Managing calcified canals

Introduction: 

Uncontrolled mineralization due to failure of enzyme, pyrophosphatase, reduced capillary permeability and reduced blood supply leads to calcifications.

CALCIFICATION OF THE PULP CAN OCCUR DUE TO
1. Mineralization in response to various irritants
2. Aging.

TREATMENT PLANNING
It should be monitored radiographically and treated only if an area of rarefaction or clinical symptoms develop. 
– Radiographs -Reducing the kVp and increasing the milliamperage accordingly increases the contrast and may make film interpretation easier.
– Multiple preoperative views may help the clinician locate root canals or establish the presence of additional root or canals.
– The use of buccal object rule and radiographic markers such as cotton pellet- stabilized burs/ segments of foil/ gutta percha can help determine the bucco- lingual orientation in posterior teeth. However, to help determine the labio- lingual position during the non- surgical treatment of calcified canals in anterior teeth one is usually forced to rely more on the visual aspect.
– With magnification, a world of remarkable lucid detail within the tooth becomes available, facilitating considerably more accurate,thus more conservative ,penetration through dentin.

MANAGEMENT:

An important fact to remember is that the canal space in normal root canal anatomy is always in the cross- sectional center of the root. Similarly the pulp chamber is (or was, before calcification) located in the cross sectional center of the crown.In a tooth with a calcified pulp chamber, the distance from the occlusal surface to the projected pulp chamber is measured from the preoperative periradicular film, or preferably from a bite- wing film, which maximizes accuracy. They applied the buccal object rule for the determination of calcified root
canals as follows:
After the initial access opening, the bur is left in place and three radiographs are taken:

1.Straight – on to the bucco- lingual dimension to determine the position of the head of the bur in the root canal in the mesio- distal dimension
2.Radiograph taken with a 20 degree horizontal angulation with the cone shifted distally.
3. Radiograph taken with a 20 degree horizontal angulation with the cone directed mesially.
The last two radiographs give information regarding the relation of the bur to the canal lumen in the bucco- lingual dimension.

The LN bur (Caulk/ Denstply, Tulsa, OK, USA), the Mueller bur (Brasseler, Savannah, GA, USA) and thin ultrasonic tips are especially useful for locating calcified canals. Another important instrument for orifice location is the DG-16 explorer. At this point a fine instrument, usually a No. 8 or No. 10 K –file is placed into the orifice, and an attempt is made to negotiate the canal. An alternative option is to use instruments with reduced flute, such as a Canal Pathfinder (JS Dental, Ridgefield. Conn.) or instruments with greater shaft strength such as the Pathfinder CS ( Kerr Manufacturing Co.), which are more likely to penetrate even highly calcified canals.Remove the cervical ledge or bulge. If the orifice still cannot be negotiated with a fine instrument, drill 1-2 mm into the center of the orifice with a No.2 round bur on slow speed and use the explorer to re-establish the canal orifice. When counter- sinking or troughing in
an area where an orifice is located, be sure the pulp chamber is dry. The bur rotating at a slow speed will remove whitish chips that then accumulate in the orifice. After a light stream of air is blown into the chamber, these chips appear as white spots on the dark floor of the
chamber and serve as markers for exploration or further countersinking. This approach can be used if the fourth canal of the maxillary molar or a separation of the mesio-buccal and mesiolingual canals is anticipated in mandibular second molars.Recently a combination of access refinement ultrasonic tips and magnification has revolutionized the basic concept of access cavity preparation. The uncovering of the floor of the pulp chamber can be accomplished with the help of the CPR 2D or BUC 1 tips. The pulp stones sometimes can be vibrated or teased out by the CPR 2D or BUC 1 tips; at other times, they can be planed with the help of a BUC 2 tip- a process similar to planning the root surface. Grind the floor until the dark- colored
dentine becomes visible. is of critical importance because it dictates and guides the extension of access cavity.13 Locating canals and initial penetration under the microscope is also aided by fine instruments like the Micro- Orifice Opener.

Coronal flaring in a crown- down fashion is preferred.Incremental instrumentation is achieved by creating new increments between the established widths by cutting off a portion of the file tip, thus making it slightly wider in diameter. For example, if a 1 mm segment is clipped from a size 10 file, the instrument becomes a size 12, by trimming sizes 15, 20 and 25, instruments of sizes 17, 22 and 27 respectively can be created. In extremely sclerotic canals, only 0.5
mm segments are trimmed, increasing the instrument width by 0.01mm and making a size 10 into a size 11, etc. because cutting the shaft imparts a flat tip, a metal nail file is used to smooth the end and reestablish a bevel after the removal of any segment.

Chelator preparations have been advocated frequently as adjuncts for root canal preparation, especially in narrow and calcified root canals. Apical dentin is more frequently sclerosed, and is more mineralized. The authors recommend liquid EDTAsolution be introduced into the pulp chamber (pipette, cotton pellet ) to identify the entrance to calcified canals.