Early bone formation around immediately loaded FBR-coated implants after 8, 10 and 12 weeks: a human histologic evaluation of three retrieved implants.

The surface characteristics of dental implants play an important role in the osseointegration process. Over the years implant surfaces have been subjected to different treatments, including turning, plasma spraying, coating, sand blasting, acid etching, and anodization. FBR coating is a fully resorbable calcium phosphate (CaP) coating made of brushite, obtained by electrochemical deposition on titanium plasma-sprayed (TPS) implants; this bioactive layer may be totally resorbable in 6-12 weeks and once the FBR coating has been resorbed, the newly formed bone is in contact with the roughness of the TPS surface. Human biopsy of immediately-loaded implants is certainly the most definitive means of determining the occurrence of osseointegration. In this case series the histologic and histomorphometric features of the bone-implant interface are analyzed and discussed in 3 immediately restored implants, retrieved from human subjects at 8, 10 and 12 weeks, respectively. All 3 implants were osseointegrated, with a bone to implant contact (BIC) ranging from 54.4% to 70.1%. The FBR coating was resorbed and replaced by new bone. Osteoconduction was especially noticeable between the implant threads, where the pristine bone was removed during implant bed preparation. The results suggest that the resorption window of 6-12 weeks for the CaP coating seems to be confirmed at least in the human mandible, and that immediately loaded FBR-coated implants placed in the posterior mandible can achieve osseointegration within 6-12 weeks of loading.

Clodronate combined with a surfactant (Tween 20) does not improve osseointegration: a rabbit immunohistomorphometric study.

Biphosphonates are compounds that inhibit bone reabsorption mediated by osteoclasts or the progression of periodontal disease independent on the host response to pathogenic bacteria that colonize the tooth surface. The use of biphosphonates in oral implantology is still in the experimental stage. The aim of this study is to evaluate the efficacy of a non-aminobiphosphonate combined with a surfactant to increase the ability of the drug to link to the implant and bone surfaces in the development of osseointegration in rabbits. Smooth titanium implants were devised to be used on rabbit femurs. A topical administration of clodronate combined with the surfactant (Tween 20) at different concentrations was made on the implant surface and in the implant site to increase the bone and implant adhesiveness. Placebo was given to the control group. New Zealand rabbits were used and sacrificed by CO2 after 8 weeks from the implantations. A histologic and histomorphometric analysis was carried out. Results did not show significant difference between the tests and the placebo groups. Our data are different from other similar studies obtaining statistically significant differences. These differences could depend on the efficacy of the drug used and on the procedure of application of the drug on the implant. This study demonstrates poor efficacy of clodronate applied topically to the implant and implant site during surgery to increase the percentage of osseointegration in the implant. Further studies using different fixation techniques of the drug may be necessary to confirm the present data.

Pharmacologic modulation of clodronate in local therapy of periodontal and implant inflammation.

Bisphosphonates are drugs used in the treatment of a variety of osteometabolic diseases. Recently they have been the object of research and studies on their potential application in dentistry and orthopedics. In particular, clodronate (non-aminobisphosphonates) has been studied, due to its reversible activity in comparison to apoptotic osteoclasts, the intrinsic action which stimulates the differentiation and activity of the osteoblasts, their antinflammatory activity, antipain and antioxidant action, represent the rational to estimate their clinical efficacy, for local use in dentistry, implatology, orthopaedic, rheumatology, oncology and dermatology.

Bone ingrowth into hydroxyapatite coating: a light microscopy and laser scanning microscopy study.

The authors present a description of the presence of organic material inside the hydroxyapatite (HA) coating of Calcitek implants inserted in rabbit tibia. Light microscopy showed that in all specimens a granular basophilic material which was not mineralized was present inside the thickness of the coatings. In two specimens out of 40, a bone-like substance was observed in some areas of the coating, at a distance from the interface. Laser scanning microscopy showed in all specimens an autofluorescence of osteocytes, osteoblasts, of the interface, and inside the coating. The presence of bone could either show an ability of the coating to serve as a scaffold for the newly forming osseous tissue or be a sign of an initial degradation of the HA.

