Dentist Questions Wisdom Tooth Extraction

Wisdom teeth removal

Why are some wisdom teeth removed by your dentist and some are removed my an oral surgeon?

69 Answers

It depends on the difficulty and degree of impaction of the wisdom teeth. Badly impacted teeth require the expertise of an oral surgeon to extract them.
Oral surgeons usually extract impacted wisdom teeth (not erupted in the mouth, covered by bone) or if patient wants to be sedated. Some general dentists will choose to extract, if they think it will not be difficult to extract.

Michelle B. Deutch, D.D.S.

some general dentists feel comfortable approaching wisdom teeth that are deemed "uncomplicated" by them... oral surgeons, however, are specialists of the facial skeleton and remove wisdom teeth on nearly a daily basis...
Hello,

Some general dentists do not do extractions at all. Some of them will do simple extractions. Wisdom teeth are often a complicated extraction. Therefore, those extractions are best done at the oral surgeon's office where they are equipped to deal with complications that may arise. Thank you for your question.
The removal of wisdom teeth can be done by any skilled dentist. When the wisdom teeth are impacted and it is too close to vital areas such as the nerve or if the roots are severely twisted or curved, then a referral to an oral surgeon may be needed because they are more likely to deal with these more complex types of extractions. But overall, when wisdom teeth are pretty straightforward, any general dentist who is experienced in oral surgery can remove them.
If the wisdom tooth is impacted & complicated, you will usually be referred to an oral surgeon. Some general dentists are comfortable with doing the procedure. It is up to the dentist to choose the treatment and what's best for the patient.
Each doctor must determine their level of comfort and competence when choosing to extract teeth, in particular wisdom teeth. Some general dentists are very comfortable with difficult extractions, others are not. Oral Surgeons are trained to handle all types of extractions, and are trained to handle the potential complications that may occur. Not that general dentists can't do it, they have to decide on their individual competency.
Some teeth may be much more difficult to remove and thus referred to an Oral Surgeon rather then your dentist struggling to get them out.
Depends on ability of your dentist or the complexity...
The more complicated procedures can require the skills of an oral surgery specialist. However, other less complicated ones can be done by your general dentist. It all depends on the procedure and the skills of your dentist.
Some wisdom teeth can be impacted making the procedure more complicated and traumatic for a patient under local anesthetic. Oral surgeons are better equipped to handle serious medical surgeries and procedures.
Mostly it's due to patients requesting or requiring IV sedation which most GPs don't provide. It can also have to do with experience on that particular procedure.
Some wisdom teeth may be harder to remove depending on their anatomy and tooth position in the jaw. Oral surgeons are usually referred the more difficult cases. It is up to your dentist to define what he is capable and comfortable with in treating a wisdom tooth case and when to refer out to an oral surgeon.
An oral and maxillofacial surgeon treats dental and medical problems involving the oral cavity and the maxillofacial area. Oral and maxillofacial surgery is considered a dental specialty, but the type of work required is usually much more complex than what a general dentist does. However, some dentist have the required needed training for wisdom teeth surgical extractions and other surgical procedures like implants, thru an additional year of post graduate residency programs such as Advanced Education in General Dentistry (AEGD) or General Practice Residency (GPR).
Some wisdom teeth are completely out and some are still under gum or bone! And it depends on how comfortable your dentist is with extracting wisdom teeth! I personally prefer to refer all the lower wisdom teeth and some upper ones to my Periodontist who is expert on these procedures!
The decision on who removes the necessary tooth is made by the general dentist most often. His or her decision is based on his or her level of comfort and training. Additionally some general dentists are not certified in sedation dentistry (putting you to sleep), so if the patient requests that he has to refer to an oral surgeon.
It really depends on the skill and the experience of who is doing the surgery. More complicated surgeries are done by oral surgeons because their training is more extensive in this area.
There are several factors that determine whether wisdom teeth are removed by a general dentist or an oral surgeon.
1. The amount of experience the general dentist has with wisdom tooth removal
2. The position of the wisdom teeth
3. If the patient wants to be sedated, then usually, the oral surgeon will be recommended as most general dentists are not licensed for general sedation
4. Difficulty of the procedure
5. Patient medical history - the more complicated, the more likely to refer to the surgeon

Keep in mind, the oral surgeon is considered the expert in this procedure and any general dentist is held to those same standards should he/she choose to perform the procedure.


