APC 101

Methods of Pain Control

• Anesthetic agents 
• Inhalation sedation
• Antianxiety agents 
• Intravenous (IV) sedation
• General anesthesia

What is an example of a psychological method to help prevent and treat pain and anxiety before, during, and after a dental procedure? (Talking with the patient in a calm, gentle, and caring manner while addressing any questions about the anesthesia and procedure.)

What is an example of a physical approach? (Gentle handling of the patient, avoiding fast, unexpected movements.) 

Providing a patient with a painless dental experience will make future appointments more pleasant.

Anesthetic agents include topical anesthetics (jelly) and local anesthetics (injectables).

Nitrous oxide and oxygen are the most common inhalation sedatives, but antianxiety medications may also be prescribed to be taken by mouth before the dental procedure.

Medications may also be administered IV alone or IV in combination with inhalation agents to provide deeper levels of analgesia and anesthesia.

Topical Anesthesia

• Provides a temporary numbing effect on nerve endings located on the surface of the oral mucosa 
• Supplied as:
  • Ointments
  • Liquids
  • Sprays

The most commonly used topical anesthetic is a jellylike ointment, usually 20% benzocaine.

Must be left on long enough to effectively permeate the oral mucosa before injectionof a local anesthetic.

What step helps promote effective penetration of the topical anesthetic? (Drying the membranes with the use of gauze to avoid dilution.)

Sprays are sometimes used in patients with severe gag reflexes.

Local Anesthesia

• The agent most frequently used for pain control in dentistry 
• Characteristics/advantages
  • Is nonirritating to the tissues in the area
    of the injection 
  • Is miminally toxic
  • Rapid in onset 
  • Delivers profound anesthesia 
  • Duration of action is sufficient
  • Sterile 
  • Completely reversible 

Most patients experience minimal pain with the proper administration of topical anesthetic before injection of the local anesthetic.

In children, is it important to know how much the child weighs because the dentist must be careful not to exceed the maximum allowable dose, which is calculated as milligrams of the drug administered per kilogram, or pound, of body weight. 

Mechanism 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. 

The dentist will normally test for anesthesia before beginning the procedure by touching local and distant tissues that are normally nonresponsive with adequate anesthesia.

It is also important to help the patient differentiate pain from other unpleasant sensations such as vibration, pressure, and noise. None of these other problems can be resolved with the use of additional local anesthesia.     

Duration

• Time from induction to completion of the reversal process
• Short-acting
  • Local anesthetic agent lasting 60 to 180 minutes
• Intermediate
  • Local anesthetic agent lasting 120 to 240 minutes 
• Long-acting
  • Local anesthetic agent lasting 240 to 540 minutes

What is a dental procedure that might require a short-acting local anesthetic? What might require longer anesthesia?

Sometimes a procedure takes longer than anticipated; some people metabolize anesthesia faster than anticipated, so additional local anesthesia is administered.

Remember that local anesthetic also has a different duration of action on the pulp of the tooth versus the soft tissue of the oral mucosa.

Vasoconstrictors

• Indications 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 
  • Neo-Cobefrin  

During a surgical procedure, additional anesthetic may be injected directly into the surgical site, not because the patient is feeling pain but because additional hemostasis is required (to stop bleeding). 

Because a vasoconstrictor prolongs the duration of action, this allows for the use of less anesthetic.

Epinephrine is one of the vasoconstrictors most commonly added to local anesthetics used in dentistry.

Ratio of Anesthetic Solution to Vasoconstrictor

• 1:20,000
• 1:50,000
• 1:100,000
• 1:200,000 

What ratio represents a higher concentration of vasoconstrictor mixed with local anesthetic? (1:20,000)

1: 20,000 means that there is 1 g (or 1000 mg) of solute (drug) contained in 20,000 mL of solution (0.05 mg/mL).

Why use a higher concentration of vasoconstrictor? (To prolong the effect of the local anesthesia and to decrease/control bleeding in the area.) 

Contraindications to 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 

In addition to these contraindications for the use of a vasoconstrictor, numerous medications that a patient may be taking may necessitate limited or no usage of a vasoconstrictor.

There are situations in which an otherwise healthy patient presents for emergency treatment and because of the vital signs (increased blood pressure as a result of extreme pain and or lack of sleep) may require the use of less vasoconstrictor than normal.

Injection Techniques

• 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.
• Block anesthesia is achieved by injecting near a major nerve, with the entire area served by that nerve being numbed. 
  • Type of injection required for most mandibular teeth

What is an important consideration with respect to the needle when you are loading the syringe with a cartridge? 

A short needle is generally used for the administration of all types of local anesthesia in children.

Remember, when passing the loaded syringe to the dentist, keep it below the patient’s chin and away from the field of view. Keep the loaded syringe present throughout the procedure in the event that additional anesthesia is required.

Maxillary injections.
A, Local infiltration.   B, Field block.   C, Nerve block.
(From Malamed SF: Handbook of local anesthesia, ed 5, St Louis, 2004, Mosby.)

The upper middle photo demonstrates the proper positioning of the needle during a posterior superior alveolar nerve block, which is used to anesthetize the maxillary first, second, and third molars. 

The bottom left photo highlights the approximate positioning of a lower right inferior alveolar nerve block of the mandible.

The bottom right photo demonstrates interproximal insertion of the needle, buccal to lingual, to deposit additional anesthetic after the completion of an incisive nerve block.

Anesthetic Cartridge

• Precautions
  • 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. 
  • Never save a cartridge for reuse.  

Where should used or unused damaged anesthetic cartridges, as well as needles, be deposited? (In a sharps container that is disposed of properly.)

Always check expiration dates and, when restocking a treatment room, place the older cartridges in such a way that they will be used before the newer ones. 

It is prudent to leave used local anesthetic cartridges on the treatment tray until the procedure has been completed so that an accurate account of the amount of anesthetic used is properly documented in the patient records.

Color-coding of local anesthetic cartridges.
(From Malamed SF: Handbook of local anesthesia, ed 5, St Louis, 2004, Mosby.)

This chart outlines the color-coding system developed by the American Dental Association for the various types of local anesthesia with and without a vasoconstrictor. The chart corresponds to color bands on the cartridges.

Although the bands offer a tool for quick recognition, dental assistants should always double-check by reading the label as well.