Nitrous Oxide & Local Anesthetic...

Dr. Pietrini writes a monthly column for Fra Noi, an Italian newspaper. Articles related to the topic of Nitrous Oxide and Local Anesthetic are featured below. Click here to view this month's article

You Must Have A Hole In Your Head by Dr. Pietrini
When I was a student at the University of Illinois College of Dentistry, one of my first patients was an elderly woman who needed a large filling in one of her lower molars. I explained to her that I would have to give her an injection on the inside of her cheek near her back molars. I have heard many excuses why people prefer to not have dental injections, but this patient really caught me by surprise. She told me that she did not want a shot in her mouth because she still had holes in her cheek from previous injections given to her years before. After looking in her mouth, I told her a little "white lie". I convinced her that I would give her the injection into one of the old holes and not make a new one. She opened wide. I gave her the injection and she was none the wiser.

Throughout history, pain has been so closely related to dentistry that the words "dentistry" and "pain" have become interchangeable. Some studies have shown that more patients postpone necessary dental care because of fear than from all other reasons combined. Today more than ever, this should not be the case. Preventive care and modern technology have helped to reduce the need for pain control in the dental office. When extensive treatment like large fillings, crowns, root canals and oral surgery are necessary, the pain can be controlled by putting the patient to sleep with a general anesthetic or with injections of local anesthetic.

In 1844, a dentist named Dr. Horace Wells started using nitrous oxide (laughing gas) to relax patients and to control pain during surgery. When nitrous oxide is used in combination with other gases and drugs, a patient can be rendered unconscious. Because it takes some time for these drugs to be eliminated from the patient's system, the patient is unable to drive for several hours after treatment. Today, many dental offices use nitrous oxide with oxygen to help relax patients during treatment. A few minutes after the treatment is completed the patient is capable of resuming normal activities.

In 1905, a physician, Dr. Albert Einhorn discovered the drug procaine (Novocain). It became the most popular form of local anesthetic--used for more than fifty years. Several different types of "caines" are used today, such as lidocaine, benzocaine, mepivacaine and bupivicaine. There are four different methods of administering local anesthetics that are most commonly used in dentistry to prevent pain-topical anesthetic, nerve block, infiltration and periodontal ligament injection (PDL). Topical anesthetic is applied to numb the surface of the tissue to reduce the sensation of the needle penetrating the injected site. The main ingredient in most topical anesthetics is benzocaine, which is also found in over-the-counter toothache medications. If your dentist had to perform an extensive amount of treatment in your lower jaw, he or she would give you a block injection, which is designed to numb the main nerve that runs to all the teeth on one side of your jaw. This nerve also has branches that serve the lip, chin and side of the tongue. If only one tooth requires treatment, an infiltration may be given under the upper lip in an area near the end of the root of the tooth. Occasionally, a local may be given for a single tooth by placing the anesthetic in the space between the tooth and the gum (a PDL injection). Since the PDL does not cause numbness in the gum, lip or cheek, it a very desirable technique for children to prevent them from accidentally biting the numbed area.

Many anesthetics contain vasoconstrictors, a type of adrenalin, which helps make them more effective and allows the numbing effect to last longer. With patients who suffer from cardiovascular disease, vasoconstrictors may need to be reduced or eliminated. In these cases your dentist may have to consult with your physician.

For almost one hundred years, the only method of administering a local anesthetic was with a hypodermic syringe. For many years when patients would ask me if there was some way they could avoid getting an injection, I would tell them that I wish I had a magic wand. Four years ago a computer controlled injection system called the Wand was introduced. Since the Wand delivers an anesthetic drip numbing the tissue ahead of the needle at a constant rate of pressure and volume the result is an effective and often pain-free injection. About one year ago, Midwest Dental introduced a device the Comfort Control Syringe. At first it may seem to some patients that it takes longer to deliver the anesthetic with these systems (approximately 60 seconds). A recent survey reports that most dentists give a traditional injection in an average time of 20 seconds, which could account for some of the discomfort the patient experiences. A study in the Journal of the Academy of General Dentistry shows that approximately two-thirds of the patients tested preferred the computer controlled system over the traditional injection.

POW, Right In The Kisser by Dr. Pietrini

In the 1950’s, Jackie Gleason starred in the Honeymooners as a bus driver, Ralph Cramden. On many occasions he shouted to his wife, “One of these days Alice, pow, right in the kisser.” Dental pain, whether it is caused by injury, infection or post-operatively can range from mild discomfort to the patient feeling like they received a hard blow to the face.

