Showing papers on "Osseointegration published in 2001"

Osteoinduction, osteoconduction and osseointegration.

Abstract: Osteoinduction is the process by which osteogenesis is induced. It is a phenomenon regularly seen in any type of bone healing process. Osteoinduction implies the recruitment of immature cells and the stimulation of these cells to develop into preosteoblasts. In a bone healing situation such as a fracture, the majority of bone healing is dependent on osteoinduction. Osteoconduction means that bone grows on a surface. This phenomenon is regularly seen in the case of bone implants. Implant materials of low biocompatibility such as copper, silver and bone cement shows little or no osteoconduction. Osseointegration is the stable anchorage of an implant achieved by direct bone-to-implant contact. In craniofacial implantology, this mode of anchorage is the only one for which high success rates have been reported. Osseointegration is possible in other parts of the body, but its importance for the anchorage of major arthroplasties is under debate. Ingrowth of bone in a porous-coated prosthesis may or may not represent osseointegration.

Repair of large bone defects with the use of autologous bone marrow stromal cells.

Abstract: To the Editor: The reconstruction of large bone segments is an important clinical problem, and none of the approaches proposed thus far have proved very effective. In animals, repair and functional...

Osseointegration in skeletal reconstruction and rehabilitation: a review.

Abstract: The loosening of implants from bone tissues has been a cause of problems in reconstructive surgery and joint replacement. The thought for decades has been that the layer of fibrous tissue that develops around the implant diminishes the integrity and mechanical stability of the implant/bone interface (1). During the 1950s it had been shown by Branemark that chambers made of the metal titanium could become permanently incorporated with bone. That is, the living bone could become so fused with the titanium oxide layer of the implant that the two could not be separated without fracture (2). Branemark introduced the term “osseointegration” to describe this modality for stable fixation of titanium to bone tissue.

Influence of the size of the microgap on crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged implants in the canine mandible.

Abstract: Background: Endosseous implants can be placed according to a non-submerged or submerged approach and in 1- or 2-piece configurations. Recently, it was shown that peri-implant crestal bone changes differ significantly under such conditions and are dependent on a rough/smooth implant border in 1-piece implants and on the location of an interface (microgap) between the implant and abutment/restoration in 2-piece configurations. Several factors may influence the resultant level of the crestal bone under these conditions, including movements between implant components and the size of the microgap (interface) between the implant and abutment. However, no data are available on the impact of possible movements between these components or the impact of the size of the microgap (interface). The purpose of this study was to histometrically evaluate crestal bone changes around unloaded, 2-piece non-submerged titanium implants with 3 different microgap (interface) dimensions and between implants with components welded...

Hydroxylapatite binds more serum proteins, purified integrins, and osteoblast precursor cells than titanium or steel.

Abstract: The implant material hydroxylapatite (HA) has been shown in numerous studies to be highly biocompatible and to osseointegrate well with existing bone; however, the molecular mechanisms at work behind this osseointegration remain largely unexplored. One possibility is that the implant, exposed to the patient's blood during surgery, adsorbs known cell adhesive proteins such as fibronectin and vitronectin from the serum. Osteoblast precursors could then adhere to these proteins through integrin-mediated mechanisms. In the present study, we have used a quantitative ELISA assay to test the hypothesis that hydroxylapatite will adsorb more fibronectin and vitronectin from serum than two commonly used hard-tissue materials, commercially pure titanium, and 316L stainless steel. We further used the ELISA, as well as a standard cell adhesion assay, to test the hypothesis that increased protein adsorption will lead to better binding of purified integrins alpha5beta1 and alpha(v)beta3 and osteoblast precursor cells to the HA than to the metals. Our results show that fibronectin, vitronectin, alpha5beta1, alpha(v)beta3, and osteoblast precursor cells do indeed bind better to HA than to the metals, suggesting that improved integrin-mediated cell binding may be one of the mechanisms leading to better clinical bone integration with HA-coated implants.

The influence of static and dynamic loading on marginal bone reactions around osseointegrated implants: an animal experimental study.

