Root-end Resection Research Articles

Application of Real-time Augmented Reality-guided Osteotomy and Apex Location in Endodontic Microsurgery: A Surgical Simulation Study Based on 3D-printed Alveolar Bone Model

IntroductionAugmented reality (AR) is a novel visualization technique in which pregenerated virtual 3D content is superimposed on surgical sites. This study aimed to validate the viability of AR-guided endodontic microsurgery (ARG) and compare the changes in objective and subjective outcomes of surgical simulation using ARG and freehand (FH) endodontic microsurgery on customized 3D-printed models. MethodsWe created and printed a customized 3D alveolar bone model with artificial periapical lesions (APLs) based on cone-beam computed tomography. Eight models with 96 APLs were equally divided into ARG and FH groups. We planned surgical trajectories on rescanned printed models. Four inexperienced residents (IRs) performed ARG and FH on the models and completed pre and intraoperative confidence questionnaires for the subjective outcome. Postoperative cone-beam computed tomography scans of the models were reconstructed and analyzed, and all procedures were timed. We used pairwise Wilcoxon rank sum tests to compare objective outcomes. Kruskal–Wallis tests and post hoc pairwise Wilcoxon rank sum tests were used to compare subjective outcomes. ResultsCompared to the FH group, the ARG group significantly reduced deviation of the volume of bone removal, root-end resection, and deviation of bevel angle, with improved confidence of the IRs (P < .05); it also significantly increased surgical time and volume of unremoved APL (P < .05). ConclusionsWe customized an APL model through 3D printing and developed and validated a low-cost AR application framework, based on free AR software, for endodontic microsurgery. ARG allowed IRs to perform more conservative and precise surgical procedures with enhanced confidence.

Analysis of the accuracy of a dynamic navigation system in endodontic microsurgery: A prospective case series study

ObjectivesTo evaluate the accuracy of a dynamic navigation system (DNS) for guided osteotomy and root-end resection during endodontic microsurgery (EMS) and assess its prognosis. MethodsNine patients who met inclusion criteria underwent DNS-guided EMS. Osteotomy and root-end resection were performed with assistance of DNS (DHC-ENDO1, DCARER Medical Technology, Suzhou, China). The preoperative virtually planned path and postoperative cone-beam computed tomography images were superimposed using DNS software. Accuracy was assessed based on deviations in the platform, apex, and angle of the osteotomy, as well as in the length and angle of the root-end resection. Follow-up evaluations were performed after at least a year postoperatively. ResultsAmong the nine patients (11 teeth with 12 roots), the mean platform, apex, and angular deviation of the osteotomy were 1.05 mm, 1.2 mm, and 6.24°, respectively. The mean length and angle deviation of the root-end resection were 0.46 mm and 4.9°, respectively. Significant differences were observed according to tooth position. The platform and apex deviated significantly less in the posterior than in the anterior teeth (p < .05). No significant differences were observed according to arch type, side, and depth of the surgical path (p > .05). Eight patients were evaluated after at least a year postoperatively; clinical and radiographic evaluation revealed a 90% success rate (9/10 teeth). ConclusionsThis study demonstrated high accuracy of DNS in EMS. Furthermore, DNS-guided EMS had a success rate similar to that of freehand EMS over a short-term follow-up. Further study with a larger sample size is necessary. Clinical significanceThe present novel DNS technology is a viable method for guided osteotomy and root-end resection in EMS. Clinical trial registration numberChiCTR2100042312

Surgical removal of periapical pathology with root end resection

In children and young adults, traumatic dental injuries (TDIs) to permanent teeth are common. Of all dental injuries, crown fractures and luxations of these teeth are the most frequent. For a successful outcome, accurate diagnosis, treatment planning, and follow-up are critical. This article presents a case report series of surgical management of traumatic injury with periapical lesion with rooth end resection using root end filling materials.

