Relationship between Canal Enlargement and Fracture Load of Root Dentin Sections.

OBJECTIVE: To investigate the effect of endodontic instrumentation on fracture susceptibility of root dentin using experiments and stress analysis. METHODS: Root canals of lower premolars were enlarged with different tapers. After, teeth were cut into 2-mm sections. A metal rod of the same taper was pushed through the center of the sections using a universal test system to fracture them. The fracture load was determined from the peak load on the load-displacement curve. To determine fracture-causing stress, an axisymmetric FE model was created. An analytical solution was developed to understand the relationship between fracture load, geometrical and material parameters. RESULTS: For the same taper, increased root canal diameter did not lead to reduced fracture load. Both analytical and FE solutions showed positive linear relationship between fracture load and enlarged root canal diameter. The hoop stress was maximum at inner surface of enlarged root canal and reduced with increasing radial distance from the center. Bending of sections introduced further nonuniform stresses along the depth. Predictions for the fracture load based on the maximum hoop stress were closest to experimental values; however, account must be taken of the variation in fracture stress of dentin along the root length. Significance Our results rejected the hypothesis that fracture load of root dentin sections reduced with endodontic instrumentation size. However, the stress distributions in whole endodontically treated teeth are more complicated. Thus, caution is necessary when using thin root sections to investigate the effect of endodontic instruments on vertical root fracture.

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.

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.

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.

Malignant lymphoma in maxilla with cystic involvement: a case report.

INTRODUCTION: Most radiolucent jaw lesions are benign and resolve with proper diagnosis and treatment. However, a small percentage of radiolucent jaw lesions are malignant and more difficult to manage. METHODS: A biopsy of the radiolucent jaw lesion associated with swelling after nonsurgical root canal therapy was submitted. RESULTS: The lesion had the combined diagnosis of diffuse large B-cell lymphoma with cystic involvement. The patient has since undergone radiation and chemotherapy treatments. Recall appointments indicate healing of the lesion, and no other areas of lymphoma have been found. CONCLUSIONS: The existence of a nonhealing radiolucent jaw lesion emphasizes the importance of an early, definitive diagnosis with biopsy.

Comparison of heat-testing methodology.

INTRODUCTION: Patients with irreversible pulpitis occasionally present with a chief complaint of sensitivity to heat. To appropriately diagnose the offending tooth, a variety of techniques have been developed to reproduce this chief complaint. Such techniques cause temperature increases that are potentially damaging to the pulp. Newer electronic instruments control the temperature of a heat-testing tip that is placed directly against a tooth. The aim of this study was to determine which method produced the most consistent and safe temperature increase within the pulp. This consistency facilitates the clinician's ability to differentiate between a normal pulp and irreversible pulpitis. METHODS: Four operators applied the following methods to each of 4 extracted maxillary premolars (for a total of 16 trials per method): heated gutta-percha, heated ball burnisher, hot water, and a System B unit or Elements unit with a heat-testing tip. Each test was performed for 60 seconds, and the temperatures were recorded via a thermocouple in the pulp chamber. Analysis of the data was performed by using the intraclass correlation coefficient. RESULTS: The least consistent warming was found with hot water. The heat-testing tip also demonstrated greater consistency between operators compared with the other methods. Hot water and the heated ball burnisher caused temperature increases high enough to damage pulp tissue. CONCLUSIONS: The Elements unit with a heat-testing tip provides the most consistent warming of the dental pulp.

Frequency and distribution of radiolucent jaw lesions: a retrospective analysis of 9,723 cases.

OBJECTIVES: Practitioners should be aware of the occurrence rate and usual location of radiolucent jaw lesions. The aims of this study were to examine the frequency and location of radiolucent jaw lesions, including apical granulomas, apical cysts, keratocystic odontogenic tumors (KOTs), central giant cell lesions (CGCLs), ameloblastomas, and metastatic lesions, that were submitted for biopsy along with associated demographics. METHODS: Biopsy diagnoses from 9,723 lesions (submitted between 1992 and 2006) were included in this study. Data on lesion location as well as patient demographics were evaluated. RESULTS: Thirty types of radiolucent jaw lesions were classified. Nonhealing apical granulomas (40.4%) and cysts (33.1%) occurred at similar rates and together totaled 73% of all biopsied lesions. The majority of reported granulomas and cysts occurred in the anterior maxilla (>36% in each category). The frequency of KOTs (8.8%), CGCLs (1.3%), ameloblastomas (1.2%), and metastatic lesions (<1%) are to be noted along with their location, which was predominately in the posterior mandible. The occurrence of apical cysts, ameloblastomas, KOTs, and metastatic lesions were seen slightly more in men, at 56%, 54%, 55%, and 68%, respectively. The occurrence of CGCLs was seen slightly more in women at 56%, whereas apical granulomas were equally present in men and women. CONCLUSIONS: Most nonhealing lesions submitted for biopsy were classified as granulomas or cysts (73%) often from the anterior maxillary jaw. Nonhealing radiolucent jaw lesions other than granulomas or cysts were reported over 20% of the time and may have more severe pathological implications, suggesting the value of differential diagnoses.