Abstract: Although it is generally accepted that adverse forces can impair osseointegration, the mechanism of this complication is unknown. In this study, static and dynamic loads were applied on 10 mm long implants (Branemark System, Nobel Biocare, Sweden) installed bicortically in rabbit tibiae to investigate the bone response. Each of 10 adult New Zealand black rabbits had one statically loaded implant (with a transverse force of 29.4 N applied on a distance of 1.5 mm from the top of the implant, resulting in a bending moment of 4.4 Ncm), one dynamically loaded implant (with a transverse force of 14.7 N applied on a distance of 50 mm from the top of the implant, resulting in a bending moment of 73.5 Ncm, 2.520 cycles in total, applied with a frequency of 1 Hz), and one unloaded control implant. The loading was performed during 14 days. A numerical model was used as a guideline for the applied dynamic load. Histomorphometrical quantifications of the bone to metal contact area and bone density lateral to the implant were performed on undecalcified and toluidine blue stained sections. The histological picture was similar for statically loaded and control implants. Dense cortical lamellar bone was present around the marginal and apical part of the latter implants with no signs of bone loss. Crater-shaped bone defects and Howship's lacunae were explicit signs of bone resorption in the marginal bone area around the dynamically loaded implants. Despite those bone defects, bone islands were present in contact with the implant surface in this marginal area. This resulted in no significantly lower bone-to-implant contact around the dynamically loaded implants in comparison with the statically loaded and the control implants. However, when comparing the amount of bone in the immediate surroundings of the marginal part of the implants, significantly (P < 0.007) less bone volume (density) was present around the dynamically loaded in comparison with the statically loaded and the control implants. This study shows that excessive dynamic loads cause crater-like bone defects lateral to osseointegrated implants.

Pore diameter of more than 100 microm is not requisite for bone ingrowth in rabbits.

Abstract: The optimal pore size for bone ingrowth is claimed to be 100-400 microm. With the use of a highly standardized experimental model, the present study reevaluated whether a pore size of 100 microm is the threshold value for bone ingrowth into porous structures under non-load-bearing conditions. Titanium triangle-shaped plates 250 or 500 microm thick were perforated with the use of a laser in order to create standard-sized holes ( 50, 75, 100, and 125 microm) in multiple rows. The amount of bone ingrowth through the implant holes was studied in the cancellous bone of the distal rabbit femur. Twelve weeks after implantation, detailed analysis of bone ingrowth was performed with computerized image analysis of backscattered electron imaging techniques of scanning electron microscopy. The results showed that the amount of ingrown new bone was independent of the pore size and implant thickness. The median value for bone ingrowth varied between 64 and 78%. A striking feature was the formation of secondary osteonal structures even in the smallest holes. Based on these results, there is no threshold value for new bone ingrowth in pore sizes ranging from 50 to 125 microm under non-load-bearing conditions.

Long-term evaluation of osseointegrated implants inserted at the time or after vertical ridge augmentation. A retrospective study on 123 implants with 1-5 year follow-up.

Abstract: The purpose of the present study was to evaluate retrospectively, after 1 to 5 years of prosthetic loading, 123 implants consecutively inserted at the time of vertical ridge augmentation in 4 clinics. At the time of the implant surgery, 3 different techniques were used: the implants were allowed to protrude 2 to 7 mm from the bone level and a titanium reinforced expanded-polytetrafluoroethylene (e-PTFE) membrane was positioned to protect either the blood clot (Group A, 6 patients), or an allograft (Group B, 11 patients), or an autograft (Group C, 32 patients). The annual implant evaluation was carried out according to a standard protocol utilized for long term studies with endosseous implants inserted in non-regenerated bone. Only 1 implant failed immediately after the second stage surgery and after 1 month it was substituted with a new implant. All the remaining implants appeared clinically stable, no signs of radiolucency were present at the bone-implant interface, therefore, they could be defined successfully osseointegrated. The radiographic analysis showed stable bone crest levels with a mean bone loss of 1.35 mm for the Group A, of 1.87 mm for the Group B and of 1.71 for the Group C during the period of observation. Only 2 implants demonstrated an increased crestal bone loss of 3.5 mm and 4 mm respectively at the first year examination. On the base of these results, we can confirm previous long term studies on regenerated bone and we can conclude that vertically augmented bone with GBR techniques responds to implant placement like native, non-regenerated bone.

Tilted implants as an alternative to maxillary sinus grafting: a clinical, radiologic, and periotest study.

Abstract: Background: Owing to mechanical and anatomic difficulties, implant treatment in the atrophic maxilla represents a challenge. The maxillary sinus floor augmentation procedure is still not universally accepted because of its complexity and its unpredictability. Purpose: In this study, a combination of tilted and axial implants was used in patients with severely resorbed posterior maxillae as an alternative to sinus grafting. Materials and Methods: Twenty-five patients were rehabilitated with 29 fixed partial prostheses supported by 101 Branemark System implants. Fifty-nine implants were installed in an axial and 42 in a tilted direction. The average follow-up period was 37 months (range:21–87 mo post loading). Results: After 5 years, the implant cumulative success rate was 95.2% (survival: rate 100%) for the tilted implants and 91.3% (survival rate:96.5%) for the axial implants, and the prosthesis survival rate was 100%. At the fifth year, the average marginal bone loss was 1.21 mm for the tilted implants and 0.92 mm for the axial ones. The mean Periotest values (PTV) at loading time were -2.62 and -3.57, and after 5 years the PTVs were -4.73 and -5.00 for the tilted and the axial implants, respectively. During the follow-up, all prostheses but two were mechanically stable, retightening of 18 abutment screws and of 5 gold screws in 14 prostheses was done, and fracture of two abutment screws and two occlusal surfaces was experienced. Conclusions: Results indicate that the use of tilted implants is an effective and safe alternative to maxillary sinus floor augmentation procedures.

