Endodontic Emergencies

Definition-   

 The reason for endo- dontic emergency treatment is pain at times, swelling ensuing from pulpoperiapi- cal pathosis. Because dental pain has many causes, the adept clinician must diagnose the origin of the pain as quickly as possible, to render rapid and effective relief.

The following classification of emergencies and procedures is designed to simplify the selection of an effective method of treatment. 

ACUTE REVERSIBLE PULPITIS

Acute reversible pulpitis (hyperemia) can be treated successfully by palliative procedures.  The diagnosis and origin of the condition can be confirmed by visual, tactile, thermal, and radiographic examination of the isolated tooth.

If a recent restoration has a premature contact point, recontouring this high spot will usually relieve the pain and allow the pulp to recuperate. 

If persistent painful episodes occur following cavity preparation, chemical cleansing of the cavity, or leakage of the restoration one should remove the restoration and replace it with a sedative cement such as zinc oxide- eugenol cement. 

The best treatment is prevention, one should place a pulp protective base under all restoration, avoid marginal leakage, reduce occlusal trauma if present, properly contour all restorations, and avoid injuring the pulp with excessive heat while preparing or polishing a metallic restoration.        

Following palliative treatment, such as the application of a zinc oxide-eugenol cement as a temporary sedative filling, the pain should disappear within several days. If it persists or worsens then the pulp should be extirpated.

ACUTE IRREVERSIBLE PULPITIS

The preferable emergency treatment for both types of acute irreversible pulpitis (ab- normally responsive to cold or to heat) is  pulpectomy.

 Teeth affected by either acute reversible pulpitis or irreversible pulpitis are abnormally responsive to cold and have many similar symptoms. It is therefore essential that they be distinguished from one another because the emergency procedure for each is different. 

If a patient describes pain that lasts for minutes to hours, or is spontaneous , or disturbs sleep, or occurs when bending over, most likely that patient will require pulpectomy of the affected tooth rather than palliative therapy for relief of the

The technique for pulpectomy is as follows

1. Anesthetize the affected tooth.

 2. Apply the rubber dam. 

3. Prepare an access cavity into the pulp chamber. 

4. Remove the  pulp from the chamber with excavators or curettes. 

5. Irrigate and debride the pulp chamber. 

6. Locate the root canal orifices and explore the root canals.

7. Extirpate the pulp by sequentially instrumenting with reamers or files to within 1 mm of the radiographic root apex.

8. Irrigate with sterile saline solution, anesthetic solution, or sodium hypochlorite solution.

9. Debride with a barbed broach, fitted loosely so it can be rotated in the root canal without binding, usually following  instrumentation with at least a No. 25 reamer or file to the root apex.

 10. Dry the root canal with sterile absorbent points. 

11. Insert a medicated cotton pledget,moistened with an obtundent such as eugenol, into the pulp chamber. 

12. Place a temporary filling such as Cavit or fast-setting zinc oxide-eugenol cement over the medicated dressing and seal the access cavity.

13. Relieve any occlusal trauma.

 14. Prescribe an analgesic for use only if pain recurs. Premedication or post- treatment medication with antibiotics is indicated only if the patient's condition is medically compromised or if systemic toxicity occurs subsequently.

 15. Consult with the patient to alleviate any anxiety concerning the emergency procedure or potential postoperative re- action, and assure the patient of your availability. 

ACUTE ALVEOLAR ABSCESS

What is an acute alveolar abscess? 

An acute alveolar abscess (acute periapical abscess, acute apical pericementitis, phoenix abscess) is a localized collection of pus in the alveolar bone at the root apex of a tooth fol- lowing death of the pulp, with extension of the infection through the apical foramen into the periapical

Clinical features-

 It is accompanied by a severe local reaction and, at times, a general reaction of systemic toxicity such as elevated temperature, gastrointestinal disturbance, malaise, nausea, dizziness, and other symp- toms related to continuous pain and lack of sleep. 

The acute episode may result from pulpitis that progressively developed into pulp necrosis affecting the periapical tissues; it maybe joan exacerbation of a chronic periapical lesion; or it may be caused by an endodontic periodontic lesion when the periodontal abscess secondarily affects the pulp through the lateral root canals or a deep infrabony pocket that extends to or beyond the root apex To relieve this constant pain, one should establish  drainage through the root canal, preferably, and through the soft tissue and bone, necessary . 

