Sven Lindskog - Academia.edu (original) (raw)

Papers by Sven Lindskog

International Journal of Oral Surgery, 1984

Ankylosis is a serious condition for the affected teeth as such teeth form part of the remodellin... more Ankylosis is a serious condition for the affected teeth as such teeth form part of the remodelling process of the alveolar bone and are therefore progressively resorbed. There are, however, very few clinical studies on tooth ankylosis and the reason for this may be due to the difficulties that are encountered in the diagnosis of minor areas of ankylosis. In the present study, the radiographs, percussion sound and mobility of experimentally extracted and replanted monkey incisors were compared with a morphometric histological study of ankylosis. Ankylotic areas were evident radiographically when the ankylosis was located on the proximal surfaces of the root, but were not evident when the ankylosis occurred on the lingual and labial surfaces. The percussion sound was dull and the mobility normal in all non-ankylotic teeth as well as in those teeth which histologically demonstrated ankylosis on less than 10% of the root surface. When the ankylosis affected 10-20% of the root surface, 2 out of 4 teeth changed their percussion sound from dull to high and these teeth no longer possessed normal mobility. When more than 20% of the root surface was affected with ankylosis, the percussion sound was characteristically high in all teeth and no mobility was present.

The use of permanent magnets in orthodontic treatment has increased significantly over the past y... more The use of permanent magnets in orthodontic treatment has increased significantly over the past years, triggered by the introduction of rare earth magnetic alloys. Concerns about possible side effects have been expressed relating to their use in orthodontic treatment. In previous experimental studies evidence of a reduction in bone formation and epithelial turnover close to rare earth magnets has been presented. The aim of the present study was twofold: to confirm earlier results and to study whether the observed changes are reversible. One hind leg in each of 45 rats was fitted with aluminum rings with Co5Sm magnets, whereas the other hind leg was fitted with sham rings. After 8 weeks 25 rats were killed, and the rings in the remaining rats were removed. The latter group was killed after another 11 weeks. The epithelial and bone reactions were evaluated histomorphometrically. Previous results showing thinner epithelium and retarded rate of bone formation close to Co5Sm magnets were confirmed. These effects were also shown to be largely reversible. It was concluded on the basis of this and the magnitude of the effects that any local side effects from orthodontic rare earth magnets appear negligible when extrapolated to the clinical situation.

The occurrence and appearance of cementum hypoplasias have been studied on teeth affected by juve... more The occurrence and appearance of cementum hypoplasias have been studied on teeth affected by juvenile periodontitis. Scanning electron microscopy showed the presence of cementum hypoplasias on the root surface of all extracted first molars and one incisor from nine patients with localized juvenile periodontitis and on most extracted teeth from two patients with generalized juvenile periodontitis. No hypoplasias were found on the extracted third molars. The alveolar bone loss in these patients seemed to be correlated to the frequency and extension of the hypoplastic areas in the associated teeth. The distribution of the teeth affected by localized juvenile periodontitis showed a symmetric distribution in the jaws. The patients with generalized juvenile periodontitis showed considerable deposits of dental calculus and wide areas of root resorption. The disturbance of cementum formation may have been caused by hereditary systemic factors, which subside with increasing age of the patient. The clinical appearance of juvenile periodontitis may therefore be influenced by the age at onset, the duration, and the frequency of such systemic factors, giving rise to a localized form and a more generalized form. One such factor may be a varying degree of hypophosphatasia.

Scandinavian Journal of Dental Research, 1990

Histomorphometric analysis of osteoclasts resorbing bone above the erupting first rat molar tooth... more Histomorphometric analysis of osteoclasts resorbing bone above the erupting first rat molar tooth germ was made at 1, 2, 6, 24, and 48 h following systemic administration of a single high dose of sodium fluoride. Compared to the number of osteoclasts in control rats, a significant reduction was observed in the number of actively resorbing osteoclasts in fluoride-injected rats at 2 and 6 h after dose administration, after which a gradual increase to control levels was observed. A locally increased number of inactive osteoclasts, not attached to bone surfaces, accompanied the reduced number of active osteoclasts.

Journal of Dental Research, 1983

Several red stripes appeared on the surface of the rat incisor enamel at the maturation stage whe... more Several red stripes appeared on the surface of the rat incisor enamel at the maturation stage when stained with a modified glyoxal bis (2-hydroxyanil) method (GBHA). The stripes running across the maturation enamel were correlated directly, morphologically, and indirectly, using 45Ca autoradiography, with the bands of overlying smooth-ended ameloblasts. In addition, GBHA strain revealed similar stripes on the maturation enamel of the developing teeth from a variety of animals (rat molar, bovine incisor and molar, porcine canine, and monkey incisor), indicating that the maturation of the mammalian tooth enamel, in general, is under the control of two types of maturation ameloblasts which undergo cyclic morphologic changes.

Cell and Tissue Research, Sep 30, 1996

Glial-cell-line-derived neurotrophic factor (GDNF) is a distant member of the transforming growth... more Glial-cell-line-derived neurotrophic factor (GDNF) is a distant member of the transforming growth factor-beta family and has potent neurotrophic effects on several classes of neurons including dopamine neurons and motoneurons. Here, we have used in situ hybridization to describe the development of the cellular expression of GDNF mRNA pre- and postnatally. Consistent with dopaminotrophic activity, GDNF mRNA is expressed in the developing basal ganglia and the olfactory tubercle. It is also found in a thalamic nucleus, in neurons of the substantia innominata, in the developing Purkinje neurons and the developing locus coeruleus area, and in trigeminal brainstem nuclei. In the spinal cord, neuronal expression is found in Clarke's column. GDNF mRNA is also expressed in the dorsal horns during development. Additional GDNF mRNA expression in the head region includes the carotid body, the retina, the vibrissae, the inner ear, the ear canal, and epithelium in the nasal cavity. Prominent expression is also found in the developing teeth. The widespread expression of GDNF in developing skeletal muscle is consistent with trophic activity on alpha-motoneurons. The smooth muscle layers of the gastrointestinal tract are also strongly positive. A very strong signal is found in the outer mesenchyme of the developing metanephric kidney. We conclude that GDNF mRNA is expressed in many different cellular systems inside and outside the central nervous system during development, suggesting multiple functions of GDNF in the developing organism.

