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PubMed2005

Tooth brushing, tooth wear and dentine hypersensitivity--are they associated?

Evidence suggests that patients suffer the painful symptoms of dentine hypersensitivity when dentine is exposed and the dentinal tubule system is opened to the oral cavity to allow stimuli to trigger a neural response in the pulp via a hydrodynamic mechanism. The processes needed to localise lesions of dentine hypersensitivity include loss of enamel and/or gingival recession. Whilst tooth brushing with or without toothpaste appears to cause minimal wear to enamel (in the absence of acids), circumstantial evidence implicates tooth brushing with gingival recession and exposure of dentine. Other tooth wear processes notably attrition and acid erosion cause loss of enamel and can expose dentine. Therefore sensitivity may result. How lesions of dentine hypersensitivity are initiated is a matter of conjecture and based on extrapolating data from studies, mainly in vitro, to affect in vivo. Again this circumstantial type of evidence suggests that abrasion by some toothpastes and erosion by dietary acid could open the tubule system. Little is known about the actual effect of desensitising toothpastes on lesions of dentine hypersensitivity even though they are formulated to either occlude dentinal tubules or block the neural response in the pulp. Clinical studies have produced contradictory findings for the efficacy of products and there have been extremely few evidence based reviews. In conclusion, available evidence supports a probable link of tooth brushing, with or without toothpaste and an acidic diet to both tooth wear and dentine hypersensitivity, and suggests also that dentine hypersensitivity is a tooth wear phenomenon. Although there is a need for more direct clinical and scientific evidence for these associations, it is recommended that they be taken into consideration when planning management strategies for the dentine hypersensitivity sufferer.

Dental Enamel↗

PubMed2000

The dentinal structure of equine incisors: a light and scanning electron-microscopic study.

This paper gives an anatomical overview of the dentinal structure in equine incisor teeth with special reference to the three-dimensional organization, the number and the diameter of the dentinal tubules. The spatial arrangement of equine dentine was examined by scanning electron microscopy of occlusal surfaces and longitudinally fractured teeth and by light microscopy of both decalcified and ground sections. The dentinal tubules of the peripherally situated primary dentine were directly continuous with those of the circumpulpal secondary dentine. The tubules had numerous side branches along their entire course and ramified into terminal branches near the dentino-enamel junction. Tubules of tertiary dentine, situated in the centre of the dental star, were few in number and not continuous with those of the surrounding secondary dentine. On non-etched incisors tubular orifices were clogged by an amorphous smear layer that covered the occlusal surface. On etched occlusal surfaces the numerical tubular density was calculated in different zones. The largest number of tubules per unit area was situated in the secondary dentine forming the dark periphery of the dental star, whereas the smallest number was present in the tertiary dentine located in the pale centre of the dental star. Dentinal tubular diameters were measured at various distances from the pulp. They were widest near the pulpal wall and narrowed progressively towards the dentino-enamel junction. Tubular widths measured on etched occlusal surfaces were considerably larger than those measured on undecalcified incisors due to the removal of intratubular dentine during the etching process.

Animals↗

PubMed1991

[Dentin adhesives. An update].

Even if mechanical bonding to enamel utilizing the acid-etch technique has been very successful, adhesion to dentin is still a challenge to researchers and clinicians. Dentin is a vital tissue and differs in composition from enamel: acid-etching does not enhance the bond strength of composite resins to dentin and may elicit a severe pulpal response. For an effective bond to occur, a dentin bonding system has to be used. The first generation of methacrylate-based dentin adhesives was capable of chemical bonding to the inorganic phase of dentin. The chemical basis for this resin-dentin adhesive was the interaction between a phosphate group attached to the methacrylate and the calcium ions on the dentin surface. This system yielded rather low bond strengths which were clinically unsatisfying. The second generation of dentin adhesives became available to the profession recently. Each of these new bonding systems use similar chemical composition for the same purpose of bonding with physicochemical interaction to the hard tooth tissues. All these systems contain a mild acid dentin conditioner to remove the smear layer and an aqueous resin containing primer to improve monomer penetration into the hydrophilic dentin surface. The second generation dentin bonding systems are extremely sensitive to variations upon the completeness of instructions and how accurately these are followed by dental practitioners.

