Biomedical subjects

L Marigo

Publications and source records attributed to L Marigo.

8 recordsLinked to original sources

PubMed2004

Probiotic treatment increases salivary counts of lactobacilli: a double-blind, randomized, controlled study.

BACKGROUND/AIMS: Lactobacilli are used in the prevention and treatment of several diseases, but they are also known to play a role in the pathogenesis of dental caries. The aim of our study was to evaluate whether the oral administration of lactobacilli could change the salivary counts of these bacteria compared with placebo. Moreover, lactobacilli were administered in liquid and in capsule form to determine the role of direct contact with the oral cavity. METHODS: Thirty-five healthy volunteers were randomized into three groups to receive lactobacilli and/or placebo for 45 days: group A (n = 14) received probiotics in capsules and placebo in liquid form; group B (n = 16) took liquid probiotics and placebo in capsules, and group C (n = 5) used placebo in both liquid and capsule form. Streptococcus mutans populations served as control. The salivary counts of lactobacilli and S. mutans were measured semi-quantitatively using the CRT bacteria kit. RESULTS: Compared with placebo, the oral administration of probiotics, both in capsules and in liquid form, significantly increases salivary counts of lactobacilli (p = 0.005 and p = 0.02, respectively). S. mutans populations were not significantly modified. CONCLUSIONS: The increased salivary counts of lactobacilli may indicate the need to closely monitor the dental health of patients undergoing long-term probiotics treatment, even when this treatment is administrated in a form that avoids direct contact with the oral cavity.

Administration, Oral↗

PubMed2003

[Light-emitting diodes (LED) technology applied to the photopolymerization of resin composites].

An adequate polymerization of resin composites can significantly contribute to increase the longevity of a restoration. In this field, the choice of the operative technique and the characteristics of the lamp are very important. The aim of this review was to evaluate the effectiveness of cure of the light-emitting diodes (LED) lamps comparing them to the others currently available for resin composites photopolymerization. At present, halogen lamps are the most commonly used light sources, but this technology does not allow further developments; even plasma arc and laser lamps have some drawbacks. The innovative LED technology, based on semiconductors, opened new and interesting views in the field of photopolymerization; to the advantages of a soft-start polymerization they add the safety, efficiency, economy and long lifetime of LED light. A careful review of the literature revealed that, although their lower emission of light, these lamps are capable of a polymerization qualitatively comparable to other light sources. Physical and mechanical properties, degree of conversion, depth of cure and final hardness of the composites cured with a LED light are similar to the values achieved with the halogen lamp, whereas the temperature increase is significantly lower and does not pose a threat to the pulp tissue. Undoubtedly, more tests of the mechanical properties of composites processed with LED units need to be carried out but, as the technology improves, LED curing will become an interesting alternative to existing curing methods.

Biopolymers↗

PubMed2000

[Clinical observations on the nature of early caries. A study with scanning electron microscopy].

BACKGROUND: Early caries lesions present a greater porosity in the deep layers than in the superficial layer of the enamel. The "white spot" lesion is a dynamic lesion which is subjected to the changes occurring in the oral cavity; it can regress, stabilize or progress. The aim of this study is to show if there are considerable morphological differences in the superficial ultrastructural aspect of early caries lesions, active or stabilized, in persons of different age. METHODS: To carry out this SEM observation, 15 patients aged from 12 to 50 presenting early caries lesions have been selected. Some of them had been recently subjected to orthodontic treatment, others several years ago. Five of these patients have been called back to examine again the demineralized area by microscope in the very same place of the first observation. The replica technique was used utilizing a silicon-based impression material, an epoxy resin for replicas casting, little steel nets to fix the silicon material. RESULTS: At the level of white spot lesions it is evident a tissural structure scattered with small overlappings and micropits with a diameter of 0.5-2 mu. The patients who removed orthodontic bands more than 10 years before show a shining white aspect, corresponding to the nearly complete loss of enamel perikymata with well defined abrasions, but without any micropits at SEM examination. CONCLUSIONS: The replica technique has shown to be useful to record the defects of active and stabilized caries lesions. However this technique can't be utilized as a diagnostic instrument because it would be too expensive, but it is certainly a valid support for in vivo research.

Adolescent↗

PubMed1999

Pulpo-dentin protection: the biocompatibility of materials most commonly used in restorative work. A literature review.

The complexity and importance of the biological structures that form the so-called pulpal dentinal complex call for considerable accuracy during restorative procedures. In practice this means accurate techniques and appropriate dental materials, able to combine protective and restorative qualities, and above all, offering biocompatibility. In order to analyze this property, a number of international studies suggest the use of sequential tests divided into three different levels: initial tests, secondary tests and usage tests in the form of in vivo and in vitro tests to observe and simulate the biological reactions to dental materials used in particular tissues. The authors publish a review of the literature regarding the biocompatibility of intermediate materials regarded as useful aids in restorative dental practice; these include paints, liners and cavity bases made from Ca(OH)2, ZOE cements, zinc phosphate, polycarboxylic compounds, glass ionomers, bonding agents and mordents. The chemical, biological, clinical and utilization parameters are outlined for each compound, paying special attention to the problem of biocompatibility and indicating the pulpal reactions reported over the past decade in connection with their use. In conclusion, while waiting for a standard international document to codify evaluation methods and classify the results obtained, these experimental data can be used to programme a more correct and safer use of materials.

