Chapter 55. Local & Regional Anesthesia in Pediatric General Dentistry

The practice of modern dentistry is inconceivable without the application of local anesthesia. The dentist has various devices and procedures available for achievement of local anesthesia at his/her disposal. However, it is a paradox that the local anesthesia procedure enables painless work in the mouth also causes patients the most discomfort and fear. Research has shown that the administration of the injection is the primary fear-inducing stimulus in children, and in patients in general.1–5 The painful experience of the injection is the most frequent reason for fear of the dentist in children. Local anesthesia in children's dentistry not only enables the therapeutic procedure in the child, but also enables the child to experience the procedure as pleasant and to remain relaxed. Of interest, studies have also shown that not only does the child fear the painful procedure and discomfort during treatment, but that dentists are also more apprehensive.5

Successfully administered local anesthesia is of crucial importance allowing the dentist to perform a number of therapeutic procedures on the tooth and in the oral cavity. Unfortunately, the administration of the injection of local anesthesia remains the main problem connected with painful sensation and the occurrence of dental anxiety in the patients, particularly children. Consequently, numerous studies in the field of pain control and fear have concentrated on reducing or completely eliminating pain when administering local anesthesia.3,6,7

Indeed, many techniques of local anesthesia administration can be made nontraumatic and without significant discomfort for the patient. This goal is possible also for mandibular blockade and infiltration anesthetic in the palatal mucosa. For administration of painless anesthesia, the dentist must possess certain knowledge, readiness, and skill. In this respect, concentrated efforts of the dentist to learn painless local anesthesia techniques are of exceptional importance.

Injection of local anesthesia is still the most common and effective method of anesthesia in clinical dental pediatric practice, in spite of many attempts to find an alternative less painful and more pleasant procedure for dental treatment. The application of jet injections without needles is only a partial solution of the problem because many areas in the oral cavity cannot be adequately anesthetized without the use of the traditional needle/syringe system.

Dental procedures are associated with pain and discomfort by the patient. This is the main reason for the development of dental fear and anxiety in children, with additional possible serious consequences for future dental treatment. For this reason alone, the painless administration of anesthetic is an important step in avoiding the development of fearful and uncooperative patients.

To control or reduce the patient's pain perception during the administration of intraoral injection, dentists must focus on the factors that influence that perception. The pain of intraoral injection is attributed primarily to the following:

1. Tissue damage by the needle

2. Pressure created by the anesthetic solution

3. Flow rate of the anesthetic

4. Temperature of the drug solution

5. pH of the anesthetic solution

To control the pain sensation during anesthetic administration, all of these factors must be controlled.

This chapter examines the specific aspects of administration of local anesthesia in dental practice and currently available procedures and devices for this application in dental practice with special emphasis to achieving painless local anesthesia in children.

When administering local anesthesia the clinician should start with the assumption that nobody likes to receive an injection of any type. This is particularly the case for children. Thus, the method of administering the anesthesia to a child is of extreme importance, not only for performing a specific operation in the mouth, but also for future cooperation from the child. Carefully administered local anesthesia can be almost painless and acceptable for the child. On the other hand, painful local anesthesia can be unpleasant and a frightening experience for the child, and the treatment is made difficult or even impossible.

Before administering local anesthesia, it is necessary to determine whether the child has had any experience of local anesthesia and what he or she feels about it. If the child has no experience and is cooperative and positive, the procedure of administering anesthesia can usually be performed with less difficulty.

Administration of anesthesia to children of preschool age is a particular problem because they are, in general, less tolerant of pain and discomfort than older children. It should be kept in mind that although it is possible to give an injection almost painlessly, it is impossible to avoid the strange sensation as the local anesthesia takes effect, which causes anxiety in some children.

The dentist can control the discomfort and fear of local anesthesia. To ensure this outcome, it is necessary to acknowledge many factors that have a significant influence on the degree of pain during the administration of anesthesia. Some of the most important are the patient's fear and anticipation of pain, perception of the needle and syringe, technique and method used, condition of local tissue, and how well the surface anesthesia is applied.

Fear & Anticipation of Pain

Most children consider the injection of anesthesia to be the most undesirable intervention in the mouth.1,5 The administration of local anesthesia is not only a stressful experience for the patient, but also for the dentist. This is particularly the case when the patient anticipates pain and unwillingly accepts the procedure of anesthesia2,8,9 (Figure 55–1).

