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Biomedical subjects

T Karring

Publications and source records attributed to T Karring.

At least 73 records · Page 4Linked to original sources
PubMed1988

Stress-induced blocking of cell division in the colchicine arrest technique.

Previous studies have shown that procedures commonly used in studies of cell population kinetics in laboratory animals cause a transient block of the entrance of cells into mitosis. The purpose of the present study was, therefore, to examine whether the handling of animals in conjunction with the administration of colchicine affects the results obtained by the metaphase arrest technique. Groups of rats were injected with colchicine or saline at 1300 h and sacrificed at regular intervals during the following 140 min. Histological sections of the palatal mucosa were produced and the number of metaphases was assessed in the epithelium. In both the saline-treated and colchicine-treated groups the numbers of metaphases decreased immediately after injection and reached a minimum within 30 min. After that time a transient increase was observed in the saline group, whereas the number of metaphases in the colchicine-treated group increased continuously during the experimental period. These results indicate that colchicine takes effect after a delay period of 30 min and that the handling procedures in conjunction with the administration of colchicine provoke a transient block of the entry of cells into mitosis. The second part of the study was designed in such a way that the number of metaphases collected during a 2 h period under the influence of stress induced by injection of colchicine could be compared with the number of metaphases collected during the same time period without the influence of stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Albinism↗
PubMed1988

Guided tissue regeneration in degree II furcation-involved mandibular molars. A clinical study.

The present clinical trial was designed to evaluate the regenerative potential of the periodontal tissues in degree II furcation defects at mandibular molars using a surgical treatment technique based on the principles of guided tissue regeneration. The patient sample included 21 subjects, 22-65 years of age. The patients selected had periodontal lesions in the right and left molar regions including advanced periodontal tissue destruction within the interradicular area. After an initial examination, each patient received a series of full-mouth scalings and root planings. 2-3 months later, they were recalled for a baseline examination including assessment of plaque, gingivitis, probing depths and probing attachment levels. The furcation involved molars were randomly assigned in each patient to either a test or a control treatment procedure. The test procedure included the elevation of mucoperiosteal flaps at the buccal and lingual aspect of the alveolar process. The inner surface of each flap was carefully curetted to remove epithelium and granulation tissue. The root surfaces were scaled and planed. A teflon membrane was adjusted to cover the entrance of the furcation area and the adjacent root surfaces as well as a portion of the alveolar bone apical to the crest. The flaps were repositioned and placed on the outer surface of the membrane and secured with interdental sutures which were removed after 10 days of healing. Following surgery, the patients were instructed to rinse the mouth twice daily with chlorhexidine gluconate. A second surgical procedure was performed after a healing period of 1-2 months to remove the teflon membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Role of "diseased" root cementum in healing following treatment of periodontal disease. A clinical study.

This clinical trial was undertaken to examine whether root debridement in the treatment of periodontal disease must include the removal of the exposed cementum in order to achieve periodontal health. The study included 11 adult patients with moderate to advanced periodontal disease. In a split-mouth design, the dentition of each patient was by random selection divided into test- and control quadrants comprising the incisors, canines and premolars. Following a baseline examination, all patients were given a case presentation and a detailed instruction in self-performed oral hygiene measures. The patients were then subjected to periodontal surgery. Following reverse bevel incisions, buccal and lingual mucoperiosteal flaps were elevated and all granulation tissue was removed. In 2 jaw quadrants (control quadrants) in each patient, the denuded root surfaces were carefully scaled and planed in order to remove soft and hard deposits as well as all cementum, using hand instruments and flame-formed diamond stones. In the contralateral quadrants (test quadrants) the roots were not scaled and planed but soft microbial deposits were removed by polishing the root surfaces with the but soft microbial deposits were removed by polishing the root surfaces with the use of rubber cups, interdental rubber tips and a polishing paste. Calculus in the test quadrants was removed by the use of a curette, but precaution was taken to avoid the removal of cementum. The flaps were repositioned to their original level and sutured. The patients were following active treatment enrolled in a supervised maintenance care program including "professional tooth cleaning" once every 2 weeks for a 3-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Surgical treatment of severe periodontitis in a haemophilic patient with inhibitors to factor VIII. Report of a case.

