Endodontics has traditionally been founded on the principles of thorough canal cleansing and natural tooth structure preservation. However, for many decades, we were forced to focus on more operator-centric techniques (straight-line access openings, large canal preps) to facilitate new technologies as they became available. For example, coronal flaring or enlargement was a big part of protecting against early-generation nickel-titanium rotary file separation and more accurately determining working lengths with electronic apex locators.
Today, we have more modern armamentarium (smaller heat-treated NiTi files, CBCT, advanced disinfection devices, bioceramics) which allows us to focus on tooth-centric techniques with the ability to maintain more natural tooth structure for fracture resistance while still thoroughly cleansing the canals.
Minimally invasive Endodontics (MIE) involves a whole tooth approach with great effort to minimally impact dentin structure from the incisal/occlusal to the apex of the tooth. The size of the endodontic access preparations is vital since it directly affects the forces delivered to the roots. However, the PERI-CERVICAL DENTIN (PCD) structure matters the most. This is the tooth structure 4mm coronal to the alveolar bone and 4-6mm apical to the alveolar bone.1
Studies show that the PCD acts as a transfer station of forces from the coronal portion of the tooth to the roots. When the PCD is left largely intact, the PCD is more protective as it transfers the longitudinal forces down the roots.2 A smaller (MIE) access results in more natural absorption of the forces at the clinical crown level and transfers less force through the PCD. The more PCD structure that remains allows for a more stable and fracture-resistant tooth. Interestingly, the size of the access opening has a more significant impact on fracture resistance than the taper of canal preparation.3 The preservation of the clinical crown structure coupled with preserving the PCD results in a tooth that can absorb and transfer forces longitudinally down the roots with greater resistance to fracture.
As we continue to advance the ability of Endodontic treatment to save and maintain natural teeth, we must understand that the PCD is the critical area of the tooth to preserve for better fracture resistance. When the tooth is not compromised by excessive dentin removal in the coronal third, the PCD can help protect it from a fracture. We can assist in preserving the PCD with minimal coronal third canal preparations and smaller access opening designs which help by transferring less force through the PCD down the vertical length of the roots. Minimizing the amount of dentin removed during access preparation while preserving the PCD with minimally invasive instruments helps to maximize the strength and resistance to fracture of teeth regardless of the taper of the full canal preparation.
We are in a golden age of Endodontics where developments in the armamentarium, knowledge and clinical skill can help patients maintain their natural dentition for life.
Oral Health welcomes this original article.
References
- Clark D, Khademi JA. Modern Molar Endodontic Access and Directed Dentin Conservation. Dental Clin N Am. 2010;54:249-73.
- Jiang Q, Huang Y, Tu X, Li Z, He Y, Yang X. Biomechanics Properties of FIrst Maxillary Molars with Different Endodontic Cavities: A Finite Element Analysis. J Endod 2018;44:1283–1288)
- Elkholy MM, Nawar NN, Nguyen W, Saber SM, Kim HC. Impact of canal taper and access cavity design on the life span of an endodontically treated mandibular molar: A finite element analysis. J Endod 2021;47:1472–80)
About the Author
Brett E. Gilbert graduated from the University of Maryland Dental School (DDS 2001, ENDO 2003). He is a professor in the Department of Endodontics at the University of Illinois at Chicago and a Diplomate of the American Board of Endodontics. He founded Access Endo, a global education platform and the Access Endo Impact Academy. Dr. Gilbert is a co-founder of the Dental Yogi Academy. He was named a top ten young dental educator in America by the Seattle Study Club in 2017. In 2019 he was named to Academic Keys Who’s Who in Dentistry Higher Education (WWDHE). In 2020, he won the People’s Choice Award as the Top Instructor of 2020 for Endodontics by Course Karma. He is a fellow in the International College of Dentists and a contributing consultant for Oral Health Journal. Dr. Gilbert lectures nationally and internationally on clinical endodontics and wellness. He has been a partner in U.S. Endo Partners since 2020 and serves on the Clinical Advisory Board. He has a private practice, King Endodontics PLLC, limited to Endodontics in Niles, IL.
