Cracks can occur in the crown or the root of a tooth. Cracks in teeth are very difficult to
restore. If the crack is limited to the crown of the tooth, placing a crown (cap) on the tooth may
protect it from further extension of the crack. If the root of a tooth is cracked, in most cases the
tooth cannot be restored and must be extracted. Teeth restored with fillings or teeth that have
undergone root canal treatment are more susceptible to cracking. Habits, such as chewing
ice, clenching and grinding can also contribute to cracked teeth.
Symptoms
Cracked teeth can present with several different symptoms. You may feel pain when
chewing or pain when the tooth is exposed to extreme temperature changes. When chewing,
the pain usually occurs when biting pressure is released. Many times the pain will come and
go, making diagnosis difficult. Cracks in teeth can be very difficult to detect, even with x-rays,
but early diagnosis is important to maintaining the tooth.
When the crack opens and closes within the tooth, the nerve of the tooth may become
irritated. Fluid may also enter the nerve canal of the tooth through the crack, causing damage
to the nerve tissue. The nerve damage may become irreversible and endodontic or root
canal treatment may be required. In some situations, the tooth may need to be extracted.
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The success rate for endodontic treatment is very high. Occasionally, endodontically treated
teeth do not respond to treatment and require retreatment.
Some reasons for endodontic failure may include:
1. Difficulty in filing and shaping of the root canal. The pulp or nerve space is very small and
cleaning the pulp tissue and filling the space is very difficult.
2. There may be accessory canals where bacteria may collect and cause infection.
3. There may be more canals than anticipated. Each tooth is distinct, and each may have
varying numbers of canals.
4. A fracture may be present or occur before or after treatment.
5. The periodontal (bone) health around the tooth may compromise the root canal treatment.
6. The filling at the root of the tooth or at the crown may leak and expose areas where bacteria
can enter the root space.
It is possible to retreat an endodontically treated tooth by removing the filling material in the
roots and reshaping and refilling the canals. It may be necessary to perform endodontic
surgery, if retreatment is not an option or is unsuccessful.
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Steps in root canal therapy:
1. Local anaesthesia (dental freezing) is administered.
2. The dental dam is applied to isolate the tooth and prevent saliva from entering the root
canals. The dental dam is a sheet of rubber that allows access to the tooth during root canal
therapy.
3. Accessing the pulp space is accomplished by creating an opening through the crown of the
tooth and into the pulp chamber, so instruments can be used to shape the canals.
4. Tiny files are used to clean and shape the canals. The files are in varying diameters that
gradually clean the canals. A disinfectant is used to irrigate the canals and keep them free of
debris. X-rays are taken during treatment to measure the canal length and to ensure proper
cleansing to the tip of the tooth.
5. The material used to fill the canal, gutta percha, is tried into the canal. The fit is checked
and adjusted as required.
6. Filling the canals is completed by using gutta percha with a cement to seal the tooth to the
apex. Additional gutta percha material will be added until the roots are completely sealed,
eliminating any space where bacteria can gather and cause infection.
7. The tooth should then be restored with a permanent restoration. It may be possible to place
a filling, but in many cases a crown should be placed. A crown will provide strength to the
tooth Some teeth may also require a post with a core foundation, prior to placing a crown,
depending on the amount of tooth structure remaining.
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Root canal therapy is a procedure where the pulp of the tooth is treated so that the natural
tooth can be maintained. The pulp tissue, which contains blood vessels, nerves and
connective tissue, is vital to the development of the tooth. Once the tooth is formed, the
function of the pulp is sensory.
The tissue of the dental pulp can be subject to irritation or injury caused by deep cavities,
trauma to the teeth, tooth cracks, chemical or thermal damage. The pulp can become
inflamed. If it cannot repair itself, the pulp needs to be removed, the canals shaped and the
space sealed, so that bacteria is prevented from gathering and causing infection.
