Changes in Root Canal Length Determined during Mechanical Preparation Stages and Their Relationship with the Accuracy of Root ZX II.
BACKGROUND
The aim of this study was to determine the variations in root canal length (RCL) occurring during endodontic treatment stages (initial, preflared, and concluded) and correlate them with the accuracy of Root ZX II (RZX).


METHODS
After coronal access, 26 mandibular molars had the apical foramen of the 52 mesial canals standardized (250 μm) and their respective initial RCL was recorded (RCL1 = initial) by using a clinical microscope (×16) and manual K-file instruments. By using the alginate model, sequential electronic measurements were taken with the RZX. After the initial measurement (EM1), WaveOne Primary instruments were used to prepare the cervical and middle thirds of the root canals, and then the second RCL and EM measurements (RCL2/EM2 = preflared) were obtained. Finally, mechanical preparation was concluded, and the measurement procedures were repeated to obtain the final RCL and EM measurements (RCL3/EM3 = concluded).


RESULTS
Statistically significant differences were observed in all comparisons in the RCL (P < .05). The RCL1 - RCL3 showed the highest variation (0.6 mm), with the extent of specimens reduced by up to 1.75 mm. No statistically significant differences were found in the accuracy of the RZX (P > .05); 100% precision (± 0.5 mm) was found in all stages.


CONCLUSIONS
Under the conditions of this study, the authors concluded that during endodontic treatment, the extent of the RCL was reduced, thereby jeopardizing control of the apical limit during instrumentation and/or obturation. The RZX was extremely accurate in all evaluated stages.
School of Dentistry of Sobral, Federal University of Ceará, Campus Sobral, Sobral, Ceará, Brazil. Electronic address: bcv@ufc.br.
Bruno Carvalho
BC
Vasconcelos
School of Dentistry of Sobral, Federal University of Ceará, Campus Sobral, Sobral, Ceará, Brazil.
Luzia Mesquista
LM
Bastos
School of Dentistry of Sobral, Federal University of Ceará, Campus Sobral, Sobral, Ceará, Brazil.
Ariany Souza
AS
Oliveira
Brazilian Dental Association, Taguatinga, Federal District, Brazil.
Ricardo Affonso
RA
Bernardes
Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
Marco Antonio Hungaro
MA
Duarte
School of Dentistry of Ceará, São Leopoldo Mandic University, Campus Fortaleza, Fortaleza, Ceará, Brazil.
Nilton
N
Vivacqua-Gomes
Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
Rodrigo Ricci
RR
Vivan
D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D009811:Odontometry / Q000295:instrumentation*; D018915:Root Canal Preparation / Q000295:instrumentation*; D012390:Root Canal Therapy / Q000295:instrumentation; D019227:Tooth Apex / Q000033:anatomy & histology; D014092:Tooth Root / Q000033:anatomy & histology* / Q000000981:diagnostic imaging
Electronic foramen locator; endodontic; root canal length