Effects of polishing techniques on the surface roughness of acrylic denture base resins

STATEMENT OF PROBLEM: Rough surfaces of denture bases promote adhesion of microorganisms and plaque formation. It is therefore important to know how different polishing systems affect surface roughness of denture base acrylic resins. PURPOSE: The objective of this study was to compare the effects of 4 chairside polishing kits and 2 conventional laboratory techniques used for polishing 3 different acrylic denture base resins. MATERIAL AND METHODS: Using contact profilometric measurement, the surface texture of 54 specimens (15x30x3 mm) per acrylic material (autopolymerized ProBase Cold, heat-polymerized ProBase Hot, and injection heat-polymerized SR Ivocap plus) was studied before and after cutting with a tungsten carbide bur, and during and after chairside polishing with 4 polishing kits (Exa Technique, Acrylic Polisher HP blue, AcryPoint, Becht Polishing Cream), and after conventional polishing with 2 polishing systems (Universal Polishing Paste for Resins and Metals, Lesk Polishing Liquid). There were 9 specimens for each acrylic resin material and polishing method combination. Conventional lathe polishing with polishing paste served as the control. Mean average surface roughness (Ra) values of each specimen group were analyzed using a 2-way analysis of variance, the Scheffé post-hoc test, and paired t test (alpha=.05) with the Bonferroni adjustment. After testing the polished acrylic resin surfaces were evaluated under a scanning electron microscope. RESULTS: The highest mean average surface roughness (Ra=2.86+/-0.8 microm to 3.99+/-1.31 microm) was measured for surfaces finished with a tungsten carbide bur. The lowest surface roughness values (Ra=0.02+/-0.01 microm) were determined for acrylic resin specimens polished with a lathe and polishing paste. The Ra values of resin specimens after polishing with chairside silicone polishing kits ranged from 0.05+/-0.0 microm to 0.35+/-0.05 microm. Mean average Ra values of specimens polished with a polishing cream alone (Ra=1.01+/-0.17 microm to 1.68+/-0.47 microm) were significantly higher (P<.05) than those obtained with other polishing systems tested, which was confirmed by scanning electron microscope images of acrylic resin surfaces. Significant differences in mean average surface roughness were found between autopolymerizing and injected heat-polymerizing resin specimens. In addition, scanning electron microscopy revealed increased porosity of autopolymerizing resin specimens. CONCLUSIONS: Conventional laboratory polishing was found to produce the smoothest surface of denture base acrylic resin. Chairside silicone polishing kits produced a significantly smoother surface of acrylic resin than specimens polished with a tungsten carbide bur. The presence of large pores was characteristic for the autopolymerizing resin material.     

Evaluation of the surface roughness of three heat-cured acrylic denture base resins with different conventional lathe polishing techniques: A comparative study

Purpose:

Surface roughness promotes adhesion and colonization of denture plaque. Therefore, it is important to know the effects of polishing and finishing on the surface roughness of various acrylic resin materials.

Objectives:

To evaluate and compare the effects of different conventional lathe polishing techniques on heat cured acrylic resins in producing surface roughness.

Materials and Methods:

Three different commercially available heat-cured acrylic resin materials namely DPI, Meliodent and Trevalon Hi were selected. 30 Specimens of each acrylic material (30 x 3 = 90, 10 x 60 x 2mm) were prepared and divided into 5 groups, each group consisted of 6 Nos. of specimens per material(6x3=18) and were grouped as Group A(unfinished), Group B (finished), Group C (Polishing Paste), Group D (Polishing Cake) and Group E (Pumice and Gold rouge). The resulted surface roughness (μm) was measured using Perthometer and observed under Scanning Electron Microscope. The values obtained were subjected statistical analyses.

