SEARCH · PubMed Health

Results for “Dentin”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources

PubMedDate not supplied

The bond of resin to different dentin surface characteristics.

This study investigated the effects of dentin surface characteristics on bond strengths between resin and dentin. The shear bond strengths mediated by two dentin adhesive systems (Clearfil SE Bond and OptiBond Solo Plus) were evaluated. For each material, flat dentin surfaces prepared from human upper premolars were allocated to eight groups according to three characterizations; dentin location (occlusal or cervical), dentin depth (superficial or deep) and dentinal tubule orientation (perpendicular or parallel). A 0.75-mm diameter area of dentin was bonded according to each manufacturer's instructions before placing 0.5-mm high resin composite. The bonds were stressed in shear at a crosshead speed of 1 mm/minute. The mean bond strengths were compared using ANOVA and independent t-test. No statistically significant differences were found in shear bond strengths based on dentin location. Clearfil SE Bond presented higher bond strengths to deep dentin specimens bonded perpendicular to the tubules compared to those that were bonded parallel to the tubules. Whereas, the opposite results were found for deep dentin specimens bonded with OptiBond Solo Plus. In the case of superficial dentin, there were no differences between the two materials when bond strengths were compared among the different orientations of tubule. The results indicated that shear bond strengths may be affected by dentin depth, orientation of the tubule and the bonding material used, but not by location of the dentin.

Analysis of Variance↗

PubMed2007

Hardness, elasticity, and ultrastructure of bonded sound and caries-affected primary tooth dentin.

Biomechanical properties of bonded dentin are important factors for resin restoration. We evaluated the hardness and elastic modulus of bonded sound and caries-affected primary tooth dentin using a one-step adhesive system, and observed the microstructure of the bonded interface. Six sound and six carious primary teeth were used. For sound teeth, flat occlusal dentin surfaces were prepared with a water-cooled high-speed diamond bur. For carious teeth, infected dentin was stained with a caries detector and removed with a water-cooled low-speed round steel bur and hand instruments. The prepared dentin was bonded with One-Up Bond F Plus (Tokuyama Dental Co., Tokyo, Japan). The resin-dentin interface and dentin beneath the interface were measured with a nano-indentation tester and observed with SEM and TEM. For both the carious and sound teeth, there was no significant difference between the hardness of the interfacial dentin and dentin 10-80 microm beneath the interface. However, the Young's modulus of the interfacial dentin was significantly lower than the dentin 40-80 microm (carious teeth) or 50-80 microm (sound teeth) beneath the interface. Both the hardness and Young's modulus of the interfacial dentin were not significantly different between the carious and sound teeth. Compared to the sound dentin, the hybrid layer on the caries-affected dentin was thicker and exhibited more complicated morphologic features. The thickness of the hybrid layers was generally less than 1 microm.

Dental Caries↗

PubMed1994

Efficacy of various commercial dentin bonding systems.

OBJECTIVES: The purpose of this study was to test the bonding efficacy of fifteen commercial dentin bonding systems and also to determine the effect of various commercial dentin cleaners on bonding and dentin hardness. METHODS: Each commercial bonding system was examined by two methods: 1) measuring the maximum contraction gap of a light-cured composite in a cylindrical dentin cavity; and 2) determine the tensile bond strength to a flat dentin surface. In addition, various commercial dentin cleansers were investigated to determine if dentin hardness was reduced after cleaning. As a control, the dentin surface was cleaned with neutralized EDTA prior to the combined application of an experimental dentin primer, a commercial bonding agent, and a commercial light-cured composite. RESULTS: The study demonstrated that complete marginal adaptation was obtained by the experimental dentin bonding system used as the control. However, it was not possible to completely prevent gap formation with the commercial dentin bonding systems tested. A high correlation (R = 0.88) was observed between maximum contraction gap width and reduction of hardness only in the group in which the dentin was rinsed after cleaning. SIGNIFICANCE: It is very important to combine optimal dentin cleansers, primers, and bonding agents to compensate for the polymerization contraction stress of the composite. Therefore, it was speculated that the commercial dentin bonding systems tested in this study consisted of unsuitable materials.

