Biomedical subjects

Lia Rimondini

Publications and source records attributed to Lia Rimondini.

13 recordsLinked to original sources

PubMed2006

Surface tension comparison of four common root canal irrigants and two new irrigants containing antibiotic.

The aim of this study is to compare the surface tension of four common endodontic irrigants: Moltendo EDTA 17%, Cetrexidin, Smear Clear, Sodium hypochlorite 5.25%, with the surface tension of MTAD and Tetraclean. Freshly produced MilliQ water was used as a reference. All measurements were performed following the Wilhelmy plate technique, using a Cahn DCA-322 Dynamic Contact Angle Analyzer at the temperature of 22 degrees C. MilliQ water, sodium hypochlorite 5.25%, and EDTA 17% had the highest surface tension, whereas those of Cetrexedin and Tetraclean has shown the lowest surface tension value. Both new irrigants, MTAD and Tetraclean, are capable of removing the smear layer. Thanks to their low surface tension, increasing the intimate contact of irrigant solutions with the dentinal walls, they may permit deeper penetration.

Anti-Infective Agents, Local↗

PubMed2006

Temporomandibular disorders due to improper surgical treatment of mandibular fracture: clinical report.

A case of mandibular fracture surgically consolidated in a wrong position resulting in craniomandibular disorders is reported. The inadequate surgical alignment of the healed bony segments caused a malocclusion. This changed the original neuromuscular system such that compensatory mechanisms began to change the whole balance of the organism. The patient presented a mandibular crossbite, an asymmetry of the face, and extensive alteration of muscular, articular, and postural function. The bony malunion and malocclusion were treated using an interdisciplinary surgical-orthodontic treatment for correcting functional disorders and aesthetic deformity. Electromyography and computerized mandibular scanning were used to evaluate improvement of the muscular activity, during rest and function, and of the mandibular kinesiology. Timing of surgical treatment and adequate fixation and immobilization of fracture segments are very important to avoid complications such as infection, delayed union, nonunion, malunion, skeletal discrepancies, nerve injury, and (rarely) ankylosis. The surgical approach should be based on the general criteria of traumatologic therapy, restoring the original bone shape and the right occlusal relations as soon as possible.

Adult↗

PubMed2005

Physical characterization of different-roughness titanium surfaces, with and without hydroxyapatite coating, and their effect on human osteoblast-like cells.

The aim of this study was to characterize and compare various titanium (Ti) and hydroxyapatite (HA) coatings on Ti6Al4V, in view of their application on noncemented orthopedic implants. Two innovative vacuum plasma sprayed (VPS) coatings, the first of ultrahigh rough and dense Ti (PG60, Ra=74 microm) and the second of ultrahigh rough and dense Ti coated with HA (HPG60, Ra=52 microm), have been developed, and the response of osteoblast-like cells (MG-63) seeded on these new coatings was evaluated in comparison to: a low roughness and sandblasted (Ti/SA, Ra=4 microm) Ti6Al4V surface; Ti medium (TI01, Ra=18 microm), and high (TI60, Ra=40 microm) roughness VPS coatings; and the relative Ti plus HA duplex coatings (HT01, Ra=12 microm and HT60, Ra=36 microm respectively), also obtained by VPS. PG60 coating presented no open porosity, making it dense and potentially intrinsically stronger. Cell adhesion and proliferation on PG60 was similar to those of the smoothest one (Ti/SA) and adhesion on ultrahigh roughness was lower than the medium- and high-roughness coatings, whereas cell proliferation on PG60 was lower than TI60. The HA coating determined significant increases in cell proliferation at medium and high roughness levels when compared to the relative Ti coating, but not compared to the ultrahigh one; all HA-coated surfaces showed a decrease in alkaline phosphatase activity and collagen I production. Surface morphology and the HA coating strongly affected cell behavior. However, ultrahigh values of roughness are not correctly seen by cells, and the presence of HA has no improving effects.

