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.

[1]  R. Loney,et al.  Finishing and polishing of a poly (fluoroalkoxyphosphazene) resilient denture liner. , 1994, The International journal of prosthodontics.

[2]  D C Watts,et al.  Comparison of two stylus methods for measuring surface texture. , 1999, Dental materials : official publication of the Academy of Dental Materials.

[3]  M. Quirynen,et al.  The influence of titanium abutment surface roughness on plaque accumulation and gingivitis: short-term observations. , 1996, The International journal of oral & maxillofacial implants.

[4]  J. Heath,et al.  Surface roughness of restorations , 1976, British Dental Journal.

[5]  M Quirynen,et al.  The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man. A review of the literature. , 2005 .

[6]  T. Watson,et al.  The effects of surface machining on heat cured acrylic resin and two soft denture base materials: a scanning electron microscope and confocal microscope evaluation. , 1997, The Journal of prosthetic dentistry.

[7]  D. Radford,et al.  Chairside polishing of heat-cured acrylic resin: an SEM and EDA study. , 2003, The International journal of prosthodontics.

[8]  M. Quirynen,et al.  The influence of abutment surface roughness on plaque accumulation and peri-implant mucositis. , 1996, Clinical oral implants research.

[9]  M. Ulusoy,et al.  An evaluation of polishing techniques on surface roughness of acrylic resins. , 1986, The Journal of prosthetic dentistry (Print).

[10]  E. Bayramlı,et al.  The effect of acquired salivary pellicle on the surface free energy and wettability of different denture base materials. , 2001, Journal of dentistry.

[11]  S. Challacombe,et al.  Denture plaque and adherence of Candida albicans to denture-base materials in vivo and in vitro. , 1999, Critical reviews in oral biology and medicine : an official publication of the American Association of Oral Biologists.

[12]  M. Hannig.  Transmission electron microscopy of early plaque formation on dental materials in vivo. , 1999, European journal of oral sciences.

[13]  P Lambrechts,et al.  Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. , 1997, Dental materials : official publication of the Academy of Dental Materials.

[14]  J. Verran,et al.  Retention of Candida albicans on acrylic resin and silicone of different surface topography. , 1997, The Journal of prosthetic dentistry.

[15]  E. Theilade,et al.  Predominant cultivable microflora of plaque on removable dentures in patients with denture-induced stomatitis. , 1988, Oral microbiology and immunology.

[16]  P. Monsénégo.  Presence of microorganisms on the fitting denture complete surface: study 'in vivo'. , 2000, Journal of oral rehabilitation.

[17]  H. Nikawa,et al.  Denture plaque--past and recent concerns. , 1998, Journal of dentistry.

[18]  D van Steenberghe,et al.  The influence of surface free energy and surface roughness on early plaque formation. An in vivo study in man. , 1990, Journal of clinical periodontology.

[19]  M. Wilson,et al.  The effects of surface roughness and type of denture acrylic on biofilm formation by Streptococcus oralis in a constant depth film fermentor , 2001, Journal of applied microbiology.

[20]  S. Yannikakis,et al.  Roughness of denture materials: a comparative study. , 2000, The International journal of prosthodontics.

[21]  S. Challacombe,et al.  Adherence of Candida albicans to denture-base materials with different surface finishes. , 1998, Journal of dentistry.

[22]  K. Yamamoto,et al.  In vitro adherence of microorganisms to denture base resin with different surface texture. , 1990, Dental materials journal.