Acid Etching, Dental↗

PubMed2002

Effect of fluoride application on tensile bond strength of self-etching adhesive systems to demineralized dentin.

STATEMENT OF PROBLEM: It has been reported that the bond strength of composite to demineralized dentin is lower than that to sound dentin. This can be a problem in the success of so-called sealed restorations. PURPOSE: The aim of this study was to evaluate the effect of fluoride application on the tensile bond strength of self-etching adhesive systems to demineralized dentin. MATERIAL AND METHODS: One hundred twenty extracted bovine incisors were ground flat with 600-grit silicone carbide paper. Ninety teeth were then immersed in acetate buffer (pH 4.0) to form demineralized dentin. These teeth were randomly divided into 3 groups of 30 each: surfaces treated with fluoride solution (Group NF), surfaces treated with fluoride solution followed by a water rinse (Group RF), and control surfaces with no pretreatment (Group C). The remaining 30 teeth comprised a group with normal dentin surfaces (Group S). Each group was further divided into 3 subgroups of 10 each to test the bond strength test of Clearfil SE Bond, Unifil Bond, and Mac-Bond II. Tensile bond strengths (in MPa) were measured with a universal testing machine at a crosshead speed of 0.5 mm/min. Mean bond strengths were analyzed by 2-way analysis of variance and Fisher's PLSD (P =.05). SEM observations of the surfaces before and after priming and at resin-dentin interfaces in each group were performed. Elemental analysis of the dentin surfaces before priming was also carried out. RESULTS: The bond strengths of the adhesives to demineralized dentin in Groups NF, RF, and C were significantly lower than that of the normal dentin in Group S (P <.05). The mean bond strengths of the 3 adhesives in Group NF were higher than those in Groups RF and C, but a significant difference was observed only when Clearfil SE Bond was used (P <.05). In SEM images the open dentinal tubules on the surface and the resin tag formation at the resin-dentin interface were apparent in Group NF but were not observed in Groups RF and C. On elemental analysis, considerable amounts of fluoride and calcium were detected in the surfaces of Group NF. CONCLUSION: Within the limitations of this study, the surface treatment with fluoride solution supported the resin tag formation at the resin-dentin interface and slightly improved the bond strength of the self-etching adhesive systems tested to demineralized dentin. This result indicated that the fluoride treatment to demineralized dentin might contribute to the success of the sealed restoration.

Analysis of Variance↗

PubMed1999

Dentin permeability after toothbrushing with different toothpastes.

PURPOSE: To evaluate the interaction of smear layer produced during brushing and dentifrice particles. MATERIALS AND METHODS: Dentin disks were obtained from extracted human third molars. Dentin permeability was evaluated using a hydraulic pressure apparatus working at 1 psi of pressure. After preparation, each sample was connected to the hydraulic pressure apparatus to evaluate the permeability of dentin with the smear layer produced during specimen preparation. After 5 min of measurements dentin was etched with 37% phosphoric acid gel for 2 min, washed and gently dried with cotton to measure the permeability after smear layer removal. This was done to measure the maximum permeability of each specimen (expressed as 100%). Then a second smear layer was produced using a #400 carbide paper under water for 1 min. Dentin permeability of the smear layer covered dentin was then measured, and expressed as a percent of the maximum permeability of that specimen, permitting each specimen to serve as its own control. The three toothpastes used (Merfluan powder, Merfluan paste and Fluorigard) were applied on dentin surfaces using a small sponge to completely cover the dentin surface. After 5 s, each sample was connected to a mechanical device and brushed under water for 3 min with constant pressure of 250 gr using a Colgate medium toothbrush. After this treatment, each sample was gently washed with tap water, gently air dried for 3-5 s and connected with the pressure apparatus to remeasure the permeability after brushing. For SEM examination of dentin before and after treatment with toothpaste and brushing, each dentin and enamel sample was fixed in 2% buffered glutaraldehyde. RESULTS: Dentin permeability proved unaffected by dentifrice treatments. SEM observations demonstrated the presence of dentifrice particles on dentin surface and inside dentin tubules. Smear plugs produced during dentin brushing were not removed by dentifrices.

