Overview of Local Anesthesia Techniques in Dentistry and Oral Surgery
Pain is an uncomfortable feeling that can occur when there’s harm or possible harm to your body. It is often experienced during dental procedures. To handle this, local anesthesia is typically used. Anesthesia is a medicine that numbs an area of your body to prevent you from feeling pain during medical procedures.
This medicine works by temporarily blocking the path of pain signals along your nerves. It does this by stopping certain substances (sodium) from entering your nerve cells. This way, the pain signals do not reach your brain, and as a result, you don’t feel the pain.
The areas in your mouth where you feel sensations, like touch and pain, are supplied by nerves that come from a larger nerve known as the trigeminal nerve. To prevent you from feeling pain during a dental procedure, the anesthesia is injected near the specific nerve that supplies sensation to the area where the procedure will take place. Therefore, understanding these nerves and their locations is crucial.
In dentistry, local anesthesia can be delivered in two ways: infiltration or block anesthesia. Infiltration anesthesia is usually used for the upper jaw (the maxilla), while block anesthesia is mostly used for the lower jaw (the mandible). Moreover, if these methods don’t completely numb the area, other anesthesia techniques can be used. These include injecting the anesthesia into the ligaments around the tooth, into the bone, right into the tooth pulp (the soft part in the middle of the tooth), or between the sections of the bone (interseptal).
This article will delve into the path the nerves take to supply sensation to your mouth and the different techniques used to numb these nerves. It will also discuss the equipment needed for giving local anesthesia in dental procedures, the commonly used anesthesia medicines and how they are used. Lastly, how to prevent and manage any problems that may occur due to local anesthesia will be discussed.
Anatomy and Physiology of Local Anesthesia Techniques in Dentistry and Oral Surgery
The infraorbital nerve is a nerve that comes from a larger nerve called the maxillary division of the trigeminal nerve, which is responsible for sending sensory information to your face. This nerve travels along a specific path at the base of your eye socket and enters the face through small hole called the infraorbital foramen. It provides sensation to your upper teeth and also gives sensation to your lower eyelid, nose, cheek, and upper lip.
Superior alveolar nerves are parts of the infraorbital nerve. The first one is the posterior superior alveolar nerve which gives sensation to the back part of your upper gums and the surrounding tissues. The second one, the middle superior alveolar nerve, provides feeling to your upper premolars – the teeth just behind your canines. In some people, these specific teeth may get their sensation from the first nerve. The third one, the anterior superior alveolar nerve, gives sensation to your canine and front teeth.
Then, there are the palatine nerves, which come from a cluster of nerves called the pterygopalatine ganglion, also stemming from the maxillary division of the trigeminal nerve. These nerves give sensation to different parts of the roof of your mouth and the inside of your nose. Some also provide sensation to your tonsils and upper front gums.
Next, we have the buccal nerve, which comes from the mandibular division of the trigeminal nerve, and gives sensation to the inner lining of cheek and gums of the back teeth in the lower jaw. The lingual nerve, another branch of the mandibular division, gives feeling to most of the front two-thirds of the tongue, the floor of the mouth and inner side of gums in lower jaw. It also carries taste sensation from the front part of the tongue and provides secretions to the two salivary glands under your tongue.
Lastly, the inferior alveolar nerve, also from the mandibular division of the trigeminal nerve, provides feeling to all the lower teeth and the skin on the lower lip and chin. It also gives nerve supply to a small muscle in the lower jaw which helps you open your mouth.
All these nerves are housed within a certain space in your lower jaw called the pterygomandibular space. This space is important in dentistry as the inferior alveolar nerve, which gives sensation to all the lower teeth, resides there.
Why do People Need Local Anesthesia Techniques in Dentistry and Oral Surgery
Local anesthesia plays a crucial role in managing pain during dental procedures. Certain dental treatments can trigger discomfort or pain due to physical touch, changes in temperature, or chemical reactions. These dental procedures can range from oral surgery, gum treatments (periodontal), root canal treatments (endodontic), fitting crowns or bridges (prosthetic), and fillings (restorative treatments). Local anesthesia is used to temporarily block sensation in a specific area of the mouth, allowing the dentist to perform these procedures without causing pain.
