DA 2

INSTRUMENT EXCHANGE SEQUENCE
- When working with a right-handed dentist, the assistant will use his/her left hand to exchange instruments.
- When working with a left-handed dentist, the assistant will use his/her right hand to exchange instruments.

1. Ready Position/Preparation
The dental assistant holds the instrument to be delivered in his/her thumb and first fingers at a distance of 8 - 10 inches from the patient’s mouth. The instrument must be held close to its non-working end to allow space at the working end for the operator to grasp the instrument. The operator should receive the instrument properly oriented for the quadrant being treated. Burs and cutting edges of hand instruments should be directed toward the area of the planned operation.

2. Signal by dentist
The operator signals a readiness to exchange instruments by lifting the instrument out of the patient’s mouth, using only the thumb and first finger.

3. Paralleling of instruments
At this moment the assistant positions the instrument to be exchanged close to and parallel to the instrument in the dentist’s hand.

4. Instrument pick up
The assistant will extend his/her two fingers and remove the unwanted instrument from the hand of the operator at the end of the instrument most distant from the patient’s mouth. By folding the pick up fingers into the palm, the assistant will lift the unwanted instrument out of the operating field.

5. Delivery
The instrument to be delivered is then lowered into the operator’s hand and he/she can resume work in the patient’s mouth.

6. Rolling used delivery position
If the instrument taken from the operator is to be reused immediately, the assistant must move the instrument from his/her pickup fingers back into the delivery portion of the hand. This can be accomplished by rolling the instrument between the thumb and pickup fingers back into the ready position.

7. Ready of next exchange
If the instrument taken from the operator is not to be used again, the assistant returns the used instrument to the instrument tray and selects the next instrument in the sequence of the treatment procedure. This instrument is then held in the ready position until the dentist makes another signal for exchange.
Certain instruments will require that the dentist release his/her finger rest at the patient’s mouth when executing an instrument transfer to the dental assistant. When exchanging a hand instrument for a double-handed instrument, such as dental pliers, scissors or rubber dam forceps, the operator must give up the finger rest to receive the new instrument in his/her palm.
When the instrument transfer method is performed properly, the dentist should not have to wait more than 1-2 seconds for any needed instrument. If the dentist is required to wait as long as 4 seconds for each exchange, the dentist could work as time efficiently by working alone. Since an average of 150 instrument exchanges are performed during a routine class II amalgam restoration, the time wasted by poor exchange techniques may significantly reduce production.

PARTS OF DENTAL HAND INSTRUMENTS
There are four parts of a hand instrument (figure 1-1). The longest part is the handle where the dental officer holds the instrument when using it. The shank joins the handle and a blade or nib. A cutting instrument has a blade and a cutting edge, whereas a non-cutting instrument has a nib and a face or point. There are identifying numbers on the handles of each instrument, and these numbers must be used when the instruments are requisitioned from the supply section.

Figure 1-1. Parts of a hand instrument.
BLACK'S CLASSIFICATION OF INSTRUMENTS
Dr. G. V. Black classified instruments according to ORDER names, SUBORDER names, CLASS names, and SUBCLASS names. Order names denote the purpose for which the instrument is to be used, such as mallet or clamps. Suborder names define the manner or position of use of the instrument, such as hand mallet or molar clamps. Class names describe the working point of the instrument, such as spoon excavator or inverted cone bur. Subclass names indicate the angle of the shank, such as bin-angle. Dr. Black also evolved the instrument formula by which instruments could be readily duplicated anywhere. For example, the number of a gingival margin trimmer is given as 15-95-8-12R. The first two digits (15) of the formula designate the width of the blade in tenths of a millimeter, the third and fourth digits (95) its length in millimeters, and the fifth digit (8) represents the angle which the blade forms with axis of the handle expressed in hundredths of a circle (100 gradations or centigrades). With the instruments in which the cutting edge is at an angle to the length of the blade, the sixth and seventh digits represent the angle made by the edge with the axis of the hand, expressed in centigrades. The handle letter (R or L) signifies that the instrument is one of a pair made in "rights" and "lefts" in order to work more efficiently.