Dentin↗

PubMed2005

[Ultrastructural study of a self-etching adhesive to sclerotic dentin in non-carious cervical lesions].

OBJECTIVE: To examine, in vitro study, the ultrastructure of resin-infiltrated sclerotic dentine following the application of a two-step self-etching dentin adhesive. METHODS: Non-carious, natural cervical sclerotic lesions were bonded using Contax (DMG Hamburg, Germany), a self-etching dentin adhesive. Artificially prepared wedge-shaped lesions were also made in sound bicuspids and bonded using the same adhesive as controls. By SEM examination, the morphological change of the dentin surface treated by Contax Primer, and the hybrid layer and resin tag in the dentin-resin interface were studied. RESULTS: Most dentinal tubules were occluded by rod-like sclerotic casts in the sclerotic dentin surface. Both hybrid layer and resin tag were observed in sclerotic dentin. The hybrid layer was almost similar to that in the sound dentin, but the resin tags were shorter than those in controls. CONCLUSIONS: Bonding to sclerotic dentin is different from sound dentin and may be compromised by occluded dentin tubules. Based on the present ultrastructural features of hybrid layer and resin tags, the Contax, a self-etching dentin adhesive with a low pH value primer, may have some bonding efficacy to sclerotic dentin.

Dentin↗

PubMed2005

Experimental investigation on the role of water in the mechanical behavior of structural dentine.

Dentine is a porous hydrated composite structure that forms the major bulk of the human tooth. The aim of this study was to investigate the role of free water on the in-plane, mechanical strain response in dentine structure. A digital moire interferometry was used for this purpose. It was observed from this experiment that structural dentine demonstrated distinct strain gradients in the axial (perpendicular to the dentinal tubules) and lateral (parallel to the dentinal tubules) directions. The hydrated dentine displayed significant increase in strain with stress in the direction perpendicular to the dentinal tubules, and this response was characteristic of a tough material. On the contrary, the dehydrated dentine, which was dehydrated at 24 degrees C, 55% relative humidity for 72 h showed a strain response characteristic of a brittle material. The strains formed in the direction parallel to the dentinal tubules for hydrated dentine were consistent and did not vary much with increase in applied loads. Upon dehydration, the outer dentine experienced higher strains, and the difference between the outer and inner dentine became more conspicuous with increase in loads. This experiment highlights hydration-induced, distinct in-plane strain gradients in the directions perpendicular and parallel to the dentinal tubules in the dentine structure.

Dentin↗

PubMed2006

Matrix metalloproteinase-8 (MMP-8) is the major collagenase in human dentin.

OBJECTIVE: Previously an unidentified collagenolytic metalloprotease together with gelatinase (matrix metalloproteinase-2, MMP-2), and enamelysin (MMP-20) have been detected in human dentin. The aim of the study was to characterize dentinal collagenolytic enzymes. Furthermore, we hypothesized that the dentinal MMPs are protected by the mineral phase, and studied the stability of dentinal MMPs. DESIGN: To characterize dentinal collagenolytic enzymes, we used Western blotting with specific antibodies against MMP collagenases (MMP-1, -8, and -13) and cathepsin K. MMP-8 immunofluorometric assay (IFMA) was also used for MMP-8 detection, and functional collagenase activity was examined with type I collagen degradation assay. The stability of dentinal MMPs was examined by autoclaving dentin blocks before protein extraction and subsequent examination of protein levels and the activities of dentin collagenase and gelatinases. RESULTS: MMP-8 (collagenase-2) was detected in dentin both with Western blot and IFMA, and dentinal samples also cleaved the intact type I collagen into characteristic 3/4(alphaA)-cleavage products in vitro. No other collagenases or cathepsin K were detected. In autoclaved samples no MMP-8 was found, but gelatinase activity was observed in protein fractions of mineralized dentin. CONCLUSIONS: MMP-8 represents the major collagenase in human dentin. Unlike MMP-8, dentinal gelatinases can be detected after autoclave treatment of dentin, indicating their high resistance to external sample treatment procedures.