Long-term results of implants treated with guided bone regeneration: a 5-year prospective study.

Abstract: The aim of this prospective 5-year longitudinal study was to follow endosteal implants in which guided bone regeneration (GBR) was applied during implant placement. In 75 patients, defects around implants (Branemark System) were treated with Bio-Oss and Bio-Gide (112 implants). In split-mouth patients in this group, Bio-Oss and Gore-Tex were used in the second defect site (41 implants). All 75 patients had at least 1 implant that was entirely surrounded by bone and served as the control (112 implants). After placement of the definitive prostheses (single-tooth, fixed, or removable implant prostheses), patients were recalled after 6 months and then every 12 months during a 5-year observation period. The following variables were investigated: implant survival, marginal bone level (MBL), presence of plaque, peri-implant mucosal conditions, height of keratinized mucosa (KM), and marginal soft tissue level (MSTL). The cumulative implant survival rate after 5 years varied between 93% and 97% for implants treated with or without GBR. The mean MBL after 60 months was 1.83 mm for sites treated with Bio-Oss and Bio-Gide, 2.21 mm for sites treated with Bio-Oss and Gore-Tex, and 1.73 mm for the control sites. The MBL values were found to increase significantly with time and differed significantly among the treatment groups. During the observation period, KM varied between 3.16 and 3.02 mm. A slight recession of 0.1 mm was observed, and plaque was found in 15% of all sites and was associated with inflammatory symptoms of the peri-implant mucosa. It was observed that such symptoms and recession correlated more strongly with the type of restoration than with the type of treatment. This study demonstrated that implants placed with or without GBR techniques had similar survival rates after 5 years, but that bone resorption was more pronounced in sites with GBR treatment. It was assumed that the use of GBR is indeed indicated when the initial defect size is larger than 2 mm in the vertical dimension.

Immediate Occlusal Loading of Brånemark Implants Applied in Various Jawbone Regions: A Prospective, 1-Year Clinical Study

Abstract: Background: The original protocol for dental implant treatment ad modum Branemark was based on submerged healing prior to loading. For patients, immediate implant function could reduce cost and increase attractiveness of implant treatment. Purpose: The goal of this study was to evaluate the short-term success rate of immediately loaded implants placed in various regions of the jaws. Materials and Methods: Forty-one patients received a total of 127 immediately loaded implants (76 maxillary and 51 mandibular). Seventy-one percent of the patients received their prosthetic restoration the same day and the others within 11 days. All prosthetic constructions were in full contact in centric occlusion. Clinical follow-up examinations were performed at 1 week, 2 weeks, and at 1, 2, 3, 6, and 12 months after implant loading. The study was completed 1 year after loading. Results: Twenty-two implants were lost in 13 patients (including 7 maxillary implants lost in 1 patient). The cumulative success rate of the implants was 82.7% after 1 year of prosthetic loading. All sites with implant losses were re-implanted, using a two-stage technique, with no further complications reported. Ninety-one percent of implants placed in regions other than the posterior maxilla were successful compared with 66% of implants placed in the posterior maxilla. Implants in patients with a parafunctional habit (bruxers) were lost more frequently than those placed in patients with no para-function (41% vs. 12%). Implants subjected to guided bone regeneration were more successful compared with those not subjected to regeneration procedures (90% vs. 67%). Conclusions: The immediate loading concept is a realistic treatment alternative in various jawbone regions except for the posterior part of the maxilla. High occlusal loads should be considered a risk factor. On the other hand, implants in combination with bone defects frequently are penetrating cortical layers to a higher extent, thereby contributing to implant stability during the healing phase and consequently do not inevitably jeopardize the treatment result. However, further controlled clinical studies with larger sample sizes need to be performed to evaluate the influence of different parameters on treatment outcome.

Substitutes for autologous bone graft in orthopaedic trauma.

