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 649 records · Page 36Linked to original sources

PubMed2003

Possible role of dentin matrix in region-specific deposition of cellular and acellular extrinsic fibre cementum.

The mechanism whereby a region-specific deposition of the two types of cementum (cellular cementum and acellular extrinsic fibre cementum) is regulated on the growing root surface was tested using bisphosphonate-affected teeth of young rats and guinea pigs. The animals were injected subcutaneously with 8 or 10 mg P x kg body weight(-1) x day(-1) of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) for 1 or 2 weeks. In rat molars, HEBP prevented mineralization of newly formed root dentin matrix and totally inhibited de novo deposition of acellular extrinsic fibre cementum. Instead, thick cellular cementum was induced on the non-mineralized root dentin surface, irrespective of the position of the root. In both animals, cellular cementum was also induced on the non-mineralized surface of root analogue dentin in HEBP-affected incisors, where only acellular extrinsic fibre cementum is deposited under normal conditions. In normal rat molars, dentin sialoprotein (DSP) was concentrated along the dentin-cellular cementum border, but not that of dentin and acellular extrinsic fibre cementum. In HEBP-affected rat incisors, DSP was shown to penetrate through the non-mineralized dentin into the surrounding tissues, but not through the mineralized portions. These data suggest that, at the site of cellular cementum formation, putative inducing factors for cellular cementum might diffuse into the periodontal space through the newly deposited mantle dentin matrix before it is mineralized. At earlier stages of root formation, mantle dentin might mineralize more promptly not to allow such diffusion. The timing of mineralization of mantle dentin matrix might be the key determinant of the types of the cementum deposited on the growing root surface.

Animals↗

PubMed2001

Viable bacteria in root dentinal tubules of teeth with apical periodontitis.

Two sets of teeth with apical periodontitis were collected at different geographic locations to study the identity of bacteria left in the root dentinal tubules. Root dentin of 20 of these teeth was cultured from three locations between pulp and cementum (A, B, and C). In addition dentin from eight teeth was examined histologically. Using the culturing technique bacteria were found in 77% of the dentin samples from set 1 (Amsterdam) and in 87.5% of the dentin samples from set 2 (Glasgow). At greater distance, in layer C, from the pulp bacteria were found in 62% (13 of 21) of the dentin samples. Twenty-three percent (3 of 13) of set 1 and 25% (2 of 8) of set 2 contained >50,000 colony-forming units/mg of dentin in layer C. In layers closer to the pulp higher numbers of anaerobic bacteria and gram-positive rods were found, as well as a larger number of bacterial species. Histological sections showed bacterial penetration in dentinal tubules in 5 of 8 teeth. In the other three teeth where the colony-forming units/mg recovered was <10,000, no histological signs of tubule penetration was seen. It seems clear that, in more than half of the infected roots, bacteria are present in the deep dentin close to the cementum and that anaerobic culturing of dentin is more sensitive than histology to detect these bacteria.

Actinomyces↗

PubMed2004

Effect of 2-hydroxyethyl methacrylate pre-treatment on micro-tensile bond strength of resin composite to demineralized dentin.

The purpose of this study was to evaluate the effect of 2-hydroxyethyl methacrylate (HEMA) application on the micro-tensile bond strength of resin composite to demineralized dentin. Artificially demineralized lesions were formed on bovine dentin surfaces and treated with 10, 30, 50, 70 and 100 wt% HEMA aqueous solution. The surfaces were then applied and covered with SE Bond and AP-X according to the manufacturer's instruction. After immersion in 37 degrees C water for 24 h, bond strength were measured using a universal testing machine. Bond strengths to both demineralized dentin and normal dentin, without HEMA application, were also measured. Scanning electron microscopic (SEM) observation and confocal laser scanning microscopy (CLSM) analysis at the resin-dentin interface were also performed. The bond strength data were statistically compared with anova and Scheffe's test (P < 0.05). Bond strength to demineralized dentin treated with over 30 wt% HEMA aqueous solution were significantly higher than that to demineralized dentin without HEMA application, but significantly lower than that to normal dentin. SEM observation revealed that the hybrid layer and resin-tags thickened and lengthened with HEMA application. In CLSM, the diffusion of adhesive primer into demineralized dentin increased with HEMA application. These results indicated that HEMA application might increase the bond strength to demineralized dentin by the enhancement of resin monomer penetration of HEMA.

