The Endo Archive

News from Endodontic Specialists of Madison, S.C.

Coronal Seal: A Clinical Update - April 15, 2012

Successful endodontic treatment requires removal of bacteria from the root canal system (1, 2) and a coronal seal to prevent bacterial recontamination (3-5). Not surprisingly, a study that compared the technical outcome of root canal treatment and the quality of the coronal seal found that the combination of a sound root canal and good coronal seal had the best clinical success while the combination of poor endodontics and poor coronal seal had the least successful outcomes.

However, this same study found that the combination of a good coronal seal and poor endodontics did better than the combination of good endodontics and poor coronal seal (6). These results imply that the quality of the coronal seal may be as or more important than the quality of the root canal. Several outcome studies show a higher success rate when teeth are restored with a crown following root canal treatment (7, 8). Teeth are not more brittle (9-11) after root canal treatment, but usually have an extensive restorative history and may be more prone to fracture due to reduced tooth structure and more limited neurological feedback (12).

Broken down on both the distal and mesial of tooth #19.

Significant distal carries history prior to root canal in tooth #2.

With this evidence in mind, we are proposing a small change to our clinical practice. When a tooth is broken down or is at increased risk of bacterial recontamination, we would like to place a composite barrier at the level of the orifice as a secondary seal below the temporary filling. The orifice barrier would not impact your ability to restore the tooth. If post space is needed to restore the tooth, no barrier would be placed in that canal. As with any changes, we would appreciate input and feedback from our referring partners.




1) Kakehashi S, Stanley HR, Fitzgerald RJ. The effects of surgical exposures of dental pulps in germ-free and conventional laboratory rats. Oral Surg Oral Med Oral Pathol 1965;20:340-9.
2) Möller AJ, Fabricius L, Dahlén G, Ohman AE, Heyden G. Influence on periapical tissues of indigenous oral bacteria and necrotic pulp tissue in monkeys. Scand J Dent Res 1981;89:475– 84.
3) Torabinejad M, Ung B, Kettering JD. In vitro bacterial penetration of coronally unsealed endodontically treated teeth. J Endod 1990;16:566-69.
4) Khayat A, Lee AJ, Torabinejad M. Human saliva penetration of coronally unsealed obturated root canals. J Endod 1993;19:458-61.
5) Alves J, Walton R, Drake D. Coronal Leakage: Endotoxin penetration from mixed bacterial communities through obturated, post-prepared root canals. J Endod 1998;24:587-91.
6) Ray HA, Trope M. Periapical status of endodontically treated teeth in relation to the technical quality of the root filling and the coronal restoration. Int Endod J 1995;28:12-8.
7) Salehrabi R, Rotstein I. Endodontic treatment outcomes in a large patient population in the USA: an epidemiological study. J Endod 2004;12:846-50.
8) Ng Y, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature-Part 2. Influence of clinical factors. Int Endod J 2008;41:6-31.
9) Papa J, Cain C, Messer HH. Moisture content of vital vs endodontically treated teeth. Endod Dent Traumatol 1994;10:91-3.
10) Reeh ES, Messer HH, Douglas WH. Reduction in stiffness as a result of endodontic and restorative procedures. J Endod 1989;15:512-6.
11) Huang TJ, Schilder H, Nathanson D. Effects of moisture content and endodontic treatment on some mechanical properties of human dentin. J Endod 1992;18:209-15.
12) Sedgley CM, Messer HH. Are endodontically treated teeth more brittle? J Endod 1992;18:332-5.