July 2004, Volume 30, Number 7

A Scanning Electron Microscope Examination of Silver Cones Removed From Endodontically Treated Teeth
Samuel Seltzer, D.D.S., Daniel B. Green, D.D.S.,** Neil Weiner, D.D.S.,*** and Frank DeRenzis, D.D.S.****

Flare-ups in Endodontics: I. Etiological Factors
Samuel Seltzer, DDS, and Irving J. Naidorf, DDS

Flare-ups in Endodontics: II. Therapeutic Measures
Samuel Seltzer, DDS, and Irving J. Naidorf, DDS

Evaluation of the Whole Genome DNA-DNA Hybridization Technique to Identify Bacteria in Histological Sections of Periradicular Lesions
Susan Chan, DDS, Nadia Mohammed, BS, Justine M. Dobeck, MA, Robert R. White, DMD, Sigmund S. Socransky, DDS, and Ziedonis Skobe, PhD

Digital Radiograph Registration and Subtraction: A Useful Tool for the Evaluation of the Progress of Chronic Apical Periodontitis
Georgios Mikrogeorgis, DDS, PhD, Kleoniki Lyroudia, DDS, PhD, Ioannis Molyvdas, DDS, PhD, Nikolaos Nikolaidis, DDS, PhD, and Ioannis Pitas, DDS, PhD

Cross-sectional Morphology and Minimum Canal Wall Widths in C-shaped Roots of Mandibular Molars
Wen Lin Chai, BDS, FDSRCS, and Yo Len Thong, BDS, MSc

Polymerase Chain Reaction Identification of Microorganisms in Previously Root-Filled Teeth in a South Korean Population
Isabela N. Rôças, DDS, MSc, Il-Young Jung, DDS, MSc, PhD, Chan-Young Lee, DDS, MSc, PhD, José F. Siqueira Jr., DDS, MSc, PhD

Assessment of Elemental Composition, Microstructure, and Hardness of Stainless Steel Endodontic Files and Reamers
Myrsini Darabara, Lefteris Bourithis, Spiros Zinelis, and George D. Papadimitriou

Pain in Endodontics
Samuel Seltzer, DDS

Healing of a Radiolucent Periradicular Lesion With Periradicular Radiopacity
E. Kosti, DDS, T. Lambrianidis, DDS, PhD, P. Chatzisavvas, DDS, and I. Molyvdas, DDS, PhD

Management of Extra Oral Sinus Cases: A Clinical Dilemma
Neelam Mittal, BDS, MDS, and Pooja Gupta, BDS

Secretion of Tumor Necrosis Factor-alpha by Mouse Peritoneal Macrophages in the Presence of Dental Sealers, Sealapex and Endomethasone
Fábio Tobias Perassi, DDS, MS, Idomeo Bonetti Filho, DDS, MS, PhD, Fábio Luis Camargo Villela Berbert, DDS, MS, PhD, Iracilda Zeppone Carlos, DDS, MS, PhD, and Renato de Toledo Leonardo, DDS, MS, PhD

Cultured Primary Osteoblast Viability and Apoptosis in the Presence of Root Canal Sealers
Saud Al-Awadhi, DDS, MS, Robert Spears, PhD, James L. Gutmann, DDS, and Lynne A. Opperman, PhD

Use of Self-Etching Adhesives to Seal Resected Apices
Michael J. Murray, DMD, Robert J. Loushine, DDS, R. Norman Weller, DMD, MS, W. Frank Kimbrough, DDS, MS, and David H. Pashley, DMD, PhD

Twenty-five silver cones were removed from teeth which had been treated endodontically from 3 months to 20 years previously. Examination by the scanning electron microscope revealed that these cones were moderately to severely corroded. The corrosion patterns were described as ranging from pitting to deep crater formation with globular or spherical agglomerations. Examinations with the electron probe showed sulfur peaks on the corroded portions of the cones. X-ray diffraction analyses indicated that the chemical compounds formed were silver sulfides, silver sulfates, silver carbonates, and silver amine sulfate amide hydrates. Tissue culture studies indicated that the corrosion products were highly cytotoxic. The mechanisms for the formation of the corrosion products have been postulated as being due to plastic deformations and metal transfer to the silver cones, plus contact of the silver with tissue fluids.

