The effect of rotary instrumentation on dentin thickness in the danger zone of the MB2 canal of maxillary first molars.

The aim of this study was to measure the initial and remaining dentin thickness in the danger zone of the second mesiobuccal (MB2) canal of maxillary first molars after rotary instrumentation using cone beam computed tomography (CBCT) imaging. After determining initial dentin thickness, each sample was subjected to a standardized protocol of rotary instrumentation files: ProTaper Gold Sx Orifice Opener (maximum depth of 7 mm); Vortex Blue 15.04, 20.04, 25.04, ProTaper Gold S1, S2, F1, F2, and finally Vortex Blue 30.06. Subsequent CBCT measurements were made to compare changes in remaining dentin thickness in comparison to initial presentation. Preoperative dentin thickness in the danger zone had a mean of 0.82 ± 0.17mm. Significant levels of dentin removal in the danger zone were noted after all instrumentation groups when compared to the pre-instrumentation mean (Sx P < 0.001, 25.04 P < 0.0006, F2 P < 0.0001, 30.06 P < 0.0001). It was concluded that a thin area of dentin exists along the distal wall of the MB2 (danger zone) from the furcation to 4 mm apically.

Preoperative Factors Associated with Anesthesia Failure for Patients Undergoing Nonsurgical Root Canal Therapy: A National Dental Practice-Based Research Network Study.

INTRODUCTION: The aim of this study was to identify preoperative factors associated with local anesthesia failure. METHODS: The National Dental Practice-Based Research Network (www.NationalDentalPBRN.org) data from 534 patients who received a nonsurgical root canal treatment completed in a single appointment were included in this analysis. Three methods for defining anesthesia failure were used: definition 1, patient-reported level of numbness; definition 2, provider-reported quality of anesthesia; and definition 3, provider-reported use of supplemental anesthesia. Fifty-one preoperative factors were investigated and analyzed individually against the overall failure rate for each method, and multivariate generalized estimating equation logistic models were fit with predictors chosen using stepwise model selection to evaluate factors that may interact with each other. RESULTS: The overall anesthesia failure rates were 5%, 15%, and 30% for definitions 1, 2, and 3, respectively. Provider experience, diabetes, absence of sharp or aching pain, absence of smoking, and a fair expected outcome were associated with anesthesia failure (definition 1). Provider level of training, absence of a sinus tract, bite sensitivity, and stress making the pain worse were associated with anesthesia failure (definition 2). Provider level of training, pain provoked by stimulus, mandibular teeth, teeth with vital pulps, and pain interfering with daily activities were associated with the use of supplemental anesthesia (definition 3). CONCLUSIONS: With the range of 5%-30% of anesthesia failures, a few common factors across the models assessed were elucidated. Providers with higher levels of training had significantly fewer anesthesia failures. Patient self-reported history of diabetes and preoperative pain-related interference with daily activities were associated with more anesthesia failures. Greater severity of various tooth-related pain characteristics, as a group but not individually, accounted for more anesthesia failures.

Postoperative Pain after Treatment Using the GentleWave System: A Randomized Controlled Trial.

INTRODUCTION: Cleaning and shaping are necessary to allow for the delivery of irrigants and medicaments to the apical third of the canal. Standard treatment irrigation generally uses a conventional needle and some frequency of sonic activation. The GentleWave System (GWS; Sonendo, Inc, Laguna Hills, CA) combines irrigant delivery with multisonic activation. This randomized clinical trial aimed to determine if the GWS significantly decreases the incidence and intensity of postoperative pain. METHODS: Patients used a numeric rating scale to record their pain level at the 6-hour time point before treatment. All participants were randomly divided into 2 groups and were blind to the treatment they received. The standard (control) group received endodontic treatment with conventional side-vented needle irrigation and ultrasonic activation. The second group received treatment with the GWS. Following treatment, patients used a numeric rating scale to record their pain level at 6, 24, 72, and 168 hours. RESULTS: In the standard treatment group, 72.2% of patients experienced at least 1 occurrence of postoperative pain, whereas in the GWS group, 83.3% of patients experienced at least 1 occurrence of postoperative pain. The highest pain intensity level for both treatments occurred at the 6-hour posttreatment time point. All pain decreased with time after the 6-hour posttreatment time point (P < 1.237e-7). CONCLUSIONS: There was no significant difference in the incidence or intensity of postoperative pain after either treatment group. However, both groups reported a statistically significant decrease in pain with time.

