Long-Term Cytocompatibility of Various Endodontic Sealers Using a New Root Canal Model
Schwarze, Leyhausen and Geurtsen
Production of Macrophage Inflammatory Protein (MIP)-1α and MIP-1β by Human Polymorphonuclear Neutrophils Stimulated with Porphyromonas endodontalis Lipopolysaccharide
Ko and Lim
Microbial Susceptibility to Calcium Hydroxide Pastes and Their Vehicles
Figueiredo de Almeida Gomes, Randi Ferraz, Garrido, Rosalen, Zaia, Teixeira and de Souza-Filho
An Assessment of Microbial Coronal Leakage of Temporary Filling Materials in Endodontically Treated Teeth
Balto
Fatigue Resistance of Engine-Driven Rotary Nickel-Titanium Endodontic Instruments
Craveiro de Melo, Guiomar de Azevedo Bahiaand Lopes Buono
Fungal Infection of the Radicular Dentin
Siqueira, Jr., Rôças, Lopes, Elias and de Uzeda
Differential Scanning Calorimetric Studies of Nickel-Titanium Rotary Endodontic Instruments after Simulated Clinical Use
Brantley, Svec, Iijima, Powers and Grentzer
The Effectiveness of Increased Apical Enlargement in Reducing Intracanal Bacteria
Card, Sigurdsson, Ørstavik and Trope
The Cellular Compatibility of Five Endodontic Sealers during the Setting Period
Schwarze, Fiedler, Leyhausen, and Geurtsen
Endodontic Treatment in Cases of Allergic Reaction to Rubber Dam
Kosti and Lambrianidis
Long-Term Cytocompatibility of Various Endodontic Sealers Using a New Root Canal Model
T. Schwarze, DDS, Dr. med. dent., G. Leyhausen, Dipl.-Biol., Dr.rer.nat. and W. Geurtsen, DDS, Dr. med. dent., PhD
It was the purpose of our study to determine the cytotoxicity of several types of root canal sealers in vitro over the period of 1 yr by using a new test model.
Roots of extracted human teeth were filled with N2, Apexit, Roekoseal, AH Plus, Ketac Endo, Endomethasone, and one gutta-percha point. In addition, roots filled with laterally condensed gutta-percha/N2. Teeth filled with one gutta-percha point only were controls. All specimens were consecutively extracted with distilled water for a total of period of 1 yr. Extracts were investigated for cytotoxicity by using immortalized 3T3 fibroblasts and primary human periodontal ligament fibroblasts. Results were statistically analyzed with Dunnett’s t tests (p < 0.05).
Pronounced cytotoxic effects were only caused by N2-extracts in both cell cultures (p < 0.05). Furthermore, statistically significant cytotoxic alterations were also induced by 10-week eluates of Endomethasone (p < 0.05). All other investigated materials did not significantly alter cell metabolism.
Production of Macrophage Inflammatory Protein (MIP)-1α and MIP-1β by Human Polymorphonuclear Neutrophils Stimulated with Porphyromonas endodontalis Lipopolysaccharide
Hyun Jung Ko, DDS, MSD and Sung Sam Lim, DDS, MSD, PhD
This study was undertaken to investigate the capacity of polymorphonuclear neutrophils (PMNs) to secrete Macrophage Inflammatory Protein (MIP)-1α and MIP-1β after stimulation with Porphyromonas endodontalis lipopolysaccharide (LPS). Escherichia coli LPS was used as a positive control. Venous blood was collected and PMNs were isolated from healthy volunteers. Cells were cultured with various concentrations of LPS for different periods of time. Cell supernatants were assayed by enzyme-linked immunosorbent assay. The levels of chemokine secretion in PMNs stimulated with each LPS were found to be significantly higher than in the unstimulated control cells (p < 0.05), and this expression occurred in a time- and dose-dependent manner. E. coli LPS induced higher levels of cytokines than P. endodontalis LPS. These findings demonstrated that P. endodontalis LPS is capable of stimulating PMNs to produce chemotactic cytokines and suggested that PMNs stimulated with P. endodontalis LPS may play a crucial role in the inflammatory and immunopathological reactions of pulpal and periapical diseases.
