Rómulo L. Cabrini

Myxoma of the jaws

Abstract A series of twenty-one primitive myxomas of the jaw, twelve of which were of central location, has been studied. The roentgenologic, macroscopic, microscopic, and clinical data are compared with the information obtained from ninety-five cases published in the literature. Myxoma of the jaw, in our experience, is a tumor found fairly frequently, the average age of the patient being 33 years. It is found more often in the female subject and in the lower jaw. The evolution differed in each case, but, in those cases in which the tumor was not widely resected, it tended to recur.

Osteoconductivity of strontium-doped bioactive glass particles: A histomorphometric study in rats

There is accumulating evidence that strontium (Sr)-containing bioceramics have positive effects on bone tissue repair. The aims of the present study were to evaluate the osteoconductivity of Sr-doped bioactive glass (BG) particles implanted in rat tibia bone marrow, and characterize the neoformed bone tissue by SEM-energy-dispersive X-ray microanalysis. Melt-derived BGs were prepared from a base 45S5 BG. Sr-doped glass (45S5.6Sr) was prepared using 6 wt % SrO as a substitute for the CaO. Histological analysis using undecalcified sections showed that new lamellar bone had formed along the surface of both 45S5 and 45S5.6Sr BG particles within 4 weeks. To evaluate osteoconductivity, affinity indices were calculated. At 30 days after implantation, 45S5 and 45S5.6Sr BGs had almost identical affinity indices (88% +/- 7% and 87% +/- 9%; p > 0.05). Strontium was not detected in the neoformed bone tissue surrounding 45S5.6Sr BG particles. These results indicate that 45S5.6Sr BG particles are osteoconductive when implanted inside the intramedullary canal of rat tibiae, and no alterations in bone mineralization, in terms of Ca/P ratio, were observed in the neoformed bone tissue around 45S5.6Sr BG particles.

Biological performance of boron-modified bioactive glass particles implanted in rat tibia bone marrow.

The aim of the present study was to characterize the neoformed bone tissue around boron-modified bioactive glass particles implanted in rat tibia bone marrow by histologic, histomorphometric and microchemical evaluation. Melt-derived glasses were prepared from a base 45S5 bioactive glass of nominal composition (45% SiO(2), 24.5% CaO, 24.5% Na(2)O and 6% P(2)O(5) in wt%). The glass composition was modified by adding 2% wt of boron oxide (45S5.2B). Histological and histomorphometric analyses using undecalcified sections showed that at 15 days post-implantation the area of neoformed bone tissue around the 45S5.2B particles was significantly higher than control 45S5 glass. No statistically significant differences were observed at 30 days post-implantation. The thickness of osseointegrated tissue on 45S5.2B BG particles was significantly greater than on the control at all experimental time-points evaluated. A statistically significant increase in the Ca:P ratio was observed in the neoformed bone around 45S5.2B particles 15 days post-implantation. The results of the present study provide evidence that particles of boron-modified 45S5 BG (45S5.2B) enhance bone formation more than 45S5 glass when implanted into the intramedullary canal of rat tibiae.

Reactive lesions of peri-implant mucosa associated with titanium dental implants: a report of 2 cases

The aim of this study was to report 2 novel clinical cases of reactive lesions of the peri-implant mucosa associated with titanium dental implants where metal-like particles were observed histologically. In both cases, the lesions were diagnosed as epulis, based on clinical evidence. Extirpation biopsies were carried out. Case 1 was diagnosed as pyogenic granuloma and case 2 as peripheral giant cell granuloma. The presence of metal-like particles in the tissues suggests that the etiology of the lesions might be related to the corrosion process of the metal structure. This is the first case of pyogenic granuloma to be reported in association with dental implants. All clinical cases of soft tissue lesions associated with implants should be reported to contribute to the understanding of the etiology and pathogeny of these lesions.

Local effect of titanium implant corrosion: an experimental study in rats.

The aim of this study was to evaluate histologically the biological effect of pitting corrosion and to contribute clinically relevant data on the permanence of titanium metal structures used in osteosynthesis in the body. Commercially pure titanium laminar implants (control) and commercially pure titanium laminar implants with pitting corrosion (experimental) were implanted in the tibiae of rats. At 14 days post-implantation the animals were killed. The tibiae were resected, fixed, radiographed and processed for embedding in methyl methacrylate. Percentage of bone-implant contact and peri-implant bone volume were evaluated. The histological study of the titanium implants submitted to pitting corrosion showed scarce bone-implant contact, it was only present in the areas with no pitting and/or surface alterations. There was a statistically significant lower percentage of bone-implant contact in the experimental group (6%+/-4) than in the control group (26%+/-6) (p<0.001). Products of corrosion in the peri-implant bed, especially around the blood vessels and areas of bone marrow in the metal-tissue interface, were observed. The microchemical analysis of corrosion products revealed the presence of titanium. The adverse local effects caused by pitting corrosion suggest that titanium plates and grids should be used with caution as permanent fixation structures.

