Chapter 23. Dental: Diagnosis, Equipment, Blocks, and Treatment

"Love conquers everything except poverty and toothaches." Mae West, Irish Times

Unlike much of the rest of this book that assumes health care professionals already have the skills and knowledge to provide treatment, but not their normal equipment, this section describes dental diagnoses and basic treatments in considerably more detail. Treating dental emergencies is a critical skill, especially in situations of resource scarcity. Even though these emergencies are common, painful, and may occur with little or no warning, non-dentists rarely have in-depth knowledge about these problems.

Describing Teeth

When annotating the patient's medical record or communicating with another health care provider, such as a dentist, use a picture in the medical record. When communicating with another provider by phone or radio, describe the type and position of the tooth.

Teeth are either baby or adult teeth.

They are either maxillary or mandibular, and are on either the right or the left side of midline. Midline is defined as the space between the front two teeth (incisors).

There are four types of teeth (Fig. 23-1).

Those with one root:

• Incisors
• Canines
• Premolars

Those with two or more roots:

• Molars

Tooth Surfaces

The following names are used for the surfaces of the teeth. The number corresponds to those in Fig. 23-2.

1. Occlusal surface: the chewing surface of molars and premolars.

2. Mesial surface: the surface nearest the midline of the body (medial).

3. Lingual surface: the surface nearest to the tongue in the lower jaw; it is called the palatal surface in the upper jaw.

4. Distal surface: the surface furthest from the midline.

5. Buccal surface: the surface nearest to the lips and cheek.

6. Incisal edge: the incisors and canines have a cutting edge instead of an occlusal surface.

7. (Not shown) Proximal surfaces: surfaces that are close together, that is, the mesial surface of one tooth may touch the distal surface of the next tooth. The two surfaces are described as proximal surfaces.

A Tooth's Three Layers

Tooth problems may involve any of the tooth's three layers or their supporting structures (Fig. 23-3).

Crown

The part of the tooth above the gum line is the crown. Covered with hard enamel, the crown protects the other layers. Do not confuse the term "crown" as part of the tooth with the dentist's "crown" (also known as a "cap"), which is a dentist-made covering for a tooth.

Dentin

Softer than enamel but about the same density as bone, dentin is a yellowish substance that lies under the enamel and surrounds the tooth's pulp cavity.

Pulp Cavity

The "heart" of the tooth, the pulp cavity contains nerves and blood vessels. Generally, it extends from the gum line to the end of the root. The vessels and nerves then continue into the alveolar bone of the mandible or maxilla.

Tooth Attachments

Every tooth has tight attachments to the bone and gums. These are the periodontal ligaments. They must be severed below the gum line when removing a tooth.

The primary culprit in dental pathology is plaque: the soft, white or yellow layer that sticks to the teeth. Consisting primarily of bacteria, plaque also contains dried saliva, blood cells, and food particles. It accumulates at the base of the teeth, in the grooves of the teeth's occlusal (chewing) surfaces, and in the spaces between the teeth. When still sticky, the simplest way to remove it from tooth surfaces is to wipe it off with a cloth. A common alternative method is to thoroughly chew a green twig from a non-poisonous plant until it becomes soft and fibrous. The end can be used to brush the teeth and gums. Eventually, this sticky, mineralized deposit (calculus) hardens and requires formal removal. At that point, it must be scraped off with a thin, bent metal tool. Dentists use a "scaler" or "dental pick." Alternatively, practitioners can use a small blunt needle to make a suitable instrument. First, cut off and sand the sharp end of the needle. Then, bend the end and attach it to a small syringe, which becomes a handle.

Oral Lesions

Many types of lesions can cause pain and swelling in the mouth and face.2,3  Table 23-1 provides a brief overview of the presentation, diagnosis, and treatment of various causes of mouth and jaw pain.