Adult↗

PubMed2006

Influence of rotating-oscillating, sonic and ultrasonic action of power toothbrushes on abrasion of sound and eroded dentine.

OBJECTIVE: This in vitro study aimed to evaluate the susceptibility of sound and eroded dentine to brushing abrasion performed by different rotating-oscillating, sonic and ultrasonic toothbrushes. METHODS: Toothbrushing abrasion (20 cycles, each 30 s) was applied to bovine dentine samples (each subgroup n = 10) exhibiting both a demineralized (each cycle: 1% citric acid, pH: 2.3, 60 s; 30 min remineralization in artificial saliva) and a sound surface area. Toothbrushing was performed in an automatic brushing machine with the rotating-oscillating, sonic and ultrasonic toothbrushes either (a) activated, supplemented by 20 strokes/min of the brushing machine, (b) inactivated, supplemented by 20 strokes/min of the brushing machine or (c) inactivated, supplemented by 80 strokes/min of the brushing machine. A manual toothbrush was applied with 20, 80 or 100 linear strokes/min. Specimens of the control group were not brushed after erosion. After each cycle, the samples were stored in artificial saliva for 4 h. After 20 cycles, loss of sound and softened dentine was determined by profilometry. Mann-Whitney-Wilcoxon test and Bonferroni corrections were applied to the data (p < 0.05). RESULTS: For all groups, demineralized dentin areas exhibited significantly higher abrasion values than the respective sound dentine surfaces. However, mean dentine loss of both softened and sound dentine was higher after use of the rotating-oscillating, sonic and ultrasonic brushes with the activated regime [(a) eroded dentine: 9.94-16.45 microm; sound dentine: 3.31-5.47 microm] than after brushing with the inactivated regimes [(b) eroded dentine: 5.10-5.62 microm; sound dentine: 1.16-1.81 microm; (c) eroded dentin: 7.64-8.89 microm; sound dentine: 1.38-1.69 microm]. CONCLUSION: The results indicate that rotating-oscillating, sonic or ultrasonic action of the power toothbrushes leads to an increased loss of demineralized and sound dentine.

Animals↗

PubMed2000

Distribution of interglobular dentine in human tooth roots.

The present study was designed to examine the distribution of interglobular dentine in human tooth roots. The material comprised 17 teeth, of which 3 were premolars extracted for orthodontic reasons from children 10-12 years of age and the other teeth (4 incisors, 3 canines and 7 molars) were extracted for periodontitis from individuals aged 32-63 years. All teeth were free of caries and cervical dentine defects. Ground sections of the teeth cut longitudinally were stained with basic fuchsin and observed by fluorescence and confocal microscopy as well as transmitted light microscopy. Basic fuchsin stained the dentinal tubules, interglobular dentine and the granular layer of Tomes. These structures appeared intense blue to faint violet with transmitted light microscopy, whereas their staining displayed intense fluorescence with fluorescence microscopy. Therefore, the interglobular dentine could be detected more sensitively with fluorescence and confocal microscopy than with transmitted light microscopy. Typical interglobular dentine was present in coronal dentine in most of the teeth. In the radicular dentin, position and size of the interglobular dentine was different among the teeth examined. Most of the teeth had the interglobular dentine in the cervical part of the roots (type A). Two premolars displayed the interglobular dentine in the coronal half of the root (type B). The types A and B contained large interglobular areas. A small amount of interglobular dentine was restricted to the apical half of the roots of two canines and one molar (type C). In contrast to types A and B which were seen at both labial or buccal and lingual sides of roots, the interglobular dentine of type C was seen only at one side, labial or lingual. Some of the tooth roots did not show any interglobular dentine (type D). Most of the incisors, canines and premolar were types A, B, and C, respectively, and the molars were mixed types A, C, and D. These results suggest that the factors affecting dentinogenesis during root formation are unique for each tooth.

