The BSA method of calculating pediatric drug dosages.
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Body Surface Area↗
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Results for “Tooth Permeability”
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Influence of dentine on the pulpward release of eugenol or acids from restorative materials.
The diffusion gradient which develops across dentine and the clearance into the capillary circulation at the pulpal side of the tissue both reduce the concentration of potential toxins applied to dentine, thus protecting pulpal cells. The data presented on eugenol indicates that when release of a potential toxin from a solid material is hydrolytic the limited wetness of dentine, i.e. the limited availability of water for hydrolysis, contributes to the protective effect of the tissue. The data on strong acids indicates that a third protective mechanism, buffering by hydroxyapatite, can contribute to dentine's protective effect in situations where the potential toxin is strongly acid. There may be other mechanisms by which dentine protects the pulp against chemical toxins from restorative materials. However, the three described: diffusion limitation; limited wetness for hydrolysis; and buffering by dentinal hydroxyapatite, appear to allow the relatively safe use of a wide range of tooth restorative materials.
Acids↗
In vivo fluid movement through dentin adhesives in endodontically treated teeth.
Fluid transudation through simplified dentin adhesives can occur in bonded vital crown dentin, since these adhesives behave as permeable membranes after polymerization. The effect of adhesive permeability in endodontically treated teeth is unknown. This study examined the hypothesis that in vivo fluid movement through simplified adhesives occurs when they are applied to root canals. Dowel spaces were prepared in endodontically treated teeth with single root canals. Six adhesives were applied to the intra-radicular dentin of canal walls. Impressions were obtained with polyvinyl siloxane, and replicas were fabricated with the use of polyether impression material. Replica hemisections were gold-coated for SEM examination. Fluid transudation was evident on the adhesive surfaces of all simplified total-etch and self-etch adhesives. Conversely, most of the specimens bonded with the control three-step total-etch adhesive were devoid of fluid droplets. Permeability of simplified adhesives results in water movement, even in root-treated dentin. This may adversely affect the coupling of auto-/dual-cured resin cements.
Acid Etching, Dental↗
The etch-bleach-seal technique for managing stained enamel defects in young permanent incisors.
Hypomineralized enamel defects frequently are manifest as a mottled-white appearance and can be associated with variable degrees of discrete yellow-brown intrinsic staining. Numerous treatment approaches have been proposed, ranging from bleaching to enamel reduction to restorative techniques. Bleaching of hypomineralized enamel lesions, using 1 to 2 applications (10 to 15 minutes each) of 5% sodium hypochlorite, has been applied clinically. Treatment using this approach has proven successful in removing yellow-brown discolorations from lesions in young permanent teeth. Young permanent incisors with yellow-brown intrinsic discolorations can often be treated by a simple and conservative bleaching protocol using sodium hypochlorite.
Acid Etching, Dental↗
Effect of local application of fluoride on initial demineralization of buccal surface of maxillary incisors. Clinical assessment from colour slides.
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Child↗
High levels of hydrogen peroxide in overnight tooth-whitening formulas: effects on enamel and pulp.
PURPOSE: Limited data are available to assess the safety of high levels of hydrogen peroxide in overnight tooth-whitening formulas. The purpose of this study was to assess the effects of hydrogen peroxide on enamel microhardness, pulp penetration, and enamel morphology. MATERIALS AND METHODS: Colgate Platinum Professional Overnight Whitening System (Colgate Oral Pharmaceuticals, Inc., Canton, MA, USA) (10% carbamide peroxide, equivalent to 3.5% hydrogen peroxide) was compared with two prototype formulations containing either 7.0% or 12.0% hydrogen peroxide. In the pulp chamber studies, human extracted teeth were exposed to 3.5%, 7.0%, or 12.0% hydrogen peroxide for 30 minutes, 4 hours, or 7 hours. Microhardness, electron spectroscopy for chemical analysis, and atomic force microscopy evaluations were made from enamel blocks cut from human extracted molars. The enamel blocks were evaluated following 14 7-hour treatments (98 h total). RESULTS: At 7 hours' post-treatment, hydrogen peroxide penetrated the pulp chamber at 23.12 +/- 10.09, 24.58 +/- 6.90, and 26.39 +/- 5.43 microg for 3.5%, 7.0%, and 12.0% hydrogen peroxide, respectively. With regard to enamel morphology, pulp penetration, microhardness, and elemental composition, no statistically significant differences were observed between treatment groups following 98 hours of treatment. CONCLUSIONS: Hydrogen peroxide does not adversely affect enamel morphology or microhardness. The levels recovered in pulp indicate that hydrogen peroxide is not expected to inhibit pulpal enzymes. CLINICAL SIGNIFICANCE: Overnight tray products containing levels of hydrogen peroxide of 3.5%, 7.0%, and 12.0% are not expected to adversely affect the enamel or pulpal enzymes. Additional safety studies are needed to assess the potential for tooth sensitivity and gingival irritation.
