Biomedical subjects

A Scarano

Publications and source records attributed to A Scarano.

At least 19 recordsLinked to original sources

PubMed1997

Clinical and histological results in alveolar ridge enlargement using coralline calcium carbonate.

A very important parameter during the insertion of dental implants is the amount of bone present in a site. A regenerative procedure to increase the width and the height of bone is proposed with the use of occlusive barrier membranes and biomaterials. The authors used, in six patients with deficient alveolar ridges, prior to implant insertion, Biocoral gel particles in connection with expanded polytetrafluoroethylene membranes. After 6 months it was observed that a tissue similar to mature bone had regenerated under the membrane and microscopically it was observed that the Biocoral particles were still present and almost all were completely surrounded by mature bone.

Adult↗

PubMed1997

Resorption of composite polymer-hydroxyapatite membranes: a time-course study in rabbit.

The histological findings in rabbit, concerning the resorption of a new composite hydroxyapatite-polymer membrane used in guided tissue regeneration are reported. The polymer appeared to be completely resorbed in about 4-6 months, while the inorganic component, hydroxyapatite, appeared to begin to resorb after the tenth month. The integrity of the membrane appeared to be unchanged after a 10-month period. No inflammatory cell infiltrate was present. This new type of membrane appeared to be relatively well tolerated by the host, had no significant adverse soft and hard tissue reaction, appeared to be easy to handle and had good space-maintaining capabilities. More research is certainly needed before clinical use in man.

Absorption↗

PubMed1997

Simultaneous demonstration of alkaline and acid phosphatase activity in bone, at bone-implant interfaces and at the epiphyseal growth plate in plastic-embedded undemineralized tissues.

The aim of the present study was to determine if it was possible to detect in bone, at the epiphyseal growth plate and at the bone-implant interface, the presence of alkaline and acid phosphatases using Technovit 7200 VLC resin. In the plastic-embedded specimens it was possible to observe the simultaneous presence of acid and alkaline phosphatases at the epiphyseal growth plate in the presence of intra-articular implants. The morphology of the cells positive for the phosphatases was very clear, with no apparent diffusion of the reaction product and no sputter ground staining.

Acid Phosphatase↗

PubMed1997

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 microns) 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 (x 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).

Acid Phosphatase↗

PubMed1997

Histological and histochemical analyses of acid and alkaline phosphatases around hydroxyapatite-coated implants: a time course study in rabbit.

One of the concerns pertaining to hydroxyapatite (HA)-coated dental implants is their possible dissolution over time, with ultimate loss of the implant. HA-coated dental implants were inserted medially into rabbit femoral articular knee joints. The implants were retrieved after 1 week, 1 month, 3 months and 6 months. At 1 week, many alkaline phosphatase (ALP)-positive osteoblasts were observed near the implant surface. No signs of degradation of the coating were present. At 1 month, only few ALP-positive osteoblasts were present in the marrow spaces at the interface with the coating. Many acid phosphatase (ACP)-positive cells were observed near the coating. In many marrow spaces the HA coating was reduced in thickness. At 3 months, a further reduction of the thickness of the coating, in the areas in contact with marrow spaces, was seen. Many ACP-positive cells were present in tight contact with the coating. Few ALP-positive osteoblasts were present. At 6 months, in many areas in contact with marrow spaces, the HA coating was completely resorbed. The histological and histochemical results seem to point to the existence of two types of ACP-positive cells: multinuclear, often in the process of phagocytosing HA particles, and mononuclear, with a morphology similar to osteoclasts.

Acid Phosphatase↗

PubMed1997

Immediate loading of titanium plasma-sprayed screw-shaped implants in man: a clinical and histological report of two cases.

