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PubMed2006

SEM-morphology in dentinogenesis imperfecta type II: microscopic anatomy and efficacy of a dentine bonding system.

AIM: Dentinogenesis Imperfecta is a hereditary defect consisting of opalescent teeth composed of irregularly formed and undermineralised dentin that obliterates the coronal and root pulpal chambers. The aim of this study was to examine the morphology of permanent human enamel, dentine and the dentine-enamel junction, in individuals affected by Dentinogenesis Imperfecta type II in undercalcified sections using scanning electron microscope (SEM) to compare the findings to the normal morphology, and to study the efficacy of modern bonding system to dentine and enamel DI type II affected. MATERIALS AND METHODS: Four third molars extracted from two 19 year-old subjects (one patient affected by Dentinogenesis Imperfecta type II) were included in resin, two divided in slices with a air-cooled diamond disc, and two used to study the characterisation of the resin-dentin interface. The sections of the teeth were examined by means of SEM. The slices were finished up with abrasive paper (400, 600, 1000, and 2000), the half surfaces obtained were etched with 37% phosphoric acid and then joined up to the stubs for SEM analysis. SEM Stereoscan 440 Leica with magnifications of 20X, 100X, 250X, 1000X, 2000X, 3000X was used. As control group were used four third molars with normal anatomy. RESULTS: This study shows that the permanent enamel from patients with DI exhibits few structural changes. No relationships were found between enamel morphology and the DI type II. Enamel appeared to be regularly mineralised. The major findings were anomalies in the dentine-enamel junction, locally a lower degree of mineralisation and an undulating morphology. The dentine showed absence of tubules. CONCLUSION: This study confirms that the problem with teeth affected by DI type II is the defect in dentine and weakness in the way the enamel is attached to the dentine. The adhesive system tested is not able to create a real hybrid layer in dentine DI type II affected and seems to be less effective than on normal substrates.

Adolescent↗

PubMed2007

Chemical profile of adhesive/caries-affected dentin interfaces using Raman microspectroscopy.

In clinical practice, dentists must frequently bond adhesives to caries-affected dentin substrates, but the bond that characteristically forms with these substrates does not provide the durability necessary for long-term clinical function. The purpose of this study was to characterize and compare the interfacial chemistry of adhesive with caries-affected and noncarious dentin using micro-Raman spectroscopy. The results indicated that the differences in the Raman spectra between noncarious and caries-affected dentin could not be accounted for by simple decreased mineralization. Both the structure of collagen and mineral in the caries-affected dentin has been altered by the caries process. The differences in structure and composition not only interfered with acid-etching process but also subsequent resin monomer penetration. It was shown that the interface between the adhesive and caries-affected dentin was wider and more complicated than that of the adhesive and noncarious dentin. As a result of adhesive phase separation, a structurally integrated hybrid layer did not form at the interface with either caries-affected or noncarious dentin. Using chemical imaging techniques, this study provides the direct evidence of adhesive phase separation at the interface with caries-affected dentin. Although our group previously reported adhesive phase separation at the interface with noncarious dentin, the chemistry of caries-affected dentin leads to greater variability and a more highly irregular composition along the length and breadth of the interface.

Adult↗

PubMed1990

Correlation among dentin depth, permeability, and bond strength of adhesive resins.

Correlations among dentin permeability, dentin depth, and dentin bonding of Scotchbond, Clearfil New Bond, and Superbond C&B were studied in bovine incisor crown segments. Since the dentin surface was prepared on deeper dentin, the permeability of the dentin increased both in the presence of, and especially after removal of, the smear layer. In general, the deeper the dentin, the lower the bond strengths of Scotchbond, Clearfil New Bond, and Superbond C&B. The higher the dentin permeability, the lower the bond strength of Superbond C&B, but there was no simple relationship in the case of either Scotchbond or Clearfil New Bond. The bond strength of Superbond C&B was much higher than those of Scotchbond or Clearfil New Bond at any depth of dentin. Superbond C&B should be considered as both an enamel- and dentin-bonding agent.