Analysis of Variance↗
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↗
Tooth sensitivity associated with the use of luting cements.
Luting Cements are still a source of frustration to the dentist. None of the cements currently available satisfies everyone, including the patient. The problems encountered when trying to obtain adhesion to a wet substance such as dentin are well-known (Christensen, 1994). The cause of postcementation sensitivity continues to a perplexing problem.
Crowns↗
Relationship between mineral distributions in dentine lesions and subsequent remineralization in vitro.
Though the mineral distribution of the dentine carious lesion varies largely from tooth to tooth and from patient to patient, there are two main distribution profiles that characterize natural carious lesions in dentine. These profiles include softened and subsurface lesion types. The mineral distribution relationship between the starting profile and the profile after remineralization is not known. In order to study the relational aspects, we have produced demineralized dentine samples in vitro with mineral profiles similar to those of typical natural carious lesions, and subsequently remineralized the samples in a remineralizing solution with various fluoride concentrations (0, 2 and 10 ppm F). The mineral distributions were obtained by using an improved microradiographic technique. In addition, the nature of deposited mineral was analyzed by diamond-coupled total internal reflectance spectroscopy. Definite relationship was observed between the original lesion mineral distribution and the mineral distributions following remineralization. The amount of mineral present in approximately the first 50 microm of the lesion influenced the overall mineral profile after remineralization, possibly through influencing ion transport. If the amount was high (> approximately 10 vol%), the deposited mineral was confined to the surface (0-50 microm). The original mineral at those depths acted like a nucleus of mineral regrowth when the amount of residual mineral was intermediate, and like a transport barrier when the surface layer was well mineralized. If a surface barrier was not present, mineral was deposited at deeper depths in the lesion. Fluoride effect on dentine remineralization was dependent on the original mineral content and its distribution in the lesion. Although a high concentration of fluoride was very effective in low-mineral lesions, it produced hyperremineralization on well-mineralized subsurface lesions so that it prevented effective remineralization especially in deeper lesions.
Acetic Acid↗
HEMA diffusion from dentin bonding agents in young and old primary molars in vitro.
OBJECTIVE: The objective of this study was to evaluate and compare amounts of HEMA diffusion from three dentin bonding systems in young and old primary molars at a remaining dentin thickness (RDT) of 1 mm. METHODS: Occlusal cavities were prepared with RDT of 1 mm in young and old primary molars. Chambers that contain 1 ml of distilled water were attached to each tooth. The groups were treated with Total Etch+Syntac Single Component, Syntac Single Component and Clearfil SE Bond. Water eluates were analyzed by HPLC at 4 min, 24 h and 72 h. RESULTS: The cumulative HEMA release amounts were significantly different among all groups (p<0.05). Acid-etching significantly increased pulpward diffusion of HEMA and young primary teeth presented higher dentin permeability. SIGNIFICANCE: Acid-etching significantly increases pulpward release of HEMA from dentin bonding systems in primary molar teeth. Young primary molars have higher dentin permeability; so the pulp should be protected with cavity liners in deep cavities. However, the dentin bonding systems can be considered safe for clinical use in primary teeth, even in deep cavities, since the released HEMA amounts are below the level of cytotoxicity.
Age Factors↗
Apical diffusion of calcium hydroxide in an in vitro model.
An in vitro agar model was developed to study the effect of intracanal medicaments on periapical tissues and was used to study the diffusion of three calcium hydroxide (Ca(OH)2) medicaments of varying viscosity through simulated root canals with various sizes of apical foramina. Experimental medicaments were added to pipette tips used to represent tooth roots, which were fixed in syringes containing brain heart infusion agar and calcium-reactive dye. OH and Ca concentrations were measured in the agar at 30 minutes and 24 hours. Ca concentration and pH increased with larger aperture sizes, and higher pH and Ca diffusion was produced by a 10% Ca(OH)2 solution than was produced by Pulpdent or a Ca(OH)2 paste. The results suggest that the properties of the Ca(OH)2-containing vehicle could affect the action of the medicament in the periapical tissues.