Animals↗

PubMed2005

The effects of phosphoric acid, sodium hypochlorite, ferric oxalate and Scotchbond Multipurpose on the rate of pressure change across dentine: a laboratory study.

The aim of this study was to investigate the consequences of dentine treatment on dentine permeability of crown preparations treated with phosphoric acid, sodium hypochlorite (NaOCl), and then ferric oxalate (Sensodyne sealant) or bis-phenol-A-diglycidyldimethacrylate (BIS-GMA) and hydroxyethylmethacrylate (HEMA) resin combination (Scotchbond Multipurpose). Thirty human premolars received full crown preparations (stage A), were then acid etched (stage B) and subsequently the pulp chamber flushed with NaOCl (stage C). They were then randomly assigned to two groups: group 1 was treated with Scotchbond Multipurpose and group 2 with 6% ferric oxalate (Sensodyne sealant) (stage D). Both groups were acid etched a second time (stage E) as the final step in the sequence. The rise in pressure in the pulp chamber because of the transmission of saline from the pressure chamber through cut dentine was recorded by a pressure transducer after each of the stages described (A to E). The mean rate of pressure change across dentine (Pa s(-1)) for each measurement point (A to E) (n = 30) were A = 2.3; B = 9.8; C = 16; D = 2.1; E = 3.1. Acid etching and NaOCl were both effective in producing significant increases in the rate of pressure change across dentine (P < 0.05). Sensodyne sealant and Scotchbond Multipurpose are both effective dentine sealants and there is no significant difference (P > 0.05) in their abilities in sealing dentine. Acid etching-sealed dentine produced a significant increase in the rate of pressure change across dentine (P < 0.05). The sealing of dentine appears to be a sensible consideration following crown preparations on vital teeth.

Acid Etching, Dental↗

PubMed2005

Fibrin clot adhesion to dentin conditioned with protein constructs: an in vitro proof-of-principle study.

OBJECTIVES: Periodontal regeneration is contingent on the adsorption, uninterrupted adhesion, and maturation of a fibrin clot to a periodontally compromised root surface. Clot adhesion appears vitally dependent on the formation of a resilient union between the clot and the root surface. Root surface demineralization will remove a root surface smear layer exposing dentin tubules and collagen matrix for enhanced clot adhesion. Recently, protein constructs have been introduced to condition the root during periodontal surgery. The effect of such root conditioning on clot adhesion has not been clarified. The objective of this study was to evaluate clot adhesion to protein conditioned dentin surfaces. METHODS: Human dentin blocks (4 x 6 x 1 mm) were exposed to a saturated citric acid solution (CA) or a commercial ethylenediaminetetraacetic acid (EDTA) preparation using standardized protocols. Some dentin blocks were additionally conditioned with proteins, either bovine serum albumin (BSA) or an enamel matrix protein preparation (EMP). Fresh human whole blood was applied to the blocks. The blood was allowed to clot for 20 min. in a humidified chamber. The dentin blocks were rinsed 3 x 5 min. in phosphate-buffered saline under standardized conditions to test clot adhesion. They were then processed for scanning electron microscopy (SEM). Two masked examiners independently evaluated the SEM images. RESULTS: CA removed the dentin smear layer, exposing dentin tubules and collagen. EDTA appeared less efficacious leaving smear layer residues. The BSA or EMP application resulted in a surface morphology similar to that of a smear layer. Fibrin clot adhesion was best supported by the CA-treated dentin surface. Forces produced by the rinse protocol partially removed the fibrin clot from EDTA-treated surfaces. BSA- or EMP-treated surfaces poorly retained the fibrin clot. CONCLUSIONS: CA surface demineralization removes a dentin surface smear layer to promote adhesion of a fibrin clot. The EDTA gel appears less effective. Further conditioning of the dentin surface with protein constructs produces a surface morphology similar to that of the smear layer with poor fibrin clot retention.

Animals↗

PubMed1994

Closing of dentinal tubules by glutardialdehyde treatment, a scanning electron microscopy study.