Mucosal Diseases and Facial Swelling

The most common painful oral lesions are aphthous ulcers (canker sores), traumatic ulcerations, and cold sores (Herpes labialis), and all can be treated with "tincture of time." They may heal faster, and pain may also be reduced, if they are covered. All three can be covered, at least for several hours, with any lip balm or salve, such as petroleum jelly. These usually relieve the pain—until they are licked off. As effective and possibly longer-lasting is cyanoacrylate (e.g., commercial Super Glue and multiple brands for medical wound closure).4

Multiple intra-oral lesions, including mucositis in immunocompromised (e.g., cancer, AIDS) patients, may be helped by "magic mouthwash." Patients use magic mouthwash by taking a mouthful every 2 to 3 hours, swishing it around in their mouth, and spitting it out. The solution can be made with any of dozens of formulations. The most common basic elements for magic mouthwash are diphenhydramine (e.g., Benadryl) elixir, viscous lidocaine 2%, and a liquid antacid, such as Maalox. Other common ingredients are tetracycline or erythromycin (that may be helpful with bacterial infections in the mouth) or, especially for cancer and immunocompromised patients, a steroid such as dexamethasone or hydrocortisone, or nystatin. One common formula uses 4 parts nystatin suspension 100,000 units/mL, 3.5 parts diphenhydramine elixir, and 1 part lidocaine viscous 2%. If the solution is made with a substance such as Kaopectate or sucralfate (Carafate), the ingredients can adhere to surfaces, and so can be applied directly to the intra-oral lesions.

A very common oral lesion is candidiasis (thrush). If standard oral agents are not available, treat oral candidiasis by having the patient suck on a vaginal anti-yeast suppository or apply a vaginal anti-yeast cream to the lesion 4 times a day.

Gum Inflammation and Pain

Painful gums can result from poor oral hygiene, infections, inflammation over an erupting tooth, or dental appliances such as orthodontics.

To avoid or treat inflamed gums resulting from poor oral hygiene, patients gently brush their teeth and gums and by floss with dental floss or a substitute. They also can rinse their mouth with warm saltwater (0.5 tsp table salt in 4 oz of warm potable water) or a solution containing 1 part potable water and 1 part 3% hydrogen peroxide (H2O2) several times a day.5

More serious, and much more painful, is necrotizing ulcerative gingivitis, also known as trench mouth, Vincent's angina or stomatitis, or necrotizing ulcerative periodontitis. This serious but treatable disease of the gums and deeper tissues usually begins abruptly; the patient may be febrile. The gums are very painful and bleeding, with punched-out ulcers covered with a gray pseudo-membrane. Patients have extremely foul breath, pain on talking or swallowing, and may have lymphadenopathy. Treatment consists of gently debriding the area over several days. Wipe the gums with cotton or other absorbent cloth soaked in 3% H2O2. Use 1 part H2O2 to 5 parts water in children. Then scrape off the larger pieces of tartar. Have the patient gently brush their teeth and gums daily with a soft brush and rinse every waking hour with warm saltwater or twice a day with 1.5% H2O2 or 0.12% chlorhexidine. For the pain, use non-steroidal analgesics and, if available, local anesthetic on the gums—after drying them. Encourage patients to avoid spicy foods and to improve their diet. They may need to be on a liquid or soft diet for a while. They should drink lots of liquids, take supplemental vitamin C, and avoid smoking and chewing betel nuts or tobacco. If thorough cleaning and debridement is not available, give oral penicillin VK 500 mg, erythromycin 250 mg, or tetracycline 250 mg q6hr until 72 hours after the symptoms resolve.

Pericoronitis occurs when inflammation develops around a partially erupted (usually molar) tooth. A flap of gingival tissue remains over the tooth, which traps food particles and is irritated by chewing. Local swelling may cause enough irritation to make it difficult to fully open the jaw. To treat this, gently irrigate the area under the flap. Have the patient rinse his mouth with warm saltwater for 10 minutes every 2 hours while awake. If no dentist will be available within a few days, excise the flap over the tooth.

