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Biomedical subjects

S Nyman

Publications and source records attributed to S Nyman.

At least 19 recordsLinked to original sources
PubMed1995

Augmentation of intramembraneous bone beyond the skeletal envelope using an occlusive titanium barrier. An experimental study in the rabbit.

The aim of this investigation was to evaluate whether augmentation of intramembraneous bone beyond the skeletal envelope can be predictably achieved by placing a completely occlusive barrier on the skull bone of rabbits, hereby creating a secluded space with bone tissue being the only adjoining tissue. The experiment was carried out in 3 New Zealand white rabbits. In each animal, a midline incision was made down to the bone surface of the skull and a skin-periosteal flap was raised to expose the skull bone on both sides of the midline. Two prefabricated titanium domes with an inner diameter of 4.5 mm and an inner height of 3.0 mm were installed on each side. The domes were supplied with a horizontal, peripheral flange and a vertical edge, fitting tightly into a circular slit, prepared by a trephine into the skull bone. This arrangement ensured a stable anchorage of the dome and a reliable peripheral sealing of the space. The skin-periosteal flaps were relocated to cover the domes and sutured. After a healing period of 3 months, the animals were killed and the experimental areas excised and prepared for histological transversal ground sections with each dome in situ. The results demonstrated complete bone fill of all domes, with no signs of ingrowth of other types of tissues, indicating that the use of a barrier with total occlusiveness, sufficient stiffness and stability and reliable peripheral sealing will result in predictable bone augmentation of spaces also beyond the skeletal envelope.

Animals↗
PubMed1995

The influence of the design of two different bioresorbable barriers on the results of guided tissue regeneration therapy. An intra-individual comparative study in the monkey.

The aim of the present study was to compare two bioresorbable barriers to evaluate whether differences in design influence the result of guided tissue regeneration (GTR) therapy. Twenty-four (24) plaque exposed, recession type defects in 4 monkeys were treated. Contralateral defects were randomized for test or control treatment. During a healing period of 6 weeks, gingival recession resulting in device exposure occurred at 3 test and 10 control sites. One control barrier was exfoliated. Histologically, 9 of the 12 test barriers were completely integrated with the surrounding tissues. At 3 test sites, epithelium had migrated apically outside the barrier to a level not exceeding one-third of the height of the device. Seven of the 11 control barriers were enclosed by dentogingival epithelium. The adjacent connective tissue exhibited local inflammatory cell infiltrates (ICT). At the remaining 4 control sites, the epithelial downgrowth as well as the adjacent ICT areas were limited to the coronal 1/3 of the device. New attachment; i.e., new cementum with inserting collagen fibers, averaged 2.2 mm and 0.8 mm at the test and control sites respectively (P < 0.01). Based on the results of the present study, it was concluded that a bioresorbable GTR device, designed to prevent epithelial downgrowth along the barrier surface, has a higher potential to promote new attachment formation than a device which does not have this property.

Animals↗
PubMed1995

Membrane-guided bone regeneration. Segmental radius defects studied in the rabbit.

We tested the principle of guided tissue regeneration (GTR) for healing segmental long-bone defects. 7 mm (3 animals) or 10 mm (5 animals) long segmental defects were created in the diaphyses of both radii in 8 rabbits. The defect on one side was covered with a barrier membrane of expanded polytetrafluoroethylene membrane shaped as a tube, while the contralateral side with no membrane served as the control. Healing was followed with radiographs obtained repeatedly during a 13- (n 3) or 27- (n 5) week period. Thereafter, the animals were killed and ground sections of the defect sites were prepared for histologic examination. Radiographically, the control sites showed some early subperiosteal callus formation and nonunion of the defects after 6 weeks. The bone ends were rounded off and sealed with cortical bone. No major changes were noted after 6 weeks. At the test sites, subperiosteal bone formation at the bone ends was first observed radiographically at 2 weeks. At 9 weeks, a thin cortical bone bridged the defect along the inner surface of the membrane. Histologically, an interrupted line of thin, cortical bone was observed along the inner surface of the barrier membrane. Fatty bone marrow occupied the central and largest volume of the defect. We conclude that it seems possible to use the principle of GTR to accomplish bone union of segmental long-bone defects.