Abstract: Although bone grafting has a well-recognised role in orthopaedic surgery for the treatment of nonunion, bridging diaphyseal defects and filling metaphyseal defects, it is associated with postoperative pain and morbidity. When extensive grafting is required, as in spinal arthrodesis and the management of large bony defects, inadequate amounts of autologous bone may not be available. Allograft bone has been used as an alternative but it has low osteogenicity, increased immunogenicity and resorbs more rapidly than autogenous bone; transmission of disease remains a concern. Autogenous bone graft is osteogenic, osteoinductive, osteoconductive and completely biocompatible. These characteristics should be present in the ideal substitute. Osteogenic materials have the inherent capacity to form bone, which implies that they have living cells such as osteocytes or osteoblasts, capable of producing it. Osteoinductive materials stimulate cells in the wound or the local environment to undergo phenotypic conversion to osteoprogenitor cell types capable of formation of bone. Osteoconductive materials have no capability to form bone or induce its formation. They merely provide an inert biocompatible scaffold, which local osseous tissue can utilise to regenerate living bone. There is no substitute for bone-graft yet available which embodies all these qualities. To date most of the available materials have tended to be either predominantly osteogenic or osteoinductive, or purely osteoconductive. This article reviews the substitutes which are commonly available and considers the clinical evidence to support their use in the management of orthopaedic trauma. Osteogenic and osteoinductive materials

Optimal implant stabilization in low density bone

Abstract: Initial stability of the implant is one of the fundamental criteria for obtaining osseointegration. An adequate primary anchorage is often difficult to achieve in low density bone (type IV). Various surgical suggestions were advanced in the 1980s which were aimed at achieving optimal osseous integration in poor quality bone. They offered satisfactory short-term results. Recently, as a result of surgical and technological innovations, new therapeutic proposals have shown very interesting results in their initial studies.

Implant-retained mandibular overdentures with Brånemark System MKII implants: a prospective comparative study between delayed and immediate loading.

Abstract: This study was designed to compare the results of immediate and delayed loading of implants with implant-retained mandibular overdentures. Ten patients (test group) received 40 Branemark System MKII implants (4 per patient) placed in the interforaminal area of the mandible. Standard abutments were immediately screwed to the implants, rigidly connected with a bar, and immediately loaded with an overdenture. Ten patients (control group) received the same type and number of implants in the same area, but the implants were left to heal submerged. Four to 8 months later, standard abutments were screwed to the implants and the same prosthetic procedure was applied. Each implant was evaluated at the time of prosthetic loading and at 6, 12, and 24 months after the initial prosthetic load with the following parameters: modified Plaque Index (MPI), modified Bleeding Index (MBI), probing depth (PD), and Periotest. Peri-implant bone resorption was evaluated on panoramic radiographs taken 12 and 24 months after initial prosthetic loading. No significant differences were found between the 2 groups regarding MPI, MBI, Periotest, peri-implant bone resorption, and PD at 6 and 24 months (P > .05). The only difference was found regarding PD values on the mesial and lingual sites at 12 months (P < .05). The cumulative success rate of implants was 97.5% in both groups. Results from this study showed that immediate loading of endosseous implants rigidly connected with a U-shaped bar does not seem to have any detrimental effect on osseointegration. Conversely, this method significantly shortens the duration of treatment with relevant satisfaction for the patients. ( INT J ORAL MAXILLOFAC IMPLANTS 2001;16:537‐546)

Early endosseous integration enhanced by dual acid etching of titanium: a torque removal study in the rabbit.

Abstract: Textured implant surfaces are thought to enhance endosseous integration. Torque removal forces have been used as a biomechanical measure of anchorage, or endosseous integration, in which the greater forces required to remove implants may be interpreted as an increase in the strength of bony integration. The purpose of this study was to compare the torque resistance to removal of screw-shaped titanium implants having a dual acid-etched surface (Osseotite) with implants having either a machined surface, or a titanium plasma spray surface that exhibited a significantly more complex surface topography. Three custom screw-shaped implant types - machined, dual acid-etched (DAE), and titanium plasma sprayed (TPS) - were used in this study. Each implant surface was characterized by scanning electron microscopy and optical profilometry. One DAE implant was placed into each distal femur of eighteen adult New Zealand White rabbits along with one of the other implant types. Thus, each rabbit received two DAE implants and one each of the machined, or TPS, implants. All implants measured 3.25 mm in diameter x 4.00 mm in length without holes, grooves or slots to resist rotation. Eighteen rabbits were used for reverse torque measurements. Groups of six rabbits were sacrificed following one, two and three month healing periods. Implants were removed by reverse torque rotation with a digital torque-measuring device. Three implants with the machined surface preparation failed to achieve endosseous integration. All other implants were anchored by bone. Mean torque values for machined, DAE and TPS implants at one, two and three months were 6.00+/-0.64 N-cm, 9.07+/-0.67 N-cm and 6.73+/-0.95 N-cm; 21.86+/-1.37 N-cm, 27.63+/-3.41 N-cm and 27.40+/-3.89 N-cm; and 27.48+/-1.61 N-cm, 44.28+/-4.53 N-cm and 59.23+/-3.88 N-cm, respectively. Clearly, at the earliest time point the stability of DAE implants was comparable to that of TPS implants, while that of the machined implants was an order of magnitude lower. The TPS implants increased resistance to reverse torque removal over the three-month period. The results of this study confirm our previous results that demonstrated enhanced bony anchorage to dual acid-etched implants as compared to machined implants. Furthermore, the present results indicate that dual acid etching of titanium enhances early endosseous integration to a level which is comparable to that achieved by the topographically more complex TPS surfaces.

