lesions in the TMJ area. Lesions were found in 60% of the girls and in 42% of the boys, the ratio thus being 3:2. The largest group had grave lesions (48%), the second largest displayed flattening of the condyle (43%) and the smallest a flattened condyle with a minor lesion (9%). There were more bilateral lesions in the children with the severest lesions. Tendencies for Class II malocclusion, small vertical overbite and open bite were visible in the JRA children. Reduced maximal opening capacity, maximal protrusion, lateral movements of the mandible and pain in the TMJ area proved to be reliable signs predicting temporomandibular joint involvement in JRA children. Maximal mouth opening capacity was significantly restricted in the patients showing condylar lesions as compared with patients having no lesions or with controls. JRA children should be divided according to sex and the severity of the lesions. The JRA children without TMJ lesions had normal values for mandibular movements and were thus comparable to healthy children.

Adolescent↗

PubMed1990

Ossification of the antler in the Lapland reindeer (Rangifer tarandus tarandus).

A histological and histochemical study of biopsy specimens from the Lapland reindeer antler indicated that the intercellular matrix of the cartilage that forms the partitions of longitudinal channels becomes calcified at virtually the initial stage of formation. The lacunae at the peripheries of the cartilaginous partitions are invaded by osteoblasts in a process comparable to endochondral ossification. The very centres of the partitions evidently become directly converted into bone without the presence of e.g. osteoclasts. The osseous partitions are remodelled by osteoclasts. The antler increases in diameter by periosteal apposition.

Animals↗

PubMed1990

Relation of the glenoid fossa to craniofacial morphology, studied on dry human skulls.

The purpose of this work was to compare glenoid fossa dimensions and craniofacial morphology on the basis of standard lateral roentgenograms. To overcome the difficulties encountered in making exact measurements on living subjects, 59 dry skulls were used. Eight angular measurements were taken to describe the form of the skull base, mandible, and articulating surface of the glenoid fossa, four linear measurements to describe the position of the fossa, and one to describe the size of the whole skull. A close relationship was observed between the morphology of the articulating surface of the glenoid fossa and the mandibular morphology. The skull base angulation was associated with the position of glenoid fossa in two ways. Basically, the position of the fossa is related to skull base characteristics, but the location of the articular eminence in relation to the clival plane suggests that the mandibular condyle may cause a remodeling of the eminence anteriorly when the glenoid fossa otherwise is translocated posteriorly in association with the flat skull base.

Adult↗

PubMed1989

Craniofacial morphology in untreated shunt-treated hydrocephalic children.

Craniofacial morphology was studied in 45 shunt-treated hydrocephalic children and 7 untreated hydrocephalic patients. A sample of 74 normal children from northern Finland were used as controls. Following shunt treatment the sella turcica became shallow and J-shaped. The cranial base angles changed markedly during shunt treatment. The cranial base angles were more obtuse in untreated patients than in control subjects, whereas the opposite was the case in shunt treated patients. The Nasion-Sella-Basion angle was 143.4 degrees in untreated hydrocephalic patients, 132.6 degrees in normal subjects and 127.9 in shunt-treated hydrocephalics. The changes in cranial base angles appeared to be progressive during a two-year follow-up period.

Adolescent↗

PubMed1988

The growth pattern of the clavicle in the rat.

The mode of growth of the rat clavicle from 17 to 45 days of age was studied by means of vital staining (alizarin red S), histology and autoradiography (tritiated thymidine). In addition the clavicle on one side was subjected to periostomy at the age of 10 days and its length compared with that of its unoperated counterpart at the ages of 17 and 45 days. The alizarin red staining revealed that the medial end of the clavicle contributes to the length of the bone, while the lateral end appears to have mainly an articulatory function. Histologically, the medial end cartilage closely resembles the condylar cartilage of the mandible, whereas the lateral end appears to be composed of two cartilaginous structures separated by a mesenchymatous layer. Tritiated thymidine was deposited in the mesenchymal cells covering the medial end cartilage, whereas virtually no activity was observed in the mesenchyme of the lateral end cartilage. The periostomised clavicle was more slender in appearance than its control throughout the observation period. The two clavicles were of the same length at 17 days, but by 45 days the periostomised clavicle was significantly longer than the control. It is suggested that the growth of the clavicle is essentially comparable to the growth of the mandible. Length growth occurs in response to the action of the surrounding structures, while analogously to the mandibular condyle, the medial end cartilage actively translates the bone in a direction perpendicular to the articular surface, giving rise to its curved shape.

Aging↗

PubMed1987

Cranial base morphology in untreated hydrocephalics.

Cephalostat radiographs of five untreated adult hydrocephalic patients were studied in order to explain events related to increased intracranial pressure and to differentiate them from those following shunt treatment. The hypophyseal fossa appeared to be well formed in every patient and no shallow fossa was found. The tip of the dorsum sella was rounded. The distances from the nasion to the sella region were increased, but those from the basion were decreased. The hypophyseal fossa was depressed inferiorly. The cranial base angle was more obtuse than in normal subjects or shunt-treated patients. The findings seem to indicate that a shallow. J-shaped sella results from the combined effect of the hydrocephalic condition and the shunt treatment, which cause a shortening of the anterior cranial base and move the fossa upwards and posteriorly away from the sphenoid bone.

Adult↗

PubMed1986