Titanium Fixtures Research Articles

Osseointegrated proximal interphalangeal joint prostheses with a replaceable flexible joint spacer--long-term results.

Osseointegrated proximal interphalangeal joint prostheses with a replaceable joint spacer were used in 25 joints in 19 patients (five men and 14 women) aged 45 (16-67) years. Indications for surgery were post-traumatic arthrosis (nine joints in eight patients), primary osteoarthrosis (10 joints in eight patients), and rheumatoid arthritis (six joints in three patients). A silicone joint spacer was attached to titanium fixtures by short titanium stems that extended from the spacer and fitted into a central canal in the screws. The arthroplasty was done in one stage, which included resection of the joint followed by grafting of marrow and cancellous bone from the iliac crest into adjacent medullary cavities before insertion of the titanium fixture. Follow up at 8.5 (5-11) years showed that 47 out of 50 fixtures (94%) had successfully osseointegrated while 17 of 25 joint spacers (68%) had fractured. However, because of the design of the prostheses fractured joint spacers could easily be replaced and a new spacer could be connected to already osseointegrated screws. The joint spacer was replaced in 11 fingers once or several times. Range of movement (ROM) in the whole series (four fusions excluded) was 41 (0-85) degrees with an extension defect of 15 (0-55) degrees. In eight joints with permanently intact joint spacers the ROM was 39 (0-60) degrees with extension defects of 16 (0-40) degrees. In six joints in which the spacer was replaced once the ROM was 43 (0-85) degrees with an extension defect of 16 (0-55) degrees. Our data confirm good long-term osseointegration of titanium fixtures and that a joint spacer, if needed, can be replaced by a new spacer that can be attached to already osseointegrated screws without jeopardizing the ROM.

Resolution of peri-implantitis following treatment. An experimental study in the dog.

The aim of the present experiment was i) to study the effect of anti-microbial therapy of experimentally induced peri-implantitis lesions and ii) to assess features of bone regrowth following treatment. Four beagle dogs were used. Three titanium fixtures (Brånemark System) were installed in each quadrant of the mandible (premolars previously extracted). Abutment connection was performed 5 months later and ligature induced breakdown was initiated. The ligatures were removed when approximately 50% of the initial bone support was lost. A 3-week antibiotic regimen (amoxicillin and metronidazole) was initiated 1 month later. Two days after the start of the antibiotic administration, the experimental implant sites were exposed to local therapy. The abutments were removed and the exposed fixture surfaces were treated with an abrasive (pumice) administered via a rotating brush (left side) or cleaned with cotton pellets soaked in saline (right side). Cover screws were attached to the fixtures and the implants were submerged. Fluorochromes were injected intravenously 2 weeks, 4 weeks and 12 weeks after surgery. The animals were killed 7 months after surgery and block biopsies of each implant site were dissected and prepared for histological analysis. The findings of the examinations disclosed that the inflammatory lesion was resolved and new bone formation had occurred in the previous defect following antimicrobial and local therapy. The amount of "re-osseointegration" that had taken place, however, was small. Indeed, at all experimental implant sites, a thin connective tissue capsule was found to separate the implant surface from the newly formed bone.

Bone response to orthodontic loading of endosseous implants in the rabbit calvaria: early continuous distalizing forces.

The purpose of this experimental study was to evaluate the effect of early orthodontic loading on the stability and bone-implant interface of titanium implants in a rabbit model. Twenty-four short threaded titanium fixtures were inserted in the calvarial mid-sagittal suture of 10 rabbits. Two weeks following insertion, 20 implants (test group) were subjected to continuous distalization forces of 150 g for a period of 8 weeks. The remaining four implants (control group) were left unloaded for the same follow-up interval. Clinically, all implants except for one test fixture were stable, and exhibited no mobility or displacement throughout the experimental loading period. Histologically, all stable implants were well-integrated into bone. No differences could be found between the pressure and tension surfaces of the test implants relative to bone quality and density within a range of 1000 microns from the fixture surface. Similarly, qualitative differences were not observed between the apical and coronal portions of test fixtures. Morphometrically, a mean percentage bone-to-implant contact of 76.00 +/- 18.73 per cent was found at the test pressure sides, 75.00 +/- 11.54 per cent at the test tension sides, and 68.00 +/- 15.55 per cent at the control unloaded surfaces. No statistically significant differences in the percentage of bone-to-metal contact length fraction were found between test pressure surfaces, test tension surfaces, and unloaded control surfaces. Marginal bone resorption around the implant collar or immediately beneath it was found in roughly the same percentage of analysed sites in the test and control fixtures. In contrast, slight bone apposition was demonstrated at the implant collar of the test pressure surfaces, while no apposition or resorption were observed in the test tension zones. This study suggests that short endosseous implants can be used as anchoring units for orthodontic tooth movement early in the post-insertion healing period.