Animals↗
PubMed1994

The use of a new bioresorbable barrier for guided bone regeneration in connection with implant installation. Case reports.

This report presents 4 cases with 6 implant exposures after the installation of Brånemark System implants which called for treatment applying the guided bone regeneration technique. A bioresorbable barrier (GUIDOR Matrix Barrier) was used to cover the defects, 4 defects with and 2 without the support of autologous bone chips. Complete bone filling was found in 4 (2 without and 2 with bone chips) and partial filling in 2 (with bone chips) of the treated defects, as registered at the abutment connection 6-7 months after surgery. Besides its ability to serve as a barrier for guided bone regeneration, it was found that the matrix barrier had the following properties; biocompatibility observed as uneventful tissue healing, malleability facilitating the clinical handling and ability to be resorbed within 6 to 7 months, as evaluated by clinical inspection. The observations of the present case reports indicate that the tested barrier may be used for guided bone regeneration in connection with implant installation. It is advisable, however, to use a supporting material to prevent barrier collapse, although bone regeneration can be achieved in certain situations without such material if the defect morphology is favourable.

Aged↗
PubMed1994

Periodontal tissue response to a new bioresorbable guided tissue regeneration device: a longitudinal study in monkeys.

This study evaluated periodontal tissue response to a new bioresorbable guided tissue regeneration barrier material following guided tissue regeneration treatment of dehiscence-type defects at 45 teeth in 15 monkeys. The results were clinically and histologically evaluated 6 weeks and 3,6, 12, and 24 months posttreatment. Healing was uneventful and without inflammation or other adverse tissue reactions. Following 6 weeks of healing, the matrix barrier was completely integrated with the surrounding tissues, preventing epithelial downgrowth along the device. There were no inflammatory cell infiltrates adjacent to the material. New attachment (ie, new cementum with inserting collagen fibers) and new supporting bone were found after 6 weeks of healing. The matrix barrier maintained its functional stability for a minimum of 6 weeks. The subsequent slow resorption process of the material occurred without detrimental effects on the surrounding tissues, demonstrating the biocompatibility of the material. The material was completely resorbed after 6 to 12 months. At the final stages of the resorption process, macrophages and multinuclear cells were present within the tissue that replaced the material. The design and the resorption pattern of the matrix barrier are discussed in relation to the regenerative wound healing process.

Animals↗
PubMed1992

Guided tissue regeneration in surgically-produced furcation defects. An experimental study in the beagle dog.

The aim of the investigation was to evaluate the potential for new attachment formation at various degree III furcation involvements in the beagle dog. 3 differently shaped furcation defects were prepared; one small and one large key-hole defect, and one furcation defect which was part of "circumferential" loss of attachment and bone. 15 beagle dogs were used in the experiments. The furcation defects were surgically created at mandibular premolars in the right and left side of the jaw. Test teeth were subsequently treated according to the GTR principle, while control teeth were treated without the application of membranes. The result from the histological examination of biopsy specimens revealed that GTR treatment may result in complete new attachment at surgically produced "through and through" furcation involvements in dogs. The study, however, also revealed that the size of the furcation defect as well as the shape of the surrounding alveolar bone were factors that determined the outcome of this kind of treatment. The treatment failures were consistently associated with flap recession during healing which resulted in the exposure of the furcation defect.

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

Bleeding on probing as it relates to probing pressure and gingival health in patients with a reduced but healthy periodontium. A clinical study.

A previous study demonstrated that the bleeding on probing (BOP) test using uncontrolled forces may result in a proportion of false positive readings when used as a parameter for inflammation. A strong possibility exists for the traumatization of clinically healthy gingival tissues if a probing force exceeding 0.25 N is applied. While these results originated form young dental hygienists exhibiting excellent oral hygiene, the aim of the present study was to evaluate the relationship between probing pressures and gingival conditions in patients with a history of treated periodontal disease, i.e., in situations with a reduced but healthy periodontium. 10 patients who had been enrolled in a periodontal maintenance program following treatment of moderate to advanced chronic inflammatory periodontal disease consented to participate in the study. They were all selected on the basis of a record of excellent oral hygiene practices for at least 2-6 years and almost complete absence of clinical inflammation following successful periodontal therapy. Applying a probing force of 0.125, 0.25, 0.375 and 0.5 N in the 4 jaw quadrants, respectively, at 2 different occasions with an interval of 10 days, bleeding on probing was assessed. Oral hygiene and gingival conditions were determined using the criteria of the plaque and gingival index systems. All subjects showed significant increases in mean BOP% with increasing probing force applied (2.5%-7.9%). Regression analysis revealed an almost linear correlation and a significant correlation coefficient between BOP% and probing force. Almost identical slope inclinations were found when the 6 subjects with the lowest mean BOP% at 0.25 N were compared with the regression analysis of the total group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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

