Oral cysts are frequently observed in dogs

Dentigerous, follicular and radicular cysts are diagnosed frequently in dogs.  Dentigerous cysts are particularly common in small breeds of dogs however they occur in all breeds.  Unerupted or embedded teeth are often found within these oral cysts.  Oral cysts are benign lesions however as they expand from continuous fluid secretion, severe local destruction occurs.  Bone, periodontal tissues and teeth can be destroyed by oral cysts.

How are oral cysts diagnosed?

Every time a tooth appears to be missing, a dental radiograph should be taken to determine if the tooth is truely missing or whether it may be unerupted or embeded subgingivally.  Embedded teeth can result in oral cyst formation.  Dental radiographs also help confirm the lesion is a cyst.

                 
Cyst around the embeded canine tooth.                              Tooth was removed & tissue evaluation

                                                                                                  confirmed a follicular cyst.


Dental radiography provides strong evidence toward the diagnosis of oral cysts.  Confirmatory diagnosis is established from histologic (tissue) evaluation by a pathologist.  These lesions have secretory epithelial lining.

Why are oral cysts clinically significant?

Oral cysts are clinically significant because they often cause severe local destruction of teeth, periodontal tissues and bone.  This local destruction can weaken the jaw and contribute to jaw fracture.

The clinical views of oral cysts (below) demonstrate that they frequently appear as fluid filled oral masses in the mandibular premolar region.  These cysts typically contain embedded teeth or dental remnant tissue and we consistantly find that they are tremendously destructive!  The earlier they are diagnosed and treated, the locallized destruction is minimized.

We have also managed patients with oral cysts in the incisive and maxillary regions.  Clinical photographs illustrate various presentations below.

How can oral cysts be prevented?

Oral cysts are particular common in small breeds of dogs from our clinical experience.
The most likely reason oral cysts are more common in small breeds is due to dental crowding which contributes to problems with tooth eruption.  Embedded teeth are frequently associated with dentigerous cysts.

These cysts can be prevented by performing a thorough oral exam during every physical exam.  Early recognition of missing teeth is important.  To recognize missing teeth, the observer must be familiar with the normal number of teeth.  Dental radiographs must be used to conform the tooth is truely missing and not embedded subgingivally. 

Dental radiographs will allow for the diagnosis of embedded teeth as well as early cystic developments.  Early extraction of unerupted or embedded teeth can prevent dentigerous cyst formation.  Early recognition and meticulous treatment of these cysts can prevent widespread destruction caused by them.

How are oral cysts treated?

Oral cysts are treated surgically.  The entire lining of the cyst must be removed or the cyst will likely return.  If at all possible, we try to excise the entire cyst "en-bloc" to avoid leaving the secretory lining within the defect (see clinical photos below).  In every case, the final surgical defect is curetted free of tissue and debris.  Teeth embeded within the cyst as well as adjacent extracted teeth are always submitted with the cystic lining tissue for histology.  Confirmation of the presumptive diagnosis of "oral cyst" must be confirmed to rule out potentially life threatening malignant oral tumors.  Additionally, radicular cysts, periapical cysts, granulomas and abscesses may need to be ruled out.  Each case must be managed based on the dental radiograph findings. 

The adjacent teeth must be evaluated for vitality (life).  Non-vital (dead) teeth must be treated by root canal therapy or by dental extraction.  The destructive nature of oral cysts makes dental extraction a higher risk for jaw fracture.  Extreme care is required to avoid complications.

For animals with severe local bone destruction, bone grafting should be performed.  An allograft is very suitable for alveolar crest augmentation to improve jaw strength.  Other osteoconductive or "osteopromotive" materials may also be used.

Clinical photos from referral cases managed by Dr. Kressin.

These specific cases were chosen to illustrate important procedures required in treating oral cysts! 

The importance of dental radiographs.

Here we have a supernumerary lower 1st premolar. It was identified underneath the gum line with dental x-rays.  

  

A cyst was already starting to form. The tooth was removed and the site sutured.

 

 

The contralateral side had a much larger cyst that was repaired 

 



Typical dentigerous cyst presentation in mandibular (lower jaw) premolar region.

