Dynamic navigation: a laboratory study on the accuracy and potential use of guided root canal treatment

Accuracy evaluation of dental CBCT and scanned model registration method based on pulp horn mapping surface: an in vitro proof-of-concept

BACKGROUND AND AIM

3D fusion model of cone-beam computed tomography (CBCT) and oral scanned data can be used for the accurate design of root canal access and guide plates in root canal therapy (RCT). However, the pose accuracy of the dental pulp and crown in data registration has not been investigated, which affects the precise implementation of clinical planning goals. We aimed to establish a novel registration method based on pulp horn mapping surface (PHMSR), to evaluate the accuracy of PHMSR versus traditional methods for crown-pulp registration of CBCT and oral scan data.

MATERIALS AND METHODS

This vitro study collected 8 groups of oral scanned and CBCT data in which the left mandibular teeth were not missing, No. 35 and No. 36 teeth were selected as the target teeth. The CBCT and scanned model were processed to generate equivalent point clouds. For the PHMSR method, the similarity between the feature directions of the pulp horn and the surface normal vectors of the crown were used to determine the mapping points in the CBCT point cloud that have a great influence on the pulp pose. The small surface with adjustable parameters is reconstructed near the mapping point of the crown, and the new matching point pairs between the point and the mapping surface are searched. The sparse iterative closest point (ICP) algorithm is used to solve the new matching point pairs. Then, in the C +  + programming environment with a point cloud library (PCL), the PHMSR, the traditional sparse ICP, ICP, and coherent point drift (CPD) algorithms are used to register the point clouds under two different initial deviations. The root square mean error (RSME) of the crown, crown-pulp orientation deviation (CPOD), and position deviation (CPPD) were calculated to evaluate the registration accuracy. The significance between the groups was tested by a two-tailed paired t-test (p < 0.05).

RESULTS

The crown RSME values of the sparse ICP method (0.257), the ICP method (0.217), and the CPD method (0.209) were not significantly different from the PHMSR method (0.250). The CPOD and CPPD values of the sparse ICP method (4.089 and 0.133), the ICP method (1.787 and 0.700), and the CPD method (1.665 and 0.718) than for the PHMSR method, which suggests that the accuracy of crown-pulp registration is higher with the PHMSR method.

CONCLUSION

Compared with the traditional method, the PHMSR method has a smaller crown-pulp registration accuracy and a clinically acceptable deviation range, these results support the use of PHMSR method instead of the traditional method for clinical planning of root canal therapy.

Does dynamic navigation system preserve more dentine? - A systematic review

OBJECTIVE

This systematic review aims to comparatively analyse the amount of dentin removal by free hand and static guided endodontics with dynamic navigation system (DNS) in endodontic access cavity preparation.

METHODS

The systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Based on the structured PICO framework of "Comparative evaluation of dynamic navigation system (I) to freehand (C) and static guided endodontics (C) in endodontic access cavity preparation on the preservation of tooth structure (O) when assessed on permanent human teeth (P)", the keywords were formulated and the articles were retrieved from three databases namely PubMed, Scopus and Embase, based on the keywords from the time of inception of DNS till June 2023. The risk of bias assessment was done using a modified Joanne Briggs Institute checklist, which evaluated domains such as randomisation, sample size, image acquisition using CBCT, angulation, accuracy and time taken. As the data was heterogenous, a quantitative meta-analysis was not performed.

RESULTS

Initially, 174 articles were retrieved from the three databases, 30 duplicates were removed, after title check 108 articles were excluded and following abstract check only 10 articles qualified for full text analysis. On reviewing the 10 full text articles, 5 articles were excluded and the remaining 5 articles were subjected to the risk of bias analysis which showed that 2 articles displayed low risk of bias and three articles showed high risk of bias. The RoB analysis revealed that only 2 studies evaluated the preservation of dentin in terms of accuracy, angulation and time taken proving the increased precision with minimal loss of tooth structure using DNS. In both the studies, DNS proved to be superior to free hand technique in terms of precision, accuracy and efficiency in locating the canals during access cavity preparation with maximal preservation of tooth structure.

CONCLUSION

With the minimal literature evidences, the present systematic review highlights maximal preservation of dentin using DNS. However, further invitro and invivo studies comparing the free hand, static guided endodontics to DNS must be carried out for its translation into clinical practice.

CLINICAL SIGNIFICANCE

Dynamic navigation system provides maximal preservation of dentin during access cavity preparation.

Does dynamic navigation assisted student training improve the accuracy of dental implant placement by postgraduate dental students: an in vitro study

OBJECTIVES

To assess the accuracy of implant placement in models and satisfaction in dynamic navigation assisted postgraduate dental students training.

