Showing papers on "Osseointegration published in 1991"

The Excessive Loss of Branemark Fixtures in Type IV Bone: A 5-Year Analysis*

Abstract: The predictability of branemark implants has been well documented. High success rates in the maxilla and mandible in fully and partially edentulous patients can be expected. A host of factors may be attributed to the etiology of fixture loss. However, the quality of bone stands out as the single greatest determinant in fixture loss. Types I, II, and III bone offer good strength. Type IV bone has a thin cortex and poor medullary strength with low trabecular density. Ninety percent of 1,054 implants placed were in Types I, II, and III bone. Only 3% of these fixtures were lost; of the 10% of the fixtures placed in Type IV bone, 35% failed. Presurgical determination of Type IV bone may be one method to decrease implant failure.

Bone graft and bone graft substitutes: a review of current technology and applications.

Abstract: The morbidity associated with autogenous bone graft harvest and the recent concern regarding the transmission of live virus through use of allografts, have been the impetus for research into a variety of materials that could take the place of these standard materials for bone grafting. The positive results reported with various ceramics and/or bone derivatives suggest the possibility of a material with osteoconductive and/or osteoinductive properties for use with or in place of bone graft. This review discusses a variety of bone graft and bone graft substitute materials. Among the osteoconductive materials outlined are the hydroxyapatite and tricalcium phosphate ceramics as well as some reportedly osteoactive polymers. While osteoconduction is a favorable quality, much interest has focussed on the use of osteoinductive or osteogenic materials such as demineralized bone matrix or bone derivatives,that is, BMP, osteogenin, etc. It is increasingly apparent that these materials require a carrier vehicle for optimal expression of osteoactivity. Therefore, the review finishes with a comparison of the various materials suggested for use as carriers.

Early failures in 4,641 consecutively placed Brånemark dental implants: a study from stage 1 surgery to the connection of completed prostheses.

Abstract: This study comprised 4,641 Branemark dental implants, which were retrospectively followed from stage 1 surgery to completion of the prosthetic restorations. The implants were placed during a 3-year period (1986 to 1988) in 943 jaws, representing 889 patients with complete and partial edentulism. The jaw and sex distribution revealed a predominance of mandibles (564/943) and females (534/943). The mean age of the patients was 57.5 years (range 13 to 88 years) at implant placement. Only 69 (1.5%) fixtures failed to integrate, and most losses were seen in completely edentulous maxillae (46/69), in which the jaw bone exhibited soft quality and severe resorption. A preponderance of failures could also be seen among the shortest fixtures (7 mm). A majority of the mobile implants were recorded at the abutment connection (stage 2) operation (48/69).

Fixation of hip prostheses by hydroxyapatite ceramic coatings

Abstract: We report the histological findings in post-mortem specimens obtained ten days, 17 days and seven weeks after implantation of hydroxyapatite-coated femoral components of hip arthroplasties. There was early deposition of woven bone on the hydroxyapatite ceramic, identical to that deposited on surviving cancellous trabeculae. The space between these deposits became bridged from both sides by new trabeculae, and there was no evidence of an inflammatory reaction or of fibrous tissue formation. The use of an hydroxyapatite coating seems to allow early, sound, secondary fixation of implants.

Effects of the platelet-derived growth factor/insulin-like growth factor-I combination on bone regeneration around titanium dental implants. Results of a pilot study in beagle dogs.

Abstract: The purpose of this study was to evaluate the early wound healing events of bone around press-fit titanium implants inserted with and without the concurrent application of a combination of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-I). Nine months prior to implant placement all mandibular premolar teeth were extracted in 8 beagle dogs. Subsequently, 40 specially manufactured titanium implants with 2 transverse holes in the apical section were press fit into precise recipient sites in the dogs' mandibles. The dogs were sacrificed at 7 and 21 days following implant placement yielding 12 PDGF-B/IGF-I treated and 8 control (placebo gel or non-treated) implants for each observation period. Coded undecalcified sections were analyzed for: 1) percentage of implant surface in contact with new bone; 2) percentage of peri-implant space filled with new bone; and 3) percentage of implant hole filled with new bone. An analysis of variance was used to determine significant differences among the treatment groups. At 7 days, the percentage of bone fill in the peri-implant spaces and the percentage of implant surface in contact with new bone were both significantly increased in PDGF-B/IGF-I treated sites (P less than 0.01 for both groups). There was less than 1.5% fill of the implant holes in both treated and control sites (no significant differences). At 21 days the percentage of bone fill in the peri-implant spaces was significantly increased in the PDGF-B/IGF-I treated sites (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Periodontal tissues and their counterparts around endosseous implants

