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Biomedical subjects

F A de Wet

Publications and source records attributed to F A de Wet.

At least 19 recordsLinked to original sources
PubMed2006

Self-etching bonding systems: in-vitro shear bond strength evaluation.

The purpose of this in vitro study was to compare the dentine shear bond strength of five self-etching bonding agents with that of a total-etch dentine bonding agent (used as control). Sixty recently extracted third molar teeth were mounted in acrylic resin and the occlusal surfaces ground to expose superficial dentine. A standardised smear layer was created by polishing with wet 600-grit SiC paper. Products evaluated were Xeno III (XIII), Clearfil SE Bond (SE), ABF (ABF), Optibond Solo Self-etch (OS), Adper Prompt-L-Pop (PLP) and the control, Scotchbond Multipurpose Plus (SBMP). Resin stubs were bonded to the dentine using the bonding agents according to manufacturer's instructions. Composite stubs were manufactured using an Ultradent jig and two increments of Z100, A1 shade composite. The bonds were subsequently stressed to failure with an Instron testing machine, operating at a crosshead speed of 0.5 mm/min. The data was statistically analysed using ANOVA (alpha < or = 0.05). The mean SBS (MPa) were: SBMP (Control) = 24.1 +/- 7.6; XIII = 17.3 +/- 4.1; SE = 26.2 +/- 7.8; ABF = 25.9 +/- 4.3; OS = 21.9 +/- 3.9 and PLP = 15.4 +/- 3.1. The shear bond strengths of both XIII and PLP to dentine were significantly lower than the control SBMP (p < 0.05). The remaining three products (SE, ABF and OS) displayed bond strengths comparable to the control (p > 0.05). Further research into cut (ground) and un-cut (un-ground) enamel shear bond strength and micro-leakage using these bonding agents are needed.

Analysis of Variance↗
PubMed2006

Self-etching bonding systems: in-vitro micro-leakage evaluation.

The purpose of this in vitro study was to compare dentine and enamel micro-leakage values of six self-etching bonding agents to that of a total etch dentine bonding agent (used as a control). Products evaluated were Scotchbond Multipurpose Plus (3M/ESPE), Xeno III (Dentsply), Clearfil SE Bond (Kuraray), ABF (Kuraray), Optibond Solo Self-Etch (Kerr), OneCoatSE Bond (Colténe Whaledent), and iBond (Heraeus-Kulzer). Using a medium sized Cerana bur (Nordiska Dental) a standard, cylindrical preparation was made at the cemento-enamel junction (CEJ) of human third molars. The teeth were randomly divided into 7 groups of ten teeth each. The bonding agents were applied and light cured strictly according to the manufacturer's instructions and the cavities then filled in two increments, using Z100 composite (3M/ESPE). The restored teeth were imbedded in acrylic resin and thermocycled between 5 degrees - 60 degrees C (+/- 2 degrees C) for 250 cycles with a dwell time of 20 seconds. All seven groups were then placed in a 5% basic Fuchsin solution for 12 hours at 37 degrees C. The embedded teeth were removed from the basic Fuchsin, rinsed well, imbedded in acrylic and cut longitudinally through the centre of each restoration using an Accutom-2 cutting machine. Each tooth was then evaluated at the occlusal enamel margin and at the cervical dentine margin for micro-leakage using a light microscope at 50x magnification. The data obtained was analysed using the Kruskal-Wallis test, with Fisher's least significant difference method used for comparison of specific groups (p<0.05). When compared to the control (Scotchbond Multipurpose Plus), results for microleakage at the occlusal enamel margins as well as the cervical dentine margins indicated that only SE Bond and ABF (Protect Bond) showed values as low as the control. It can be concluded that, as far as micro-leakage is concerned, Clearfil SE Bond and ABF (Protect Bond) self-etching bonding agents could be clinically acceptable alternatives to the clinically proven Scotch-bond Multipurpose. The other products showed more microleakage.

Acid Etching, Dental↗
PubMed2005

Shear bond strength of five porcelain repair systems on cerec porcelain.