If orthodontic appliances are causing pain, use a blunt object, such as a tongue depressor or pencil eraser, to bend the wire away from the gum. If it cannot be bent, cover it with wax (candle or dental) or a tiny piece of cloth or cotton. Paradoxically, chewing (preferably sugarless) gum reduces the general pain caused by orthodontic appliances.

Toothache

Most of the cases for which non-dentists will need to provide emergency dental treatment will be for toothaches. While teeth can be transiently painful for a number of reasons, constant, often excruciating pain in a tooth constitutes a toothache. Generally, toothaches are caused by fractures or decay (caries; causes cavities) that extends into the tooth's central area (pulp). A tooth in which the pulp is no longer healthy often has a history of persistent, often severe and throbbing, pain after eating hot or cold food. Cold stimulus causes prolonged pain, but the tooth is generally not sensitive to palpation.

Diagnosis

To locate the painful tooth, have the patient point to it or gently tap on teeth in the affected area with an instrument until the patient experiences discomfort. When a tooth is tender to percussion, it is likely that there is a periapical abscess. The affected tooth can also be located by touching it with the corner of an ice cube. A normal tooth will briefly feel the cold stimulus; a diseased, but salvageable, tooth with some healthy pulp may have slightly more prolonged pain after withdrawal of the ice and is not usually sensitive to percussion. These can be treated as described in the subsequent paragraphs. Be sure to check adjacent teeth for their relative sensitivity to percussion and cold. An unsalvageable tooth generally has no sensation to percussion or a cold stimulus.

Table 23-2 provides a method of diagnosing about 90% of non-trauma-related toothaches. However, for the clinician faced with a patient's sore tooth, this table may not help in differentiating between an abscess and pulpitis. (Pulpitis is inflammation of the pulp, or center, of the tooth that contains vessels and nerves). To make this differentiation easier, remember the mnemonic PAIN to indicate that pain on Percussion (the tap test on the tooth) = Abscess (periodontal or periapical) and pain with Ice (test the tooth by touching ice to it) = Nerve pain (pulpitis).

Treatment

First try to treat a toothache conservatively. Have the patient rinse vigorously with warm water. Then clean out the tooth defect and insert an analgesic gauze or filling. (See "Filling Cavities" in Chapter 24, Dental: Fillings, Extractions, and Trauma.) The cleaning can be done using dental floss, a toothbrush, a toothpick, or a similar narrow and relatively blunt tool. If an abscess is present, treat accordingly.6 (See "Dental Abscesses," below.)

Using small tweezers, a hemostat, or a similar instrument, put a very small piece of cotton or other cloth soaked in local anesthetic, such as oil of cloves (long-acting) or benzocaine, into the cavity or over the fracture site. A paste of oil of cloves and zinc oxide can also be used effectively, if available. When using oil of cloves rather than the less-potent commercial products containing eugenol, avoid using too much or letting it drip onto the gums or mouth tissues, since it causes mucosal burns. This provides immediate, but temporary, pain relief.

Cover this anesthetic dressing with a temporary soft putty-like filling material that can be molded to the cavity. Wax from a candle can be used: melt some wax, let it cool until it is pliable, and then place it over the affected area. An alternative is to use cyanoacrylate glue.

If this doesn't work, open the pulp chamber (center of tooth) to drain the tooth. As a last resort, extraction may be necessary (see "Extractions" in Chapter 24, Dental: Fillings, Extractions, and Trauma).

Dental Abscesses

Dental (periapical and periodontal) abscesses are adjacent to the affected teeth. The presence of abscesses can often be recognized by swelling of the cheek, the mouth, or the neck. The adjacent tooth will generally be very tender to gentle percussion. The patient with a periapical abscess may also have increased pain when recumbent, have a bad taste in his mouth, or say that the tooth feels "longer" than adjacent teeth. In addition, he may have a gumboil (an abscess under the gum at the end of a sinus tract extending from the periapical abscess). The abscess may also develop into facial cellulitis with significant swelling. Periodontal abscesses may be more localized than periapical abscesses and usually result from chronic gingival disease, rather than caries.