When a Person Should Avoid Local Anesthesia Techniques in Dentistry and Oral Surgery
People with allergies to local anesthetics, or any of their ingredients, should avoid them. Allergy is the only absolute reason why local anesthesia can’t be used. However, some anesthetics or procedures should be used carefully in certain people.
In addition, it’s important to consider any harmful side effects or potential reactions with other drugs. Side effects can happen if a person receives too much anesthetic or if they are using the anesthetic along with other medications. However, drug interactions with local anesthetics are rare. Certain medications used with local anesthetics–specifically, beta-blockers (blood pressure medicines), tricyclic anti-depressants (certain types of depression medicine), amphetamines (stimulants), and volatile anesthetics (gases or vapors to help you sleep)–may cause high blood pressure and irregular heartbeats.
There are also specific conditions you need to be cautious of when using local anesthesia:
For those with liver or kidney problems, it may be better to use a lower dose of anesthesia. This is because the liver and kidney play a significant role in clearing out the anesthetic. Lidocaine and mepivacaine are mostly broken down in the liver, and a small portion gets excreted in the urine. However, Prilocaine is processed by the kidneys, lungs, and liver.
For those with heart diseases, the use of adrenaline (commonly added to local anesthetics) is recommended to be done cautiously. If adrenaline is used, the dose is advised to be significantly less than what a normal, healthy adult would receive. Despite this, research on the effects of adrenaline in local anesthesia on patients with heart diseases is limited. Injecting it into highly vascular areas or using more than the recommended dose can cause adverse effects.
Older patients also require caution. Because liver and kidney functions may be reduced in the elderly, lower doses should be considered. Due to the higher prevalence of heart diseases in the elderly, the use of adrenaline should also be limited.
Pregnant women can generally receive lidocaine safely, with research suggesting it doesn’t increase the risk of complications for the mother or the baby. However, it’s crucial to remember that local anesthesia can reach the baby, so the benefits and risks must be weighed up carefully. As a general rule, dental treatment should be avoided in the first and last trimesters. Some doctors might also avoid using prilocaine with felypressin, as it may theoretically induce labor and cause fetal methemoglobinemia–a condition where the baby’s blood can’t carry oxygen efficiently.
Patients with bleeding disorders or taking blood thinners should get local anesthesia injected directly into the affected area rather than blocking the nerve supply to that region. This helps to avoid the risk of blood pooling in the muscles, which could affect the airways. The injection to numb a whole region of the mouth can, however, be safely used for patients on blood thinners.
Equipment used for Local Anesthesia Techniques in Dentistry and Oral Surgery
When you go to the dentist for a procedure, they protect themselves by wearing personal safety gear. They use a dental syringe with a short or long needle to inject a local anesthetic, or numbing medicine, into your mouth. Sometimes, a numbing gel or cream is applied to your gums before the injection.
Local anesthetics, the drugs that numb your mouth, come in two types: amides and esters. Amides like lidocaine, prilocaine, mepivacaine, and bupivacaine are commonly used in dentistry. Articaine is unique—it’s an amide anesthetic with an ester component. Esters are less commonly used in dentistry, but you might find benzocaine in some topical anesthetics.
Lidocaine is considered the best and is most commonly used in dentistry because it’s safe and effective. It’s usually combined with adrenaline, which helps lidocaine stay at the site of injection longer, providing a longer duration of numbness and reducing any risk of toxic reactions from the drug.
While not as commonly used as lidocaine, articaine with adrenaline is often chosen thanks to its high solubility, meaning it easily spreads and numbs the area. Because it diffuses easily in bone tissue, articaine is particularly useful for procedures in the lower back part of the jaw, where the bone is dense. Still, it’s worth noting that articaine isn’t suggested for use in a specific type of numbing technique called Intraoral Nerve Block (IANB) due to a higher risk of nerve damage.