Adult↗

PubMed2002

The extent of odontoblast processes in the dentin is distinct between cusp and cervical regions during development and aging.

The question of whether odontoblast processes extend to the dentinal surface has been widely debated in previous studies. In this study odontoblast processes were investigated in the developing and aging dentin of rats and monkeys (Japanese macaques). For this purpose, F-actin of microfilaments and cellular membranes were stained with phalloidin and DiI, respectively. This dual staining demonstrated that positive signals for odontoblast processes were present in the dentinal surface in both the cusp and cervical regions of the dentin at 2 weeks of age. The tips of doubly positive processes were detectable in the dentinal surface in the cusp region even at 100 weeks of age, whereas in the cervical region they were retracted from the dentinal surface towards the pulp during the period of 3-6 weeks of age. During these stages, phalloidin-positive signals showing retracted odontoblast processes in the cervical region were closely associated with the interglobular dentin that was stained with sWGA-lectin. After 6 weeks of age, no association was observed between the processes and the interglobular dentin, since they were retracted approximately to the inner third portion of the dentinal tubules. This staining pattern can be detected until 100 weeks of age. Moreover, different distribution patterns of odontoblast processes between the two dentinal regions were also confirmed in dentin of monkey teeth. These results suggest that the existence of the regional differences in the extent of the odontoblast processes in the dentin, i.e., the persistence of the processes in the dentinal surface in the cusp region and their retraction from the dentinal surface in the cervical region.

Aging↗

PubMed2001

Effect of antimicrobial agents on the micromorphology of primary dentin.

The use of disinfectants on the dentin surface contributes to superficial cleaning and removal of remaining microorganisms of the carious process. However, the effect of these agents on the adhesion of resin materials to the dentin surface of primary teeth has not been established. This study evaluated the dentin micromorphological effects due to the use of antimicrobial agents in the different depths of dentin. Twenty-five buccal surfaces of primary molars were prepared from the sectioned teeth, ground flat and polished with silicon carbide paper of different grits. The surfaces were treated with 32% phosphoric acid with benzalkonium chloride (Bisco), 35% phosphoric acid gel (3 M), 3% benzalkonium chloride solution by itself or 10% maleic acid. All agents were applied for 15 seconds on the dentin surface. The samples were washed with distilled water, dried and coated with gold for observation of the dentin surface with the scanning electron microscope. The samples were subdivided according to the dentin depth in upper, middle and lower areas. The following was observed: presence of smear layer, opening of the dentin tubules, and inter and intratubular dentin morphology. The effects of the antimicrobial agents were compared in the different depths of the dentin. The results demonstrated that the surface conditioned with 3% benzalkonium chloride solution presented few disclosed dentin tubules. The use of the 32% phosphoric acid with benzalkonium chloride completely removed the smear layer and increased the diameter of the dentin tubule openings. The 35% phosphoric acid totally exposed the tubules in the upper area of the analyzed surface but partially exposed them in the middle and lower areas. The 10% maleic acid totally removed the smear layer, left all the tubules opened and conditioned the intertubular dentin. It was concluded that in the different depths of the dentin surface, conditioning with 10% maleic acid in primary teeth showed the most consistent micromorphological characteristics compared to the other agents used in this study.

Acid Etching, Dental↗

PubMedDate not supplied

Influence of air-abrasion treatment on the interfacial bond between composite and dentin.