I hope this helps.

Dr. Jennifer Rankin
Different dentists have different levels of experience and training in oral surgery. Each wisdom tooth has its own shape and position in the individual person’s jaw and a critical evaluation by the general dentist will uncover whether the patient would be best served by either the general dentist or the oral surgeon. There may also be health considerations, medical conditions and medications that would need a specialist’s attention. Other factors are the travel distance to the specialist and whether or not the patient requires sedation.
It depends on the relative complexity of the clinical situation. Straight forward tissue impactions can be handled by a general dentist. Complex and deep bone impactions requiring general anesthesia should be done by a board certified oral surgeon.
General dentists have training to remove teeth, but because of the location and difficulty of some extractions, a general dentist may refer the treatment to an oral surgeon. Oral surgeons have advanced training for the more difficult extractions. When teeth are impacted, sideways or anatomically difficult to reach without complications, they are frequently best handled by an expert. If the general dentist feels he/she can deliver the treatment at the level of the specialist, he/she may choose to preform the extractions in office.



Hope this helps!
Jossi Stokes, DDS
Wisdom teeth can generally be removed in our office. There are differing difficulties involved with wisdom teeth. Some can be impacted by tissue and others by bone. Basically, some are more difficult than others to remove. There is also the option of sedation. We provide oral sedation in our office but to be put to sleep (general anesthesia) and oral surgeon is generally used. I hope this helps!
A dentist can foresee complications regarding the extraction procedure and wouldn't like to happen that to a patient. A dentist would like the procedure to go smooth. So, sometimes they refer patient to oral surgeon depending on complications associated with surgery.
In general, It is usually based upon the difficulty of extraction of the the wisdom teeth. If the wisdom teeth are fully erupted then it is usually extracted by the dentist. However, case difficulty that might require removal of soft tissue as well proximity of the underlying nerves are most likely referred to Oral Surgeons.
Some wisdom tooth removals are better performed by a surgical specialist, at the discretion of the general dentist. Examples could include fully impacted wisdom teeth near or on the main jaw nerve, those patients on blood thinners, and those with certain medical risks. Patient safety with minimal trauma would all be considerations influencing possible specialty referral for wisdom tooth removal.
Hi Thank you for your patience!
To be to the point - some wisdom teeth are easy & and some are quite difficult to remove:
Most wisdom teeth, when correctly erupted, if they need to be removed, due to caries or gum disease, it is like any other tooth extraction. The problems is when the wisdom tooth has erupted in an awkward position usually at an angle to the 'normal' 2nd molar. Then the dentist often have to make a small insision in the gum & remove some bone with a dental drill - usually a grove besides the wisdom tooth, or splitting the tooth in easy removable parts. Sutures are place after the removal in the mouth.
Sometimes it is best to refer to a oral maxillo-facial surgeon, who is a specialist dentist with extra training & experience, for the most difficult cases. Best to discuss this with your dentist. Each dentist scope is different - some have additional training & experience. Referral to a specialist is also more expensive. There are, like any medical / surgical procedure, complications that can arise: some are minor & probably temporary, others more serious & potencially permanent. Therefore you have to give consent after your dentist discussed the pros & cons with you, even when you just get a simple extraction. The more difficult your extraction, the more likely the complication & time for healing. Hope this gives you a satisfactory answer.
Wisdom teeth removal are within the scope of practice of Dentist. However, some wisdom teeth can be very difficult to remove and many Dentist do not like to do difficult extractions. For this reason, many dentist refer the more difficult extraction, or difficult wisdom teeth extraction to a dentist that have more experience in this area. Oral Surgeon is a health practitioner that trained as a Dentist and Maxillofacial surgery.
Any general dentist can remove wisdom teeth if he or she feels comfortable enough doing so. In my office, we don't offer sedation...so if a patient wants to be put to sleep to get their wisdom teeth extracted or if the case is too difficult, we refer to an oral surgeon.
Good morning and thank you so much for your question. That depends on the degree of expertise in the field of wisdom teeth surgery of the general dentist that do the initial consultation. Some General Dentists send to the Oral Surgeon all wisdom teeth, some GD just do the wisdom teeth when these are fully erupted, and some GD are able to pull out all wisdom teeth that they receive in their offices.
The answer is that this depends of the General Dentist's criterion when they do the initial assessment of the patient.

