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.

Highly crystalline MP-1 hydroxylapatite coating. Part II: In vivo performance on endosseous root implants in dogs.

The in vivo integration strength and degree of bone apposition were compared for oral endosseous implants with different plasma-sprayed hydroxylapatite (HA) coatings. Pullout strength measurements and histological analysis were used to compare two different commercially available coating from the same manufacturer. One coating does not receive a post-plasma-spray treatment and contains about 75% crystalline HA. The other coating is treated with the MP-1 process, a pressurized hydrothermal post-plasma-spray process, which increases the coating composition to approximately 95% crystalline HA without changing the coating's adhesive or cohesive strength. Comparisons were made in dogs after healing times of 3 and 15 weeks in the mandible. No significant differences were found in either case between the two coatings. Two different methods were used to determine the degree of bone apposition at 15 weeks. Both methods confirmed that the MP-1 process does not affect the osseointegration rate of plasma-sprayed HA coatings. Qualitative histology data suggest that the treated coating is more stable than the control coating, especially in cases of direct soft tissue attachment to the implant. The present data suggest that extensive dissolution of calcium phosphate components into surrounding tissue is not a necessary precursor for direct apposition of bone to HA-coated implants.

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.

Bone classification: clinical-histomorphometric comparison.

This study was aimed to correlate the hand clinical assessment of the bone quality to the histologic structure quantified by histomorphometric evaluation of bone density. Small bone biopsies were harvested in 56 patients during oral implant surgery, and were utilized for histomorphometric evaluation. The bone scoring was recorded during drilling of the implant bed, based on the hand-felt perception of the drilling resistance. The bone biopsies were then processed to obtain thin ground sections. The results of histomorphometric analysis were expressed as percentage of bony trabeculae over the total biopsy area, and the Spearman's rank correlation test, was applied to calculate the statistical differences of the clinically assessed classes of bone density and linear regression was calculated. Samples from the D1 showed a mean histomorphometric density of 76.54% +/- 16.19. Samples from D2 showed a mean value of 66.78% +/- 15.82. D3 specimens had a mean histomorphometric density scoring 59.61% +/- 19.55%. D4 samples had a mean value of 28.28% +/- 12.02. The interclass correlation analysis of the variance, showed that the clinically assessed classes D1 (P = 0.01) and D4 (P = 0.0006) were significantly different from the population. On the other hand, the classes D2 (P = 0.6) and D3 (P = 0.4) were not significantly different. This study demonstrated that hand feeling allows to distinguish, with statistically significant confidence, D1 and D4 bone, but failed to distinguish between the intermediate classes of bone quality.

A human histologic analysis of osseotite and machined surfaces using implants with 2 opposing surfaces.

A human histologic study was conducted to compare the percentage of bone-to-implant contact (BIC) at 6 months for Osseotite and machined, commercially pure titanium implant surfaces. To eliminate potential influences caused by differences in bone density at different intraoral locations, 2 mm x 5 mm, threaded, 2-surfaced titanium implants were manufactured; 1 side received the Osseotite surface modification and the opposite side maintained a machined surface. In each of 11 patients, 1 test implant was placed in the posterior maxilla (Types III and IV bone) during conventional dental implant surgery. Following 6 months of unloaded healing, the conventional implants were uncovered, and the test implants and surrounding hard tissue were removed. Histologic analysis indicated that at 6 months of unloaded healing, the mean BIC value for the Osseotite surfaces (72.96% +/- 25.13%) was statistically significantly higher (P < 0.05) than the mean BIC value for the machined surfaces (33.98% +/- 31.04%). When the BIC values for the machined and Osseotite surface pairs were ranked from high to low based on the machined BIC value range of 93% to 0%, the upper 50th percentile (20 surface pairs) mean BIC value was 86.1% +/- 16.7% for the Osseotite surfaces and 60.1% +/- 18.3% for the machined surfaces. The lower 50th percentile (19 surface pairs) mean BIC value was 59.1% +/- 25.3% for the Osseotite surfaces and 6.5% +/- 10.8% for the machined surfaces. Differences between mean BIC values for the 2 surfaces in both the upper and lower 50th percentiles were statistically significant (P < 0.05). The results of this study indicate that in the poorer quality bone typically found in the posterior maxilla, a statistically significantly higher percentage of bone contacts Osseotite surfaces when compared to opposing machined surfaces on the same implant.

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 around dental implants using a membrane technique and autogenous bone or allografts in humans.

This study investigated the effect on vertical bone regeneration of the addition of demineralized freeze-dried bone allograft or autogenous bone chips to a membrane technique. Twenty partially edentulous patients with vertical jawbone deficiencies were selected for this study. The patients were divided into two groups of 10 individuals. The 10 patients of Group A received 26 Brånemark implants in 10 surgical sites. The 10 patients of Group B received 32 implants in 12 surgical sites. Fifty-two out of 58 implants (22 in Group A and 30 in Group B) extended 1.5 to 7.5 mm superior to the bone crest. Titanium-reinforced expanded polytetrafluoroethylene membranes were used to cover the implants and, before complete membrane fixation, demineralized freeze-dried bone allograft particles were condensed under the membrane in Group A, and autogenous bone chips were used in Group B. At the reentry after 7 to 11 months the membranes were removed and a small biopsy was collected from 11 sites comprehending the miniscrews. The clinical measurements from Group A demonstrated a mean vertical bone gain of 3.1 mm (SD = 0.9 mm, range 1 to 5 mm) with a mean percentage of bone gain of 124% (SD = 46.6%). The measurements from Group B showed a mean vertical bone gain of 5.02 mm (SD = 2.3 mm, range 1 to 8.5 mm) with a mean percentage of bone gain of 95% (SD = 26.8%). Histomorphometric analysis of the present study clearly demonstrated a direct correlation between the density of the pre-existing bone and the density of the regenerated bone. The mean percentage of new bone-titanium contact was from 39.1% to 63.2%, depending on the quality of the pre-existing bone. Both the clinical and histologic results indicate a beneficial effect of the addition of demineralized freeze-dried bone allograft or autogenous bone particles to vertical ridge augmentation procedures in humans.

