Exploring Technological Progress in Three-Dimensional Imaging for Root Canal Treatments: A Systematic Review

Abstract

Introduction and aims

Root canal therapy is a crucial aspect of endodontic treatment aimed at preserving natural dentition. Over the years, advancements in three-dimensional (3D) technology have revolutionized diagnosis and treatment planning. Different 3D technologies are used in dental care, such as cone-beam computed tomography (CBCT), which ensures 3D slice visualization, root canal microanatomy, and dynamic navigation throughout the pulp cavity. By exploring the latest technological progress in this field, we seek to understand how these innovations are enhancing precision, efficiency, and patient outcomes, shedding light on the benefits and potential impact of 3D imaging in improving root canal procedures.

Methods

Literature was searched from different databases, including PubMed, ScienceDirect, The Cochrane Library, Scopus, and Google Scholar. Inclusion criteria involved studies on 3D technology in root canal therapy with comparison groups, including RCTs and non-RCTs. Excluded studies lacked 3D imaging advancements, a control group, or were review articles or case studies. Quality assessment utilized QUIN for in vitro studies and ROBINS-I for non-RCTs to evaluate the studies' validity.

Results

According to the PRISMA guidelines, among 5015 initial articles, 16 were included. CBCT was the most used 3D imaging technique for root imaging followed by micro-computed tomography (MCT) and limited CBCT (LCBCT) imaging methods. 2D radiographs and 2D histological methods and clearing techniques were the most common comparative modalities. Overall, 3D imaging streamlined dental treatment as clinicians could visualize much clearer and higher-quality images. Different resolutions and voxel sizes were applied to improve imaging quality.

Conclusion

Three-dimensional imaging, especially CBCT, improves root canal treatments by providing superior image quality. CBCT outperforms other techniques like MCT and LCBCT, enhancing clarity. Varying resolutions and voxel sizes optimize the effectiveness of 3D imaging in root canal therapy.

Clinical relevance

The advancements in 3D imaging technology, particularly CBCT, have significantly enhanced the diagnosis and treatment planning for root canal therapy. CBCT provides detailed insights into intricate root canal anatomy, improving diagnostic accuracy.

Introduction

Root canal treatment (RCT) is a very common procedure used in dentistry, with 55.7% of the global population undergoing RCT.¹ Moreover, Europeans showed the highest prevalence, with 59.6% having at least one RCT.¹ There can be deviations from the usual shape during tooth formation, and several anatomical variations can occur in each tooth type, such as the number of roots and their canals.² Successful outcomes of RCT depend on appropriate access to the cavity and its shaping, cleaning, and root-filling techniques.³ Knowledge of root canal anatomy is the most fundamental aspect for this purpose. Over the past decades, various techniques have been used to extensively investigate teeth' internal and external anatomy.

The pitfalls of two-dimensional (2D) radiographs in endodontics are well-established.^4,5 For diagnosis, 2D radiographs may have specific limitations in identifying all root canals, including blocked canals, and limited accuracy in determining the canal type.^6,7 Moreover, fracture or crack detection is challenging when 2D radiographs are used, mainly when the fracture or crack lines are in the radiation beam direction.⁸ Furthermore, periapical radiographs are conventionally utilized for the outcome assessment of root canal treatment, and no observation of periapical radiolucency is considered a healthy tooth.⁹ The non-precision and inaccuracy of cavity assessment may lead to several intraoperative complications, which can impair RCT, and ultimately, tooth survival may be at stake.¹⁰ Therefore, advanced techniques are paramount for the accurate diagnosis and treatment assessment of root canal therapy.

Recently, three-dimensional (3D) technology has had an outstanding impact on our understanding of the root canal.11, 12, 13 The transformation of real goals into mathematical models with the assistance of computer logic expressions is considered a 3D reconstruction technology widely used in dentistry.^14,15 Three-dimensional imaging is useful in displaying cone beam computed tomography (CBCT) data for planning endodontic treatment, and it allows dentists to view the tooth with more precision and better understanding than conventional 2D radiography.¹⁶ For this purpose, different 3D technologies are used in dental care, such as CBCT, which ensures 3D slice visualization, root canal microanatomy, and dynamic navigation throughout the pulp cavity.¹⁷ Moreover, other CT types have been used to diagnose root canal anatomy, including spiral CT, peripheral quantitative CT, and micro-CT.^18,19 Similarly, a 3D dynamic navigation system (3D-DNS) can be used successfully for root resection and investigation of the viability of root-end cavity preparation and filling.²⁰ Numerous in vitro studies have reported DNS's accuracy and efficiency in detecting the calcified canals' location.²¹ In addition to C-shaped canal detection, 3D CBCT imaging has several other advantages, including identifying anomalous anterior teeth and additional root canal location during treatment.²² Moreover, CBCT provides high-quality images with a better spatial resolution than conventional radiography.²³

Advancements in 3D imaging technology have significantly revolutionized RCT by providing clinicians with enhanced diagnostic capabilities and precision in treatment planning. Moreover, comprehensive assessment facilitated by 3D imaging enables clinicians to formulate tailored treatment strategies, thereby optimizing therapeutic outcomes and minimizing procedural risks. Additionally, this systematic review provides evidence that 3D imaging is pivotal in enhancing clinical efficacy and patient satisfaction. Furthermore, evidence synthesis underscores the effectiveness of integrating 3D imaging technology into routine endodontic practice, as it diminishes the need for retreatments and fosters a more streamlined workflow.

