Comparison of calcium hydroxide extrusion with syringe versus spiral filler delivery: A pilot study.

This study aimed to evaluate Ca(OH)2 extrusion in relation to delivery technique, apical size and depth of placement. Plastic blocks had j-shaped canals shaped to apical sizes #35 and #45 (n = 32 each). Amounts of calcium hydroxide extrusion was determined relative to apical taper, depth of insertion and whether syringe or spiral filler at 500 rpm was used. Blocks were immersed in pH-sensitive gel and observed for colour change. Extent of extrusion was expressed in mm2 . Extrusion occurred in 48/64 of the samples. At 3 mm from the canal terminus, the device affected the frequency of extrusion, with syringe placement causing extrusion significantly (P < 0.01) more frequently, irrespective of apical size. Extrusion was significantly greater at 2 mm short of the canal terminus (median 27.44 mm2 ) compared to 3 mm (median 19.69 mm2 ). Under in-vitro conditions, a spiral filler at 500 rpm, 3 mm short of the apex, minimised extrusion of Ca(OH)2 from root canals.

The double-edged sword of calcium hydroxide in endodontics: Precautions and preventive strategies for extrusion injuries into neurovascular anatomy.

BACKGROUND: Nowhere in the consideration of dental care involving endodontics does a patient become more vulnerable to potentially life-changing injuries than during a root canal procedure on the mandibular dentition that may invade and injure the neurovascular anatomy. CASE DESCRIPTION: The authors present a series of 5 cases wherein using calcium hydroxide as a disinfection strategy in endodontics caused serious neurologic injury to the treated patients. The mechanism in all cases was the inappropriate use of needle applications resulting in significant overfill into the inferior alveolar nerve space. Although calcium hydroxide has been recognized and used as a meaningful disinfectant in endodontic therapy for many years, the dangers and risks associated with a needle delivery technique are discussed and analyzed with recommendations based on current research to minimize risk. CONCLUSIONS AND PRACTICAL IMPLICATIONS: A literature search revealed that the 5 cases are not solitary cases; indeed, consequences of calcium hydroxide overfills have been described before. Therefore, a clinician initiating root canal therapy on a mandibular posterior tooth should always be mindful of the vital neurovascular anatomy, which commonly approximates the ends of these roots. Preoperative cone-beam computed tomographic imaging and the thoughtful delivery of medicaments in treatment can help the clinician manage close proximity to neural anatomy and avoid potential injuries.

Rotary Versus Reciprocation Root Canal Preparation: Initial Clinical Quality Assessment in a Novice Clinician Cohort.

INTRODUCTION: Reports comparing clinical outcomes using nickel-titanium (NiTi) reciprocating instruments with other instrumentation modalities are scarce. This study examined initial shaping outcomes after an instrumentation change of root canal instrumentation technique in a doctor of dental surgery educational program. Student characteristics, faculty/student ratio, facility, and overall endodontic treatment guidelines remained unchanged. METHODS: A total of 200 nonsurgical initial molar root canal treatments completed by third-year dental students were evaluated. The cases were examined regarding the number of treatment appointments, access cavity preparation, canal taper, canal transportation, perforations, missed canals, presence of ledges, fractured instruments, obturation length, obturation quality, and sealer extrusion. Two independent evaluators determined the number of appointments per case; 4 independent and blinded evaluators analyzed radiographs at 4 treatment stages: preoperative situation, working length, cone fit, and obturation. RESULTS: The following factors were significantly different between the 2 cohorts: the number of appointments, preparation length, taper, and occurrence of ledges. The WaveOne (Dentsply Sirona, York, PA) cohort had a significantly reduced treatment time compared with hand/GT rotary instrumentation (Dentsply Tulsa Dental, Tulsa, OK) (average of 3.3 vs 4.3 appointments). Appropriate length control and adequate taper were significantly more frequent in the WaveOne group. The frequency of ledges was significantly larger in the hybrid group. Other variables, such as access cavity preparation, canal transportation, perforations, missed canals, fractured instruments, obturation quality, and sealer extrusion, were statistically similar between the 2 groups. CONCLUSIONS: NiTi reciprocation instrumentation was superior to hybrid hand/NiTi rotary instrumentation in reducing both patient appointments and the incidence of ledging and in improving obturation length and taper in a dental student clinic setting.

Educational Outcomes of Small-Group Discussion Versus Traditional Lecture Format in Dental Students' Learning and Skills Acquisition.

