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Biomedical subjects

I Kvinnsland

Publications and source records attributed to I Kvinnsland.

16 recordsLinked to original sources
PubMed1994

Nerve fibres and cells immunoreactive to neurochemical markers in developing rat molars and supporting tissues.

The distribution of nerve fibres immunoreactive to calcitonin gene-related peptide (CGRP), substance P (SP) and neuropeptide Y (NPY) was compared to the general neurochemical markers for nerves and neuroendocrine cells protein gene product 9.5 (PGP 9.5) and neurone-specific enolase (NSE), by use of the avidin-biotin peroxidase complex method in developing dental structures in rats aged 13 to 27 days. A substantially greater part of the nerve fibres was immunoreactive to CGRP and SP than to NPY. In the bell stage, nerve fibres immunoreactive to PGP 9.5, CGRP and SP were found in the dental follicle but not in the dental papilla and stellate reticulum. In the advanced bell stage, after initiation of dentine and enamel formation, PGP 9.5, CGRP- and SP-immunoreactive fibres were found in the dental papilla, while the first NPY-immunoreactive fibres were observed in the papilla when root formation started. Concomitant with the beginning of root development, a subodontoblastic nerve plexus was gradually formed and PGP 9.5-, CGRP- and SP-immunoreactive fibres were found within the dentinal tubules. From the start of root formation, CGRP-, SP- and NPY-immunoreactive nerves were shown in the developing periodontal ligament, although a mature distribution pattern was not observed until root formation was nearly completed. Ameloblasts, odontoblasts and cell-like structures in the outer enamel epithelium and within the dental lamina were PGP 9.5-immunoreactive at the bell stage. As the tooth matured, the immunolabelling gradually decreased, but was still present in some odontoblasts after tooth eruption. NSE-immunoreactive, cell-like structures were found in the periphery of the dental follicle, and persisted close to alveolar bone in the periodontal ligament when the tooth reached occlusion. Hence, it may be concluded that sensory nerves containing SP and CGRP are present in the pulp in advance of sympathetic nerves immunoreactive to NPY.

Alveolar Process↗
PubMed1993

Nerve fibers immunoreactive to protein gene product 9.5, calcitonin gene-related peptide, substance P, and neuropeptide Y in the dental pulp, periodontal ligament, and gingiva in cats.

The distribution patterns of nerve fibers immunoreactive (IR) to calcitonin gene-related peptide (CGRP), substance P (SP), and neuropeptide Y (NPY) in the dental pulp, periodontal ligament (PDL), and gingiva were studied and compared with the complete innervation visualized by antibody to protein gene product (PGP) 9.5 in adult cats. The pulp showed considerably denser nerve supply for PGP 9.5, CGRP, and SP than the periodontal tissues. Most of the pulpal fibers were CGRP-IR, and approximately three to four times more IR fibers were labeled with CGRP than SP. Most fibers in the odontoblast area penetrating into the dentin tubules were CGRP-IR. NPY-IR nerves were mainly observed in connection with the larger blood vessels in pulp and PDL. In the PDL most nerves were localized in the apical third in connection with blood vessels, but CGRP-IR fibers extending close to root cementum were often observed. Immunoreactivity to PGP 9.5 and CGRP was frequently found in cell-like structures in connection with Malassez epithelium in the PDL and in some round epithelial-like cells located in the base of gingival rete pegs.

Animals↗
PubMed1993

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.

Animals↗
PubMed1992

Analysis of low affinity nerve growth factor receptor during pulpal healing and regeneration of myelinated and unmyelinated axons in replanted teeth.

