Dental Anesthetics Study Guide

• Study notes on Anesthetics

Topical Anesthetics

• Topical anesthetics numb a specific area before injection.
• Ointments are applied with a Q-tip to the injection site for 15-30 seconds up to 1-2 minutes.
• Topical anesthetics are available as ointments, gels, sprays, liquids, and patches.

Local Anesthesia

• Local anesthesia is injected near the nerve in the treatment area.
• It temporarily blocks the nerve's ability to generate a pulse.
• Local anesthesia takes effect quickly and is sterile.

General Anesthesia

• General anesthesia results in a loss of consciousness.
• It is commonly used for restorative dentistry.

Most Common Pain Control

• Local anesthesia is the most frequently used form of pain control in dentistry.

Vasoconstrictors

• Vasoconstrictors are added to local anesthetics to slow intake and increase duration.
• Epinephrine is the most commonly used vasoconstrictor.
• The greatest concentration of a vasoconstrictor in an anesthetic is 1:20,000.

Contraindications for Vasoconstrictors

• Angina (chest pain).
• Recent myocardial infarction (heart attack).
• Recent heart surgery (bypass surgery).
• Uncontrolled or untreated congestive heart failure.

Infiltration Injection

• An infiltration injection involves injecting into a small, isolated area, typically for one tooth.
• It is commonly injected into the mucobuccal fold near the apex of the tooth.

Block Injection

• Block injection is used when working on more than one tooth.

Field Block

• Field block involves an injection near a larger nerve branch.
• Applied when working on two or more teeth.

Nerve Block

• Nerve block involves injecting anesthetic close to the main nerve trunk.
• Used for quadrant dentistry.

Anesthetic Syringe Parts

• Thumb ring: Controls the syringe and aspirates effectively.
• Harpoon: Sharp hook that locks the stopper of the cartridge, allowing aspiration.
• Piston rod: Pushes the stopper and solution through the needle.
• Syringe barrel: Holds the anesthetic cartridge.
• Threaded tip: Allows needle attachment to the syringe barrel.

Needle Parts

• Cartridge end: Attaches to the syringe.
• Needle hub: Body of the needle.
• Injection end: Needle with a beveled tip.
• Protective cap: Protects the end that attaches to the syringe.
• Seal on cap: Ensures sterility; do not use if broken.
• Needle guard: Protects the needle that enters the skin.

Cartridge/Carpule Parts

• Rubber diaphragm.
• Aluminum cap.
• Neck.
• Drug identifying color band.
• Plunger indented from the rim of glass/silicone rubber plunger.

Needle Gauge and Length

• A short needle (1 inch) is used for infiltration anesthesia.
• A long needle (1 5/8 inches) is used for block anesthesia.
• Larger gauge means a thinner needle, and small gauge means a thicker needle.

Loading an Anesthetic Syringe

• Inspect the syringe.
• Retract the piston rod fully using the thumb ring.
• Place the cartridge in the barrel with the stopper end first, then release the piston rod.
• Push the piston rod into the rubber stopper until it is fully engaged.
• Remove the protective plastic cup from the needle end and screw the needle onto the syringe.
• Attach the needle guard to the needle cap.
• Carefully remove the protective cover, hold the syringe upright, replace the cap, and place it on the tray.

Aspiration

• The dentist aspirates by pulling back the needle to check for blood in the cartridge.
• If blood is present, the dentist repositions the needle.

Hypersensitive Reactions

• Injection into a blood vessel.
• Infected areas.
• Toxic reactions.
• Temporary numbness.
• Paresthesia.

Topical Application Time

• Topical anesthetics should be applied to the mucosa for a minimum of 15-30 seconds and a maximum of 1-2 minutes.

Paresthesia

• Paresthesia is a condition where an area remains numb beyond the usual time.
• It can be temporary or permanent.

Nitrous Oxide

• Nitrous oxide and oxygen gases are combined to relieve apprehension during treatment.
• This combination is a safe sedation method for patients who experience fear during dental care.