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PubMed1994

In vitro action of various bleaching agents on the microhardness of human dentin.

The authors verified a decrease in human dentin microhardness after application of the following bleaching agents for 72 hours: sodium perborate+water, sodium perborate + 3% hydrogen peroxide, sodium perborate + 30% hydrogen peroxide, Endoperox (crystallized hydrogen peroxide), Proxigel (carbimide peroxide), and 30% hydrogen peroxide. Sodium perborate+water and sodium perborate + 3% hydrogen peroxide caused less of a decrease in dentin microhardness than Endoperox, Proxigel and 30% hydrogen peroxide which caused the greatest decreases in dentin microhardness. Sodium perborate + 30% hydrogen peroxide fell into a statistically intermediate position.

Analysis of Variance↗
PubMed2004

Peroxide penetration into the pulp from whitening strips.

It was observed that externally applied bleaching gels may penetrate into the pulp chamber. This study was conducted to evaluate the peroxide diffusion from two whitening strips into the pulp chamber. Twenty-four, human, extracted, maxillary central teeth were separated into three groups (n = 8). All teeth were sectioned 3-mm apical to CEJ, the intracoronal pulp tissue was removed, and the pulp chamber was filled with acetate buffer. Vestibuler crown surfaces of teeth in the experimental groups were subjected to whitening strips; the teeth in the control group were exposed only to distilled water. The acetate buffer solution in each tooth was transferred to the tube. Leuco-crystal violet and enzyme horseradish peroxidase also were added to the tube. The pulpal peroxide was determined spectrophotometrically. The results indicated that the whitening strip containing 14% hydrogen peroxide presented a higher pulpal peroxide penetration than 6.5 % hydrogen peroxide (p < 0.001).

Dental Devices, Home Care↗
PubMed1999

A comparative study of fluoride uptake from dentin bonding agents and glass-ionomer cements in permanent and primary tooth enamel.

OBJECTIVE: Many fluoride-releasing dental materials are being sold on the basis of their cariostatic properties. However, the amount of fluoride release of these materials is still uncertain. The aim of this study was to determine the amount of fluoride uptake in primary and permanent tooth enamel from 1 conventional glass-ionomer cement (Fuji II), 1 resin-modified glass-ionomer cement (Fuji II LC), and 2 fluoride-releasing dentin bonding agents (Liner Bond 2 and Optibond) in vitro. METHOD AND MATERIALS: One hundred sixty caries-free primary and permanent molar teeth were assigned to the study. Materials were applied according to the manufacturer's instructions to standard windows created on the enamel surfaces. The amount of fluoride uptake by enamel was investigated by using a specific fluoride electrode and acid-etching biopsy technique. RESULTS: The amount of fluoride taken up from Fuji II and Fuji II LC by permanent and primary tooth enamel was found to be statistically significant. However, no significant fluoride uptake from Optibond and Liner Bond 2 was found. CONCLUSION: Fuji II and Fuji II LC glass-ionomer materials seemed to provide more effective fluoride release than did Optibond and Liner Bond 2 in permanent and primary enamel.

Analysis of Variance↗
PubMed2002

Sealer distribution in coronal dentin.

A major cause of tooth discoloration is sealer remnants in the pulp chamber after root canal treatment. The purpose of this study was to assess coronal distribution and color changes of four commonly used sealers placed in the pulp chamber after 2 yr. Fifty extracted premolars were cross-sectioned in the coronal third of the root. The chamber contents were removed, and instrumentation was via the canal; then freshly mixed sealer was placed in each chamber. Sealers evaluated were: AH 26, Kerr Pulp Canal Sealer, Roth 801, and Sealapex. The apical access was sealed with white sticky wax, and the tooth was maintained in a moist environment at 37 degrees C for 2 yr. Teeth were split longitudinally, and digital images of the exposed dentin were made, scrambled, and evaluated blindly by trained evaluators for color changes and for presence of sealer in dentin. There was no measurable penetration of sealer into dentin for all groups and no dentin discoloration occurred. The sealers displayed marked discoloration. At 2 yr, the sealers discolored and remained confined primarily to the pulp chamber.

