Open Access
CC BY 4.0 · European Journal of General Dentistry
DOI: 10.1055/s-0044-1801826
Original Article

Accuracy Evaluation of Access Cavity Preparation between Guided Endodontics and Conventional Technique

Santosh Kumar Singh
1   Conservative Dentistry and Endodontics, People's College of Dental sciences and Research Centre, People's University, Bhopal, Madhya Pradesh, India
,
Pankaj Mishra
1   Conservative Dentistry and Endodontics, People's College of Dental sciences and Research Centre, People's University, Bhopal, Madhya Pradesh, India
,
Siddhi Yadav
1   Conservative Dentistry and Endodontics, People's College of Dental sciences and Research Centre, People's University, Bhopal, Madhya Pradesh, India
,
Priyanka Dubey
1   Conservative Dentistry and Endodontics, People's College of Dental sciences and Research Centre, People's University, Bhopal, Madhya Pradesh, India
,
Suchi Pandey
1   Conservative Dentistry and Endodontics, People's College of Dental sciences and Research Centre, People's University, Bhopal, Madhya Pradesh, India
,
Muskan Sitlani
1   Conservative Dentistry and Endodontics, People's College of Dental sciences and Research Centre, People's University, Bhopal, Madhya Pradesh, India
,
Marco Di Blasio
2   Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, Italy
,
3   Department of Biomedical and Surgical and Biomedical Sciences, Catania University, Catania, Italy
,
Giuseppe Minervini
4   Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, India
5   Multidisciplinary Department of Medical-Surgical and Odontostomatological Specialties, University of Campania “Luigi Vanvitelli,” Naples, Italy
› Author Affiliations

Funding None.
 

Abstract

Objective The accuracy of endodontic access cavity preparation is crucial for the success of root canal treatment. This study aimed to compare the precision and efficiency of Guided Endodontics (GE) versus conventional techniques in locating and navigating root canals, examining the deviation from planned to performed procedures, and assessing the procedural time differences between the two methods.

Materials and Methods We utilized six sets of mandibular and maxillary jaws, each with 10 extracted single-rooted teeth, for our study. The teeth were divided into two groups for GE and conventional preparation. Preoperative CBCT and intraoral scans were used to facilitate virtual planning for GE, while conventional techniques relied on periapical radiographs. Two trained endodontists performed access cavity preparations on both groups, with deviations from the planned to the actual cavity and procedural times recorded meticulously.

Results Out of 60 teeth accessed, GE achieved a 100% canal detection rate, whereas the conventional technique identified 70% of the canals. The procedural time was significantly less for GE. Deviation analysis showed a linear discrepancy in the coronal region of 0.164 ± 0.190 mm and 0.254 ± 0.223 mm in the apical region for the first operator, with the second operator presenting similar deviations. Angular deviations were nearly identical between both operators.

Conclusion GE demonstrated superior accuracy in canal detection with less procedural time compared to the conventional technique. Although the difference in canal detection rate was not statistically significant, the reductions in time and linear deviation suggest that GE may offer a more precise and efficient approach to access cavity preparation.


Introduction

Conventionally, endodontic intervention aims to prevent the incidence of apical periodontitis.[1] This could further become difficult with the presence of an obliterated pulp canal, characterized by hard tissue deposited in root canal space.[2] This can be brought on by carious lesions, coronal restorations, pulp capping, and luxation injuries following dental trauma.[3]

Root canal therapy done to prevent apical periodontitis follows cleaning and shaping procedures to remove microbes. The first yet crucial step in achieving this aim is to prepare the cavity in a manner to obtain access to the root canal that determines the outcome, stability, and longevity. A straight line access is recommended for total debridement and disinfection, but with least invasiveness to decrease risk of fracture to the restored teeth.[4] Also, gaining endodontic access to calcified root canals is a difficult task. It is susceptible to technical failures such as altercations in the root canal morphology and significant loss of hard tissue, which may subsequently weaken a tooth or cause root perforation.[5] [6] [7] [8] [9] [10] [11] [12]