Flare-ups in Endodontics: I. Etiological Factors
Samuel Seltzer, DDS, and Irving J. Naidorf, DDS

A number of hypothetical mechanisms which may be responsible for pain and swelling before and during endodontic therapy are presented. These mechanisms may be interrelated.

Se presentan un número de mecanismos hipotéticos, los cuales pueden ser responsables del dolor y el edema antes y durante la terapia endodóntica. Estos mecanismos deben ser interrelacionados.

Flare-ups in Endodontics: II. Therapeutic Measures
Samuel Seltzer, DDS, and Irving J. Naidorf, DDS

Various treatment regimens for the relief of pain during endodontic therapy, including relief of occlusion, pre-medication, establishment of drainage, and intracanal and systemic medications are presented. In addition, the rationale for the use of placebos is discussed.

Se presentan varios regimenes de tratamiento para el alivio del dolor durante la terapia endodóntica, incluyendo el alivio de la oclusión, premedicación, estable-cimiento de un drenaje ymedicaciones sistemáticas y dentro del conducto. Además, es discutido el uso racional de placebos.

Whole genome DNA-DNA hybridization has been used to identify bacteria in periradicular lesions partly because there is no amplification of the bacteria, therefore, minor contaminants are not detected. There are, however, potential pitfalls with this technique, including inability to distinguish dead bacteria, cross-reactions of species within a genus, and inability to detect species present in low numbers because of loss of DNA during extraction and purification. Alternatively, inadequate extraction and purification of DNA could result in false positives. Therefore, controls are required to monitor DNA loss, DNA cross-reactions, and DNA of pure cultures mixed with bacteria-free tissue to monitor for false positives.

We determined that the quality of DNA extracted from histological sections of periradicular lesions is excellent for DNA-DNA hybridization. Although lesions contain large numbers of bacteria, histological sections through lesions barely contain sufficient quantity of bacteria for such analysis. This was confirmed by histological observation of sparsely distributed bacteria within lesions. Furthermore, we found that the bacteria are not distributed evenly throughout periradicular lesions, in numbers or species.

The purpose of this study was to evaluate the suitability of a digital radiograph registration and subtraction software for a sensitive and reliable assessment of the progress of chronic apical periodontitis. Ninety cases of teeth with chronic apical periodontitis have been studied. In each case, a preoperative radiograph was taken, root canals were prepared, and a Ca(OH)₂ paste was placed in the root canals. Radiographic control and replacement of Ca(OH)₂ paste took place at 15-day intervals. The root canals were obturated 1.5 months after the first appointment. Recall radiographs were taken 0.5, 1.5, 3, 6, and 12 months after the obturation. All radiographs were taken for each case under constant conditions by using a direct digital radiography system. In each case, the preoperative, postoperative, and control and recall radiographs were digitally registered and pairwise subtracted. The resulting images were further processed by using contrast enhancement and pseudocoloring methods. Changes to the periapical tissue structure were easily detectable by using the above-mentioned methodology, even during short time intervals.

Cross-sectional Morphology and Minimum Canal Wall Widths in C-shaped Roots of Mandibular Molars
Wen Lin Chai, BDS, FDSRCS, and Yo Len Thong, BDS, MSc

The cross-sectional canal morphology and minimum widths of buccal and lingual canal walls were studied in 20 mandibular molars with C-shaped roots and canal orifices. The roots were mounted in clear resin blocks and sectioned transversely at 1-mm intervals. A total of 154 cross-sections were evaluated with an image analyzer. Twelve different longitudinal canal configurations were identified. The most prevalent were types 1-2 and 1-2-1 with each type occurring in four roots. Evaluation of the cross-sectional morphology showed that the configurations were complete “C” (27%), incomplete C (64%), and non-C (9%). The mean value for the minimum width of the lingual canal wall was 0.58 ± 0.21 mm and the buccal wall was 0.96 ± 0.26 mm. This suggests that there is a higher risk of root perforation at the thinner lingual walls of C-shaped canals during shaping and post canal preparation procedures. Both buccal and lingual canal walls were frequently narrower at mesial locations.

