Bone-titanium Interface Research Articles

Four Stable and Functioning Dental Implants Retrieved for Fracture After 14 and 17 Years from the Same Patient: A Histologic and Histomorphometric Report.

The aim of the present study was a histologic and histomorphometric analysis of the peri-implant tissue reactions and of the bone-titanium interface in successfully osseointegrated, clinically stable, and immobile retrieved titanium dental implants after a long loading period. Four successfully osseointegrated and stable implants with a sandblasted surface were retrieved from a patient due to fracture, two after 14 years of loading and two after 17 years. None of these implants has been previously reported. Mature, compact bone with a few marrow spaces was observed around all four implants. At low magnification, a high percentage of bone-implant contact (BIC) was present at the interface of almost all implants. BIC percentage for the four implants was 83%, 66%, 74%, and 65%. In almost all the implants, the space within the threads was almost completely filled by compact bone. Close, tight contact between bone and implant surface was observed in all specimens, and no gaps or fibrous connective tissue was found at the bone-implant interface. All implants appeared to be well integrated in the surrounding mineralized bone, and all showed adequate BIC percentages after a long loading history.

Periimplant Bone Response in Human-Retrieved, Clinically Stable, Successful, and Functioning Dental Implants After a Long-Term Loading Period: A Report of 17 Cases From 4 to 20 Years.

This study aimed at a histologic and histomorphometric analysis of the periimplant tissues and bone-titanium interface reactions in successfully osseointegrated, clinically stable, and immobile human titanium dental implants retrieved after a long loading period. In the last 30 months (2013-2015), 21 implants, retrieved from individuals for different causes after a loading period ranging from 4 to 20 years, were sent to the Implant Retrieval Center, University of Chieti-Pescara, Italy. In 4 cases, almost all the bone had been lost during the retrieval, whereas in the remaining 17 cases, mineralized bone was still present. Around the majority of the implants, mature compact bone with few marrow spaces was found. The trabecular bone, constituted by a few thin bone trabeculae, was in a periimplant location around only a few implants. A high percentage of bone-implant contact (BIC) (comprised between 32 ± 4.1% and 83 ± 2.9%) was present. In almost all implants, the space within the threads was almost completely filled by compact lamellar bone or by a thin layer of bone. Close and tight contact between bone and implant surface was observed in all specimens with no gaps or connective tissue at the interface. All implants appeared to be well integrated in the surrounding mineralized bone, and all of them showed adequate bone-to-implant contact percentages.

Microradiographic and histological evaluation of the bone-screw and bone-plate interface of orthodontic miniplates in patients

To describe the tissue reactions at the bone-titanium interface of orthodontic miniplates in humans. Forty-two samples, consisting of tissue fragments attached or not to miniplates or their fixation screws, were collected from 24 orthodontic patients treated with miniplate anchorage, at the time of removal of their miniplates. The samples were embedded in methylmethacrylate and cut into undecalcified sections which were submitted to microradiographic analysis. The sections were also stained and examined under ordinary light. Three types of reactions were observed both on the histological sections and on the microradiographs. 1. The majority of the stable miniplates were easy to remove (34/42). The tissue samples collected consisted mainly in mature lamellar bone with some medullary spaces containing blood vessels, 2. two screws were highly osseointegrated and required the surgeon to remove them by trephining (2/42). They were surrounded by bone tissue which extended to the miniplate. The histological features were similar to the previous group, though the bone-screw contact was higher, and 3. in six samples obtained after unstable miniplate removal during the treatment, we observed either some woven bone trabeculae or loose connective tissue, without any histological sign of inflammation. For evident ethical reasons, our data were limited by the size of the tissue fragments and the limited number of patients and variety of clinical presentations. The healing reactions consisted mainly in mature lamellar bone tissue sparsely in contact with the screw or the miniplate, with signs of a moderate remodelling activity.