The properties of dentin are strongly influenced by the so-called smear layer. This layer is always present on the dentin surface after cutting, drilling, sawing, etc. The smear layer can be removed by various chemical treatments, such as those of acid etching or ethylenediaminetetraacetic acid (EDTA). These treatments remove the smear layer and open the tubules. In this paper, the effect on the smear layer of human dentin of treatment with a 2% glutardialdehyde (GDA) solution at pH 3.5 for 2 min and a 0.5-M EDTA solution at pH 7.4 for 4 min was investigated by scanning electron microscope (SEM). The dentin samples were dried by air or critical-point drying before SEM photography was employed. The number of open dentin tubules was quantified on micrographs of EDTA- and GDA+EDTA-treated dentin. The results show that the GDA treatment fixed part of the smear layer and the superficial dentin surface in such a way that at least 50% of the tubules remained closed after EDTA treatment. By closing the dentinal tubules, the GDA-fixed layer might have a positive effect on dentin hypersensitivity, root caries, and bonding of composite to dentin.

Adolescent↗

PubMed1995

The effects of a sodium hypochlorite treatment on demineralized root dentin.

The effects of a 10% NaOCl treatment for 2 min on demineralized human root dentin were investigated by means of: microradiography (MR), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and secondary ion mass spectroscopy (SIMS). MR measurements revealed that NaOCl caused a tissue contraction not related to water loss but to removal of organic substance(s), resulting in reductions of the lesion depth and mineral loss values by 15% and 42%, respectively. CLSM observations on wet dentin showed that the dentinal tubules underneath the surface are clearly observable and not deformed substantially by the NaOCl, except near the outermost surface. This indicates the importance of wet as well as of dried (high vacuum) observations. SEM micrographs (high vacuum) showed definite changes in the outer dentin surface structure; 85% of the originally open dentinal tubules were closed after NaOCl treatment. No marked changes were observed in the dentin ultrastructure inside lesions, as shown by SEM on fractured surfaces. SIMS data, pertaining to samples in high vacuum, showed a remarkable increase of chlorine (Cl) content in the entire lesion due to the NaOCl, indicating deep penetration of the original OC1 ions. The results suggest that the 2-min treatment of demineralized dentin by NaOCl solutions removes and/or changes part of the dentin matrix in nearly the whole lesion. As a consequence the mineral is somewhat redistributed, the outermost surface of a few mu m is changed, but the main dentin structure and element composition are still intact. These findings indicate that NaOCl treatments are of interest in remineralization and hyper-remineralization studies of dentin.

Adolescent↗

PubMed2006

Dentin resorption and cementum-like tissue formation by bone morphogenetic protein application.

BACKGROUND AND OBJECTIVE: Recent studies have shown that bone morphogenetic protein-2 (BMP-2) stimulates mineralization and osteoclast differentiation. Osteoclastic resorption by BMP-2 application may play an important role in the regulation of new cementum-like tissue formation on the dentin surfaces. Therefore, this study aimed to examine the effect of BMP-2 application on dentin resorption and cementum-like tissue formation at the dentin surfaces. MATERIAL AND METHODS: Seventy-two flat dentin blocks were prepared from rat roots and treated with 24% EDTA. Each block was assigned to group 0, group 100, or group 400, and immersed correspondingly in 0, 100, or 400 microg/ml BMP-2. The dentin blocks were then implanted into palatal connective tissue of rats, and specimens were prepared 2, 4 and 8 wk after surgery for histologic and histomorphometric analyses. RESULTS: BMP-2 caused a dose-dependent increase in dentin resorption by osteoclastic cells. New cementum-like tissue was randomly formed on parts of the nonresorbed and resorbed dentin surfaces in groups 100 and 400. Dentin resorption in groups 100 and 400 was significantly greater than group 0 (p < 0.01). However, at 8 wk, new cementum-like tissue formed in 41.8% of group 100, as compared with 16.2% of group 400 (p < 0.05). CONCLUSION: Dentin resorption was stimulated by a high dose of BMP-2, and cementum-like tissue was induced by a low dose of BMP-2, effectively suggesting that BMP-2 application, at an appropriate dose, to a dentin surface may enhance periodontal regeneration.

Animals↗

PubMed2004

Stress-strain response in human dentine: rethinking fracture predilection in postcore restored teeth.

In this study, the biomechanical perspective of fracture predilection in post-core restored teeth is investigated using computational, experimental, and fractographic analyses. The computational finite element analysis and the experimental tensile testing are used to evaluate the stress-strain response in structural dentine. The fractographic evaluations are conducted using laser scanning confocal microscopy and scanning electron microscopy to examine the topography of dentine from experimentally fractured specimens, and clinically fractured post-core restored teeth specimens. These experiments aided in correlating the stress-strain response in structural dentine with cracks and catastrophic fractures in post-core restored teeth. It was observed from these experiments that the inner dentine displayed distinctly high strains (deformations), while the outer dentine demonstrated high stresses during tensile loading. This implies that the energy fed into the material as it is extended will be spread throughout the inner dentine, and there is less possibility of local increase in stress at the outer dentine, which can lead to the failure of dentine structure. During post-endodontic restoration with increase in loss of inner dentine, the fracture resistance factor contributed by the inner dentine is compromised, and this in turn predisposes the tooth to catastrophic fracture.