Endodontic diagnostic terminology update.

Determination of the etiology of the patient's chief complaint and a correct diagnosis are paramount prior to a recommendation of endodontic therapy. Reproduction of the patient's chief complaint is critical. If the chief complaint cannot be reproduced, consider consultation with or referral to an endodontist or orofacial pain specialist. The diagnostic terminology presented in this update provides for a more accurate description and communication of the health or pathological conditions of both pulpal and apical tissues. This information is summarized in Table I.

Sex differences in neuropeptide content and release from rat dental pulp.

INTRODUCTION: Studies to examine sex differences in response to pain have suggested that females exhibit lower threshold responses to painful stimuli and that threshold response varies greatly at different stages of the menstrual cycle. Additional studies suggest that sex differences may be caused by societal sex roles or differences in anxiety responses by men and women. OBJECTIVE: The purpose of this study was to evaluate biologically evident sex differences in male and female rats chronically treated with a systemic algogen, the nerve growth factor (NGF), by measuring neuropeptides (calcitonin gene-related peptide) content and release from isolated dental pulp. METHODS: Rats were injected subcutaneously every other day with either murine NGF (1 mg/kg) or vehicle for 7 or 13 days. Isolated incisor pulp tissue was evaluated from these male and female rats (n = 96). Capsaicin-evoked neurosecretion of CGRP and tissue content were measured using a previously validated radioimmunoassay. RESULTS: Dental pulp from female rats at 7 days showed significantly increased capsaicin-evoked immunoreactive CGRP release (>50% increase) compared with tissue from male rats. After 13 days, this release was significantly increased only in NGF-treated female rats (3-fold increase) when compared with control females or both male groups. The CGRP content in tissue from both female groups was also significantly increased after 7 days of treatment (>3 fold), but after 13 days this content was only significantly increased in tissue from NGF-treated female rats (P = .0001). CONCLUSIONS: These data suggest that sex differences affect the role of NGF in the modulation of inflammation through the regulation of peripheral neuropeptide release and content.

Cone-beam computed tomography evaluation of maxillary sinusitis.

INTRODUCTION: Dental pain originating from the maxillary sinuses can pose a diagnostic problem. Periapical lesion development eliciting inflammatory changes in the mucosal lining can cause the development of a sinusitis. The purpose of this study was to describe the radiographic characteristics of odontogenic maxillary sinusitis as seen on cone-beam computed tomography (CBCT) scans and to determine whether any tooth or any tooth root was more frequently associated with this disease. METHODS: Eighty-two CBCT scans previously identified as showing maxillary sinus pathosis were examined for sinusitis of odontogenic origin in both maxillary sinuses. RESULTS: One hundred thirty-five maxillary sinusitis instances with possible odontogenic origin were detected. Of these, 37 sinusitis occurrences were from nonodontogenic causes, whereas 98 instances were tooth associated with some change in the integrity of the maxillary sinus floor. The average amount of mucosal thickening among the sinusitis cases was 7.4 mm. Maxillary first and second molars were 11 times more likely to be involved than premolars, whereas either molar was equally likely to be involved. The root most frequently associated with odontogenic sinusitis is the palatal root of the first molar followed by the mesiobuccal root of the second molar. CONCLUSIONS: Changes in the maxillary sinuses appear associated with periapical pathology in greater than 50% of the cases. Maxillary first or second molar teeth are most often involved, and individual or multiple roots may be implicated in the sinusitis. The use of CBCT scans can provide the identification of changes in the maxillary sinus and potential causes of the sinusitis.

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.

Sniffing out endodontic pain: use of an intranasal analgesic in a randomized clinical trial.

INTRODUCTION: Orofacial pain is a common encounter in dentistry (affecting 12% of the population) and is a primary reason for patients seeking emergency care. Dentists often prescribe oral analgesics, which have disadvantages of decreased absorption rates and delayed onset. Intranasal (IN) delivery takes advantage of a large surface area of mucosal tissue for rapid absorption. The purpose of this study was to evaluate the efficacy of IN ketorolac for endodontic pain using a randomized, double-blind, placebo-controlled parallel design study. METHODS: Twenty-two patients presenting with moderate to severe endodontic pain were selected to receive IN treatment with placebo (n = 11) or ketorolac (n = 11) 30 minutes before endodontic treatment was started and immediately after the completion of endodontic treatment. Baseline pain levels were recorded before IN treatment. Pain levels were also recorded at 15 and 30 minutes after the initial IN dosing (before endodontic treatment); 30 minutes after completion of endodontic treatment; and 4, 8, and 12 hours after the initial IN spray. Primary analysis was a repeated-measures analysis of variance. RESULTS: IN ketorolac alone or with endodontic treatment showed significantly better pain relief compared with IN placebo spray alone or with endodontic treatment at 30 minutes after the first or second intranasal dose and at 4 hours after the first intranasal dose (P = .03). CONCLUSIONS: These results suggest that IN ketorolac may provide a novel and efficacious method for pain relief in endodontic pain patients.