Composite Resins↗

PubMed1991

Shear bond strength to dentin by simulation of three-dimensional Class V cavity configuration.

The purpose of this study was to investigate the effect of composite polymerization contraction on early shear bond strength of conventional and new dentin adhesives to dentin. The dentin adhesives selected for this study, i.e., Bondlite, Gluma, Prisma Universalbond, Scotchbond LC, Scotchbond 2, and XR Bonding, were tested in combination with Silux and in combination with their respective composites. The composite was applied to the treated dentin surface in cylindrical brass moulds of 4 mm diameter and 3 mm length. The configuration of cylindrical butt-joint Class V cavities was simulated by the coating of the insides of the brass moulds with silane in order that a chemical bond to the composite could be established. The results showed that shear bond strength to dentin was higher for XR Bonding and Scotchbond 2 compared with conventional phosphate ester-based dentin adhesives and Gluma. When XR Bonding or Scotchbond 2 was used, the obstruction of polymerization contraction had no effect on the bond strength to dentin. In contrast, the dentin adhesion of Scotchbond LC/Silux, Prisma Universalbond/Prisma Microfine, Bondlite/Herculite, and Gluma/Lumifor was adversely affected by the reduction of the unbonded composite surfaces. However, this effect was not observed when Prisma Universalbond, Bondlite, and Gluma were tested in combination with Silux. It can therefore be concluded that the effect of polymerization contraction on the bond strength to dentin depends not only on the dentin adhesive but also on the type of composite used.

Adhesives↗

PubMed1995

Demonstration of a focused ion-beam cross-sectioning technique for ultrastructural examination of resin-dentin interfaces.

OBJECTIVES: focused ion-beam (FIB) etching, commonly used as a cross-sectioning technique for failure analysis of semiconductor devices, has recently been applied to biological tissues to expose their ultrastructure for examination. It was the aim of this investigation to determine the practical utility of FIB to cross-section resin-dentin interfaces in order to morphologically evaluate the completeness of resin penetration into the exposed collagen scaffold at the resin-dentin bond interface. METHODS: Two representative commercially available dentin adhesive systems were bonded to mid-coronal dentin. After appropriate fixation and dehydration of the resin-bonded dentin samples, a scanned focused ion-beam of a few tens of nano-meters in diameter was used to cross=section the resin-dentin interface. Examination of the interfacial ultrastructure was accomplished using a field-emission SEM. RESULTS: Results indicate possible artifact production at the cross-sectioned interface, hiding its actual ultrastructure, probably due to a heat-effect with possible recrystallization. Further studies of FIB are needed to optimize its usefulness for resin-dentin interface examinations and other biological tissue applications. SIGNIFICANCE: Complete resin saturation of the demineralized dentin surface-layer has been claimed to be the key factor for a long-lasting resin-dentin bond. A "clean" artifact-free micro-cross-sectioning technique may provide indisputable ultra-structural information about the depth of resin penetration into the demineralized zone. Such a test would be useful in the development of dentin adhesive systems.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1996

Regional bond strengths of resins to human root dentine.

OBJECTIVES: The demand for restoration of root dentine defects such as cervical erosion and root caries has significantly increased recently, but there is limited information on the performance of the adhesive resins to radicular dentine. The purpose of this study was to measure the regional tensile bond strength (TBS) of composite bonded to human root and coronal dentine, and to observe the interface between resin and root dentine by SEM. METHODS: Human extracted cuspid teeth were used to measure TBS with a new microtensile bond test. Enamel and cementum were removed from the labial tooth surfaces to form a long cavity preparation into dentine from the mid-crown to the apex of the root within the same tooth. All Bond 2 (all etch technique) or Imperva Bond (no etch) was bonded to dentine surfaces and covered with Protect Liner resin composite. The resin-bonded teeth were serially sliced into 16 sections at right angles to the long axis of the tooth, and the bonded surfaces were trimmed to give a bonded surface area of 1 mm2 for TBS testing. RESULTS: All Bond 2 bond strengths to coronal and apical dentine showed high values (23.5 MPa) but the bond strength was significantly lower on cervical root dentine. Imperva Bond produced a relatively high tensile bond strength to all regional areas. SEM showed that the thickness of the resin-infiltrated layer formed by All Bond 2 in root dentine was less than coronal areas. Resin infiltration with Imperva Bond was always less than 0.5 micron. The results suggest that high TBS values can be obtained with minimal resin infiltration in root dentine.

