Chapter 37 Anesthesia and Pain Control in Dentistry Copyright 2003, Elsevier Science (USA) All rights reserved. No part of this product may be reproduced or transmitted in any form or by any means, electronic or mechanical, including input into or storage in any information system, without permission in writing from the publisher. PowerPoint® presentation slides may be displayed and may be reproduced in print form for instructional purposes only, provided a proper copyright notice appears on the last page of each print-out. Produced in the United States of America ISBN 0-7216-9770-4

Introduction The practice of various psychological, physical, and chemical approaches to the prevention and treatment of preoperative, operative, and postoperative anxiety and pain. Methods of pain control Anesthetic agents Inhalation sedation Antianxiety agents Intravenous sedation General anesthesia

Anesthetic Agents The numbing of a specific site or area. Topical Anesthesia provides a temporary numbing effect on nerve endings that are located on the surface of the oral mucosa. Supplied as: Ointments Liquids Sprays

Local Anesthesia Agents most frequently used for pain control in dentistry. Criteria for use: Be nonirritating to the tissues in the area of the injection. Produce minimal toxicity. Be of rapid onset. Provide profound anesthesia. Be of sufficient duration. Be completely reversible. Be sterile.

Method of Action Local anesthesia temporarily blocks the normal generation and conduction action of the nerve impulses. Local anesthesia is obtained by injecting the anesthetic agent near the nerve in the area intended for dental treatment. Induction time is the length of time from the injection of the anesthetic solution to complete and effective conduction blockage.

Duration Length of time from induction until the reversal process is complete. Short-acting: Local anesthetic agent lasts less than 30 minutes. Intermediate-acting: Local anesthetic agent lasts about 60 minutes. Long-acting: Local anesthetic agent lasts longer than 90 minutes.

Vasoconstrictor Criteria for use: Prolongs the duration of an anesthetic agent by decreasing the blood flow in the immediate area of the injection. Decreases bleeding in the area during surgical procedures. Types: Epinephrine Levonordefrin Norepinephrine

Vasoconstrictor- cont’d Ratio of vasoconstrictor to anesthetic solution: 1:20,000 1:50,000 1:100,000 1:200,000

Vasoconstrictor- cont’d Contraindications for the use of vasoconstrictors Unstable angina. Recent myocardial infarction. Recent coronary artery bypass surgery. Untreated or uncontrolled severe hypertension. Untreated or uncontrolled congestive heart failure.

Types of Local Anesthesia Injections Infiltration is achieved by injecting the solution directly into the tissue at the site of the dental procedure. Most frequently used to anesthetize the maxillary teeth. Used as a secondary injection to block gingival tissues surrounding the mandibular teeth.

Types of Local Anesthesia Injections- cont’d Block anesthesia The solution is injected near a major nerve, and the entire area served by that nerve is numbed. Type of injection required for most mandibular teeth. Inferior alveolar nerve block Obtained by injecting the anesthetic solution near the branch of the inferior alveolar nerve close to the mandibular foramen. Type of injection for half of the lower jaw, including the teeth, tongue, and lip.

Types of Local Anesthesia Injections- cont’d Incisive nerve block Injection given at the site of the mental foramen. Used when the mandibular anterior teeth or premolars require anesthesia. Periodontal ligament Alternative infiltration anesthesia method by which the anesthetic solution is injected directly into the periodontal ligament and surrounding tissues.

Table 37-2 Local Anesthesia Setup: Anesthetic Syringe

Local Anesthesia Setup Anesthetic carpule: Care and caution of use Cartridges should be stored at room temperature and protected from direct sunlight. Never use a cartridge that has been frozen. Do not use a cartridge if it is cracked, chipped, or damaged in any way. Never use a solution that is discolored or cloudy or has passed the expiration date. Do not leave the syringe preloaded with the needle attached for an extended period of time. Never save a cartridge for reuse.

Table 37-3 Disposable Needle

Local Anesthetic Cautions Injection into a blood vessel Infected area Localized toxic reaction Systemic toxic reaction Temporary numbness Paresthesia

Electronic Anesthesia A noninvasive method to block pain electronically by using a low current of electricity through contact pads that target a specific electronic waveform directly to the nerve bundle at the root of the tooth. Benefits to the patient: No needles. No post-operative numbness or swelling. Chemical-free method of anesthesia. No risk of cross-contamination. Reduces fear and anxiety. Patients have control over their own comfort level.

Inhalation Sedation Nitrous oxide/oxygen (N²O/O²) is a combination of these gases that the patient inhales to help eliminate fear and to help the patient relax. History Dates back to 1844. Dr. Horace Wells first used it on his patients. Effects Non addictive. Easy onset, minimal side effects, and rapid recovery. Produces stage I anesthesia. Dulls the perception of pain.

