A Study on the Removal of Dental Calculi by the Use of Ultrasonic Scaler

Abstract

The removal of dental calculi is one of the basic concepta in the maintenance of proper oral health and is fundamental in every form of dental treatment, being particularly important in the prevention and treatment of periodontal diseases. Because of the heavy clinical load of the dentist today, however, coupled with an increasing number of patients requiring the dental care, the removal of dental calculi is not always carried out in an adequate manner.On the other hand, recent efforts have introduced various kinds of mechanical instruments for scaling to replace the manual instruments hitherto in use. More efficient scaling is expected from the use of these mechanical means.Of the mechanical scaling instruments, one which uses utrasonic waves has been extensively studied not only abroad (Zinner, Johnson, Goldman among others), but also in Japan (Nakashizu, Konishi, Imagawa among others). Although these investigators confirmed the usefulness of an ultrasonic scaler, they pointed out the main disadvantage of this instrument in its possible injury to the cementum.For purposes of examining the merits and demerits of this scaling instrument comparatively, the author has undertaken the present study consisting of the following 5 items: i) comparison of scaling time between the ultrasonic and hand scalers owing to the difference of the deposition of calculi and their hardness, ii) the incidence of wounds on the dental surface and its relation to the polishing; iii) the subjective feelings of the patients, pain and bleeding associated with the scaling operation; iv) examinations of the vital reaction in terms of the number of heart beats, pulse and galvanic skin reflex (G.S.R.); and v) comprehensive evaluation of the scaling by the ultrasonic device based on these findings.The following are the salient conclusions arrived at as the result of the aforementioned study.1. The amount of calcular deposition and hardness were determined by the author as preliminary step. For the determination, recourse was had to visual inspection and palpation by means of an explorer.With a total sample of 148 males and females, the lower 3 anteriors on the right and left were respectively subjected to scaling by a hand scaler and an ultrasonic scaler, this combination being alternated from subject to subject. The comparison of scaling time revealed that the same operation with a hand scaler (461.8 seconds) took less than half as long with ultrasonic device (216.8 seconds). This difference was also true as regards the amount of calcular deposition and hardness. When there was a larger deposition with a corresponding increase in the hardness, the ultrasonic device was found to be far more effective.2. Since the calculi are mechanically removed, some kind of wounds are apt to be inflicated on the dental surface.The greater portion of calcular deposition takes place on the cervical region and extends to the cementum boundaries. For this reason, wounds on the cementum cannot be ignored. There are known several interpretations of the problem, but, within the scope of the present stundy, wounds were detected in both of these regions. The incidence of wounds was smaller in the case of the ultrasonic scaler as compared with the hand scaler. It was also established that, by paying sufficient attention to the operating angle of a scaler tip, it was possible to prevent the incidence of wounds on the dental surface to a large extent.In terms of electric current output, low output Produced fever wounds than hign output.