Overview of Oral Surgery, Extraction of Mandibular Third Molars
Mandibular third molars, also known as wisdom teeth, are the teeth most commonly removed in dental surgeries, making up about 18% of all tooth extractions. Wisdom teeth usually start growing when individuals are between 8 to 15 years old and complete their growth around the age of 17 to 22. Because wisdom teeth are the last to grow in, they often don’t have enough space to grow properly, leading to impaction. This occurs in 17 to 69% of cases.
The extraction of wisdom teeth can be complex because of its location near an important nerve called the inferior alveolar nerve (IAN). The IAN is a part of the fifth cranial nerve and is responsible for feeling in the lower cheek, chin, lip, tongue, gums, and teeth. The wisdom teeth can sometimes grow very close to this nerve, making the extraction process more complicated. Furthermore, the back of the mouth can be difficult to access, adding to the complexity of the procedure.
The procedure to remove wisdom teeth considers multiple factors including the structure of the mouth, the state of the tooth, whether the extraction is needed, whether it may cause more harm than good, and the specific surgery method to be used.
Anatomy and Physiology of Oral Surgery, Extraction of Mandibular Third Molars
The mandibular nerve is the third and largest part of the fifth cranial or head nerve, also called the trigeminal nerve. It provides feeling to the skin of the lower face and lip, powers the muscles used for chewing, and also senses the lower teeth, gums, and front two-thirds of our tongue.
A branch of this nerve called the inferior alveolar nerve is the largest offshoot and plays a crucial role as it provides sensation to the lower cheek, chin, lip, tongue, teeth, and gums. This nerve is very important when it comes to performing dental procedures like an extraction of the lower third molars, often known as your wisdom teeth. Since the nerve and these teeth are usually located close together, there is a risk of damaging the nerve during the extraction. If the nerve gets damaged, it might cause temporary or permanent changes in sensation in the areas it serves. The odds of temporary change in sensation vary from 1% to 5% and permanent changes occur in 0 to 0.9% of people.
Advanced imaging methods like Cone Beam Computed Tomography (CBCT) can help determine the exact relationship between your lower wisdom tooth and the nerve, assisting in quantifying the risk of unintended nerve damage.
There are certain features on a normal X-ray, like orthopantomogram (OPG/DPT) that suggest the close closeness of a wisdom tooth to this nerve (See figure 1). These features include:
1. Absence of white ‘tram lines’ indicating a loss of the lining of the inferior dental canal.
2. Dark ‘banding’ across the area of the lower wisdom tooth roots, suggesting they’ve darkened.
3. Deviation, or movement, of the dental canal away from the roots of the wisdom tooth.
4. Localized narrowing of the dental canal around the region of the lower wisdom tooth root.
5. Excess curving of the lower wisdom tooth roots, known as Dilaceration of roots.
6. Abnormal narrowing at the end of the lower wisdom tooth roots.
If one or more of these indicators are present, CBCT can be used for an in-depth understanding of the relationship between the lower wisdom tooth and the nerve.
Why do People Need Oral Surgery, Extraction of Mandibular Third Molars
Your wisdom teeth, also known as lower third molars, are the teeth most commonly removed by dentists. This is about 18% of all dental extractions. There are a couple of reasons for this. Firstly, due to their location at the back of your mouth, they can often become impacted, meaning they don’t come through properly. This can lead to inflammation and infection of the surrounding gums, a condition called pericoronitis.
A dentist might advise you to have a wisdom tooth removed if you have repeated infections (pericoronitis), if the tooth is decayed and can’t be restored, or if the decay has reached the tooth’s pulp (the inner part of the tooth containing nerves and blood vessels). Additionally, if your wisdom tooth is coming in at an awkward angle and causing decay in the tooth in front of it, having it removed can make it easier to treat the decayed tooth. Sometimes, a wisdom tooth might need to be taken out if it’s associated with cysts or tumors, if it’s in the way of other surgery (like corrective jaw surgery), or if it’s involved in a fracture (break) of the lower jaw.
However, it’s important to note that a crowded front lower teeth is not a reason to have wisdom teeth removed. There’s a common belief that erupting wisdom teeth can push other teeth out of place, leading to crowding. However, research has not been able to find a definite link between the arrival of wisdom teeth and crowding of the front teeth. Therefore, removing wisdom teeth will likely not solve the issue of crowded teeth and is not worth the potential risk of damaging a major nerve that runs through the jaw.
When a Person Should Avoid Oral Surgery, Extraction of Mandibular Third Molars
Sometimes, a dentist may worry about pulling out a person’s lower wisdom teeth because of concerns like these:
– High risk of harming the inferior alveolar nerve (IAN), an important nerve in your lower jaw.
– Complex root shapes that make extraction hard.
– Too much tooth cement (hypercementosis) or the tooth is fused to the bone (ankylosis).
– The person had previous treatments involving drugs taken through an IV cannula (bisphosphonates) or radiation therapy.
If a special X-ray called cone beam computed tomography (CBCT) shows a close relationship between your wisdom tooth roots and the IAN, or for several other reasons, the dentist may choose to do a ‘coronectomy’ instead removing the whole tooth. A coronectomy involves removing only the top part of the tooth, getting rid of all the enamel, and leaving the roots in place. The goal of this approach is to eliminate the discomfort from a partially erupted wisdom tooth that gathers food and causes inflammation called pericoronitis, while reducing the risk of damage to the IAN.
However, there are situations where a coronectomy should not be performed:
– If the tooth has decay that has reached the pulp or innermost part of the tooth.
– The person has immune system related diseases or conditions like diabetes mellitus that can slow down the healing process.