Bone Response to Dental Implants After a 3- to 10-Year Loading Period: A Histologic and Histomorphometric Report of Four Cases

The aim of this study was to histologically and histomorphometrically analyze the peri-implant tissue reactions and the bone-titanium interface in loaded Ankylos implants retrieved after loading periods of longer than 1 year. The archives of the Implant Retrieval Center of the Dental School of the University of Chieti- Pescara were searched for Ankylos implants retrieved from humans after a loading period of longer than 1 year. A total of four implants were found: one had been retrieved after 3 years (Friadent plus surface), two after 3.5 years (Friadent plus surface), and one after 10 years (Deep Profile surface). All implants had been loaded; two had been loaded immediately. One implant was retrieved after fracture, one was retrieved after fracture of the superstructure, and the other two were retrieved because of bone resorption with or without infection. Compact bone with few small marrow spaces was present around the three implants retrieved after 3 and 3.5 years; trabecular bone was present around the implant retrieved after 10 years. The bone-implant contact of the three best threads was 35% for the implant retrieved after 10 years, 99% for the implant retrieved after 3 years, and 100% for the implants retrieved after 3.5 years. No untoward effects were present at the interface, and a high bone-implant contact was present around the implants with the microstructured surface. The data show that these implants had the potential to maintain osseointegration under long-term function with continuous and ongoing bone remodeling.

Peri-implant bone tissues around retrieved human implants after time periods longer than 5 years: a retrospective histologic and histomorphometric evaluation of 8 cases

Only rarely, it is possible to find in the literature histological reports of human retrieved implants, especially after several years of functional loading. These implants can help us in understanding the reactions of peri-implant bone. The aim of this study was to perform a histologic and histomorphometric analysis of the peri-implant tissues behavior and of the bone-titanium interface in titanium dental implants retrieved from patients after time periods longer than 5 years. The archives of the Implant Retrieval Center of the Dental School of the University of Chieti-Pescara, Italy were searched for human dental implants, retrieved after a loading period of more than 5 years. A total of 8 implants were found: 3 of these had been retrieved after 5 years, 1 after 6 years, one after 10 years, 1 after 14 years, 1 after 18 years, 1 after 22 years. Only the bone to implant contact in the three best threads was evaluated. Compact, mature, lamellar bone, with few and small marrow spaces, was present around the implants. Osteons with Haversian canals were present inside some threads, in close proximity to the interface, at both cortical and trabecular regions. Other osteons had a direction perpendicular to the direction of the long axis of the implants. Numerous reversal lines were present. At higher magnification, no gaps or fibrous, connective tissues were present at the interface. The BIC of the three best threads for all implants varied from 94 to 100 %.In conclusion, within the limitations of the present report histology showed that implants with different surfaces all presented the potential to maintain osseointegration over a long period, with a continuous remodeling at the interface, as indicated by the presence of reversal lines.

A Role for Proteoglycans in Mineralized Tissue-Titanium Adhesion

Biomechanical properties of the bone-titanium interface have rarely been studied, due to the technical limitations involved; whether biological bonding mechanisms exist has not been determined. We hypothesized that a selected set of proteoglycan/glycosaminoglycan complexes plays a role in establishing the adhesion between bone and titanium, and utilized the rat bone-marrow-derived osteoblastic culture model to gain an insight into the hypothesis. Gene expression of selected proteoglycan core proteins was up-regulated in the osteoblasts cultured on titanium compared with those on polystyrene. Various sulfated glycosaminoglycans were immunochemically localized at mineralized tissue-titanium interfaces. The administration of various glycosaminoglycan-degrading enzymes into the cultures resulted in a 25-45% reduction of the tissue-titanium interfacial strength, measured by a nanoscratch test; while the hardness and elastic modulus of the mineralized tissue, evaluated by nano-indentation, were not altered. In conclusion, glycosaminoglycan degradation resulted in a decreased interfacial strength between cultured mineralized tissue and titanium, but did not alter the intrinsic strength of the mineralized tissue, suggesting a role for proteoglycan/glycosaminoglycan complexes in the establishment of tissue-titanium adhesion.

The influence of the X-ray spectrum at compact bone–titanium interfaces in digital dental radiography

To determine the optimum X-ray spectrum in digital dental radiography once the dose around an implant and the diagnostic usefulness of the image are taken into account. A Monte Carlo code (MCNP4B) was employed for computing the dose distribution across the bone-titanium interface. The X-ray spectra used were those met in digital dental radiography; 50-70 kVp, 2 mm Al total filtration, 5 kVp increment. The variation of the ratio of dose with as opposed to without implant against depth reaches maximum values at the bone-implant interface that vary between 2.9 and 3.2. For the same number of photon histories followed, the higher the tube potential setting, the greater the dose both in contact and inside the implant. In digital dental radiography, a 60-65 kVp spectrum accompanied by the known 30% reduction in mAs leads to lower dose to the patient for a diagnostically useful image.