During access cavity preparation, marginal ridges are reduced resulting in loss of cuspal stiffness. Hence the concept of minimally invasive endodontics arose to preserve the tooth structure. However, certain clinical scenarios challenge this concept. Calcification in the coronal area or sclerosed canals demand excessive removal of tooth tissue compromising tooth structure and increase chances of perforation. This has paved the path for Guided Endodontics (GE)—a concept utilizing a three-dimensional (3D) imaging system, i.e., cone-beam computed tomography (CBCT)—for access cavity guidance. Since its advent, CBCT has opened up numerous prospects for treatment planning. CBCT is frequently employed in the field of dental implantology for 3D design, bone-level measurement, or to view anatomical structures like the mandibular nerve canal.[13] Another use of CBCT in guided implant surgery is the use of templates for implant-site preparation and insertion. With the help of matched 3D surface scans and CBCT data, these templates can now be produced utilizing 3D printing technology. CBCT images represent a considerable advancement in recent years. More recent devices and creative software with more resources have made it possible to create a more accurate reproduction of the internal anatomy of teeth while avoiding distortions that cause inaccuracy and access mistakes.[14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] In the vast majority of indicated circumstances, guided access may therefore be efficiently planned with the removal of image artefacts caused by high-density materials.

The procedure for GE includes obtaining volumetric data from CBCT and surface scan from an intraoral scanner. Both sets of data are then superimposed for planning a virtual access cavity and creating a template in the computer-aided design (CAD) software. The template is then created using 3D printing, and cavity prepared through drills. The present study was undertaken to answer the research questions “What is the accuracy of GE in navigation and location of root canals as compared to conventional technique,” “What is the difference in deviation between planned and performed procedure in virtual endodontics,” and “What is the difference in procedural time taken between the conventional and guided techniques.”


Materials and Methods

Study Models

Six similar sets of mandibular and maxillary jaw with 10 extracted teeth in each were used for the present study. The sample size was calculated at 80% power and 0.05 level of significance to detect medium effect size in outcomes, such as procedural time and deviation. This size ensured sufficient precision and robustness for binary and continuous outcomes. Teeth extracted for orthodontics or periodontal reasons and with a single root were chosen. Teeth restored endodontically or with severe dental caries were excluded. Models were divided into GE group and conventional canal preparation group. The teeth were randomly assigned to either group using a computer-generated randomization sequence. Additionally, the allocation of teeth to the two endodontists was randomized to reduce operator-related bias. Blinding was only partially used in the study. Because of the nature of the procedures, the operators were aware of the technique they were doing; nevertheless, the evaluation of accuracy (linear and angular deviations) and procedural outcomes was performed by an impartial assessor who was blinded to the group assignments.

Intraoral periapical radiographs were used for the conventional technique. Teeth in each model were adjoined using cold cure polymer at the cervical region alone barring root surface. A removable base made of putty silicone was then made to facilitate stability during clinical procedure.

Preoperative CBCT on all models was obtained using Carestream equipment, with voxel sizes of 150 m (110 kV; 30 mA; field of view: 128 cm), and data were stored in Digital Imaging and Communication in Medicine (DICOM) format. Furthermore, surface data were saved in the stereolithography (STL) file format after the models were scanned with an intraoral scanner. For virtual access cavity design, both types of data were superimposed using dental CAD software. A planning tool for guided implant surgery was used to import CBCT data. A virtual bur measuring a total length of 37 mm, having a working length of 18.5 mm, and a diameter of 1.5 mm was created. For planning purposes, a virtual sleeve for guidance with dimensions of 1.5 mm on the inside, 2.8 mm on the outside, and 6 mm on the length was also developed. To enable direct access to the apical part of the root canal, the virtual bur was placed on each tooth. The surface scans were submitted to the implant planning program in order to make a template for “GE.” By lining up the teeth's crowns, scans and CBCT data were compared. Finally, using a coDiagnostiX software tool, a virtual template was created.


Access Cavity Preparation

Two trained endodontists with normal visual acuity performed the access cavity preparation in both upper and lower arch models. Each operator performed five sets using GE and five sets with conventional technique. Dental loupes were used by both operators.


Conventional Cavity Preparation

A high-speed contra-angle handpiece and a cylindrical diamond bur with rounded edges were used to prepare the initial access cavity. Root canal was located using long pulp burs or an ultrasonic instrument with 25 size K file. The operators were permitted to halt the procedure if they were unable to reach a root canal or determined that the tooth was too compromised to be retained due to perforations.