Analysis of Variance↗
Effect of cavity preparation instruments (oscillating or rotating) on the composite-dentin interface in primary teeth.
OBJECTIVES: To evaluate the effect of preparation of instruments on the interfacial integrity between cavity wall and composite restoration. METHODS: Two class II slot preparations were done in 10 primary teeth either with SonicSys or with a conventional bur. The cavities were filled using an adhesive system. One layer of a flowable composite and one layer of a condensable composite were applied. The specimens were analyzed by confocal laser scanning microscopy. RESULTS: In the SonicSys group the mean thickness of the hybrid layer was 6.12 (0.60) microm; in the control group it was 6.04 (0.63) microm. The difference was not statistically significant. Two fractures were observed in one tooth of each group. These were located only in the enamel. The cavity margins were beveled in all specimens. SIGNIFICANCE: Compared to conventional preparations, cavity preparation with SonicSys has no deleterious effect on the integrity of the interface.
Composite Resins↗
An analysis of the effect of tooth intrusion on the microvascular bed and fenestrae in the apical periodontal ligament of the rat molar.
An analysis of the rat apical periodontal ligament (PDL) microvascular bed and fenestrae was conducted to evaluate the effect of a continuous 1.0 N intrusive tooth load for 30 minutes. The microvascular bed consisted of postcapillary-sized venules, venous and arterial capillaries, and terminal arterioles. Intrusion produced significant increases (p less than 0.01) in vascular volume for postcapillary-sized venules and venous capillaries in three of the four animals. Arterial capillaries, overall, showed a statistically significant increase (p less than 0.01). The endothelial surface area (micron2 x 10(6)) per cubic millimeter of PDL responded variably in postcapillary-sized venules and venous capillaries but showed a strong trend to increase in arterial capillaries. After tooth intrusion a significant reduction (p less than 0.01) occurred in the number of fenestrae per square micrometer of endothelium in postcapillary-sized venules and venous capillaries. Fenestrae in the control PDL had a mean diameter of 51.5 nm +/- 0.6 (SE), whereas those on the intrusion side were smaller (p less than 0.05), measuring 49.9 nm +/- 0.4 (SE).
Animals↗
In vitro cytotoxicity of dental adhesive systems under simulated pulpal pressure.
OBJECTIVES: Most of the devices used to evaluate the cytotoxicity of resin-based composites in vitro use a dentin barrier test. However, it is difficult to obtain the number of freshly extracted teeth, all on the same day, that is necessary for powerful statistical analysis. Tooth cryopreservation provides a way to build up a supply of teeth. This in vitro study compared cryopreserved teeth and freshly extracted teeth in an evaluation of the cytotoxicity of resin-based composites. In addition, this study also evaluated the effects of pulsatile pressure and the importance of dentin permeability on the cytotoxic response to bonding resins. METHODS: Forty freshly extracted and forty cryopreserved third molars were used. A standardized Class I cavity was prepared within the dentin. The hydraulic conductance of each tooth was recorded. The cavities were filled either with Scotchbond Multi-Purpose Plus and Z 100 (3M Dental Products) or with Optibond and Herculite (Kerr). A plexiglas device was designed to permit 24 h long contact between culture medium and the roof of the pulp chamber while a pulsatile pulpal pressure was simulated. The viability of L 929 cells cultured with a control medium and evaluated by an MTT assay was compared to that of L 929 cells cultured with medium which remained for 24 h in contact with the pulp chamber of restored teeth. A three-way ANOVA was used to compare the cytotoxicity among the different groups. A simple least-squares linear regression was used to seek a relationship between the hydraulic conductance of dentin and the cytotoxicity of composite restorative materials. RESULTS: No significant differences in cytotoxicity were found between the freshly extracted teeth and the cryopreserved teeth (p = 0.53). The cytotoxicity of the resin adhesives was statistically higher when a pulsatile pulpal pressure was simulated (p = 0.04). A significant relationship was found between the hydraulic conductance of dentin and the cytotoxicity of resin-based composites (p = 0.02). SIGNIFICANCE: Cryopreserved teeth can be used for in vitro evaluation of the cytotoxicity of resin adhesives. Pulsatile pulpal pressure simulations increased the in vitro cytotoxicity of the tested materials.
