Dental Problems

Pulpectomy In Primary Teeth – Canal Cleaning and Shaping

DenturesPulpectomy is the removal of the contents of the pulp chamber and the roof in order to gain success to the root canals which are enlarged, debrided and disinfected. Pulpectomy in primary teeth -canal cleaning and shaping and different root filling materials is discussed below in this article.

Pulpectomy In Primary Teeth -Canal Cleaning and Shaping

  • Isolation:

    Use of rubber dam is essential in any endodontic procedure as it is best method of isolating the tooth from the oral cavity. It was first introduced by Barnum (1864), it is useful in providing a clean, dry and sterilizable field.

Debridement:

  • Canal cleaning and shaping is one among the most important phases of primary endodontic therapy. The main objective of the chemical -mechanical preparation of the primary tooth is debridement of the canals. Although an apical taper to the canals is desirable, it is not necessary to have an exact shape to the canals. The biomechanical preparation in the primary teeth can be said to be different enough to warrant the following considerations:

    1. Relative pulpectomy:

    This is due to the tortuous course of the canal coupled with the numerous accessory canals, the complete removal of pulp cavity in the primary teeth might be difficult often, if not it might be impossible. Thus, all such procedures are also known as partial pulpectomy procedures.

    2. Selective filling:

    Resorption in the primary teeth might have started during the treatment time. Also, all the slender roots with the thin apical ends might predispose the tooth to a root fracture in cases of excessive preparation. Thus, the procedure of selecting filling of the canals should be followed.

  • It is important to establish the working length to prevent over extension through the apical foramen, it is suggested that the working length be shortened, 2 or 3 mm short of the radiographic root length: especially in the teeth showing signs of apical root resorption.
  • Instruments should be gently curved to help negotiate canals. This helps in maintaining the original shape of the canal and this lessens the risk of perforation. Shaping of the canal and thus lessens the risk of perforation. Shaping of the canals proceeds in much the same manner as is done to receive a gutta-percha filling. The canals are enlarged several file sizes past the first file that fit snugly into the canal, with a minimum size of 30 to 35.
  • Since many of the pulpal ramification cannot be reached mechanically, copious irrigation during cleaning and shaping must be maintained. Debridement of the primary root canal is more often accomplished by chemical means than mechanical means. The use of sodium hypochlorite to digest organic debris and RC-prep to produce effervescence must play an important part in removal of the tissue from the inaccessible area of the root canal system.
  • If the inflammation is beyond the coronal pulp with only inter radicular but no periapical radiolucenc, a single visit pulpectomy is preferred. On the other hand, if the pulp is necrotic with periapical movement, involvement, filling procedure is delayed until a later time.
    After canal debridement, the canals are again copiously flushed with sodium hypochlorite and are then dried with sterile paper points: a pellet of cotton is barely moistened with camphorated parachlorophenol and sealed into the pulp chamber with temporary cement.
    At a subsequent appointment the canal is reentered. As long as the patient is free of all signs and symptoms of inflammation, the canals are again irrigated with sodium hypochlorite and dried preparatory to filling.

Filling of the primary Root canals:

Root filling materials:

Developmental, anatomic and physiologic differences between the primary and permanent teeth calls for differences in the criteria for root canal filling materials. The ideal requirements of a root-filling materials for the primary teeth are as follows:

Ideal requirements:

  • Resorb at a similar rate as the primary root.
  • Should be harmless to the periapical tissues and to the permanent tooth germ, resorb readily if pressed beyond the apex.
  • It should have a stable disinfecting power.
  • It should be inserted easily into the root canal and be removed easily if necessary.
  • Should adhere to the walls of the canal and should not shrink.
    It should not be soluble in water.
  • Be radiopaque and not discolor the tooth.

No material currently available meets all these criteria. The filling material most commonly used for primary pulp canals are Zinc Oxide – Eugenol paste, iodoform paste and calcium hydroxide.

Zinc Oxide -Eugenol Paste:

Zinc oxide -eugenol paste (ZOE) is probably the most commonly used filling material for primary teeth. Camp (1984) introduced the endodontic pressure syringe to overcome the problem of underfilling, a relatively common finding when thick mixes of ZOE are employed. Under-filling, however, is frequently clinically acceptable. Overfilling, on the other hand, may cause a mild foreign body reaction. Another disadvantage of ZOE paste is the difference between its rate of resorption and that of the tooth root.

Iodoform paste:

Several authors have reported the use of KRI paste. IT resorbs rapidly and has no undesirable effects on succedaneous teeth when used as a pulp canal medicament in abscessed primary teeth. Further, KRI paste that extrudes into the periapical tissue is rapidly replaced with a normal tissue. It is also found to have a long lasting bactericidal potential. Since iodoform paste does not set into a hard mass, it can be removed if retreatment is required. KRI was found to have a success rate of 84% as compared to ZOE, which slowed a success rate of only 65%.

A paste developed by Maisto has been used clinically for many years, and good results have been reported with its use. This paste has the same composition as the KRI paste with additions.

Calcium hydroxide:

This material is generally not used in pulp therapy for primary teeth. However, several clinical and histopathologic investigations of calcium hydroxide and iodoform mixture (Vitapex, Neo Dental Chemical Products Co. Tokyo) have been published by Fuchino and Nishino (1980). This material was found to be easy to apply and resorbs at a slightly faster rate than that of the root. It has no toxic effects on permanent successor and is radioopaque.

For these reasons, the calcium hydroxide -iodoform mixture can be considered to be a nearly ideal primary tooth filling material. Other preparation with a similar composition is available in the United Stated with the trade name of Endoflas (Sanlo Laboratories, A.A. 7523 Cali, Colombia S.A).

Chawla et al (1998) carried out a pilot study in the mandibular primary molars using calcium hydroxide paste as a root canal filling material and found it to be a success.

We have also observed almost a 100% clinical success in 10 endodontically treated primary molars which are filled with vitapex (calclium hydroxidised iodoform).

Gutta Percha:

Since gutta percha is not a resorbable material, its use is contraindicated in the primary teeth.

The above article discusses briefly about the pulpectomy in primary teeth -canal cleaning and shaping.

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