The purpose of this in vitro investigation was to evaluate the shear bond strength of composite resin bonded to Cerec Vitablocs Mark II porcelain with four different porcelain repair systems. The systems evaluated in this study were Scotchbond/ RelyX Primer (S/ 3M), Ultradent Porcelain Repair Kit (U, Ultradent), Vivadent Ceramic Repair Kit (V, Vivadent) and Prime & Bond NT/ Calibra Silane Coupling Agent (P, Dentsply). Seventy five Cerec Vitablocks Mark II porcelain were embedded in metal rings, leaving 7 mm of porcelain exposed above the ring surface. Samples were ground wet on 400 grit SiC paper to roughen the surface and then screened for surface defects. The five porcelain repair agents were applied according to manufacturers' instructions and matching composite stubbs, then bonded onto 15 treated porcelain surfaces, using an Ultradent mould with a diameter of 2,38 mm. All samples were stored in distilled water for 24 hours at 37 degrees C before the bonds were stressed to failure, using a shear load in a Texture Analyser (TAXT2i) (Stable Micro Systems) Data was analyzed statistically (ANOVA). The effects of the pretreatments on the porcelain surfaces after treatment with the different systems were examined in a Scanning Electron Microscope (SEM), and the modes of fracture were assessed under a light microscope. The mean SBS (MPa) for the products in descending order were: U = 26.6 1.7; V = 20.9 3.4; C = 19.4 5.3; S = 18.0 2.0 and P = 15.9 2.1. The Student-t Test revealed a statistical significant difference (p < 0.05) between the mean shear bond strengths of P and U. There was also a statistical significant difference (p < 0.05) between the mean shear bond strengths of P and V. Most debonded specimens showed cohesive fractures in the porcelain. Significant shear bond strength differences were observed for the different repair systems. All the systems tested can probably be used to repair Cerec Vitablocs Mark II porcelain, with some systems providing higher bond strengths.

Acrylic Resins↗
PubMed2004

Flexural properties of denture-base polymer reinforced with glass-fibre polysulphone composite.

The aim of this study was to determine the effect of glass-fibre composite reinforcement on the flexural strength and flexural modulus poly-methyl methacrylate (PMMA). Prefabricated electrical glass-fibre polysulphone composite rods (GF/PSu), 3mm in diameter, were incorporated in cylindrical, heat polymerizing PMMA specimens with diameters of 4, 5 and 6mm respectively (n = 10). These specimens were compared with PMMA control groups of similar dimension. A three point loading test was performed in air after storage of specimens in water at 37 degrees C for 8 weeks. The following variables were measured : Flexural Strength (FS) and Flexural Modulus (FM). The data were analyzed using one way analysis of variance (ANOVA). After testing, the fracture zone was evaluated using a scanning electron microscope (SEM). The glass-fibre reinforcement used in this study significantly enhanced both the FM and FS values of PMMA. This enhancement was, however, progressively reduced in relation to an increase in cross-sectional dimension of the specimens. SEM evaluation revealed delamination and fracture of the glass-fibres in the polymer matrix.

Adhesiveness↗
PubMed2004

Anti-bacterial efficacy of new self-etching dentine bonding agent.

Since a perfect seal is not easily achieved during bonding procedures, any product which will limit or delay bacterial proliferation in the resulting micro-leakage spaces should extend the life span of bonded restorations. This study compared the antibacterial properties of an experimental, self-etching, fluoride-releasing, antibacterial bonding system (ABF) with two standard bonding systems (SE Bond and Scotchbond MP). Spread plates of three different bacteria (Streptococcus mutans, Lactobacillus paracasei and Actinomyces naeslundii) were prepared on Brain-Heart Infusion agar. Standardised, sterilised filtration paper disks were infiltrated with 20 microl of primer and then placed on the inoculated agar and incubated at 37 degrees C for 48 hours. The extent of the inhibition zones were measured at different positions and data were analysed using the Student t-test to determine significant differences. All three primers showed zones of inhibition for all three bacteria tested. Inhibition zones for ABF primer against S. mutans were significantly larger (p<0.05) compared to that of Scotchbond MP and SE Bond. In general the antibacterial activity of the three primers against the three bacteria tested varied, and the inhibitory effect for the experimental primer was significantly superior against S. mutans only.

Actinomyces↗
PubMed2004

Resin-infiltrated-dentine--a FE-ESEM microscopy investigation.