Guided tissue regeneration in interproximal defects in the monkey.

The potential for guided tissue regeneration was evaluated in one-walled interproximal sites in Macaca fascicularis. Histologic differences were evaluated at 1 and 3 months. Within the experimental (barrier) group, 100% of the root surfaces with potential for regeneration were covered with new cementum, whereas the control specimens had 20% or less new cementum. The amount of regeneration was determined by the position of the barrier membrane; the more coronal the barrier, the greater the regeneration. Observations indicated that the optimal time for barrier removal is between 1 and 3 months.

Animals↗
PubMed1991

Bleeding on probing as it relates to probing pressure and gingival health.

The present study was designed to determine the threshold pressure value to be applied in provoking bleeding on probing (BOP) in clinically healthy gingival units. 12 female dental hygiene students volunteered for the study. They were selected on the basis of excellent oral hygiene standards, absence of probing depths greater than 3 mm and absence of caries or dental restorations on smooth and proximal tooth surfaces. Applying a probing force of 0.25, 0.5, 0.75 and 1.0 N in one of the 4 jaw quadrants, respectively, on 2 different occasions with an interval of 10 days, bleeding on probing was assessed. Oral hygiene and gingival conditions were determined using the criteria of the plaque control record and the gingival index. On the basis of the BOP values, obtained using the lowest probing force (0.25 N), the subjects were divided into 2 groups: group 1 ("minimal BOP" value) consisted of 6 subjects yielding practically no bleeding (mean BOP = 0.9%) at both examinations, while the subjects of group 2 ("low BOP" value) had slightly higher BOP% (mean BOP = 13.4%). Both groups showed significant increase in mean BOP% with increasing probing force (0.9%-36.1% in group 1 and 13.4%-47.0% in group 2). Regression analysis revealed an almost linear correlation and a high correlation coefficient between BOP% and probing force. The comparison of the regression lines of the 2 groups showed almost identical slope inclination. However, slight differences in slope inclination were found for different sites: approximal sites clearly yielded steeper regression lines than buccal/oral sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Bone regeneration using the principle of guided tissue regeneration.

The biological principle of "guided tissue regeneration" (GTR) was developed for regenerating periodontal tissues, lost as a result of periodontal disease. This principle was based on the hypothesis that non-desirable types of tissue cells can be prevented from migrating into a wound by means of a membrane barrier and at the same time giving preference to those particular cells to repopulate the wound, which have the capacity to regenerate the desired type of tissue. This principle may have its application in many areas of surgery, aimed at regeneration of lost tissues. One such area is osseous surgery aimed at bone regeneration. In the present paper, a series of experiments in laboratory animals using the method of GTR for regeneration of various types of bone defects are presented as well as examples of application in humans for regeneration of jaw bone defects in conjunction with the placement of dental implants.

Alveolar Process↗
PubMed1990

Regeneration and enlargement of jaw bone using guided tissue regeneration.

The purpose of this study was to present the surgical procedures and the clinical results of guided tissue regeneration (GTR) treatment aimed at regenerating local jaw bone in situations where the anatomy of the ridge did not allow the placement of dental implants. 12 patients were selected for ridge enlargement or bony defect regeneration. A combined split- and full-thickness flap was raised in areas designated for subsequent implant placement. Following perforation of the cortical bone to create a bleeding bone surface, a PTFE membrane was adjusted to the surgical site in such a way that a secluded space was created between the membrane and the subjacent bone surface in order to increase the width of the ridge or to regenerate bony defects present. Complete tension-free closure of the soft tissue flap was emphasized. Following a healing period of 6 to 10 months, reopening procedures were performed and the gain of bone dimension was assessed. In 9 patients with 12 potential implant sites, a sufficient bone volume was obtained to allow subsequent implant placement. The gain of new bone formation varied between 1.5 and 5.5 mm. In 3 patients, acute infections developed which necessitated early removal of the membranes and no bone regeneration could be achieved. The results of the study indicate that the biological principle of GTR is highly predictable for ridge enlargement or defect regeneration under the prerequisite of a complication-free healing.