THIS STUDY REPORTS ON THE histological findings of two immediately loaded titanium plasma-sprayed (TPS) implants, retrieved for a fracture of the abutment and for psychological reasons, after 8 and 9 months of loading, respectively. The microscopical analysis showed that mature, compact, cortical bone was present around both implants, with the bone implant contact percentage about 60 to 70%. No fibrous tissue or gaps were present at the interface. No resorption was present in the peri-implant bone. On both implants a few osteoblasts were found positive at the interface for alkaline phosphatase (ALP); while no cells positive for acid phosphatase (ACP) were present. Immediate loading can, perhaps, be used in very selected cases of good bone quality, with implants that have certain macro- (screw shape) and micro-interlocks (titanium plasma-sprayed surface) characteristics. Good results have been reported also for non-TPS surface (e.g., machined surface). More data about different designs (e.g., cylinders) or coatings (e.g., hydroxyapatite) are needed before any firm conclusions about immediate loading can be reached.

Aged↗

PubMed1997

Histologic aspects of the bone and soft tissues surrounding three titanium non-submerged plasma-sprayed implants retrieved at autopsy: a case report.

The authors report the histological features found around three non-submerged titanium plasma-sprayed implants retrieved, after a 10-month loading period, from an autopsy case. At the time of implant insertion, the clinician had noted a wide vestibular dehiscence of the central implant, and it was decided to use a bioabsorbable membrane for guided bone regeneration in this area. After specimen processing, it was possible at low magnification to observe that in the most vestibular slides, the central implant was almost completely surrounded by connective tissue, while in the most lingual slides, the quantity of bone around the implant tended to increase. The other two implants had a bone-implant contact percentage of about 60%. Only in a few areas was mineralized bone in direct contact with the metal surface, while around the major portion of the implant perimeter a layer of unmineralized, red-stained, osteoid material was present. No inflammatory infiltrate was present in the epithelium and in the supracrestal connective tissues. The fibers of this tissue had a different orientation: in the most coronal portion of the implants (smooth surface), they tended to run parallel implant's surface, while in the most apical region (plasma-sprayed surface), they tended to be arranged in a perpendicular fashion. These results, in man, were strikingly similar to those previously reported in dogs and monkeys.

Absorption↗

PubMed1996

Clinical and histologic aspects of biphasic calcium phosphate ceramic (BCP) used in connection with implant placement.

A granulate of biphasic calcium phosphate ceramic (BCP), composed of 50% hydroxyapatite and 50% beta-tricalcium phosphate, was used, in man, to fill defects resulting from cyst enucleation. The defects were covered with e-PTFE membranes, and at the re-entry procedure after six months, it was possible to see that the defects were filled by a newly formed tissue with the macroscopic features of mature bone. Smooth titanium implants were inserted in the newly regenerated tissue. Histological examination of this tissue showed that most of the particles were lined by newly formed bone. Some particles were undergoing resorption processes and were being gradually substituted by newly formed bone. No inflammatory infiltrate was present. Our results point, in conclusion, to a good biocompatibility and osteoconductivity of this material.

Adult↗

PubMed1996

Presence of multinucleated giant cells around machined, sandblasted and plasma-sprayed titanium implants: a histological and histochemical time-course study in rabbit.

A histological and histochemical evaluation was conducted in rabbit to study the presence of multinucleated giant cells (MGCs) at the interface with machined, sandblasted and plasma-sprayed titanium implants. No MGCs were observed, at any of the experimental times, around machined and sandblasted titanium surfaces. MGCs were, on the contrary, present at the interface with titanium plasma-sprayed implants at two weeks and at two months. At two weeks these cells were numerous, and in some areas, particularly around the spires, tended to line almost all the implant perimeter surface. MGCs were present in large numbers where bone was present at the interface, while, on the contrary, where there was no newly formed bone, they tended to be fewer in number and smaller in diameter. At four and eight weeks these cells tended to decrease in number. The histochemical staining for acid phosphatase (ACP) and alkaline phosphatase (ALP) showed that MGCs were negative to ACP, while many ALP-positive osteoblasts, actively secreting osteoid matrix, were in close and tight contact with the MGCs. In no case was an inflammatory infiltrate present in connection with the MGCs. The precise nature of MGCs is still not clear, but our histological and histochemical results could point to a priming effect on the activity of the osteoblasts in a similar way to the supposed role of the osteoclasts.

