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July 29, 2014
There are a significant number of handpiece brands on the market and various terms are thrown out to refer to the different slow-speed handpieces and components available. Names like “attachment” or “contra angle” or “handpiece” can all be used to refer to the same thing. No wonder so many practitioners are often confused.
Most slow-speed handpiece systems consist of a separate motor and various attachments. The motor provides the force to drive whatever type of rotary instrument will be used for a given procedure. The motor will not directly accept any type of rotary instrument (e.g. burs). Most motors operate at a given maximum rpm -- 20k and 5k being the most common speeds available.
E-TYPE This is the most common type of slow-speed motor and is the closest to a “universal” type on the market. Most house brand slow speeds use an E-type motor. NSK is one of the best known name brands to use an E-type motor. Most electric motors are also E-type motors and will accept any E-type attachments. E-type motors primarily rely on friction to hold any attachments on using o-rings and a “split ring”. Some E-type motors (long shaft- #15-105 & #15-113) also incorporate an attachment lock to further secure the attachment.
Some common brand names associated with E-type motors and attachments are: NSK, Lynx, Micro Mega, Medidenta, American and Champion, although there are many others.
STAR TITAN or "T" TYPE Star Dental has a proprietary system they use for their motors and attachments. As it is a proprietary system it will only work with components designed to work within it (ie: You cannot use components designed for a Star Titan with an E-type or Midwest Shorty (see below) component or vice versa). The Star systems use a short shaft on the motor with a groove and attachments with a spring-loaded collar covering ball bearings that seat into the groove on the motor shaft.
MIDWEST SHORTY & RHINO Midwest motors use their own proprietary attachment system. The end of the motor is recessed allowing the attachment to seat into the motor housing. The motor also incorporates a locking lever that clips onto a lip at the end of the attachment to hold it on the motor. As with the Star type, Midwest compatible components will only work with other components specifically designed for this system.
All of these motors are available in different speeds or speed combinations (some Midwest motors are available in a 2 speed configuration and the user can select the speed of the motor before operating it). The speed of the motor will dictate the speed of the rotary instrument but can be affected by the attachment (q.v.).
The first step in procuring a slow-speed system or component should always be determining what type of motor you have so that you can get components that will be compatible with it.
An attachment is the next component in the series and will attach directly to the motor. Attachments come in two primary types: nosecones and contra angles. We’ll discuss attachments in next month’s episode.
June 29, 2014
The turbine is the heart of the high-speed handpiece and bearings are the heart of the turbine.
Bearings are the most common failure point of a turbine and are often the primary differentiator between one turbine and another.
Way back in Practice Tips #22, “High-speed Handpiece Design,” we covered all of the components that make up a complete bearing assembly. For ease of reference, we’ve included the diagram of a bearing assembly below. For further explanation of the components, check out Practice Tips #22.
Today, we’re going to look at some of the different bearing materials and designs on the market.
Many turbines use stainless steel bearings that require lubrication. The balls, inner ring, outer ring, and shield are all made of stainless steel. The ball cage will be made of a polymer (there are a few more variations within this broad category and different types of polymers for the cage, but all these permutations require lubrication).
Stainless steel bearings have been in use for decades and are a proven design with good performance and good reliability. They are manufactured in large quantities for dental turbines and many other industries so cost is comparatively low. As these turbines incorporate metal bearings in metal housings, they require lubrication. Most handpiece lubricants on the market are designed to withstand the rigors of sterilization, but these turbines should still be lubricated every time they are used (see our handpiece maintenance products here). Lubrication after using and before sterilization is generally adequate, but consult the manufacturer of your turbine and lubricant to determine if post sterilization lubrication is required as well.
Many turbines currently on the market are advertised as “lube free.” There are 2 primary methods of manufacturing lube free bearings:
LTL bearings are still the same basic stainless steel design so they share many of the features of standard stainless bearings. The greasing and sealing process adds to the cost (and they aren’t manufactured in quantities like the standard bearings), so they will add to the cost of the turbine or handpiece that uses them. The sealing process, also, prevents debris from getting into the center of the bearing assembly and on the actual steel balls, so maintenance is a little easier. Nonetheless, these bearings (or, more accurately, turbines that incorporate these bearings) still need to be cleaned after every use and before sterilization.
Last of all, there are ceramic bearings. Ceramic bearings are actually made of a ceramic silicon nitride, so they have a very smooth low-friction surface. The low-friction surface removes the need for lubrication and also minimized heat build-up during use. They, also, withstand high temperatures very well, so they withstand repeated sterilization better than stainless steel bearings.
Both LTL and ceramic bearings will run at higher rpm than stainless bearings and are better able to handle higher air pressure (they typically require in excess of 40 psi drive air pressure). The higher rpm can help these turbines cut faster so some practitioners feel they perform better (naturally, this is subjective).
In summary, the materials and techniques used to manufacture lube free bearings are more costly than standard stainless bearings, so these bearings (or the turbines that incorporate them) often cost twice as much as turbines that need to be lubricated. It’s up to the practitioner if the advantages are worth the expense.
January 29, 2014
A dentist's handpiece is one of the ultimate tools in his dental office. Making sure it runs smoothly is very important.
The primary function of a handpiece is to provide power for rotary instruments, i.e. burs. If your handpiece won’t hold the bur, or won’t release the bur (so you can’t change burs) it effectively ceases to function.
Regular readers of Practice Tips will know that the chuck is the part of the turbine responsible for bur retention. Consult our issues on handpiece design and chucks for more information on this component.
There are basically two reasons for a chuck to cease functioning. One is simple break-down of the chuck itself: wear, breakage, or other alteration from the original specification preventing it from functioning as designed. The other is simple debris. If the chuck is clogged with debris, this will impede proper function.
This month we’ll show you how to properly maintenance the chuck in an auto-chuck handpiece to minimize debris build-up and eliminate it when present.
The steps illustrated below should be taken at least once a week on all auto-chuck handpieces to keep the chuck working as well as possible for as long as possible.
Materials required (see image below):
Step 1. Place a drop or two of lubricant into the chuck. If using a spray lubricant (such as Once-A-Day), a quick shot of lubricant should be sprayed into the chuck.
Step 2. Activate the chuck and insert a bur.
Step 3. While activating the chuck, (hold down the button if a push button handpiece) work the bur in and out to loosen any debris.
Step 4. Remove the bur and clean any debris off of it with the swab. Some debris may be on the exterior of the handpiece, swab this off as well.
Step 5. Re-insert bur and verify proper function. Bur should be held securely and remain in place if tugged.
Step 6. Repeat the above steps as needed. It is not uncommon to have a significant debris build-up so you may need to flush the chuck several times.
NOTE: We’ve demonstrated the technique with a Star 430 push button handpiece. We encounter clogged chucks on this make and model of handpiece frequently, but chuck cleaning should be a part of your regular weekly routine with all models of auto-chuck handpieces, Lares, Kavo, Midwest (push button or Power Lever™) or any others in your inventory. Add chuck cleaning once a week to your handpiece maintenance routine to help keep your handpieces functioning well.