Acid Etching, Dental↗

PubMed1992

Effects of CO2 laser energy on dentin permeability.

The effect of a CO2 laser on the structure and permeability of smear layer-covered human dentin was evaluated in vitro. Three different energy levels were used (11, 113, and 566 J/cm2). The lowest exposure to the laser energy increased dentin permeability, measured as a hydraulic conductance, due to partial measured as a hydraulic conductance, due to partial loss of the superficial smear layer and smear plugs. The intermediate energy level also increased dentin permeability by crater formation, making the dentin thinner. The lack of uniform glazing of the surface of the crater, leaving its surface porous and in communication with the underlying dentinal tubules also contributed to the increase in dentin permeability seen with the intermediate laser energy. The highest laser energy produced complete glazing of the crater surfaces and sealed the dentinal tubules beneath the crater. However, it also completely removed the smear layer in a halo zone about 100-microns wide around each crater which increased the permeability of the pericrater dentin at the same time it decreased the permeability of the dentin within the crater. The combined use of scanning electron microscopy and permeability measurements provides important complementary information that is essential in evaluating the effects of lasers on dentin.

Adolescent↗

PubMed2001

Effect of remaining dentin thickness and the use of conditioner on micro-tensile bond strength of a glass-ionomer adhesive.

OBJECTIVES: The purpose of this study is to investigate the effect of remaining dentin thickness and the use of a 20% polyalkenoic acid conditioner on the micro-tensile bond strength of a glass-ionomer adhesive to dentin. METHODS: Resin composite was bonded to flat dentin surfaces from 14 extracted human teeth using Fuji BOND LC (GC) with or without a polyalkenoic acid conditioner, then sectioned to thin slabs, trimmed into an hourglass shape with the area of the interface being approximately 1mm(2), and subjected to micro-tensile testing at a cross-head speed of 1mm/min. Micro-tensile bond strengths were determined at three depth levels with a remaining dentin thickness of more than 3mm, between 2 and 3mm, and less than 2mm. Failure modes of the broken interfaces were determined using field-emission scanning electron microscopy. RESULTS: The micro-tensile bond strength to dentin significantly improved when the remaining dentin thickness increased and the conditioner was used. When the conditioner was used (irrespective of remaining dentin thickness), failures mainly occurred adhesively at the interface between the adhesive and resin composite. When no conditioner was used, no adhesive failures between the adhesive and resin composite occurred, but failures occurred mainly adhesively between dentin and the adhesive, or mixed adhesive-cohesively. SIGNIFICANCE: The bonding effectiveness of the glass-ionomer adhesive tested was affected by the area of intertubular dentin available for micro-mechanical retention through hybrid-layer formation. Removal of the smear layer improved the bond strength of the adhesive to dentin.

Acid Etching, Dental↗

PubMed2001

Transdentinal stimulation of reactionary dentinogenesis in ferrets by dentine matrix components.