Adult↗
Infiltration/evaporation-induced shrinkage of demineralized dentin by solvated model adhesives.
During dentin bonding, solvated adhesive comonomers are applied to water-saturated decalcified dentin matrices. When alcohol-solvated hydrophilic or hydrophobic methacrylate monomers are applied, they chemically remove water and cause matrix shrinkage during comonomer infiltration. Evaporation of solvent induces further shrinkage. The purpose of this work was to compare the shrinkage of water-saturated dentin matrices infiltrated with ethanol- or methanol-solvated 2-hydroxyethyl methacrylate (HEMA), 2,2-bis[4(2-hydroxy-3-methacryloyloxy-propyloxy)-phenyl] propane (BisGMA), or triethyleneglycol dimethacrylate (TEGDMA) at 90/10, 70/30, 50/50, and 30/70 mass fraction % alcohol/monomer before and after evaporation of alcohol. Thin (ca 0.2 mm) disks of human mid-coronal dentin were demineralized and placed in a well beneath the contact probe of a linear variable differential transformer (LVDT). The height of the matrix was measured before and after random application of one of the twelve alcohol/monomer mixtures. Matrix height was measured during infiltration and during solvent evaporation. Between trials, residual monomer was extracted using ethanol. These studies were repeated on specimens in which 100% alcohol was used to substitute for water in the matrix. Both studies revealed that matrices shrink 30-50% but that pretreatment of matrices with alcohol prevents BisGMA phase separations from occurring. Wet bonding with ethanol instead of water permits infiltration of relatively hydrophobic alcohol/monomers.
Adhesives↗
In vitro permeability of furcation dentin in permanent teeth.
Extracted unerupted permanent third molars with the occlusal half of the crown and apical half of the roots removed were cemented to Plexiglas blocks. Using a positive pressure system in which the movement of fluid across the dental tubules could be measured, the permeability of furcation dentin was measured before and after alteration of the furcation thickness. Subsequently, measurements of reduction in thickness of cementum and dentin were performed. Furcation dentin permeability was found to increase as the cementum and dentin thickness was reduced and the smear layer removed. The permeability values obtained for the furcation dentin were similar to those found in radicular dentin in general, indicating that root dentin has a low permeability and that it has good barrier properties. The data would suggest that any bone resorption seen under the furcation region of permanent molars is more likely to be due to the presence of accessory canals than due to permeation directly through furcation hard tissues.
Adolescent↗
Structural and functional changes in root dentin following exposure to KTP/532 laser.
The use of a new, modified Nd:YAG laser called the KTP/532 laser was evaluated within root canals to determine whether it would modify dentin permeability or alter the scanning electron microscopic appearance of canal dentin. Energies and exposure times were chosen which did not permit periodontal temperatures to increase above 5 degrees C (1 W x 1 s-5 W x 0.5 s). Half of the root canals were covered with smear layer and half were treated with EDTA/NaOCI to remove the smear layer. The results showed that this laser did not change the permeability of the smear layer-covered dentin, although scanning electron microscopic examination revealed modifications to the surface of smear layer. Lasing of etched dentin produced modest increases in root permeability which were associated with enlargement and cracking of tubule orifices.
Dental Pulp Cavity↗
Microleakage of human saliva through dentinal tubules exposed at the cervical level in teeth treated endodontically.
This study investigated the possibility of saliva recontamination occurring between the root canal wall and sealer through dentinal tubules exposed after the cementum was removed at the cervical level by root planing and treatment with citric acid. Thirty-four extracted human maxillary anterior teeth were randomly placed into five groups after chemomechanical preparation and obturation with gutta-percha and sealer; the sealer was allowed to set for 48 h. A ring 3 mm high, at the cervical level, was subjected to root planing, with complete removal of the cementum. All specimens were coated with two layers of nail polish and two layers of sticky wax, except for the ring subjected to root planing that was treated with citric acid for 30 s. The specimens were exposed to human whole saliva for 20 to 80 days and then immersed in dye to determine microleakage. Specimens were cleared and measurements made to the maximum point of dye penetration. All of the specimens exposed to saliva showed leakage except for the negative control, wherein no dye penetration was seen. Where leakage was found, the dye penetrated between the canal walls and the sealer to increasing depths, proportional to the time of exposure to the saliva. Statistical analysis confirmed these data, evidencing a difference between the means, which was highly significant for all pairs.
Analysis of Variance↗