ABSTRACT
The use of odontological or orthopedic metal implants requires the availability of techniques to estimate tissue response to the corrosion processes. In previous experimental studies we showed the deposition of corrosion products not only locally (Olmedo et al., Implant Dent 2003; 12: 75-80) but also systemically (Olmedo et al., J Mater Sci: Mater in Medic 2002; 13: 793-796) in organs such as liver, spleen and lung. The aim of the present study was to propose a method to quantitatively assess the tissue deposits of the corrosion products of the materials used to manufacture implants. The samples (liver and lung) were embedded in paraffin, and the histological sections were submitted to thickness standardization. The quantitative evaluation of the deposits was performed in an MPM-800 (Carl Zeiss)* microscope. The light microscopy images were digitalized and then analyzed employing the DNA-IBAS-Kontron software that allows for the identification and evaluation of cells loaded with corrosion products (objective 20x). The following end-points were assessed: total field area, number of deposits of corrosion products, partial and total area of the deposits, and the ratio between volume of the deposits and tissue volume. The method proposed serves to quantitatively evaluate, at light microscopy level, the deposition of corrosion products in tissues.
ABSTRACT
Among the local and systemic factors affecting bone repair, great interest is focused on age and gender. The aim of this work was to perform a histomorphometric evaluation of peri-implant bone healing response in male and female rats aged 1 and 3 months. Forty Wistar rats were i.p. anesthetized with xylazine and ketamine. A c.p. Ti implant (Implant Vel, Buenos Aires-Argentina) was placed in the right tibia following the method described by Cabrini et al. (Implant Dent 1993; 2:264-267). Group I: (GI, n = 10) female rats aged 1 month; Group II: (GII, n = 10) female rats aged 3 months; Group III: (GIII, n = 10) male rats aged 1 month; Group IV: (GIV, n = 10) male rats aged 3 months. All the animals were killed by ether overdose 30 days post-implantation. The tibiae were resected, radiographed and embedded in methyl-methacrylate. Ground sections perpendicular to the longer axis of the tibia were obtained and stained with toluidine blue. Percentage of osseointegration and peri-implant bone tissue volume were evaluated. No differences in peri-implant bone tissue histology were observed among groups. No statistically significant differences in peri-implant bone volume and percentage of osseointegration were observed between GII (adult females) and GIV (adult males). Peri-implant bone volume and percentage of osseointegration were markedly greater in GIV (adult males) than in GIII (young males) (14 +/- 1 mm2 and 8 +/- 2 mm2) p < 0.01 and (49 +/- 6
) p < 0.01 respectively. Using this experimental model, differences in peri-implant osteogenesis (bone volume and percentage of osseointegration) associated to gender were only observed in the young rats, and differences associated to age were found between the groups of males.
ABSTRACT
The effects of anemia on different physiological parameters have been the object of permanent study. There are no studies in the literature on the effects of this disorder on the process on bone healing. The aim of the present study was to evaluate, histologically and histomorphometrically, the process of osteogenesis in the post-extraction alvcolus of the lower molar, and in the peri-implant environment of rats. Twenty male Wistar rats (body weight (b.w.): 60 +/- 7 g) were grouped into two experimental sets. The control group (n:10) was given 0.5 mL saline solution i.p. The anemic group (n:10) was injected with 6 mg/100 g of b.w. or 3 mg/100 g b.w. phenylhidrazine, a well known hemolytic agent. Under ketamine-xylazine anesthesia the rats were submitted to extraction of the first lower molars, and to implantation in the tibia in keeping with the [quot ]laminar test[quot ] procedure. Other parameters, i.e. body weight (b.w.), food intake (FI), hematocrit (Htc), and hemoglobinemia (Hb) were monitored every 48 hs. The results showed a reduction in b.w., FI, Htc and Hb in the experimental group. The histological and histomorphometrical data show that the condition of anemia affects osteogenesis quali-quantitatively in the post-extraction alveolus and peri-implant microenvironment. Both bone reparative situations showed that ostegenesis is [quot ]sensitive[quot ] to anemia and/or the associated conditions, causing a delay in bone healing.