Treatment

The emergency treatment of acute alveolar abscess differs from that of acute irreversible pulpitis. Because the pulp is necrotic, local anesthesia is not needed routinely. In fact. local anesthesia is frequently contraindicated in acutely inflamed tissue because the injection of an infiltration anesthetic does not anesthetize the tissue. 

Acutely inflamed tissue has a localized pH that is acidic in spite of the body's natural buffering action. Local anesthetics are effective in tissue with a more alkaline pH and, as a result, are in- effective when injected into acutely inflamed tissue. In addition, insinuating a needle and forcing anesthetic solution into an acutely infected and swollen area may increase pain and may spread infection.

Conduction anesthesia may be administered to reduce the pain of acute alveolar abscess, as long as the injection route is distant from the inflamed area. A mandibular block or an infraorbital injection can be used effectively when needed for the few isolated cases in which some pulp vitality persists. Because most of the pain that occurs during  access-cavity preparation is caused by tooth movement resulting from vibration of the high-speed bur, one should stabilize the tooth with finger pressure so penetration into the pulp chamber will be painless The value of the test cavity in treating teeth with acute alveolar abscess is twofold. First, it tests for any remaining vital pulp that could require anesthesia; and second, it initiates emergency therapy quickly, because the pulp chamber can be penetrated painlessly with- out delay, waiting for anesthesia to take  effect.

To complete the emergency treatment of an acute alveolar abscess, the following procedure is recommended:

1 . Place the rubber dam over the infected tooth. 

 2. Complete the access opening painlessly by bracing the tooth with finger pressure. 

3. Irrigate profusely, debride the pulp chamber, but avoid forcing any solution or debris into the periapical tissue. 

4. Using a No. 10 or No. 15 file or reamer as an explorer, locate the root canal orifices and instrument each root canal within 1 mm of the root apex.

5. Continue to debride and to irrigate while enlarging each root canal, but keep all instruments and irrigants within the root canals.

6. Frequently, a purulent exudate escapes into the chamber and indicates that the root canal is patent and draining; relief follows quickly. If no evidence of drain- age appears, leave the tooth open, its root canals patent, and expect relief within a short time.

7. Advice the patient to use hot saline rinses for 3 min each hour. 

8. Prescribe analgesics Or antibiotics if indicated and necessary. 

In mild cases of acute alveolar abscess, the tooth may be sealed with an antiseptic,  obtundent  medicament after biomechanical preparation of the chamber and root canals Leaving the tooth open for drainage, however, reduces the possibility of continued pain and swelling.

 The open-drainage technique is preferable lo one in which the pre- pared root canals are sealed followed by incision of the soft tissue and artificial fistulation of the bone to establish drainage. Open root canals permit drainage and frequently eliminate the need for a surgical incision as well as the routine administration of oral antibiotics and analgesics .

Nevertheless, some clinicians suggest that all acutely abscessed be sealed with an intracanal medicament after initial emergency instrumentation.  They claim that leaving a tooth open continues the bacteriologic contamination and increases the risk of adverse reaction when the tooth is resealed. They claim that the bacterial contamination prolongs the treatment time needed to overcome the resulting infection. 

The pain of an acutely abscessed tooth, whether of periapical or periodontal origin, is frequently accompanied by swelling.

 If the swelling is slight and is localized, it will disappear 24 to 48 hours after drainage has been established. Routinely, hot saline rinses should be prescribed to assist drainage.

 If the swelling is extensive, soft, and fluctuant, an incision through the soft tissue to the bone may be necessary . One should first dry the mucosa over the affected area, then spray the tissue with a refrigerant topical anesthetic such as ethyl chloride. The intraoral incision is made through the soft, fluctuant swelling to the cortical bone plate. A rubber dam or gauze drain may be inserted for several days. If the swelling is hard, it can be converted to a soft, fluctuant state by rinsing with hot saline solution 3 to 5 min at a time, repeated every hour. Antibiotics and anal- gesics can be prescribed as needed. Finally, the tooth should be disoccluded slightly if it is extruded from its socket. This procedure eliminates pain caused by contact with teeth in the apposing arch.

ACUTE PERIODONTAL ABSCESS

An acute periodontal abscess causes pain and swelling. It is often mistaken for an acute alveolar abscess. Although the acute perio- dontal abscess (parietal abscess) can occur with either vital or necrotic pulp, its origin is usually an exacerbation of infection with pus formation in an existing deep infrabony pocket. If the pulp tests indicate pulp vitality within the normal range, then emergency treatment consists of curettage, debridement, and  establishment of drainage of the infra- bony pocket through the sulcular crevice. At times, incision of the soft tissue is necessary. If the pulp is affected, it must be extirpated as well. 

