All About Dental Local Anesthesia

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This article contains everything you should know about dental local anesthesia and sedation.

Going to the dentist whether it is for a routine checkup, a simple dental procedure, or a complex orthodontic treatment like getting braces can be daunting for many people. Things like needles, syringes, drills, and even spoon excavators, curettes, and scalers can all easily strike fear in anyone who is about to sit on the dental chair. Some even experience panic attacks from dental anxiety. However, delaying dental treatments can only make problems worse. The biggest factors for this dilemma are the fear of pain and not knowing what to expect. This is why understanding the benefits and effects of dental local anesthesia is very important – to help you rationalize the situation and conquer your fear.

If you are scheduled for a dental procedure and you have questions about dental local anesthesia, then you have come to the right place, this entry will tell you everything you need to know about dental anesthesia.

Anesthetics and its role in dentistry

The word anesthetic comes from the Greek word anaisthēsia, from the combination of the words “an” meaning “without” and “aesthesis” which means sensation.

Anesthetics have been around since the mid-1800s. The medical world has come a long way since then, and anesthesia played a huge role in developing new techniques and methods of treatment for various medical conditions, including dental procedures.

Over the past one hundred years, local anesthesia has played the biggest role in the practice of clinical dentistry. Dental procedures and treatments that were once considered painful have now been made routine with the help of local anesthetics.

Despite that, many people are still apprehensive about being unconscious for the entirety of a procedure. If this sounds familiar to you, you should know that you can actually remain conscious during a dental procedure without feeling pain and anxiety. This is because there are lots of different types of sedation used for dental procedures.

Understanding anesthesia: Different types of anesthesia and why people respond differently

Medical procedures are important to maintain good health, this includes oral health. Anesthesia is probably the most inherent element in almost all medical procedures, from knee replacement surgeries to tooth extraction and filling cavities. When used properly, anesthetics aren’t usually a point of concern. But that doesn’t mean everyone can have the same experience with anesthesia.

Types of dental anesthesia

There are generally three types of anesthesia used in dentistry: local anesthesia, sedation, and general anesthesia. Each has its specific purpose and can be used with other medications.

The type of anesthetics used depends on the type of dental procedure that will be performed, length of the procedure, health condition and age of the person, and any negative reaction of the person to anesthetics in the past (allergic reactions).

Moreover, depending on what is used, anesthetics work in different ways. It can be short-acting (when applied directly to a specific area) or can work longer (usually used for surgeries).

Subsequently, the success of dental anesthesia is based on the drug, the specific area to be anesthetized, the dental procedure, and other individual factors about the patient.

Dental local anesthesia

Used for simpler dental procedures, local anesthesia provides temporary loss of sensation in a specific part of the body without depressing the level of consciousness. It can be topically applied or used with an injection.

Dentists use two types of numbing injections; block injections and infiltration injections. Block injections can cover the whole region in the mouth, such as one side of the top jaw, while an infiltration injection numbs a small area where it is applied.

Basically, the local anesthetic agent simply desensitizes a specific portion of the body (or the mouth) by injecting the medicine straight into the gum or inner cheeks. Thus, the patient can stay awake and can communicate during the whole dental process.

Most dental local anesthesia takes effect in as fast as 10 minutes and can last for as much as 30 to 60 minutes. In some cases, a dental professional may use a vasopressor (medication for raising low blood pressure) like epinephrine with the anesthetic to improve its efficacy and keep the anesthetic effect from spreading into other areas of the body.

Local anesthetics come in different forms, such as creams, gels, ointments, patches, sprays, liquid, and injectables. They are available over the counter or through a prescription.

Most dental local anesthesia is applied topically to numb a specific area or injected into the area to be treated. In some cases, a dentist may use light sedation to add to the anesthetic effect and help relax the patient better.

The upper jaw (maxillary) section is way easier to anesthetize than the lower jaw (mandibular) section.

