DH Theory unit 2

Q: What is the purpose of topical anesthetic in dentistry?

A: To anesthetize terminal nerve endings in the mucous membrane before injection and increase patient comfort.

Q: Why must topical anesthetic be applied to dry tissue?

A: Dry tissue increases absorption and allows the drug to diffuse effectively.

Q: Why is the concentration of anesthetic higher in topical anesthetics compared to injectable anesthetics?

A: Because a higher concentration is needed to penetrate the mucous membrane (about 2–3 mm).

Q: What is the main purpose of topical anesthetic diffusion?

A: To allow the drug to pass through the mucous membrane and numb superficial nerve endings.

Q: Why is it critical to use only small amounts of topical anesthetic?

A: To avoid toxicity, since high concentrations can be absorbed systemically if overused.

Q: What types of topical anesthetics are available?

A: Both amide and ester formulations.

Q: In what forms are topical anesthetics prepared?

A: Gels, solutions, ointments, and sprays.

Q: Why can sprays that deliver a constant stream be dangerous?

A: They can deliver excessive amounts of anesthetic, increasing the risk of toxicity.

what are indications for Topical Anesthetic

Probing

Periodontal Dressing Removal

Scaling/Root Planing

Suture Removal

Prior to injections

what are contraindications to topical anesthetic

• Do not place topical anesthetic if there are Open sores/lesions

• Direct route to blood stream which will increase the potential for toxicity

• History of allergies or sensitivities

what are the steps of applying topical anesthetic

1. Medical History Update(Contraindications)

2. Explain the procedure (Informed Consent)

3. Vital Signs

4. Gather supplies (gauze, cotton tip applicator, topical)

5. Place patient in supine position

6. Examine the area

7. Dry the tissue (to remove saliva and clean the area) - (saliva will dilute and reduce  effectiveness)

8. Place small amount of the topical (leave 2-3 minutes) with a cotton-tip applicator

Q: What is a local anesthetic (LA)?

A: A drug that prevents the generation and conduction of nerve impulses.

Q: Are local anesthetics vasodilators or vasoconstrictors?

Vasodilators

Q: What is the primary mechanism of action of local anesthetics?

A: They reduce nerve membrane permeability to sodium ions.

Q: Why does blocking sodium ion movement prevent nerve conduction?

A: Sodium stays outside the nerve cell, so an action potential cannot occur.

Q: What happens to a nerve impulse when it reaches a blocked nerve segment?

A: It cannot be transmitted to the brain and is not interpreted as pain.

Q: What are the two main categories of local anesthetics used in dentistry?

A: Esters and Amides.

Q: How are ester anesthetics metabolized?

A: In the plasma.

Q: What is the most common ester used in dentistry?

A: Benzocaine (topical only)

Q: How are amide anesthetics metabolized?

A: Through biotransformation in the liver, and partially in plasma/lungs.

Q: Why is liver function important when using amide anesthetics?

A: It influences the rate of biotransformation.

Q: How are amide anesthetics excreted?

A: Through the urine.

Q: Why are amides preferred in dentistry over esters?

A: They are less likely to cause allergic reactions.

indications for use of LA

• Therapeutic scaling and Root Planing

• Deep Pocket Debridement

• Root/Tooth Sensitivity

• Furcation Involvement

• Periodontal/Oral Surgery

• RCT

• Restorative Procedure

what are absolute contraindications for LA

when Administering could be life- threatening

Q: Why is cardiovascular disease a concern when using local anesthetic?

A: Vasoconstrictors should be avoided or limited to a cardiac dose.

Q: What percentage of the population has a true allergy to local anesthetic?

A: About 1% — this is an absolute contraindication.

Q: What should be avoided in patients with a bisulfite (sulfite) allergy?

A: Any LA containing vasoconstrictors (epinephrine) — absolute contraindication to vasoconstrictors.

Q: Why is asthma a concern when using LA with vasoconstrictors?

A: Bisulfites can trigger bronchospasm; there is up to a 10% chance of reaction.

Q: What is the contraindication of LA for patients with uncontrolled hyperthyroidism?

A: Absolute contraindication to vasoconstrictors.

Q: Why should vasoconstrictors be minimized in patients with underactive thyroid?

A: They may be more sensitive and at higher risk for overdose.