Nerve regeneration was examined in rat molars that were briefly extracted and then replanted in the socket for 1-90 days. Immunocytochemistry was used to evaluate neural and nonneural immunoreactivity (IR) for low affinity nerve growth factor receptor (p75-NGFR) and for laminin and calcitonin gene-related peptide (CGRP). Three different types of pulpal response to replantation were found. Type I: Some replanted teeth had mild injury and still contained coronal odontoblasts and associated fibroblasts that retained p75-NGFR-IR; they continued regular dentin formation and had excellent reinnervation. Type II: Teeth with intermediate injury lost most or all of the coronal pulp tissue, but they regenerated odontoblast-like cells that formed irregular dentin, they had numerous dispersed p75-NGFR-IR fibroblasts in crown pulp during early regeneration, and they had excellent reinnervation. Type III: Severely injured teeth lost their original pulp; they filled with dense connective tissue and bone and had poor reinnervation. After Type I or II injury the Schwann cells around degenerating myelinated and unmyelinated axons had increased expression of p75-NGFR by 1-3 days. By 7-10 days those Schwann cells had formed hollow tubes (bands of Bungner) along the degenerating axon tracks. They maintained their increased p75-NGFR-IR during and after regeneration of unmyelinated axons, whereas Schwann cells involved in remyelination lost p75-NGFR-IR at that stage. The number of CGRP-IR axons in the regenerating pulp increased from 7 to 90 days. Laminin-IR increased in all replanted teeth at 3-10 days and only returned to normal patterns in teeth with Type I or Type II response at 20-90 days. The special p75-NGFR-IR of pulpal fibroblasts of adult rat molars did not usually persist in regenerated, reinnervated pulp. The extensive depletion of fibroblast p75-NGFR-IR and the continuing enhanced p75-NGFR-IR in unmyelinated nerve fibers at 90 days show that altered growth factor conditions characterize regenerated pulp of replanted teeth.

Animals↗
PubMed1992

Effect of traumatic occlusion on CGRP and SP immunoreactive nerve fibre morphology in rat molar pulp and periodontium.

Traumatic occlusion provides a trauma that affects the whole tooth and its supporting tissues. To study the effect of this trauma on CGRP and SP immunoreactive nerve morphology in pulp and periodontium, traumatic occlusion was induced in 2-months-old rats. The occlusal surface of the first maxillary molar in 30 rats were unilaterally raised 1 mm with a composite material. At different observation periods up to 30 days, the rats were transcardiacally perfused, the jaws demineralized, sectioned and processed for immunohistochemistry with the avidin-biotin-peroxidase method. Changes in nerve morphology, distribution and density in first and second molars and their supporting tissues were analyzed and compared in experimental (n = 30) and control rats (n = 14). Already after 5 days with traumatic occlusion, 22% of the experimental teeth had increased density of CGRP and SP immunoreactive nerves locally in gingiva, the periodontal ligament and the pulp, while in 15%, axonal proliferation and changed nerve morphology were found in the whole pulp (severe reaction). During a 20-day period, the pulpal nerve reactions progressed and included the whole pulp in 46% of the experimental teeth. The periodontal nerve responses were still localized only to the cervical and apical regions, and they remained local in these areas throughout the experimental periods. After 20 days the number of teeth with severe nerve changes seemed to decrease. The study shows that an unilateral change in occlusion of the first molar initiate nerve responses in the total molar dentition. In this experimental model the pulpal axons containing CGRP and SP reacted more serious to occlusal trauma than the nerves in the periodontium. The results indicate that the nerve changes in some cases might be transient.

Animals↗
PubMed1992

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.

Animals↗
PubMed1992

Effects of dental trauma on pulpal and periodontal nerve morphology.

Regeneration and morphological changes in sensory peptidergic nerves in pulp and periodontium were studied after general dental trauma by means of immunohistochemistry. In control teeth also the total nerve supply was demonstrated by using antibody to the general neuronal marker, protein gene product (PGP)9.5. Two experimental rat models were used, i.e. tooth replantation and induced traumatic occlusion. Results from these studies are reviewed here. In the controls, the PGP9.5-immunoreactive(IR) nerve supply in pulp and periodontium was generally denser compared to CGRP-IR and SP-IR nerves. In the replanted teeth, regeneration of CGRP-IR nerves closely followed the pulp cell renewal. Density and distribution of the regenerated nerves showed two different patterns which seemed to depend on the capacity of the renewed pulp to form postoperative dentine. The nerve density never reached the same level as the controls. In teeth not able to form irregular dentine, the pulp was sparsely innervated and the pulp cavity was filled with innervated bone. Nerve responses in CGRP-IR and SP-IR nerves after unilateral induced traumatic occlusion in the first maxillary molar were studied at different observation periods up to 30 days. After 5 days, localized morphological nerve changes were found both in the pulp and periodontium within the total rat molar dentition. With increasing observation periods, the pulpal neural changes progressed and were extended to all pulpal areas compared to the periodontium, where the nerve responses remained localized to cervical and apical tissues throughout the experiment.

