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Biomedical subjects

T Karring

Publications and source records attributed to T Karring.

At least 55 records · Page 3Linked to original sources
PubMed1993

Periodontal ligament formation around different types of dental titanium implants. I. The self-tapping screw type implant system.

The aim of this study was to determine if a periodontal ligament can form around self-tapping, screw type titanium dental implants. Implants were inserted in contact with the periodontal ligament of root tips retained in the mandibular jaws of 7 monkeys. In each side of the mandible, 1 premolar and 2 molars were removed in such a manner that in approximately half the cases, the root tips were retained. Following healing, the experimental areas were examined on radiographs, and sites were selected for the insertion of the implants, so that every second implant would have a close contact to the retained root tips. Three months after placement of the implants, the animals were sacrificed, and ground sections were produced for histological analysis. The results demonstrated that newly-formed cementum had become deposited on the implant surface in the contact area between the implant and the retained roots, whereas osseointegration was consistently found on the remaining part of the implant surface as well as on the entire surface of the implants placed without contact to the retained root tips. The study has shown that, when placed in contact with periodontal ligament tissue of retained roots, a periodontal ligament can form on self-tapping, screw type titanium dental implants in areas where a void is present between the surrounding bone and the implant at the time of insertion.

Animals↗
PubMed1992

Digital subtraction radiography in assessing bone changes in periodontal defects following guided tissue regeneration.

19 patients with a total of 23 periodontal lesions were selected for the study. Following flap-elevation, an occlusive membrane (Gore Tex) adjusted to the size and shape of the lesion was applied. The membrane was removed 4-6 weeks later by a 2nd operation. Clinical attachment levels were measured and intraoral radiographs taken prior to surgery, and 6 and 12 months postoperatively. The root length and marginal bone level were measured on paper drawings of the teeth magnified (15x) from the conventional radiographs. The radiographs were digitized for analysis of the subtraction images between the preoperative and the 6- and 12-month postoperative images. Clinical attachment gain was seen in 78% of the teeth after 6 months and 70% after 12 months. Bone gain was recorded in 56% and 22% after 6 months and in 44% and 66% after 12 months by conventional and digital subtraction radiography, respectively. The bone level measurements on conventional radiographs differed significantly (p = 0.001) between the preoperative and 6-month postoperative, but not between the 6- and 12-month, (p = 0.29) conventional radiographs. There was no significant relationship between the clinical measurements and the assessments of bone changes on conventional radiographs (r = 0.28, p = 0.25), while a stronger relationship was observed between assessment of clinical attachment gain and assessment of bone changes on the subtraction images (r = 0.58, p = 0.01).

Alveolar Bone Loss↗
PubMed1992

Maintenance of new attachment gained through guided tissue regeneration.

The aim of the present study was to evaluate whether new attachment, gained following guided tissue regeneration (GTR) therapy, can be maintained over longer periods of maintenance therapy. 88 sites at 52 teeth with various types of periodontal defects in 39 patients were treated with the GTR procedure during the period 1984-1989. The effect of treatment was evaluated by assessing probing attachment level (PAL) prior to surgery and 6 months post-surgery. Only sites which at the 6-month examination (baseline) had gained 2 mm or more of PAL were regarded as successfully treated and scheduled for further monitoring. At baseline, 80 sites could be identified which fulfilled this criterium. Of the 80 new attachment sites, all have been monitored for 1 year, 65 for 2 years, 40 for 3 years, 17 for 4 years and 9 sites for 5 years. The results demonstrated that the attachment gain, obtained as the result of the GTR treatment, could be maintained over periods up to 5 years.

Epithelial Attachment↗
PubMed1992

Guided tissue regeneration combined with osseous grafting in suprabony periodontal lesions. An experimental study in the dog.

The purpose of the present investigation was to evaluate the use of bone grafts in combination with the GTR-procedure in reinstituting periodontal support around teeth with horizontal bone loss. Orthodontic elastic bands were placed around mandibular and maxillary premolars in 3 dogs in order to induce breakdown of the periodontal tissues. When the destruction had reached a level corresponding to approximately half the root length, the elastic bands were removed and the teeth were scaled. After a period with plaque control, mucoperiosteal flaps were elevated on the buccal and lingual aspects of the experimental teeth. The exposed root surfaces were curetted, and a notch was made at the level of the reduced bone crest. In randomly selected test quadrants, Kielbone mixed with fibrin sealant (Tisseel) was placed in the interproximal space and in the bifurcations. Both the buccal and lingual aspect of the test teeth were then covered by a teflon membrane (Zitex) and the raised tissue flaps sutured in a coronally displaced position. The contralateral teeth (controls) were treated the same way, except that fibrin sealant without Kielbone was applied in the bifurcations and the interproximal space prior to the placement of the membranes. The membranes were removed by a 2nd operation after 35 days. Clinically, various complications were observed during healing. The buccal and lingual flap margins consistently failed to join in the interproximal area, and increasing recession of the flap margins and exposure of the membranes, resulting in accumulation of bacterial deposits and food debris, occurred during the period the membranes were maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1992

Effect of Tisseel on healing after periodontal flap surgery.

