Biomedical subjects

L Rimondini

Publications and source records attributed to L Rimondini.

At least 19 recordsLinked to original sources

PubMed2006

In vitro corrosion study by EIS of an equiatomic NiTi alloy and an implant quality AISI 316 stainless steel.

The electrochemical impedance spectroscopy (EIS) technique was used for the study of the electrochemical behavior of an equiatomic NiTi alloy and an implant quality AISI 316 stainless steel type ASTM F138. Experiments were carried out using four different different test solutions: phosphate buffered saline (PBS), Dulbecco minimum essential medium (MEM), MEM + fetal calf serum (FCS), and MEM + fetal calf serum + fibroblast cell (CELL). Specimens were finished to 600-grit SiC paper and were tested in conditions that did not provoke abrupt mechanical damage of the passive film. Bode-phase spectra showed the presence of two maxima and were fitted with an equivalent circuit characterized by two parallel combinations (R, resistance; CPE, constant phase element). The R(1) and CPE(1) branch was assigned to the inner compact passive film and the R(2) and CPE(2) branch to the external porous film. The resistance of the inner film R(1), roughly corresponding to the polarization resistance (R(p)), which is inversely proportional to the material's corrosion rate, increased with the immersion time and was generally greater in PBS than in other media. With the exception of FCS solution, R(1) for NiTi alloy is better or similar to that of ASTM F138.

Biocompatible Materials↗

PubMed2006

Cementoenamel junction of deciduous teeth: SEM-morphology.

AIM: The aim of this study was to investigate the cementoenamel junction of a group of 11 primary sound mandibular incisors extracted for orthodontic reasons. MATERIALS AND METHODS: Eleven caries and defect-free human inferior deciduous incisors were extracted for orthodontic reasons and the cementoenamel junction was investigated by scanning electron microscopy (SEM). The types of tissue interrelations were classified in four possible categories: 1) cementum and enamel edge-to-edge, 2) cementum overlapped by enamel, 3) enamel overlapped by cementum, 4) presence of exposed dentin between enamel and cementum. RESULTS: In our observations root cementum and enamel edge-to-edge interrelation was the most frequent feature observed in overall sample, root cementum overlapping enamel tissues was observed in more than one third of the cementoenamel junction area, exposed dentin was a rare observation. In few, small and rare areas enamel overlapped cementum. Further studies could determine statistical prevalence. CONCLUSION: The cementoenamel junction of primary teeth differs from that of permanent teeth, the scarcity of gaps between cementum and enamel, the epithelial junction at the equator of the crown and the globosity of the crown are probable protective factors toward decay susceptibility.

Child↗

PubMed2004

A new austenitic stainless steel with a negligible amount of nickel: an in vitro study in view of its clinical application in osteoporotic bone.

A biomaterial named P558 is a new austenitic stainless steel (SS) with a negligible amount of Ni (<0.20%). In previous in vitro and in vivo studies it was compared with conventional SS and Ti6Al4V and shown to be a promising material in orthopedics. Because osteoporosis is a type of pathology very often encountered in implanted patients and can be studied with in vitro models, the purpose of the present study was to evaluate P558 in vitro through comparison of normal (nOB) with osteopenic (oOB) bone-derived primary rat osteoblasts. Osteoblasts were cultured directly on P558 and polystyrene as controls for 72 h. Osteoblast proliferation, adhesion, and activity (ALP, OC, TGF-beta1, and IL-6) were evaluated at 24 and 72 h. Results demonstrated that the growth of nOB and oOB cultured on P558 was not affected negatively when compared to control. Cells on P558 did not show any alteration in terms of adhesion, proliferation, and metabolic marker production in nOB and oOB cultures, and a significant increase in ALP, OC, and TGF-beta1 production was observed. SEM images revealed no alteration in cell morphology. The current findings demonstrate that P558 promotes osteoblast proliferation, activation, and differentiation not only in normal bone, but also in osteopenic bone-derived osteoblasts.

Biocompatible Materials↗

PubMed2004

Interactions of fibroblasts with soldered and laser-welded joints.

