Chairside Dental Assisting Unit 6 - Anesthesia and Pain Control Notes

Pain Control Methods

  • Anesthetic Agents

  • Inhalation Sedation

  • Antianxiety Agents

  • Intravenous Sedation

  • General Anesthesia

  • Topical Anesthesia/Anesthetic Agent: Provides a temporary numbing effect on nerve endings on the surface of the oral mucosa.

    • Supplied As:

    • Ointments

    • Liquids

    • Sprays

Local Anesthesia

  • Definition: The agent most frequently used for pain control in dentistry.

  • Characteristics:

    • Nonirritating to the tissues at the injection site.

    • Produces minimal toxicity.

    • Rapid onset.

    • Provides profound/deep anesthesia.

    • Sufficient duration.

    • Sterile.

    • Completely reversible.

Mode of Action of Local Anesthesia

  • Mechanism: Temporarily blocks the normal generation and conduction of nerve impulses.

  • Injection Method: Injects the anesthetic near the nerve in the area intended for dental treatment.

Induction and Duration Time

  • Induction Time: The length of time from injection to complete and effective conduction blockage.

  • Duration: The length of time from induction until the reversal process is complete.

Classification of Local Anesthetics by Duration

  • Short-acting Anesthetics: Last 60-180 minutes (1-3 hours).

  • Intermediate-acting Anesthetics: Last 120-240 minutes (2-4 hours). Used for most general dental procedures.

  • Long-acting Anesthetics: Last 240-540 minutes (4-9 hours).

Vasoconstrictors

  • Function: Prolongs anesthesia duration by decreasing blood flow in the injection area and reducing bleeding during surgical procedures.

  • Types/Names: Epinephrine, Levonordefrin, NeoCobefrin.

  • Ratios of Local Anesthetic to Vasoconstrictor:

    • 1:20,000

    • 1:50,000

    • 1:100,000

    • 1:200,000

    • Note: Smaller the number, higher the concentration (e.g., 1:20,000 indicates a high concentration of vasoconstrictor).

Contraindications for Vasoconstrictors

  • Conditions:

    • Unstable angina.

    • Recent myocardial infarction (heart attack).

    • Recent coronary artery bypass surgery.

    • Untreated or uncontrolled severe hypertension (elevated blood pressure).

    • Untreated or uncontrolled congestive heart failure.

  • Action: Use anesthetics without epinephrine for these patients.

Injection Techniques

  • Infiltration: Injecting solution directly into the tissue at the site of the dental procedure, typically used for maxillary teeth.

  • Block Anesthesia: Injecting near a major nerve, numbing the entire area served by that nerve; typically required for most mandibular teeth due to their dense nature.

  • Palatal Anesthesia: Treatment involving soft tissues of the palate/surgery.

Local Anesthetic Cautions

  • Potential Issues:

    • Injection into a blood vessel.

    • Infected area.

    • Localized toxic reaction leading to prolonged anesthesia and paresthesia.

    • Systemic toxic reaction affecting CNS, heart, etc.

    • Temporary numbness, paresthesia.

    • Risks: May cause strain on the heart as local anesthetic is absorbed into the bloodstream and may interact with other medications the patient is taking.

Local Anesthesia Setup

  • Components of the Syringe:

    • Thumb Ring/Finger Grip: Control syringe.

    • Aspirate: Draw back to ensure injection is not into a blood vessel.

    • Harpoon: Sharp hook locking into the rubber stopper of the carpule/cartridge.

    • Piston Rod: Pushes rubber stopper.

    • Barrel of Syringe: Holds cartridge in place.

    • Threaded Tip: Attaches needle to syringe.

Disposable Needle Characteristics

  • Sterile and Protected: By a two-part plastic covering.

  • Beveled Tip: Angled tip; must face toward the bone before injection.

  • Lumen: The hollow center of the needle.

  • Needle Gauge: Thickness of needle; larger gauge indicates thinner needle (e.g., common sizes are 25, 27, 30).

  • Needle Length: Short (1 inch) and Long (1 5/8 inches).

Anesthetic Cartridge Management

  • Store at room temperature away from direct sunlight; do not freeze.

  • Inspect for cracks, chips, or damage; discard if discolored, cloudy, or past expiration date.

  • Preloading Warning: Do not leave the syringe preloaded with the needle attached for extended periods. Never reuse.

Commonly Used Dental Anesthetics

  • Lidocaine: 2% (Brand Names: Lignospan 2%, Octocaine 2%).

