Eight-Year Retrospective Study of the Critical Time Lapse between Root Canal Completion and Crown Placement: Its Influence on the Survival of Endodontically Treated Teeth.
BACKGROUND
The purpose of this study was to investigate the effects of factors associated with various coronal restorative modalities after root canal treatment (RCT) on the survival of endodontically treated teeth (ETT) and to assess the effect of time lapse between RCT and crown placement after RCT to form a tooth loss hazard model.


METHODS
Computerized analysis was performed for all patients who received posterior RCT from 2008 to 2016 in the graduate endodontic department. Data collected included dates of RCT, type of post-endodontic restoration, and time of extraction if extracted. Teeth that received crown after RCT were also divided into 2 groups: receiving crown before 4 months and after 4 months after RCT. Data were analyzed by using Kaplan-Meier log-rank test and Cox regression model (α = 0.05) by using SPPS Statistic 21.


RESULTS
Type of restoration after RCT significantly affected the survival of ETT (P = .001). ETT that received composite/amalgam buildup restorations were 2.29 times more likely to be extracted compared with ETT that received crown (hazard ratio, 2.29; confidence interval, 1.29-4.06; P = .005). Time of crown placement after RCT was also significantly correlated with survival rate of ETT (P = .001). Teeth that received crown 4 months after RCT were almost 3 times more likely to get extracted compared with teeth that received crown within 4 months of RCT (hazard ratio, 3.38; confidence interval, 1.56-6.33; P = .002).


CONCLUSIONS
Patients may benefit by maintaining their natural dentition by timely placement of crown after RCT, which otherwise may have been extracted and replaced by implant because of any delay in crown placement.
Department of Endodontics, Case School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio.
Isaac
I
Pratt
Department of Endodontics, Case School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio.
Anita
A
Aminoshariae
Department of Endodontics, Case School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio.
Thomas A
TA
Montagnese
Department of Public Health, Case School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio.
Kristin A
KA
Williams
Department of Endodontics, Case School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio. Electronic address: Nxk326@case.edu.
Navid
N
Khalighinejad
Department of Endodontics, Case School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio.
Andre
A
Mickel
D000328:Adult; D003442:Crowns; D003786:Dental Pulp Cavity; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011176:Post and Core Technique; D012189:Retrospective Studies; D012390:Root Canal Therapy / Q000379:methods*; D019553:Tooth, Nonvital / Q000628:therapy*; D016896:Treatment Outcome
Endodontically treated teeth; restoration; root canal treatment; survival analysis; survival rate