Relatively little is known about the biocompatibility of the soldered or laser-welded joints of dental appliances. We investigated the reaction of human gingival fibroblasts cultured in vitro in direct contact with samples of soldered and laser-welded joints from orthodontic lingual arches. Contrast phase light microscopy was used to evaluate cell adhesion, morphology and proliferation after 6 and 24h and after 7 and 16 days. Scanning electron microscopy (SEM) was performed at 16 days. Our in vitro findings provide evidence that laser-welded orthodontic appliances have superior fibroblast biocompatibility.

Adult↗

PubMed2004

Poly(2-hydroxyethyl methacrylate) biomimetic coating to improve osseointegration of a PMMA/HA/glass composite implant: in vivo mechanical and histomorphometric assessments.

Bone implants must simultaneously satisfy many requirements, even though the surface properties remain a crucial aspect in osseointegration success. Since a single material with a uniform structure cannot satisfy all of these requirements, composite materials specifically designed for orthopedic or dental implant application should be envisaged. Two poly(methylmethacrylate)/hydroxyapatite composites reinforced by E-glass fibres, uncoated (PMMA/HA/Glass) and poly(2-hydroxyethyl methacrylate) (PMMA/HA/Glass+pHEMA) coated by the biomimetic method, were mechanically (push-out test) and histomorphometrically (Affinity Index, AI) investigated in an in vivo rabbit model. Cylindrical implants (diameter 2 mm x 5 mm length) were inserted into rabbit femoral cortical (mid-diaphysis) and cancellous (distal epiphysis) bone, under general anesthesia. The highest values of push-out force and ultimate shear strength were observed for the PMMA/HA/Glass at 12 weeks, which significantly (p < 0.001) differed from those of PMMA/HA/Glass+pHEMA at the same experimental time and from those of PMMA/HA/Glass at 4 weeks. At both experimental times, significantly (p < 0.0005) lower values of AI were observed in the PMMA/HA/Glass+pHEMA versus PMMA/HA/Glass (distal femoral epiphysis: 4 weeks = 33%; 12 weeks = 19%; femoral diaphysis: 4 weeks = 15%; 12 weeks = 11%). The good mechanical and histomorphometric results obtained with PMMA/HA/Glass should be followed by further evaluation of bone remodeling processes and mechanical strength around loaded PMMA/HA/Glass implants at longer experimental times. Finally, the biomimetic method applied to pHEMA needs to be further investigated in order to improve the positive effect of SBF on pHEMA and to enhance the coating adhesion.

Animals↗

PubMed2003

Histomorphometric and microhardness assessments of sheep cortical bone surrounding titanium implants with different surface treatments.

Several factors influence the healing process and the long-term mechanical stability of cementless fixed implants, such as bone remodeling and mineralization processes. Histomorphometric and bone hardness measurements were taken in implants inserted in sheep femoral cortical bone at different times to compare the in vivo osseointegration of titanium screws (diam.; 3.5 x 7 mm length) with the following surface treatments: machined (Ti-MA); acid-etched (Ti-HF); HA vacuum plasma spray (Ti-HA); and Ca-P anodization followed by a hydrothermal treatment (Ti-AM/HA). Ti-MA and Ti-AM/HA implants presented the lowest (Ra = 0.20 +/- 0.01 microm) and highest (Ra = 1.97 +/- 0.64 microm) significant (p < 0.0005) roughness value, respectively. Bone-to-implant contact of Ti-HF was lower than that of the other surface treatments at both experimental times (8 weeks: -20%, ns; 12 weeks: -30%, p < 0.01). Significant differences in MAR (mineral apposition rate) were also found between the different experimental times for Ti-MA (115%, p < 0.01) and Ti-HF (57%, p < 0.01), demonstrating that bone growth had slowed inside the screw threads of Ti-HA and Ti-AM/HA after 12 weeks. No bone microhardness changes in preexisting host bone were found, while Ti-MA showed the lowest value for the inner thread area at 8 weeks (HV(200 microm)= 49.8 +/- 3.8 HV). These findings confirm that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as Ca-P anodization followed by a hydrothermal treatment, which enhance bone interlocking and mineralization.

