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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↗
PubMed1997

The effects of immunoglobulins on the convective permeability of human dentine in vitro.

Immunoglobulin molecules are localized in the dentinal tubules of non-carious and carious teeth, but their possible role in caries invasion is not understood. This study sought to examine the effects of immunoglobulin molecules on dentine permeability using a fluid-filtration method. Crown segments cut from impacted human third molars were treated by filtration with 100 micrograms/ml IgG, 100 micrograms/ml IgA or 30 micrograms/ml IgM under a constant pressure. Flow rates were recorded and percent changes in flow rate analysed over time. Filtrates collected at various times were tested for changes in immunoglobulin concentrations by an enzyme-linked immunosorbent assay, and the percent retention of immunoglobulins to dentine was calculated. There was a decreasing non-linear exponential relation between the percent changes in flow rate and filtration time for all three immunoglobulins. The percentage of retained immunoglobulins was significantly related to the filtration time for all three classes of immunoglobulins. Immunoglobulin retention contributed to significant changes in flow rate with time. These in vitro results indicate the potential mechanism of immunoglobulins in decreasing tabular permeability.

Dental Caries↗
PubMed1992

Dentin wetness, permeability and thickness and bond strength of adhesive systems.

This study evaluated the shear bond strength of Scotchbond 2, Clearfil PhotoBond, Tenure, All-Bond and Vitrabond and their sensitivity to dentin permeability, wetness and thickness. Occlusal dentin was prepared from extracted human teeth that were connected to a hydraulic pressure apparatus. Dentin permeability was calculated as a fluid flow rate and dentin surface wetness was evaluated using the Periotron device. Dentin thickness was measured using a pincer caliper. Shear bond strength was tested after 24 hours storage under hydrostatic pulpal pressure. Several significant correlations were found between dentin wetness, dentin permeability and remaining dentin thickness and the shear bond strengths of Scotchbond 2, Tenure and All-Bond/no etch. No apparent correlations were observed for the other adhesive systems.

Acid Etching, Dental↗
PubMed1993

Permeability of dentin to adhesive agents.

The permeability of dentin to adhesive agents is of crucial importance in obtaining good dentinal bonding. In those systems that remove the smear layer, the opportunity exists for resin to infiltrate both tubules and intertubular dentin. Resin penetration into tubules can effectively seal the tubules and can contribute to bond strength if the resin bonds to the tubule wall. Resin infiltration into intertubular dentin can only occur if the mineral phase of dentin is removed by acidic conditioners or chelators. This is more easily accomplished in fractured dentin than in smear layer-covered dentin because of the residual collagen debris that remains on the surface following acid etching of smear layers. The channels for resin infiltration are the perifibrillar spaces created around the collagen fibers of dentin following removal of apatite mineral by acids. The diffusion of adhesive resins through these narrow, tortuous, long channels in 1 to 2 minutes offers a number of challenges that require further research.

Acid Etching, Dental↗
PubMed2002

Dentin morphology and permeability after brushing with different toothpastes in the presence and absence of smear layer.

BACKGROUND: The purpose of this study was to evaluate the morphology and permeability of dentin after brushing with different toothpastes in the presence and absence of smear layers. METHODS: Dentin discs were prepared from extracted third molars. Dentin permeability was measured using a hydraulic pressure apparatus working at 70 cm H2O pressure. Dentin was treated with 0.5 M EDTA for 5 minutes and washed to remove a smear layer and to establish the maximum permeability of each dentin disc, which was expressed as 100%. A new smear layer was then created on the upper surface using a #400 carbide paper under water for 30 seconds. Dentin permeability of the smear layer-covered dentin was measured and expressed as a percentage of the maximum permeability of that specimen, permitting each specimen to serve as its own control. Each sample was then brushed by a mechanical device under water for 3 minutes with constant pressure of 250 g using a medium toothbrush and permeability remeasured. Finally, 1 of 5 different toothpastes was applied on the dentin and brushed for 3 minutes. In another group, the same procedures were performed with the exception of the smear layer production, so it was possible to calculate changes in the permeability of dentin with open tubules following brushing. Scanning electron microscopic (SEM) examination of dentin was obtained before and after treatments with brushing and toothpastes. RESULTS: Dentin permeability was reduced by brushing procedures when the smear layer was absent, but it was increased when the smear layer was present. Toothpaste application reduced dentin permeability when no smear layer was present on the top of the surface, but modified and increased permeability of samples with smear layers. SEM observations demonstrated the presence of dentifrice particles on dentin surfaces and inside dentinal tubules, and this may be responsible for the observed reductions in permeability. Smear plugs produced during dentin brushing were not removed by the dentifrices. CONCLUSIONS: Dentin permeability and morphology are significantly affected by toothbrushing and by the type of dentifrice used. The presence of smear plugs in the dentin may decrease severity.