The purpose of this investigation was to evaluate the effect on healing of fast and slow absorbable Tisseel in combination with periodontal flap surgery. Mucoperiosteal flaps were raised on the buccal aspect of maxillary premolars and mandibular premolars and first molars in 4 beagle dogs. The underlying buccal, interproximal and inter-radicular bone was then removed to a level of approximately 5 mm apically to the original bone crest and half way into the interdental spaces and bifurcations. The exposed root surfaces were curetted in order to remove the periodontal ligament tissue, and a notch was made in the root surface at the base of the defects. On the control teeth, the flaps were sutured immediately after creation of the defects, while on the test teeth, a layer of fast (group I) or slow (group II) absorbable Tisseel was applied between the curetted roots and the subsurface of the flaps prior to suturing. Postoperatively, the teeth were brushed 2 x weekly. The dogs were sacrificed after 4 months. Histological analysis revealed that the amounts of new attachment and bone regrowth were similar in the test and control groups, although the results tended to be most favorable for the group of teeth treated with fast absorbable Tisseel (Group I).

Absorption↗
PubMed1992

Guided tissue regeneration using biodegradable membranes of polylactic acid or polyurethane.

The purpose of the present investigation was to evaluate the use of biodegradable membranes of polylactic acid or polyurethane for obtaining regeneration following treatment of circumferential periodontal defects in monkeys with the "guided tissue regeneration" procedure. Orthodontic elastic bands were placed around selected test and control teeth in 4 monkeys in order to induce breakdown of the periodontal tissues. When the destruction of the supporting tissues had progressed to a level corresponding to approximately half the length of the roots, the elastic bands were removed. After 1 to 8 months, full thickness flaps were raised on the buccal and lingual aspects of both test and control teeth. The exposed root surfaces were scaled and a notch was prepared in the root surface at the level of the reduced bone crest. Membranes of polylactic acid or polyurethane were placed circumferentially around the test teeth, while no membranes were placed around the control teeth. The tissue flaps were then sutured in a coronally displaced position. The surgical procedures and sacrifice of the animals were scheduled to provide observation times of 1, 4 and 8 months. During the healing period, various complications such as recession of the flap margins and exposure or exfoliation of the membranes were noticed. The histological analysis showed that the amount of new connective tissue attachment on test and control teeth did not differ and was restricted to the most apical part of the lesions. The bio-degradable membranes could be identified in a few specimens, and they were always surrounded by an epithelial layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

3 regimens of topical metronidazole compared with subgingival scaling on periodontal pathology in adults.

This report presents the findings from an open randomized multicentre clinical trial designed to compare the clinical efficacy of scaling with application of 3 different preparations/dose frequencies of topical metronidazole in the treatment of adult periodontitis. The 4 treatments were: (A) metronidazole 25% dental gel administered 1 x a week for 2 weeks; (B) metronidazole 15% dental gel applied 1 x a week for 2 weeks; (C) metronidazole 15% dental gel applied 2 x a week for 2 weeks; (D) subgingival scaling, performed 1 x only. A split mouth design was used. Patients were included in the study if they had at least 1 tooth in each quadrant with a pocket depth > or = 5 mm in at least 1 of 4 sites. A total of 61 patients from 4 centres were entered into the study. The efficacy parameters were probing pocket depth and bleeding on probing. Follow-up visits for recording of clinical efficacy were made at 2, 4, 6 and 12 weeks after the end of metronidazole treatment. All 3 antibiotic treatments (A, B, C) reduced the symptoms of periodontal pathology and yielded results comparable to those seen after subgingival scaling (D). When using a topical drug therapy, it seems important to use a preparation that requires as few applications as possible. The best candidate for drug therapy would therefore be treatment (A) metronidazole 25% applied 1 x a week for 2 weeks.

Adult↗
PubMed1992

Comparative clinical and microbiological effects of topical subgingival application of metronidazole 25% dental gel and scaling in the treatment of adult periodontitis.

