Resorcinol-Formaldehyde Resin “Russian Red” Endodontic Therapy
Nathan W. Schwandt and Tom G. Gound
Positive and Negative Bacterial Associations Involving Dialister pneumosintes in Primary Endodontic Infections
José F. Siqueira Jr. and Isabela N. Rôças
Periapical Inflammation Affecting Coronally-inoculated Dog Teeth with Root Fillings Augmented by White MTA Orifice Plugs
Terence Mah, Bettina Basrani, João M. Santos, Elizeu A. Pascon, Leo Tjäderhane, Ghassan Yared, Herenia P. Lawrence, and Shimon Friedman
Effect of Rotational Speed on Root Canal Preparation with Hero 642 Rotary Ni-Ti Instruments
Işil Karagoöz-Küçükay, HandanErsev, Ece Engin-Akkoca, Sedat Küçükay, and Tankut Gürsoy
In Vitro Antimicrobial Efficacy of MTAD and Sodium Hypochlorite
Shahrokh Shabahang, Manouchehr Pouresmail, and Mahmoud Torabinejad
In Vitro Evaluation of the Cytocompatibility of a Glass-Ionomer Cement Sealer
Y. Yoshimine, M. Yamamoto, T. Ogasawara, Y. Koishi, K. Tanabe, I. Hashiguchi, and A. Akamine
Calibrated Latex Microspheres Percolation: A Possible Route to Model Endodontic Bacterial Leakage
Pierre Michaïlesco and Philippe Boudeville
Computed Tomography as a Diagnostic Aid for Extracanal Ivasive Resorption
Euiseong Kim, Kee-Deog Kim, Byoung-Duck Roh, Yong-Sik Cho, and Seung-Jong Lee
Modified Usage of the Masserann Kit for Removing Intracanal Broken Instruments
Takashi Okiji
Resorcinol-Formaldehyde Resin “Russian Red” Endodontic Therapy
Nathan W. Schwandt, DDS, and Tom G. Gound, DDS, MS
Resorcinol-formaldehyde resin is a material used in endodontic therapy in many foreign countries. With immigration to the United States increasing, American dentists need to become familiar with resorcinol-formaldehyde therapy. It contains two potentially toxic components, formaldehyde (liquid) and resorcinol (powder). Zinc oxide or barium sulfate may be used for radiopacity. When 10% sodium hydroxide is added to the mixture, polymerization occurs, which can form a brick-hard red material that has no known solvent. Several variations in technique exist. The catalyst can be mixed in before insertion into the tooth, added after the mixture is inserted, or not used. Providers believe pulp tissue will be fixed and bacteria destroyed apical to the level of resorcinol-formaldehyde resin placement. Canals are frequently not instrumented or obturated to their full length. Few success-failure studies have been published and results are contradictory. Consequently, providers have little guidance regarding when to retreat or for predicting the difficulty of retreatment.
Positive and Negative Bacterial Associations Involving Dialister pneumosintes in Primary Endodontic Infections
José F. Siqueira Jr., DDS, MSc, PhD, and Isabela N. Rôças, DDS, MSc
Dialister pneumosintes is an anaerobic Gram-negative rod that has been recently implicated as a candidate endodontic pathogen. In this study, samples taken from abscessed teeth and infected root canals associated with asymptomatic or symptomatic periradicular lesions were examined for the occurrence of bacterial associations involving D. pneumosintes. DNA was extracted from the samples, and the presence of D. pneumosintes and 16 other bacterial species was determined by means of species-specific nested polymerase chain reaction. Positive and negative associations involving D. pneumosintes were investigated by computing the odds ratio of D. pneumosintes being found in a sample from endodontic infection in co-infection with one of the other target species. The association between the pairs containing D. pneumosintes and the occurrence of pain also was evaluated. D. pneumosintes was always detected in mixed infections with at least two of the other target species. D. pneumosintes was positively associated with Treponema denticola, porphyromonas endodontalis, Fusobacterium nucleatum, Peptostreptococcus micros, Campylobacter rectus, Prevotella intermedia, T. pectinovorum, and T. vincentii. Negative associations were observed iwth Bacteroides forsythus, P. gingivalis, and Actinomyces israelii. No pair containing D. pneumosintes was found to be significantly associated with symptomatic cases (p > 0.01). The findings of this study lend considerable support to the notion of D. pneumosintes being an important endodontic pathogen, usually in a mixed infection. Positive associations of this species with other highly prevalent species, such as T. denticola and P. endodontalis, suggest that bacterial synergism can occur and thereby play an important role in the pathogenesis of different forms of periradicular lesions.