Biocompatible Materials↗

PubMed2005

In vivo experimental study on bone regeneration in critical bone defects using an injectable biodegradable PLA/PGA copolymer.

OBJECTIVES: An assessment was done of the bone-healing rate after implantation of a polylactide/polyglycolide copolymer (PLA-PGA) 50/50 dispersed in aqueous solution of PGA and dextran, used as bone substitutes in an animal model. STUDY DESIGN: Two groups of 5 rabbits each were used. In both the femoral condyles, a critical size defect of 6x10 mm was made. On the right side PLA/PGA was inserted; the left side remained empty. Thirty and 90 days after surgery the animals were killed. RESULTS: Defects left unfilled showed no spontaneous healing after 30 and 90 days. Sites filled with experimental materials showed new bone ranging between 11.46% and 76.82% after 30 days, and 75.98% and 95.34% after 90 days. Histomorphometry showed an increase in bone maturation between day 30 and 90 in experimental sites. At day 90, no statistical difference was seen as compared to normal bone. CONCLUSION: PLA/PGA copolymer dispersed in hydrosoluble matrix seems to be suitable as osteoconductive material in critical size defects.

Absorbable Implants↗

PubMed2005

Tissue healing in implants immediately placed into postextraction sockets: a pilot study in a mini-pig model.

OBJECTIVE: A pilot in vivo study was conducted to evaluate (1) the rate of osseointegration at apical, middle, and coronal levels of oral implants immediately installed into fresh extraction sockets; (2) the maturation of the newly formed bone surrounding implants during 60 days of healing; and (3) the epithelium seal development. STUDY DESIGN: The premolars of 8 male adult mini-pigs were extracted at each mandibular site under general anesthesia. In the experimental side, Frialit-2 implants were immediately inserted. The gap between bone and implants ranged between 3 and 6 mm circumferencially. Bone specimens were obtained at 7, 15, 30, and 60 days after surgery for histologic and histomorphometric studies. Bone-to-implant contact (BIC), bone volume, trabecular thickness, number, and separation were recorded. Nonparametric exact tests were used to evaluate data. RESULTS: BIC at the coronal level was observed close to 0% at day 7 and increased up to 60% at day 60 after surgery on an average. BIC increased from 11.7% to 47.38% at middle level and from 53.4% to 67.38% at apical level from day 7 to day 60. With respect to bone maturation, in the earlier stages of healing, many thin trabeculae were observed, which, particularly at coronal level, became significantly fewer and thicker in more advanced stages. At day 60, the features of the bone were similar to those of baseline. The epithelium never migrated more than 1.8 mm apically to the top of the alveolar bone level. CONCLUSION: When implants are placed immediately into fresh extraction sockets, in minipig models osseointegration also occurs without initial bone contact.

Analysis of Variance↗

PubMed2004

Histomorphometric, ultrastructural and microhardness evaluation of the osseointegration of a nanostructured titanium oxide coating by metal-organic chemical vapour deposition: an in vivo study.

Over the past decade the increase of elderly population has determined a rise in the incidence of bone fractures, and the improvement of the implant-bone interface remains an open problem. Metal-organic chemical vapour deposition (MOCVD) has recently been proposed as a technique to coat orthopaedic and dental prostheses with metal nanostructured oxide films either through the decomposition of oxygenated compounds (single-source precursors) or the reaction of oxygen-free metal compounds with oxygenating agents. The present study was performed to assess the in vivo biocompatibility of commercially pure Ti (control material: TI/MA) implants ( psi 2 mm x 5 mm length) coated with nanostructured TiO2 films by MOCVD (Ti/MOCVD) and then inserted into rabbit femoral cortical (middhiaphysis) and cancellous (distal epiphysis) bone. Histomorphometric, ultrastructural and microhardness investigations were carried out. Four and 12 weeks after surgery, significant (p<0.0005) increases in AI of Ti/MOCVD implants were observed as compared to Ti/MA implants (distal femoral epiphysis: 4 weeks=8.2%, ns; 12 weeks=52.3%, p <0.005; femoral diaphysis: 4 weeks=20.2%, p <0.0005; 12 weeks=10.7%, p <0.005). Bone microhardness results showed significant increases for the Ti/MOCVD versus Ti/MA implants at 200 microm in the femoral diaphysis (4 weeks=14.2, p <0.005) and distal femoral epiphysis (12 weeks=14.5, p <0.01) at 4 and 12 weeks, respectively. In conclusion, the current findings demonstrate that the nanostructured TiO2 coating positively affects the osseointegration rate of commercially pure Ti implants and the bone mineralization at the bone-biomaterial interface in both cortical and cancellous bone.