MAINTENANCE OF CUTTING 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 dental officer 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 45º 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.
SCOPE OF ORAL DIAGNOSIS
Diagnosis is the process of identifying a disease or disease process from a study of its appearance and effects. Since the patient is not always aware of the presence of disease, recognition must often precede diagnosis. For this reason, both periodic physical and dental examinations are required for Army personnel. Dental examinations result routinely in the diagnosis of dental caries and periodontal disease, but the dental officer does not limit his examination to dental and periodontal tissues. Because of his training, the dental officer has the responsibility of diagnosing localized diseases of the lips, the tongue, the oral mucosa, and the salivary glands and diagnosing changes in such tissues that are indications or extensions of diseases at other locations in the body. Many systemic diseases present early oral manifestations that are discovered during routine dental examination. Thorough examination of oral tissues occasionally results in the discovery of malignant, potentially malignant, or other serious lesions. Early recognition of these conditions permits early, more effective, and more conservative treatment, resulting in a more favorable prognosis.
FACILITATING PATIENT TREATMENT
No matter what type of procedure the dental officer is about to perform---amalgam restoration, root canal, or even oral surgery--he must also perform preliminary procedures. In order to check the condition of the patient's oral cavity and to see if any changes have taken place since the last visit, he conducts a basic dental examination. Secondly, the dental officer will need to administer an anesthetic prior to most restorative or surgical procedures. The equipment, materials, and instruments used during an examination or used for administering anesthesia are the topics for discussion in this lesson. Your primary goal is to facilitate the treatment of patients, as a dental specialist. Have the proper basic examination instruments ready and the anesthesia items assembled for use will result in overall decreased chair time, help allay patient apprehension, and provide for quicker and more efficient treatment. As a quick reference, the items in a typical setup are listed in Annex A.
INSTRUMENTS
a. Mouth Mirrors (Mirror, Mouth Examining). Mouth mirrors (figure 1-8) enable the dental specialist and the dental officer to see, by reflective vision, surfaces of tissues and teeth, which cannot be seen with direct vision. They aid in reflecting light into dark areas in the mouth so tissues and teeth may be more readily seen. They can be used to retract soft tissues of the cheek, tongue, and lips. There are two general types of mouth mirrors: plane glass mirrors in which the reflected image is the same size as the object being viewed, and magnifying mirrors in which the reflective image provides an enlarged view. The type of mirror used depends on the preference of the dental officer. Mirrors are screwed to their handles at an angle to facilitate viewing and to permit replacement after the mirror has become ineffective.

Figure 1-8. Mouth mirror.
b. Explorers (Explorer, Dental). Explorers (figure 1-9) are sharp, pointed metallic instruments so designed that the various surfaces of teeth may be conveniently reached with the explorer point. Three different explorers are commonly used in the Army Dental Service. One, the number 23 explorer, ends in a semicircle tapering to a point at its distal end. The working end of the other two explorers, numbers 6 and 17, are shorter, straight, and at an angle to the handle. These instruments are used for diagnostic
purposes based on the sense of touch and on mechanical penetration of defects in tooth surfaces. Some diagnostic purposes are: locating caries and enamel defects on the interproximal, occlusal, and other surfaces which are difficult to see by direct vision, locating subgingival calculus, and locating of faulty margins on dental restorations.

Figure 1-9. Explorers.
c. Cotton Pliers (Forceps, Dressing). Cotton pliers (figure 1-10) are tong-like, metallic instruments. The working end of a pair of cotton pliers consists of two tapered opposing portions that form a 60-degree angle with their handle. Cotton pliers are used for handling cotton pellets, cotton rolls, small instruments, or other small items placed into or withdrawn from the mouth. The pliers are also used to carry liquid medication between the closed beaks for deposit in areas of the mouth or teeth.

Figure 1-10. Cotton pliers.
d. Periodontal Probes (Probe, Periodontal). Periodontal probes are non-cutting instruments (figure 1-11) that are used to determine the depth and outline of soft tissue pockets. Most are single-ended; some are double-ended. Periodontal probes have handles, a rounded nib, and a point (or face). The angle of the nib will vary according to the intended use. The nib is marked with graduations that correspond to millimeters.