  • Mepivacaine: 2% and 3% (Brand Names: Carbocaine, Polocaine, etc.).

  • Prilocaine, Etidocaine, Bupivacaine, etc.

Assembling the Syringe

  • Steps to assemble:

    • Organize supplies out of the patient's view.

    • Select the correct needle for the area being treated.

    • Hold syringe in one hand; use thumb ring to pull back on the plunger while loading the cartridge with the other hand.

    • Release the thumb ring to allow harpoon to engage the stopper, ensuring engagement by slightly pulling back.

    • Break the seal on the needle, remove the protective cap, and screw the needle into the syringe.

Assisting in Administration of Local Anesthesia

  • Preparation Steps:

    • Wipe injection area with gauze.

    • Apply topical anesthetic for 3-5 minutes using a sterile cotton-tipped applicator.

    • Loosen needle guard.

    • Transfer syringe just below the patient’s chin by placing the thumb ring over the operator's thumb.

  • Post-Injection Actions:

    • Monitor the patient for adverse reactions.

    • Use a one-handed scoop or recapping device to replace the needle guard.

    • Rinse patient's mouth and inform them about the numbness, advising caution not to bite lip or cheek.

    • Safely remove needle and dispose of in sharps container.

Electronic Anesthesia

  • Definition: Noninvasive method blocking pain electronically using a low current through contact pads targeting specific waveforms to nerve bundles.

  • Patient Benefits:

    • No needles, no postoperative numbness or swelling.

    • Chemical-free, reduces fear and anxiety.

    • Patients maintain control over their comfort level.

Inhalation Sedation (Nitrous Oxide-Oxygen)

  • Purpose: Eliminates fear and helps relax the patient.

  • Effectiveness: Nonaddictive, easy onset with minimal side effects and rapid recovery. Produces stage I anesthesia to dull pain perception.

Equipment for Inhalation Sedation

  • Components:

    • Cylinders: Colored steel cylinders (green for O², blue for N²O).

    • N²O Machines: Portable or part of the dental unit.

    • Control Valves: Control flow of gases.

    • Flowmeter: Indicates gas flow rate.

    • Reservoir Bag: Where gases combine for patient breathing.

    • Nosepiece: Through which patient inhales gases.

    • Scavenger System: Protects from occupational risks of N²O exposure.

Safety Guidelines for Nitrous Oxide Usage

  • Recreational Use Warning: Never administer for non-medical purposes.

  • Hazard Reduction: Use scavenger systems, discourage patient conversation, inspect equipment regularly, and implement N²O monitoring badges.

Patient Preparation for Inhalation Sedation

  • Review health history and vital signs, explain the procedure, the importance of nasal breathing, and sensations to expect (e.g., tingling).

  • Provide reassurance to the patient.

Administration of Inhalation Sedation

  • Start with pure oxygen, titrate nitrous oxide to achieve desired sedation level (typically 70% N²O to 30% O²).

  • Instruct patients not to talk or mouth-breathe during the procedure. End administration with 100% O² for 3-5 minutes.

  • Record postoperative vital signs and compare with preoperative readings.

Antianxiety Agents

  • Purpose: Drugs for relief of anxiety during procedures.

  • Usage Criteria: For patients very nervous, procedures that are long or difficult, mentally challenged individuals, or very young patients needing extensive treatment.

  • Examples:

    • Secobarbital sodium (Seconal)

    • Chlordiazepoxide HCl (Librium)

    • Diazepam (Valium)

    • Chloral hydrate (Noctec): intended for children.

Intravenous Sedation

  • Administers antianxiety drugs intravenously during procedures at a controlled pace, providing deeper stage I analgesia.

General Anesthesia

  • Definition: A state of unconsciousness with loss of protective reflexes, inability to maintain airway independently, and unresponsive to physical stimulation or verbal command resulting in stage III general anesthesia.

Four Stages of Anesthesia

  • Stage I: Analgesia

    • Patient is relaxed and fully conscious, able to follow directions and exhibits euphoria with pain reduction; vital signs remains normal.

  • Stage II: Excitement

    • Patient becomes less aware of surroundings, may exhibit excitement and unmanageable behavior; nausea and vomiting can occur making this stage undesirable.

  • Stage III: General Anesthesia

    • Patient calms after stage II, feels no pain or sensation, and becomes unconscious. Requires anesthesiologist supervision in controlled environments.

  • Stage IV: Respiratory Failure or Cardiac Arrest

    • The stage marked by the lungs and heart slowing or stopping; if unaddressed, can lead to death.