Acid Etching, Dental↗

PubMed1989

[Mineralization patterns in the dentine of the floor of the pulp chamber of porcine molars].

The relationship between the arrangement of the matrix fibre bundles and the shape of the mineralization front (mineralization pattern) were observed in the dentine of the subpulpal wall of porcine molars. The observations were made using mainly light microscopy and scanning electron microscopy on the primary dentine excluding the secondary dentine. The results obtained shows that the dentine of the subpulpal wall consists of two parts, a surface layer and the circumpulpal dentine. The surface layer can be divided into two sublayers according to the arrangement of it's matrix fibres. The mineralization pattern was also observed to have another two sublayers which did not correspond with the two fibrous subdivisions. Adjacent to the dentine-cement junction, there is a layer, measuring about 3 microns in thickness, in which the matrix fibres run parallel to the junction. The second layer is characterized by two types of fibre bundles which run perpendicularly to the dentine-cement junction. These outer radially oriented fibres are about 1-2 microns in diameter, and the inner radially oriented fibre bundles are coarse, 10 microns in diameter. In the outermost 10 microns, mineralization begins as an aggregation of mineral granules, and forms a hypermineralized layer which overlays the junctional region between the fibres which are oriented parallel and perpendicular to the dentine-cement junction. Except for the most-superficial layer, mineralizing cones surround the radial fibre bundles at the mineralizing front. The circumpulpal dentine, which forms the floor of the pulp chamber, can also be divided into two layers by the differences in their fibrous matrix. The fibres of both of these layers lay in the plane of the predentine surface. However, in the outer layer the fibres of the matrix are randomly arranged around and between the dentinal tubules, whereas in the inner layer the fibres have a preferred orientation extending radially from a central region between the roots. In the outer layer, calcospherites, which are the units of the mineral aggregation, appear at the mineralizing front. In the inner layer, at the mineralizing front, ridges, measuring approximately 10-15 microns in width, 10 microns in height and 100 microns in length, also have a preferred orientation, 90 degrees to the fibre direction. Microradiographs show that a higher mineralized "lamellae-like' region exists in the center of each ridge-crest. X-ray diffraction indicates two preferred crystallite orientation, one is parallel to the matrix fibres and the other perpendicular to the predentine surface. The latter seems to be situated in the highly mineralized lamellae. In the circumpulpal dentine, therefore the mineralizing units have a spheritic shape in the outer layer, and a columner shape in the inner layer. As far as the author is aware the columnar mineralization unit in mammalian dentine has not been described before.

Animals↗

PubMed1997

Dentin bond strength of Dyract Cem.