OBJECTIVES: Trans-dentinal stimulation of reactionary dentinogenesis may be mediated through cellular signalling by bio-active components released from the dentine matrix during injury. Understanding of these processes will be important to guide dentinal repair activity following restorative surgery. The purpose of this study was to investigate the effects of implanting isolated dentine matrix proteins within cavity preparations on dentinal repair activity and odontoblast survival using a controlled experimental animal model. METHODS: Forty-five ferret canine teeth each had a standardised non-exposed cylindrical Class V cavity cut into the buccal dentine. Ten cavities were restored with zinc oxide eugenol, as a control. Two different lyophilised preparations of dentine matrix components were implanted on the axial floor of the remaining 35 cavities prior to filling with zinc oxide eugenol. After post-operative periods of 2, 7, 14, 28, and 90 days, the teeth were extracted and examined histomorphometrically and the data analysed statistically by analysis of variance tests. RESULTS: The odontoblasts beneath the restored cavities responded to the presence of the two dentine matrix preparations by increasing the mean area of reactionary dentine secreted by 433 and 578%, and the numbers of odontoblasts remained stable. CONCLUSION: Dentine matrix components can stimulate reactionary dentinogenesis in non-exposed cavity preparations. It will now be important to identify how this may be harnessed as a part of routine restorative surgery to optimise treatment outcomes with a biological basis.

Analysis of Variance↗

PubMed1997

Storage effect on dentine structure and on resultant composite bond strengths.

This study evaluates the effects of a food simulating solution (75 vol% ethanol/water) and an artificial saliva (Moi-Stir) on dentine structure and chemistry, using scanning electron microscopic examination and Fourier transform infra-red (FTIR) microscopic characterization. The effect on the bonding of composites to the conditioned dentine were evaluated by shear bond strength (SBS) tests. Three adhesive/composite systems were examined: Tenure/Marathon One, Scotchbond Multi-Purpose/Z100, and Optibond/Herculite XRV. Control specimens were stored in either distilled water or tested without storage. Dentine surface exposure to ethanol resulted in partial loss of the smear layer and of plugs, as well as possible perturbation of collagen. Dentine surfaces exposed to artificial saliva or to distilled water had no evidence of any change from normal appearance of the smear layer. The measured FTIR spectra for most specimens conditioned in these two liquids appeared to be similar to those obtained from fresh dentine. SBS data were analysed using ANOVA and the Tukey LSD test. The SBS value for the non-preconditioned control (23.0 +/- 3.7 MPa) or for the dentine preconditioned in distilled water (22.9 +/- 4.2 MPa) was significantly higher (P < 0.05) than that for dentine pre-conditioned in ethanol (20.0 +/- 3.5 MPa). The SBS (13.3 +/- 3.4 MPa) of all bonding systems was reduced by 40-50% (P < 0.001) when artificial saliva pre-conditioned dentine was used. The failure mode at the dentine-bonding agent interface for the artificial saliva group was adhesive in nature. This is in contrast to the complex cohesive fracture mode found in the control groups and in most ethanol conditioned groups. Dentine structure and chemistry, shear bond strength, and the subsequent debonded mode can be significantly affected by exposure to oral environment prior to conditioning.

Adhesiveness↗

PubMed2004

Comparative study of dentine permeability after apicectomy and surface treatment with 9.6 microm TEA CO2 and Er:YAG laser irradiation.