The formation of a hybrid layer is essential for bonding of dental composites to dentine. The objective of this study was to examine the effects of various etchants/conditioners and dentine bonding systems on dentine surfaces utilising a Field Emission Environmental SEM (FE-ESEM). Twenty one, freshly extracted human molar teeth were utilised. Dentine without resin application was initially observed both wet and dried in the following conditions: (1) fractured surface, (2) smear layer, and (3) smear layer removed with 37% phosphoric acid. Resin infiltration into dentine was then studied after applying Scotchbond 1, Optibond Solo, Prime & Bond NT, or Prompt L-Pop systems. Scotchbond 1, Optibond Solo, and Prime & Bond NT resins penetrated the dentine tubules and created hybrid layers; although, in some cases Prime & Bond NT only created a partially filled hybrid layer. No polymerised resin or hybrid layer was observed for Prompt L-Pop. The FE-ESEM permitted observation of specimens at near in-vivo wet conditions.

Acid Etching, Dental↗
PubMed2003

Effect of biological contamination on dentine bond strength of adhesive resins.

The purpose of this in vitro study was to determine the effect of saliva (S) and blood (B) contamination on the dentine bond strength of two single-component dentine bonding systems. The occlusal thirds of 120 recently extracted, human molars were removed with a low speed saw and subsequently embedded in Bencor rings by means of self-curing, acrylic resin. The occlusal surfaces were ground wet on 600-grit silicone carbide paper in a polishing machine to expose superficial dentine and to create a smear layer. The teeth were randomly divided into 12 groups (n = 10). All the dentine surfaces were etched with 34% phosphoric acid for 15 seconds rinsed with water, air-dried for 3 seconds, leaving the surfaces visibly moist. For the control groups (C) the etched dentine surfaces were treated with either, Scotchbond 1 (SB1, 3M) or Prime & Bond NT (PBNT, Dentsply) according to the manufacturer's instructions. In the contaminated groups, the saliva or blood was applied by means of a disposable brush, left undisturbed for 1 minute, and the excess then thinned by air spray. The dentine bonding systems were then applied, also according to manufacturer's instructions. Composite (Z250 and TPH) and Compomer (F2000 and Dyract AP (D-AP)) stubs were packed and cured incrementally to the corresponding pretreated dentine surfaces. All specimens were stored for 24 hours under water at 37 degrees C. The bonds were then stressed to failure with a Zwick testing machine, operating at a crosshead speed of 0.5 mm/min. Fractured samples were examined in a Scanning Electron Microscope. The data were statistically analysed (Student-t test). The mean SBS (MPa) were. SB1 with Z250: C = 19.1 +/- 4.4; S = 17.3 +/- 3.5; B = 2.6 +/- 0.9; SB1 with F2000: C = 11.8 +/- 3.3; S = 9.7 +/- 1.8; B = 4.7 +/- 1.6. PBNT with TPH: C = 9.2 +/- 3.2; S = 6.5 +/- 3.0; B = 4.3 +/- 1.5; PBNT with D-AP: C = 10.2 +/- 3.6; S = 9.3 +/- 2.9 and B = 7.3 +/- 2.5. There was no statistical significant difference in shear bond strengths between the control and the saliva-contaminated samples for both systems. There was, however, a significant difference in bond strengths between the control and the blood-contaminated samples. Blood contamination negatively influenced bond strength of bonding systems to dentine.

Blood↗
PubMed2003

Dental materials used by general dental practitioners.

As a follow-up to previous surveys regarding materials used by dentists a total of 1500 questionnaires were distributed to general dental practitioners in private practice. A response rate of 11.8% was achieved. The most popular products used during 1999 were identified. Changes in the choices of materials were observed when compared to previous surveys. This may be attributed to the development of various new products.

Choice Behavior↗
PubMed2000

The current state of dentine bonding systems: a review of materials and techniques.

The acid-etch technique for bonding composite resin to enamel is a well-established clinical procedure. Although bonding composite resin to dentine has proved to be a difficult challenge, it has become an indispensable link in aesthetic dentistry. The purpose of this article is to provide a brief history of dentinal bonding as well as an overview of clinical indications and available products for the bonding of composites and/or amalgam.