Periapical Inflammation Affecting Coronally-inoculated Dog Teeth with Root Fillings Augmented by White MTA Orifice Plugs
Terence Mah, DDS, MS, Bettina Basrani, DDS, PhD, João M. Santos, DDS, MS, Elizeu A. Pascon, DDS, MSD, PhD, Leo Tjäderhane, DDS, PhD, Ghassan Yared, DDS, MSc, Herenia P. Lawrence, DDS, PhD, and Shimon Friedman, DMD
Placement of orifice plugs has been suggested to augment the seal of conventional root canal fillings. This study assessed in vivo the efficacy of white mineral trioxide aggregate (MTA) plugs in preventing periapical inflammation subsequent to coronal inoculation of root-filled teeth. The two-rooted mandibular permolars of six beagle dogs were conventionally prepared and filled with gutta-percha and sealer. A white MTA orifice plug was placed into one canal in each tooth. Pulp chambers were inoculated with plaque except for 12 teeth (negative control), and restored. Radiographs were taken at regular intervals. At 10 months, dogs were killed and jaw blocks processed for histology. None of the roots revealed radiographic or histologic evidence of severe inflammation. Mild inflammation was observed in 17% and 39% of the roots with and without an orifice plug, respectively (McNemar, p > 0.05). Without development of severe inflammation, the seal augmentation efficacy of MTA orifice plugs could not be determined.
Effect of Rotational Speed on Root Canal Preparation with Hero 642 Rotary Ni-Ti Instruments
Işil Karagoöz-Küçükay, DDS, PhD, Handan Ersev, DDS, PhD, Ece Engin-Akkoca, DDS, PhD, Sedat Küçükay, DDS, PhD, and Tankut Gürsoy, DDS, PhD
The purpose of this study was to evaluate the influence of Hero 642 rotary Ni-Ti instruments driven at 300, 400, or 600 rpm on root canal straightening, loss of working length, and instrument breakage. Sixty mesial root canals from extracted human mandibular molars were divided into 3 groups of 20 each and were instrumented at the aforementioned rotational speeds with a crown-down technique. Using a digital intraoral radiography system directly on the images of pre- and postoperative radiographs, degrees of canal curvatures were measured and recorded. Statistical analysis showed that final canal curvatures and working lengths were significantly reduced compared with those of original values in each group (p < 0.001). However, using Hero 642 rotary Ni-Ti system at different rotational speeds had no effect on canal curvature and working length alterations (p > 0.005). No file breakage was observed in any of the groups.
In Vitro Antimicrobial Efficacy of MTAD and Sodium Hypochlorite
Shahrokh Shabahang, DDS, MS, PhD, Manouchehr Pouresmail, DMD, and Mahmoud Torabinejad, DMD, MSD, PhD
The purpose of this study was to compare the ability of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) with that of sodium hypochlorite (NaOCI) to disinfect human root canals that had been contaminated with whole saliva. One hundred and thirty-two root canals of extracted human teeth were cleaned and shaped using the passive step-back technique and rotary NiTi files. The smear layer was removed, and the teeth were autoclaved. Six autoclaved samples were transferred to sterile broth without contamination with saliva to serve as negative controls. Whole saliva was used to contaminate the root canals of the rest of the samples for 48 h. Six of these contaminated samples were irrigated with Brain Heart Infusion (BHI) broth and served as positive controls. The rest of the contaminated specimens were then divided into two experimental groups of 60 teeth each. In one group, the canals were irrigated with 1 ml MTAD, and the samples were immersed in 2 ml of the same solution for 5 min. In the second group, the specimens were similarly treated with 5.25% NaOCI. All samples were washed in BHI broth and then placed in another tube containing BHI broth and incubated for 96h. Disinfection of the samples was determined based on presence or absence of turbidity in the broth 96 h later. Twenty-three of 60 teeth treated with NaOCI remained infected. Only one of 60 teeth treated with NaOCI remained infected. Only one of 60 teeth treated with MTAD remained infected. Statistical analysis of the data using the Chi-square test showed a significant difference between the two groups (p < 0.0001).