Animals↗

PubMed2003

Exploring the damage limitation possibilities of mineral fibres for future integrated solutions: an in vitro study.

Owing to their possible carcinogenic effect, asbestos and other silica derivatives have been identified as priority substances for risk reduction and prevention of pollution. Neutralisation procedures have thus become a topical research subject in many European and American countries. In the present study, silica derivatives (asbestos-containing and asbestos substitutes like slag wool, rock wool, cement asbestos) were fully impregnated with an epoxy resin according to the procedure used for the in situ impregnation with viscous polymeric media, which penetrate and cement the fibres in place and reduce the risk of their dispersion in air. Untreated and treated samples were used to investigate their in vitro interaction with a human continuous epithelial cell line (NCTC 2544 keratinocytes) and test the resin's efficiency in passivating the surface activity of the fibrous particulate. SEM and morpho-quantitative data evidenced that impregnation with the epoxy resin modifies the mineral fibres' bioactivity (reduction of cell adhesion and decreased spread/round cell ratio) and demonstrated the value of in vitro cell testing after passivation as a risk-assessment procedure. These tests could be used for the rapid determination of the level of passivation of new synthetic mineral fibrous materials subjected to resin impregnation.

Air Pollutants, Occupational↗

PubMed2003

In vitro behaviour of osteoblasts cultured on orthopaedic biomaterials with different surface roughness, uncoated and fluorohydroxyapatite-coated, relative to the in vivo osteointegration rate.

The effects of two surfaces with different roughness (Low Roughness, LR: Ra: 5.6-5.9 microm; High Roughness, HR: Ra: 21.5-22.5 microm), uncoated and fluorohydroxyapatite(FHA)-coated, were investigated in MG-63 osteoblasts. At 72 hours, cells proliferated on biomaterials more slowly than in the control group (p < 0.0001), the proliferation rate was higher on FHA-coated LR than uncoated HR (p = 0.037). Collagen-I production was positively affected by the LR surface (p = 0.001) as compared to controls, while it was significantly lower (p = 0.0001) in the HR surfaces. Compared to controls, LR and HR surfaces led to enhanced production of TGF-beta1, further improved by FHA (FHA-coated LR: p = 0.007; FHA-coated HR p < 0.0001 respectively). ALP, OC, IL-6 and TNF-alpha levels were not significantly different from the controls. Results suggest that collagen-I production could be useful in predicting the in vivo osteointegration rate of biocompatible biomaterials observed in previous studies.

Alkaline Phosphatase↗

PubMed2003

In vitro biocompatibility of titanium oxide for prosthetic devices nanostructured by low pressure metal-organic chemical vapor deposition.

Metal-Organic Chemical Vapor Deposition (MOCVD) has recently been proposed to coat orthopedic and dental prostheses with metal nanostructured oxide films through the decomposition of oxygenated compounds (single-source precursors) or the reaction of oxygen-free metal compounds with oxygenating agents. The present study was carried out to assess the in vitro biocompatibility in terms of cell proliferation and activation, of commercially pure Ti (control material: TI/MA) coated with nanostructured TiO2 film by MOCVD (Ti/MOCVD) using osteoblast-like cell cultures (MG-63). Evaluations were performed at 3, 7 and 14 days. Cell proliferation showed a similar trend for Ti/MA and TilMOCVD compared to polystyrene; cell number increased with time from seeding to day 7 (p < 0.005), and then decreased progressively until day 14 (ranging from -14% to -47%). The ALP level and OC production showed no significant differences between Ti/MOCVD and Ti/MA at each experimental time. Significantly higher ALP levels were found in Ti/MA at 3 days and in Ti/MOCVD at 7 and 14 days when compared to the polystyrene group. OC production decreased over time and the highest values were observed at 3 days, when it was significantly higher in the Ti/MA than in the polystyrene group (50%, p < 0.05). CICP synthesis was positively affected by the presence of Ti/MOCVD and was higher in Ti/MOCVD than in the polystyrene group. No significant differences were found between Ti/MOCVD and Ti/MA in terms of IL-6 and TGF-beta1 synthesis at any experimental time. In conclusion, the current findings demonstrate that the nanostructured TiO2 coating positively affects the osteoblast-like cell behavior in terms of cell proliferation and activity, thus confirming its high level of in vitro biocompatibility in accordance with expectations.