A large body of evidence indicates that microorganisms are the primary causative agents of endodontic treatment failures. This study intended to assess the occurrence of nine putative endodontic pathogens in root-filled teeth associated with periradicular lesions in a South Korean population using a culture-independent molecular approach. Fourteen root-filled teeth with persistent periradicular diseases were selected for retreatment. After removal of the root canal filling, the canals were sampled, and a polymerase chain reaction assay using taxon-specific oligonucleotide primers was used for microbial detection. Bacteria were present in all cases, as revealed by amplification using ubiquitous 16S rDNA primers. The most frequently detected taxon was Enterococcus faecalis (64%), followed by Streptococcus spp. (21%) and Tannerella forsythensis (14%). The results of this study using a highly sensitive identification method are concurrent with those from other geographical locations using diverse identification methods in that E. faecalis is the main species found in cases of root-filled teeth associated with periradicular lesions.

The purpose of this study was to determine the elemental composition, microstructure, and hardness of commercially available reamers, K files, and H files. Five instruments of each type from different manufacturers (Antaeos, FKG, Maillefer, Mani, and Micromega) were embedded in epoxy resin along their longitudinal axis. After metallographic grinding and polishing, the specimens were chemically etched and their microstructure investigated under an incident light microscope. The specimens were studied under a scanning electron microscope, and their elemental compositions were determined by energy dispersive Xray microanalysis. The same surfaces were repolished and X-ray diffraction was performed. The same specimen surface was used for the assessment of the Vickers hardness (HV200) by using a microhardness tester with a 200-g load and 20-s contact time. The hardness results were statistically analyzed with two-way ANOVA and Tukey’s test (a = 0.05). All files demonstrated extensively elongated grains parallel to longitudinal file axis because of cold drawing. The elemental composition of Maillefer and Mani reamers, Antaeos K files, and Mani H files were found in the range of AISI 303 SS, whereas all the rest were determined as AISI 304 SS. Two different phases (austenite SSt and martensite SSt) were identified with X-ray diffraction for all files tested. The results of hardness classified reamers in the following decreasing order (HMV200): Micromega = 673 ä 29a, Mani = 662 ± 24a, Maillefer = 601 ± 34b, Antaeos = 586 ± 18b, FKG = 557 ± 19c, and the K files (HV200): FKG = 673 ± 16a, Mani = 647 ± 19a, Maillefer = 603 ± 41b, Antaeos = 566 ± 21cb, Micromega = 555 ± 15c, and the H files (HMV200): Mani = 640 ± 12a, FKG = 583 ± 31b, Maillefer = 581 ± 5b, Antaeos = 573 ± 3b, Micromega = 546 ± 14b. Although only two stainless steel alloys were used for the production of endodontic files, the differences in hardness are independent to the alloys used, implying that other factors, such as the production method or the thermomechanical history of the alloys, play an important role on the mechanical properties of endodontic files.

Pain in Endodontics
Samuel Seltzer, DDS

A frequent problem in endodontics is the development of pain and swelling during or after endodontic therapy. Although the reasons for such exacerbations are not always clear, there are a number of hypotheses which will be discussed in this article.

Healing of a Radiolucent Periradicular Lesion With Periradicular Radiopacity
E. Kosti, DDS, T. Lambrianidis, DDS, PhD, P. Chatzisavvas, DDS, and I. Molyvdas, DDS, PhD

Periradicular radiopacities that reveal the existence of sclerotic bone are less common than periradicular radiolucencies. Replacement of a radiolucent periradicular area by sclerotic bone after endodontic treatment is not very often reported and may be confused with condensing osteitis. An unusual case is presented of sclerotic bone formation after endodontic treatment of a first mandibular molar with initial diagnosis of apical periodontitis.