PURPOSE: To evaluate the influence of provisional cements and of a dentin bonding agent on the adhesion of a self-curing polyacid-modified resin composite (Dyract Cem) on pressurized human dentin. MATERIALS AND METHODS: Freshly prepared dentin specimens of human teeth were perfused with physiologic saline. Three different types of surface treatment were evaluated. (1) Dyract Cem was applied to freshly prepared dentin without (Group 1.1) or with (Group 1.2) the respective dentin bonding agent (Prime & Bond 2.0) and cured. (2) Freegenol (Groups 2.1 and 2.2) or Temp Bond (Groups 2.3 and 2.4) were applied first on the dentin surface for 24 hours. Only then was Dyract Cem (with or without Prime & Bond 2.0) added onto the dentin after cleaning the dentin surface with pumice. 3) Prime & Bond 2.0 was applied first on the dentin surface and cured. Then Freegenol (Group 3.1) or Temp Bond (Group 3.2) were added for 24 hours. After cleaning with pumice, Prime & Bond 2.0 was applied for a second time on the dentin (= dual application) and finally Dyract Cem was added. As control, a conventional glass ionomer cement (Ketac-Cem Maxicap; Groups 4.1-4.3) was used in a similar way. After 1,500 thermal cycles with constant imitation of intrapulpal pressure, shear bond strengths were measured. Resulting shear bond strength values were displayed by means of a box plot and they were analyzed statistically by Mann-Whitney, Kruskal-Wallis or one way ANOVA tests. RESULTS: Lowest and highest mean shear bond strength values were 0.27 +/- 0.42 MPa (Group 2.4; single use of Prime & Bond 2.0 with prior application of TempBond) and 5.84 +/- 3.36 MPa (Group 3.1; dual use of Prime & Bond 2.0 with intermediate application of Freegenol). A clearly significant difference between groups could only be found when a single or dual use of the dentin bonding agent Prime & Bond 2.0 were combined with either Freegenol (Groups 2.1, 2.2 and 3.1; Kruskal-Wallis: P < 0.01) or Temp Bond (Groups 2.3, 2.4 and 3.2; Kruskal-Wallis: P < 0.001) as additional dentin surface treatment.

Adhesiveness↗

PubMed1996

The density and branching of dentinal tubules in human teeth.

Detailed knowledge of dentine structure, and especially that of the dentinal tubules, is essential in order to understand dentine permeability and to interpret data from investigations on dentine adhesive materials. The aim here was to examine the density and branching of dentinal tubules in human teeth by light and scanning electron microscopy. Stained and unstained demineralized sections and undemineralized fractured specimens were studied. Statistically significant differences in the density of tubules were found depending on location. Differences in density of tubules between the peripheral and inner aspects were more marked in the crown than in root. The mean number of dentinal tubules in the middle part of the root was significantly lower than in the middle part of the crown. The density of the tubules in the outer dentine at the cusp location was also significantly different from that subjacent to the occlusal fissure. The number of branches of dentinal tubules was particularly abundant in locations where the density of tubules was low. The branching patterns revealed an intricate and profuse canalicular, anastomosing system, criss-crossing the intertubular dentine. Three types of branches, major, fine and microbranches, were identified on the basis of size, direction and location. Major branches, 0.5-1.0 micron dia., were the typical delta branchings found peripherally. Fine branches, 300-700 nm dia., forked off at 45 degrees and were abundant in areas such as in the root where the density of the tubules was relatively low. Microbranches, 25-200 nm dia., extended at right angles from the tubules in all parts of the dentine. The findings emphasize the need for detailed characterization of dentine substrates for adhesive testing and of samples used in permeability studies.

Adolescent↗

PubMed2004

Effect of dentin perfusion on the sealing ability and microtensile bond strengths of a total-etch versus an all-in-one adhesive.

OBJECTIVES: To test the null hypothesis that perfusion of dentin has no effect on the sealing or bond strength in Class V resin composite restorations using a two-step total-etch (Scotchbond 1), or a one-step self-etch (all-in-one) (Prompt L-Pop) adhesive. METHODS: Dentin permeability in Class V cavity preparations cut into extracted human third molars was measured in a fluid transport setup. Resin composites were placed using either Scotchbond 1, or Prompt L-Pop with or without dentin perfusion at 1.47 kPa. Permeability was re-measured, and the reduction in permeability was calculated as a percentage of the initial value. Additionally, microtensile bond strength (microTBS) to dentin was measured. RESULTS: Whereas the ability of Scotchbond 1 to seal dentin was significantly decreased due to dentin perfusion (p = 0.00025), that of Prompt L-Pop was not affected (p = 0.099). Scotchbond 1 produced significantly less dentinal seal than Prompt L-Pop only in the restorations carried out with perfusion (p = 0.0003), in the absence of perfusion, however, the difference was not significant (p = 0.343). Dentin perfusion significantly decreased the microTBS of Scotchbond 1 to dentin (p = 0.001). Due to excessive premature failure during sectioning, microTBS test could not be performed with Prompt L-Pop. SIGNIFICANCE: Dentinal fluid flow may have detrimental effects on the sealing ability of dental adhesives depending on the type of adhesive used. Studies aiming to rank adhesives in relation to their sealing ability in vitro should not disregard dentin perfusion.

