Effects of CBCT acquisition protocol and additional superimposed computerized optical impressions on the accuracy of root canal length measurements: an ex vivo study.

AIM: The purpose of the present investigation was to evaluate the accuracy of root canal length (RCL) determination according to CBCT acquisition protocol and evaluate the influence of additional superimposed computerized optical impressions. MATERIALS AND METHODS: CBCT scans with low-dose (LD) and high-definition (HD) protocols as well as computerized optical impressions of 30 extracted human molars were acquired. Sicat Endo software (Sicat) was used for CBCT RCL measurements with (LD+, HD+) and without (LD-, HD-) a superimposed optical impression. To evaluate the accuracy, absolute differences between test groups and the actual root canal length (ARCL) were calculated and statistically analyzed using the Wilcoxon rank sum test. RESULTS: Absolute differences between the ARCL and the tested measurement methods varied significantly (P < 0.05). Both higher resolution and additionally superimposed computerized optical impression improved measurement accuracy. Mean differences compared with the ARCL were 0.26 mm (HD+), 0.34 mm (HD-), 0.43 mm (LD+), and 0.66 mm (LD-). 93.4% of all measurements in the HD+ group were within the limits of ± 0.5 mm. CONCLUSION: Both resolution and superimposition of additional computerized optical impressions have a significant influence on RCL measurements using CBCT.

A critical analysis of research methods and experimental models to study working length determination and the performance of apex locators - A narrative review with recommendations for the future.

Outcome studies have repeatedly shown that the apical endpoint of root canal preparation and filling is a determinate factor for the outcome of root canal treatment. Accurate determination of root canal length enhances the efficacy of chemo-mechanical disinfection and prevents over-/under-instrumentation and over-/under-filling in relation to the canal terminus. Long and short root canal fillings are consistently reported to be associated with higher rates of post-treatment endodontic disease. Although standards for undertaking and reporting diagnostic accuracy studies are available, publications dealing with the determination of root canal length are highly heterogeneous and describe procedures inconsistently. The aim of this review is to critically assess the methodology of publications in the past three decades. The process of planning, performing and analysing working length studies are presented stepwise with suggestions to optimize research methods.

Accuracy of CBCT-based root canal length predetermination using new endodontic planning software compared to measurements performed with an electronic apex locator ex vivo.

OBJECTIVE: To evaluate the accuracy of the new endodontic planning software (3D Endo Dentsply Sirona) based on cone beam computed tomography (CBCT) to predetermine root canal lengths compared with measurements performed with an electronic apex locator (Raypex 6; VDW) ex vivo. MATERIALS AND METHODS: CBCT scans of forty extracted human maxillary (n = 20) and mandibular (n = 20) molars were taken, and root canal lengths were predetermined with the 3D Endo software using the apical foramen (AF) and the adjoining cusp as references. Root canal lengths were determined with the Raypex 6 using the same references. To evaluate the accuracy, absolute differences between both methods and the actual root canal length (gold standard) were calculated and statistically analyzed. RESULTS: Differences between lengths measured with the 3D Endo and the Raypex 6 compared with the gold standard showed no significant differences (P = 0.879). Mean differences were 0.37 mm versus 0.35 mm in the maxillary molars, and 0.30 mm versus 0.31 mm in the mandibular molars. A total of 75.8% (3D Endo) and 79.1% (Raypex 6) of all measurements were within the limits of ± 0.5 mm. Both methods showed a tendency to result in short measurements (P < 0.001). CONCLUSIONS: Within the limitations of this study, the 3D Endo software enables an accurate three-dimensional (3D) predetermination of root canal lengths.

Accuracy of working length measurement: electronic apex locator versus cone-beam computed tomography.

AIM: To compare the accuracy of working length (WL) determination using the Raypex 6(®) electronic apex locator and cone-beam computed tomography (CBCT). METHODOLOGY: A total of 150 extracted human teeth were decoronated and randomly assigned to five groups (n = 30). WL was measured with the Raypex 6(®) at both the 'constriction' and the 'apex' marks under dry conditions (group 1) or with 2.5% NaOCl, distilled water or Ultracain(®) (groups 2-4). The radiological WL (group 5) was calculated from bucco-lingual and mesio-distal CBCT sections. Differences between electronic, CBCT measurements and actual length (AL) were calculated. Positive and negative values, respectively, indicate measurements falling short or long of AL. Two-way anova and the Bonferroni and Welch tests were used to compare mean differences amongst groups. The chi-squared and Fisher's exact tests were used to compare percentages of precise, ±0.5 and ±1.0 mm of the AL measurements amongst the experimental groups. Statistical analysis was performed at α = 0.05. RESULTS: Mean differences with respect to AL ranged from 0.26 to -0.36 mm and from 0.05 to 0.18 mm, respectively, for the electronic measurements at the 'constriction' mark and 'apex' mark. CBCT measurements were an average of 0.59 mm shorter than AL. Percentages of electronic measurements falling within ±0.5 mm of the corresponding AL referred to the 'apex' mark were greater than at the 'constriction' mark, but the differences were only significant in group 4 (with Ultracain(®) ). Percentages of CBCT measurements falling within ±0.5 mm of AL (46.7%) were significantly lower than electronic measurements, regardless of the condition of the root canal. In 30-38.5% of the measurements taken at the 'apex' mark and in 3.4-13.3% of those at the 'constriction' mark, the file tip extended beyond the foramen. CONCLUSIONS: Electronic measurements were more reliable than CBCT scans for WL determination. The Raypex 6(®) was more accurate in locating the major foramen than the apical constriction under the experimental set-up.