Studies utilizing micro‐computed tomography (micro‐CT) and cone beam computed tomography (CBCT) have revolutionized the understanding of root canal anatomy.²⁴ This technology offers a comprehensive view of root canal aberrations, including number, form, and curvature, surpassing the limitations of traditional two-dimensional imaging.²⁵ The accuracy and potential of 3D imaging techniques, such as high-resolution tomography, have been highlighted in evaluating root canal geometry.²⁶ The use of CBCT in conjunction with 3D modelling has facilitated the evaluation of anomalous pulp canal configurations, enhancing the precision of endodontic procedures.²⁷ Furthermore, advancements in guided endodontics, supported by CT imaging and 3D printing, have enabled precise localization of root canals, leading to more predictable treatment outcomes.²⁸ The integration of CBCT and 3D printing technology has allowed for inlay-guided endodontics, enhancing navigation during dental procedures.²⁹ Overall, the application of 3D imaging techniques in root canal treatments has significantly improved the understanding of root canal morphology, aiding in diagnosis, treatment planning, and procedural precision.

In this study, we aim to investigate the ongoing improvements in 3D imaging in root canal procedures. Examining the recent technological development of 3D imaging in root canal procedures will help us understand the increased level of precision and efficiency and improve patient outcomes with these innovations. This exploration will help us understand the potential of 3D imaging to enhance the root canal procedure.

Materials and methods

Study design and ethical aspects

Preferred Reporting for Systematic Reviews and Meta-analysis (PRISMA) protocols were followed for better reproducibility and transparency in the literature search process to perform this study.³⁰ The protocol for this systematic review was registered with the International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) (registration number: 202430037).

Search strategy

An advanced search strategy was developed using different databases, including PubMed, ScienceDirect, Scopus, Cochrane Library, and Google Scholar, from January 2003 to February 2024. Different keywords and Medical subject headings (MeSH) were used. The full search strategy used to search different databases is detailed in Supplementary Table 1.

Inclusion criteria

Studies were selected on the basis of PICO guidelines: P = Population (who underwent for RCT), I = Intervention (3D modality used for the diagnosis), C = Control (Conventional or other modality used for comparison), O = Outcomes (in terms of accuracy, precision or advancement). In addition, there were other inclusion criteria set for studies to be included in the present study: studies that evaluated 3D technology for the diagnosis or assessment of root canal therapy, studies with defined comparison groups, randomized controlled trials (RCTs), and non-RCTs (retrospective, prospective, comparative studies), and published in English after 2003.

Exclusion criteria

Certain exclusion criteria were set for the studies: studies without any advancement in 3D imaging and performed without a comparative control group, reviews (systematic, meta-analysis, scoping, narrative, literature reviews), editorials, letters, commentary, opinion papers, conference papers, case studies, or animal studies published before 2003.

Study selection

Two reviewers, RS and SV, selected the research articles. They screened the titles and abstracts of each article based on the eligibility criteria for inclusion. After removing duplicates, they performed a full-text screening. Articles that satisfied the inclusion criteria were included in the study. In case of any disagreement between the reviewers, a third reviewer, SB, was consulted, and the issues were resolved through detailed discussions.

Data extraction

Microsoft Excel was used for data extraction. The included variables were study characteristics (study ID, country, study design, sample size, age, gender, and clinical conditions), intervention (3D imaging technology) characteristics (type of 3D imaging technology used, specific features of 3D modality, software used, capabilities of the imaging technology, and any technological advancements or modifications over time), and types of root canal procedures (clinical indications for root canal therapy and outcomes related to the use of 3D imaging in planning and performing root canal procedures). In addition, data regarding root canal anatomy including visualization of root canal anatomy using 3D imaging, detection of complex root canal morphology, role of 3D imaging in identifying and treating anatomical variations. Furthermore, root dimension measurements were recorded including accuracy and precision, comparison with traditional methods of measuring root dimensions, implications for treatment success and prognosis. Finally, clinical outcomes (clinical outcomes associated with the use of 3D imaging in root canal therapy, and success rates). Additionally, advancements in 3D imaging including innovations or improvements in 3D imaging technology, impact on diagnostic accuracy, treatment planning, and treatment outcomes.

