Dentinal Fluid Research Articles

The effect of dentinal fluid flow during loading in various directions—Simulation of fluid–structure interaction

ObjectivesThis study uses a fluid–structure interaction (FSI) simulation to evaluate the fluid flow in a dental intrapulpal chamber induced by the deformation of the tooth structure during loading in various directions. MethodsThe FSI is used for the biomechanics simulation of dental intrapulpal responses with the force loading gradually increasing from 0 to 100N at 0°, 30°, 45°, 60°, and 90° on the tooth surface in 1s, respectively. The effect of stress or deformation on tooth and fluid flow changes in the pulp chamber are evaluated. ResultsA horizontal loading force on a tooth may induce tooth structure deformation, which increases fluid flow velocity in the coronal pulp. Thus, horizontal loading on a tooth may easily induce tooth pain. ConclusionThis study suggests that experiments to investigate the relationship between loading in various directions and dental pain should avoid measuring the bulk pulpal fluid flow from radicular pulp, but rather should measure the dentinal fluid flow in the dentinal tubules or coronal pulp. The FSI analysis used here could provide a powerful tool for investigating problems with coupled solid and fluid structures in dental biomechanics.

Effect of Er,Cr:YSGG laser on human dentin fluid flow

The aim of the current investigation was to assess the rate and magnitude of dentin fluid flow of dentinal surfaces irradiated with Er,Cr:YSGG laser. Twenty extracted third molars were sectioned, mounted, and irradiated with Er,Cr:YSGG laser at 3.5 and 4.5 W power settings. Specimens were connected to an automated fluid flow measurement apparatus (Flodec). The rate, magnitude, and direction of dentin fluid flow were recorded at baseline and after irradiation. Nonparametric Wilcoxon signed ranks repeated measure t test revealed a statistically significant reduction in fluid flow for all the power settings. The 4.5-W power output reduced the flow significantly more than the 3.5 W. The samples showed a baseline outward flow followed by inward flow due to irradiation then followed by decreased outward flow. It was concluded that Er,Cr:YSGG laser irradiation at 3.5 and 4.5 W significantly reduced dentinal fluid flow rate. The reduction was directly proportional to power output.

Facilitatory effect of AC-iontophoresis of lidocaine hydrochloride on the permeability of human enamel and dentine in extracted teeth

ObjectivesThe objectives of the present study were to quantitatively evaluate chemical permeability through human enamel/dentine using conductometry and to clarify if alternating current (AC) iontophoresis facilitates such permeability. Materials and methodsElectrical impedance of different concentrations of lidocaine hydrochloride was measured using a bipolar platinum impedance probe. A quadratic curve closely fitted to the response functions between conductance and lidocaine hydrochloride. For analysis of the passage of lidocaine hydrochloride through human enamel/dentine, eight premolars that were extracted for orthodontic treatment were sectioned at the cemento-enamel junction. The tooth crowns were held between two chambers with a double O-ring. The enamel-side chamber was filled with lidocaine hydrochloride, and the pulp-side chamber was filled with extrapure water. Two platinum plate electrodes were set at the end of each chamber to pass alternating current. A simulated interstitial pulp pressure was applied to the pulp-side chamber. The change in the concentration of lidocaine hydrochloride in the pulp-side chamber was measured every 2min using a platinum recording probe positioned at the centre of the pulp-side chamber. Passive entry without iontophoresis was used as a control. ResultsThe level of lidocaine hydrochloride that passed through enamel/dentine against the dentinal fluid flow increased with time. Electrical conductance (G, mho) correlated closely to the concentration (x, mmol/L) of lidocaine hydrochloride (G=2.16x2+0.0289x+0.000376, r2=0.999). ConclusionsLidocaine hydrochloride can pass through enamel/dentine. Conductometry showed that the level of lidocaine hydrochloride that passed through enamel/dentine was increased by AC iontophoresis.

Dental Adhesion

Contemporary dental adhesives show favorable immediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. It appears that simplification of adhesive techniques is rather detrimental to the long-term stability of resin-tooth interface. The hydrostatic pulpal pressure, the dentinal fluid flow and the increased dentinal wetness in vital dentin can affect the intimate interaction of certain dentin adhesives with dentinal tissue. Bond degradation occurs via water sorption, hydrolysis of ester linkages of methacrylate resins, and activation of endogenous dentin matrix metalloproteinases. The three-step etch-and-rinse adhesives still remain the gold standard in terms of durability. This review discusses the fundamental process of adhesion to enamel and dentin with different adhesive techniques, factors affecting the long-term bonding performance of modern adhesives and addresses the current perspectives for improving bond durability.