Failure of apicectomies is generally attributed to dentine surface permeability as well as to the lack of an adequate marginal sealing of the retrofilling material, which allows the percolation of microorganisms and their products from the root canal system to the periodontal region, thus compromising periapical healing. The purpose of this study was to evaluate dentine and the marginal permeability after apicectomy and surface treatment with 9.6 micro m TEA CO(2) or Er:YAG 2.94 micro m laser irradiation. Sixty-five single rooted human endodontically treated teeth were divided into five experimental groups: group I (control), apicectomy with high speed bur; group II, similar procedure to that of group I, followed by dentinal surface treatment with 9.6 micro m CO(2) laser; group III, similar procedure to group I followed by dentinal surface treatment with Er:YAG laser 2.94 micro m; group IV, apicectomy and surface treatment with CO(2) 9.6 micro m laser; and group V, apicectomy and surface treatment with Er:YAG laser 2.94 micro m. The analysis of methylene blue dye infiltration through the dentinal surface and the retrofilling material demonstrated that the samples from the groups that were irradiated with the lasers showed significantly lower infiltration indexes than the ones from the control group. These results were compatible with the structural morphological changes evidenced through SEM analysis. Samples from groups II and IV (9.6 micro m CO(2)) showed clean smooth surfaces, fusion, and recrystallized dentine distributed homogeneously throughout the irradiated area sealing the dentinal tubules. Samples from groups III and V (Er:YAG 2.94 micro m) also presented clean surfaces, without smear layer, but roughly compatible to the ablationed dentine and without evidence of dentinal tubules. Through the conditions of this study, the Er:YAG 2.94 micro m and the 9.6 micro m CO(2) laser used for root canal resection and dentine surface treatment showed a reduction of permeability to methylene blue dye.

Apicoectomy↗

PubMed2001

Permeability characteristics of bovine and human dentin under different pretreatment conditions.

In order to use bovine dentin instead of human dentin for in vitro adhesion and cytotoxicity tests the permeability characteristics of human and bovine dentin should be similar. In the present study hydraulic conductance (Lp) and diffusional water flux (J5) of human and bovine dentin slices were compared. The permeability experiments were performed in a split chamber using tritiated water in physiological saline. Lp and Js of bovine dentin were 0.7- to 2.4-fold and 1.1- to 3.5-fold that of human dentin (not statistically significant). For human and bovine dentin Lp and Js increased with etching and showed an inverse linear relationship (r > or = 0.7) with dentin thickness. The variability of bovine data was low (perfusion = 30%, diffusion = 22%) and about half that of the human data. In conclusion bovine dentin near the cementoenamel junction seems to be a suitable alternative for coronal human dentin for in vitro tests with respect to transdentinal permeability characteristics.

Acid Etching, Dental↗

PubMed2004

Effect of acid etching time and technique on interfacial characteristics of the adhesive-dentin bond using differential staining.

Dentin bonding using the total-etch method has been claimed to be technique-sensitive. The aim of this study is to examine the effect of acid-etch variations on the dentin demineralization and interfacial structure of the adhesive-dentin bond using a differential staining technique. Single Bond adhesive with 35% phosphoric acid gel was used. The occlusal one-third of the crown was removed from 60 extracted, unerupted human third molars. Smear layers were created by abrading the dentin with 600 grit SiC under water for 30 s. The prepared teeth were randomly assigned to four groups according to etching time (Group 1, 10 s; Group 2, 15 s; Group 3, 30 s; Group 4, 60 s). In each group, the etching gel was: (i) applied and spread to the dentin surface and left to stand undisturbed; (ii) applied and gently agitated during etching; (iii) applied without using dispensing tips for the syringe and left for the same period as above. After rinsing, the etched dentin was then treated with the adhesive per manufacturers' instructions. 3-5 micro m thin sections of the adhesive/dentin (a/d) interface were cut with a microtome and stained with Goldner's trichrome. Stained, thin sections from each prepared tooth were imaged with light microscopy. The depth and extent of dentin demineralization, and the a/d interdiffusion zone were clearly visible by this differential staining microtechnique. The thickness of the interdiffusion zone increased as a function of etching time. However, the etchant gel application methods have a significant influence on dentin demineralization. Although agitating acid gel facilitates the penetration and etching into dentin, it should not be recommended, especially for longer etching time. These results indicated that the etching technique has a large effect on the profile of both dentin demineralization and interfacial structure.

Acid Etching, Dental↗

PubMed2005

Effect of endodontic irrigation on bonding of resin cement to radicular dentin.

