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Biomedical subjects

J Lindhe

Publications and source records attributed to J Lindhe.

At least 19 recordsLinked to original sources
PubMed2005

Inflammatory lesions in the gingiva following resective/non-resective periodontal therapy.

BACKGROUND: Findings from previous experiments have revealed that inflammatory cell infiltrates may remain in the gingiva following clinically successful non-surgical periodontal therapy. PURPOSE: To investigate the presence of inflammatory lesions in the gingiva following a periodontal treatment procedure that included either soft-tissue resection [gingivectomy (GV)] or non-resective open-flap debridement (OFD). MATERIAL AND METHODS: Fifteen patients with advanced generalized chronic periodontitis were recruited. Following oral hygiene instruction and supragingival debridement, one tooth site in each quadrant (non-molar, probing pocket depth>5 mm, bleeding on probing(+) and >50% bone loss) was selected and a soft-tissue biopsy was obtained and prepared for immunohistochemical analysis. Using a split-mouth design, two quadrants were randomly selected for periodontal therapy including GV, while the two remaining quadrants were exposed to non-resective OFD procedure. Six months after completion of surgical treatment, a new set of biopsies was obtained from GV and OFD sites. RESULTS: The inflammatory lesions residing in the gingival biopsies obtained prior to surgical therapy were 1.33-1.41 mm(2) large and contained similar proportions of CD19(+)- (B-cells, 15%), CD3(+)- (T-cells, 7%) and elastase(+)- (polymorphonuclear cells, 2%) cells in the two treatment groups. The corresponding lesions identified in the soft-tissue specimens obtained after 6 months of healing were twice as large at OFD as at GV sites (0.19 versus 0.08 mm(2), p=0.002). The densities of CD19(+)- and elastase(+)-cells in these lesions were significantly greater at OFD than at GV sites. CONCLUSION: The findings of the present study indicate that surgical therapy including soft-tissue resection results in regenerated gingival units that contain smaller lesions with lower densities of immunocompetent cells when compared with the lesions remaining in sites treated by non-resective means.

Adult↗
PubMed2005

Healing of extraction sockets and surgically produced - augmented and non-augmented - defects in the alveolar ridge. An experimental study in the dog.

OBJECTIVES: The current experiments had three aims (i) to determine whether the absence of the periodontal ligament (PDL) may alter features of the healing of an extraction socket, (ii) to examine if there were differences in the proportion of different tissues in resolved extraction sockets and surgically produced defects after 3 months of healing, (iii) to study the influence of different biomaterials on the healing of surgically produced bone defects. MATERIAL AND METHODS: Extraction sites: In five dogs, the 4th mandibular pre-molars were hemi-sected and the distal roots were removed. The extraction socket of one of the pre-molars was instrumented to eliminate all remnants of the PDL tissue. The socket of the contra-lateral pre-molar was left without instrumentation. The dogs were sacrificed after 3 months of healing. Defect sites: In five dogs, the pre-molars and 1st molars on both sides of the mandible were first removed and 3 months of healing allowed. After this interval three standardized cylindrical defects were prepared in each side of the mandible. The defects were 3.5 mm in diameter and 8 mm deep. In each quadrant one defect was grafted with Bio-Oss Collagen, one with Collagen Sponge and one defect was left non-grafted. The dogs were sacrificed 3 months after the grafting procedure. RESULTS: Extraction sites: The two categories of extraction sockets did not differ with respect to gross morphological features. The tissue of the extraction sites, apical of a newly formed bone bridge, was dominated by bone marrow. Few trabeculae of lamellar bone were also present. Defect sites: The non-augmented defect was sealed by a hard-tissue bridge. In the central and apical portions of the defect bone marrow made up about 61%, and mineralized bone 39% of the tissues. The invagination of the surface of this crestal bone was 0.8+/-0.3 mm. The defect augmented with Collagen Sponge was covered by a hard-tissue bridge 38% of the tissue within the defect was made up of bone marrow while the remaining 62% was occupied by mineralized bone. The invagination of the hard-tissue bridge was on the average 0.6+/-0.1 mm. In defects augmented with Bio-Oss Collagen the biomaterial occupied a substantial portion of the tissue volume. Eighty-five percent of the periphery of the Bio-Oss particles were found to be in direct contact with newly formed mineralized bone. Woven bone and bone marrow made up 47% and 26% of the newly formed tissue. The invagination of the most coronal part of the bone defect was 0.1+/-0.1 mm. CONCLUSION: Sockets that following tooth removal had their PDL tissue removed exhibited similar features of healing after 3 months as sockets which had the PDL retained. The tissues present in an extraction site appeared to be more mature than those present in a surgically produced defect of similar dimension. The Bio-Oss Collagen augmented defect exhibited less wound shrinkage than the non-augmented defect.

