Identification of Cultivable Microorganisms from Primary Endodontic Infections with Exposed and Unexposed Pulp Space
Frederick C. S. Chu, BDS, MSc, C. S. Peter Tsang, BDS, PhD, Tak W. Chow, BDS, MSc, PhD, Lakshman P. Samaranayake, BDS, DDS
This study was aimed at comparing the cultivable microorganisms in canals with periapical radiolucencies with exposed and unexposed pulp space. Microbiological samples were taken and analyzed from 45 canals with exposed pulp space, and 43 canals with unexposed pulp space. The canal contents were analyzed by aerobic/anaerobic culture, and conventional identification techniques. There were 211 isolates of bacteria belonging to 28 genera and 55 species recovered from exposed canals. In the unexposed group, 185 isolates of bacteria were recovered, of which 54 species of 28 genera were identified. Among the four most common genera, Prevotella was significantly more common in the exposed group (51/211 in the exposed group versus 30/185 in the unexposed group) (p = 0.049), while there were no differences in prevalence of Actinomyces, Peptostreptococcus, and Campylobacter between two groups of canals. In addition, Fusobacterium nucleatum and Propionibacterium acne were significantly more common in the unexposed canals (p = 0.047 and p = 0.0051, respectively). Similarity in bacterial species in these two groups suggests that pulp space exposure may not be a significant factor in determining the type of bacteria present in infected canals.
Comparison of Intraosseous and Infiltration Injections For Venous Lidocaine Blood Concentrations and Heart Rate Changes after Injection of 2% Lidocaine with 1:100,000 Epinephrine
Mark Wood, DDS, MS, Al Reader, DDS, MS, John Nusstein, DDS, MS, Mike Beck, DDS, MA, David Padgett, PhD, Joel Weaver, DDS, PhD
The purpose of this prospective, randomized study was to compare the venous blood levels of lidocaine and heart rate changes after intraosseous and infiltration injections of 1.8 ml of 2% lidocaine with 1:100,000 epinephrine. Using a crossover design, 20 subjects randomly received an intraosseous and infiltration injection at two separate appointments. The heart rate was measured using a pulse oximeter. Venous blood samples were collected before the injections and at 2, 5, 10, 15, 20, 25, 30, 45, and 60 min after the injections. The blinded plasma samples were analyzed for lidocaine concentrations using high-performance liquid chromatography (HPLC). The intraosseous injection resulted in a statistically significant increase in heart rate, when compared to the infiltration injection, during solution deposition and for 2 min after the injection. The plasma levels of lidocaine were not statistically different for maxillary anterior intraosseous and infiltration injections when using 1.8 ml of 2% lidocaine with 1:100,000 epinephrine.
Buccal Bone Plate Thickness of the Asian People
G-C Jin, DDS, MS, K-D Kim, DDS, PhD, B-D Roh, DDS, PhD, C-Y Lee, DDS, PhD, and S-J Lee, DDS, MS
Distances from the apex to the buccal bone plate were measured on the computed tomography (CT) images of 1806 teeth from 66 patients, using an image analyzer program (Image-Pro Plus, Ver. 4.0, Media Cybernetics). In the mandible, the mean distance from the distal apex of the mandibular second molar to the buccal bone plate was the largest distance measured, at 8.51 mm, followed by distance from the mesial root to the buccal bone (7.34 mm). In the mandibular first molar, the mean distal and mesial bone thicknesses were 5.18 mm and 4.09 mm, respectively. However, when there were two distal roots, the distance of the disto-lingual root to the buccal plate was found to be 9.52 mm, which constitutes the greatest measured thickness. In the maxillary buccal roots, the distances from the mesio-buccal and disto-buccal root of the second molar to the buccal bone plate were the largest, at 4.63 mm and 3.61 mm, respectively. The average distances from the palatal apex of the maxillary first and second molars to the buccal bone plate were 10.69 mm and 10.17 mm, respectively, while, from the palatal bone plate, average distances of 3.15 mm and 3.08 mm were measured. Special considerations, such as bony lid approach, lingual approach, or intentional replantation may be required, especially when a patient has a surgical need in the second molars and the disto-lingual root of the mandibular first molar, or in the palatal root of the maxillary molars.