METHODS

Postgraduate dental students who had at least one year of dental clinical practice with no experience in dental implant surgeries were included. Students were instructed to make treatment plans in the dynamic navigation system. Each student placed two maxillary right incisors, using freehand approach at first and then under dynamic navigation. The implant position was compared with treatment plan. Factors influencing the accuracy of implants placed under dynamic navigation were analyzed. Student acceptance towards the training and use of dynamic navigation was recorded using a questionnaire.

RESULTS

A total of 21 students placed 42 implants. For freehand implant placement, the median entry point deviation, apex point deviation, and implant axis deviation was 3.79 mm, 4.32 mm, and 10.08°. For dynamic guided implant placement, the median entry point deviation, apex point deviation, and implant axis deviation was 1.29 mm, 1.25 mm, and 4.89° (p < 0.001). The accuracy of dynamic guided implant was not influenced by student gender or familiarity with computer games. All students were satisfied with the training.

CONCLUSIONS

Dynamic navigation system assisted students in improving the accuracy of implant placement and was well accepted by students.

Accuracy and efficiency of dynamic navigated root-end resection in endodontic surgery: a pilot in vitro study

BACKGROUND

The operation accuracy and efficiency of dynamic navigated endodontic surgery were evaluated through in vitro experiments. This study provides a reference for future clinical application of dynamic navigation systems in endodontic surgery.

MATERIALS AND METHODS

3D-printed maxillary anterior teeth were used in the preparation of models for endodontic surgery. Endodontic surgery was performed with and without dynamic navigation by an operator who was proficient in dynamic navigation technology but had no experience in endodontic surgery. Optical scanning data were applied to evaluate the length and angle deviations of root-end resection. And the operation time was recorded. T tests were used to analyze the effect of dynamic navigation technology on the accuracy and duration of endodontic surgery.

RESULTS

With dynamic navigation, the root-end resection length deviation was 0.46 ± 0.06 mm, the angle deviation was 2.45 ± 0.96°, and the operation time was 187 ± 22.97 s. Without dynamic navigation, the root-end resection length deviation was 1.20 ± 0.92 mm, the angle deviation was 16.20 ± 9.59°, and the operation time was 247 ± 61.47 s. Less deviation was achieved and less operation time was spent with than without dynamic navigation (P < 0.01).

CONCLUSION

The application of a dynamic navigation system in endodontic surgery can improve the accuracy and efficiency significantly for operators without surgical experience and reduce the operation time.

Negotiation of Calcified Canals

The gradual formation of hard tissue along the root canal walls is a natural process associated with aging, typically progressing slowly over time. In reaction to tooth wear, operative procedures, vital pulp treatments, or regenerative endodontic procedures, hard tissue may also accumulate within the pulp canal space at a slow rate. In certain cases, such as dental trauma, autotransplantation, or orthodontic treatment, this deposition of hard tissue can accelerate unexpectedly, resulting in rapid narrowing or complete closure of the root canal space. This situation is called calcific metamorphosis (CM), root canal calcification, or pulp canal obliteration (PCO). Performing conventional endodontic therapy on severely calcified canals presents significant challenges and increases the risk of procedural accidents. Calcified canals introduce such complexity that dedicated negotiation concepts and specially designed instruments have been developed to deal with the challenge. This article seeks to review the existing methods for effectively navigating calcified canals and to introduce the buckling resistance activation test (BRAT) technique.

Quality and haptic feedback of three-dimensionally printed models for simulating dental implant surgery

STATEMENT OF PROBLEM

A model offering anatomic replication and haptic feedback similar to that of real bone is essential for hands-on surgical dental implant training. Patient-specific skeletal models can be produced with 3-dimensional (3D) printing, but whether these models can offer optimal haptic feedback for simulating implant surgery is unknown.

PURPOSE

The purpose of this trial was to compare the haptic feedback of different 3D printed models for simulating dental implant surgery.

MATERIAL AND METHODS

A cone beam computed tomography image of a 60-year-old man with a partially edentulous mandible was manipulated to segment the mandible and isolated from the rest of the scan. Three-dimensional models were printed with 6 different printers and materials: material jetting-based printer (MJ, acrylic-based resin); digital light processing-based printer (DLP, acrylic-based resin); fused filament fabrication-based printer (FFF1, polycarbonate filament; FFF2, polylactic acid filament); stereolithography-based printer (SLA, acrylic-based resin); and selective laser sintering-based printer (SLS, polyamide filament). Five experienced maxillofacial surgeons performed a simulated implant surgery on the models. A 5-point Likert scale questionnaire was established to assess the haptic feedback. The Friedman test and cumulative logit models were applied to evaluate differences among the models (α=.05).

RESULTS

The median score for drilling perception and implant insertion was highest for the MJ-based model and lowest for the SLS-based model. In relation to the drill chips, a median score of ≥3 was observed for all models. The score for corticotrabecular transition was highest for the MJ-based model and lowest for the FFF2-based model. Overall, the MJ-based model offered the highest score compared with the other models.