Alveolar Process↗
PubMed2005

Host response to microbial challenge following resective/non-resective periodontal therapy.

BACKGROUND: The host response to microbial challenge depends on the recruitment of homing leucocytes and may be related to the experience to infectious insults over years. PURPOSE: The aim of this study was to investigate the soft tissue reactions to de novo plaque formation at sites treated with either open flap debridement or with the use of resective means during periodontal therapy. MATERIAL AND METHODS: Fifteen patients, who had been treated for periodontal disease (severe generalized chronic periodontitis), participated in the study. Surgical therapy was performed using either gingivectomy (GV) or open flap debridement (OFD) procedures in a split mouth design. After 6 months of healing (day 0), two gingival biopsies were obtained, one from the GV- and one from the OFD-treated sites. The experimental gingivitis model was applied and plaque accumulation was allowed for 3 weeks. New biopsies were obtained from the remaining quadrants on day 21 of plaque formation. The biopsies were snap frozen and prepared for immunohistochemical analysis. RESULTS: Following 3 weeks of plaque accumulation, the size of the lesion in OFD sites was more than twice as large than that in GV sites (0.42 versus 0.19 mm2). In the GV units, the lesion was characterized by almost similar proportions of T cells (CD3+, 6.0%) and B cells (CD19+, 6.6%), while the ICT in OFD sites was dominated by B cells (13.8%). During the 3-week period of plaque formation the increase in cell densities of T and B cells was three times larger in OFD than in GV sites. The proportion of ELAM-1 (CD62+ cells) decreased in GV (-0.4%) and increased in OFD (0.9%) sites. CONCLUSIONS: The host response that occurred in the gingival sites treated with OFD was more pronounced than the reaction that under similar experimental conditions took place in the regenerated gingiva at sites treated by resective means.

Adult↗
PubMed2005

Bone reactions to longstanding functional load at implants: an experimental study in dogs.

OBJECTIVES: The aims of the present investigation were (i) to study marginal bone level alterations following implant installation, abutment connection and functional loading and (ii) to analyse bone tissue reactions to functional load. MATERIAL AND METHODS: Six beagle dogs, about 1-year old, were used. All mandibular pre-molars were extracted. Three months later four implants of the Astra Tech Implants Dental System were installed in one side of the mandible and four standard fixtures of the Brånemark System were placed in the contralateral side of the mandible. Abutment connection was performed 3 months later and a plaque control programme was initiated. Three months after abutment connection fixed partial dentures (FPDs) made in gold were cemented to the maxillary canines and pre-molars. FPDs were also connected to the three posterior implants in each side of the mandible, while the mesial implant in each side was used as an unloaded control. Radiographs were obtained from all implant sites following implant installation, abutment connection and FPD placement. Ten months after the FPD placement the radiographic examination was repeated. The animals were sacrificed and biopsies from all implant sites were obtained and prepared for histological analysis. RESULTS: The radiographic analysis revealed that largest amount of bone loss occurred following implant installation and abutment connection and that this loss was more pronounced at Brånemark than at Astra implants. The bone level alterations that were observed at implants exposed to 10 months of functional load in both implant systems were small and did not differ from control sites. The histological analysis revealed that implants exposed to functional load exhibited a higher degree of bone-to-implant contact than control implants in both implant systems. CONCLUSION: It is suggested that functional load at implants may enhance osseointegration and does not result in marginal bone loss.