Biocompatible Materials↗

PubMed2002

Osseointegration of sandblasted or anodised hydrothermally-treated titanium implants: mechanical, histomorphometric and bone hardness measurements.

The improvement of the implant-bone interface is still an open problem in the long-term mechanical stability of cementless fixed implants. Mechanical, histomorphometric and bone hardness measurements were performed in sheep femoral cortical bone implants at 8 and 12 weeks from surgery to compare in vivo the osseointegration of titanium screws (psi 3.5 mm x 7 mm length) with two different surface treatments: sandblasting with 70-100 microm HA followed by acid etching with HNO3 (Group A) and Ca-P anodization followed by a hydrothermal treatment (Group B). No significant differences were found for maximum push-out force and interfacial strength between groups at both experimental times. No significant difference was observed for Bone Ingrowth between groups at both experimental times, while the Affinity Index of Group B was significantly higher (7.5%, p<0.05) and lower (10.2%, p<0.05) than that of Group A at 8 and 12 weeks, respectively. Finally, a significant increase in bone microhardness measured within 200 microm from the interface and inside the thread depth of Group A was observed between the two experimental times (p<0.05). In conclusion, present findings show that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as current tested treatments which enhance bone interlocking and mineralization.

Animals↗

PubMed2001

Self-preventive oral behavior in an Italian university student population.

BACKGROUND/AIM: The aim of this study was to assess the oral hygiene attitude and the professional preventive examination compliance in Italian university students. METHOD: A sample of 202 students attending the University of Bologna was randomly selected and interviewed about their preventive oral health attitude and compliance. All students reported using toothpaste and most of them (92.1%) brushed their teeth at least 2x a day using artificial, medium stiffness bristles. The toothbrush was generally (81.6%) replaced within 3 months. Few subjects (14.9%) said they used dental floss daily or utilized other devices. A majority of subjects (59.9%) had a dental examination within the year previous to the interview. Cluster analysis was performed. RESULTS: 4 groups were identified with homogeneous oral hygiene behavior and compliance toward professional preventive examination. Only one cluster, representing 33.6% of the sample, showed consistent frequency and modalities of oral hygiene habits. The other clusters seemed to be defective with interproximal cleaning procedures and compliance toward professional preventive care. Since the sample was characterized by a young, urbanized, homogeneous group with a high educational level and frequently from an upper middle class social status, the analysis probably gives a supra-estimation of the positive behavior. CONCLUSION: It is rational to suppose that strategies to promote dental service utilization, patients' compliance and a professional style oriented toward prevention may be useful to improve the oral health condition in the young adult Italian population.

Adult↗

PubMed2001

Internal contamination of a 2-component implant system after occlusal loading and provisionally luted reconstruction with or without a washer device.

BACKGROUND: Microbial internal contamination of oral implants has been suggested as being responsible for inflammatory infiltration of peri-implant tissues at the fixture-abutment interface of 2-stage and 2-component implant systems; it is also considered as a potential source of pathogens. The present in vivo study evaluated contamination of the inner abutment-implant retaining screw, after occlusal loading and provisionally-luted reconstruction with or without a washer device. METHODS: Eight 2-component oral implants sealed with an o-ring silicon washer device and 9 without a seal were placed in 7 patients with high oral hygiene standards. Two months after prosthetic reconstruction, crowns and internal screws were removed, and organic and inorganic screw contamination was examined by scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS) analysis. RESULTS: An amorphous and crystalline contamination, suggestive of calcium and phosphate compounds, was seen on all screw surfaces. Microbial contamination was more frequently observed in the unsealed group. No differences in bacterial morphotypes were observed between the sealed and unsealed implants. Cocci were the most representative morphotypes, while rods were seldom seen. CONCLUSIONS: In clinical situations, leakage occurs at the implant-abutment interface, although bacterial contamination is limited in patients with high oral hygiene standards. Contamination may be reduced by using a washer device.