Acid Etching, Dental↗

PubMed2000

Dimensional changes of demineralized dentin treated with HEMA primers.

OBJECTIVES: The purpose of this study was to measure the dimensional changes of demineralized dentin before and after application of HEMA (2-hydroxyethyl methacrylate) by confocal laser scanning microscopy (CLSM). METHODS: The middle portion of bovine dentin was ground, polished, and covered with a vinyl tape with a 4-mm hole punched through it. A strip of polysiloxane impression material was then placed across the center of the dentin surface to preserve a strip of the original unetched surface. Dentin surfaces were etched with 32% phosphoric acid for 60 s and rinsed with water. The impression material was then removed and the following sequential steps were performed: the dentin surface was mildly air-dried, then strongly air-dried, then treated with either 35 wt.% HEMA/water or 100 wt.% HEMA and mildly air-dried, and then strongly dried again. The shrinkage of the demineralized dentin surface from the original unetched level was measured by CLSM in each step and results analyzed by one-way ANOVA. RESULTS: The dimensional changes of demineralized dentin after mild air drying were approximately -1 micron and, following strong air drying, resulted in -5 microns shrinkage. Following the application of 35 wt.% HEMA/water, the height of the demineralized dentin changed to a level of -3.3 microns, but then shrank to -4.8 microns after strong drying. ANOVA indicated that re-expansion of the shrunken etched dentin was significant (p < 0.05); however, the treated surface collapsed when it was strongly dried again (p < 0.05). 100% HEMA did not re-expand the shrunken demineralized dentin under any of the application on protocols (p > 0.05). SIGNIFICANCE: Thirty-five wt.% HEMA in water re-expanded the collapsed demineralized dentin matrix, however not to the original level. One hundred wt.% HEMA did not cause any re-expansion.

Acid Etching, Dental↗

PubMed1999

Effect of removal of surface collagen fibrils on resin-dentin bonding.

OBJECTIVES: The aim of this study was to evaluate the effects of NaOCl at removing the demineralized layer by examining the morphology of the hybrid layer and measuring shear bond strengths after different dentin treatments. METHODS: Dentin disks were treated with: (1) 35% phosphoric acid (PA) 20 s; (2) PA treatment followed by 1.5% NaOCl, 2 min; (3) PA treatment, followed by a 10% NaOCl immersion for 120 h. SEM was used to analyze the morphology of dentin and its interface with dentin bonding agents (DBAs), while shear bond strength tests were used to measure adhesion. All specimens were then fractured into two halves: One half was inspected under SEM; the other half was sequentially placed in 10% PA followed by 12.5% NaOCl for 70 h, to remove all dentin from the resin replica of the original bonded interface. RESULTS: SEM observations showed that collagen fibrils were completely removed from the acid-etched surface by NaOCl treatment. The diameter and the size of dentinal tubules and the number of lateral branches of the tubules were increased following NaOCl treatment. NaOCl applied on dentin smear layers did not significantly modify their SEM morphology. Resin tags were larger in diameter after phosphoric acid/NaOCl treatment than after only phosphoric acid treatment. Resin-infiltrated dentin-layers were only observed after the single phosphoric acid (i.e. conventional etching) procedure, and were not observed after combined phosphoric acid/NaOCl treatment. Etched/NaOCl samples showed a lower bond strength using Scotchbond MP and 3M Single Bond, but were higher in Optibond FL and unmodified in Prime & Bond 2.0 groups when compared with acid-etched controls. Treatment of etched dentin with NaOCl for 120 h produced an unusual type of resin infiltration of mineralized dentin that could be called a "reverse hybrid layer" which may explain the mechanism of resin bonding to NaOCl treated dentin. SIGNIFICANCE: The use of acidic conditioners for exposure of the collagen matrix exposes a soft delicate mesh that can collapse, thereby interfering with resin infiltration. If acid-etching is followed by NaOCl treatment, high bond strengths can be achieved via "reverse hybrid layer" formation, a proposed new mechanism of micromechanical resin retention. This mechanism is not yet recommended for clinical use but demonstrates a new type of resin retention.