Animals↗

PubMed1996

Histological evaluation of the peri-implant bone around plasma-sprayed non-submerged titanium implants retrieved from man: a report of two cases.

Two cases of non-submerged implants are reported: one was removed, unloaded, after 1 year, for psychiatric reasons, and the other, after a loading period of 4 years, for a fracture of the implant. The implants and surrounding tissues were processed to obtain thin ground sections. In the first case compact lamellar bone was observed in close contact with the titanium all around the implant perimeter. No connective tissue or empty spaces were found at the bone-implant interface. Histochemical staining with von Kossa demonstrated that all the bone around the implant was highly mineralized. No areas of osteoid tissue were found at the bone-implant interface. In the implant retrieved due to fracture it was possible to observe a very high percentage of bone-implant contact.

Adsorption↗

PubMed1996

Evaluation of guided bone regeneration in rabbit tibia using bioresorbable and non-resorbable membranes.

The aim of this study was an evaluation of the possibility of bone regeneration in connection with implant placement, using a new bioresorbable membrane (Guidor Matrix Barrier) used previously in periodontal tissues regeneration. The study compared the bone regeneration obtained around Bonefit-ITI implants inserted in rabbit tibia using Guidor membranes, Gore-Tex membranes and in control sites. Microscopic analysis was performed after 6, 9 and 12 weeks. It was possible to see that the amount of bone around implants covered by Guidor and Gore-Tex membranes was roughly equivalent in all experimental sites at the 6-, 9- and 12-week time intervals. Also, all control sites healed completely. It could be concluded from this study that: (1) rabbit tibia cannot be recommended in research connected with guided bone regeneration, as all control sites healed in the same way as the test sites; (2) in no case did the presence or the degradation of the resorbable membrane prevent the formation of new bone; (3) no inflammatory reaction was present around the bioresorbable and the non-resorbable membranes; (4) bone formed in all cases on the outer surface of the non-resorbable membranes; (5) large Guidor membrane fragments were present in the 6-week specimens, while in the 12-week specimens only small fragments were recognizable; (6) Guidor membranes can be used in guided bone regeneration.

Animals↗

PubMed1996

Direct bone formation on sand-blasted titanium implants: an experimental study.

Surface modifications of an implant have been demonstrated to be important in influencing the tissue reactions around the implant. Recently, osteoblasts have been shown to be capable of laying down a mineralized matrix in direct contact with the titanium surface. The aim of the present study was to analyse the early bone responses to titanium implants with an aluminium dioxide sand-blasted surface. Microscopical analysis showed that in the first week it was possible to observe the presence of mineralized bone in direct contact with the metal surface, while in other portions of the interface, osteoblasts were seen at the implant surface. These results were confirmed in the 2 and 4 wk observations. Our results could help to explain the increased removal torque forces reported in the literature concerning sand-blasted implants.

Animals↗

PubMed1996

Microscopical aspects of failure in osseointegrated dental implants: a report of five cases.

Implant failures can be due for the most part to infections or to trauma. Different clinical pictures and microbiological findings have been reported for these two different aetiologies. The authors report the histological findings of five osseointegrated implants, removed for failure, in four patients. In some of the implants a fibrous connective tissue was present, interposed between the implant and the bone: in this tissue it was possible to find epithelial cells, even in the most apical part of the implant. These features seem to be the hallmark of the implants which failed due to surgical trauma or insertion in sites ill-fitted for such treatment. In one case a gap between the prosthetic restoration and the abutment was present, and this fact could have contributed to the implant failure. In some cases recognition of the exact aetiological factors of the failures is not possible, and, moreover, an association between the two types, infective and traumatic, is possible.

Adult↗

PubMed1996

Comparison of bone regeneration with the use of mineralized and demineralized freeze-dried bone allografts: a histological and histochemical study in man.

