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PubMed1999

Effect of toothbrushing on fluoride release of polyacid-modified composite resins.

The aim of the study was to evaluate the fluoride release of polyacid-modified composite resins (Dyr-act, Compoglass) submitted to brushing abrasion. Twenty samples were taken from each material and stored in a buffer solution (pH 4.0) for 12 days. Each day, the samples were transferred to a fresh solution. Ten samples of each material were brushed in an automatic tooth-brushing machine (250 strokes, 260-g load) every fourth day. The remaining samples were not subjected to brushing. Fluoride content of the solutions was measured with a fluoride sensitive electrode after the addition of TISAB. Statistical analysis demonstrated significant differences between the two materials with regard to cumulative fluoride release within the 12 days of the experiment. However, no difference was observed between the fluoride release of the brushed samples compared to the unbrushed specimens. This was true for both, the cumulative fluoride release and its release on the day following brushing. It is assumed that regular brushing of the tested materials did not influence their release of fluoride and that brushing of polyacid-modified composite resins does not lead to maintaining their initially high level of fluoride release.

Analysis of Variance↗
PubMed2006

Ultrastructure of gingival sulcus mucosa after application of hybrid heliocomposites.

Hybrid heliocomposites were used for repair of the carious tooth crown. Ultrastructural study of mucosa biopsy specimens from sites adjacent to the filling 3 weeks after treatment showed that Charisma, Herculite, and Esterfil Ca filling materials led to degenerative changes in the mucosa, while Filtek Z-250 heliocomposite caused no pathological changes in the gingiva at the site of contact.

Adult↗
PubMed1995

Curing shrinkage and volumetric changes of resin-modified glass ionomer restorative materials.

OBJECTIVES: The objective of the study was to evaluate initial curing shrinkage and volumetric change during water storage of six resin-modified glass ionomer cements (Dyract, DeTrey Dentsply; Fuji II LC, GC Dental Int.; Ionosit Fil, DMG; VariGlass VLC, DeTrey Dentsply; Vitremer, 3M Dental Products; Photac-Fil, ESPE), a hybrid composite (blend-a-lux, Blendax) and a chemical-cured glass ionomer cement (ChemFil Superior, DeTrey Dentsply). METHODS: The curing shrinkage was determined 5 min and 24 h after polymerization and mixing, respectively. Volumetric changes were examined after 14 d and 28 d water storage. Curing shrinkage and volumetric changes were evaluated using the hydrostatic principle. In addition, the total water content of the materials was measured after 28 d water storage. RESULTS: Curing shrinkage of most of the resin-modified glass ionomers was greater than the hybrid composite and the chemical-cured glass ionomer cement. After a 28 d water storage, the resin-modified glass ionomers showed volumetric expansion and the chemical-cured glass ionomer showed volumetric loss. All of the examined glass ionomer materials had a higher total water content than the composite. SIGNIFICANCE. The large curing shrinkage of the resin-modified glass ionomer materials measured in this in vitro study could affect the marginal integrity of glass ionomer restorations.

Acrylic Resins↗
PubMed1995

In vitro fatigue behavior of restorative composites and glass ionomers.

OBJECTIVES: This in vitro study was conducted to investigate the fatigue behavior of several dental restoratives, including composites, glass ionomers and a resin-reinforced glass ionomer. METHODS: Fatigue was imposed under a reverse stress-controlled regimen, following a staircase approach. Samples were stored and tested under both dry and wet conditions. The following parameters were measured and analyzed: Young's modulus, restrained fracture strength, and flexural fatigue limit. RESULTS: As a general trend, all products showed a decrease in Young's modulus following water sorption. For all products except the resin-reinforced glass ionomer, the same trend was seen in the restrained fracture strength. This is, however, no longer valid for the flexural fatigue limit: the trend is steady-state for the glass ionomers, status quo for the resin-reinforced glass ionomer, and all composites tested show a decrease. SIGNIFICANCE: The diversity in structure of both composites and glass ionomers does not allow findings for one product to be extrapolated to other similar products.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2006

Shear/peel bond strength of orthodontic attachments to moist and dry enamel.

