About Lifelong Learning - Contact Us - DonateFree-Ed.Net Home   Bookmark and Share

1. The Basic Examination and Anesthetic Instruments


Restorative procedures cannot be done adequately without proper maintenance of equipment. Sharp cutting instruments are particularly important and present a continual maintenance problem for the dental specialist. Regardless of what type of cutting procedure (oral hygiene, restorative, or surgical) is to take place, it is very important to have sharp instruments. The dentist
 can do a better and more efficient job if he has sharp instruments to work with. You, as a dental specialist, will be responsible for sharpening these instruments. There are three very important reasons for having sharp instruments. A sharp instrument decreases the chance of traumatizing the patient's soft tissue, or of operator fatigue, and, therefore, greatly increases efficiency.

a. Techniques For Sharpening Instruments.

(1) The fixed-stone technique. The fixed-stone technique is the first of three techniques for sharpening instruments that we will consider. Fixed stones are unmounted stones. There are two types--hand stones with rounded edges, in cylindrical or rectangular shapes, and flat stones, rectangular in shape, which may be smooth without grooves or have one surfaced grooved lengthwise. Equipment for the fixed-stone technique consists of either a Carborundum™ stone or an Arkansas stone, a lubricant, two-inch by two-inch gauze, and of course, the instrument to be sharpened. The Carborundum™ stone is a soft (artificial) stone that has a coarse grit, thereby limiting it to gross sharpening only. Carborundum™ stones are made in both flat and thin taper shapes. The Arkansas stone is a natural stone and comes in varying hardness. It is a fine stone for obtaining a finished edge. Black Hard is the hardest Arkansas stone. Hard is the next hardest, followed by Soft (good for hunting knives, etc.) and Washita (most rapid cutting), which has a fine grit, thereby producing a fine edge. Arkansas stones come in varying shapes: flat (grooved on one side), flat on both sides (without grooves), cylindrical, and tapered. The fixed-stone technique has one primary advantage. Use of the fixed stone will remove only minimal metal. However, the technique is messy due to the oil that is required as a lubricant. The oil prevents metal particles from adhering to the stone, reduces friction, thus reducing heat, and aids in producing a fine edge on the instrument.

Figure 1-2. Flat sharpening stones.

Figure 1-3. Proper angulation for sharpening an instrument.

(2) The mounted-stone technique. The second technique for sharpening dental instruments is the mounted-stone technique. This technique is especially useful in sharpening instruments with curved or irregularly shaped nibs. Equipment consists of mandrel-mounted stones, a straight handpiece, lubricant, two-inch by two-inch gauge, and again, the instrument to be sharpened. Mounted stones are made of two materials, Arkansas stones and ruby stones (sometimes called sandstones). Ruby stones are primarily composed of aluminum oxide. The ruby stone is comparatively coarse, has a rapid cutting ability, and is used for sharpening instruments that are dull. Mounted stones are cylindrical in shape and appear in several sizes. They have a fine grit and are used with the straight handpiece. The stones permit rapid sharpening, but without extreme care, will remove too much metal and may overheat the instrument. Overheating the instrument will destroy the temper, thereby causing the instrument to no longer hold a sharp edge.

(3) The rotary-hone technique. The rotary-hone technique is the third technique of sharpening instruments. The rotary hone was invented by Dr. E. L. Kirkpatrick of Marquette University, and it is called the E.L.K. Rotary Hone. The equipment for this technique is the same as for the mounted-stone technique with the addition of the hone itself. The hone attaches to the straight handpiece and provides a table serving as a rest and a guide for the instrument. The advantages/disadvantages of the rotary-hone technique are the same as that of mounted stones. However, greater control of the instrument is provided by the table. Oil is used as a lubricant with this technique as recommended by the manufacturer.

Figure 1-4. Removing wire edge from instrument.

NOTE: Using a hand stone, the instrument should be stabilized while being sharpened. The instrument is placed so the inner concave surface is upward and parallel to the floor. The stone is placed on the inner surface of the blade at its junction with the shank and then moved back and forth in a sawing motion until it reaches the tip. The outer surface is honed slightly to remove the wire edge.

Figure 1-5. Sharpening an instrument using a hand stone.

b. Instrument Sharpening Principles. Certain principles of instrument sharpening MUST be adhered to in order to properly sharpen an instrument.

(1) Establish the proper angle. Before starting to sharpen, establish the proper angle between the stone and the surface to be ground. The plane of the surface being ground should be used as a guide. Sharpening entails reducing the surface of the blade in relation to the dull edges; to accomplish this, reduce the entire surface--do not create a new bevel at the cutting edge. Do not tilt the stone so that it cuts unevenly across the surface being ground.

(2) Lubricate the stone. Always lubricate the stone while sharpening. This avoids unnecessary heat, as indicated earlier, which changes the temper of the instrument, making the steel softer. Avoid excessive pressure. This heats the edge, even though the stone is lubricated. A light touch is essential. Sharpen the instrument at the first sign of dullness.

(3) Wear safety glasses. Finally, the most important principle or precaution is to always wear safety glasses, especially when using the mounted-stone or rotary-hone techniques. The metal particles and the lubricant will be flying through the air and inevitably will strike eyes or face; so be sure the wheel is rotated away from you. The safety glasses are for your protection. WEAR THEM!

c. Testing For Instrument Sharpness. Two methods of testing instruments for sharpness are available, the light test and the thumbnail test.

(1) The light test. This test requires that you look directly at the sharpened edge. A shiny edge indicates that the instrument is dull, while a sharp edge will appear as a black line. A sharp edge will not reflect light caused by the fine line that appears as sharpness is achieved.

(2) The thumbnail test. This test is the more reliable of the two tests. Hold the sharpened edge of the instrument at a 45 angle to the nail. Using light pressure, push or pull the instrument (as dictated by the function of the instrument). If the instrument slips or glides along the nail, it is still dull. If the instrument grabs or shaves the nail, a sharp edge has been restored.

Figure 1-6. Mounted sharpening stones.

NOTE: Using a mounted stone, the instrument is held in a palm and thumb grasp, with the inner concave surface facing upward, and the tip toward the dental specialist. The stone is made to revolve slowly in the handpiece. Place the slowly revolving stone against the inner surface of the junction of the blade and the shank and draw it slowly toward the tip until it passes off the scaler. Both lateral edges will be sharpened simultaneously.

Figure 1-7. Sharpening an instrument using a mounted stone.

David L. Heiserman, Editor

Copyright   SweetHaven Publishing Services
All Rights Reserved

Revised: June 06, 2015