The influence of endodontic irrigation on shear bond strengths of resin cement to radicular dentin was investigated. Human radicular dentin blocks were divided into four groups and subjected to one of four endodontic irrigations: ethylenediaminetetraacetic acid (EDTA) group, 17% EDTA for 60 s; EDTA/sodium hypochlorite (NaOCl) group, 17% EDTA for 60 s followed by 10 ml of 5% NaOCl for 15 s; NaOCl group, 10 ml of 5% NaOCl for 15 s; and control group, no treatment. Morphological changes of dentin surface after endodontic irrigation were observed by scanning electron microscopy (SEM). A resin block was bonded to the radicular dentin after irrigation using resin cement with either wet-bonding (Uni-Etch/One-Step; Bisco) or self-etching (Tyrian SPE/One-Step Plus; Bisco) adhesives. Shear bond strengths were measured and the penetration of resin tags into dentinal tubules at resin-dentin interface was observed by SEM. With the wet-bonding system, the shear bond strengths for the EDTA/NaOCl group, in which dentinal tubules openings and uniform resin tag penetration into dentinal tubules were observed, were significantly higher than the EDTA and control groups. With the self-etching system, the shear bond strengths were significantly lower in the EDTA group compared with the NaOCl and control groups. The effects of endodontic irrigation on the bonding of resin cement to radicular dentin depended on the dentin bonding system used.

Acid Etching, Dental↗

PubMed2004

In situ effect of 10% carbamide peroxide on resin-dentin bond strengths: a novel pilot study.

PURPOSE: This pilot study used a novel study design to evaluate the effect of a 10% carbamide peroxide bleaching gel on the bond strength of a resin-based composite system to dentin. MATERIALS AND METHODS: Dentin disks were obtained from human third molars, polished to 600 grit, and mounted on the palatal aspect of a removable orthodontic retainer. Two disks were exposed to a 10% carbamide peroxide bleaching gel for 2 h/d for 21 days, whereas two disks were not treated and served as controls. A retainer was worn by the participant regardless of whether bleaching was used, simulating the action of the saliva/oral fluids on the dentin specimens. After the treatment phase, the dentin disks were retrieved and a resin-based composite system was applied to the specimens following manufacturer's instructions. Composite dentin "sticks" were obtained and tested in microtensile mode. Bond strength values were obtained for treated (n = 20) versus nontreated (n = 26) dentin and were analyzed statistically. RESULTS: Mean bond strengths values (SD) were 29.9 MPa (6.2) and 39.2 MPa (5.8) for treated and nontreated dentin specimens, respectively (p < .001). CONCLUSION: The results of this study suggest that nightguard (home) bleaching with 10% carbamide peroxide for 2 h/d for 21 days significantly affects resin-dentin bond strengths when dentin is exposed to bleaching material. CLINICAL SIGNIFICANCE The findings of this novel pilot study imply that dentin bonding, such as to exposed root surfaces and cervical areas of the teeth, should not be performed immediately after bleaching with 10% carbamide peroxide.

Adult↗

PubMed2006

The effect of silver fluoride and potassium iodide on the bond strength of auto cure glass ionomer cement to dentine.

BACKGROUND: Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been shown to reduce the incidence of caries in primary dentitions. The clinical application of this material has been limited by staining associated with both teeth and restorative materials. The application of potassium iodide (KI) after AgF eliminates stain formation. There is a lack of information as to how the addition of AgF followed by KI may affect the bond strength to dentine. The purpose of this study was to compare the bond strengths of auto cure glass ionomer cement to dentine surfaces that had been treated with AgF and KI and without treatment. METHODS: Ten recently extracted human third molars were embedded into methyl methacrylate resin and sliced to form a square block of exposed dentine surfaces. Each of the four surfaces were treated by one of the following procedures: (a) etching with 37 per cent phosphoric acid; (b) applying GC dentine conditioner; (c) etching, followed by application of AgF/KI then washing off the precipitate and air drying; and (d) etching, applying AgF/KI and air drying the reaction products on the surface. Fuji VII auto cure glass ionomer cement was bonded onto each sample and fracture tested. RESULTS: The dentine samples treated with AgF/KI followed by washing away the precipitate and air drying had bond strengths (2.83 MPa) not significantly different from samples that had been conditioned (2.40 MPa). Samples where the AgF/KI precipitate had been air dried onto the dentine surface had significantly lower bond strengths (1.49 MPa) than the washed samples. Samples that were etched had significantly lower bond strengths (1.91MPa) than the conditioned samples. CONCLUSIONS: This study found that the application of AgF/KI to etched dentine samples followed by washing off the precipitate, created bond strengths that were not significantly different to conditioned samples. Leaving the AgF/KI precipitate on the dentine surface significantly reduced the bond strength of auto cured glass ionomer cement to dentine. Washing away the reaction products and air drying is recommended as the clinical protocol for using AgF and KI on dentine surfaces prior to application of an auto cure glass ionomer cement.

