I. VASCULAR VITALITY ASSESSMENT OF PULP

Traditional vitality assessment methods such as heat, cold, and electric pulp testers assess neural vitality and often cause false-positive errors. As the histological assessment of pulpal status is not feasible clinically, a tool to assess the vascular flow of the pulp would be very useful.

Laser Doppler flowmetry (LDF) is an accurate method to assess the blood flow in a microvascular system

II. PULP CAPPING AND PULPOTOMY

Pulp capping and pulpotomy constitute a more conservative form of pulp therapy in comparison to pulpectomy. Although the outcome of pulp capping procedure is variable ranging from 44 to 97%, the procedure is recommended when the exposure is 1.0 mm or less and especially when the patient is young. Pulpotomy is recommended in immature permanent teeth, where pulpectomy is not advised.

The most commonly used agents for both the procedures are calcium hydroxide and MTA (mineral trioxide aggregate). The use of a laser in these procedures leads to a potentially bloodless field as the laser has the ability to coagulate and seal small blood vessels. The laser-tissue interactions make the treated wound surface sterile and also improve the prognosis of the procedure.

III. DISINFECTION OF ROOT CANALS

The ability of bacterial pathogens to persist after shaping and cleaning is one of the main reasons for endodontic failures. This is attributed to the complex nature of the root canal system, the presence of a smear layer, and the fact that large areas (over 35%) of the canal surface area remain unchanged following instrumentation with various Ni-Ti techniques.

IV. OBTURATION

Thermoplasticized gutta-percha obturation systems are one of the most efficient methods is achieving a fluid-impervious seal. Softening of the gutta-percha has been attempted with various lasers. These include argon, CO , Nd:YAG, and Er:YAG.

V.APICAL SURGERY

Apical surgery including apical resection is indicated when the previously performed root canal therapy fails and nonsurgical means are inadequate to ensure the complete removal of the pathological process.

The potential for using lasers is on the basis of the following observations:
• Ability of lasers to coagulate and seal small blood vessels, thereby enabling a bloodless surgical field
• Sterilization of the surgical site
• Potential of lasers (Er:YAG) to cut hard dental tissues without causing elaborate thermal damage to the adjoining tissues .

Techniques for Compaction of Gutta-Percha

1. Lateral Condensation

   • Description: This technique involves the use of a master cone of gutta-percha that is fitted to the prepared canal. Smaller accessory cones are then added and compacted laterally using a hand or rotary instrument.
   • Advantages:
     • Simplicity: Easy to learn and perform.
     • Adaptability: Can be used in various canal shapes and sizes.
     • Good Sealing Ability: Provides a dense fill and good adaptation to canal walls.
   • Disadvantages:
     • Time-Consuming: Can be slower than other techniques.
     • Risk of Overfilling: Potential for extrusion of material beyond the apex if not carefully managed.
     • Difficult in Complex Canals: May not adequately fill irregularly shaped canals.

2. Vertical Condensation

   • Description: In this technique, a master cone is placed in the canal, and heat is applied to the gutta-percha using a heated plugger. The softened gutta-percha is then compacted vertically.
   • Advantages:
     • Excellent Adaptation: Provides a better seal in irregularly shaped canals.
     • Reduced Voids: The heat softens the gutta-percha, allowing it to flow into canal irregularities.
     • Faster Technique: Generally quicker than lateral condensation.
   • Disadvantages:
     • Equipment Requirement: Requires specialized equipment (heated plugger).
     • Risk of Overheating: Potential for damaging the tooth structure if the temperature is too high.
     • Skill Level: Requires more skill and experience to perform effectively.

3. Thermoplasticized Gutta-Percha Techniques

   • Description: These techniques involve heating gutta-percha to a temperature that allows it to flow into the canal system. Methods include the use of a syringe (e.g., System B) or a warm vertical compaction technique.
   • Advantages:
     • Excellent Fill: Provides a three-dimensional fill of the canal system.
     • Adaptability: Can adapt to complex canal anatomies.
     • Reduced Voids: Minimizes the presence of voids and enhances sealing.
   • Disadvantages:
     • Equipment Cost: Requires specialized equipment, which can be expensive.
     • Learning Curve: May require additional training to master the technique.
     • Potential for Overfilling: Risk of extrusion if not carefully controlled.

4. Single Cone Technique

   • Description: This technique uses a single gutta-percha cone that is fitted to the canal and sealed with a sealer. It is often used with bioceramic or resin-based sealers.
   • Advantages:
     • Simplicity: Easy to perform and requires less time.
     • Less Technique-Sensitive: Reduces the risk of procedural errors.
     • Good for Certain Cases: Effective in cases with simpler canal systems.
   • Disadvantages:
     • Limited Adaptation: May not adequately fill complex canal systems.
     • Potential for Voids: Increased risk of voids compared to other techniques.
     • Less Retention: May not provide as strong a seal as other methods.

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.

Common Canal Configurations:
There are many combinations of canals that are present in the roots  of human permanent dentition, most of these root canal systems in any one root can be categorized in six different types.  These six types are:

Type I : Single canal from pulp chamber to the apex.

Type II : Two separate canals leaving the chamber but merging short of the apex to form only one canal.

Type III : Two separate canals leaving the chamber and existing the root in separate apical foramina.

Type IV : One canal leaving the pulp chamber but dividing short of the apex into two separate canals with two separate apical foramina.

Type V : One canal that divides into two in the body of the root but returns to exist as one apical foramen.

Type VI : Two canals that merge in the body of the root but re-divide to exist into two apical foramina.

Root Canal Classes:

Another classification has been developed to describe the  completion of root canal formation and curvature.

Class I : Mature straight root canal.

Class II : Mature but complicated root canal having-severe curvature, S-shaped course, dilacerations or bayonet curve.

Class III : Immature root canal either tubular or blunder bass.

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.