Results:

Among the materials tested, better results were obtained with Trevalon Hi followed by Meliodent and DPI. Among the polishing methods used, superior results were obtained with universal polishing paste followed by polishing cake; Pumice and Gold rouge. Although Pumice and Gold rouge values produced greater roughness value, they were well within the threshold value of 0.2 mm.Key Words: Gold rouge, heat-cured acrylic resin, polishing cake, pumice, universal polishing paste     

Effect of finishing and polishing procedures on the surface roughness of packable composites

This study examined the average surface roughness (Ra, micron) of three packable composites and one hybrid composite cured against mylar, before and after treatment with a fine finishing diamond bur, a resin finisher followed by fine and extrafine polishing paste, two silicone-based finishing and polishing systems, fine and super-fine aluminum-oxide polishing disks, a silicon carbide-impregnated polishing brush and a surface-penetrating composite sealant. Additionally, the Ra was examined for one of the packable composites before and after treatment with a finishing carbide, prior to the finishing and polishing procedures detailed above. The finishing diamond significantly increased the Ra for all composites (ALERT, SureFil, Solitaire and Z-100). The finishing carbide used with SureFil (SureFil + C) also increased the Ra; however, it also produced surfaces up to 3.5x smoother when compared to SureFil surfaces finished with the diamond. Overall, Sof-Lex Contouring and Polishing Discs were able to produce the smoothest surfaces, followed by the Jiffy Composite Polishing Cups, the Enhance Composite Finishing & Polishing System/Prisma-Gloss Composite Polishing Paste, the Diacomp Intra-Oral Composite Polishers and the Jiffy Composite Polishing Brushes, respectively. The smoothest surfaces were produced using Z-100, followed by SureFil + C (carbide finishing bur), Solitaire, SureFil and ALERT, respectively. In general, Protect-It Composite Surface Sealant had little effect on the Ra, except with ALERT, where a slight increase in Ra was observed.     

Effects of a paste-free prophylaxis polishing cup and various prophylaxis polishing pastes on tooth enamel and restorative materials

The application of cleaning and polishing agents to a patient's dentition is a routine part of many dental practices. This study measured the surface roughness and surface gloss of tooth enamel, composite resin, and dental porcelain restorative materials when exposed to a paste-free prophylaxis polishing cup as well as a conventional prophylaxis polishing paste. Samples of human tooth enamel, a composite resin restorative material, and dental porcelain were prepared by a series of polishing papers to produce a flat smooth surface. The baseline average surface roughness (Ra) was measured using a contact stylus profilometer, and the surface gloss was measured with a glossmeter. The test samples were subjected to a standardized polishing routine using a paste-free prophylaxis polishing cup and a fine- or coarse-particle prophylaxis paste. Post-treatment surface roughness and gloss measurements were compared using a paired t statistical test. The conventional prophylaxis pastes increased surface roughness and decreased the gloss of the composite resin and tooth enamel test groups. The paste-free cups did not significantly affect the surface roughness of the enamel or the restorative materials. Dental porcelain surface roughness essentially was not affected by the application of paste-free cups and the fine and coarse pastes.     

Effect of prophylactic polishing protocols on the surface roughness of esthetic restorative materials

Many polishing protocols have been evaluated in vitro for their effect on the surface roughness of restorative materials. These results have been useful in establishing protocols for in vivo application. However, limited research has focused on the subsequent care and maintenance of esthetic restorations following their placement. This investigation evaluated the effect of five polishing protocols that could be implemented at recall on the surface roughness of five direct esthetic restorative materials. Specimens (n=25) measuring 8 mm diameter x 3 mm thick were fabricated in an acrylic mold using five light-cured resin-based materials (hybrid composite, microfilled composite, packable composite, compomer and resin-modified glass ionomer). After photopolymerization, all specimens were polished with Sof-Lex Disks to produce an initial (baseline) surface finish. All specimens were then polished with one of five prophylactic protocols (Butler medium paste, Butler coarse paste, OneGloss, SuperBuff or OneGloss & SuperBuff). The average surface roughness of each treated specimen was determined from three measurements with a profilometer (Surface 1). Next, all specimens were brushed 60,000 times at 1.5 Hz using a brush-head force of 2 N on a Manly V-8 cross-brushing machine in a 50:50 (w/w) slurry of toothpaste and water. The surface roughness of each specimen was measured after brushing (Surface 2) followed by re-polishing with one of five protocols, then final surface roughness values were determined (Surface 3). The data were analyzed using repeated measures ANOVA. Significant differences (p=0.05) in surface roughness were observed among restorative materials and polishing protocols. The microfilled and hybrid resin composite yielded significantly rougher surfaces than the other three materials following tooth brushing. Prophylactic polishing protocols can be used to restore a smooth surface on resin-based esthetic restorative materials following simulated tooth brushing.     

