Biomedical subjects

I Abrahamsson

Publications and source records attributed to I Abrahamsson.

10 recordsLinked to original sources

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↗

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↗

PubMed1999

Peri-implant tissues at submerged and non-submerged titanium implants.

The present experiment was performed to study the peri-implant tissue response to non-submerged (1-stage) and initially submerged (2-stage) implant installation procedures. 6 beagle dogs were used. All mandibular premolars and the 1st, 2nd and 3rd maxillary premolars were extracted. After 3 months of healing, 3 fixtures of the Astra Tech System were installed and submerged in the right (or the left) edentulous, premolar region in each of the 6 dogs. Radiographs were obtained immediately after fixture installation. In the radiographs, the distance between the abutment-fixture junction and the most "coronal" bone in contact with the implant surface was determined. 3 months later, abutments were connected to the initially submerged fixtures and another 3 fixtures of the same system were installed in the contralateral, edentulous premolar region. Abutments were, however, immediately connected to the newly-installed fixtures (non-submerged side; test side). The mucosal flaps were replaced, adjusted and sutured in such a way that the coronal portion of the abutments remained exposed in the oral cavity. A new set of radiographs were obtained from all 6 implant sites in each animal. A period of plaque control was initiated. Clinical examinations were performed and radiographs obtained from all implant sites after another 3 months and at the termination of the experiment. 9 months after the 1st fixture installation procedure, the animals were sacrificed, the mandibles were removed, and each implant region dissected. The most mesially-located implant sites were processed for ground sectioning. The remaining biopsies were processed and embedded in EPON. The histometric analysis included assessment of the vertical dimension of the marginal soft and mineralized peri-implant tissues. The ground sections were used for measurements describing (i) "bone to implant contact" and (ii) "bone density". It was observed that the mucosa and bone tissue that formed at implants placed in a non-submerged or a submerged procedure had many features in common. Thus, figures describing (i) the height of the mucosa, (ii) the length of the junctional epithelium and the height and quality of the zone of "connective tissue integration", (iii) the % of bone to implant contact as well as (iv) the density of the peri-implant bone, were similar in the submerged and the non-submerged groups. It is therefore suggested that a non-submerged (1-stage) installation technique may provide conditions for tissue integration that are similar to those obtained using a submerged (2-stage) approach.

Alveolar Process↗

PubMed1999

The barrier between the keratinized mucosa and the dental implant. An experimental study in the dog.

The present study was performed in order to examine the composition of the connective tissue that forms an attachment to a dental implant. 6 beagle dogs were used. All mandibular premolars were extracted. After 3 months of healing, 6 fixtures--3 in each side of the mandible--(Astra Tech Implants, Dental System TiO blast; Astra Tech AB, Mölndal, Sweden) were installed. After another 3 months of healing, abutment (Uni-abutment 45; Astra Tech AB, Mölndal, Sweden) connection was performed and a plaque control program was initiated. The animals were sacrificed and perfused with a fixative through the carotid arteries. Each implant site, including the implant and the soft and hard peri-implant tissues, was dissected, decalcified in EDTA and further processed using a "fracture technique". The specimens were subsequently embedded in EPON, cut with the microtome set at 3 microm and the sections stained in PAS and toluidine blue. From the EPON-embedded blocks, ultra-thin sections were cut and electron micrographs were prepared. The detailed histologic and morphometrical examinations were restricted to a 200 microm wide zone of connective tissue interposed between the apical border of the junctional epithelium and the bone tissue. In the analysis, this zone was further subdivided into 2 different units; (i) one central, 40 microm wide unit (zone A) located immediately next to the implant surface, and (ii) one lateral, 160 microm wide unit (zone B) that was continuous with the central unit. The implant surface apical of the junctional epithelium and coronal of the bone crest appeared to be in direct contact with a connective tissue. Zone A of this connective tissue was characterized by its (i) absence of blood vessels and (ii) abundance of fibroblasts which were interposed between thin collagen fibers. The more lateral zone B contained comparatively fewer fibroblasts, but more collagen fibers and blood vessels. There are reasons to assume that the fibroblast rich barrier tissue next to the titanium surface plays a rôle in the maintenance of a proper seal between the oral environment and the peri-implant bone.