Some wisdom teeth which are impacted, infected or complicated require the expertise of an oral surgeon. Some dentist are not comfortable with any extractions and thus refer out.
Great question! All dentists learned in Dental School how to remove teeth with various leves of expertise. Many dentist are very good at removal of teeth but refer their patient to an Oral Surgeon for the more difficult teeth as well as impacted 3rd molars ( wisdom teeth). Oral surgeons have between 4-6 years in additional surgical training to remove teeth and treat the various complication that can occur fom wisdom teeth removal, and are trained in general anesthesia to make the surgical experience more pleasant. Talk with your dentist and ask if a referral to an oral surgeon is appropiate.
Depending on the training a general dentist has had, it will determine what type of extraction they will do. Some programs do not have much training in extractions and then the dentist will only do very simple extraction. The oral surgeon on the other hand has had training in all types of extraction. Some general dentist may have had enough training to remove simple to moderately difficult wisdom teeth. The oral surgeon will remove wisdom teeth with all levels of difficulty
It depends on a few things.  Some general dentists don't have extensive experience in removing impacted wisdom teeth, and thus are not comfortable with the procedure.  Then there are those with good experience that encounter a particularly difficult case that would be better handled by an oral surgeon.  But the usual reason is that the patient needs or wants to be sedated, and many general dental practices are not equipped or trained to provide general anesthesia, while surgical offices are fully equipped and trained for that.

Michael A. Conrad, DDS
Ultimately, that is dependent on what the wisdom tooth looks like on the x-ray and if there is an infection present. Oral surgeons are better equipped for managing deeply impacted wisdom teeth that have not erupted yet. Frequently, general dentists remove wisdom teeth that are partially erupted where a patient does not have to be put to sleep. If you are concerned about your wisdom teeth, schedule a consultation with your general dentist. Hope this helps!
-Dr. Levitz
Thank you for your good question. A general dentist who is experienced and properly trained can remove wisdom teeth. However, if the wisdom teeth are fully impacted meaning the teeth are deep inside the bone, usually those are best removed by an oral surgeon. Also, complicated cases or patients with compromised medical conditions are best removed by an oral surgeon who has more medical background. This does not mean a qualified general dentist who has equal training, experience, and knowledge cannot handle these diificult cases too. Hope this helps. Good luck!
General dentists will remove erupted teeth, already through the bone. If they are buried below or in close proximity to the nerve or sinus an oral surgeon is required.
Whether a wisdom tooth is removed by a general dentist versus an oral surgeon depends on a number of factors.

Is the patient medically compromised-on blood thinners or very sick and needs to be treated in a hospital setting where it is safer for the patient.

The complexity of the extractions-are the teeth up or near the sinuses for top teeth or for lower teeth in the nerve canal or impacted where major surgery or bone removal is required to remove them.

The last factor has to do with the skill and/or comfort level of the general dentist doing the wisdom tooth extraction.
Oral surgeons are specialized dentists that have 4-6 years of head and neck surgery residency training making them the most competent to handle difficult impacted wisdom teeth. Dentists are trained to extract teeth but may not have that experience to handle complicated wisdom teeth that may be near vital structures in the head and neck.

There's nothing wrong with the general dentists pulling wisdom teeth if they feel competent to do so. Talk to your dentist and see if they are willing to. Most of the time they will refer to a specialist if the tooth is under the gum and bone due to the surgical complexity.

Hope this helps.

