Biomedical subjects

A Piattelli

Publications and source records attributed to A Piattelli.

At least 109 records · Page 6Linked to original sources

PubMed1997

Presence of human herpesvirus 8 variants in the oral tissues of human immunodeficiency virus-infected persons.

A 210-bp DNA segment specific to the human herpesvirus 8 (HHV-8) genome was amplified by nested polymerase chain reaction from 10 of 14 archived oral biopsy samples of HIV-positive patients in London who had no evidence of oral Kaposi's sarcoma (KS). Various oral sites were represented. Oral tissues from 20 general dental patients not known to be HIV-infected were negative. When DNA sequences of these products were compared with sequences derived from 5 oral KS tissues of AIDS patients in London and 10 skin biopsies of Italian patients with Mediterranean KS (total number of positive tissues = 25), 11 were found to be unique. DNA and predicted peptide motifs of these sequences were also different from those in 28 of 36 HHV-8-positive lesions previously reported from American and African patients. HHV-8 is tropic for the oral mucosa of HIV-infected persons, and HHV-8 variants, though diverse, may be geographically restricted.

Amino Acid Sequence↗

PubMed1997

Bacterial penetration through Resolut resorbable membrane in vitro. An histological and scanning electron microscopic study.

The aim of this study was to evaluate the characteristics of resorption and the pattern of bacterial collonisation of polyglycolic and polylactic resorbable membranes under controlled experimental conditions. A removable cobalt-chromium device was applied to the lower jaw of 5 students for a period of 4 weeks. 8 composite resin chambers were glued to the device, 4 on each side of the mouth. A small piece of PLA/PGA membrane separated the composite chambers into 2 parts. The subjects wore the devices 24 h a day, except for the time necessary for oral hygiene procedures, during which time, the structure was submerged in a 0.2% chlorexidine solution. Every week, 2 of the chambers were removed; one was processed for scanning electron microscopy, to be observed both on the external and internal surface, and the other one for light microscopy examination. Both the electron microscopic and histologic observations showed a progressive increase in the plaque layer on the external surface of the membrane during the period of observation. The light microscopy showed an early invasion of the membrane, starting about 1 week after the exposure. On all the 3- and 4-week specimens, a complete bacterial invasion over the whole thickness of the membrane was visible. After 3 weeks of plaque accumulation, bacterial colonisation of the inner portion of the membrane was detectable in all the specimens. At 3-weeks, we observed in the light microscopy group in 4 out of 5 specimens, a large reduction of the thickness of the material and small voids in the membrane structure. In 1 specimen, the membrane was no more detectable. Only in 5 specimens of the 4-week group was the membrane still recognizable, though reduced to fragments. In conclusion, once exposed to the oral cavity, the PLA/PGA membranes start to resorb in the early stages: this process concludes itself between the 3rd and 4th weeks of exposure. However, the particular conditions of the experimental design nevertheless classify this study as an in vitro, more than as an in vivo experimentation.

Adult↗

PubMed1997

Antibodies to epithelial components in oral lichen planus (OLP) associated with hepatitis C virus (HCV) infection.

Oral lichen planus (OLP) is a common chronic inflammatory disorder sometimes associated with hepatitis C virus (HCV) infection. An increased prevalence of autoimmune markers has been reported in patients with HCV infection. The aim of the present study was to determine, by conventional indirect immunofluorescence, the nature and frequency of circulating antibodies to epithelial antigens in the sera of HCV-positive patients who also have OLP. The study comprised four groups: 14 patients with OLP and HCV infection. 14 HCV-seronegative patients with OLP, 21 HCV-seropositive patients without OLP and 18 healthy controls. We found a significant association between the concomitance of OLP and HCV infection and the presence of such antibodies. It is concluded that some patients with HCV-associated OLP may have circulating antibodies to epithelial antigens, although their precise aetiological role in the development of this disease in HCV infection remains unknown.

Antiviral Agents↗

PubMed1997

HCV genotypes in Italian patients with HCV-related oral lichen planus.

Hepatitis C virus (HCV) has high genomic variability and since its discovery, six different "types" and an increasing number of "subtypes" have been reported. HCV genotype may influence viral replication, natural history of disease and response to therapy. Recently, an association between lichen planus (LP) and HCV infection has been suggested, as there is an increased frequency of HCV infection among some groups of patients with LP, in particular from Italy and Japan. These results have not been confirmed by other reports from different geographical areas. Since HCV genotypes have a heterogeneous geographical distribution, we have determined by restriction fragment length polymorphism the genotypes of 39 HCV-seropositive Italian patients with oral LP in order to establish whether the association between LP and HCV infection is influenced by HCV subtype. Of the 33 (84.6%) viraemic patients, 17 (51%) were infected by HCV subtype 1b, 9 (27%) were infected by HCV subtype 2a, 2 by subtype 1a and 1 by subtype 2b. In four cases the gel patterns were uninterpretable. This distribution of HCV genotypes is similar to that reported in recent studies of Italian HCV-seropositive patients of unknown LP status. It is concluded from this small sample that the association of lichen planus with HCV infection and its differential geographic distribution is unlikely to be due to infection by a particular HCV genotype.

Adult↗

PubMed1997

Detection of human herpesvirus-8 DNA in oral ulcer tissues of HIV-infected individuals.

OBJECTIVE: To determine the frequency of detection of human herpesvirus-8 (HHV-8) in HIV-related oral ulcers. DESIGN: Analysis of archived biopsy material. METHODS: Nested polymerase chain reaction of DNA extracts. RESULTS: HHV-8 DNA was detected in six of 10 oral ulcers of HIV-positive patients without oral Kaposi's sarcoma (KS) lesions and five of 11 oral KS lesions. The positive non-KS samples were derived from various oral sites. CONCLUSIONS: In HIV-positive people, HHV-8 can infect oral tissues that are not affected by KS.

AIDS-Related Opportunistic Infections↗

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↗

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↗