Acid Etching, Dental↗
PubMed2000

Environmental scanning electron microscopy of hydrated conditioned/etched dentine.

Various etchants/conditioners are used during dental treatment to affect or remove the smear layer. The purpose of this study was to evaluate the effect of different treatments on moist dentine, using a field emission environmental scanning electron microscope (FE-ESEM). Twenty freshly extracted, human molar teeth were utilised. The roots and pulps were removed, and the crowns horizontally sectioned with a low speed diamond saw (Isomet) (with cooling in a saline solution) in order to expose superficial dentine. A smear layer was created on these surfaces by using 600 grit silicone carbide paper. Test surfaces were then treated in one of the following ways: 1. 37% phosphoric acid liquid 2. 37% phosphoric acid gel 3. NRC (non-rinse conditioner) without rinsing 4. NRC with rinsing. Shallow grooves were cut on the untreated sides, using a thin diamond bur. This enabled the samples to be split in half when pressure was applied in the grooves. Samples were maintained moist throughout specimen preparation. Samples were examined in the FE-ESEM (Philips XL 30) in such a way that the effect of the treatment could be viewed occlusally, as well as perpendicular to the treated interface. Phosphoric acid liquid and gel removed the smear layer, and demineralised the dentine for approximately 5-10 micrometers. NRC penetrated the smear layer and modified it to a lesser degree. However, washing of the NRC treated surface removed part of the smear layer, and opened up some dentinal tubules. Excellent resolution was possible with the FE-ESEM in both the wet and dry modes.

Acid Etching, Dental↗
PubMed1999

Shock absorption potential of different mouth guard materials.

STATEMENT OF PROBLEM: Clinical stresses and situations in the mouths of patients are substantially different; thus, it is not possible to make an exact in vivo comparison of the efficiency of various mouth guards. PURPOSE: This study developed a device and a method to test and quantify the potential of mouth guards to absorb shock and evaluated and compared 5 designs for mouth guards. MATERIAL AND METHODS: Strain gauges and accelerometer sensors were mounted in various positions on the maxilla and inside an artificial skull. Sensors quantified the response of several areas of the skull to inputs of force on the maxillary teeth protected by the mouth guard being investigated. Input of force was applied to the maxillary teeth with a modal hammer equipped with a load cell. Five mouth guards of each of 5 designs were manufactured and placed in position before force was applied to the maxillary teeth. All inputs were measured and analyzed and, from those results, a method was developed to quantify the relative potential of the mouth guards to absorb shock. This method was then used to quantify the shock absorption potential of the 5 types of mouth guard designs. RESULTS: All 5 types of mouth guards provided some measure of protection and were better than no protection. However, the level of protection provided by the 5 mouth guard designs differed.

Dental Stress Analysis↗
PubMed1998

The film thickness of five adhesive resin cements.

The purpose of this in vitro investigation was to determine the film thickness of five resin cements, namely All-Bond 2(Bisco,AB), C&B-Metabond(Parkell,CB), Enforce(Caulk/Dentsply,E), Imperva Dual(Shofu,ID) and Panavia EX(Kuraray,P). An electronic gauge with an accuracy of 0.5 micron was recalibrated after each recording, and each cement was measured 10 times. Statistical analysis was carried out using the ANOVA test. The mean film thickness values (micron) of the five cements were: AB = 58.8 +/- 4; CB = 35.8 +/- 1.2; E = 22.9 +/- 1.4; ID = 25.7 +/- 1.2 and P = 44.3 +/- 1.2. There was a statistical significant difference between the film thicknesses of AB and the other cements (p < 0.05). The ID and E cements also demonstrated statistically significant lower film thicknesses than CB and P (p < 0.01). Imperva Dual and Enforce demonstrated the lowest and All-Bond 2 the highest film thickness values.

American Dental Association↗
PubMed1997

Bonding of composite resin using different enamel etchants.