– The wisdom tooth is causing problems for other surgeries such as corrective jaw surgery (orthognathic) or surgery after an injury (trauma surgery).
– The tooth is involved with large cysts or abnormal growths (neoplasms).
Preparing for Oral Surgery, Extraction of Mandibular Third Molars
Before doctors can examine a patient’s bottom third molar, also known as a wisdom tooth, they need to understand several things. These include a patient’s pain history, medical background, and social habits. They also need to be aware of any medical issues that could affect the tooth removal process, such as blood clotting disorders, radiation therapy history, certain medication use, and a weakened immune system. This information helps to predict how well a patient may heal after surgery and reduce the chances of complications, particularly in patients who might heal slower. For instance, those who had radiation therapy to the jaw could develop a condition called osteoradionecrosis, where the jawbone starts to damage due to lack of blood.
During the examination, doctors pay close attention to the position, accessibility, and level of impaction (how “stuck” the tooth is) of the lower third molar. This helps them evaluate how complex the extraction process might be. This examination can be done both visually and using images like X-rays.
When determining the complexity of a wisdom tooth extraction, doctors take into account multiple factors ranging from the tooth’s position compared to the tooth in front of it (occlusal level), how much the tooth is angled (degree of impaction), and how deep the tooth is compared to the front tooth (depth to the application point). They also consider the level of bone loss around the tooth, visibility of the space around the tooth root (Periodontal ligament (PDL) space), how many roots the tooth has, the curve of the tooth roots, the width of the roots (root bulbosity), and the tooth’s proximity to the inferior dental canal which is a canal inside the lower jaw that contains a nerve and blood vessels.
These factors are then categorized into low, moderate, and high difficulty levels which helps the doctor prepare for potential challenges during the extraction.
The Winter’s Lines method is a well-known technique proposed by Dr. Winter in 1926 to more accurately determine the complexity of wisdom tooth extraction. It involves drawing three imaginative lines across the lower molars and extending towards the impacted wisdom tooth. This method helps to visualize the amount of bone that needs to be removed to extract the tooth. According to researcher Howe, every 1mm increase in the length of a specific red line, the complexity of the surgery increases three times.
How is Oral Surgery, Extraction of Mandibular Third Molars performed
In some dental procedures, a small section of the gum called a mucoperiosteal flap may be surgically lifted for better access. It’s important that this flap has its own blood supply to keep the tissue healthy. The size and shape of the flap depend on its purpose. For instance, when a lower wisdom tooth is removed, the flap must be large enough to offer clear visibility and avoid strain. It’s also vital to design the flap to avoid any damage to a nerve in the mouth, called the lingual nerve.
When removing the lower wisdom tooth, either a two-sided or three-sided flap is used. The design of choice is the “Ward’s incision”, where the additional cut is positioned in such a way that avoids damage to the lingual nerve. In the past, dentists used to lift and pull back a part of the mouth called the lingual flap in order to protect the lingual nerve. However, it’s been found that this actually increases the risk of damaging the nerve, so it is not used anymore.
After the gum flap is raised, it is carefully pulled back using a special tool called a retractor. This not only allows for better visibility but also protects surrounding tissues like the lips and the inside of the cheeks. Then, a space is created using a special drill on a tool called a surgical handpiece. This space allows for the removal of the wisdom tooth. Occasionally, the tooth has to be cut into pieces for easier extraction. A groove is made with the drill and then a thin instrument is used to break the tooth apart. This is done first for the top part of the tooth and then for the roots, which are removed separately.
Once the tooth is fully removed, the empty socket is cleaned and any rough edges are smoothed down to prevent damage to a nerve called the inferior alveolar nerve. The gum flap is then stitched back with sutures that naturally dissolve over time.
Possible Complications of Oral Surgery, Extraction of Mandibular Third Molars
Removing the third molar, also known as the wisdom tooth, can be a complex surgery. After the procedure, it’s common for patients to experience temporary pain, swelling, and trismus (difficulty opening the mouth). These side effects are typically short-lived and can be controlled with over-the-counter painkillers.
A complication that might occur is called alveolar osteitis, or dry socket. This happens when the blood clot that usually forms after surgery gets dislodged or dissolves before the wound has healed. Dry socket can be treated by carefully rinsing the area where the tooth was extracted with a mouth rinse or saline solution and dressing the area with a special medical material that gets absorbed by the body over time.
Patients who take medication for blood thinning or have bleeding disorders may have prolonged bleeding after surgery. This is handled by cleaning the extraction socket, applying substances that can quickly stop bleeding in the socket, and closing the bleeding area with stitches.
Although these complications can happen with any tooth extraction, removing wisdom teeth has the added risk of damaging the IAN (Inferior Alveolar Nerve) and the lingual nerve. These nerves provide feeling to your chin, lip, tongue, and teeth. Damage to them can temporarily or permanently alter sensation in these areas. Usually, this numbness disappears on its own within a few days to a few months. However, if it persists beyond six months, it might be permanent.
What Else Should I Know About Oral Surgery, Extraction of Mandibular Third Molars?
If you have to get your wisdom teeth (also known as third molars) removed, there’s a small chance you may experience numbness or a tingling sensation in your mouth after surgery. This condition is called oral paraesthesia and while not common, it can impact how you feel day-to-day. What’s more, in most cases, it isn’t completely reversible.
This is why careful planning and a thorough understanding of your head and neck structure is so important for your surgeon. By knowing exactly where your wisdom teeth are and where the nerves in your mouth run, your surgeon can greatly lower the risk of accidentally causing nerve damage during the procedure. So, getting a detailed assessment and carefully planned surgery is key to prevent this condition from happening.