The purpose of this in vitro study was to investigate the effect of air abrasion on the interfacial bond between composite and dentin. Dentin surfaces surrounded by enamel were produced by removing the incisal part of the crown from extracted human anterior teeth. The dentinal area of the specimen surfaces was conditioned either by air-abrasion treatment (27 microns aluminum oxide particles, 120 psi), application of dentin adhesives, and combination of air abrasion and dentin adhesives, or left nontreated (controls). The enamel was conditioned by acid etching, by air abrasion, or by air abrasion and subsequent acid etching. A 2 mm layer of six different composite resins (Brilliant, Charisma, Helioprogress, Herculite, Pekafill, Z-100) was applied on the specimen surfaces and light cured. The composite dentinal interface was evaluated in cross-cut sections of 324 specimens by SEM analysis, and the mean gap width (MGW) between composite and dentin was calculated. SEM analysis revealed gap formation ranging from 1.1-3.6 microns in control specimens. Gap width was reduced significantly due to air-abrasion treatment of the dentinal surface (MGW: 0.3-1.4 microns) or by application of dentin adhesives (MGW: 0.06-0.6 micron). Combined air-abrasion treatment and application of dentin adhesives resulted in a gap-free adaptation between composite and dentin in the majority of specimens. However, thermocycling of the specimens (5 degrees C/55 degrees C; 1000 cycles) caused a significant increase in gap formation (MGW: 0.03-2.9 microns) at the composite-dentin interface. It is concluded that air-abrasion treatment and subsequent application of a dentin adhesive is an effective procedure to resist the contraction stress at the dentinal surface during polymerization of the composite resin and to improve the internal bond of composite resin restorations.

Air↗

PubMed1997

Sealing depth of Nd:YAG laser on human dentinal tubules.

Dentin permeability and hypersensitivity are both reduced when the dentinal tubules are occluded. Previous scanning electron microscopic studies showed that Nd:YAG laser could cause melting of dentin and closure of exposed dentinal tubules without dentin surface cracking. Therefore, the aim of the present study was to evaluate the sealing depth of Nd:YAG laser on human dentinal tubules. Thirty-six dentin specimens with exposed dentinal tubule orifices were used in this study. Samples were randomly divided into three groups. Groups A and B were lased by Nd:YAG laser at energy of 30 mJ with 10 pulses/s for a stroke along the dentin surface. Group C was not lased and served as a control. Subsequently, group B was frozen in liquid nitrogen and split by a sharp chisel. Under SEM observation, nonlased specimens showed numerous exposed dentinal tubule orifices, and lased specimens showed melting of dentin and closure of exposed dentinal tubule orifices. The sealing depth of Nd:YAG laser on human dentinal tubules was approximately 4 microns.

Dentin↗

PubMed2006

Effects of plaque control on the patency of dentinal tubules: an in vivo study in beagle dogs.

BACKGROUND: The aim of this in vivo study was to evaluate the effects of plaque control on the patency of dentinal tubules using vital teeth of beagle dogs. METHODS: Class V cavities were prepared on the cervical areas of the mandibular and maxillary molars in each dog with a diamond point. To simulate the state of dentinal hypersensitivity, the teeth were etched with 50% citric acid for 2 minutes to obtain patent dentinal tubules. Plaque control was achieved by brushing the left-side teeth every day, whereas no plaque control was performed for the right-side teeth. A dentin biopsy was performed after 1, 2, and 3 weeks using the cylindrical diamond point to obtain dentin specimens. RESULTS: In the plaque control group, some of the dentinal tubules were occluded with precipitate (Ca/P=1.49), and the diameter of the dentinal tubules decreased from 2.42+/-0.33 microm (mean+/-SD) to 1.11+/-0.51 microm after 7 days, although most of the dentinal tubules remained open. In contrast, no precipitate was observed in the dentinal tubules of the non-plaque control group. Also, the diameter of the dentinal tubules increased from 2.42+/-0.33 to 2.9+/-0.49 microm, due to the demineralization of the peritubular and intertubular dentin. CONCLUSION: Plaque control plays a key role in reducing the patency of dentinal tubules and, therefore, might promote the natural repair of dentinal hypersensitivity.

Analysis of Variance↗

PubMed1995

Does resin based dentine bonding work?