Accuracy of Software-Based Three-Dimensional Root Canal Length Measurements Using Cone-Beam Computed Tomography.

OBJECTIVE: This study aims to evaluate the accuracy of three-dimensional root canal length measurements performed by dentists with different experience levels using a special software based on cone beam com-puted tomography (CBCT). METHODS: A CBCT scan of an artificial resin maxillary molar was used to train dentists (n=65) in using the software (3D Endo, DentsplySirona, Ballaigues, Switzerland) as part of a continuing education course. At the beginning, each participant completed a questionnaire on endodontic and CBCT experiences. After com-prehensive instructions, each participant performed an entire three-dimensional treatment plan by tracing the root canal anatomy between the apical foramen and the center of the canal orifice and simulating a straight-line access. The final root canal length was indicated after the virtual rubber stop of a simulated instrument was adapted to the adjoining cusp. To evaluate the individual accuracy in terms of trueness and precision, differences between the three-dimensional planning and the actual root canal length (ARCL) were calculated, and statistically analyzed. RESULTS: Mean absolute differences between the measurements with the 3D Endo™ software (n=260) and the ARCL were 0.30±0.22 mm. All measurements were within a limit of ±1 mm. The accuracy of root canal length measurements was significantly influenced by the type of root canal (p<0.0001). The smallest devia-tions were observed for the palatal root canal (0.18±0.13 mm), followed by the mesiobuccal (0.26±0.22 mm), the distobuccal (0.32±0.17 mm), and the second mesiobuccal root canal (0.46±0.24 mm). CONCLUSION: Within the limitations of this study, the 3D Endo software enables reproducible and accurate root canal length measurements as part of a three-dimensional endodontic treatment plan. However, mea-surements should always be clinically verified, as root canal morphology has a statistically significant influence.

A comparative evaluation of electronic and radiographic determination of root canal length in primary teeth: An in vitro study.

AIMS: The purpose of this in vitro study was to compare the root canal length determination by Electronic apex locator (EAL) (Raypex 5) and conventional radiography, and then compare them with the actual measurements obtained by direct visualization. SETTINGS AND DESIGN: This study was conducted at the Department of Pedodontics and Preventive Dentistry, Government Dental College, Thiruvananthapuram, Kerala, India. SUBJECTS AND METHODS: One hundred single rooted primary teeth extracted due to extensive caries, trauma, serial extraction or unwillingness of the parent to save the teeth were selected. The teeth were numbered and root canal length was determined using the visual, electronic and the radiographic methods. The actual, electronic and the radiographic measurements were recorded. STATISTICAL ANALYSIS USED: Data were analyzed using Intraclass correlation test and linear regression analysis. RESULTS: The accuracy of EAL and radiographic methods were 92% and 72%, respectively within + 0.5 mm. Both the electronic and conventional radiographic methods showed a high correlation and agreement (ICC intraclass correlation coefficient = 0.99 and 0.98 respectively) with the actual measurements. CONCLUSIONS: EALs proved to be more accurate in determining the root canal length than the radiographic method.

