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Biomedical subjects

P Trisi

Publications and source records attributed to P Trisi.

At least 37 records · Page 2Linked to original sources
PubMed1994

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.

Adult↗
PubMed1994

Qualitative and quantitative comparative study on different filling materials used in bone tissue regeneration: a controlled clinical study.

This study compared, in a human model, the ability of (1) expanded polytetrafluorethylene (e-PTFE) membranes plus bone-chip autografts, (2) e-PTFE membranes plus demineralized freeze-dried bone, (3) e-PTFE membranes plus a new form of demineralized allograft bone tissue, and (4) e-PTFE membranes alone to enhance bone regeneration around dental implants placed into recent extraction sockets. The histologic results demonstrated that, in humans, guided tissue regeneration techniques are capable of producing new bone osseointegrated with titanium dental implants. Among the graft materials, autogenous bone provided the densest and the greatest amount of bone formation, but use of demineralized freeze-dried bone and a new form of de-mineralized allogenic bone matrix also improved bone regeneration compared to membranes alone after 6 months of healing.

Alveolar Bone Loss↗
PubMed1993

Bone ingrowth into hydroxyapatite coating: a light microscopy and laser scanning microscopy study.

The authors present a description of the presence of organic material inside the hydroxyapatite (HA) coating of Calcitek implants inserted in rabbit tibia. Light microscopy showed that in all specimens a granular basophilic material which was not mineralized was present inside the thickness of the coatings. In two specimens out of 40, a bone-like substance was observed in some areas of the coating, at a distance from the interface. Laser scanning microscopy showed in all specimens an autofluorescence of osteocytes, osteoblasts, of the interface, and inside the coating. The presence of bone could either show an ability of the coating to serve as a scaffold for the newly forming osseous tissue or be a sign of an initial degradation of the HA.

Animals↗
PubMed1993

Pulp obliteration: a histological study.

Pulp obliteration is a very rare occurrence that is most frequently caused by trauma. A 58-yr-old female patient had a generalized pulp obliteration that involved all maxillary and mandibular teeth. One tooth was extracted due to an extensive carious lesion and it was processed by a cutting-grinding technique. It was possible to observe the complete obliteration of the pulp chamber, which was filled in part by reparative dentin and in part by a calcified tissue with a concentric layers structure with no tubular pattern. The root canals were almost completely obliterated by an amorphous calcified material.

Dental Pulp Calcification↗
PubMed1993

A light microscopy, scanning electron microscopy, and laser scanning microscopy analysis of retrieved blade implants after 7 to 20 years of clinical function. A report of 3 cases.

The aim of the present study was to evaluate by means of light microscopy, scanning electron microscopy, and laser scanning microscopy the thin ground sections of blade implants retrieved after 7 to 20 years of clinical function. Microscopic examination revealed that most of the implant surface had an intimate contact with compact lamellar bone tissue. Higher magnifications revealed the presence of a gap (1 to 5 mu) interposed between bone and implant. Many osteocytes were near the implant surface and, in many instances, osteocyte canaliculi, running from the lacunae towards the implant surface, were seen. Structures similar to bone reversal lines were observed at the edge of the bone side of the interface. The bone-titanium region is probably an area of dynamic biological activity.

Aged↗
PubMed1993

Microscopic and chemical analysis of bone-hydroxyapatite interface in a human retrieved implant. A case report.

The aim of the present study was a histological and chemical analysis of the bone-hydroxyapatite interface in a retrieved human implant. The implant was cut in two: one half was processed for light microscopy with the cutting grinding system, and the other for SEM analysis with EDX and a cathodoluminescence system. Bone maintained an intimate contact with the hydroxyapatite and the bonding of the hydroxyapatite with the metal was very strong. An analysis of the interface from a double staining (basic fuchsin and von Kossa) showed a non-mineralized matrix, interposed between hydroxyapatite and bone in many areas. It is possible that different microscopic features are present in different areas of the interface, however, intimate contact was observed 6 months after insertion of the implant.

Calcium↗
PubMed1993

Histologic analysis of a screw implant retrieved from man: influence of early loading and primary stability.

This paper presents a histologic analysis of a one-piece screw implant put into immediate function and retrieved from man after 7 years of clinical function. Compact lamellar bone with many Haversian canals and osteons was found very near the metal surface, and the morphometric analysis of the perimeter of the implant showed a percentage of bone contact of 86.69% (SD = 5.43). The compact bone was particularly thickened around the top of the spires. At high-power magnification, it was possible to observe optically a small empty gap between bone and titanium, and the use of a histochemical stain (von Kossa) showed that mineralized bone was separated from the metal surface by a very thin layer of unmineralized red-stained material; this layer had the same staining features as the osteoid and the osteocyte lamina limitans.