CBCT or Virtual Imaging

Each model had templates attached to it. The bur was pecked through the template's sleeve with a low-speed handpiece until it came to rest against the resin sleeve's mechanical stop. Gauze was used to clean the bur, sodium hypochlorite irrigation was done at every 2 mm while drilling, and the bur was changed after working on 10 canals. Each canal was examined with a size 10 K-file (Dentsply Sirona, Charlotte, United States) to determine the accessibility of the canals after guided access cavity preparation was finished. The operation was classified as a canal accessibility if the K-file could enter the root canal by guided access cavity preparation without encountering any resistance; otherwise, it was classified as a canal inaccessibility. [Figs. 1] [2] [3] [4] [5] to [6] show the workflow for GE, including preoperative mandibular models, stabilization techniques, 3D-printed templates, virtual template designs using CBCT and STL data, and visualizations of planned and guided access cavities with precise angular deviations.

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Fig. 1 Preoperative model of mandibular arch for guided and conventional endodontics.
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Fig. 2 Mandibular model with cold cure polymer stabilization for endodontic access preparation.
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Fig. 3 3D-printed template for guided endodontic access cavity preparation. 3D, three-dimensional.
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Fig. 4 Superimposed CBCT and STL data for virtual template design in guided endodontics. CBCT, cone-beam computed tomography; STL, stereolithography.
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Fig. 5 Visualization of planned guided endodontic access cavities in the maxillary arch.
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Fig. 6 Virtual path of burs for guided endodontic access with angular deviations marked.

Quantifying Accuracy

Postoperative CBCT scans of the models were performed following access cavity preparation. By comparing the pre- and postoperative CBCT scans, data were uploaded into the coDiagnostiX program to assess the variation between the intended and performed access cavities. The virtual burs used for planning were placed on the access cavities of the postoperative scan after both scans had been aligned. The software automatically determines the divergence between the created cavity and the virtual planning at the base point (coronal end point of the working length of the bur) and tip of the bur. Variations in mesial/distal and buccal/palatal aspect, depth, and angle were identified.


Statistical Analysis

Data were analyzed using Statistical Package for Social Sciences (SPSS) version 25.0. Descriptive statistics were calculated for linear and angular deviations in coronal and apical areas. A paired “t”-test was used to assess the difference between planned and performed access cavities and procedural time for both groups. For all analyses, the level of significance was set below 5 percent.



Results

Sixty teeth were evaluated and categorized into two groups: guided and conventional. Outcomes assessed were key differences in terms of canal detection rates, procedural time, and accuracy between the planned and performed access cavities.

Canal Detection Rates

When assessed for the canal detection rates, the GE technique showed a superior canal detection rate by locating all 10 canals in each model, with a 100% success rate. Conversely, the conventional technique identified 7 out of 10 canals in the models, accounting for a success rate of 70%. Although the difference was not statistically significant, the difference in detection rates highlights the efficacy of guided techniques in navigating and locating root canals, particularly in challenging clinical scenarios like calcified canals.


Procedural Time

When evaluating procedural time, the guided technique was significantly faster than the conventional method for both operators. The mean procedural time for Operator 1 using the conventional technique was 22.58 ± 2.73 minutes, whereas the guided method reduced this time to 17.41 ± 1.51 minutes, with a statistically significant difference (p = 0.000). Similarly, Operator 2 required 21.76 ± 2.19 minutes for the conventional technique, which decreased to 17.65 ± 1.54 minutes using the guided method, also showing a significant difference (p = 0.000) as observed in [Table 1]. The reduction in procedural time with GE can be attributed to the preoperative planning and the precision provided by the templates.

