Mohamed N. Abass, Enas Fathelbab And Yasser F. Hussein,

ABSTRACT


Purpose: The Aim Of This In Vitro Study Was To Evaluate The Effect Of High Concentrated Light Activated Bleaching Agent On Surface Roughness And Wear Resistance Of Conventionally And CAD � CAM Fabricated Feldspathic Ceramic Restorations.

Materials and Methods: A Total Of Forty Cubic Samples Were Prepared. Samples Were Divided Into Two Equal Groups (20 Samples Each) According To Type Of Tested Ceramic. Each Group Was Subdivided Into Two Subgroups (10 Samples Each) According To Type Of Testing. All Samples Subjected To 35% HP (BEYOND Max5�) Light Activated Bleaching Gel. Surface Roughness Measurements Were Recorded For All Tested Samples Before Any Treatment To Provide Baseline Values As A Control Group. A Micro-saw Was Used To Cut Blocks (VITABLOCS�MarkII) Into Standardized Cubes. A Specially Designed Acrylic Mold Was Used For Construction Of Samples To Standardize The Shape And Dimensions Of The Cubic Samples. Predetermined Proportions Of (VITAVM�7) Dentin Powder And Build Up Liquid Was Used According To The Manufacturer�s Instructions. Twenty Teeth Caries And Crack Free (premolars) Were Collected, A Micro-saw Used To Cut Teeth Into Equal Half In Vertical Section. All Samples Stored In Distilled Water Before And After Bleaching. Samples Of Both Types Of Ceramics Were Photographed Before And After Bleaching By USB Digital Microscope With A Built-in Camera For Surface Roughness Measurements. Wear Resistance Was Assessed By Weight Loss Of Tested Samples. Weight Was Measured By Electronic Analytical Balance. Chewing Simulator Device Was Used To Simulate The Vertical And Horizontal Movements In The Oral Cavity.

Results: Results Showed That There Was No Statistically Significant Difference Between Mean Values Of Ra Of The Two Tested Ceramic Types. However, Both Tested Materials Showed Statistically Significant Lower Mean Values Of Ra Than Tooth Structure But There Was No Statistically Significant Difference Between Changes In Surface Roughness (?Ra) In The Three Groups Either Before Or After Bleaching. There Was No Statistically Significant Difference Between Mean Values Of Wear Of The Two Ceramic Types. The Wear Ranged (0.49 To 72) The Maximum Wear Was Found In (VM 7) While The Lowest Was In Tooth Structure. That Was Interesting To Find That The Wear Of Tooth Structure (0.42) Which Is Significantly Less Than Two Types Of Dental Ceramics.

Conclusions: High Concentrated Light Activated Bleaching Agents Have No Effect On Surface Roughness And Wear Resistance Of Dental Ceramic. Both Types Of Dental Ceramics (fine Structure Feldspathic Porcelain) Have Mild Abrasive Effect On Antagonist Natural Teeth. Industry Manufacture Dental Ceramics Showed More Wear Resistance Than Conventional One.