Endodontic Microsurgery With an Autonomous Robotic System: A Clinical Report

INTRODUCTION

Endodontic microsurgery (EMS) requires minimally invasive osteotomy and accurate root-end resection, which can be challenging in many instances. Evidence suggests that autonomous robotic systems can significantly enhance the precision of dental implantation. The aim of this case report is to introduce a novel EMS technique that employs robot-guided osteotomy and root resection procedures.

METHODS

A 59-year-old man was diagnosed with previously treated, symptomatic apical periodontitis in the mandibular left first molar. Patient data were used to integrate a digital model into preoperative planning software to design the surgical plan. The robotic system utilizes spatial alignment techniques for registration, guiding the robotic arm to autonomously perform a 3-mm osteotomy and root-end resection, based on the surgical plan. After completing the resection, the clinician confirmed the absence of cracks or root fractures and subsequently performed root-end preparation and filling under a microscope.

RESULTS

To the best of our knowledge, this case marks the first use of autonomous robotic assistance in EMS.

CONCLUSIONS

Utilizing an autonomous robotic system could enable precise apicoectomy in patients with intact cortical plates, thus facilitating successful EMS procedures. This has the potential to minimize errors caused by operator inexperience and mitigate the risks associated with excessive bone removal.

Stabilizing bony plate in guided endodontic surgery using an innovative approach

Endodontic microsurgery in tandem with advanced radiographic techniques has led to the emergence of guided surgeries. Preservation of the cortical bone to enhance the healing and stabilization of tissues surrounding the tooth of concern can now be facilitated by bone cement used in the field of orthopedics. This case report details a guided endodontic surgery technique in 17 years old where a traumatic infliction leads to a phoenix abscess. The technique elaborated emphasizes on the three-dimensional printing of a surgical template with the help of cone-beam computed tomography, followed using a medical-grade bone cement in the most minimal manner to reposition the buccal cortical bone. A 12-month-old follow-up revealed the patient to be asymptomatic with a flawless periapical region radiographically. This case testifies that the optimum use of available biomedical material in surgical endodontics can assure a predictable prognosis.

Augmented Reality-Guided Apicoectomy Based on Maxillofacial CBCT Scans

Implementation of augmented reality (AR) image guidance systems using preoperative cone beam computed tomography (CBCT) scans in apicoectomies promises to help surgeons overcome iatrogenic complications associated with this procedure. This study aims to evaluate the intraoperative feasibility and usability of HoloLens 2, an established AR image guidance device, in the context of apicoectomies. Three experienced surgeons carried out four AR-guided apicoectomies each on human cadaver head specimens. Preparation and operating times of each procedure, as well as the subjective usability of HoloLens for AR image guidance in apicoectomies using the System Usability Scale (SUS), were measured. In total, twelve AR-guided apicoectomies on six human cadaver head specimens were performed (n = 12). The average preparation time amounted to 162 (±34) s. The surgical procedure itself took on average 9 (±2) min. There was no statistically significant difference between the three surgeons. Quantification of the usability of HoloLens revealed a mean SUS score of 80.4 (±6.8), indicating an "excellent" usability level. In conclusion, this study implies the suitability, practicality, and simplicity of AR image guidance systems such as the HoloLens in apicoectomies and advocates their routine implementation.

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.

Three-dimensional printing: A revealing pathway to an unpredictable maze

Three-dimensional (3D) technology has gained wide acceptance in dentistry. It has been used for treatment planning and surgical guidance. This case report presented a novel treatment approach to remove and preserve the cortical bone and root-end resection during periapical surgery with the help of cone-beam computed tomography (CBCT), computer-aided design, and 3D printing technology. A 22-year-old male patient presented with a large periapical lesion in the right maxillary central and lateral incisors was referred for endodontic surgery. The data acquired from a preoperative diagnostic CBCT scan and an intraoral scan were uploaded into surgical planning software and matched. A template that could be used to locate root ends and lesion areas was virtually designed based on the data and was fabricated using a 3D printer. With the guidance of the template, the overlying cortical bone was precisely removed and preserved, and apicectomy was performed. The patient was clinically asymptomatic at a 6-month follow-up review. Six months after the surgery, the lesion was healing well, and no periapical radiolucency was observed on radiographic examination. The digitally designed directional template worked in all aspects to facilitate the periapical surgery as anticipated. The root ends were accurately located and resected. The surgical procedure was simplified, and the treatment efficiency was improved. This technique minimized the damage and reduced iatrogenic injury.

Crack Formation Following Root-End Preparation in Roots with the Butterfly Effect

Objective:

To investigate apical cracks in roots that exhibit the butterfly effect and that have undergone apical resection and ultrasonic root-end cavity preparation. The effect of the obturation material was also studied.

Methods:

Forty extracted single-rooted teeth were decoronated at the cemento-enamel junction. Roots were viewed under a light microscope and coded according to the presence or absence of the butterfly effect. Canals were prepared using ProTaper Next instruments to size X3 and assigned to two obturation groups (gutta-percha and AH Plus, and ProRoot MTA alone). Each contained twenty roots (10 with the butterfly effect and 10 without the butterfly effect). Roots were resected perpendicular to their long axis, 3 mm from the apex, and cavities were cut using ultrasonic retrotips. Resin replicas were used for crack imaging from scanning electron micrographs. Statistical analyses were performed using Stata 13.1 (StataCorp, College Station, TX, USA).

