Effect of polyacrylic acid treatment of dentin on adhesion of glass ionomer cement

Poly(benzofuran-co-arylacetic acid) – a new type of highly functionalized polymers

A new type of polymer containing a number of functional groups with orthogonal reactivity, allowing linkage to several functionalities.

Effect of dentine conditioning on adhesion of resin-modified glass ionomer adhesives

BACKGROUND

The aim of this study was to investigate the use of phosphoric acid as a surface treatment compared to traditional conditioning agents to dentine bonded with resin-modified glass ionomer (RMGIC) adhesives.

METHODS

Forty human molars were utilized in microtensile bond strength testing, while another 16 were used for evaluation of the bonded interface with scanning electron microscopy. Three RMGIC adhesives were evaluated: Fuji Bond LC (GC Corp); Riva Bond LC (SDI Ltd); and Ketac N100 (3M-ESPE). Surface treatments were 37% phosphoric acid (5 s) or 25-30% polyacrylic acid (PAA) (10 s), or the manufacturer's method - Fuji Bond LC: Cavity Conditioner (20% PAA + 3% AlCl3 10 s) or Ketac N100 primer: Ketac Nano priming agent (15 s). Teeth were finished with 600-grit SiC paper, surfaces treated and bonded with RMGIC adhesive and stored in distilled water for 24 h then subjected to microtensile bond strength testing.

RESULTS

Two-way analysis of variance (ANOVA) revealed adhesion was affected by the 'type of RMGIC adhesive' and 'method of dentine surface treatment' (p < 0.05). The microtensile bond strength of Ketac N100 primer groups was lower than Fuji Bond LC and Riva Bond LC (p < 0.05).

CONCLUSIONS

For RMGIC adhesives a brief etch with phosphoric acid does not adversely effect short-term bond strengths, but is no better than traditional conditioning with PAA.

Performance of Brazilian and imported glass ionomer cements used in Atraumatic Restorative Treatment (ART) regarding microleakage in primary molars

With the aim of assessing the performance of Brazilian and imported glass ionomer cements (GIC) with regard to microleakage, 40 primary molars received two standard class II cavity preparations with margins in enamel. Twenty cavities were filled with Brazilian materials (Vidrion R and Vidrion R(Caps)) and the other 20 cavities were filled with imported materials (Fuji IX and Fuji IX(GPFast) capsule). All fillings were performed by a single operator according to the manufacturer's instructions. Teeth were immersed in 0.5% methylene blue and half-sectioned. Three independent calibrated examiners assessed microleakage using scores (0-3). Data were submitted to the Kruskal-Wallis statistical test and Wilcoxon analysis. High microleakage indexes were verified for all ionomer cements: 59.5% of the samples restored with Vidrion R or Vidrion R(Caps) and 83.4% of the samples restored with Fuji IX or Fuji IX(GPFast) capsule obtained the maximum score (3). The Brazilian ionomer cements presented less microleakage than imported cements, although this difference was only significant (p=0.003) among the encapsulated materials.

Morphological study of demineralized dentine after caries removal using two different methods

BACKGROUND

Caries-affected dentine is the usual substrate bonded to in everyday clinical practice. The first step for most of the current dentine adhesive systems is etching or conditioning. It is therefore important to understand the effect of etchant/conditioner on caries-affected dentine.

METHODS

Twelve extracted carious permanent molars were examined. Six teeth had caries removed using burs after staining with a caries detector dye, and caries from the other six was removed using Carisolv. After caries removal, three teeth from each group were left untreated. The remaining teeth were sectioned to obtain two normal dentine samples and two caries-affected dentine samples from each tooth. One half of the normal dentine samples and one half of the caries-affected dentine samples were treated with 35 per cent phosphoric acid, and the remaining samples were treated with 20 per cent polyacrylic acid/3 per cent aluminium chloride. The samples were observed using field emission scanning electron microscopy (FE-SEM).

RESULTS

Phosphoric acid treated samples showed more obvious intertubular dentine microporosity and greater depth of demineralization in caries-affected dentine. Polyacrylic acid treated samples showed some residual smear layer. However, the peritubular and intertubular collagen network was easily observed in Carisolv treated dentine. The depth of demineralization was not as distinct as that of the phosphoric treated samples.

CONCLUSIONS

From this study it was shown that etched 'normal' dentine and etched caries-affected dentine had different surface appearances. Furthermore, the two caries removal techniques resulted in different caries-affected dentine surfaces after acid treatment that may influence the longevity of bonds from adhesive restorative materials.