Abstract: New technology coupled with a better understanding of tissue biology has played a key role in restoring the somewhat tarnished image of implant dentistry, Thanks to carefully conducted longitudinal studies, it has now become clear that the replacement of missing teeth by artificial implants integrated into the living tissues of the jaws is a predictable procedure, as long as certain guidelines are followed in the manufacture of the implant, its placement, its eventual functional loading, and its maintenance. Yet, functional success for a natural tooth is dependent on a number of anatomic, physiologic, and environmental considerations which differ in some important respects from those that insure the functional success of an implant. In this paper, we review the anatomic features of the natural dentition with emphasis on the periodontal tissues, and contrast these characteristics with those that exist around well-integrated endosseous implants.

Dental implant design–effect on bone remodeling

Abstract: Bone remodeling around three different endossesous dental implant designs placed in dog mandibles was studied using radiography during lengthy periods of function and by histology after animal sacrifice. The three designs investigated were (a) threaded (c.p. titanium), (b) fully porous-coated (titanium alloy), and (c) partially porous-coated (titanium alloy). The implants were kept in function for either 32 weeks (fully porous-coated) or 73 to 77 weeks (partially porous-coated and threaded). The studies indicated that some crestal bone loss occurred for both the threaded and partially porous-coated implants while no significant bone loss was seen with fully porous-coated implants in the absence of plaque-associated infection. It is suggested that these observed differences are a result of the different stress states that develop in bone surrounding the three designs underlying the importance of implant design on bone remodeling.

Periotest: an objective clinical diagnosis of bone apposition toward implants.

Abstract: Implant mobility as an indicator of failing close bone apposition is generally known. Whereas a clearly visible mobility can always be correlated with an interposition of soft tissue, the range from a clinically firm implant to just tangible implant mobility represents the actual problem zone. Thirty consecutive patients who had mandibles restored with osseointegrated implants ad modum Branemark were tested with the Periotest device for damping characteristics of the implants and the peri-implant tissues as a whole. The mean Periotest value (PTV) was -1.74. The characteristics of the mandible, the peri-implant tissue, and the abutment length are the determining factors for the PTV. Fixture length, dolder bar, and length of time in function had no significant influence on the PTV.

Criteria for success of osseointegrated endosseous implants

Abstract: Because of the proliferation of implant systems, a set of criteria for implant success based on scientific investigations is essential. A review of the literature and the analysis of the results indicate that six criteria are supported as valid for determining the clinical success of endosseous dental implants. These criteria are proposed for use in clinical investigation on implants.

Periodontal aspects of osseointegrated fixtures supporting an overdenture. A 4-year retrospective study.

Abstract: 196 Branemark implants in 86 consecutive patients rehabilitated by means of overdentures (6 upper jaws, 80 lower jaws) were observed longitudinally. In each jaw, only 2 implants were used to anchor the overdenture. 2 implants in the lower jaw showed some mobility at the abutment installation and were removed immediately. During the loading period (mean loading time 19.1 months ranging from 4 to 48 months), none of the implants showed any signs of non-integration. The marginal tissue reaction and plaque accumulation were monitored using conventional indices. Clinical methods and standardized radiographs were used to evaluate the bone level and density. The numbers of approximal surfaces without plaque (40%) or with gingival inflammation (55%) were almost constant throughout the study. The probing pocket depths remained within the range of 2.7 to 3.2 mm during the observation time, whereas the distance of the gingival margin from the top of the abutment clearly increased (from 1.8 to 2.9 mm). For loaded lower jaw implants connected to each other with a straight bar, a radiographic bone loss of 0.8 mm was observed during the first postsurgical year followed by a mean annual bone loss of less than 0.1 mm. For the "sleeping" fixtures, 50% less bone loss was recorded. For loaded but not interconnected implants in the upper jaw, the bone loss during the first 6 months reached 2.0 mm. The loss in marginal bone height did not clearly correlate with parameters such as the plaque index, the gingivitis index, the presence or absence of gingiva around the abutment, or the implant length. The present data, with an observation time up to 4 years, showed that the failure rate for Branemark implants supporting overdentures in the lower jaw can be limited to 1%. However, the use of 2 unconnected fixtures in the upper jaw cannot presently be advocated since considerable bone loss was observed.