Histologic evaluation of the bone integration of TiO(2) blasted and turned titanium microimplants in humans.

Abstract: Twenty-seven patients received 2 microimplants each during implant surgery. One microimplant was blasted with 25 microm sized particles of TiO(2); the other was left as machined i.e. a turned surface. Before insertion the surface topography was characterized with an optical confocal laser profilometer. The surface roughness was greater than standard implants, and was similar for both surface modifications averaging over all parts of the implant i.e. tops, valley and flanks. The mean surface roughness from flank measurements only replicated previously reported findings: i.e. significantly rougher surfaces on blasted implants. After a mean healing period of 6.3 months in the maxillae and 3.9 months in the mandible, the microimplants and surrounding tissue were removed with a trephine burr. The histomorphometrical evaluation demonstrated significantly higher bone-to-implant contact for the blasted implants, inserted in the maxilla or in the mandible. Significantly more bone was found inside the threaded area for the blasted implants in the mandible, but there was no difference for implants positioned in maxillae.

Early loading of sandblasted and acid‐etched (SLA) implants: a prospective split‐mouth comparative study

Abstract: Sandblasted and acid-etched (SLA) implants were recently introduced to reduce the healing period between surgery and prosthesis. In this split-mouth study, SLA implants were compared to titanium plasma-sprayed (TPS) implants under loaded conditions one year after placement in 32 healthy patients, with comparable bilateral edentulous sites and no discrepancies in the opposing dentition. The surgical procedure was performed by the same operator and was identical at 68 SLA (test) and 68 TPS (control) sites. Tapping was never performed and primary stability was always achieved. Abutment connection was carried out at 35 Ncm 6 weeks postsurgery for test sites and 12 weeks for the controls, by the same dentist blind to the type of surface of the implant. In 4 of the 68 test sites the implant rotated slightly, patients reported minor pain and connection was not completed. Provisional restoration was fabricated and a new tightening was performed after six weeks. Similar gold-ceramic restorations were cemented on the same type of solid abutments on both sites. No implant was lost. Clinical measures and radiographic changes were recorded by the same operator, blind to the type of surface of the implant, 1 year post surgery. No significant differences were found with respect to presence of plaque (24% vs. 27%), bleeding on probing (24% vs. 31%), mean pocket depth (3.3 mm vs. 2.9 mm) or mean marginal bone loss (0.65 mm vs. 0.77 mm). The results suggest that SLA implants are suitable for early loading at 6 weeks. Limited implant spinning may occasionally be found but, if properly handled, it produces no detrimental effect on the clinical outcome.

Biological reactions of alveolar bone to orthodontic loading of oral implants.

Abstract: Enosseous oral implants have been suggested as anchorage for orthodontic appliances in cases where the existing dentition cannot provide sufficient stability Long-term studies of oral implants have suggested that excessive loading may contribute as an etiologic factor in the pathogenesis of failing implants The purpose of the present study was to perform a histomorphometric analysis of tissue reactions around implants subjected to a well-defined force system The analysis was performed on undecalcified sections cut perpendicularly to the long axis of the implant The degree of osseointegration, bone density at varying distances from the implant as well as the relative extent of resorption and formation of alveolar bone adjacent to the implant-bone interface were evaluated The results were correlated with the local strain of the tissue estimated by the means of a finite element analysis It was found that loading significantly influenced both the turnover and the density of the alveolar bone in the proximity of the implants However, even unloaded implants tended to maintain the bone characteristics of the alveolar process On the other hand, the degree of osseointegration appeared to be independent of the loading of the implant

Maxillary sinus augmentation with the xenograft Bio-Oss and autogenous intraoral bone for qualitative improvement of the implant site: a histologic and histomorphometric clinical study in humans.

Abstract: The aim of the present clinical study was to determine, through histologic and histomorphometric investigations of human bone specimens, whether the addition of autogenous bone to the bone substitute material Bio-Oss can produce a high-quality implant site. To improve vertical bone height, 13 sinus floor elevations were carried out in a total of 12 patients. Augmentation of the maxillary sinus floor was completed using a mixture of Bio-Oss and bone harvested intraorally from the mandibular symphysis, the retromolar space, or the tuberosity region. Following an average of 7.1 months of healing, 36 Branemark System implants were placed. During this surgical intervention, 23 cylinder-shaped bone biopsies were taken from the augmented maxillary region using trephine burs. Histologic analysis of the bone biopsies revealed that the Bio-Oss granulate was well-integrated into the newly formed bone; 33.1% (+/- 12.4%) of the substitute material surface was in direct contact with bone. Histomorphometric analysis of the samples revealed an average percentage proportion of bone of 18.9% (+/- 6.4%). The bovine substitute material and soft tissue occupied, respectively, 29.6% (+/- 8.9%) and 51.5% (+/- 9.4%) of the measured surface. When the implants were uncovered after an average healing phase of 6 months, all 36 implants had become osseointegrated. The combination of osteoconductive Bio-Oss and osteoinductive autogenous bone thus proved to be a material suitable for application in sinus floor augmentation.

