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Results for “Dentin Permeability”

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At least 829 records · Page 46Linked to original sources
PubMed1991

[Investigations of centrifugal penetration of the tooth root hard substances by hydrogen peroxide].

After application of hydrogen peroxide into the root canal of extracted teeth of patients between the ages of 18 and 30 years the antiseptic could be detected on the root surface by means of iodometry and in tooth cross sections in dentine and cementum by means of staining reaction (benzidine-peroxidase solution). Out of the root canals which were apically not passable and coronally closed the first traces of the instilled 5% hydrogen peroxide appeared after 14 min 45 sec on the root surface. In the dentine a mean penetration depth of hydrogen peroxide up to 1.28 mm (apical root area), 1.45 mm (middle root third) and 1.95 mm (coronal root area) could be measured. Best results were obtained after rinsing/suction treatment of the root canal, especially in combination with low-frequency ultrasound.

Adolescent↗
PubMed1990

[Barodontology: current status. Dental aspects].

We present a comprehensive review of barodontalgia, with reference to the several pathogenetic hypotheses, and insisting on the consideration of barodontalgia in the differential diagnosis of toothache. The odontologists approach to this increasing clinical problem is also discussed.

Aerospace Medicine↗
PubMed1990

[Gypsum temporary filling material containing HY-agent. The effects of the HY-agent on the dentin].

The effects of the Tannin-Fluoride preparation, called the HY-agent, on dentin substrate were examined by immersion of the dentin previously treated with HY-agent into the calcifying fluid at 37 degrees C. The changes in the nature of the dentin surface and penetration of elements in the dentin were observed. CaF2 was formed on the dentin as a result of a reaction between F, an element of the HY-agent, and Ca which precipitated from the calcifying fluid. This observation was confirmed by means of the X-ray diffraction method. Penetration of F, Zn, Sr and Ca into dentin was confirmed by the use of an electron probe X-ray microanalyser (EPMA). Application of the HY-agent to the dentin for sevendays increased the hardness of the dentin about 10%. Application of the HY-agent to the dentin for sevendays increased the contact angle about 3%. These results suggested that the organic and inorganic matter in dentin can be stabilized effectively both chemically and physically by treatment with an HY-agent.

Calcium Sulfate↗
PubMed1990

[Adhesion of liners to dentin. In vivo experiments].

Research was performed in vivo on 42 vital teeth. Cavities of I and V Class where made, than restored with glass ionomer liners and composites. The teeth were extracted, stained and sectioned. Optic microscope did not show any stain under the ionomer liner, even in cases where composites were infiltrated. Electron microscope did not show any gap between ionomer liner and dentin.

Adhesiveness↗
PubMed1990

The smear layer in endodontics.

With the cascade of new restorative products being unveiled almost monthly, dentists incorporating endodontics into their practices must be able to evaluate the potential of these products for successful integration into their procedures. This evaluation should be based on a knowledge of how the new products relate to the smear layer formed along the root canal walls. Rather than relying on information supplied by the dental manufacturers, the aware dentist should regularly resort to the most current research reports available in journal or abstract form. With the use of certain products in some clinical situations, other branches of restorative dentistry may suggest retention of the smear layer. Although pulpally infected teeth have been successfully treated for generations in the presence of the smear layer, it has become accepted practice now in endodontics to remove the smear layer. Different quantities and qualities of smear layer can be produced by various techniques of instrumentation. However, they all present a barrier to intimate contact between obturating materials and the canal wall. Various types of solvents will produce different results in smear layer removal. One ideal endodontic irrigant follows the use of the antimicrobial 5.25 per cent sodium hypochlorite solution with the equally antimicrobial 6 per cent citric acid solution or 17 per cent EDTA. Chelating agents are effective in that they remove the smear layer, open the dentinal tubules, and produce a clean surface for closer obturation. Removal of the smear layer encourages the creation of a good apical plug to prevent over filling, post-filling sensitivity, and possible microleakage. The use of glass ionomer cements and unfilled resin as a cementing medium following smear layer removal shows promising results in both strength of cementation and the possibility of reducing post lengths. Controversies will always arise in dentistry with the advent of new information and the discovery of new clinical techniques. But a total awareness of both sides of a controversy will enable the practitioner to find a way through the confusion.

