Jan Bellows, DVM
Diplomate, American Veterinary Dental College
All Pets Dental Clinic
9111 Taft St.
Pembroke Pines, FL 33024
(954) 432-1111
ENDODONTICS: CARE FOR THE FRACTURED TOOTH
The days of observing and neglecting fractured teeth should be over. Our
patients may not "complain" to their owners or us about fractured teeth until
lesions have progressed sometimes to the untreatable
All teeth are susceptible to fracture, however in the mature dog the
maxillary canines are most commonly broken, followed by the mandibular
canines, the maxillary fourth premolars, and incisors. In the immature dog
deciduous canine teeth commonly fracture. In the cat the canine teeth
fracture most often.
How do small animals fracture their teeth? Commonly from chewing on cage
doors, airplane crates, or chain linked fences. Also implicated are hard chew
toys, ice cubes, and horse hooves. Auto accidents, aggressive Schutzhund
training, and dog fights can additionally lead to fractures.
What happens to a tooth when a fracture occurs? The lesions that develop
vary. Many times a tooth fracture will occur that does not enter the pulp
chamber and only the enamel or dentin is affected. Even so, trauma that
caused the enamel and dentin to fracture may be sufficient to cause direct
vascular damage and hemorrhage that can lead to inflammation and tissue
destruction. Bacteria can then move in through anachoresis (the process of
bacteria lodging in an area of previously damaged tissue) causing a myriad of
problems ranging from internal inflammation to an apical abscess.
Therapy decisions depend on which parts of the tooth are exposed. If the
fracture involves enamel only, the treatment of choice is to smooth the sharp
edges with fine diamond burs and sanding disks, in order to prevent trauma to
the lips and tongue. Intraoral radiographs should be taken to get baseline
images of the apex and to check for apical fractures The tooth should be
re-radiographed six and twelve months for evidence of perlaplcal
pathology.
If the crown fracture involves enamel and dentin, bacteria have a direct
pathway to the pulp through the dentinal tubules. Initial treatment of choice
after intraoral films involves covering the exposed dentin with a layer of
calcium hydroxide followed by glass ionomer. Restoration of the tooth with
amalgam, acrylic composite, or metallic crowns follow. Follow-up radiographs
should be taken at six month intervals after the injury for several years
examining the pulp chamber for internal resorption and the periapical
structures for pathology.
Sometimes the crown fractures and pulp is exposed. This will be visually
evident as a red or brown dot on the cut surface of the fracture. If the dot
is black and shiny there may not be a pulp exposure but an area of sclerotic
or reparative dentin A method to diagnose pulpal exposure is to
insert an explorer tip into the suspected exposed pulp. If the explorer tip
does not penetrate, then a pulp exposure is probably not present. An
intraoral film should be taken and if the pulp chamber, the periapical, and
periodontal structures appear normal then, no fudher therapy is necessary.
Follow-up radiographs are recommended.
If an exposure of the pulp exists, endodontic therapy must be performed or
the tooth extracted. An untreated exposed pulp can lead to pulpal necrosis
and abscess formation from bacterial infection.
Two variables that enter into the decision making process when the pulp is
exposed, are: i-the age of the patient and 2-the time between the fracture
and treatment.
Immediately after pulpal exposure, and for up to two weeks, inflammation of
the pulp exists less than two millimeters from the exposure site. When
superficial necrosis does occur, healthy pulp tissue is usually found several
millimeters deeper within the pulp. If superficial layers of the pulp are
removed, healthy pulp tissue is usually encountered that will respond to
vital conservative pulp procedures. If the fracture is recent (less than two
weeks old) and the patient is less than one and a half years old, a vital
pulpotomy also referred to as apexogenesis in the young patient can be
performed. One to four millimeters of pulp tissue are removed with a high
speed drill and a direct pulp cap with calcium hydroxide is applied as a
dressing on top of the vital pulp. The hope is that calcium hydroxide will
stimulate dentinogenisis forming a new dentinal bridge over the fracture
site.
The primary goal in conventional endodontics is sealing the apex to prevent
transmission of harmful bacteria to the periapical structures. If the dog or
cat is less than one and a half years old, the root apex has not completely
closed making an effective seal via the non-surgical root canal procedure
uncertain. When an immature patient is presented with an older fracture an
apexification treatment can be performed that allows the apex of the root to
continue to mature so a conventional root canal procedure can be performed at
a later time. Apexification is accomplished by performing a conventional
endodontic procedure with the exception of calcium hydroxide paste is used to
fill the canal Follow-up radiographs are taken every two months to evaluate
apical closure. Once the root tip is closed, the calcium hydroxide is removed
and the canal filled with gutta percha and zinc oxide-eugenol.
In the mature patient with recent fracture a vital pulpotomy with follow-up
radiographs can be performed, but may not be as long term effective as
conventional endodontics. In cases that the owners do not know when the
fracture occurred, or if the fracture is greater than two weeks old, then a
conventional root canal procedure should be performed to remove the effected
pulp, seal the apex and restore the crown. In cases where intraoral
radiographs show marked periapical lysis, retrograde surgical endodontics or
extractions are indicated.
Materials chosen for crown restoration depend on how the crown was fractured.
An acrylic composite is easy to apply as a restoration and approximates the
appearance of the tooth. Unfortunately acrylic does not hold up well to
occlusal trauma. A better choice would metallic crowns fabricated from
nickel and chromium.HOW TO DO ROOT CANALS
Indications
*Fractured teeth with pulpal exposure-more than 24 hours old, fractured
segments coronal to gum line.
*Discolored teeth-usually indicates pulpal death from trauma. Can result in
periapical abscess if untreated,
*Periapical abscesses with or without fistula formation.
*Prior to post placement for crown placement.
Instrumentation
"Hardware"
*delivery system to make access-high speed air drill with water.
*lentulo filler-helps delivering apical sealing cement to root apex.
*dental x-ray machine-makes endodontics much easier-conventional machines can
be used at 10 Mass 50-70 kvp 12"FFD
*light cure gun-for restoration of access hole (optional)
"Software"
*barbed broaches-used to remove pulp
*endodontic files-diameter sizes 10-80 length sizes 21, 25, or 55 mm
*paper points-for drying canal-same size and diameter as files
*gutta percha-inert filling material for root canal
*Zinc-oxide Eugenol-liquid-paste sealer for root apex
*composiet or amalgam for restoration
Procedure: Seven steps to a successful root canal
1.make access opening over each root as close to gum line as practical
2 use barbed broach to remove root
3.use files to ream out root canal and remove necrotic debris between each
larger file size irrigate canal with Chorox and saline Take intraoral
radiograph to make sure you are working 2 mm from the apex.
4.dry out canal with paper points.
5. mix zinc-oxide eugenol place on spiral filler and fill canal.
6-pack appropriate sized gutta percha points into pulp chamber, radiograph
7.restore access opening composite or amalgam.
There are variations of different steps and instruments used to complete the
conventional root canal procedure.