The aim of the study was to compare the clinical and microbiological effects of topical application of a metronidazole gel and a single session of subgingival scaling in the treatment of adult periodontitis. An open, randomized controlled clinical study design was employed. Each of 24 subjects received the 2 treatments simultaneously each in 2 randomly selected quadrants of the dentition. The metronidazole, 25% gel was applied subgingivally on days 0 and 7. Scaling was carried out in one quadrant on day 0 and in one quadrant on day 7. Clinical and microbiological examinations were carried out before treatment and on days 21, 49, 91, 133, and 175 of the experimental period. The microbiological analyses included determination of total anaerobically cultivable bacteria, and relative proportions of anaerobes, aerobes, black-pigmented anaerobic Gram negative rods, Actinobacillus actinomycetemcomitans, streptococci, and spirochetes. Both treatments were effective in reducing probing pocket depth and bleeding on probing. Metronidazole tended to be a little better than scaling during the study period and the clinical effects of both treatments persisted during the whole 6 months observation period. Local metronidazole treatment induced a significant and long-lasting shift in the subgingival flora towards a composition more compatible with health and comparable to that obtained by mechanical debridement. Proportions of black pigmented anaerobes including Prevotella intermedia, and the number of spirochetes were significantly reduced after both treatments with a concomitant increase in the proportions of streptococci. While scaling resulted in a statistically significant increase in the proportion of A. actinomycetemcomitans, this was avoided after metronidazole treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Clinical responses to subgingival application of a metronidazole 25% gel compared to the effect of subgingival scaling in adult periodontitis.

A newly developed metronidazole 25% dental gel was compared with subgingival scaling in the treatment of adult periodontitis. 206 patients in 9 centres participated in the study. Probing pocket depth (PPD) and bleeding on probing (BOP) were recorded before treatment and 2, 6, 12, 18, and 24 weeks after the treatment. All patients had at least 1 tooth in each quadrant with a PPD of 5 mm or more. The treatments consisted of 2 applications of dental gel (days 0 and 7) in 2 randomly selected quadrants (split mouth design) and 2 sessions of subgingival scaling (1 quadrant on day 0, and 1 quadrant on day 7). Instruction in oral hygiene was given 2 weeks after completed treatment. The average PPD and the average frequency of BOP were calculated over all sites with initial PPD of 5 mm or more. PPD and BOP were thus, at each examination, calculated from the same sites. The mean PPD was 5.9 mm before gel application and 5.8 mm before scaling (p = 0.31). BOP was 88% in both treatment groups. 24 weeks after the treatment, PPD and BOP were significantly reduced in both groups and for both parameters (p < 0.01). PPD was reduced by 1.3 mm after gel application and 1.5 mm after scaling; BOP was reduced by 32% and 39%, respectively. The difference between the treatments was statistically significantly, but considered as clinically unimportant.

Adult↗
PubMed1992

Biodegradable guide for bone regeneration. Polyurethane membranes tested in rabbit radius defects.

Segmental, 1-cm osteoperiosteal defects were produced in both radii of 10 rabbits. One defect was covered with a biodegradable polyurethane membrane formed as a tube. The contralateral defect served as an untreated control. Healing was analyzed by radiographic and histologic studies after 5 weeks. Nine out of 10 control defects displayed nonunion, whereas membrane-treated defects consistently healed by forming callus external to the membrane fusing the bone fragments. Loose connective tissue was predominant in the bone gap underneath the membrane. Presumably, the membrane has served as a scaffold for regenerating periosteum.

Animals↗
PubMed1992

Development of the principle of guided tissue regeneration.

Guided tissue regeneration (GTR) is a new treatment principle in surgical therapy, developed from the result of studies in experimental animals. It implies that only those types of cells with the capacity of producing regeneration are allowed to invade the surgically treated lesion during healing. This is accomplished by the placement of a physical barrier with excludes undesirable types of tissue. Healing of periodontal bony lesions can be obtained predictably by treatment according to the principle of guided tissue regeneration but several studies have suggested that the same principle can also be applied successfully in other fields of dentistry. In implantology, the method has been used for immediate placement of implants into extraction sockets, for healing of peri-implant bony defects and for augmentation of atrophic alveolar ridges.

Alveolar Bone Loss↗
PubMed1991

Effect of surgical and non-surgical periodontal treatment on periodontal status and subgingival microbiota.

The purpose of this study was to evaluate, on a short-term basis, the clinical and microbiological effects of a single course of scaling and root planing as compared with those obtained by flap surgery in patients with moderate to advanced periodontitis. 11 patients participated in the study. Using a split-mouth design, one quadrant of the mouth was treated with reverse bevel flap surgery, whereas the contralateral one was subjected to a single course of scaling and root planing. 2 approximal sites on single-rooted teeth with a pocket depth greater than or equal to 5 mm were monitored clinically and microbiologically for 16 weeks after active treatment. Both techniques resulted in a gain of probable attachment levels, a reduction in bleeding on probing and a reduced mean pocket depth, although 31.2% of the sites in the scaling and root planing group still had 6-7 mm deep pockets at 8 and 16 weeks after treatment. Both techniques reduced median relative proportions and frequencies of detection of black-pigmented Bacteroides species. A highly statistically significant increase (p less than 0.01) in median proportions of oral streptococci was recorded only for surgery within the 1st month post-operatively. No correlation was found between residual pocket depth and any of the microbiological parameters considered in the study, suggesting that residual pocket depth does not exert a significant influence on bacterial subgingival recolonization after therapy. The results from this study suggest that surgery can be as effective as scaling and root planing in favoring the establishment of micro-organisms compatible with periodontal health, although this effect is limited to the 1st month after therapy.