Examples of dental local anesthetic:

  • Articaine
  • Bupivacaine
  • Lidocaine
  • Mepivacaine
  • Prilocaine

Applying the dental anesthesia

Before administering the dental anesthesia, your dentist will have to prepare your mouth by drying a certain part with air or rubbing it with cotton. To alleviate the pain from the needle of the syringe, your dentist can also apply a numbing gel to numb the skin. This is quite helpful for those who are afraid of injections.

You will rarely ever notice the needle once the numbing gel takes effect. The only sensation you will feel is the sting of the anesthesia moving inside and to your tissues.

Depending on the type and dosage of the anesthesia, the numbing effect can last for a couple of hours or more. This means you will likely experience difficulty speaking or eating even after the dental procedure.

Make sure you avoid eating on the numbed side of your mouth until you regain the sensation since it is possible to bite and hurt yourself and not realize it.


Sedation is used to relax a person, particularly those who may have anxiety, to keep still for the procedure. It can be categorized into different levels, namely mild, moderate, and deep.

Sedation may be administered orally (oral sedation), inhaled, intramuscularly (IM), or intravenously (IV).

For the inhaled version, a mixture of oxygen and nitrous oxide is administered through a mask (also known as a laughing gas). This anesthetic is not intended to put the patient to sleep; rather it makes the patient feel light-headed and comfortable, along with some numbing effects. This is often used on children and patients with dental anxiety.

Moderate sedation is administered intravenously (IV sedation), and this type of anesthetic can alter the patient’s state of consciousness to make them feel comfortable and relaxed. While the patient may still be conscious and may be able to answer questions or respond to commands, he/she may not remember anything from during their time under sedation.

Also called monitored anesthesia care (MAC), a patient under deep sedation will not be away from his/her surroundings. Moreover, the patient can only respond to repeated or painful stimulations.

There are risks involved in moderate and deep IV sedation, which is why the breathing and heart rate of the patient must be constantly monitored.

Medications used for sedation include:

  • Nitrous oxide
  • Diazepam (Valium)
  • Midazolam (Versed)
  • Propofol (Diprivan)

General anesthesia

As the strongest form of anesthesia, general anesthesia is only used for major surgical procedures that could take a longer time, such as extraction of impacted wisdom teeth. The patient will be completely unconscious and its anesthetic effects can take a longer time to wear off. This is to keep the muscles relaxed so the patient can feel no pain.

General anesthesia is administered through a mask or intravenously. There are also levels of anesthesia depending on the procedure and the patient. Moreover, there are also risks involved in this type of anesthesia.

Medications used for general anesthesia include:

  • Desflurane
  • Diazepam
  • Etomidate
  • Isoflurane
  • Ketamine
  • Methohexital
  • Midazolam
  • Nitrous oxide
  • Propofol
  • Sevoflurane

Dental anesthesia side effects

Most people do not experience adverse side effects with dental anesthesia. However, allergic reactions occasionally happen. Moreover, reactions to anesthesia vary from one person to another.

One of the most common side-effects of dental anesthesia is that the numbness can go far beyond the affected part of the mouth. In many cases, after local injection of anesthetics to the gums, the medicine can cause the cheek muscles and even the eyelid to droop. This, of course, dissipates after the effect of the anesthesia wears off.

Other common side effects of dental local anesthesia include:

  • Hematoma – blood filled swelling on the area where the needle was injected
  • Unable to blink – numbness can reach the eyelid, causing it to droop and unable to blink
  • Racing heart beat – this is due to the vasoconstrictor drug in the anesthesia which increases the heart rate for a couple of minutes. If you experience this, make sure to mention it to your dentist.
  • Nerve damage – if the needle hits a nerve, it can cause pain and numbness that could last for weeks, if not months. This however, is quite rare.

Side effects of sedation and general anesthesia

Since both sedation and general anesthesia are stronger than dental local anesthesia, their side effects can be more pronounced. General anesthesia, for example, has more risks involved.