Q: What is malignant hyperthermia and why does it matter for LA use?

A: It’s an inherited reaction to certain general anesthetic drugs requires physician consultation.

Q: Can pregnant patients receive local anesthetic?

A: Yes, but ideally in the 2nd trimester or postpone elective procedures.

Q: Why is significant liver disease a concern for LA administration?

A: Amides are metabolized in the liver, increasing overdose risk.

Q: Why is significant kidney disease less of a concern with LA?

A: Only a small amount of unmetabolized LA is excreted by the kidneys.

Q: Why should epinephrine be limited in diabetic patients?

A: Epinephrine opposes insulin, potentially altering blood glucose levels.

LA Vasodilative Properties

1.Increase rate of anesthetic absorption into

bloodstream by dilating blood vessels

2.Decrease in duration of LA action as it is carried

away from injection site

3.Higher plasma levels in the blood - increased

risk of toxicity

4. Increased bleeding in the area due to increase

blood flow.

Addition of Vasoconstrictors

Decreasing blood flow to the area by constricting the blood vessels

Provide hemostasis

Increased duration of LA’s effects

Reduce risk of toxicity

what are localized complications due to LA

occurs in the region of the injection, needle breakage

Cause: the needle, administration technique, type of anesthetic drug administered

hematoma

Swelling, bruising

Cause: puncturing of a blood vessel, due to over-insertion of needle

Apply Ice

Transient Facial Paralysis

• Loss of motor function, on one side

• Cause: local into parotid gland

• (Transient) – lasts a few hours

Paresthesia

• Prolonged anesthesia

• ‘frozen’ for hours/days following injection

• rare

Trismus

• muscle spasm causing ‘lock-jaw’

• Cause: irritation to the nerve sheath after injection due to repeated injections, too large a dose, or contaminated solution,

Edema

• Abnormal accumulation of fluid beneath the skin

• Cause: trauma during injection, infection, contaminated LA/needle

Tissue Sloughing

• Loss of surface layers of epithelium

• Cause: prolonged use of topical

Pain During LA Technique

• Cause: careless technique, dull needle, rapid deposit

Burning During Injection

• Cause: contaminated LA, heated cartridges, expired, rapid deposit

Systemic Complications are usually cased by

HIGH PLASMA CONCENTRATIONS of LA DRUGS

Q: What is a local anesthetic overdose?

A: The body’s response to excessively high blood levels of a local anesthetic drug.

Q: Under ideal conditions, how is local anesthetic absorbed?

A: Slowly and continuously from the injection site while being biotransformed, keeping toxicity risk low.

Q: What happens if LA is absorbed too quickly or in excessive amounts?

A: Blood levels rise too high, increasing the risk of overdose.

Q: How can injecting into a blood vessel cause overdose?

A: It delivers the drug directly into circulation, rapidly increasing blood levels.

Q: How does injecting an excessive amount of LA contribute to overdose?

A: More drug than the body can safely metabolize leads to toxic blood levels.

Q: Why is a fast rate of injection dangerous?

A: It overwhelms the body’s ability to absorb and metabolize the drug gradually.

Q: How does delayed drug clearance cause overdose?

A: Slow biotransformation (e.g., liver issues) allows LA to accumulate in the bloodstream.

Q: Why is aspiration important before injecting LA?

A: It helps avoid injecting directly into a blood vessel.

Q: Why should minimal doses be used?

A: Smaller amounts reduce the risk of reaching toxic blood levels.

Q: How do vasoconstrictors help prevent overdose?

A: They slow systemic absorption, keeping LA at the injection site longer.

Q: Why is reviewing the patient’s health status essential?

A: Conditions like liver disease or cardiovascular issues increase overdose risk.

Predisposing client Factors to development of an overdose

age, body weight, genetics, disease & gender

Predisposing Predisposing drug factors to development of an LA overdose

LA vasoactivity (potent or weak vasodilator), drug dose, route of administration, rate of injection, vascularity of injection site, presence of vasoconstrictors, other meds

Clinical Signs of a LA overdose

light-headedness, dizzy, visual/auditory disturbances, disorientation, drowsiness, elevated BP, HR, RESP. RATE, Muscle twitching, convulsions, unconscious, respiratory &/or CVS depression/arrest

management of LA overdose

• recognize signs and symptoms, monitor vitals, basic life support and maintain airway until help arrives

The most common overdose reaction is due to

 too large of a dose given. The onset of symptoms is gradual, but may be severe More common with amides.