Bismuth↗
PubMed2004

[Chromatic study of all-ceramic crown--IPS Empress: difference of color by manufacturing technique and cements].

PURPOSE: In recent years,aesthetic appearance and function are called for and all-ceramic crowns are spreading. By choosing an all-ceramic crown the problem of metal ceramics is avoided. There are difficulties of color tone reproducibility of cervical margin and darkness of gingival margin. We examined IPS Empress also in various all-ceramic crowns. IPS Empress has high permeability a ceramic ingot of various color tones and excellent color tone reproducibility of natural teeth. Generally a layering technique is used for an anterior tooth and the staining technique is used for a molar. However the details are unknown We examined how differences of manufacturing method and cement affect the color tone of all ceramics clinically. METHODS: Two kinds of Empress crown were fabricated for a 27 year-old woman's upper left-side central incisors:the staining technique of IPS Empress and the layering technique of IPS Empress II. Various try-in pastes(transparent opaque white white and yellow) of VariolinkII of the IPS Empress System were used for cementing. Color was measured using a spectrophotometer CMS 35FS. The L*a*b* color system was used for showing a color. The right-side central incisors on the opposite side of the same name teeth were used for comparison. RESULTS: We analyzed the color difference (DeltaE* ab)with a natural tooth. Consequently when it had no cement of staining technique and was tranceparent small values were obtained. CONCLUSIONS: It is considered that the color tone can be adjusted by color cement. It is effective to use the staining technique for an anterior tooth crown depending on the case. The crown manufactured using the layering technique is not easily influenced by cement. The crown manufactured by the staining technique tends to be influenced by cement.

English Abstract↗
PubMed2005

Effects of one versus two-layer applications of a self-etching adhesive to dentin of primary teeth: a SEM study.

Resin composite is increasingly the material of choice for the restoration of primary teeth, and new materials with simplified procedures are increasingly being offered. Self-etching primers have been developed to simplify the bonding procedures. Some manufacturers recommend the application of these materials in two layers. However little is known about the application times. Therefore, this study evaluated the quality of the interfacial seal and the micromorphology of the hybrid layer in composite restorations bonded with one or two layer applications of a self-etching adhesive to the dentin of the primary teeth. The superfacial dentin (within 1-2 mm of dentinoenamel junction (DEJ)) on the occlusal surfaces of fourteen primary molars was exposed by a flat cut perpendicular to the long axis of the tooth. The occlusal surfaces were divided into two halves by a 1 mm deep groove in the labial-lingual orientation. The teeth were randomly divided into two groups: Group 1: Single Bond (control group) was applied according to the manufacturer's instructions on one half of the surface. On the other half of the same tooth, one layer of Prompt-L-Pop (experimental group) was applied according to the manufacturer's instructions. Group 2: the teeth received the same bonding regimes as group 1, but the experimental group had two layer application of Prompt-L-Pop. All samples were analyzed in SEM. Student's t-test was used to compare the width of the gap and hybrid layer thickness generated by experimental groups and control. There was a statistically significant difference between control (Single Bond) and the experimental groups (one or two layer application of Prompt-L-Pop) (p<0.05). Single Bond showed the best results. Two layer application of Prompt-L-Pop showed better sealing ability than one layer application of it (p<0.05). Only Single Bond presented a visible hybrid layer that had an average thickness of 3.7microm.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1994

Evaluation of a new dentifrice for the treatment of sensitive teeth.

A dentifrice containing 5% potassium nitrate, 1.3% soluble pyrophosphate, 1.5% polyvinylmethyl ether and maleic acid (PVM/MA) copolymer and 0.243% sodium fluoride in a silica base (Sensitive/Tartar Control) has been developed to concomitantly control tartar, caries and dentinal hypersensitivity. In vitro and animal studies show that the fluoride in this product effectively inhibits formation of enamel and dentine caries. In vitro studies also demonstrate that this dentifrice effectively reduces hydraulic conductance by occluding dentine tubules with a mixed surface deposit of copolymer and silica. Using an in vitro model that simulates in vivo conditions, this dentifrice also allows a rapid penetration of potassium nitrate through the dentine matrix. These findings demonstrate a correlation under in vivo conditions between the occlusion of dentine and the ability to deliver topically applied agents to target sites within or below dentine. The results indicate that this new dentifrice should provide multiple clinical therapeutic benefits including controlling tooth decay and tartar formation, and reducing and preventing dentinal hypersensitivity.

