Surgical Management of Cysts in Orofacial Region(Jaws)-Oral Surgery Lecture

CYST ENLARGEMENT

Cyst cannot stay at the same size. It will enlarge

3 THEORIES OF CYST ENLARGEMENT

(these theories might work together to cause enlargement)

• Bone resorbing factor(theory 1)

The capsule of the cyst produce bone resorbing factors like Prostaglandins, Leukotrienes, osteoclast

• Osmotic theory(theory 2)

The centre of the cyst has a higher concentration of sodium than the surrounding serum, so it tends to absorb water.

• Hydrostatic pressure(theory 3)

This water that accumulates has hydrostatic pressure which probably stimulate the release of these factor, then these factor will resorb the bone. Eventually, the small sac will became bigger and bigger with time. The enlargement of cyst is slow, it’s not a rapid process that can take over months.

SYMPTOMS OF CYST

None.

• Patient may be totally asymptomatic. The cyst does not cause much expansion yet.
• Intraoral swelling
• Extraoral swelling also possible
• Intraoral discharge.
• If the cystic sac manage to get outside the bone, then you will have discharge of straw-coloured or yellowish fluid from an intraoral sinus.
• Secondary infection that will cause pain and abscess.
• It is not painful, unless it get secondarily infection where you will have typical abscess like pain, tender teeth etc
• Lower lip anesthesia which is rare.
• A very big cyst that usually are infected will compress the inferior dental canal and mental nerve. But the most common cause of lower lip paresthesia is a tumor or osteomyelitis.
• Difficulties with dentures.
• The denture will not fit any more as it used to be
• Movement or tilting of adjacent teeth.
• A cyst locating between 2 roots, will cause the roots to move away from each other and the crown of each tooth will also move accordingly.
• Facial asymmetry or swelling in one side.
• But this rarely happens.
• The best way to assess a swelling at the mid portion of the face is to look to the patient either from above or below, so that you can get better differentiation of normal and swollen side.

SIGNS

• The signs are similar to the symptoms. The pt might be totally asymptomatic or will present with:
• Swelling
• Tender if become infected. Cysts are painless at the beginning. Pain only if it get infected
• Expansion labio-bucally.
• It is rare to have expansion lingually or palatally except the nasopalatine cyst. but cyst at the mandible will always have expansion labially or bucally. If you see lingual expansion, this is more likely to be a tumor rather than a cyst.
• Sinus with straw-coloured fluid with shimmering cholesterol crystals
• Displace teeth
• Missing teeth
• Pathological fracture (if the cyst was large).
• A very large cyst can cause the bone to be so thin that might fractured easily by even a minor trauma.
• This is a summary of time-scale FINDINGS when you try to palpate a cyst. When you examine a pt, you will only find one of these findings depends on at which stage the cyst are.

DIAGNOSIS

• History and examination. This is very important
• Radiograph (Intraoral Periapical, extraoral OPG). It is wise to have 2 radiograph that are right-angled to each other. Sometimes its good to have both intraoral PA and extraoral OPG to have an idea about the size or the extends of the cyst
• Vitality test of the neighbouring teeth. This will tell you if the periapical area is the actual cause of the cyst (from a dead pulp that confirmed an inflammatory cyst)
• Aspiration (with wide needle, no 18). This is very important when you are dealing with a jaw cyst. We don’t use fine needle to do aspiration of a cyst because it is for soft tissue masses, it will break when you try to enter a fine needle into a bone! You introduce the needle into the bone (insert the needle occlusally because this area usually thinner from the buccal or lingual area) and withdraw the content of this cyst.
• Straw-coloured fluid and crystal (inflammatory cyst or dentigerous cyst)
• If you put the fluid on a piece of gauze, you can see some spots in the yelow clear fluid. The spots that appear like sugar or salt is the cholesterol crystals. When you put it under the sunlight, you can see the cholesterol crystals clearly (shimmering).
• Blood hemorrhagic (small amount of blood most probably a hemorrhagic bone cyst. But if you have a mass bleeding once you insert the needle and the syringe filled with blood spontaneously, this is hemangioma osteomyelitis.
• Thick creamy fluid (keratocyst)
• Air (maxillary sinus, hemorrhagic). There is condenstion of air in the syringe
• Nothing (tumor). You will have negative pressure in the syringe. When you leave the plugger, it will go back by itself. This means you are dealing with a soft tissue mass that most probably a tumor, until proven otherwise.
• To minimize the amount of pt’s unease, it is wise to put 2 needles; one for the entry of the air (needle without syringe), while the other one (needle with syringe) for the aspiration. Otherwise it’ll become painful during the withdrawal.
• (like when you want to open a can, you’ll do 2 holes for the content to come out easily. It’s physics.)
• Soluble protein (albumins and globulins) determintion of the aspirate (electrophoresis)
• 5-10g/dl: inflammatory cyst (range of serum soluble protein)
• <4g/dl   : keratocyst
• Biopsy (incisional or excisional). For a confirmation of your diagnosis or if you have no clue at all, do a biopsy. We can do excisional biopsy if the cyst was small. For a very big cyst, do a flap, take some of the cyst (incisional) and send it to the histopahology lab.