Localized chronic suppurative bone infection as a sequel of peri-implantitis in a hydroxyapatite-coated dental implant.

Plaque-induced lesions can produce peri-implant bone loss with ultimate implant loss. Although the peri-implant tissues seem to be more resistant than the periodontal ones to plaque and calculus, they can produce a more extensive spread of the infection to the deeper tissues around implants. The case of a 45-year-old female patient is presented in which, over a three year period, there was a progressive loss of peri-implant bone and the formation of a periapical radiolucency with an external fistula. The implant was removed and examined with the cutting-grinding system. Microscopy examination showed that most of the hydroxyapatite (HA) was still adherent to the metal. There was a detachment in the area of the HA-titanium interface. The implant surface was almost completely covered by bacteria. Bacteria were also present in the bone medullary spaces surrounding the implant. The infection of the periodontal tissues had progressed into the alveolar bone, thus producing a localized bone infection. The cause of the implant failure is probably related to a defective connection of the abutment or to overloading of the implant due to the presence of interlocks in the prosthetic restoration.

Histochemical and confocal laser scanning microscopy study of the bone-titanium interface: an experimental study in rabbits.

The aim of our study was an analysis of the presence of an unmineralized bone matrix between mineralized bone and titanium screws in rabbit tibiae. A microscopical analysis, using a histochemical technique, was performed on the titanium-bone interface of commercially pure titanium implants placed in rabbit tibiae and harvested after 2 months. Thin ground sections of the specimens were prepared by the cutting-grinding system and stained using the von Kossa method for calcium salts and basic fuchsin for osteoid. The microscopical and morphometrical evaluation showed that bone covered about 40% (+/- 7.5%) of all implants. Mineralized bone was, however, in direct contact with the titanium surface on only about 10% of the implant, while in the remaining 30% the mineralized bone was separated from the implant by an unmineralized tissue. This basophilic, probably osteoid matrix, could represent the medium that allows the biochemical exchanges between bone and cells under the influence of the implant. A small, optically translucent gap (1-5 microns), probably an artifact, was present in some areas between titanium and bone. Confocal laser scanning microscopy (CLSM) in a fluorescent mode showed the presence at the interface of a fluorescent material. Results from our study showed that light microscopy of thin ground sections allowed a good analysis of the real nature of the titanium-bone interface. Moreover, this double staining technique showed the presence of an unmineralized bone matrix at most of the bone-titanium interface.

Microscopic and chemical analysis of bone-hydroxyapatite interface in a human retrieved implant. A case report.

The aim of the present study was a histological and chemical analysis of the bone-hydroxyapatite interface in a retrieved human implant. The implant was cut in two: one half was processed for light microscopy with the cutting grinding system, and the other for SEM analysis with EDX and a cathodoluminescence system. Bone maintained an intimate contact with the hydroxyapatite and the bonding of the hydroxyapatite with the metal was very strong. An analysis of the interface from a double staining (basic fuchsin and von Kossa) showed a non-mineralized matrix, interposed between hydroxyapatite and bone in many areas. It is possible that different microscopic features are present in different areas of the interface, however, intimate contact was observed 6 months after insertion of the implant.

Freeze-dried dura mater for guided tissue regeneration in post-extraction dental implants: a clinical and histologic study.

