Mostly there is no sign if we examine the patient clinically. The crack line is not diagnosed even with the radiograph, but a cracked tooth is very painful every time the patient chews or pressure is applied on that tooth.
The treatment and the prognosis of the cracked tooth depends upon the location of the crack line i.e. whether the crack line lies supragingivally or subgingivally or it is fracturing the tooth in vertical direction involving the nerve. Supragingival means the crack line lies above the gums and the subgingival means the crack line lies below the gums.
It depends upon the type of the crack line i. e. from which part of the tooth the line crosses.
Supragingival and Oblique without Invovlving the Nerve
If the crack line is Supragingival and it does not involve the nerve, then the treatment is quiet easy and prognosis of the tooth is also good. In this case if the involved tooth is the front tooth and the patient comes with the fragment of the tooth, if it gets separated then the treatment of choice is to reattach the same fragment using good adhesive material. If the patient does not have the fragment then the lost tooth structure is built with good and tooth colored restorative material.
If the involved tooth is back tooth then in that case cracked segment is not reattached because chewing forces are more on the back tooth and the fractured segment does not stay. In this case the cracked part of the tooth is built by good restorative material and if indicated by the dentist, crown is given.
Supragingival and Oblique with Involving the Nerve
If the crack line is Supragingival i.e. above the gums margin but it involves the nerve, in that case root canal treatment has to be done. After doing the root canal treatment crown is given. The prognosis of this type of tooth is also good.
Subgingival Crack Line without Involving the Nerve
If the crack line goes below the gum line, the cracked fragment remains attached with the tooth and it is very painful whenever there is small movement. In this case the cracked segment is removed and periodontal surgery has to be done to expose the margin. In this type mostly the part of the tooth which is lost is so much that, the root canal treatment is advised along with post and core and the crown. The prognosis depends upon how far the crack line is below the gum line.
Subgingival Crack Line with Involving the Nerve
If the crack line is below the gum and it involves the nerve even then the treatment remains the same. Dentist has to do the root canal but in this case post and core and crown becomes mandatory as the part of the tooth lost is definitely more.
In the back teeth, there is not a single root. At a point the root divides either into two parts or three parts that is called furcation area. When the crack lines passes through the furcation area the prognosis is very poor. If the patient comes immediately before the infection sets then after root canal and giving post and crown. Dentist can think of saving the tooth. Now new materials like MTA (Mineral Trioxide Aggregate) have come which has very good potential of repairing the tooth. Still dentists cannot guarantee about the prognosis. Some may last for few years but some may last with in a year.
Root fracture can be
At apical 1/3
Vertical Root fracture
This type of fracture is at the end of the root. This has good prognosis. We leave the tooth like this and give instructions to the patient not to put pressure on the tooth for couple of weeks. If the symptoms are there then the root canal treatment is performed but we leave the fractured part. Nature takes care of the fractured part.
If the fracture line is between the end of the root and the beginning of the root, the prognosis is not very good. If the tooth is mobile then splinting is done and root canal treatment is done. After that in such cases post and core can be put to stabilize the fragments. But the length of the post core should be such that it crosses the fracture line.
When the crack line is near the function of crown and root, the prognosis is very bad. In that case the extraction of tooth is the only option.
In this Picture
1) Root fracture at cervical 1/3
2) Root fracture at apical 1/3
Vertical Root Fracture
These types of fracture occur in root canal treated teeth. When the root canal treatment is done in a particular tooth it becomes brittle and loses its elasticity. When we put post and core in these types of teeth some times the fracture occur in the root or if this is used as the abutment tooth (support tooth) in the canti liver bridge (the bridge where the support is only from side and the other side is hanging). The prognosis is very bad and these types of teeth have to be extracted.
Now the question arises whether the cracked tooth can be saved?
It all depends upon the type of crack and how quickly the patient comes to the dentist. With cracked teeth mostly pain occurs while chewing so the patient does not see the dentist. The other problem is to diagnose the case because the crack line is not visible clinically so the dentist cannot ascertain whether he will be able to save the tooth or not. Some times the dentist starts with a very positive note but still the extraction has to take place, so sparing cracked teeth is always very risky.
So it is always better to take care of our teeth.
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