The reliability of pocket probing around screw-type implants

Abstract: This study involved 108 patients (age 38-82 years) rehabilitated with overdentures in the lower jaw supported by 2 endosseous screw-shaped implants. At each follow-up visit, the clinical attachment level (PAL) around the implants was assessed with a Merrit-B probe or a constant force electronic probe, Peri-probe, and biannually parallel long-cone radiographs were taken to locate the marginal bone level. These data were used to examine the relationship between bone and attachment level estimations around implants. As a mean, bone level and PAL, for mesial and distal sites, was 0.67 and 0.61 for the Merrit-B probe, and 0.76 and 0.65, respectively for the Peri-probe. The highest correlations were obtained for sites with a healthy gingiva or in absence of intra-bony craters. Duplicate PAL registrations showed a standard deviation for the intra-examiner variability of 2.37 (Peri-probe) or 0.40 mm (Merrit-B probe) with more than 90% of the variation within 0.5 mm. The mean difference in PAL between Merrit-B probe or Peri-probe was 0.05 mm. It was concluded that the clinical attachment level determination is a reliable indicator for bone level around implants with a moderate healthy gingiva.

Structure of the bone-titanium interface in retrieved clinical oral implants.

Abstract: 7 clinically stable, "osseointegrated", titanium implants, inserted in human jaws for 1-16 years, were retrieved for morphological analysis of the bone-titanium interface, using 3 different preparation techniques. The bone-titanium interface varied as judged from light microscopy of ground sections. The threads of the implants were well filled (79-95%) with dense lamellar bone as quantified with morphometry. A large fraction of the implant surface (56-85%) appeared to be in direct contact with the mineralized bone. In general, the non-bone areas consisted of pockets with osteocytes, bone marrow tissue and/or vessels. Sections were prepared for light microscopy and transmission electron microscopy using a fracture technique, where the implant was separated from the embedded tissue before sectioning, and an electropolishing technique, where the bulk part of the implant was electrochemically removed. In areas judged as direct mineralized bone-titanium contact in the light microscope, the interfacial structure varied at the ultrastructural level. In areas along the interface, unmineralized tissue was present either as a narrow 0.5-1 micron wide zone containing collagen fibril or as deeper pockets containing osteocytes or vessels. In areas with mineralized bone contact, an amorphous granular layer (100-400 nm wide) with no mineral was observed in the innermost interface bordering the mineralized bone, with an electron-dense lamina limitans-like line (approximately 50 nm thick). It is concluded that the bone-titanium interface of the 7 clinically retrieved titanium oral implants examined in the present study bone was heterogenous. In areas of a direct mineralized bone-titanium contact at the ultrastructural level, mineralized bone reached close to the implant surface, but was separated by an amorphous layer, being 100-400 nm thick.

Bonding of hydroxyapatite-coated femoral prostheses. Histopathology of specimens from four cases.

Abstract: We examined specimens of hydroxyapatite-coated femoral prostheses from four patients who had died within nine months of implantation for fractured neck of femur. Histology showed newly formed immature bone overlying the hydroxyapatite coating with new trabeculae bridging to the endosteal bone layer. In the diaphysis, where there had been contact between the hydroxyapatite and the cortex, there was dense, firmly anchored bone with an haversian architecture. In other places the newly formed bone had a trabecular structure, containing bone marrow tissue with normal cellularity. It appeared that biological osseointegration had taken place.

In vivo load measurements on osseointegrated implants supporting fixed or removable prostheses: a comparative pilot study.

Abstract: Load was measured in vivo on a single terminal abutment cylinder by means of a strain gauge technique. The clinical measurements were made on one female patient (age 62) provided with six implants in the edentulous maxilla. A fixed prosthesis was tested initially, followed by an overdenture supported by a bar connected to the implants. The results indicated that a significant force could be introduced when connecting the framework. Furthermore, measurements showed that compression/tension forces were lower in the overdenture situation. However, the preliminary data also indicated relatively higher bending moments on the implant when the overdenture was loaded.