Soft membranes were used in 69 patients for bone regeneration around implants (blades and screws, submerged and non-submerged) placed into extraction sockets. In about 10% of the patients a prosthetic restoration was completed immediately, while in the remaining patients the prostheses were connected after a healing period of 3 to 6 months; follow-up ranged from 6 to 30 months. In 22 patients a re-entry procedure was done to evaluate the membrane and in 4 patients a bone biopsy was taken from 3 to 6 months after the placement of the membrane. In all cases the peri-implant tissues appeared clinically healthy and it was possible to see radiographically that the newly formed bone closely adapted to the implants. In most cases it was possible at 6 months re-entry to see the membrane and detach it from the underlying tissues. There was a partial dehiscence of the membrane in only 4% of the cases. After 3 months the tissue under the membrane presented macroscopical features similar to mature bone, and bone biopsies in all cases showed a spongious lamellar bone with a high level of activity and a wide band of osteoid tissue.

A light microscopy, scanning electron microscopy, and laser scanning microscopy analysis of retrieved blade implants after 7 to 20 years of clinical function. A report of 3 cases.

The aim of the present study was to evaluate by means of light microscopy, scanning electron microscopy, and laser scanning microscopy the thin ground sections of blade implants retrieved after 7 to 20 years of clinical function. Microscopic examination revealed that most of the implant surface had an intimate contact with compact lamellar bone tissue. Higher magnifications revealed the presence of a gap (1 to 5 mu) interposed between bone and implant. Many osteocytes were near the implant surface and, in many instances, osteocyte canaliculi, running from the lacunae towards the implant surface, were seen. Structures similar to bone reversal lines were observed at the edge of the bone side of the interface. The bone-titanium region is probably an area of dynamic biological activity.

A preliminary report on a method for studying the permeability of expanded polytetrafluoroethylene membrane to bacteria in vitro: a scanning electron microscopic and histological study.

The technique of guided tissue regeneration using expanded polytetrafluoroethylene (ePTFE) membranes has been shown to be effective in implant dentistry (bony defects, extremely thin alveolar ridges, and implants placed in fresh extraction sockets). One of the drawbacks associated with the use of membranes is their premature exposure with consequent bacterial contamination. The aim of this study was to examine the possibility that oral bacteria migrate through the occlusive portion of ePTFE membranes and to determine the time needed for microorganisms to pass from the outer surface to the inner surface of the membranes. A removable acrylic device was adapted to the molar-premolar region of one quadrant of the jaws in each of three volunteers. Five cylindrical teflon chambers were glued to the buccal aspect of each device. The chambers were divided into two rooms separated by the inner portion of a ePTFE membrane. The outer room was open to the oral cavity allowing plaque accumulation; the inner room was isolated from the oral cavity by the ePTFE membrane. One of the 5 chambers was completely closed and used as control. The test period lasted for 4 weeks. Every week, one chamber was removed from each device and processed for scanning electron microscopic and histologic examinations. Our study showed the possibility that oral bacteria may contaminate ePTFE membranes exposed to the oral cavity. One specimen showed partial bacterial penetration after 2 and 3 weeks, but after 4 weeks, all membrane specimens demonstrated bacterial contamination.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulp obliteration: a histological study.

Pulp obliteration is a very rare occurrence that is most frequently caused by trauma. A 58-yr-old female patient had a generalized pulp obliteration that involved all maxillary and mandibular teeth. One tooth was extracted due to an extensive carious lesion and it was processed by a cutting-grinding technique. It was possible to observe the complete obliteration of the pulp chamber, which was filled in part by reparative dentin and in part by a calcified tissue with a concentric layers structure with no tubular pattern. The root canals were almost completely obliterated by an amorphous calcified material.

A histometric comparison of smooth and rough titanium implants in human low-density jawbone.

The aim of this investigation was to conduct a comparative histometric analysis of bone-implant interface between a rough titanium surface and smooth implants in low-density human jawbone after 3, 6, and 12 months of submerged, undisturbed healing. Six adult volunteer patients undergoing standard implant placement were enrolled in this project. Each patient received 1 smooth and 1 rough implant. After 3, 6, and 12 months, the implants were harvested for histometric analysis. The values of bone-implant contact were the following: 3 months smooth 6.2%, 3 months rough 58.9%, 6 months smooth 3.55%, 6 months rough 72.9%, 12 months smooth 6.7%, and 12 months rough 76.75%. The results showed that in low-density bone the rough surface dramatically enhanced the amount of bone-to-implant contact. Because of the small number of implants examined, definite conclusions cannot be drawn, even though the statistical analysis showed significant differences between the smooth and rough groups (P = .0129; F = 76.065). Nevertheless, a trend was evident in these observations: while a rough implant surface may enhance the rate of osseointegration, it is not able to significantly change the bone density, and an implant placed low-density bone is at a higher risk of failure when occlusal loading begins.