Bonding of contemporary glass ionomer cements to dentin

OBJECTIVE

The objective of this study was to investigate the microtensile bond strength (microTBS) of contemporary glass ionomer cements (GIC) to sound coronal dentin.

METHODS

Three specimen teeth were prepared for each material tested: Fuji IX GP (GC), ChemFlex (Dentsply) and Ketac-Molar Aplicap (ESPE). GIC buildups were made according to the manufacturers' instructions. After being stored at 37 degrees C, 100% humidity for 24h, the teeth were vertically sectioned into 1x1mm beams for microTBS evaluation. Representative fractured beams were prepared for scanning (SEM) and transmission electron microscopic (TEM) examination.

RESULTS

Results of the microTBS test were: Fuji IX GP (12.4+/-8.6MPa), ChemFlex (15.0+/-9.3MPa) and Ketac-Molar Aplicap (11.4+/-7.7MPa). One-way ANOVA and a multiple comparison test showed that ChemFlex had a statistically higher microTBS (p<0.05). SEM fractographic analysis showed that the predominant failure modes were interfacial and mixed failures. The GIC side of the fractured beams revealed dehydration cracks, a high level of porosity, and voids with an eggshell-like crust. TEM analysis of the demineralized dentin sides of the fractured beams revealed the presence of an intermediate layer along the GIC-dentin interface. This zone was present on the fractured dentin surface in the case of interfacial failure, and beneath GIC remnants in specimens that exhibited a mixed failure mode.

SIGNIFICANCE

The findings suggest that the bonding of GIC to dentin is not weak and that the microTBS values probably represent the weak yield strengths of GICs under tension.

Microtensile bond strengths of glass ionomer (polyalkenoate) cements to dentine using four conditioners

OBJECTIVES

The purpose of this study was to measure the microtensile bond strengths of three glass ionomer cements to dentine (Photac-Fil Quick; Fuji II LC; Fuji IX GP) using four different conditioners (Ketac Conditioner; Dentin Conditioner; Cavity Conditioner; and an experimental conditioner, K-930).

METHODS

Superficial occlusal dentine of extracted human third molars was exposed, finished with wet 600-grit silicon carbide paper, and each of the above glass ionomer cements bonded using the four conditioners according to the manufacturers' instructions. After 24h in tap water at 37 degrees C, the teeth were sectioned to obtain 3-4 bar-shaped specimens. Ten specimens were prepared for each group and shaped to an hour-glass form of (1.2+/-0.02)mm diameter. The specimens were mounted in a jig and stressed in tension at a crosshead speed of 1mm/min until failure. The mean bond strengths were calculated and compared using one-way ANOVA and LSD tests, and the fracture modes were examined by scanning electron microscopy.

RESULTS

Mean microtensile bond strengths for Photac-Fil Quick were not significantly different from Fuji II LC for each of the conditioners used. However, the bond strengths for Photac-Fil Quick were significantly greater than Fuji II LC when no conditioner was applied. Mean microtensile bond strengths of conditioned specimens of Fuji II LC were significantly greater than non-conditioned specimens. Mean microtensile bond strengths of non-conditioned specimens of Fuji IX GP were not significantly different from conditioned specimens. The fracture mode of all specimens demonstrated mostly cohesive failure within the cement.

SIGNIFICANCE

The use of surface conditioners resulted in improvement in bond strength of Fuji II LC, while Photac-Fil Quick and Fuji IX GP showed no difference.

SEM observations of the reactions of the components of a light-activated glass polyalkenoate (ionomer) cement on bovine dentine

OBJECTIVES

Glass ionomer cements are used in clinical dentistry as lining, luting and restorative materials. The precise nature of their bonding mechanism to dentine is unclear. This study is an SEM examination of the effect of the liquid contained in Vitrebond cement (3M Co., MN) on the surface of bovine dentine, with respect to delays in photocuring and washing off with water under pressure or as a gentle stream. The effects of delaying photocuring of the mixed and applied cement for up to 120 s were also examined.

RESULTS

The results of this study demonstrated that the liquid component of Vitrebond reacts chemically with dentine in a manner suggestive of an effervescent chemical reaction. This reaction produces plugs in the dentinal tubules which are resistant to dislodgement by water under pressure or by gentle washing. Similarly, a delay in photocuring the mixed and applied cements results in porosity of the cement at the dentine interface.

CONCLUSION

The findings in this study suggest that the adhesion of Vitrebond to dentine is primarily chemical in nature and that its mechanical strength is compromised if there are substantial delays in photocuring.

