PubMed Health⌕ Search

Biomedical subjects

Marco Ferrari

Publications and source records attributed to Marco Ferrari.

At least 91 records · Page 5Linked to original sources
PubMed2003

Efficacy of self-etching primer on sealing margins of Class II restorations.

PURPOSE: To evaluate sealing ability of different types of restorative-adhesive combinations and to correlate etch patterns with leakage scores. MATERIALS AND METHODS: 56 molars were selected and divided randomly in four groups of 14 specimens each. A standardized adhesive Class II preparation with the cervical margin placed 1 mm below the CEJ and an occlusal reduction of 2 mm was performed. No bevels were utilized in the preparation. Four combinations of bonding system/restorative material were tested. Group 1: Excite (EX) in combination with Tetric Ceram (TC) as control; Group 2: Prompt-L-Pop (PP1) applied for 15 seconds in combination with TC; Group 3: Etch and Prime 3.0 in combination with Definite restorative material (EP); Group 4: Prompt-L-Pop (PP2) applied for 30 seconds in combination with TC. The bonding systems (Groups 1, 2 and 3) and all restorative materials were used following strictly manufacturers' instructions. The resin composite was applied following an incremental technique. Ten specimens of each group were processed for leakage test. The specimens were sectioned with a diamond saw in three different areas in mesial-distal direction. Two different operators evaluated the sections blindly for scoring leakage at cervical and occlusal margins. The highest score for the sections of each tooth area was selected for scoring and further statistical analysis. The results of the staining measurements were statistically evaluated using the Kruskal-Wallis non-parametric analysis of variance with Bonferroni alpha protection. The level of statistical significance was defined as P<0.05. The remaining four specimens of each group were kept in a 37% HCl solution for 48 hours to dissolve the dental structures and to observe the resin replica of the cavities by SEM. RESULTS: EX showed less dye penetration at occlusal margins than the other three groups, while no statistically significant differences were found at the dentin margin. The SEM observations showed rougher and more uniform enamel etch pattern when phosphoric acid (EX) was applied than that obtained with self-etching adhesive systems. Resin tags and adhesive lateral branches were noted in all groups at the dentin site.

Composite Resins↗
PubMed2003

Sealing ability of packable resin composites in class II restorations.

PURPOSE: To evaluate in Class II restorations the marginal adaptation of ten packable composite resins in combination with the proprietary adhesive system. MATERIALS AND METHODS: Standard Class II cavities were prepared in 100 extracted molars. The sample was randomly divided into ten groups. In each group, one specific packable composite was tested in association with its own adhesive: Groups: 1) Scotchbond1/FiltekP60; 2) Etch & Prime3.0/Definit; 3) Prime & Bond 2.1/SureFil; 4) Excite/Tetric Condensable; 5) Gluma/Solitaire; 6) Kerr Bonding/Prodigy Condensable; 7) One-step/Pyramid; 8) Tenure/Virtuoso; 9) Syntac/Cavex Packable; 10) Excite/Tetric flow/Tetric Ceram. The restored teeth were sectioned at three levels in the mesiodistal direction and processed for the microleakage test. On each section, the degree of dye penetration along the margins of the restoration was assessed, and the differences in the leakage given by the ten materials at either the occlusal or the cervical margin were evaluated for statistical significance. A statistical analysis was also conducted to assess the significance of the differences between the scores recorded at the occlusal margin and those measured at the cervical margin of the restoration. RESULTS: In general, the scores recorded at the cervical margin were significantly higher than those measured at the occlusal margin (p < 0.05). When all of the groups were compared for microleakage at the occlusal margin, the only significant difference revealed by the statistical analysis was that the specimens treated with Etch&Prime 3.0 and Definit (group 2) exhibited a marginal adaptation significantly worse than that seen in groups 1, 3, 4, 6, 8, 10. CONCLUSION: The application of a thin layer of a flowable composite at the cervical margin as a liner underneath the packable composite enhanced the marginal adaptation of the restoration. The use of a self-etching primer to condition the dental substrate resulted at the occlusal margin in greater microleakage than when phosphoric acid was applied.