Jeff Litman DMD
The simplest answer to this question involves the particular teeth being removed. Wisdom teeth are located all the way in the back of a rather small, constricted area. There are usually a number of teeth in front of them, making it more difficult to even see them. Access is not the easiest. The roots of top wisdom teeth might be in the sinus; there is a possibility of these teeth going up into the sinus or ripping off the bottom of the sinus during extraction. Roots of bottom wisdom teeth may be in the nerve canal; there is a possibility of damaging the nerve and leaving the patient with temporary or permanent numbness called paresthesia. Another factor influencing who will take out these teeth is how badly broken down they are. If the tooth has a huge cavity in it or it's split and not too much tooth is there to grab it's very difficult to get out easily. An oral surgeon is trained for many years to deal with such problems. General dentists don't have the same amount of experience as oral surgeons and, therefore, are not necessarily comfortable extracting wisdom teeth. I, personally, am a general dentist and may extract wisdom teeth if they do not go into the sinuses or next to or into a nerve canal, if they are not too badly decayed and appear easy to get at. Otherwise, I'm happy to refer my patients to an oral surgeon!
Wisdom teeth have different reasons to be extracted Such as for
Orthodintic, pain , impactions, infections Extractions of wisdom teeth
could be simple or surgical and most of impacted ones have diffrent
complications that some require referrals to an oral surgeon depends on
different factors such as type of impactions , possible nerve involvement,
patients health issues and level of patients apprehension that some need to
be sedated orally or locally or under Iv or general sedation and mostly the
level of the general dentist's experience in those type of cases . So the
general dentist would be able to evaluate and diagnosis each case
individually depends on the issueds mentioned above and then decides if ur
dentist would be able to do it or an oral surgeon to perform those
procedures . Good panoramic X-ray with good visual oral exam are the key to
evaluate who will perform such cases like that .
Hello
Well if the wisdom teeth are impacted or are sideways then they are removed by the oral surgeon. But if they are out and easy to remove then they are removed by your dentist.
It depends on if they are impacted or not and if so the level of impaction. Oral Surgeons extract teeth regardless of whether or not they are impacted. That is there job! Many general dentists will extracted fully erupted 3rd molars, a.k.a wisdom teeth as well as any other tooth. Some general dentists will extract soft tissue impactions in which the tooth is erupted out of the bone, but is partially or fully covered by the gum tissue. Very few general dentists will attempt to extract boney impactions in which the tooth is partially or fully covered by bone.  The oral Surgeon is better equipped for such a task. And the liability is much higher for general dentists who extracts impacted third molars. Another reason, since this is considered a surgical procedure, most patients choose to have general anesthesia.  Most general dentists do not offer general anesthesia services. 
Francis C. Mecadon
A general dentist can remove any tooth that he/she is comfortable with. Some GP dentists refer all wisdom teeth while others refer very few. Wisdom teeth that are unerupted are considered impacted and are usually more difficult to extract. They are the teeth that are most often referred to an oral surgeon.
If a wisdom tooth can be extracted atraumatically
by a general dentist , it usually is
because the wisdom tooth is not impacted,
loose or will not require the general dentist
to remove bone in order to remove it. It really
depends on the judgement of dentist to do
what is in the best interest of dtesss xxxce

Thanks
There are several factors that the dentist must take into consideration in determining whether to remove the wisdom tooth or to refer it to an oral surgeon. First and foremost is the determination that the tooth indeed needs to be removed and for what reason. Not all wisdom teeth require extraction, though a very high percentage do. In making this diagnosis it is important to determine presence of infection, likeliness of complications, medications taken by the patient, medical history of the patient, ability of the dentist as well as training of the dentist. I think that there are many other less obvious factors to take into consideration, but perhaps the most important thing is try to insure that patient has as atraumatic of an experience as possible. "Because I can", is not a good reason to remove a tooth if it is not in the best interest of the patient. If your general dentist knows and feels that he is well qualified, and you trust that he is, then by all means the two of you should discuss whom you wish to extract the tooth. It should never be a matter of ego. If having an oral surgeon remove your tooth would make you feel better then always do what you feel is in your best interest. As a general dentist, I want my patients to be stress free and confident in their decision making.
Some general dentists feel less competent to perform procedures like 3rd molar ("wisdom tooth") extraction if they don't perform that procedure frequently, and knowing there are certain complications which might occur with wisdom tooth extraction but are less likely with other tooth extractions. Oral Surgeons perform extractions very routinely, and hence are more comfortable with them than a general dentist who performs other procedures like fillings and crowns routinely. Also, Oral Surgeons are often certified to administer IV or General Anesthesia, which few general dentists are certified to provide, and which is often appropriate for wisdom tooth extraction.
Fully erupted wisdom teeth can be more easily extracted and can be done by a general dentist. All general dentists are trained to extract wisdom teeth. In some cases, the teeth may be impacted in the bone or may lie close to a nerve or the sinus. These cases are usually referred to an oral surgeon, because they are more involved. Also, some patients may want sedation and that is often provided in an oral Surgery practice.
Some wisdom teeth can be removed by your dentist and some that are more complicated extractions need to be removed by an oral surgeon! Impacted teeth, or partially erupted teeth are surgically removed. Now, if you can see or feel your wisdom teeth, the chances are that your dentist can extract it.
I am a general dentist and remove wisdom teeth because of the training and experience that I have received. After dental school, I completed 2 years of training which included an oral facial surgery internship. This gave me the ability to perform this procedure effectively and efficiently. In practice, I have completed thousands of cases of wisdom teeth which continue to refine my abilities. Patients receive very sound care.
There are three basic reasons that some wisdom teeth are removed by general dentists and some are referred for removal to an oral surgeon for removal.