Quality assessment

The QUIN assessment tool was utilized to assess the quality of the in vitro studies. Each study was evaluated according to 12 items and rated as yes (1-2 points), no (0 points), or not applicable.³¹ Each research paper was graded according to the point responses. Scores of <50% were considered a high risk of bias, 50%-70% were a medium risk of bias, and >70% were a low risk of bias.³¹ For non-RCTs, Risk of Bias (RoB) for Non-randomized Studies- Interventions (ROBINS-I) was utilized, and assessment was performed in seven domains: confounding, selection of participants, intervention classification, deviation, missing outcome data, outcome measurement, and reporting outcomes.³²

Statistical analysis

For systematic analysis, Microsoft Excel was used to organize the extracted data and construct tables and graphs.

Results

Literature search

Databases such as PubMed, ScienceDirect, Cochrane Library, Scopus, and Google Scholar were searched for relevant literature. In the identification phase of PRISMA, 5015 articles were extracted, and 566 duplicates were identified using Endnote X9 referencing software, after which duplicates were removed. In the screening phase, 4449 articles were screened to select the most appropriate articles for full-text assessment. During this process, 4363 articles were excluded because they were considered irrelevant, and some were reviews, as indicated in Figure 1. In the eligibility phase, 86 articles were assessed using strict eligibility criteria for final selection. Among the 86 articles, 70 were excluded for various reasons (Figure 1). Finally, 16 articles were included in this systematic review.

Fig. 1.

PRISMA flowchart illustrates the selection process for the included studies. General and intervention characteristics.

Most studies have been conducted in the USA,33, 34, 35, 36 followed by China,37, 38, 39 Iran,^40,41 Sweden,⁴² Japan,⁴³ France,⁴⁴ Hungary,⁴⁵ South Korea,⁴⁶ Turkey,⁴⁷ and Brazil.⁴⁸ Most studies were published in 2018,^40,41,47 followed by 2007,^42,43 2014,^36,46 and 2017.^35,37 Most studies followed in vitro, while only four studies followed comparative study designs,^38,42,45,46 as indicated in Table 1. Most of the studies used extracted teeth; thus, they did not mention the number of patients and age, while a few studies mentioned participant numbers,^37,39,43 with a minimum of 135 participants⁴³ and 760 as the maximum number of participants.³⁹ A total of 2556 teeth were used in the included studies, with a minimum of nine teeth⁴⁴ and a maximum of 1520 teeth³⁹ and most of the teeth were mandibular molars and premolars (Table 1). CBCT was the most utilized 3D modality for imaging roots for various purposes, followed by micro-computed tomography (MCT)^45,46 and limited cone beam computed tomography (LCBCT).^37,42 Other techniques, including traditional 2D radiographs, histological comparisons, and clearing techniques in which decalcification of the teeth is done with nitric acid, dehydration with alcohol and clearing with methyl salicylates to visualize the fine details of root canal morphology, were identified as control or competitor modalities, and other 3D imaging techniques, such as MCT, were also utilized (Table 1). The specific features of the 3D imaging techniques and software used for viewing the images are listed in Table 1. Overall, 3D imaging techniques positively impact dentists' performance, as these modalities provide clear and better-quality images. Different resolutions (high and low) and voxel sizes were used to obtain improved outcomes (Table 1).

Table 1.

General and intervention characteristics of the included studies.