Table 1

Operative time

Parameter

Conventional

Guided endodontics

Chi-square statistic

p-Value

Canals detected

Operator 1

8/10

10/10

2.222

0.136 (NS)

Operator 2

7 / 10

10 /10

3.529

0.060 (NS)

Procedural time required (in minutes)

ANOVA statistic

p-Value

Operator 1

22.58 ± 2.73

17.41 ± 1.51

Operator 2

21.76 ± 2.19

17.65 ± 1.54


Accuracy of Access Cavity

The accuracy of access cavity preparation was quantified by comparing the deviations between the planned and performed cavities in both techniques. Linear deviations were measured at the coronal and apical ends of the cavity, while angular deviations were also recorded. For Operator 1, the linear deviation in the coronal region was 0.164 ± 0.190 mm, and in the apical region, it was 0.254 ± 0.223 mm. Operator 2 showed similar results, with coronal deviation being 0.197 ± 0.237 mm and apical deviation measuring 0.216 ± 0.155 mm. These deviations were minimal and indicated that GE closely adhered to the virtual plan. The angular deviations were almost identical between the two operators, averaging 1.818 ± 1.228 degrees across all samples as seen in [Table 2]. In comparison, the conventional technique showed greater variability in linear and angular deviations due to the lack of guidance and reliance on manual control. This shows the enhanced precision of GE, which is particularly valuable in clinical cases with complex canal anatomies or calcifications.

Table 2

Accuracy between cavity created and virtually planned

Variables

Mean + SD

Minimum

Maximum

Linear deviation (coronal), in mm

Operator 1

0.164 ± 0.190

0.00

0.52

Operator 2

0.197 ± 0.237

0.00

0.64

Linear deviation (apical), in mm

Operator 1

0.254 ± 0.223

0.00

0.74

Operator 2

0.216 ± 0.155

0.01

0.48

Angular deviation, in degrees

Operator 1

1.804 ± 1.238

0.02

3.86

Operator 2

1.832 ± 1.218

0.02

3.93

Average

1.818 + 1.228



Discussion

This study showed that GE fared well compared to the conventional form in terms of locating canals and time taken for the procedure. When evaluating for GE, it was observed there was minimal difference between the planned and performed procedures in terms of linear and angular deviations.

The first laboratory research on the predictability of guided endodontic cavity preparation was reported by Buchgreitz et al[32] and Zehnder et al.[33] Both studies found minor variations between virtually planned and practically carried out preparations in extracted human teeth. Subsequent clinical case reports also reported on the successful treatment of calcified anterior teeth in the maxilla by Krastl et al[34] and van der Meer et al.[35]

Our study showed a linear deviation of 0.213 ± 0.33 mm in the apical region and 0.180 ± 0.233 mm in the coronal region. This was similar to the other studies in the existing literature. Buchgreitz et al assessed the accuracy between drilled and guided paths on 48 teeth mounted with calcified canals and found it to be 0.42 mm. Another study conducted by Su et al[3] noted a linear deviation of 0.13 mm in the coronal part and 0.46 mm in the apical part. Angular deviation reported in our study was 1.818 ± 1.228 degree, which was slightly lesser than that reported by Su et al[3] but was almost similar to that of Zehnder et al.

Decurcio et al[36] have recommended GE in cases of endodontic surgery for better positioning of the lesion site and dental apex. Coronary access to calcified tooth is a demanding surgical task, making it difficult to keep the correct trepanation direction when it mostly involves the middle and apical thirds. It can lead to deviations or perforations even for skilled endodontists, increasing the likelihood of failure. Employing the guided approach offers the patient improved safety, enhanced predictability, lesser amount of tooth tissue removal, and a shorter duration of clinical visit. Additionally, these guided techniques lessen the possibility of trans- and postoperative problems such bleeding or injury to nearby anatomical tissues and in turn a better prognosis.

The benefit of GE is that it takes less investment in the office because digital planning centers are equipped with tools for image acquisition, virtual planning, and guides printing. Additionally, it requires fewer clinical appointments, which improves patient comfort and lowers professional stress. The use of GE is recommended in a variety of clinical settings. Greater practical applicability was made possible by a deeper comprehension of its features and by exploring digital resources in endodontics. Indications must regard this as an adjunct to aid the endodontist's arsenal rather than as a particular convenience resource and facilitator for practitioners with less clinical expertise and/or who do not employ the right technology for difficult endodontic procedures. However, with the advancement of technology, extensive research and applications for digital endodontics are needed.