When the pulp is abnormal and vital the tooth is treated as if for acute irreversible pulpitis. If the pulp is necrotic, the tooth should be treated as if for acute alveolar abscess. In any case, emergency periodontal treatment must be done simultaneously, otherwise, the patient will not be relieved of the pain and swelling."

EMERGENCIES DURING TREATMENT

Endodontic emergencies can occur during the course of endodontic treatment. They are usually caused by instrumentation beyond the root apex, with resultant trauma to the periapical tissue, or when debris and micro organisms are forced through the apical foramen into the periapical tissue and cause an infectious reaction.

 Other causes may be chemical irritants, such as irrigating solutions or intracanal medicaments, penetrating the periapical tissue, incomplete or inadequate debridement of all root canals, lost or depressed access-cavity seals, with resulting recontamination of the root canals, or over- filled root canals with subsequent periapical inflammation. These emergencies can be avoided if instruments, irrigating solutions medicaments, cements, and filling materials are confined to the root canals themselves and teeth under treatment are properly sealed between visits and are recontoured to prevent trauma.

Ideally, an endodontic emergency should not occur during  treatment; however, it does occur occasionally.

Patients should be warned during endodontic instrumentation that a reaction may occur within the next few days and that, if it does, it can be controlled by medication, usually a mild analgesic such as aspirin. 

When severe periodontitis is present, the patient's pain can be relieved by reopening the tooth under the rubber dam, removing the sealed medicament, carefully wiping the root canal dry with sterile absorbent points, and resealing the root canal with a cotton pellet from which a mild obtundent, such as eugenol or cresatin, has been expressed. The occlusion should be adjusted if necessary.

If pain or swelling occurs, the sealed medicament should be removed and the tooth opened for drainage. Analgesics should be prescribed, opioid or nonopioid, depending on the severity of the reaction. If indicated. antibiotics may be prescribed as well. Incision and drainage of a soft, fluctuant swelling should be considered when drainage is in- sufficient or when severe pain persists.

When the root canals have already been filled and discomfort is present, the occlusion should be checked and the completed treatment and root canal fillings re-evaluated. 

Slight overfilling of the root canals with either the core or cement often causes a tran- sient discomfort, but it may persist in some cases. When relieving the occlusion has not had the desired effect after a week or so, a prescription for a corticosteroid and anti- biotic may be given to the patient, such as dexamethasone (Decadron) (0.50 mg) and erythromycin (250 mg) each taken 4 times a day for 4 to 5 days. 

The routine use of an antibiotic is contraindicated, however, and a corticosteroid should not be prescribed for patients with hypertension, gastric or duodenal ulcers, or diabetes. At times, the root canal filling must be removed, to relieve the pain and to establish drainage. In such cases, treatment should be as for an acute alveolar abscess.

When a post-crown restoration cannot be removed and an acute abscess is present, an incision and drainage should be considered if the swelling is soft and fluctuant, and an antibiotic should be prescribed. If the swelling is hard, hot mouth rinses should be recommended, and an antibiotic should be prescribed to control the infection.

In some cases, if relief is not obtained, trepanation (artificial fistulation) of the bone over the root apex may be necessary. 

CROWN FRACTURE

A traumatic injury to a tooth can cause a cracked crown, a fractured crown, or a frac tured root and may result in pain. 

Symptoms -

A cracked tooth can elicit bizarre symptoms such as sharp, piercing pain, especially during masticstion .  At times, thermal changes cause fleeting painful reactions. Observation of a hairline crack in a tooth confirms the diagnosis, but the crack may be difficult to detect. Transillumination or a dye can be used to disclose the crack line in the tooth . A rubber polishing disc can be used to confirm the presence of a cracked crown. When the patient bites on the disc, it acts as a wedge on the cracked tooth and causes pain. 

When a visible crack is found, lateral pressure, either digital or from the handle of an operative instrument, is applied along the cusp on the occlusal surface. 

If the crown segment shears off and if the pulp is not exposed, the pain will usually disappear. The emergency treatment is completed by covering the exposed dentin with a sedative dressing and cementing a stainless steel band in place. If the pulp is exposed, a band should be cemented in place, and a pulpectomy should be performed.

If a greenstick fracture of the crown is present and the crown segment does not shear off under pressure, one should cement a stainless steel band around the tooth. Adjust the provisional restoration to eliminate any occlusal trauma to the tooth. This procedure should eliminate the pain . 