Four-year evaluation of the effect of 10% polyacrylic acid or water rinsing pretreatment on retention of glass polyalkenoate cement

To optimize the bonding of glass polyalkenoate (ionomer) cement to dentin, different conditioning methods have been suggested. The effect of two easily applied conditioning methods, a 10-15 seconds cleaning with a 10% polyacrylic acid or rinsing with copious amounts of water, was compared in class V abrasion/erosion lesions. The cervical lesions were restored, without any form of mechanical cavity preparation, with an anhydrous glass ionomer cement. During a 4-yr period, 137 restorations were evaluated every 6 months. Cumulative loss rates after 4 yr were 15.6% for the polyacrylic acid group and 21.9% for the water rinsing group. The difference was not significant. No secondary caries was registered.

Adhesion of a glass ionomer cement to human radicular dentine

The adhesion of cements to root canal surfaces is a crucial factor for strengthening non-vital teeth--weakened due to extensive loss of tooth structure--by cemented posts. The aim of this study was to determine the tensile strength of a glass ionomer cement (Ketac-Cem) on root canal walls following pretreatment with conditioners. Upon cleaning and shaping, 56 straight root canals--divided into seven groups--were conditioned with one of the following solutions: NaOCl (1%) + EDTA (20%), H3PO4 (37%), HNO3 (2.5%), citric acid (6%), polyacrylic acid (10% and 20%) and NaCl (0.9%) as control. Standardized dentine cylinders were prepared out of the coronal half of each root perpendicular to the root axis and subsequently split. The exposed root canal areas were coated with Ketac-Cem. Using an universal testing machine a tensile force was applied to Ketac-Cem up to fracture. Pretreatment with EDTA-NaOCl provided the strongest bond strength (2.2 MPa). The median values for the other conditioning solutions ranged from 1.2 to 1.9 MPa. The significantly weakest bond (0.5 MPa) was recorded for NaCl. The elimination of the smear layer appeared to be an essential factor in order to improve the adhesion.

Diametral tensile strength and bonding to dentin of type I glass ionomer cements

This study evaluated the diametral tensile strength of type I glass ionomer cements and measured their tensile and shear bond strengths to dentin with and without conditioning. Four brands of glass ionomer cement and one brand of zinc phosphate cement were tested. Disks of each cement type were prepared and the 7-day diametral compression test for tension was conducted. The shear and tensile tests, with and without 10% polyacrylic acid dentin conditioning, were performed with an Instron testing machine. Two additional groups, one for each bond test, were prepared and conditioned with 90% trichloracetic acid. No significant differences of the diametral strength were found among the various glass ionomer cements. The comparison of means suggests that, except for trichloracetic acid dentin pretreatment, the conditioning is an effective promoter of shear strength and has no significant effect (p < 0.01) on the tensile bond strength. However, trichloracetic acid was found to be a most effective dentin conditioner for both shear and tensile bond strengths (p < 0.01).

The effect of dentine conditioning with polyacrylic acid on the clinical performance of glass ionomer cement--3-year results

Forty cervical abrasion lesions were restored with a self-cure Type 2A glass ionomer cement. Prior to placement of the restorations, 20 lesions were scrubbed for 15 seconds with 25 per cent polyacrylic acid and 20 lesions were cleaned with a pumice and water slurry on a rubber cup. After three years, there was negligible marginal staining, and one restoration from each group was partly lost. There was no evidence to suggest that polyacrylic acid was preferred to pumice and water in the restoration of cervical abrasion lesions with glass ionomer cement.

Three-year evaluation of effect of surface conditioning on bonding of glass ionomer cement in cervical abrasion lesions

Cervical abrasion/erosion lesions were restored without any form of mechanical cavity preparation with an anhydrous glass ionomer cement. To study the effect of dentin pretreatment on the bonding between dentin and glass ionomer cement three cleaning methods were tested: 1) mechanical cleaning with a prophylaxis paste, 2) scrubbing with a surface active cavity cleanser (Tubulicid) for 60 seconds, or 3) a 10-15 s application of a 40% polyacrylic acid solution. During a 3-yr period, 193 restorations were evaluated every 6 months. Cumulative loss rates after 3 yr were 11.6%, 12.3%, and 17.9% respectively. One restoration showed secondary caries during the evaluation period.

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

Subjects of the past decade in the dental literature are reflected in this year's Committee report. We note the decrease in the prevalence of caries, the influence of dental implants, the advancements in dental materials, and the continued efforts to control adhesive events in the oral cavity. This year we included comments from and about many significant review articles published this past year. The Committee continues to be concerned about the quality of some of the work reported and the quality of the reporting. We have attempted to select the distinguished work, that which provides new information to our profession. The subjects covered include pulp biology, caries prevention, periodontics, implants, craniomandibular function and dysfunction, occlusion, and dental materials.