Failure case analysis during each stage of endodontic microsurgery: A retrospective study based on clinical databases

Introduction: This study aimed to investigate the most important stage of endodontic surgery by examining failed cases and analyzing the cause of failure during each stage of the procedure. Materials and Methods: We searched the clinical database of the Department of Conservative Dentistry, Dankook University, for patients with a history of endodontic microsurgery (EMS) performed between March 2017 and February 2021. Among the 428 patients who underwent EMS, those with a history of endodontic surgery were included. All surgical procedures were performed using a microscope, and the previously resected root surface or the root surface to be resected was inspected during surgery. The patients were followed up at 6 and 12 months and every year thereafter. Results: A total of 68 cases were included for analysis. The most common cause of failure was incomplete root-end filling (24 cases, 35.3%), and mineral trioxide aggregate (MTA) was used in 17 cases. This was followed by no root-end management after root-end resection (33.8%), incorrect root-end preparation (19.1%), inspection error (7.4%), cracks (2.9%), and incomplete root-end resection (1.5%). After resurgery, 41 were followed up for more than 1 year (recall rate, 60.3%), and the success rate was 85.4% (35 out of 41 cases). Conclusions: Root-end filling was shown to be the most important stage in determining the outcome, even when using the biocompatible material, MTA.

Elevated Cytokine Levels in Gingival Crevicular Fluid of Teeth with Apical Periodontitis

IntroductionBiomarkers assayed from gingival crevicular fluid (GCF) are a potential tool for endodontic diagnosis and for monitoring treatment response. This cross-sectional study measured cytokines in GCF from teeth with apical periodontitis and evaluated their relationship with preoperative pain and other clinical findings. MethodsParticipants presenting for root-end resection surgery due to apical periodontitis diagnosis (n = 56) underwent standardized clinical testing and completed preoperative questionnaires. GCF from diseased and control teeth were collected, processed, and analyzed. Mann-Whitney U and Wilcoxon tests were used to examine the cytokine levels in diseased compared to healthy control teeth. We also assessed the relationship of cytokine levels with clinical findings. ResultsInterleukins (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, interferon-γ, and tumor necrosis factor-⍺ (TNF-⍺) were detected in GCF. TNF-⍺ levels were significantly higher in GCF collected from diseased versus control teeth (P = .02) and increased IL-1β levels in diseased teeth were detected (P = .06). Lower IL-10 levels were observed in teeth with a sinus tract and/or swelling compared to teeth without a sinus tract and/or swelling (P = .08). Cytokine levels did not clearly relate to the presence of pain. ConclusionsElevated levels of proinflammatory cytokines, including TNF-⍺ and IL1- β, were detected in GCF from diseased teeth compared to the healthy controls. Additional studies are needed to further investigate the utility of these biomarkers for objectively evaluating periradicular pathology.

Comparison of a Novel Static Computer-aided Surgical and Freehand Techniques for Osteotomy and Root-end Resection

IntroductionThis study compared the accuracy and efficiency of a novel static computer-aided surgical technique using a 3-dimensional (3D)-printed surgical guide (3D-SG) with a fully guided drill protocol (3D-SG FG) to the freehand (FH) osteotomy and root-end resection (RER). MethodsForty-six roots from 2 cadaver heads were divided into 2 groups: 3D-SG FG (n = 23) and FH (n = 23). Cone-beam computed tomographic scans were taken preoperatively and postoperatively. The endodontic microsurgery was planned in Blue Sky Bio software, and the 3D-SG was designed and 3D printed. The osteotomy and RER were conducted using a guided twist drill diameter of 2 mm and an ascending tapered drill with diameters of 2.8/3.2, 3.2/3.6, 3.8/4.2, and 4.2 mm with respective guided drill guides. Two-dimensional and three-dimensional virtual deviations and angular deflection were calculated. Linear osteotomy measures and root resection angle were obtained. The osteotomy and RER time and the number of mishaps were recorded. ResultsTwo-dimensional and three-dimensional accuracy deviations and angular deflection were lower in the 3D-SG FG protocol than in the FH technique (P < .05). The height, length, and depth of the osteotomy and root resection angle were less in the 3D-SG FG protocol than in the FH technique (P < .05). The osteotomy and RER time with the 3D-SG FG protocol were less than the FH method (P < .05). ConclusionsWithin the limitations of this cadaver-based study using denuded maxillary and mandibular jaws, 3D-SG FG protocol showed higher accuracy than FH osteotomy and RER. Moreover, the 3D-SG FG drill protocol significantly reduced the surgical time.