Q: How does vasoconstrictor (epinephrine) overdose typically present?

A: Like a fight‑or‑flight response (rapid heart rate, anxiety, shaking).

Q: How long do adverse effects of vasoconstrictors usually last?

A: 5–10 minutes.

Q: Why can 5–10 minutes of epinephrine effects be dangerous for clients with severe cardiovascular disease?

A: Their heart cannot safely handle the increased workload caused by epinephrine.

Q: Which patients are more likely to experience epinephrine overdose?

A: Patients with cardiovascular disease.

Q: Why are topical anesthetics absorbed quickly?

A: Because mucous membranes allow rapid drug penetration.

Q: When does topical anesthetic pose a higher risk of toxicity?

A: When applied over an entire arch or quadrant instead of a small area.

Q: Why must dosage guidelines be followed for local anesthetics?

A: To prevent systemic toxicity and overdose.

Q: Why should clinicians use the lowest possible epinephrine ratio?

A: To reduce the risk of vasoconstrictor toxicity.

Q: How common are true allergies to amide anesthetics?

very rare

Q: Which products require caution in patients with allergies?

A: Topical anesthetics and anesthetics containing vasoconstrictors.

Q: What are local signs of an allergic reaction?

A: Erythema, urticaria, pruritis, angioedema.

Q: What are systemic signs of an allergic reaction?

A: Bronchospasm, dyspnea, wheezing, cyanosis, tachycardia, laryngeal edema.

Q: Which type of allergic reaction onset is more serious: delayed or immediate?

A: Immediate onset.

Q: What emergency drug is used for anaphylaxis?

Epinephrine

Q: What four steps help prevent LA complications?

A: Aspiration, minimal dose, vasoconstrictor use (if appropriate), thorough health assessment.

Q: What is the main advantage of eutectic mixtures?

A: Faster onset and deeper topical penetration.

Q: Why do eutectic mixtures penetrate deeper?

A: Their combined melting point is lower, forming a liquid that diffuses easily.

Q: What does EMLA stand for?

A: Eutectic Mixture of Local Anesthetics.

Q: Is EMLA used in dentistry?

no

Q: What procedures is Oraqix used for?

A: Scaling and root planing (SRP).

Q: What are the active ingredients in Oraqix?

A: Lidocaine 2.5% and prilocaine 2.5% (both amides).

Q: Why does Oraqix stay inside the periodontal pocket?

A: It has thermosetting properties—liquid at room temperature, gels at body temperature.

Q: How is Oraqix applied?

A: Using a blunt tip applicator to fill the periodontal pocket.

Q: Does Oraqix provide pulpal anesthesia?

no

Q: What is the cartridge volume for Oraqix?

A: 1.7 mL.

Q: Why is Oraqix considered low‑risk for toxicity?

A: It has low systemic absorption and easy dose tracking.

Q: What should you check before assembling Oraqix?

A: Make sure the bubble moves in the cartridge (indicating it is still liquid).

Q: What should you do if the Oraqix cartridge has already gelled?

A: Cool it briefly (refrigerate or place in cool water) to return it to liquid form.

Q: What are the steps to assemble the Oraqix applicator?

• Pierce the cartridge with the blunt tip applicator.

• Reset the handle dial to the start position.

• Screw the cartridge into the handle.

• Bend the applicator tip if needed (not more than 45°).

Q: What happens to Oraqix once it is placed subgingivally?

A: It becomes a gel at body temperature and stays in place.

Q: How long does Oraqix take to start working?

A: About 30 seconds.

Q: How long does Oraqix last?

A: About 20 minutes (range 14–31 minutes).

Q: What is the maximum amount of Oraqix you can use per session?

A: 5 cartridges (8.5 g gel).

Q: How much Oraqix is needed for one quadrant?

A: One 1.7 g cartridge.

Q: Where should used blunt tip applicators and cartridges be disposed?

A: In the sharps container.

Q: How should the Oraqix handle be cleaned?

A: Wipe with surface disinfectant (Birex/Optim), then autoclave in a poly paper bag.