Treat these by having the patient rinse the abscessed area with warm saltwater for 10 minutes every 2 hours while awake. This may provide some immediate relief and can help the abscess drain spontaneously. Apply ice to the face. Nonsteroidal analgesics may decrease the pain; opioids may be required.

If no dental care will be readily available and the abscess is pointing, drain it using a scalpel, needle, or fishhook that has been thoroughly cleaned. Be sure to remove the barb before using a fishhook. Subsequent warm saltwater rinsing, although initially painful, will help the drained abscess resolve more quickly.

If the tooth is loose due to the abscess or, if not, as a last resort after more conservative treatment has failed, extract the tooth (see "Extractions" in Chapter 24, Dental: Fillings, Extractions, and Trauma). Since the tooth acts similar to any infected foreign body (such as a splinter), the infection is best treated by removing the tooth as soon as possible once it is determined that the tooth cannot be salvaged. (Daniel Kemmedson, DMD, personal written communication received June 5, 2008.) If extraction is not possible, treat the patient with antibiotics, if available, to cover mouth flora (usually penicillin); have the patient use warm moist soaks over the affected area and warm water rinses in the mouth.

Antibiotics

Since antibiotics may be scarce, it is worthwhile to consider whether they are necessary for dental lesions.7 While antibiotics may not make a difference in most outcomes, "without good radiographic and pulpal evaluation or good follow-up, and [given] the potential of serious deep-space infection risk, antibiotics should probably be prescribed for at-risk patients."8 So, prescribing antibiotics will depend on both the specific circumstances and the availability of the medication. If used, antibiotics for dental infections include penicillin VK 500 mg po qid, erythromycin 500 mg po qid, and clindamycin 300 mg po tid.

Lost Filling or Lost Crown (Cap)

If a dentist-formed crown, otherwise known as a "cap," is lost, gently clean out the hole where the filling resided. Do not try to replace the cap unless the patient is in so much pain that there is no other choice or if dental care will not be available in a timely manner. Save the cap for a dentist to use at a later time. The danger in replacing the cap is that it could come off again and the patient might aspirate it. In the meantime, the exposed pulp can be covered with softened candle wax, cyanoacrylate, or a commercial temporary tooth filling material.

If a cap must be replaced by a non-dentist, gently clean out any residual cement from the inside of the cap with a very small knife, paperclip, the filament from a lightbulb, or similar tool. Then place a thin layer of dental filling, denture adhesive, cyanoacrylate, or a thick mixture of flour and water inside the crown. Having the patient gently bite down on the replaced cap helps position it correctly. Remove any excess material. Advise the patient not to use that tooth when eating; the cap will most likely come off.

Cavities

If a tooth has a cavity but is not abscessed, try to put in a temporary filling. (A permanent filling requires the skill and equipment that only a dentist can provide.) This decreases the chance of further tooth decay, prevents an abscess from forming, decreases the patient's pain, and may ultimately save the tooth.9

Do not put a filling in an abscessed tooth! It will only make the pain and swelling worse. If the tooth has an abscess and you are in a situation with few resources and no dentist, pull the tooth. (Even if you break the tooth, it will allow the abscess to drain, improving the patient's condition.9)

Chapter 24, Dental: Fillings, Extractions, and Trauma, provides detailed information on how to do fillings and extractions.

If dental instruments (hand tools) are available, great! If not, they can often be fashioned from many different items. For example, Native healers fashion knives and dental extractors from beaten iron nails.10

Use small, thin, flat screwdrivers to loosen teeth by breaking the periodontal ligaments before extracting them. Don't use them to lever one tooth against another.

General Equipment

Before beginning any dental procedure, three things are necessary: the patient should be correctly positioned, there should be adequate light, and you should have a way to dry and isolate the tooth.