Analysis of Variance↗
PubMed2003

Microtensile dentin bond strength of self-etching and single-bottle adhesive systems in different cavity configurations.

PURPOSE: To evaluate the bond strength of a self-etching (Clearfil SE Bond) and a single-bottle (Excite) adhesive system using two cavity configurations (C-factors 5 and 1). MATERIALS AND METHODS: Class I cavities (3 x 4 x 2.5 mm) were prepared in 28 extracted human molars using diamond burs under water cooling. Teeth were divided into 4 groups: G1: Excite, C-factor 5; G2: Excite, C-factor 1; G3: Clearfil, C-factor 5; G4: Clearfil, C-factor 1. To determine C-factor 5, systems were applied to all cavity walls according to the manufacturers' instructions (5 bonded, 1 unbonded). For C-factor 1, lateral walls were isolated using nail varnish, and adhesive systems were only applied to the pulpal floor (5 unbonded, 1 bonded). Cavities were restored using Tetric Ceram composite resin (Ivoclar/Vivadent), and bulk light cured for 40 s (500 mW/cm2). Teeth were stored in distilled water for 24 h at 37 degrees C, and then sectioned using a diamond disk, yielding stick-shaped specimens with a bonded area of approximately 0.8 mm2. Specimens were submitted to the microtensile bond test at a rate of 1 mm/min speed in a universal testing machine. RESULTS: Resin-dentin bond strengths (MPa) were submitted to ANOVA and Tukey's tests (p < 0.05) [number of specimens]: G1 = 35.8b [43]; G2 = 48.9a [55]; G3 = 45.9a [60]; G4 = 49.0a [53]. There was no statistically significant difference between adhesive systems for C-factor 1. For C-factor 5, Clearfil SE Bond produced higher values when compared to the other group. CONCLUSION: Changes in C-factor only affected the total-etch adhesive system tested. This may be a result of the different filler volume in the self-etching system, and not of the bonding technique itself.

Acid Etching, Dental↗
PubMed2003

Microleakeage and resin cement film thickness of luted all-ceramic and gold electroformed porcelain-fused-to-metal crowns.

PURPOSE: The purpose of this study was to evaluate the sealing ability of single-unit all-ceramic and gold-electroformed crowns luted with a resin cement under laboratory conditions. MATERIALS AND METHODS: Thirty extracted maxillary premolars were selected. Standardized abutments were prepared for full-crown restorations with cervical margins located 1 mm below the cementoenamel junction. Samples were divided into two groups (n = 15) based on type of restorative system: Group 1: a heat-pressed all-ceramic system (IPS Empress 2, Ivoclar-Vivadent); Group 2: a gold-electroformed porcelain-fused-to-metal system (Gramm Technik). Crowns were luted with Excite DSC bonding system (Ivoclar-Vivadent) and Variolink II resin cement (Ivoclar-Vivadent) following manufacturer's instructions. After luting procedures and 700 thermal cycles (5 degrees C and 55 degrees C, 1 min dwell time), 20 specimens (n = 10 per group) were randomly selected and processed for microleakage evaluation at cervical sites. The remaining specimens (n = 5 per group) were prepared for SEM investigation on film thickness. Microleakage and film thickness data were statistically evaluated using the Mann-Whitney U-test (p < 0.05). RESULTS: Fifty percent of group 1 and 60% of group 2 samples showed leakage. For group 1, dye penetration was mostly observed between metal and resin material, while group 2 specimens showed leakage mainly between ceramic margins and resin cement. Samples from group 1 showed a cement thickness of 82 microm, while 71 microm was found for group 2. Statistically significant differences were not found between samples from the two groups. CONCLUSION: Regarding microleakage and film thickness, both restorative systems evaluated in this study performed similarly.

Bicuspid↗
PubMed2002

Lateral frontal cortex oxygenation changes during translation and language switching revealed by non-invasive near-infrared multi-point measurements.