Alveolar Bone Loss↗
PubMed2004

Submerged or non-submerged healing of endosseous implants to be used in the rehabilitation of partially dentate patients.

OBJECTIVE: To evaluate bone-level alterations that occurred at implants of the Astra Tech(R) System that were placed in the load carrying, posterior parts of the dentition using either a submerged (two-stage) or a non-submerged (one-stage) installation protocol. MATERIAL AND METHODS: Eighty-four patients that required 115 fixed partial dentures (FPDs or cases) entered the prospective study. All subjects were assigned one patient and > or =one case numbers. For the randomization of cases, a custom-made program based on balanced random permuted blocks was utilized. The cases were assigned to two treatment groups, namely one-stage installation procedure, non-submerged technique (group A) and two-stage installation procedure, submerged technique (group B). Several subjects contributed with cases to both groups A and B. Periodontal, endodontal and open caries lesions were treated prior to implant installation. All patients received careful oral hygiene instruction and training in self-performed plaque control measures. The surgical technique used for fixture installation followed the outline described in the manual for the Astra Tech System. The FPDs were placed 3 months (mandible) and 6 months (maxilla) following implant installation. Immediately following FPD placement, a baseline examination was performed that included assessment of plaque, soft-tissue inflammation and bone level. Clinicians who were otherwise not involved in the study performed the radiographic measurements. Clinical and radiographical examinations were repeated once a year after the baseline examination. DATA ANALYSIS: The primary outcome variable was the change in the bone level at the implants from the time of placement of the bridge (FPD) to the 1- and 2-year reexaminations. Fisher's permutation test was used to test if differences existed between groups A and B, and between patients (men/women, smokers/non-smokers, age), sites (maxilla/mandible) and implants (length, diameter). Pitman's test was used to study correlations between bone shape and quality data and different radiographic bone-level data. RESULTS: It was demonstrated that tissue healing following implant installation appeared to be independent of the surgical protocol, i.e. whether the marginal portions of the implants during surgery were fully or only partly submerged under the ridge mucosa. Thus, (i) in both treatment groups the number of implants that failed to osseointegrate (early failures) was small (<2%); (ii) at the end of the recommended periods of bone healing prior to loading, - in both groups, maxilla=6 months and mandible=3 months - the level of the marginal bone was close to the coronal rim of the fixture; group A: 1.54+/-0.92 mm, group B: 1.31+/-0.77 mm. The current study also demonstrated that irrespective of surgical protocol (two-stage, one-stage), implants supporting the FPDs exhibited only small amount of radiographic bone loss during the first year of function (group A: 0.02+/-038 mm, group B: 0.17+/-0.64 mm). Moreover, during the second year of function, the amount of additional bone loss that occurred in the two treatment groups was close to zero. CONCLUSION: Periimplant bone-level change during function seemed to be unrelated to whether initial soft- and hard-tissue healing following implant installation had occurred under submerged or non-submerged conditions.

Adult↗
PubMed2004

The long-term effect of a plaque control program on tooth mortality, caries and periodontal disease in adults. Results after 30 years of maintenance.

