Filling materials for retreatment of failed root canals – only very low quality evidence is available from RCTs

Composite_resin_fillng_2The living part of the tooth, also known as the tooth pulp, can become irreversibly inflamed as a result of damage or bacterial infection due to tooth decay. To deal with this problem, the dentist has to drill a hole to access the inner space of the tooth or root canal system, and remove the infected tissue and toxic irritants by a combination of mechanical cleaning and irrigation. After this is done, the dentist fills the space with an inert packing material and seals the opening. This procedure is known as root canal therapy. Although results are generally good, a small number of failures do occur. This may be attributed to the complexity of the root canal system, which has many small additional pathways communicating with each other, making it difficult to completely eliminate all of the toxins and irritants. These can spread, causing the infection around the root to last indefinitely. When root canal therapy fails, a retreatment called retrograde filling is a good alternative to save the tooth. During retrograde filling the dentist cuts a flap in the gum and creates a hole in the bone to get access to the bottom tip of the root. After cutting off the tip, then thorough preparation, the apex is sealed (the apical seal) and the hole made by the dentist filled with a dental material. This sealing process is thought to be the single most important factor in achieving success in a retrograde root filling. Many materials have been developed to seal the root tip, mineral trioxide aggregate is the material of interest at present, but there is no consensus about which material is best. Continue reading