Early results with osseointegrated proximal interphalangeal joint prostheses.

Osseointegrated endoprostheses were used in 22 proximal interphalangeal joint replacements in 12 patients between 1993 and 1995. Indications for surgery were joint destruction due to rheumatoid arthritis (13 joints), primary osteoarthrosis (7 joints), posttraumatic arthrosis (1 joint), and psoriatic arthritis (1 joint). The prostheses consisted of 2 screw-shaped titanium fixtures with a flexible silicone spacer. The 1-stage surgical procedure included joint resection and cancellous bone grafting from the iliac crest before insertion of the titanium fixtures. At a follow-up examination 27 months (range, 12-37 months) after surgery, the average active range of motion was 56 degrees (20 degrees to 80 degrees) with an extension lag of 11 degrees (-5 degrees to 45 degrees), corresponding to an average arc of motion of from 11 degrees to 67 degrees flexion. Radiographs indicated that 41 of 44 fixtures were osseointegrated. Four of the 22 joint mechanisms showed fracture of the silicone spacer; deformation of the silicone was noted in an additional 27%. Patient satisfaction was high (20 of 22 joints), with significantly improved range of motion and hand function, increased grip strength, good pain relief, and satisfactory appearance. The results of this study indicate good early clinical findings using osseointegrated implants for proximal interphalangeal joint replacement but also show the need for further development regarding the durability of the flexible silicone joint spacer.

Osseointegrated silicone implants. 18 patients with 57 MCP joints followed for 2 years.

20 patients were operated on consecutively with osseointegrated MCP joint prostheses in 64 joints at our department between September 1993 and February 1995. The one-stage procedure included joint resection and cancellous bone grafting from the iliac crest before insertion of screw-shaped titanium fixtures, connected with a flexible silicone spacer. 18 patients (57 joints) were clinically and radiographically examined at median 28 (18-37) months postoperatively. Indications for surgery were joint destruction due to chronic arthritis in 17 patients (56 joints), and posttraumatic arthrosis in 1 patient (1 joint). Postoperative median range of motion was 40 (15-85) degrees, with an extension deficit of 30 (-20-70) degrees. 16 patients were satisfied, and had good pain relief and substantially improved postoperative hand function, evaluated with the standardized Sollerman hand function test. Radiographic osseointegration was obtained in 112 of 114 titanium fixtures (98%), but fracture of the silicone spacer was observed in 14 implants (25%). We conclude that osseointegration of longitudinal titanium fixtures in the bone marrow canal is possible in a one-stage procedure, but our findings show the need for a new, more durable joint spacer.

The use of a conical fixture design for fixed partial prostheses. A preliminary report.

A specially designed, TiO2-blasted titanium fixture, partially conical and microthreaded, the Astra Tech Fixture ST, was used for rehabilitation of partial edentulism in the posterior mandible. Superior to the mandibular canal 25 fixtures were placed in 10 patients. Fixed metal-ceramic bridges were then performed. After 1-year follow-up, all bridges were found to be clinically stable. The implant survival rate was 100% and the mean marginal bone resorption was 0.05 +/- 0.11 mm.

Clinical and radiographic evaluation, following delivery of fixed reconstructions, at GBR treated titanium fixtures.

