| PrefaceDental ceramics has been widely used to provide esthetic restoration for dental patients because of the merits such as its vivid colors, high strength, no harm to human body, resistant to wear, etc. The i-deal is to restore tooth loss by using materials those have no negative influences on the human enamel, and the wear is as close as possible to the lost teeth. Essential difference of the wear loss of prosthetic materials, and the dental porcelain when contact with the natural teeth may result to the dysfunction of oral - maxillary system. Manufacturers claim that these materials can substitute for the traditional restoration. However, there are more studies reported that the traditional restorative materials is harmful to the natural enamel, and scholars are more concerned about the use of the ceramics. In 1998 the proficients discussed the promise of the nanometers porcelain and agreed to think it is an impending problem to improve the property of the ceramics.In order to look for a better restorative material, which has the close wear to the enamel and does no harm to the enamel, scholars have made a lot of researches. Now various materials have been introduced to the dental field and the physical and chemical characters have been improved, the strength is reinforced.This laboratory study was designed to evaluated the wear loss ofthe traditional ceramics (vita and sofu) and the mixture of the namome-ter powder with the traditional vita ceramics and determined the value of the wear, which provide clinical proof for the use of ceramics.Materials and methodsRing/block, wear testing machine was used under abrasive liquid. Fifteen teeth enamel were prepared as a control group, it was restored to 3 3mm, the thickness of the enamel was more than 1mm, the length is as long as possible. The ceramics vita (made in Germany) , Vita - 1 (the mixture of 1 vol. nanometer materials with 8vol vita) , Vita -2 (the mixture of 1 vol of namometer powder with vita) , sofu, the namometer materials is 50nmSi02. All the ceramics were fused in the ceramics fusing machine according to the manufacturers, the size is 3 x3 x 10mm, the specimen were fixed in the plastic so as to be clamped by the machine. All specimens need cleaning in the supersonic machine. The stress is 1.5, 3.0, 4. 5Kg. The lower specimen was made of 18 - 8 steel which is 37. 5 in diameter and 10mm in thickness. The wear loss of materials of the ceramics and enamel were tested by electric balance (tianguang factory, shanghai). The loss of materials was calculated by the v = m/p. The volumes of the specimen were analyzed by ANOVA and the difference was compared. The surfaces of the specimens of vita and its mixtures were scanned by SEM.ResultThe mean of the wear of every specimen were compared by different stress. It revealed that there was significant difference between the groups. The vita has the most wear resistance, and the Sofu was the least.When the stress was 1.5Kg, the difference is significant betweenvita and enamel. Vita -1, vita - 2 has the wear of equal loss to that ofenamel ( p > 0.05 ) . The group vita - 1 has lost more than vita - 2 ( p<0.05). So to think that the nanometer powder changed the wearproperty.When the stress was 3, OKg, the vita group has less loss than others. But Vita - 1 and vita - 2 had the same wear as enamel ( p > 0. 05). So we can say that the adding of the nanometer powder affected the wear. But the effect of its volume is not significant.When the stress was 4. 5Kg, Vita - 1 has ecpial wear loss to the enamel ( p > 0.05 ) . But the wear resistance of vita - 2 was lower than enamel ( p < 0.05 ) , and the volume is not larger than that of the wear of 3. 0kg.As for the photos of the SEM, vita which had many projections was rougher than vita - 1 whose grooves were filled with different sized fillings. And vita -2 had more grooves and fracture than vita - 1. The surface of the wear of Vita - 1 is smoother than other ceramics.DiscussionWear is the loss of the body when... |