INTRODUCTION: The purpose of this study was to evaluate the in-vitro shear-peel bond strength of orthodontic attachments bonded to moist and dry enamel surfaces with orthodontic resin. METHODS: Two stainless-steel mesh-based buttons were bonded to pumiced and etched enamel of each of 60 human molars mounted in cylindrical molds with Transbond XT (3M/Unitek, St Paul, Minn) (control), Smartbond (Gestenco International, Goteborg, Sweden), or Assure (Reliance Orthodontic Products, Itasca, Ill) according to each manufacturer's instructions. Half of the teeth were bonded under dry conditions, and half were given a thick layer of whole, unstimulated, fresh human saliva just before bonding. The teeth were stored in distilled deionized water at 37 degrees C. The shear-peel bond strength of 1 button on each tooth was evaluated in a testing device (Zwick, Ulm, Germany) at 24 hours; the remaining button on each tooth was evaluated at 6 months. RESULTS: Statistically significant differences (P < .05) were evident in button adhesion to the tooth surface between moisture variations for Transbond XT, but not for Assure and Smartbond. Superior bond strengths were obtained for Transbond XT on dry enamel; the bond strength of Assure to saliva-contaminated enamel was better than that of the other materials. CONCLUSIONS: Bonding to moist and dry enamel appears to be material-specific. Adequate in-vitro bonding to moist, saliva-contaminated enamel is possible with certain bonding materials.

Compomers↗
PubMed2006

Comparison of in-vitro bond strengths between resin-modified glass ionomer, polyacid-modified composite resin, and giomer adhesive systems.

INTRODUCTION: The purpose of this in-vitro study was to compare the shear bond strength of orthodontic brackets bonded to tooth enamel with 4 adhesives: a commercially available giomer material, a polyacid-modified composite resin (PMCR), a resin-modified glass ionomer (RMGI), and a standard resin-based composite (RBC) adhesive. MATERIALS: Eighty extracted human molars were collected and divided into 4 groups (n = 20). Two stainless steel premolar brackets were bonded to each tooth with 1 of the 4 adhesives, according to each manufacturers' instructions. One bracket was tested for shear bond strength at 1 hour and the other at 7 days. A shear force was applied to the bracket/tooth interface with a chisel-shaped rod attached to a universal testing machine at a crosshead speed of 0.5-mm per minute until bracket failure. The force in newtons was recorded. Debonded enamel surfaces were examined under a stereomicroscope to assess the amount of residual adhesive. RESULTS: A 2-factor analysis of variance detected significant differences among adhesive types and time of load test. The Tukey HSD test determined that the RBC and the RMGI adhesives had significantly higher shear bond strength than the giomer and the PMCR materials at both 1 hour and 7 days. The chi-square test detected a significant difference in adhesive remnant index scores. The bracket/resin interface was the most common site of failure for all groups except the RMGI group. CONCLUSIONS: RMGI orthodontic cement provides acceptable bond strength in vitro. Further clinical research is needed to validate this laboratory finding.

Acrylic Resins↗
PubMed2005

Systematic variation of interfacial phase reactivity in dental nanocomposites.

This study was designed to determine the effect of varying the chemistry of the interfacial phase on critical composite properties in dental nanocomposite materials. Silica nanoparticles were silanized with varying ratios of 3-methacryloxypropyltrimethoxysilane (MPTMS) and octyltrimethoxysilane (OTMS) while keeping the total amount of silane constant at 10% by mass fraction relative to the mass of filler. The silanized nanoparticles were mixed into a dimethacrylate resin (60% filler by mass fraction). The mechanical properties of the uncured pastes were assessed by compression testing between parallel plates. The composites were photo-cured and tested by biaxial flexure and three-point bend flexure testing. Fracture surfaces were analyzed by field-emission scanning electron microscopy (FE-SEM). At maximized filler mass fractions, the workabilities of the uncured pastes were better maintained as the fraction of OTMS in the interphase increased relative to MPTMS. The flexure strengths and moduli of the MPTMS silanized and dual silanized composites were similar but decreased as OTMS mass fractions in the silane mixture increased to 7.5% and 10%. FE-SEM images revealed evidence for phase separation in the composites containing silica silanized with high fractions of OTMS. Among the potential practical benefits of dual silanized nanoparticles are the improved workability of composite pastes with higher filler loadings that should lead to higher modulus composites with lower polymerization shrinkage.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2004

Non-destructive characterization of resin-based filling materials using Electronic Speckle Pattern Interferometry.