Anatomic Analysis of Palatal Roots of Maxillary Molars Using Micro-computed Tomography.

INTRODUCTION: The morphology of the palatal root of maxillary first and second molars was analyzed and compared using micro-computed tomographic scanning. METHODS: Forty-seven extracted maxillary molars were scanned with a micro-computed tomographic device to analyze the palatal radicular dentin dimensions, canal working width, root length, canal curvature, lateral canals, and apical constriction anatomy. Quantitative data were analyzed with mean and standard deviation for first and second molars, respectively. Comparison was made between first and second molars using an unpaired t test. RESULTS: The palatal root of maxillary first molars was found to have statistically significantly thinner dentin than second molars on the palatal aspect of the root 8-11 mm from the apex, correlating to the coronal and middle thirds of the root. First molar palatal roots also had a statistically significantly wider canal mesiodistally than second molars at 13-15 mm from the apex, correlating approximately to the level of the cementoenamel junction and pulpal floor. Significant canal curvature was present. These findings suggest the need for conservative coronal flaring and instrumentation. CONCLUSIONS: The absence of an apical constriction in 76.6% of the specimens highlights the importance of creating an apical seat through instrumentation to maintain obturation materials. A minimum master apical file size of 40 is recommended based on preoperative working widths in the apical 0.5-1.0 mm. A root-end resection of 3.5 mm would remove a greater majority of lateral canals.

Cone-beam Computed Tomography: Anatomic Analysis of Maxillary Posterior Teeth-Impact on Endodontic Microsurgery.

INTRODUCTION: It is imperative that the endodontic surgeon be knowledgeable of the anatomic dimensions of the surgical site. If cone-beam computed tomography is not available because of location/cost, it is prudent for the clinician to consult a knowledge base for the surgical site. An understanding of the root thickness of maxillary premolars and molars at the preferred level for root resection (3.0-3.6 mm), bone thickness over these roots, and the proximity of each root apex to the maxillary sinus will help the surgeon before and during the surgical procedure. METHODS: Cone-beam computed tomography scans from 155 patients were used to evaluate measurements from 505 teeth and respective areas. RESULTS: (1) Buccal bone was thinnest over the buccal root of the 2-rooted first premolar (0.66 mm) and the mesiobuccal (MB) root of the first molar (0.84 mm) and thickest over the MB root of the second molar (1.91 mm). (2) The palatal bone was thinnest over the palatal root of the maxillary first molar (1.24 mm) and thickest over the single-rooted second premolar (3.26 mm). (3) The longest distances to complete resection were found for the 2-rooted first and second premolars (8.81 mm and 9.14 mm, respectively) and the MB root of the second molar (7.40 mm). (4) The MB root of the second molar had the closest proximity to the sinus floor, with an average distance of 0.66 mm. CONCLUSIONS: An understanding of the maxillary posterior tooth anatomy for apical resection is beneficial to the endodontist.

Mandibular Canal Location: Cone-beam Computed Tomography Examination.