Microbial Susceptibility to Calcium Hydroxide Pastes and Their Vehicles
Brenda Paula Figueiredo de Almeida Gomes, DDS, MS, PhD, Caio Cezar Randi Ferraz, DDS, MS, PhD, Fabio Devora Garrido, DDS, Pedro Luiz Rosalen, DDS, MS, PhD, Alexandre Augusto Zaia, DDS, MS, PhD, Fabricio Batista Teixeira, DDS, MS, PhD, and Francisco Jose de Souza-Filho, DDS, MS, PhD
The aim of this study was to investigate the susceptibility of some microorganisms commonly isolated from root canals to calcium hydroxide in combination with several vehicles by the agar diffusion method. Stainless-steel cylinders were placed on each inoculated agar medium. The test medications and their controls were placed inside the cylinders. The zones of growth inhibition were measured and recorded after the incubation period for each plate, and the results were analyzed statistically. Enterococcus faecalis was most resistant, whereas the anaerobic Porphyromonas endodontalis was more susceptible to all medications, followed by P. gingivalis and Prevotella intermedia/intermedia. Ca(OH)2 + CMCP + glycerin showed significantly larger mean zones of inhibition when compared with the other medications. We conclude that anaerobic Gram-negative bacteria are more susceptible to calcium hydroxide pastes than facultative Gram-positive microorganisms.
An Assessment of Microbial Coronal Leakage of Temporary Filling Materials in Endodontically Treated Teeth
Hanan Balto, BDS, MSc
This in vitro study evaluated the microbial leakage of Cavit, IRM, and Dyract when used as temporary filling materials after root canal treatment. The degree of coronal leakage was assessed by using a microbiological marker consisting of Streptococcus faecalis and Candida albicans. For each of the two organisms, a set of 15 maxillary premolars were prepared chemomechanically and obturated with thermoplasticized gutta-percha. A 3.5-mm thick layer of one of the three temporary filling materials was inserted in the access cavities of the teeth from each group (each group was compromised of five teeth). The control teeth (four positive and four negative) lacked any filling material over the gutta-percha, whereas the orifice and the apical foramen of the negative control were completely sealed with nail polish. Each tooth was placed in a well of a 24-well tissue culture plate and embedded in trypticase soy broth and 0.5% Bactoagar. An organism suspension was inoculated in the access cavity, and microbial penetration was detected as an increase in turbidity of the broth. At the end of 30 days, the results showed that all positive control teeth leaked within 1 week, whereas those that served as negative control remained uncontaminated throughout the test period. With both organisms, IRM started to leak after 10 days, whereas Cavit and Dyract leaked after 2 weeks.
Fatigue Resistance of Engine-Driven Rotary Nickel-Titanium Endodontic Instruments
Marta Chaves Craveiro de Melo, MSc, Maria Guiomar de Azevedo Bahia, MSc, and Vicente Tadeu Lopes Buono, Dr Eng
A comparative study of the fatigue resistance of engine-driven nickel-titanium endodontic instruments was performed, aiming to access the influence of the cutting flute design and of the size of the files that reach the working length in curved canal shaping. Geometrical conditions similar to those found in practice were used. Series 29 #5 ProFile, together with #6 and #8 Quantec instruments, were tested in artificial canals with a 45-degree angle of curvature and 5-mm radius of curvature. It was observed that the size of the instrument, which determines the maximum strain amplitude during cyclic deformation, is the most important factor controlling fatigue resistance. The effect of heat sterilization on the fatigue resistance of the instruments was also examined. The results obtained indicate that the application of five sterilization procedures in dry heat increases the average number of cycles to failure of unused instruments by approximately 70%.
Fungal Infection of the Radicular Dentin
Jose F. Siqueira, Jr., DDS, MSc, PhD, Isabela N. Rôças, DDS, Hélio P. Lopes, DDS, LD, Carlos N. Elias, PhD, and Milton de Uzeda, DDS, MSc, PhD
Although fungi have been detected in infected root canals, their precise role as endodontic pathogens has not yet been elucidated. The purpose of this study was to investigate the pattern of radicular dentin colonization by five fungal specimens. Bovine root sections were infected with each of the following fungal species: Candida albicans, Candida glabrata, Candida guilliermondii, Candida parapsilosis, and Saccharomyces cerevisiae. After 14 days, the sections were fixed in glutaraldehyde, split into two halves, critical point-dried in CO2, sputter-coated with gold, and examined under scanning electron microscopy. Regardless of the species, single or budding yeast cells were the only fungal forms observed. C. albicans colonized most of the specimens. On the other hand, the other four fungal species presented discrete or no colonization of the radicular dentin. C. albicans showed different patterns of dentin infection. In some specimens, colonization of the dentinal surface was slight and no penetration within dentinal tubules was observed. In the other specimens, some areas of the root canal walls were covered with large colonies of yeast cells and some dentinal tubules were heavily infected. The results suggested that whereas C. albicans showed the ability to colonize dentin, the other four fungal species did not. This can help to explain why C. albicans is the fungal species most often found in endodontic infections.