Bonding systems make use of different types and concentrations of enamel etchants. The purpose of this in vitro investigation was to determine the shear bond strength of composite resin to etched enamel using different enamel etchants. The following etchants were used: 35 per cent phosphoric acid for 30 seconds, (Group 1, control), 10 per cent phosphoric acid for 20 seconds (Group 2), 10 per cent maleic acid for 15 seconds (Group 3), 65 per cent phosphoric acid for 30 seconds (Group 4) and 10 per cent citric acid/3 per cent ferric chloride for 30 seconds (Group 5). Composite (Z100) stubs were bonded to the adhesively treated etched enamel surfaces using a rubber split mould. The bonded specimens were stored in distilled water for 24 hours before they were stressed to failure using a shear load in an instron testing machine. Data were analysed statistically (Student-t-test). The micromorphology of the enamel etched with the different etchants was also evaluated in a SEM. Shear bond strength (MPa) for the different groups were as follows: group 1 (23.9), group 2 (18.9), group 3 (18.0), group 4 (20.4) and group 5 (15.6). Ten per cent maleic acid, 10 per cent phosphoric acid and 10 per cent citric acid/3 per cent ferric chloride demonstrated lower enamel bond strengths than conventional 35 per cent phosphoric acid.

Acid Etching, Dental↗
PubMed1997

Shear bond strength of four dentine bonding systems to dry and moist dentine.

Recent studies demonstrated that dentine wetness may be an important factor influencing the bond strength of dentine bonding systems. The purpose of this in vitro study was to evaluate the ability of four different dentine bonding systems to bond to dry (Group 1) and moist (Group 2) dentine. The four systems tested were Scotchbond Multi-Purpose (SMP, 3M), Imperva Bond (IB, Shofu), All-Bond 2 (AB2, Bisco) and OptiBond (OB, Kerr). In Group 1 the products were applied to dentine surfaces which had been dried with compressed air, after the etchant was rinsed off. In Group 2, however, the dentine was wiped with a damp facial tissue to remove excess water from the surface after rinsing off the etchant. The bond strengths (MPa) for the different products to dry (D) and moist (M) dentine were as follows: SMP: D: 24.9 +/- 4.5; M: 18.9 +/- 4.4; IB: D: 19.2 +/- 3.6; M; 15.6 +/- 2.8; OB: D: 25.9 +/- 2.9; M: 24.5 +/- 4.5 and AB2: D: 16.3 +/- 2.6; M: 27.2 +/- 2.3. Data were statistically analysed using the Wilcoxon Sum of Rank as well as Kruskal-Wallis tests. SMP and IB showed statistically significant higher bond strengths to dry dentine than to moist dentine. OB demonstrated no significant difference in bond strength between dry and moist dentine. AB2, however, demonstrated significantly higher bond strengths to moist than to dry dentine.

Dental Bonding↗
PubMed1996

Repair of Cerec porcelain with seven different systems.

Intra-oral repair of fractured porcelain is a challenging clinical necessity, because time, economics, as well as possible trauma to teeth, often contra-indicate replacement of the original restoration. The purpose of this study was to evaluate the bond strength of seven different porcelain repair systems used in combination with Cerec Vitablocs Mark II porcelain. The systems were Scotchbond Multi-Purpose (SMP), All-Bond 2 (AB), Optibond (OB), C&B Metabond (CB), Imperva Bond (IB), Silistor (S) and Mirage Bond (MB). When Mirage Bond was used, the porcelain was either etched with 9.6 percent hydrofluoric acid for 2 min (10 specimens = MB1) or with 4 percent APF gel for 2 min (10 specimens = MB2). The shear bond strengths (SBS) of all the products were determined using an Instron. The effects of the pretreatments on the porcelain with different systems were also examined in a SEM. Data were statistically analysed (Wilcoxon Sum of Rank Test). The mean SBS (MPa) of the products were: SMP = 22.6 +/- 6.5; AB = 17.1 +/- 4.1; OB = 17.1 +/- 2.3; CB = 25.8 +/- 4.2; IB = 18.3 +/- 5.2; S = 16.4 +/- 3.7; MB1 = 13.1 +/- 3.9 and MB2 = 6 +/- 2.1. CB and SMP were significantly stronger (p < 0.05) than all other products, with MB2 statistically weaker (p < 0.01) than the other groups. Most specimens showed cohesive fractures in the porcelain, except when MB was used with 4 percent APF gel, where all samples fractured at the adhesive interface. It can be concluded that all seven systems can be used to repair Cerec Porcelain, except possibly MB when used in conjunction with 4 percent APF etchant.

Ceramics↗