Adult↗

PubMedDate not supplied

Shear bond strength to dentin and Ni-Cr-Be alloy with the All-Bond universal adhesive system.

The shear bond strength of the All-Bond system to dentin and a nonprecious alloy was evaluated. Eighty human molar teeth (10 per group) were used in the dentin bonding phase of the study. A bond site was prepared in dentin, and both the succinic anhydride modified HEMA and 10 percent phosphoric acid dentin conditioning techniques were evaluated under both wet and dry conditions. Eighty Rexillium III specimens were used in the metal bonding phase of the study. All-Bond primer and opaquer were applied to the metal surface, followed by a visible light-cured composite restorative material. Dentin bond strengths were determined at 24 hours, while metal bond strengths were evaluated both at 24 hours and after thermocycling (2,500 cycles). Separate groups were established for adhesion to both dentin and metal with the composite placed in a plastic matrix or a gelatin capsule. The highest mean shear bond values to dentin were obtained in the groups with the gelatin capsule bonding procedure, where the dentin was treated with 10 percent phosphoric acid and then blotted dry (wet technique) before the bonding procedure (39.99 MPa). These values were higher than the succinic anhydride modified HEMA-treated group with gentle air drying (wet technique-29.56 MPa). There was essentially no difference in mean shear bond strengths to dentin when a succinic anhydride modified HEMA dentin conditioner was used with aggressive (dry technique) or gentle air drying (wet technique) [29.56 versus 29.08 MPa]. High bond strengths to Rexillium III were obtained when the All-Bond adhesive system was used in combination with a dual-care opaquer and a composite restorative material.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗

PubMed2005

Immediate dentin sealing: a fundamental procedure for indirect bonded restorations.

UNLABELLED: The purpose of this article is to review evidence-based principles that could help optimize dentin bonding for indirect composite and porcelain restorations. More than 30 articles were reviewed, most of them addressing the specific situation of dentin bonding for indirect restorations. It appears that the combined results of this data plus clinical experience suggest the need for a revision in the dentin bonding procedure. Immediate application and polymerization of the dentin bonding agent to the freshly cut dentin, prior to impression taking, is recommended. This new application procedure, the so-called immediate dentin sealing (IDS), appears to achieve improved bond strength, fewer gap formations, decreased bacterial leakage, and reduced dentin sensitivity. The use of filled adhesive resins (low elastic modulus liner) facilitates the clinical and technical aspects of IDS. This rational approach to adhesion also has a positive influence on tooth structure preservation, patient comfort, and long-term survival of indirect bonded restorations. CLINICAL SIGNIFICANCE: Tooth preparation for indirect bonded restorations (eg, composite/ceramic inlays, onlays, and veneers) can generate significant dentin exposures. It is recommended to seal these freshly cut dentin surfaces with a dentin bonding agent (DBA) immediately following tooth preparation, before taking impression. A three-step total-etch DBA with a filled adhesive resin is recommended for this specific purpose. The major advantages, as well as the technical challenges of this procedure, are presented in detail.

Dental Bonding↗

PubMed2004

Effect of home bleaching agents on the roughness and surface morphology of human enamel and dentine.

AIMS: Carbamide peroxide (CP) containing bleaching agents are now widely used in different concentrations. In this study, the effect of 10% and 15% CP containing home bleaching agents on the surface roughness and morphology of human enamel and dentine were evaluated in vitro. METHODS: 90 non-carious human mandibular incisors were divided randomly into two equal groups (enamel and dentine). The dentine group specimens were ground to expose dentine surfaces. The samples in both groups were then randomly divided into three main groups and then divided into three subgroups, according to bleaching application times (n=15). The samples in both enamel and dentine groups were treated with 10% CP at Group 1 and 4, 15% CP at Group 2 and 5 and distilled water at Group 3 and 6. The surface roughness of the samples was analysed before bleaching (1a, 2a, 3a for enamel, 4a, 5a, 6a for dentine), after 4hr (1b, 2b, 3b for enamel, 4b, 5b, 6b for dentine) and after 28hr of bleaching application (1c, 2c, 3c for enamel, 4c, 5c, 6c for dentine) using a computerised roughness tester. The surface morphologies of treated and control specimens were also examined by SEM. RESULTS: There were no statistically significant differences between the surface roughness of untreated control specimens and the specimens treated with the bleaching materials (10% and 15% CP) for both enamel and dentine at any given measurement time (p>0.05). CONCLUSION: Under the careful guidance of a dentist, home bleaching can be thought a reliable treatment for both stained enamel and dentine, regardless of whether 10% or 15% CP is used.