1. The anticipated difficulty of the removal. Some wisdom teeth may be relatively easy to remove with basic instrumentation such as fully erupted teeth with uncomplicated root structures. These can often be removed by a general dentist. Other cases may be more complex requiring more sophisticated instrumentation and an increased level of expertise such as impacted teeth. These are more likely to be referred to an oral surgeon.
2. The level of expertise in oral surgery of the general dentist. Some general dentists have more of an interest in basic oral surgery and have taken the necessary training and have acquired the experience to do more complex cases in their offices. Other general dentists have little or no interest in doing oral surgery in their offices and refer all 3rd molar removal cases out to an oral surgeon.
3. If a patient requires or chooses to have their removals done under general anesthesia due to the difficulty of the case, anxiety about the procedure, or because of a desire to have all 4 wisdom teeth removed in the same visit. Most general dentists are not trained or licensed in general anesthesia, so those cases will typically be referred to an oral surgeon.
yes

Regards,
Aristo J. Shyn, DMD
Hi there,

Thank you for the great question.

Wisdom teeth extractions that are unpredictable has to be done in a special setting with an oral surgeon. The way to tell if the wisdom teeth extraction will be more complicated is to check the surrounding anatomical structures in the mouth and on X-rays. In case the upper wisdom teeth are impacted - covered with bone, and/or are close to the upper sinus, they need to be removed by an oral surgeon. In case the lower wisdom teeth are impacted or close to the lower canal where the nerve runs they need to be removed by an oral surgeon.
Keep in mind that some general dentists have special training in surgical extractions without being board certified and this will be enough to handle a complicated wisdom teeth extraction.

The safest thing will be to ask your general dentist about wisdom teeth extraction experience.

I hope this helps.

1. Some patients want to be put to sleep for this type or any extraction. Most General Dentists are not qualified or don't have the equipment to put you to sleep.
2. If you are OK with just a local anesthetic, it depends on the General Dentist's comfort in his ability to do the extraction. If he does not feel comfortable, he will refer his/her patient to an oral surgeon for the extraction.
That is a good question with a simple answer. Oral surgeons are dentists. They are general dentists who have gone on after dental school for additional training, usually 3-4 years, to specialize in oral surgery. All general dentists (what you are referring to as “dentists”) are trained and qualified to remove wisdom teeth. Some general dentists chose to not perform these procedures and they refer these patients to an oral surgeon. The general dentist will make that decision based on their personal training, experiences, comfort levels, position of wisdom teeth, and what is in the patients’ best interest. Many wisdom teeth cases, but not all, require the patient to be sedated (asleep) and the vast majority of general dentists do not perform sedation in their offices. These cases are best handled by an oral surgeon.

I hope I have answered your question. If you have any additional questions, feel free to reach out to me.

