Buying rotary instruments is an easy task when you are used to always buying the same ones. But if we are to compare them with each other, the task can become quite difficult... So what is it that we have to take into account when buying a turbine that is economical, yet durable and efficient?
In this post we will detail everything you need to know when buying a quality turbine as well as how you can preserve its life span.
How a turbine handpiece works?
First, we need to know how a dental turbine actually works in order to identify where most problems occur while operating them.
A turbine handpiece is a rotary instrument that is driven by air compression directly through the dental unit's hose via a coupling. Among all rotary instruments, it is the one with the highest speed (from 100,000 to 500,000), but the one with the lowest torque. The working speed is approximately half that of the freewheeling speed.
Due to this high speed, significant frictional heat is produced by the driving force in the head rotor, which is why it is integrated with an air and water irrigation system to cool it down.
This instrument is needed for jobs that require greater resistance to the treatment, for instance to remove hard tissues from the tooth such as enamel or prosthesis material. Multiple contra-angle handpieces can also be used for this, but turbine handpieces will be much more efficient.
Parts of a turbine handpiece
The most important part of the turbine is the rotor, which is the component that does all the work. The standard parts of which it is composed are shown in the following diagram:
1 – Spindle: In the centre of the turbine, the rotating shaft.
2 – Chuck: It is inside the spindle. This is a hollow tube into which the lathe is fitted.
3 – Impeller: located in the middle (front to back) of the spindle. It is the impeller that captures the air that causes the turbine to spin.
4 – Front Bearing.
5 – Rear Bearing. On each side of the impeller are bearings, which allow the spindle to rotate as friction is reduced.
6 – O-rings. They guarantee a firm fixation inside the turbine head, also reducing vibrations.
7 – Washer / corrugated washers. They are used only on handpieces with automatic mandrel to provide lateral tension, keeping the turbine pressed against the cap to facilitate the operation of the mandrel.
8 – Slinger. It is placed on the front bearing to protect the bearing from dust and contamination.
What to consider when buying a dental turbine?
When choosing a dental turbine, you must take into account the following variables to choose the one that best suits your needs:
1. Head technology. The smaller the head the better it is to provide a good view to the dentist in the field of operation. The height of the head should also be considered together with the bur, as if it is too low the measurement would lose power.
2. Vibration. The noise produced by the turbine while vibrating is annoying to the patient. So the higher the vibration, the lower the number of decibels and the less disturbing it is to the patient.
3. Torque. This is the ability for a rotary instrument to continue spinning despite resistance. So the higher the torque, the greater the turbine's ability to keep turning.
4. Irrigation holes. There are two major reasons for irrigating the field with an air and water spray. First, the tooth must be cooled down to prevent overheating of the pulp and to release the material being removed for better visibility. Secondly, the irrigation cools down the head's own internal system so that it does not overheat and damage itself.
The perfect number of irrigation holes for a turbine is 4. Less would not irrigate enough, and more would unnecessarily overload the turbine.
5. Lighting. It is important to know whether or not the turbine is fitted with light to facilitate visibility of the working area. Previously, halogen lights were used, but LED technology has become very successful since it was introduced in 2007. The LED light is more powerful, durable and a whiter shade which provides a more realistic and shadowless view of the working field.
6. Power. The more power you have, the more efficient it will be to do the work, and the more comfortable the dentist will be in performing the treatment.
7. Material. The material that the turbine is made out of is also important as it will indicate the life resistance of the instrument. Among the different materials such as aluminum, chrome or titanium, titanium is the winner as it is both light and resistant, two properties that are highly demanded by dentists. This is because treatments with rotary instruments exhaust and a handpiece is needed that is both effective and light.
8. Type of grip. The type of grip is also important because as time passes during a treatment it becomes more difficult to hold the hand of the instrument as it might start being slippery. So the more notches and roughness in the handle design, the better the grip you will have. However, this has its advantages and disadvantages; the rougher it is, the better it will be, but the more dirt it will retain (as is the case with grooved handles). Fortunately, manufacturers are increasingly designing handles that are more ergonomic and easier to clean.
What can cause dental turbine failures?
Turbines, like any other device, don't last forever - but what can we do to make sure they last as long as possible? We will have to take care of the pieces that suffer the most and maintain them in the best way possible.
Bearings (specifically the bearing cage) are some of the most common parts of a turbine to fail; reasons for this include:
- Excessive air pressure.
- Very high temperatures during the sterilization process.
- Wear caused by side loading.
- Water from the compressor air storage tank.
- Use of bent lathers or a badly fitted lathe.
- Use of poor quality ball bearings of unknown origin.
- Solid residues inside the head due to inadequate or insufficient maintenance.
Bearings are not usually covered by manufacturers' warranties, as they are a wearing part of the turbine from the moment they are first used. So the more you lubricate it and the less force you apply to it, the longer it will last. It is therefore recommended to buy turbines with ceramic bearings, as they are more resistant and less likely to heat up.
Rapid cooling of handpieces with cold water after sterilization: Rapid cooling can cause deformation of some parts of the turbine, as well as contamination of already sterilized tools.
Running the turbine without the winch: This can damage the spindle or chuck mechanisms.
Irregular lubrication: The chuck should be lubricated at least once a week to keep it clean and to promote proper operation. Fragments can obstruct the chuck and affect the attachment of the lathe. Lubrication is an important task to be performed as usual in the clinic, as this will ensure that the instruments last as long as we want them to. The manufacturers recommend lubricating the turbine (especially the turbine outlet) between the patient and the patient, since with the passage of time the waste and debris solidify and damage the operation of the turbine, which would shorten its useful life.
It is very important to use the right lathes. One of the most common errors when it comes to dental turbines is the use of unsuitable lathes with a diameter smaller or larger than the standard diameter (1.59 mm). Unfortunately there are many thinner or softer lathes on the market, which come from low cost manufacturers and are attractive due to their low price. But if the lathes are too thin or too soft, they do not hold well on the chuck. Turning at around 300,000 revolutions per minute or more, sooner or later these lathes will start to deflect and end up causing damage to the chuck.
In addition to this, certain standard burs will not fit properly into a turbine handpiece even if it looks like they do. This can cause damage to the clamp that holds it in place as the diameter does not conform to the standards.
Another factor affecting the operation of the lathe is poor wear resistance of the nozzle (the gap in which the lathe is inserted). The nozzle must be made of carbide or hardened steel and must be separated from the mandrel. Many manufacturers of rotors for dental handpieces join the mandrel and nozzle in one piece because this simplifies the spindle design and thus reduces the manufacturing cost. But this technique is not the best option to increase the nozzle's wear resistance. The pressure on the lathe during the operation can wear away the nozzle, leaving the lathe more room to move radially. Due to this radial movement, dentists can no longer achieve the same precision when working with their handpiece. Increasing this movement also affects the bearing life.
Don't forget to visit the student section of the website for special deals! Call us or email us firstname.lastname@example.org with an questions or group orders.