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M Piattelli

Publications and source records attributed to M Piattelli.

At least 37 records · Page 2Linked to original sources
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

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

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

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↗
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↗
PubMed1995

Abscess formation around the apex of a maxillary root form implant: clinical and microscopical aspects. A case report.

This case report describes the occurrence of an abscess in the periapical area of a root form maxillary titanium implant, with a radiolucent appearance and purulent discharge. The removal of the infected periapical tissues was carried out but the clinical symptoms of infection persisted, an attempt at guided tissue regeneration with a freeze-dried dura mater membrane notwithstanding, and it was necessary to remove the implant. The microscopical examination showed that it was possible to observe nonviable bone tissue, with absence of bone cells and areas of bone resorption in the apical portion of the implant. These microscopical features were compatible with an acute localized suppurative osteomyelitis.

Adult↗
PubMed1995

Osteoma of the mandible. A case report.

The authors present a case of osteoma of the mandible. Osteomas are solitary lesions occurring predominantly in the skull and many authors believe that most osteomas in the maxillofacial areas are reactive bone hyperplasia or advanced ossifications. In some countries the prevalence of the osteoma is about 1% of all patients in the ENT clinics. Malignant transformation has not been described and surgery of the lesion should be conservative and consist essentially of enucleation.

Adult↗
PubMed1995

Multiple impacted and erupted supernumerary premolars.

The authors present a case of a 22-years-old patient with five supernumerary impacted and erupted premolars in the mandible. This dental anomaly is relatively rare occurring from 0.14% to 0.64% of the general population. About 75% of supernumerary premolars seen to be erupted.

Adult↗
PubMed1995

Compound odontoma associated with a primary molar.

The authors describe a case of a compound odontoma located between the roots of a primary molar. It is a very unusual location. The primary tooth and the odontoma were extracted and a slide was obtained with the cutting grinding system.

Adult↗
PubMed1994

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.

Animals↗
PubMed1993

Bioactive metabolites from Sicilian marine fennel, Crithmum maritimum.

Bioactivity-guided fractionation of the lipid extract of Crithmum maritimum using the brine shrimp lethality assay led to the isolation of three bioactive compounds. Two of these are known C17 polyacetylenic metabolites, falcarinol [1] and falcarindiol [2], previously isolated from several species of the Umbelliferae and Araliaceae. The third active principle was identified as O-geranylvanillin [3], an aromatic ether described in the literature as a synthetic compound but unknown as a natural product. Cytotoxic activity of the pure compounds was significant for 1 and 2, much less intense for 3.

Alkynes↗
PubMed1991

Leiomyosarcoma of the oral cavity: report of two cases located on the lips.

The authors report 2 cases of leiomyosarcoma of the lips occurring in two elderly women. They review the incidence, the symptoms, the microscopic appearance, the differential diagnosis, the treatment and prognosis of this kind of tumor. It is a highly malignant neoplasm with a high rate of recurrences and metastases and should be treated with a radical resection and radical neck dissection when there is a metastatic node.

Aged↗