The organisation of language in the brain of multilingual people remains controversial. Using a high temporal resolution 12-channel near-infrared continuous wave spectroscopy system, we have demonstrated that it is possible to monitor non-invasively, comfortably and, without the interferences due to intrinsic limitations of positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), cortical oxygenation changes in the Broca's area in response to translation of short sentences and language switching. Eight Dutch students proficient in English translated aloud from their native language into English or vice versa or alternating (switching) short visually presented sentences. These tasks provoked, in the left inferior frontal cortex which includes the Broca's area, a consistent and incremental rise in oxyhaemoglobin accompanied by a smaller decrease in deoxyhaemoglobin. The investigated cortical areas surrounding the Broca's area showed no uniform and consistent oxygenation changes upon the three different translation tasks. These results confirm that Broca's area is involved in the translation process and its so called activation is unaffected by the direction of the translation. In addition, these results strengthen the role of near-infrared multi-point measurements as a powerful tool for investigating the spatial and temporal features of the cortical oxygenation changes during language processing.

Adult↗
PubMed2002

Ultrastructural localization of tyrosine hydroxylase in human peripheral blood mononuclear cells: effect of stimulation with phytohaemagglutinin.

Using immunocytochemistry coupled to fluorescence and electron microscopy, we investigated the expression and ultrastructural localization of tyrosine hydroxylase (TH, EC 1.14.16.2), the rate-limiting enzyme in the biosynthesis of catecholamines, in human peripheral blood mononuclear cells (PBMCs), with PC12 cells as positive controls. In unstimulated PBMCs, TH-specific immunoreactivity was localized to the plasma membrane. However, after stimulation with the polyclonal mitogen phytohaemagglutinin (PHA), TH immunoreactivity was almost completely localized to electron-dense cytoplasmic granules, which resembled those found in PC12. TH-positive granules, however, were larger (300-500 nm) than in PC12 cells (100-200 nm). Flow cytometry analysis of TH expression showed about 46-50% positive cells in unstimulated PBMCs and in PHA-stimulated PBMCs in the G0/G1 phase of the cell cycle, but more than 80% positive cells in PHA-stimulated PBMCs in the S+G2/M phase. In agreement with previous observations, PHA stimulation also induced de novo expression of TH mRNA as well as increased intracellular catecholamine content, suggesting the occurrence of TH upregulation at the level of both gene expression and enzyme activity. The ultrastructural localization of TH in human PBMCs seems therefore regulated by cell stimulation and related to the functional activity of the enzyme.

Humans↗
PubMed2002

An SEM evaluation of several adhesive systems used for bonding fiber posts under clinical conditions.

OBJECTIVES: The objective of this investigation was to evaluate the effectiveness of three 'one-bottle' and two 'three step' adhesive systems (as controls) in the formation of resin tags, adhesive lateral branches and a resin dentin interdiffusion zone (RDIZ) when used to bond fiber posts under clinical conditions. This study was performed using standardized SEM observations and scoring resin tag formation and density. METHODS: Fifty root canal treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study. The patients were informed and their written consent was obtained. The samples were randomly allocated to five groups of ten samples each. Group 1: All Bond 2 with C & B (Bisco); Group 2: Scotchbond Multipurpose Plus with Opal Luting Composite (3M); Group 3: Scotchbond 1 in combination with Rely X ARC resin cement (3M); Group 4: One-step with C & B resin cement (Bisco); Group 5: All Bond Experimental with Post Cement HI-X (Bisco). The adhesive systems and resin cements were used strictly according to the manufacturers' instructions. The priming-adhesive solution of each 'one-bottle' system was light-cured before placing the resin cement and the post. Fifty Aestheti-Plus posts (white quartz fiber posts, RTD, France) were used. A week later, the roots were extracted and processed for SEM observations. RESULTS: All the adhesive systems showed a RDIZ and resin tag and adhesive lateral branch formation. Microscopic examination of the restored interfaces of Groups 1 and 2 showed a higher percent of RDIZ than those found in samples of Groups 3, 4 and 5. RDIZ morphology was easily detectable and uniform in the first two thirds of the root canals, whilst in the apical third the RDIZ was not uniformly present. Resin tag morphology and formation were significantly more detectable in the cervical and middle areas than in the apical zone. No statistically significant differences were found among the five groups coronally, while in the apical and middle thirds two 'one-bottle' systems (Groups 3 and 4) showed significantly less resin tags than the control Groups 1, 2 and the experimental Group 5. No statistically significant differences were found among the three 'one-bottle' systems in the three evaluated areas. The standardization of SEM observations and scoring resin tag formation allowed statistical evaluation. CONCLUSIONS: The 'three step' adhesive systems can create a wider micromechanical interlocking between adhesive materials and etched dentin than 'one-step' systems.