INTRODUCTION: The increased use of implants and potential endodontic misadventures can lead to nerve damage. The purpose of this study was to use cone-beam computed tomography (CBCT) measurements to investigate mandibular canal (MC) location in relation to mandibular posterior teeth, the dimension of the buccal and lingual bone over the MC, the diameter of the MC, and the anterior loop location near the mental foramen. METHODS: CBCT scans from 106 patients (age, 18-69 years) were used to evaluate measurements from 636 teeth and respective MC areas. RESULTS: Respective locations of MC to teeth (buccal, inferior, or lingual) were as follows: second molar (57% buccal, 40% inferior, and 3% lingual), first molar (18% buccal, 55% inferior, and 27% lingual), and second premolar (33% buccal, 55% inferior, and 11% lingual). Buccal bone thickness over the MC was thickest at mesial root of second molars and thinnest over the second premolar (5.4 versus 2.6 mm). The lingual bone next to the MC was thickest over the second premolar and thinnest at distal root of first molars (3.8 versus 1.7 mm). The average diameter of the MC along the length of the canal from second molar to second premolar was 3.03 mm on left and 2.91 mm on right. The anterior loop was present in 10.4% of patients, with the average depth below bone of 13.43 mm. The anterior loop was more often seen on the left side than right and occurred bilaterally 50% of the time. CONCLUSIONS: Mandibular bone thickness, nerve location, and dimension data all contribute to a useful knowledge base for practitioners. The application of CBCT imaging techniques aids in the surgical treatment, while offering advantages over conventional periapical and panoramic films.

Electrical Pulp Testing: Sources of Error.

INTRODUCTION: Accurate identification and assessment of an inflamed or necrotic tooth is essentialfor endodontic treatment. The purpose of this research was to investigate possible sources of error associated with the use of the electric pulp tester (EPT). METHODS: Forty-six intact teeth (23 tooth pairs) in 22 patients were evaluated in vivo. For the tooth pairs, one tooth had to have been previously endodontically treated and restored with a class II amalgam restoration. The restoration was required to have proximal contact with a class II amalgam of another vital posterior tooth. EPT was performed on pulpless and vital teeth for experimental groups (enamel, restoration, contacting, or isolated). RESULTS: The highest rate of false positive responses (82%) was found in the pulpless restored contacting group, suggesting that EPT impulses are able to travel through proximal metallic contacts and stimulate teeth distant from the EPT probe. All vital tooth groups had a high rate of positive responses with no significant diferences. CONCLUSIONS: If a tested tooth contains an interproximal restoration contacting adjacent restorations or the gingival, the teeth must be isolated (rubber dam) and the EPT probe should be placed in a region suspected to have uninterrupted tubule paths to the pulp.

The Incidence of Furcation Region Patency in Molars Before and After Simulated Periodontal Therapy.

PURPOSE: To determine if there is increased bacterial communication through the furcation region in molar teeth after simulated periodontal therapy. METHODS: Sixty-five extracted first and second molars were accessed and the roots were sectioned 4 mm apical to the furcation. The canals and external suface of the root were sealed except the furcation region. In Phase I, the teeth were sterilized and then suspended in Rogosa SL broth. A broth containing Lactobacillus casei was placed in the pulp chamber. The Rogosa SL broth in the bottom chamber was monitored daily for 30 days for turbidity, and once turbidly was noted, the broth was plated to confirm the presence of L. casei. In Phase II, the furcation regions were scaled and cementum removed, the teeth were sterilized, and the microbial leakage was repeated. RESULTS: The Phase I and Phase II median times to turbidity were 9.5 days and 4 days, respectively, and the difference was statistically significant (p = 0.0035). Phase I turbidity rate was 86.5%, and Phase II was 92.3%, which was not statistically significant (p = 0.25). CONCLUSIONS: The root canal system communicated with the furcation region an average of 86.5% and 92.5% after scaling and root planing during the 30 days of the experiment. The time of leakage between the two groups decreased from 9.5 to 4 days (p = 0.0035). CLINICAL SIGNIFICANCE: Periodontal instrumentation of the furcation region in molar teeth can increase the risk of bacterial contamination by 39% while shortening the time for bacterial penetration in teeth with exposed dentin or furcation canals. accessory canals, scaling, and root planing.

An anatomical investigation of the mandibular second molar using micro-computed tomography.

