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P Calas

Publications and source records attributed to P Calas.

At least 19 recordsLinked to original sources
PubMed2006

[Diffusion of hydroxyl ions from calcium hydroxide in the dentinal tubules].

The aim of this study was to compare hydroxyl ions diffusion from various calcium hydroxide forms: Hycal (1), Roeko points (2) and aqueous suspension placed in the pulpar chamber (3) or in the root canal (4). These experiments were conducted with bovine incisors in order to obtain quantitative evaluation. 540 lateral cavities, deep and superficial, were created in root dentin to measure the hydroxyl ions diffusion with a color indicator, the Blue epsilon With Hycal and aqueous suspension the diffusion of the OH- is obtained in the superficial cavities situated in the coronal part at 14 days (1 = 72%; 3 = 44%; 4 = 100%, (n=18)). In the apical part of the canal this phenomenon is never complete at 21 days (1 = 17%; 3 = 22%; 4 = 17%, (n=18)). No diffusion was observed with the Roeko points (the first generation).

Animals↗
PubMed2005

[Dental consultations at a university hospital in Toulouse: the role for conservative treatments in oral health].

A retrospective study was carried out looking at the files of 481 patients who were seen for their first consultation at a university hospital dental school clinic. Their needs for conservative treatment were evaluated and the data from their files were analysed, including the following elements: demography, general health status, the expressed reason for the consultation, and the initially planned treatment. The descriptive analysis reveals a relatively young population group with an average age of 43.8 years, for whom 32% of them had existing or past medical conditions which necessitated that certain precautions be taken when prescribing conservative treatment. The most frequently given reasons for the consultation were the need for an annual dental check-up (41%) and pain (20%). 74% of the patients were in need of conservative treatments, and a priority for an initial treatment was cited for 48.4% of them.

Adult↗
PubMed2003

[Composite-bonded bridges reinforced with Ribbond THM ribbon: an alternative of choice to other temporary prosthetic methods].

In the presence of anterior unitary tooth loss, the therapeutical arsenal of the practitioner remains the implant solution. But, at the young patients who have not completed their growth, it's necessary to pass by a transitional stage. The bonded bridges reinforced by a polyethylene fibbers splint such as Ribbond THM constitute an alternative of choice to solve the aesthetic damage in the short and medium term while waiting for the prosthesis with implant. It's a similar case that is reported through this article.

Adolescent↗
PubMed1999

[Computer-assisted preoperative planning of knee replacement arthroplasty].

UNLABELLED: The general configuration of replaced knee is difficult to anticipate because of the large number of geometrical parameters related to morphology, prosthetic implants and pre-operative choices (such as ligament release). This article features the studies achieved in order to create a decision aiding computer tool dedicated to total knee prosthesis. METHOD AND MODEL: We have built a geometrical modelling of the physiological knee and prosthesis elements association. A numerical processing through biomechanical laws permitted to simulate the geometrical and mechanical behaviour of the whole for different flexing angle. RESULTS: A first validation of the model, comparing the numerical simulation results and the measuring of the 30 implanted knee X-rays, showed a valid matching (86 p.cent of the total cases) between model and real configuration. DISCUSSION: This tool allows to realise simulations and optimizations with regard to the following issues: decreased risks of the unsealing of the patellar component through contact centering with the trochlea, increased mechanical efficiency of the force transmission from the quadriceps to the tibia, increased maximum flexing angle considering the extension of the quadriceps. CONCLUSION: The orthopedic surgeon should be greatly assisted in the future preoperative planning by these initial findings.

Arthroplasty, Replacement, Knee↗
PubMed1998

In vitro adhesion of two strains of Prevotella nigrescens to the dentin of the root canal: the part played by different irrigation solutions.

Blocks of bovine incisor dentin, on the root canal surface of which a smear layer had been formed, were inoculated in vitro with two strains of Prevotella nigrescens, a wild sampled strain and a reference one (NCTC 9336). Half the blocks were pretreated with irrigating solutions: 6% citric acid for 5 min + 6.25% sodium hypochlorite for 10 min. They were compared with the other blocks simply rinsed in distilled water (i.e. the control samples). The bacteria adhering to the dentin surface after an incubation time of 3 h were counted by direct examination using a scanning electron microscope. The adhesion of P. nigrescens was less marked on all of the samples treated with irrigating solutions. Adherence was particularly significant in the case of the wild strain (F = 10.22). The latter was far more active than the reference strain (F = 35.82). The use of a chelating agent at the end of root canal preparation served to remove the smear layer and limited the attachment of P. nigrescens to the dentin.

