The term complication may be defined as any deviation from the normally expected pattern during or after securing local analgesia.
Complication of local analgesia can be classified as follows:
- • Primary of secondary: Primary complication is that which is caused and manifested at time of securing the analgesia, while secondary complication is that which is manifested later though it may be caused at time of securing
- • Mild or sever: Mild complication is that one which exhibited slight change from the normal pattern while sever complication is that one that is manifested by sever deviation from the expected normal
- • Transient of permanent: Transient complication is that one which leaves no residual effect while permanent complication, on the other hand, leaves residual effect whatever minor it is.
may be further divided into those which are attributed to the solution used and those which are attributed to the insertion of the needle. (Table 8-I)
COMPLICATIONS ATTRIBUTED TO THE SOLUTION USED
The term toxicity or toxic over dose refer to the symptoms manifested as a result of over-dosage or excessive administration of the solution.
The occurrence of toxicity depends on the presence of a sufficient concentration of the drug in the blood stream to adversely affect organs most sensitive to the drug which are the central nervous system, the cardiovascular system and the respiratory system.
To reach a sufficient blood stream concentration the drug must be absorbed into the systemic circulation in a rate more than the rate of its biotransformation and elimination. Accordingly toxic overdose may come about by one of the following ways:
- • The use of too large volume of the solution.
- • Accidental intravascular injection.
- • The use of too great concentration.
- • Unusually rapid absorption into the blood stream as when injection is made in an
extremely vascular area. Also rapid injection increases the rate of absorption of the drug.
- • Slow biotransformation of the drug as in cases of advanced liver diseases.
- • Slow elimination of the drug from the body as in cases of
impaired kidney functions.
Signs and symptoms
Toxicity is usually manifested by an early central nervous system depression followed by a proportionate degree of depression. On occasion central nervous system depression
may appear as the first sign. Table8-2 shows a list for signs and symptoms of stimulation and depression phases.
Prevention of toxicity
As a general rule prevention of the occurrence of complication is better than waiting until
it happened and treating it. The symptoms of toxic overdose although easy to recognize and treat, it may , in some occasions occur in such rapidity that it is impossible to be treated successfully. This fact emphasizes the necessity of prevention rather
than treatment. The chance for the development of systemic toxicity can be greatly decreased by applying the following rules:
1. Pre-analgesic evaluation of the patient
This is a must to detect any systemic condition that may
affect the biotransformation and elimination of the drug.
2. Use the least possible volume
The belief that if a small volume is good a larger volume is better is not true. There is an optimal volume of the solution that produces
satisfactory analgesia. The use of greater volume will not improve the analgesia it only increases the possibility of toxicity to occur and/or cause local tissue damage.
3. Use the weakest possible concentration
Like the volume
of the analgesic solution used the use of greater concentration will not improve the analgesia. For example 1% procaine will secure adequate analgesia, 2% or 4% concentration can not do any more other than increasing the chance for development of toxicity
4. Slow injection
The solution must be deposited slowly into the tissue. Rapid injection increases the rate of absorption of the solution thus enhancing the possibility of toxic reaction. Also rapid injection may cause local tissue
5. Aspirate before injection
This is especially true when injection is made in highly vascular area as when doing posterior superior alveolar nerve block. Aspiration before injection will decrease the possibility of accidental
However, it must be beard in mind that failure to aspirate blood does not mean that the needle is for sure not in a blood vessel. Factors like viscosity of the blood, collapse of the wall of the blood vessel upon aspiration
and occlusion of the needle by soft tissue may give a false sense of security. For these reasons, the operator should inject the solution slowly while watching the patient for any unusual reaction.
6. The use of vasoconstrictors
All local analgesic agents are vasodilators and as such they are rapidly absorbed into the circulation which increases the possibility for toxic reaction. Accordingly vasoconstrictor agent must be added to the solution unless otherwise contraindicated.
The symptoms of toxic overdose should be recognized at the very early moment of their appearance. This means that the patient must be observed during the injection and for a considerable period of time after the injection.
The sooner the symptoms are recognized and the treatment instituted the more is the chance for favorable results. Table 5-III shows an outline for the treatment of toxic overdose.
II. VASOCONSTRICTOR TOXICITY
A systemic toxic reaction is manifested when a sufficient high toxic blood level of the drug is reached. The same factors governing the rate of absorption, biotransformation and elimination
of the local analgesic drug are applied for the vasoconstrictor. Signs and symptoms of vasoconstrictor toxicity include palpitation, tachycardia, hypertension and headache. Apprehension and restlessness also occur but they are very difficult to be differentiated
from those due to the local analgesic agents. However, the treatment of both types of toxicity is the same.