The aim of this prospective quantitative study was to compare the effect of different instructional formats on dental students' skills and knowledge acquisition for access cavity preparation. All first-year dental students were invited to participate in this study conducted during the four consecutive two-week endodontic rotation courses at the University of the Pacific Arthur A. Dugoni School of Dentistry in spring semester 2015. Four alphabetically distributed intact groups of students were randomly allocated to two groups (n=70 each) that participated in either small-group discussion or a traditional lecture on access preparation. The first outcome measure was skill acquisition, measured by the quality of access cavities prepared in extracted teeth at the conclusion of the session. Two blinded raters scored direct observations on a continuous scale. Knowledge, the second outcome measure, was scored with a multiple-choice and open-ended question test at the end of each two-week session. Data were obtained for 134 of the 140 students, for a 96% response rate. The results showed that students in the small-group discussion groups scored significantly higher than those in the lecture groups when skill performance was tested (p=8.9 × 10(-7)). However, no significant differences were found in the acquisition of knowledge between the two groups on the written test. Active student participation was significantly related to improved manual skill acquisition, but the format of the session does not seem to have had a direct influence on acquired knowledge.

Comparison of 2 canal preparation techniques in the induction of microcracks: a pilot study with cadaver mandibles.

INTRODUCTION: The purpose of this pilot study in a cadaver model was to compare 2 different shaping techniques regarding the induction of dentinal microcracks. METHODS: Three lower incisors from each of 6 adult human cadaver skulls were randomly distributed into 3 groups: the control group (CG, no instrumentation), the GT group (GT Profile hand files; Dentsply Tulsa Dental, Tulsa, OK), and the WO group (WaveOne; Dentsply Tulsa Dental). In the GT group, manual shaping in a crown-down sequence with GT Profile hand files was performed. In the WO group, Primary WaveOne files were used to the working length. Teeth were separated from the mandibles by careful removal of soft tissue and bone under magnification. Roots were sectioned horizontally at 3, 6, and 9 mm from the apex using a low-speed saw. Color photographs at 2 magnifications (25× and 40×) were obtained. Three blinded examiners registered the presence of microcracks (yes/no), extension (incomplete/complete), direction (buccolingual/mesiodistal), and location. Data were analyzed with chi-square tests at P < .05. RESULTS: Microcracks were found in 50% (CG and GT) and 66% (WO) of teeth at 3 mm, 16.6% (CG) and 33.3% (GT and WO) at 6 mm, and 16.6% in all 3 groups at 9 mm from the apex. There were no significant differences in the incidence of microcracks between all groups at 3 (P = .8), 6 (P = .8), or 9 mm (P = 1). All microcracks were incomplete, started at the pulpal wall, and had a buccolingual direction. CONCLUSIONS: Within the limitations of this pilot study, a relationship between the shaping techniques (GT hand and WaveOne) and the incidence of microcracks could not be shown compared with uninstrumented controls.

Analysis of temperature rise and the use of coolants in the dissipation of ultrasonic heat buildup during post removal.

INTRODUCTION: This study was designed to calculate probabilities for tissue injury and to measure effectiveness of various coolant strategies in countering heat buildup produced by dry ultrasonic vibration during post removal. METHODS: A simulated biological model was used to evaluate the cooling efficacy of a common refrigerant spray, water spray, and air spray in the recovery of post temperatures deep within the root canal space. The data set consisted of cervical and apical measures of temperature increase at 1-second intervals from baseline during continuous ultrasonic instrumentation until a 10 °C increase in temperature at the cervical site was registered, wherein instrumentation ceased, and the teeth were allowed to cool under ambient conditions or with the assistance of 4 coolant methods. RESULTS: Data were analyzed with analysis of variance by using the independent variables of time of ultrasonic application (10, 15, 20 seconds) and cooling method. In addition to the customary means, standard deviations, and analysis of variance tests, analyses were conducted to determine probabilities that procedures would reach or exceed the 10 °C threshold. Both instrumentation time and cooling agent effects were significant at P <.0001. CONCLUSIONS: Under the conditions of this study, it was shown that injurious heat transfer occurs in less than 1 minute during dry ultrasonic instrumentation of metallic posts. Cycles of short instrumentation times with active coolants were effective in reducing the probability of tissue damage when teeth were instrumented dry. With as little as 20 seconds of continuous dry ultrasonic instrumentation, the consequences of thermal buildup to an individual tooth might contribute to an injurious clinical outcome.

Pulp capping with mineral trioxide aggregate (MTA): a retrospective analysis of carious pulp exposures treated by undergraduate dental students.