CONCLUSIONS

The 3D printed model with MJ technology and acrylic-based resin provided the best haptic feedback for performing implant surgery. However, none of the models were able to completely replicate the haptic perception of real bone.

Comparing accuracy in guided endodontics: dynamic real-time navigation, static guides, and manual approaches for access cavity preparation - an in vitro study using 3D printed teeth

OBJECTIVES

To assess root canal localization accuracy using a dynamic approach, surgical guides and freehand technique in vitro.

MATERIALS AND METHODS

Access cavities were prepared for 4 different 3D printed tooth types by 4 operators (n = 144). Deviations from the planning in angle and bur positioning were compared and operating time as well as tooth substance loss were evaluated (Kruskal-Wallis Test, ANOVA). Operating method, tooth type, and operator effects were analyzed (partial eta-squared statistic).

RESULTS

Angle deviation varied significantly between the operating methods (p < .0001): freehand (9.53 ± 6.36°), dynamic (2.82 ± 1.8°) and static navigation (1.12 ± 0.85°). The highest effect size was calculated for operating method (ηP²=0.524), followed by tooth type (0.364), and operator (0.08). Regarding deviation of bur base and tip localization no significant difference was found between the methods. Operating method mainly influenced both parameters (ηP²=0.471, 0.379) with minor effects of tooth type (0.157) and operator. Freehand technique caused most substance loss (p < .001), dynamic navigation least (p < .0001). Operating time was the shortest for freehand followed by static and dynamic navigation.

CONCLUSIONS

Guided endodontic access may aid in precise root canal localization and save tooth structure.

CLINICAL RELEVANCE

Although guided endodontic access preparation may require more time compared to the freehand technique, the guided navigation is more accurate and saves tooth structure.

Limitations and Management of Dynamic Navigation System for Locating Calcified Canals Failure

Nonsurgical endodontic teeth treatment with severe pulp canal obliteration poses challenges, primarily locating canals. By combining 3-dimensional reconstruction and spatial location registration, the dynamic navigation technique uses an optical tracking system to guide the clinician to drill in real time according to the predesigned path until access to the canal is established. Several in vitro studies and case reports have shown that calcified canal location with dynamic navigation system (DNS) is more accurate and efficient, yet the technique has limitations. In 4 cases with 7 teeth, this work presents manipulation process and clinical outcomes of DNS helping in calcified canal location. We performed handpiece adaptation and elucidated the failure to locate the canals with DNS in 2 teeth, resulting in canal geometry alteration and canal path deviation. Subsequently, the more experienced endodontist located the canals by combining cone-beam computed tomographic imaging and dental operating microscopy. All patients were completely asymptomatic after treatment. At the 1-year follow-up visit, the bone healing of periapical lesions progressed well according to the periapical radiography or cone-beam computed tomographic imaging. These findings indicate that DNS is a promising technique for locating calcified canals; however, it needs to be refined before clinical use.

Expert consensus on digital guided therapy for endodontic diseases

Digital guided therapy (DGT) has been advocated as a contemporary computer-aided technique for treating endodontic diseases in recent decades. The concept of DGT for endodontic diseases is categorized into static guided endodontics (SGE), necessitating a meticulously designed template, and dynamic guided endodontics (DGE), which utilizes an optical triangulation tracking system. Based on cone-beam computed tomography (CBCT) images superimposed with or without oral scan (OS) data, a virtual template is crafted through software and subsequently translated into a 3-dimensional (3D) printing for SGE, while the system guides the drilling path with a real-time navigation in DGE. DGT was reported to resolve a series of challenging endodontic cases, including teeth with pulp obliteration, teeth with anatomical abnormalities, teeth requiring retreatment, posterior teeth needing endodontic microsurgery, and tooth autotransplantation. Case reports and basic researches all demonstrate that DGT stand as a precise, time-saving, and minimally invasive approach in contrast to conventional freehand method. This expert consensus mainly introduces the case selection, general workflow, evaluation, and impact factor of DGT, which could provide an alternative working strategy in endodontic treatment.

Dynamic Navigation System vs. Free-Hand Approach in Microsurgical and Non-Surgical Endodontics: A Systematic Review and Meta-Analysis of Experimental Studies