Histomorphometric analysis of a half hydroxyapatite-coated implant in humans: a pilot study.

The aim of this study was to compare the characteristics of the bone-to-implant interface of hydroxyapatite-coated and non-coated commercially pure titanium threaded implants after different periods of healing in humans. To eliminate possible variations of the results from differences in bone quality and in surgical techniques used in the different test and control sites, only one half of each implant was coated with hydroxyapatite. The coated portions of the implants showed a tendency toward a higher percentage of direct bone-to-implant contact at each period of healing that was observed, although the small number of specimens does not allow definitive conclusions to be made.

Histochemical and laser scanning microscopy characterization of the hydroxyapatite-bone interface: an experimental study in rabbits.

An experimental study was done in rabbits to characterize the bone-hydroxyapatite (HA) interface by the use of histochemical staining for mineralized tissue and laser scanning microscopy (LSM) on undemineralized sections. Twenty HA-coated Sustain implants were placed in rabbit femurs and retrieved after 6 months. The specimens were then processed to obtain thin ground sections. In all specimens, there was intimate contact between bone and HA. In some portions, mineralized bone was in tight, direct contact with the HA, while in other portions, a basophilic unmineralized material was present between bone and HA. This material was thicker in areas with active bone formation upon the HA surface and had staining characteristics similar to the material present around the osteocyte lacunae. LSM showed a fluorescence present in many areas of the interface, in osteocyte lacunae, and inside the coating. An organic bonding between bone and HA can probably be hypothesized.

Light and confocal laser scanning microscopic evaluation of hydroxyapatite resorption patterns in medullary and cortical bone.

An animal study was conducted with unloaded blocks and hydroxyapatite (HA)-coated titanium implants. Four HA blocks were positioned in rabbit tibiae and four HA-coated titanium implants were positioned in pig tibiae. Implants were positioned so that half was placed in cortical bone and half in medullary space. Biopsy specimens were taken 4 months after implant placement for histologic evaluation. Light microscopy and confocal laser scanning microscopy demonstrated that the HA resorption rate was higher in the medullary spaces, whereas resorption was almost absent in the areas embedded in cortical bone.

The bone growing chamber: a new model to investigate spontaneous and guided bone regeneration of artificial defects in the human jawbone.

Spontaneous bone repair and regeneration of jawbone defects have been insufficiently studied in the dental literature. The present study analyzes a new human model designed to evaluate the basis for spontaneous bone regeneration in human jawbones. Hollow titanium cylinders, termed "bone growing chambers," were prepared with commercially pure titanium. Ten volunteers undergoing routine implant surgery were enlisted. A properly calibrated drill was used to prepare the bone-growing-chamber bed. The bone growing chamber was inserted inside the bone defect, and care was taken to submerge the cylinder at the level of the bone crest. After an adequate healing period, the bone growing chambers were retrieved with a small quantity of peripheral bone using a calibrated trephine bur. The retrieved specimens were processed to obtain thin undecalcified ground sections. The stable bone growing chambers showed bone tissue inside the growing space. The maturity of the regenerated bone was related to the time of removal. The bone growing chamber provides a well-defined space that is easy to prepare and to retrieve; its dimensions are always identical and it allows quantitative measurements of bone regeneration inside the chamber space.

Vertical ridge augmentation using a membrane technique associated with osseointegrated implants.