Chair

A key element of successful dental work is not to be bending over. Raise the patient's mouth to a level where you can work comfortably. The patient is most comfortable if his head, back, and neck are supported. One method of putting the patient in the proper position for dental work is to use a regular office-type chair, back it up to a desk or table, and place the patient's head on several pillows on that surface.6 Modify a chair with two side posts (Fig. 23-4) by securely attaching two pieces of wood or metal and tying a cloth between them. Have the patient rest his head on the cloth. You can also use a low chair with a back. If the chair is too low for you to work comfortably, have the patient sit on books.

Headlamp/Light Source

A headlamp is standard equipment for all surgical procedures in austere situations. If you don't have a headlamp, use any available light source, including a lamp, laryngoscope, or fiber-optic light. To direct the light so that it illuminates the part of the patient's mouth you are working on, use a hand mirror or have someone hold the light source (or a mirror) in the best position. To work in the sunlight, position the patient toward the sun. (In some cases, you may want to cover his eyes.) If indoors, position the patient to face the window.

Secretion Barriers

To isolate a tooth from mouth secretions, position cotton rolls or 2 × 2 gauze squares inside the lip next to the tooth and between the tongue and the tooth. If working on a maxillary tooth, place the gauze or cloth roll over Stensen's duct (opening of the parotid salivary gland).

Dental Drill

Dental drills should only be used by trained dentists.

Mirror

Use a mirror to reflect light onto the field of operation, to view the cavity indirectly, and to retract the cheek or tongue as necessary. A mouth mirror can be fashioned by taping the edges of a small piece of broken mirror (to protect the patient from the sharp edges) and gluing it onto the end of a short piece of a coat hanger or other relatively stiff metal wire.

Needed to Fill Cavities

Besides a headlamp and a mirror, a standard set of instruments to apply a temporary filling includes the following items:

Probe (Explorer)

Use a probe (Fig. 23-5) to identify where soft carious dentine is present. Take care not to penetrate very small caries (this may destroy the tooth's surface) or obvious deep cavities (this may damage the pulp). A probe can be fashioned from a small (23- or 25-gauge) needle that has the tip filed off and is bent on the end. Use a small syringe or wooden dowel (e.g., Q-tip, cotton swab) as a handle.

Cotton Pledgets/Absorptive Gauze

Use cotton pledgets or any small pieces of absorptive gauze to soak up any saliva and keep the work area dry.

Mixing Block and Tool (Cement Spatula)

If a polymer with two components, generally a liquid and a powder, is used, these have to be mixed. A piece of glass or a rigid plastic sheet will work as a mixing block. A piece of wood can be used as a spatula.

Tweezers (Pickups)

Use a tweezers to place materials in the mouth. This is more elegant than using your fingers, which are what you use if tweezers, hemostats, or similar devices are not available.

Dental Hatchet

This is used to widen the entrance to a cavity so there is better access for the excavator. It is also used to remove the thin, unsupported carious enamel that remains after carious dentine has been removed. A thin piece of rigid metal, such as a large-gauge (12- or 14-gauge) needle with its point filed off, should be used. It helps if it is bent at the end.

Spoon (Spoon Excavator)

Use a spoon excavator to remove soft carious dentine. A needle that fits into the carie can be used instead. The sharp tip can be filed down to make it easier to use.

Filling Tool (Filling Instrument)

If a dental filling tool to put the filling material into the cavity and smooth it over is not available, use a small thin piece of metal. If using cyanoacrylate, the top of the tube often works well.

Sterilizing Dental Equipment

While the mouth is not sterile, failing to sterilize dental equipment between patients can lead to transmission of serious diseases, such as hepatitis and HIV. Before sterilizing instruments, they should be cleaned of any visible grime. Chemically sterilizing dental equipment is inadequate. Likewise, standard boiling-water devices are not effective. In austere environments, use dry-heat ovens with an uninterrupted cycle, including a holding time of 60 minutes at 160°C (320°F).11 Whenever possible, autoclaving should be used to sterilize dental instruments.

