NS-ReRCT max incisors

Question 1

How are teeth with blocked and ledged canals treated?

Answer 1

A blocked canal contains residual pulp tissue.This debris is frequently infected, resulting in persistent disease, and must be removed if possible (Jafarzadeh & Abbott 2007). A ledge is a type of canal transporta- tion that results in irregular shaping on the outside of the canal curvature.The ledge makes it difficult to detect the original canal.The best treatment for blocked and ledged canals is to prevent their occur- rence. If the clinician is careful during instrumenta- tion, the chances for blocked and ledged canals to develop are minimized (Roda & Gettleman 2011). Blocks and ledges may be detectible on radiographs as a root filling short of the ideal working length. However, short filling should not be performed in re‐ treatment (Farzaneh, Abitbol & Friedman 2004). When a block or ledge is encountered, the coronal portion of the canal should be enlarged to enhance tactile impression. Frequent irrigation should be performed to remove the debris that could block access.The obstacle should be gently probed with a pre‐curved size #10 K‐file to determine if there are any “sticky” spots that could be the entrance to a blocked canal. Frequent irrigation and use of a lubricant such as RC‐Prep® enhances the ability to place a small file into the apical canal (Roda & Gettleman 2011). A K‐file is useful for penetrating and enlarging root canals. When the negotiation with watch‐winding motion results in some resistance, the clinician should continue to negotiate until further apical advancement is accomplished. Once apical working length is achieved, apical patency should be confirmed using an electric apex locator. If a sticky spot cannot be found, the clinician must consider the possible presence of a ledge.This technique is useful for ledged canals. After detecting the original canals, shaping is performed as usual.

Question 2

Why is initial treatment sometimes a failure?

Answer 2

The following are examples of reasons for failure of initial treatment:

• Persistent or reintroduced intra‐radicular microorganisms: When the root canal space and dentinal tubules are contaminated with microorganisms, and allowed to contact the periradicular tissues, apical periodontitis develops. Inadequate cleaning, shaping, obturation, and final restoration of an endodontically diseased tooth can lead to posttreatment disease (Roda & Gettleman 2011). If initial endodontic treatment does not leave the canal space free of bacteria, if the obturation does not adequately entomb those that may remain (Siqueira & Rôças 2008), or if new microorganisms are allowed to re‐enter the cleaned and sealed canal space, posttreatment disease can and usually does occur.
• Extra‐radicular infection: Bacterial cells can invade the periradicular tissues by spread of infection from the root canal space through contaminated periodontal pockets that communicate with the apical area, through extrusion of infected debris, or by use of infected endodontic instruments (Simon, Glick & Frank 1972).
• Foreign body reaction: Persistent endodontic dis- ease occurs in the absence of discernable micro- organisms and has been attributed to the presence of foreign material in the periradicular area. Several materials have been associated with inflammatory responses (Roda & Gettleman 2011). Generally, filling material extrusion leads to a lower incidence of healing.
• True cysts: The incidence of periapical cysts has been reported to be 15–42% of all periapical lesions (Roda & Gettleman 2011). It is hard to determine radiographically whether periapical radiolucency is a cyst or not (Bhaskar & Rappaport 1971).

Question 3

How is a tooth‐caused sinus tract traced?

Answer 3

The sinus tract is useful to detect the source of a given infection.The opening of the sinus tract may be located directly adjacent to or at a distant site from the infection (Roda & Gettleman 2011).Tracing the sinus tract will provide objectivity in diagnosing the location of the problem tooth.To trace the sinus tract, a size #25–#35 gutta‐percha cone is threaded into the opening of the sinus tract. Although this may be slightly uncomfortable to the patient, the cone should be inserted until resistance is obtained. After a periapical radiograph is taken, the gutta‐percha cone detects the location of the pathosis.

Question 4

What are the important points in cases involving multiple visits?

Answer 4

The canals are dressed with setting calcium hydroxide, and 3.5 mm of temporary filling is placed to decrease bacterial leakage.

Question 5

For which cases are multiple visits recommended?

Answer 5

The following are examples of cases warranting multiple visits:
• There is a clinical symptom such as pain, swelling,
or sinus tract.
• The prognosis is difficult to predict and therapeu- tic effect must be evaluated.
• There is bleeding, discharge of pus, or exudate at the apex.
• Mechanical shaping isn’t finished