BACKGROUND: The biofilm that forms and remains on tooth surfaces is the main etiological factor in caries and periodontal disease. Prevention of caries and periodontal disease must be based on means that counteract this bacterial plaque. OBJECTIVE: To monitor the incidence of tooth loss, caries and attachment loss during a 30-year period in a group of adults who maintained a carefully managed plaque control program. In addition, a comparison was made regarding the oral health status of individuals who, in 1972 and 2002, were 51-65 years old. MATERIAL AND METHODS: In 1971 and 1972, more than 550 subjects were recruited. Three hundred and seventy-five subjects formed a test group and 180 a control group. After 6 years of monitoring, the control group was discontinued but the participants in the test group was maintained in the preventive program and was finally re-examined after 30 years. The following variables were studied at Baseline and after 3, 6, 15 and 30 years: plaque, caries, probing pocket depth, probing attachment level and CPITN. Each patient was given a detailed case presentation and education in self-diagnosis. Once every 2 months during the first 2 years, once every 3-12 months during years 3-30, the participants received, on an individual need basis, additional education in self-diagnosis and self-care focused on proper plaque control measures, including the use of toothbrushes and interdental cleaning devices (brush, dental tape, toothpick). The prophylactic sessions that were handled by a dental hygienist also included (i) plaque disclosure and (ii) professional mechanical tooth cleaning including the use of a fluoride-containing dentifrice/paste. RESULTS: Few teeth were lost during the 30 years of maintenance; 0.4-1.8 in different age cohorts. The main reason for tooth loss was root fracture; only 21 teeth were lost because of progressive periodontitis or caries. The mean number of new caries lesions was 1.2, 1.7 and 2.1 in the three groups. About 80% of the lesions were classified as recurrent caries. Most sites, buccal sites being the exception, exhibited no sign of attachment loss. Further, on approximal surfaces there was some gain of attachment between 1972 and 2002 in all age groups. CONCLUSION: The present study reported on the 30-year outcome of preventive dental treatment in a group of carefully monitored subjects who on a regular basis were encouraged, but also enjoyed and recognized the benefit of, maintaining a high standard of oral hygiene. The incidence of caries and periodontal disease as well as tooth mortality in this subject sample was very small. Since all preventive and treatment efforts during the 30 years were delivered in one private dental office, caution must be exercised when comparisons are made with longitudinal studies that present oral disease data from randomly selected subject samples.

Adult↗
PubMed2004

Spontaneous progression of experimentally induced periimplantitis.

BACKGROUND: Periimplantitis represents an inflammatory condition that is associated with the presence of a submarginal biofilm and with advanced breakdown of soft and mineralized tissues surrounding endosseous implants. Animal models have been used to describe mechanisms involved in the pathogenesis and treatment of the soft and hard tissue lesions of periimplantitis. OBJECTIVE: The aim of the present experiment was to study the presence and progression of inflammatory lesions in tissues surrounding implants exposed to "experimental periimplantitis". MATERIAL AND METHODS: Five Labrador dogs were used. In each dog, 2 or 3 implants were placed in both the left and right edentulous premolar regions of the mandible. Abutment connection was performed 4 months later and a plaque control regimen was initiated and maintained for 5 months. "Experimental periimplantitis" was subsequently induced by ligature placement and plaque accumulation was allowed to progress until about 40% of the height of the supporting bone had been lost. The ligatures were removed, but plaque formation was allowed to continue for an additional 12 months. Radiographs of all implant sites were obtained before and after active "experimental periimplantitis" as well as at the end of the experiment. Biopsies were harvested from the implant sites in 3 of the dogs. The tissue samples were prepared for light microscopy and the sections were used for histometric and morphometric examinations. RESULTS: One implant was lost during the first 2 months of "experimental periimplantitis" and two implants were lost during the 12 months that followed ligature removal. The radiographic examination indicated that varying amounts of additional bone loss occurred in the majority of the implant sites also following ligature removal. The mucosa of all implant sites harbored inflammatory lesions that extended apically of the pocket epithelium. The lesions were separated from the marginal bone by a zone of apparently normal connective tissue. CONCLUSION: A remission of the destructive inflammatory lesion in the periimplant tissues was seen in some sites following ligature removal, but in the majority of sites additional loss of supporting bone occurred.

Animals↗
PubMed2003

Association between level of education and oral health status in 35-, 50-, 65- and 75-year-olds.