Here are some common side effects related to sedation and general anesthesia:

  • Headaches
  • Dizziness
  • Nausea
  • Vomiting
  • Dry mouth or sore throat
  • Slurred speech
  • Shivering or sweating
  • Confusion, delirium, or hallucinations
  • Tiredness
  • Numbness
  • Lockjaw
  • Anesthetics combined with vasoconstrictor drug such as epinephrine is also known to cause heart and blood pressure issues.

Precautions on dental anesthetics

There are some conditions and situations that your dentist needs to consider to determine the right type and dosage level of anesthesia that is suitable for you.

Additionally, treatment consent is a very important part of the treatment discussion. Thus, make sure you discuss with your dentist any concerns and learn about the risk and safety precautions that will be taken to ensure positive results.


Your dentist or dental surgeon will discuss the risks versus rewards of the anesthetics for you and your baby. Some anesthetics are highly discouraged due to their associated risk of the fetus developing certain conditions. Moreover, depending on which trimester, heart rate is also monitored to avoid postural hypotension.

Older adults

Older adults with certain health problems may need adjustment in their anesthesia dosage, along with careful monitoring during and after the surgery to ensure safety.

Some anesthesia is known to cause confusion and delirium, or even memory problems after surgery on older adults.

Special needs children

Children with special needs require a thorough evaluation of the type and dosage of dental anesthetics to avoid adverse reactions or overdose. Also, numbing agents for teething should not be used for children below two years old.

Children and adults with special may have other medical complications that increase the risk of dental anesthetics. Children who suffer from cerebral palsy, for example, have the highest risk of airway-related adverse reactions to general anesthesia.

Those with heart, kidney, liver, and lung problems

People with existing issues in their heart, kidney, liver, and lungs might need dosage adjustment in their anesthesia, as the drug may take longer to leave their body and may have a stronger effect.

Those with neurologic conditions

Neurological conditions such as Alzheimer’s disease, Parkinson’s disease, history of stroke, mental illness, and thyroid problems are at high risk with general anesthesia.

Other health conditions

People with allergies, acid reflux, hiatal hernia, open sores in the mouth, infections, or severe nausea and vomiting due to anesthetics should discuss their conditions with their dentist.

The risk of experiencing side effects is also higher among people with:

  • children with attention or behavior disorders
  • chronic obstructive pulmonary disease (COPD)
  • gastric bypass surgery
  • heart problems
  • high blood pressure
  • obesity
  • seizure disorder
  • sleep apnea
  • substance misuse or substance use disorder

There is also a higher risk for people with a history of bleeding disorders or those who take medications that increases the risk of bleeding, such as aspirin. If you are taking anxiety medications like benzodiazepines, opioid-type medications, or gabapentin, then make sure to let your dentist or dental surgeon know so he/she can adjust the dosage of the anesthesia accordingly.

Risks of dental anesthesia to some people:

  • Allergic reactions (mild to severe itching, rash, swelling of the lips, tongue, mouth, and/or throat, difficulty breathing).
  • Malignant hyperthermia – dangerous rise of body temperature, with increased heart rate, breathing problems, and/or muscle rigidity
  • Low blood pressure
  • Seizures
  • Heart attack or heart failure
  • Stroke
  • Coma

The Takeaway

Anesthetics and dental procedures almost always go hand in hand. Most of the side effects and risks involved in dental anesthetics are rare and mild and few and far in between. However, make sure you share your medical history with your dentist, along with other medications you are currently taking and possible allergic reactions.

There is nothing to fear about dental local anesthesia, it is there to help you in your dental treatment.

Dr Febin Mary George - Editor

With more than 10 years as a dental surgeon, Dr Febin Mary George is passionate about educating consumers around the world to help look after their teeth.

She completed her Bachelor of Surgery at the Century Institute of Dental Science and Research Centre in 2010.

Alongside editing the International Journal of Dental Clinics she has also written for major publications including Thrive Global.