Conditions following incorporation of fixed reconstructions, at endosseous titanium implants augmented at local bony dehiscence and fenestration defects using a bioabsorbable Resolut membrane were studied in 7 patients. Fixture stability, radiographic marginal bone levels and peri-implant soft tissue status were evaluated at 21 membrane treated and 17 control fixtures (installed in regions of adequate bone volume), following a 2-year period of functional loading. Prosthetic reconstructions were removed and clinical examination and Periotest values revealed that all fixtures were stable. All peri-implant soft tissues were clinically healthy. The mean probing depths at buccal sites for fixtures with original dehiscence (n = 10) and fenestration (n = 11) defects were 1.6 +/- 0.7 mm and 1.2 +/- 0.4 mm respectively. The control fixture group had a mean buccal probing depth of 1.4 +/- 0.6 mm. At abutment connection radiograph membrane treated fixtures had significantly lower marginal bone levels than control fixtures, indicating that optimal bone regeneration was not achieved at all defects. Mean radiographic bone loss 23-27 months following delivery of fixed reconstructions for original dehiscence and fenestration defect fixtures was 0.7 +/- 0.8 mm and 0.8 +/- 0.6 mm respectively at mesial surfaces, and 0.8 +/- 0.7 mm and 0.6 +/- 0.5 mm at distal surfaces. In the control fixture group a mean loss of 0.7 +/- 0.5 mm at mesial surfaces and 0.5 +/- 0.4 mm at distal surfaces was found. Results showed no significant difference in the rate of bone loss following functional loading between membrane treated and control fixtures.

Biomechanical characterization of osseointegration: an experimental in vivo investigation in the beagle dog.

This study reports the results of torsion tests, pull-out tests, and lateral loading tests on osseointegrated commercially pure titanium fixtures. The tests were performed in vivo on six beagle dogs. Three fixtures, each with a diameter of 3.7 mm, were installed bilaterally in the tibia of each animal. The mean maximal pull-out load was 1.55 kN (n = 4), the mean maximal lateral transverse load was 0.21 kN (n = 2), the mean maximal lateral axial load was 0.18 kN (n = 2), the mean breakpoint torque was 0.31 Nm (n = 3), and the mean maximal torque was 0.43 Nm (n = 3). The torsion test revealed an almost immediate plastic deformation of the interface between the implant and bone; this indicates that although the contact between the bone and the implant is close, there is no strong bond, at least not in shear. The major transfer of load from the implant to the surrounding bone tissue must therefore depend on the design of the implant. A histological evaluation with measurements of the amount of bone in contact with the fixtures was performed. By the use of the histological and mechanical data, it is possible to estimate shear stresses in bone tissue (pull-out test) and in the interface (torque test). The mean maximal shear stress in bone tissue in the pull-out tests was 100 MPa (n = 4); the mean shear stress in the interface was 4.3 MPa (n = 3) in the torsion tests at the breakpoint torque and was 6.0 MPa (n = 3) at the maximal torque. It was also possible to estimate the shear modulus of elasticity in the pull-out and torque tests. The mean shear modulus in pull-out was 119 MPa (n = 4), and the mean apparent shear modulus in torsion was 9 kPa (n = 3) for an assumed interface thickness of 100 nm and was 86 kPa (n = 3) for an assumed interface thickness of 1,000 nm.

Bone morphogenetic protein-2 for peri-implant bone regeneration and osseointegration.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) induced bone regeneration and osseointegration was evaluated in supraalveolar peri-implant defects in 5 beagle dogs. Alveolar bone was reduced 5 mm in height in mandibular premolar areas and the premolars were extracted. Three 10 mm titanium fixtures were placed 5 mm into each reduced alveolar crest, leaving 5 mm in a supraalveolar position. Alternate quadrants in consecutive animals received a surgical implant consisting of 2 ml rhBMP-2 (0.43 mg/ml) in a type I bovine collagen carrier, or the carrier alone (control). Fixtures and surgical implants were submerged under the gingival flaps. The healing interval was 16 weeks. Histometric and radiographic evaluations were made. Defect height averaged (+/- SD) 5.3 +/- 0.2 and 5.1 +/- 0.2 mm for rhBMP-2 and control defects, respectively (P > 0.05, n = 5, paired, t-test) Bone regeneration (height) averaged 4.2 +/- 1.0 and 0.5 +/- 0.3 mm for rhBMP-2 and control defects, respectively (P < 0.05). Bone regeneration (area) averaged 6.1 +/- 6.3 and 0.2 +/- 0.2 mm2 for rhBMP-2 and control defects, respectively (P > 0.05). Osseointegration within the confines of the defect averaged 19.1 +/- 10.1% and 8.2 +/- 4.6% for rhBMP-2 and control defects, respectively (P > 0.05). Osseointegration within regenerated bone averaged 29.1 +/- 9.8% and 65.3 +/- 15.3% for rhBMP-2 and control defects, respectively (P < 0.05). Osseointegration within the retained alveolar bone averaged 67.1 +/- 4.6% and 68.1 +/- 3.6% for rhBMP-2 and control defects, respectively (P > 0.05). The results suggest that there is a potential for rhBMP-2 induced bone regeneration and osseointegration in surgical peri-implant defects.