(1) Background: A Dynamic Navigation System (DNS) is an innovative tool that facilitates the management of complex endodontic cases. Despite the number of advantages and limitations of this approach, there is no evidence-based information about its efficiency in comparison with that of the traditional method in endodontics. (2) Objectives: We aimed to explore any beneficial effects of the DNS and compare the outcomes of DNS vs. free-hand (FH) approaches for non-surgical and microsurgical endodontics. (3) Methods: A literature search was conducted in August 2023 to identify randomized, experimental, non-surgical, and microsurgical endodontic studies that compared the DNS with FH approaches. The procedural time (ΔT, s), substance loss (ΔV, mm3), angular deviation (ΔAD, °), coronal/platform linear deviation (ΔLD_C, mm), and apical linear deviation (ΔLD_A, mm) were recorded and analyzed. Quality and risk of bias assessments were conducted according to the Quality Assessment Tool For In Vitro Studies. A meta-analysis was performed using mean difference and standard deviation for each outcome, and heterogeneity (I2) was estimated. p < 0.05 was considered significant. (4) Results: One-hundred and forty-six studies were identified following duplicate removal, and nine were included in the systematic review and meta-analysis. The overall risk of bias was classified as low. The DNS was found to be more accurate and efficient than the FH approach was, resulting in a significantly shorter operation time (p < 0.00001) and less angular (p ≤ 0.0001) and linear deviation (p ≤ 0.01). For substance loss, the advantage of the DNS was significant only for microsurgery (p = 0.65, and p < 0.005, for non-surgical and microsurgical procedures, respectively). A reduced risk of iatrogenic failure using the DNS was observed for both expert and novice operators. (5) Conclusions: The DNS appears beneficial for non-surgical and microsurgical endodontics, regardless of the operator's experience. However, appropriate training and experience are necessary to access the full advantages offered by the DNS.

Accuracy and Efficiency of Endodontic Microsurgery Assisted by Dynamic Navigation Based on Two Different Registration Methods: An In Vitro Study

INTRODUCTION

This study aimed to compare the accuracy and efficiency of dynamic navigation-assisted endodontic microsurgery (DN-EMS) using two different registration methods.

METHODS

Three-dimensional-printed jaw models, including 40 teeth, were divided into two groups (n = 20). Cone-beam computed tomography images of all teeth were scanned under the same exposing parameters. An endodontic dynamic navigation system (DHC-ENDO1) was used to plan the drilling paths. Dynamic navigation-assisted endodontic microsurgery (DN-EMS) was performed using either U-shaped tube (UT) or tooth cusp (TC) registration method. The accuracy was determined by platform deviation, end deviation, angular deviation, resection angle, and resection length deviation. The registration efficiency was defined as the time required to complete the registration procedure. Osteotomy volume of each resection was calculated by Mimics 21.0. Statistical analyses were performed using IBM SPSS Statistics 24.0. Comparisons between groups were performed using the independent sample t test or Mann-Whitney U test. P < .05 was adopted as significant difference.

RESULTS

The UT group was significantly more accurate in terms of mean platform deviation, end deviation, angular deviation, and resection angle (P < .05). Resection length deviation did not differ significantly between the registration groups. The UT group was significantly more efficient than the TC group (P < .05). No significant differences were found in the osteotomy volumes between the two groups.

CONCLUSIONS

In the model-based surgical simulation comparison, DN-EMS based on UT registration is more accurate and efficient than the TC method but requires an additional registration device. TC technique may be a reasonable alternative to UT registration in certain clinical tasks.

Current Applications of Dynamic Navigation System in Endodontics: A Scoping Review

This scoping review (SCR) was conducted to map the existing literature on dynamic navigation system (DNS), to examine the extent, range, and nature of research activity. Additionally, this SCR disseminates research findings, determines the value of conducting a full systematic review with meta-analysis, and identifies gaps in the existing literature and future directions. This SCR followed Arksey and O'Malley's five stages framework. The electronic search was performed in PubMed (Medline), Scopus (Elsevier), and Web of Science (Clarivate Analytics) databases using a search strategy. Five themes emerged during the descriptive analysis that captured the DNS application in endodontics. The DNS has been explored for creating access cavities (8/18, 44.44%), locating calcified canals (4/18, 22.2%), microsurgery (3/18, 16.6%), post removal (2/18, 11.1%), and intraosseous anesthesia (1/18, 5.5%). Out of the 18 studies included, 12 are in vitro (66.6%), five are in vivo (case report) (27.7%), and one is ex vivo (5.5%). The DNS demonstrated accuracy and efficiency in performing minimally invasive access cavities, locating calcified canals, and performing endodontic microsurgery, and it helped target the site for intraosseous anesthesia.

Effect of field of view and voxel size on CBCT-based accuracy of dynamic navigation in endodontic microsurgery: an in vitro study

INTRODUCTION

This study aimed to evaluate the influence of field of view (FOV) and voxel size on the accuracy of dynamic navigation (DN)-assisted endodontic microsurgery (EMS).

METHODS

Nine sets of maxillary and mandibular three-dimensional-printed jaw models composed of 180 teeth were divided into nine groups with different FOVs (80 × 80 mm, 60 × 60 mm, and 40 × 40 mm) and voxel sizes (0.3, 0.16, and 0.08 mm). The endodontic DN system was used to plan and execute the EMS. The accuracy of the DN-EMS was represented by the platform deviation, end deviation, angular deviation, resection angle, and resection length deviation. Statistical analyses were performed using SPSS 24.0, and the significance level was set at p < 0.05.