Animals↗

PubMed2004

Alveolar distraction osteogenesis vs. vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: a 1-3-year prospective study on humans.

The purpose of this prospective study was to compare vertical guided bone regeneration (GBR) and vertical distraction osteogenesis (DO) for their ability in correcting vertically deficient alveolar ridges and their ability in maintaining over time the vertical bone gain obtained before and after implant placement. Eleven patients (group 1) were treated by means of vertical GBR with autogenous bone and e-PTFE membranes, while 10 patients (group 2) were treated by means of DO. In group 1, six patients received implants at the time of GBR (subgroup 1A), while five patients had implants placed at the time of membrane removal (subgroup 1B). In group 2, implants were placed at the time of distraction device removal. A total of 25 implants were placed in group 1 and 34 implants were placed in group 2 patients. Three to 5 months after implant placement, patients were rehabilitated with implant-borne dental prostheses. The following parameters were evaluated: (a) bone resorption of the regenerated ridges before and after implant placement; (b) peri-implant clinical parameters 1, 2, and 3 years after prosthetic loading of implants; (c) survival and success rates of implants. Bone resorption values before and after implant placement were significantly higher in group 1. The results suggested that both techniques may improve the deficit of vertically resorbed edentulous ridges, although distraction osteogenesis seems to be more predictable as far as the long-term prognosis of vertical bone gain is concerned. Implant survival rates as well as peri-implant clinical parameters do not differ significantly between the two groups, whereas the success rate of implants placed in group 2 patients was higher than that obtained in group 1 patients.

Adolescent↗

PubMed2003

Mechanical and histomorphometric evaluations of titanium implants with different surface treatments inserted in sheep cortical bone.

Improvement of the implant-bone interface is still an open problem and the interest in chemical modification of implant surfaces for cementless fixation has grown steadily over the past decade. Mechanical and histomorphometric investigations were performed at different times on implants inserted into sheep femoral cortical bone to compare the in vivo osseointegration of titanium screws ( X 3.5 x 7 mm length) with different surface treatments. After 8 weeks of implantation, the push-out force of anodized and hydrothermally treated implants (ANODIC) was significantly higher than that of machined implants (MACH) (36%, p<0.0005), whereas a decrease of 39% was observed for acid-etched implants (HF) when compared to other surface treatments. After 12 weeks of implantation, the push-out force values of HF implants were still significantly lower than those observed for MACH (-19%, p<0.01) and hydroxyapatite vacuum plasma-sprayed implants (HAVPS, -25%, p<0.0005), and the highest push-out force was found in HAVPS (p<0.001) implants. After 8 and 12 weeks of implantation, the AI of HF implants was significantly (p<0.05) lower ( approximately -25%) than that of MACH, HAVPS and ANODIC implants. In conclusion, results appear to confirm that there are no specific differences between ANODIC and HAVPS implants in terms of behavior. Moreover, although MACH implants show some surface contaminating agents, they appear to ensure good osseointegration within 12 weeks both mechanically and histomorphometrically, as do ANODIC and HAVPS implants. However, further studies are required to investigate bone hardness and mineralization around implants.

Animals↗

PubMed2003

Primary osteoblasts response to shock wave therapy using different parameters.