Cyanoacrylate (e.g., Super Glue) as a surgical adhesive is discussed more thoroughly under "Wounds" in Chapter 22, Wounds and Burns.

To use any cyanoacrylate properly, all surfaces must be dry. Use gauze, tissue paper, or cloth to dry the affected tooth and to keep saliva away from it during the process. Use the top of the cyanoacrylate tube or a small piece of metal to keep pressure on the tooth for the few seconds it is drying. Try not to use your fingertip, since that will result in its being stuck in the patient's mouth for a while. After the glue sets, have the patient salivate and wet the entire area at once.

While gluing the gums may be part of the stabilization for some dental problems, if the application of glue to the gums is not necessary for the procedure, try to keep the glue off the gums. Glue near the gums can irritate them; excess glue also can form a rough edge that irritates the tongue. The latter can be corrected by carefully filing the edge or by covering the area with a small amount of additional glue.

Using the glue so that the bite is normal can be a problem when repairing dentures or teeth. People notice even the smallest change in their dental occlusion. Excess glue can be filed down. See the method for optimizing the patient's bite using carbon paper in Chapter 24, Dental: Fillings, Extractions, and Trauma ("How to Fill a Tooth," step 6). Even if the fit is not perfect, whatever you can do will probably improve the situation. As a non-dentist, you are using these techniques only to buy time until the patient can see a dentist.

If cyanoacrylate is used, the patient should be warned not to put too much pressure on the tooth and to try not to bite with it. These dental repairs generally last days to weeks, but eventually the procedures must be redone. Of course, if the patient can see a dentist, that is optimal.

Cyanoacrylate adhesives can be used for many dental problems. These include protecting or repairing oral soft tissues, repairing dentures and teeth, and even protecting hypersensitive teeth.

Oral Soft Tissues

People have applied cyanoacrylate to aphthous lesions (canker sores) for many years to reduce the pain. One need only apply the glue to the lesion. It remains until the moisture of the lip and natural turnover of skin make it peel off. Of course, anything that covers the lesion (such as a lip balm) will lessen the discomfort. In 1999, the US Food and Drug Administration (FDA) approved a cyanoacrylate (Colgate Orabase Soothe-N-Seal Liquid Protectant) for over-the-counter use in the treatment of aphthous ulcers, mouth sores, and traumatic ulcerations. This formulation has much less tensile strength than do the standard medical formulations and will slough off in only 6 to 10 hours; so it may have to be replaced if continued coverage is needed.12

Cyanoacrylate is also useful for repairing abrasions and lacerations to the lip and oral mucosa.13,14 Perhaps because of its occasionally unpleasant taste, some people have tried to develop flavored products. Cyanoacrylate has been used for wound closure in oral surgery; it compares favorably with sutures, showing normal healing of incisions and immediate hemostasis. It has also been useful in relieving the pain when dressing donor sites and mucosal ulcerations, while helping them to heal quickly.14

Orthodontic Appliances

Cyanoacrylate can also be used to re-bond loose orthodontic brackets, although care must be taken to be sure they remain in the correct location.15

Denture Repair

Cyanoacrylate can be used to temporarily glue a tooth or part of a tooth back into a denture (dental prosthesis). The glue may not be strong enough to repair a denture that breaks in half, depending on the denture material.16 If the denture is made of acrylic, it can be repaired using cyanoacrylate adhesive. In the developing world, acrylic is still widely used for dental prostheses because of its relatively low cost.