Figure 1-11. Periodontal probe.
e. Saliva Ejectors (Mouthpiece, Saliva Ejector, Dental). Saliva ejector mouthpieces are made to be attached at one end to the saliva ejector tubing on the dental unit. The other end rests in the mouth for the evacuation of saliva, blood, water, or debris during dental procedures.
f. Pulp Tester (Tester, Pulp, Dental). A pulp tester (figure 1-12) is a standard instrument for use in the oral diagnosis service. This instrument is used to determine the vitality of the tooth being tested by passing a small amount of electrical current from the pulp tester to the tooth. The amount of current necessary to obtain a reaction aids the dental office in determining the vitality of pulp. To perform this procedure, the dental officer will isolate the tooth to be tested with cotton rolls, and dry the tooth with a warm air syringe. He will apply toothpaste or fluoride gel to the tip of the pulp tester. This paste acts as an electrical conductor and ensures good contact with the tooth. Next, the dentist applies the tip of the pulp tester to the tooth. The tester will automatically start at 0 and slowly increase the current until the tester reads 80. Normally, a vital tooth will respond to the electrical stimulus at some point between 5 and 80. Eighty is the maximum current level on the pulp tester and indicates that the pulp is nonvital. Because of the plastic covering, the tip of the pulp tester should be disinfected and not heat sterilized.

Figure 1-12. Pulp tester.
BASIC DENTAL EXAMINATION SETUP
a. The Setup. The basic dental examination setup (figure 1-13) consists of a mouth mirror, cotton pliers, explorer, periodontal probe, cotton dispenser with cotton, Two by two inch gauze pads, and a saliva ejector. This equipment is used in almost every dental treatment procedure. The water and air syringes are frequently used to remove debris and fluids from tooth surfaces so that they may be examined more accurately. A good light source is also essential to adequate vision in performing any oral diagnostic procedures.
b. The Sterile Pack.
(1) Certain instruments are required for each type of dental procedure. In order to facilitate the work being done, these instruments can be prepared in advance. Possibly days, or even weeks, before the actual operation is performed, the dental assistant can wrap the proper instruments in a pack (usually paper or muslin) and autoclave them. These sterile packs can then be stored and used whenever necessary. This method will save both time and space in the dental clinic. The pack used most frequently contains the basic examination instruments, with the exception of the saliva ejector. These could be prepared long in advance since a basic examination is common procedure for all types of dental work. Remember, though, that the type of material in which the instruments are autoclaved determines how long they will remain sterile.
(2) The instruments found in the basic examination sterile pack is the explorer, (number 6, number 17, or number 23), the mouth mirror, the periodontal probe, cotton pliers, and 2x2-inch gauze pads.