Adult↗
PubMed1990

Guided tissue regeneration following treatment of recession-type defects in the monkey.

Recent studies have demonstrated extensive amounts of new attachment formation following reconstructive surgery based on the biological principle of guided tissue regeneration (GTR). The aim of the present investigation was to evaluate the effect of using a polytetrafluorethylene (PTFE) membrane in GTR-treatment of recession-type defects and to examine the interrelationship between the PTFE membrane and surrounding periodontal tissues. Full-thickness flaps were raised around 24 maxillary premolar and molar teeth in 6 monkeys. The buccal alveolar bone was surgically removed to a level corresponding to the apical third of the roots. The exposed root surfaces were scaled and planed. In 12 teeth, PTFE membranes were adjusted to cover the exposed root surfaces from a level 1 to 2 mm apical to the CEJ, to a level 3 to 4 mm apical to the alveolar crest. The coronal border of the membranes was tightly adapted to the root surfaces by sling sutures. Twelve teeth served as control teeth without placement of membranes. The flaps were placed with the margin coronal to the CEJ and sutured. The animals were sacrificed after 3 months of healing and all experimental teeth were subjected to histological analysis. The membranes were found to be incorporated with the surrounding connective tissue, and the apical extension of the junctional epithelium terminated at the coronal border of the membranes. The amount of new attachment formation was on the average 74.3% of the defect height in the test teeth, which corresponded to 100% of the membrane covered root portion. Newly formed connective tissue attachment in the controls amounted to an average of 36.9% of the defect height.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1990

Formation of a periodontal ligament around titanium implants.

The aim of this study was to examine wound healing events around titanium implants in the presence of retained root tips whose periodontium could serve as a source for cells which could participate in the healing process. Hollow cylinder implants with a titanium plasma-sprayed surface were placed in the mandible of monkeys where the apical portions of previously removed teeth were retained. After a healing period of 12 months, free of functional loading, the implants with surrounding tissues were removed and specimens analyzed in undecalcified sections. This report describes histologic findings of six such implants. Microscopic analysis revealed that in regions where implants were close to retained roots, a periodontal ligament had formed around large portions of the implant. Furthermore, there was a distinct layer of cementum on the implant surface and a periodontal ligament with collagen fibers perpendicularly oriented to the implant surface, implanted into the cementum on the implant surface as well as to the opposing bone. This initial observation suggests that it may be possible to achieve an anchorage of certain dental implants with a periodontium simulating that found surrounding the normal tooth. Furthermore, these findings provide the basis for further studies on regeneration of all components of the periodontal attachment apparatus including cementum, periodontal ligament, and bone.

Animals↗
PubMed1990

Titanium implants with a true periodontal ligament: an alternative to osseointegrated implants?

The purpose of the present study was to experimentally determine if cementum formation with inserting collagen fibers can be accomplished on dental implants. Titanium implants were placed in the mandible of monkeys, where apical root portions were retained. The histologic examination of undecalcified sections revealed that a cementum layer on the implant surface with inserting collagen fibers was achieved around implants placed in close relationship to retained roots; however, implants without contact to retained roots demonstrated the typical findings of osseointegration. These results demonstrate that dental implants with a true periodontal ligament can be accomplished.

Animals↗
PubMed1989

Guided tissue regeneration in the treatment of furcation defects in mandibular molars. A clinical study of degree III involvements.

The present investigation was designed to evaluate the regenerative potential of the periodontal tissues in degree III furcation defects at mandibular molars using a treatment procedure based on the principle of guided tissue regeneration. The patient sample included 21 patients, 26-65 years of age, who presented periodontal lesions in the right and left molar regions including "through and through" furcation defects. After an initial examination, each patient was subjected to a series of full-mouth scaling and root planing. 2-3 months later, they were recalled for a baseline examination. 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 muco-periosteal flaps at the buccal and lingual aspects of the molars. Granulation tissue was removed and the exposed root surfaces were debrided and planed. The width and the height of the entrance openings to the furcation defects were assessed. A teflon membrane was adjusted to cover the entrances to the defects (buccal and lingual) and was retained in the manner described by Pontoriero et al. (1988). The flaps were repositioned on the outer surface of the membrane and secured by sutures which were removed after 10 days. Following surgery, the patients were instructed to rinse the mouth twice daily for 4 weeks with chlorhexidine gluconate. The membranes were removed after a healing period of 1-2 months. A surgical procedure identical to the test procedure was performed in the control tooth regions with the exception of the placement of membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