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November 14, 2014
Practice Tips this month is getting a little dressed up for Halloween. We are going to get into character and tell you a little story called "The Vacuum & The Chairside Trap."
In the history of dental practices, infection control has had two major characters when it comes to chairside disposal.
The assistant’s instrumentation (particularly the high volume evacuator valve) is your first line of defense in infection control as it reduces contaminated aerosols which can spread blood borne pathogens which can contribute to cross-contamination.
The high volume evacuator (HVE) and Saliva Ejector (SE) are often collectively referred to as the “assistant’s instrumentation” and will both connect to a collection canister or “chairside trap” as many refer to it.
The collection canister serves two primary functions:
One: Splits the main vacuum line from the central vacuum so you can have multiple vacuum valves in the operatory. Most canisters have 4 ports on the bottom, 2 for the HVE, one for the SE, and one to connect to the main line from the central vacuum. The different vacuum valves will reduce the expulsion of contaminated aerosols into the operatory, evacuate fluids from the oral cavity to improve visibility and allow bonding of various materials, and can even be used in conjunction with nitrous oxide to scavenge exhaled gases . In fact, the 2nd HVE port is often dedicated to a valve to use with your scavenger circuit.
It is fairly common for the 2nd HVE port to be plugged with a port plug on new equipment. The port plug available from American Dental Accessories is different from most plugs in that it is tapered so it will fit inside the HVE port and outside the SE port. One plug can thus be used for either port. This plug is also made of a long lasting synthetic rubber rather than the thin plastic caps used by many equipment manufacturers.
Two: Filter solids picked up by the HVE valve(s). As you can see in the photo below, the HVE ports poke up through the collection canister, so solid debris picked up will be caught in the basket. The SE normally only picks up liquids, so the SE port does not penetrate the basket.
American Dental Accessories, Inc. carries 3 styles of collection canister, referred to as types “A”, “B” and “C”:
The Type “B” canister has a ½” outside diameter port to connect to the central vacuum line (the same size as the HVE ports). This is also the smallest canister with a basket (filter screen) that is only 1-7/8” in diameter. Because of the small size, the HVE ports are off center. This off-center design is unique to the type “B” canister. If using color-coded baskets, the baskets for a Type “B” canister are green.
The type “A” and type “C” canisters both have a 5/8” port to connect to the line from the central vacuum (“drain port”) so they can offer superior suction. The overall size of the canister is bigger and they accept a basket that is 2-1/8” in diameter. The larger size allows placing the HVE ports along the diameter of the canister (and basket). There are other older designs that have this feature as well, however, so having ports along the diameter is not a clear indicator of which canister (or basket) one might have. If using color-coded baskets, the basket for the type “A” and “C” canisters is blue.
The “A” and “C” canisters are distinguished from each other by the location of the drain port. The “A” canister has the 5/8” drain port on the bottom of the canister, the “C” canister has the port coming out of the side of the canister. The side drain allows the “C” canister to be used at the end of telescoping arms (#08-98 for example) or in other configurations that may not allow for a drain on the bottom. With a telescoping arm mount, the side port allows the drain line to feed through the arm aiding in asepsis and giving the unit clean aesthetics.
August 29, 2014
There are 2 basic types of attachments used with slow-speed motors: nosecones and contra angles.
A nosecone is a straight attachment that will accept a slow-speed bur or a shaft-driven angle (contra angle or prophy angle). Nosecones are unique and come with different gear ratios. The default is a 1:1 ratio – the nosecone will operate at the same speed as the motor. 4:1 is a common gear reduction, the nosecone will spin at ¼ the speed of the motor. Some nosecones (primarily those designed for use with electric motors) will also have speed increasing gears, so they will operate at a 1:5 gear ratio (for example), or 5 times the output speed of the motor.
Nosecones are standardized so they all will accept the same diameter bur or shaft driven attachment. Nosecones also incorporate a pin of some sort to prevent rotation of any shaft driven attachment placed on the nosecone. All shaft driven attachments have a groove that slides over this pin.
As nosecones can accept a slow-speed bur, all you may need to perform a particular procedure may be a motor and nosecone (and bur, of course).
The other type of attachment, a contra angle, will work with gear driven attachments only (most commonly some sort of head). They will not accept a bur, so further attachments are required. As the name implies, a contra angle provides an angle for the next attachment which can improve intra-oral access.
Both Midwest and E-type contra angles accept the same type of gear driven heads. The heads incorporate a drive shaft with a gear at the end that seats into the contra angle meshing with the internal drive shaft causing the head to spin. The drive gear has pointed teeth making it easier to seat the two halves together. The head also has square “teeth” under a threaded collar that mesh with the square “teeth” on the outside of the contra angle. These teeth hold the head onto the contra angle and prevent the entire head from spinning (so only the drive shaft spins). It is these teeth that one must count to determine compatibility between a head and contra angle. Heads and contra angles come with either 12 or 14 locking teeth.
