The relationship between design and cutting efficiency of dental burs.

R ECENTLY several articles have been presented which have described in some degree the heat generation, the vibration characteristics, and the cutting efficiency of various rotating dental instruments.1-6 These reports have indicated that the operating characteristics of rotating instruments are interrelated to some degree and are modified by the speed of operation and the force applied to the instrument. The previous reports have given little attention to the matter of instrument design as it is related to the cutting efficiency and functional life of the dental bur. The cutting efficiency of a rotating dental instrument may be considered the ability of that instrument to remove a maximum amount of tooth tissue with a minimum of effort and time involved in the operation. Closely related to the cutting efficiency characteristic of the instrument is its functional life, which may be considered the time interval through which the instrument may be used effectively to cut tooth tissue. Both the efficiency and the functional life of the rotating instrument are no doubt interrelated, and both characteristics are of significance to the practitioner in his effort to shape the cavity with a minimum of time and effort. It was the purpose of this study to determine some of the factors of design which influence the relative cutting efficiency and the functional life of the steel and carbide dental bur. Because of the manner in which the study was conducted, it has been to some degree a survey of the products available to the profession. This was not, however, the primary purpose of the investigation. It has been observed empirically by many clinical operators that there is a variation in the behavior of different products with respect to both the cutting efficiency characteristics and the relative life of the cutting instrument. It was the basic purpose of this study, therefore, to determine if there were some fundamental reasons of design which might account for this observed difference in operating behavior. Some of these differences are described in this report.