All the foregoing procedures are predicated on the presence of a vital pulp. Because any traumatic accident can temporarily affect the usual responses to the electric pulp test. cold test, and test cavity, negative test responses for pulp vitality are non diagnostic and should not be the basis for selecting endodontic emergency treatment. It is wiser to assume that the pulp is vital because vital pulp in the root canal of a fractured tooth can enhance the prognosis for healing. If later evidence indicates the presence of pulp in- flammation or necrosis, the pulp can be extirpated at the time without altering the healing potential of the tooth. 

FRACTURED ROOT

A fractured root is an endodontic emergency if the tooth is painful and especially. if the incisal segment is mobile .The prognosis for a horizontally fractured root  depends on the location and direction of the fracture .

A horizontal fracture above the alveolar crest has an excellent prognosis be cause the tooth can be restored after endodontic treatment. The closer the root fracture is to the root apex, the more favorable the prognosis ,sufficient root will remain even it the fractured segment has to be removed later. 

Emergency treatment for a horizontally fractured root consists of stabilization by ligation of the tooth and adjacent teeth it mobility is present. Treat any soft-tissue lacerations .

 A fractured root that contains a vital pulp has a better prognosis for root repair than one in which the pulp has died or has been extirpated.

Unfortunately, traumatic injury to a tooth may cause pulpal death. When a fractured root with a necrotic pulp requires emergency care, treatment consists of ligation for stabilization, root canal therapy including instrumentation, irrigation, debridement, and intracanal medication. If pain and swelling are present, the root canals may be left open for drainage. If the tooth is not strategic or restorable, it should be extracted as soon as possible.

A horizontal fracture at the midroot, level with or below the crest of alveolar bone, has a guarded-to-poor prognosis unless it is ame- nable to orthodontic root extrusion. 

Usually, the extra-alveolar segment, that is, incisal segment, is mobile and requires extraction. When the remaining apical root segment is long enough to retain a functional post-core crown, and has sufficient bony support, the emergency treatment for this segment is pul- pectomy. If the pulp is necrotic and the tooth causes moderate-to-severe pain or swelling. then the root should be treated as if for an acute alveolar abscess. 

A tooth with a vertical or longitudinal fracture of the root has a hopeless prognosis. The usual emergency treatment is extraction. 

TOOTH, AVULSION

 The avulsed or luxated tooth is both a dental and an emotional problem. It is usually the result of trauma to an  anterior tooth of a child or young adult. The shock and pain of the injury and the loss of a tooth needed for eating, speaking and smiling often lead to emotional upheaval in patient and parent. 

 The longer the luxated tooth is out of its socket, the less likely will remain in a healthy, functional state after replantation. 

The following instructions should be given to the parent or patient as soon as the dentist has been informed of the accident and in preparation for an imminent visit

1) Wash the tooth in running water with out brushing or cleaning it, and examine it to be certain that the tooth is intact. 

2) Have the patient rinse mouth. Replace tooth in its socket using gentle, steady finger pressure. If the patient is cooperative and able, have the patient gently close the teeth together to force the tooth back into its original position. 

3 ) Take the patient to the dentist immediately.

If the patient or parent cannot replace the tooth in its socket, then care in transporting that tooth to the dentist becomes essential. The tooth must be carried in a moist vehicle to maintain the viability of the torn periodontal ligament.

 The most readily available vehicle is the patient's mouth, in which the tooth is bathed in saliva at body temperature. If this cannot be safely done, such as if the patient is too young, then one should place the tooth in a container of milk, if available, for transport to the dentist. The tooth should not be in a dry handkerchief or tis- sue because the periodontal ligament will be come dehydrated.

Because several studies have shown that extraoral time for an avulsed tooth optimally should not exceed 30 min, the patient must be taken to the dentist immediately. 

The sooner the replantation, the better the prognosis. 

On the patient's arrival at the dentist's  office, the following procedure obtains:

1) If the tooth is in its socket. ligate,  stabilize, and disocclude the replanted tooth .Ifthe tooth is out of its socket or is improperly positioned, replant the Jooth properly  before ligation.

2) Take a radiograph to verify the position of the tooth in its socket and to examine it for any root or alveolar bone fracture. Check the adjacent teeth for possible root fracture. 

3. Do not attempt endodontic treatment at this time unless the tooth requires venting (drainage). In that case, open the pulp chamber, debride it and the root canals, insert an intracanal medicament, and seal the access cavity.