Drug allergy may be defined as a specific type of
hypersensitivity to a chemical compound brought about by alteration in the body’s reaction to an antigenic substance. Allergy, however, is an uncommon reaction which contribute for less than 1% of the local analgesic complications.
The primary cause of allergy is a specific antigen-antibody reaction in a patient previously sensitized to this particular drug or chemical compound. Figure 8-1 shows a schematic presentation for the mechanism of allergic reaction.
Signs and symptoms may be mild or sever, immediate or delayed. Symptoms are exhibited by the shock organs which are the skin, mucous membrane and blood vessels. There may be:
- • Skin rashes.
- • Urticarial.
- • Angioneurotic edema.
- • Mucous membrane congestion in the form of rhinitis and asthmatic symptoms.
Delayed reaction: This may result when injection is done in patient previously sensitized. As
a rule delayed reaction are more annoying than serious. Manifestation may be in the form of local edema at the site of injection, serum sickness and malaise and joint pain and tenderness.
1. Adequate pre-analgesic
evaluation: The history is the most valuable means for securing important information:
- • Patients with history of asthma and hay fever are considered potentially allergic individuals and are more liable to develop allergy.
- • When the patient gives history to a specific drug, named by the patient, he may be given another drug. But if the patient is uncertain about the name of the drug to which he is allergic, it is advisable to do allergic test for different drugs.
2. When the patient gives history of allergic reaction: No drug should be used if the patient gives history of previous allergic reaction. Also no patient should be tested to disprove his allergic history. This may result
in serious complications.
In mild cases no treatment is required but the drug should not be used in the future. In moderate and sever cases antihistaminic and epinephrine are given together with aminophylline and oxygen
administration if the patient is asthmatic.
IV. ANAPHYLACTIC REACTION
It is a form of allergy that is characterized by its sudden onset during or immediately after the administration of the
drug. It is one of the most urgent emergencies in the dental office.
There is sudden loss of the vasomotor tonus resulting in increase in the vascular bed which leads to:
- • Sever hypotension.
- • Weak pulse.
- • Unconsciousness.
- • Cyanosis.
- • Death.
In the majority of cases death is a must unless the treatment is immediate and accurate. Treatment modalities
- • The patient is placed in shock position to assist adequate blood supply to the brain.
- • Respiration is immediately supported by demonstration of oxygen, artificial respiration or mouth-to-mouth breathing.
The circulation should be supported and the hypotension overcomed by the demonstration of intravenous fluids, vasopressor drugs and steroid hormones.
- • Closed chest cardiac massage may be needed if circulation failed to respond to previous measures.
The term idiosyncrasy is often assigned to a bizarre type of reaction that cannot be classified as toxic or allergic. It has been claimed that true idiosyncratic tube
of reaction do not exist. The manifestations exhibited when a subtoxic dose is given represent a true toxic reaction in a patient who is sensitive to the drug.
Reactions other than toxic or allergic are usually not related to the analgesic solution.
This is most probably psychogenic in nature.
VI. LOCAL REACTIONS
Infections due to contaminated solution are very rare at present time. This is due to
the rigid standards under which the analgesic cartridges are manufactured, so that they reach the dentist as sterile ampules. However, the following should be noticed to prevent the chance of using a contaminated solution:
- • The cartridge
is only used for one patient and any remaining amount is discarded.
- • The cartridge is stored dry in a sterile container that is kept covered all the time.
- • Do not store the cartridge in alcohol or any other solution. Leakage allows
the alcohol or the storing solution to seep into the ampule. If an alcohol contaminated solution is injected, prolonged analgesia and local tissue irritation will result. Disinfection of the ampule is done by placing it for a limited time in a colored solution
to see if leakage occurred.
- • Always handle the cartridge by the stopper end and the end containing the rubber diaphragm should be sterilized with alcohol sponge before use.
B. Local tissue damage
result from too rapid injection and the use of large volume especially in the confined areas as the palate.
COMPLICATIONS ATTRIBUTED TO NEEDLE INSERTION
AND TECHNIQUE USED
Syncope or fainting is the most common complication associated with the use of local analgesia. It is a form of neurogenic shock which occurs
due to cerebral ischemia secondary to vasodilatation of the peripheral circulation. This will result in sudden drop in the blood pressure. As the patient is sitting in the dental chair the brain is in superior position and is liable to reduced blood flow.
Syncope is not always associated with loss of consciousness. Loss of consciousness is an extreme manifestation of cerebral ischemia that is sufficient to interfere with cortical function of the brain. In most
cases the patients becomes pallor, dizzy and complain of feeling different or strange.
Proper management of the patient at this stage usually result in complete recovery. However, in sever case or if proper management was not taken, there may be:
- • Changes in respiratory pattern which is accompanied by extreme pallor and cyanosis.