The concept of osseointegration and bone matrix expression.

Abstract: Osseointegration has been defined as the direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant. To date, this concept has been described by descriptive histological and ultrastructural criteria but not by biochemical means. This review evaluates the basic science work performed on this concept and then applies the concept to the principle of osseous healing. Specific studies are cited where alterations in the healing response are due to clinical management of implant placement and how studies of surface properties may lead to further insights on implant design and prognosis. In addition, a review of bone expression as a function of in vitro stress applications is given. This is followed by an indepth review of the collagens and noncollagenous proteins, described to date, within isolated bone matrix. It is this collagenous matrix (especially type I) that is described as being close to and oriented with a glycoprotein component next to the implant surface. In turn, the large family of noncollagenous proteins are important in mediating bone proliferation, matrix accumulation, orientation, mineralization, and turnover. This section is followed by a discussion of specific growth factors as they may relate to osseous healing around an implant.

Histomorphometric studies of hydroxylapatite-coated and uncoated CP titanium threaded implants in bone.

Abstract: Threaded hydroxylapatite-coated implants of commercially pure (CP) titanium were inserted in the rabbit tibial metaphysis. Uncoated CP titanium screw implants inserted in the contralateral leg served as controls. After 6 weeks and 1 year postinsertion, the semiloaded implants were histomorphometrically analyzed. While not significant, there was more direct bony contact with the hydroxylapatite-coated implants after 6 weeks of follow-up. One year after insertion, there was significantly more direct bone-to-implant contact with the uncoated CP titanium controls.

Fixation of titanium and hydroxyapatitecoated implants in arthritic osteopenic bone

Abstract: Retrieval studies of porous-coated prostheses have demonstrated deficient bony ingrowth in high percentages. Possible reasons for this are lack of initial mechanical stability and the presence of osteopenia. The authors studied ingrowth of osteopenic bone into titanium alloy (Ti) porous-coated implants with and without hydroxyapatite (HA) coating in an experimental dog model. Unilateral osteopenia of the knee with a 20% reduced bone density as judged by computed tomography (CT) scanning ( P

Guided tissue regeneration ensures osseointegration of dental implants placed into extraction sockets. An experimental study in monkeys.

Abstract: The aim of the present study was to explore the possibility of achieving osseointegration of dental titanium implants, inserted into alveoli immediately after tooth extraction, by covering the recipient site with a teflon membrane In each of 7 monkeys, mucoperiosteal flaps were raised on the buccal and palatal aspects of the maxillary molars in both sides of the jaw The second molars were then extracted and self tapping titanium implants of the screw type (Astra® Dental Implants) were inserted into the sockets of the largest roots In the coronal portion of the sockets, a void was always present between the implant and the socket walls In one side of the jaw, a membrane (Gore-;Tex Aug-mentation Material@) was adjusted to cover the implant The implant in the other side of the jaw served as control and was only covered by the tissue flaps Microscopic analysis after 3 months of healing revealed that soft tissue was facing the coronal portion of the implants to a varying degree in the control side, while osseointegration was consistently observed to the top of the membrane-covered implants which remained submerged throughout the experimental period The results suggest that the membrane techniaue can secure complete osseointegration of implants inserted immediately into extraction sockets

Angulated abutment for osseointegrated implants

Abstract: An angulated abutment system for affixing a dental prosthesis to an anchor implanted in the jaw bone such that the dental prosthesis can be mounted axially offset from the axis of the implant. Two components of the abutment system are designed in such a manner to allow the dental prosthesis to be adjusted in small angles of rotation.

Clinical and microbiological findings on newly inserted hydroxyapatite-coated and pure titanium human dental implants.

