Biomedical subjects

A Scarano

Publications and source records attributed to A Scarano.

At least 55 records · Page 3Linked to original sources

PubMed1997

Bone reactions to early occlusal loading of two-stage titanium plasma-sprayed implants: a pilot study in monkeys.

This pilot study analyzed the bone reactions to early loaded titanium plasma-sprayed implants. A total of 24 titanium plasma-sprayed implants (12 in the maxilla and 12 in the mandible) (Primary Healing Implant, Legnano) were inserted into four Macaca fascicularis monkeys with instruments specially designed to obtain a precise fit of the implant in the bone socket. A metal superstructure was cemented into 10 mandibular and 10 maxillary implants 15 days after implant insertion. The four remaining implants were used as controls. Eight months after implant placement, a block section was carried out, the defect was filled with nonresorbable hydroxyapatite, and all 24 implants were retrieved. The implants were treated to obtain thin ground sections that were examined under normal and polarized light. Histologic analysis showed that bone was observed around the implant surface in all implants. Morphometric analysis demonstrated that bone lined 67.2% (SD = 3.1%) of the maxillary implant surface, and 80.71% (SD = 4.6%) of the mandibular implant surface. No differences were found in the percentage of bone-implant contact in the control implants. In the loaded implants, however, the bone around the implants had a more compact appearance. The study demonstrated that it is possible to obtain a high percentage of bone-implant contact in early loaded titanium plasma-sprayed implants.

Animals↗

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↗

PubMed1996

Vertical ridge augmentation using a resorbable membrane: a case report.

The vertical dimension may be very important clinically where anatomic structures may limit the bone height available for implant insertion. Moreover, lack of bone tissue may result in exposure of implant threads, soft tissue recession, less-than-optimal implant stability, and esthetic problems in the prosthetic reconstruction. Attempts have been made to increase the bone height with the placement of autografts and allografts on top of the ridge, but long-term results have been unsatisfactory. Recently an increase of bone in a vertical direction has been obtained in rats, rabbits, and man using expanded polytetrafluoroethylene (ePTFE) membranes. The authors present a case in which an increase of the vertical dimension of the alveolar ridge was obtained using a resorbable freeze-dried dura mater membrane in association with demineralized freeze-dried bone. After a 6-month uneventful healing period the space under the membrane was filled by a tissue with the macroscopic features of bone, and the two implants were almost covered by the newly-formed tissue. An histological examination of a retrieved sample of the newly formed tissue demonstrated the presence of mature bone. It can be concluded that a localized vertical increase of the alveolar ridge may be obtained with the use of a resorbable freeze-dried dura mater membrane.

Adult↗

PubMed1996

Juvenile hyaline fibromatosis of gingiva: a case report.

Juvenile hyaline fibromatosis is an extremely rare inherited condition, probably resulting from an inborn error of metabolism. It is characterized by cutaneous nodules, gingival hypertrophy and joint contractions. It affects children but usually it is not present at birth, and is microscopically characterized by a conspicuous hyalinization of the connective tissue.

Child↗

PubMed1996

Cellular colonization and bone formation into expanded polytetrafluoroethylene membranes: a light microscopical and histochemical time course study in the rabbit.

We report on a time course study of cellular colonization of expanded polytetrafluoroethylene (ePTFE) membranes in rabbits. Bone defects (8 mm) were prepared with low speed burs in rabbit tibial metaphyses and covered with ePTFE membranes. The membranes were retrieved after 3, 6, 9, and 12 weeks. At 3 weeks, all membranes were filled by cells and osteoid tissue: no mineralized tissue was found. Osteoblasts positive for alkaline phosphatase (ALP) were observed on the outer surface and inside the material interstices of the membrane. At 6 weeks, it was possible to observe an increase of the quantity of the osteoid material inside the membranes. At 9 weeks, bone tissue was present and it usually originated from the most external part of the membrane, and spread to the central part of the membrane. Only the central portion of this bone appeared to be completely mineralized. A sharp decrease in the number of ALP-positive osteoblasts was observed. At 12 weeks, the quantity of bone present appeared to be substantially increased. Only a small percentage of the bone inside the membrane appeared to be completely mineralized. No cells positive to acid phosphatase were observed. These histological results confirm the high biocompatibility of ePTFE membranes and the bone formation inside the ePTFE interconnected nodes could, probably, help in achieving a good biomaterial-tissue integration with predictable results in bone regeneration.

Alkaline Phosphatase↗

PubMed1996

Microscopical observations of the osseous responses in early loaded human titanium implants: a report of two cases.

The authors present the histological picture of the surrounding tissues of two screw-shaped titanium plasma-sprayed implants retrieved for a fracture of the abutment after 18 and 42 months, respectively. These two implants were loaded after two months. The microscopical examination showed that both implants were covered in a large part of the implant surface by compact, mature lamellar bone with the presence of many Haversian systems and osteons. With von Kossa staining it was possible to see that the bone at the interface with the implant was highly mineralised. No connective tissue or inflammatory cells were present at the interface.

Adolescent↗

PubMed1996

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.

Alveolar Bone Loss↗

PubMed1995

Detection of alkaline and acid phosphatases around titanium implants: a light microscopical and histochemical study in rabbits.

Alkaline phosphatase (ALP) may play a very important role in the mineralization process of bone, while acid phosphatase (ACP) is implicated in bone resorption. The aim of the present study was a histochemical characterization of ALP and ACP at the bone-implant interface after the insertion of smooth screw-shaped threaded titanium implants in rabbit tibia. In the first 3 weeks it was possible to observe a very strong positivity in the cytoplasm of osteoblasts near the implant surface. These osteoblasts surrounded islands of soft tissue or trabeculated woven bone. In the first 4 weeks a large quantity of newly formed bone originating from the periosteal and endosteal surfaces was observed; a remodeling of the cortical bone was also present. A sharp decrease of the ALP activity was observed from the third week onwards, and at 2 months it was possible to observe that the ALP and ACP activities were similar, possibly in relation to the remodelling of bone. From 2 to 6 months there were no morphological differences in the microscopical appearance of the bone around the implants. The bone was mature, compact and the new bone had staining features similar to pre-existing bone.

Acid Phosphatase↗