Study characteristics								Intervention (3D imaging technology) characteristics
Study ID	Country	Study design	Sample size	Age	Gender (M: F)	No. of teeth/type	Clinical conditions	Type of 3D imaging technology used	Control/competitor	Specific features 3D	Software used	Capabilities of the imaging technology	Any technological advancements or modifications over time
Soğur et al., 200742	Sweden	Comparative	NR	NR	NR	17/Mandibular incisor teeth	NR	LCBCT	F-speed film and Digora Optime (image plate system)	Accu-I-Tomo (3DX) kV(80) and mA (1.5) with 3.1 mm Al equivalent filtration and 17.5 s the exposure time	NR	The image was captured using a solid-state sensor	Accu-I-Tomo CB unit (later version), an image intensifier tube, produces images with more noise than flat panel detectors
Tantanapornkul et al., 200743	Japan	Prospective	135	33	50:.85	145/Mandibular and third molar	Mandibular canal and mandibular third molars (impacted)	CBCT	Panoramic	3DX imaging area (a cylinder with a height of 29 mm (240 voxels) and a 38 mm (320 voxels)	3DX	After scanning, contiguous sectional images in 3D	Contain a minute voxel (isotropic cube) with a side of approximately. 0.12 mm and can provide images (3D) with high-resolution
Matherne et al., 200834	USA	In-vitro	NR	NR	NR	72	Possessing multiple RCS	CBCT	CCD and PSP	The CBCT unit used a grayscale (12 bits) with a 0.4 mm voxel size	NR	NR	NR
Michetti et al., 201044	France	In-vitro	NR	NR	NR	9	NR	CBCT	Histologic sections	The Kodak 9000 3D (60 kV and 6.3 mA), FOV, 50 37 mm, a volume with a spatial resolution of 76 mm (isotropic voxel) and a contrast resolution (14 bits)	J imaging	Complete root canal anatomy	NR
Benyó et al., 201245	Hungary	Comparative	NR	NR	NR	25	NR	MCT	CBCT	High resolution (1500–3000 dpi)	NR	Medial axis of the root canal	NR
Bechara et al., 201333	USA	In-vitro	NR	NR	NR	66 teeth	Fractures	CBCT	PSP	A resolution (12803-1024 pixels) and a screen size (48.26 cm)	OnDemand 3D™	Detect small FOV	NR
Lee et al., 201446	S. Korea	Comparative	NR	31-69	NR	18/ Maxillary first molar	Single canal, advanced caries	MCT	2D TS-MinIP and combination with 3D	NR	OnDemand3D	Can identify fine structures	NR
Fernandes et al., 201436	USA	in-vitro	NR	NR	NR	40/ Mandibular incisors	NR	CBCT	Digital PA	Kodak 9000 3D, Veraviewepocs 3De, NewTom 5G	CTan	Root canals and internal patterns	Kodak (0.076 mm), Veraviewepocs (0.125 mm), NewTom (0.075 mm)
Ordinola-Zapata et al., 201735	USA	In-vitro	NR	Unknown	Unknown	32/ Mandibular first molars	Unknown	CBCT	MCT and clearing techniques	ProMax 3Ds (12 mA, 90 kVp, FOV 4 9 5 cm, voxel size 0.15 mm) and Pax-i 3D (10 mA, 75 kVp, FOV 5 9 5 cm, 0.12 mm voxels)	NR	Better image quality	NR
Zhang et al., 201638	China	Comparative	NR	NR	NR	143/Mandibular first premolars	NR	CBCT	MCT	85 kV and 21 mA, exposure time (2–5 s), voxel size (125 μm)	NR	Accuracy	NR
Song et al., 201737	China	In-vivo	268	40.1	115:153	323	NR	LCBCT	PA	3D Accuitomo XYZ Slice View Tomograph voxel size (0.08 mm or 0.125 mm) and FOV (434 or 63 6 cm)	i-Dixel, one-volume viewer 1.5.0	NR	NR
Kajan et al., 201840	Iran	In-vitro	NR	NR	NR	80 teeth	NR	CBCT	Tooth clearing	NewTom (110 kV, 0.5 mA, and 2.04 mA; FOV (0.200-0.240 mm)	NNT	Better accuracy	NR
Koç et al., 201847	Turkey	Ex vivo study	NR	NR	NR	40/Mandibular molars	Endodontic complications	CBCT	PA	ProMax® 3D (3 different voxel sizes (0.075, 0.1 and 0.2 mm) at 96 kVp, 1 mA with a 55 × 50 mm FOV and exposure times of 12 and 15 s	NR	NR	NR
Shokri at al., 201841	Iran	Comparative	NR	NR	NR	72/Mandibular molars	NR	CBCT high resolution	CBCT low resolution	Cranex 3D and NewTom 3G (110 kV, 0.61 mA, 3.6 s, FOV (6-inch), and a voxel size (180-210 µm) μm	NR	Provides accuracy	NR
Caetano et al., 202148	Brazil	Ex vivo study	NR	NR	NR	45/Premolars	Root fractures	CBCT Kodak 9000 3D	CBCT (Orthopantomography 300 and PreXion 3D	Kodak 9000 3D (FOV 5 × 3.7 cm, Voxel 0.076 mm, kV 70, mA 10, Exposure type Pulsed, Acquisition time 10.8; OP300 (FOV 6 × 4 cm, Voxel 0.085 mm, kV 90, mA 10, Exposure type Pulsed, Acquisition time 6.1 s; PreXion 3D FOV 1 × 5.1 cm, Voxel 0.1 mm, kV 90, mA 4, Exposure type Continuous, Acquisition time 37 s	InVivo and e-Vol DX	Provides accurate dimensions	Three different devices with two different systems were used
Zhang et al., 202339	China	In-vitro	760	32.2	343:417	1520/Mandibular first premolars	Fracture, resorption and calcification	CBCT	MCT	Newtom VGi (110 kV, 3 mA, 150 × 150 mm FOV, and 250 μm3 voxel size.	NNT Viewer	NR	NR

Abbreviations: LCBCT = Limited Cone Beam Computed Tomography, NR = Not Reported, RCS = Root Canal System, CCD = Charged Coupled Device, PSP = Photostimulable Phosphor plate; FOV = Field of View, 3D = Three Dimensional; MCT = Micro-computed tomography; PA = Periapical.