TREATMENT

Once we have establish the diagnosis, we can go on to the treatment. Firstly we need to tell the pt that it is a cyst. It is benign, will not metastasize or kill the pt. That’s why some people ask why we cannot just leave it? This is because they will enlarge, bone expansion and pathological fracture. The cyst also can get infected. That’s why the pt need treatment.

Preoperatively

Vitality test on the teeth that had been reached by the cyst

Root filling of non-vital teeth

Let’s say we have a big periapical cyst at the upper lateral incisor. It might be associated with lateral incisor but in the x-ray you can see the cyst had gone to periapical of the central, the canine and also the 1^st PM. During surgery, we will remove the cyst, and do apisectomy of the involved tooth. If we know by vitality test that the central, canine and 1^st PM are vital, we will not do anything on that teeth. we will not disturb the vessels that inserted into the foramina of the vital teeth. That’s why it is important to do vitality testing before any surgery.

Treatment modalities

• Marsupialization : opening a window
• Enucleation : complete removal of the cystic sac

After done with enucleation, we can either primarily close it (suture the flap).

*in americam school they will do bone graft before suturing but we from british school won’t*

*If the cyst get infected, we will leave it open. Put a tag and it will heal by itself (not used anymore)*

• Decompression (Marsupialization followed by Enucleation)

Post-operatively

Antiseptick pack

obturator

MARSUPIALIZATION

To undertsand marsupialization, imagine the lecture room as a cyst and outside it is the oral cavity. The wallpaper that lining the room is the cystic lining. After we open the door (do surgery to open the cyst), we will suture the cystic lining (the wallpaper of lecture room) with the oral cavity lining (wallpaper outside the lecture room) and then leave it to heal. What happened was we had converted the cyst into a small pouch of the oral cavity. This action of maintaning an open window will cause the cyst to be fluid free and contain zero pressure. So bone will start forming outside the cyst and causes the cyst to shrink with time. Eventually, it will be filled completely with bone and the whole cyst will disappear. 

So for marsupialization to succeed, we need to maintain the window open. How? By constructing a small denture or obturator (something to obturate the opening) that fit inside the opening that you had created. The pt need to clean this obturator after every meal and put it back to keep the pouch open, preventing any food or fluid to accumulate inside the cyst that might cause secondary infection.

If you have no hydrostatic and osmotic pressure, the cyst will not enlarge. Think like it’s a battle of the bone-forming power and the bone-resorbing power of the cyst. If you weaken the cyst, the bone-forming power will win!

What if we just aspirate the fluid inside the cyst, without opening any window? The answer is, the fluid will start forming again because of the osmotic theory. So the idea of marsupialization was to open a window, making a zero pressure area.

This is an example of a cyst that is compressing the mental nerve. Removal of the cystic lining might danger the mental nerve and the pt will have lower lip numbness. In this situation, its better to do marsupialization.

Open a window by raising a flap.

Remove some bone that covering the cyst. Just a small window, not need to remove the whole bone covering the cyst.

Remove the impacted tooth that causing the dentigerous cyst.  

At the end, the mandible is hollow. This yellowish tissue is the lining of the cyst. We will suture it with the lining of the oral mucosa.

To maintain the area open, fill the pouch with an antiseptic pack

construct an obturator (for sure you need to take an impression first. The obturator is out of occlusion)

How about if we are dealing with dentigerous cyst? The impacted teeth that was the main factor of the cyst, when we do marsupialization, the teeth will move with the shrinken cyst.  Impacted teeth are very dramatic, they can move within the bone.

The aim of marsupialization is to gain bone. For example in a case where we have a very thin bone around the cyst (usually at the mandible), surgery might fracture the bone. so by doing marsupialization, bone will form by time. We can either wait for the complete bone formation in the pouch which will took about 6 months (in this case we do marsipulization only) or we can do enucleation after we are sure that the bone are thick enough to receive a surgery (in this case, we do decompression).

This methode also apply when we have a cyst compressing a nerve. After few months of marsupialization, the cyst will shrink away from the bone and we can consider doing enucliation at this time without damaging the nerve.

Advantage	Disadvantage	Indication
Simple (not necessarily need a specialist) Avoid damaging nerves Avoid pathological fracture	Leaves pathological tissue (We cannot sure whether it is a cyst or a cystic tumor. There might be a small tumor that we do not reach during biopsy. This is potentially dangerous) Needs great compliance (pt need to wear obturator for long periods of time) Incovenience for patient Hygiene demands (bad OH can cause bad smell of the mouth)	Very large cyst near vital structure Patient unfit for surgery (poor medical status) Infected cyst (in infected cyst, the lining is friable. Enucliation will cause the lining to tear and we might leave a small piece of the cyst. A remaining cyst can cause recurrence)

ENUCLIATION

Enucleation means complete removal of a cyst. This can be done by currettage (using currette),or by blind sections of cystic lining (we put a blunt instrument and you sort of ‘peeling’ the bony lining).

