This article is sponsored content brought to you by W&H.
Innovation and problem- solving when working with Zirconia
Zirconia has become a popular material in restorative dentistry for its biocompatibility, high fracture toughness and radiopacity. Dental zirconia is more often a modified yttria (Y2O3) tetragonal zirconia polycrystal (Y-TZP), because it has greater mechanical properties and better tear resistance than other ceramics.
Despite the advantages of zirconia, restoration failure due to crown fracture remains a possibility. In a recent survey, the difficulty associated with its removal or replacement was reported by practitioners to be one of the main disadvantages of using zirconia as a prosthetic material.
Material science is a crucial aspect of drilling science, and different materials are described in terms of hardness using the Mohs Hardness Scale. Zirconia is 8.8; around the same hardness as tungsten carbide, which is a commonly used material in burs. Diamond is 10 on the Mohs Scale, and super coarse diamond burs have been found to be more effective at cutting zirconia than others, although the greater force needed to cut zirconia still results in frequent bur wear.
Friction and heat
Balancing the relationship between torque and speed, while managing the effects of friction, is an enormous challenge when cutting very hard materials. Thermal damage to patients is a greater risk when working intraorally, due to the very high temperatures generated in the process.
The heat generated within the handpiece itself is higher when cutting hard material, this can cause the water to heat up, which can potentially hurt the patient and/or handpiece operator, so techniques to reduce overheating and improve cooling have had to be innovative. The faster the coolant flow rate, the more effectively it will maintain a lower temperature.
The normal spray rate is 15ml/min. Increasing this to 25ml/min not only reduces the risk of thermal damage, it has also been shown to improve cutting performance and keep burs cleaner. Handpieces with higher torque operate effectively at a lower speed, and have a lower vibration rate than low-torque handpieces.
W&H has been a global leader in the development and manufacture of medical technology products since 1890. Their new Synea Power Edition has been specifically designed to manage the hardest new materials used in dentistry today including zirconia.
Cutting efficiency is maximized by the optimum ratio of torque and speed, making it the optimal solution for advanced ceramic material like zirconia. Its superior cooling capabilities allow a flow rate of over 50ml/min – more than triple the normal spray rate – ensuring greater safety and improved durability.
Innovation in one area of technology often requires other technologies to advance rapidly to keep up. As long as material sciences continue to develop to deliver greater restoration robustness, innovation in handpieces designed to support new clinical needs will undoubtedly also grow.
To find out more visit our website at www.wh.com/en_australia or contact your W&H Sales Partner to find out the latest promotion.