The effect of finishing and polishing procedures on the surface roughness of composite resin materials

AIMS: The aims of this study were to evaluate the effect of various finishing and polishing procedures on the surface roughness of six different composite resin materials (Artemis Enamel, TPH Spectrum, Filtek A-110, Filtek Supreme Enamel, Solitaire 2, and Filtek P-60) as well as to evaluate the effectiveness of the surface sealant application (BisCover) on the surface roughness after finishing and polishing procedures of tested composites. METHODS AND MATERIALS: Specimens (n=168) measuring 5 mm in diameter x 2 mm in thickness were fabricated in a plexiglass well covered with a Mylar strip using six composite resins. A control group of seven specimens of each material received no polishing after being cured under the Mylar strip. Twenty-one specimens for each composite were randomly divided among three finishing and polishing groups (n=7). Each group was polished using a different system: Carbide bur/Sof-Lex disc, Carbide bur/Enhance disc with polishing paste, and Carbide bur/Edenta composite finishing kit. The average surface roughness (Ra, microm) of the control and treated specimens were measured with the Mitutoyo Surftest-402 Surface Roughness tester. After a surface sealant (BisCover) was applied to all treated specimens, according to manufacturer's instructions, the average roughness (Ra) was measured again. Results were statistically analyzed using analysis of variance (ANOVA) and the post-hoc Scheffe's test at a p<0.05 significance level. RESULTS: Significant differences were found for the surface roughness (p<0.05) with interaction among composite resins and the finishing systems used (p<0.05). Enhance/Biscover finishing and polishing procedure surface was not significantly different from the Mylar strip surface groups (p>0.05). The Mylar strip group was not significantly different from the Sof-Lex/BisCover and Edenta/BisCover groups. The ranking of mean Ra values by materials was as follows: Filtek Supreme Enamel < Filtek A110 < TPH Spectrum < Artemis 相似文献   

The effect of prophylactic polishing pastes and toothbrushing on the surface roughness of resin composite materials in vitro

Polishing composite restorations at recall prophylaxis may affect their surface roughness. This investigation evaluated the effect of prophy paste on the surface roughness of a microfilled (Filtek A110) and a microhybrid (Filtek Z250) resin composite before and after simulated toothbrushing. Twenty, two-sided samples of both materials were fabricated in acrylic molds against a Mylar strip (baseline). Three roughness readings were recorded for each surface using a Surfanalyzer 5400 to determine the mean roughness. The samples were finished and polished with the Sof-Lex disk system and the surface roughness (Ra) was re-measured. Samples were randomly assigned and five surfaces for each material were polished with Nupro coarse, medium, fine or Clinpro prophy paste and the surface roughness measured again. All surfaces were brushed 60,000 times at 1.5Hz using a 2N brush-head force (Manly V-8 cross-brushing machine) in a 50:50 (w/w) slurry of toothpaste and water. The surface roughness was measured followed by the application of prophy paste as previously described and this final roughness recorded. Data were analyzed using repeated measures two-factor ANOVA with TUKEY HSD pairwise comparison as appropriate (alpha = 0.05). No significant difference in surface roughness was determined between the microfilled and microhybrid materials at baseline or disk treatment, yet significant differences were observed following brushing and/or prophy paste application. In conclusion, although baseline and disk treated surfaces were not significantly different in microfilled versus microhybrid composites, subsequent prophy paste application and/or simulated toothbrushing caused significant differences.     

Surface characteristics of posterior composites after polishing and toothbrushing

The surface characteristics of eight posterior and two anterior composite resins were studied by SEM and profilometric tracings. The materials included both chemically cured and light-cured resin systems. Two posterior materials were microfilled composites; the others were conventional or hybrid types. The anterior composites were of conventional and hybrid types. At various steps in the procedures the following polishing/brushing treatments were evaluated: 1) dry polishing with Sof-Iex discs followed by brushing with toothpaste; and 2) wet polishing with diamond pastes of increasing fineness, followed by brushing with toothpaste. The base line before the polishing/brushing procedures was obtained by wet polishing on silicon-carbide paper (4000 grit). All materials could be polished to a comparable smoothness by the Sof-lex discs, but this polishing procedure was associated with the development of an amorphous surface layer. Polishing with diamond pastes gave various results, with a 20-fold difference in surface roughness values from the smoothest to the roughest material. Toothbrushing after polishing with the Sof-lex system increased the surface roughness for all materials, but to various degrees. The two microfilled and four of the conventional posterior composites showed comparable surface roughness values, whereas two remaining posterior and the two anterior materials showed two to three times higher surface roughness values after toothbrushing. □ In vitro study; operative dentistry; profilometric investigation; scanning electron microscopy; surface roughness, composite resin     

