Changes

==Powered Instruments==

==Powered Instruments==

'''Mechanical or powered scalers''' allow easy removal of calculus, are more time efficient to use, and require less training to use effectively. Unfortunately though, they have a greater potential for iatrogenic damage if used incorrectly. There are three types of mechanical scalers, namely sonic, ultrasonic and rotary.<br><br>

'''Mechanical or powered scalers''' allow easy removal of calculus, are more time efficient, and require less training to use effectively. Unfortunately, they have a greater potential for iatrogenic damage if used incorrectly. There are three types of mechanical scalers; sonic, ultrasonic and rotary.<br><br>

'''Sonic scalers''' are driven by compressed air, so they require a compressed air driven dental unit for operation. The tip of the scaler oscillates at a sonic frequency. They are generally less effective than ultrasonic scalers, but generate less heat and are thus less likely to cause iatrogenic damage to the tooth surface. Most sonic scalers are designed for supragingival scaling but can be used subgingivally if the appropriate tip is used. <br><br>

'''Sonic scalers''' are driven by compressed air, and require a compressed air driven dental unit for operation. The tip of the scaler oscillates at a sonic frequency. They are generally less effective than ultrasonic scalers, but generate less heat and are thus less likely to cause iatrogenic damage to the tooth surface. Most sonic scalers are designed for supragingival scaling but can be used subgingivally if the appropriate tip is used. <br><br>

'''Ultrasonic scalers''' are the most commonly used scaler in veterinary practice. The tip oscillates at ultrasonic frequencies (25kHz, 30kHz or sometimes slightly higher). They are driven by an electric micromotor. The tip vibration is generated either by a magnetostrictive mechanism, or by a piezoelectric mechanism in the handpiece. In magnetostrictive–type scalers, the mechanism is an electric coil around a stack of laminated ferromagnetic strips or a ferrite rod. The tip vibrates in an elliptical path. Piezo-elecetric-type scalers use a piezo-electric crystal system with piezoceramoc discs that vibrate on a titanium shaft when a high frequency electric current is applied. The tip vibrates only in a linear direction. Metal vibrating at a high frequency generates heat so the tip needs to be cooled to prevent thermal damage to the teeth and soft tissues. The ultrasonic oscillation of the tip also causes cavitation of the water coolant. Cavitation is the production of microscopic bubbles which then implode, realeasing energy. This helps disrupt the calculus on the surface of the tooth and has also been thought to have an antibacterial action especially on [[:Category:Anaerobic bacteria|anaerobic bacteria]]. Ultrasonic scalers are generally designed for supragingival use, but tips designed for subgingival scaling are available.<br><br>

'''Ultrasonic scalers''' are the most commonly used scaler in veterinary practice. The tip oscillates at ultrasonic frequencies (25kHz, 30kHz or sometimes slightly higher). They are driven by an electric micromotor. The tip vibration is generated either by a magnetostrictive mechanism, or by a piezoelectric mechanism in the handpiece. In magnetostrictive–type scalers, the mechanism is an electric coil around a stack of laminated ferromagnetic strips or a ferrite rod. The tip vibrates in an elliptical path. Piezo-elecetric-type scalers use a piezo-electric crystal system with piezoceramic discs that vibrate on a titanium shaft when a high frequency electric current is applied. The tip vibrates only in a linear direction. Metal vibrating at a high frequency generates heat so the tip needs to be cooled to prevent thermal damage to the teeth and soft tissues. The ultrasonic oscillation of the tip also causes cavitation of the water coolant. Cavitation is the production of microscopic bubbles which implode, realeasing energy. This helps disrupt the calculus on the surface of the tooth and has also been thought to have an antibacterial action especially on [[:Category:Anaerobic bacteria|anaerobic bacteria]]. Ultrasonic scalers are generally designed for supragingival use, but tips designed for subgingival scaling are available.<br><br>

'''Rotary scalers''' are described here for completeness but are never recommended in veterinary practice as the potential for iatrogenic damage is high. Non cutting burs are used in a high-speed, air driven hand piece. When the bur is applied to the calculus, the calculus disintegrates and is flushed away by the water spray. They have been shown to cause extensive [[Enamel Organ#Enamel|enamel]] damage and when used in humans, resulted in post operative pain.

'''Rotary scalers''' are described here for completeness but are never recommended in veterinary practice as the potential for iatrogenic damage is high. Non cutting burs are used in a high-speed, air driven hand piece. When the bur is applied to the calculus, the calculus disintegrates and is flushed away by the water spray. They have been shown to cause extensive [[Enamel Organ#Enamel|enamel]] damage and when used in humans, resulted in post operative pain.

[[Category:Dental Instruments]]

[[Category:Dental Instruments]]

[[Category:To Do - Dentistry preMars]]

[[Category:To Do - Mars Check]]