LOCAL ANESTHESIA

Contents : Definition. Requirements. Indication/contra indications. Advantages/disadvantages. Composition of local anesthesia. Local anesthesia techniques.

About requirements, indications, contraindication, advantages, disadvantages and composition was taken previously in oral surgery topics,

Definition : It is temporary loss of sensation in a circumscribed area of the body due to depression of excitation in nerve endings or inhibition of the conduction process in peripheral nerve. Local anesthesia produce loss of sensation without consciousness.

Local anesthesia techniques : 1- preparation of the child dental patient : The child will be told that to treat his teeth properly and comfortably this tooth is going to be ‘PUT TO SLEEP’ . At first ‘paste’ will be applied to put the gum to sleep. The parents, if present in the operating room, should be informed not to be interfere or comment or ask their child to open , or close his mouth or even try to help by encouraging words.

A patient who is going to receive LA A patient who is going to receive LA. For any kind of dental treatment should be prepared as follows: -He should fulfill and sign a medical history questionnaire, before any kind of dental practice. The patient maybe contraindicated to L.A. -The patient should be instructed not to be fasting. -If the patient is medically compromised he should receive his regular treatment and consult his physian. -Warm the anesthetic carpule by holding it for few minutes in your hand .

Position your patient correctly Position your patient correctly. It should be convenient to the surgeon and comfortable to the patient. Focus the head and spot light properly on the site of injection. Review the anatomy and sensory nerve course before injection. Be sure that the anesthetic solution is not expired. Dry the tissues at the site of injection. Apply antiseptic solution. Communicate with the patient. Establish firm hand rest.

A traumatic and painless injection: Apply topical anesthesia. Avoid using cold anesthetic solution. Do not display the needle in front of the patient. Deposit few drops slowly before touching the periosteum. Slowly deposit the anesthetic solution. You must not let the child see the syringe by follow some techniques as : Take the syringe from the assistant above the left shoulder of the child. Or

Application of topical anesthetics : Put your hand on his eyes. OR Adjust the light on his eyes. Application of topical anesthetics : -the application of topical anesthetic on the injection site can render needle insertion painless. -there is some evidence that use of topical anesthetic paste is better than use of topical spray, that may cause gagging sensation An acceptable topical anesthetic for oral use should be: - pleasant taste. -fast acting and effective. -cause no irritation.

Methods of use : Use one end of cotton wool roll to dry the site of insertion and the other end being used to apply the paste allow time about 2 minutes to work before the injection is given ‘to wash this paste away’.

Injection of local anesthesia : -anaesthetization of mandibular teeth and soft tissues: Inferior alveolar nerve block : When deep operative or surgical procedures are undertaken for the mandibular 1ry or permanent teeth , the inferior alveolar nerve must be blocked. The mandibular foramen is situated at level lower than the occlusal plane of the 1ry teeth of pediatric patient. So injection must be made slightly lower and posteriorly than for adult patient.

Technique : -is one in which the thumb is laid on the occlusal surface of the molars, with the tip of the thumb resting on the int. oblique ridge and the ball of the thumb resting in the retro molar fossa. -The barrel of the syringe should be directed on a plane between the two 1ry molars on the opposite side of the arch. It is advisable to inject a small amount of the solution as soon as the tissue is penetrate and to continue to inject minute quantities as the needle is directed toward the mand. Foramen . Approximately 1 ml of the sol. Should be deposited around the inf. Alv. Nerve.

Lingual nerve block : (0.1-0.2 ). -One can block the lingual nerve by bringing the syringe to the opposite side with the injection of a small quantity of the sol. As the needle is withdrawn. Long buccal nerve block :(0.5). For the removal of mandibular permanent molar or for placement of a rubber dam clamp on these teeth,it is necessary to anaesthetize the long buccal nerve. A small quantity of solution maybe deposited in the mucobuccal fold at a point distal and buccal to the indicated tooth.

Mental nerve block :( 0.75-1 ml ). used in the case of extraction or cavity preparation of lower 1ry. Molars when inf. Alv. Nerve block is contraindicated. mental n. exist the skull through the mental foramen which located 2.5 cm from the midline of the face . Technique : the foramen should be palpated with the middle finger of one hand and the lip lifted by the thumb and index finger of the same hand. The needle should be inserted at the inferior labial sulcus between first & second 1ry. Molars .

Primary infiltration anesthesia for mandibular molars : -injecting L.A. solution in the mucobucaal fold between the roots of 1ry. Mand. Molars. -the infiltration anesthesia was as effective as block anesthesia for all the performed therapies except for pulpotomy in mand. 2nd 1ry. Molar. Infiltration for mand. Incisors : - The labial cortical bone overlying the mand. Incisors is usually thin enough for supraperiosteal anesthesia.

If only superficial caries excavation of mandibular Incisors is needed or if the removal of a partially exfoliated 1ry. Incisor is planned ,infiltration anesthesia alone maybe adequate. Anesthetization of maxillary primary and permanent incisors and canines : local infiltration (supraperiosteal technique ) is used to anesthetize the 1ry. Ant. Teeth. the sol. Should be deposited close to the bone after the needle tip has penetrated the soft tissue at the mucobuccal fold, because the apices of the max. 1ry. Ant. Teeth are at the level of the mucobuccal fold.

