Requirements for root canal filling materials

1. It should be tacky when mixed to provide good adhesion between it and the canal wall when set.

2. It should make a hermetic seal.

3. It should be radiopaque so that it can be visual­ized in the radiograph.

4. The particles of powder should be very fine so they can mix easily with the liquid.

5. It should not shrink upon setting.

6. It should not stain tooth structure.

7. It should be bacteriostatic, or at least not encourage bacterial growth.

8. It should set slowly.

9. It should be insoluble in tissue fluids.

10. It should be tissue-tolerant, that is, nonirritating to periradicular tissue.

11. It should be soluble in a common solvent if it is necessary to remove the root canal filling.

12. It should not provoke an immune response in periradicular tissue.

13. It should be neither mutagenic non carcino­genic.

Developmental, anatomic, and physiologic differences between primary and permanent teeth call for differences in the criteria for root canal filling materials. The ideal root canal filling material for primary teeth should resorb at a similar rate as the primary root, be harmless to the periapical tissues and to the permanent tooth germ, resorb readily if pressed beyond the apex, be antiseptic, fill the root canals easily, adhere to their walls, not shrink, be easily removed if necessary, be radiopaque, and not discolor the tooth. No material currently available meets all these criteria. The filling materials most commonly used for primary pulp canals are Zinc Oxide-Eugenol Paste (ZOE), iodoform paste, and calcium hydroxide.

Zinc Oxide-Eugenol Paste. ZOE is probably the most commonly used filling material for primary teeth. But 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. Although particles of ZOE may remain in the alveolar bone for a long time, it is not certain that this has a clinically significant effect.

Iodoform Paste. Several authors have reported the use of Kri paste (Pharmachemie, Zurich), which is a mixture of iodoform, camphor, para-chlorophenol, and menthol. 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 periapical tissue is rapidly replaced with normal tissue. Sometimes the material is also resorbed inside the root canal. A paste developed by Maisto has been used clinically for many years, with good results reported. This paste has the same components as the Kri paste with the addition of zinc oxide, thymol, and lanolin.

Calcium Hydroxide. Calcium hydroxide is generally not used in pulp therapy for primary teeth. However, several clinical and histopatho­logic investigations of a calcium hydroxide and iodoform mixture (Vitapex, Neo Dental Chemical Products, Tokyo) have been published in Japan. These authors found that this material is easy to apply, resorbs at a slightly faster rate than that of the roots, has no toxic effects on the permanent successor, and is radiopaque. For these reasons, Machida considers the calcium hydroxide-iodoform mixture to be a nearly ideal primary tooth filling material.

Дата добавления: 2014-01-05