Adult↗

PubMedDate not supplied

The effect of dentine on fluorescence measurements of enamel lesions in vitro.

This study aimed to determine the contribution of the underlying dentine and the enamel-dentine junction to measurements of mineral loss from enamel recorded using quantitative light fluorescence (QLF). Sixteen square blocks (5 x 5 mm) were cut from the labial surfaces of extracted bovine incisor teeth. A dental drill was used to remove dentine and the enamel-dentine junction from half of each specimen. All specimens were embedded in epoxy resin and ground to produce a smooth, flat enamel surface. Half of the enamel surface of the block, perpendicular to where the dentine had been removed, was demineralised for 72 h prior to undertaking QLF measurements from the enamel surface to compare fluorescence loss from different areas of the block. QLF readings taken from lesions with no underlying dentine or enamel-dentine junction were very similar to readings from lesions with underlying dentine. A comparison of the two data sets demonstrated a linear relationship with a gradient of 0.95 and a y intercept of -1.24 (r(2) = 0.936). From these data, the underlying dentine and enamel-dentine junction did not influence mineral loss in enamel measured using QLF.

Animals↗

PubMedDate not supplied

Host-derived proteinases and degradation of dentine collagen in situ.

Dentine root caries is a process of demineralization and degradation of the organic matrix by proteinases. In this in situ study, the presence and activity of the matrix metalloproteinases 1, 2 and 9 (MMP-1, MMP-2, MMP-9) in saliva and in completely demineralized dentine specimens were investigated. Furthermore, the activity of cathepsin B was determined in saliva. A correlation between these enzymes and the level of degraded collagen was investigated. Demineralized dentine specimens were mounted in the partial prosthesis of 17 volunteers. Saliva samples were taken at 0, 2 and 4 weeks. After 4 weeks, the enzymes were extracted from the dentine specimens and the collagen loss was assessed. The collagen loss varied between 0 and 40.3%. Zymography of the saliva and the dentine extract samples showed that (pro-)MMP-2 and (pro-)MMP-9 were present. The levels of active MMPs were assessed, using fluorogenic MMP-specific substrates. All but 3 of the 51 saliva samples showed MMP-1 activity ranging from 1.5 to 101.1 relative fluorescence units (RFU)/s. Forty-eight saliva samples showed gelatinolytic MMP-2/MMP-9 activity (1.7-141.1 RFU/s). MMP-1 activity was shown in all dentine extracts varying between 3.5 and 295.0 RFU/s. From the dentine extracts, 15 showed MMP-2/MMP-9 activity (0.2-13.7 RFU/s). The MMP activity from both saliva and dentine extracts did not correlate with the collagen loss. The activity of salivary cathepsin B varied from 4.8 to 42.2 arbitrary units/min. A positive correlation was found between salivary MMP activity and cathepsin B activity. This study revealed that gelatinolytic enzyme activity was present both in saliva and dentine collagen. No correlation could be observed, however, between the level of enzyme activity and the collagen loss of the dentine specimens.

Aged↗

PubMed1991

Demineralization of human dentine compared with enamel in a pH-cycling apparatus with a constant composition during de- and remineralization periods.