Analysis of Variance↗

PubMed2000

Plaque removal by worn toothbrush.

BACKGROUND/AIMS: Assessment of the influence of toothbrush wear on plaque (PI) and gingival (GI) indexes. METHOD: 20 university students were recruited. PI and GI were recorded at the starting point (T0). Each subject received a toothbrush and toothpaste. 5 measurements of toothbrush were recorded to establish the initial size. The subjects were instructed to brush 3 x a day and to refrain from using other plaque removal aids. After 1 month (T1), the subjects were randomly divided into 2 groups: group no. 1 substituted the toothbrush at each monthly visit; group no. 2 brushed only with the toothbrush provided at T0. Recalls were scheduled after 1 (T1), 2 (T2) and 3 months (T3). PI, GI and an index of wear (WI) were calculated using 5 measurements of the toothbrush head and were recorded at recalls. RESULTS: From T0 to T3, a significant increase of PI was found within both groups. Non-significant differences, but very close to the significant level (p= 0.063), in group no. 1 and significant differences in group no. 2 of GI were found. No significant differences of PI and GI were found between groups. Increase of the WI was registered from T0 to T3 (p<0.001). CONCLUSION: Each individual is capable of maintaining low PI, even if using a toothbrush that shows evidence of wear.

Adult↗

PubMed2000

Micro-morphometric assessment of titanium plasma-sprayed coating removal using burs for the treatment of peri-implant disease.

This study evaluated, in vitro, the effectiveness of diamond and carbide burs, and bur sequences to remove the plasma-sprayed titanium coating from IMZ fixture surfaces. Fifteen polishing procedures were tested. They included the use of 12, 16, 30 bladed carbide burs or bevered carbide burs and 30, 15, 8 microns mean-particles-size diamond burs. The treated surfaces were evaluated with profilometer and SEM. Worn burs and titanium debris produced by the grinding were observed with SEM. All procedures produce smoother surfaces than baseline plasma-sprayed surfaces for both Ra and Rz(DIN) parameters (P < 0.001). A roughening effect of the 8 microns mean-grit diamond bur and 30 bladed burs were noted. The single carbide burs produce polished surfaces affected by waviness. Waviness was minimized by sequence or diamond bur use. The carbide bur blades were variously damaged after their use. In contrast, the grit of diamond burs was observed to be clogged by titanium debris whose amount seemed to be inversely related to the diamond mean particle size. Debris produced by diamond burs was granular whereas that produced by carbide bladed burs showed needle or flake morphology. In conclusion, the most effective titanium plasma sprayed removal were obtained by 30 microns and 15 microns mean-particle-size diamond burs, i.e. 30 microns plus 15 microns diamond burs and carbide 12 plus 16 bladed burs used in sequence.

Analysis of Variance↗

PubMed1999

GM-CSF mouthrinses in the treatment of severe oral mucositis: a pilot study.

OBJECTIVE: The aim of this open trial was to test the efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) mouthrinses as a potential treatment in reducing the duration of severe oral mucositis in patients undergoing bone marrow transplantation for hematologic malignancies. STUDY DESIGN: The study group was composed of 10 consecutive patients suffering from severe oral mucositis during bone marrow transplantation procedures. The control group was similar to the study group in age and gender and comprised 29 historical patients with similar clinical characteristics. Freshly prepared GM-CSF mouthwash (0.5 microg/mL) was administered to the study population for 1 minute 3 times per day after oral hygiene procedures, starting from the first day of mucositis until clinical improvement of oral lesions. The study and control populations were compared with respect to duration of severe oral mucositis (1-9 days, 10-19 days, > or =20 days). RESULTS: There was no statistically (chi2 exact test) significant difference in mean mucositis score between the study group (11.9+/-6.1) and the control group (16.6+/-8.9). However, the duration of severe mucositis appeared to be reduced; 60% of the GM-CSF mouthrinse patients had severe mucositis for less than 9 days, whereas only 28% of the controls had severe mucositis for less than 9 days. In addition, 10% of the GM-CSF mouthrinse patients experienced severe mucositis lasting 20 or more days, whereas 34% of the controls experienced severe mucositis for 20 or more days. CONCLUSIONS: These findings suggest that GM-CSF may reduce the duration of severe mucositis, but controlled, double-blind clinical trials are now required.