REFERRED PAIN

Accurately determining the origin of the patient's pain is the first step in emergency endodontic treatment. Although the most frequent cause of dental pain is pulpoperiapical pathosis. 

Referred pain may be initiated from an inflamed pulp to other parts of the body, usually on the same side and in close proximity to the tooth, or from other sources that cause pain that simulates the painful symptoms of pulpoperiapical disease.

According to Hurwitz, dental pain can have its origin in trigeminal neuralgia, atypical facial neuralgia, migraine, cardiac pain.  temporomandibular arthrosis .Sinusitis or a head cold may cause pain referred to the maxillary posterior teeth. Pain arising from periodontal problems, such as periodontal abscess, occlusal trauma, muscle spasm, bruxism and clenching, and pericoronitis is often mistaken for pulpoperiapical pain.

 Spicer reported pain referred  to a lower molar from a basilar artery aneurysm that produced pressure in the trigeminal nerve. Verbin and colleagues described odontalgia in a maxillary lateral incisor due to herpes zoster of the maxillary division of the fifth cranial nerve (trigeminal) The pain subsided spontaneously following the disappearance of the mucocutaneous eruption.

Sakurai and Richardson described vascular neck pain referable to the mandibular posterior teeth. 

 Otitis media can refer pain to the mandibular molars. 

Temporomandibular joint dys function may cause a toothache. A toothache on the left side of the mouth can be due to myocardial infarction or angina pectoris, especially if the pain occurs while the patient is exercising.

Harris reported a case in which pain was referred to the opposite side of the mouth; however, such an occurrence is rare. Other causes of referred or unusual pain include intensive radiation, systemic diseases (malaria, typhoid, influenza, anemia, hyperten sion, or neurasthenia), menstrual onset, neurologic diseases of the central nervous system, and some malignant diseases and tumors. 

Conversely, ocular pain may be caused by disease of the pulp or periodontium of anterior teeth. 

Maxillary posterior teeth may refer pain to the maxillary sinus and to the back and side of the head.

 Pain from mandibular molars can be referred to the ear or the back of the head. 

Duquette and Goebel reported that pulpitis can cause temporomandibular joint pain and may be mistaken for myofascial pain dysfunction. 

ANALGESICS AND ANTIBIOTICS

The use of analgesics and antibiotics is im- portant in endodontic emergency treatment. Because their role is essential and supportive to the previously described emergency procedures, every clinician should be familiar with their mode of action, dosage, toxicity, route of administration, indications, contraindications, and interactions with other drugs.

 The following description of the  analgesics and antibiotics used in emergency endodontic procedures is limited in scope and is presented for orientation only. The reader is referred to pharmacologic textbooks that describe these and similar drugs in detail.

Analgesics

Analgesics are pain relievers. Generally the narcotic analgesics are used to relieve acute, severe pain and the non-narcotic or mild analgesics are used to relieve slight-to- moderate pain. The clinician's therapeutic judgment determines which analgesic should be prescribed. The drugs used most often are the mild, nonopioid analgesics.

Deuben described a possible mode of ac- tion of the nonopioid analgesics as interference with membrane phospholipid metabolism.

 

The more frequently used non-narcotic analgesic are aspirin ,acetaminophen (Tylenol), diflunisal (Dolobid) naproxen (Naprosyn), and ibuprofen (Motrin) Aspirin, alone or in compound form, is used most often. 

1 Aspirin -In addition to relieving pain, aspirin has anti- pyretic and anti-inflammatory properties. It is effective against mild-to-moderate pain. Beaver demonstrated that 600 mg aspirin was superior to 30 mg codeine for relief of pain. 

 It can cause an anaphylactoid reaction in an allergic person or an adverse reaction in per- sons with gastric ulcers. In addition, aspirin is contraindicated in patients receiving an- ticoagulant therapy, in patients undergoing antineoplastic chemotherapy, in diabetics. and in those suffering from gouty arthritis.

2)Acetaminophen, the second most commonly used analgesic, is as effective as aspirin for relief of mild-to-moderate pain. It has a lower incidence of side effects than aspirin and is effective in smaller doses. It lacks the anti-inflammatory effect of aspirin. Acetaminophen is recommended when prescribing analgesics for children and is available in liquid form. 

 3) Naproxen, like diflunisal, is a long lasting analgesic. It is prescribed in 275-mg tablets, to be taken twice daily. Both naproxen and ibuprofen are proprionic acid derivatives,but their potencies differ.