For a cyst that has a recurrence potential, you need to do peripheral osteoctomy after removing the cyst. How? By removing the 3-4mm of bone surrounding the cavity with a big, sharp bur. Make sure that the bur are big enough to remove any remaining cyst or daughter cyst (if dealing with keratocyst). 

Opening a wide flap or window and remove all the cyst as one sac(with the lining intact). Then we close the window and leave it to be fill up with bone over time.

In the case of dentigerous cyst, when you open the area you can see a bluish sac which is the cyst. Then you need to enlarge the bone around it. You bluntly remove the whole cyst with the causative impacted tooth. You can see that this is obviously a dentigerous cyst because the crown was completely covered with the dentigerous sac. 

Advantage	Disadvantage	Contraindication
Remove all pathological tissue Little patient compliance -It just takes about 10 days to see any healing activity. -oral hygiene is not so important. -You can just leave the patient and do follow-up	Difficult -You need a specialist to do especially if the cyst was too big or the cyst in the maxilla near the orbit or pterygomandibular area. You need to have experties. High morbidity to surrounding tissue -that’s why you need to trim some bone so that you can get the whole cyst out -you might endanger the maxillary sinus, the nasal lining of the nose, the ID canal -you might also thinning the posterior or the lower border of the mandible, making it susceptible to fracture	In most cases we use this methode. We just do marsupialization in cases that we had discussed. Large cyst encroaching vital structure Existing pathological fracture -pt come with already fractured bone because of the large cyst. In this case it’s contradict to do enucleation. We will do marsupialozation with splinting of the fractured bone. -We can consider doing enucleation after we gain some bone

DECOMPRESSION

As we has discuss previously, usually we do marsupialization first.

Continue with enucleation after we had:

gain some bone (bone deposition)

the cyst has become smaller

the cyst has move away from important sturucture (ID canal, maxillary sinus)

Indication:

Very large keratocyst

In this case we have save the patient from removing the mandible. I think it is not ethical and inhumane to resect the mandible only bacause of a benign cyst.

There are some authorities (mostly the non-dental authorities like ENT specialist and plastic surgeon) saying that we can resect the mandible because of the large keratocyst. But I think we need to have some patience to wait and allow the cyst to shrink. It’s a different story if we are dealing with a tumor but a keratocyst is not indicated for bone resectomy.

Cystic variants of ameloblastoma

Dentigerous cyst

In case of dentigerous cyst, after we’re done with marsupialization, the tooth will move with the shrinken cyst. if the tooth has good eruption potential, it will erupt at It’s normal position. But in majority if cases, the impacted tooth has bad eruption potential. In this situation we need to remove the impacted canine with the cyst at the same time.

Eruption cyst

Eruption cyst is easy to treat. You just de-roof it, excise the bone and the tissue covering the cyst (go down until you found the cavity of the cyst). Once you remove the tissue and bone, you will see the crown of the erupting tooth in the cystic cavity. Then we just leave it because the tooth  will erupt and the whole thing will heal.

Solitary bone cyst

You open the area, you might do detachment or do not. it will heal once you open it. Nobody knows why, but if you open the area, induce some bleeding inside it and it will heal.

Keratocyst

We know that it has high recurrence rate.

4 theories of high recurrence rate of keratocyst:

The cyst stays in marrow spaces. Marrow spaces have trabeculaetion. When you try to remove it, you might leave some remnants of cyst in it.

This lining is friable and it might tear during enucleation where we might leave some remnants.

formation of daughter cyst either as capsules or within the surrounding bone

the epithelial lining of keratocyst has growth potential

If you see in Dentigerous cyst you have stacking of cyst over  each other. While if u look at keratocyst you can see that there is definite stratification of the epithelial layer of the keratocyst (the stratification was very similar that you see at the skin). It is a tissue, not only collection of cells. It have potential of growth at the base and it will move upward until it reaches the keratinized area and became ortho or parakeratinized as we mention in the last lecture.

Because of this growth potential, it is most probably why the keratocyst recur. They behave like tumor that they can grow independently without depending on hydrostatic pressure only.

Treatment is either by enucleation but u have to eliminate the daughter cyst by peripheral osteoctomy and you have to use the big bur. If you want to gain mandible      

Some authorities do en block resection. They will resect the cyst 1cm in front, behind and below the bone. it leaves a big cavity in the mandible. And if it’s already big, they will do total  jaw resection (maxillectomy or mandibulectomy). But we don’t do this.

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