A variety of endodontic guiding systems are now introduced, such as the sleeveless guide system and the dynamic navigation system (DNS).[37] [38] The path is guided by guiding rails and cylinders attached to the handpiece in the sleeveless guide system. This method could be utilized to address the issue of a shortage of vertical space in the molar area because it takes up lesser space above the occlusal surface and offers better visibility than a sleeve template. On the other hand, DNS offers precision comparable to static templates and has the capacity to modify the direction of the access cavity in real time.[39] However, operating DNS requires stronger eye–hand coordination and technological practice, which adds to the increased cost.

The complex architecture of root canals might limit the utilization of GE, even when proposed as an indication. Only the straight section of the root canal may be reached with guided access, and the accuracy decreases as the root canal curves. In this regard, careful planning is required, with only the straight portion being subjected to wear and drilling to prevent bending. The diameter of the root is another feature of dental anatomy. The use of burs in this area is incompatible due to the diverse root configurations in the various dental groups, which may result in roots with limited thickness in the mesiodistal and/or buccolingual direction (e.g., lower incisors or mesiobuccal roots of the upper molars). Patients with limited mouth opening may make guided access more difficult or even dangerous, especially for posterior teeth. The virtual planning and accuracy of the prototype guides for the procedure may also be restricted by CBCT tests that exhibit image artefacts in the region.

Comparing our study's canal detection rates with those reported in the literature, our success rate surpasses the conventional technique's findings of merely 70 to 80% success by quite some margin. Kostunov et al[40] present results that stand in contrast to these: their employment of traditional methods yielded an impeccable track record—achieving a perfect score—a feat not replicated by any means using guided techniques, which earned only slightly lower at 93.3%. Both methods, in alignment with Hildebrand et al,[41] successfully detected canals; however, the studies may exhibit variations due to differences in tooth selection type, degree of present calcification, or specific methodologies employed. The study of Kostunov et al observed that modalities indeed preserve more tooth structure compared to the conventional technique, in terms of the removal of dental substance; our study however—while not providing quantitative data on tooth substance removed—suggests through minimal deviations between planned and executed cavities: it is likely that guided techniques result in less loss of tooth structure.

Our study further reveals that when we scrutinize procedural times, guided techniques demonstrate a reduction in procedure duration compared to the conventional technique. However, these findings somewhat contradict those of Hildebrand et al[41]; their research did not unveil any significant difference in the time taken for procedures using either method. The complexity of the cases handled, the operators' experience level, or the specific guided technology utilized may attribute to these differences. Hildebrand et al[41] underscored the necessity for extra radiographs, requiring a total of 31 supplementary ones in procedures employing GE; nonetheless, our study did not scrutinize the quantity of radiographs taken. This aspect—potentially indicative of overall efficiency and time-saving benefits—is worth considering when assessing its merits. Should the guided approach indeed require additional radiographic imaging, it may undermine certain benefits—specifically, those pertaining to time efficiency.

By incorporating guided techniques into their daily operations, dentists might potentially reduce treatment durations. Consequently, they could accommodate a larger patient load without sacrificing care quality. This enhanced efficiency may yield superior throughput and satisfaction among patients: they would value not only speedier procedures but also decreased discomfort levels. Moreover, the exceptional accuracy of this approach proves especially advantageous in managing challenging cases with intricate anatomy or when conventional landmarks become obscured. The transition, however, necessitates a learning curve and an initial investment in requisite technology and training. Dentists should balance these considerations with the potential benefits: they must not only evaluate the short-term impact on their practice but also forecast long-term improvements in treatment outcomes. When contemplating this shift, practices need to incorporate ongoing expenses of materials—as well as maintenance costs linked directly to the implemented technological advancements—into their deliberations.

The experimental setup utilized in our study may not entirely replicate the conditions encountered during endodontic access in a live clinical environment. We selected single-rooted teeth for this study—specifically extracted for distinct reasons: to limit case diversity and potentially influence external validity and applicability of results towards complex root system or differently indicated extraction cases. We also excluded teeth that had received previous endodontic treatment or were significantly decayed. Yet, this selection criterion might have omitted a large patient population who typically needs endodontic intervention; therefore, it fails to depict the entire spectrum of clinical scenarios. The models constructed fixed teeth in place with a polymer at the cervical region only; this method could compromise procedural stability and inaccurately mimic the natural support that surrounding tissues provide in a patient's mouth. All dental practices, particularly those in resource-limited settings, may not have the accessibility or practicality to rely on advanced imaging techniques such as preoperative CBCT and sophisticated virtual planning software. The comparative assessment between the two techniques could potentially incorporate an element of subjectivity and inconsistency due to the operator's discretionary power in halting conventional procedures. Scans obtained after the procedure and software analysis heavily influence the quantification of accuracy; however, this approach–though thorough–falls short in capturing every clinical variable impacting access cavity preparation's success. These unaccounted factors include: the clinician's tactile feedback or their decision-making process throughout the procedure.

