Although ultrasound is used routinely on patients, there are few hazards associated with its use. The ultrasonic scaler may result in potential hazards to both the patient and the clinical operator of the equipment. The ultrasonic scaler is a useful instrument in the field of periodontology, but considerations need to be made when utilizing it in the clinical situation
Thermal effects on pulp
A temperature rise in the tooth caused by heating can cause damage to the pulp and dentine. Heating of the [pulp should be avoided as it can cause irreversible pulpitis. The use of ultrasonic scaler will produce an increase in temperature, and this heat may be due to friction between scaler and tooth. The studies conclude that powered scaling should not be considered without irrigation and the flow rate should be in the region of at least 20-30 ml\min.
Thermal effects on periodontal tissues
Early workers demonstrated that ultrasonic scaling causes no injury to the periodontal membrane, alveolar bone or the gingiva. Further histological examination of tissues immediately after ultrasonic scaling showed superficial tissue coagulation. It was found that curettage with ultrasonic instruments resulted in quicker healing
Vibrating a wire at an ultrasonic frequency will potentially damage erythrocytes, leucocytes, platelets. Platelets are sensitive to shear stresses, and such forces are produced by the occurrence of acoustic micro streaming around an ultrasonically oscillating wire. Pulpal thrombosis from dental ultrasonic scaling is still a possibility. If the formation of thrombus occurs in vessels supplying the tooth pulp, it could result in tooth death during ultrasonic scaling
Vibration to operator
It is known that the large amplitudes produced by pneumatic drills causes ‘white finger’, a disruption in the blood flow to the fingers, caused by vibrations passed from the drill through to the hand. Some persons experienced symptoms like tingling, numbness and reduced manipulative dexterity although none of the persons had neurological symptoms in their non-dominant hand. Long time exposure to ultrasonic scalers had a high frequency of neurological symptoms that was especially prevalent in their dominant hand. However it was concluded that these neurological symptoms were not due to a vibrating hand piece since the exposed second and unexposed fifth fingers were similarly affected. It was found that the vibrations could produce a reduction in strength and tactile sensitivity and performance due to disruption of blood and nerve supplies to the fingers.
When using the ultrasonic scaler a fine aerosol is produced, this may spread pathogenic microorganisms. This aerosol production could be hazardous to health. Aerosol containing micro9organisms can be reduced by 99% during ultrasonic scaling, if air is blown down from the ceilings and through vents in the wall base which are then filtered to re- enter the cycle. Aerosol can be greatly reduced if t6he operator uses a high filtering properly fitted face mask. The use of a pre procedural rinse using an antiseptic mouth wash reduces the microbial content of aerosols during ultrasonic scaling. If ultrasonic scalers are used subgingivally, the aerosol produced will contain blood contamination.
Ultrasonic scalers may be a potential hazard to the auditory system of both clinicians and patients. Damage to operator hearing is possible through the ultrasonic scaler. FOR the patient damage can occur through the transmission of ultrasound through tooth contact to the inner ear via the bones of the skull. This later hazard is a possibility during scaling of the molar teeth. Tinnitus is an early sign of hearing loss and may occur following ultrasonic scaling. A small number of dentists have experienced tinnitus or numbness of the ears after the prolonged use of ultrasonic scalers, which indicates a small potential risk to hearing.
The proximity of magnetic, electrical or electromagnetic fields can affect the operator of cardiac pace makers. Recent work investigating the magnetostrictive scaler stated that interference can be caused if the pacemaker pacing lead comes within 37.5 cm of the scaler.