Animals↗
PubMed1979

Reducing marginal leakage: a review of materials and techniques.

Although significant progress has been made with the advent of composite restorative materials and associated techniques, the problem of marginal leakage has been lessened but not solved. The primary aim of future work must still be directed toward preventing the formation of a gap between the restoration and the tooth.

Absorption↗
PubMed1996

Therapeutic delivery of calcitonin to inhibit external inflammatory root resorption. I. Diffusion kinetics of calcitonin through the dental root.

Insertion of calcitonin into root canals of monkey teeth has been shown to inhibit external inflammatory root resorption and suppress inflammation. Regulation of this therapeutic event depends upon the rate of arrival (diffusion) of the hormone at sites of resorptive activity. In the present study, the diffusion characteristics of calcitonin through the dental root in an extracted human-tooth model are described, and the role of cementum in the diffusion process is also addressed. Root-canals were endodontically prepared to form a reservoir for [125I]-calcitonin, and macerated to remove organic material from dentinal tubules. In teeth with intact cementum, an initial period of delay (4-5 h) prior to the detection of calcitonin at the external tooth-root surface was followed by a rapid release of the calcitonin during the first 10.5 h (rate peaks at 6 h). Slower, sustained releases of calcitonin through intact cementum were measured for the following 9 days. Removal of cementum, to expose "smear-free" dentine, resulted in an earlier efflux of calcitonin (2 h) at external tooth surfaces and increased amounts of calcitonin release over 9 days. Biphasic delivery of calcitonin by such internal diffusion mechanisms suggests that loss of cementum will enhance therapeutic availability, while prolonged delivery to intact external dental-root surfaces following early intra-canal placement may also be useful for the therapeutic prevention of external inflammatory root resorption.

Administration, Topical↗
PubMed1991

The effects of storage after extraction of the teeth on human dentine permeability in vitro.

Freshly extracted third molars were stored for one week in one of four solutions: 70% ethanol, 10% formalin, distilled water with thymol and phosphate-buffered saline with thymol. Crown segments were prepared and initial permeability measurements taken. Each specimen was placed in a fresh preparation of its original solution, and permeability was measured over two periods: 1, 4, 6 and 8 days or 1, 8, 15 and 22 days. Ten crown segments were used for each solution for each time sequence. Permeabilities were lower for those specimens stored in ethanol and formalin than in water/thymol and saline/thymol, but most specimens showed increased permeability with time. Both storage solution and storage time had statistically significant effects (p less than 0.05), with significant differences between specimens stored in water/thymol and saline/thymol and those stored in ethanol and formalin. Thus, type of storage solution effects dentine permeability over time.

Analysis of Variance↗
PubMed2004

The in vitro effect of pulpal pressure and luting agent on tensile bond strength of complete cast crowns.