Seal that Heals

ABSTRACT Introduction Dentinal hypersensitivity can be treated by dentinal tubule occlusion which prevents any stimuli from causing dentinal fluid movement. This in vitro study aims to compare the dentinal tubule occluding capability of four chemical compounds, a bonding agent, a compound of fluoride and hydroxyapatite, potassium oxalate gel and sodium fluoride varnish. Materials and methods Forty dentin samples were divided into four groups of 10 samples each. Group A (treated with Clearfil SE Bond), Group B (treated with Remin Pro), Group C (treated with Potassium Oxalate, Vi-sense,) and Group D (treated with Pro Fluoride varnish). The samples were treated with ethylene diamine tetraacetic acid (EDTA) gel prior to application of desensitizing agents to remove the smear layer and open the dentinal tubule orifice. Following the desensitizing treatment the specimens were washed and dehydrated using graded series of ethanol treatments (25, 50, 75, 90 and 100%). After each treatment tubule occlusion was analyzed by scanning electron microscope. Results Qualitative and quantitative analysis demonstrated potassium oxalate gel to cause maximum tubule occlusion followed by Remin Pro > Sodium fluoride varnish > Clearfil SE Bond. Conclusion Life expectancy is increasing and patients are retaining their natural teeth for a longer time due to effective treatment strategies. The results showed the potential use of these products as an effective means of tubule occlusion. How to cite this article Benjamin S, Roshni, Pradhan S, Nainan MT. Seal that Heals. World J Dent 2012;3(3):243-246.

<I>In vitro </I>permeability of etch-and-rinse and self-etch adhesives used for immediate dentin sealing

To investigate the permeability of deep dentin following immediate sealing with different etch-and-rinse and self-etch adhesives (Single Bond 2, Adper Prompt L-Pop, Clearfil Protect Bond, Clearfil S3 Bond, G-Bond) and a dentin desensitizer (Gluma). Fluid-transport model was used to measure fluid conductance during and after application of adhesives. Polyvinylsiloxane impressions of bonded dentin were taken to monitor fluid transudation from the surface of the adhesives. The area and number of dentinal fluid droplets and/or blisters were calculated using image analysis. None of the adhesives were able to block fluid conductance completely. The fluid conductance values of the adhesives displayed the following statistical ranking (p<0.05): G-Bond≤Clearfil Protect Bond<Smear-layer-covered dentin<S3 Bond≤Single Bond 2≤Adper Prompt L-Pop<Gluma Desensitizer<Acid-etched dentin. Highly significant correlation was observed between the permeability of the tested adhesives and the area fraction of fluid droplets/blisters on the adhesive surfaces (r=0.99, p<0.01).

Marginal adaptation of large adhesive class IV composite restorations before and after artificial aging

To test the marginal adaptation of Class IV restorations made of different composite materials designed for anterior use. Forty-two extracted caries-free human maxillary central incisors were randomly divided into 7 experimental groups - one per composite tested - for which Class IV cavities were prepared. The microfilled composite materials tested (SolidBond/Durafill [D/SB], Syntac classic/Heliomolar [H/SC], Scotchbond1/ Experiment127 [EXI/SB1], Optibond FL/Point 4 [P4/OBFL], Prime&Bond NT/Esthet-X [EX/PBNT], ART Bond/ Miris [MIR/ART], SE Bond/Clearfil ST [CLE/SE-B]) were inserted in two increments after polymerization of their respective adhesive systems. While under simulated dentinal fluid pressure, specimens were submitted to cyclic incisal stress (1,200,000 cycles, maximum load 49 N) and thermal loading (3000 cycles). Both after polishing and after thermomechanical loading, impressions were made of the surface of each restoration, and epoxy replicas were prepared for the marginal adaptation evaluation using SEM. Perfect margins before loading in enamel ranged from 49.9% (EXI/SB1) to 98.2% (MIR/ART) and after loading from 25.3% (EXI/SB1) to 91.9% (MIR/ART). For margins located in dentin, perfect margins ranged from 16.8% (EXI/SB1) to 100% (CLE/SE-B) before loading and from 4.6% (EXI/SB1) to 67.1% (CLE/SE-B) after loading. The poor results obtained in this in-vitro test with the microfilled composites suggest avoiding their use in large Class IV restorations with margins in dentin.