Star systems do not normally use a contra angle attachment. Instead, they use a straight attachment which accepts a Star-specific head. Star heads have an elbow incorporated at the end to provide the angle normally provided by a contra angle attachment as used by other systems.
American Dental Accessories, Inc. also has an after-market contra angle that will work with a Star-type motor. This angle will allow you to use standard heads with your Star system (which can save money over the more costly Star-specific heads).
Regardless of system, a contra angle (or angle attachment) will require a 3rd attachment for use with a rotary instrument and will not be a complete set-up for a given procedure (as a motor and nosecone alone can be).
Finally, there are heads. As mentioned above, heads will have both drive teeth and attachment teeth (or drive teeth and a threaded elbow). The number of attachment teeth will determine compatibility with a particular contra angle. The head will accept the rotary instrument with which one will perform a given procedure. The most common head is a latch head which will accept a latch (or RA, for “Right Angle”) bur. RA burs have a groove at the end into which the latch of the head will secure holding the bur in. Some heads also accept standard friction grip burs, exactly as used in a high-speed handpiece.
Other heads are designed only to accept prophy cups. Prophy cups can come with either a threaded “screw on” shaft or that simply “snap on” a knob designed for this purpose. Some are also attached to a standard latch-type shaft so they’ll work in a standard latch head.
The flexibility afforded by the various head configurations allows for a tremendous range of applications for a slow-speed set-up. This flexibility can allow for great value with a slow-speed system.
February 27, 2014
Air water syringe tips are one of the most common products dentists and hygienists use in dental offices. So let's get to know more about the differences between syringe tips and which ones will work best for your practice.
The basic design of the standard air water syringe tip has remained unchanged for decades. The air water syringe has two concentric passageways, one for air (usually the outer passage) and one for water (usually the inner passage).
The central tube (see image below) is for water. On most standard tips, this tube is longer and projects out the back of the tip. This design allows the water tube to penetrate a small o-ring (#01-06) inside the syringe head to help keep the air and water separate.
On many disposable tips, the inner water passage is the same length as the rest of the tip; this means that these tips will require a special adaptor to help keep the air and water separate. If used without an adaptor, they are much more prone to cross-over (See Tech Tips #50 & Tech Tips #51). This is one reason that autoclavable tips will usually deliver superior performance.
On most syringe tips, air moves through the outer passage of the tip coming out at the end. Sometimes the air is expelled through a simple gap but sometimes several holes are used (this aspect of the design can vary widely). Most metallic tips will have a series of holes regularly spaced at the end of the tip to allow expulsion of air (see image below). The regular and consistent spacing of these holes provides a consistent spray pattern (when spraying both air and water mist). As a cost saving measure, many disposable tips simply use the natural “gap” between the inner water line and outer air line of the tip to allow air to escape out the end. Relying on this gap provides inconsistent spacing and an irregular and inconsistent spray pattern.
As mentioned, syringe tips at their most basic are simply an assembly of two concentric tubes. These are round. They go into a round passage in the air water syringe and are normally secured with o-rings. This means you’ve got a round tube in a round hole. It will spin. Many practitioners like to use the syringe tip for retraction and will push on the cheek with the syringe tip. If pushing with the tip, rotation is not desired. Most syringes are designed for quick changing of tips (as the tip should be changed after each patient) which does not normally allow for a mechanism to reduce the ability to spin if pushed on. The DCI rotation lock tips (#01-97) are an exception to this.
The rotation lock tips have a series of “dimples” (see image below) around the perimeter of the tip which will lock in with the ball bearings of the DCI syringe holding mechanism (“collar”) making it harder for these tips to spin. These tips will only work in a DCI syringe (#01-01Q or #01-85) which has 6 ball bearings in the collar to secure the tips. The ball bearings are retracted to change tips, so using a design that incorporates the ball bearings does not preclude quickly changing tips either.
With most other syringes, two o-rings (#01-04) are used to hold the tips in place. On some of these, one o-ring may be replaced with a cone (#01-21 or #01-23). Along the length of the cone is a slit (see image below). This slit provides lateral tension making it harder to spin the tip. Some syringes can be adapted to use a cone instead of an o-ring if you wish to minimize tip spin. Normally, use of a cone will make it more difficult to change tips, but it shouldn’t prevent quickly changing tips. Consult with our staff and we will help you determine if you can incorporate a cone in your syringe.
As you can see, many aspects of the tip design affect syringe performance. Keep your needs and uses in mind when purchasing tips and syringes.