Steinar Kvinnsland

Effect of experimental traumatic occlusion on periodontal and pulpal blood flow

Fluorescent microspheres (FM) were used to visualize and semi-quantify flood flow in the periodontal ligament (PDL) and dental pulp during experimental traumatic occlusion of the maxillary and mandibular molar teeth in young rats. At different observation points FM were injected systemically, and the number of FM was counted in serial sections from the jaws in the PDL and pulp of the molar teeth in a fluorescent microscope. Blood flow was related to the number of FM in the tissues and in a reference blood sample. In the early stages an increase in blood flow in the PDL and dental pulp was found on the experimental side compared with the contralateral side. Furthermore, there was an increase in blood flow on both sides of the jaws compared with an unoperated control material. The study thus indicates that a local unilateral occlusal trauma initiates blood flow responses in the total molar dentition in rats.

The Sagittal Growth of the Foetal Cranial Base

There is an increase in the angular relationship between the anterior and posterior cranial components in foetal life. The angular changes taking place seem to occur in the region of the sphenoethmoidal junction. The spheno-occipital element of the cranial base showed stability during foetal life, whereas the spheno-ethmoidal part of the cranial base angles increased in the corresponding period. A large angle in any one of the cranial base angles is followed by large angles in the rest of the cranial angles. A large cranial base angle is followed by a large anterior total facial height and a relatively posterior rotation of the upper jaw, retrognathic lower face and a relatively posterior rotation of the lower jaw. The growth of the anterior cranial base is more active than the growth of the posterior cranial base. The ethmoidal and sphenoidal parts of the anterior cranial base contribute equally to the increase in length. A long anterior cranial base is followed by a large spheno-ethmoidal angle and rela...

Epithelial restitution and cellular proliferation after gastric mucosal damage caused by hypertonic NaCl in rats

Hypertonic NaCl enhances gastric cancer in rats induced by N-nitroso compounds. This study was designed to examine the structural changes and alterations in mitotic activity occurring after mucosal exposure to hypertonic NaCl. Wistar rats were given one ml of 4.5 M NaCl by gastric tube and groups of 4–5 animals were sacrificed at different time intervals up to 120 h. An i.p. injection of thymidine was given 1 h before death. Samples of antral and corpus mucosa were prepared for microscopy and autoradiography. Hypertonic NaCl caused uniform destruction of surface mucous cells and pits in the corpus and antrum. Epithelial restitution with the formation of a thin epithelial layer occurred within one h of damage. The mucosa changed towards normal within 24–48 h. The distance between mucosal surface and the replicating cells decreased during the first 2 h. The proliferation zone remained in the middle of the glandular layer throughout the experiment. The proliferative activity increased during the first 24 h after mucosal damage. The number of labelled cells per unit area of mucosa was somewhat larger in the corpus than the antrum, but in the corpus the distance between proliferating cells and mucosal surface was double that of the antrum. Hypertonic NaCl causes a series of changes in the gastric mucosa. The increased mitotic activity can only partly explain the cocarcinogenic effect, since N-nitroso-induced adenocarcinomas occur predominantly in the antrum while the mitotic activity is maximal in the corpus.

Effect of inferior alveolar nerve axotomy on periodontal and pulpal blood flow subsequent to experimental tooth movement in rats

The aims of this study were to evaluate the effect of inferior alveolar nerve (IAN) axotomy on periodontal (PDL) and pulpal blood flow incident to experimental tooth movement and to investigate whether nerve fiber regeneration coincides with blood flow changes. The first right mandibular molar was moved mesially for 3, 7, and 14 days after ipsilateral IAN axotomy in 29 rats. Four rats served as unoperated controls. At the end of each experimental period fluorescent microspheres (FM) were injected into the left ventricle and thereafter counted in serial sections in the PDL and pulp of the right and left first mandibular molars. The number of FM per tissue volume was taken as a measure of blood flow. Re-innervation of nerve fibers was mapped immunohistochemically 7, 14, and 21 days after IAN axotomy in 9 rats that had no orthodontic appliance. The statistical analysis showed no significant differences in the number of FM/mm3 PDL between the denervated and the contralateral side at 3 and 7 days. At 14 days the PDL on the denervated side showed a significant increase in the number of FM/mm3, coinciding with the initial periodontal nerve fiber re-innervation. In the pulp no significant differences were found between the denervated and the contralateral, innervated side in any experimental period. It can be concluded that IAN axotomy postpones an increase in periodontal blood flow until a sensory tissue re-innervation is established, thus indicating that neurogenic mechanisms play an important role in the development of the inflammatory reaction induced by experimental tooth movement.