This report describes the surgical treatment of advanced periodontitis in a haemophilic patient with inhibitors to Factor VIII. The treatment was performed after substitution therapy with Factor VIII-concentrate, supported by local and systemic antifibrinolytic treatment with tranexamic acid. No complications developed postoperatively, and after 9 months, the patient did not show recurrence of periodontal disease. Although the present case shows, that even severe periodontitis can be treated surgically in haemophilic patients with inhibitors to Factor VIII, this should not be done unless it is absolutely necessary. The treatment of periodontal disease in such patients should be instituted as early as possible in order to prevent the need for extensive surgery or dental extractions.

Antibodies↗
PubMed1987

The effect of prolonged stress-inducing electrical stimulation on cell proliferation in rat palatal epithelium.

This study examines whether blocking of cell division by stress-inducing electrical stimulation can be maintained for a prolonged period of time and whether this results in the accumulation of a large number of cells ready to divide when the block is released. A total of 96 rats was subjected to electrical stimulation at intervals of 30 min for periods of 2, 4, 6 or 12 hr. Groups of animals were killed every second hour during these stimulation periods. After 2, 4 and 6 hr groups of animals were exempted from further stimulation and killed 2 or 4 hr later. After termination of the 12 hr stimulation period, groups of animals were killed every second hour during the succeeding 24 hr. Forty-eight animals were left undisturbed and served as controls. Two and a half hours prior to death, each of the experimental and control animals was injected intraperitoneally (i.p.) with colchicine. Histological sections of the palatal mucosa were prepared and the numbers of arrested metaphases were counted. The electrical stimulation for 2, 4, 6 and 12 hr consistently resulted in a reduced number of cells entering mitosis, indicating a blockade at the G2/M transition. However, with an increase in the length of electrical stimulation, an increasing number of cells passed the block, while a decreasing number entered mitosis during the first 4 hr following cessation of the stimulation. The sum of metaphases accumulated during the various stress periods and the following 4 hr was always similar and consistently lower than the number of metaphases accumulated in the control animals within the same time periods. This observation indicates that, during stress-inducing electrical stimulation and the succeeding 4 hr, only a defined number of cells can enter the mitotic phase. Thus, in addition to the block at the G2/M transition, there appears to be another block of cell division at an earlier stage in the cell cycle.

Animals↗
PubMed1986

New attachment formation in the human periodontium by guided tissue regeneration. Case reports.

The aim of the present study was to evaluate whether a regenerative surgical procedure, based on guided tissue regeneration, could predictably result in the formation of a new attachment in human teeth. The material included 12 teeth in 10 patients with advanced periodontal disease. Following flap elevation, scaling, root planing and removal of granulation tissue, a teflon membrane was placed over the denuded root surface in such a way that the epithelium and the gingival connective tissue were prevented from reaching contact with the root during healing. The flap was replaced on the outer surface of the membrane and secured with interdental sutures. This design of wound preparation gives preference to the cells originating from the periodontal ligament (PDL-cells) to repopulate the wound area adjacent to the root. Histologic analysis of the result of treatment was made in 5 of the 12 teeth scheduled for extraction. In the remaining 7 teeth, the result was evaluated using clinical measurements. The result of healing disclosed that in all teeth treated, substantial amounts of new attachment had formed. This suggests that predictable restitution of the attachment apparatus can be accomplished by using a method of treatment which is based on the principle of guided tissue regeneration.

Adult↗
PubMed1986

Treatment of localized gingival recessions with coronally displaced flaps and citric acid. An experimental study in the dog.