The purpose of this study was to evaluate: (1) the surgical protocol, effectiveness, and reliability for vertical ridge augmentation using a new titanium-reinforced membrane and osseointegrated implants; and (2) the histologic characteristics of the interface between a pure titanium implant and newly regenerated human bone. Five patients received 15 conical Brånemark-type implants in six different surgical sites requiring vertical augmentation. The implants protruded 4 to 7 mm from the bone crest. Pure titanium miniscrews (1.3 x 10 mm) were positioned distally to the implants, protruding 3 to 4 mm from the bone level. The implants and the miniscrews were covered with a titanium-reinforced membrane, and the flaps were sutured. Membranes were removed at the stage 2 surgery after 9 months of healing. Measurements of biopsy specimens showed a gain in bone height from 3 to 4 mm. Histologic examination showed that all retrieved miniscrews were in direct contact with bone. Histomorphometric analysis of bone contact gave a mean value of 42.5 +/- 3.6% for five of the six examined miniscrews. The results suggest that the placement of implants protruding 3 to 4 mm from the top of resorbed bone surfaces may result in vertical bone regeneration to the top of the implant cylinder and that the regenerated bone is able to osseointegrate pure titanium implants.

GBR with an e-PTFE membrane associated with DFDBA: histologic and histochemical analysis in a human implant retrieved after 4 years of loading.

As a result of a fracture to the cemented post and core, a pure titanium implant was extracted from a 54-year-old patient after 4 years of clinical loading. At implantation, the implant was positioned into an extraction socket and the defect was treated with an e-PTFE membrane associated with a DFDBA graft. At retrieval the implant underwent histologic and histochemical examination to assess the characteristics of the regenerated bone after 4 years of prosthetic loading. The implant showed an angular bony defect at the smooth collar, but the bone-implant direct contact rate seemed to be elevated in the remaining implant surface. Normal transmitted and polarized light examinations demonstrated that most of the DFDBA particles were resorbed and substituted by vital newly formed bone. The regenerated bone appeared compact with secondary osteons and large haversian canals; however, some partially mineralized remnants residuated in the spaces, between the osteons. Within the limits of this study, the authors concluded that DFDBA can be substituted by the host bone, but the rate of substitution is very slow and not complete after 4 years. From a clinical point of view, however, the load-bearing capacity of the bone regenerated with the membrane technique associated with DFDBA appeared to be similar to that of normal bone.

Qualitative and quantitative comparative study on different filling materials used in bone tissue regeneration: a controlled clinical study.

This study compared, in a human model, the ability of (1) expanded polytetrafluorethylene (e-PTFE) membranes plus bone-chip autografts, (2) e-PTFE membranes plus demineralized freeze-dried bone, (3) e-PTFE membranes plus a new form of demineralized allograft bone tissue, and (4) e-PTFE membranes alone to enhance bone regeneration around dental implants placed into recent extraction sockets. The histologic results demonstrated that, in humans, guided tissue regeneration techniques are capable of producing new bone osseointegrated with titanium dental implants. Among the graft materials, autogenous bone provided the densest and the greatest amount of bone formation, but use of demineralized freeze-dried bone and a new form of de-mineralized allogenic bone matrix also improved bone regeneration compared to membranes alone after 6 months of healing.

A histologic study of nonsubmerged titanium plasma-sprayed screw implants retrieved from a patient: a case report.

The authors report on the microscopic findings in two plasma-sprayed nonsubmerged implants retrieved from a patient 6 months after placement. One of the implants had been loaded for 3 months, while the other was left unloaded. Clinically, the peri-implant gingival tissues were in good health. The implants were sectioned according to the cutting-grinding system. Bone lined the titanium surface almost completely with 77.3% +/- 5.1% of contact in the unloaded implant and 86.5% +/- 3.3% of contact in the loaded implant. Signs of bone resorption with many macrophages and osteoclasts were present in the loaded implant, while in the unloaded implant only osteoclast resorption activity was demonstrable.