Surface characteristics of posterior composites after polishing and toothbrushing

The surface characteristics of eight posterior and two anterior composite resins were studied by SEM and profilometric tracings. The materials included both chemically cured and light-cured resin systems. Two posterior materials were microfilled composites; the others were conventional or hybrid types. The anterior composites were of conventional and hybrid types. At various steps in the procedures the following polishing/brushing treatments were evaluated: 1) dry polishing with Sof-lex discs followed by brushing with toothpaste; and 2) wet polishing with diamond pastes of increasing fineness, followed by brushing with toothpaste. The base line before the polishing/brushing procedures was obtained by wet polishing on silicon-carbide paper (4000 grit). All materials could be polished to a comparable smoothness by the Sof-lex discs, but this polishing procedure was associated with the development of an amorphous surface layer. Polishing with diamond pastes gave various results, with a 20-fold difference in surface roughness values from the smoothest to the roughest material. Toothbrushing after polishing with the Sof-lex system increased the surface roughness for all materials, but to various degrees. The two microfilled and four of the conventional posterior composites showed comparable surface roughness values, whereas two remaining posterior and the two anterior materials showed two to three times higher surface roughness values after toothbrushing.     

烤瓷表面抛光和上釉对其表面粗糙度及细菌黏附的影响

目的比较不同抛光方法对烤瓷表面粗糙度的影响,以及不同粗糙度烤瓷表面对口腔变异链球菌黏附的影响。方法采用原子力显微镜测量不同抛光方法对瓷表面粗糙度的影响,并通过细菌实验观察不同粗糙度的瓷表面对细菌黏附的影响。结果用抛光膏抛光或者上釉后,瓷面平整且有光泽。无论是表面粗糙度还是表面黏附的细菌数,橡皮轮组都大于抛光膏组和上釉组（P<0.05）。结论建议调改过的瓷表面进行抛光膏抛光或上釉以恢复瓷表面的光滑度和减少口腔致龋菌的黏附。     

The effect of mechanical and chemical polishing techniques on the surface roughness of heat-polymerized and visible light-polymerized acrylic denture base resins

Objective

The purpose of this study was to compare the effects of mechanical polishing (MP) and chemical polishing (CP) on the average surface roughness (Ra) of heat-cured (HC) and light-cured (LC) denture base acrylic resins.

Methods

A total of 120 specimens (30 × 15 × 3 mm) were prepared from one HC and one LC acrylic resin. To remove nodules and gross surface irregularities, all specimens were finished with a lathe-mounted small acrylic bur and 360-grit sandpaper. Ten finished specimens of each acrylic resin were randomly assigned to each of six polishing techniques: Resilit High-luster Polishing Liquid (RHPL), Universal Polishing Paste, Abraso-star K50, pumice, Jet Seal Liquid, or Acrypoint. MP was performed with an automatic polishing machine for 2 min, under 50 rpm and 500 g of load. CP was performed by immersing the HC and LC specimens in preheated methyl methacrylate at 75 ± 1 °C for 10 s. The surface roughness of the acrylic resin specimens was measured with a contact profilometer. The Ra values were analyzed by two-way analysis of variance, post hoc Scheffe''s test, and paired t-test (p ⩽ 0.05). Polished and tested acrylic resin surfaces were evaluated by scanning electron microscopy.

Results

MP was more effective than CP. The smoothest surface was obtained with the use of the RHPL on the LC (0.05 ± 0.01 μm) or HC (0.07 ± 0.01 μm) acrylic resin. Two-way ANOVA showed a statistically significant difference between MP and CP.

Conclusions

MP produced the smoothest surface of denture base acrylic resin. The mean surface roughness values after MP and CP were not influenced by the type of acrylic resin.     