4) Ibuprofen, prescribed in doses of 300 to 400 mg 4 times daily, is more effective for severe pain relief than the daily therapeutic dose of aspirin. Ibuprofen should not be used in patients with a history of peptic ulcer or aspirin intolerance.

Moore and Deuben stated that narcotic analgesic control pain better than other drugs currently available. These workers postulate the mode of action of opioid analgesics as an inhibition of neurotransmission along central pain pathways by inhibiting the release of an excitatory pain transmitter. 

Some of these narcotic analgesics are:

Morphine: not administered orally 

meperidine, 50 to 100 mg (Demerol), 1 tab q4h p.r.n. 

codeine, 30 mg. 1 tab q4h p.r.n.

 oxycodone, 5 mg, with acetaminophen, 325 mg (Percocet-5), 1 tab q4h p.r.n. hydrocodone, 5 mg, with acetaminophen, 500 mg (Vicodin), 1 tab q6h p.r.n. dihydrocodeine, 16 mg, with aspirin. 356.4 mg, and caffeine, 30 mg (Synalgos-DC),1 tab q4h pr.n. 

acetaminophen, 300 mg, with codeine, 30 mg (Tylenol No. 3), 1 tab q4h p.r.n. aspirin, 325 mg, with codeine, 30 mg (Empirin No. 3), 1 tab q4h p.r.n.

acetaminophen, 650 mg, with propoxy- phene napsylate, 100 mg (Darvocet-N 100), 1 tab q4h p.r.n..

Each of these drugs must be used with caution. Narcotic analgesics may depress the central nervous system. They can interact adversely, sometimes fatally, with alcohol, antihistamines, barbiturate, local anesthetics, phenothiazines, tricyclic antidepressants, and monoamine oxidase inhibitors by enhancing the depression of the central nervous system. All opioid analgesics may be abused and should be prescribed with discretion.

Antibiotics

Antibiotics are life saving therapeutic agents of inestimable value. They are used for prophylactic coverage of the medically compromised patient and, in special circum- stances, an adjunctive treatment of acute periapical or periodontal infection. These drugs must be administered with care and discretion. Their future value for treating life- threatening infectious disease may be diminished or eliminated if they are used indiscriminately. One must not prescribe an antibiotic without being certain that the patient is not allergic to that antibiotic.

Ideally, the selection of a prescribed antibiotic should be based on the result of susceptibility tests that indicate effectiveness against the infecting microorganisms. The more lethal the antibiotic, the less likely re- sistant microorganisms will develop to it. 

The decision to administer antibiotics for an endodontic emergency, excluding prophy- lactic coverage of the medically compro- mised patient, depends on symptoms of sys- temic toxicity, such as elevated temperature, or on localized symptoms of extensive swelling or cellulitis, and the selection of antibiotic is usually empiric. Because these symptoms are usually absent in patients with pulpitis, antibiotics are rarely needed for treatment of these diseases. The use of antibiotics should be limited to adjunctive treat- ment of acute periapical and periodontal dis-ease, and then only when truly needed.

The most effective antibiotic for use in endodontic emergencies is penicillin. Its mode of action is by inhibition of cell-wall synthesis during multiplication of microorganisms..

Its antimicrobial action is bactericidal. The penicillins are effective against gram- positive cocci, especially the viridans strain,- Rod ike bacteria, and many anaerobes involved in endodontic infections. The acid. stable penicillin V (phenoxymethyl penicillin) is the antibiotic of choice for oral administration for the medically compromised patient. 

The recommended standard regimen for dental procedures is: penicillin V, 20g orally 1 hour before the procedure, then 1.0 86 hours later. In case of allergy to penicillin, erythromycin may be prescribed: 1.0 g orally 1 hour before, then 500 mg 6 hours later. Penicillin should not be prescribed for a patient with a history or suspicion of penicillin allergy. 

Erythromycin's mode of action is inhibition of protein synthesis: however, its anti- bacterial spectrum is similar to that of penicillin. Resistant forms can occur and have been reported for staphylococci, strepto- cocci, and enterococci. Because erythromycin is acid labile, it should be taken with food. It can be administered in tablets having an acid-insoluble coating, to ensure effective blood levels and to prevent inactivation by stomach acids.

Other antibiotics useful for treating endo- dontic emergencies are cephalexin (Keflex). 250 to 500 mg every 6 hours, clindamycin phosphate (Cleocin HCI), 150 to 300 mg every 6 hours, and tetracycline hydrochloride (Achromycin V), 250 to 300 mg every 6 hours. Tetracycline is the least effective of all the antibiotics listed for endodontic emergencies.