OBJECTIVES: The aim of this study was to develop a non-destructive test for characterizing the modulus of resin-based filling materials. METHODS: Five different visible-light-cured composites (Filtek A110 [AO], Z100 [ZO], Filtek Z250 [ZT], F2000 [FT] and Filtek Flow [FF]; 3M-ESPE) were selected for this study. An ESPI (Electronic Speckle Pattern Interferometry) apparatus involving cantilever beam specimens (28 mm long, 8 mm wide and 2 mm thick) was developed for determining modulus. Out-of-plane displacement upon force application was measured using two focus region lengths (22 mm [EI1]; 11 mm [EI2]) and modulus (n = 7) was subsequently computed based on cantilever beam equations. Data was compared to those obtained from three-point-bend flexural testing (n = 7) based on ISO4049:2000 specifications [ISO]. Specimens were stored in distilled water at 37 degrees C for 1 week prior to evaluation for all tests. Results were analyzed using ANOVA/Scheffe's post-hoc tests (p < 0.05) and Pearson's correlation (p < 0.01). RESULTS: Modulus ranged from 5.53 to 13.99, 5.78 to 14.24 and 4.26 to 11.30 GPa for EI1, EI2 and ISO, respectively. For all three tests, the modulus of ZO and FT was significantly greater than ZT, which in turn was significantly greater than AO and FF. Correlation of EI1 and EI2 to ISO was significant, positive and very strong (r = 0.94 for EI1 and EI2). SIGNIFICANCE: ESPI may be a viable method of characterizing the modulus of resin-based filling materials. As it is a non-destructive test, time-dependent effects of composites can be determined using the same specimens leading to substantial time and material savings.

Analysis of Variance↗
PubMed2004

Shear bond strength of different types of luting cements to an aluminum oxide-reinforced glass ceramic core material.

OBJECTIVE: The aim of this study was to find the optimal choice of luting cement to Synthoceram, an aluminum oxide-reinforced glass ceramic material. The bond strength of five different commercial luting cements to the ceramic material was evaluated. The effect of surface treatments, etching, sandblasting, silanizing, and combinations of these treatments was also investigated. METHODS: Shear bond strength tests were performed using the ceramic material as substrate with each of the luting cements. Cements rods were prepared on pre-treated ceramic surfaces. The shear bond strength was determined 24 h after cementation. The effect of surface treatments: etching, sandblasting, and sandblasting followed by etching, respectively, on the morphology of the material, was investigated with SEM. RESULTS: The shear bond strength increases significantly from Ketac Cem, Rely X Luting, Fuji Plus, Panavia F to Xeno Cem. The surface treatments etching and/or sandblasting followed by silanization generally provide the highest bond strength values. SIGNIFICANCE: Based on the results of this study, the use of resin composite based cements is preferred for cementation of an all-ceramic restoration with an aluminum oxide-reinforced glass ceramic base. Surface treatment of etching and/or sandblasting followed by silanization is recommended.

Aluminum Oxide↗
PubMed2004

Curing depth of (polyacid-modified) composite resins determined by scraping and a penetrometer.

OBJECTIVES: The present study aimed to compare the curing depth of polyacid-modified composite resins (PAM-C) and some representative composite resins as a function of shade and post-cure using a scraping method and a penetrometer. METHODS: The curing depth of the PAM-C Hytac, F2000, Glasiosite, Dyract, Dyract AP, and Compoglass F and of the composite resins Durafill VS and Z100 were determined for shade A2 and A4 using a scraping method based on ISO 4049:2000 and a digital penetrometer. Samples were light-cured (800 mW/cm2 at 40 s) in bulk in split stainless steel molds. Immediately after light-curing or after a 24 h post-cure, the height of the cylinder of cured material was measured and taken as the curing depth. RESULTS: For both test methods, the curing depth was independent of post-cure (P > or = 0.05) but differed significantly among materials and shade (P<0.001). Moreover, there was a significant interaction between the latter (P<0.001). Regression analysis generally demonstrated that there was no significant systematic or proportional difference between the test methods. The curing depths of the PAM-C F2000 and Glasiosite were comparable to that of the hybrid composite Z100, but greater than the curing depth of the microfilled composite Durafill VS. The PAM-C Dyract AP, Dyract, Compoglass F and Hytac had a curing depth smaller than that of the microfilled composite. SIGNIFICANCE: The scraping method based on ISO 4049:2000 and a digital penetrometer give comparable curing depths for PAM-C. The curing depth greatly varies among the materials and can be considerably smaller than that of a microfilled composite resin. Shade A2 results in significantly greater values for the curing depth compared to shade A4, the effect depending quantitatively on the formulation of the material.