Biomechanical characterization of osseointegration during healing: an experimental in vivo study in the rat

This study reports torsion tests and pull-out tests on osseointegrated commercially pure titanium fixtures. The tests were performed in vivo on a total of 26 rats. Three fixtures with a diameter of 2.0 mm were installed bilaterally in the proximal tibia in each animal. The mechanical testing was performed immediately after installation, after 2, 4, 8 and 16 weeks of unloaded healing. The torsional strength started to increase after 4 weeks of unloaded healing and there was a significant increase with time during the initial 16 weeks. The pull-out load increased rapidly during the first 4 weeks; thereafter, a moderate increase occurred during the following 12 weeks. A histological evaluation was performed after 0, 4, 8 and 16 weeks. There were significant ( P < 0.01) correlations between torque and percentage of bone in contact with the fixture, and between pull-out load and the bone thickness around the fixture ( P < 0.001). Estimations of shear stresses and shear moduli in the bone tissue (pull-out test) and at the interface (torque test) indicated that the increase in bone volume around the implant substantially improved the mechanical capacity.

Guided bone regeneration in dental implant treatment using a bioabsorbable membrane.

The aim of this study was to evaluate an osteopromotive technique, using a bioabsorbable membrane, for its ability to restitute bone over buccal fenestration and dehiscence defects following fixture installation. 11 patients requiring dental implant treatment and exhibiting sufficient vertical height of the maxilla and compromised bucco-palatal dimensions, as determined clinically and radiographically, were included in the study. 17 Brånemark titanium fixtures were placed with buccal defects which were augmented by a bioabsorbable membrane, Resolut. No complications were observed post-operatively. At 6-8 months, abutment connection was performed, and clinical evaluation of the healed defect area was made. The number of exposed buccal threads at fixture installation (median 8; range 2-19), and abutment connection (median 0; range 0-5), respectively, was compared. Out of the 17 fixtures; 14 exhibited complete coverage with bone, whereas 3 showed some remaining threads. A small punch biopsy taken at abutment connection in an area where the membrane had been placed showed a combination of dense connective tissue and bone. Radiographic evaluation of the marginal periimplant bone level is in progress and results to date show a median bone loss of 1.2 mm after a loading period of 4-6 months. Results show that fixture dehiscence and fenestrations, augmented with this bioabsorbable membrane, demonstrate a highly significant amount of new bone formation.

Healing at implants with and without primary bone contact. An experimental study in dogs.