AIM: The aim of the present study was to evaluate the association between educational level and dental disease, treatment needs and oral hygiene habits. MATERIAL AND METHODS: Randomized samples of 35-, 50-, 65- and 75-year-olds, classified according to the educational level: [low (LE): elementary school or higher (HE)], were identified. In 1091 subjects, a number of characteristics such as (i) number of teeth, (ii) periodontal attachment levels (PAL), (iii) caries and (iv) occlusal function were recorded. Educational level, oral hygiene and dietary habits were self-reported. Non-parametric variables were analyzed by chi2, Mann-Whitney U-Wilcoxon's rank sum tests, and parametric variables by Student's t-test (level of significance 95%). A two-way anova was performed on decayed, missing and filled surfaces to investigate the interaction between age and educational level. All statistical procedures were performed in the SPSS statistical package. RESULTS: The number of remaining teeth was similar for LE and HE in the 35-year olds (25.8 versus 26.6), but in the older age groups LE had significantly a larger number of missing teeth. The LE groups (except in 65-year olds) exhibited significantly more PAL loss. LE had significantly fewer healthy gingival units in all but the 75-year age group. In all age groups, LE had fewer intact tooth surfaces and a significantly poorer occlusal function. The frequency of tooth cleaning measures and dietary habits did not differ between LE and HE. CONCLUSION: Educational level was shown to influence the oral conditions and should be considered in assessing risk, and in planning appropriate preventive measures.

Adult↗
PubMed2003

Dynamics of bone tissue formation in tooth extraction sites. An experimental study in dogs.

OBJECTIVES: The aim of the present experiment was to study events involved in the healing of marginal, central and apical compartments of an extraction socket, from the formation of a blood clot, to bone tissue formation and remodeling of the newly formed hard tissue. MATERIAL AND METHODS: Nine mongrel dogs were used for the experiment. The fourth mandibular premolars were selected for study and were divided into one mesial and one distal portion. The distal root was removed and the socket with surrounding soft and mineralized tissue was denoted "experimental unit". The dogs were killed 1, 3, 7, 14, 30, 60, 90, 120 and 180 days after the root extractions. Biopsies including the experimental units were demineralized in EDTA, dehydrated in ethanol and embedded in paraffin. Serial sections 7 microm thick were cut in a mesio-distal plane. From each biopsy, three sections representing the central part of the socket were selected for histological examination. Morphometric measurements were performed to determine the volume occupied by different types of tissues in the marginal, central and apical compartments of the extraction socket at different intervals. RESULTS: During the first 3 days of healing, a blood clot was found to occupy most of the extraction site. After seven days this clot was in part replaced with a provisional matrix (PCT). On day 14, the tissue of the socket was comprised of PM and woven bone. On day 30, mineralized bone occupied 88% of the socket volume. This tissue had decreased to 15% on day 180. The portion occupied by bone marrow (BM) in the day 60 specimens was about 75%, but had increased to 85% on day 180. CONCLUSION: The healing of an extraction socket involved a series of events including the formation of a coagulum that was replaced by (i) a provisional connective tissue matrix, (ii) woven bone, and (iii) lamellar bone and BM. During the healing process a hard tissue bridge--cortical bone--formed, which "closed" the socket.

Animals↗
PubMed2003

Effect of enamel matrix proteins (Emdogain') on healing after re-implantation of "periodontally compromised" roots. An experimental study in the dog.