Figure 1-13. Instruments and materials for basic examination.
1-13. MEDICAL HISTORIES
a. General. Any dental examination includes taking and recording the patient's medical history. The medical history may be brief or detailed, depending upon the findings and observations made during the examination. The history consists mainly of information pertinent to the conditions revealed during the examination and is obtained from the patient from questions asked by the dental officer. A medical history should be updated at every appointment.
b. Importance of Medical Histories. The following are four important functions of patient medical histories:
(1) Provide important information that assists the dental officer in arriving at a diagnosis.
(2) Provide information on conditions that might lead to complications during treatment procedures if not previously recognized.
(3) Establish good rapport with the patient.
(4) Provide a good opportunity for patient education.
c. Taking and Recording Histories. Pertinent information brought out while taking the patient's history should be recorded in writing. In taking a history, the dental officer often has an established routine, which he conscientiously follows so that no possible information is overlooked. He may take brief notes and later write the summary to be recorded or transcribed as part of the patient's record.
d. Ethical Aspects. Information given by the patient to the dental officer is confidential and is used to enhance professional care. The dental specialist will not reveal confidential information to any person not concerned with the patient's medical or dental health.
e. Medication. The dental officer, during an initial examination and before starting any dental treatment, routinely asks a patient if he is taking any medication. If so, a notation is made on the record as to the type and amount of drug being taken. Special considerations in providing dental treatment and in prescribing additional drugs will be determined from this information.
f. Medical Treatment. During a dental examination, the dental officer asks the patient if he is under medical treatment and, if so, for what particular condition. This will enable the dental officer to determine the best plan for dental treatment.
g. Systemic Conditions. There are a number of oral manifestations of systemic diseases, if discovered while taking the medical history, which must be considered carefully in planning and carrying out the course of treatment. Because of physical standards for active military duty, these conditions are not as common in the military community as in other segments of the population. Some of these conditions, including potential dangers and precautions to be taken, are as follows:
(1) Congestive heart failure. Patients with congestive heart failure have hearts that have been weakened to the extent that they can no longer fulfill the body's demands. A physician is usually consulted before oral surgery or other dental treatments are performed.
(2) Rheumatic heart disease. Rheumatic fever is a disease that may affect the valves of the heart. Heart valves that have been damaged (rheumatic heart disease) by rheumatic fever are susceptible to infections from bacteria, which may be forced into the bloodstream during extraction of teeth or other dental procedure. Should a patient with a history of rheumatic fever require dental care, the dental officer normally will consult the patient's physician and institute prophylactic antibiotic treatment before performing the indicated treatment.
(3) Coronary artery disease. Patients with coronary artery disease (disease of the arteries that supply blood to the heart) may experience pressure or pain in the chest called angina pectoris. Pressure or pain occurs when narrowing of the coronary arteries prevents adequate oxygen to the heart muscles. Attacks may be brought on by nervousness and physical or emotional stress. Patients with a known history of angina pectoris should be treated only after every precaution has been taken to minimize nervousness and stress. Usually a physician is consulted before these patients are treated. The patient who has angina pectoris usually carries his own supply of nitro- glycerin.
(4) High blood pressure (hypertension). The dental officer normally will consult the patient's physician before surgery or any extensive dental treatment on a patient with elevated blood pressure. Premedication, selection of the anesthetic agent, and the duration and nature of anticipated surgery or dental manipulation all require careful consideration.
(5) Diabetes mellitus. Diabetes is a systemic disease in which the body is unable to utilize sugars in the diet because of the lack of insulin in the system. Diabetes may be controlled by periodic injections of insulin, oral medication, or diet, depending on its severity. Periodontal disease is often associated with uncontrolled diabetes. Special consideration must be given in performing surgery or any dental treatment on diabetics because of their tendency to bleed easily and their high susceptibility to infections. The dental officer normally will not perform extractions on uncontrolled diabetics unless the patient's physician assumes responsibility and supportive measures have been employed.
(6) Hemophilia. Hemophilia is a rare hereditary condition appearing in males. In hemophilia, there is profuse bleeding due to an inadequate clotting mechanism resulting in prolonged uncontrollable bleeding, even from the slightest cut. Any necessary surgical procedures should be done only with the cooperation of the patient's physician to minimize and to control bleeding.
(7) Pernicious anemia. Pernicious anemia is a severe form of anemia characterized by lowering red blood cell count, weakness, and other forms of debilitation. One frequent early symptom is a painful, fiery red inflammation of the tip and sides of the tongues. The wearing of dentures or any other mild mechanical irritations cannot be tolerated by some patients with pernicious anemia.
(8) Allergy and hypersensitivity. Patients may be allergic or hypersensitive to any of a number of drugs or materials used in dentistry. The dental officer must take a thorough history, so that he may avoid the use of drugs and materials to which the patient may have an unfavorable reaction.
(9) Hyperthyroidism. Hyperthyroidism is a disease in which the thyroid gland is abnormally active and produces marked systemic effects. Among these effects are pronounced nervousness and emotional instability, cardiovascular changes, weakness, and other symptoms. Extensive or painful oral operations or the use of agents containing adrenalin is contraindicated in the active hyperthyroid cases. The patient's physician normally will be consulted before an oral operation is performed on the patient. The hyperthyroid patient on adequate medication can become a well-stabilized dental patient.
