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.