3D imaging impact on root canal treatment parameters

Overall, root canal anatomy^44,46 is the main reason for performing imaging, which may be used to detect root fractures,^33,48 bifurcations,⁴⁵ voids, and over-extensions³⁷ as clinical indications for root canal therapy. Some studies have focused on confirming the proper repositioning of root canal fillings,⁴² predicting neurovascular bundle exposure during extractions,⁴³ identifying root canal configurations,³⁵ detecting fractures,^33,48 and evaluating root canal morphology.^36,46 The different components of the root canal system were identified using 3D imaging techniques (Table 2). Moreover, these techniques are helpful in the detection of complex root canal morphology, such as calcification, fractures, root canal obturation, furcation area, strip or root perforations, and C-shaped root canal systems.^{33,37,38,40,41,46,48} 3D imaging techniques, including CBCT and MCT, were accurate, except for a few studies that reported that other techniques, such as PSP³³ and the combination of 2D and 3D techniques,⁴⁶ were also accurate. A single study reported that LCBCT was not as accurate as PSP and film radiographs,⁴² as shown in Table 2.

Table 2.

Impact of 3D imaging on root canal treatment parameters.

Study ID	Types of root canal procedures		Root canal anatomy			Root dimension measurements
	Clinical indications for root canal therapy	Outcomes related to the use of 3D imaging in planning and performing root canal procedures	Visualization of root canal anatomy using 3D imaging	Detection of complex root canal morphology	Role of 3D imaging in identifying and treating anatomical variations	Accuracy and precision of intervention	Comparison with traditional methods of measuring root dimensions	Implications for treatment success and prognosis
Soğur et al., 200742	Root canal fillings due to cavities	Confirmation of the proper repositioning and apical pathosis absence.	Homogeneity and the length of root fillings	NR	Provides better image quality	Not accurate	NR	Inferior compared to other imaging techniques
Tantanapornkul et al., 200743	Inferior alveolar neurovascular bundle presence or absence of exposure at the time of extraction	Neurovascular bundle exposure following impacted mandibular third molar extraction prediction	Inferior alveolar neurovascular bundle	NR	Better accuracy	More accurate	CBCT had a significantly superior sensitivity and specificity to panoramic	Superior compared to panoramic
Matherne et al., 200834	NA	Number of RCS per tooth	RCS	NR	Better success rate	Accurate	CBCT had better outcomes than CCD and PSP	Superior compared CCD and PSP
Michetti et al., 201044	Root canal anatomy for fillings	Root canal lumen and Feret's diameter was measured	Area and diameter	NR	Comparable outcomes with histological study	Accurate	Histological sections	Reliable
Benyó et al., 201245	Root canal bifurcations	Root canal medline, using a fuzzy chain relation and 3D curve skeletons	Medline axis detection	NR	Automatic detection	Both were accurate	NR	Accurate and reliable
Bechara et al., 201333	Fractures	Detection of fractures	Root fractures	Root fractures	It can be helpful in the identification of root fractures	Both were accurate	NR	Both were accurate and successfully detected fractures
Lee et al., 201446	Root canal structure for fillings	Detailed root canal morphology	Delicate anatomic structures (accessory canals, loops, and intercanal communications)	Calcified	Accuracy of RCS	Combines 2D and 3D was more accurate	NR	Combined more successful
Fernandes et al., 201436	Type I, II, and III	Root canal structure	NR	NR	It can be helpful in the identification of oval canals	The high degree of accuracy in all methods	NR	Both can be successful
Ordinola-Zapata et al., 201735	Type I and II	Root canal configuration	Root canal configuration	NR	NR	MCT was accurate	A significant (p<0.05) difference between the test methods and the MCT	MCT had more success
Zhang et al., 201638	Types I, III, V, and VII. Additional types including type 1–3, type 1-2-3, and type 1-3-2, classified as type IX	NR	Root canal configuration	NR	No difference	Accuracy needs to be improved	Root canal morphology	MCT had more success
Song et al., 201737	Voids and overextension	259/323 roots had voids	NR	Root canal obturation	Both techniques underestimated the RCO's overextension	NR	NR	NR
Kajan et al., 201840	NR	NR	Roots (85%) were correctly demonstrated; however, the root canal forms were not appropriately visualized in 15% of roots	RCS	Provides better root canal morphology	CBCT had better accuracy	The number and forms of root canal	CBCT had more successful
Koç et al., 201847	Dry mandible (Mandibular molar sockets) covered with 2 cm red wax	NR	Curves	NR	NR	Can be accurate	CBCT can be used as an adjunct to intraoral radiographs	Successful when using adjunct
Shokri at al., 201841	NR	NR	Axial, coronal, and sagittal planes	Furcation area, strip or root perforations	NR	The high resolution had high accuracy	NR	NR
Caetano et al., 202148	Root fractures	Fractures	NR	Vertical root fractures	NR	OP300 and PreXion had accuracy	NR	NR
Zhang et al., 202339	Root canal (C-shaped)	NR	Connecting and accessory canals, apical and accessory foramina	Radicular groove and canal system (C-shaped)	C2 (51.5%) showed the highest proportion and was distributed mainly in the middle and apical regions. C3 showed a 38.7% configuration and was distributed primarily in the apical regions.	Both were accurate	NR	NR