OBJECTIVE: The present experiment was performed to assess whether Emdogain applied on the root surface of extracted teeth or teeth previously exposed to root planning can protect the tooth from ankylosis following re-implantation. MATERIAL AND METHODS: The experiment included two groups of dogs, including five animals each. The root canals of all mandibular third premolars (3 P 3) were reamed and filled with gutta-percha. A crestal incision was placed from the area of the second to the fourth premolar. Buccal and lingual full thickness flaps were elevated. With the use of a fissure bur, the crown and furcation area of 3 P 3 were severed in an apico-coronal cut. The distal and mesial tooth segments were luxated with an elevator and extracted with forceps. Group A: The mesial and distal segments of 3 P 3 were air dried on a glass surface for 60 min. The roots from the right side were conditioned and exposed to Emdogain application. The roots from the left side received the same treatment with the exception of Emdogain application. The mesial and distal tooth segments were re-implanted and the crown portions were severed with a horizontal cut and removed. The buccal and lingual flaps were mobilized and sutured to obtain complete coverage of the submerged roots. Group B: A notch was prepared in each root, 4-5 mm apical of the cemento-enamel junction. The area of the root that was located coronal to the notch was scaled and planned. The roots in the right side of the mandible were treated with Emdogain, while the roots in the left side served as controls. After 6 months of healing, the dogs were killed and blocks containing one root with surrounding tissues were harvested, and prepared for histological examination, which also included morphometric assessments. Thus, the proportions of the roots that exhibited signs of (i) replacement (ii) inflammatory and (iii) surface resorption were calculated. RESULTS AND CONCLUSION: It was demonstrated that healing of a re-implanted root that had been extracted and deprived of vital cementoblasts was characterized by processes that included root resorption, ankylosis and new attachment formation. It was also demonstrated that Emdogain treatment, i.e. conditioning with EDTA and placement of enamel matrix proteins on the detached root surface, failed to interfere with the healing process.

Animals↗
PubMed2002

Bone reactions at implants subjected to experimental peri-implantitis and static load. A study in the dog.

AIM: The aim of the present experiment was to study peri-implant tissue reactions to lateral static load at implants subjected to experimental mucositis or peri-implantitis. MATERIAL AND METHODS: 5 beagle dogs were used. The mandibular premolars were extracted. After 12 weeks, 3 implants were installed in each quadrant of the mandible. In one side, the implants were designed with a SLA surface and in the contralateral side with a turned surface. A plaque control program was initiated. 12 weeks later, the central and posterior implants were connected with an appliance containing an expansion screw. Cotton ligatures were placed around the neck of the anterior and posterior implants in both sides, and the plaque control measures were terminated. Sixteen weeks later the ligatures were removed. After 8 weeks without ligatures, the expansion screws in both sides were activated. Once every 2 week during a 12-week interval, the screws were reactivated. Thus, the model included 3 different experimental sites of each surface group: group M+L (mucositis+load); group P (peri-implantitis); group P+L (peri-implantitis+load). Fluorochrome labels were injected and standardized radiographs obtained. The animals were sacrificed and block biopsies of all implant sites dissected and prepared for histological analysis. RESULTS: It was demonstrated that the lateral static load failed to induce peri-implant bone loss at implants with mucositis and failed to enhance the bone loss at implants with experimental peri-implantitis. The proportion of bone labels and the bone density in the interface zone were significantly higher in group P+L than in group P. CONCLUSION: It is suggested that a lateral static load with controlled forces may not be detrimental to implants exhibiting mucositis or peri-implantitis.

Alveolar Bone Loss↗
PubMed2002

The mucosal attachment to titanium implants with different surface characteristics: an experimental study in dogs.

BACKGROUND: Findings from in vitro studies have indicated that the orientation and proliferation of cells on titanium surfaces may be influenced by the topography of the surface on which they are grown. It may be argued, therefore, that differences may occur in the mucosal attachment to titanium implants with different surface roughness. AIM: The present experiment was performed to study the composition of the soft tissue barrier that formed to implants prepared with well-defined smooth or rough surfaces. MATERIAL AND METHODS: Five beagle dogs were used. Four implants made of c.p. titanium were placed in the right edentulous mandibular premolar region. After 3 months, two different types of abutments were connected: one experimental (OA) with a dual, thermal acid-etched surface ('Osseotite'), and one regular (RA) abutment with a 'turned' surface. At the end of a 6-month period during which proper plaque control had been maintained, biopsies including the implant and the surrounding soft and hard tissues were obtained, decalcified and processed for light and electron microscopy. A confocal He-Ne laser profilometer was used to study the surface topography of the abutments. RESULTS: The attachment between the peri-implant mucosa and titanium abutments with either a turned (RA; 'smooth') or acid-etched (OA; 'rough') surface was similar from both a quantitative and a qualitative aspect. The attachment comprised a barrier epithelium and a zone of connective tissue attachment of similar dimension at RA and OA. It was further observed that the 'inner' zone of the connective tissue attachment at both types of abutment was composed of about 30-33% fibroblasts and 63-66% collagen. CONCLUSION: It was demonstrated that the soft tissue attachment that formed to implants made of c.p. titanium was not influenced by the roughness of the titanium surface.