(10) Hepatitis B. Patients with active hepatitis, or who are carriers of the Hepatitis B virus, can infect the dentist, staff, and other patients. To reduce risk to everyone, strict barrier protection procedures must be enforced (masks, gloves, gowns, and protective eyewear) along with strict aseptic techniques. Hepatitis is a very debilitating disease and causes death in a small percentage of the cases. Therefore, it is recommended that all dental personnel receive the heptavax vaccine to eliminate risk of infection with the Hepatitis B virus.
(11) HIV Infection. Human Immunodeficiency Virus (HIV) infection, or AIDS as it was originally called, causes death by destroying the patient's immune system. More simply, the patient dies from an infection because the body's defense system does not work. This virus is very difficult to transmit from one person to another. A dental care provider cannot contract an HIV infection through daily contact at the workplace. The HIV infection enters the bloodstream by having sex with an infected person or by shooting drugs with a needle or syringe that has been used by an infected person. If you work on an HIV positive patient, the patient is many more times at risk than you are. The reason is the their immune system cannot easily control new and different infections. It is important, then, to have extremely strict aseptic procedures before, during, and after patient care. This reduces the risk to the HIV patient and the possibility of risk to other patients and the dental care providers.
ORAL EXAMINATIONS
a. Classification. Direct examination of the teeth and oral tissues is the procedure used most in determining the status of oral health. Four classifications are used to describe the dental health of active duty service members. Dental classifications are described in more detail in AR 40-66, Medical Record and Quality Assurance Administration.
(1) Class 1. Personnel who require no dental treatment.
(2) Class 2. Personnel whose existing condition is unlikely to result in a dental emergency within 12 months.
(3) Class 3. Personnel that require dental treatment to correct a dental condition that is likely to cause a dental emergency within 12 months. Class 3 includes patients who have deep caries, a fractured tooth, or pericoronitis (infection around a wisdom tooth).
(4) Class 4. Personnel who have missed two annual exams or whose status is unknown.
b. Records. As in all patient treatment areas, the dental specialist in the oral medicine and treatment planning service should assure, when treating the patient, that the correct records for the patient have been provided. As the dentist conducts the examination, he will state his initial findings and the dental specialist will record these findings on applicable charts and sections of the various forms used. The dental specialist in the oral medicine and treatment planning service must be proficient in recording examinations and know the provisions of publications which cover prescribed forms, authorized terms and abbreviations, methods of recording, and dental classifications.
RADIOGRAPHS (X-RAYS)
a. General. Radiographs are indispensable aids in diagnosing many conditions existing within the teeth, bone, or tissues that are not apparent on clinical examination. Information revealed by radiographs includes the following:
(1) Infection and abscesses within the bone and about the roots of the teeth.
(2) Size and shape of roots of teeth to be extracted.
(3) Carious lesions, which cannot be detected in other ways.
(4) Condition of the periodontal bone.
(5) Condition of teeth and bone that have been considered for the support of fixed or removable prosthodontic appliances.
(6) Presence of impacted teeth, supernumerary teeth, or retained roots.
b. Recording Radiographic Findings. Radiographs are usually completely processed before they are interpreted. This often takes place after the examination. If emergency treatment is indicated, the dental officer may request a "wet reading." At such times the radiographs are processed enough to obtain suitable image for interpretation and diagnosis, and remain attached to the radiograph hanger. Radiographs that have been completely processed and mounted are interpreted by the dental officer, when he is not engaged in examination or treatment procedures. The dental specialist must see that the radiographs are properly mounted and available for the dental officer for interpretation and must be able to record radiographic findings on dental health records. Radiographs should be kept in the dental health record until they are no longer needed.
STUDY CASTS
a. Definition. Study casts are another aid in examination and diagnosis. They are plaster or artificial stone casts poured in accurate impressions of the dental arches. These are often mounted on an anatomic articulator (articulator which may be adjusted to reproduce the movement of the jaw).
b. Function. Study casts are used to:
(1) Permit study of alignment and occlusal relationships of the teeth outside the confines of the patient's mouth.
(2) Permit coordinated study of the teeth and radiographs after the patient has left the office and the radiographs have been processed and dried.
(3) Provide a duplication of the mouth, which is useful in consultations with other dental officers.
(4) Provide a permanent record of oral conditions as they existed prior to treatment.
(5) Provide a media upon which proposed treatment procedures, such as spot grinding for occlusal equilibration or the fabrication of prosthetic appliances may be studied.
GENERAL
a. Introduction. Following the basic examination, the anesthetic is administered, when required. There are a few situations, such as an oral prophylaxis, in which an anesthetic is not necessary. However, in most restorative or surgical procedures, the dental officer will administer some type of anesthesia.
b. Uses. Anesthesia is the loss of sensation. It may be partial or complete. Certain drugs are used in dentistry to achieve anesthesia for the prevention of pain during surgical and restorative procedures. Local anesthesia, or anesthesia limited to small areas of the body, is used for most dental operations. General anesthesia, or insensibility of the entire body, is sometimes used for extensive oral surgery and cases in which local anesthesia is contraindicated. See paragraph 1-13 for systemic conditions requiring special precautions during anesthesia and surgery.
c. Local Anesthesia. Local surface (topical) anesthesia may be achieved by application of certain drugs to the skin or mucous membrane. (See figure 1-14.) Examples are: Xylocaine® (lidocaine hydrochloride) and Benzocaine® (ethylamine benzoate). Another type of agent used for topical anesthesia is known as refrigerants (ethyl chloride). These are sometimes employed to relieve gagging tendencies during dental operations and to anesthetize the tissues over an abscessed area before incision for drainage. For local anesthesia of deeper tissues, such as the nerves of teeth, muscles, and alveolar bone, an anesthetic solution is injected into soft tissues.