Adolescent↗

PubMed1998

Efficacy of topical mesalazine compared with clobetasol propionate in treatment of symptomatic oral lichen planus.

OBJECTIVE: To compare topically applied mesalazine (5-aminosalicylic acid) to topically applied clobetasol propionate in the treatment of patients suffering from symptomatic oral lichen planus. DESIGN: Randomized controlled longitudinal investigation. PATIENTS AND METHODS: Twenty-five out-patients suffering from oral lichen planus and referred to the Department of Oral Pathology and Oral Medicine of the University of Milan, Italy, during the period January to August 1997. Patients were randomly allocated (Group A and Group B) to treatment with mesalazine 5% or clobetasol propionate 0.05%. The drugs were topically applied twice daily for 4 weeks. Discomfort and pain were evaluated by the patient before and after treatment using a Visual Analogue Scale from zero (no pain) to 10 (extreme pain). Results were statistically evaluated by a Mann-Whitney U test. RESULTS: The two pharmacological regimens obtained partial and complete absence of symptoms. In particular, the mesalazine tested group disclosed 57% complete absence of symptoms, 21.3% partial response and 9% no response. No statistically relevant difference has been detected between the two regimens. CONCLUSIONS: The results of this preliminary study, if confirmed by further investigations, suggest that mesalazine might be considered an alternative to clobetasol propionate for treatment of symptomatic oral lichen planus.

Administration, Topical↗

PubMed1997

Attitude towards smoking and oral cancer prevention among northern Italian dentists.

The aim of the study was to evaluate the smoking habits of Northern Italian dental practitioners and their basic skills in the prevention of oral cancer. 217 of the 250 dental practitioners (86.8%) contacted by telephone from September to December 1994, answered a simple questionnaire. One third of the sample interviewed was formed by current smokers; nevertheless 60.8% of them always advise their patients to give up smoking. Only a relatively small percentage of the questioned dental practitioners (10.6%) do not examine the oral mucosa of the patients on a regular basis and 40% of responders had made a clinical diagnosis of oral cancer in the past. The lack of a specific dental education was associated with less scrupulous examination of the oral soft tissues and minor experience of cancer diagnosis. Despite their smoking habit, Northern Italian dental practitioners self-reported encouraging behaviour towards primary and secondary oral cancer prevention.

Adult↗

PubMed1997

The effect of surface roughness on early in vivo plaque colonization on titanium.

THE STUDY ASSESSES IN VIVO the surface roughness necessary to reduce plaque colonization on titanium after 24 hours. Three groups of 16 titanium disks were assigned to 3 different polishing groups (A, B, and C). The roughness was evaluated with a laser profilometer and the morphology with a scanning electron microscope (SEM). Eight volunteers were enrolled and two stents were applied in the mandibular posterior region of each. Each stent supported 3 disks, one per group. The volunteers suspended oral hygiene for 24 hours, after which the stents were removed; one was processed for evaluation of the adherent biomass and the other for SEM study. On each specimen a global area of 100 x 125 microns was examined with SEM. The area was composed of five 20 x 25 microns randomly selected fields. For each field the density of bacteria and the morphotypes were recorded. The data quoted for the global area are cumulative of those observed in the 20 x 25 microns fields. Group A had a significantly smoother surface than groups B and C. The adherent microbial biomass determination and SEM evaluation revealed that group A contained less bacteria than the roughest group. The bacterial population was composed of cocci in group A, and of cocci and short and long rods in groups B and C. We conclude that a titanium surface with Ra < or = 0.088 microns and Rz < or = 1.027 microns strongly inhibits accumulation and maturation of plaque at the 24-hour time period and that such smoothness can be achieved in transgingival and healing implant components.

Analysis of Variance↗