Dental Bonding↗
PubMed2002

Stimulation with phytohaemagglutinin induces the synthesis of catecholamines in human peripheral blood mononuclear cells: role of protein kinase C and contribution of intracellular calcium.

Although it is now established that immunocompetent cells produce catecholamines (CA), which in turn may act as autocrine/paracrine mediators, little is known about the mechanisms regulating CA production in these cells. In the present study, evidence is provided that stimulation of human cultured peripheral blood mononuclear cells (PBMCs) with phytohaemagglutinin (PHA) induces the expression of tyrosine hydroxylase (TH) mRNA and subsequently increases intracellular CA levels through protein kinase C (PKC) activation and the contribution of intracellular Ca(++)-dependent mechanisms. Increased production of CA in PHA-stimulated PBMCs suggests a preferential involvement of catecholaminergic pathways in the functional modulation of activated cells. These findings may help to better define the role of immunocompetent cell-derived CA in the neuroimmune network.

Calcium↗
PubMed2002

Catecholamine production and tyrosine hydroxylase expression in peripheral blood mononuclear cells from multiple sclerosis patients: effect of cell stimulation and possible relevance for activation-induced apoptosis.

Sympathoadrenergic mechanisms may play a role in multiple sclerosis (MS). We examined catecholamine (CA) levels and production and tyrosine hydroxylase (TH) expression in peripheral blood mononuclear cells (PBMCs) from MS patients, and the correlation between CA production and apoptosis in PBMCs. PBMCs from MS patients had increased norepinephrine (NE) levels. However, phytohaemagglutinin (PHA)-stimulated PBMCs from MS patients with active disease synthesized less dopamine (DA) than cells from both healthy controls and patients with inactive disease. PBMCs from patients with inactive disease showed lower expression of TH. Pharmacological inhibition of TH in cultured PBMCs stimulated with PHA reduced the percentage of apoptotic cells. Since a failure of activation-induced apoptosis in immune cells may be involved in MS, it is suggested that altered CA production by PBMCs may be implicated in such dysregulation.

Adult↗
PubMed2002

Differences in oxygen re-saturation of thigh and calf muscles after two treadmill stress tests.

Spatially resolved near-infrared oximeters quantify non-invasively muscle haemoglobin oxygen saturation (TOI) and, indirectly, local venous oxygen saturation (SvO(2)) and blood flow (MBF). TOI, SvO(2) and MBF of vastus lateralis and medial gastrocnemius were investigated after 5-min walking (3.2 km/h) and running (9.6 km/h) (n=7). The values of TOI were unchanged in the vastus lateralis during walking, whilst decreased during running in both muscles. For both muscles, TOI and SvO(2) values after walking were significantly greater than those found after running (P=0.043). The TOI went back (in 2 min) to its baseline value after walking in both muscles, whilst more slowly (in 4 min) after running in vastus lateralis. After running TOI of medial gastrocnemius had a tendency to be higher than the baseline value (reactive hyperaemia), concomitantly to the high MBF (twice the control value). The diverse oxygen demand in the stress tests and the consequent different pattern of TOI recovery reflect the different engagement of the two muscles. In conclusion, these results demonstrated the utility of TOI, independent of MBF and SvO(2), to be measured upon specific stress testing for differentiating the severity of peripheral vascular diseases and for assessing the collateral blood flow.

Adult↗
PubMed2002

Microtensile bond strength tests: scanning electron microscopy evaluation of sample integrity before testing.

