The Comparative Investigation On The Wear Ability Of Several Normal Crown Prosthetic Materials

All kinds of clinical causes may result in different degrees of wear of human tooth and artificial crown prosthesis . Serious wear of natural teeth do great harm to tooth , periodontal tissue , oro-maxillofacial system, muscular tissue, temporomandibular joint . As a result, dentin hypersensitiveness , pulpitis , periodontitis, food impaction and dysfunction of TMJ may appear . The different wear abilities between enamel and prosthetic materials constitute one of the most important causes. On the one hand, over-abrasion of enamel may appear when the wear ability of prosthetic materials is higher than that of enamel. On the other hand, over-abrasion of the crown prosthsis may appear when the wear ability of the prosthetic material is lower than that of enamel. In both conditions, the results could not meet the restoration needs. Ideal crown prosthetic materials should be of the same or similar wear ability to the enamel of tooth. The wear ability of eight kinds of artificial dental prosthetic material and natual enamel of human were tested and the comparative investigation were designed. The wear abilities of above prosthetic material were evaluated taking the associated factors into account and the results would provided theoretical proof in choosing the right material in clinical point of view.Method:The C's rigidity of eight normal crown prosthetic material including five metal material and three ceramic material and human enamel were choosen for test. The quantity reduction of the materials were tested by wearing test machine adopting suface to surface mode. The wear trace of the wear surface were investigated by SEM.Results :1. The percentage of average volume reduction of the sample by the surface to surface mode : 55% gold alloy > natural enamel >pure titanium> nanometer composite ceramic > low temperature ceramic> Vata ceramic> titanium alloy> nickel-chromium alloy > hard cobalt-chromium alloy2. The percentage of average volume reduction of talcum ceramic : hard cobalt-chromium alloy> nickel-chromium alloy> titanium alloy> Vata ceramic> low temperature ceramic> pure titanium> natural enamel> 55% gold alloy3. The value of microscopic C's rigidity of the sample surface: nanometer composite ceramic> talcum ceramic body> hard cobalt-chromium alloy> Vata ceramic> low temperature ceramic> nickel-chromium alloy> natural enamel> titanium alloy> pure titanium>55% gold alloy Conclusion:1. The pure titanium is of the most similar wear ability to the natural enamel.2. Rigidity have some extent of relationship with the ability to resist wear of metal materials .Meanwhile hardness is not the deciding factor influencing the wear ability of ceramic materials.3. The wear ability of nanometer composite ceramic is more similar to natural enamel than normal ceramic materials and metal materials.4. The microscopic structure of prosthetic materials is an important factor influencing the wear ability.