Adult↗
PubMed2001

2000 Judson C. Hickey Scientific Writing Award. Effect of impression materials on hybridized dentin.

STATEMENT OF PROBLEM: Tooth sensitivity after crown preparation is not an uncommon complication. For dentin bonding agents to be effective in preventing postoperative sensitivity, they must remain intact throughout the fixed prosthodontic procedures. PURPOSE: This study evaluated, by analyzing the change in dentin permeability, whether a dentin bonding agent was removed from the surface of prepared teeth in the process of making an impression. MATERIAL AND METHODS: Eighty extracted human molars were cut horizontally apical to the cemento-enamel junction and horizontally through the middle of the clinical crown. The specimens were prepared to measure dentin permeability (fluid flow rate, Lp). The specimens (n = 40) were randomly assigned to either the primer-only group (PO) or the primer + adhesive group (PA). Five different impression materials were tested: vinyl polysiloxane, polyether, polysulfide, irreversible hydrocolloid, and reversible hydrocolloid. Dentinal permeability was measured after smear layer removal (control, etched Lp = ELp), after coating the dentin with either PO or PA (coated Lp = CLp), and again after making an impression (impression Lp = ILp). A 1-way ANOVA of differences, followed by a Student-Newman-Keuls test (alpha=.05), was performed to compare the ELp, CLp, and ILp values. RESULTS: A statistically significant difference was found between the CLp and ELp for all 5 impression materials in both groups (PO and PA). No difference was found between the CLp and ILp values for any of the impression materials. No significant differences were found between any of the 5 impression materials or either of the dentin surface treatments (PO or PA) when measuring the CLp and ILp. CONCLUSION: The dentin bonding agent had a significant effect in decreasing the Lp of the treated specimens. None of the impression materials significantly affected the measured CLp. There was no significant difference between the PO or PA (CLp) values.

Acid Etching, Dental↗
PubMedDate not supplied

The effects of acid etching on the pulpodentin complex.

Acid etching of dentin is used by many bonding systems to remove the smear layer and permit bonding directly to the dentin matrix. Although early animal studies indicated that acid etching caused moderate to severe pulpal reactions, there is a high probability that the pulpal irritation may have been due to microleakage of bacteria and their products. As these reactions are not seen following acid etching of dentin using newer dentin bonding systems, it is clear that one can acid etch dentin if, and only if, one can seal the dentin with subsequently placed bonding systems. Because acid etching increases dentin permeability and dentin wetness, successful bonding of adhesive resins to acid-etched dentin requires the use of hydrophilic resins that bond equally well to both peritubular and intratubular dentin. Future trends seem to be toward lowering both the concentration of acids and the time of etching of dentin. While all bonding systems should be carefully scrutinized prior to marketing, the future looks very promising for the use of adhesive resins on acid-etched dentin.

Acid Etching, Dental↗
PubMed1989

The permeability of dentine from bovine incisors in vitro.

The permeability of coronal dentine was investigated by measuring the hydraulic conductance of dentine discs. Reductions in dentine thickness from the enamel side of disc resulted in a greater increase in permeability than reductions from the pulpal side. Scanning electron microscopy revealed fewer dentinal tubules with smaller diameters in superficial dentine than in deep dentine. The permeability of coronal incisor bovine dentine is six to eight times less than that of unerupted coronal human third molar dentine but similar to that of human root dentine.

Animals↗
PubMedDate not supplied

[Microbial permeability of dentin].

This is a review of the literature about the contemporary aspects of microbial permeability of dentin. They are discussed the factors that are responsible for this question and analytically: the structure of dentin, the composition of dentin in organic and inorganic ingredients, the response mechanisms of dentin, that is the irritation dentin and sclerotic dentin, the hypermineralized zone under carious lesions, the role of saliva and dentinal fluid, the role of pulp and its microcirculation against the invasion of microbes and, the role of smear layer. Also this article refers to the immunological reaction of the pulp and finally to the role of dentist in the permeability of dentin, because the more conservative is a tooth preparation the less is the permeability of dentin. In conclusion, the microbial permeability of dentin is a very complicated biological phenomenon that needs more study and further investigations.

Dental Pulp↗
PubMed1995

Duration of dentinal tubule occlusion formed by calcium phosphate precipitation method: in vitro evaluation using synthetic saliva.

The use of a calcium phosphate precipitation method occluded dentin tubules with apatitic mineral and, thus, showed good potential for the treatment of dentin hypersensitivity. The aim of this study was to elucidate the occluding behavior of the precipitate in the oral environment. Dentin disks treated by the calcium phosphate precipitation method, and disks treated with potassium oxalate, NaF, and SrCl2 solutions, were immersed in synthetic saliva, which was regularly replenished so that ionic concentration would be maintained. Treatment of dentin disks by the calcium phosphate precipitation method immediately reduced dentin permeability to 6 +/- 8%. When the disk was immersed in synthetic saliva, dentin permeability remained low, even seven days after immersion. Scanning electron microscopic observation showed no distinct boundary line between the precipitate and intertubular dentin; this indicated further mineralization on the precipitate. Potassium oxalate treatment also reduced the dentin permeability to 8 +/- 3%. However, the dentin permeability gradually but steadily increased with immersion time, reaching 39 +/- 14% at seven days. To elucidate the mechanism underlying dentin permeability changes in synthetic saliva, we immersed the precipitates, i.e., apatitic mineral and calcium oxalate, in a fixed volume of synthetic saliva. When calcium oxalate was immersed in synthetic saliva, there was a large concentration of oxalate ions, indicating dissolution of the calcium oxalate; this phenomenon was ascribed to the increase in dentin permeability. In contrast, calcium and phosphate ions decreased when apatitic powder, the precipitate formed by the calcium phosphate precipitation method, was immersed in synthetic salvia. The decrease in the calcium and phosphate ions in synthetic saliva indicated further precipitation of calcium phosphate on the apatitc precipitate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

Calcium phosphates produced by physical methods in the treatment of dentin hypersensitivity.