Since Buonocore, in the mid 1950s, introduced enamel etching to be used to bond resinous restorations to enamel, different resin based bonding procedures have continuously found their way into dental practise. Today, dentists bond materials not only to enamel, but also to dentine. Up until recently, the clinical success with dentine bonding agents had been unreliable at best, and many clinicians had become sceptical as to whether it would ever be possible to bond to dentine. In this paper, some of the important break-throughs in the field of dentinal adhesives are reviewed in an attempt to throw some light on the question, does resin based dentine bonding work? The technical procedure used to optimise dentine bonding is reviewed, emphasising the significance of etching dentine, placing the primer on a slightly moist dentine surface, avoiding oxygen inhibition of the bonding resin, and maximising the degree of cure. In addition, emphasis is also placed on the significance of variations in dentine structure, and how sclerotic dentine may make dentine bonding less efficient. The conclusion of the entire review is that although significant improvements have been made in the field of dentine bonding during the last few years, it is still too early to conclude that dentine bonding will survive several years of clinical service.

Acid Etching, Dental↗

PubMed1994

The neurophysiological basis and the role of inflammatory reactions in dentine hypersensitivity.

Recent studies indicate that intradental A-type nerve fibres are responsible for the sensitivity of dentine and are activated by fluid movements in dentinal tubules (hydrodynamic mechanism). The patency of the tubules affects dentine sensitivity to a great extent. Both A delta- and A beta-type nerve fibres respond to dentinal (hydrodynamic) stimulation in a similar way. Only a few studies have been made on the regional sensitivity of dentine or the receptive areas of intradental nerve fibres. The results indicate that the fibres innervating different parts of coronal dentine are equally sensitive to dentinal stimulation but those in the cervical area may be less responsive. Inflammation in the pulp can considerably alter dentine sensitivity. In dog teeth with chronically exposed dentine, nerve responses to hydrodynamic stimulation were reduced although other functional changes indicated nerve sensitization. This may be due to spontaneously occurring changes in the exposed dentine that block the tubules. In acute experiments on cat and dog teeth with open dentinal tubules, certain inflammatory mediators increase the sensitivity of the responding nerve fibres. It seems that intradental C-fibres do not respond to hydrodynamic stimulation of dentine. They are polymodal and activated when external stimuli reach the pulp proper. They could perhaps mediate the dull pain connected with pulpitis. However, they might also have an important modifying effect on dentine sensitivity because they can release neuropeptides, which function in the inflammatory reactions.

Animals↗

PubMed2000

Pilot study of conditioner/primer effects on resin-dentin bonding after provisional cement contamination using SEM, energy dispersive x-ray spectroscopy, and bond strength evaluation measures.

STATEMENT OF PROBLEM: Previous studies have shown that provisional cement cannot be completely removed from the dentin surface and the remnants inhibit adhesion of resin cement to dentin. PURPOSE: This study investigated the effects of dentin conditioners on resin-dentin bonding after provisional cement contamination. MATERIAL AND METHODS: A total of 216 bovine dentin specimens were divided into 2 groups with and without provisional cement coating on the dentin surface. Each group was further divided into 3 subgroups with 2 conditioning methods and without dentin conditioning (36 specimens per subgroup). The 2 methods applied were (1) phosphoric acid etching and (2) phosphoric acid etching, followed by sodium hypochlorite gel. Provisional cement was completely removed with a curette before dentin conditioning. Stainless steel rods were luted to dentin surfaces with Panavia 21 resin cement. Tensile bond strengths were measured before and after thermocycling. The dentin surface was analyzed by SEM and energy dispersive x-ray spectroscopy. Three-way ANOVA and Scheffe's comparison test were performed (P =. 05). RESULTS: Bond strength was significantly influenced by provisional cement application, type of dentin conditioning, and thermocycling. Bond strength decreased when treated with provisional cement, but the decreased strengths were restored to their original values or higher by both dentin conditioners used. Specimens treated with sodium hypochlorite gel applied after phosphoric acid etching demonstrated the highest bond strengths with good stability after thermocycling. CONCLUSION: Application of sodium hypochlorite gel after phosphoric acid etching was more effective than etching with phosphoric acid alone to eliminate the inhibitory effect of provisional cement remnants on adhesion between resin cement and dentin.

Acid Etching, Dental↗