Re-osseointegration after treatment of peri-implantitis at different implant surfaces. An experimental study in the dog.

Abstract: Peri-implantitis is a condition that includes soft tissue inflammation and rapid loss of bone. Treatment of peri-implantitis includes both antimicrobial and bone augmenting methods. The question of whether true re-osseointegration may occur following treatment of peri-implantitis is controversial. The aim of this study was to investigate whether the character of the implant surface was of importance for the occurrence of re-osseointegration following treatment of peri-implantitis. Four beagle dogs were used. The mandibular premolars were extracted. After 12 months, 3 ITI(R) solid screw dental implants were placed in each side of the mandible. In the left side, implants with a turned surface (Turned sites) were used, while in the right side implants with a SLA surface (SLA sites) were placed. After 3 months of healing, peri-implantitis was induced by ligature placement and plaque accumulation. When about 50% of the initial bone support was lost, the ligatures were removed. Five weeks later, treatment was initiated. Each animal received tablets of Amoxicillin and Metronidazole for a period of 17 days. Three days after the start of the antibiotic regimen, one implant site (experimental site) in each quadrant was exposed to local therapy. Following flap elevation, the exposed titanium surface was cleaned with the use of cotton pellets soaked in saline. The implants were submerged. Six months later, biopsies were obtained. Treatment resulted in a 72% bone fill of the bone defects at Turned sites and 76% at SLA sites. The amount of re-osseointegration was 22% at Turned sites and 84% at SLA sites. A treatment regimen that included (i) systemic administration of antibiotics combined with (ii) granulation tissue removal and implant surface cleaning resulted in resolution of peri-implantitis and bone fill in adjacent bone defects. Further, while substantial "re-osseointegration" occurred to an implant with a rough surface (SLA), bone growth on a previously exposed smooth surface (Turned) was minimal.

A multi-center study comparing dual acid-etched and machined-surfaced implants in various bone qualities.

Abstract: Background: A major reason for the success of modern dental implant systems has been the development of implant designs. that enhance direct bone-implant interface. Surface roughness has been a factor in this success and different systems have utilized very different implant surface roughness. The major purpose of this study was to evaluate 2 similar implants with different surface roughness characteristics. Methods: Two similarly designed, screw-type, commercially pure titanium implants, one dual acid-etched (DAE) and the other machined-surfaced (MS), were compared in this prospective, randomized-controlled, multi-center study, in which a total of 97 patients were enrolled at a private dental practice or a university dental clinic. Both implant types were placed in each patient using a 2-stage approach with a conventional 4- to 6-month healing period. Implants supported fixed prostheses, hybrid prostheses, and overdentures as dictated by the individual patient's need. All of the cases were followed using...

Monitoring of periprosthetic BMD after uncemented total hip arthroplasty with dual-energy X-ray absorptiometry--a 3-year follow-up study.

Abstract: Insertion of a metallic implant into the femur changes bone loading conditions and results in remodeling of femoral bone. To quantify changes in bone mass after uncemented total hip arthroplasty (THA), we monitored femoral bone with dual-energy X-ray absorptiometry (DXA). The periprosthetic bone mineral density (BMD) was measured with Lunar DPX densitometry in seven Gruen zones and the total periprosthetic area at scheduled time intervals in 22 patients during a 3-year follow-up. BMD decreased significantly almost in all Gruen zones during the first 3 months, ranging from 3.4% to 14.4% (p < 0.05 top < 0.001). At the end of the first year, the most remarkable decrease in BMD was found in the calcar (zone 7; -22.9%). During the second postoperative year, a slight restoration of periprosthetic bone mass was recorded. During the third year, no significant changes in BMD were found. The preoperative BMD was the only factor that was significantly related to the periprosthetic bone loss. Clearly, the early periprosthetic bone loss noticed during the 3 months after THA is caused by mainly limited weight bearing to the operated hip and stress shielding. We suggest that the restoration of bone mass is a sign of successful osteointegration between bone and metallic implant. DXA is a suitable tool to follow the bone response to prosthetization and will increase our knowledge on the behavior of bone after THA.

Remote implant anchorage for the rehabilitation of maxillary defects.

