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Biomedical subjects

S Nyman

Publications and source records attributed to S Nyman.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1990

Healing of maxillary and mandibular bone defects using a membrane technique. An experimental study in monkeys.

Cyst-like cavities in the jaw bone often heal incompletely owing to ingrowth of connective tissue, thus preventing osteogenesis from occurring. In the present study, a new membrane technique has been utilized in an attempt to improve bone healing. By means of an inert, porous membrane, placed in close contact with the bone surface, a secluded space is created which can only be repopulated by cells from the adjacent bone. Thus, osteogenesis is able to occur without interference from other tissue types. Through-and-through bone defects were produced bilaterally (1) in edentulous areas of monkey (n = 5) mandibles, and (2) in conjunction with apicectomy of the lateral maxillary incisors, also in monkeys (n = 7). On one side, the defects were covered buccally as well as lingually/palatally with expanded PTFE membranes, whereas the defects on the other side served as controls (no membrane). In the mandible, complete bone healing was seen at all test sites after a healing period of 3 months. On the control side, 3 experimental sites showed bone discontinuity with a transosseous core of connective tissue, whereas some bone healing had occurred lingually at 2 sites, but with massive soft tissue ingrowth from the buccal side. In the maxillary periapical defects, all the membrane-covered defects had healed with bone closure after 3 months but with a minute portion of connective tissue, probably derived from the periodontal ligament, around the tooth apices. None of the control defects (no membrane) healed spontaneously, but all were filled with connective tissue to varying degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Clinical and microbiologic findings that may contribute to dental implant failure.

Clinical and DNA probe analysis were used to evaluate 36 failing implant sites in 13 patients. Failing implants showed evidence of increased mobility and a high incidence of peri-implant radiolucencies in radiographs. The probing depth was greater than 6 mm in 58% of the sites measured. Moderate levels of Actinobacillus actinomycetemcomitans, Bacteroides intermedius, and Bacteroides gingivalis were detected with DNA probe analysis.

Actinobacillus↗
PubMed1990

Bone regeneration adjacent to titanium dental implants using guided tissue regeneration: a report of two cases.

The biologic principle of guided tissue regeneration was applied to regenerate alveolar bone in conjunction with the placement of titanium dental implants. In one case, complete osseointegration of an implant was achieved by the placement of a Teflon membrane over an implant that had been inserted into an alveolus immediately following tooth extraction. In a second case, the same biologic principle was used to increase the volume (height and width) of a resorbed, edentulous alveolar ridge to provide adequate bone dimensions for implant installation. In both cases, the membranes appear to have prevented the repopulation of the wound area by cells other than those derived from surrounding bone tissue. These two different applications of the principle of guided tissue regeneration open new avenues for reconstructive osseous surgery.

Adult↗
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↗
PubMed1989

Generation of new bone around titanium implants using a membrane technique: an experimental study in rabbits.

Insufficient bone volume may be a significant problem in connection with dental implants. In this study, a technique based on the principle of guided tissue regeneration was tested for its ability to generate bone tissue around titanium implants. Implants were inserted in tibiae of rabbits. To create a secluded space for osteogenesis and to prevent soft-tissue ingrowth, a porous Teflon membrane was placed around exposed parts of the implant. Where a membrane had been used, the threads of the implant were completely covered with significant amounts of new bone. This study indicates that the membrane technique is a reconstructive surgical method that may be applicable to create new bone around exposed parts of titanium implants in a clinical setting.

Animals↗
PubMed1988

Healing of bone defects by guided tissue regeneration.

In this study we describe a principle for the accomplishment of bone regeneration based on the hypothesis that different cellular components in the tissue have varying rates of migration into a wound area during healing. By a mechanical hindrance, using a membrane technique, fibroblasts and other soft connective-tissue cells are prevented from entering the bone defect so that the presumably slower-migrating cells with osteogenic potential are allowed to repopulate the defect. Defects of standard size were created bilaterally through the mandibular angles of rats. On one side of the jaw the defect was covered with Teflon membranes, whereas the defect on the other side served as control. Histologic analysis after healing demonstrated that on the test (membrane) side, half the number of animals showed complete bone healing after 3 weeks and all animals showed complete healing after 6 weeks. Little or no sign of healing was evident on the control side even after an observation period of 22 weeks.

Animals↗
PubMed1988

The angular bony defect in the maintenance of the periodontal patient.

The present retrospective study was performed to evaluate some long-term alterations of the alveolar bone level at periodontal sites with angular and even ("horizontal") patterns of bone loss. The investigation included 48 patients who, following treatment for advanced periodontal disease, were placed in a maintenance care program which included recall appointments every 3-6 months for a period of 5 to 16 years. The material of the study comprised all teeth at which angular osseous defects (test sites) could be detected in a full-mouth series of radiographs obtained at the end of the active treatment phase. Alterations in the position of the marginal alveolar bone crest and the base of the osseous defect which took place during the maintenance period were assessed by comparing the post-treatment radiographs with a 2nd set of radiographs obtained at the final examination. In the same patients, an equal number of contralateral or neighboring teeth at which bone loss in the radiographs had an even or "horizontal" character were included as controls. The results from the assessments demonstrated that periodontal sites which, following active therapy displayed either angular or "horizontal" patterns of alveolar bone loss underwent, during a 5-16 year period of maintenance, only minor bone level alterations. Additional loss of supporting bone occurred equally frequently at sites with "horizontal" and angular patterns of bone loss. Thus, the findings reported failed to show up sites with angular bony defects as being particularly susceptible to recurrent destructive periodontitis.

Adult↗
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↗
PubMed1987

Prevalence and microbiology of localized prepubertal periodontitis.

Loss of crestal alveolar bone at primary teeth was ascertained radiographically in a dental school clinical population of 2264 children. 19 patients (0.84%) demonstrated distinct periodontal bone destruction around one or more primary teeth; in only 2 of these patients had periodontal disease been identified in previous clinical examinations. A microbiological study of 35 subgingival samples from 9 available patients revealed a high prevalence of black-pigmented Bacteroides spp., mainly Bacteroides intermedius. Actinobacillus actinomycetemcomitans and Capnocytophaga spp. were predominant organisms in some samples. The present data indicate that localized prepubertal periodontitis is more common than previously realized and is associated with bacteria generally regarded as major periodontal pathogens.

Aggregatibacter actinomycetemcomitans↗