Remaining Dentin Thickness in the Apical 4 mm Following Four Cleaning and Shaping Techniques
Paul J. Weller, DDS, MS, Timothy A. Svec, DDS, MS, John M. Powers, PhD, John R. Ludington, Jr, DDS, MSD, John A. Suchina, DDS, MS
The aim of this study was to determine the remaining dentin thickness (RDT) in the apical 4 mm following four cleaning and shaping techniques. Sixty human adult extracted mandibular incisors and 60 mesial buccal canals of mandibular molars were assigned to five groups of 12 teeth for each tooth type: Step-down stainless steel hand instrumentation, Lightspeed, Profile GT and 0.4 taper, K3 “g pack,” control group. After instrumentation the teeth were sectioned at 0.5, 1.5, 2.5, and 3.5 mm short of working length (WL) and evaluated for the minimum RDT at each level. ANOVA of RDT showed significant differences among levels and techniques. For incisors, no technique yielded greater RDT than the other techniques (p < 0.0001). For molars, K3 had greater RDT than the other techniques (p = 0.0006) at the 1.5, 2.5, and 3.5 mm levels. While there were significant statistical differences in RDT among techniques at different levels, further study would be required to determine any significant clinical difference in RDT.
Shaping Ability of RaCe Rotary Nickel-Titanium Instruments in Simulated Root Canals
Samantha Rangel, BDS, Renato Cremonese, BDS, Susan Bryant, BDS, Paul Dummer, DDSc
This study assessed the shaping ability of RaCe rotary nickel-titanium instruments in simulated root canals. Forty simulated root canals consisting of four different shapes were prepared with RaCe rotary nickel-titanium instruments in a crowndown approach. Preoperative images were taken at the outset and postoperative images at various stages of preparation including at the conclusion of the shaping procedure. The combined images enabled assessment of aberrations and resin removal at various positions along the canal length. Overall, mean preparation time to size 40, .02 taper was 1.36 min. Thirty-three canals (83%) maintained the working length, three instruments deformed and no zips, perforations, or ledges were created. Under the conditions of this study RaCe rotary nickel-titanium instruments prepared simulated canals rapidly and successfully, with little change in working length and with few aberrations or instrument deformities.
Bone Tissue Response to a Methacrylate-Based Endodontic Sealer: A Histological and Histometric Study
Osvaldo Zmener, DDS, Dr. Odont, Gladys Banegas, DDS, Cornelis H. Pameijer D, MD, MScD DSc, PhD
Biocompatibility of endodontic sealers is a prime requisite for successful endodontic therapy. The purpose of this study was to evaluate the reaction of bone to a methacrylate-based endodontic sealer. Silicone tubes, filled with a methacrylate-based sealer and silicone rods used as controls, were implanted in the tibias of white male Wistar rats. Ten and 60 days after implantation the reaction of the bone was analyzed by means of histological and histometric methods. After 10 days the amount of reactionary bone in contact with the methacrylate-based sealer was significantly lower than that observed for the controls (p < 0.05). Cell counts demonstrated that the number of inflammatory cells that were in contact with the sealer were significantly higher (p < 0.05). After 60 days, no significant differences were observed in the amount of reactionary bone that was in contact with either material. The initial inflammatory reaction observed for the methacrylatebased sealer was resolved. Furthermore the cell counts demonstrated no statistically significant differences (p < 0.05) between the methacrylate based sealer and control.
