OS Lec#6 By Yasmin Hzzayen

by **Sura** 3/11/2011, 9:48 pm

http://www.mediafire.com/?1h8ntdpn1y1c15g

by **Shadi Jarrar** 9/11/2011, 3:36 am

بسم الله الرحمن الرحيم

Oral Surgery lecture #6

01.11.2011

Dr. Ashraf Abu Karaky

Yasmin Hzayyen

Impacted Canines

Today we'll talk about impacted canines, early management *. What we will focus on is the management of impacted canines after 12 years old; after the eruption of most of the permanent teeth in the anterior area, delay of eruption or impaction of the canines happens. Why the canines get impacted?

One of the reasons, is that the canines form in a very high position; mainly we're talking about impacted upper canines, their path of eruption is long. Second reason is that the 1^st premolar erupts and the lateral incisor as well, leaving no enough space for the canine to erupt.

-Most common teeth to be impacted are the third molars and the second most common are the maxillary canines.

-Upper lateral incisors erupt at the age of: 8-9 years old.

-Upper 1^st premolars erupt at the age of : 10-11 years old.

-Upper canines erupt at the age of: 11-12 years old.

Canines' role in the oral cavity:

1) The upper canines have an important role in the occlusion, we call it ''canine guidance''; canines are the first to touch when the mouth closes (usually), therefore they're important in the guidance of the arches in the proper position.

2) The canines are located at the corner of the mouth, which means that the upper canines give the shape of the maxilla, so it's important to have the canine in its proper position.

Now, when the patient is 11/12 years old and the canine is still not there, we take an OPG (it's recommended at this age to take an OPG). An orthodontist can detect from this OPG, the chances of an abnormal eruption or impaction of the tooth, therefore at this stage they can intervene and do some sort of an orthodontic treatments and create some enough space for the canine to erupt in its normal position. 80-90% of the intervention cases, there is prevention to the impaction of the canine. That is in early management cases.

However, if the "impacted canine" patient is an adult (the Dr. is talking about any age older than 14 years old) there are 3 treatment options to choose from:

i. We leave the impacted canine in its place.

The Dr. is showing a case with an impacted canine; the central incisor is there, the lateral incisor is there and the primary canine is in its place although this patient is above the age of the permanent canine eruption. The Dr.'s management would be either to leave it in its place or,

ii. Surgically remove it or,

iii. Surgical exposure; we expose the canine and with the help of an orthodontist, the canine is pulled to its place. This is the best treatment option; because of the canines' importance, but it's not always the case sometimes we have to remove it or just leave it and follow up the case.

Surgical removal is indicated when the impacted canine is associated with pathology and the most common pathology associated with it, is a cyst. This cyst is called ''dentigerous cyst'', in these cases we have to treat the pathology and most of the cases we have to remove the cyst with the associated tooth, sometimes we can open the cyst and leave the tooth. Another pathology could be a tumor which also needs a treatment.

Patient's preference; sometimes the patient might be not willing to go through an orthodontic treatment although the dentist might prefer to expose the canine and pull it, in this case we go with the patient's preference.

Sometimes, the patient might have the perfect occlusion even though the canine is impacted; the lateral and the 1^st premolar close down the space that might occur with the impacted canine, we consult an orthodontist regarding the good occlusion and whether take the tooth out or leave it, again the patient might not want to go through any treatment to pull down this canine in its place. We could have space in the maxilla where the canine is supposed to be and we might think of doing a bridge there to cover up this space, what we have to be concerned of is not to leave any impacted teeth underneath; as with time changes or pathologies may occur, in this case it should be removed. Same story if we want to put an inplant, as they are inserted in the bone and no impacted tooth getting in the way. We remove the canine wait for bone formation and then put an inplant.

There are times, when it's hard to do an orthodontic treatment, to pull or retract the canine down because of its position and location very up high or between roots of other teeth or anatomical problems in this impacted tooth (deformed/ dilacerated), in these situations we might decide to take it out. The impacted canine can be ankylosed (ankylosis) to the bone, it may not always show on an x-ray, and the decision here can be to take it out.

(The Dr. is showing an example of an impacted canine, part of an OPG with an impacted canine and a radiolucent lesion most probably a cyst, in this case we have to deal with both the tooth and the cyst)

When we decide to surgically remove the impacted tooth, first of all, we need to locate the canine, and this is a very difficult step, we have to decide whether it's located labially or palatally. Now, the OPG and the normal x-rays are 2D only and we can't determine where their impaction is only by those two, we have to investigate more before any surgery and to avoid opening from both sides (labial and palatal); risk of necrosis and loosing blood supply. Next thing to do, is to open a flap according to where the impaction is. Most of the cases the canine is inside the bone, so we have to remove some of the bone surrounding this tooth and find an area that we can catch the canine or put a good application to it down. Sometimes we have to section the tooth in small pieces for an easier removal. I take the tooth out, close the flap, suture it and give the patient instructions.