On the other hand, prilocaine and mepivacaine don’t dilate blood vessels much, so they can be used without adrenaline. They’re both short-acting anesthetics, which makes them good choices for children, older adults, or patients who can’t take adrenaline for health reasons. As they wear off quickly, children, who might accidentally bite their numb lips or tongues, could benefit from these shorter-acting drugs. Furthermore, mepivacaine is usually chosen for patients with heart disease. Some research even suggests that it might be more effective than other anesthetics for numbing teeth with severe tooth pulp inflammation.
Bupivacaine is different—it’s a long-acting anesthetic that can last up to eight hours. It’s not used as often in dentistry, where long-lasting numbness isn’t usually necessary.
Who is needed to perform Local Anesthesia Techniques in Dentistry and Oral Surgery?
Local anesthesia is usually given by dentists or other dental staff like hygienists or therapists, with the help of a dental assistant. The dental assistant makes sure that all the tools and materials needed are ready. They or the dentist can put together the dental syringe, which is a special tool that holds the medicine to numb your mouth. The dentist then safely gives the local anesthesia and properly throws away any sharp tools used. The dental assistant cleans and gets rid of any leftover tools.
After the procedure, either the dentist or the dental assistant will tell you what you need to do to take care of the area where you got the anesthesia. They will let you know what to expect as the numbness wears off and if there are any specific steps you need to follow to keep the area clean and safe.
Preparing for Local Anesthesia Techniques in Dentistry and Oral Surgery
Before a dental procedure, it’s important for the dentist to review your medical history. This includes any health issues you may have, medications you’re taking, and if you are allergic to anything. This information can affect the type of numbing medicine (anesthetic) they use during the procedure. Also, the dentist needs to know your weight to make sure they don’t give you too much of the numbing medicine, which could be unsafe.
The dentist or dental assistant prepares the numbing injection by checking the expiration date and the type of anesthetic they plan to use. When it’s time for the injection, you will be seated comfortably in a dental chair. The chair may be tilted backwards so you’re lying down or nearly lying down.
Before giving the injection, the dentist looks at your mouth and teeth to make sure they’re injecting it in the right place. They might also apply a special numbing gel or cream to your gum before the injection. This “freezing” treatment helps to reduce discomfort when the needle goes in. As always, a well-lit room is important for the whole process to go smoothly.
How is Local Anesthesia Techniques in Dentistry and Oral Surgery performed
Infiltration anesthesia involves injecting an anesthetic into your gum tissue to block the nerve sensations around your tooth. Your dentist will make a small injection into your gum next to the tooth that’s being treated. The anesthetic then spreads across the tissue and bone underneath your gums, numbing the nerves that are causing the pain.
Usually, infiltration anesthesia is more often used in the upper jaw, as its spongy structure makes it easier for the anesthetic to penetrate. However, a new anesthetic called articaine is now being used for the same effect in the lower jaw too. This is because articaine can be very easily absorbed by body tissues. This has brought the success rates of numbing the lower jaw teeth to about 84-94%.
Studies also show that, with articaine, you can get numbing effect on the soft tissues behind your upper teeth, without having to inject the anesthesia separately there.
Another type of anesthesia is a palatal infiltration. Just like buccal infiltration, your dentist will inject the anesthetic into your palatal tissues (the roof of your mouth) to numb it. You might feel a bit more pain during this injection because the needle causes the thick tissue that covers the hard palate to separate from the bone underneath it.
Ways to lessen the pain from this injection could be using an anesthetic gel before the injection, cooling the area with an ice pack, gently applying pressure on the area with a mirror handle, or pulling back the needle slightly before injecting.
Intrapapillary infiltration is another method to avoid painful injections on the roof of your mouth. After a buccal infiltration, the anesthetic is injected into your gum tissue between the teeth, over the bone to reach the roof of your mouth. This method numbs the tissue between your teeth in the roof of your mouth. It’s a common method for primary teeth (milk teeth).
There are also different types of blocks for numbing specific areas in your mouth, like a section of teeth or a particular side of the jaw, etc. For this, the needle is either inserted inside your mouth or outside, depending on the area that needs numbing.