PURPOSE: An understanding of root anatomy is an important foundation for providing successful endodontic treatment. The aim of this study was to use micro-computed tomography (micro-CT) to investigate the root anatomy of the mandibular second molar. METHODS: Eighteen mandibular second molars were scanned using micro-CT. Images were reconstructed, and measurements and observations were recorded regarding pulpal floor anatomy, canal configuration, root wall thickness along the root, presence of calcifications in the pulp chamber and in canals, and apical anatomy. RESULTS/CONCLUSIONS: The most frequently found mesial root canal configuration was Vertucci Type 7 (1-2-1-2), which was seen in 33.3% of samples. Distal canals were most frequently Vertucci Type 1 (one canal), with 61.1% of samples showing this configuration. 11.1% of samples had two canals, 44.4% of samples had three canals, 33.3% of samples had four canals, and 11.1% of samples had five canals at some point along the length of the roots. Average root wall thickness between the mesiobuccal canal and the furcation was 1.23 mm. Mesiolingual canal root wall thickness was on average 1.29 mm, and the distal root furcation wall thickness averaged 1.41 mm. 77.8% of samples had calcifications present in both the pulp chamber and within the canals.

Spectrophotometric determination of irrigant extrusion using passive ultrasonic irrigation, EndoActivator, or syringe irrigation.

INTRODUCTION: Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation. METHODS: One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples. RESULTS: Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1-3 µL) in straight roots or curved roots occurred in 10%-11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3-10 µL of NaOCl. CONCLUSIONS: The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant.

Palatal anesthesia: comparison of four techniques for decreasing injection discomfort.

INTRODUCTION: The aim of this study was to evaluate the patient's perceived pain response to injection and anesthetic deposition for the greater palatine nerve block. METHODS: Heft-Parker Visual Analog Scale (VAS) pain scale measurements were used to compare the following techniques for the injection: (1) control (no concurrent stimulation), (2) pressure, (3) pressure and topical anesthetic (20% benzocaine), and (4) pressure and cold (TFE). Forty-two volunteers, 21 male and 21 female, participated in the study. A bilateral model was used on each patient to give an injection on each side of the palate with two different techniques followed by the next appointment (> or = two weeks later), when the two other injection techniques were used. Following injection given in the supine position, the patients were returned to an upright position and asked to rate their pain on a VAS. RESULTS: Pain upon needle insertion appears less than that of anesthetic deposition. There was no statistically significant difference in perceived pain response among the four techniques, the visit, the order, the side, or patient gender at either time point. Following the application of Endo Ice, 81% of participants reported a sore on their palate occurring two to 48 hours after cold application and persisting for one to 10 days. The pain score for this injection had a mean value of 30% (51.4/170). CONCLUSIONS: This prospective, single-blind study evaluating three injection techniques to reduce posterior palatal injection pain to a control injection method showed no significant reduction in pain with any of the three techniques. Furthermore, 1,1,1,2-tetrafluoroethane placed with pressure for 10 seconds appeared injurious to the oral mucosa.

Effect of Ibuprofen on masking endodontic diagnosis.

INTRODUCTION: An accurate diagnosis is of upmost importance before initiating endodontic treatment; yet, there are occasions when the practitioner cannot reproduce the patient's chief complaint because the patient has become asymptomatic. Ibuprofen taken beforehand may "mask" or eliminate the patient's symptoms. In fact, 64%-83% of patients with dental pain take analgesics before seeing a dentist. The purpose of this study was to examine the possible "masking" effect of ibuprofen on endodontic diagnostic tests. METHODS: Forty-two patients with endodontic pain underwent testing (cold, percussion, palpation, and bite force measurement) and then received either placebo or 800 mg ibuprofen. Both patients and operators were blinded to the medication received. One hour later, diagnostic testing was repeated and compared with pretreatment testing. RESULTS: Ibuprofen affected testing values for vital teeth by masking palpation 40%, percussion 25%, and cold 25% on affected teeth with symptomatic irreversible pulpitis and symptomatic apical periodontitis. There was no observed masking effect in the placebo group on palpation, percussion, or cold values. When nonvital teeth were included, the masking effect of ibuprofen was decreased. However, little masking occurred with the bite force measurement differences. CONCLUSIONS: Analgesics taken before the dental appointment can affect endodontic diagnostic testing results. Bite force measurements can assist in identifying the offending tooth in cases in which analgesics "mask" the endodontic diagnosis.