Pain control can be achieved in a variety of ways. Even in cases of moderate to severe pain, strong medications are not always necessary. As an example, let us look at two possible scenarios involving a sixteen-year old male who injures one of his upper front teeth playing basketball. If the tooth was fractured in half exposing the pulp that contains tiny nerves and blood vessels, it would be very sensitive to hot and cold foods. The patient would be given an injection of local anesthetic and root canal treatment would be performed. Since the tooth would no longer respond to hot or cold, in most cases post-operative pain medication usually is not required. If the same patient had a blow resulting in a bruised and swollen lip causing the tooth to become loosened but not fractured, the treatment and post-operative care would be quite different. Initially an ice pack would be applied to the lip to help control the swelling and pain. The patient might need an analgesic for pain relief, such as aspirin or ibuprofen. If the trauma was severe enough, the pulp in the tooth could be damaged irreversibly leading to a future infected (abscessed) tooth. When a tooth becomes abscessed, it is often accompanied by extreme pain, swelling and pressure. Several steps may have to be taken to treat this condition. Applying ice over the area and taking pain medications will be helpful while waiting for treatment to be started. The patient is usually placed on an antibiotic, which will aide in controlling the infection. The pain and pressure can be managed by draining the abscess by creating an opening in the back of the tooth and/or making a small incision in the gum near the end of the root. As the antibiotic takes affect and the pressure is relieved, the amount of pain medication can usually be reduced or eliminated. Eventually, the root canal treatment can be completed.

In the first twenty-four hours after an injury occurs or after oral surgery has been performed, applying ice packs to the affected area is usually best. For the next several days applying a hot, moist compress will help increase circulation to the area and provide soothing relief. Modern technology and gentle care have helped to reduce the amount and duration of pain for patients; however, sometimes medications are still necessary. Next month I will discuss the various over-the-counter and prescription pain medications that are available.

Take Two Aspirin And Call Me In The Morning  by Dr. Pietrini

When I was in dental school in the 1960’s, we were told that if a patient called with a complaint that was not considered an extreme emergency our response should be, “Take two aspirin and call me in the morning.” At that time, aspirin was the number one choice of medicine for mild to moderate pain relief. In the early 1970’s, ibuprofen was introduced. Drugs such as Advil^TM, Motrin^TM and Nuprin^TM are types of ibuprofen. These analgesics along with aspirin are in a category of medicines known as non-steroidal, anti-inflammatory drugs (NSAIDs). The pain that is associated with arthritis and dental treatment is related to the amount of inflammation present in the joints or structures of the oral cavity. NSAID’s affect these areas by blocking inflammation, reducing swelling, pain and stiffness. 

The newest generation of anti-inflammatories is the Cox-2 inhibitors—rofecoxib (Vioxx) and celecoxib (Celebrex). The Food and Drug Administration (FDA) approved these drugs for use in patients with osteoarthritis and rheumatoid arthritis. They block the Cox-2 enzyme responsible for producing swelling, pain and stiffness; however, the Cox-1 enzyme, which protects the stomach lining from the irritation caused by digestive acids, is left untouched. Also, because these medications do not tend to thin the blood like other NSAIDs, they may be more suitable for long-term use. A prescription is necessary to obtain these medications.  

Tylenol^TM (acetaminophen) has become very popular, because it has a lower incidence of side effects, such as prolonged bleeding and gastrointestinal discomfort. While acetaminophen is effective in reducing fever and headache pain, since it is not an anti-inflammatory, it is not as effective as the NSAID’s. When acetaminophen is combined with opioids, such as codeine or related synthetic drugs, like hydrocodone (Vicodin^TM), oxycodone (Percocet^TM) or propoxyphene (Darvocet^TM), it is a better pain reliever.

Because aspirin, ibuprofen and acetaminophen are sold over-the counter, they tend to cost less and are available in brand name or generic form. Taking the proper dosages for shorter periods of time can minimize the various side effects. The opioids have several limitations. Because they affect the central nervous system, blocking the pain awareness in the brain, some of the possible symptoms are: dizziness, sedation, nausea, constipation, urinary retention and depression of respiration and/or blood pressure. Long-term use may lead to physical and psychological dependence. It is best to take opioids at bedtime and not while driving or operating machinery. 

As with all other medications, you should consult with your physician or dentist about any pain relievers that you take. Health factors, like pregnancy, ulcers, allergies, asthma and diseases of the heart, kidney or liver must be evaluated. Always take your pain medications after meals with a full glass of water to avoid stomach distress.