Animals↗
PubMed1992

Tissue pressure and blood flow in pulpal inflammation.

The initial vascular reactions during inflammation are vasodilation and increased vessel permeability. Both these basic reactions cause increased pulpal fluid volume. In the dental pulp the inflammatory vascular reactions take place in a rigid enclosed dentin chamber, which to some extent makes the pulp vulnerable. Due to this lack of distensibility any gain in pulpal volume will necessarily increase the pulpal tissue pressure. If the tissue pressure rises to the same level as the blood pressure it will compress the pulpal vessels, thus counteracting a beneficial blood flow increase during inflammation. Using the micropuncture technique and laser Doppler flowmetry we have performed simultaneous measurements of tissue pressure and blood flow in the cat dental pulp during neurogenic inflammation. Sensory nerve stimulation caused a rise both in blood flow and tissue pressure. Our findings thus strongly suggest that the increased pulpal tissue pressure promote fluid absorption back into the blood. If, in theory, plasma proteins and other macromolecules had leaked out during sensory nerve stimulation they must have been successfully removed by lymphatics, unless the tissue pressure would have risen to the same level as the capillary blood pressure causing a fall in PBF. This was not found. On the contrary, increased blood flow was measured, even in experiments lasting for more than 8 hours. It is therefore concluded that the pulp may have a beneficial blood flow increase during inflammation in spite of simultaneously increased tissue pressure.

Animals↗
PubMed1991

Regeneration of calcitonin gene-related peptide immunoreactive nerves in replanted rat molars and their supporting tissues.

First maxillary right molars in 66 rats were elevated and replanted and the pulps allowed to regenerate for 1-90 days. The contralateral tooth served as control. Regeneration of nerves in the pulp and periodontium was studied by CGRP-immunohistochemistry and the avidin-biotin-peroxidase method. The pulp and periodontium of the controls were richly supplied with CGRP-labelled nerves. One day after replantation the pulp was completely devoid of CGRP-immunoreactive nerves. After 2 days, axon sprouts were present in the apical, regenerated pulp and in the periodontium. From 3-7 days CGRP-immunoreactive axons were regularly seen to have regenerated in front of the cellular inflammation in the pulp. After 10 days, the pulps were reinnervated up to the horns, although more sparsely than in the controls. From day 20-90 there was a marked divergence in pulpal healing: 17 pulps formed irregular postoperative dentine with a gradual increase in nerve density; 16 pulps remained sparsely innervated and were gradually replaced by bone. Root resorption was most extensive in the teeth with bone replacement of pulp. The soft tissue adjacent to extensive resorbing areas had many more CGRP-labelled axons than in the controls. The reinnervation of the regenerating pulp occurred at the same time as pulpal wound healing, but did not achieve the innervation density of the controls.

Animals↗
PubMed1990

Changes in CGRP-immunoreactive nerve fibres during experimental tooth movement in rats.

Immunohistochemical localization of calcitonin gene-related peptide (CGRP) was used to investigate changes in nerves expressing CGRP in periodontium and pulp during experimental mesial movement of the first maxillary molar in rats. The orthodontic appliance consisted of a coil spring connecting the first maxillary molar on one side to the central incisors. After 5 days with a continuous force of 30-50 g the animals were perfused after an overdose of anaesthetic. Serial sections from the experimental and control jaws were exposed to the avidin-biotin-peroxidase technique for demonstration of CGRP-immunoreactive (IR) nerve fibres. The induced tooth movement caused reproducible changes in the relative number of CGRP-IR nerves as well as morphological alterations within parts of the nerve supply of the experimental teeth and related tissue structures. The majority of the experimental teeth showed increased number of CGRP-IR nerves in the coronal pulp and periapical tissues. The results indicate that peptidergic nerve fibres immunoreactive for CGRP takes an active part in tissue responses in pulp and supporting tissues during experimental tooth movement.