Acid Etching, Dental↗
PubMed2002

Soft tissue reactions to plaque formation at implant abutments with different surface topography. An experimental study in dogs.

BACKGROUND: The mucosal attachment that forms to titanium implants, uncontaminated by bacterial plaque comprises, independent of the surface characteristics of the abutment, one barrier epithelium and one zone of connective tissue attachment. It was suggested that abutments with a rough surface may accumulate more plaque than abutments with a smooth surface and that such an enhanced rate of plaque build-up may favor the development of inflammatory lesions in the periimplant mucosa. OBJECTIVES: The aim of the present experiment was to study some reactions of the periimplant mucosa to plaque accumulation on implant abutments designed with either a rough or a smooth external surface. MATERIAL AND METHODS: In five beagle dogs, four fixtures were placed and submerged in the premolar region. In a second stage procedure performed after 3 months, abutments with two different types of surface topography, one rough, acid-etched (OA) and one smooth, turned abutment (TA), were installed in a random order. After 6 months of undisturbed plaque formation, the animals were sacrificed and biopsies obtained. Tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. RESULTS: Six months of plaque accumulation resulted in the establishment of an inflammatory lesion (pl-ICT) in the connective tissue of the periimplant mucosa, the location, size and composition of which did not differ between OA and TA sites. In addition, most OA and TA sites harbored a second inflammatory cell infiltrate in the tissue lateral to the abutment/fixture junction (ab-ICT). While pl-ICT was dominated by plasma cells and lymphocytes, ab-ICT contained a comparatively large number of polymorphonuclear leukocytes. CONCLUSION: The different surface characteristics of abutment made of c.p. titanium failed to influence plaque formation and the establishment of inflammatory cell lesions in the periimplant mucosa.

Acid Etching, Dental↗
PubMed2002

Expression of endothelial adhesion molecules in the alveolar ridge mucosa, gingiva and periimplant mucosa.

OBJECTIVES: The purpose of this study was to analyze the expression of adhesion molecules on endothelial cells in the alveolar ridge mucosa, the gingiva and the periimplant mucosa in humans. MATERIAL AND METHODS: Twelve partially edentulous subjects were included in the study. In each subject, one soft tissue biopsy was harvested from the edentulous alveolar ridge mucosa, one from a tooth site and one from an implant site. After 3 weeks of undisturbed plaque accumulation, an additional biopsy was obtained from one tooth and one implant site in each subject. The tissue samples were snap frozen and prepared for immunohistochemical analysis. RESULTS: In the alveolar ridge mucosa, smaller proportions of endothelial cells expressing ICAM-1, ELAM-1 and VCAM-1 were observed than in the gingiva. ELAM-1-positive cells occurred in lower numbers than in periimplant mucosa. After 21 days of plaque accumulation, ELAM-1 was increased in tooth sites, but decreased in periimplant mucosa. CONCLUSION: The results of the present study indicated that the proportions of activated endothelial cells and the extravasation of leukocytes is larger in gingiva and periimplant mucosa than in alveolar ridge mucosa. This might be due to the less permeable keratinized epithelial layer in the edentulous ridge mucosa, which offers proper protection against microbial pathogens. The greater expression of endothelial cell adhesion molecules during experimental gingivitis, compared to periimplant mucositis, may reflect its longer history of repeated antigenic assaults.

Aged↗
PubMed2002

Lateral ridge augmentation by the use of grafts comprised of autologous bone or a biomaterial. An experiment in the dog.