Color↗
PubMed2005

An FTIR study of the effects of artificial saliva on the physical characteristics of the glass ionomer cements used for art.

OBJECTIVE: To investigate the physical and chemical changes of five esthetic restorative materials in an artificial saliva using Fourier transform infrared spectroscopy (FTIR). METHODS: The materials included two glass polyalkenoate (ionomer) cements, one polyacid-modified resin composite, and two resin composites. Five fresh and 20 aged specimens for each material were immersed in 2 ml of artificial saliva at 37 degrees C for 1 week, 2 weeks, 1 month, and 2 months. They were examined by laser surface profilometer and FTIR. RESULTS: Surface roughness average (Ra) value showed significant differences among the physical properties of glass ionomers, polyacid-modified resin composite, and resin composites. SIGNIFICANCE: FTIR spectra showed that a major chemical changes in Fuji IX GP Fast glass ionomer cement in P-NH2 group bonding (900-1000 cm(-1)) that may explain the previously reported increase in microhardness after immersion. There was no direct correlation between surface roughness and spectral changes of the materials tested.

Compomers↗
PubMed2005

Effects of surface finish on indentation modulus and hardness of dental composite restoratives.

OBJECTIVES: The depth-sensing micro-indentation testing was recently introduced for the characterization of dental composites. One of the critical issues raised was the possible influence of surface finish on material properties. The aim of this study was to investigate the effects of surface finish on the indentation modulus and micro-hardness of resin-based dental composite materials. METHODS: The materials used included minifill (Z100, 3M ESPE), microfill (A110, 3M ESPE) and poly-acid modified (F2000, 3M ESPE) composites. The specimens were polished successively using SiC grinding papers of different grit size and diamond suspensions to achieve varying surface roughness. The arithmetic mean of the roughness (R(a)) was measured using profilometry. In the depth-sensing micro-indentation test, specimens (n=7) were indented to 10N with Vickers indenter and the load-displacement (P-h) data was obtained using a universal testing system. The indentation modulus (E(in)) and hardness (H) were then computed using the developed analytical solutions. Data was analyzed using ANOVA/post-hoc Scheffe's test at significance level 0.05. RESULTS: The polished specimens had surface roughness ranging from 0.02 to 0.81 microm. The roughness of F2000 was significantly higher than A110 and Z100. The E(in) and H for Z100 ranged from 14.02 to 14.83GPa and 1.18 to 1.27 GPa, respectively. E(in) for F2000 and A110 ranged from 12.25 to 13.82 GPa and 5.26 to 5.52 GPa and hardness ranged from 0.89 to 0.98 GPa and 0.52 to 0.55 GPa, respectively. SIGNIFICANCE: The indentation modulus and hardness of dental composite restoratives were independent of the surface finish provided indenter penetration is sufficiently deep (h(max)/R(a)>30).

Compomers↗
PubMed2006

Relative curing degree of polyacid-modified and conventional resin composites determined by surface Knoop hardness.

OBJECTIVES: The aim of the present study was to investigate the relative curing degree at a depth of 2 mm of several polyacid-modified composites (PAM-Cs) as a function of shade. METHODS: The Knoop hardness of the irradiated top and non-irradiated bottom surfaces of 2 mm thick samples of the PAM-Cs Hytac, F2000, Glasiosite, Dyract, Dyract AP, and Compoglass F and of the resin composites Z100, Herculite Enamel XRV, and Durafill VS, were determined for shades A2 and A4. RESULTS: The top and bottom hardness of F2000 and Glasiosite ranged between that of the two composites Herculite and Z100. Compoglass, Dyract and Dyract AP had a lower top and bottom hardness than the hybrid composites, but higher than that of the microfilled composite Durafill. The top hardness of Hytac compared with that of the first group, whereas the bottom hardness compared with the second group. The bottom-to-top KHN ratio reflecting the relative curing degree at a depth of 2 mm was less than 80% for the two shades of Hytac and Compoglass as well as for the A4 shade of Dyract AP and Herculite. SIGNIFICANCE: A hard top surface of a PAM-C is not an indication of adequate in depth polymerization. Shade A2 results in significantly greater values for the curing degree compared to shade A4, the effect depending quantitatively on the formulation of the material. Some formulations of PAM-C do not reach an adequate curing degree at a depth of 2 mm so that it is recommended to apply the incremental technique even in box-only cavities with layers of maximum 2 mm.