- • Cardiac arrhythmia with weak pulse.
Syncope is better to be managed at its early phase and before
loss of consciousness. The following should be done:
- • The performed procedure is discontinued.
- • The patient is placed in semirecling position (Shock position). The back of the chair is tilted so that the head is elevated 5o and
the legs are elevated 20o. This position will aids the venous return from the lower portion of the body and assist adequate blood supply to the brain.
- • If the patient is conscious he is instructed to take few deep breaths. This will assist the
venous return and provide adequate oxygenation.
This simple management is usually enough and the patient regains his normal feeling. The patient should now be reassured and reevaluated. However when the more sever symptoms of cyanosis and cardiac
arrhythmia are present the respiratory and circulatory supportive measures should be taken.
II. MUSCLE TRISMUS
Trismus (inability to open the mouth normally) is a common complication particularly
after inferior dental nerve block.
- • The most common cause is trauma to the muscle during needle insertion.
- • Injection of an irritating solution.
- • Hematoma formation in the muscle.
- • Low grade infection within the muscle.
- • Use sharp sterile needle.
- • Insertion should be as atraumatic as possible.
- • The area of needle insertion should be
cleaned and painted with nonirritant antiseptic solution.
- • Avoid repeated injections.
In most cases no treatment is necessary and the condition corrects itself. However, when it is due to muscle
trauma muscle exercises and analgesics may be needed. When hematoma formation or low grade infection is expected mouthwashes and antibiotics may be required.
Pain during or after
injection is very common and in most cases it is due to carelessness on the part of the operator.
- • Always use sharp needles.
- • Area of penetration should be painted with topical analgesic.
- • Insertion should be made as atraumatic as possible.
- • Multiple insertions in the same area should be avoided.
- • Injection should be injected slowly.
- • Injection of large volume in constricted areas, as the
palate, should be avoided.
- • The solution temperature should be as close to the body temperature as possible. Too hot solution is more harmful than too cold solution. This is achieved by holding the analgesic cartridge in hand of the operator
for few minutes before injection.
Edema is rather a symptom and not an entity in itself. Trauma, infection, hemorrhage allergy can produce edema. Treatment depends on the
Infection may result from the use of nostril needles or solution or from carrying surface bacteria from non-sterile mucosa into the deeper tissue by the tip of the needle.
VI. PROLONGED ANALGESIA
Prolonged analgesia may occur due to the following causes:
- • Prolonged analgesia may occur due to injection of a solution contaminated with alcohol or
other sterilizing solution.
- • More commonly this complication is due to trauma to the nerve sheath caused by the needle which results in hemorrhage into the nerve sheath. In such cases the patient will report an electric shock in the areas innervated
by the traumatized nerve. The resultant hemorrhage undergoes resorption very slowly due to the poor circulation of the area.
- • Trauma and swelling of the soft tissue in the proximity of the nerve.
In almost all cases of prolonged analgesia the condition returns to normal with treatment.
VII. HEMATOMA AND ECCHYMOSIS
Hematoma is the diffusion of blood into the tissue as a result of
punctured vessel. It is usually associated with infraorbital nerve block and posterior superior alveolar nerve block. All hematomas are absorbed in due time with no residual effect other than the skin discoloration which may persist for few days. No attempt
should be made to aspirate or to otherwise interfere with the normal absorption of the blood as the condition has no complications.
VIII. BIZARRE NEUROLOGICAL SYMPTOMS
On rare occasions unexplained
neurological manifestations may occur during or after administration of local analgesia. These may be in the form of facial paralysis, crossed eyes, temporary blindness ...etc.
Occurrence of such symptoms is quite rare. However, the best method of prevention
is to follow closely the accepted techniques and to adhere to all basic concepts of accepted procedures.
IX. LOCAL TISSUE DAMAGE
Sloughing and ulceration may occur if the analgesic solution
is too rapidly injected in the tissue or too much volume is used. This is especially true in confined areas as the palate and the labial aspect of the lower teeth.
X. BROKEN NEEDLE
is one of the most annoying and depressing complications. This complication is quite uncommon at present time due to the use of single-used needles. However, for this complication to occur it needs a great deal of carelessness on the part of the operator.
- • Never force the needle against resistance. Needles were never made to be forced into bone or beneath the periosteum.
- • Never change the direction of the needle inside the tissue. Always withdraw
the needle to just below the mucosa and redirect it.
- • Do not use needles with too fine gauge.
- • Do not use resterializable needles. Resterialization of the needle makes it dull and more liable for breakage.
- • Never
insert the whole needle inside the tissue. As a rule 1/3 of the needle must be in view outside the tissue so that if breakage occurs, usually at the hub, the needle can be removed by grasping the portion in view outside the tissue.