Biomedical subjects

A Scarano

Publications and source records attributed to A Scarano.

At least 37 records · Page 2Linked to original sources

PubMed1998

Benign cementoblastoma associated with an unerupted third molar.

Benign cementoblastoma is a rare lesion representing less than 1% of all odontogenic tumours. It usually affects young people and is located in the posterior jaw. In almost all cases the tumour tends to be associated with an erupted permanent tooth, most often the first molar: only rarely has an association with an impacted or deciduous tooth been reported. The authors present a case of a cementoblastoma involving an impacted third molar.

Adult↗

PubMed1998

Histologic observations on 230 retrieved dental implants: 8 years' experience (1989-1996).

The histologic examination of dental implants retrieved from humans is important to establish the causal determinants of implant failure, and to compare and validate the results obtained from animal studies. This study presents a retrospective review of the histologic features of 230 implants retrieved in an 8-year period (1989-1996). All the implants were treated to obtain thin (20 to 30 microm) ground sections. The majority of implants were retrieved because of mobility (n=56), peri-implantitis (n=54), or fractures (n=90). Peri-implantitis occurred more frequently before (n=44) than after (n=10) abutment connection. A dense fibrous connective tissue with no inflammatory cells was present at the interface in the implants retrieved for mobility; bone was found only in the most apical part. In many of these implants epithelial cells were present. The main histologic features of peri-implantitis consisted of the presence of a bone sequestrum near the implant, many bacteria present on the implant surface, and an inflammatory infiltrate (macrophages, lymphocytes, and plasma-cells) nearby. Histology showed that in the implants removed for fracture, there was a very high percentage (80 to 100%) of peri-implant bone.

Animals↗

PubMed1998

Hollow implants retrieved for fracture: a light and scanning electron microscope analysis of 4 cases.

One of the possible complications of implant treatment is the occurrence of an implant fracture. Metal fatigue and biomechanical overload seem to be the most common causes of fractured implants. This study evaluated 4 implants (3 hollow cylinders and 1 hollow screw) which fractured after a mean loading period of 2.8 years. All implants had a 4 mm diameter and had been inserted in a posterior location. In 3 cases parafunctional habits were present. In all cases a vertical resorption of the peri-implant bone was present. The endosseous portion of the implant presented always a very high bone-implant contact percentage. Scanning electron microscopic examination showed that at least one of the implant holes was involved in the fracture line; no porosities or material defects were observed on the fractured surface of the implant. In hollow implants the holes could represent a site of less resistance.

Alveolar Bone Loss↗

PubMed1998

Immediate loading of titanium plasma-sprayed implants: an histologic analysis in monkeys.

Aim of this study was to evaluate peri-implant tissue reactions to immediately loaded titanium plasma-sprayed implants in Macaca fascicularis monkeys. A total of 48 titanium plasma-sprayed implants were inserted (24 in the posterior maxilla and 24 in the posterior mandible). A metal superstructure was cemented 3 days after implant insertion on 24 implants (12 in the maxilla and 12 in the mandible) (test implants). The remaining 24 implants (12 in the maxilla and 12 in the mandible) were left unloaded (control implants). Nine months after implant placement a block section was carried out, the defect filled with non-resorbable hydroxyapatite, and all 48 implants retrieved. The implants were treated to obtain thin ground sections. Three slides were cut for each implant and examined under normal and polarized light and a morphometrical analysis done. All implants were covered by bone under light microscopy. The histomorphometrical analysis demonstrated that in test implants, the bone-implant contact percentage was 67.3% (+/-7.6%) in the maxilla, and 73.2% (+/-5.9%) in the mandible; in control implants the percentages were, respectively, 54.5% (+/-3.3%) and 55.8% (+/-6.5%). In the test implants the bone around the implants tended to have a more compact appearance. In conclusion, our study demonstrated that in test implants the bone-implant contact percentage was significantly greater than in the controls (P < 0.01) and no fibrous connective tissue was present at the interface.

Alveolar Process↗

PubMed1998

Molar root furcation: morphometric and morphologic analysis.

The objective of the present study was a morphometric and morphologic analysis of maxillary and mandibular first and second molars using three different techniques. Measurements of 207 maxillary molars (105 first and 102 second molars) and 207 mandibular molars (110 first and 97 second molars) were measured; root length, radicular trunk length (RTL), mesiodistal and buccolingual diameters (BLD) at the cementoenamel junction, inter-radicular angle (IRA) width, and furcal roof area (FRA) were recorded. No significant statistical correlations were found for most of these measurements, the only exception being the relationship between IRA/FRA, IRA/BLD in maxillary molars, and IRA/RTL in the maxillary first molar. Morphologic examination was carried out by stereo microscopy, light microscopy of undecalcified sections, and scanning electron microscopy. All of these techniques showed the complexity of the furcation area with a large number of anatomic irregularities and plaque-retentive structures that could hamper adequate cleaning during periodontal treatment.