BACKGROUND: The aim of this paper is to study the properties of innovative materials based on defective calcium phosphates produced by physical methods in the therapy of dentin hypersensitivity. METHODS: In particular, the effects of gels, aqueous solutions and toothpastes containing the above mentioned materials on dentinal permeability measured as dentin hydraulic conductance have been studied. The calcium phosphates have been characterized by X-ray powder diffraction (Rietveld analysis) and Fourier transform infra-red analysis. In addition, scanning electron microscopy has been performed to study the surface of dentin and enamel after treatment with the phosphates. In particular sound occlusal dentin, sound cervical dentin, carious occlusal dentin, sound buccal enamel and carious buccal enamel have been observed. RESULTS: The results have shown that these biocompatible materials can be produced with chemical and physical characteristics very similar to dentin and/or enamel. By forming a protective layer inside and outside the dentin tubuli, the calcium phosphates significantly reduce the dentinal hypersensitivity. CONCLUSIONS: These phosphates seem to be a promising material for clinical application.

Calcium Phosphates↗
PubMed1989

Permeability of etching agent constituents through dentin.

The in vitro dentin permeability of the constituents of two types of conventional phosphoric acid etching agents which had different viscosities, and their pH changes after being permeated dentin were investigated. It was recognized that, even though the etching was for a short time (one minute) followed by rinsing, the etching agents were still detected in the dentinal tubules which had permeated through the dentin. The results of a qualitative and quantitative analysis of the constituents which had permeated through the dentin showed that, after one minute of etching, the concentrations of calcium, magnesium, zinc and phosphorus increased as compared with the non-etched control samples.

Acid Etching, Dental↗
PubMed1997

Permeability of dentine after Nd:YAG laser treatment: an in vitro study.

The purpose of this investigation was to determine the effects of Nd:YAG laser treatment on the permeability of dentine. Forty dentine discs were prepared by horizontal sectioning through the middle coronal third of freshly extracted non-carious third molars. After the removal of the pulp the discs were finished with 600 grit and divided into three test groups and one control group (n = 10). For the test group three different laser power settings were chosen: test group A: 3 x 60 sec, 60 mJ; test group B: 3 x 60 sec, 90 mJ; test group C: 3 x 60 sec, 120 mJ. No laser treatment was performed on the control group. In a two-chamber system the filtration rate of dentine tubules from an exactly defined area of the specimens was measured using a radioactive Ringer solution under a pressure of 30 cm H2O. Permeability measurements were carried out three times prior to lasing, three times immediately following laser treatment and six times after the application of phosphoric acid. Analysis of variance showed a significant influence of the Nd:YAG laser treatment on the permeability of dentine (P < 0.001). The mean quotient of non-treated control vs. lased dentine was 2.19 +/- 0.86 for the 60 mJ beam, 1.49 +/- 0.88 for the 90 mJ beam, and 2.04 +/- 2.17 for the 120 mJ beam. Etching the lased surfaces had a statistically significant influence on the permeability of the dentine only in the 60 mJ group (P < 0.001). The data show that the Nd:YAG laser treatment often increases the permeability of smear layer covered dentine but moderates the increase of permeability after etching the surface with phosphoric acid.

Acid Etching, Dental↗
PubMed2006

Oxalate-containing phytocomplexes as dentine desensitisers: an in vitro study.

It is known that pulpal fluid movement through dentinal tubules causes dentinal hypersensitivity and that pain can be reduced by decreasing the fluid flow. The aim of this study was to evaluate dentinal permeability and morphology after a single exposure to experimental phytocomplex substances containing oxalates. The treatments tested were experimental pastes, gels and solutions of phytocomplexes (extracted from rhubarb, spinach and mint), an experimental paste containing 5% potassium oxalate, and two commercial toothpastes recommended for dentinal hypersensitivity (Elmex and Sensodyne). Dentine discs from human third molars were used in this study. Each sample was brushed for 3 min with each treatment in order to test reductions in dentinal permeability. Each treated sample was challenged with orthophosphoric acid for 90 s to determine changes in dentinal permeability and the sensitivity of treatments to acid challenge. Scanning electron microscopy was used to analyse the samples. This study found that spinach and rhubarb phytocomplex treatments reduced dentinal permeability by occluding dentinal tubules through formation of calcium oxalate crystals. These results indicate that phytocomplexes extracted from rhubarb and spinach, used in different formulations, should be effective for topical treatment of dentinal hypersensitivity.

Amines↗