An anatomic investigation of the mandibular first molar using micro-computed tomography.

INTRODUCTION: The mandibular first molar is the most frequently endodontically treated tooth and is extremely anatomically challenging. The purpose of this micro-computed tomographic evaluation was to quantitatively investigate the morphology of the mandibular first molar to improve both orthograde and retrograde treatment. METHODS: Twenty-two mandibular first molars were scanned, reconstructed, and subjected to various linear measurements. The average, standard deviation, and standard error of the mean of each linear measurement were calculated, and the mode for each nominal data category was determined. RESULTS/CONCLUSIONS: The furcal aspect of the entire mesial root should be considered a "danger zone." Mesial canals were found to be much more variable than distal canals in morphology, whereas the relative position of the orifices of the mesial canals was relatively consistent at 1.5 mm from the pulpal floor. Root-end resection of 3 mm would remove the majority of lateral canals and apical ramifications.

The effect of powder:liquid ratio and pre-mixing on sealing properties of Roth 801 sealer.

OBJECTIVES: To investigate the sealing ability of Roth 801 sealer mixed using two different powder/liquid ratios and prepared up to seven days prior to canal obturation. STUDY DESIGN: Of the 152 maxillary anterior teeth endodontically instrumented for this study, 144 were randomly assigned to the treatment group, and eight were assigned to the control group. Of the 144 teeth in the treatment group, 72 were obturated using gutta-percha and Roth 801 sealer mixed with a 10:1 ratio, while the remaining 72 were obturated with a sealer ratio of 7.5:1. Within both treatment groups, the teeth were further subdivided into six groups of 12 teeth based upon the amount of time between sealer mixing and canal obturation, which varied from 0 days to seven days. Teeth were analyzed with fluid filtration either immediately after obturation or 14 weeks after obturation. The data were analyzed using a three-way analysis of variance. RESULTS: For teeth tested at the time of obturation, leakage decreased for older sealer, p < 0.0001. After the 14-week storage period, there was no significant difference in leakage. No significant differences were noted between either powder/liquid ratios. CONCLUSIONS: Pre-mixed Roth 801 sealer maintained an apical seal when prepared up to seven days prior to canal obturation. Varying the powder/liquid ratio of Roth 801 sealer did not significantly affect the apical seal.

Mandibular first molar with six separate canals.

INTRODUCTION: Many anatomical variations can occur within the mandibular first molar. Commonly, 3-4 canals are located, but as many as 6-7 canals have been reported. METHODS: This report describes a case of a mandibular first molar with 6 separate canals (3 mesial and 3 distal) that was instrumented with conventional hand and rotary files and obturated by using a hybrid warm vertical compaction technique. RESULTS: Recall examination as far as 3 years post-treatment found no sensitivity to percussion or palpation and recall radiographs after treatment show resolution of the previous apical periodontitis. CONCLUSIONS: The existence of such teeth as these underlies the importance of looking for additional canals.

Challenges in regenerative endodontics: a case series.