Effect of texture of polishing particle on the surface roughness of a cobalt-chromium alloy using a centrifugal shooting type polishing machine

In a previous report, we investigated the influence of the shooting angle of polishing particle on the surface roughness of a cobalt-chromium (Co-Cr) alloy using a centrifugal shooting type polishing machine. In the present work, we examined the effects of the texture of polishing particle and polishing time on the surface roughness of Co-Cr alloy cast specimens. Nine different textures of polishing particle were investigated with respect to core material and particle abrasiveness: three different elastic body cores (core A, hard chloroprene rubber; core B, soft chloroprene rubber; core C, natural rubber) and three different green carborundum powders as abrasives (#800, #3000, and #6000). Polishing was performed under a fixed shooting angle of 30 degrees for six different polishing times (1, 2, 3, 5, 7, and 10 minutes). Surface roughness (Ra, Sm) and cutting depth on the polished surface were measured after each polishing stage. Surface roughness was significantly improved within three minutes, particularly using a polishing particle with rough carborundum powder (#800 or #3000) and a heavy core (core A or core B). Cutting depth increased in proportion to polishing time and roughness of carborundum powder, and was least with core C. These results suggested that a polishing particle composed of core B and #3000 carborundum paste was superior for the intermediate polishing of a Co-Cr alloy, and that polishing time should be limited to within three minutes.     

Effect of bleaching versus repolishing on colour and surface topography of stained resin composite

Background: The aim of this study was to examine the effect of ozonated gel, carbamide peroxide bleaching agent and polishing paste on the colour and surface topography of stained resin composite. Methods: Ninety disc‐shaped resin composite specimens were used in this study. They were randomly divided into three groups of 30 specimens each according to the immersion solutions used, i.e., tea, cola or artificial saliva. Each group was further subdivided into three equal subgroups (n = 10) according to the type of whitening treatment applied; 30% carbamide peroxide, ozonated KY gel or polishing paste. Colour and surface roughness was measured at baseline, after immersion, also following whitening procedures by using a stereomicroscope. The results were recorded, tabulated and statistically analysed. Results: The colour values of artificial saliva displayed the highest statistically significant mean colour difference compared to cola and tea. However, there was no statistically significant difference in surface roughness. Also, a superior whitening effect was demonstrated with ozonated gel. Ozonated gel showed statistically significant lowest roughness compared to both carbamide peroxide and polishing paste. Conclusions: Immersion solutions have a positive influence on the colour of resin composite. Also, ozonated gel is an efficient bleaching agent with the least adverse effect on surface roughness.     

The surface finish of the new microfill restorative materials

Surface smoothness is an important requirement for restorative materials. Recently, restorative materials claimed to be inherently smooth in surface characteristics have been developed. Matrix-formed and finished surfaces of five new microfill restorative materials were compared with two composite resins, an acrylic resin and a silicate cement by means of scanning electron microscopy. The results of this investigation indicated that the matrix-formed surfaces of all the restorative materials studied were not altogether perfect. Polishing using sandpaper and cuttlefish discs produced a very smooth surface finish in the new microfill restorative materials, Estic microfill, Estilux microfill, Isopast, Isolux and Silar which was comparable to that of the acrylic resin, Sevriton. The composite resins, Adaptic and Estilux exhibited the worst surface finish and the silicate cement, Bio-trey was intermediate. Finishing, using other finer polishing devices on four of the materials produced a further improvement in the surface finish.     

不同抛光系统对纳米树脂表面粗糙度和菌斑黏附的影响

目的研究比较5种抛光系统处理纳米树脂后的表面粗糙度及其对细菌黏附程度的影响。 方法Filtek Z350 XT纳米树脂制作54个样本,随机平均均分为6组,每组9个。其中5组为实验组（抛光组）分别用OptiDisc、HiLuster^Plus、Sof-Lex、Super-snap以及Composite Polishing Kit CA0310等5种抛光系统修整、抛光,另1组不做抛光处理为对照组。激光共聚焦扫描显微镜测定样本表面粗糙度（Ra）。将上述样本与变异链球菌于体外混合培养24 h,测定其表面细菌黏附量。采用单因素方差（One-Way ANOVA）分析方法对样本表面粗糙度和生物膜菌落计数结果进行统计学分析。 结果实验组中HiLuster^Plus组的Ra值最低平均（0.196 ± 0.02）μm,与Composite Polishing Kit CA0310组相比差异有统计学意义（P= 0.016）;其余各实验组间Ra值无显著差异,均能达到较低的粗糙度值。5个实验组的细菌黏附量均低于对照组,差异有统计学意义（P<0.05）;5个实验组间的细菌黏附量差异无统计学意义（P>0.05）。 结论HiLuster^Plus抛光系统处理纳米树脂可获得较低的表面粗糙度。系统抛光可明显降低纳米树脂材料表面细菌黏附量。     