Abbreviations: NR = Not Reported, CCD = Charged Coupled Device, PSP = Photostimulable Phosphor plate; RCS = Root Canal System, LCBCT = Limited Cone Beam Computed Tomography, CBCT = Cone Beam Computed Tomography.

Clinical outcomes and advancements in 3D imaging

Findings from multiple studies revealed varying outcomes regarding the clinical effectiveness and advancements of 3D imaging in root canal procedures. Digora images showed superiority,⁴² while CBCT exhibited high sensitivity, specificity, and outperformed panoramic images.^43,48 Michetti, Maret⁴⁴ highlighted the reliability of area and diameter measurements using CBCT. In contrast, one study suggested that panoramic radiographs were better than CBCT in detecting voids and overextensions.³⁷ Furthermore, there may be improvements in the detection of simulated endodontic complications.⁴⁷ Despite differing results, MCT and CBCT showed similar overall success rates, with CBCT often excelling in diagnostic accuracy and treatment planning. However, continuous refinement and innovation in 3D imaging are necessary to overcome specific challenges and enhance endodontic outcomes (Table 3).

Table 3.

Clinical outcomes and advancements in 3D imaging.

Study ID	Clinical outcomes		Advancements in 3D imaging
	Clinical outcomes	Success rate	Innovations or improvements	Impact on diagnostic accuracy	Treatment planning	Treatment outcomes
Soğur et al., 200742	Digora images were found significantly (P < .05) superior, followed by F-speed films and LCBCT images.	LCBCT and F-speed films were Inferior and had a low success rate	NR	Inferior	NR	NR
Tantanapornkul et al., 200743	CBCT had 93% sensitivity and 77% specificity while, for panoramic images, that was 70% and 63%, respectively	93%	NR	Superior	NR	NR
Matherne et al., 200834	76%-84% of RCSs with CCD and PSP compared with the RCS number identified by the CBCT	High	NR	Superior	NR	NR
Michetti et al., 201044	Area = 0.928; Diameter = 0.890	Reliable	The performance of the 9000 3D was high because it shows the complexity of RCS	Stronger correlation between CBCT and histological sections	Positive	Positive
Benyó et al., 201245	Both had comparable outcomes	MCT (92%), CBCT (91.7%)	NR	Both had a high success rate	The algorithms proved to be accurate for therapy planning (endodontic)	Efficiently validated the image processing systems and corresponding image processing methods to assist interventions
Bechara et al., 201333	Small FOV images had significantly (P < .05) higher sensitivity and accuracy for detecting RFs than PSP plates and large FOV images	Same	NR	Both had a comparable impact	Clinically, when RF is observed on a PSP plate radiograph, it will be unnecessary to perform a CBCT scan.	NR
Lee et al., 201446	MCT showed detailed configurations and numerous delicate structures	NR	Innovative tool for the scanning tooth anatomy without damaging tooth structure	Combines more accurate	Canals can be classified, which can be helpful in planning	NR
Fernandes et al., 201436	CBCT imaging was more accurate for type I than PA radiography. Type Ia (oval canals), there was a significant (P < .05) difference between PA radiography and CBCT	Imaging modalities used in intervention and control groups had a comparable success rate	All CBCT devices showed improved accuracy	Both had a comparable impact	Identification of oval canals (Type Ia) was improved only with the NewTom CBCT device.	NR
Ordinola-Zapata et al., 201735	The clearing method and CBCT were significantly (P < .05) less accurate than MCT	MCT had a better success rate	NR	CBCT had less accuracy than MCT	NR	NR
Zhang et al., 201638	There were no significant (P < .05) differences between the two modalities (CBCT and MCT) for the detection of root canal configurations	Imaging modalities used in intervention and control groups had a comparable success rate	NR	Both 3D techniques were accurate	Both accurate	NR
Song et al., 201737	The PR was superior to those of CBCT in detecting voids and overextensions (P < .05)	For overextension, sensitivity was better; however, for void, it was poor	Overestimated or underestimated	NR	NR	CBCT was not suitable for evaluating the quality of RCOs.
Kajan et al., 201840	CBCT detected 92.1% of the number of root canals and 85% of the form of the root canals	CBCT had a high success rate	NR	Improved	Application of this technique could result in more successful endodontic treatment.	NR
Koç et al., 201847	In Group 1 (instrument separation), intraoral images yielded the highest Az values, while CBCT (0.2 mm voxel size) had the lowest. Group 2 (strip perforation) had the highest Az values overall, with CBCT images outperforming intraoral images significantly. In Group 3 (underfilling), CBCT images showed higher Az values compared to intraoral images, though without statistical significance (P > .05). In Group 4 (overfilling), CBCT images had significantly (P < .05) higher Az values than digital intraoral images for observers 1 and 2	Intervention group had a comparable success rate	Need improvement	It had an impact when used as an adjunct	It can be helpful in the detection of complications	NR
Shokri at al., 201841	In strip perforations, there was 75% and 83% accuracy for low- and high-resolution modes for NewTom 3G; for Cranex 3D, it was 67% and 69%. In root perforations, there was 79% and 83% accuracy for low- and high-resolution modes for NewTom 3G and 56% and 73% for Cranex 3D	Imaging modalities used in intervention and control groups had a comparable success rate	Improved	When used in a high-resolution	NR	NR
Caetano et al., 202148	PreXion 3D, using InVivo (0.96) or e-Vol DX (0.92), showed the highest accuracy	PreXion 3D presented 96% accuracy, 94% sensitivity, and 98% specificity.	PreXion 3D had superior performance	High accuracy for PreXion 3D	NR	NR
Zhang et al., 202339	The most common type was C2, while in the 3D classification, the predominant type was S. Accessory canals were present in 36.4% of samples, primarily located in the middle and apical regions. Additionally, 42.4% of samples exhibited 1-3 variable connecting canals, and 40.9% had only one apical foramen	Both MCT and CBCT groups had a success rate	Both techniques (MCT and CBT) had superior performance	Both MCT and CBT had accuracy	NR	NR