INTRODUCTION: An immature tooth with pulpal necrosis and apical periodontitis presents a unique challenge to the endodontist. Endodontic treatment options consist of apexification, apical barriers, or more recently, revascularization. The purpose of this case series is to report three cases that used revascularization protocol as described by Banchs and Trope. Each case presented its own special circumstances and challenges. The lessons learned from each case provided guidance for more predictable outcomes on subsequent cases. METHODS: Six immature teeth with apical periodontitis (in three patients) were treated via the revascularization protocol using irrigants, a triple antibiotic paste, and a coronal seal of mineral trioxide aggregate and composite. RESULTS: For follow-up, all six teeth showed resolution of periapical radiolucencies, whereas three of six teeth showed continued root development. Two teeth displayed a positive response to vitality testing. CONCLUSIONS: Results from this case series show that revascularization is a technically challenging but effective treatment modality for the immature tooth with apical periodontitis. Based on this case series, the following recommendations are made to help with the revascularization technique: (1) clinicians should consider the use of an anesthetic without a vasoconstrictor when trying to induce bleeding, (2) a collagen matrix is useful for the controlled placement of MTA to a desired and optimal level, (3) patients/parents should be informed about the potential for staining, especially in anterior teeth when the paste contains minocycline, and (4) patient/parent compliance with the necessary multiple appointment treatment plan may be significant for case selection.

Identify and determine the metrics, hierarchy, and predictive value of all the parameters and/or methods used during endodontic diagnosis.

A Consensus Conference on Terminology was convened by the American Association of Endodontists in Chicago on Oct 3, 2008 to review solicited papers on focused questions. This paper addressed the question: Identify and determine the metrics, hierarchy, and predictive value of all the parameters and/or methods used during endodontic diagnosis. The best available clinical evidence was used to determine the sensitivity, specificity, and predictive value of pulpal and periapical testing methods and imaging technologies. Diagnosis of dental pulp diseases suffers from operator's inability to test/image that tissue directly due to its location within dentin. In general, current pulp tests are more valid in determining teeth that are free of disease, but less effective in identifying teeth with pulp disease. Radiographic imaging is probably the most commonly used diagnostic tool to determine the status of root-supporting tissue, although interpretation of structural changes in the periradicular tissues is still considered unreliable.

Evaluation of pretreatment analgesia and endodontic treatment for postoperative endodontic pain.

This study compares single-dose ibuprofen pretreatment for postoperative endodontic pain. Thirty-nine emergent patients were randomly assigned to 3 groups: placebo, ibuprofen tablets, or ibuprofen liquigels. Patients recorded their pain levels before and at the end of treatment, then every 6 hours for 24 hours after administration of the medications and standard endodontic treatment. Pain evaluations by using 3 pain scales (visual analog scale [VAS], category, and Heft-Parker) were highly correlated, suggesting the rationale for only using one pain scale in pain studies. No significant differences in postoperative pain levels were found between either single-dose ibuprofen formulation or the placebo control group (P = .84). Patients treated with calcium hydroxide versus obturation did not differ in postoperative pain levels (P = .44). This study suggests that single-dose pretreatment analgesia alone in endodontic pain patients will not significantly reduce postoperative pain below the reduction in pain from endodontic treatment.

Effect of irrigants and cementum injury on diffusion of hydroxyl ions through the dentinal tubules.

This study measured hydroxyl ion diffusion through dentinal tubules into a bathing solution. Eighty single-canal, instrumented teeth were divided into 8 groups. Control groups 1 and 3 were irrigated with 10 mL 0.9% saline and 10 mL 6% sodium hypochlorite (NaOCl), respectively. Control groups 5 and 7 were irrigated with 3 mL and 1 mL 17% ethylenediaminetetraacetic acid (EDTA) and then 10 mL 6% NaOCl, respectively. Experimental groups 2, 4, 6, and 8 were irrigated as groups 1, 3, 5, and 7, followed by placement of calcium hydroxide (Ca(OH)2) into canals. Bathing solution pH was recorded for 30 days, a cementum defect was made, and then pH was recorded for another 30 days. With a paired difference test, average pH during steady state was statistically different and higher after the defect (P < .001). With Tukey multiple comparisons, post-defect pH for group 6 was found to be significantly greater (P < .01) than in other groups. This study indicated final canal irrigation with 3 mL 17% EDTA and 10 mL 6% NaOCl before Ca(OH)2 placement allowed the greatest hydroxyl ion diffusion to the root surface.