Adolescent↗

PubMed2002

Effect of HEMA on bonding of Er:YAG laser-irradiated bovine dentine and 4-META/MMA-TBB resin.

The purpose of this study was to evaluate the priming effect of 2-hydroxyethylmetaclirate (HEMA) following acid treatment on resin bonding to prototype Er:YAG laser-irradiated dentine. Extracted bovine dentine following laser irradiation was acid treated by aqueous solution of 10% citric acid (10-0) or 10% citric acid/3% ferric chloride (10-3), and additionally treated with 35% HEMA. Pre-treated dentines were bonded to the polymethyl-methacrylate (PMMA) rod with 4-META/MMA-TBB resin (Super Bond C & B) and miniaturized dumbbell-shaped bonded specimens were prepared. These specimens profiled for tensile bond testing and fractured surfaces were observed by scanning electron microscopy (SEM). Cross-sections of resin-dentine interface were also examined. The HEMA treatment following acid conditioned by 10-3 or 10-0 for both laser-irradiated and non-irradiated dentines was significantly higher than that without HEMA treatment. SEM view of a fractured specimen showed some cohesive failure in cured resin, but almost all of the fractured surface shows boundary failure between the penetrated resin and underlying dentine. A cross-sectional view of the interface showed a very thick hybrid layer between the hybridized dentine and underlying dentine. It was concluded that HEMA treatment following acid conditioning provided a slightly higher bond strength for both the Er:YAG laser-irradiated and non-irradiated dentines. However, the bond strength of Er:YAG laser irradiated dentine was significantly lower than that of the non-irradiated dentine.

Animals↗

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↗

PubMedDate not supplied

Effect of desensitizers on the bond strength of a self-etching adhesive system to caries-affected dentin on the gingival wall.

A self-etching dentin adhesive was evaluated for its ability to bond to caries-affected and sound dentin after applying three desensitizers to the gingival walls. Sixty extracted human molars, with approximal dentin caries, were cut horizontally on the long axis of the tooth through caries-affected gingival walls. Carious dentin was removed with SiC paper by means of a caries detector to expose caries-affected dentin. The molars were randomly assigned to four groups: control and three experimental groups-Micro Prime, Glauma Desentizer and Cervitec. Desensitizers were applied to the dentinal surfaces according to manufacturers' instructions. A resin composite was bonded to both the caries-affected and sound dentin of each tooth using a bonding system and plastic rings. The restoration was debonded by shear bond strength. The application of Micro Prime and Gluma Desensitizer to caries-affected dentin did not show any effect on bond strength testing. However, Cervitec caused a decrease in bond strength to caries-affected dentin. The effect of desensitizers on the bond strength of the self-etch bonding agent to caries-affected dentin changed according to the chemical composition of the materials. Desensitizer application on sound dentin is recommended with self-etch bonding systems.

Benzethonium↗

PubMed2006

Tooth brushing, tooth wear and dentine hypersensitivity--are they associated?