When doing these repairs, the dentures must be properly aligned. If done incorrectly and the dentures no longer fit well, the adhesive can be very difficult to remove.17

Dental Trauma

As noted above, cyanoacrylate can be used to repair tooth fractures, to glue on pieces of fractured teeth, and to attach temporary dental splints.18

Filling Cavities

Cyanoacrylate has been shown to be very effective in filling holes for root canals. It also controls micro-leakage of oral fluid at the tooth–filling interface, and so is effective, at least temporarily, for filling a cavity.19,20

Gluing Avulsed Teeth

While gluing in avulsed teeth may help temporarily, and has been used to temporarily keep avulsed teeth in position, it is best to use cyanoacrylate as part of a splinting process as described above. One patient was found to have repeatedly used cyanoacrylate over a year to retain an avulsed second upper incisor.21 Another man, who had four adjacent maxillary teeth fractured in a baseball game, glued them to each other and repeatedly glued the group back onto adjacent teeth over a period of a year until seen by a dentist (and, since he was lost to follow-up due to a lack of insurance, probably after that). His technique was to first carefully dry the crowns and roots that were broken, and glue them together with nonmedical cyanoacrylate while in the correct position in his mouth. The four teeth were also bonded together. (Having used a larger amount of glue than necessary, it adhered to his palate but separated "after a few hours.") He then removed the four-tooth piece and "shaped it with a file," reinserting it into position and gluing it to the adjacent teeth. He removed the four-tooth piece every 4 to 6 weeks, cleaned it, filed it as necessary to improve the fit, and re-glued it to adjacent teeth. While he initially used the liquid cyanoacrylate, he eventually switched to the gel, which worked better. The patient's lack of pain during the initial procedure was attributed to the pulp (and nerves) being dead.22

Hypersensitive Teeth

Cyanoacrylate has also been shown to be more effective than some standard methods for treating hypersensitive teeth. The hypersensitive area is dried and cyanoacrylate applied and allowed to dry. Patients then rinse their mouths thoroughly with lukewarm water. For approximately half of all patients, the treatment lasts for about 3 months; it can then be repeated.23

Analgesics

Oral analgesics effective for most dental problems include acetaminophen 650 to 1000 mg q6hr and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen 400 to 800 mg q6hr. For severe pain, these drugs may be combined with opioids, such as 5 mg codeine.24

Local Anesthetics for Dental Blocks

Standard local anesthetics can be used for dental blocks, with or without epinephrine. Two easy methods are available to dose children with local anesthetics. The first is Clark's rule, which says that the maximum dose of any local anesthetic = (weight of child in lb/150) × max adult dose (mg). For example, the dose of lidocaine without epinephrine for a child weighing 50 lb would be: (50 lb/150) × (2.0 mg/lb × 50 lb) = 1/3 × 100 mg = 33 mg.

An even simpler method is to use 1.8 cc of 2% lidocaine/20 lb. The volume of a normal dental anesthetic "carpule" used in dental syringes is 1.8 cc.

Blocking Individual Teeth

Supraperiosteal Infiltration

Supraperiosteal infiltration can be used to block individual teeth. If topical benzocaine (20%) is available, first apply it to the injection site using a cotton swab. Then retract the lip and shake it to get access and provide some mechanical anesthesia (or useful distraction). Using a 25-, 27-, or 30-gauge needle (or the smallest gauge available), enter at the junction of the lip and the gum directly over and parallel to the long axis of the affected tooth. Advance the needle 3 to 4 mm and inject 0.5 cc of 2% lidocaine with 1:100,000 epinephrine or 0.5% bupivacaine (Marcaine) with 1:100,000 epinephrine (adults). Repeat the procedure, as needed. If a mandibular tooth is being blocked, more anesthetic will be needed because the mandibular bone is denser than the maxilla.25 (The maximum dose of bupivacaine for intra-oral injection is 90 mg. The maximum intra-oral dose of lidocaine with epinephrine or articaine with epinephrine is 500 mg.)

Infraorbital Block

While an infraorbital block is actually a regional block for the upper (maxillary) incisors, the upper lip, and the side of the nose, the procedure is a simple extension of supraperiosteal infiltration. (See Fig. 25-9.) The needle inserted over the upper canine tooth need only advance about 2 cm, so that needle tip is over the most prominent part of the cheek (malar eminence). Experience shows that injecting 2 to 3 cc of 2% lidocaine with or without epinephrine works nearly 100% of the time and is very effective.

