Cracked tooth syndrome denotes an incomplete fracture of a tooth with a vital pulp. The fracture involves enamel and dentin, often involving the dental pulp.

Prevalence
Molars of older individuals most frequently present with cracked tooth syndrome. Most cases occur in teeth with class I restorations (39%) or in those that are unrestored (25%), but with an opposing plunger cusp occluding centrically against a marginal ridge. Mandibular molars are most commonly affected , followed by maxillary molars and maxillary premolars.

Symptoms
The patient usually complains of mild to excruciating pain at the initiation or release of biting pressure. Such teeth may be sensitive for years because of an incomplete fracture of enamel and dentin that produces only mild pain. Eventually, this pain becomes severe when the fracture involves the pulp chamber also. The pulp in these teeth may become necrotic.

Clinical features

Close examination of the crown of the tooth may disclose an enamel crack, which may be better visualized by using the following methods:

Fiber optic light: this is used to transilluminate a fracture line. Most cracks run mesiodistally and are rarely detected radiographically when they are incomplete.

Dye: Alternatively, staining the fractute with a dye, such as methylene blue, is a valuable aid to detect a fracture.

Tooth slooth: this is a small pyramid shaped plastic bite block, with a small concavity at the apex of the pyramid to accommodate the tooth cusp. This small indentation is placed over the cusp, and the patient is asked to bite down. Thus, the occlusal force is directed to one cusp at a time, exerting the desired pressure on the questionable cusp.

Root canal sealers are materials used in endodontics to fill the space between the root canal filling material (usually gutta-percha) and the walls of the root canal system. Their primary purpose is to provide a fluid-tight seal, preventing the ingress of bacteria and fluids, and to enhance the overall success of root canal treatment. Here’s a detailed overview of root canal sealers, including their types, properties, and clinical considerations.

Types of Root Canal Sealers

1. Zinc Oxide Eugenol (ZOE) Sealers

   • Composition: Zinc oxide powder mixed with eugenol (oil of cloves).
   • Properties:
     • Good sealing ability.
     • Antimicrobial properties.
     • Sedative effect on the pulp.
   • Uses: Commonly used in conjunction with gutta-percha for permanent root canal fillings. However, it can be difficult to remove if retreatment is necessary.

2. Resin-Based Sealers

   • Composition: Composed of resins, fillers, and solvents.
   • Properties:
     • Excellent adhesion to dentin and gutta-percha.
     • Good sealing ability and low solubility.
     • Aesthetic properties (some are tooth-colored).
   • Uses: Suitable for various types of root canal systems, especially in cases requiring high bond strength and sealing ability.

3. Calcium Hydroxide Sealers

   • Composition: Calcium hydroxide mixed with a vehicle (such as glycol or water).
   • Properties:
     • Biocompatible and promotes healing.
     • Antimicrobial properties.
     • Can stimulate the formation of reparative dentin.
   • Uses: Often used in cases where a temporary seal is needed or in apexification procedures.

4. Glass Ionomer Sealers

   • Composition: Glass ionomer cement (GIC) materials.
   • Properties:
     • Good adhesion to dentin.
     • Fluoride release, which can help in preventing secondary caries.
     • Biocompatible.
   • Uses: Used in conjunction with gutta-percha, particularly in cases where fluoride release is beneficial.

5. Bioceramic Sealers

   • Composition: Made from calcium silicate and other bioceramic materials.
   • Properties:
     • Excellent sealing ability and biocompatibility.
     • Hydrophilic, allowing for moisture absorption and expansion to fill voids.
     • Promotes healing and tissue regeneration.
   • Uses: Increasingly popular for permanent root canal fillings due to their favorable properties.

Properties of Ideal Root Canal Sealers

An ideal root canal sealer should possess the following properties:

• Biocompatibility: Should not cause adverse reactions in periapical tissues.
• Sealing Ability: Must provide a tight seal to prevent bacterial leakage.
• Adhesion: Should bond well to both dentin and gutta-percha.
• Flowability: Should be able to flow into irregularities and fill voids.
• Radiopacity: Should be visible on radiographs for easy identification.
• Ease of Removal: Should allow for easy retreatment if necessary.
• Antimicrobial Properties: Should inhibit bacterial growth.

Clinical Considerations

• Selection of Sealer: The choice of sealer depends on the clinical situation, the type of tooth being treated, and the specific properties required for the case.
• Application Technique: Proper application techniques are crucial for achieving an effective seal. This includes ensuring that the root canal is adequately cleaned and shaped before sealer application.
• Retreatment: Some sealers, like ZOE, can be challenging to remove during retreatment, while others, like bioceramic sealers, may offer better retrievability.
• Setting Time: The setting time of the sealer should be considered, especially in cases where immediate restoration is planned.

Conclusion

Root canal sealers play a vital role in the success of endodontic treatment by providing a seal that prevents bacterial contamination and promotes healing. Understanding the different types of sealers, their properties, and their clinical applications is essential for dental professionals to ensure effective and successful root canal therapy.