Growth in height of autotransplanted nasal septum in the rat Its correlation to increase in height of the upper face

The present investigation was undertaken in an attempt to elucidate the role of the cartilagenous nasal septum in facial growth. The increase in height of autotransplanted nasal septum was compared to the normal increase in anterior and posterior facial heights in rats. A similarity was found both in the general pattern of growth and in the dimensional increase. This tends to agree with the theory that the cartilagenous nasal septum has its own growth potential.

Effect of experimental traumatic occlusion on blood flow in the temporomandibular joint of the rat

Fluorescent microspheres (FM) were used to visualize and semi-quantify blood flow in the temporomandibular joint (TMJ) during experimental unilateral traumatic occlusion of the maxillary and mandibular molar teeth in 30 young rats. At different postoperative observation periods varying from 1 to 30 days FM were injected systemically, and the number of FM were counted in serial sections from the TMJ in a fluorescent microscope. Blood flow was related to the number of FM found in the fibrous connective tissue and bony condyle of the TMJ. A percentage increase in blood flow was found at 15 to 20 days on the experimental side, compared with the contralateral side. Furthermore, there was an increase in blood flow in both TMJs in the experimental animals compared with an unoperated control material of 10 animals. The study thus indicates that a local unilateral occlusal trauma initiates blood flow responses not only unilaterally but also in the TMJ on both sides in rats.

The Sagittal Growth of the Lower Face During Foetal Life

The mandibular line (ML) seems to show stability with both the anterior cranial base (NSI,) and with the Nasal Line (NL) during foetal lifr. The jaw angle, gn—go—co also shows angular stability during the same period. These findings suggest that the lower jaw follows the angular changes found in the cranial base, nasal septum and the upper jaw, the primary factor being possibly the cranial base. There is a reduction in the prognathic development of the lower jaw in the period investigated. Increased lower face prognathism seems to be associated with an anterior rotation of the lower jaw. Lower anterior facial height increases more than upper anterior facial height whereas horizontal growth of the lower face shows less increase than the anterior cranial base, nasal septum and upper jaw. Increased lower face height is followed by a long lower jaw, a large jaw angle and an increased distance between the condyle and NSL. Increase in the sm-NSP distance seems to be associated with a relative anterior position ...

The Sagittal Growth of the Upper Face During Foetal Life

The nasal septum seems to be stable in its angular relationship with the anterior cranial base The Nasal Line NL despite an initial small increase seems to follow the same trend as the anterior cranial base and nasal septum in their angular behaviour to the posterior cranial base. There is an increase in the prognathic development of the upper jaw in relationship to NSL. The correlation analysis tends to show that a posterior rotation of the Nasal Line (NL) and the Septal Line (SL) in relation to the cranial base will lead to a reduction in upper jaw prognathism whereas an anterior rotation of NL and SL to the anterior cranial base will be followed by an increase in upper jaw prognathism. Upper facial prognathism is associated with the length and also with the relative forward position of the upper jaw and nasal septum. Increased upper facial prognathism seems to be associated with a distal basal relationship between the two jaws. There seems to be an anterior shift of the transverse maxillo-palatine sutu...

Delayed Recruitment of Immunocompetent Cells in Denervated Rat Periodontal Ligament Following Experimental Tooth Movement

It has previously been shown that the number of mononuclear phagocytic cells in the periodontal ligament (PDL) of orthodontically moved rat molars is significantly increased (p ≤ 0.05) at 3, 7, and 14 days compared with the controls. Since these changes coincide with increased density of peptidergic nerve fibers, it was of particular interest to investigate a possible relation between the immunocompetent cells and sensory nerve fibers in the PDL of experimentally moved and denervated rat molars. Twenty-two young animals had the first right mandibular molar moved mesially, 7, 14, and 21 days after ipsilateral inferior alveolar nerve axotomy. The left side served as unoperated control. An immunohistochemical procedure was carried out on alternate, serial, cryostat sections with antibodies against CDllb (macrophages, dendritic cells) and class II major histocompatibility complex (MHC) molecules (RT1B). At 7 and 14 days, the number of CDllb+- and RTlB-expressing cells in the denervated PDL showed no significant difference compared with the contralateral side. However, at 21 days, when periodontal tissue re-innervation is established, the number of the investigated immunocompetent cells in the PDL of the denervated and experimentally moved mandibular molars demonstrated a significant difference compared with the contralateral and control molars (p ≤0.05). It can be concluded that axotomy of the inferior alveolar nerve delays the recruitment of macrophage-like and class II MHC molecule-expressing cells in the PDL of orthodontically moved rat molars. The results further indicate that sensory nerve fibers interact with immunocompetent cells and participate in their mobilization to locally inflamed tissues.

The changes in craniofacial growth following papain administration in young mice

The effect on craniofacial growth after repeated papain administrations was studied in young mice. The length of the upper face and lower face were both seriously affected whereas the length of the neurocranium, the anterior height of the upper and lower face were moderately affected.The posterior height of the upper face and the height of the neurocranium were not influenced by papain injections.