Histologic Evaluation of 3 Retrieved Immediately Loaded Implants After a 4-Month Period

To perform a histologic and histomorphometric analysis of the peri-implant tissue reactions and bone-titanium interface in 3 immediately loaded (provisional loaded) titanium implants retrieved from a man after a loading period of 4 months. A 35-year-old patient with a maxillary partial edentulism did not want to wear a provisional removable prosthesis during the healing period. It was decided to insert 3 definitive implants and use 3 provisional implants for the transitional period. The provisional implants were loaded the same day with a resin prosthesis in occlusal contact. During the second surgical phase, after 4 months, the provisional prosthesis was removed, and the provisional implants were retrieved with a trephine bur. Before retrieval, all implants appeared to be clinically osseointegrated. The specimens were processed for observation under light microscopy. At low magnification, it was possible to observe that bone trabeculae were present around the implant. Areas of bone remodeling and haversian systems were present near the implant surface. Under polarized-light microscopy, it was possible to observe that in the coronal aspect of the thread, the lamellar bone showed lamellae that tended to run parallel to the implant surface, while in the inferior aspect of the thread, the bone lamellae ran perpendicular to the implant surface. Histologic data pertaining to these 3 immediately loaded implants, and retrieved after a 4-month loading period, show that immediate loading did not produce untoward effects on peri-implant bone healing.

Radiation absorbed doses at compact bone-titanium interfaces in diagnostic radiography: a Monte Carlo approach.

The aim of this study was to estimate the radiation absorbed dose at cortical tissue-implant interfaces in diagnostic radiology. Since our interest was the radiation dose at an interface (cortical bone-implant interface), a Monte Carlo simulation was considered to be the most suitable method for studying the problem. The Monte Carlo code employed was MCNP4B. A phantom consisting of soft tissue, cortical bone, an implant and air, with appropriate chemical compositions and densities, was described in the code. The implant simulated had a commercial name of ASTM67, grade 2 and was 1.9 mm wide. The incident photon beam was divergent of 20 cm x 20 cm at a source-to-phantom distance of 40 cm. Two energy spectra were employed (70 kVp and 100 kVp, 0.5 mm Al internal filtration) and their photon fluence distribution against energy was described in the code with an energy interval of 5 keV. The computations that led to radiation dose calculations had a spatial resolution of 0.01 cm (100 microm) to allow a detailed radiation dose distribution across the cortical bone-titanium interface. Monte Carlo runs took place both with and without an implant in the phantom and, in each case, 120 million photon histories were followed, leading to a radiation dose statistical fluctuation between 5% and 10%. The ratio of radiation dose with implant to dose without implant against depth allows a direct estimate of the effect of the implant on the radiation dose to the cortical bone surrounding the implant. At a distance >or=100 microm there was no radiation dose increase due to the titanium implant. However, in contact with the implant (i.e. the first layers of cells) there was a sharp radiation dose increase as high as 3.5 times the radiation dose compared with when the implant was absent. Also, the newly formed bone inside the implant's tiny hole received a radiation dose close to 50% of the radiation dose without the implant owing to high absorption by the implant itself. Assuming that the patient received five radiographic images over a 6-month period, the maximum radiation dose at the cortical bone-titanium interface was estimated to be less than 20 mGy (0.02 Gy).

Histologic analysis of clinically retrieved immediately loaded titanium implants: a report of 11 cases.

Several investigators have reported high survival rates for early or immediately loaded dental implants. The aim of the present study was to analyze histologically the periimplant tissue reactions and the bone-titanium interface of clinically retrieved immediately loaded titanium implants. Eleven implants were inserted in the posterior jaw regions of six patients, serving as the most distal abutments of fixed provisional bridges and subjected to immediate occlusal loading. After a 10-month loading period, all 11 implants were retrieved with a trephine. Mature bone was present at the interface of all implants. Some vertical bone loss was observed; this was more pronounced for cylindric implants. The bone-implant contact was approximately 60 to 65% for all implants. The results demonstrate that osseointegration of dental implants can occur during immediate loading.