RESULTS

The average platform, end, angular, resection angle, and resection length deviation were 0.69 ± 0.31 mm, 0.93 ± 0.44 mm, 3.47 ± 1.80°, 2.35 ± 1.76°, and 0.41 ± 0.29 mm, respectively. No statistically significant differences in accuracy were observed between the nine FOV and voxel size groups.

CONCLUSION

FOV and voxel size did not appear to play an important role in the accuracy of DN-EMS. Considering the image quality and radiation dose, it is reasonable to select a limited FOV (such as 40 × 40 mm and 60 × 60 mm) to cover only the registration device, involved teeth, and periapical lesion. The voxel size should be selected according to the required resolution and CBCT units.

Ex-vivo and in-vivo validation of a novel measuring protocol for guided endodontics

OBJECTIVES

To (1) validate the use of a post-operative intraoral scan (IOS) versus Cone Beam Computed Tomography (CBCT), gold standard, on its ability to measure the accuracy of guided endodontics, and (2) present clinical data on the accuracy of guided endodontics.

METHODS

Four models, including 10 extracted teeth each, were created. Forty guided access cavities were planned on dentin to simulate pulp canal obliteration (PCO). Two operators performed guided access cavities. A post-operative CBCT and IOS were acquired. The deviation coronally, apically, and angular deviation was measured with CBCT and IOS. Clinical accuracy was measured using an IOS acquired immediately after drilling the access cavity with the aid of a guide. Data analysis was performed using multiway Anova and corrected for simultaneous hypothesis testing according to Tukey. P ≤ 0.05 was considered statistically significant. Descriptive statistics on the clinical accuracy of guided endodontics were performed.

RESULTS

Thirty-eight cavities were assessed with a mean length of 13.8 mm. No statistical difference between operators and methods was found for all parameters (P > 0.05). Thirty-three patients were treated with guided endodontics and measured using an IOS. Results show an average coronal, apical, and angular deviation of 0.2 mm, 0.45 mm, and 1.91^° respectively. The average length of the access cavities was 12.5 mm.

CONCLUSIONS

An IOS can be used to measure the accuracy of guided endodontics. Clinical data showed high accuracy of guided endodontics with a mean apical deviation smaller than 0.5 mm and a mean angular deviation of less than 2^°.

CLINICAL SIGNIFICANCE

The use of an IOS does not involve additional radiation exposure. A safety margin of at least 1 mm around the planned trajectory should be respected when planning the case to minimize the possibility of root perforation.

In vitro study on the accuracy of sleeveless guided endodontics and treatment of a complex upper lateral incisor

PURPOSE

The present study aims to assess the accuracy of sleeveless guided endodontics for root canal treatment of severe pulp canal obliteration (PCO) in 3D printed jaws. Additionally, the treatment of a complex lateral incisor is presented to illustrate the use of sleeveless guides in a clinical situation.

METHODS

Two cone-beam computed tomography (CBCT) volumes of an upper and lower jaw were selected to design 3D printed models with PCO. Virtual planning of the access cavities was performed from right to left second premolar. Then, the models were mounted into a phantom head to simulate an actual patient. Two operators with different levels of experience in endodontics performed guided access cavities. The handpiece was guided by guiding rails placed against each other on the sides of the tooth. A post-operative CBCT scan was taken for analysis.

RESULTS

Eighty-eight guided access cavities (44 per operator) were drilled on eight 3D printed models. The mean length of the access cavities was 15.3 mm, with a mean coronal and apical deviation of 0.5 mm and 0.7 mm respectively. The mean angular deviation was 1.5^°. No statistically significant difference was found between operators for the three measured parameters.

CONCLUSIONS

This study demonstrates, within its limitations, that sleveless guides represent an accurate method for guided endodontic treatment. No statistically significant difference between operators was found when using the guide.

CLINICAL SIGNIFICANCE

This method offers a valuable alternative to conventional endodontic guides with similar accuracy results.

Guided Endodontic Surgery: A Narrative Review

Background and objectives: Endodontic surgery has evolved over the last two decades. The use of state-of-the-art guided endodontic surgical procedures produces a predictable outcome in the healing of lesions of endodontic origin. The main objective of this review paper is to define and characterize guided surgical endodontics as well as its benefits and drawbacks by reviewing the most recent relevant scientific literature. Methods: A literature search was conducted using multiple databases comprising of MEDLINE (via PubMed), EMBASE, and Web of Science. The terms used for the search were ‘guided endodontics’, ‘surgical endodontics’, and ‘endodontic microsurgery’. Results: In total, 1152 articles were obtained from the analysis of the databases. Unrelated articles from the available full text of 388 articles were excluded. A total of 45 studies were finally included in the review. Conclusions: Surgical-guided endodontics is a relatively new area of study that is still maturing. It has many applications such as root canal access and localization, microsurgical endodontics, endodontic retreatment, and glass fiber post removal. Additionally, it does not matter how experienced the operator is; the procedure can be completed for the patient in less time and provides greater accuracy and safety than conventional endodontics.