Animals↗
PubMed1990

Cell renewal and ground substance formation in replanted cat teeth.

The cellular dynamic pattern of pulpal healing 4, 10, 30, and 60 days after replantation of 47 apicoectomized cat incisors was studied after pulse labeling with 3H-thymidine and 35S-sulfate, autoradiography, and routine histology. In the control teeth the labeling index was less than 0.05%. The apical pulpal cells were capable of ground substance formation and cell proliferation already 4 days after replantation, with a labeling index of 7%, which increased up to 43% within 10 days. A gradual postoperative restitution and reorganization within the pulpal cellular compartment was seen. The maximum cell density, reached after 30 days, was reduced to on average 60% compared with the controls. The tissue reorganization was near completion within all pulpal zones after 60 days, and the labeling index was reduced to 2.5%. In some instances internal resorption in cervical pulpal areas negatively influenced the favorable healing. The present study shows that the pulpal healing in replanted teeth follows a consistent basic pattern in cellular dynamics and in histologic changes. The replanted tooth thus seems to be a suitable model for studies of healing and repair in connective tissues.

Animals↗
PubMed1989

A clinical and roentgenological study of 55 cases of root perforation.

The treatment outcome of 55 root perforations in man were related to pretreatment conditions and various treatment procedures used, with a mean recall period of 3 years 5 months. In this study maxillary teeth were perforated three times more often (74.5 per cent) than mandibular teeth (25.5 per cent); 47 per cent of the perforations were due to endodontic and 53 per cent due to prosthodontic treatment. The buccal and mesial root surfaces as well as the midroot areas were most often perforated. In 25 per cent, radiographic changes were directly related to the perforated areas. Twenty-eight perforations were repaired by orthograde fillings with gutta-percha and Kloro-percha N-phi; eight received a combined orthograde and surgical repair, and in only three cases a surgical approach was used. Four cases received no treatment but were recalled, and twelve perforations showed a size and location hopeless for repair; the teeth were therefore extracted. Five failures of the primary orthograde treatment group later underwent surgical treatment and were followed up for 3 years 3 months. The overall success rate in the primary treatment group of teeth was 56 per cent while 36 per cent became failures. Five failures were retreated, and four of these became successful. A combined orthograde and surgical repair of the perforations provided the most favourable outcome with 92 per cent successful. The study stresses the importance of preventing this type of treatment complication.

Humans↗
PubMed1989

Dentin and osteodentin matrix formation in apicoectomized replanted incisors in cats.

The reestablishment and rate of osteodentin and dentin matrix formation in 27 apicoectomized replanted and 20 control incisors in cats were studied after Procion H8-BS vital staining. In control teeth the pattern of matrix formation differed in the various pulpal zones, with a higher rate of matrix formed toward apical areas, most dominantly in maxillary incisors. Osteodentin formation could be traced after a lag period of more than 10 days after replantation. Thirty and 60 days postoperatively osteodentin matrix was found in the total pulpal length in 83% and 73% of the teeth, respectively. A common finding was a tubular osteodentin matrix in the pulpal apical third in the replanted teeth. Tubular osteodentin matrix was, however, present most incisally in some teeth 60 days postoperatively. Internal resorption corresponding to outer cervical lesions dominated the pulpal reactions in the maxillary replanted teeth after 60 days. It is concluded that under the present experimental conditions the pulp tissue possesses a high healing potential and that the osteodentin formation reflects the pulpal healing pattern after replantation traumas. The results also indicate that successful pulpal healing depends on unexposed dentinal tubules.

Animals↗