Behavior of the bone-titanium interface after push-in testing: a morphological study.

Fourteen titanium dental implants (Tioblast) were implanted singly in the proximal tibia of New Zealand rabbits for 120 days. A bone defect was surgically produced and filled with Bio-Oss around six of these implants. After the animals were sacrificed and their organs harvested, bone segments were fixed and methacrylate embedded after the push-in test had been performed. Microradiography was performed on longitudinal sections of the implants, whereas scanning electron microscope analysis was performed on the remaining embedded half-implants using secondary electrons only. The results showed that the implants were apically and coronally surrounded by bone, whether Bio-Oss was used or not. Fractures were evident through the newly formed bone and between the pre-existing and newly formed bone. Some fracture lines propagated through the bone and stopped at the implant surface without continuing along the bone-titanium interface. Detachment between the implant and the bone occurred at the coronal extremity of the implants and along its cervical region. These results highlight the fact that the bone-titanium interface has a high resistance to loading. It exhibited greater resistance than the newly formed bone and seems to behave in a manner similar to the cement lines of osteons.

The behaviour of titanium as a biomaterial: microscopy study of plates and surrounding tissues in facial osteosynthesis

Titanium has become the biomaterial of choice for facial osteosynthesis. Titanium is considered a highly biocompatible and corrosion resistant material, although the ultrastructural behaviour of titanium in human tissues after bone fixation is not well documented. A prospective scanning electron microscopy study was carried out on 37 commercially pure titanium miniplates which were removed from 23 patients who had undergone surgery for maxillofacial trauma or deformity. Twenty two cases were used as a control group. Implant-bone specimens were excised using tungsten burs and studied with a scanning electron microscope (Jeol JSM-T-300). Findings at the bone-titanium interface were analyzed, as well as the presence of contaminating bodies on the specimen surface. Biopsies were also obtained from the soft tissues adjacent to 20 miniplates, then sectioned and stained with Haematoxilin-Eosin for histological evaluation by light microscopy. The results showed good ultrastructural osseointegration of the osteosynthesis material in most cases (81.8%). Mobility was found upon removal in 80% of plates which showed clinical complications. A significant correlation was found between the degree of microscopical osseointegration and macroscopic fixation of the plate. Microscopical contamination was found in 100% of the nine plates with intraoral exposure, while only 36% of the 22 miniplates of the control group had contaminating elements (P < 0.001). Thirty-five point one percent of the plates showed hole-like substance loss images, whose size ranged from 10-25 mu. Light microscopy showed granular deposits in soft tissues surrounding the plates in 80% of the 20 specimens investigated. Our findings suggest a higher development of corrosion in titanium than previously reported. These findings are not correlated, however with the clinical complications.

An immunoelectron microscopic localization of noncollagenous bone proteins (osteocalcin and osteopontin) at the bone-titanium interface of rat tibiae.

This study was designed to investigate by postembedding immunogold method the localization and distribution of osteocalcin (Ocl) and osteopontin (Opn) at the bone-titanium interface in rat tibiae 14 and 28 days postimplantation to determine which bone proteins are present at this interface. Both proteins were widely distributed on the newly formed bone and accumulated predominantly in the region of bone close to the titanium, in electron-dense patches in the bone, and at the osteocytic lacunae. Collagenous osteoid showed little or no labeling for either Ocl or Opn. An amorphous zone (20-50 nm) was interposed between the titanium and interfacial slender cells, osteoid, or bone, and was labeled strongly for Ocl but only weakly for Opn. Furthermore, a second electron-dense layer, the lamina limitans, which faces the titanium, was labeled strongly for Opn but weakly for Ocl. Ocl as a marker protein of osteoblasts was sometimes found in the granules and vesicles of the interfacial cells and extracellularly in their intercellular spaces, close to the titanium. However, Opn was not detected in any granules. This is the first report to show that the amorphous zone contains large amounts of Ocl and small amounts of Opn, and that bone contacts titanium through this Ocl-rich amorphous zone. Furthermore, it is suggested that the interfacial cells seem to be osteoblasts, and that Ocl in the amorphous zone is produced and secreted by these cells and functions with Opn as a regulator of the mineralization front close to the titanium, and as a mediator of cell-matrix and matrix-matrix/mineral adhesion along the titanium.