Differential Scanning Calorimetric Studies of Nickel-Titanium Rotary Endodontic Instruments after Simulated Clinical Use
W. A. Brantley, T. A. Svec, M. Iijima, J. M. Powers, and T. H. Grentzer
Differential scanning calometric (DSC) analyses have been performed between -130o and 100oC on single-segment specimens obtained from ProFile and Lightspeed nickel-titanium rotary endodontic instruments in the as-received condition and after one, three, and six periods of simulated clinical use in extracted teeth. The DSC analyses showed that both brands of instruments were always in the superelastic condition, although the enthalpy values for the transformation from martensitic NiTi to austenitic NiTi were much smaller for the Lightspeed instruments. Simulated clinical use had no evident effect upon this transformation for both brands, which is attributed to insufficient mechanical deformation of the instruments. There were substantial differences in the enthalpy change associated with the transformation from martensitic NiTi to austenitic NiTi for test segments from different positions along the shafts of the instruments and for as-received instruments from two different batches that were analyzed in this study and a previous study. These differences are attributed to variations in work hardening along the shaft during instrument fabrication and to processing differences during production of the two batches of each instrument brand.
The Effectiveness of Increased Apical Enlargement in Reducing Intracanal Bacteria
Steven J. Card, DDS, MS, Asgeir Sigurdsson, DDS, MS, Dag Ørstavik, DDS, PhD, and Martin Trope, DMD
It has been suggested that the apical portion of a root canal is not adequately disinfected by typical instrumentation regimens. The purpose of this study was to determine whether instrumentation to sizes larger than typically used would more effectively remove culturable bacteria from the canal.
Forty patients with clinical and radiographic evidence of apical periodontitis were recruited from the endodontic clinic. Mandibular cuspids (n = 2), bicuspids (n = 11), and molars (mesial roots) (n = 27) were selected for the study. Bacterial sampling was performed upon access and after each of two consecutive instrumentations. The first instrumentation utilized 1% NaOCl and 0.04 taper ProFile® rotary files. The cuspid and bicuspid canals were instrumented to a #8 size and the molar canals to a #7 size. The second instrumentation utilized Lightspeed® files and 1% NaOCl irrigation for further enlargement of the apical third. Typically, molars were instrumented to size 60 and cuspid/bicuspid canals to size 80.
Our findings show that 100% of the cuspid/bicuspid canals and 81.5% of the molar canals were rendered bacteria-free after the first instrumentation sizes. The molar results improved to 89% after the second instrumentation. Of the (59.3%) molar mesial canals without a clinically detectable communication, 93% were rendered bacteria-free with the first instrumentation.
Using a Wilcoxon rank sum test, statistically significant differences (p < 0.0001) were found between the initial sample and the samples after the first and second instrumentations. The differences between the samples that followed the two instrumentation regimens were not significant (p = 0.0617). It is concluded that simple root canal systems (without multiple canal communications) may be rendered bacteria-free when preparation of this type is utilized.
The Cellular Compatibility of Five Endodontic Sealers during the Setting Period
T. Schwarze, DDS, Dr. med. dent., I. Fiedler, DDS, G. Leyhausen, Dipl.-Biol., Dr.rer.nat., and W. Geurtsen, DDS, Dr. med. dent., PhD
The purpose of this study was to evaluate the cellular compatibility of five endodontic sealers in the first 24 h after mixing.
Specimens of N2, Endomethasone, Apexit, AH Plus, and Ketac Endo were extracted with cell culture medium 0, 1, 5, and 24 h after mixing. Eluates were tested for cytotoxicity with immortal 3T3 cells and primary human periodontal ligament fibroblasts using XTT-assays. Data were analyzed for statistically significant differences by means of Dunnett’s t tests (p < 0.05).
All extracts of N2 completely inhibited cell metabolism (p < 0.05). Similar effects were provoked by the first three eluates of Endomethasone, but the 24-h extract irritated cells significantly less (p < 0.05). Severe cytotoxicity was also observed with all Ketac Endo extracts (p < 0.05). A significant inhibition of mitochondrial activity was induced by the first (3T3) or the first and second eluate (periodontal ligament fibroblasts) of AH Plus (p < 0.05). The subsequent eluates of this sealer and all extracts of Apexit did not reveal any cytotoxic potency.
Endodontic Treatment in Cases of Allergic Reaction to Rubber Dam
Eleni Kosti, DDS and Theodor Lambrianidis, DDS, PhD
The prevalence and severity of latex allergies have rapidly increased recently. This article presents two cases of patients with rubber latex allergy. The patient in case A was unaware of her sensitivity to latex and presented symptoms of contact dermatitis-stomatitis during endodontic treatment. The patient in case B reported latex allergy before the initiation of the treatment and a different approach was followed. Certain aspects of latex allergy related to the endodontic treatment are discussed. Moreover, a protocol is proposed for treatment of patients with latex hypersensitivity with safety.