Inflammatory mediators in fluid extracted from the coronal occlusal dentine of trimmed teeth

BackgroundChemokines and cytokines may occur in dentinal fluids in response to local infection and inflammation. To test this hypothesis, we assessed the presence and concentration of inflammatory mediators in fluid extracted from the coronal occlusal dentine of trimmed teeth. DesignFreshly extracted sound, carious, and restored molars were trimmed through the enamel to expose the underlying dentine, etched with 35% phosphoric acid, and rinsed. Fluid was extracted from the coronal occlusal dentine of these trimmed teeth by centrifugation at 2750×g for 30min. ResultsWhen assessed by MALDI-TOF, fluid extracted from the coronal occlusal dentine from 16 molars contained at least 117 peaks with different masses suggesting that this fluid was rich with molecules within the appropriate mass range of potential mediators. Indeed, when assessed for chemokines and cytokines, fluid extracted from the coronal occlusal dentine from 25 extracted molars with caries lesions, 10 extracted restored molars with occlusal amalgam, and 77 extracted sound molars contained IL-1β, TNF-α, IL-6, IL-8, IL-12(p70), and IL-10. A significant elevation was found for TNF-α (p=0.041) in extracted fluid from teeth restored with amalgam fillings. ConclusionsOverall, fluid extracted from the coronal occlusal dentine of trimmed teeth may be useful in identifying proteins and other molecules in dentine and pulpal fluids and determining their role as mediators in the pathogenesis of oral infection and inflammation.

Fluid Mechanics in Dentinal Microtubules Provides Mechanistic Insights into the Difference between Hot and Cold Dental Pain

Dental thermal pain is a significant health problem in daily life and dentistry. There is a long-standing question regarding the phenomenon that cold stimulation evokes sharper and more shooting pain sensations than hot stimulation. This phenomenon, however, outlives the well-known hydrodynamic theory used to explain dental thermal pain mechanism. Here, we present a mathematical model based on the hypothesis that hot or cold stimulation-induced different directions of dentinal fluid flow and the corresponding odontoblast movements in dentinal microtubules contribute to different dental pain responses. We coupled a computational fluid dynamics model, describing the fluid mechanics in dentinal microtubules, with a modified Hodgkin-Huxley model, describing the discharge behavior of intradental neuron. The simulated results agreed well with existing experimental measurements. We thence demonstrated theoretically that intradental mechano-sensitive nociceptors are not “equally sensitive” to inward (into the pulp) and outward (away from the pulp) fluid flows, providing mechanistic insights into the difference between hot and cold dental pain. The model developed here could enable better diagnosis in endodontics which requires an understanding of pulpal histology, neurology and physiology, as well as their dynamic response to the thermal stimulation used in dental practices.

Analysis of thermal-induced dentinal fluid flow and its implications in dental thermal pain

ObjectivesThe initiation of the pain sensation experienced following the thermal stimulation of dentine has been correlated with fluid flow in the dentinal tubules. There may be other mechanisms. MethodsThis study examines this possibility using a mathematical model to simulate the temperature and thermal stress distribution in a tooth undergoing thermal stimulation. The results obtained were then used to predict the fluid flow in a single dentinal tubule by considering the deformation of the dentinal tubules and dentinal fluid. ResultsDeformation of the pulp chamber was observed before a noticeable temperature change was recorded at the dentine–enamel junction. Tubule deformation leads to changes in fluid flow more rapidly than fluid expansion or contraction. This finding agreed with previously reported experimental observations. An initially high rate of outward fluid flow under cooling was found to correspond to short latency neural responses whilst heating was associated with long latency neural responses. ConclusionRapid fluid flow caused by thermal deformation of dentinal tubules may account for the short latency (<1s) activation of mechano-sensitive receptors after of cooling. Long latency (>10s) neural responses could be associated with the activation of thermo-sensitive receptors.