An immunoelectron microscopic localization of noncollagenous bone proteins (osteocalcin and osteopontin) at the bone–titanium interface of rat tibiae

This study was designed to investigate by postembedding immunogold method the localization and distribution of osteocalcin (Ocl) and osteopontin (Opn) at the bone–titanium interface in rat tibiae 14 and 28 days postimplantation to determine which bone proteins are present at this interface. Both proteins were widely distributed on the newly formed bone and accumulated predominantly in the region of bone close to the titanium, in electron-dense patches in the bone, and at the osteocytic lacunae. Collagenous osteoid showed little or no labeling for either Ocl or Opn. An amorphous zone (20–50 nm) was interposed between the titanium and interfacial slender cells, osteoid, or bone, and was labeled strongly for Ocl but only weakly for Opn. Furthermore, a second electron-dense layer, the lamina limitans, which faces the titanium, was labeled strongly for Opn but weakly for Ocl. Ocl as a marker protein of osteoblasts was sometimes found in the granules and vesicles of the interfacial cells and extracellularly in their intercellular spaces, close to the titanium. However, Opn was not detected in any granules. This is the first report to show that the amorphous zone contains large amounts of Ocl and small amounts of Opn, and that bone contacts titanium through this Ocl-rich amorphous zone. Furthermore, it is suggested that the interfacial cells seem to be osteoblasts, and that Ocl in the amorphous zone is produced and secreted by these cells and functions with Opn as a regulator of the mineralization front close to the titanium, and as a mediator of cell–matrix and matrix–matrix/mineral adhesion along the titanium. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 111–119, 1998.

An immunocytochemical study for lysosomal cathepsins B and D related to the intracellular degradation of titanium at the bone-titanium interface.

The morphological relationship between titanium and lysosomal proteinases, cathepsins B and D, at the bone-titanium interface using titanium-coated plastic implants placed for 28 days in the tibiae of 6-week-old rats was immunocytochemically investigated by the colloidal immunogold-silver method. Under light microscopy the titanium layer appeared to make direct contact with the bone and one or a few layers of slender cells were interposed between the bone and titanium. Ultrastructurally, the titanium came in contact with the bone or the slender cell layer through a 20 to 40 nm thin amorphous zone. The slender cells at the bone-titanium interface consisted of two types; one was an osteoblast type with glycogen granules which was found along the newly-formed bone facing titanium layer. The other was a fibroblast type which came in contact with the titanium layer and occasionally endocytosed the detached titanium fragments. In addition, some of the slender cells also showed degenerative changes. Immunocytochemically, cathepsins B and/or D were sometimes colocalized in some phagolysosomes with titanium fragments. These findings suggested that the fibroblast types at the bone-titanium interface may act as scavengers to remove both cell debris and titanium by means of some endocytotic ability, and lysosomal cathepsins also developed in response to the endocytosed titanium. The osteoblast type also appears to show a high degree of osteogenic activity around the titanium-coated plastic implants.

Long-term evaluation of bone-titanium interface in rat tibiae using light microscopy, transmission electron microscopy, and image processing.

We conducted a 2-year histologic and histometric evaluation of the tibial bone-titanium (Ti) implant interface in male rats. Thirty male 6-week-old rats were used in this study. They were divided into two groups: 15 for day 28 and 15 for day 730. Microscopic observation at day 28 revealed that the newly formed bone around the implant almost surrounded the implant, but fibroblastlike cells were interposed in some histologic sections. At day 730, in contrast, such cells were rarely seen, and the bone around the implant presented a lamellar structure. Transmission electron microscopic observation at day 28 disclosed mature or poorly mineralized bone near the implant; however, an electron-dense amorphous zone about 50 nm in thickness was interposed between the bone and Ti. In places slender cells were interposed between the bone and Ti. The amorphous zone was also observed at the cell-Ti interface. At day 730, a poorly mineralized layer remained in some areas between the mature bone and the titanium, and the interposed amorphous zone was still observed. Occasionally, a 200-nm-thick layer, thought to be cell remnant, was seen. As calculated in an image-processing, system analysis, the percent bone contact and the thickness and area of the surrounding bone for the Ti implant at day 28 were 43.6%, 30.4 microns, and 0.10 mm2, respectively, and those at day 730 were 89.9%, 53.5 microns, and 0.19 mm2, respectively. In summary, although the passage of time may affect bone maturity, interfacial cells remain at the bone-Ti interface as a uniform layer together with unmineralized bone.