Titanium transport through the blood stream. An experimental study on rats.

Different metals are increasingly being used to manufacture implants, especially in the fields of dentistry and orthopedics. No metal or alloy is completely inert in vivo. The metal and the organic fluids interact releasing, for example, metallic products. Several hypotheses regarding the probable dissemination routes of titanium have been postulated, but its valence, the organic nature of its ligands and its potential toxicity have yet to be established. In a previous experimental study we demonstrated that i.p. injected titanium and zirconium oxides disseminate and deposit in organs such as liver and lung. The aim of this work was to study the eventual participation of blood cells in the transport mechanism of titanium employing the intraperitoneal injection of titanium oxide in rats as the experimental model. Twenty male Wistar rats, x: 100 g body weight, were intraperitoneally injected with 16×103 mg/kg b.w. of TiO2 in saline solution. Blood samples were taken by heart puncture at 3 and 6 months; blood smears were performed and stained with safranin evidencing monocytes containing titanium particles. The results obtained in this study would indicate that one of the ways in which titanium is disseminated is through the blood stream, via blood cells.

Exposure to Subcutaneously Implanted Uranium Dioxide Impairs Bone Formation

Abstract The introduction of uranium particles into subcutaneous tissue is a risk that affects workers engaged in the extraction, purification, and manufacture of uranium, as well as soldiers who are wounded with uranium shrapnel. The authors evaluated the effect of an internal source of an insoluble form of uranium on bone. Uranium dioxide powder (0.125 gm/kg body weight) was implanted subcutaneously in rats. After 30 days, animals exposed to uranium weighed less than controls. Bone formation activity in endochondral ossification and bone growth were also lower in the experimental animals, as evidenced by histomorphometric and morphometric methods. This is the first study to report bone damage resulting from continuous, nonlethal exposure to an insoluble compound of uranium dioxide over a period of 30 days.

Osteosarcoma of the jaw: an analysis of a series of 74 cases

To analyse a series of cases of osteosarcoma of the jaw.

Expression of ezrin and metastatic tumor antigen in osteosarcomas of the jaw

Aims and background Ezrin is a membrane-cytoskeleton linker protein involved in regulation of the growth and metastatic behavior of cancer cells. Metastatic tumor antigen (MTA) is a potential metastasis-associated protein. The objective of this study was to evaluate the expression of ezrin and MTA and their correlation with clinico-pathological features in osteosarcomas of the jaw. Methods We analyzed ezrin and MTA protein levels by immunohistochemistry in 31 osteosarcomas of the jaw. Results The mean age at diagnosis was 39 years and half of the patients were male. The mandible (n = 19) was more frequently involved than the maxilla (n = 12). The predominant histological type was chondroblastic (58.1%) and 24 patients (77.4%) were classified as having a high grade of malignancy. Immunoreactivity for ezrin was identified in 6 of 31 cases (19.4%), while 77.4% displayed expression of MTA. All ezrin-positive patients had high-grade tumors. The high-grade tumors (n = 24) had a higher rate of MTA expression (42.9% vs 87.5%). Expression of ezrin and MTA was not significantly different according to age, sex, tumor site, histological type, and tumor ploidy. Follow-up information was available for 13 patients, with a mean follow-up time of 26.7 months (range, 6–48 months). At the time of last follow-up, 5 (38.5%) patients had died of disease and 8 patients (61.5%) were alive with no evidence of disease. Expression of ezrin and MTA was not significantly different according to the follow-up data. Conclusions In our study, high-grade tumors had a higher rate of ezrin and MTA expression. This expression pattern indicates that ezrin and MTA positivity can be additional prognostic markers in osteosarcoma of the jaw.

Alveolar wound healing after x-irradiation: a histologic, radiographic, and histometric study.

Healing of extraction wounds in rats following cephalic irradiation was studied by histologic, radiographic, and histometric methods 14 days after tooth extraction. Irradiation was given at 0, 3, and 7 days after surgery in doses of either 15, 20, or 30 Gy. No significant differences were seen with the different doses given seven days post-extraction. However, socket healing was delayed when irradiation was given immediately and three days after extraction. On the basis of these observations, it is recommended that radiation not begin until at least one week after the extraction of teeth.