Evaluation of the influence of dentin on radiopacity of retrograde filling materials : An In-vitro study

Aim: To assess and compare the influence of dentin on radiopacities of five retrograde filling materials and subjecting the samples to radiographic interpretation by various endodontists. Materials and Methodology: Fifty extracted incisors for non endodontic reasons were selected and sectioned to standardize the working length to 16mm.Root canal treatment was done and rootend resection was carried out with a fissure bur under constant water spray. 3mm deep cavities were prepared on the resected root with a straight fissure bur. Samples were randomly divided into five groups. Group 1- Amalgam, Group 2- GIC, Group 3- MTA (Mineral trioxide aggregate), Group 4- Biodentin, Group 5- Thermoplasticized gutta percha. Retrograde filling was done in the prepared cavities and also packed into plastic straws. Samples were stored at 100% humidity for 24 hrs and the radiodensity was measured using a radiodensity tool.The digitized images were selected randomly and a questionnaire was prepared using google form. This form was circulated among the endodontists and the responses were recorded. The data was Statistically analyzed using one way analysis of variance and post hoc tukey test. Results: Dentin did not show any influence on the radioopacity of root end filling materials amalgam (P-1.00), thermoplasticized gutta-percha (P- 0.18). radiopacity was significantly reduced for GIC (P- 0.01), MTA (P &lt; 0.001), Biodentin (P- 0.02) Radiodensity of amalgam was highest compared to all other groups tested, and biodentin was found to exhibit lowest radiodensity. 92% of participants interpreted amalgam, 80% interpreted biodentin, 67% identified thermoplasticized gutta-percha, 50% identified MTA and GIC correctly. Conclusion: The root end filling materials showed varying degree of radiopacity. More number of endoodntists were able to identify amalgam and biodentin correctly. Radiopacity was significantly reduced for GIC, MTA, Biodentin when placed as root end filling materials. Keywords: Apicoectemy, Radiopacifiers, Root-end filling materials, radiodensity tool.

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

IntroductionThis 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. MethodsMaxillary 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. ResultsThe 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. ConclusionsRegardless 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.

Extraoral Root-End Resection May Promote Pulpal Revascularization in Autotransplanted Mature Teeth—A Retrospective Study

Tooth germ autotransplantation of open apices of the teeth exhibits high pulpal healing rates, whereas that of mature permanent teeth normally causes irreversible pulpal necrosis. Extraoral root-end resection (EORER) during transplantation may promote pulpal revascularization (PRV) in transplanted mature teeth and reduce endodontic treatment requirement. This study compared the primary outcomes of survival rates, PRV, and root resorption and determined relevant confounders in autotransplanted mature and immature teeth. The medical charts of consecutive patients who underwent tooth autotransplantation between January 2017 and March 2021 were evaluated. Teeth with a documented follow-up of at least 1 year were included. During the study period, 59 teeth were transplanted in 44 patients. Overall, 2 teeth were excluded owing to missing data; 57 teeth were analyzed, including 25 mature teeth additionally treated with EORER. After a mean follow-up of 21.2 ± 16.1 months, no significant differences in primary outcomes were detected. Fifty-five teeth remained in situ (96.5%), and radiological signs of root resorption were detected in 9/57 teeth (15.8%). PRV was positive in 54/57 teeth (94.7%). Surgical duration and PRV failure were significantly associated with high incidences of root resorption. Mature teeth autotransplantation with EORER yielded similar results to immature teeth autotransplantation and is a feasible treatment option. Long surgery and failed revascularization increased root resorption rates. More factors should be evaluated in larger trials with longer observation periods.