Animals↗
PubMed1996

Effect of dentin treatment on in vitro root tubule bacterial invasion.

In light of the in vitro S. sanguis bacterial migration observed deep into root dentin, an in vitro system was developed to determine the viability of these bacteria at the end of migration. Also of interest is whether the smear layer formed during root canal instrumentation modifies migration into root dentinal tubules. Forty-eight bovine root dentin samples were randomly split into two groups. Group 1 dentin blocks were not instrumented and were treated with 17% ethylenediamine tetraacetic acid and 2.5% sodium hypochlorite for 4 minutes in an ultrasonic bath Group 2 root canals were conventionally instrumented. The smear layer formed was not removed. Dentin blocks were inoculated with a S. sanguis National Collection of Type Culture 7863 suspension. Each sample was immersed in a receiver broth, incubated at 37 degrees C, and checked daily for 14 days. After a 14-day incubation period, group 1 S. sanguis cells remained viable and capable of inoculating the receiver medium after migration through the tubules. Group 2 cells, where the smear layer was intact, revealed an absence of S. sanguis migration in 88% of the cases. It is therefore plausible that smear layer on canal walls limits S. sanguis penetration of dentinal tubules in vitro.

Animals↗
PubMed1994

In vitro attachment of Streptococcus sanguis to the dentin of the root canal.

The adhesion of a strain of Streptococcus sanguis (NCTC 7863) to the root canal dentin of bovine incisors was evaluated. Samples (104) were prepared and smear layer was created on the root canal surface with a tungsten carbide bur. The samples were divided into four groups, one of them serving as a control sample and the other three each receiving a different treatment: 6% citric acid for 2 min (group 3), 6% citric acid for 2 min + 6.25% sodium hypochlorite for 1 min (group 2), 6% citric acid for 10 min (group 4). After sterilization, they were incubated, and adhesion was assessed by direct examination using a scanning electron microscope. The use of irrigation solutions significantly reduced the adhesion in the latter two groups only, with a reduction of 15% (group 2) and 18.7% (group 4) in the number of bacteria.

Animals↗
PubMed1994

[Incidence and elimination of parietal smear layer in endodontics].

During canal preparation, the repeated passage of instruments provokes the formation of smear on the surface of the dentin. It is advisable to eliminate that, so as to increase antisepsis and filling impermeability. This is obtained by means of an irrigation, using a chelate compound of 6% citric acid for 60 seconds, at the end of the preparation.

Bacterial Adhesion↗
PubMed1993

In vitro study of the penetration of three bacterial strains into root dentine.

The purpose of this study was to assess in vitro migration of the following three bacterial species into dentinal tubules: Streptococcus sanguis, Actinomyces naeslundii and Prevotella intermedia. Twenty-seven bovine incisors were randomly divided into three groups. Only the root dentin was used for the experiment. Within each group, the nine incisors were sectioned into 36 dentin blocks that were incubated with one of the tested bacterial suspensions. Twelve samples were taken after 10, 20, and 28 days. Half the samples were observed with scanning electron microscopy and the others with light microscopy after standard histologic procedures, and the depth of bacterial penetration was measured. Analysis of the examinations showed that whatever the technique used, only one strain on this experimental model migrated into dentinal tubules. S. sanguis was observed at a depth of 792 microns, but no migration was observed for either A.naeslundii or P.intermedia. The differences in migration of the bacteria tested appear to be related to their morphologic factors and cellular arrangement.

Actinomyces↗
PubMed1993

Migration of a Streptococcus sanguis strain through the root dentinal tubules.

The persistent presence of bacteria in the root canal system often leads to the failure of treatment. The aim of this study was to study the in vitro penetration of root dentinal tubules by bacteria. Bovine dentin was inoculated with a strain of Streptococcus sanguis, NCTC 7863; samples were taken at 10, 20, and 28 days, and bacterial penetration of the tubules was demonstrated using two techniques, scanning electron microscopy and light microscopy after Brown and Brenn staining. The results showed that S. sanguis can penetrate deep inside the tubules (792 microns). The maturity of the dentin blocks seems to be a major factor in tubule penetration.

Animals↗
PubMed1991

[Interpretation of S.E.M. images using a treatment system and image analysis: preliminary study].

The scanning electron microscope has multiple applications in the research of endodontics, but there are not standard methods for the evaluation of the results. The use of the computerized processing and analysing systems for the images reduces the sources of error due to the subjectivity of the operator. This first part, after the introduction of the principles of processing and analysis, puts in view two methods of computerized analysis used in the study of the films of dentinal walls in the scanning electron microscope.

Color↗