Disinfection of Immature Teeth with a Triple Antibiotic Paste
William Windley, III, DDS, MS, Fabricio Teixeira, DDS, MSc, PhD, Linda Levin, DDS, PhD, Asgeir Sigurdsson, DDS, MS, Martin Trope, DMD
This study assessed the efficacy of a triple antibiotic paste in the disinfection of immature dog teeth with apical periodontitis. The canals were sampled before (S1) and after (S2) irrigation with 1.25% NaOCL and after dressing with a triple antibiotic paste (S3), consisting of metronidazole, ciprofloxacin, and minocycline. At S1, 100% of the samples cultured positive for bacteria with a mean CFU count of 1.7 × 10⁸. At S2, 10% of the samples cultured bacteria-free with a mean CFU count of 1.4 × 10⁴. At S3, 70% of the samples cultured bacteria-free with a mean CFU count of only 26. Reductions in mean CFU counts between S1 and S2 (p < 0.0001) as well as between S2 and S3 (p < 0.0001) were statistically significant. These results indicate the effectiveness of a triple antibiotic paste in the disinfection of immature teeth with apical periodontitis.
Human Saliva Penetration of Root Canals Obturated with Two Types of Mineral Trioxide Aggregate Cements
Khalid Al-Hezaimi, BDS, Jafar Naghshbandi, DDS, Samuel Oglesby, DDS, James H.S. Simon, DDS, and Ilan Rotstein, DDS
The sealing ability of orthograde mineral trioxide aggregate (MTA) root canal filling against human saliva was assessed in vitro. Leakage of gray-colored MTA, white-colored MTA and vertically condensed gutta-percha and sealer were compared. Forty-three extracted single-rooted human teeth were serially instrumented to a file size 40/0.06 at the apex and obturated with either gray-colored MTA (group A), white-colored MTA (group B), or gutta-percha and Kerr Canal Sealer EWT (group C). The teeth were then mounted in a model to test for saliva leakage. After 42 days, one root in group A (9.1%), four roots in group B (36.4%), and nine roots in group C (81.8%) showed saliva leakage. Statistically, a significant difference was found between group A and group C (p < 0.001). No statistical difference was found between group A and group B. Out of the root samples that leaked, the one sample in group A leaked after 36 days. Of the four samples in group B, one sample leaked after 32 days, one sample after 33 days, and two samples after 39 days. All nine samples in group C had leaked after 19 days. It appears that under the conditions of this study both MTA preparations may be more resistant to human saliva leakage than vertically condensed gutta-percha and sealer.
Complications Associated with Fractured File Removal Using an Ultrasonic Technique
Nigel J. Souter, BDS, DClinDent, Harold H. Messer, MDSc, PhD
A technique utilizing modified Gates Glidden burs and ultrasonics has recently been advocated to remove fractured instruments from root canals. Varying extents of tooth structure are removed during this procedure, potentially leading to complications. This study evaluated the in vitro and in vivo complications associated with fractured file removal. Fractured instrument fragments were removed from three different levels (coronal, middle, or apical third) of mesiolingual canals of extracted human mandibular molars. The success rate, frequency of perforations, and root strength were recorded for each group. Perforations and unsuccessful file removal occurred only with fragments lodged in the apical third. Fracture resistance declined significantly with more apically located file fragments. A review of 60 clinical cases showed similar rates of successful file removal and rate of perforations. Removal of a fractured file fragment from the apical third of curved canals should not be routinely attempted.
Periapical Tissue Responses and Cementum Regeneration with Amalgam, SuperEBA, and MTA as Root-End Filling Materials
Seung-Ho Baek, DDS, PhD, Hanns Plenk, Jr, MD, Syngcuk Kim, DDS, PhD
The purpose of this study was to compare the periapical tissue responses and cementum regeneration in response to three widely used root-end filling materials, amalgam, SuperEBA, and Mineral Trioxide Aggregate (MTA). These materials were placed using modern microsurgical techniques on endodontically treated dog premolars and molars. After 5 months, the cell and tissue reactions of surface-stained un-decalcified ground sections were evaluated by light microscopy and statistically analyzed. The major difference in the tissue responses to the three retrofilling materials were the degree of inflammation and types of inflammatory cells, number of fibrous capsule formations, cementum neoformation over these materials, osseous healing and resulting periodontal ligament thickness. MTA showed the most favorable periapical tissue response, with neoformation of cemental coverage over MTA. SuperEBA was superior to amalgam as a root-end filling material.