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

IntroductionEndodontic 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...

Surface Morphological Analysis and Evaluation of the Sealing Ability of a Nanoparticle-Incorporated Hydraulic Root-End Cement

Since the inception of mineral trioxide aggregate (MTA), calcium silicate cements have emerged to dominate in the dental sector, mainly due to their hydraulic property. The ability of such cements to set in the presence of moisture is their most significant characteristic. A plethora of products based on hydraulic silicate cement constitution have recently entered the market; these items can be seen as MTA improvements attempting to minimize MTA’s shortcomings. Despite any possible benefits, the capacity to seal in an endodontic root repair material is, however, the most significant aspect determining its success. An experimental calcium silicate-based cement incorporated with nanosilver was fabricated to evaluate the sealing ability and to compare with the existing commercially available MTA. Teeth were decoronated and root canal treatment was performed. Root-end resection and cavity preparation, followed by root-end filling was done with the materials. Confocal scanning microscopy was used to assess the extent of rhodamine dye leakage in the root-end cavities. The results showed that both the experimental nanosilver incorporated calcium silicate-based cement and Mineral Trioxide Aggregate showed microleakage under a confocal microscope.

Taxonomic abundance in primary and secondary root canal infections.

To evaluate the root canal microbiome composition in cases of primary and secondary apical periodontitis. Thirty-nine samples from patients with primary root canal infections obtained before root canal treatment, and 40 samples obtained during root-end resection procedures from previously filled cases with apical periodontitis were evaluated using 16S rRNA next-generation sequencing analysis (NGS). Demographic and clinical factors included age, sex, infection type, percussion sensitivity, and presence of pain. Differences in abundances of genera were evaluated using Kruskal-Wallis test. Alpha and beta diversity indices were calculated using mothur. The Shannon and Chao1 indices were used to measure alpha diversity. The Bray-Curtis dissimilarity was used to measure beta diversity. Differences in community composition were evaluated using analysis of similarity (ANOSIM) with Bonferroni correction for multiple comparisons. Significantly fewer operational taxonomic units values were observed from samples from secondary infections (p < .0001). While no significant differences were observed in the Chao 1 index between primary and secondary infections, the Shannon alpha diversity was significantly lower in secondary relative to primary infections (p=.008). Among samples, sex, age (adult vs. older adult), percussion sensitivity, and presence of pain all showed no significant effects on community composition via an analysis of similarity (ANOSIM). However, community composition was significantly different depending on whether the sample was from a primary or secondary infection (R=.051, p=.03). Nine microbial genera comprised the predominant taxa observed among samples (>3.3%) and included Parvimonas, Fusobacterium, Campylobacter, Arachnia, Eubacterium, Prevotella, Peptostreptococcus, Fretibacterirum, and Pseudoramibacter. Significantly greater relative abundances of Prevotella, Peptostreptococcus, Veillonella, Lactucaseibacillus, and Dialister were observed in primary infections. Primary endodontic infections are more diverse than secondary infections. The microbial composition is not associated with the clinical manifestations of apical periodontitis.

Outcome of intentional replantation of endodontically treated teeth with periapical pathosis: A systematic review and meta-analysis.

The purpose of the present review was to examine success, survival and failure following intentional replantation of endodontically treated teeth with existing periapical pathosis and to determine the factors that might affect the outcome of replantation. Clinical trials, longitudinal studies, case series with >10 cases and at least 1-year follow-up were included. The average rate of success following intentional replantation was 77.23%. Meta-analysis revealed the mean weighted survival to be 85.9% (95% CI: 79.6-91.2) Common complications include inflammatory root resorption (0%-27%) and ankylosis (0%-25%). Variables influencing successful outcome include extra alveolar dry time <15 min; root-end resection (2-3 mm) and cavity preparation (3 mm); manipulation of the tooth using the crown only; and use of an appropriate storage media. The review concludes that intentional replantation is a viable treatment option with acceptable survival rates for endodontically treated teeth with periapical pathosis.