Figure 1-14. Materials for application of topical anesthetic.
INSTRUMENTS FOR LOCAL ANESTHESIA
a. Anesthetic Syringe (Syringe, Cartridge) (figure 1-15). The anesthetic syringe is designed to support and expel anesthetic solution from a commercially prepared glass cartridge called a Carpule™. (The trademark name is Carpule.) The cartridge syringe available for local anesthesia has a thumb-ring handle at the outer end and a harpoon at the cartridge end of the plunger. The harpoon is designed to engage the rubber stopper plunger of the cartridge. The thumb-ring is used to draw back on the plunger to determine whether the needle has penetrated a blood vessel. This procedure is called "aspirating," and the syringe is an aspirating syringe.

Figure 1-15. Anesthetic syringe (aspirating).
b. Disposable Needles (Needles, Disposable). Disposable needles are packaged to keep them in a sterile condition. Once used, they are discarded. They are attached to the syringe by a plastic hub, which is part of the disposable needle. They are supplied in lengths of thirteen-sixteenths of an inch and one and three-eighths of an inch. Disposable needles are always sterile, always sharp, and less likely to break than other needles. Hypodermic needles should be disposed of in such a way that they cannot injure clinic personnel or will not be available for pilferage or theft.
ANESTHETIC INSTRUMENT SETUP
a. Sterilized Instruments. As in the basic examination, the anesthesia also requires a certain setup. (Look in Annex A for typical instrument setups for various dental procedures.) One instrument in the setup that always requires autoclaving is the syringe. The other items are sterilized by the manufacturer and packaged in this condition.
b. The Topical Anesthetic. The first item in the setup is topical Xylocaine®. This anesthetic is produced in a jelly-like or ointment form. It is most often used to anesthetize the area where the actual injection is to be made. Two-inch by two-inch gauze or cotton tip applicators will be necessary when administering topical Xylocaine®. A small amount is placed on the applicator and applied over the area to be injected. The purpose of this topical anesthesia is to lessen the discomfort to the patient during the actual injection.
c. The Syringe. The syringe (side-loading cartridge syringe) is the only item in the setup that will require autoclaving after each patient. This syringe is used to administer local anesthetics. Syringe needles are the disposable type. The length and gauge needle used will vary depending on the preference of the dental officer. You will be handling two different needles: an infiltrative and a conductive needle. The infiltrative needle is 13/16" long and is used for maxillary injections. It is used to anesthetize a small area of possibly two or three teeth. The conductive needle is 1-3/8" long. Block injections are made with this, anesthetizing an entire area.
d. Local Anesthetics. Currently, two types of local anesthetics are available through routine supply: lidocaine hydrochloride (Xylocaine®) with epinephrine (1:50,000 to 1:100,000); and mepivacaine hydrochloride (Carbocaine®) without epinephrine. These types can be identified by their stopper color and by the color of their containers. For example: lidocaine hydrochloride with epinephrine, one part to fifty thousand, is recognized by a green stopper and green stripe on the container; lidocaine hydrochloride with epinephrine 1:100,000, has a red stopper and a red striped can; and mepivacaine hydrochloride has a white stopper and a brown container. The epinephrine is the controlling factor as to how long the anesthetic will last. The more epinephrine, the longer the area will stay anesthetized. The epinephrine is a vasoconstrictor that causes the tissue around the capillaries to swell and thus constricts the capillaries and slows the blood flow. The decreased blood flow slows diffusion of the anesthetic throughout the body thus prolonging its action. It also aids in controlling bleeding.
e. Aspiration Required. The assembly and usage of the aspirating syringe is quite simple. The syringe is equipped with a device enabling the dental officer to determine if he is injecting into the blood stream. The accidental injection of the agent into the circulatory system may produce undesirable symptoms or death. Notice the thumb ring and the barbed plunger. The barb penetrates the rubber stopper of the anesthetic cartridge, permitting aspiration when the dental officer retracts the syringe plunger by means of the thumb ring.
f. Instrument Setup. For the instrument setup for local anesthesia, see figure 1-16.