Abbreviations: NR = Not Reported, CCD = Charged Coupled Device, PSP = Photostimulable Phosphor plate; RCS = Root Canal System, LCBCT = Limited Cone Beam Computed Tomography, CBCT = Cone Beam Computed Tomography.

Quality assessment

In-vitro studies

There were seven in vitro studies, and most of the studies had a low risk of bias (>70% score), while three of the studies had a medium risk of bias (50%-70% scores). Two domains did not apply to this study: sample size calculation and outcome assessor details. However, most studies had low scores in sampling technique explanation, randomization, and binding (Table 4).

Table 4.

Quality assessment of included in vitro studies.

Non-RCTs

Non-RCTs were assessed for bias using the ROBINS-I quality assessment tool, and most studies were of good quality as they had a low RoB in the quality assessment domains. However, one study had a severe risk of bias in participant selection.⁴⁵ One study had a moderate risk of bias in the domain of confounding and participant selection.⁴⁶ Moreover, most studies had no information on confounding factors or the selection of participant domains (Figure 2).

Fig. 2.

Quality assessment of non-RCTs.

Discussion

Radiographic imaging is the most essential and necessary element for diagnosing and treating endodontic patients.⁴⁹ With technological advancements, numerous imaging modalities have been used in dentistry to enhance diagnostic ability and treatment outcomes.^50,51 In endodontics, the importance of 3D imaging technologies has been highlighted over the last decade and has played an increasingly important role in diagnosing root canal anatomy.¹⁸ Therefore, the present systematic review highlighted the technological Progress in 3D Imaging for Root Canal Treatments.

The study identifies three primary types of 3D technology: Cone Beam Computed Tomography (CBCT), Limited Field of View Cone Beam Computed Tomography (LCBCT), and Microcomputed Tomography (MCT). CBCT stands out as the most commonly employed imaging technique for diagnosing and treating root canals, with 44 out of 47 studies utilizing this method.^52,52 This preference for CBCT can be attributed to several factors. CBCT can be used at low and high resolutions, which provides detailed insight into the complex root canal anatomy, such as root fusion, multiple roots, and accessory canals, which can be missed or misdiagnosed by conventional radiographs,⁵³ resulting in better, enhanced, and accurate diagnosis and treatment planning. Moreover, its fast-scanning time makes it a practical choice in most clinical settings. Our findings are consistent with another study that revealed a high prevalence of single canals in maxillary incisors, variations in root configurations in maxillary first molars, and diverse anatomical distributions in mandibular molars (C-shaped canals) using CBCT.⁵⁴ Likewise, 2 canals were found in mandibular central incisors (10.9%), lateral incisors (25.5%), and 18.2% of mandibular incisors by utilizing CBCT.⁵⁵ Furthermore, accessory canal number detection, obliterations, and ramifications in the root canal and fractures, CBCT showed significant (P < .005) and better outcomes compared to intraoral periapical radiographs.⁵⁶ However, identification of minor anatomical changes might be difficult with CBCT.⁵⁷ Therefore, for a more detailed study of structures and quantification of dental parameters, including trabecular thickness, bone volume, and connectivity density, MCT can play a better role.⁵⁸