Stress Distribution on Trephine-Resected Root-end in Targeted Endodontic Microsurgery: A Finite Element Analysis

IntroductionThis study aimed to determine if stress distribution from occlusal loads after targeted endodontic microsurgery (TEMS) differed for trephine-resected flat and curved root-ends, with and without bone graft. MethodsFinite element analysis models were constructed from cone-beam computed tomography data of a TEMS-treated maxillary central incisor. Models included flat and curved resected root-ends, with and without apical bone graft, and normal or root canal filled controls. In centric occlusion, axial force was directed on mesial and distal lingual marginal ridges at 120° angle. For lateral excursion, additional mesiodistal forces were applied from centric occlusion. For edge biting, axial force was directed on the incisal edge. Under occlusal loads, stress distribution patterns on tooth and root-end circumference were analyzed. ResultsIn normal and root filled controls, occlusal stress was distributed on labial and palatal root surfaces, concentrated in the labial cervical area, and maximized at the apex. For resected root-ends, occlusal loads concentrated stress on the labial cervical area. With bone graft, maximum stress concentration shifted to the apex, which implied stress relief and dispersion from the cervical root area. Stress patterns on the root-end were more widely spread in models with apical bone graft, whereas curved root-end showed stress concentrating arc especially when without apical bone support. The mean stress values on root-end circumference were significantly higher in curved than flat root-end (P < .05), especially with apical bone support (P < .05). ConclusionsOcclusal stress patterns on a maxillary central incisor were markedly affected by root-end resection configuration and apical bone support. Trephine-resected curved root-end had stress pattern concentrated on its circumference. Curved and flat root-ends had labial cervical stress that was relieved by bone graft. TEMS resected root-ends should be flattened and bone grafted to disperse stress from occlusal loads.

Effect of laser irradiation protocols on temperature, roughness, and morphology of the root surface after root-end resection

This study evaluated the effect of laser irradiation protocols using Thera Lase Surgery (TL), at 2.5 W (2.5) or 2.7 W (2.7), and Gemini (GE), at 1.2 W (1.2) or 1.5 W (1.5) of potency, on the root-end resection surface, in relation to external root temperature, roughness, and surface morphologic changes after the treatments, in the areas near to the root canal (RC) or external root surface (ER). Fifty teeth were endodontically treated and the root-end were resected 3 mm away from the root apex. The specimens were randomized into 5 groups (n = 10), according to the laser irradiation protocol: Control (CO-DW) without irradiation; (TL-2.5) Thera Lase Surgery, 2.5 W; (TL-2.7) Thera Lase Surgery, 2.7 W; (GE-1.2) Gemini, 1.2 W; and (GE-1.5) Gemini, 1.5 W. The external root temperature change was obtained through the difference between the highest value observed during the irradiation and the value at the beginning of the treatment. The surface roughness (µm) was analyzed by confocal laser microscopy and the apical surface morphology was evaluated by scanning electron microscopy, in RC or ER. The temperature change was similar between the irradiation protocols (p > 0.05). CO-DW and GE-1.5 provided the lowest surface roughness (p < 0.05), regardless of the analyzed area. TL-2.7 and GE-1.7 showed more uniform on apical resected morphology and a higher incidence of dentinal tubules occlusion, but only near the root canal (p < 0.05). Root-end resected surface submitted to TL-2.7 and GE1.7 irradiation protocols are more homogeneous and shown higher incidence of closed dentinal tubules near to root canal, despite providing a surface roughness.