The aim of the present investigation in the dog was to study: (i) if it was possible by the use of EREt to predictably expand the compromised alveolar ridge; (ii) if proper osseointegration also occurred at sites where the implant following installation was devoid of direct bone contact. 5 beagle dogs, about 1-year old, were included in the study. During a preparatory period, the mandibular premolars were extracted and the ridge in the edentulous regions markedly reduced. After 3 months of healing, ridge expansion surgery was performed. A partial thickness flap was raised on the buccal and lingual surfaces for the soft tissue preparation. The buccal part of the ridge was mobilised and the bone plate with its periosteum displaced in the buccal direction. In each quadrant, 2 fixture sites were prepared in the mandibular bone apical of the displaced bone plate. 2 unthreaded titanium plasma sprayed fixtures were installed in such a way that the coronal border of the fixture was flush with the level of the lingual and buccal bone plate. The "internal" distance between the mobile buccal and the non-mobile lingual bone plates was identical to the diameter of the fixtures, i.e., 3.3 mm, while the distance between the mesial and distal borders of the 2 implants and the mesial or distal bone was > 5 mm. In each quadrant, 1 additional fixture was installed in the non- reduced mesial part of the alveolar ridge (control site). 3 months after fixture installation, abutment connection was performed. Following abutment connection, a plaque control program was initiated and maintained for 4 months, at which time, the dogs were re-examined and biopsies obtained for histological examination. It was observed that bone regeneration and osseointegration may occur to titanium fixtures placed in surgically-created bone defects. The amount of bone that was in intimate contact with the fixture surface was similar in test and control sites. In addition, the periimplant mucosa at test and control implants had similar dimensions and composition in terms of junctional epithelium and connective tissue.

Guided bone regeneration in the treatment of periimplantitis.

The objective of the present experiment was to study the soft and hard tissue healing following treatment of experimentally induced periimplantitis. 5 labrador dogs about 1-year old were used. The mandibular right and left 1st molars, 4th and 3rd premolars were removed, titanium fixtures (Brånemark System) were installed, and standard abutments were connected in a 2nd stage procedure. After 3 months experimental periimplantitis was induced by the placement of cotton floss ligatures in a submarginal position. 6 weeks later the ligatures were removed. 1 month after ligature removal, an antibiotic regimen was initiated. During a 3-week period, each dog was given tablets of amoxicillin and metronidazole. In the left side of the mandible, buccal and lingual mucoperiosteal flaps were elevated and granulation tissue within the bone craters curetted. The abutments were removed. The exposed outer surfaces and the internal part of the fixtures were carefully cleaned with a detergent (delmopinol HC1). An e-PTFE membrane was placed over each fixture and adjusted to cover the bone crater. New cover screws were fitted through the membranes to the cleaned fixtures. The implants were submerged and the flaps sutured. In the right side of the mandible no local treatment was performed. The dogs were sacrificed after 4 months and biopsies prepared for histological examination. The findings indicated that treatment of a periimplantitis lesion, including comprehensive systemic antimicrobial therapy and cleaning of submerged implants resulted in (i) the elimination of the inflammatory process in the periimplant tissues and (ii) the establishment of a dense connective tissue capsule in direct contact with the previously exposed surface of the implant system. It was also observed that (iii) new bone was frequently laid down on the pristine cover screws.

The effect of antimicrobial theram on peri‐implantitis lesions. An experimental study in the dog.

The objective of the present study was to evaluate the effect of systemic antibiotics and local debridement in the treatment of experimentally induced periimplantitis lesions. 5 Labrador dogs, and about 1-year old, were included in the study. In order to establish bilateral recipient sites for implants the mandibular right and left 1st molars, 4th and 3rd premolars were removed. 6 titanium fixtures (Brånemark System Nobelpharma AB, Göteborg, Sweden) were installed and standard abutments were connected 3 months after fixture installation. Cotton floss ligatures were placed in a submarginal position around the neck of the abutments and the animals were placed on a diet which allowed plaque accumulation. After 6-8 weeks, when the tissue destruction amounted to about 20% of the fixture length, the ligatures were removed. 1 month after ligature removal, an antibiotic regimen (amoxicillin and metronidazole) was initiated and maintained for 3 weeks. In the left side of the mandible, buccal and lingual mucoperiosteal flaps were elevated, the granulation tissue within the bone craters adjacent to the implants was curetted, and the abutments were removed. The exposed outer surface, the internal part of the fixtures, as well as the abutments were treated with a detergent, delmopinol. The cleaned abutments were autoclaved, and connected to the clean fixtures. The mucoperiosteal flaps were replaced to their original position, adapted to the abutments and sutured. A careful plaque control program was initiated for the left jaw quadrants. In the right side of the mandible no local treatment was given to the fixtures and the abutments following ligature removal. Furthermore, no plaque control was provided to the implant segments in the right jaws. After 4 months of healing block biopsies including one implant with adjacent hard and soft tissue were harvested and prepared for light microscopy. It was observed that systemic antimicrobial therapy, combined with implant cleaning, curettage of the bone defect and regular plaque control resulted in (i) resolution of the periimplantitis lesion, (ii) a significant recession of the marginal periimplant mucosa, and (iii) a minor additional apical shift of the base of the bone defect. In the untreated sites the plaque associated infiltrate remained and was in several sites examined in contact with the adjacent bone tissue.