FLUID DYNAMICS ANALYSIS OF SHEAR STRESS ON NERVE ENDINGS IN DENTINAL MICROTUBULE: A QUANTITATIVE INTERPRETATION OF HYDRODYNAMIC THEORY FOR DENTAL PAIN

Noxious thermal and/or mechanical stimuli applied to dentine can cause fluid flow in dentinal microtubules (DMTs). The fluid flow induces shear stress (SS) on intradental nerve endings and may excite pulpal mechanoreceptors to generate dental pain sensation. There exist numerous studies on dental thermal pain, but few are mathematical. For this, we developed a computational fluid dynamics (CFD) model of dentinal fluid flow (DFF) in innervated DMTs. Based on this model, we systematically investigated the effects of various parameters (e.g., biological structure, DFF velocity, and fluid properties) on the SS experienced by intradental nerve endings and thus provide a quantitative interpretation to the hydrodynamic theory. The dimensions of biological structures, odontoblastic process (OP) movement, dentinal fluid velocity, and viscosity were found to have significant influences on the SS while dentinal fluid density showed negligible influence under conditions studied. The results indicate that: (i) dental pain study of animal models may not be directly applied to human being and the results may even vary from one person to another and (ii) OP movement caused by DFF changes the dimension of the space for the fluid flow, affecting thus the SS on nerve endings. The present work enables better understanding of the mechanisms underlying dental pain sensation and quantification of dental pain intensity resulted from clinical procedures such as dentine sensitivity testing and dental restorative processes.

Biomimetic dentin desensitizer based on nano-structured bioactive glass

Objectives This study evaluated the ability of a novel sol–gel bioactive glass, in conjunction with appropriate carrier vehicles, to reduce dentinal fluid flow, with an eye toward reducing dentinal hypersensitivity. Methods Experiments were conducted to measure the reduction in tubule fluid flow after treatment of cut tooth surfaces with sol–gel bioactive glass particles in several carrier vehicles. Surfaces were also examined after exposure to brushing and acidic solutions. A non-bioactive particulate glass was compared. Results Tubular occlusion produced by the bioactive glass was observed via SEM and a sustained reduction in hydrodynamic conductance was measured after exposure to various fluids and brushing. Conclusions This new material may be used with the tested carriers to significantly and durably reduce tubule fluid flow, ultimately resulting in reduced dentinal hypersensitivity.

A First Study on the Usefulness of Matrix Metalloproteinase 9 from Dentinal Fluid to Indicate Pulp Inflammation

Introduction Pulpal diagnostics might be improved by using molecular markers found in dentinal fluid. In the current pilot study, we tested whether matrix metallopeptidase 9 (MMP-9) levels in dentinal fluid were detectable and differed between pulps from symptomatic teeth diagnosed with irreversible pulpitis and healthy counterparts. Methods Thirty-one patients participated; 19 were diagnosed with irreversible pulpitis, and 12 were in need of replacement of a filling close to the pulp space in a clinically healthy tooth. Dentinal fluid was collected during a period of 2 minutes from dentin cavities by using folded polyvinylidene difluoride (PVDF) membranes, which were then transferred to microcentrifugation tubes containing physiologic saline solution. Total MMP-9 levels in these solutions were assessed by using a human MMP-9 fluorescent assay, detection limit 0.25 ng/mL. MMP-9 levels between groups were compared by using Mann-Whitney U test (alpha <0.05). Results Three specimens from the symptomatic teeth were not included because coronal pulps proved to be necrotic on access. Dentinal fluid samples from symptomatic teeth had significantly higher MMP-9 levels than those from clinically healthy counterparts ( P < .05). However, merely 7 of the 16 pulpitis samples contained detectable levels of MMP-9. None of the clinically healthy control specimens contained any detectable amounts of MMP-9. Conclusions With a sensitive assay, it was possible to detect an enzyme linked with pulp tissue destruction (MMP-9) in dentinal fluid. However, the collection method needs to be improved to provide predictable fluid yields. Longitudinal studies should be performed to assess the predictive value of molecular markers in dentinal fluid on pulpal pathosis.

Review of matrix metalloproteinases' effect on the hybrid dentin bond layer stability and chlorhexidine clinical use to prevent bond failure.

This review describes the relationship between dentin collagen hybrid bond layer degradation and the Matrix Metalloproteinases (MMPs) after their release by acid etch and rinse adhesives and self etching bonding adhesives that can reduce the bond stability over time. MMP-2, MMP-8 and MMP-9 are indicated as the active proteases that breakdown the collagen fibrils in the hybrid bond layer. Phosphoric acid in the acid etch and rinse bonding process and acid primers in the self etch process are implicated in the release of these proteases and their activation by several non-collagen proteins also released from dentin by the etching. MMPs are released in saliva by salivary glands, by cells in the gingival crevices to crevicular fluid and by pulpal odontoblasts cells to the dentinal fluids. These sources may affect the hybrid layer also. Evidence of the bond strength deterioration over time and the ability of Chlorhexidine to prevent bond deterioration by inhibiting MMP action are discussed. Dentin Bonding procedure utilizing Chlorhexidine for different application times and concentrations are being developed. The application of 2% Chlorhexidine to the phosphoric acid etch surface after rinsing off the acid is the only procedure that has been clinically tested for a longer period of time and shown to prevent bond strength degradation so far. The adoption of this procedure is recommended as means of improving bond stability at this time.