Comparison of the Accuracy and Efficiency of a 3-Dimensional Dynamic Navigation System for Osteotomy and Root-end Resection Performed by Novice and Experienced Endodontists

IntroductionThe aim of the study is to investigate whether the 3-dimensional dynamic navigation system (3D-DNS) can improve experienced endodontists' (EEs') and novice endodontists' (NEs’) accuracy and efficiency in osteotomy and root-end resection (RER) and to verify that the 3D-DNS enables NEs to perform osteotomy and RER as accurately and efficiently as EEs. MethodsSeventy-six roots in cadaver heads were randomly divided into 4 groups: 3D-DNS-NE, 3D-DNS-EE, freehanded (FH)-NE, and FH-EE (all, n = 19). Cone-beam computed tomography scans were taken preoperatively and postoperatively. Osteotomy and RER were planned virtually in the X-guided software (X-Nav Technologies, Lansdale). Accuracy was calculated by measuring the 2-dimensional and 3D virtual deviations and angular deflection using superimposing software (X-Nav technologies). Efficiency was determined by the time of operation and the number of mishaps. ResultsAccuracy deviations were significantly fewer in the 3D-DNS-EE group than those in the FH-EE group (P < .05). We found less 2-dimensional and 3D accuracy deviations comparing the 3D-DNS-NE group to the FH-NE group (P < .05). The time required for osteotomy and RER with the 3D-DNS was ∼ ½ of that required for the FH method for both EEs and NEs (P < .05). We found no difference in the number of mishaps between the 3D-DNS and FH groups for EEs and NEs (P > .05). ConclusionsThe 3D-DNS improved EEs' and NEs' accuracy and efficiency in osteotomy and RER. The NEs were as efficient as the EEs using the 3D-DNS. Notably, the 3D-DNS improved the NEs’ accuracy compared to the FH method, but the 3D-DNS did not enable the NEs to perform osteotomy and RER as accurately as the EEs.

Sealing Ability of Bioactive Root-End Filling Materials in Retro Cavities Prepared with Er,Cr:YSGG Laser and Ultrasonic Techniques.

The aim of this in vitro study was to compare the apical sealing ability of total fill bioceramic root repair material (BC-RRM) and mineral trioxide aggregate (MTA), regarding the retrograde preparation technique used: ultrasonic or erbium, chromium: yttrium, scandium, gallium, or garnet (Er,Cr:YSGG) laser. The study sample consisted of 48 human single-rooted teeth. After root-end resection, the samples were divided into two groups, according to the retrograde preparation technique used: Group 1: ultrasonic; Group 2: Er,Cr:YSGG laser. In each group, half of the retrograde cavities were filled with BC-RRM, and the other half were filled with MTA. The specimens were mounted in tubes and sterilized in plasma. The root canals were inoculated with Enterococcus faecalis, and the tubes were filled with fetal bovine serum, leaving the apical part of the root in the serum. After 30 days, the canals were sampled and cultured, and the colony forming units (CFUs) were counted with the additional polymerase chain reaction (PCR analysis). There was no significant difference between ultrasonic groups and the Er,Cr:YSGG-MTA group, regarding the number of CFUs (p > 0.05). The Er,Cr:YSGG-BC-RRM group showed the highest number of remaining viable bacteria (p < 0.001). Both filling materials filled in ultrasonic preparations presented similar sealing abilities. The BC-RRM showed more leakage when used in retro cavities prepared with the Er,Cr:YSGG laser.

Guided endodontics by Niraj Kinariwala and Lakshman Samaranayake, editors. Cham, Switzerland: Sringer Nature; 2021