STATEMENT OF PROBLEM: The degree to which pulpal pressure may affect bond strength of complete cast crowns is unknown. PURPOSE: The aim of this in vitro study was to evaluate the effect of simulated pulpal pressure on the tensile bond strength of complete cast crowns luted with 2 different cements. MATERIAL AND METHODS: Forty-eight human mandibular canine teeth were cleaned and stored in saline solution. The crowns were prepared by 1 investigator, and standardization of the preparation was accomplished by fixing a dental handpiece in a parallelometer. Uniform grooves, 0.5 mm in depth, were prepared with burs with depth guides. The complete crowns were prepared with a 0.5-mm shoulder margin. Teeth were randomly divided into 2 groups of 24 teeth each (Group I and Group II). In Group I, bonding and tensile test procedures of the teeth were carried out under simulated pulpal pressure (15 cm of saline solution). In Group II, simulated pulpal pressure was not used. The roots were removed 1 mm below the cementoenamel junction to create direct communication with the pulp chamber. The remaining pulpal tissues were carefully removed, and crowns were embedded in acrylic resin. The acrylic resin was then penetrated by a stainless steel tube that connected the pulp chamber and the barrel of a disposable plastic 5-ml syringe. The pulp chambers were filled with physiological saline solution under elevated pressure to locate the area of greatest permeability on the dentinal surface. Crowns were cast (Co-Cr alloy) with a 20-mm bar to allow testing of the bond strength. Each of the 2 groups were further divided into 2 luting cement groups of 12 each (Group I, A and B, and Group II, A and B). Group IA/IIA and Group IB/IIB specimens were luted with a polycarboxylate luting cement (Poly-F Plus) and an adhesive luting cement (Superbond C&B), respectively. After storage in distilled water for 24 hours, all specimens were subjected to a tensile bond test in a universal testing machine at a crosshead speed of 0.5 mm/min until failure. The maximum load at fracture (Newton) was recorded. The results were then evaluated with 2-way analysis of variance and Tukey's honestly significant difference tests (alpha=.05). RESULTS: Simulated pulpal pressure increased the bond strength of cast complete crowns cemented with an adhesive luting agent (P=.01). No significant difference was found in the bond strength of complete cast crowns cemented with polycarboxylate cement with or without pulpal pressure. Superbond C&B adhesive luting agent showed significantly higher bond strength values for Group I (388.9+/-32.7) and Group II (300.9+/-66.8), when compared with polycarboxylate cement for Group I (221.3+/-17.3) and Group II (186.8+/-38.5) (P=.001). CONCLUSION: Simulated pulpal pressure had a positive effect on the retention of complete cast crowns when cemented with Superbond C&B adhesive luting agent. Superbond C&B significantly increased the retention of crowns in either the presence or absence of pulpal pressure.

Analysis of Variance↗
PubMed1990

Dentin permeability: effects of endodontic procedures on root slabs.

The permeability of human radicular dentin was measured as a hydraulic conductance before and after treatment with K files and before and after subsequent treatment of the endodontic smear layer with NaOCl, 50% citric acid, or 3% monopotassium-monohydrogen oxalate. Filing reduced dentin permeability 25 to 49%, respectively, depending upon whether outer or inner root dentin was filed. The permeability of these smear layers was unaffected by 5% NaOCl but increased many times after treatment with 50% citric acid for 2 min. Oxalate treatment lowered root dentin permeability to levels below that produced by creation of smear layers due to the production of a crystalline precipitate.

Adult↗
PubMedDate not supplied

In situ acid resistance of in vivo formed white spot lesions.

Thin sections of natural enamel lesions, so-called white spots (WS), and areas of sound enamel (SEn) adjacent to the WS were exposed to an intraoral environment for 2 weeks. Thin sections of WS samples, clamped in a PMMA holder, were microradiographed before and after exposure to intraoral conditions. Acid resistance was evaluated by lesion depth and mineral changes during the cariogenic challenge. The results show that there were statistically significant differences in lesion depth, mineral loss and mineral volume percent at the surface before and after the intraoral cariogenic challenge at least at p<0.05, except for a change in mineral volume percent at the surface of WS samples. This exception indicates that no mineral change occurred in the surface layer of WS. The fact of 2.8 and 1.8 times higher ratios of SEn over WS of mean changes in lesion depth and mineral loss data, respectively, seems to indicate a quantitative difference in acid resistance level of WS lesions compared with the areas of SEn. Regarding the site of mineral changes, a distinctive feature of WS samples is that mineral loss occurs at the bottom of lesions. In contrast, areas of SEn produce a typical subsurface type of lesions. From this in situ study, it can be concluded that the surface of WS samples was apparently much more acid-resistant (at least approximately 2 times) than the areas of SEn that received a similar intraoral acid challenge.

Acids↗
PubMed2000

A comparative scanning electron microscopic study on the characteristics of demineralized dentin root surface using different tetracycline HCl concentrations and application times.