A Comparison of Torque Required to Fracture Rotary Files With Tips Bound in Simulated Curved Canal
Wallace L. Guilford, DMD, Jack E. Lemons, BS, MS, PhD, Paul D. Eleazer, DDS, MS
The purpose of this study was to compare torque force and rotation needed to fracture three types of nickel titanium alloy rotary instruments in a simulated curved root canal space that were bound at the file tip. Files of similar size tips were studied. The files studied were ProFiles with 0.04 taper diameters of 15, 20, 25, 30, 35, 40, 45; 0.04 ProFile GT sizes 20, 30, 40; and ProTaper files sizes S1, S2, F1, F2, and F3. All files were 25 mm in length. Unwinding was defined as the rotation in degrees it took for a file to fracture after the first evidence of permanent deformation. All files exhibited permanent deformation before breaking, with the Pro-File GT files demonstrating the greatest unwinding. The #45 0.04 ProFile withstood the most force while the #20 ProFile GT required the least amount of force before beginning to exhibit permanent deformation. The S1 and S2 ProTaper files fractured with so little rotation that no extended data were recorded. Generally, as the file diameter increased, the force needed to begin unwinding also increased. Also, as the file diameter increased, the force needed to fracture also increased.
A Treatment Approach. A Case Report
Sashi Nallapati, BDS
Mandibular premolars have earned the reputation for having aberrant anatomy. The occurrence of three canals with three separate (type V, Vertucci) foramina in mandibular premolars is very rare. If one is to treat mandibular premolar teeth with three canals predictably, it is necessary to be aware of their clinical and radiographic anatomy. These teeth may also require special shaping and obturating techniques. This article reports and discusses the treatment recommendations for an unusual occurrence of three canals with three separate foramina in both the first and second mandibular premolars in the same patient.
Comparison of the Antimicrobial Activity of Six Irrigants on Primary Endodontic Pathogens
Katherine R. Carson, DDS, MS, Gary G. Goodell, DDS, MS, MA, Scott B. McClanahan, DDS, MS
The purpose of this study was to compare the antimicrobial activities of 6% and 3% sodium hypochlorite (NaOCl), 2% and 0.12% chlorhexidine gluconate (CHX), and 0.01% and 0.005% doxycycline (Doxy) on four microorganisms associated with primary endodontic infections. The agar diffusion test was used to measure antimicrobial activities of these agents against Peptostreptococcus micros, Prevotella intermedia, Streptococcus sanguis, and Lactobacillus acidophilus. Minimum inhibitory concentration analysis was performed using the macrodilution method. For three of the four microorganisms, the general order of antimicrobial effectiveness was 0.01% Doxy > 0.005% Doxy > 6% NaOCl > 3% NaOCl > 2% CHX > 0.12% CHX. For L. acidophilus, the order of effectiveness was 6% NaOCl > 3% NaOCl > 2% CHX > 0.01% Doxy > 0.005% Doxy > 0.12% CHX. The 6% NaOCl showed significantly greater zones of inhibition than 3% NaOCl for all endopathogens tested.
Exploiting Molecular Methods to Explore Endodontic Infections: Part 1—Current Molecular Technologies for Microbiological Diagnosis
J. F. Siqueira, Jr, DDS, MSc, PhD, and I. N. Roˆc¸as, DDS, MSc, PhD
Endodontic infections have been traditionally studied by culture-dependent methods. However, as with other areas of clinical microbiology, culture-based investigations are plagued by significant problems, including the probable involvement of viable but uncultivable microorganisms with disease causation and inaccurate microbial identification. Innumerous molecular technologies have been used for microbiological diagnosis in clinical microbiology, but only recently some of these techniques have been applied in endodontic microbiology research. This paper intended to review the main molecular methods that have been used or have the potential to be used in the study of endodontic infections. Moreover, advantages and limitations of current molecular techniques when compared to conventional methods for microbial identification are also discussed.