Endodontic guides (synonyms: endoguides, endodontic templates, 3-dimensional endoguides) guarantee two things: minimal invasiveness of the procedure and high level accuracy. That is why two editors, Niraj Kinariwala and Lakshman Samaranayake, united another 18 contributors from totally 6 countries (Austria, Brazil, China, Denmark, Hungary, and India) bringing to the world Guided Endodontics. The textbook consists of 10 Chapters; all of them are dedicated to planning, manufacturing and application of all types of endodontic guides: (1) types depended upon their use in endodontic treatment (non-surgical and surgical guides), (2) types depended upon their support, and (3) types from classification of surgical endodontic templates. Perfect illustrations: computed tomography (CT), micro-CT data, virtual surgical planning, digital workflow, intraoperative images, and control X-rays immerse the reader in the smallest details of the guided treatment. Chapter 8, “Static Guided Approach in Surgical Endodontics” perfectly describes guided microscopic root-end resection using stereolithographic manufacturing what is extremely useful in modern practice. In summary, this textbook is a phenomenal chance for every endodontists to absorb all we need to know about state of the art principles and techniques of guided endodontics. I can honestly say that with profound knowledge and appropriate implementation of these techniques any practice limited to endodontics will reach the highest level of modern endodontic specialty.

Present status and future directions: Minimally invasive root canal preparation and periradicular surgery.

Inspired by several other surgical disciplines, the quest for treating diseases through minimally invasive procedures has permeated endodontics, but not without controversy. Indeed, pulp amputation/excision and root-end resection are akin to surgical procedures elsewhere in the body and therefore, an increasing number of studies have addressed the "potential" to adopt such minimally invasive procedures in root canal treatment, with the larger goal of conserving tooth tissue for long-term survival of treated teeth. Yet, it is undeniable that this "trend" has been met with immense resistance with unclear evidence to strongly support or refute this philosophy. One may view root canal treatment as having two important procedural parts: (i) gaining access to the root canal and (ii) achieving clean root canals to remove the necrotic/infected or irreversibly inflamed tissues and then fill the space that was occupied by the pulp tissue and subsequently enlarged during cleaning and shaping, which should result in two key long-term outcomes: (i) healing of periradicular periodontitis and (ii) survival/retention of the tooth. Whilst a lot of interest has been directed towards gaining access through minimally invasive cavity designs, it is surprising that little effort has been expended on studying minimally invasive root canal preparation or surgical intervention. The aim of this review is not to promote or denigrate these philosophies, but to provide a balanced overview of the concepts, currently available evidence and future perspectives on minimally invasive endodontics from the context of root canal preparation and surgical endodontics. Specific attention is given to the role of modern irrigation strategies in potentially improving canal cleanliness even when canals are minimally prepared and the areas of research that are currently lacking in this topic.

Real-time 3-dimensional Dynamic Navigation System in Endodontic Microsurgery: A Cadaver Study

This study evaluated the accuracy and efficiency of the 3-dimensional dynamic navigation system (3D-DNS) to perform minimally invasive osteotomy (MIO) and root end resection (RER) in endodontic microsurgery (EMS) and investigated the viability of root end cavity preparation (RECP) and root end fill (REF) in MIO. Forty-eight tooth roots were divided in cadaver heads into 2 groups: 3D-DNS (n=24) and freehand (n=24). Cone-beam computed tomographic scans were taken before and after surgery. First, virtual 3D-DNS accuracy was verified using 3 outcome measures: 2-dimensional and 3-dimensional virtual deviations and angular deflection. Second, the accuracy of 3D-DNS for performing MIO was investigated in 2 outcome measures: osteotomy size and volume. Third, the 3D-DNS accuracy was determined for RER in 3 outcomes: resected root length, root length after resection, and resection angle. The viability of RECP and REF was investigated and REF depth and volume measured as well, and procedural time and the number of mishaps were recorded. Two- and 3-dimensional virtual deviations and the angular deflection were lower in the 3D-DNS group than the freehand group (P<.05). Osteotomy height, length, and volume were all reduced when using 3D-DNS (P<.05). The resection angle was lower for 3D-DNS (P<.05). RECP and REF were completed in 100% of the roots. The REF depth achieved was ∼3mm. Osteotomy time, RER time, and the total procedure time were all significantly shortened using 3D-DNS (P<.05). 3D-DNS enabled our surgeon to perform accurate and efficient EMS with minimally invasive osteotomy and RER. The surgeon was also able to conduct RECP with adequate REF in minimally invasive osteotomy performed using 3D-DNS guidance.