There are two important aspects of administering painless anesthesia: (1) communication and (2) technical. The occurrence of fear and a negative experience of local anesthesia are most frequently found in children.4,5 A calm and relaxed child is not only important for easier administration of anesthesia but also for its success, that is, the effect of the anesthetic.5,10,11 Psychological and pharmacologic techniques can both be used to prepare the child for the administration of local anesthesia.

It should be stressed that a tense patient with an increased anticipation of pain usually feels more intense pain during local anesthesia. Acquainting the patient with surface (topical) anesthesia and the subsequent anticipation that there will be no pain, can reduce the anticipation of pain to a great extent. It is also important to stress that suggestion can be used, with the aim of reducing anticipation of pain. Suggestion and relaxation before the injection are also important for the effect of the local anesthesia.5,11

Verbal communication with the patient is essential, and it should be maintained during the preparation and administration of local anesthesia. It is important to emphasize that surface anesthesia is given initially to ensure that all other procedures are painless and pleasant. The patient should be encouraged while administering the anesthesia. It should be stressed that this is done slowly so that the administration is more pleasant and the anesthesia is maximally effective.

Conversation with the patient achieves better relaxation before and during administration. If this is not possible by psychological means, sedation (eg, nitrous oxide or midazolam) can be used. However, sedation cannot replace local anesthesia; it is merely preparation for easier and more successful administration of the local anesthesia.11

Injection Needle

The main reason for fear of local anesthesia for most patients is the needle. In the case of patients with strong fears or phobias of the needle, a needleless technique of local anesthesia can be applied (eg, jet injection).

During administration of needle injection anesthesia attention should be paid to ensure that the discomfort of needle insertion is minimal or completely prevented. Factors that influence the discomfort during the penetration of the needle include diameter (gauge) of the needle, type of needle, method of penetration through tissue, and quality of the topical anesthesia of the mucous membrane. For instance, a thinner needle causes less tissue trauma and less pain during penetration of the tissue (Figure 55–2). Needles thicker than 27 gauge (optimal 27 and 30 gauge) are not recommended for use in children.11 Also, a slow injection of small amounts of anesthetic is less painful to patients. The site of the needle penetration should be prepared with the application some form of surface anesthesia.

Anesthetic

Two features of local anesthetic have an influence on pain during injection: temperature and pH. Prior to administering anesthesia, the local anesthetic should be at room temperature. If the anesthetic is kept in a refrigerator, it should be warmed up to body temperature prior to use by holding it in the hand or better yet, in a warming device10,11 (Figure 55–3).

Local anesthetic that contains a vasoconstrictor (epinephrine) has an appreciably lower pH than plain solutions of local anesthetic. The lower the pH of the anesthetic, the more painful is the injection. Consequently, the use of local anesthetic without a vasoconstrictor is appropriate in children (eg, plain solutions of mepivacaine or prilocaine). Indeed, studies have shown that pain associated with the intraoral administration of local anesthesia can be significantly reduced if a plain anesthetic without vasoconstrictor is used.10,12

Syringe

The level of anxiety in the patient before administration of local anesthesia also depends to a large extent on the appearance of the syringe. The traditional needle-injection assembly automatically induces fear of dental treatment in a child. To avoid fear of the needle or tension in the patient prior to anesthesia, it is possible to successfully use jet injection in some areas. This method then can be extended by additional administration of injection anesthesia, if necessary.

Technique

Infiltration anesthesia in loose tissue is less painful than for instance, mandibular block anesthesia, in which the needle penetrates into the denser tissues. In small children, infiltration anesthesia in the mandible, can be used and thus avoid mandibular blockade, which is more painful.

Anesthesia of the palatal mucous membrane can be achieved by the application of palatal nontraumatic injections (a combination with intrapapillary anesthesia), application of jet injections, or computerized anesthesia (eg, Wand method). Slow and steady injection is most important to decrease pain, which is easiest to achieve by an automated method. Alternatively objective assessment of injection pressure can be used to avoid forceful, traumatic injection of local anesthetic.

A combination of transcutaneous electrical nerve stimulation (TENS) and infiltration anesthesia can reduce or completely eliminate pain from injection (either infiltration or blockade).