Evidence suggests that patients suffer the painful symptoms of dentine hypersensitivity when dentine is exposed and the dentinal tubule system is opened to the oral cavity to allow stimuli to trigger a neural response in the pulp via a hydrodynamic mechanism. The processes needed to localise lesions of dentine hypersensitivity include loss of enamel and/or gingival recession. Whilst tooth brushing with or without toothpaste appears to cause minimal wear to enamel (in the absence of acids), circumstantial evidence implicates tooth brushing with gingival recession and exposure of dentine. Other tooth wear processes, notably attrition and acid erosion, cause loss of enamel and can expose dentine. Therefore, sensitivity may result. How lesions of dentine hypersensitivity are initiated is a matter of conjecture and based on extrapolating data from studies, mainly in vitro, to effect in vivo. Again, this circumstantial type of evidence suggests that abrasion by some toothpastes and erosion by dietary acid could open the tubule system. Little is known about the actual effect of de-sensitising toothpastes on lesions of dentine hypersensitivity even though they are formulated to either occlude dentinal tubules or block the neural response in the pulp. Clinical studies have produced contradictory findings for the efficacy of products and there have been extremely few evidence-based reviews. In conclusion, available evidence supports a probable link of tooth brushing, with or without toothpaste and an acidic diet, to both tooth wear and dentine hypersensitivity, and also suggests that dentine hypersensitivity is a tooth wear phenomenon. Although there is a need for more direct clinical and scientific evidence for these associations, it is recommended that they be taken into consideration when planning management strategies for the dentine hypersensitivity sufferer.

Journal Article↗

PubMed1983

Autoradiographic location of sensory nerve endings in dentin of monkey teeth.

We have used the autoradiographic method to locate trigeminal nerve endings in monkey teeth. The nerve endings were labeled in two adult female Macaca fascicularis by 20 hours of axonal transport of radioactive protein (3H-L-proline). We found a few labeled axons in contralateral mandibular central incisors and one mandibular canine. In ipsilateral teeth, numerous myelinated and unmyelinated axons were labeled; they formed a few terminal branches in the roots but primarily branched in the crown to form the peripheral plexus of Raschkow and to terminate as free endings in the odontoblast layer, predentin, and as far as 120 micrometers into dentinal tubules. Electron microscopic autoradiography showed that the radioactive axonally transported protein was confined to sensory axons and endings; odontoblasts and dentin matrix were not significantly labeled. Labeled free nerve endings were closely apposed to odontoblasts in dentin but did not form distinctive junctions with them. Nerve endings were most numerous in the regular tubular dentin of the crown adjacent to the tip of the pulp horn, occurring in at least half of the dentinal tubules there. Reparative dentin was poorly innervated, even near the tip of the crown, and it had a different tubular structure and adjacent pulpal structure from the innervated dentin. Radicular dentin was not innervated in most areas but did contain a few labeled axons where the predentin was wide and the odontoblasts were columnar, as at the buccal and lingual poles of some roots. Our results show tha dentinal sensory nerve endings in primate teeth can be profuse, sparse, or absent depending on the location and structure of dentin and its adjacent pulp. When dentin was innervated, the tubules were straight and contained odontoblast processes, the predentin was wide, the odontoblast cell bodies were relatively columnar, and there was an adjacent cell-free zone and pulpal nerve plexus.

Animals↗

PubMed2007

Nanoleakage and microshear bond strength in deproteinized human dentin.

This study evaluated the influence of dentin deproteinization with NaOCl on the microshear bond strength (microSBS) and the nanoleakage patterns of three dentin bonding systems (DBS). Occlusal dentin surfaces, obtained from extracted noncarious human molars, were divided into two experimental groups, according to dentin surface treatment: Group I-37% H(3)PO(4)/15s and Group II-37% H(3)PO(4)/15s + 10% NaOCl/1 min. The dentin surfaces were bonded with one of the following DBS: Scotchbond Multipurpose-SBMP, Prime & Bond NT-PB and Clearfil SE Bond-SE. After 1 week storage in water at 37 degrees C, the specimens were subjected to the microSBS test. The data were analyzed by two-way ANOVA and Student-Newman-Keuls' test (p = 0.05). The nanoleakage was evaluated using scanning electron microscopy (SEM) in backscattered electron imaging regime. No significant difference in microSBS between dentin treatments was found for SBMP. For PB, microSBS increased after NaOCl dentin treatment. SE showed a reduction in microSBS in deproteinized specimens. SEM analysis showed different nanoleakage patterns for each DBS. Irrespective of dentin treatments, all SBMP specimens showed nanoleakage. SE did not show nanoleakage with the two dentin treatments. PB showed nanoleakage within the hybrid layer only in acid-etched specimens. The influence of dentin deproteinization was dependent on the dentin bonding system formulation.