OBJECTIVE: The present investigation was performed to determine if a block of Bio-Oss used as an onlay graft can be used as a scaffold for new bone formation. MATERIAL AND METHODS: Five mongrel dogs were used. The mandibular premolars were extracted. On both sides of the mandible, the buccal bone plate was resected and defects, about 25 mm long, 8 mm high and 5 mm wide, were produced After 3 months of healing, a second surgical procedure was performed. In the left side, a block of Bio-Oss was adjusted to the buccal bone wall. The graft had the shape of a cylinder and was retained with a miniscrew and covered with a collagen membrane. In the contra-lateral side of the mandible, a block biopsy was first obtained from the ascending ramus. This bone graft had the shape of a cylinder that was 8 mm in diameter and 3 mm thick. The graft was transferred to the experimental site, adjusted to the buccal wall, retained with a miniscrew, and covered with a membrane. The flaps were repositioned and closed with sutures to ensure a complete coverage of the experimental sites. After 6 months of healing, the dogs were sacrificed and the experimental sites dissected. The biopsies were processed for ground sectioning. The sections were stained in toluidine blue, examined in the microscope, and a number of histo- and morphometric assessments made. RESULTS: The study demonstrated that cortical bone used as an onlay graft in the lateral aspect of the alveolar ridge, during a 6-month period of healing integrated with the host bone but underwent marked peripheral resorption. Thus, close to 30% of the height and 50% of the length of the graft was replaced with connective tissue. It was further observed that while the dimensions of a graft which contained a scaffold of cancellous bovine bone mineral remained unchanged, only moderate amounts of new bone formed at the base of this graft. CONCLUSION: Grafts of autologous cortical bone, placed on the surface of a one-wall defect, may undergo marked resorption during healing. A similar graft of Bio-Oss may retain its dimension, and limited amounts of new bone will form within the biomaterial.

Alveolar Ridge Augmentation↗
PubMed2001

Bone reactions adjacent to titanium implants subjected to static load. A study in the dog (I).

The aim of the study was to evaluate the effect of lateral static load induced by an expansion force on the bone/implant interface and adjacent peri-implant bone. In 3 beagle dogs, the 2nd, 3rd and 4th mandibular premolars were extracted bilaterally. Twelve weeks later 8 implants of the ITI Dental Implant System were placed in each dog. Crowns connected in pairs were screwed on the implants 12 weeks after implant installation. The connected crowns contained an orthodontic expansion screw yielding 4 loading units in each dog. Clinical registrations, standardized radiographs and fluorochrome labeling were carried out during the 24-week loading period. Biopsies were harvested and processed for ground sectioning. The sections were subjected to histological examination. No evident marginal bone loss was observed at either test or control sites. The bone density and the mineralized bone-to-implant contact were higher adjacent to the lateral loaded implants than at the unactivated control sites. It is suggested that the static load applied to implants in a lateral direction resulted in a structural adaptation of the peri-implant bone.

Adaptation, Physiological↗
PubMed2001

Bone reactions adjacent to titanium implants with different surface characteristics subjected to static load. A study in the dog (II).

The purpose of the present study was to compare bone reactions adjacent to titanium implants with either a titanium plasma-sprayed (TPS) or a machined surface subjected to lateral static loading induced by an expansion force. In 3 labrador dogs, the 2nd, 3rd and 4th mandibular premolars were extracted bilaterally. 12 weeks later, 2 implants with a TPS surface were placed in one side and 2 implants with a machined surface were placed in the contralateral side. Twelve weeks after implant installation, crowns, connected in pairs with orthodontic expansion screws, were fitted to the implants and a 0.6 mm wide expansion was initiated. Clinical registrations, standardized radiographs and fluorochrome labeling were carried out during a 24-week period of loading. Biopsies with the implants in situ were harvested and processed for ground sectioning. The sections were subjected to histologic and histometric examination. A higher marginal bone level was observed around implants with a TPS surface compared to machined implants. Furthermore, the values describing the amount of bone-to-implant contact at the bone/implant interface as well as the density of the peri-implant bone were lower at the machined than at the TPS implants.

Alveolar Process↗