Indications for root canal therapy
There are a number of situations where root canal therapy is indicated. If a tooth is sensitive
to touch or biting pressure, sensitive to heat or displays swelling in the gums, root canal
therapy may be indicated. There are also occasions when there is no pain associated with
the need for treatment.
Why does a tooth require root canal therapy?
If the nerve in the root is damaged, bacteria may gain entry to the nerve and cause an
infection. White blood cells, that fight infections, cannot access this space and bacteria will
infect the entire pulp.
If the nerve is not treated, pain and swelling may result. Infection can continue and cause
destruction of surrounding bone, forming an abscess. Continuing destruction may result in
loss of the tooth.
Success of Endodontic Treatment
The success rate for endodontic is approximately 95%. More than 14 million root canal
procedures are done yearly. If a tooth requiring endodontics is left untreated, bone loss and
infection can occur. This may be very painful. This tooth may be replaced with a bridge or
dental implant. But these options may be more expensive and time-consuming than treating
the offending tooth.
Root canal therapy is a way to retain teeth that may otherwise require extraction, allowing you
to eat the food you want and have a healthy smile.
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There are a number of different types of cracked teeth.
Craze lines
Craze lines are small breaks in the enamel or outer surface of the tooth. These cracks are
shallow and cause no pain. No treatment is required for this condition, unless it is desired for
esthetic purposes.
Cusp Fracture
These cracks occur when a cusp is weakened and fractures away from the tooth. If the
fractured cusp is loose and has not come off, the cusp usually needs to be removed. If the
nerve in the root of the tooth is not involved, treatment usually involves placing a crown on the
tooth. If the nerve tissue has become exposed, root canal treatment may be required
followed by a post, core and/or crown.
Crown Fracture
This type of crack is limited to the crown of the tooth, but may extend to or below the gum line.
If this type of crack is treated early, a crown may be sufficient treatment. If the pulp has
been irritated or the crack is extensive, root canal treatment may be required, followed by a
post, core and/or crown.
Split Tooth
This type of crack extends from the crown of the tooth into the root structure and usually
involves loss of the tooth. It may be possible, with a multi-rooted tooth, to section the tooth,
perform root canal treatment, and then crown the remaining portion of the tooth.
Vertical Root Fracture
These cracks begin in the root and extend to the chewing surface of the tooth. These types
of fractures have few symptoms. They are usually diagnosed once bone loss is evident on
an x-ray film. Treatment is usually extraction of the tooth. In some cases, a part of the tooth
may be maintained by sectioning the fractured part of the tooth, performing root canal
treatment and restoring with a crown.
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Endodontic (root canal) treatment is generally successful. In the rare cases when root canal
treatment fails, it may be possible to save the tooth with a minor surgical procedure (root canal
surgery).
Endodontic surgery may be needed because of chronic infection, root anatomy variations or
calcifications, or to repair root perforations.
One of the most common endodontic surgical procedures is an apicoectomy. This is an
in-office procedure where the root tip of the tooth is treated. The area around the tooth is
anaesthetized with a local anaesthetic. The root tip of the tooth is exposed. If there is any
infected tissue around the root end, it is removed so that healthy bone can then grow in
around the root. If the root end is not adequately been sealed, a small filling can be placed at
this time. It may take a number of months before the bone completely heals around the root
end.
A hemisection or root amputation are other types of surgery that can be done on root canaled
teeth. A hemisection is when one root of a lower molar, which has two roots is removed. A
root amputation is when one of the three roots of an upper molar is removed. These
procedures are performed on multi-rooted teeth where one root cannot be treated with root
canal therapy but others have been successfully treated. A hemisection or root amputation
may also be required if there is extensive bone loss around one root. These procedures
leave a smaller tooth in the original tooth space. Your dentist will discuss options to fill this
space.
As in most surgical procedures, no guarantees can be given as to the results of the treatment
but endodontic surgery is an excellent opportunity to save your tooth.
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