Alveolar Process↗

PubMed1998

Soft tissue response to plaque formation at different implant systems. A comparative study in the dog.

The aim of the present experiment was to study the location and composition of plaque associated lesions in the mucosa adjacent to implant systems that differed with respect to both geometry and dimension. At day 0 extraction of the mandibular premolars were performed. After a healing period of 3 months, fixtures of the Astra Tech Implants, Dental System, the Brånemark System and the ITI Dental Implant System were installed. In each mandibular quadrant 1 fixture of each implant system was installed in a randomized order. A period of plaque control was initiated. Following another 3 months of healing, abutment connection was performed in the 2-stage systems (the Astra Tech Implants, Dental System and the Brånemark System). After 1 month, the plaque control measures were abandoned and plaque formation was allowed for 5 months. The animals were killed and biopsies representing each implant region obtained. The tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. The present study demonstrated that plaque formation resulted in the establishment of an ICT lateral to a pocket epithelium. The lesion was found to be similar regarding extension and composition in the peri-implant mucosa of the 3 implant systems tested. The vertical extension of the ICT was in all systems within 91-99% of the vertical dimension of the junctional epithelium. The marginal bone level, measured from the abutment/fixture (PS) border, did not differ between the three systems.

Animals↗

PubMed1998

The mucosal attachment at different abutments. An experimental study in dogs.

The present experiment was performed to examine if the material used in the abutment part of an implant system influenced the quality of the mucosal barrier that formed following implant installation. 5 beagle dogs were included in the study. The mandibular premolars and the 1st, 2nd and 3rd maxillary premolars were extracted. Three fixtures of the Brånemark System were installed in each mandibular quadrant (a total of 6 fixtures per animal). Abutment connection was performed after 3 months of healing. In each dog the following types of abutments were used: 2 "control abutments" (c.p. titanium), 2 "ceramic abutments" (highly sintered Al2O3), 1 "gold abutment", and 1 "short titanium abutment". This "short titanium abutment" was provided with an outer structure made of dental porcelain fused to gold. Following abutment connection a plaque control program was initiated and maintained for 6 months. The animals were sacrificed and perfused with a fixative. The mandibles were removed and each implant region was dissected, demineralized in EDTA and embedded in EPON. Semithin sections representing the mesial, distal, buccal and lingual aspects of the peri-implant tissues were produced and subjected to histological examination. The findings from the analysis demonstrated that the material used in the abutment portion of the implant influenced the location and the quality of the attachment that occurred between the periimplant mucosa and the implant. Abutments made of c.p. titanium or ceramic allowed the formation of a mucosal attachment which included one epithelial and one connective tissue portion that were about 2 mm and 1-1.5 mm high, respectively. At sites where abutments made of gold alloy or dental porcelain were used, no proper attachment formed at the abutment level, but the soft tissue margin receded and bone resorption occurred. The abutment fixture junction was hereby occasionally exposed and the mucosal barrier became established to the fixture portion of the implant. It was suggested that the observed differences were the result of varying adhesive properties of the materials studied or by variations in their resistance to corrosion.

Aluminum Oxide↗

PubMed1997

The mucosal barrier following abutment dis/reconnection. An experimental study in dogs.

