Targeted Endodontic Microsurgery: A Retrospective Outcomes Assessment of 24 Cases.

INTRODUCTION: Targeted endodontic microsurgery (TEMS) replaces freehand carbide or diamond bur osteotomy and root-end resection with a guided approach using an end-cutting trephine bur rotated within a guide tube. TEMS departs from traditional endodontic microsurgery in osteotomy size, control of resection level and bevel, surgical time, and resection method; yet, the impact of these departures on clinical outcomes has yet to be assessed. The aim of this study was to assess clinical outcomes of TEMS surgeries at least 1 year after treatment. METHODS: Potential cases were retrospectively identified from a secure database of all patients who received TEMS in the Air Force Postgraduate Dental School from June 2017-May 2019 with a postsurgical follow-up examination at 1 year or beyond (23 patients with 24 teeth). Two board-certified endodontists completed a calibration exercise before assessing radiographs. A retrospective outcomes assessment was conducted considering follow-up clinical and radiographic findings to assign 1 of 3 healing designations: complete healing, reductive healing, or failure. RESULTS: Combined clinical and radiographic data led to 20 designations of complete healing, 2 designations of reductive healing, and 2 failures (91.7% success rate). Considered alone, radiographic criteria for complete healing were met for 20 cases, reductive healing for 3 cases, and radiographic failure for 1 case. CONCLUSIONS: This limited retrospective outcomes assessment is an early indication that TEMS-guided trephine bur root-end resection leads to similar success as is established for freehand carbide and diamond bur resection. Controlled clinical trials with long-term follow-up are warranted.

Targeted Endodontic Microsurgery: Implications of the Greater Palatine Artery.

INTRODUCTION: Targeted Endodontic Microsurgery (TEMS) combines trephine burs and 3D-printed guides to make flapless maxillary palatal root-end surgery possible. This study assessed the location of the greater palatine artery (GPA), the relationship of the GPA to maxillary molar root ends, and the feasibility of flapless palatal-approach TEMS. METHODS: Three endodontists analyzed 250 cone-beam computed tomographic images of maxillary molars for (1) transition morphology between the hard palate and the alveolar process adjacent to first and second molars as an indication of the most likely location of the GPA, (2) the superior-inferior relationship between the GPA and root ends, and (3) the feasibility of palatal-approach TEMS. RESULTS: Palatal transition morphology included 20% Spine, 72% Bridge, and 8% Smooth. GPA position as related to palatal root ends was classified as 34% superior, 40% adjacent, and 21% inferior. Five percent of classifications were undefined. TEMS was deemed feasible for 47% of maxillary first molars and 52% of second molars, and was significantly more feasible with GPAs superior to palatal root ends. Reasons for infeasibility included GPA proximity and unfavorable resection angle or level. Maxillary first molar palatal roots were 11.13 ± 2.68 mm from the greater palatine foramen (GPF) and 2.37 ± 1.46 mm from the GPA. Second molar palatal roots were 4.94 ± 2.55 mm from the GPF and 2.53 ± 1.77 mm from the GPA. CONCLUSIONS: Palatal transition morphology and GPA position adjacent to maxillary molars, as manifested in cone-beam computed tomographic coronal views, suggested maxillary palatal root TEMS could be accomplished with a 2-mm safety margin in 47% of first molars and 52% of second molars. Historical paradigms that do not consider flapless palatal surgical approaches may need to be revised.

Targeted Endodontic Microsurgery: Digital Workflow Options.

Targeted endodontic microsurgery (TEMS) combines a precisely designed 3-dimensional (3D)-printed surgical guide with a trephine bur for safe and efficient osteotomy and root-end resection. The TEMS digital workflow converts the patient's anatomy into digital data in 4 steps. First, bone, teeth, and neurovascular spaces are rendered with cone-beam computed tomographic imaging. Next, crowns and soft tissues are rendered with an intraoral optical scan, a benchtop optical scan of an impression or cast, or a cone-beam computed tomographic scan of an impression or cast. Third, these renderings are merged within design software to create a 3D construction containing a virtual model. Finally, guide design is performed on the virtual model for 3D printing. A significant gap in knowledge exists in that digital workflow principles and considerations are not documented in the endodontic literature. The aim of this article is to describe TEMS digital workflow guiding principles.

Cyclic fatigue resistance and metallurgic comparison of rotary endodontic file systems.

The aim of this study was to compare, in pairs, the cyclic fatigue resistance, scanning electron microscopic (SEM) appearance, and energy-dispersive X-ray (EDX) profiles of 6 rotary files: ProTaper Gold vs EdgeTaper Platinum; ProTaper Universal vs EdgeTaper; and Vortex Blue vs EdgeSequel Sapphire. Six types of rotary file were tested in 2 sizes of each type. A 3-point cyclic fatigue apparatus imparting a 60-degree angle of curvature and a 3-mm radius of curvature was used to evaluate 30 files of each type and size. The cyclic fatigue testing results from similar file types and sizes were paired for statistical analysis. After fatigue testing was completed, 36 files (3 of each type and size) were randomly selected for SEM imaging and EDX analysis. When similar file types and sizes were paired in independent-samples t tests, statistically significant differences (P < 0.0001) in cyclic fatigue resistance were established. For both tested sizes, EdgeTaper Platinum exhibited significantly greater fatigue resistance than ProTaper Gold. ProTaper Universal and EdgeTaper each demonstrated significantly greater fatigue resistance than the other system in 1 size pairing. Vortex Blue exhibited significantly greater fatigue resistance than EdgeSequel Sapphire in both size pairings. In general, the heat-treated files demonstrated greater cyclic fatigue resistance than the non-heat-treated files. The SEM images verified that fracture patterns were consistent with cyclic fatigue failure. Differences in file design between the matched pairs were noted, particularly at the tips. The EDX comparisons showed that nickel and titanium were present in similar percentages (1:1 atomic ratio) for all file types. The disparities in cyclic fatigue results and tip design indicate that clinicians should not expect identical clinical performance from different files.