Best regards,
David M. Kaffey, DDS
Location, location, location. It depends upon the anatomy of the roots and the location of the wisdom tooth. Some are beyond the expertise of a general dentist.
It depends on the difficulty of the extraction. Many wisdom teeth are in a proper position but there is no room for them. A general dentist can usually remove these type. Most wisdom teeth never come in and can be still under the bone. These are called impacted wisdom teeth and are best removed by an oral surgeon under general anesthesia.
Wisdom tooth removal is generally judged on a case-by-case basis. Sometimes, a tooth is impacted or some other clinical situation presents that your dentist feels would be better handled by someone with extensive training above and beyond what general dentists receive. It might also be a matter of sedation. In many states, general dentists cannot legally perform IV sedation without proof of extra training at an approved program, while oral surgeons receive their IV training as part of their advanced degree protocol.
Great question. The answer is that it really just depends on the confidence, skill and expertise of that particular dentist. Technically, a licensed dentist can extract any tooth in the mouth, wisdom teeth included. Unfortunately, many did not get a lot of training or experience extracting teeth of any kind while in dental school. This is why some dentists refuse to extract any tooth in their practice and refer everything out to the oral surgeon. Those dentists who do extractions in their office are left to gain extraction experience through dental residencies, continuing education courses and through their own patient experiences. I, for instance, have no issues extracting teeth in the mouth, performing surgical extractions or handling wisdom teeth. I do tend to draw my line for wisdom teeth that are very impacted below the level of bone present and when they are near a vital nerve that gives feeling to your lip, teeth and other structures on that side of your mouth. These are the cases I tend to refer to the oral surgeon. Oral Surgeons have spent an additional 3-6 years after dental school with one of their main focuses being on extracting teeth. Most notably wisdom teeth or 3rd molars and handling these cases where that vital nerve may play a role. Because they have significantly more experience with these more challenging cases, I feel it's in my patients best interest to see them. I hope that clarifies things a bit more for you.
It depends on various factors.......including surgical experience and preferences as well as limits of the general dentist. Wisdom teeth extractions will vary in complexity. Wisdom teeth, due to the human jawbone evolution, are very often malpositioned, impacted,due to lack of space for their eruption. Sometimes, the roots may be positioned close to or around the mandibular canal. In such a case, a 3D SCAN will be suggested and an oral surgeon will be required,as well as all cases with potential surgical or anatomical complications. ORAL SURGEONS are dental specialist in all things related to oral surgery.
It's a simple matter of what complications can be foreseen. Wisdom teeth may be small, and fully erupted with straight roots, or they can be large, fully impacted (still buried in the bone), and sideways in the jaw. They are also prone to having odd shaped roots that can easily fracture during extraction, making the procedure much more complex. Oral surgeons have as much as six extra years of training in complex surgical procedures, so if your general dentist refers you, trust that he sees something he doesn't want to, or can't, address. 

It is also true that many general dentists have procedures that they enjoy, and others that they do not. Surgery is one of those procedures that many dentists prefer to refer out as a rule, preferring to focus on other areas instead.
It depends on the expertise of the doctor. Some wisdom teeth are impacted and some are hidden in the bone. It all depends on the growth of the wisdom teeth and how comfortable your doctor is with removing them.

Thank You,
Rachel
It depends on the difficulty of the extraction, usually the upper wisdom teeth are easier to extract than lower ones. Thanks
Because some of them are easier to remove and not close to vital structures like the inferior alveolar nerve, but the ones that are located close to a vital structure or very deep may need the knowledge and expertise of a specialist.
Depends on skill and confidence of general dentist. Some general dentists are able to and like to extract teeth. Some do not want to. Some pick and choose which teeth they would extract. Also, if a patient wants to be sedated, put under anesthesia, then an oral surgeon is usually your best bet.
It all depends on the complexity of the extractions and the level of confidence the dentist has in removing them. Oral Surgery is a specialty within the dental field, but a general dentist can legally perform any procedure that a dental specialist such as a periodontist, endodontist, or even an oral surgeon can perform. The advantage an oral surgeon usually has is the ability for conscious sedation and 4-5 more years of training than a general dentist has. But there are many general dentists more than capable of handling 3rd molar extractions. Thanks for your question!
This is more to do with the experience, training and confidence of your dentist. In theory, a dentist should be able to remove any wisdom tooth. However, in some cases such as where the tooth is near to a nerve or there is a risk of perforating the sinus, your dentist may choose to refer to an oral surgeon, who can better manage complications that might arise.

Indeed, there are some general dentists whose practice is limited to oral surgery.
That depends on the complexity of the extractions and the anxiety level of the patient. Most general dentists will do simple extractions of teeth and the more advanced extractions will be seen by a specnkikialist. Also, the specialist has the equipment to sedate nervous patients and most general dentists do not.

-Dr. Finkelstein
Some impacted wisdom teeth don't require removal, but symptomatic cases usually need surgical extraction by an oral surgeon in an outpatient setting. Local or general anesthesia may be used, depending on the severity of the condition. First, an incision in the gums is made and any bone blocking the impacted tooth is removed before the tooth itself. Afterward, the incision is stitched shut and the empty tooth socket is packed with gauze. If the tooth is too large to extract in one piece, or if it's coming in at an angle, the surgeon cuts the tooth into smaller pieces with a drill.
In answer to your question on why some wisdom teeth are removed by a general dentist and some by an oral surgeon, it really depends on the case and capability/training of the dentist.