Endodontics Dental Traumatology, Feb 1, 1986

AbstractAbstract The major causes of post-replantation tooth loss are inflammatory root resorptio... more AbstractAbstract The major causes of post-replantation tooth loss are inflammatory root resorption and root resorption associated with ankylosis. Recent studies have concentrated on delineating the cellular interactions in the pulp and periodontium in order to more fully understand the various factors affecting the prognoses of such teeth. The aim of this report is to discuss the nature of the pathology responsible for tooth loss following avulsion and to review recent replantation and attachment studies.

ABSTRACT A new method for measuring the width of the periodontal ligament (PDL) in orthodonticall... more ABSTRACT A new method for measuring the width of the periodontal ligament (PDL) in orthodontically treated rats has been presented. For the present experiment the first upper molar in twelve young adult Spraque-Dawley rats were moved buccally with forces up to 700 mN. The appliance used was modified according to Kvam (13) and Rygh (32). After 24 h the rats were sacrified and the sculls were embedded in carboxymethylcellulose and frozen. In a predetermined area the surfaces of the specimens were stained with silver-nitrate and photographed. Some sections were also collected on tape and stained with hematoxylin and eosin. The width of the PDL decreased with increasing forces following a logarithmic function. When the PDL was compressed more than 30% on the buccal side and 40% on the palatal side, red areas indicating extravasated blood were found in the pressure zones. Bending of the buccal alveolar plate was associated with strong orthodontic forces. The contralaterals to the orthodontically treated teeth were also affected. The method described seems to be the first attempt to systematically correlate the compression of the PDL to the strength of the orthodontic force and to allow a simultaneous evaluation of histochemical and histological changes.

The effect of media with different osmolalities and compositions on cell viability and integrity ... more The effect of media with different osmolalities and compositions on cell viability and integrity of the cell membrane has been studied. Physiologic media, such as milk, saline and physiologic sucrose solution, preserved cell viability and membrane morphology equally well. The cell membrane of cells stored in saliva was more extensively damaged than the cell membrane of cells stored in a sucrose solution with an hypotonic osmolality similar to saliva. Thus a hypotonic osmolality seemed to potentiate the damaging effect of an unfavourable composition or a bacterial contamination of the storage media.

Acta Odontol Scand, 1994

The buccal surfaces of premolar teeth are common sites of gingival recession, generally attribute... more The buccal surfaces of premolar teeth are common sites of gingival recession, generally attributed to overzealous oral hygiene. Scanning electron microscopy (SEM) of replicas made from dental impressions was applied to document the micromorphology of the buccocervical region of all premolar teeth in 27 dentally healthy, young adults. The SEM observations were correlated with clinical examination. Of the 216 sites, one-third, predominantly the maxillary first premolars, had gingival recession, but fewer than 50% were clinically discernible. The exposed roots were devoid of cementum, and the dentinal surface was smear-like or dotted with tubular apertures from which droplets of fluid extruded. SEM of replicas of gingiva, recorded as clinically healthy, frequently showed signs of inflammation: fluid exudate and distortion of gingival contour by swelling. The cervical enamel of healthy and affected sites showed characteristic periodic fissure-like cracks, probably enamel tufts. The high frequency of subclinical gingival recession, exposed cervical dentin, and gingival inflammation in dentally healthy young adults, in the absence of abrasion of hard or soft tissues, indicates the need to review conventional concepts of initiation of buccal recession and root exposure.

Oral Surgery Oral Medicine Oral Pathology, Apr 1, 1987

Acta Odontologica Scandinavica, Sep 1, 1999

The purpose of the present study was to examine the morphology of healthy dentin surfaces after t... more The purpose of the present study was to examine the morphology of healthy dentin surfaces after treatment with Carisolv followed by conditioning with phosphoric acid and EDTA, since surface morphology may be of interest for dentin bonding. Another purpose was to evaluate the effect of treatment with Carisolv on healthy non-carious dentin surfaces with exposed collagen fibers. Scanning electron microscopy was utilized to carry out a detailed morphological examination of the dentin surfaces with regard to presence or absence of both smear layer and collagen fibers. Twelve premolars extracted for orthodontic reasons from young adults were used. The two etchants appeared to have produced two distinctly different surfaces. Etching with phosphoric acid following Carisolv treatment resulted in a porous dentin surface, while EDTA etching without prior Carisolv treatment appeared to have uncovered an intact collagen network. In contrast, the surfaces treated with Carisolv prior to EDTA etching displayed smooth intertubular surfaces with only occasional fibers. Apparently, the ability of EDTA to expose collagen in the dentin surface is counteracted or inhibited by the Carisolv treatment. Furthermore, it cannot be excluded that the Carisolv treatment in itself may have dissolved collagen fibers. Since most bonding systems claim bonding to the collagenous component of dentin, the question arises which of the etched surfaces is preferable and to what degree the collagenous component contributes to bonding strength. Further studies are thus needed to evaluate the micromechanical retention of a restoration to the different surfaces described in the present study.