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Questions and Answers

What is the primary purpose of a topical anesthetic?

To provide permanent numbness to deep tissue

To block sensory nerve endings to the tooth

To enhance blood circulation in the treatment area

To provide temporary numbness to sensory nerve endings of surface mucosa (correct)

Which type of tissue is known to absorb topical anesthetics the fastest?

Buccal mucosa

Palatal mucosa

Attached gingiva

Vestibular tissues (correct)

Which characteristic should a good topical anesthetic possess?

Should induce hypersensitivity

Should delay healing

Should be non-irritating to tissues (correct)

Should be difficult to wash off

What is the most widely used topical anesthetic agent?

Benzocaine Signup and view all the answers

What is a primary drawback of ester anesthetics compared to amide anesthetics?

Less effective and shorter acting Signup and view all the answers

Which of the following forms of topical anesthetics is NOT one of the listed forms?

Capsules Signup and view all the answers

What is the recommended application time for benzocaine to achieve optimum effect?

1-2 minutes Signup and view all the answers

What characteristic distinguishes amide anesthetics from ester anesthetics?

Have a different chemical structure Signup and view all the answers

What is the typical onset time for lidocaine when used as a topical anesthetic?

1-2 minutes Signup and view all the answers

Which of the following statements about topical anesthesia is incorrect?

It has a longer duration compared to injection anesthesia. Signup and view all the answers

What is the duration of effectiveness for lidocaine when used as a topical anesthetic?

15 minutes Signup and view all the answers

What is a common symptom of an allergic reaction to anesthetics?

Difficulty swallowing Signup and view all the answers

Why should lidocaine not be used over a large area?

It can cause immediate elevation of anesthetic blood levels. Signup and view all the answers

What is the primary purpose of a bioadhesive patch for topical anesthetics?

To improve the duration of contact between the anesthetic and tissue. Signup and view all the answers

What is a potential effect of an overdose of local anesthetics?

Increased talkativeness Signup and view all the answers

Which of the following types of anesthetics has a greater tendency to produce allergic reactions?

Ester type drugs Signup and view all the answers

Study Notes

Purpose of Topical Anesthetics

Induces temporary numbness to sensory nerve endings in surface mucosa.
Does not impact sensory nerves related to teeth.
Depth of anesthesia depends on drug absorption, influenced by tissue thickness and keratinization.

Absorption Characteristics

Vestibular tissues absorb anesthetics quickly.
Attached gingiva and buccal mucosa have slower absorption rates.
Skin, lips, and palatal mucosa exhibit high resistance to absorption.

Uses of Topical Anesthetics

Administered prior to local anesthesia injections.
Prevents gagging during x-ray exposure and impressions.
Assists in dental procedures such as probing, scaling, and suture removal.
Facilitates crown seating and matrix band placement.
Provides pain relief for localized issues like oral ulcers and injuries.

Characteristics of Effective Topical Anesthetics

Should produce lasting and effective anesthesia.
Must be stable in its applied form.
Anesthetic agent should release easily from preparation upon application.
Non-irritating to tissues and should not cause hypersensitivity.
Should not be toxic at required concentrations and should not delay healing.
Capable of being washed off with water.

Forms of Topical Anesthetics

Available in various formulations, including ointments, gels, liquids, sprays, oral rinses, and patches.

Components of Anesthetic Agents

Esters
- First local anesthetic used was cocaine, which had adverse side effects.
- Esters were developed to retain cocaine's properties while reducing side effects.
- Associated with allergic reactions, less effective and shorter acting compared to amides, primarily used for topical applications.
Amides
- Developed later with a distinct chemical structure.
- Generally lack significant allergic reactions.
- Potential risks include toxicity and drug overdose; cause vasodilation.

Types of Topical Anesthetics

Benzocaine (Ester)
- Most commonly used, available in various forms.
- Minimal blood absorption; low toxicity potential.
- Onset in 30 seconds, optimum effect in several minutes, duration between 5-15 minutes.
Tetracaine Hydrochloride (Ester)
- Rapid absorption with high toxicity risk; not recommended for large areas.
- Onset in 2 minutes, duration 20-60 minutes.
Lidocaine (Amide)
- Rare allergic reactions, unlikely to cause toxicity.
- Onset in 1-2 minutes, maximum effectiveness in 5 minutes, duration of 15 minutes.
- Available as spray, ointment, and transoral patches.
Lidocaine Transoral Patch
- Bioadhesive design extends duration of contact between anesthetic and tissue.
- Powerful soft tissue anesthesia with minimal pulpal anesthesia.
- Onset takes 2.5 to 5 minutes, maximum effectiveness reached in 15 minutes, lasting 45 minutes post-application.

Topical vs. Injection Anesthesia

Topical Anesthesia
- Affects gingival sensation; has short duration and slower onset (3-5 minutes).
- Recommended wait time of 5 minutes before starting injections or procedures.
Injection Anesthesia
- Affects both teeth and gingiva; provides longer duration and faster onset.

Adverse Reactions

Allergic Responses
- Greater tendency for esters to cause allergies than amides, with symptoms ranging from mild erythema to life-threatening anaphylaxis.
Overdose Risks
- Occurs from excessive anesthetic spread and rapid absorption, leading to elevated blood levels.
- Symptoms include increased talkativeness, anxiety, elevated pulse, and blood pressure.

Application Technique

Use a cotton-tipped applicator to gather ointment on gauze.
Dry the injection site with sterile gauze.
Position applicator directly on the injection site; use a new applicator for each site.
Maintain the applicator in place for the manufacturer's recommended time, minimum of 1 minute.