BACKGROUND: The use of demineralizing agents has been reported to enhance the degree of connective tissue attachment to denuded roots. Of the agents used, tetracycline HCI has received the most attention. METHODS: The purpose of this study was to evaluate and compare the SEM surface morphology of human root dentin following various concentrations and application times of tetracycline HCl. The surface characteristics were compared and the width of dentin tubule orifices were measured and analyzed. Twelve human teeth were collected and stored in distilled water after soft tissue removal using hand instruments. The apical third of each root was removed and remaining mid-root region was sectioned longitudinally through the root canal following removal of its cementum with a fine diamond bur. A total of 48 dentin specimens were randomly divided into 8 groups for conditioning at different tetracycline HCl concentrations, at 0, 10, 25, 50, 75, 100, 125, and 150 mg/ml. Application times for each group were 1, 3, and 5 minutes. Immediately following treatment procedures, the specimens were rinsed, fixed in GTA-PBF, dehydrated, and prepared for SEM. Each specimen was examined at 2 magnification values, representative fields photographed, and data tested by one-way ANOVA and paired t test statistical analysis. RESULTS: Our results indicate that the use of tetracycline HCl solution between 50 mg/ml and 150 mg/ml showed a statistically significant opening of dentin tubules. All tetracycline HCl groups at 1, 3, and 5 minutes show smear layer removal from the dentin surface. CONCLUSIONS: Dentin demineralization is not time dependent at all concentrations of tetracycline HCI.

Anti-Bacterial Agents↗
PubMed2003

Permeability and morphology of dentin after erosion induced by acidic drinks.

BACKGROUND: The aims of this study were to evaluate 1) the alterations of dentin permeability after single exposure of dentin to several acidic soft drinks with different acid composition; 2) the effectiveness of smear layer on dentin surface to prevent erosion of sound dentin; and 3) the role of brushing procedures. METHODS: Dentin discs from human third molars were prepared. Each disc was treated with 0.5 M neutral EDTA for 5 minutes to remove the smear layer and to calculate the maximum fluid flow rate for each disc (to which an arbitrary value of 100% was assigned) using a pressure apparatus working at 1.0 psi. An homogeneous thin smear layer was then recreated with an abrasive paper under water. The following acidic drinks were applied for 5 minutes onto dentin surface: cola drink (phosphoric acid), orange fruit juice (ascorbic + citric acid), white wine (tartaric acid), vinegar (acetic acid), and mucolytic syrup (benzoic and tartaric acid). Each sample was then brushed for 3 minutes. Finally, each sample was brushed with a toothpaste and, as the final step, etched with phosphoric acid for 1 minute. Permeability was measured after each step. RESULTS: All acidic drinks were able to statistically increase dentin permeability and to open dentinal tubules by removing the smear layer. CONCLUSIONS: The study demonstrated that acidic drinks increased dentin permeability by removing and dissolving the smear layer and smear plugs. The erosion of peritubular dentin and smear plug removal is the main agent responsible for the increase in dentin permeability and probably for clinical dentin hypersensitivity. Brushing procedures reduced dentin permeability, creating a new fine and thin smear layer. Toothpaste may play a protective role in preventing complete smear layer removal and reducing dentin hypersensitivity by producing a new artificial smear layer and deposit inside tubules. The use and the abuse of acidic drinks may damage dentin and increase the risk for dentin hypersensitivity.

Acids↗
PubMedDate not supplied

The effect of 10% carbamide peroxide bleaching material on microhardness of sound and demineralized enamel and dentin in situ.

This in situ study evaluated the microhardness of sound and demineralized enamel and dentin submitted to treatment with 10% carbamide peroxide for three weeks. A 10% carbamide peroxide bleaching agent--Opalescence/Ultradent (OPA)--was evaluated against a placebo agent (PLA). Two hundred and forty dental fragments--60 sound enamel fragments (SE), 60 demineralized enamel fragments (DE), 60 sound dentin fragments (SD) and 60 demineralized dentin fragments (DD)--were randomly fixed on the vestibular surface of the first superior molars and second superior premolars of 30 volunteers. The volunteers were divided into two groups that received bleaching or the placebo agent at different sequences and periods at a double blind 2 x 2 crossover study with a wash-out period of two weeks. Microhardness tests were performed on the enamel and dentin surface. The SE and DE submitted to treatment with OPA showed lower microhardness values than the SE and DE submitted to treatment with PLA. There were no statistical differences in microhardness values for SD and DD submitted to the treatment with OPA and PLA. The results suggest that treatment with 10% carbamide peroxide bleaching material for three weeks alters the enamel microhardness, although it does not seem to alter the dentin microhardness.

Adult↗