超音波牙鑽表面特性對牙釉質磨削效率之研究

Abstract

超音波技術使用在牙科醫療上優點有軟硬組織辨識功能，病人忍受度較高以及提供醫師較好的手術視野，但目前超音波牙鑽尚無法有效切割牙釉質(enamel)，且容易磨損及成本較高，因此在臨床上並未被廣泛使用。故本研究的目標為提出超音波牙鑽的最佳表面設計參數，有效提升對牙釉質之磨削效率。 本研究先分析現有超音波牙鑽的磨耗行為、黏屑問題對磨削效率的影響。結果顯示鑽石顆粒的磨耗是以破裂為主，輕微磨耗時磨削效率上升，嚴重磨耗則造成效率下降。使用過程中，牙鑽黏屑現象會降低牙鑽的磨削效率。 接著使用田口式實驗設計法及變異數分析法來探討表面因子對磨削效率的影響性。結果顯示粒度不會對磨削效率造成明顯的影響，而晶形、單位面積顆粒數量及突出量都有顯著的影響，突出量影響程度最大，單位面積顆粒數量次之，接著是晶形。而球狀超音波牙鑽最佳參數組合為使用粒度100/120、突出量75μm、晶形較破碎以及單位面積顆粒數量為每1mm2含有約45顆的鑽石顆粒，能有效提升磨削效率，國產UL3A由0.019 mm3/s變為0.064 mm3/s，可提升約3.4倍，而國外EX1由0.04 mm3/s變為0.126 mm3/s，可提升約3.2倍。

Ultrasonic system has following advantages: 1. Safety; 2. Less fear and better acceptance by patients; 3. Not blocking the view and high precision cuts. However, when it is used for dental cutting, deficiencies such as the inefficient removal of enamel, slow cutting, and cost have worked against it acceptance by dentists. The aim of this study was to increase enamel removal rate of dental diamond burs with ultrasonic system. Clogging of the spaces between the particles by debris may interfere with effective removal rate, because this partially blocks the penetration of the abrasive particles into the substrate. Most of worn particles of diamond burs are fractured crystals, and the surface wear influence enamel removal rate. The Taguchi method was used to find the better surface characteristics of dental diamond burs with ultrasonic system. The highest enamel removal rate was found in this experiment for spherical bur with 100 to 120 diamond particle mesh size, 75 μm protrusion, higher degree of surface roughness on crystal facets, and 45 particles per unit bur surface area. The enamel removal rate of UL3A with new characteristics reached 0.064 mm3/s, which was 3.4 times larger than the original UL3A burs, whereas EX1 with new characteristics reached 0.126 mm3/s, which was 3.2 times larger than the original EX1 burs.