In mandibular blocks or lower jaw blocks, the anesthesia is injected in a way that numbs the whole side of the lower jaw, including the teeth, bone, lower lip, chin, and the inner tissues from the middle to the back. To make this injection, it’s important that you open your mouth as widely as possible. If not, the nerve in the lower jaw that needs to be numbed will relax, making it hard for the anesthesia to take effect.
In the Gow-Gates technique, the mandibular nerve is blocked right where it divides into four other nerves. This numbs all the hard and soft tissues on one side of your lower jaw, two-thirds of your tongue, the base of your mouth, inner cheek tissues, and the skin.
Possible Complications of Local Anesthesia Techniques in Dentistry and Oral Surgery
If you’re having a medical procedure that needs a local numbing agent, there are a few potential issues that you might come across. One of these is an allergic reaction to the numbing agent, which happens in a very tiny fraction of cases (between 0.1-1% of people). Allergies to certain types of local anesthetics like benzocaine are more common. If you’re allergic, you might get sores in your mouth, or in very rare cases, have a potentially life-threatening reaction called anaphylaxis.
Another issue you might face is that the anesthesia doesn’t work as expected. This can happen for several reasons like differences in your body structure, not applying the anesthetic properly, your level of anxiety, or any infection or inflammation in the area. This issue is more common in cases when anesthesia is being used on the lower jaw, and only works 80 to 85% of the time. Sometimes, other nerves can also provide sensation to the teeth, which may need to be numbed separately.
It also turns out that your jaw shape can influence whether the anesthesia works properly. A jaw that’s set back a bit (a ‘retrognathic’ jaw) can make the anesthesia less likely to work. Changes to how and where the anesthesia is applied may be needed for it to work properly.
In cases where there’s an infection, the numbing agent may not work as well because infections make the environment more acidic. Trying to inject the numbing agent as far away from the infection as possible might help. Also, the numbing agent itself is usually acidic, so tweaking its pH by adding something like baking soda might make it work faster and cause less discomfort when being injected.
The next complication is hematoma formation – a swelling filled with blood that can form around the injection site. This can cause soreness, swelling of the face, or difficulty opening your mouth wide (a condition called ‘trismus’). Usually, applying pressure can help stop the blood flow and reduce the hematoma.
In some cases, the anesthesia accidentally gets into a blood vessel, causing symptoms like palpitations, visual disturbances, headaches, and dizziness. But these symptoms should go away on their own. Before injecting, a technique called ‘aspiration’ is used to make sure the needle isn’t inside a blood vessel.
In rare situations, it’s possible for the needle to break during the injection if there’s any sudden movement. This can cause pain, swelling, difficulty opening the mouth, and trouble swallowing. The risk of breakage is higher in the lower jaw and in needles with a smaller diameter. To help prevent this, the doctor should hold your mandible firmly, you should stay still during the process and the needle should be changed if multiple injections are needed.
If a needle does break, it should be removed as soon as possible. No matter the complication, your doctor is trained to identify and manage these issues, so you are in good hands during your procedure.
What Else Should I Know About Local Anesthesia Techniques in Dentistry and Oral Surgery?
For most dental treatments, a deep numbing (profound anesthesia) is necessary. This helps to make the patient comfortable and aids the dentist in performing the treatment effectively. Since fear of the dentist often comes from painful past experiences, managing pain through numbing the area (local anesthesia) is useful in reducing and preventing dental fear.
The choice of numbing agents and the methods used to deliver them can affect how well the numbing works. For this reason, it’s important that dentists have a strong understanding of the numbing agents and methods used in dentistry, including when and when not to use them.
Although numbing is rarely linked with serious side effects, dentists need to be aware of potential complications to keep their patients safe. Dentists also need to know the best ways to manage or prevent these complications.
It’s also crucial for dentists to understand the network of nerves that supply the teeth and surrounding tissues. This ensures that the numbing solution is placed near the nerves that supply the area being treated. Also, being aware of possible differences in anatomy helps the dentist understand why numbing might not work and what methods can be used to overcome this.
If the numbing doesn’t work, it can delay treatment and cause the patient to lose trust in the dentist and in dentistry as a whole. Dentists need to understand why numbing can fail and be able to use alternative techniques when the usual methods don’t work.