Acid Etching, Dental↗

PubMed1977

Microscopy of the junctional region between human coronal primary and secondary dentine.

The juction between human primary dentine and regular and irregular secondary dentine was examined with a number of different light and electron microscopic techniques. In decalcified material, a narrow band along the innermost surface of the primary dentine stained intensely. The walls of the tubules within the band stained intensely, whereas the tubular walls within the bulk of the primary dentine were not stained. Generally, the walls of the tubules in both types of secondary dentine were also preferentially stained. Although not readily apparent in ground sections, observations of thin sections revealed a dramatic reduction in the number of tubules in regular secondary dentine. Generally, the radiodensity of the intertubular matrix was the same in primary and secondary dentine and the intensely stained band was not seen radiographically. The pulpal ends of the tubules in primary dentine were often occluded with a material having the same radiodensity as peritubular matrix. Both patent and occluded tubules were seen in irregular secondary dentine. Scanning electron microscopy of acid-etched specimens of secondary dentine revealed that some tubules had irregular walls of highly mineralized matrix which was less acid-soluble then the peritubular matrix of primary dentine.

Cuspid↗

PubMed1993

Effect of delayed light curing of a resin composite on marginal integrity in cylindrical dentine cavities.

The effect of delayed light curing of resin composite on marginal adaptation has been examined by measuring the wall-to-wall polymerization contraction gap when using a commercial resin composite together with experimental dentine bonding systems to restore cylindrical preparations in dentine. Morphological changes in dentine during dentine bonding procedures were observed using a scanning electron microscope. In a previous report, the contraction gap width for a resin composite increased when irradiation of the resin system was delayed, despite the use of a dentine bonding system considered to be 'contraction' gap free. Such deterioration in marginal adaptation was minimized by use of an experimental dentine primer, 40% erythritol methacrylate aqueous solution (EM), followed by the use of a commercial dual- or autocured dentine bonding agent. Under scanning electron microscopy, the dentine surface microstructure became unclear after EM priming, and a polymer film was detected after polymerization of the dual-cured dentine bonding agent. The hydrogelled primer and the formation of a polymer network on the dentine surface may prevent the flow of fluid from the pulp through the dentine tubules, and maintain marginal integrity if there is delay in light curing of light-activated resin composite systems.

Analysis of Variance↗

PubMed2001

A survey of the use of dentin-bonding systems in Denmark.

OBJECTIVES: Dentin-bonding systems, which usually involve multistep procedures, are relatively new in dentistry. This study was conducted to survey dental practitioners in Denmark concerning their use of dentin-bonding systems. METHODS: A questionnaire regarding dentin-bonding systems was distributed to dentists at an annual dental conference, and 462 dentists were included in the survey. RESULTS: Dentin-bonding systems were used by 99% of the dentists. Twenty-one different dentin-bonding systems were being used, with six of the systems being used by 78% of the dentists. Of the 456 dentists who used a dentin-bonding system, 77% recalled a clinical procedure for their dentin-bonding system that was in accordance with the written instructions of the manufacturer. The degree to which the dentists complied with the instructions for use, was influenced by the number of operating steps involved for a given dentin-bonding system, by the frequency with which the dentin-bonding system was used, and by the degree to which the dentist was satisfied with the instructions for use provided by the manufacturer. The frequency with which dentin-bonding systems were used, was influenced by year of graduation, place of work, and gender of the dentist. SIGNIFICANCE: Further studies, which focus on the adherence of dental practitioners to instruction manuals are warranted as are investigations of the potential clinical consequences of incorrect use of dentin-bonding systems.

Attitude of Health Personnel↗