In the present experiment, the effect on the marginal peri-implant tissues following repeated abutment removal and subsequent reconnection was studied. 5 beagle dogs were used. The mandibular premolars were extracted and 2 fixtures of the Brånemark System were installed, 1 in each mandibular quadrant. 3 months later, abutment connection was performed. A 6-month period of plaque control was initiated. Once a month during the plaque control period, the abutment of the right side (test) in each dog was disconnected, cleaned and reconnected to the failure. Thus, each test abutment was removed and reconnected altogether 5x during this period. The contralateral abutment remained undisturbed for 6 months and served as control. 1 month after the last reconnection, the animals were sacrificed and tissue samples, comprising the implant and the surrounding soft and hard peri-implant tissues, were obtained, decalcified, embedded in Epon and sectioned. The following landmarks were identified and used for linear measurements: PM (the marginal portion of the peri-implant mucosa), aJE (the level of the apical termination of the junctional epithelium), B (the marginal level of bone to implant contact), A/F (the abutment/fixture border). The findings indicate that the dis- and subsequent reconnections of the abutment component of the implant compromised the mucosal barrier and resulted in a more "apically" positioned zone of connective tissue. The additional marginal bone resorption observed at the test sites following abutment manipulation may be the result of tissue reactions initiated to establish a proper "biological width" of the mucosal-implant barrier.

Alveolar Bone Loss↗

PubMed1996

The peri-implant hard and soft tissues at different implant systems. A comparative study in the dog.

The aim of this study of the present experiment was to study the marginal periimplant tissues at intentionally non-submerged (1-stage implants) and initially submerged and subsequently exposed implants (2-stage implants). 5 beagle dogs, about 1-year-old, were used, 3 months after the extraction of the mandibular premolars, fixtures of the Astra Tech Implants Dental System, the Brånemark System and the Bonefit--ITI system were installed. In each mandibular quadrant, 1 fixture of each implant system was installed in a randomised order. The installation procedure followed the recommendations given in the manuals for each system. Thus, following installation, the bone crest coincided with the fixture margin of the Astra Tech Implants Dental System and the Brånemark System, whereas the border between the plasma sprayed and the machined surface of the Bonefit-ITI implant system was positioned at the level of the bone crest. Following a healing period of 3 months, abutment connection was carried out in the 2-stage systems (the Astra Tech Implants Dental System and the Brånemark system). A 6-month period of plaque control was initiated. The animals were sacrificed and biopsies representing each important region dissected. The tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. The mucosal barrier which formed to the titanium surface following 1-stage and 2-stage implant installations comprised an epithelial and a connective tissue component, which for that 3 systems studied, had similar dimensions and composition. The amount of lamellar bone contained in the periimplant region close to the fixture part of the 3-implant systems was almost identical. It is suggested that correctly performed implant installation may ensure proper conditions for both and hard tissue healing, and that the geometry of the titanium implant seems to be of limited importance.

Alveolar Process↗

PubMedDate not supplied

Bone and soft tissue integration to titanium implants with different surface topography: an experimental study in the dog.

The aim of the present experiment was to study the peri-implant soft and hard tissues formed at titanium implants with 2 different surface configurations and to give a topographic description of the surfaces examined. In 5 beagle dogs, the mandibular premolars were extracted. Three months later, 4 self-tapping standard implants (SI) and 4 Osseotite implants (OI) of the 3i Implant System were placed. The marginal 3 mm of the OI is turned, while the remaining part has an acid-etched surface structure. Abutments were connected after 3 months. A plaque control period was initiated, and after 6 months block biopsies were obtained. From each animal 2 units of each implant type were processed and embedded in EPON. The remaining biopsies were processed for ground sectioning. The histometric measurements performed on the EPON sections revealed that the peri-implant soft tissues and the marginal level of bone-to-implant contact were similar for SI and OI sites. In the ground sections, bone-to-implant contact (BIC%) and bone density assessments were made in 2 different zones. Zone I represented the contact area measured from the marginal level of bone-to-implant contact (B) to a position 4 mm above the apex of the implant, and zone II represented the apical 4 mm of the implant. For the SI sites, the BIC% was 56.1% in zone II and 58.1% in zones I + II. The corresponding figures for the 01 sites were 76.7% and 72.0%. The BIC% was significantly larger at OI than at SI sites. Bone density values were similar at the SI and OI sites.

Acid Etching, Dental↗