Condition of Local Tissue

Administration of anesthesia into inflamed tissue may result in less successful local anesthesia because of the high pH of the tissue and because of other mediators of the inflammation. Nerve endings in an inflamed area are hyperalgesic, and conduct painful impulses on minimal stimulation.11 Consequently, the entrance of a needle and administration of anesthetic into an inflamed area is considerably more painful. Hyperalgesia of the nerves in the inflamed area can be remedied by the administration of an anesthetic of greater concentration (eg, 4% instead of 2% articaine, or 5% lidocaine).11

Method of Administering Anesthesia

Slow injection of the anesthetic is extremely important to decrease pain on injection.

To decrease pain one 1.8-mL cartridge is injected over 1 to 2 minutes. Faster injection is painful because it results in greater trauma injection pressure, and painful stretching of the local tissue.

Topical Anesthesia

Topical anesthesia is a fundamental part of the administration of infiltration local anesthesia because it has both psychological and pharmacologic importance. Skillfully and patiently applied topical anesthesia can reduce or completely eliminate the pain from the needle penetration (Figure 55–4).

Various methods are used with the aim of reducing pain when administering local anesthesia in children. Among the most frequent are surface anesthesia of the site of the needle penetration, anesthesia by jet injection, and sedation of the child prior to administering the injection. More recently, a specific technique of a computerized local anesthesia device (eg, WAND) was developed.10,13–18

Jet Injection

The most important aspect of its application is the elimination of fear of the injection needle. For this reason, jet injection is especially suitable for application in children and adults with a phobia of needle injection. Using a jet injection, it is often possible to achieve reliable anesthesia of the working area for an entire range of intraoral procedures. For those patients in whom jet injection is insufficient, it is almost always possible to accomplish adequate local anesthesia to allow painless administration of additional, traditional needle injection anesthesia (Figure 55–5).

Jet injection offers a great advantage in ensuring local anesthesia in patients with a phobia of classic injection (needle penetration). This is particularly the case in pediatric dentistry, where, because of lower bone density, much better anesthetic effect can be achieved than in adults. Consequently, in children, a small amount of anesthetic can be used to achieve good anesthesia for almost all procedures on the teeth in primary dentition. Used alone or in combination with sedation jet injection allows pleasant and virtually painless dental treatment in children and adults.

Computer-Controlled Anesthesia Delivery System

An example of a computer-controlled anesthesia delivery system is shown in Figure 55–6. The system shown allows practically painless administration of local anesthesia, even in an area with dense connective tissue, such as the mucous membrane of the hard palate.13,14,16–18

The device functions by injecting anesthetic at a constant, slow rate and controlled pressure, regardless of the type and resistance of the tissue (loose connective or firm connective palatal mucous membrane). Slow, intermittent injection is maintained by a computer controlled piston. The appliance also enables electronic control of the rate of injection during the entire procedure. Administration of the anesthetic into the tissue is performed very slowly so as to enable the anesthetic to enter the tissue before the needle and to create a passage for it. It is believed that the maintenance of constant pressure and passage of the anesthetic, with an ideal rate of injection of the anesthetic, are the main reasons for achievement of pleasant and almost painless injections with this system.13,14,16

The appearance of the system for administering anesthesia has an important role in the total perception and attitude toward anesthesia. The hand piece with the needle looks like a stick, which is why the system is often called “anesthesia with a stick.” It can be presented to the children picturesquely as “anesthesia with a magic stick” and not injection, which children are far more willing to accept (Figure 55–7). Such a device does not induce a feeling of anxiety in children, and children with experience with it report the procedure as pleasant.15,19,20 Multiple studies have demonstrated that computer-controlled anesthesia for children, particularly those of preschool age, is associated with significantly less discomfort, when compared to the needle-injection method.

In summary, the use of modern methods and devices makes it possible to ensure an almost painless administration of intraoral local anesthesia in children. It is important to take into account all of the factors that influence pain including the perception of pain with the intraoral injection of anesthetic. The injection of anesthesia in a relaxed child, with prior application of surface anesthesia, plays an important role in making dental procedures more pleasant experiences. In patients with significant fear of the needle, application of jet injection followed by classic infiltration anesthesia, when necessary, is extremely useful.