Treatment Outcomes and Prognostic Analysis of Root Canal-treated Posterior Cracked Teeth: The Modified Iowa Index
CE Hours: 1.0
Description: This study evaluated the treatment outcomes and prognostic factors of root canal–treated posterior cracked teeth using the Modified Iowa Index, as published in the Journal of Endodontics. The index enables structured prognostic stratification by integrating crack morphology, periodontal status, radicular crack depth, periapical conditions, occlusal risk, and definitive restoration type. Understanding survival trends and independent risk factors supports evidence-based clinical decision-making and improves long-term tooth preservation in compromised posterior cracked teeth following root canal treatment.
At the conclusion of this article, the reader will be able to:
- Explain the value of the Modified Iowa Index for assessing prognosis and predicting tooth survival in posterior cracked teeth after root canal treatment.
- Identify independent risk factors associated with endodontic failure, including Age, Probing depth ≥ 5 mm along the crack, Radicular extension ≥3 mm, Presence of periapical lesion, Multiple crack lines, Absence of occlusal splint in patients with parafunctional habits, Restoration with onlay or resin composite.
- Interpret outcome and survival patterns to guide post-endodontic treatment planning, including selection of definitive restoration and occlusal stress control to optimize long-term success.
Key:
Complete
Next
Failed
Available
LockedNorachai Wongkornchaowalit, DDS, MSc
Dr. Norachai Wongkornchaowalit graduated from the Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand, in 2008. He subsequently completed a Master of Science in Endodontics in 2011 and a Higher Graduate Diploma in Endodontics in 2012, both from Chulalongkorn University. In the same year, he also received the Thai Board Certificate in Endodontics.
From 2011 to 2015, Dr. Wongkornchaowalit served as a full-time lecturer at Chulalongkorn University and has continued as a part-time lecturer since 2015. He currently serves on the board examination committee and is the secretary of both the Thai Endodontic Association and the Thai Board of Endodontics.
He has delivered numerous lectures and hands-on courses on root canal treatment nationwide, co-authored two endodontic textbooks, and contributed to academic publications.
His clinical interests include microscope-assisted root canal therapy, management of cracked teeth, non-surgical and surgical retreatment, and post-endodontic restoration.
Taratorn Soontornkiat, DDS, MSc
Dr. Taratorn Soontornkiat is a diplomate of the Thai board of Endodontics (2000) and the American Board of endodontics (2004). She currently works in private practice and serves as a part-time faculty member in the department of Conservative Dentistry and Prosthodontics, Faculty of dentistry Srinakharinwirot University and Department of Operative Dentistry and Endodontics, faculty of Dentistry, Mahidol University, Thailand.
Dr. Soontornkiat received her Graduate Diploma in Clinical Science (Endodontics) from Mahidol University (1992). She completed her Specialty Certificate in Endodontics (1997) and MSc. (1998) from University of Minnesota School of Dentistry. She was a past president of Thai Endodontic Society of Thailand (2010-2011).
Tadkamol Krongbaramee, DDS, PhD
Dr. Tadkamol Krongbaramee is a Diplomate of the American Board of Endodontics (2024). She currently serves as a full-time faculty member in the Department of Endodontics, Faculty of Dentistry, Chiang Mai University, Thailand, and is also the owner of a private dental practice in Chiang Mai, where she provides specialty care focused on root canal treatment. Dr. Krongbaramee earned her PhD in Oral Science (2021) and Specialty Certificate in Endodontics (2023) from the University of Iowa College of Dentistry, receiving advanced training in evidence-based endodontic therapy and translational oral science research.
Attawood Lertpimonchai, DDS, MSc, PhD
Dr. Attawood Lertpimonchai is an Associate Professor in the Department of Periodontology at the Faculty of Dentistry, Chulalongkorn University in Bangkok, Thailand. He attended Chulalongkorn University where he received his D.D.S. in 2007 and his M.Sc. in Periodontics in 2011. He furthered his education at Mahidol University, earning a Ph.D. in Clinical Epidemiology and Biostatistics in 2017. Dr. Lertpimonchai has authored numerous publications in the field of periodontics and dental research, with recent work appearing in the Journal of Endodontics, Journal of Clinical Periodontology, and BMC Oral Health. His primary research interests include periodontal disease, periodontal medicine, epidemiology, and statistics.
Keith V. Krell, D.D.S., M.S., M.A.
Dr. Krell has been an endodontist for 44 years. He was a full time educator for 8 years at the University of Iowa and was in private practice in West Des Moines, Iowa for 29 years until he retired December 31,2017. In 1993, he retired from the United States Army National Guard as a lieutenant colonel after 22 years of service. He was also an adjunct clinical Professor in the department of Endodontics at the University of Iowa, College of Dentistry until July 1, 2025 completing a 50 year career with the University of Iowa. He received the University of Iowa, Distinguished Service Alumni Award Sept 26, 2025. He is a past president of the American Association of Endodontist, and also a past president of both, the American Board of Endodontics and the Foundation for Endodontics. He is a Diplomate of the American Board of Endodontics and is a both a Fellow in the American College of Dentists and in the International College of Dentists.
Dr. Krell has been married for 54 years to Diane and they have two grown children, and five grandchildren. He still has research interests in cracked teeth and vertical root fractures and has provided continuing education nationally and internationally for the past 40 years. He has played guitar for more than 50 years and has collected guitars for the past 30 years.
Disclosure:
I declare that I have no proprietary, financial, or other personal interest of any nature or kind in any product, service, course, and/or company, or in any firm beneficially associated therewith, that will be discussed or considered during the proposed presentation.