Acid Etching, Dental↗

PubMed1981

The effects of desensitizing agents on the hydraulic conductance of human dentin in vitro.

The hydrodynamic theory of dentin sensitivity states that a stimulus applied at the orifice of exposed dentinal tubules causes movement of tubular fluid which stimulates nerve receptors. The fluid should obey principles of fluid movement through capillary tubes. Any decrease in the functional radius of the dentinal tubules should greatly reduce the rate of fluid flow, thus reducing dentinal sensitivity. The purpose of this study was to evaluate the ability of agents that have been used previously for clinical dentin desensitization to reduce the rate of fluid flow through dentin in vitro. Dentin discs prepared from extracted human third molars were treated with 50% citric acid to remove debris from tubular orifices. After placing the discs in a split chamber device, the rate at which buffer solution could filter across the dentin under 240 cm of water pressure was measured. The occlusal side of the disc was then treated with an agent thought to desensitize dentin to determine if it reduced fluid flow rate. Discs that had more than a 50% reduction in flow rate were examined by scanning electron microscopy to determine if those agents that decreased fluid flow also partially occluded tubular orifices. This in vitro model provided a useful quantitative method for screening a host of preparations that have been used in the past to decrease dentin sensitivity.

Adolescent↗

PubMed2006

[Effectiveness of methacrylamide monomer for dentin bonding].

PURPOSE: In this study, we investigated the conditioning efficacy of a self-etching primer consisting of methacrylamide, N-methacryloyl-omega-amino acid (M omega A) derivatives for enhancing the bond strength of resin to crown and root dentins. METHODS: A series of four M omega A derivatives, with different methylene chain numbers, were synthesized, as follows. 1: N-methacrylole glycine (Gly); 2: N-methacrylole-beta-alanine (beta Ala); 3: N-methacrylole-4-aminobutyric acid (Bu); 4: N-methacrylole-5-aminovaleric acid (Va). The dissociation equilibrium pH (pKa) of carboxylic acid in each of the M omega A derivatives was determined. The shear bond strengths of resin to the crown and root dentins, primed with the Gly solution were measured for various conditioning times. We also measured the bond strength to both the dentins following application of the M omega A adhesives with different pKa values for 30 seconds. RESULTS: For the Gly primer, the bond strength of resin to both dentins increased with the conditioning time until 30 seconds, leveled off thereafter by increase in the methylene chain number. The effects of conditioning time on the bond strength to the crown and the root dentin were the same. Furthermore, the bond strengths to the dentins, conditioned with each of the four M omega A derivatives for 30 seconds, were the same, even though the decalcified amounts of the dentin apatite noted following conditioning with Bu and Va were lower than that noted following conditioning with Gly. This was attributed to the pKa value of the acidic groups in the acidic monomer directly relating to the decalcified amount of dentin apatite. CONCLUSIONS: Application of the M omega A solutions, resulted in an increase in the bond strength of resin to both crown and root dentins. In particular, the Bu and Va primers were very useful as primers promoting the bond of resin to dentin, since the etching potential was very low.

Acrylamides↗