Contraindication of Using N²O/O² Pregnancy: First trimester Nasal obstruction: Problems inhaling through the nose Emphysema: Increased O² Multiple sclerosis: Breathing difficulties Emotional stability: Altered perception of reality

Inhalation Sedation Equipment Cylinders: Gases are dispensed in steel cylinders, which are colored green for O² and blue for N²O. N²O machines: Portable or part of the dental unit. Control valves: Control the flow of each gas. Flowmeter: Indicates the rate of flow of the gases. Reservoir bag: The two gases are combined in this bag and the patient draws on it for breathing.

Inhalation Sedation Equipment- cont’d Gas hose Carries the gases from the reservoir bag to the mask or nosepiece. Masks: Supplied in sizes for adults and children The nosepiece through which the patient breathes the gases. Scavenger system Protection from the occupational risks of N²O.

Exposure to Nitrous Oxide Used only for patient treatment. Never administered for recreational purposes. How to reduce N²O hazards to dental personnel Use a scavenger system. Use a patient mask that fits well. Discourage patients from talking. Vent gas outside the building. Routinely inspect equipment and hoses for leaks. Use an N²O monitoring badge system.

Patient Preparation for Inhalation Sedation Review health history. Obtain base-line vital signs. Describe the procedure of administering the gases. Describe the use of the mask and the importance of nasal breathing. Describe the sensations that the patient will experience. Reassure the patient.

Assisting in the Administration of Inhalation Sedation Start with pure oxygen while establishing the patient’s tidal volume. Slowly titrate the nitrous oxide until the desired results are achieved. Patients should refrain from talking or mouth breathing. The N²O/O² analgesia should end with the administration of 100% O² for 3 to 5 minutes. Obtain postoperative vital signs and compare them to the preoperative recordings.

Antianxiety Agents For the relief of anxiety. Sedatives Criteria for use: Patients are very nervous about a procedure. Procedures are long or difficult. Mentally challenged patients. Very young children requiring extensive treatment.

Sedatives Commonly prescribed: Secobarbital sodium (Seconal) Chlordiazepoxide HCl (Librium) Diazepam (Valium) Chloral hydrate (Noctec): For children

Intravenous Sedation Antianxiety drugs that are administered intravenously continuously throughout a procedure at a slower pace, providing a deeper stage I analgesia.

Intravenous Sedation- cont’d Patient assessment A health history, physical examination, and signed consent are performed. Baseline vital signs are taken and recorded. Oximetry and electrocardiogram are completed and recorded. Weight taken and recorded for dose determination.

Intravenous Sedation- cont’d Patient monitoring Physiologic measurements taken and recorded every 15 minutes. Level of consciousness Respiratory function Oximetry Blood pressure Heart rate Cardiac rhythm

General Anesthesia A controlled state of unconsciousness in which there is a loss of protective reflexes, including the ability to maintain an airway independently and to respond appropriately to physical stimulation or verbal command. This controlled state in loss of consciousness, produces stage III general anesthesia.

General Anesthesia- cont’d Pharmacologic make-up Combination of gases N²O/O² Halothane or enflurane mixtures Intravenous agents such as thiopental sodium and methohexital sodium

Four Stages of Anesthesia Stage I: Analgesia is the stage at which a patient is relaxed and fully conscious. The patient is able to keep his or her mouth open without assistance and is capable of following directions. The patient will have a sense of euphoria and a reduction in pain. Vital signs are normal. Depending on the agent, the patient can move into different levels of analgesia.

Four Stages of Anesthesia- cont’d Stage II: Excitement is the stage at which a patient is less aware of his or her immediate surroundings and can start to become unconscious. The patient can become excited and unmanageable. Nausea and vomiting can occur. This is an undesirable stage.

Four Stages of Anesthesia- cont’d Stage III: General anesthesia is the stage of anesthesia that begins when the patient becomes calm after stage II. The patient feels no pain or sensation. The patient will become unconscious. This stage of anesthesia can be met only under the guidance of an anesthesiologist in a controlled environment such as a hospital.

Four Stages of Anesthesia- cont’d Stage IV: Respiratory failure or cardiac arrest is the stage at which the lungs and heart slow down or stop functioning. If this stage is not reversed quickly, the patient will die.

General Anesthesia- cont’d Patient preparation Preoperative physical examination. Laboratory tests. Patient or legal guardian must sign a consent form. Preoperative instructions Dentist will review the procedure, as well as the risks. Must not have anything to drink or eat 8 to 12 hours before receiving general anesthesia.

Record Keeping for Sedation Methods Always document the following measures and observations: Review of patient’s medical history. Preoperative and postoperative vital signs. Patient’s tidal volume if using inhalation sedation. Time anesthesia began and ended. Peak concentration administered. Amount of postoperative time (in minutes) for patient recovery. Adverse events or patient complaints.