Topical Dental Anesthesia is that type of anesthesia that is manually applied to mucous membranes or abraded skin to obtain the desired effect of surface numbing. In dentistry, the most common site of application is the mucous membranes of the mouth.
Topical Dental Anesthesia are primarily used for numbing of the tissues of the mouth prior to giving an anesthetic injection. This numbing makes the anesthetic injection less painful to the patient. The most common types of topical anesthetics are lidocaine and benzocaine. Topical anesthetic agents are very useful in numbing the oral tissues in the area where the needle will be inserted to give local Dental Anesthesia. It is especially useful in treating patients that are anxious about getting an injection. Topical anesthetics also provide for excellent behavioural management of children.
ADMINISTRATION AND TYPES
Topical Dental Anesthesia come in a variety of formulations, such as an ointment form, a liquid form, and a spray form. All topical anesthetics are used to produce a numbing effect to the soft tissues of the oral mucous membranes. Some topical Dental Anesthesia are faster acting and will numb the soft tissue in only 15 seconds.
Spray topical anesthetic must be controlled and precautions should be taken so that the patient does not inhale the spray. Examples of spray anesthetics are ethyl chloride and cetacaine.
Local Dental Anesthesia is used at a specific site in the body to block painful sensations, which would normally occur during a procedure. It gives tissues a numbing effect. This type of anesthesia is called local because it only acts in the surrounding area where it is injected.
TECHNIQUES OF LOCAL ANESTHESIA
Injectable local Dental Anesthesia agents used in dentistry are divided into two different categories depending on how the anesthetic agent is administered. These categories are local infiltration and block (regional nerve block and field block). The type of injection for a given procedure is determined by the magnitude of the dental procedure. When managing only an isolated area, local infiltration may be enough. When the procedure may involve two or three teeth, a field block is indicated. When the dental procedures involve an entire quadrant or sextant, then a regional nerve block is probably the best choice.
(1) Infiltration Anesthesia
Local infiltration Dental Anesthesia is the process whereby a local anesthetic agent is injected into an area to achieve a numbing response by placing the agent into the small nerve terminal endings. This is a non-specific flooding of the tissues with the injection to cause only the nerve endings to numb. The anesthetic is injected directly into the tissues at the site where a procedure will take place; it diffuses into the surrounding area giving a local numbing. Most dental local Dental Anesthesia agents can be utilized in this manner. Local infiltration usually has the shortest duration of action. In most cases local infiltration is given using a short needle either of a 27 gauge or 30 gauge.
Area of the Mouth where Local Infiltration Anesthesia is used. There are five main areas in the mouth where local infiltration Dental Anesthesia is used. They are the following:
1. Submucosal and paraperiosteal. Examples of this type of local infiltration Dental Anesthesia are the lingual nerve region or mylohyoid nerve region, which is found on the tongue side behind the mandibular third molar, and the long buccal nerve region, which is found on the cheek side of the mandibular third molar.
2. Subperiosteal. Subperiosteal means right at the periosteum, which is the outer covering of bone. This region is anesthetized by the introduction of an agent at the region between the cheek and the gumline, aiming it below the gum tissues. The needle is usually almost touching the periosteum and care should be taken by the dentist to avoid scraping the bone. This is usually a very traumatic injection.
3. Periodontal ligament (PDL), intraligamentary. The anesthetic is injected into the periodontal ligament space. The onset of Dental Anesthesia occurs rapidly but in some cases it is very short acting.
4. Intraosseous. It is given in the bone and this type of injection is used very infrequently in dentistry today.
5. IntraseptaL This injection is quite painful and is performed by injecting into the soft tissues of the interdental papilla. The advantage of this type of injection is that it gives an immediate onset of numbing and has few complications.
(2) Block Anesthesia
Block Dental Anesthesia includes both field block and regional nerve block anesthesia. Field block anesthesia refers to the local anesthetic agent being deposited near larger terminal nerve endings so that two or three teeth and most of the surrounding soft tissues are numbed. An example of a field block is maxillary Dental Anesthesia in the region of the bicuspids (premolars), which is called a middle superior nerve block.
Regional nerve block anesthesia refers to when the anesthetic agent is placed close to the main nerve trunk. In most cases this is a distance from the site that is going to get numb. An example of a regional nerve block is in the region of the mandible to numb half the mandible, which is called a mandibular block.
Nerve blocks last longer and in many cases require smaller doses (amounts) of local Dental Anesthesia agents to achieve deep, profound nerve numbing. Different local anesthetic agents have different durations and dental local anesthetic agents with epinephrine added usually produce some of the longest durations—in some cases 3—5 hours. Dental block Dental Anesthesia is used primarily for the mandibular (lower) arch and also for the molars in the maxillary (upper) arch. The injection is usually given with a long needle of either a 25 or 27 gauge.