Effect of different osmotic stimuli on fluid flow before and after self-etching adhesive application.

To determine the in vitro dentinal fluid movement produced by various osmotic stimuli, and evaluate fluid movement across human dentin in response to the application of various osmotic stimuli before and after the application of self-etching adhesive (Clearfil S3 Bond). The experiments were carried out on 10 extracted premolars. Each tooth was cut transversely below to the cementoenamel junction with a diamond disk and water coolant. Dentin was exposed at the tip of the buccal cusp by cutting a cavity and was etched with acid. The osmotic stimuli were solutions of saturated CaCl2, sugar syrup, chocolate, and sweet Thai dessert, used as osmotic test solutions, randomly applied to dentin.The fluid flow through dentin obtained after 15 s of application of each osmotic stimulus was measured before and after bonding with Clearfil S3 Bond single-dose. Before bonding procedures, CaCl2 produced peak rates of fluid flow that were significantly higher (p <0.001), when compared with normal saline, sugar syrup, chocolate, and sweet Thai dessert. During the applications of all osmotic stimuli, the amount of fluid movement across resin-bonded dentin was significantly lower than that without adhesives. There were no significant differences of fluid shifts across resin-bonded dentin obtained during the application of any osmotic stimuli. It appears that different osmotic stimuli produced different rates of outward fluid flow through dentin. Clearfil S3 Bond produced similar significant reductions of fluid movement in response to osmotic stimulation, irrespective of the chemical composition, or the osmotic pressure of stimuli.

Synthesis of nanobioglass and formation of apatite rods to occlude exposed dentine tubules and eliminate hypersensitivity

The occlusion of patent dentine tubules may reduce or eliminate hypersensitivity by restricting dentinal fluid movement. The efficacy of a novel sol-gel nanobioglass and a melt-derived bioglass to occlude tubules and promote apatite formation was tested by mechanically brushing a slurry of bioglass powder and human saliva onto dentine possessing exposed tubules. Scanning electron microscopy, focused ion beam and energy-dispersive X-ray spectroscopy were used to characterize the powders and assess tubule occlusion. Melt-derived bioglass possessed an irregular particle morphology and had a mean size of 3.30 +/- 0.42 microm. The sol-gel bioglass particles were spherical, with a mean size of 0.65 +/- 0.19 microm. Dentine treated with melt-derived bioglass exhibited a tightly adherent continuous apatite layer. Treatment with nanobioglass resulted in particle deposition within tubules and formation of apatite rods which were tightly adherent to tubule walls and continuous to a measured depth of 270 microm.

The influence of a local anesthetic containing vasoconstrictor on microtensile bond strengths of two adhesive systems to human dentin in situ.

To evaluate the bond strengths of an etch-and-rinse adhesive and a self-etching adhesive to human dentin in vitro and under two in situ conditions: non-anesthetization and anesthetization of the teeth with a local anesthetic containing vasoconstrictor. An in situ study was performed on 49 maxillary premolars scheduled for extraction due to orthodontic reasons. For the bond strength test, occlusal cavities were prepared either with or without a local anesthetic containing vasoconstrictor. The cavities were bonded with Adper Single Bond or Clearfil SE Bond and filled with a resin composite, Filtek Z250. The teeth were then extracted, sectioned, trimmed, and tested for microtensile bond strength. For the observation of dentin surfaces, 20 premolars were used. The impressions of the cavity floors in the anesthetized and non-anesthetized groups were taken before and after acid etching. The replicas were observed under a scanning electron microscope. In vitro, the bond strength test and the SEM observation were also carried out on 24 extracted premolars with the same procedures used in the in situ study. The bond strengths of the two adhesives bonded to dentin in situ were significantly lower than those in vitro. When both adhesives were tested under in situ conditions, there were no significant differences between the bond strengths to dentin of anesthetized and non-anesthetized groups (p > 0.05). No fluid droplets were found on dentin on the cavity floor prepared in vitro, either before or after acid-etching. For the unetched dentin prepared in situ, fluid droplets were found and covered on the smear layer in anesthetized and non-anesthetized groups, but the droplets were slightly larger in the non-anesthetized group. In the non-anesthetized, acid-etched group, dentin surfaces were covered with coalescent dentinal fluid in most specimens. However, in the anesthetized, acid-etched group, patent tubules and some dentinal fluid were observed on the surfaces. It was concluded that in situ, dentinal fluid had a detrimental effect on the dentin bond strengths of an etch-and-rinse adhesive and a self-etching adhesive. However, reduction in dentinal fluid due to the effect of a local anesthetic containing vasoconstrictor did not improve the bond strengths in either adhesives.