Effect of Polishing Technique and Brushing on Surface Roughness of Acrylic Resins

Purpose: This study evaluated the abrasion resistance of acrylic resin to routine dental brushing procedures using different dentifrices after the resin surface had been chemically or mechanically polished.
Materials and Methods: Eighty specimens were prepared using heat-polymerizing (HP) and autopolymerizing (AP) acrylic resin, and immediately submitted to grinding with abrasive stones and disks. The specimens were divided into two groups: the first group was mechanically polished (MP) using pumice slurry, and the second group was chemically polished (CP) using heated monomer. After polishing, the specimens were submitted to 30,000 brushing cycles. Surface roughness was measured after polishing and brushing procedures, using a Surfcorder SE 1700 rugosimeter. Data were statistically analyzed by ANOVA (α= 0.05).
Results: There were significant differences in surface roughness between polishing with MP and CP ( p < 0.05). Significant differences in surface roughness were also found between brushing with MFP dentifrice and Tartar Control dentifrice ( p < 0.05).
Conclusion: MP produced smoother surfaces than CP, and surface roughness as a result of polishing technique was not influenced by acrylic resin type. Even though MP resulted in smoother surfaces initially, subjecting the acrylic resin to dentifrice brushing negated this advantage.     

Effect of polishing systems on the surface roughness of microhybrid composites

Purpose : This study was undertaken to examine the effect of three different polishing systems on surface roughness of five newly developed resin composites.
Materials and Methods : Three microhybrid composites (Point 4™, Kerr, Orange, CA; Esthet-X™, Dentsply/Caulk, Milford, DE; Vitalescence®, Ultradent, South Jordan, UT, USA), one microfilled composite (Renamel Microfill®, Cosmedent, Chicago, IL, USA), and one experimental micro-hybrid composite (FZB, Ivoclar Vivadent, Schaan, Liechtenstein) were light cured with a Mylar strip. Fifteen specimens of each composite (6 mm in diameter and 3 mm in depth) were fabricated and randomly assigned to three groups. Specimens in each group were finished with a carbide bur (16 fluted) and three polishing systems (Astropol®, Ivoclar Vivadent; Diagloss®, Axis Dental, Irving, TX, USA; Sof-Lex™, 3M, ESPE, St. Paul, MN, USA). The average surface roughness (Ra) and the mean peak spacing (Sm) were measured with a surface profilometer after polishing. Five tracings at different locations on each specimen were made. Data were analyzed by analysis of variance.
Results : For Astropol, Ra ranged from 0.10 to 0.15 um and Sm ranged from 24 to 40 um for the five composites; for Diagloss, Ra ranged from 0.24 to 0.34 um and Sm from 38 to 74 urn; for Sof-Lex, Ra ranged from 0.06 to 0.10 um and Sm ranged from 16 to 22 um. Significant differences between materials and polishing systems were observed. Polishing systems had the most important role in determining the surface roughness of resin composites.
CLINICAL SIGNIFICANCE
Of the polished systems tested, Sof-Lex discs provided the lowest roughness for polishing microfilled and microhybrid composites, and the microfilied resin composite showed the lowest roughness.     