Abstract: The rehabilitation of maxillary defects is a significant challenge in terms of creating retention and preserving existing dentition in an environment of expanded functional stress. The advent of osseointegration has enhanced the dental practitioner’s capabilities in this regard with a remarkably improved potential for increasing prosthesis stability and preserving tissue. For patients with extensive prosthetic cantilevers, however, the opportunity for implant placement in defect areas is compromised unless remote bone sites are considered. Implants in the defect buttress zone through the maxillary sinus in non-defect sites (zygoma implants) can be valuable in providing a level of functional rehabilitation previously unattainable. (J Prosthet Dent 2001;86:377-81.)

Immediate loading of implants with fixed restorations in the completely edentulous mandible: report of 27 patients from a private practice.

Abstract: Numerous authors have documented clinical success in loading threaded implants at the time of implant placement when carefully controlled surgical and restorative protocols are followed. This clinical series documents the application of immediate loading techniques to fixed mandibular restorations in 27 patients who were edentulous or had non-restorable mandibular dentitions. Eighteen patients had complete conventional maxillary dentures, while 9 had natural or fixed prosthetic maxillary dentitions. Twelve different restorative dentists provided prosthetic support for these patients and used 4 different restoration types: laboratory- or office-processed, with cement or screw retention. Five to 8 threaded implants were placed in each patient. One hundred sixty-one of the 186 implants that were placed by the authors were loaded immediately using fixed provisional restorations of the various designs. More than 99% (160/161) of the immediately loaded implants and 99.5% (185/186) of all implants were clinically integrated and radiographically successful at the time of final evaluation for restoration fabrication. After final implant evaluation, no additional implant losses occurred, indicating an implant survival rate of nearly 100% over a mean of 25.0 months (range 13 to 41 months) following implant placement. While a strong preference for cement-retained restorations was apparent, all prostheses showed similar success. The data and the experience described in this report indicate that immediate loading with fixed restorations using appropriate surgical and restorative techniques can be a predictable technique for rehabilitation of the completely edentulous mandible.

Oxidized implants and their influence on the bone response.

Abstract: Surface oxide properties are regarded to be of great importance in establishing successful osseointegration of titanium implants Despite a large number of theoretical questions on the precise role of oxide properties of titanium implants, current knowledge obtained from in vivo studies is lacking The present study is designed to address two aspects The first is to verify whether oxide properties of titanium implants indeed influence the in vivo bone tissue responses The second, is to investigate what oxide properties underline such bone tissue responses For these purposes, screw-shaped/turned implants have been prepared by electrochemical oxidation methods, resulting in a wide range of oxide properties in terms of: (i) oxide thickness ranging from 200 to 1000 nm, (ii) the surface morphology of barrier and porous oxide film structures, (iii) micro pore configuration – pore sizes<8 μm by length, about 127 μ2 to 21 μm2 by area and porosity of about 127–244%, (iv) the crystal structures of amorphous, anatase and mixtures of anatase and rutile type, (v) the chemical compositions of TiO2 and finally, (vi) surface roughness of 096–103 μm (Sa) These implant oxide properties were divided into test implant samples of Group II, III, IV and V Control samples (Group I) were turned commercially pure titanium implants Quantitative bone tissue responses were evaluated biomechanically by resonance frequency analysis (RFA) and removal torque (RT) test Quantitative histomorphometric analyses and qualitative enzyme histochemical detection of alkaline (ALP) and acidic phosphatase (ACP) activities were investigated on cut and ground sections after six weeks of implant insertion in rabbit tibia In essence, from the biomechanical and quantitative histomorphometric measurements we concluded that oxide properties of titanium implants, ie the oxide thickness, the microporous structure, and the crystallinity significantly influence the bone tissue response At this stage, however, it is not clear whether oxide properties influence the bone tissue response separately or synergistically

A multicenter 12-month evaluation of single-tooth implants restored 3 weeks after 1-stage surgery.

Abstract: The time-intensive, multi-step process of dental implant therapy limits patient acceptance. This 3-year prospective multicenter study sought to determine the safety of an expedited therapy that consisted of loading unsplinted maxillary anterior single-tooth implants 3 weeks after 1-stage surgical placement, and determination of the peri-implant cortical bone and mucosal responses to the expedited procedure. Fifty-two patients missing 1 or 2 maxilliary anterior teeth were enrolled in a study approved by the Institutional Committee on Human Subjects Research and based on strict inclusion and exclusion criteria. Astra Tech ST implants placed in a 1-stage procedure were restored 3 weeks later with ST abutments and a provisional crown (baseline); 7 to 9 weeks later, a porcelain-fused-to-metal or all-ceramic crown was cemented. Radiographic and clinical examinations were made at baseline and at 6 and 12 months. Implant survival was recorded. Cortical bone responses and peri-implant mucosal responses were evaluated. Fifty-eight implants were placed. During the 3-week period after implant placement, 4 patients were dismissed because of smoking cigarettes (a protocol deviation), and 1 patient was excluded because of deviation in loading time. Of the remaining 53 implants, 2 failed before definitive crown cementation. The resultant 96.2% survival rate was independent of implant length, tooth position, and bone quality/quantity. The mean change in marginal bone level was 0.4 mm at 12 months. The number of surfaces with plaque decreased from 3.4% at baseline to 0.5% at 12 months. The surfaces with inflammation also decreased. A mean gain in papilla length of 0.61 mm occurred, and a gain in buccal gingiva (x = 0.34 mm) was observed. A high success rate with positive tissue responses was achieved for maxillary anterior unsplinted single-tooth implants placed in a 1-stage surgery and restored at 3 weeks. This 2-component system is suited to a single-stage, rapid loading protocol for esthetic single-tooth replacement.

