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Purpose:The objective of this study was to compare the surface roughness according to polishing process in conventional laboratory techniques used for polishing three different acrylic denture base resins.Materials and methods: Specimen preparation and surface polishing procedures were conducted to manufacturer's recommendation with three heat-polymerized denture base resins. Surface roughness and gloss were measured by a contact type tester and a LED gloss checker using thickness 2 mm and diameter 10 mm. There were five specimens for each acrylic resin material and polishing procedures.Mean average surface roughness (Ra) values of each specimen group were analyzed using a one-way ANOVA analysis of variance and Scheffe's post hoc test. Surfaces after surface roughness and gloss testing according to each polishing process were evaluated under a stereoscopic microscope.Results: The highest mean average surface roughness was measured(Ra=2.43 0.47) for surfaces finished with a denture tungsten carbide bur in Triplex. The lowest surface roughness values (Ra=0.11 0.07) were determined in Vertex polished with a lathe. In addition, all materials revealed that surface roughness determined highly in HP1 and HP2 than other procedures.All correlation between surface roughness and gloss showed highly with three heat-polymerized resins. Specially, topmost correlation revealed than other material in Triplex. Significant differences in mean average surface roughness were found between polishing process used high speed lathe and low speed hand-piece.Conclusion: Laboratory polishing used to high speed was found to produce the smoothest surface of heatpolymerized denture base acrylic resin. Therefore, we recommended that high polishing process need to get smooth surface.[Abstract] 205

The purpose of the study is to investigate the need for the retirement attitude of korean dental technicians. Retirement attitude is important in the study of retirement planning.Methods: A total of 778 dental technicians were selected by proportional stratified by region compared to extraction sampling from a list of korea dental technician association in 2012. The final sample size was 386. Questionnaires consisted of 10 questions general characteristics, 9 questions for the current life satisfaction and retirement preparation, and 4 questions about retirement attitudes on a Likert 5 scale. Cronbach's alpha was 0.812 in the study. All statistical analyzed were performed using SPSS 14.0(Statistical Packages for Social Science Ver. 14.0. Chicago, IL, USA).Results: An average of 3.01 0.8 dental technicians were retirement attitude. To affect retirement attitude marital status, age, subjective health status, assets satisfaction, job type, job satisfaction and the economic outlook was living after retirement (p <0.05). Conclusion:This study suggested that retirement attitude of korean dental technicians was very important and the preparation must be connected with the social welfare policy.