Linearity of sound transmission through the human skull in vivo

The linearity of sound propagation through the human skull was investigated. One male subject, equipped with bilateral skin-penetrating titanium fixtures for attachment of bone-anchored hearing aids, was studied thoroughly. Three different methods were used: comparison of the frequency response functions estimated at different signal levels (using stepped sine as well as random noise), comparison of the coherence function at different signal levels (using random noise), and the Hilbert transform of the estimated frequency response function. Frequencies from 0.1 to 10 kHz and signal levels up to 77 dB HL at discrete frequencies were used. No indication of any significant nonlinear behavior was found with the three methods used.

Osseointegrated thumb prostheses: A concept for fixation of digit prosthetic devices

Three patients with traumatic amputation of the thumb at the metacarpophalangeal joint level underwent a two-stage reconstruction aimed at fixation of a thumb prosthesis to the first metacarpal bone via an osseointegrated titanium fixture. The first stage included insertion of the fixture into the medullary cavity of the first metacarpal bone in combination with transplantation of cancellous bone from the iliac crest. After 3 months, when the fixture was firmly osseointegrated into the bone, a skin-penetrating abutment was placed on top of the fixture, the surrounding skin being thinned to the thickness of a split-skin graft to minimize relative mobility. A thumb prosthesis could then be firmly attached to this fixture. At follow-up examinations between 18 months and 3 years; postoperatively perfect osseointegration of the implant persisted. There were no skin problems. Some extent of tactile discrimination was achieved in the prosthesis hypothetically based on transfer of tactile stimuli to endosteal nerves in the bone via the titanium fixture.

The periodontal ligament of teeth connected to osseointegrated implants. An experimental study in the beagle dog

Abstract The aim of the present investigation was to analyze the periodontal tissues at immobilized teeth connected to osseointegrated implants. 10, 1-year old beagle dogs, were used. Bilaterally, the mandibular 2nd (2P2) and 3rd pre-molars (3P3) and 1st molars (1M1) were extracted. 2 titanium fixtures were installed in the edentulous segment of the right side of the mandible, one about 10 mm mesial and the other about 10 mm distal to 4P (test tooth). 3 months later, abutment connection was performed and healing allowed for one month. The dogs were randomly divided into 2 groups of 5 each, group A and group B. In group A, a fixed gold splint, rigidly connecting the tooth and the 2 implants, was installed on day 0 and 4P was hereby immobilized. The controlateral 4th premolar (P4) served as the non-splinted control tooth. Plaque control measures continued until the end of the experiment (day 180). In group B, plaque control measures were abandoned 1 month after abutment connection and a 4-month period of experimental periodontal tissue breakdown was initiated. This was accomplished by placing cotton floss ligatures submarginally around 4P and P4. At the end of this 4-month period, the ligatures were removed, and an apically positioned flap procedure was performed. Healing was allowed for another 2 months. Plaque control measures were re-established and continued throughout the experiment. A given day was termed day 0 and 4P was rigidly connected to the adjacent implants in the manner described for group A. At the end of a subsequent 6-month period, radiographs of 4P and P4 were taken and biopsies harvested from all the dogs. The results of measurements, made in histological sections, revealed that the splinting of mandibular premolars to osseointegrated implants failed to induce marked alterations (qualitative and quantitative) in the gingiva and periodontal tissues of the immobilized teeth. These findings offer a biological explanation for the fact that a fixed bridge, utilizing both teeth and implants as abutments, seems to function well in the rehabilitation of partially edentulous patients.