Area of the Mouth where Block Dental Anesthesia is used
1. Greater palatine, lesser palatine, and sphenopalatine nerves. Block Dental Anesthesia of the greater palatine region and greater palatine nerve is attained by injecting into the hard palate or the roof of the mouth near the second molar from the back of the mouth.
2. Posterior superior alveolar dental nerve (PSA). This injection usually numbs the entire maxillary molar region except the roof of the mouth in that region.
3. Middle superior alveolar dental nerve (MSA). This region is anesthetized by an injection on the cheek side near the first molar and bicuspids in the maxillary arch. This injection usually numbs the two premolars and the front root of the maxillary first molar.
4. Anterior superior dental nerve (infraorbital). This injection is not used that frequently.
5. Maxillary nerve. The maxillary nerve is usually numbed for very extensive surgical procedures involving the teeth, gum tissues, and bone of the molars and premolars in that region. This injection isn’t frequently used.
6. Inferior alveolar nerve (also referred to as mandibular nerve).
The inferior alveolar nerve block is also referred to as the mandibular nerve block. Of all injections used in dentistry for local Dental Anesthesia, this is used the most and also has the highest rate of failures with a single injection (15—20 ercent). This injection usually numbs all the teeth on that side up to the central incisor, half the tongue, and the lower lip.
7. Buccal nerve block. This injection is given slightly past the second molar into the cheek tissue. Very little Dental Anesthesia solution is needed.
PRECAUTIONS DURING PROCEDURE
(i) Patient observations. It is important to monitor the patient throughout the entire Procedure. Certain symptoms should be noticed if they occur. Normally, with the administration of a local Dental Anesthesia, there will be a pinprick, burning and pain at the site of injection, followed by gradual numbing of the region. But if the patient should become short of breath, develop a rash, have an increasing heart rate, or act abnormally, it should be considered that the patient is having an adverse reaction to the anesthetic agent and should be treated accordingly.
The most common adverse reaction that a patient has during a local Dental Anesthesia injection is Fainting. This is usually due to patient anxiety. In most cases of fainting, the oxygen and a blood pressure monitoring device is used and the patient pulse is continuously monitored. The patient should be positioned in the chair in a supine (lying back) position.
(ii) Heart patient hazards. Some Dental Anesthesia agents can produce adverse effects on the heart. Lidocaine should be avoided in patients with heart block or a slow heart rate and used cautiously in patients with other heart problems.
(iii) Administration into blood vessel: The accidental administration of an Dental Anesthesia agent into a blood vessel can be life-threatening. It is a particular concern in patients with existing heart disease. The veins carry blood towards the heart so if medication is injected into a vein, its effects will occur instantly. This can be prevented altogether by aspirating (withdrawing fluid) before injecting. If there is no return of blood with aspiration, one can be sure the needle has not entered into a vessel.
(iv) Infected areas. Local Dental Anesthesia should not be injected into infected areas of the oral cavity for several reasons. Most importantly, it may spread the infection into deeper tissues by the needle passing through the infected tissue. Also, the acidity of infected tissue can slow and obstruct the drug’s intended effect.
(v) Temporary numbness. The primary effect, which the local anesthetics provide, is a numbing effect. It takes minutes to several hours to wear off, depending on the agent used. Therefore, the effects are considered temporary. Occasionally, the effects wear off before a procedure is complete and an additional injection of Dental Anesthesia agent has to be administered. The dentist will usually choose a local anesthetic agent that will last the length of the dental procedure being accomplished.
(vi) Allergic reactions. As with other medications, anesthetics have the potential to cause allergic reactions. Most of the Dental Anesthesia agents currently being used are tertiary amines with an extremely low risk of adverse allergic reactions.
(vii) Paresthesia. As mentioned, a temporary numbness occurs with local Dental Anesthesia agents. However, there is the potential for a permanent numbness to occur. This is known as a paresthesia and is most common in dentistry after giving a nerve block injection (especially a mandibular block injection). When this very rare event occurs during nerve block injections, the needle penetrates or scrapes past the nerve. In these cases the numbing effect may be accentuated and last for a longer period of time. This is a temporary paresthesia.
The aspirating syringe is used for dental block and local infiltration Dental Anesthesia. The typical syringe used in dentistry either has a spring loading assembly, or a breech-loading assembly whereas the syringe folds in half. Both syringes allow for the insertion of pre measured and packaged local anesthetic carpule. For safety reasons, some syringes are self-aspirating; upon the release of pressure during an injection, the syringe will self-aspirate.
The disposable needle is the type of needle that should be discarded after being used on a single patient. Not all needles are the same. They may differ in length and gauge (thickness). The most common lengths used in a dental office are 1-inch needles (short needles) for infiltration anesthesia and 1.5 to 1.8 inch needles (long needles) for block Dental Anesthesia.