Chelating Agents↗
PubMed1988

[Changes induced by ouabain and colchicine in the transdentinal flow estimated in vivo by perfusion: the "push-pull" of the incisors of rats].

The active or passive mechanisms regulating the various movements of dentinal fluid have not yet been sufficiently studied. For this reason different "in vivo" factors that may modulate the kinetics of transdentinal flow were investigated. After systemic administration of a radiotracer in rats, the kinetics were examined with a push-pull perfusion device fixed to the incisor dentin. The drugs chosen, i.e. ouabain and colchicine, were for their respective effects on microtubules and on the ATPase-dependent Na+ K+ pump, since these two factors are involved in the transport process. Anesthetized animals were prepared to allow intravenous injection of iodine 125 (0,5 to 0,7 mCi), carotid sampling, and perfusion of upper incisors. Ouabain induced a very significant decrease in transdentinal flow, which was particularly evident in younger animals (2,81 x 10(-2) % vs 0,04 x 10(-2)%, p less than 0,05). However, colchicine produced two different kinds of results : at low doses (3,5 to 5 mg/100 g) the pulsatile pattern of the curves was partially inhibited, whereas, at higher doses (6 to 7 mg/100 g), the transdentinal flow of radioactivity increased. These results suggest that a combination of active and passive transport may be involved in the various movements of this fluid.

Animals↗
PubMed1989

[Trial of a new method for removal of demineralized dentin].

An experimental method designed to remove demineralised dentine Caridex, the recently-introduced chemico-mechanical dentinal tissue removal system, uses the chemical solution GK 101 to soften dentinal tissue already demineralised by caries, guaranteeing more selective removal of the dentine and treatment which is almost always painless.

Adult↗
PubMed1989

[Effects of sealing of dentinal tubules of root canal wall with Ag (NH3)2F (3.8%) solution].

In this study, in order to determine a method for obtaining a good reaction, the reactive products of 3.8% Ag (NH3)2F, using formalin as a reducing agent, were studied. Saforide RC was used as the 3.8% Ag (NH3)2F solution and 10% neutral formalinsolution was used as a reducing agent. The silver mirror test and reaction products on the root canal wall were investigated under the scanning electron microscope, along with observation of dye penetration using a stereoscopic microscope. Reaction of periapical tissue to the materials was studied histologically in dogs. In the natural reduction group, less amounts of reactive products were seen, and sealing of the dentinal tubules of the root canal wall was inadequate. In the formalin reduction group, large amounts of reactive products were found, and the dentinal tubules of the root canal wall were sealed. CaF2, Ag3PO4, Ag2O and Ag were identified as reactive products. In the natural production groups, obstruction was present but incomplete. In Formalin groups, dye osmosis obstruction was recognized. No harmful action of the solution on the surrounding tissue of the dog's tooth was recognized.

Ammonium Compounds↗
PubMed1989

[Do root canal filling materials enter dentin tubules?].

After removal of the smear layer all root filling materials tested were able to infiltrate dentin tubules. With the cement types studied, filled dentin tubules were found even at a distance of 100 microns from the root canal. The infiltration of the dentin tubules now explains the outstanding results of pigment penetration tests. The question, if the smear layer is to be removed or not, can now be answered "yes".

Dentin↗
PubMed1989

[Marginal leakage in dental restorations].

We make a review of the factors contributing to microleakage around dental restorations and the biological effects that this produces. We also make an evaluation of the existing methods for its research. We analize the behaviour of the different restorative materials, in relation to microleakage, and we set the rules to minimize this inevitable event that affects so much the longevity of dental restorations.

Composite Resins↗
PubMed1989

[Scanning electron microscopy and microprobe studies of fillings prepared with dentin glue].

The dentin wall of a cavity of class V prepared in vivo was, after a cavity cleaning with phosphorous acid, covered with a composite filling. The filling material penetrated into the dentin tubules. However, it did not adhere to the tubule wall. If the dentin wall of the cavity was cleaned according to factory prescriptions, the filling material did not reach the dentin. Only the preparation debris were impregnated by it.

Adhesives↗