In endodontics, dental trauma often results in the luxation of teeth, which is the displacement of a tooth from its normal position in the alveolus (the bone socket that holds the tooth). There are several types of luxation injuries, each with different endodontic implications. Here are the main types of dental luxation:

1. Concussion: A tooth is injured but not displaced from its socket. The periodontal ligament (PDL) is compressed and may experience hemorrhage. The tooth is usually not loose and does not require repositioning. However, it can be tender to percussion and may exhibit some mobility. The pulp may remain vital, but it can become inflamed or necrotic due to the trauma.

2. Subluxation: The tooth is partially displaced but remains in the socket. It shows increased mobility in all directions but can be repositioned with minimal resistance. The PDL is stretched and may be damaged, leading to pulpal and periodontal issues. Endodontic treatment is often not necessary unless symptoms of pulp damage arise.

3. Lateral luxation: The tooth is displaced in a horizontal direction and may be pushed towards the adjacent teeth. The PDL is stretched and possibly torn. The tooth may be pushed out of alignment or into an incorrect position in the arch. Prompt repositioning and splinting are crucial. The pulp can be injured, and the likelihood of endodontic treatment may increase.

4. Intrusion: The tooth is pushed into the alveolar bone, either partially or completely. This can cause significant damage to the PDL and the surrounding bone tissue. The tooth may appear shorter than its neighbors. The pulp is often traumatized and can die if not treated quickly. Endodontic treatment is usually required after repositioning and stabilization.

5. Extrusion: The tooth is partially displaced out of its socket. The PDL is stretched and sometimes torn. The tooth appears longer than its neighbors. The pulp is frequently exposed, which increases the risk of infection and necrosis. Repositioning and endodontic treatment are typically necessary.

6. Avulsion: The tooth is completely knocked out of its socket. The PDL is completely severed, and the tooth may have associated soft tissue injuries. Time is of the essence in these cases. If the tooth can be replanted within 30 minutes and properly managed, the chances of saving the pulp are higher. Endodontic treatment is usually needed, with the possibility of a root canal or revascularization.

7. Inverse luxation: This is a rare type of luxation where the tooth is displaced upwards into the alveolar bone. The tooth is pushed into the bone, which can cause severe damage to the PDL and surrounding tissues. Endodontic treatment is often necessary.

8. Dystopia: Although not a true luxation, it's worth mentioning that a tooth can be displaced during eruption. This can cause the tooth to emerge in an abnormal position. Endodontic treatment may be necessary if the tooth does not respond to orthodontic treatment or if the displacement causes pain or infection.

The endodontic management of luxated teeth varies depending on the severity of the injury and the condition of the pulp. Treatments can range from simple monitoring to root canal therapy, apicoectomy, or even tooth extraction in severe cases. The goal is always to preserve the tooth and prevent further complications.

Weine Classification

The Weine classification divides root canal systems into three main categories:

The pulp canal system is complex, and it may branch, divide, and rejoin. Weine categorized the root canal systems in any root

into four basic types. Others, using cleared teeth in which the root canal systems had been stained with hematoxylin dye, found a

much more complex canal system. They identified eight pulp space configurations, that can be briefly described as following :

Type I : A single canal extends from the pulp chamber to the apex (1).

Type II: Two separate canals leave the pulp chamber and join short of the apex to form one canal (2-1).

Type III: One canal leaves the pulp chamber and divides into two in the root; the two then merge to exit as one canal (1-2-1).

Type IV: Two separate, distinct canals extend from the pulp chamber to the apex (2).

Type V: One canal leaves the pulp chamber and divides short of the apex into two separate, distinct canals with separate apical foramina (1-2).

Type VI: Two separate canals leave the pulp chamber, merge into the body of the root, and redivide short of the apex to exit as two distinct canals (2-1-2).

Type VII: One canal leaves the pulp chamber, divides and then rejoins in the body of the root, and finally redivides into two distinct canals short of the apex (1-2-1-2).

Type VIII: Three separate, distinct canals extend from the pulp chamber to the apex (3).

The Ca(OH)2, has been used by endodontists throughout the world since Hermann introduced it to dentistry in 1920.

It is a highly alkaline substance with a pH of approximately 12.5.

Calcium hydroxide has antibacterial properties and has the ability to induce repair and stimulate hard-tissue formation. The

bactericidal effects is conferred by its highly alkaline pH. The release of hydroxyl ions in an aqueous environment is related to the

antimicrobial property.

Hydroxyl ions are highly oxidizing free radicals that destroy bacteria by :

· Damaging the cytoplasmic membrane

· Protein denaturation

· Damaging bacterial DNA

The vehicle used to mix Ca(OH)2 and the manner in which it is dispensed has a significant role to play in achieving maximum

antibacterial effects as an intracanal medicament in endodontics.

In general, aqueous viscous or oily vehicles are used. The aqueous or water-soluble vehicles have high degree of solubility and

need multiple dressings to achieve desired results.

On the other hand, viscous vehicles like glycerine, polyethylene glycol, and propylene glycol promote slow solubility and hence

longer dressing intervals. The other medicaments combined with Ca(OH)2 include CMCP and 0.12% chlorhexidine.