Because nerve fibers may be extending from the opposite side, it may be necessary to deposit a small amount of sol. Adjacent to the apex of the other central incisor to obtain adequate anesthesia in either 1ry. Or permanent teeth. Before extraction of the incisors or canines in the 1ry. Dentition , it will be necessary to anesthetize the palatal soft tissues.

Anesthetization of maxillary 1ry. Molars and premolars : The bone overlying the 1st 1ry. Molar is thin and this tooth can be adequately anesthetized by injection of anesthetic solution opposite the apices of the roots. To anesthetize the Max. 1st or 2nd premolars a single injection is made at the mucobuccal fold allow the sol. To be deposited above the apex of the tooth. The injection should be made slowly, and the solution should be deposited close to the bone.

if the rubber dam clamp impinges on the palatal tissue, injection of a drop or two of the anesthetic sol. Into the free marginal tissue lingual to the clamped tooth will alleviate the discomfort and less painful than greater palatine injection.

Anesthetization of maxillary permanent molars : To anesthetize the max. 1st or 2nd permanent molars, the dentist instructs the child to partially close the mouth to allow the check and lips to be stretched laterally. The tip of the dentist’s left forefinger (for a right handed dentist ) will rest in a concavity in the mucobuccal fold and is rotated to allow the fingernail to be adjacent to the mucosa. The index finger should point in the direction of the needle during the injection.

the puncture point is in the mucobuccal fold above and distal to the distobuccal root of the 1st permanent molar. If the 2nd molar has erupted,the injection should be made above the 2nd molar. To complete the LA. Of the 1st permanent molar for operative procedures, the supraperiosteal injection is made by insertion of the needle in the mucobuccal fold and deposition of the sol. At the apex of the mesiobuccal root of the molar.

Intra dental papillary injection : Used in the case of ext. in upper jaw to avoid the palatal injection or lower jaw to avoid lingual injection. Technique : L.A. is injected into the palatal or lingual aspect of the interdental papilla mesial & distal to the tooth to be extracted.

Recent trend in local anesthesia : Topical anesthetic agents . L.A drugs. New modalities. a)- Recent trend in topical anesthesia : 1- EMLA (Eutectic mixture of L.A.). It is oil in water emulsion containing high concentration of lidocaine and prolicane in base result in EMLA. The intraoral application of EMLA as effective topical anesthesia more than traditional topical formulation but it require an extended period of application (5min).

Lidocaine patches : 1-Centbureidine : Mini patches act as topical anesthesia agent contain lidocaine to be applied on the mucous memb. Before injection. Electric current can be applied to it through electrophoresis device to allow the agent to rapidly penetrate the skin and mucous membrane. b) Local anesthetic local anesthesia : 1-Centbureidine : It is considered to be 5 to 8 time more potent than lidocaine, such that 0.5% of centbureidine equivalent to 2%. It characterized by – rapid onset - no side effect of CVS, CNS except in over doses.

2- articaine : new amide drug. It has several properties that make it high attractive. rapid onset.(1:2 min.). long duration anesthesia : infiltration 220-150min. Nerve block 270-225min. it is save agent for CNS,CVS except in over dose. contraindication: sulfur allergy. 3-Carbonated L.A : rapid onset 2min. less tissue irritation in compare with lidocaine .

But the stability of L.A. decrease as PH increase leading to considerable short shelf life of the agent so carbonated L.A. agent have be prepared just before injection. 4- Hyaluronidase: -Is an enzyme that breaks down intracellular, it is permits injection sol. To spread & penetrate the tissue rapidly, But it decrease the duration of action of the agent. -It is added to the anesthetic cartilage just before the injection by removing 1/3 of the anesthetic sol. &refilling the cartilage with hyaluronidase.

6-Ropivacine : 5-Ultra long acting L.A.: Tetrodoxine TTX & Sxitoxin STX they are biotoxins found in puffer fish. They block sodium channels on the nerve membrane when applied to outer memb. Surface& thus produce impulse conduction blockade. They are highly toxic. In dental field they still under research. 6-Ropivacine : It is long acting amide anesthesia. It’s potential in dentistry still need more clinical evaluation.

New modalities : Computer-controlled local anesthetic delivery system(wand). The system includes : A conventional local anesthetic needle. A disposable wand like syringe held by a pen grasp. A microprocessor with a foot control regulates the delivery of anesthetic solution through the syringe at a precision-metered flow rate, constant pressure, and controlled volume.

The system includes an aspiration cycle. block, infiltration, palatal and PDL injection are all reported to be more comfortable for all patient with wand than conventional injection techniques. In a randomized clinical trial comparing the Wand with traditional anesthetic delivery system, the use of the Wand led to significantly fewer disruptive behaviors in preschool-aged children.

THANK YOU EVERYONE