The failure of a certain number of microtensile specimens during their preparation and before loading is a common and undesirable occurrence. This study was aimed at observing, under a scanning electron microscope, enamel and dentin microtensile specimens, in order to find structural faults that might be responsible for their premature failure. In a sample of 80 sticks, none of the specimens was found to be free of defects. These may consist of microcracks in enamel, most often at the periphery of the stick, or in dentin at the level of hybrid layer. Gaps were often seen at the interfaces between the substrates. Voids were sometimes visible within the resin composite thickness. Enamel specimens tended to exhibit more defects than dentin specimens. It is fair to suspect that, because of the brittleness of the tissue, enamel microtensile specimens are intrinsically more prone to failure, thus yielding bond strengths which are not significantly higher than those measured on dentin specimens. This leads one to question the reliability of the microtensile method for testing adhesion on enamel. It seems sensible to develop a method for a quantitative assessment of specimens integrity before loading as a possible predictor for their performance under load.

Adhesiveness↗
PubMed2002

Influence of a microbrush on bonding fiber post into root canals under clinical conditions.

OBJECTIVE: The objective of this clinical report was to evaluate the effectiveness of a microbrush as a carrier of priming-adhesive solution in formation of resin tags, adhesive lateral branches, and resin-dentin interdiffusion zone (RDIZ) when the brush was used to bond fiber posts under clinical conditions. STUDY DESIGN: Twenty endodontically treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study. The patients were informed, and their written consent was obtained. The samples were randomly divided into 2 groups of 10 samples each. In group 1, One-Step (Bisco, Schaumburg, Ill) was applied with a brush with Duo-Link resin cement (Bisco). In group 2, One-Step was applied with a microbrush with Duo-Link resin cement (Bisco). Use of the adhesive systems and resin cements was strictly according to manufacturers' instructions. The priming-adhesive solution was light-cured before the dual resin cement and the post were placed. Twenty Aestheti-Plus posts (white quartz fiber posts; RTD, St. Egreve, France) were used. A week after application, the root samples were extracted and processed for SEM observations. RESULTS: Both adhesive systems showed RDIZ and resin tag and adhesive lateral branch formation. In Group 2 samples, RDIZ morphology was easily detectable and uniform along root canals. Also, resin tag formation was well represented in all thirds. In group 1 samples, resin tag formation at the apical third and RDIZ formation was less evident. Statistically significant differences were found among the two groups at the apical third. CONCLUSION: The microbrush permitted a more uniform RDIZ and resin tag formation along the entire length of the canal than did the standard brush. The microbrush can be routinely used for bonding fiber posts into root canal preparations.

Adhesives↗
PubMed2002

Evaluation of Glyde File Prep in combination with sodium hypochlorite as a root canal irrigant.

The purpose of this study using a scanning electron microscope was to investigate the efficacy of four different irrigation techniques after canal preparation with Profile Ni-Ti rotary instruments. A modified technique for the use of Glyde File Prep is proposed. Forty anterior teeth were divided into four groups, instrumented, and irrigated as follows: physiological solution (group A), 2.5% sodium hypochlorite (group B), 2.5% sodium hypochlorite and Glyde File Prep (group C), and 2.5% sodium hypochlorite and Glyde File Prep applied at the end of the preparation with sterile paper points (group D). After scanning electron microscopic evaluation at three different levels, debris, smear layer, and dentinal tubules were scored. Groups A and B had significantly more smear layer and less open tubules on the canal walls compared with the group C and group D samples. Differences in the mean amount of debris between group A samples and other irrigation regimes were statistically significant.

Chelating Agents↗
PubMed2002

Comparison between two clinical procedures for bonding fiber posts into a root canal: a microscopic investigation.