In Vivo Accuracy of Two Electronic Foramen Locators Based on Different Operation Systems

The aim of this study was to compare in vivo the accuracy of two electronic foramen locators (EFLs) based on different operation systems - Root ZX and Propex II. Ten healthy adult patients needing premolar extractions due to orthodontic reasons participated in the study, providing a sample of 17 noncarious, non-restored, vital teeth (n= 24 canals). After coronal access preparation and cervical preflaring and prior to tooth extraction, the root canal length was measured alternating the two EFLs. All measurements were performed with K-files well fitted to the canal diameter at the level that each EFL indicated the apical foramen in their display (APEX or 0.0). The last K-file were fixed in place with cyanoacrylate, the tooth was extracted, and the apical 4 mm of each root were resected to measure the distance between the file tip and the apical foramen. The mean errors based on the absolute values of discrepancies were 0.30 ± 0.29 mm (Root ZX) and 0.32 ± 0.27 mm (Propex II). Analysis by the Wilcoxon test for paired samples showed no statistically significant differences between the electronic canal measurements performed with the EFLs (p=0.587). The apical foramen was accurately located in 75% (Root ZX) and 66.7% (Propex II) of the cases, considering a ±0.5 mm error margin, with no statistically significant difference by the chi-square test. Despite having different measurement mechanisms, both EFLs were capable of locating the apical foramen with high accuracy in vivo. Under the tested clinical conditions, Root ZX and Propex II displayed similar results.

O presente estudo teve como objetivo avaliar, in vivo, a precisão de dois localizadores eletrônicos foraminais (LEFs) baseados em diferentes mecanismos de funcionamento, Root ZX e Propex II, na determinação do forame apical, sendo utilizados nos mesmos dentes. Após o acesso coronário e o pré-alargamento, e anteriormente à exodontia, os comprimentos de 24 canais radiculares foram determinados eletronicamente alternando-se os dois LEFs. As odontometrias foram realizadas até que os dispositivos apontassem o FA (APEX), utilizando-se limas tipo-K ajustadas. O último instrumento utilizado foi fixado em posição, o dente extraído e os 4,0 mm apicais de cada canal desgastados de forma a possibilitar a determinação da distância entre a ponta dos instrumentos e o forame apical. Os erros médios em função dos valores absolutos das discrepâncias foram, respectivamente, 0,30 ± 0,29 mm (Root ZX) e 0,32 ± 0,27 mm (Propex II). A análise estatística realizada por meio do teste de Wilcoxon para amostras pareadas demonstrou a semelhança entre as determinações do forame apical realizadas pelos dois LEFs (p=0,587). O comprimento radicular até o forame apical foi corretamente determinado em 75% (Root ZX) e 66,7% (Propex II) dos casos, considerando margem de ± 0,5 mm, sem diferenças estatísticas quando analisados pelo teste qui-quadrado. Os LEFs avaliados e consequentemente seus mecanismos de funcionamento, foram capazes de determinar o comprimento dos canais radiculares com precisão em condições in vivo. Nas condições do presente estudo, Root ZX e Propex II apresentaram resultados semelhantes.

Gray scale inversion in digital image for measurement of tooth length

The aim of this study was to assess the applicability of gray scale inversion in performing digital linear endodontic measurements. Standardized digital images were taken of 40 extracted human permanent single-rooted teeth with K-files size 15 placed at different lengths in the root canal, using the CDR Wireless® digital system. All images were treated with Positive, a digital tool that inverts the grayscale value. Eight radiologists measured the distance between the lower limit of the rubber stop and the tip of the file on both original and positive images. After 15 days, they repeated this procedure in 50% of the image samples. The intra- and inter-examiner agreement was analyzed by intraclass correlation test, and the comparison between the two image groups and the actual lengths by the Student's t-test (α=0.05). Intra- and inter-examiner evaluation showed high reproducibility (r>0.95) of both original and positive images. No statistically significant differences (p>0.05) were found between measurements performed on original and positive images, but both differed significantly from the actual lengths (p<0.05). Gray scale inversion has low applicability in measuring endodontic files, since it did not improve the accuracy of measurements.

O objetivo deste estudo foi avaliar a aplicabilidade da inversão da escala de cinza na realização de mensurações endodônticas lineares digitais. Quarenta dentes unirradiculares humanos extraídos foram radiografados com limas K tamanho 15 posicionadas no canal radicular em diferentes comprimentos, usando o sistema digital CDR Wireless®. Todas as imagens foram tratadas com Positive, uma ferramenta digital que inverte os valores da escala de cinza. Oito radiologistas mediram a distância entre o limite inferior do stop de borracha e a ponta da lima endodôntica nas imagens originais e positivas. Após quinze dias, eles repetiram esse procedimento em 50% da amostra. A concordância intra- e interobservador foi analisada pelo teste de correlação intraclasse e a comparação entre os dois grupos de imagem e os valores reais, pelo teste t-Student (α=0,05). A análise intra- e interobservador apresentou elevada reprodutibilidade (r>0,95) das imagens original e Positive. Não foi encontrada diferença (p>0,05) entre as medidas realizadas nas imagens original e positiva, mas ambas diferiram dos valores reais (p<0,05). A inversão da escala de cinza tem baixa aplicabilidade na realização de mensuração endodôntica, considerando que as medidas não se apresentaram mais acuradas.