Results:

Cracks occurred more frequently in teeth with the butterfly effect (80%), with this difference being significant (P=0.001). Most cracks (73%) ran buccolingually. Teeth obturated with MTA developed fewer cracks compared to those obturated with GP and sealer.

Conclusion:

Root-ends with the butterfly effect had a significantly higher number of buccolingual cracks following resection and ultrasonic root-end preparation. This might explain the development of some vertical root fractures, which usually run buccolingually. Canal obturation with MTA may be protective.

Endoscopic Evaluation of Cut Root Faces and Histologic Analysis of Removed Apices Following Root Resection: A Clinical Study

Objective:

To evaluate the resection plane after root-end resection during apical surgery using endoscopy.

Methods:

Following apicectomy of 69 roots, the cut root faces were inspected with a rigid endoscope for the presence of unfilled areas of the root canal space, gaps between the obturated root canal and dentinal wall, isthmi, ‘opaque’ dentine and cracks. Endoscopic pictures were captured and assessed using a 12-sectorn transparent grid for determination of location of the studied elements. Furthermore, the removed apices were examined histologically (n=47). The surfaces of the removed apices opposite the cut root faces were histologically analysed for the same outcome measures.

Results:

Endoscopy revealed the following findings: opaque dentine in 84.1%, unfilled parts of the root canal system in 59.4%, gaps between the existing root canal filling and dentinal walls in 49.3%, and cracks in 10.1% of cases. With regard to isthmi, histology of the removed apices demonstrated an isthmus in two-thirds of those seen with endoscopy at the root end. Ramifications were histologically observed only in 6 root apices.

Conclusion:

The studied elements may cause failure of the root canal treatment, and conventional root canal retreatment or apical surgery may be indicated. The clinical significance of opaque dentine with regard to tooth prognosis after apical surgery remains unclear and warrants further research.

Changes of Root Length and Root-to-Crown Ratio after Apical Surgery: An Analysis by Using Cone-beam Computed Tomography

INTRODUCTION

Apical surgery is an important treatment option for teeth with post-treatment periodontitis. Although apical surgery involves root-end resection, no morphometric data are yet available about root-end resection and its impact on the root-to-crown ratio (RCR). The present study assessed the length of apicectomy and calculated the loss of root length and changes of RCR after apical surgery.

METHODS

In a prospective clinical study, cone-beam computed tomography scans were taken preoperatively and postoperatively. From these images, the crown and root lengths of 61 roots (54 teeth in 47 patients) were measured before and after apical surgery. Data were collected relative to the cementoenamel junction (CEJ) as well as to the crestal bone level (CBL). One observer took all measurements twice (to calculate the intraobserver variability), and the means were used for further analysis. The following parameters were assessed for all treated teeth as well as for specific tooth groups: length of root-end resection and percentage change of root length, preoperative and postoperative RCRs, and percentage change of RCR after apical surgery.

RESULTS

The mean length of root-end resection was 3.58 ± 1.43 mm (relative to the CBL). This amounted to a loss of 33.2% of clinical and 26% of anatomic root length. There was an overall significant difference between the tooth groups (P < .05). There was also a statistically significant difference comparing mandibular and maxillary teeth (P < .05), but not for incisors/canines versus premolars/molars (P = .125). The mean preoperative and postoperative RCRs (relative to CEJ) were 1.83 and 1.35, respectively (P < .001). With regard to the CBL reference, the mean preoperative and postoperative RCRs were 1.08 and 0.71 (CBL), respectively (P < .001). The calculated changes of RCR after apical surgery were 24.8% relative to CEJ and 33.3% relative to CBL (P < .001). Across the different tooth groups, the mean RCR was not significantly different (P = .244 for CEJ and 0.114 for CBL).

CONCLUSIONS

This CBCT-based study demonstrated that the RCR is significantly changed after root-end resection in apical surgery irrespective of the clinical (CBL) or anatomic (CEJ) reference levels. The lowest, and thus clinically most critical, postoperative RCR was observed in maxillary incisors. Future clinical studies need to show the impact of resection length and RCR changes on the outcome of apical surgery.

Scanning electronic microscopy analysis of the apical surface after of root-end resection with different methods

To compare the time dispensed and the surface characteristics when a root-end resection was performed with a surgical ultrasonic device (VarioSurg, NSK, Japan) or with a Zekrya bur. Forty distal roots of freshly extracted mandibular molars were selected and divided into four different groups: (G1) stainless steel insert with ultrasound; (G2) diamond insert with ultrasound; (G3) stainless steel and diamond inserts with ultrasound, and (G4) Zekrya burs. The time required for the root-end resection was timed and the surface characteristics were evaluated via scanning electronic microscopy. The median times for the root-end resections were: 115.9 s for G1, 249.8 s for G2, 112.7 s for G3, and 7.44 s for G4, the latter presented a smoother root-end surface. There was no statistically significant difference in the comparisons between G3 group and G4 group (Zekrya burs). The other groups where the root-end resections were with ultrasonic devices proportioned a prolonged time to resection with irregular surfaces.