Integrating GE into ordinary clinical practice necessitates a careful study of its benefits, costs, and practical implications. Though GE provides higher benefits such as improved accuracy, shorter procedure times, increased safety, and less tooth structure loss, adoption of these techniques requires significant financial and technological resources. The initial expenditure covers the CBCT system, intraoral scanners, CAD software, and 3D printing capabilities, as well as continuous maintenance and material costs. Although these costs may be prohibitively expensive for small or resource-constrained clinics, the potential benefits, especially in complex instances such as calcified or destroyed canals, justify their usage in enhancing treatment outcomes and reducing procedural mistakes. GE's ability to reduce treatment time can improve practice throughput, allowing physicians to accommodate more patients while providing high-quality care. However, its use necessitates training to understand digital workflows such as CBCT imaging, virtual planning, and template fabrication, which has a modest learning curve. High-resolution CBCT systems and dependable 3D printers are critical for reaching the precision that GE claims. Practices that cannot afford these investments could work with centralized planning centers for imaging and guide production, lowering their financial load while providing access to this advanced approach. As a result, its routine application may be more appropriate for complex circumstances requiring precision, whereas simpler scenarios may not merit the additional cost and labor.


Conclusion

GE was better than the conventional procedure when compared to location of canal and time taken. The precisional accuracy of guided path and followed path was also acceptable in the GE procedure. The procedure time was notably reduced with the guided method. Deviations from the virtual plan to the actual cavity preparation were minimal. The assessments support the integration of guided techniques into routine endodontic practice to improve the precision and efficacy of treatments. In challenging situations, such as those requiring obliterated or calcified canals, the guided technique results in a more predictable outcome with fewer iatrogenic mistakes, such as perforations or excessive tooth structure removal. The guided technique's modest deviations highlight its ability to preserve tooth structure while maintaining the integrity of the remaining tooth. This is consistent with the concepts of minimally invasive endodontics, which aim to improve treatment outcomes while minimizing tooth harm.



Conflict of Interests

None declared.

Acknowledgements

Not applicable.

Ethics Approval and Consent to Participate

Permission to conduct the study was obtained from Peoples College of Dental Sciences and Research Centre, Bhopal (EC244236).


Consent for Publication

Obtained.


Availability of Data and Materials

The data will be available on reasonable request from the corresponding author.


Author Contribution

Conceptualization: S.K.S. and P.M.; methodology: S.Y., P.D., and S.K.S.; software: P.M. and S.K.S.; formal analysis: P.M. and S.Y.; investigation: P.D. and P.M.; data curation: P.D. and P.M.; writing—original draft preparation: M.S., M.C., and G.M.; writing—review and editing: M.S., M.C., G.M.; supervision: G.M.; funding acquisition: M.C.; administration: P.D. All authors have read and agreed to the published version of the manuscript.



Address for correspondence

Marco Di Blasio, PhD
Department of Biomedical, Surgical and Dental Sciences, University of Milan
Milan
Italy   

Publication History

Article published online:
01 September 2025

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Zoom
Fig. 1 Preoperative model of mandibular arch for guided and conventional endodontics.
Zoom
Fig. 2 Mandibular model with cold cure polymer stabilization for endodontic access preparation.
Zoom
Fig. 3 3D-printed template for guided endodontic access cavity preparation. 3D, three-dimensional.
Zoom
Fig. 4 Superimposed CBCT and STL data for virtual template design in guided endodontics. CBCT, cone-beam computed tomography; STL, stereolithography.
Zoom
Fig. 5 Visualization of planned guided endodontic access cavities in the maxillary arch.
Zoom
Fig. 6 Virtual path of burs for guided endodontic access with angular deviations marked.