To locate the impacted canine, we start with an x-ray; we usually depend on an OPG. Other thing that helps in taking the decision, is the angulation of the lateral incisors; as they are related to the impacted canines. Let's say the impacted canine is labial to the lateral incisor and it is pushing the lateral's root to the inside (palatally) and the lateral's incisal edge labially. If the canine was situated palatally and it's pushing the lateral's root to the outside (labially) and the incisal edge palatally, we can't depend on this 100% but it helps in some cases. Palpation is helpful too; palpate the buccal sulcus and the palatal area and look for a budge in the soft tissue, we want to palpate the crown and if the canine had a pushed out root, we can misdiagnose the case. Parallax technique used to be a dependable technique, now the cone beam 3D is more used. Parallax technique (the Dr. is demonstrating on Abdallah (A.) and Bustani (B.) if you rem.; they are 2 impacted canines, (A.): is palatally located and (B.) is labially located, we want to take an x-ray, we start from a point and then change the alignment and take an x-ray from another point, now (B.) got further away and the one that got closer is (A.); the one that moves with our alignment is the palatal one and the one that goes further is the labial one: Horizontal parallax technique using 2 periapical x-rays ). Vertical parallax technique is done by using an OPG and a periapical x-ray… same story (I'm writing exactly what the Dr. is saying but here is a link that might help and the ones who didn't get the parallax thing just start reading below the " parallax" subtitle

http://ejo.oxfordjournals.org/content/23/1/25.full.pdf

and remember SLOB = Same Lingual Opposite Buccal, I hope it works) all this is used when we don't have the cone beam CT scan; this is a new technology, the CT scan has high dose of radiation so the cone beam CT scan was introduced, it gives us 3D an 3 cuts: sagittal, coronal and axial, with a smaller dose of radiation and anyone can use it as it is very easy, and it shows the exact relation of the impacted canines and other roots; the most accurate method in determining the position of the impacted teeth.

We do the extraction, if the impacted canine was located labially we open a flap labially, one-sided/ two-sided flap; expose the tooth, minimal removal of bone using a bur and then slowly take the tooth out, if there is an obstacle and it's not moving we can do sectioning to the tooth and then take it out by sections, sometimes, its position is obvious and on x-ray there is not much bone surrounding the crown, we can make a gingival flap, just a small incision above the cervical margin expose it and take it out. Usually in surgical extraction we do either a two-sided flap or a three-sided flap. if the canine was positioned palatally, 1 canine, we do an incision that extends from the 1^st molar to the 1^st premolar and it's on the gingival margin, afterwards we deflect the palatal flap, further down to the mid of the palate is the blood supply and we should be careful not to cause necrosis in the anterior area "descending palatine artery"! so no releasing incisions and tearing in the palate are allowed! If there were 2 canines, it is the incision starts from the 1^st molar left an ends at the 1^st molar 1^st right, releasing incision on the palatal surface then deflect the flap down.

Surgical exposure is done after determining the position of the canine and the evaluation of its anatomy and condition, and that it can be pull down, the orthodontist has to decide that he can create space for this canine in the arch; we don't start pulling the canine until we're sure there is enough space for it. We expose the impacted canine by removing the soft tissue and if it is covered by bone, we have to remove the bone that covers the crown we don't reach the CEJ; then it means we reached the root and it's going to be exposed and gum recession will happen to it, from the buccal or palatal without going below the CEJ. Sometimes, orthodontists they prefer the tooth to be exposed and then they wait and see; as there are some studies that say that there is an impacted tooth and surgical exposure was made and it is enough for it to erupt, as if we initiate the eruption of it, other times braces attachments are made to this exposed tooth that pulls it down.

In order to expose the tooth if it was labially situated, we could either do what we call "window flap", just a small window; we cut the whole tissues around the crown, or we can open the whole flap; three-sided flap to expose the crown and put the attachment and then return the flap in its place, so the attachment is covered we can't see it.

Apical reposition flap: we expose the crown put the attachment and then suture the flap in a slightly higher place than the tooth this will provide enough attached gingiva below the level of the crown (?) what's the point from doing that? In this case, when we removed the whole soft tissue, if there is no attached gingiva, gum recession will occur. What you need to know when we do labial flap, either we do window flap, we have to have good amount of attached gingiva underneath the tooth, or an open flap with the exposed tooth and attachment or apical reposition flap.

If the impacted canine was positioned palatally, we do the same thing; just open a small window flap and pull it down, the attachment doesn't have to be labially placed; if the tooth was impacted labially we put the attachment labially and if it was impacted palatally we put the attachment palatally… same story…

In some cases, we don't do anything; the patient has good occlusion and we took an x-ray and we found the impacted canine, not associated with any pathology, doesn't cause problems for the adjacent teeth (problems like pressure on the other roots causing resorption), a follow up for the case could be enough, this follow up would be every couple of years to make sure that no pathology is in the making…

Complications that may occur from this surgical procedure: 1. Trauma to the adjacent structures. 2. Damage to the adjacent vital structures; the impacted canine might be close to the nasal cavity, maxillary sinus and during the extraction we could make communication between the oral cavity and the nasal cavity "oro-nasal communication". 3. Fracture in the alveolar ridge; that happens if we put too much force on the impacted tooth. other vital structures like the infraorbital nerve that is near the area, so we have to be able to localize it and protect it. 4. Other complications like any other surgical procedures: edema, pain and possibility of infection.

Other impacted teeth like the lower canines/ premolars (fours and fives)same procedure is applied. Supernumerary teeth between the centrals called "mesodens".

Corrections are more than welcome c:

OS Lec#6 By Yasmin Hzzayen

OS Lec#6 By Yasmin Hzzayen

Re: OS Lec#6 By Yasmin Hzzayen