Novocain: Local Anesthesia in Dentistry (the “shot”)
Local anesthesia in dentistry (commonly referred to as Novocain), is used to completely remove the pain sensation of the dental procedure. Local anesthetic works by the chemical process known as dissociation. The Novocain (anesthetic) is in the form of two or more chemicals attached to one another. In healthy tissue, the pH in the tissue allows the chemicals that are hooked together to become ‘unhooked’ or to dissociate. The separation of these chemicals from one another frees up the one chemical that blocks the movement of sensation along the nerve fiber.
If the soft tissue in the area of the injection is infected, this means the pH in the area is different from an area of healthy soft tissue. This means the chemicals cannot dissociate enough to free up the chemical that blocks the nerve sensation. In this instance, the anesthesia won’t work as well and it takes a number of injections to get the patient “numb”. There is a limit to the amount of anesthesia that can be administered according to body weight. It is often considered a better practice to rid the patient of infection prior to treating the dental problem that requires anesthesia.
There are some complications that can occur with the administration of local anesthesia in the dental office. The most common of these are dizziness, a rapidly beating heart (tachycardia), agitation, and tremors. These problems are usually short lived and pass without further incident.
More serious complications include seizures, and bronchial spasms (allergic reactions). It can be stated that dental local anesthesia can be considered safe and that complications can be reduced if:
- patients are routinely evaluated for risk factors (the most common being cardiovascular disease and allergies) with an adequate medical history prior to dental treatment
- doses of local anesthetics are determined according to body weight
- anesthetics with no or low concentrations of epinephrine are used
Analgesia: Inhalation Sedation with Nitrous Oxide or “Laughing Gas”
Nitrous oxide (N2O/O2) is a gas that is delivered through a face mask as an analgesic; it works to relieve pain and it induces a sense of calm. It has no color, smell, and doesn’t irritate the mouth, throat or lungs. Some patients experience hearing and visual effects as well. The use of N2O/O2 helps the patient relax and makes any dental procedure move along faster and easier.
Today, we know that nitrous oxide gas (N2O) can only be used for short periods of time without mixing it with at least O2 (oxygen). Nitrous oxide gas and a lack of oxygen can lead to unconsciousness and death. The “laughing gas” used now is called N2O-O2, and contains 70% oxygen to 30% nitrous oxide.
Advantages of Nitrous Oxide/Oxygen Sedation:
- It reaches the brain within 20 seconds creates a feeling of relaxation and pain relief after about 2-3 minutes.
- The degree to which you are sedated can be altered up or down easily.
- Once the sedation is decreased as the procedure comes to completion, you are placed on O2 and there are no after effects. The gas leaves your body within about 3-5 minutes and there are no restrictions to driving or operating machinery.
- With nitrous oxide, it’s easy to give incremental doses until the desired action is obtained (this is called “titration”).
- For some procedures such as scaling and root planing, it may be possible to forego the use of local anesthesia, completely eliminating the use of the needle. This can vary widely, however and cannot be considered valid for everyone.
- In the case of severe needle fear, N2O/O2 can be used first in order to help you relax prior to receiving the local anesthetic injection.
- Inhalation sedation is very safe. It has very few side effects and the drugs used have no ill effects on the heart, lungs, liver, kidneys, or brain.
- N2O/O2 has been shown to greatly reduce the problem of gagging.
- It’s safe to use with a history of: epilepsy, liver disease, heart disease, diabetes, or cardiovascular disease.
Disadvantages of Nitrous Oxide/Oxygen Sedation:
- Some patients simply do not reach an adequate level of sedation with safe levels of oxygen.
- A respiratory infection, any inability to breath through your nose (such as a habitual mouth breather ), an issue with claustrophobia, would prohibit the use of N2O/O2.
- Some patients don’t like the feeling of a loss of control experienced with the use of N2O/O2.
- Some patients get nauseous when N2O/O2 is used
- There is a possibility that the dental team can experience certain health problems when continuously exposed to N2O/O2 (such as spontaneous abortion).
- Contraindications to the use of N2O/O2 are: patients with MS, emphysema, chest problems, recent eye surgery, eye pressure disorders, and during the first trimester of pregnancy.
Oral Sedation in Dentistry
Oral sedation dentistry involves the oral administration of sedative drugs. Dental patients with generalized anxiety, fear of needles, prior dental trauma, or generalized fear of the dentist can take oral medication and reduce their anxiety. Oral sedation requires you be driven to and from your dental appointment.
Advantages of Oral Sedation:
- Ease of administration (you only have to take a pill)
- No needles involved
- High patient acceptance
- Amnesic effect
- Lower cost ( as opposed to IV Sedation)
- Allows more treatment to be completed in a shorter period of time
IV Sedation in Dentistry
IV Sedation or conscious sedation is when a drug is injected into a vein in your arm or the back of your hand. It enters the bloodstream creating a sense of deep relaxation and amnesia (memory loss). You will be conscious and able to understand and respond to the operator, however, you will not remember anything once the drug wears off. This type of sedation still requires you get local anesthetic for the dental procedure: it’s an anti-anxiety drug, not a pain medication.
Your pulse and oxygen level (pulse-ox) are measured throughout the entire procedure; this allows the operator to determine if you are getting adequate oxygen. Your blood pressure is taken before and after the procedure and you will need to be escorted home, as driving following the administration of IV sedation is prohibited.
IV sedation is extremely safe when carried out under the supervision of a specialty-trained dentist. Many patients make jokes asking: “can you put me out, Doc?” It should be noted that a license to perform sedation procedures carries with it a huge responsibility and a great deal of additional training and continuing education to maintain that privilege.
Contraindications to IV Sedation:
- known allergy to benzodiazepines
- alcohol intoxication
- CNS depression
- some instances of glaucoma.
- impaired lung or kidney or liver function
- advanced age
- sleep apnea: many people who have sleep apnea haven’t been officially diagnosed – if you are overweight and you snore, tell your dentist
- heart disease is generally not a contraindication
- having been prescribed benzodiazepines for many years, your tolerance may be high; let your dentist know how long you’ve been taking them
General Anesthesia in Dentistry
General anesthesia is a controlled state of complete unconsciousness. It is necessary for the elimination of awareness, movement during dental procedures. Local anesthesia is not necessary with patients undergoing general anesthesia for dental procedures.
The most common use of general anesthesia in dentistry is for children needing extensive dental treatment, uncooperative or fearful children, children who are too young to provide a safe level of cooperation or children with special needs (such as autism).