In Vitro Evaluation of the Cytocompatibility of a Glass-Ionomer Cement Sealer
Y. Yoshimine, DDS, PhD, M. Yamamoto, DDS, T. Ogasawara, DDS, Y. Koishi, DDS, K. Tanabe, DDS, PhD, I. Hashiguchi, DDS, and A. Akamine, DDS, PhD
The purpose of this study was to evaluate the cytocompatibility of two different types of root canal sealers in cell culture. Human periodontal ligament cells were cultured with set materials from an experimental glass-ionomer cement sealer (KT-308) and a commercially available zinc oxide-eugenol-based sealer (Canals) for 1, 3, and 7 days. Cytotoxic effects were evaluated from the morphological changes under a light microscope. Canals induced severe degenerative alteration of human periodontal ligament cells. In contrast, human periodontal ligament cells adjacent to KT-308 showed normal morphology and growth during the culture period. These results suggest that the glass-ionomer cement sealer, KT-308, is cytocompatible and has good potential as a root canal sealer.
Calibrated Latex Microspheres Percolation: A Possible Route to Model Endodontic Bacterial Leakage
Pierre Michaïlesco, DCD, PhD, and Philippe Boudeville, PhD
Endodontic therapy is conducted to effectively seal the root canal system. In vitro methods are used to estimate the quality of the seal, generally by measuring any microleakage that allows the tracers to penetrate along the obturated root canal. The use of bacteria as traces seems to give the most clinically relevant demonstration of microleakage associate with a root canal system. Many bacterial strains have been used to evaluate marginal leakage, but results are sometimes contradictory, probably because they may depend on the bacterial strain used. In the studies described in this article, the percolation of both calibrated latex microspheres equivalent in diameter (0.4-9.5 μm) to bacteria and three bacterial strains (Actinomyces odontolyticus, Lactobacillus acidophilus, and Pseudomonas fluorescens) was compared in teeth filled using noncompressive and compressive techniques. The depth (d) to which the microspheres and bacteria penetrated varied over the time (t) of contamination according to a logarithmic relation. The slope (S) and the intercept (I, corresponding to penetration after 1 month) of the d = f(ln t) plots can serve to quantify penetration over time. Statistical analysis of 1 by the Newman-Keuls procedure, which couples the tracers and filling techniques, showed that A. odontolyticus and L. acidophilus behave like 4.8μm particles and P. fluorescens like 2.2 μm particles (corresponding approximately to their size in length) and that noncompressive techniques are less hermetic than compressive techniques. S and l are in direct relation and this relation is independent of the filling technique. Moreover, for the calibrated particles, both l and S varied linearly with the inverse of the square root of the particle diameter, indicating that their displacements are governed solely by Brownian movements and the penetration over time is caused by diffusion phenomena. The size of the tracer is the predominant factor governing its penetration. Inert particles mimic bacterial percolation into the marginal hiatus and can thus be used to model this percolation and establish a relative scale of the behavior of different bacteria during percolation.
Computed Tomography as a Diagnostic Aid for Extracanal Invasive Resorption
Euiseong Kim, DDS, MDS, Kee-Deog Kim, DDS, MSD, PhD, Byoung-Duck Roh, DDS, MSD, PhD, Yong-Sik Cho, DDS, and Seung-Jong Lee, DDS, MS
A case of multiple extracanal invasive resorption is reported. The patient had a history of hypothyroidism for approximately 1 yr before the dental visit. Utilization of computed tomography and a rapid prototyping tooth model in diagnosing the exact location and the size of the resorption area are discussed.
Modified Usage of the Masserann Kit for Removing Intracanal Broken Instruments
Takashi Okiji, DDS, PhD
The Masserann kit is a hollow tube device specially designed for the removal of intracanal metallic objects. This report describes some modifications in the usage of this device for effective removal of tightly bound intracanal broken instruments whose diameter is relatively large at the coronal end. The techniques described are: (1) modification of the extractor to ensure gripping by creating a wider space inside the tube; and (2) combined use of the modified extractor with an ultrasonic device and a surgical operating microscope. A clinical case demonstrating that these modifications resulted in successful retrieval of firmly wedged instruments is presented.