Local Anesthesia and Nitrous dental sedation
Each operatory of the dental office is capable of supporting nitrous oxide (laughing gas) dental sedation.  There are many benefits and few risks of using nitrous oxide. The gas is administered through a comfortable mask placed over the nose, and the patient is instructed to inhale in through the nose and exhale through the mouth. As a precaution, patients should not eat anything for about two hours prior to use of the gas. The patient begins to feel a pleasant level of sedation anywhere from 30 seconds to three or four minutes after initial administration. After the gas has been adjusted to the appropriate dose and the patient is relaxed, the dentist can comfortably give the injection (if needed) to the patient, and then proceed with normal dental treatment. After the treatment is completed, the patient is given pure oxygen (100%) to breathe for about five minutes, and all the effects of sedation are usually reversed. Unlike IV sedation or general anesthesia, the patient can almost always leave the office by themselves, without an escort.

Nitrous oxide has few side effects. High doses can cause nausea in some patients. Patients that are claustrophobic or have blocked nasal passages cannot use nitrous oxide effectively. Nitrous oxide is one of the safest anesthetics available. Interestingly, it is also routinely used by anesthesiologists for general anesthesia in combination with other more potent gases.

Dentists find nitrous oxide especially useful for fearful patients as well as young children. The effect of nitrous oxide is often remarkable. A patient that was once anxious will become relaxed and calm. Since nitrous oxide is so effective, dentists rarely need to prescribe Valium for anxious patients before treatment. It works wonders!

Local Anesthetics/ Needles
The type of dental needle that is mainly used here is the “blue colored” needle which is a 30G needle and is relatively short in length. According to Dr. Dorfman, it causes less discomfort to the patient while delivering local anesthesia. However, before any needle injection to patient, a topical anesthetic gel is applied on the area to be injected. This helps to block the free nerve endings on the mucosa to be injected and patient feels little or no pain. It should also be emphasized at this point that the clinical skill of the practitioner in rendering a pain free dental procedure shouldn’t be undermined. I find Dr. Dorfman skilled at this as well.

Carbocaine, which contains no vasoconstrictors like epinephrine, is most often used at Dr. Dorfman’s practice. As such, the risks of medical emergencies are minimized to the barest minimum. Though rarely used. lidocaine may be supplemented at times.

Local infiltration
Most infiltrations are given in the maxillary quadrant. Sometimes, the mandibular quadrant can be used as an adjunct to a block.  If Dr. Dorfman is to perform a dental procedure on a maxillary anterior area of the mouth, he starts giving his injection from the premolar area at the mucobuccal fold and moves medially towards the midline while giving little time interval between injections. According to Dr. Dorfman, the area around the premolar is usually less of a discomfort to the patient during injection of local anesthetic. For the maxillary posterior, the anesthesia is given just towards the apex of the tooth in question in the mucobuccal fold area.
Mandibular Block
Dr. Dorfman prefers to use the “Gow-Gates Technique” for mandibular block injection.

Gow and Gates Technique
Fortunately, an Australian dentist named Dr. George A.E. Gow-Gates invented an alternative to the standard mandibular block in the mid 1970′s.  This block is appropriately named the Gow-Gates and is delivered towards the neck of the condyle just under the insertion of the lateral pterygoid muscle.  The Gow-Gates has a number of advantages over its more conventional alternative.

• Unlike the mandibular block, the path the needle traverses contains much less muscle tissue than is traversed by the needle in a conventional mandibular block. Thus there is little release of bradykinins, which are the chemicals which cause the aching that patients feel when receiving a mandibular block.  Furthermore, the tissue through which the needle passes contains no nerve receptors, and thus there is little direct pain during the injection.  It is not uncommon for patients to remark that they felt nothing during the injection.
• The area where the Gow-Gates is delivered is less vascularized than the area adjacent to the location of injection in a standard mandibular block.  Studies indicate that there is an 89-90% lower likelihood of giving an intra-vascular injection using this technique.  In addition, because of the lower vascularization in the area, the anesthesia is less rapidly absorbed into adjacent blood vessels prolonging the presence of the anesthesia in the area, which means that mepivicaine without vasoconstrictor (Carbocaine) may be used to greater and longer lasting effect using the Gow-Gates.
• Finally, the Gow-Gates anesthetizes the nerve trunk before it splits into its three main branches; the lingual branch, the buccal branch and the alveolar branch.  Hence the Gow Gates delivers three shots in one.  A single shot does the work of three separate injections.

Technique:
The tragus is a useful landmark since it lies just distal to the temporomandibular joint.  The little notch just below it is called the intertragal notch.  The intertragal notch is the landmark that is used as the “aiming point” of the needle when giving the Gow-Gates injection. The patient opens his/her mouth as wide as possible.

This technique is not possible if the patient is not able to open wide enough to allow the condyles to translate fully over the articular eminence. Place your thumb in the patient’s mouth retracting the cheek. Instructions to appropriately perform the technique are as follows:

1. Place the middle finger of the same hand over the intertragal notch. Allow the needle to enter the buccal mucosa just distal and apical to the tuberosity.
2. Now aim the tip of the needle toward the the intertragal notch. Keeping the middle finger in this position, and using it as the aiming point makes giving the Gow-Gates block easy and predictable.
3. Proceed until the needle hits bone.  The needle will enter about two-thirds to three-quarters of its length before hitting bone.  If the needle does not hit bone, then you have missed the target and should withdraw and try again, aiming slightly laterally, or medially.  Then deposit the anesthetic solution slowly.