Novel method for augmented reality guided endodontics: an in vitro study

OBJECTIVE

The aim of this study is to evaluate the accuracy in endodontics of a novel augmented reality (AR) method for guided access cavity preparation in 3D-printed jaws.

METHODS

Two operators with different levels of experience in endodontics performed pre-planned virtually guided access cavities through a novel markerless AR system developed by a team among the authors on three sets of 3D-printed jaw models using a 3D printer (Objet Connex 350, Stratasys) mounted on a phantom. After the treatment, a post-operative high-resolution CBCT scan (NewTom VGI Evo, Cefla) was taken for each model and registered to the pre-operative model. All the access cavities were then digitally reconstructed by filling the cavity area using 3D medical software (3-Matic 15.0, Materialise). For the anterior teeth and the premolars, the deviation at the coronal and apical entry points as well as the angular deviation of the access cavity were compared to the virtual plan. For the molars, the deviation at the coronal entry point was compared to the virtual plan. Additionally, the surface area of all access cavities at the entry point was measured and compared to the virtual plan. Descriptive statistics for each parameter were performed. A 95% confidence interval was calculated.

RESULTS

A total of 90 access cavities were drilled up to a depth of 4 mm inside the tooth. The mean deviation in the frontal teeth and in the premolars at the entry point was 0.51 mm and 0.77 mm at the apical point, with a mean angular deviation of 8.5° and a mean surface overlap of 57%. The mean deviation for the molars at the entry point was 0.63 mm, with a mean surface overlap of 82%.

CONCLUSION

The use of AR as a digital guide for endodontic access cavity drilling on different teeth showed promising results and might have potential for clinical use. However, further development and research might be needed before in vivo validation to overcome the limitations of the study.

Comparison of Static and Dynamic Navigation in Root End Resection Performed by Experienced and Inexperienced Operators: An In Vitro Study

INTRODUCTION

This study aimed to compare the effects of static navigation (SN), a dynamic navigation system (DNS), and the freehand (FH) technique in root end resection and the differences between these effects according to the level of experience of the operator.

METHODS

Maxillary models reconstructed with Mimics software (Materialise, Leuven, Belgium) were 3-dimensionally printed and divided according to the experimental technique (FH, SN, or DNS) and the operator (experienced or inexperienced). SN was designed using 3-matic Medical software (Materialise) and printed, and a surgical approach plan for DNS was established and performed using DCARER (Suzhou, China) software. The accuracy, efficiency, and safety of the resections were assayed.

RESULTS

The length, angle, volume, and depth deviations of the root end resections were significantly lower in the SN and DNS group compared with the FH group. SN significantly improved the efficiency of both operators, whereas DNS only improved the efficiency of the inexperienced operator. No difference between the SN and DNS groups was found, except for the time required for the surgery. No mishaps occurred during surgery in the SN or DNS group. The number of mishaps with the FH technique when used by the inexperienced operator was significantly higher than that registered for the rest of the groups. No interaction effect between technique and operator experience level was detected.

CONCLUSIONS

Regardless of operator experience, both SN and DNS could improve the accuracy and safety of root end resection. SN significantly improved the chairside efficiency of both operators, whereas DNS was more helpful for the inexperienced operator.

Evaluation of a dynamic navigation system for endodontic microsurgery: study protocol for a randomised controlled trial

INTRODUCTION

Endodontic microsurgery is a very important technique for preserving the natural teeth. The outcomes of endodontic microsurgery largely depend on the skill and experience of the operators, especially for cases in which the apices are located far away from the labial/buccal cortical bone. A dynamic navigation system (DNS) could provide a more accurate and efficient way to carry out endodontic microsurgery. This study is devoted to comparing the clinical outcomes of the DNS technique with those of the freehand technique.

METHODS AND ANALYSIS

Sixteen patients will be randomly assigned to one of two groups. For the experimental group, the osteotomy and root-end resection will be performed under the guidance of dynamic navigation. For the control group, these procedures will be performed freehand by an endodontist. The required time to perform these procedures will be used to evaluate the efficiency of the DNS technique. A Visual Analogue Scale will be used to evaluate pain at 1, 3 and 7 days after endodontic microsurgery. Preoperative and postoperative cone beam CT scans will be obtained to evaluate the accuracy of the DNS technique. The global coronal deviations, the apical deviations and the angular deflection will be measured. The root-end resection length deviation, the root-end resection angle deviations, the extent of the osteotomy and the volume change of the buccal cortical bone will also be measured. Periapical radiographs will be obtained to evaluate the outcome at 1 year after microsurgery. The time to execute the study, including follow-ups, will last from 1 June 2022 to 31 December 2025.