ABSTRACT
Corrosion phenomena would appear to play a decisive role in metallic implant long term behaviour. This study presents a method to correlate results obtained in [quot ]in vivo[quot ] and [quot ]in vitro[quot ] studies on materials used for metallic implants. Samples of titanium and copper immersed in saline solution (pH 7.4 and 5.2) were used for the [quot ]in vitro[quot ] study. Implants of these same materials were placed in rat tibiae following the method previously described by Cabrini et al. The animals were killed 14 days post-implantation, the tibiae were resected, radiographed and embedded in acrylic resin. Polarization curves revealed high corrosion in copper implants and low corrosion in titanium implants. It is important to point out that the titanium samples suffered slightly higher corrosion when immersed in a lower pH medium (pH 5.2), as in chronic inflammatory processes. A passive film was found on titanium samples as opposed to the strong corrosion observed in the copper implants. Microscopy revealed osseointegration around titanium implants and a severe inflammatory reaction with abscesses surrounding the copper implants. The method presented herein would allow to correlate [quot ]in vivo[quot ] and [quot ]in vitro[quot ] studies on corrosion in different implant materials and establish their relation with cell response.
ABSTRACT
El estudio del material del implante en relación con el tejido vivo (hueso y/o médula) es de especial importancia. En esta presentación deseamos resumir una serie de datos experimentales obtenidos del estudio de diferentes materiales y condiciones que han posibilitado disponer de una metodología que puede ser aplicada sobre un número significativo de muestras, obteniéndose medidas y datos a nivel microscópico y con valor estadístico
Subject(s)
Argentina , Bone Substitutes , Prostheses and Implants , Interphase , OsseointegrationABSTRACT
In a previous study we analyzed the behaviour of Zircalloy 4 particles employed in patients with significant loss of periodontal bone support which threatened the permanence in situ of the tooth. We herein present the results obtained after regular examination over a 2-year period of 6 patients submitted to this treatment. Our results reveal that all patients exhibited excellent gingivo-periodontal health with an increase in clinical insertion of 7 mm +/- 1 and a marked reduction in motility from 3 to 1. None of the cases featured added inflammation or expulsion of the implant material. In one of the cases it was possible to study the histology of the area by punch biopsy with a disposable needle (Sherwood-Medical). Analysis of the sample revealed the presence of bone tissue in intimate contact with implanted metallic particles of Zircalloy 4, producing osseointegration. This osseointegration would lead to filling of the periodontal bone defect. Macrophages loaded with metallic particles were found in the vicinity of particles which were not osseointegrated. These features may correspond to superficial areas related with soft tissue as observed in our study on alveolar filling in rats with the same type of particles.
ABSTRACT
Metallic dental and orthopedic implants are essential therapeutic tool. The biologic success of an implant involves intimate contact between the implant and vital bone tissue, an event which has been termed osseointegration. The aim of the present study was to study the biocompatibility and biomechanic properties of different implant materials. Zircalloy 4 metallic cones (1.8 mm base x 2 mm height) were implanted in the diaphysis of the tibiae of 6 Wistar rats (90 g body weight) under i.p. Ethyl Urethane anesthesia. The animals were killed 30 days postimplantation, the tibiae were resected, and radiographed. One side chosen at random was used for the biomechanical study; whereas the other implant of each animal was processed for embedding in methyl-methacrylate. The bond of the implanted material to bone tissue was monitored immediately after resecting the tibiae by applying an extraction force to the base of the cone via a device designed ad hoc connected to a testing machine. Histological and radiographic analyses revealed the presence of bone tissue in contact with the implant surface. A force of about 35 g was necessary to separate the implant from the bone tissue. The system proposed renders possible the study of biocompatibility in histologic terms and in terms capacity to bond to bone tissue and could be a valuable research tool and the basis for quality control of all types of material, metallic or otherwise, used in endosseous implants.
ABSTRACT
A statistical study of 1289 biopsies of children 0-15 years old, received at the Pathology Department, Dental Faculty, Buenos Aires University is presented. This number, represents 6.8
of the 18,966 biopsies received from 1960 to 1985. The histologic diagnosis were grouped into the following categories: 1) cysts, 2) tumour-like lesions, 3) inflammatory lesions, 4) neoplasms, 5) neck and head non-oral lesions, 6) dental anomalies and pulp diseases, 7) unclassified diagnosis. Cysts were the most frequent lesion (25.4
were localized in the jaws and 25
) were less frequent than the soft tissue tumour-like lesions (79.9
). Inflammatory lesions and neoplasms in children, account for 15.7
of the lesions respectively. Eighty four percent of the neoplasms were benign and 16
of all the neoplasms studied. These results indicate the need to be constantly aware of the possible presence of these clinical and radiographic lesions to allow for early diagnosis and adequate treatment.