Over the past decade extracorporeal shock-wave therapy (ESWT) has been increasingly applied to orthopaedic and musculoskeletal pathologies, the aim of this study was to assess how the energy density of the shock waves and the number of impulses affect viability, differentiation and synthetic activity of osteoblasts. Primary sheep osteoblasts cultures were treated with ESWT with an electro-hydraulic shock wave generator by selecting three different energy levels (14-21-28 kV corresponding at 0.15-0.31-0.40 mJ/mm2) and two different total numbers of impulses (500, 1000) for each level. At the end of treatment, cell counts and viability were recorded. Cells were then cultivated for 48 hours starting from a concentration of 1 x 10(4) cells/ml. The biological activity and viability were evaluated at 24 and 48 hours after treatment. No cytodestructive effects were observed in Group A, while a cytodestructive effect of ESWT was seen in cultures receiving the highest energy treatments. The different shock wave treatment induced differences in MTT assays after 24 and 48 hours, in particular the highest level showed a detrimental effect on cell respiration at both experimental times as compared to the Control Group and the protein metabolism was generally depressed by ESWT with impulses at the highest energy level. After 24 hours such effect further increased with the growing number of impulses. The lowest energy level appeared to significantly improve the metabolic parameter in primary cell cultures as compared to controls when 500 impulses were selected. The current study has demonstrated that one of the most important aspects to be considered is not the total number of impulses used but the energy level of the shock waves, thus confirming that ESWT has a dose-dependent effect on cells.

Animals↗

PubMed2002

The effect of pulsed electromagnetic fields on the osteointegration of hydroxyapatite implants in cancellous bone: a morphologic and microstructural in vivo study.

Effects of pulsed electromagnetic fields (PEMFs, 75 Hz. 1.6 mT) were investigated in 12 rabbits after placing hydroxyapatite (HA) implants in their femoral condyles. Six animals were stimulated with PEMFs for three consecutive weeks, 6 h/day, while the remaining animals were sham-treated (Control Group). Rabbits were sacrificed at 3 and 6 weeks (after a 3-week non-stimulation period) for histomorphometric analysis and microhardness testing (at 200, 500, 1,000, 2,000 microm from the implant) around the implants. Histomorphometric analysis did not highlight any significant changes. On the contrary, there were statistically significant differences between the effects produced by PEMFs and Control Groups (F = 149.70, p < 0.0005) on the Affinity Index results, as well as by the experimental time of 6 and 3 weeks (F = 17.12, p = 0.001) on the same results. In PEMF-stimulated animals the microhardness (HV) values measured in trabecular bone at a distance of 200 and 500 microm from the implants, were significantly higher with respect to controls. At 6 weeks, HV values at the bone-implant interface in PEMF-stimulated animals were not significantly different with respect to normal bone, while they remained significantly lower in control animals. Both morphological and structural results demonstrated a positive therapeutic effect of PEMFs in accelerating HA osteointegration in trabecular bone.

Animals↗

PubMed2002

Characterization of bone defect repair in young and aged rat femur induced by xenogenic demineralized bone matrix.

BACKGROUND: The osteoinductive effect of some biomaterials could be affected by those systemic conditions typical of old age. The aim of the present paper was to assess the effects of age on the healing of bone defects treated with demineralized bone matrix (DBM). METHODS: The study was conducted in young (3 month old) and aged (18 month old) rats to assess the efficacy of DBM in the treatment of osseous defects in bone with limited repair capacities. A standard bone defect was created in the distal femoral condyles of male Wistar rats: the left condyle was filled with rabbit DBM granules, while the right condyle was left empty (control). Histological and microhardness analyses were performed at 30 and 45 days after implant surgery. RESULTS: After implantation of xenogenic DBM, bone healing areas of the aged and young groups showed a significant increase in the formation of newly mineralized bone relative to controls. Measurements of trabecular thickness on day 45 revealed no differences between newly formed and preexisting bone in the young group, while control values were lower. Microhardness measurements demonstrated that newly mineralized bone, either induced by DBM or not, and preexisting bone were comparable in terms of trabecular hardness after 45 days. CONCLUSIONS: In conclusion, xenogenic DBM seems to be effective in bone defect healing, since it increases mineralized tissue volume. In both DBM-filled and empty sites, age seems to have a detrimental effect on the volume of new bone formation but no influence on bone maturation.