Humans↗

PubMed1998

Microscopic and histochemical evaluation of demineralized freeze-dried bone allograft in association with implant placement: a case report.

A case report is presented in which a titanium implant was placed into a defect resulting from the extraction of an impacted tooth; the defect was filled with demineralized freeze-dried bone allograft particles without a membrane barrier. After a 6-month healing period the bone defect had completely healed and the tissue present had macroscopic features similar to mature bone. Histologic examination of this tissue showed that, in all demineralized freeze-dried bone allograft particles, mineralization nodules were scattered inside the demineralized bone; in the areas where the mineralization nodules were present, osteocyte lacunae could be observed. In the case presented, significant new vital bone formation was observed 6 months after placement of a demineralized freeze-dried bone allograft.

Acid Phosphatase↗

PubMed1998

Vertical ridge augmentation around dental implants using a membrane technique and autogenous bone or allografts in humans.

This study investigated the effect on vertical bone regeneration of the addition of demineralized freeze-dried bone allograft or autogenous bone chips to a membrane technique. Twenty partially edentulous patients with vertical jawbone deficiencies were selected for this study. The patients were divided into two groups of 10 individuals. The 10 patients of Group A received 26 Brånemark implants in 10 surgical sites. The 10 patients of Group B received 32 implants in 12 surgical sites. Fifty-two out of 58 implants (22 in Group A and 30 in Group B) extended 1.5 to 7.5 mm superior to the bone crest. Titanium-reinforced expanded polytetrafluoroethylene membranes were used to cover the implants and, before complete membrane fixation, demineralized freeze-dried bone allograft particles were condensed under the membrane in Group A, and autogenous bone chips were used in Group B. At the reentry after 7 to 11 months the membranes were removed and a small biopsy was collected from 11 sites comprehending the miniscrews. The clinical measurements from Group A demonstrated a mean vertical bone gain of 3.1 mm (SD = 0.9 mm, range 1 to 5 mm) with a mean percentage of bone gain of 124% (SD = 46.6%). The measurements from Group B showed a mean vertical bone gain of 5.02 mm (SD = 2.3 mm, range 1 to 8.5 mm) with a mean percentage of bone gain of 95% (SD = 26.8%). Histomorphometric analysis of the present study clearly demonstrated a direct correlation between the density of the pre-existing bone and the density of the regenerated bone. The mean percentage of new bone-titanium contact was from 39.1% to 63.2%, depending on the quality of the pre-existing bone. Both the clinical and histologic results indicate a beneficial effect of the addition of demineralized freeze-dried bone allograft or autogenous bone particles to vertical ridge augmentation procedures in humans.

Adult↗

PubMed1998

Implant periapical lesions: clinical, histologic, and histochemical aspects. A case report.

A new entity, the "implant periapical lesion," has recently been described. The etiology of this condition could be attributed to overheating of the bone, overloading of the implant, presence of a pre-existing infection or of residual root particles and foreign bodies in the bone, implant contamination during production or during insertion, or placement of the implant in an infected maxillary sinus. In this report, a titanium plasma-sprayed implant had been inserted into the mandible of a 53-year-old patient; after 5 months a fistula developed and periapical radiography showed a large radiolucent image around the apical portion of the implant. The implant was removed, and histologic examination showed necrotic bone and an inflammatory infiltrate inside the hollow portion of the implant. The etiology of the implant failure in this instance could be related to a fracture and vascular impairment of the bone inside the implant during insertion, to external contamination of the implant, or to the poor bone quality of the implant site.

Alveolar Process↗

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

Squamous odontogenic tumour: report of two cases.

Squamous odontogenic tumour is a benign odontogenic tumour composed of a well-differentiated squamous epithelium immersed in a fibrous connective tissue stroma. It is a rare tumour and a recent literature review yielded only 36 cases. Two cases of squamous odontogenic tumour are presented, 1 located in the maxilla and the other in the mandible: 1 of these cases showed a periodontal involvement. The radiographic picture was fairly characteristic in 1 case, with a radiolucent lesion between the roots of the second mandibular premolar and the first molar, while, in the other case, it was possible to observe the presence of a lesion located at the apex of a molar. The tumours were enucleated, and no recurrences were observed after 5 years.

Adult↗

PubMed1997

Ameloblastic fibro-odontoma: report of two cases.

Ameloblastic fibro-odontoma is a rare odontogenic tumour. It affects young people and is usually located in the posterior jaws. Two cases of this tumour are presented: both lesions had produced an asymptomatic swelling. The histology showed the presence of an odontogenic epithelium immersed in a fibrous mesenchyme; dental hard tissues were also present. No recurrences were found after 12 and 4 years from the surgical enucleation of the tumour.

Child, Preschool↗

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

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↗