Management of Extra Oral Sinus Cases: A Clinical Dilemma
Neelam Mittal, BDS, MDS, and Pooja Gupta, BDS

The cutaneous sinus tract of dental origin is an uncommon but well documented condition. Its diagnosis is not always easy unless the treating clinician considers the possibility of its dental origin. Such patients may undergo multiple surgical excisions, biopsies, and antibiotic regimens, but all of them fail with the recurrence of the sinus tract. This is because the primary etiology is incorrectly diagnosed. This case report describes the treatment of four patients presenting with variable complaints of pain and purulent or hemorrhagic discharge from lesions of the face. Clinical and radiographic examination revealed carious teeth with radiolucent areas indicating chronic periradicular abscess. The teeth were restorable, so nonsurgical endodontic therapy was performed in all of them. No systemic antibiotic therapy was provided. The patients responded well, and the cutaneous lesions healed uneventfully. Improper diagnosis can lead to needless loss of teeth that can be otherwise maintained through timely and proper management.

After filling root canals, the healing process depends on the chemical composition or physicalchemical properties of the material used, among other factors. All root canal sealers, whether solid or plastic, are foreign matter for the body if they remain in permanent contact with apical and periapical tissues. As a result, the first organic reaction that occurs is an attempt to phagocytize the material. During phagocytosis, macrophages release a large number of cell mediators into the area, among which are cytokines that are essential in intercellular communication and in many physiological and pathophysiological processes. One of these cytokines is tumor necrosis factor-alfa (TNF- α), which acts through links to specific receptors on the cell membrane initiating a cascade of events leading to induction, activation, or inhibition of numerous cytokine-regulated genes in the cell nucleus. The release of TNF-α in a cell culture of mouse peritoneal macrophages incubated with three concentrations (25, 50, and 100 mg/ml) of two endodontic sealers was measured. The solutions containing the calcium hydroxide-based root canal sealer (Sealapex) released fewer units of TNF-α than solutions containing the zinc oxide and eugenol-based sealer (Endomethasone).

Cultured Primary Osteoblast Viability and Apoptosis in the Presence of Root Canal Sealers
Saud Al-Awadhi, DDS, MS, Robert Spears, PhD, James L. Gutmann, DDS, and Lynne A. Opperman, PhD

This study was designed to test the hypothesis that Roekoseal is less cytotoxic than eugenol-based Sealapex or calcium hydroxide-based Kerr’s Pulp Canal Sealer. Embryonic, day-19, rat calvarial osteoblasts were cultured at 4 × 105 cells/well. The concentration of conditioned medium from each sealer producing 50% surviving cells (ED50) was determined and long-term viability and apoptosis of cells assessed after exposure to the ED50 of each sealer. Low concentrations of Kerr’s Pulp Canal Sealer (190 mm2/1 ml) and high concentrations of Sealapex and Roekoseal (190 mm2/300 µl) produced the ED50. ED50 challenged osteoblasts had fewer viable cells at 72 h than at 24 h, with significantly more viable cells in the Roekoseal group. There was significantly less apoptotic activity in cells exposed to Roekoseal ED50 than in cells exposed to Kerr’s Pulp Canal Sealer (p < 0.05) ED50. Roekoseal may be less cytotoxic than Kerr’s Pulp Canal Sealer, but further studies of this new sealer are required.

Use of Self-Etching Adhesives to Seal Resected Apices
Michael J. Murray, DMD, Robert J. Loushine, DDS, R. Norman Weller, DMD, MS, W. Frank Kimbrough, DDS, MS, and David H. Pashley, DMD, PhD

The purpose of this study was to evaluate the sealing ability of four self-etching adhesives placed over blood-contaminated/uncontaminated resected root apices without root-end preparation. Extracted maxillary incisors and canines were randomly divided into four groups of 10 teeth each. After canal preparation and resection of the apex, four self-etching adhesives (Clearfil SE Bond, One-Up Bond F, Unifil Bond, and ABF) were applied over the control and contaminated surfaces. The roots were then subjected to 15 cm of water pressure to simulate periapical microleakage stress. Data were analyzed using a two-way repeated measures, ANOVA. Positive and negative controls responded as expected. Statistical analysis indicated that there were no significant differences in the sealing effectiveness among the adhesives applied to contaminated or uncontaminated groups. All contaminated groups had significantly higher leakage (p<0.003) than their uncontaminated pairs.

AAE The Root Canal Specialists

July 2004, Volume 30, Number 7