The current study estimated pulpal vitality after MTA pulp caps were performed by undergraduate student clinicians. At recall after 12 to 27 months, 51 pulp caps were clinically and radiographically assessed. Kaplan-Meier analyses were used to estimate overall success at 12 and 24 months, determined as the presence of a vital pulp, as well as impact of preoperative variables on pulp vitality at recall. Overall, one-year pulp survival was 67.7%, while the two-year survival rate was 56.2%. Tarone-Ware statistics indicated that neither age of the patient nor size of the exposure ("minimal" or "moderate") and the amount of bleeding ("none," "minimal" or "moderate") had a significant effect on survival rates. Within the limitations of the current study on procedures performed by student clinicians, it may be concluded that, for MTA pulp caps applied to carious exposures in adults, certain preoperative conditions--patient age, exposure size and amount of bleeding--are not predictive of clinical outcome. Considering the comparatively low success rate for the current cohort, more research is needed to define predictive criteria for successful pulp capping with MTA.

Identify and define all diagnostic terms for periapical/periradicular health and disease states.

INTRODUCTION: The purpose of this in-depth investigation was to identify, clarify, and substantiate clinical terminology relative to apical/periapical/periradicular diagnostic states, which is used routinely in the provision of endodontic care. Furthermore, the information gleaned from this investigation was used to link diagnostic categories to symptoms, pathogenesis, treatment, and prognosis wherever possible, along with establishing the basis for the metrics used in this diagnostic process. MATERIALS AND METHODS: Diagnostic terminologies and their relevance to clinical situations were procured from extensive historic and electronic searches and correlated with contemporary concepts in disease processes, clinical assessments, histologic findings (if appropriate), and standardized definitions that have been promulgated and promoted for use in the last 25 years in educational programs and test constructions and for third-party concerns. RESULTS: In general, clinical terminology that is used routinely in the practice of endodontics is not based on the findings of scientific investigations. The diagnostic terms are based on assumptions by correlating certain signs, symptoms, and radiographic findings with what is presumed (not proven) to be the underlying disease process of a given clinical state. There were no studies that specifically tried to assess the accuracy of the metrics used contemporarily for the classification of clinical disease states. CONCLUSION: A succinct diagnostic scheme that could be described thoroughly, agreed on unanimously, coded succinctly for easy electronic input, and ultimately used for follow-up analysis would not only drive treatment modalities more accurately, but would also allow for future outcomes assessment and validation.

Thermal injury through intraradicular heat transfer using ultrasonic devices: precautions and practical preventive strategies.

BACKGROUND: The use of ultrasonic energy is a highly efficient method of removing obstructions and cements within the root canal space when re-treatment or rehabilitation of that ultrasonic energy dislodges and removes cemented objects from the bonded interface of the canal wall. When using this method, there is less potential for structural loss or root damage and significantly less operator stress than when using other methods. CASE DESCRIPTIONS: There is little evidence in published research of the considerable heat transfer that occurs during use of ultrasonic devices to remove posts, pastes and separated instruments in teeth. The authors present three cases of patients who experienced serious burn injuries during application of ultrasonic energy for restorative dentistry. The authors also offer techniques and strategies for safe and effective use of ultrasonic devices. CLINICAL IMPLICATIONS: On the basis of the best available evidence, the authors recommend strategies to provide safe and effective therapy while using ultrasonic devices in intraradicular obstruction removal. The intent of the suggested protocols is to provide advanced and sophisticated therapies in a safe and regulated manner with patient safety as an overriding priority.

The crisis in endodontic education: current perspectives and strategies for change.

The current status of dental education in the United States and Canada with respect to faculty recruitment and retention is reviewed; poor salaries and lack of interest are major reasons for dwindling numbers. The pros and cons of an academic career and what the American Association of Endodontists' (AAE) and other constituencies have done to help alleviate the problem are presented. The results of an on-line survey to full-time endodontic educators on their perspectives on education are presented; personal fulfillment, sharing knowledge, giving back to the profession, and passion for teaching were reasons for teaching whereas income disparity, lack of mentoring, and high demands of the job were reasons against an academic career. The final phase of the paper proposes various strategies on how the AAE and its membership, dental schools, and the American Board of Endodontics (ABE) can further work together to alleviate the critical problems facing endodontic education.

The aesthetic post and core: unifying radicular form and structure.

Use of a post system for the rehabilitation of endodontically treated teeth requires traditional planning for the function of the restoration as well as a structural and aesthetic strategy for novel technologies in ceramic and composite dentistry. Contemporary material options have greatly expanded the clinician's ability to rehabilitate the coronoradicular complex. Transilluminating posts, bondable fabrics, and high-technology ceramics create exciting possibilities in post and core design. The use of bondable materials allows the practitioner to unify the structure and morphology of root systems to provide creative solutions to challenges heretofore unmet.