February 2006 – Mandibular Molars with Distal Marginal Ridge Cracks – What is the Prognosis?
Fractures are becoming more and more common. One of the most frequent scenarios we see in cases with mandibular second molars is the classic distal marginal ridge crack that extends to eth distal canal orifice…and deeper. For many years I used to try to save these teeth. One strategy involved trying to minimize vertical condensation forces in order to prevent propagation of the fracture down the root.
Another strategy I have seen mentioned in association with this problem involved the use of Rib-Bond placed down into the coronal aspect of the fractured endodontically filled root and then filling the access with bonded composite. This is supposed to splint the tooth from the inside. I have seen no literature to support this finding.
In this installment of case of the month, I present two cases. The first represents a tooth that showed a in Sept 2005 with such a fracture. I was very pleased with the endo fill and the tooth was promptly restored with a crown. Nevertheless over a period of approximately 6 years, the distal PDL attachment eventually broke down in the area of the fracture and a deep pocket developed. Although we note that the radiolucency associated with the distal root has healed, we see the beginnings of mesial root lucency, distal vertical periodontal breakdown with pocketing to the apex. The tooth was not salvageable.
A more recent second molar case presented with a fresh occlusal amalgam and percussive sensitivity. The restoration appeared fairly conservative, depth wise. Pulp tests were negative. An obvious distal marginal ridge crack is visible. There is even amalgam packed into the most coronal aspect of the crack.
Examination of the radiograph revealed a periradicular radiolucency and developing angular defect in the supporting distal periodontium. Placement of a gutta percha cone into the distal pocket showed it to probe about half way down the root. This, in combination with the pulpal necrosis, led me to recommend extraction rather than trying to salvage the tooth.