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Microdentistry updated


“Needle’ and ‘drilling’ are the most objectionable words in most people’s vocabulary for dental treatments. Before the 1940s, drilling with steel burs in belt driven, slow speed handpieces was traumatic, noisy, vibrating and painful and, in addition, dentists used ‘novocain’ mostly for extractions.

The nature of the practice of dentistry has dramatically changed during the past 60, and especially during the past 20 years, both for the patients as well as dentists.

Dr Robert Black invented ‘AirDent’ in the 1940s, distributed by the S.S. White Company 1, which was the precursor of the air-abrasion tooth preparation, the way we know it today. While there was no vibration, it was silent and fast; the then current ‘venturi operated’ saliva ejector could not do its job on the onslaught of the sand-like particles, because there was no high-speed evacuation. The end result was a big mess in the office. Yet, by 1950 there were more than 2000 dentists who used it.

‘Airdent’ faded and died in the 1950s, after the high-speed drill made its appearance. In spite of the shrill noise of the turbine and the vibration during tooth preparation, it ruled as the king from the 1950s to the 1980s.
In the late 1980s air abrasion had a rebirth. It was redesigned, modernized and many companies joined the revolution to assist in the cavity preparations for the newly developing bonding techniques. Our restorations became small. Instead of the large GV Black type preparations, we removed only the defective parts, preserved tooth structure, then restored the teeth with the toothcolored restorations (Figures 3,4,5,6,7,D1,D2). 

Microdentistry was born and it became easier and much more comfortable for the patients (7, 5).   Treatment of cavities became faster, most of the time there was no need for anesthesia and as a result, we could do multiple quadrants during the same appointment. Patients didn’t leave with a fat lip or tongue, there was no vibration or noise during the ‘drilling’ and there were no microfractures or shattering of the enamel as with the bur (3, 4).  Bond strength also increased for both direct and indirect restorations.

The major negative discussions regarding air abrasion always revolved around the generation of dust in the office and its relation to health issues.  While using it only for a short time for each tooth, we had to follow the rules then, which are standard procedures today, gloves, covering the patient, facemasks, goggles, safety glasses for patient, doctor and assistant and intraoral high speed evacuation. They all cut down the spreading of the dust tremendously. Following the proper protocol, the health issue problems were minimized. It was recommended that air abrasion use 29µ Al2O3 particles intraorally. While particles less than 10µ can penetrate into the alveoli of the lung, OSHA, (Occupational Safety and Health Administration) have always considered particles larger than 10µ only a nuisance dust (2,6) . With this knowledge we still had to be careful, because the dust could always be an upper airway irritant in patients who have respiratory problems, asthma, blocked nasal passages or cold. Environmentally I have never removed old amalgams with it and never used it with patients who were on a restricted sodium diet.

For the past eight months I have been using a brand new version of an air abrasion unit, Aquacut, by Velopex (8), (figure 8), which combines the positive qualities of the previous AA machines with increased efficiency, convenience and a substantial reduction of dust in the mouth, as well as in the office.

The Acquacut unit ingeniously combines the delivery of the pressurized cutting powder with a concurrent water curtain before it hits the tooth. The water spray reduces the need for higher air pressure, decreases sensitivity, increases efficiency, and reduces dust and tooth preparation debris. Overall, the treatment is more pleasant for the patient as well as the team. I found it more enjoyable to work with, than my previous units.

The Al2O3 powder comes in sealed individual, sterilized, color coded containers (Figure 11) in two grades, 29µ and 50µ. The former is used for tooth preparation, while the latter, if used at all, is recommended for extraoral cleanup of cements and to microabrade indirect restorations before they are cemented or bonded in.

The tungsten carbide tip handpiece has two tubes (figure 9). One is connected to the sealed aluminum oxide powder cartridge (figure 11); the second is connected to a small bottle of sterile water bottle. To enable the water to flow and form a curtain around the exiting, high-speed particles, a small, disposable, flexible, clear plastic tubing is attached between the nozzle (figure 10), and the water tube. This plastic tubing is discarded after treatment and the handpiece is easily removed through a quick disconnect for sterilization.

Aquacut is available as a twin dispensor unit (Figure 8). I use one canister of the 29µ grade aluminum-oxide powder and a second cartridge of sodium bicarbonate powder, also color coded, to be able to remove stains and polish teeth. I use this combination, because I can please patients irrespective of their hygiene appointments and it only takes a few minutes. I can switch between the two cartridges already seated in the unit by flipping the lilac switch, as shown in Figure 12). The cartridges themselves also can be changed any time, at will, so I am not restricted in which powder I am using.  

The handpieces come with tip orifices of either 0.05mm blue), 0.06mm (silver), or 0.08mm (gold) for the tasks ahead. The air pressure can be adjusted from 15psi to 100psi and the powder flow can be adjusted from 15psi to 34psi independently from each other.

I also enjoy the unit’s redesigned foot control. It has triple action now. When the pedal is depressed, it can WASH the debris, only water flows, DRY the prep, only air flows or CUT the tooth (figure 12), both water and powder flows.

As the water forms a conical curtain around the powder exiting the tip, it contains it, cools the tooth and reduces dust formation. The remaining dust and the tooth preparation debris can be easily evacuated with the high-speed evacuation system we dentists are familiar with already. The masks, goggles and all the other specific safety features should still be used at all times, but the improvements increase the pleasure of using the equipment.
With the emergence of the hard tissue lasers and the electric handpieces, two additional modes of tooth preparation, we are again at a crossroad. Or are we?

The cost and size, as well as the movability of the equipment, the space available, the requirement need for additional training, certification and the style and type of the practice will determine which direction each of us take. We all have different needs and preferences.

One can always put forward a compelling argument for any treatment or technology. We need to be able to incorporate and utilize the proper technology for different situations to achieve our goal: treating our patients efficiently, with minimum trauma, care, diligence and respect.

Having used and abandoned this technology for years I have found, that Acquacut is certainly making my life easier. Cavity preparation again is fast, silent, vibration free, produces no heat, no microcracks and practically dust free. We still maintain structural integrity of the teeth by doing conservative preps, which is easily restored with toothcolored restorations, exactly what patients want today (figures 16,17,13,14,15). 

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