ETHICS AND DISSEMINATION

The present study has received approval from the Ethics Committee of Peking University School and Hospital of Stomatology. The results will be disseminated through scientific journals.

TRIAL REGISTRATION NUMBER

ChiCTR2200059389.

Guided Endodontics: A Literature Review

The main objective of this paper is to perform an updated literature review of guided endodontics based on the available up-to-date scientific literature to identify and describe the technique, its benefits, and its limitations. Four electronic databases (PubMed, Scopus, Science Direct, and Web of Science) were used to perform a literature search from 1 January 2017 to 13 May 2022. After discarding duplicates, out of 1047 results, a total of 29 articles were eligible for review. Guided endodontics is a novel technique that is currently evolving. It is applied in multiple treatments, especially in accessing and locating root canals in teeth with pulp canal obliteration, microsurgical endodontics, and removing glass fiber posts in endodontic retreatments. In addition, it is independent of an operator's experience, requires less treatment time for the patient, and is more accurate and safer than conventional endodontics.

EDTA Combined with C-Pilot Files and Microultrasound for Root Canal Calcification: Dredging Effect and Safety Analysis

Objective

This paper discussed the dredging effect and safety of ethylenediaminetetraacetic acid (EDTA) combined with C-pilot files and microultrasound (mUS) on root canal calcification.

Methods

From October 2021 to January 2022, 132 patients with calcified root canals treated in our hospital were selected as the research subjects. Among them, 64 cases who received EDTA combined with C-pilot Files and mUS plus ultrasonic instruments to dredge calcified root canals were regarded as the research group (RG), and another 68 cases given ultrasonic instruments plus C-pilot files were regarded as the control group (CG). The root canal dredging time was recorded, and the dredging success rate and total success rate of different tooth positions and calcification sites were compared between groups. The clinical efficacy was assessed 6 months after treatment. Pain severity was evaluated by the Pain Intensity Numerical Rating Scale (PI-NRS) before (T0), during (T1), and after treatment (T2). Finally, the incidence of adverse reactions within one week after treatment was counted.

Results

RG was observed with statistically higher success rates of root canal dredging in different tooth positions and calcified sites than CG (P < 0.05). Besides, the total effective rate of treatment was 92.19% in RG, which was also higher compared with CG, while the root canal dredging time in RG was shorter than that in CG (P < 0.05). Increased NRS scores were found in both groups at T1, and the score in RG was significantly lower compared with that in CG. At T2, both groups showed a lower PI-NRS score than T1 but higher than T0, and the score at T2 was also lower in RG as compared to CG (P < 0.05). Moreover, the reduced incidence of adverse reactions were observed in RG compared with CG (P < 0.05).

Conclusions

EDTA combined with C-pilot files and mUS can effectively improve the dredging success rate of root canals obstructed by calcification, shorten the dredging time, and improve patient comfort, which is an effective method for clinical dredging of calcification obstructed root canals.

Present status and future directions - Guided endodontics

Luxation injuries and other stimuli may lead to a pulp canal obliteration (PCO). Even though the apposition of tertiary dentine is a sign of a vital pulp, in some cases root canal treatment is indicated in the long term due to apical periodontitis or pulpitis. Depending on the extent of PCO, root canal treatment may be challenging even for experienced and well-equipped endodontic specialists. The 'guided endodontics' (GE) technique was introduced 6 years ago as an alternative to conventional access cavity preparation for teeth with PCO and apical pathosis or irreversible pulpitis. Using three-dimensional radiological imaging such as cone-beam computed tomography and a digital surface scan, an optimal access to the orifice of the calcified root canal can be planned virtually with appropriate software. GE is implemented either with the help of templates analogous to guided implantology (= static navigation) or by means of dynamic navigation based on a camera-marker system. GE has emerged as a field of research in the last 6 years with very promising laboratory-based results regarding the accuracy of guided endodontic access cavities for both static and dynamic navigation. Clinical implementation seems to provide favourable results, but the evidence is mainly based on numerous case reports and a few case series. This narrative review aims to provide an update on the present status of GE and to identify relevant research areas that could contribute to further improvements of this technique.