Figure 1-16. Instrument setup for anesthesia.
PROCEDURES
a. Loading the Syringe. When a disposable needle is used, the plastic hub is threaded on to the syringe without breaking the seal or removing the outer protective plastic cylinder. The first step is inserting the proper needle. The next step is to withdraw the plunger of the syringe and insert the Carpule™ (cartridge) of the anesthetic. After inserting the Carpule™, release the plunger and secure the barb in the rubber stopper by striking the thumb ring in the palm of the hand. The protective cylinder may be removed at the discretion of the dental officer. This usually will be done after the Carpule™ of anesthetic solution has been and inserted just before the injection is made. The needle and hub are discarded after use, following standard precautions, and in accordance with local policy.
b. The Injection.
(1) When the dental officer is ready to inject the anesthetic solution, he will dry the injection area with 2-inch by 2-inch or 4-inch by 4-inch gauze. He may then apply an antiseptic solution to the area with an applicator. The tissue is then ready for the injection. The specialist may hand each item to the dentist as needed and receive them from him as each step is accomplished. The dental specialist will be expected to assist by retracting tissues, reassuring the patient, and observing the patient for signs of fainting or any other reaction to the anesthetic.
(2) Local anesthetics are undoubtedly the most frequently used drugs employed in the practice of dentistry. The local anesthetic most commonly used in the Army is Xylocaine®, also called lidocaine hydrochloride (two per cent concentration with epinephrine 1:50,000 or 1:100,000). The manner of packaging these anesthetics, in disposable cartridges, makes their use in the dental syringe quick and simple. Anesthetic needles come in different gauges and lengths. The long needle is used primarily for "block" type injections and the short needle for infiltration type injections; however, the long needle may be used for both types. The 25-gauge, long needle is the one provided in the dental field kit.
c. Possible After Effects. Although the techniques are followed, and drugs are used which have a very high margin of safety, and equipment is used which is efficient and easily sterilized, complications do occur. The most common is syncope (fainting), which is caused by cerebral anemia (which is usually psychogenic in nature), and normally lasts from 30 seconds to 2 minutes. If the patient does not injure himself (that is, by falling or aspirating a foreign body and obstructing his airway), no problem of any consequence will arise. Syncope is treated by placing the unconscious patient in the shock position, using a cold, damp towel on his forehead, and/or allowing him to inhale the irritating fumes from an ammonia ampule. Occasionally, allergic reactions to the drugs used may arise, but these are extremely rare.