Surface Roughness of Denture Base Acrylic Resins After Processing and After Polishing

PURPOSE: Circumstances exist in which the need to adjust denture base acrylic resins is necessary. This process obviously alters the surface of the polished denture base. The purpose of this study was to compare the effects of three chairside polishing kits and conventional polishing on four denture acrylic resins. MATERIALS AND METHODS: Twenty-four 30 x 30 x 2 mm acrylic resin specimens were fabricated with each of four acrylic resins: autopolymerizing, heat processed, injection molded, and microwaveable. One side was polished conventionally with pumice and polishing compound. The other side was polished with one of three chairside polishing kits: Axis, Brasseler, and Shofu. Each side was evaluated by a Dektak 8 Programmable Stylus Profiler to determine the surface roughness (Ra). RESULTS: One-way analysis of variance (ANOVA) revealed that: (1) There was no significant difference in the time it took to polish the specimens with the chairside polishing kits (F=2.118, p=0.14). (2) There was a significant difference in surface roughness between the acrylic resins before any polishing, with the injection-molded and heat-processed being less rough than the autopolymerizing (F=4.588, p=0.005). (3) There was a significant difference in surface roughness between the acrylic resins when conventionally polished, with the injection-molded and microwavable being less rough than the autopolymerizing (F=4.503, p=0.005). Factorial ANOVA revealed that: (1) There was no significant difference in the surface roughness among the chairside polishing kits (F=1.209, p=0.30). (2) There was a significant difference between the acrylic resins, with the heat-processed, injection-molded, and microwaveable being significantly less rough than the autopolymerizing (F=6.610, p=0.0001). (3) There was no significant interaction between the acrylic resins and the chairside polishing kit in the amount of surface roughness (F=1.728, p=0.12). An independent t-test revealed that conventional polishing was significantly smoother than polishing with the chairside polishing kits (t=3.847, p=0.0001). CONCLUSIONS: It was concluded that time was not a factor in using any of the chairside polishing kits. It is recommended that conventional polishing be used after adjustments to the cameo surface of denture acrylic resin.     

Porcelain refinishing with two different polishing systems after orthodontic debonding

OBJECTIVE: To compare the effects of two polishing systems on the surface roughness of three types of porcelain after orthodontic debonding. MATERIALS AND METHODS: A total of 90 porcelain discs were fabricated from feldspathic (n = 30), leucite-based (n = 30) or lithia disilicate-based (n = 30) ceramics. Ten samples in each group served as the control and received no surface treatment. The remaining 60 samples in three of the porcelain groups were bonded with lower incisor brackets and debonded using a testing machine in shear mode at a rate of 1 mm/minute crosshead speed. After debonding, the remaining adhesive resin was removed with a tungsten carbide bur. Then, two experimental subgroups (10 each) in each porcelain group were treated as follows: in the first subgroup, porcelain polishing wheel and polishing paste were applied, whereas in the second, polishing was performed using a series of Sof-Lex discs. The average surface roughness (Ra) of the all samples was evaluated using SPM/AFM (surface probe microscope/atomic force microscope). Data were statistically analyzed by analysis of variance for each porcelain material and polishing method. RESULTS: The polishing techniques affected surface roughness significantly. There were significant differences between the groups; higher Ra values were obtained with the use of porcelain polishing wheel and polishing paste (P < .001). CONCLUSION: The application of Sof-Lex discs can produce smoother porcelain surfaces than porcelain polishing wheel and polishing paste.     

Surface roughness of auto polymerized acrylic resin according to different manipulation and polishing methods: an in situ evaluation

OBJECTIVE: To test the hypothesis that no differences exists in the in situ level of surface roughness of an auto polymerized acrylic resin irrespective of the method of manipulation and polishing. MATERIALS AND METHODS: Forty volunteers received the test specimens. Surface roughness was evaluated using a rugosimeter. Samples of auto polymerized acrylic resin were submitted to two methods of manipulation--mass and addition--as well as to two types of polishing--mechanical and chemical. Four test groups were designated according to manipulation and polishing techniques: mass-mechanical, mass-chemical, addition-mechanical, and addition-chemical. Five measures of surface roughness were taken from each sample and average surface roughness (Ra) was determined before and 20 days after the samples were worn by the volunteers. The data obtained were analyzed by the Student's t-test for paired samples as well as by analysis of variance. RESULTS: Significant differences in Ra were found between mechanical and chemical polishing. Surface roughness was not influenced by manipulation techniques. Mechanical polishing presented the lowest values of Ra. There was a significant increase in surface roughness after volunteers wore the specimens for 20 days. CONCLUSIONS: The hypothesis is rejected. There were differences on the surface roughness according to the different methods of manipulation and polishing used, but high values of surface roughness were found for all groups. Mechanical polishing showed the lowest values of surface roughness and thus should be preferred.