Regional Blocks

Inferior Alveolar Block

This blocks all mandibular teeth on the side injected and, if done correctly, can also block the side of the tongue.

Procedure

The needle is directed through the mouth from the opposite side to the side to be blocked. The operator's thumb is placed in the coronoid notch of the mandible, and the index finger is on the mandible external to the mouth (Fig. 23-6). The coronoid notch can be located by passing the thumb over the lower molars until it contacts the mandibular ramus. The notch is the hole that the thumb tip naturally falls into when doing this.

A 25- or 27-gauge needle is directed toward the mucosa on the medial border of the mandibular ramus. Generally, this should be just next to (just medial to) the tip of the thumb in the coronoid notch. This should place the needle 6 to 10 mm above the mandibular molars. Insert the needle about 25 mm (1 inch) and, after a negative aspiration, inject ~0.5 to 1.5 cc of local anesthetic, such as bupivacaine. Continue to aspirate and inject ~0.5 to 1.0 cc on removal from injection site to anesthetize the lingual branch (side of the tongue).

Inject another 0.5 to 1.0 cc of anesthetic into mandibular coronoid notch (where the thumb was, just distal to the last molar) to perform a long buccal nerve block. This anesthetizes the buccal surface of the mandibular molars and adjacent gum.

Gow-Gates Technique: Alternative to Inferior Alveolar Block

The Gow-Gates mandibular block is another technique for mandibular anesthesia, especially when the standard inferior alveolar nerve block fails to supply adequate anesthetic effect. It anesthetizes the inferior alveolar, lingual nerve, and the long buccal nerve with one injection.26

Perform the Gow-Gates block by inserting the needle higher than with a standard alveolar block. The technique will anesthetize the mandibular teeth to the midline, the buccal tissues and bone, the floor of the mouth and tongue to the midline, lingual tissues and bone, the body of the mandible, and the skin over the zygoma.

Technique

Insert a 25- or 27-gauge needle distal to the last (second or third) molar on the medial surface of the mandibular ramus. Guide the needle on an imaginary line from the intertragic notch (ear) to the corner of the mouth (Fig. 23-7). Use a thumb in the coronoid notch and the index finger over the head of the condyle. (Find the head of the condyle at the temporomandibular joint by having the patient open and close his mouth to feel it move.) The needle is aiming for the head of the mandibular condyle. Keep the barrel of the needle approximately over the mandibular premolars on the same side and insert the needle using the landmarks of the tragus and second molar. Keep the needle parallel with the imaginary line from the corner of the mouth and the intertragic notch and advance the needle slowly until bone is contacted. This will be the head of the condyle. Insert the needle to the same depth as for the inferior alveolar nerve block—about 25 mm in an adult. If bone is not contacted, slightly withdraw the needle and reinsert it.

Once the needle contacts bone, withdraw it about 1 mm and aspirate. Positive aspiration for this injection occurs less often than with similar blocks (<2% of the time), but aspiration is still necessary. If positive, the needle is probably in the internal maxillary artery, inferior to the target. In that case, withdraw the needle, get new anesthetic solution, and redirect the needle superiorly to the previous injection site.

If the aspiration is negative, slowly deposit ~2 to 3 cc of local anesthetic. After the needle is withdrawn, have the patient keep his mouth open for a few minutes for the anesthetic to properly diffuse and until he reports signs of inferior alveolar anesthesia.26 To help the patient keep his mouth open, have him bite down on the syringe you just used. Onset of anesthesia may take longer because the nerve is denser at this point and the area of deposition is somewhat farther from the nerve. The patient's tongue and lower lip should be numb. Check all areas for anesthesia before proceeding with treatment.27

Infraorbital Block

Infraorbital blocks are discussed in Chapter 25, Otolaryngology (ENT).