Color↗
PubMed2006

Effect of bleaching on subsurface micro-hardness of composite and a polyacid modified composite.

OBJECTIVE: To investigate the influence of different bleaching techniques on subsurface physical properties of composite and polyacid modified composite tested via determination of micro-hardness. METHODS: Specimens of Tetric Flow, Tetric EvoCeram and Compoglass were light cured (2.5mm thickness) and stored in artificial saliva for 2 weeks (n=12/group). The samples were only removed for application of the following bleaching agents in a humid atmosphere: Either Vivastyle (1h/d), Whitestrips (30min/d), sodium-perborate-water mixture (once for 72h), Simply White (1h/d), or Opalescence XtraBoost (1st and 5th day for 15min) were applied on the surfaces of the samples. Untreated specimens served as negative controls, samples treated with ethyl alcohol for 1h acted as positive controls. After the bleaching period, samples were cross-sectioned and the micro-hardness (Knoop) of different subsurface levels (0.1mm-2.0mm) was determined. RESULTS: All bleaching techniques significantly reduced the Knoop-hardness of the restoratives compared to untreated controls. Thereby, bleaching significantly affected not only superficial but also the deep layers of the specimens: in superficial layers (0.1mm, 0.2mm) lowest micro-hardness values amounted to 69.5% and 76.3% of the respective untreated controls (Compoglass/Vivastyle). In deeper subsurface levels, the lowest hardness was observed with Opalescence/Tetric EvoCeram (0.3mm: 78.3%; 0.4mm: 80%; 0.5mm: 80.5%; 1.0mm: 84.2%; 2.0mm: 84.4%). SIGNIFICANCE: Bleaching with the tested bleaching agents softens the adhesive restorative materials examined. Due to the fact that subsurface layers are also affected, polishing of the surface may not suffice for re-establishing the physical properties of the surface of the fillings.

Borates↗
PubMed2006

Effect of selected mouthwashes on the surface roughness of resin modified glass-ionomer restorative materials.

OBJECTIVES: It is known that the use of mouthwashes and toothbrushing can affect some restorative dental materials. The purpose of this laboratory study was to investigate the effect of four commercially available mouthwashes on the surface roughness of a number of resin modified glass-ionomer restorative materials when used with and without tooth brushing. METHODS: Specimens of the restorative materials in the study (Vitremer, Compoglass and Dyract) were prepared. Half of the specimens were only exposed to a mouthwash (Plax, Macleans, Listerine, Corsodyl or deionised water as control). The remaining specimens were exposed to one of the mouthwashes in conjunction with tooth brushing. The initial surface roughness and the subsequent changes in surface roughness were assessed by scanning electron microscopy (SEM) and profilometry. The assessment times were: baseline, 4, 12 and 24 weeks. RESULTS: Initial SEM observations of the surface morphology of the specimens revealed a rougher surface for Vitremer in comparison to the other two materials. Assessments at increasing time intervals showed that specimens exposed to a mouthwash only appeared to become rougher. The appearance of specimens exposed to mouthwash and brushing seemed to become even rougher with increasing time. The results of the profilometric assessment showed that at 24 weeks, specimens exposed to mouthwash only, had an overall increase in the surface roughness values for all three materials investigated. The differences between groups allocated to different mouthwashes were not however statistically significant (P>0.05). Exposure to mouthwash and toothbrushing over the same time period resulted in an increase in roughness values in all groups. The differences between mouthwash groups were not statistically significant at this stage (P>0.05). SIGNIFICANCE: Exposure of the materials investigated to the mouthwashes included in the study had adverse effects on surface roughness. The adverse effects were more pronounced with tooth brushing.

Compomers↗
PubMed2006

Linear regression modeling to compare fluoride release profiles of various restorative materials.