Abstract: The clinical and microbiologic features of 30 hydroxyapatite-coated root-form endosseous dental implants (Tri-Stage) were compared to 10 similar pure titanium implants without hydroxyapatite coatings. In 7 of 9 partially edentulous patients studied, pure titanium fixtures were placed adjacent to hydroxyapatite-coated implants. Implants in the maxilla were submerged beneath mucosal tissues after implant placement for a minimum of 6 months, and in the mandible for at least 4 months. All patients were prescribed short-term beta-lactam antibiotic therapy after fixture placement, and 8 of 9 used chlorhexidine mouthrinses after fixture exposure. Clinical and microbiological examination was carried out 7-10 months after fixed prosthetic loading of the implants. Clinical measurements included the gingival index, plaque index, bleeding on probing and peri-implant probing depths determined with the Florida Probe system. Subgingival microbial samples were collected with paper points and transported in VMGA III. Specimens were examined by direct phase-contrast microscopy and were plated onto nonselective and selective culture media for anaerobic and aerobic incubation. No significant mean clinical or microbiological differences were found between the implant types, although one hydroxyapatite-coated implant exhibited deep probing depths, bleeding on probing and marked radiographic crestal bone loss. Streptococcus sanguis and Streptococcus mitis were the most predominant organisms recovered from clinically stable implants, whereas high proportions of Fusobacterium species and Peptostreptococcus prevotii were isolated from the ailing hydroxyapatite-coated implant. One or more implants in 8 of the study subjects yielded enteric rods, pseudomonads, enterococci or staphylococci. The prognosis of implants with varying early microbiotas needs to be established in longitudinal studies.

Mandibular deformation in subjects with osseointegrated implants.

Abstract: Relative movement and force transmission between osseointegrated (OI) implants in the premolar regions of the edentulous mandible have been measured using intraoral transducers linked to OI implants. These have shown deformations of up to 420 microns and force transmission of up to 16 N as a result of jaw movement from the rest position. Greater displacements and forces were observed in active opening and protrusion than in lateral excursions. There were wide variations from subject to subject, and while the effects of these phenomena are not known, they may be potentially harmful to the interfaces between the implants and bone and the various components of the implant superstructure.

Clinical Comparison of Hydroxyapatite-Coated Titanium Dental Implants Placed in Fresh Extraction Sockets and Healed Sites

Abstract: The placement of hydroxyapatite-coated dental implants in fresh extraction sockets was compared to placement in adjacent healed sites in 14 patients. Systematic sequential documentation was obtained regarding periodontal health, radiographic bone levels, and implant stability at the time of implant placement, at uncovering, and from 8 to 24 months (mean 16 months) after loading and restoration delivery. There were no significant differences in any clinical parameter between those implants placed in fresh extraction sockets and those placed in healed areas. Periodontal health, maintenance of crestal bone levels, and implant stability were excellent for implants placed in both types of recipient sites. The results of this study suggest that hydroxyapatite-coated dental implants can be successfully placed in fresh extraction sockets utilizing otherwise standard implant placement techniques, and that they appear to clinically perform equally well in fresh sockets and healed sites. J Periodontol 1991; 62:468–472.

The Effect of Partial Coating with Hydroxyapatite on Bone Remodeling in Relation to Porous-coated Titanium-alloy Dental Implants in the Dog

Abstract: For inhibition of crestal bone resorption due to stress shielding and disuse atrophy, an hydroxyapatite (HA) plasma coating was added to the coronal portion of partially porous-coated endosseous dental implants. These implants, as well as control non-HA-coated implants were placed in healed mandibular premolar extraction sites in dogs for a 72-week period of function. Histological examination showed that both implant designs became securely fixed by bone ingrowth into the porous-coated apical region of the implants. The plasma-sprayed HA coating resulted in significantly greater bone height formation and maintenance next to the coronal portion of the implant compared with non-HA-coated implants of similar design. In addition, significant resorption of the 20-to-50-microns-thick plasma-sprayed HA coating occurred over the 18-month period of function.

Immediate implantation of a pure titanium implant into an extraction socket: report of a pilot procedure.

Abstract: The conventional osseointegration protocol calls for waiting up to 12 months for ossification of an extraction socket to heal before placing an endosseous implant. In this study the possibility of placing a pure titanium implant directly into an extraction socket immediately after extraction was investigated. A pure titanium Nobelpharma 10-mm implant was placed into a central incisor extraction socket of a stump-tailed monkey and allowed to heal for a period of 6 months, followed by functional loading of the implant. The implant was osseointegrated on a clinical and histological level. This pilot study suggests that pure titanium implants have the potential to integrate when placed immediately after extraction of the teeth and warrants further investigation.