Have you ever bitten into something hard, felt a sharp pain that stops as soon as you release the pressure, and can not figure out where the pain was coming from? Despite no signs of decay, excruciating pain occurs with biting. That could very well be Cracked tooth syndrome (CTS).

Introduction

The Cracked Tooth Syndrome was defined by Cameron in 1964 as an incomplete fracture of a vital posterior tooth that involves the dentin and occasionally extends to the pulp. Later, it became a fractured plane of unknown depth, which originates from the crown, passes through the tooth structure, extends subgingivally, and may progress to connect with the pulp or periodontal ligament.¹ 

Classification

American Association of Endodontists classifies CTS into the following types:

1. Craze line

It originates in the crown, has a variable direction, is asymptomatic, and has a vital pulp. It has an excellent prognosis.

2. Fractured cusp

Origin is in the crown, direction can be mesiodistal or faciolingual, mild symptoms, the pulp is usually vital, and has a good prognosis.

3. Cracked tooth

It can originate in the crown or the root in the mesiodistal direction. Acute pain occurs on biting and occasional sharp pain to cold. The pulp status is variable, and prognosis depends on the depth and extent of the crack. 

4. Split tooth

Similar in origin and direction to the cracked tooth, with pain on chewing and treated pulp, it has a poor prognosis.

5. Vertical root fractures

Originating in the roots which extend in a faciolingual direction, pain is vague, mostly occurs in RC-treated teeth, and the prognosis is poor.²

Importance of understanding CTS

Gibbs described it as cuspal fracture odontalgia. He coined this term in 1954 for clinical symptoms of incomplete fracture of cusps of posterior teeth. It can be described as a small break or crack in any part of the tooth. Its severity varies from being asymptomatic to causing excruciating pain depending upon the extent of the crack. Early diagnosis of a cracked tooth is important as it helps save the tooth. It helps in good restorative management and is thus linked with a better prognosis.²

Causes of cracked tooth syndrome³

CTS occurs due to many reasons. Prevention, diagnosis, and treatment of CTS depend on understanding its origin. Predisposing factors include those that impair the teeth's resistance to chewing force or increase the force applied to the teeth. These can be due to dental procedures known as Iatrogenic factors and non-iatrogenic factors which are unrelated to any kind of procedures but are normal physiological processes.

Iatrogenic procedures

• Root canal therapy
  • Instrumentation can weaken the tooth structure
  • Higher concentration of sodium hypochlorite
  • Excessive widening of the root canal
• Restorative procedures
  • Inadequate design procedures like extra removal of tooth structure
  • Insufficient protection in the cuspal fossa region
  • Improper stress distribution
  • Metallic restorations increase differences in thermal expansion from that of tooth structure
• Head and neck radiation therapy
  • Weakens the tooth structure
  • Has a synergistic effect with other symptoms. 
  • Causes tooth demineralization
• Stress function
  • Stress exerted on adjacent teeth during extraction
  • Excessive masticatory forces on healthy teeth and physiological forces on weakened teeth can cause CTS

Non Iatrogenic procedures

It includes the developmental, functional, and pathological processes associated with teeth. Some of the factors are:

• Ageing
  • Decreases elasticity of dentin
  • Tooth fractures when forces exceed the elasticity
• Oral habits
  • Unilateral chewing
  • Sleep bruxism
  • Premature occlusion
• Tooth structure
  • Large pulp chambers
  • Incomplete fusion during development
  • High cusp inclination

Diagnosis of cracked tooth syndrome⁴

CTS presents with variable and unusual symptoms. It poses a challenge for practitioners to make a diagnosis. Pain occurring as a result of CTS resembles pathologies like Temporomandibular disorders, sinusitis, ear pain, and headache as well. Patients cannot point to the affected tooth because of vague and diffuse pain. An appropriate diagnosis is necessary. Early diagnosis helps prevent pulp involvement and saves the tooth. Some of the ways to diagnose CTS are:

History

Patients give dental history involving any procedures carried out on the tooth, history of pain after biting on a particular tooth, and habits that might contribute to CTS.

Clinical examination

Pinpointing cracks is difficult, making the diagnosis of CTS complex. However, visual examination of facets, gum defects, eliciting cold and hot stimuli, and improper restorations can help to locate the affected teeth.

Tactile examination

Scratching the tooth surface with an explorer may reveal a crack by engaging the explorer.

Excavation

Removing an existing restoration may reveal fracture lines, yet patients must be aware of inconclusive findings.

Percussion 

Cracked teeth are often tender to percussion and can be distinguished sometimes. 

Dye test

Dyes like methylene blue are used to highlight the fracture lines.

Transillumination

The most common diagnostic test of CTS is placing a light source on the tooth. If a crack is present, it will disrupt the transmission of light. 

Bite tests

Patients can be asked to bite a cotton roll and then release the pressure. Diagnosis is confirmed by pain after a sudden release of pressure. 

Symptoms

CTS presents with varying signs and symptoms depending on the position and severity of the fracture. Patients may present with one or more of the following symptoms:

• History of pain and discomfort when biting or consuming cold food or drinks for several months
• Pain on release of pressure, also known as rebound pain
• Pain elicited by intake of sugary substances
• Pain experienced while grinding teeth or while making jaw movements
• Most often, patients are unable to locate the offending tooth
• Heat-induced sensitivity is not present
• No radiographic signs of chronic pulpitis
• Pulp involvement may occur because of cracks and microleakage from them
• There may be swelling around the tooth
• Untreated cracked teeth may further cause many dental problems⁵

Management 

Different protocols exist for managing CTS. Appropriate management would be cost-effective, conservative, efficient, and prompt in treatment. Restorative therapy aims to immobilize the movable fragments. 

Some common treatment options for CTS include:

• Immediate treatment
  • A circumferential splint is a tight-fitting stainless steel band or a copper ring that immobilizes the tooth. They are tight-fitting and do not interfere with the occlusion. Occlusal grinding provides temporary relief but is not recommended as it causes pressure on the tooth after contacting a food bolus
  • The temporary crown is a cost-effective, minimally invasive way to provide relief though not easily accessible and some clinicians might not have the expertise to place them. Placing temporary, full-coverage acrylic crowns has also been described as another way of providing relief in the case of CTS. These restorations, though effective, are also time-consuming and costly
  • Direct composite splints are a quick, low-cost, readily available, and non-invasive method of providing relief in CTS
• Long-term management of CTS
  • Inlays, onlays, direct and indirect restorations provide long-term management of CTS. They have the benefit of improving the fracture strength of the tooth and decreasing the complications but have the disadvantage of undermining the residual tooth structure and causing pulpal injuries⁶ 

FAQs

Is it ok to live with a cracked tooth?

Cracked tooth leads to infection and cause serious health issues. It is advisable to get it treated as soon as possible.

Which tooth is most affected by cracked tooth syndrome?

The most affected teeth are mandibular second molars, followed by mandibular first molars, and maxillary premolars.

How to treat a cracked tooth?

It can be treated temporarily by relieving the occlusion and for permanent solution, it requires restorative procedures. 

Summary

Prevention plays an important role in saving teeth from the effects of CTS. To prevent CTS, one should aim to practice good oral hygiene by cleaning the teeth properly, learning appropriate chewing techniques, and adhering to a balanced diet that limits intake of hard foods, betel nuts, abrasions, and clenching. It can also be beneficial to increase the frequency of oral examinations, which is particularly crucial for the elderly. 

Whenever symptoms of CTS are noticed, it is imperative to address them to avoid further damage.