Moreover, the present study identified different advancements, such as changes in resolution (low or high) and voxel sizes with different and faster scanning times. All these advancements positively impacted accuracy and precision, which ultimately enhanced the diagnosis and treatment planning for root canal therapy. Changes in resolution might be helpful in the detection of small defects in images, whereas voxel sizes enhance the image quality and speed up the scanning process. Our findings are in line with those of another study, which indicated that high-resolution imaging 3D radiographs provide more detailed anatomical structures.⁵⁹ Another advancement is using 9.4T ultrashort echo time (UTE) MRI to visualize root canal anatomy at a resolution of 66 µm. After treatment, MRI differentiates the obturation materials and the surrounding structure of the tooth.⁶⁰ Another study used high resolution to visualize complete root fractures and observed higher diagnostic accuracy, particularly in the no-filling group.⁶¹ Furthermore, developments in software algorithms have enabled automated analysis of root canal morphology, aiding in the precise identification of anatomical variations and complexities. In a case study of a patient who presented with unsuccessful root canal treatment, CBCT imaging was performed, and the images were imported into a novel segmentation software, which allowed for successful and quick management of the tooth with ledges.⁶² Similarly, modern artificial intelligence driven approaches were also used to enhance the accuracy, particularly in the domain of deep learning-based tooth segmentation utilizing CBCT.⁶³ Deep learning models, which mostly require supervised learning, can offer several advantages over alternative semi-automated or manual approaches, owing to their robustness, accuracy, and speed.⁶⁴

3D imaging technology, particularly CBCT, has showcased higher accuracy compared to traditional radiography, attributed to its comprehensive 3D imaging capabilities offering varied perspectives of root canal anatomy.⁶⁵

Overall, 3D imaging technology, particularly CBCT, is more accurate than traditional radiography, as highlighted in the present study. The higher accuracy of CBCT imaging might be due to the provision of 3D imaging capabilities, allowing for a more comprehensive evaluation of root canal anatomy and morphology from different angles. Three-dimensional (3D) visualization enables dentists to detect subtle anatomical variations (complex root morphology and accessory canals) that may be missed on 2D radiographs. Furthermore, CBCT provides higher-resolution images without distortion and reduced superimposition of structures, leading to a visualized root canal anatomy. Finally, it provides precise and accurate measurements of root dimensions and distances, aiding in more accurate planning, treatment, and execution. Our findings agree with those of another study that compared MRI with CBCT (both 3D imaging modalities), and the reliability of MRI was high and comparable to that of CBCT. However, the temporal and spatial resolutions of CBCT are higher than those of MRI, which indicates that MRI has lower accuracy than CBCT.⁶⁶ Likewise, root canal working lengths were 15.38, 15.52, and 16.38 measured through CBCT, electronic apex locator, and digital radiography, respectively, in another study and showed significant differences among the groups and concluded that CBCT can be a reliable approach used for the determination of root canal working length.⁶⁷

This study provides an overview of technological improvements in 3D imaging technology for root canal therapy. However, limitations also arise, particularly in studies that use different methodologies, imaging protocols, and sample sizes, which potentially affect the generalizability of the present study's findings. Another significant limitation is the outcome variation, making it impossible to perform a meta-analysis. To improve the outcomes of root canal therapy, researchers, clinicians, and industry stakeholders must come together to translate innovations into clinical practice.

Conclusion

This review illustrates that CBCT provides a more accurate diagnosis of anatomical variations in the root canal. The introduction of CBCT into Endodontics allows for 3D visualization of the tooth anatomy and accurate detection of any anatomic variation, including minute differences associated with the number, shape, and position of the canals. However, this level of accuracy cannot be achieved using traditional radiography. The synthesis of evidence presented in this review underscores the transformative potential of 3D imaging technology in optimizing root canal therapy protocols and underscores the need for continued research and clinical validation to maximize its clinical utility while ensuring patient safety and affordability Moreover, this study provides evidence of how different image resolutions influence the precision and accuracy of clinical diagnosis and treatment planning for endodontically treated teeth. It also makes planning more accessible, as it shows which direction to take, and it is possible to see even wonderful details of the root canal system in 3D form. More importantly, incorporating 3D imaging techniques (e.g., CBCT imaging) into endodontic practice results in higher success rates.

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.