The present study was designed to examine the effect of citric acid conditioning on the result of healing following treatment of localized gingival recessions with coronally displaced flaps. In 3 beagle dogs, localized gingival recessions were surgically created at the buccal surfaces of canines, premolars and molars. All experimental sites were allowed to accumulate plaque for a period of 6 months. Following preparation of notches in the buccal root surfaces at the level of the gingival margin, buccal and lingual mucoperiosteal flaps were raised. The exposed portion of the root surfaces was scaled and the cementum layer was removed. Another notch was prepared in the root surfaces at the level of the crest of the alveolar bone. Half the number of the roots were treated by topical application of citric acid while the remaining roots were used as non-acid treated controls. The flaps were sutured in a coronally displaced position. After 3 months of healing, the dogs were sacrificed and the jaws removed and placed in fixative. After decalcification, histological sections of the experimental roots and their periodontal tissues were produced. The 2 notches described above were used as reference points in the histological examination. The histological analysis disclosed that new attachment had formed on all test and control roots and extended in some specimens of both groups to a position coronal to the presurgical level of the gingival margin. The amount of new attachment was similar in the 2 categories of roots, demonstrating that citric acid conditioning did not produce additional new attachment.

Animals↗
PubMed1986

The significance of coronal growth of periodontal ligament tissue for new attachment formation.

The present study was designed to examine whether coronal growth of granulation tissue originating from the periodontal ligament is a prerequisite for new attachment formation. In each of 4 monkeys, 1 central incisor and 2 first molars in the maxilla and the mandible were selected for experimentation. Angular bony defects were surgically produced to the mid-root level around each single root after crown resection and root separation of the multirooted teeth. The periodontal ligament tissue and the root cementum were removed to the bottom of the bony defects. In half the number of the teeth, an elastic ligature was placed tightly around each root at the bottom of the defects (test roots). In the remaining teeth, an elastic ligature was placed loosely around each root at the same level (control roots). All roots were subsequently covered by laterally displaced flaps. After 3 months of healing, the animals were sacrificed and the jaws removed and placed in fixative. Following decalcification, histological sections of the experimental roots and their surrounding periodontal tissues were produced. The histological analysis disclosed that new attachment had former to a level coronal to the elastic ligature in 10 of 14 control roots but in only 1 of 18 test roots. The results indicate that the repopulation of a detached root surface by cells from the periodontal ligament is a prerequisite for new attachment formation.

Animals↗
PubMed1985

Cantilevered fixed partial dentures in a geriatric population: preliminary report.

This study has shown that treatment with distally extending cantilever fixed partial dentures is a favorable alternative to treatment with removable partial dentures in elderly patients with reduced dentition. In patients with anterior teeth and one or two premolar teeth remaining in the mandible, sufficient occlusal stabilization for a maxillary complete denture was provided by a two- or three-unit cantilever fixed partial denture. A pronounced improvement in chewing function and stability of the maxillary denture was expressed, even by patients who were previously well adapted to wearing removable partial dentures.

Aged↗
PubMed1985

Regeneration of alveolar bone following surgical and non-surgical periodontal treatment.

The purpose of this investigation was to examine the regeneration of alveolar bone following surgical and non-surgical periodontal treatment. A total of 16 patients who had advanced periodontitis and demonstrated angular bony defects on radiographs participated in the study. After the initial examination, they received instruction in oral hygiene and had their teeth thoroughly scaled. When the individual patient at 2 succeeding appointments had plaque on less than 20% of the tooth surfaces, one maxillary and one mandibular quadrant was treated with the modified Widman flap procedure while one of the remaining quadrants was treated with the reverse bevel flap procedure. The last quadrant was treated with root planing under local anesthesia. None of these procedures included bone contouring. Following treatment, the patients were recalled every 2 weeks for professional tooth cleaning. Radiographs taken 12 months following treatment revealed that only minor changes in the bone level had occurred in areas with horizontal bone loss following the various treatment modalities. Following the modified Widman flap procedure, however, a statistically significant coronal regrowth of bone (0.5 mm) had occurred in angular bony defects. The majority of the angular bony defects persisted following all 3 treatment modalities.

Alveolar Process↗