A comparison was made between the demineralization of enamel and dentine with and without abraded surfaces. This was done in a pH-cycling experiment for different demineralization/remineralization ratios--in the range from 1:1 to 1:4--and for different fluoride additions (up to 2 ppm) in solution. A new automatic pH-cycling system, in which the de- and remineralization solutions have a constant composition during the de- and remineralization cycles, was used to create mineral loss in human dentine and enamel. Changes in mineral content were monitored by means of longitudinal microradiography. A linear correlation was found between the amount of mineral lost and the total demineralization time for both dentine and enamel. The demineralization rates were comparable for abraded enamel and dentine and for polished enamel and dentine, and this rate was roughly doubled by the removal of the outer surface for both tissues. This showed that the presence of the outer surface is equally important to dentine and enamel. Under the pH-cycling conditions used, a logarithmic relation was found between the addition of fluoride and the decrease in demineralization for both enamel and dentine. The inhibitory effect of fluoride on demineralization was most pronounced on abraded enamel, followed by pumice-polished enamel, abraded dentine and pumice-polished dentine. About 2 ppm fluoride was needed under the conditions used to stop enamel demineralization completely; in the case of dentine, however, this amount of added fluoride did not inhibit demineralization.

Analysis of Variance↗

PubMed2001

Nanomechanical properties of hydrated carious human dentin.

Most restorative materials are bonded to caries-affected dentin that has altered structure. We tested the hypothesis that hydrated dentin of the transparent zone did not have increased hardness or elastic modulus. Nanoindentation by modified AFM was used to determine site-specific elastic modulus and hardness for components of hydrated dentin from 8 carious and non-carious human teeth. Indentations in intertubular dentin were made at intervals from pulp through the affected layers (subtransparent, transparent, and discolored zones). The values of intertubular dentin increased slightly from near the pulp into the transparent zone, then remained constant or decreased slightly through transparent dentin (E, 18.3 GPa; H, 0.8 GPa; confirming the hypothesis), and decreased markedly through the discolored region. Peritubular dentin values were unaltered in transparent dentin, and intratubular mineral had values between those of normal peritubular and intertubular dentin. Superficial areas contained distorted tubules without peritubular dentin or intratubular mineral.

Analysis of Variance↗

PubMed1991

Effect of 2-(methacryloxy)ethyl phenyl hydrogen phosphate on adhesion to dentin.

A variety of methacrylate-based materials has been developed with the capacity of adhering to dentin. This study investigated the effectiveness of 2-(methacryloxy)ethyl phenyl hydrogenphosphate (phenyl-P) for bonding 5% phenyl-P in methyl methacrylate (MMA) to dentinal surfaces. Polymerization of the phenyl-P/MMA monomer was initiated by partially oxidized tri-n-butyl borane catalyst (TBB). The mean tensile bond strength of 5% phenyl-P in MMA to dentin that was pre-treated with an aqueous solution of 10% citric acid/3% ferric chloride, abbreviated as 10-3, was found to be 10.5 MPa. Scanning electron microscope examination demonstrated the formation of a transitional or "hybrid" layer of resin-reinforced dentin, created by the intermingling and entanglement of polymerized resin with collagen bundles exposed by dentin pre-treatment with 10-3, an effective remover of the dentinal smear layer. This "hybrid" layer or zone was essential for high tensile bond strength to be attained. Phenyl-P was found to be effective in promoting monomer diffusion and impregnating monomer into demineralized dentinal surfaces. The formation of the "hybrid" layer of resin-reinforced dentin followed in situ resin polymerization initiated by partially oxidized tri-n-butyl borane (TBB). Ferric (Fe3+) ions deposited on dentinal surfaces from the 10-3 solution also acted to improve monomer diffusion and entanglement with demineralized dentin, and facilitated the formation of the "hybrid" layer/zone.

Acid Etching, Dental↗

PubMed1995

Mineral distribution and dimensional changes in human dentin during demineralization.

Many bonding agents require the dentin surface to be acid-etched prior to being bonded. Understanding the stability and morphology of the etched dentin surface is important for improving bond strength and reliability in these systems. In this study, the atomic force microscope was used to quantify dimensional changes that occur to fully hydrated dentin during demineralization with a pH 4.0 lactic acid gel. A high-resolution microtomography instrument, the x-ray tomographic microscope, was also used to quantify the mineral density distribution in the dentin as a function of etching time. The intertubular dentin surface shrank by less than 0.5 microns during etching, while the peritubular dentin receded at an initially rapid linear rate. The dentin surface retained its initial morphology, although it was more porous with the removal of the peritubular dentin. Beneath the etched surface, there were three major zones characterized by mineral density differences. The first zone was a fully demineralized collagen layer, subjacent to which was a partially demineralized zone of roughly constant mineral density. Immediately following the partially mineralized layer was normal dentin. The presence of the partially mineralized layer could be explained in terms of different transport rates in the peritubular and intertubular dentin.

Acid Etching, Dental↗