Aged↗
PubMed1993

An histologic and histomorphometric study of bone reactions to unloaded and loaded non-submerged single implants in monkeys: a pilot study.

The authors present an histologic study of bone peri-implant tissue responses to non-submerged unloaded and early-loaded titanium screw implants in monkeys. Titanium screws were placed in the maxillae of 3 Macacus rhesus monkeys. One crown for each of three implants was placed after 30 days under occlusal contact, while the other three implants were left unloaded (one pair per animal). Fifteen months later, the animals were killed, and block sections were obtained to be processed for histology. Thin ground sections were excised so that histomorphometric analyses could be performed. In all samples examined, a tight contact of new bone to the implant surfaces was observed. Moreover, around the implant necks of the early-loaded screws was observed an histologic pattern of lamellar, cortical bone, thicker than in unloaded implants. Comparison with peri-implant bone of adjacent teeth showed a similarity to the surfaces of loaded peri-implant bone.

Alveolar Process↗
PubMed1993

Resorption in impacted teeth. A case report.

External resorption of the crown in embedded teeth is uncommon. The authors present a case of an impacted third molar affected by this pathology and review its etiology, pathogenesis, radiological appearance, differential diagnosis and therapy.

Female↗
PubMed1993

Light and confocal laser scanning microscopic evaluation of hydroxyapatite resorption patterns in medullary and cortical bone.

An animal study was conducted with unloaded blocks and hydroxyapatite (HA)-coated titanium implants. Four HA blocks were positioned in rabbit tibiae and four HA-coated titanium implants were positioned in pig tibiae. Implants were positioned so that half was placed in cortical bone and half in medullary space. Biopsy specimens were taken 4 months after implant placement for histologic evaluation. Light microscopy and confocal laser scanning microscopy demonstrated that the HA resorption rate was higher in the medullary spaces, whereas resorption was almost absent in the areas embedded in cortical bone.

Animals↗
PubMed1992

Supracrestal circular collagen fiber network around osseointegrated nonsubmerged titanium implants.

Eight non-submerged titanium implant screws were placed in the first upper molar edentulous sites of monkeys and subsequently kept loaded with single crown prosthesis 1 month following implantation. The animals were killed after a further 14 months and specimens including implant and adjacent teeth were processed for light and electron microscopy. Histological pictures of all samples showed the neck and most of the screw body to be surrounded by new bone. The soft tissue surrounding the implant post included pocket epithelium and supra-crestal connective tissue displaying collagen fiber bundles comparable to gingival ligaments. These peri-implant collagen fiber bundles arose from the neighboring alveolar crest, root cementum of adjacent teeth or, superficially, from the epithelium and followed a circular array around the implant neck.

Animals↗
PubMed1992

Morphodifferentiation and histodifferentiation of the dental hard tissues in compound odontoma: a study of undemineralized material.

Dental hard tissues and mineralization at the enamel surface or in the ameloblastic epithelium were studied in 10 odontomas using undemineralized material. All the specimens showed a high degree of histo- and morphodifferentiation. Dentin formed the bulk of the tumors. Much of the enamel was prismatic and apparently normal and in almost every specimen were present enamel tufts and spindles. At greater magnification it could be seen that the prisms had a very irregular orientation. Cementum was mostly acellular. Calcified material formed focally in the intercellular portion of the enamel epithelium: this material showed a concentric layers arrangement.

Ameloblasts↗
PubMed1991

Ghost cells in compound odontoma: a study of undemineralized material.

Calcifications and ghost cells at the enamel surface or in the ameloblastic epithelium were studied in twelve odontomas using undemineralized material. Calcified material formed focally in the intercellular portion of the enamel epithelium: this material showed a concentric layers arrangement. Ghost cells were present in most of the odontomas. These ghost cells were epithelial cells which enlarged, became eosinophilic and underwent an aberrant type of keratinization with the formation of large masses of keratin, that didn't stain as deeply as normal keratin. These cells often showed karyolysis of the nucleus as keratinization progressed. Frequent was the appearance of dystrophic calcifications in individual cells or clusters of cells, characterized by extremely fine basophilic granularity. The outlines of these keratinized cells could often still be discerned, even if with some difficulty.

Ameloblasts↗