Real-time measurement of dentinal fluid flow during amalgam and composite restoration

This study examined changes in the dentinal fluid flow (DFF) during restorative procedures and compared permeability after restoration among restorative materials and adhesives. A class 1 cavity was prepared and restored with either amalgam (Bestaloy), or composite (Z-250) with one of two etch-and-rinse adhesives (Scotchbond MultiPurpose: MP and Single Bond 2: SB) or one of two self-etch adhesives (Clearfil SE Bond: CE and Easy Bond: EB) on an extracted human third molar which was connected to a sub-nanoliter fluid flow measuring device (NFMD) under 20 cm water pressure. DFF was measured from the intact tooth state through the restoration procedures to 30 min after restoration, and re-measured at 3 and 7 days post-restoration. Inward flow during cavity preparation was followed by outward flow after preparation. In amalgam restoration, the outward flow changed into an inward flow during amalgam filling, which was followed by a slight outward flow after finishing. In composite restoration, MP and SB showed an inward flow and outward flow for the rinsing and drying steps, respectively. Application of a hydrophobic bonding resin in the MP and CE systems caused a decrease in the flow rate. Air-drying of solvent for the CE and EB systems caused a sudden outward flow, whereas light-curing of the adhesive and composite caused an abrupt inward flow. Each restorative step clearly changed the direction and the rate of the DFF during restoration, which could be well identified with NFMD.

Marginal seal stability of one bottle adhesives in Class V vs. Class I cavities

The aim of this study was to test the influence of two different cavity configurations on marginal stability of recent one bottle "etch & rinse" and "self-etch" adhesives in Class V vs. Class I cavities, before and after thermo-mechanical loading under simulation of dentinal fluid. Forty human upper molars were selected and assigned to five experimental groups. Intrapulpal pressure was maintained during cavity preparation, restoration placement, finishing and stressing. Standardized Class I and V-Shaped Class V cavities were prepared on each tooth. Half of the margins of Class V cavities were located in enamel and half in dentin. All cavities were restored with different adhesives systems and a nano-hybrid composite. Materials were light-cured using a LED unit. Restored teeth were loaded in a computer-controlled chewing machine with 1.2 million mechanical occlusal cycles simultaneously with 3,000 thermal cycles (5-50-5°C). Impressions were made with polyvinylsiloxane of each restoration before and after loading. Gold-coated epoxy replicas were prepared for SEM examination at ×200 magnification. Significant differences between materials were found both before and after loading (Kruskal-Wallis, Bonferroni, p < 0.05). Significant differences were also found between Class I and V restorations (Wilcoxon Matched-Pairs Signed-Rank Test, p < 0.05). Even before thermo-mechanical loading, none of the groups had 100% continuous margin. Marginal seal stability of recent one bottle "etch & rinse" and "self-etch" adhesives are significantly different and susceptible to cavity configuration.

Real-time measurement of dentinal fluid flow during desensitizing agent application

Objectives: The aim of this study was to examine changes in the dentinal fluid flow (DFF) during desensi- tizing agent application and to compare permeability after application among the agents. Materials and Methods: A Class 5 cavity was prepared to exposure cervical dentin on an extracted human premolar which was connected to a sub-nanoliter fluid flow measuring device (NFMD) under 20 cm water pressure. DFF was measured from before application of desensitizing agent (SealP SuperSeal, SS; BisBlock, BB; Gluma desensitizer, GL; Bi-Fluoride 12, BF) through application procedure to 5 min after application. Results: DFF rate after each desensitizing agent application was significantly reduced when compared to initial DFF rate before application ( p < 0.05). SP showed a greater reduction in DFF rate than GL and BF did (p < 0.05). SS and BB showed a greater reduction in DFF rate than BF did (p < 0.05). Conclusions: Characteristic DFF aspect of each desensitizing agent was shown in NFMD during the applica- tion procedure. (J Kor Acad Cons Dent 2010;35(5):313-320.) ABSTRACT