Biocompatible Materials↗

PubMed1997

[Saliva: clinical and diagnostic usefulness. Review of the literature].

Modern clinical pathology is mainly based on the analysis of blood samples, carried out through more and more sophisticated techniques. Being the blood test an invasive technique, it certainly reduces the possibility of carrying out blood analysis, especially in patients such as children, old people, handicapped people and every person who needs continuous biochemical or pharmacological monitoring. In these cases it is very important to find other body fluids that can be easily obtained and that can offer the same reliable data as blood. Due to some of its characteristics, sometime saliva may be a good alternative to venous blood, as it presents the same features of plasma or urine. The chemical analysis of saliva provides some information that are useful for metabolic, inflammatory, neoplastic and genetic diseases; furthermore radioimmunological dosages allow to assess small concentrations of active substances. On the basis of an accurate review of literature, the aim of this study is to analyse the importance of saliva in diagnosing and monitoring certain systemic diseases, the utilization of saliva in hormonal and pharmacological dosages and the use of saliva in some epidemiological studies. Finally, it is emphasized that saliva in monitoring may help to manage several clinical conditions.

Diagnostic Techniques and Procedures↗

PubMedDate not supplied

Bonding of composite resins to dentin: SEM observation of one-component enamel-dentin bonding systems.

AIM: To evaluate in vitro the qualitative characteristics of the surfaces of some enamel-dentin bonding systems. METHODS: Seven different bonding systems were observed first by stereomicroscopy then by scanning electron microscopy, as follows: 49 extracted teeth were abraded to expose a uniform dentin surface. After application of the bonding system, composite resin was placed on the surface and shaped as an inverted truncated cone. The tensile bond test was performed and the specimens observed under SEM; the fracture location was determined and the formation of the hybrid layer evaluated. RESULTS: SEM observation indicated that adhesive, cohesive and mixed fractures had occurred. The abraded dentin surfaces were also observed under SEM before and after etching. The most recent enamel-dentin bonding systems use a conditioning technique that demineralizes the upper dentin surface at and around the tubule entrance. This is known as the total etching technique. A layer is formed in which the demineralized dentin is impregnated with fluid resin: the so-called hybrid layer. CONCLUSIONS: The length of the plugs of adhesive was not found to be determinant. The formation of the hybrid layer appeared to be more important, as it indicated a three-dimensional interaction between the conditioned collagen fibres and the primer that diffuses the adhesive.

Acid Etching, Dental↗

PubMedDate not supplied

[Efficacy of 4 adhesive systems for amalgam. In vitro study].

BACKGROUND: The aim of this research is to study the shear bond strength of 4 adhesive systems of the last generation: All-Bond 2 (AB2), Clearfil Liner Bond 2 (CL), Scotchbond MP plus (SBMP) and High Q Bond plus (HQB). According to the manufacturing company these products are suitable for amalgam adhesion to dentin. METHODS: Forty extracted human third molars have been ground to expose a flat dentin surface. The teeth were randomly assigned to 4 groups, and every group was treated with one of the adhesive system according to the manufacturer's instructions. Samples were then secured in a split Teflon mould, having a 6 mm diameter opening and a spherical amalgam was triturated and condensed onto the treated dentin surfaces. The amalgam cylinders have been exposed to a tensile bond test using a Universal Testing Machine (Instron 4500). ANOVA test has been used to the statistic study among groups. RESULTS: The study of the tensile mean range, showed that dentin shear bond strength values (MPa) for the adhesive systems tested were: 8.13 +/- 1.48 for AB2, 7.06 +/- 1.41 for SBMP, 4.2 +/- 1.06 for HQB, 3.04 +/- 0.68 for CL. The statistic test revealed significant differences among the 4 groups (p < 0.05). CONCLUSIONS: The bond strength mean values of amalgam adhesives are lower than the ones for composite resins, nevertheless dentin-enamel adhesive systems specific for amalgam have to be taken into consideration particularly in case of conservative restorations that need chemical retention as a support, when the mechanical one is not enough.

Dental Amalgam↗

PubMedDate not supplied

3-D surface profile analysis: different finishing methods for resin composites.

A microfilled and hybrid resin composites used for esthetic restoration were finished and polished using four methods: Enhance system, Sof-Lex system, Multi-step system and Identoflex points. The tested materials were condensed into cylindrical molds, covered with a Mylar matrix at the surface to be tested and incrementally cured according to manufacturers' instructions. Samples were randomized into four groups of three for each material and were finished/polished using the different methods. The samples were then analyzed by a 3-D surface profiler to obtain roughness average (Ra), root mean square value (rms), greatest distance peak-valley (PV), measure of profile about the center line (Rsk) and measure of steepness of the amplitude density curve of the roughness profile (Rku) directly from the tested area. This method offers the advantage of being error-free. All parameters were determined for each sample and the mean of each parameter was determined for each group. ANOVA and Sheffé's test were employed to determine whether significant differences existed. The Enhance and Multi-step systems gave the best finish and polish for both materials.

Analysis of Variance↗