Aging↗

PubMedDate not supplied

Titanium alloy osseointegration in cancellous and cortical bone of ovariectomized animals: histomorphometric and bone hardness measurements.

PURPOSE: Histomorphometry and microhardness measurements were performed after Ti6AI4V implantation in cancellous and cortical bone of healthy and ovariectomized animals to determine characterization of the bone-biomaterial interface in osteopenic bone. MATERIALS AND METHODS: Nine ovariectomized and 9 sham-aged rats were used. Four months later, nails were implanted in the distal femurs, and the animals were sacrificed after 8 weeks. Moreover, 3 ovariectomized and 3 sham-aged sheep were used. Twenty-four months later, screws were implanted in the tibial diaphyses and the animals were sacrificed after 12 weeks. RESULTS: Histomorphometry showed the development of osteopenia in both trabecular and cortical bone, and revealed a significant decrease in the osseointegration rate in osteopenic versus sham-aged animals for both trabecular (Affinity Index: -18.6%, P < .001) and cortical bone (Affinity Index: -23.5%, P < .005; Bone Ingrowth: -9%, P <.05). At the interfaces of the sham-aged animals in both trabecular and cortical bone, a decrease of bone microhardness was observed in comparison with preexisting bone (trabecular: -9.8%, P < .0005; cortical: -19.3%, P < .0005). In case of osteopenia, this decrease was even more extensive (trabecular: -15.5%, P < .0005; cortical: -24.7%, P < .0005). DISCUSSION: The present data suggest that bone formation around Ti6AI4V was not associated with complete bone maturation, even in healthy animals. In case of osteopenia, both bone formation and maturation were delayed. CONCLUSION: These results apparently demonstrate the utility of investigating biomaterials in osteopenic bone and the importance of careful evaluation of the healing rate and bone maturation degree around implanted biomaterials.

Alloys↗

PubMedDate not supplied

Bacterial colonization of zirconia ceramic surfaces: an in vitro and in vivo study.

PURPOSE: The microbial colonization of new ceramic materials developed for abutment manufacturing was assessed. MATERIALS AND METHODS: The materials used in these experiments were disks of 'as-fired' and 'rectified' ceramic material made of tetragonal zirconia polycrystals stabilized with yttrium (Y-TZP) and commercially pure grade 2 titanium (Ti) with corresponding eluates. They were tested in vitro with the following bacteria: Streptococcus mutans, S. sanguis, Actinomyces viscosus, A. naeslundii, and Porphyromonas gingivalis. Proliferation was evaluated on plates by inhibitory halos around pits, previously inoculated with eluates obtained from the materials. Bacterial adhesion on materials was quantified by spectrophotometric evaluation of the slime production by the same bacteria. Moreover, early bacterial adhesion was evaluated in human volunteers and observed with SEM. RESULTS: No inhibition of bacterial proliferation using eluates was observed. In vitro as-fired and rectified Y-TZP showed significantly more adherent S. mutans than did Ti disks, while S. sanguis seemed to adhere easily to Ti specimens. No differences were noted for Actinomyces spp and P. gingivalis. In vivo Y-TZP accumulated fewer bacteria than Ti in terms of the total number of bacteria and presence of potential putative pathogens such as rods. No differences were observed between rectified and as-fired Y-TZP. DISCUSSION: Overall, Y-TZP accumulates fewer bacteria than Ti. CONCLUSION: Y-TZP may be considered as a promising material for abutment manufacturing.

Actinomyces↗