Mineralized (FDBA) and demineralized freeze-dried bone allografts (DFDBA) have been proposed as substitutes for autologous bone in oral surgery. The demineralization process has been shown, in rodents, to determine osteoinduction in tissues other than bone. Other investigators have reported poor clinical results, in man, with the use of DFDBA. The aim of the present study was a comparative light microscopical and histochemical analysis of bone regeneration processes, in man, with the use of FDBA and DFDBA. Our histological results showed that in DFDBA only the particles near the host bone were involved in the mineralization processes, while in FDBA even the particles that were farthest from the host bone were lined by osteoblasts, actively secreting osteoid matrix and newly formed bone. These results probably point to a more osteoconductive effect of FDBA. No osteoinduction was observed with FDBA or DFDBA.

Bone Demineralization Technique↗

PubMed1996

Histological evaluation of bone reactions to aluminium oxide dental implants in man: a case report.

Alumina implants have been shown to possess high biocompatibility. The authors present the case of an aluminium oxide ceramic implant removed because of fracture of the abutment after a 30-month loading period. It was possible to observe microscopically that the implant was covered by highly mineralized mature compact lamellar bone; no connective tissue or inflammatory cells were present at the interface. Osteocytes were observed very close to the bone-implant interface. These features indicate the good biocompatibility of the implant.

Adult↗

PubMed1996

Effects of alkaline phosphatase on bone healing around plasma-sprayed titanium implants: a pilot study in rabbits.

Alkaline phosphatase (ALP) is an enzyme thought to be important in the process of biomineralization. ALP promotes hydrolysis of phosphate containing substrates, produces orthophosphate and increases the uptake of calcium. ALP has been demonstrated recently to induce mineralization of collagen sheets in the animal body. Many factors are being investigated to try to increase the quantity of bone around dental implants. The aim of this study was an evaluation of the bone formation around dental implants used in conjunction with ALP extracted from calf intestine. Titanium plasma-sprayed implants were put for 30 min in glasses containing 500 micrograms of ALP, and then inserted into the femoral articular surface of the knee joint. The implants were retrieved after 2, 3, 4 and 8 weeks, and treated to obtain thin ground sections. The histological examination showed a higher quantity of bone trabeculae, and at 2 and 3 weeks, the presence of plump, elongated, highly stained, very active ALP-positive osteoblasts around the treated specimens. ALP seems, in the experimental conditions of this pilot study, to have a positive effect on bone formation around titanium plasma-sprayed implants.

Alkaline Phosphatase↗

PubMed1996

Bone formation inside the material interstices of e-PTFE membranes: a light microscopical and histochemical study in man.

Membranes used in guided bone regeneration (GBR) should possibly achieve a good degree of tissue integration with neighbouring connective tissues in order to obtain a mechanically stable environment necessary for successful bone and soft tissue healing. The authors observed, in a histological study of e-PTFE membranes used for GBR and retrieved from 10 patients, inside the material interstices of the membranes, in many cases the presence of connective tissue cells and collagen fibres, and in two cases the presence of bone. The presence, inside the membrane, of connective tissue and bone could help toward a tight integration between the membrane and neighbouring tissues, with the production of a biological seal.

Bone Development↗

PubMed1996

Histological evaluation of freeze-dried dura mater (FDDMA) used in guided bone regeneration (GBR): a time course study in man.

In 26 patients freeze-dried dura mater (FDDMA) membranes were used in fenestrations and dehiscences around dental implants, in implants inserted into postextraction sockets, in vertical ridge augmentation and in sinus lifting procedures. A re-entry procedure was carried out after 6, 9 and 12 months. In all patients a small portion of the membrane was removed and examined. No inflammatory infiltrate was present in the tissues around the membranes. No cells were present inside the membranes and only in the most peripheral portions was it possible to observe a few cells positive to acid phosphatase. The FDDMA membranes appeared to resorb slowly, did not seem to elicit an inflammatory reaction, and at 12 months they still appeared to play a role in cell occlusion.

Adult↗