Adolescent↗
PubMed1990

The significance of alveolar bone in periodontal disease. A long-term observation in patients with cleft lip, alveolus and palate.

The periodontal conditions in 19 patients with unilateral cleft lip, alveolus and palate (CLAP) and in 6 patients with bilateral CLAP, were evaluated in 1979 and re-examined in 1987. During these 8 years, these patients were not subjected to any professionally supervised maintenance care program. Pronounced plaque accumulation and high frequency of gingival units exhibiting bleeding on probing were noted in the majority of the patients both in 1979 and 1987, documenting inadequate oral hygiene standards with resulting inflammatory reactions of the periodontal tissues. Progression of periodontal disease over time was assessed as loss of clinical attachment and loss of alveolar bone height. The periodontal destruction was not found to be more severe at cleft sites with a long connective tissue attachment than at control sites not affected by cleft defects. It was concluded that sites with a long supracrestal connective tissue attachment do not seem to be more prone to periodontal destruction, induced by bacterial infection, than sites with a normal length of the supraalveolar fibrous attachment. The results also show that the alveolar bone height, as visualized in radiographs at sites with alveolar defects, is of limited value for the diagnosis of the degree of periodontal destruction at such sites.

Adolescent↗
PubMed1990

Absence of bleeding on probing. An indicator of periodontal stability.

Following active periodontal therapy, 41 patients were incorporated in a maintenance program for 2 1/2 years with recall intervals varying between 2-6 months. At the beginning of each maintenance visit, the periodontal tissues were evaluated using "bleeding on probing" (BOP). Reinstrumentation was only performed at sites which bled on probing. However, supragingival plaque and calculus was always removed. Pocket probing depths and probing attachment levels were recorded after active treatment and at the conclusion of the study. Progression of periodontal disease was defined by an observed loss of probing attachment of greater than or equal to 2 mm. The reliability of the BOP test as a predictor was evaluated by calculating sensitivity, specificity, accuracy, and positive and negative predictive values. While only a 29% sensitivity was calculated for frequent bleeding, the specificity was 88%. The fact that the positive predictive value for disease progression was only 6% and the negative predictive value was 98% renders continuous absence of BOP a reliable predictor for the maintenance of periodontal health.

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

Localized ridge augmentation in dogs: a pilot study using membranes and hydroxyapatite.

This study was designed to evaluate the potential to reconstruct localized ridge defects with bone by preventing non-osteogenic extraskelatal connective tissue from participating in the process of healing following experimental ridge augmentation treatment procedures. Following the elevation of buccal muco-periosteal flaps, buccal, interproximal, and interradicular bone was removed to the apical level of the second and third premolar teeth and the teeth were extracted to create bucco-lingual ridge defects that averaged 13 mm x 7 mm x 3.5 mm in each quadrant of two adult beagle dogs. The defects were permitted to heal for 90 days. The defects did not fill in with new bone. Subsequently, buccal muco-periosteal flaps were elevated and a membrane was placed over the defect and positioned so that it rested on bone that was exposed adjacent to the defect. In two quadrants test support materials were used to ensure that a space was maintained between the surface of the defect and the membrane. One quadrant was maintained as a sham-operated control site, three sites received membranes and no supporting implants and two sites received supporting implants and no membranes. The surgical schedule was designed to yield sacrifice times of 8 to 12 weeks. In the three quadrants available for study that were covered with membranes, bone and/or non-mineralized connective tissue was found to fill all of the space that had been provided by the membrane. Histologic examination confirmed that the space was filled with young, actively growing bone by 90 days. No new bone formation (bone fill) was observed in the sham-operated control site.

Alveolar Process↗