Clinician-centered Outcomes Assessment of Retreatment and Endodontic Microsurgery Using Cone-beam Computed Tomographic Volumetric Analysis.

INTRODUCTION: Outcomes assessment of retreatment and endodontic microsurgery (EMS) are traditionally based on clinical findings and radiographs. The purpose of this study was to assess the volumetric change of periapical radiolucencies (PARLs) by cone-beam computed tomographic (CBCT)-based analysis in retreatment and EMS cases. METHODS: For 68 retreatment and 57 EMS cases, preoperative and recall clinical data, periapical (PA) radiographs, and CBCT imaging were retrospectively obtained. Specialized software was used by 2 board-certified endodontists for volumetric analysis of PARLs. For EMS and retreatment, clinical outcomes were determined by combining clinical data with CBCT-generated volumetric analysis (PA radiographs not used). Additionally, comparisons of percent volume reduction for EMS and retreatment were performed. Examiner interpretations of outcomes assessment using PA radiography and CBCT imaging were compared. RESULTS: In teeth with or without a preoperative PARL, EMS resulted in a statistically significant difference in complete healing (49/57 [86.0%]) versus retreatment (28/68 [41.2%], P < .0001). EMS resulted in a statistically significant difference in combined complete healing and reductive healing (54/57 [94.7%]) versus retreatment (56/68 [82.4%], P < .05). Of 46 recalls in which CBCT imaging detected a PARL, PA radiography detected 30 (a 35% false-negative rate). Of the 79 recall studies in which CBCT imaging did not detect a PARL, PA radiography did detect PARL in 13 (a 16.5% false-positive rate). CONCLUSIONS: In this CBCT and clinical data-based outcomes assessment, EMS resulted in a greater mean volumetric reduction and a higher healing rate compared with retreatment. Postoperative CBCT imaging is more sensitive and specific than PA radiography in assessing PARL and has demonstrable usefulness in outcomes assessment.

Targeted Endodontic Microsurgery: A Novel Approach to Anatomically Challenging Scenarios Using 3-dimensional-printed Guides and Trephine Burs-A Report of 3 Cases.

Endodontic microsurgery (EMS) techniques have increased success rates over traditional approaches. Despite surgical advances, anatomically challenging scenarios can preclude EMS in certain cases. The aim of this article was to introduce targeted EMS, which uses 3-dimensional-printed surgical guides (3DSGs) and trephine burs to achieve single-step osteotomy, root-end resection, and biopsy in complex cases. In each of 3 cases, a 3DSG with a trephine port was printed using computer-aided design/computer-aided manufacturing implant planning software. The osteotomy site, angulation, and depth of preparation were defined preoperatively to avoid sensitive anatomic structures. The 3DSG was inserted at the target site to achieve precise osteotomy and root-end resection during surgery. A hollow trephine rotated within the 3DSG port produced single-step osteotomy, root-end resection, and biopsy. Root-end preparation and fill were accomplished, and tissues were sutured in place. Targeted EMS potentiated successful surgical treatment in 3 anatomically challenging scenarios: (1) a palatal approach to the palatal root of a maxillary second molar, (2) a facial approach to a fused distofacial-palatal root of a maxillary first molar, and (3) a mandibular second premolar in close proximity to the mental foramen. Trephine burs guided by 3DSGs produce efficient targeted osteotomies with a predictable site, angulation, and depth of preparation. Apical surgery in challenging anatomic cases such as the palatal root of the maxillary second molar, fused molar roots, and root ends in approximation to the mental nerve are possible with targeted EMS.

Healing of apical periodontitis through modern endodontic retreatment techniques.

The presence of apical periodontitis in teeth which have undergone initial root canal treatment is largely attributed to bacteria residing in or invading from the apical root canal space. Bacteria-associated apical periodontitis will not heal spontaneously, nor will systemic antibiotics eradicate the infection. Only endodontic retreatment, endodontic surgery, or extraction will control the bacterial etiology. Modern retreatment is an effective means of addressing apical periodontitis. A mandibular premolar with apical periodontitis, apical root resorption, and overfilled gutta percha was retreated with post removal, retrieval of gutta percha from beyond the apex, ultrasonic irrigation and disinfection, and placement of a collagen internal matrix to facilitate a well-controlled MTA apical fill. The magnification and illumination imparted by the operating microscope was integral to achievement of treatment objectives. The patient's symptoms were resolved and complete osseous healing occurred. During treatment planning, clinicians should consider the capability of modern endodontic techniques to overcome technical challenges, often allowing the natural dentition to be preserved and restored to function days after retreatment.

Cyclic fatigue of EndoSequence and K3 rotary files in a dynamic model.

The cyclic fatigue resistance of K3 and EndoSequence files was compared by rotating files against a highly polished surface inclined at 15 degrees to the horizontal. For each brand, files with a 25 tip in .04 and .06 taper and files with a 40 tip in .04 and .06 taper were tested at both 300 and 600 rpm. A 3-mm axial movement simulated a clinical pecking motion at 1 cycle per second. The number of rotations to failure was calculated and analyzed by using analysis of variance and Independent Student's t tests, with results confirmed by nonparametric Mann-Whitney U tests with a Bonferroni correction. At both 300 and 600 rpm, K3 files exhibited statistically significantly more cycles to fracture than their EndoSequence counterparts with the same tip size and taper. Scanning electron microscopy images demonstrated surface features consistent with fracture due to cyclic fatigue. In this model, file design appeared to be the most important determinant of cyclic fatigue resistance.