Freestanding and tooth‐implant connected prostheses in the treatment of partially edentulous patients

Abstract: In 123 patients, 339 implants were connected to 313 teeth by means of fixed partial prostheses (test) and followed up for 1.5–15 years (mean: 6.5). In another ad random selected 123 patients, 329 implants were connected to each other by means of 123 freestanding fixed partial prostheses (control) and were followed up for 1.3–14.5 years (mean: 6.2). The aim of this study was to compare both treatment modalities with each other based on implant, tooth and prosthesis complications. The cumulative implant success, based on implant immobility and/or lack of implant fractures after loading, in the test and control groups amounted to 95% and 98.5%, respectively. Although in the test group 10 implants versus only 1 in the control group failed, a regression analysis of the survival data, based on the cox proportional hazards model, revealed no significant difference. In the test group periapical lesions (3.5%), tooth fracture (0.6%) and tooth extraction due to fatal decay or periodontitis (1%) were observed, besides tooth intrusion (3.4%) and crown cement failure (8%). Framework fracture occurred in 3 patients. In the control group, only 2 abutment screws fractured. The treatment of partial edentulism by means of oral implants was beneficial for our patients. Because of a clear tendency of more implant failures (mobility or fractures) and tooth complications in the tooth-implant connected prostheses, the freestanding solution is the primary option to be considered. To avoid intrusion of abutment teeth, the connection, if made, should be completely rigid.

Porous bovine bone mineral in healing of human extraction sockets: 2. Histochemical observations at 9 months.

Abstract: Background: Porous bovine bone mineral (PBBM) has been used in ridge preservation procedures following tooth extractions. The aim of this study was to investigate histochemically tissue sockets grafted with PBBM at 9 months post-extraction. By using different histochemical stainings, characteristics of the newly formed bone; i.e., lamellar/woven ratio at different socket depths, were investigated and the arrangement of bone around the grafted material, as well as the nature of the amorphous organic material found in all specimens, were examined. Methods: After extraction of 15 single-rooted maxillary teeth from 15 patients, socket sites were grafted with PBBM particles (250 to 1000 µ). Primary soft tissue closure of the grafted site was established using the rotated split palatal pedicle flap technique. At 9 months, a cylindrical tissue specimen, 2.5 mm in diameter, was trephined from each previously grafted site followed by placement of a screw-shaped implant. Horizontal tissue section cuts, 5 µ wide, we...

Treatment outcome of bone-anchored craniofacial prostheses after tumor surgery

Abstract: BACKGROUND Percutaneous endosseous implants have acquired an important place in the prosthetic rehabilitation of patients with craniofacial defects. The objective of this study was to evaluate the clinical outcome of the use of endosseous implants in the orbital and auricular region as well as to assess the satisfaction of patients with implant-retained craniofacial prostheses after tumor surgery. METHODS The clinical outcome and patient satisfaction of implant-retained prostheses in the auricular and orbital region were evaluated in a group of 26 patients with facial defects after tumor surgery by using standardized questionnaires and a clinical assessment. Twelve patients (n = 31 implants) received the implants during ablative tumor surgery, from which 7 patients (n = 20 implants) were treated with radiation therapy after surgery (mean, 65 grays [Gy]). Fourteen patients (n = 44 implants) received the implants after the tumor surgery, from which 5 patients (n = 21 implants) were irradiated after ablative surgery (mean, 54.4 Gy), but before implant placement. RESULTS No implants were lost in patients who had not undergone irradiation (100%), whereas 5 implants were lost in the irradiated group (87.8%). The overall implant survival rate was 93.3%. The peri-implant tissues had a healthy appearance, and no cases of osteoradionecrosis occurred. When compared with patients treated with conventional adhesive retained facial prostheses, satisfaction was higher in patients treated with implant-retained facial prostheses. CONCLUSIONS From this study, it is concluded that implant-retained facial prostheses are better tolerated than adhesive retained prostheses and offer an improvement in the quality of life. Radiotherapy is not a contraindication for the use of osseointegrated implants in the maxillofacial region, but the loss of implants is higher than in nonirradiated sites. Cancer 2001;92:3045–50. © 2001 American Cancer Society.