Guided tissue regeneration using a resorbable membrane in gingival recession-type defects: a histologic case report in humans.

This case report clinically and histologically evaluated the regeneration of gingival tissues with the use of resorbable membranes. The study was performed on a premolar for which extraction was planned. The exposed root surface was thoroughly cleaned and planed with curettes and rotary instruments, and two notches were created on the facial aspect of the exposed root surface. A resorbable Resolute membrane (WL Gore) was applied above the defect to allow for gingival regeneration. After a 6-month healing period, a block section containing the root and the regenerated tissues was removed. The biopsy specimen was processed to obtain thin ground sections. The histologic analysis demonstrated the formation of a newly generated periodontal tissue from the deepest notch toward the coronal gingiva. The newly formed tissue was composed of a coronal area of connective tissue attachment and an apical area of bone fibers and cementum. The present report histologically demonstrates the ability of a resorbable membrane to allow complete regeneration of the periodontal ligament in the coverage of gingival recessions.

Supracrestal bone regeneration around dental implants using a calcium carbonate and a fibrin-fibronectin sealing system: clinical and histologic evidence.

This study evaluated a new surgical technique for the treatment of an alveolar ridge deficiency in 11 patients. Twenty-two implants were placed, 15 of which presented with a combination of supracrestal and dehiscence kinds of defects, and seven presented only supracrestal bone loss. Surgical procedures were performed utilizing a combination of the resorbable space-making material calcium carbonate stabilized with a fibrin-fibronectin sealing system and the immediate placement of titanium dental implants. After implant placement, the mean height for supracrestal and dehiscence defects measured 2.57 +/- 1.41 mm and 2.47 +/- 1.54 mm, respectively. The defects were filled with calcium carbonate and a fibrin-fibronectin sealing system, and the flaps were sutured, avoiding any compression of the treated area. Healing was uneventful in all instances. At second-stage surgery at 6 months, a hard bone-like tissue was detectable at the defect sites. Histologic examination of four defects confirmed the presence of newly formed bone and revealed residual particles of calcium carbonate. There was a mean gain of 2.05 +/- 1.47 mm in the supracrestal defects and of 2.23 +/- 1.62 mm in the dehiscences. The results indicated that calcium carbonate, combined with a fibrin-fibronectin sealing system, is a viable alternative in the treatment of supracrestal and dehiscence bony defects.

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.

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.

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.

Bacterial penetration in vitro through GTAM membrane with and without topical chlorhexidine application. A light and scanning electron microscopic study.

Premature exposure of membrane in the oral cavity is considered the most common complication as well as a reason for failure or incomplete success of guided tissue regeneration, as the exposed membrane undergoes plaque accumulation. A method to control, or at least to reduce the bacterial invasion of the membrane allowing a delay in the membrane removal, could be of clinical interest. The purpose of the present study was to evaluate the possibility of treating, with topical chlorhexidine application, the bacterial colonization of exposed membranes. A special device was developed in order to evaluate, under an experimental environment, the bacterial colonization. This device was made from a removable acrylic denture base to which 5 gold cups were attached. The cups consisted of an internal compartment, isolated from the oral cavity by a GTAM membrane, and an external compartment exposed to the oral environment. 3 healthy subjects had this device fitted, bilaterally, in the molar-premolar region of the upper jaw. The cups of one side of each subject had 0.2% chlorhexidine gluconate gel applied 2x a day for 1 min, whereas those of the other side served as controls. 12 cups were removed after 2 weeks and the remainder removed after 1 month. The non-treated control specimens were characterized by greater amounts of plaque accumulation. In all the test sites, plaque deposits increased in thickness and quantity during the 4 weeks of the experiment. Complete invasion of the membrane and initial colonization of its internal surface were observed only in 4-week specimens. A relatively simple flora consisting mainly of cocci and short rods, was found in bacterial deposits forming under the influence of chlorhexidine, whereas in non-treated specimens, it was possible to observe a more mature and complex plaque, composed mostly of filamentous bacteria. In conclusion, topical application of chlorhexidine gel is an effective method of reducing plaque and calculus formation on the surface of GTAM membranes exposed to the oral cavity for up to 4 weeks. This study has, however, failed to demonstrate the capacity of chlorhexidine to prevent or to retard bacterial penetration through the thickness of the inner portion of the membranes.

Cementum growth in impacted teeth.

The authors present a study on the cementum of impacted teeth. It was not possible to correlate the thickness of the cementum and the age of the patients. Significant differences were found, on the other hand, between the thickness and distribution of the cementum in different teeth. Third molars showed in almost all cases an increase in the thickness of cementum.

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.

Composite resin-amalgam compound restorations.

Extensive silver amalgam restorations in premolars and molars occasionally require sacrifice of healthy unsupported enamel walls or cusps. A posterior composite resin-amalgam compound technique has been proposed to conserve these structures. Microleakage was high at the enamel-amalgam interface, moderate at the composite resin-silver amalgam and dentin-composite resin interfaces, and minimal between the inner enamel and the composite resin. Light microscopy and scanning electron microscopy demonstrated that marginal adaptation of the silver amalgam to the composite resin of the cusps was acceptable and that penetration of the inner etched enamel to the composite resin was complete.

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)