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Oral (dentigerous) cyst as viewed from above.
This is the classic location in the mandibular
premolar area.  This is also the classic
appearance of these lesions.

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A periodontal probe was used to measure
the cyst and for percussion of the fluid within it.
Dental radiographs confirmed localized
bone loss.

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This lesion has been opened and an unerupted
first premolar tooth was identified within a
pool of pink fluid. Viewed from above.

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Cystic lesion viewed from behind.

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The cystic lining was carefully curetted
circumferentially and submitted with
the premolar tooth for histology
(tissue analysis by a pathologist).


This case was in the typical location with an atypical appearance.


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A missing premolar tooth was identified
below this firm protrusion of gingival tissue.
This firm elevation of the gingiva (gum) is not
a typical presentation with oral cysts.

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A dental radiograph demonstrated a
malpositioned premolar tooth within the
subgingival mass.   Also notice the
bony destruction.

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The upper soft tissue (the operculum)
was incised and reflected towards the
tongue to expose the unerupted premolar
tooth.

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The cystic tissue lining was previously lifted
from the defect in an "en-block" fashion.  This
photo shows a curette being used to meticulously
remove remaining lining tissue in an attempt to
prevent reoccurance.  All tissues are submitted to
a  pathologist for histology.

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Cystic defect viewed from the side.

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View of cyst from above.

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The surgical defect was sutured closed
after placement of a graft material.

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This radiograph demonstrates the filled
defect.  The material was gently compressed
into the cystic defect.  Histology confirmed
that this was a dentigerous cyst.

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Top view of blood filled cystic fluid.

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Alternate view of cyst.

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Initial surgical isolation of cyst.

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Fluid has exuded from the cyst.

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An "en-bloc" surgical excision of lining
tissue.

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Notice the imbeded premolar tooth.

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Premolar tooth attached to the lining tissue. 
The defect was curetted 360 degrees.

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View of defect after curettage and prior
to placement of bone graft material.

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Closure of surgical defect.


The following oral cyst was very descructive and associated with the upper premolar and molar teeth in the upper maxillary bone!


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Right side view of the upper jaw with
substantial fluid filled swelling (oral cyst).

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Alternate view from the bottom of cyst.
It appears the cyst has drained and
partially deflated.

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Destruction of the maxilla supporting
the fourth premolar and molar teeth.

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Cystic lining tissue identified.

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The cyst was opened, fluid exuded and
a tooth-like structure was identified.

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An imbeded tooth remnant was identified
surgically and confirmed histologically.

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Severe cavitational destruction of the maxilla.



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Extensive bony destruction from chronic
pressure build up.


Severe left facial swelling in a 5 year old dog.


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Matisse; 5 year old dog with a severe left side facial swelling.

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Dental radiograph left premolar area.     Alternate view of left facial swelling.

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View of swelling inside the mouth.

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Second premolar tooth within fluid       Premolar tooth within very deep cyst.
filled cyst.

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The embedded premolar was removed.
   
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Periodontal probe measured very large
cystic cavity; 32mm x 15mm x 14mm.

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Surgical defect closed with 5-0 Monocryl Suture.
Cystic lining tissue and premolar tooth
submitted for histology.

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Post-operative dental radiograph with
embedded premolar tooth removed.


French Spaniel at seven months with unerupted, embedded lower first premolar teeth on both sides.  Embedded teeth create a risk for dentigerous cyst formation.  Missing teeth must be evaluated with dental radiographs to identify unerupted, embedded teeth!


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Lower right first premolar missing.       Lower left first premolar missing.

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This dental radiograph demonstrates both the left and right first premolar teeth
malpositioned between the canine and the second premolar on both sides.  These
teeth are called embedded and create a risk for dentigerous cyst formation.

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Horizontally embedded first premolar.   Horizontally impacted first premolar.   

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Lower right first premolaw exposed.     Lower left first premolar exposed.

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Right side surgical defect sutured.      Left side surgical defect sutured closed!

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Post surgical dental radiograph            Embedded first premolar extracted!
demonstrates extracted premolar.


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