Happiness is a Root Canal
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Apexification: a method of inducing a calcified apical barrier or continued apical development of an incompletely formed root in which the pulp is necrotic.

Apexogenesis: physiological development and formation of the root-end. This term is frequently used to describe vital pulp therapy performed to permit the continuation of this process.

Source: American Association of Endodontists Contemporary Terminology for Endodontics, Fifth Edition 1994

Diagnosis of pulpal necrosis in the tooth with an incompletely formed apex is sometimes difficult unless a frank exposure of the pulp chamber exists.
The usual cause of endodontic involvement in a tooth with an incompletely developed root is trauma. A detailed history of any injury is of prime importance from both a diagnostic and a treatment point of view as well as documentation for dental-legal and insurance reasons.
Radiographic diagnosis of disease is complicated in these teeth because of the normal radiolucency occurring at the apex as the root matures. Comparison of root formation with that in contralateral teeth should always be considered.
The electric pulp tester usually will not provide meaningful data in teeth with incompletely formed roots. Thermal tests are more reliable for ascertaining vitality but may be complicated by the reliability of the response in the young child.
The presence of acute or chronic pain, percussion sensitivity, mobility, and any discoloration of the crown should be considered in the diagnosis.
In the tooth without a pulp exposure-if any doubt persists after all the foregoing tests have been completed-take a watch and wait approach before entering the tooth endodontically to be certain that conclusive evidence of pulpal necrosis exists. If dentin exposure is present, the tooth must be restored in such a manner as to prevent any further pulpal irritation.
In the apexification technique the canal is cleansed and sanitized in the routine endodontic manner with the use of a rubber dam. The access opening is made as usual but may require some extension, especially in the anterior teeth, to accommodate the larger-sized instruments necessary to clean the root canals.
The length of the canal is established radiographically and the canal is cleansed as thoroughly as possible. Frequent irrigation with sodium hypochlorite helps remove debris from the canal. Since the coronal half of the root canal is of smaller diameter than the apical half, root canal instruments that are smaller than the canal space must be utilized. Thus, while mechanically cleaning and shaping the canal, lean the instruments toward each surface of the tooth to contact all surfaces of the root because the canal diverges apically. Sonic and ultrasonic devices are extremely helpful in debriding the canal.
After thorough debridement the canal is dried and just barely medicated with CMCP or some other suitable intracanal medicament. It is then sealed with a temporary cement.
If symptoms persist or any signs of infection are present at a subsequent appointment, or if the canal cannot be dried, the debridement phase is repeated and the canal is medicated with a slurry of Ca(OH)2 paste and sealed.
When the tooth is free of signs and symptoms of infection, the canal is dried and filled with a stiff mix of Ca(OH)2 and CMCP. The filling procedure is usually performed without the use of local anesthetic. This is preferable if possible so the patient's response can be utilized to indicate the approach to the apical foramen.

The material should be spatulated as little as possible since spatulation decreases the working time and may cause the material to set into a hard mass before the filling procedure is completed. If this happens, the canal may contain voids and should be recleaned and the filling procedure is then repeated.
The paste may be carried into the canal with an amalgam carrier, Lentulo spiral, disposable syringe, or endodontic pressure syringe. Pluggers are helpful for packing the material to the apex. The addition of some dry Ca(OH)2 powder within the canal my means of an amalgam carrier will aid in condensing the paste of the apex. The canal should not be overfilled. The response of the patient is used as a guide in approaching the apex: however, because of differences in patient response, this method in not wholly reliable. Radiographic checks of the depth of the filling are essential to verify an adequate filling. The addition of small amounts of barium sulfate to the paste aids in radiographic interpretation without altering the response of the material.
Commercial paste of Ca(OH)2 may be use to fill the canals. In this technique, the paste is placed in the canal via the sterile needle supplied with the paste. The liquid portion of the paste is then absorbed with paper points placed into the canal. Injection and absorption of the liquid are repeated until filling of the canal is achieved. Condensation of the dried paste with pluggers is necessary to completely obliterate the canal space.
It has been reported that successful apexification can occur with an overfil of material; in fact, it has been reported that an overfill is preferable to an underfill (Camp JH: Continued apical development of pulpless permanent teeth following endodontic therapy. Master's thesis, Bloomington, 1968, Indiana University School of Dentistry.). In the event of an overfill, the material )being absorbable) is not removed from the apical tissues. The presence of an overfill rarely causes postoperative pain.
After the canal is filled, the access opening must be sealed with a permanent filling material. If the outer seal is defective, the calcium hydroxide paste is lost and recontamination of the canal will result. For this reason temporary type cements should never be used to seal the tooth after filling procedure. Composite resin or silicate cement is recommended for anterior teeth and amalgam for posterior teeth.
The usual time required to achieve apexification is 6 to 24 months (average 1 year +/- 7 months). Factors that lead to increased time are the presence of a radiolucent lesion, inter-appointment symptoms, and loss of the external seal with re-infection of the canal. During this time the patient is recalled at 3-month intervals for monitoring of the tooth.
If any signs or symptoms of re-infection or pathology occur during this phase of treatment, the canal is recleaned and refilled with the Ca(OH)2 paste. The patient is recalled until radiographic evidence of apexification has become apparent. Then the tooth is reentered and clinical verification of apexification is made by the failure of a small instrument to penetrate through the apex after removal of the Ca(OH)2 paste. If apexification is incomplete, the canal is repacked with Ca(OH)2 paste, and the periodic recall continues.

Source: Cohen S, Burns R: Pathways of the Pulp, 6th edition, pg. 660-667.