High-precision, cost-effective cutting system for producing thin sections of oral tissues containing dental implants

A new high-precision, cost-effective cutting system, able to produce thin (20–30 μm) sections of oral tissues, containing dental implants, is presented. With this system the authors have been able to obtain, in a reproducible and consistent way, thin slides containing biomaterials and biological tissues. Very high cellular detail was possible, even at high magnifications (× 1200). Histochemical reactions (e.g. acid and alkaline phosphatases) have also been obtained in a reproducible way, without sputter ground staining. The time involved in specimen cutting was significantly reduced, and about five slides per specimen were obtained with minimal loss of tissue. In almost all cases it has been possible to eliminate the grinding process with its inherent problems, such as formation of ledging at the bone-titanium interface. With this system it was also possible to obtain thin slides of soft tissue lesions (i.e. benign mucous membrane pemphigoid).

Evolution of the bone-titanium interface on implants coated/noncoated with xenogeneic bone particles: quantitative microscopic analysis.

Titanium cylinders having a sandblasted surface were implanted in holes drilled in the internal condyles of rabbit femurs. The right side received a titanium implant coated with xenogeneic bone particles and the left side received a titanium cylinder alone and was used as control. The femoral extremities were removed at 1, 2, and 3 months postsurgery and embedded undecalcified in methacrylic resins. Sections were studied by quantitative analysis and the interface contact between bone and titanium was measured at two microscopic magnifications due to the fractal dimension of this parameter. In addition the amount of bone volume in a given referent volume provided automatically by the image analyzer was obtained. No differences could be evidenced between the two series of implants, supporting the view that xenogeneic particles were ineffective in improving the attachment of bone to the implant. The bone-to-implant interface measured at the low magnification reflected the anchorage of the implant. In both series a progressive increase upon time of the bone-to-implant interface at the highest microscopic magnification evidenced the importance of late remodeling changes responsible for bone bonding and the fractal characteristics of this interface, related to surface quality of the implant responsible for stress transfer.

Morphometric evaluation of the bone-titanium interface in an experimental animal bone graft model

Morphometric evaluation of the bone-titanium interface in an experimental animal bone graft model

Light and electron microscopic studies of bone-titanium interface in the tibiae of young and mature rats.

Bone-titanium contact was examined in young and mature rats on various days after insertion of pure titanium into the tibia. Under light microscopy, on the 14th day, lamellar mature bone was initially formed, and was seen to make direct contact with the titanium in both groups. In young rats on the 28th day, bone-titanium contact was greater than that in mature animals. On 1-micron sections, an amorphous zone 0.5-1.0 micron thick was found around the titanium, and a slender cell layer lay parallel to the implant, forming the superficial layer of the amorphous zone. Ultrastructurally, these slender cells were identified as osteoblastlike cells and made direct contact with the implant via a 20-50-nm thin amorphous zone. Below this cell layer, a collagen-containing, poorly mineralized zone was present and bordered by lamellar bone with a lamina limitans-like structure. However, this cell layer was absent in places, and therefore the thick amorphous zone without slender cell layer consisted ultrastructurally of a 20-50-nm thin amorphous zone and a poorly mineralized zone bordered by the lamellar bone. Sometimes this poorly mineralized zone was absent, and in such cases, the lamellar bone contacted the titanium by the thin amorphous zone formed on the lamina limitans-like structure. Thus, although bone was seen to make contact with the titanium implant, ultrastructurally a 20-50-nm thin amorphous zone, a slender cell layer, and/or a poorly mineralized zone were interposed between the bone and titanium.