Resolution of ligature‐induced peri‐implantitis lesions in the dog

The present experiment in the Labrador dog was performed to study tissue alterations that occurred in a peri-implantitis lesion following ligature removal. The study was carried out in 5, 1-year old Labrador dogs. The mandibular right and left 1st molars and 4th and 3rd premolars were extracted to establish recipient sites for implants. After 3 months of healing, 4 titanium fixtures, 2 in each jaw quadrant, were installed and abutment connection carried out in a 2nd stage procedure after another 3 months. After a 6-month period of healing, cotton floss ligatures were placed in a submarginal position around the neck of the fixture abutments. The ligatures were forced into a position "apical" of the margin of the peri-implant mucosa and secured. When the tissue destruction after 4-6 weeks was found to amount to about 25% of the original bone height at each individual implant, the ligatures were removed. 2 dogs were sacrificed 1 month and 3 dogs 3 months after ligature removal. The animals were perfused with a fixative and block biopsies were obtained from the implant sites. The biopsies were prepared for histometric and morphometric analyses.(ABSTRACT TRUNCATED AT 250 WORDS)

The periodontal ligament of teeth connected to osseointegrated implants. An experimental study in the beagle dog.

The aim of the present investigation was to analyze the periodontal tissues at immobilized teeth connected to osseointegrated implants. 10, 1-year old beagle dogs, were used. Bilaterally, the mandibular 2nd (2P2) and 3rd premolars (3P3) and 1st molars (1M1) were extracted. 2 titanium fixtures were installed in the edentulous segment of the right side of the mandible, one about 10 mm mesial and the other about 10 mm distal to 4P (test tooth). 3 months later, abutment connection was performed and healing allowed for one month. The dogs were randomly divided into 2 groups of 5 each, group A and group B. In group A, a fixed gold splint, rigidly connecting the tooth and the 2 implants, was installed on day 0 and 4P was hereby immobilized. The controlateral 4th premolar (P4) served as the non-splinted control tooth. Plaque control measures continued until the end of the experiment (day 180). In group B, plaque control measures were abandoned 1 month after abutment connection and a 4- month period of experimental periodontal tissue breakdown was initiated. This was accomplished by placing cotton floss ligatures submarginally around 4P and P4. At the end of this 4-month period, the ligatures were removed, and an apically positioned flap procedure was performed. Healing was allowed for another 2 months. Plaque control measures were re-established and continued throughout the experiment. A given day was termed day 0 and 4P was rigidly connected to the adjacent implants in the manner described for group A.(ABSTRACT TRUNCATED AT 250 WORDS)

Osseointegration in Sinus-Forming Bone

Osseointegration, using bone-anchored titanium fixtures, is a well-established technique for both intraoral and craniofacial prosthetic rehabilitation. The use of this technique in children can be complicated by craniofacial growth and sinus development. This study evaluates the effects of sinus formation and growth on the fate of osseointegrated titanium fixtures in the growing porcine model. At 3 weeks of age, six Landrace White cross male pigs had a 3.75 x 3.0 mm titanium fixture (Noblepharma) inserted into their right frontal bone where the right frontal sinus would subsequently develop. Preoperative CT scans with three-dimensional reconstructions were used to determine the insertion site. To follow the effects of growth and sinus formation, CT scans with three-dimensional reconstructions and cephalometric radiographs were taken at 1, 3, 6, and 9 weeks postoperatively and at sacrifice. The pigs were sacrificed serially, and direct osteometric measurements were taken to determine skull symmetry. All skulls were sectioned, and osseointegration was determined clinically, radiologically, and histologically with light and scanning electron microscopy. Five of the six fixtures osseointegrated. There were no apparent growth disturbances due to the fixtures. As growth progressed, the osseointegrated fixtures submerged into the frontal bone in a posteroinferior direction to become completely intraosseous 14 weeks after insertion. As the frontal sinus pneumatized, the fixtures remained osseointegrated, but progressive amounts of the fixtures became exposed in the sinus. From this study it would appear that osseointegrated titanium fixtures do not have any effect on calvarial growth and gradually submerge into the growing bone. As sinus development ensues, the fixtures remain integrated but become partially exposed within the sinus.(ABSTRACT TRUNCATED AT 250 WORDS)