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.

Comparative Biocompatibility and Osteogenic Potential of Two Bioceramic Sealers.

INTRODUCTION: Endodontic sealers have traditionally been used to seal dentinal tubules, creating a homogenous interface between the obturation material and the dentinal walls. However, bioceramic sealers have potential added benefits because of their bioactivity. After adequate endodontic therapy, osseous healing is largely dependent on the differentiation and activity of osteoblasts. We hypothesized that EndoSequence BC Sealer (Brasseler, Savannah, GA) and ProRoot ES (Dentsply Tulsa Dental Specialties, Johnson City, TN) have superior biocompatibility and osteogenic potential compared with Roth (Roth International, Chicago, IL) and AH Plus (Dentsply DeTrey Gmbh, Konstanz, Germany) sealers. METHODS: A murine osteoblast precursor cell line (IDG-SW3) was exposed to a wide range of concentrations for each of the sealers for 7 days. The relative cell viability was determined by luminescence assay based on adenosine triphosphate quantification (CellTiter-Glo [Promega, Madison, Wisconsin]). The osteogenic potential was determined by fluorescence microscopy of DMP-1 expression, alizarin red staining, and real-time reverse transcription polymerase chain reaction with primers specific for known markers of osteogenesis such as DMP-1, ALP, and Phex. Data were analyzed with 2-way analysis of variance or 1-way analysis of variance with the Bonferroni post hoc test. RESULTS: Both bioceramic sealers have excellent biocompatibility even at high concentrations. Conversely, cell death was detected when Roth and AH Plus were used at concentrations 100× lower than the bioceramic groups. Importantly, both bioceramic sealers significantly enhanced osteoblastic differentiation although greater responses were noted with EndoSequence BC Sealer. This was evidenced by increased DMP-1 expression, robust up-regulation of osteogenic marker gene expression, and superior mineral deposition. Osteoblastic differentiation and function were significantly impaired when Roth or AH Plus sealer was used. CONCLUSIONS: EndoSequence BC Sealer and ProRoot ES were significantly more biocompatible and promoted osteoblastic differentiation, a bioactivity not found in AH Plus and Roth sealers.

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.

Binary Decision Trees for Preoperative Periapical Cyst Screening Using Cone-beam Computed Tomography.

INTRODUCTION: Cone-beam computed tomographic (CBCT) analysis allows for 3-dimensional assessment of periradicular lesions and may facilitate preoperative periapical cyst screening. The purpose of this study was to develop and assess the predictive validity of a cyst screening method based on CBCT volumetric analysis alone or combined with designated radiologic criteria. METHODS: Three independent examiners evaluated 118 presurgical CBCT scans from cases that underwent apicoectomies and had an accompanying gold standard histopathological diagnosis of either a cyst or granuloma. Lesion volume, density, and specific radiologic characteristics were assessed using specialized software. Logistic regression models with histopathological diagnosis as the dependent variable were constructed for cyst prediction, and receiver operating characteristic curves were used to assess the predictive validity of the models. A conditional inference binary decision tree based on a recursive partitioning algorithm was constructed to facilitate preoperative screening. RESULTS: Interobserver agreement was excellent for volume and density, but it varied from poor to good for the radiologic criteria. Volume and root displacement were strong predictors for cyst screening in all analyses. The binary decision tree classifier determined that if the volume of the lesion was >247 mm3, there was 80% probability of a cyst. If volume was <247 mm3 and root displacement was present, cyst probability was 60% (78% accuracy). CONCLUSIONS: The good accuracy and high specificity of the decision tree classifier renders it a useful preoperative cyst screening tool that can aid in clinical decision making but not a substitute for definitive histopathological diagnosis after biopsy. Confirmatory studies are required to validate the present findings.

The effect of 8.25% sodium hypochlorite on dental pulp dissolution and dentin flexural strength and modulus.

INTRODUCTION: The purpose of this study was to evaluate the effect of various concentrations of sodium hypochlorite (NaOCl), including 8.25%, on dental pulp dissolution and dentin flexural strength and modulus. METHODS: Sixty dental pulp samples and 55 plane parallel dentin bars were retrieved from extracted human teeth. Five test groups (n = 10) were formed consisting of a pulp sample and dentin bar immersed in various NaOCl solutions. The negative control group (n = 5) consisted of pulp samples and dentin bars immersed in saline. The positive control group (n = 5) consisted of pulp samples immersed in 8.25% NaOCl without a dentin bar. Every 6 minutes for 1 hour, the solutions were refreshed. The dentin bars were tested for flexural strength and modulus with a 3-point bend test. The time until total pulp dissolution and any changes in dentin bar flexural strength and modulus for the different NaOCl solutions were statistically analyzed. RESULTS: An increase in NaOCl concentration showed a highly significant decrease in pulp dissolution time. The pulp dissolution property of 8.25% NaOCl was significantly faster than any other tested concentration of NaOCl. The presence of dentin did not have a significant effect on the dissolution capacity of NaOCl if the solutions were refreshed. NaOCl concentration did not have a statistically significant effect on dentin flexural strength or modulus. CONCLUSIONS: Dilution of NaOCl decreases its pulp dissolution capacity. Refreshing the solution is essential to counteract the effects of dentin. In this study, NaOCl did not have a significant effect on dentin flexural strength or modulus.

The effects of dentin debris on the cyclic fatigue resistance of several nickel titanium rotary systems.

OBJECTIVE: The aim of this study was to compare the effects of impacted dentin debris on the cyclic fatigue resistance of a traditional ground file, an electropolished file, and a thermally treated twisted file. STUDY DESIGN: One hundred thirty-five files were rotated against bovine dentin or a highly polished surface at the manufacturers' recommended rotation speed with a continuous 5-mm axial movement of 1 cycle per second. The files were equally divided into 3 groups: group 1, contacting dentin for 500 cycles and then metal to failure; group 2, contacting metal only to failure; group 3, contacting dentin only to failure. Cycles to failure were analyzed using analysis of variance (P < .05). RESULTS: K3 and Twisted Files outperformed EndoSequence files in the dentin-only group. No difference was found between the metal and dentin-metal groups. CONCLUSIONS: In the presence of dentin, the electropolished surface of the EndoSequence NiTi rotary files did not increase the files' cyclic fatigue resistance compared with K3 or Twisted Files of the same tip size and taper.