Guided Endodontics: Static vs. Dynamic Computer-Aided Techniques—A Literature Review

(1) Background: access cavity preparation is the first stage of non-surgical endodontic treatment. The inaccuracy of this step may lead to numerous intraoperative complications, which impair the root canal treatment’s prognosis and therefore the tooth’s survival. Guided endodontics, meaning computer-aided static (SN) and dynamic navigation (DN) techniques, has recently emerged as a new approach for root canal location in complex cases. This review aims to compare SN and DN guided endodontics’ techniques in non-surgical endodontic treatment. (2) Methods: an electronic search was performed on PubMed, Scopus, and Cochrane Library databases until October 2021. Studies were restricted by language (English, Spanish and Portuguese) and year of publication (from 2011 to 2021). (3) Results: a total of 449, 168 and 32 articles were identified in PubMed, Scopus, and Cochrane Library databases, respectively, after the initial search. Of the 649 articles, 134 duplicates were discarded. In this case, 67 articles were selected after title and abstract screening, of which 60 were assessed for eligibility through full-text analysis, with one article being excluded. Four cross-references were added. Thus, 63 studies were included. (4) Conclusions: guided endodontics procedures present minimally invasive and accurate techniques which allow for highly predictable root canal location, greater tooth structure preservation and lower risk of iatrogenic damage, mainly when performed by less experienced operators. Both SN and DN approaches exhibit different advantages and disadvantages that make them useful in distinct clinical scenarios.

Treatment of Pulp Canal Obliteration Using a Dynamic Navigation System: Two Case Reports

Endodontic treatment of calcified canals presents a major challenge because of the high incidence of complications, such as perforation, canal geometry alteration, and loss of dental hard tissue. The dynamic navigation technique uses an optical tracking system for real-time navigation to guide the operator to drill according to the preoperative plan and obtain access to the calcified canals. This article describes in detail the use, advantages, disadvantages, and limitations of a novel dynamic navigation system (DNS) in two cases with severely calcified canals. The findings in these cases demonstrate that DNS is a promising technique for the location of calcified root canals.

Accuracy of Dynamic Navigation for Non-Surgical Endodontic Treatment: A Systematic Review

In recent years, the application of Guided Endodontics has gained interest for non-surgical endodontic treatment and retreatment. The newest research focuses on the accuracy of Dynamic Navigation (DN). This article systematically reviewed existing data on the accuracy of non-surgical endodontic treatment procedures that were completed using DN. Following the PRISMA criteria, an electronic database search was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Studies comparing the accuracy of non-surgical endodontic treatment using DN and the conventional freehand technique were eligible. The literature search resulted in 176 preliminary records. After the selection process six studies were included. The risk of bias was evaluated using the modified Cochrane Collaboration Risk of Bias 2.0 tool. Five studies examined the aid of DN for planning and executing endodontic access cavities, and one for fiber post removal. In two studies, endodontic access cavities were performed in teeth with pulp canal obliteration. The main outcomes that were measured in the included studies were preparation time, global coronal entry point and apical endpoint deviations, angular deviation, tooth substance loss, qualitative precision, number of unsuccessful attempts or procedural mishaps. The risk of bias was rated from low to raising some concerns. Overall, DN showed increased accuracy compared to the freehanded technique and could be especially helpful in treating highly difficult endodontic cases. Clinical studies are needed to confirm the published in vitro data.

Present status and future directions - Minimal endodontic access cavities

In the last decades, the move of Medicine towards minimally invasive treatments is notorious and scientifically grounded. As Dentistry naturally follows its footsteps, minimal access preparation also became a trend topic in the endodontic field. This procedure aims to maximize preservation of dentine tissue, backed up by the idea that this is an effective way to reduce the incidence of post-treatment tooth fracture. However, with the assessment of the body of evidence on this topic, it is possible to observe some key-points (a) the demand for nomenclature standardization, (b) the requirement of specific tools such as ultra-flexible instruments, visual magnification, superior illumination, and three-dimensional imaging technology, (c) minimally invasive treatment does not seem to affect orifice location and mechanical preparation when using adequate armamentarium, but it (d) may impair adequate canal cleaning, disinfection, and filling procedures, and also (e) it displays contradictory results regarding the ability to increase the tooth strengthen compared to the traditional access cavity. In spite of that, it is undeniable that methodological flaws of some benchtop studies using extracted teeth may be responsible for the conflicting data, thus triggering the need for more sophisticated devices/facilities and specifically designed research in an attempt to make it clear the role of the access size/design on long-term teeth survival. Moreover, it is inevitable that a clinical approach like minimal endodontic access cavities that demands complex tools and skilled and experienced operators bring to the fore doubts on its educational impact mainly when confronted with the conflicting scientific output, ultimately provoking a cost-benefit analysis of its implementation as a routine technique. In addition, this review discusses the ongoing scientific and clinical status of minimally invasive access cavities aiming to input an in-depth and unbiased view over the rationale behind them, uncovering not only the related conceptual and scientific flaws, but also outlining future directions for research and clinical practices. The conclusions attempt to skip from passionate disputes highlighting the current body of evidence as weak and incomplete to guide decision making, demanding the development of a close-to-in-situ laboratory model or a large and well-controlled clinical trial to solve this matter.