OBJECTIVES: The aim of this study was to compare the released fluoride profiles of various restorative materials by using linear regression analysis. METHODS: Specimens were prepared using a cylindrical Teflon mold with a height of 2 mm and a radius of 8 mm. After being prepared, specimens were immediately placed into artificial saliva which was replaced at various times during 6 weeks. These released intrinsic fluoride amounts were measured by using an ion selective electrode. Then, data obtained cumulatively were statistically analyzed, and the released profiles were compared. RESULTS: It was observed that the materials released fluoride at different levels of concentration and the largest fluoride release was obtained from the conventional glass ionomer cement. This was followed by resin modified glass ionomer cement, polyacid modified composite resin, and fluoride releasing composite resin, respectively. Although the released fluoride amounts of the materials were different, their release profiles were found to be similar in that the release was initially fast and then it became steady as time passed. SIGNIFICANCE: The statistical modeling of the release profiles helps to compare the fluoride release behavior of materials and also to predict fluoride release amounts for the future. In literature, for these purposes, separate nonlinear statistical models have extensively been utilized. However, the single linear statistical modeling approach has numerous advantages such as providing estimators having good statistical properties, exact results, precise inference and simplicity in calculation. Therefore, this study was conducted to introduce the use of single linear regression modeling to compare release profiles statistically.

Compomers↗
PubMed2004

Influence of Er:YAG laser on tensile bond strength of a self-etching system and a flowable resin in different dentin depths.

OBJECTIVE: The aim of this study was to evaluate the tensile resistance of a flowable resin in different dentin depths, after superficial treatment with Er:YAG laser. METHODS: Eighteen molars were selected and roots were removed. Crowns were bisected in half, embedded in polyester resin and ground until dentin was exposed. The bonding site was delimited and samples were randomly assigned into two groups: superficial dentin (SD--1 mm from amelodentinal junction) and deep dentin (DD--2 mm from amelodentinal junction). The samples were subdivided in three groups according to superficial treatment: non-rinsing conditioner (NRC) solely; Er:YAG laser (80 mJ/2 Hz)+NRC; Er:YAG laser solely. After conditioning, Prime and Bond NT/Dyract flow (Dentsply) was used for the manufacture of specimens. They were adapted to a metallic device, where resin cones were prepared. Samples were stored for 24 h and subjected to a bond strength test (50 kgf at 0.5 mm/min). RESULTS: Means in MPa were: SD-NRC solely 12.29 (+/-4.40); laser+NRC 12.11(+/-3.23); laser solely 5.74(+/-3.01) and DD-NRC solely 9.60 (+/-3.13); laser+NRC 10.44(+/-2.23); laser solely 3.50(+/-1.70). Data were submitted to statistical analysis by ANOVA and Scheffé test (p < 0.05). CONCLUSIONS: SD produced better results and tensile bond strength, while on DD the treatment with NRC or Laser+NRC had higher tensile bond strength. The results suggest that when Er:YAG laser for dentin treatment is used, it is mandatory to associate it to a conditioning agent.

Acid Etching, Dental↗
PubMed2004

Influence of food-simulating solutions and surface finish on susceptibility to staining of aesthetic restorative materials.

OBJECTIVES: To determine the degree of surface staining of resin-based composites (RBCs) and glass-ionomer cements (GICs) after immersion in various stains and food-simulating solutions (FSS). METHODS: Six tooth-coloured restorative materials were used: a light-cured microfilled RBC (Durafil, Kulzer), a light-cured microglass RBC (Charisma, Kulzer), a polyacid-modified RBC (F2000, 3M/ESPE), a conventional GIC (Fuji IX, GC) and two resin-modified GICs (Fuji II LC, GC; Photac Fil, 3M/ESPE). Disk-shaped specimens were prepared and tested with either a matrix finish or polished using wet silicon carbide papers up to 2000 grit. All specimens were immersed in 37 degrees C distilled water for 1 week, followed by three different FSS (water, 10% ethanol, Crodamol GTCC) and five stains (red wine, coffee, tea, soy sauce and cola) for a further 2 weeks. Three specimens of each material for each stain were tested. Colour coefficients (CIE L* a* b*) were measured by a spectrophotometer after each treatment. The change in colour (DeltaEn) was calculated using the formula: DeltaEn=[(DeltaLn+(Deltaa(n))2+(Deltab(n))2]1/2. RESULTS: Distilled water caused no perceptible colour change as tested by ANOVA and Tukey's tests. The effect of surface finish on staining was not statistically significant (P>0.05). There was no strong interaction between FSS and stains or between FSS and materials. There was a strong interaction between surface and material, and stain and material (P<0.001). CONCLUSIONS: All materials were susceptible to staining by all stains especially coffee, red wine and tea; Fuji IX showed the least susceptibility and F2000 the greatest.

Analysis of Variance↗