The purpose of this study was to evaluate the influence of two brushes used as carriers of a primer-adhesive solution as to the formation of resin tags, adhesive lateral branches, and a hybrid layer when used to bond translucent fiber posts. Twenty endodontically treated teeth, extracted for periodontal reasons, were used. The samples were randomly divided into two groups of 10 samples each (Group 1: Microbrush + Scotchbond 1 + Rely X ARC resin cement; Group 2: small plastic brush + Scotchbond 1 + Rely X ARC resin cement). The adhesive system and resin cement were used strictly following manufacturers' instructions. The priming-adhesive solution of the one-bottle system was light-cured before placing the resin cement and the post. Twenty translucent fiber posts were used. After luting procedures, root samples were processed for SEM observations. The adhesive system showed a resin dentin interdiffusion zone (RDIZ), resin tag, and adhesive lateral branch formation. Microscopic examination of restored interfaces of group 1 showed a higher percentage (p < 0.05) of RDIZ than those found in samples of group 2. In group 1 samples, RDIZ morphology was well detectable and uniform in all thirds of the root canals. In group 2, RDIZ was not visible in the apical third. No statistically significant differences were found among the two groups coronally and at the middle third, but the apical third of group 1 showed significantly more resin tag formation than group 2. The characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of the root canals of both groups and in the apical third of group 1. In the apical third of group 2 root canals, the resin tags showed a less uniform morphology and a shorter length than those found in the other observed thirds.

Cementation↗
PubMed2002

Scanning electron microscopic investigation of the surface of fiber posts after cutting.

This study evaluated the surface of different types of fiber posts after cutting and investigated whether different cutting procedures can affect the integrity of the posts. Six types of fiber posts were selected for this study (Carbon Fiber Posts, Quartz Fiber Posts, Aesthetic Posts, Aesthetic Plus Posts, Translucent Posts, Dentatus, FRC Postec Posts). Fifteen posts of each type were studied. All posts had a diameter of 1.2 to 1.4 mm and were between 14 and 16 mm long. Each group was divided into three subgroups (n = 5) according to cutting method: diamond bur, carborundum disk, or scissors. The samples were then processed for scanning electron microscopic investigation. At low magnifications, no microscopic differences were found among the samples of groups 1-4 and 6. Surfaces from group 5 were more irregular, but only when cut using rotating instruments. All groups showed differences between surfaces cut with scissors and those cut with either diamond bur or carborundum disk. Posts displayed regular surfaces after cutting with a diamond bur. Cutting with a carborundum disk produced a mostly regular surface but sometimes produced irregularities close to the surface borders. The surfaces cut with scissors showed two plane and convergent flanges, and because of the formation of fracture lines these posts lost their integrity not only at the cutting surface but also along their length. The results of this study indicated that fiber posts can be cut using a diamond bur mounted in a handpiece under copious water coolant. Although the carborundum disk cutting procedure showed a less regular post surface, it can be speculated that it might be clinically acceptable. The cutting procedure using scissors should be avoided.

Alloys↗
PubMed2002

Pulp-dentin biology in restorative dentistry. Part 6: Reactions to restorative materials, tooth-restoration interfaces, and adhesive techniques.

A number of defense mechanisms may be activated in conjunction with restorative dental treatment. Tissue changes that lead to reduced dentinal permeability are important to minimize pulpal reactions. The healing potentials of the pulp-dentin complex are significant, and restorative dentistry is dependent on the available defense reactions. Clinicians should intentionally include considerations of these reactions in their treatment planning and during restorative treatment.

Adult↗
PubMed2002

Sealing ability of new generation adhesive-restorative materials placed on vital teeth.

The sealing ability of restorations is an important factor in order to prevent or reduce marginal gaps, which are often associated with postoperative sensitivity, caries and pulp disease. Usually the sealing ability of a new material is tested under laboratory conditions before being introduced on the market. However, in vitro evaluation of marginal integrity cannot predict in vivo performances of enamel-dentin bonding systems. A critical review of available data on sealing ability of last generation of adhesive-restorative materials placed on vital teeth is presented. The review includes the data of sealing performances of direct and indirect restorations, ethical considerations, influence of dental substrates on bonding, correlation between in vivo leakage studies and bond strength tests and microscopic evaluations. An in vivo protocol is presented in order to standardize leakage studies performed on vital teeth. A larger number of in vivo leakage tests are desirable in order to compare properties of new materials in multicenter studies. The ideal sequence of evaluation for new enamel-dentin bonding systems should be: in vitro tests, short term in vivo evaluations and then clinical trials.

Clinical Trials as Topic↗