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Biomedical subjects

S Nyman

Publications and source records attributed to S Nyman.

At least 37 records · Page 2Linked 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

Clinical and microbiological changes associated with an altered subgingival environment induced by periodontal pocket reduction.

The purpose of the present investigation was to study the effect of an altered subgingival environment, induced by changing the local soft tissue morphology, i.e., pocket depth reduction, on the subgingival microbiota and the clinical conditions. 7 patients aged 30-60 years with generalized marginal periodontitis were selected. Patients were instructed in proper oral hygiene and all teeth were cleaned supragingivally. Mucoperiosteal flaps were raised and the bone re-contoured to eliminate angular bony defects. While the control teeth were carefully debrided and thoroughly root planed, no root instrumentation was performed on the test teeth. Calculus deposits visible to the naked eye were only chipped-off with the tip of a scaler. The flaps were apically repositioned and sutured at the level of the bone crest. Clinical parameters showed a similar pattern of response in the test and control sites over a one year observation period post therapy. Probing depths and probing attachment levels were significantly reduced one month after surgery and remained at a lower level. A significant decrease was also noted for total anaerobic viable bacterial counts. The proportion of the Gram-negative anaerobic rods decreased significantly in both groups. P. gingivalis, Fusobacterium sp., C rectus were detected significantly less often after treatment in both groups. Capnocytophaga and A. odontolyticus, on the other hand, were more frequently isolated after therapy. These findings corroborate the concept that the reduction of selected subgingival microorganisms is the key element for the success of periodontal therapy, rather than the removal of tooth substance and mineralized deposits by root instrumentation.

Actinomyces↗
PubMed1995

The effect of ambient temperature and saline loading on changes in plasma and urine electrolytes (Na+ and K+) following exercise.

In this study 4 Standardbred geldings (age 3-8 years, weight 431-531 kg) were used. The horses were fed a hay and oat diet and the total sodium intake was about 32 mg/kg bwt (690 mmol/day). An exercise test (ET) which contained 3 phases was performed. Phase I consisted of 23.5 min of mainly submaximal exercise, Phase 2 of 2 h of box rest and Phase 3 of 26 min of exercise including an intensive trot over 2600 m at 90% of VO2max. The ET was repeated 3 times: the first at 20 degrees C (30-40% RH), the second at 35 degrees C (30-40% RH) and the third at 35 degrees C (30-40% RH) after a nasogastric administration of 10 litres of 0.9% NaCl solution (35 degrees C and saline load [+ F]). Blood samples were taken before, during and after exercise. To measure fluid loss, horses were weighted before and after the ETs. Total urine output was determined 2 days before the ET (control), throughout the exercise day and for 2 days after (recovery days). There were an increase in blood and rectal temperatures after both exercise phases and a significant higher blood temperature was observed after exercise at 35 degrees C compared to 20 degrees C. The horses lost about 2% of their bodyweight (bwt) during the ETs. The plasma protein concentration increased during the exercise phases and remained elevated 2 h after exercise at both 20 degrees C and 35 degrees C, even though the horses had free access to water. The plasma protein concentration had returned to pre-exercise levels 26 h post exercise. After the saline load, total plasma protein concentration fell and increased only at the end of each exercise phase. The major mechanism regulating fluid balance after exercise seemed to be a lowered urinary excretion since water intake did not increase significantly. Urinary potassium excretion was positive throughout the experiment. During control days there was a positive sodium balance, shown by a urinary sodium excretion of 260 mmol/day. Post exercise urinary sodium excretion fell and remained very low until the second day of recovery, except after saline loading. In addition, plasma sodium was lowered 26 h after exercise at 35 degrees C. This study shows that with a daily salt intake of 38 g it will take several days to compensate for a sodium loss caused by sweating. Therefore, it is recommended that extra salt be given during the exercise day. In the experimental situation, pre-exercise saline supplementation was beneficial since the recovery time was shortened.

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↗
PubMed1993

Periodontal tissue response to orthodontic movement of teeth with infrabony pockets.

The aim of this study was to evaluate the effect of orthodontic tooth movement on the level of the connective tissue attachment in sites with infrabony pockets. The experiment was carried out in four beagle dogs. The second and fourth premolars were extracted. After healing, angular bony defects were prepared at the mesial aspect of the third premolars. The exposed root surface was scaled and planed, and a notch was prepared at the bottom of the defect. Plaque-collecting cotton floss ligatures were placed around the neck of the teeth and maintained in situ for 3 weeks, followed by an additional 2 months of plaque accumulation before the orthodontic tooth movement was initiated. In each dog, one premolar was moved away from the angular bony defect and one premolar into and through the angular bony defect. The maxillary third premolars served as control teeth and were not subjected to orthodontic tooth movement. After orthodontic treatment (5 to 6 months), the teeth were stabilized for a period of 2 months before biopsy sampling. Clinical, radiographic, and histologic evaluations revealed that it was possible to establish and maintain an infrabony pocket with a subcrestal, plaque-induced inflammatory lesion during the entire course of the study. While the control teeth had maintained their attachment levels, all but one of the orthodontically moved teeth showed additional loss of attachment.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗
PubMed1993

Orthodontic tooth movement into edentulous areas with reduced bone height. An experimental study in the dog.

The present study was performed in order to test the hypothesis that the height of supporting bone and connective tissue attachment will be maintained around teeth bodily moved into areas of reduced bone height. During a pre-experimental period, areas with markedly reduced bone height were produced in the mandible of 4 beagle dogs through extraction of the 4th premolars and subsequent surgical reduction of the bone height in the extracted sites to a level corresponding to half the root length of the 3rd premolar. Following healing, one of the third premolars was bodily moved in a distal direction into the area of reduced bone height, while the contralateral premolar served as a non-moved control. After 6 months of active tooth movement, the teeth were retained in their new position for a further 2 months before biopsies of test and control tooth sites were sampled. Radiographic evaluation showed that a bodily movement had been achieved with no or only minimal vertical displacement of the teeth. The histological analysis revealed that none of the teeth, orthodontically moved or not, had experienced loss of connective tissue attachment. Although a greater distance between the cemento-enamel junction and the bone crest was found on the pressure side of the orthodontically moved test teeth in comparison to the contralateral, non-moved control teeth, the bone level at all test teeth was more coronally positioned than the original, reduced bone level in the area into which the test teeth had been moved. Hence, these findings indicate that a tooth with a normal height of periodontal support can be orthodontically moved into an area of markedly reduced bone height with maintained height of the supporting apparatus.

Alveolar Bone Loss↗
PubMed1993

Isolation of periodontal species after guided tissue regeneration.

One advanced localized periodontal lesion in each of 10 patients was treated using the guided tissue regeneration procedure. Six weeks after placement of expanded polytetrafluoroethylene (ePTFE) membranes, microbial samples were taken from each treated site and the membranes were removed. Six weeks later the cases were re-evaluated. They had all healed successfully with varying amounts of gain of clinical attachment. Gram-negative, anaerobic rods were found in all samples and made up 31% of all organisms cultivated. In 1 patient, Porphyromonas gingivalis was found in a proportion of 17.5%. Six of the other 9 patients harbored Prevotella intermedia (mean proportion 21.3%) and 6 Prevotella melaninogenica (6.8%). Fusobacterium and Capnocytophaga were also frequently found. The results demonstrate that ePTFE membranes are frequently colonized by periodontal microorganisms. The importance of bacterial colonization on clinical success is presently not known. Further studies are needed to determine the effect of the presence or absence of putative pathogens during guided tissue regeneration.

Actinomyces↗
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↗