PubMed Health⌕ Search

Biomedical subjects

P Rygh

Publications and source records attributed to P Rygh.

7 recordsLinked to original sources
PubMed1992

Orthodontic magnets: effects on gingival epithelium and alveolar bone in monkeys.

The purpose of the present study was to examine soft and hard oral tissues in contact with or close to orthodontic magnets following an extended exposure time. Two male monkeys were used in the experiment. Individual silver splints covering the teeth from 17 to 27 in the upper jaw and 32-42 in the lower jaw were made. Co5Sm magnets were inserted with cold-curing acrylic buccally and lingually in the splints. The monkeys were injected with tetracycline at the start of the experiment and after 4 weeks. The epithelial thickness in buccal and lingual mucosa under the magnets and corresponding sites on the control side were estimated. The intensity of tetracycline fluorescence in the bone under the magnets and corresponding control sites was assessed semiquantitatively. A thinner epithelium compared to the controls and a patchy tetracycline-incorporation in the bone adjacent to orthodontic magnets in contrast to a homogeneous tetracycline fluorescent pattern in the controls were the most conspicuous findings. It cannot be excluded that the magnetic field or corrosion products from the magnetic material influenced vital processes in the epithelium and the bone close to the magnets. However, it cannot be concluded from the present study what cellular processes were affected.

Alveolar Process↗
PubMed1991

Root resorption after local injection of prostaglandin E2 during experimental tooth movement.

The purpose of this study was to investigate the occurrence of orthodontic root resorption in connection with local injection of prostaglandin E2 (PGE2). The material consisted of 25 male Wistar rats. The control group comprised six animals where no force was applied. In five animals 0.1 ml of 0.1 micrograms/microliter PGE2 was injected in the gingival area of the upper right first molar. In one animal no PGE2 was injected. The animals were killed after 3 days. The experimental tooth movement groups consisted of 19 animals. Duration of experiments was 3 days, 7 days, and 10 days. The maxillary first molars on both sides were each moved mesially by means of a coil spring. On the right side 0.1 ml of PGE2 0.1 micrograms/microliters was injected in the gingiva on the buccal side of the upper first molar on days 0, 3, 5, and 7. On the left side no injection of PGE2 was performed. In three animals in the 7-day group the vehicle (Waymouth medium) was injected. There was no significant difference in root resorption between the experimentally moved teeth with and without local injection of PGE2, but a trend towards more root resorption was registered on the teeth where such injections had been performed.

Animals↗
PubMed1990

[New treatment modalities for patients with cleft lip, jaw and palate].

Cleft lip/palate patients are reported at birth to a national register and are referred to one of the cleft palate teams in Oslo or Bergen. The teams coordinate the active treatment periods by plastic surgery, orthodontics/jaw orthopedics, logopedics, otology, pediatrics, psychology and orthognatic surgery. Presurgical orthopedics is performed early after birth in some total clefts with very asymmetric jaw segments. Lip is closed at 3 months, hard and soft palate at 1 1/2 years. Only a few cases now need early protraction of the upper jaw due to growth restraint. Many need orthodontic repositioning of the jaw segments and establishment of good occlusion. Bone from the ileac crest is grafted to the cleft prior to eruption of the canine. This permits normal development of the alveolar bone and eruption or, if the lateral is missing, orthodontic mesialization of the canine, excluding prosthetic replacement.

Adolescent↗
PubMed1986

Activation of the vascular system: a main mediator of periodontal fiber remodeling in orthodontic tooth movement.

The behavior and role of blood vessels and blood-borne cells in the process of the remodeling of the periodontal ligament (PDL) incident to experimental tooth movement was studied in rats. Particular interest was focused on areas of tension and of pressure with frontal bone resorption but without overt hyalinization. An increase of vascular activity occurred in the above mentioned situations. Extensive breakdown of collagen was observed in pressure areas with frontal resorption and in areas of tension concomitant with vascular invasion. Two patterns of fiber and bone remodeling were seen in areas of tension: intense vascular activity within the periodontal membrane and intense vascular activity inside the alveolar bone. Macrophages occurred consistently near blood vessels both in areas of tension and in areas of resorption. These are multipotent cells that obviously influence the remodeling process.

Alveolar Process↗
PubMed1977

Orthodontic root resorption studied by electron microscopy.

The present study supports previous findings that root resorption takes place simultaneously with and after the elimination of hyalinized tissue. The cementoid layer and the more mature periodontal collagen fibers adjacent to cementum are possible barriers preventing root resorption. The microenvironment around hyalinized tissue is favorable for the introduction of hard-tissue resorbing cells. The findings show that the elimination of hyalinized tissue leads to the removal of the cementoid and the mature collagen thus leaving a raw cemental surface without a barrier. It is therefore hypothesized that such an area is readily attacked by odontoclasts. Once resorption lacunae are established, the cementum is resorbed from the rear as an undermining process. By continued orthodontic force application the resorption process will proceed even after all hyalinized tissue is eliminated. If the orthodontic force is discontinued or falls under a certain level, the resorption lacunae are repaired.

Animals↗
PubMed1976

Ultrastructural changes in tension zones of rat molar periodontium incident to orthodontic tooth movement.

The purpose of this study was, by introducing transmission electron microscopy, to clarify fine details of tissue reactions in the periodontal ligament on the tension side. A preliminary investigation was undertaken on nine rats in which experimental tooth movement lasted 2 days, 14 days, and 28 days. It was hoped that these new observations might help in the planning and directing of further studies. A marked increase of interstitial spaces between the formed ligament structures of the periodontal ligament was characteristic of the initial phases of tension. The cells and the endoplasmic reticulum within the cells were spindle shaped and oriented in the direction of strain. Occasionally, collagen fibrils were observed within the cytoplasm of fibroblasts. During experimental tension a higher prevalence of elastic fibers was observed and new details of the reaction of collagen fibrils were obtained. The new cementum and bone deposited during the experiment were studied. The preliminary study indicated that electron microscopy may become a valuable tool for the study of the tension side.

Alveolar Process↗