Nikolaos Economides

Long-Term Evaluation of the Influence of Smear Layer Removal on the Sealing Ability of Different Sealers

The purpose of this study was to examine the effect of the smear layer on apical microleakage over 16 wk. One hundred and four extracted human teeth were assigned to four groups treated as follows: group A1--smear layer was left intact and canals were obturated with gutta-percha and Roth 811; group A2--smear layer was left intact and canals were obturated with gutta-percha and AH26; group B1--smear layer was removed and canals were obturated with gutta-percha and Roth 811; and group B2--smear layer was removed and canals were obturated with gutta-percha and AH26. Microleakage was measured by the electrochemical method. In parallel, 12 teeth were examined under a scanning electron microscope. The results indicated that the smear layer removal resulted in a statistically significant reduction of microleakage values in groups obturated with AH26. The presence or absence of smear layer had no significant effect on the sealing ability of Roth 811.

Experimental study of the biocompatibility of four root canal sealers and their influence on the zinc and calcium content of several tissues

Four root canal sealers (AH-26, Roth 811, CRCS, and Sealapex) were tested for tissue biocompatibility in rat connective tissue. Each sealer was placed in Teflon tubes and implanted subcutaneously in Wistar-Furth rats. The implants were removed after 7, 14, and 21 days, fixed, and histologically prepared for microscopical evaluation. Brain, liver, kidneys, and uterus were removed from the animals killed at the first experimental period (7 days) and analyzed for zinc and calcium concentration by flame atomic absorption spectrophotometry. In total, 100 specimens were examined. At the seventh day, the most irritant material was seen to be AH-26, but this inflammatory reaction decreased with time. Roth 811 and Sealapex caused moderate-to-severe inflammatory reaction, whereas CRCS caused mild to moderate. CRCS and Roth 811 induced redistribution of zinc, whereas AH-26 induced changes in calcium content in some organs.

Comparative Study of Apical Sealing Ability of a New Resin-Based Root Canal Sealer

The purpose of this study was to compare the microleakage of two root canal sealers, Fibrefill (resin-based sealer) and calciobiotic root canal sealer (CRCS; calcium hydroxide-based sealer), with and without the presence of smear layer. The model used for the measurement of microleakage was a fluid transport model. Sixty human extracted teeth were used in this study. The teeth were divided into four groups and treated as follows. In group A, the smear layer was left intact, and canals were obturated with gutta-percha and Fibrefill. In group B, the smear layer was removed, and canals were obturated with gutta-percha and Fibrefill. In group C, the smear layer was left intact, and the canals were obturated with gutta-percha and CRCS. In group D, the smear layer was removed, and canals were obturated with gutta-percha and CRCS. Microleakage was measured at 7 days, 1 month, and 2 months. The results showed that the Fibrefill groups with and without smear layer leaked significantly less than the CRCS groups at all experimental times. No significant difference was found between the groups of same materials, but the microleakage values were less when the smear layer was removed.

In vivo comparison of the biocompatibility of two root canal sealers implanted into the subcutaneous connective tissue of rats

The purpose of this study was to evaluate the in vivo biocompatibility of Apexit (a calcium hydroxide) and Pulp Canal Sealer (a classic zinc oxide-eugenol), root canal sealers, after implantation in rat connective tissue. Forty-four white female Wistar-Furth rats were used. Each sealer was placed in Teflon tubes and implanted into specific dorsal subdermal tissues sites. Implants were removed after 5, 15, 60, and 120 days; fixed; and histologically prepared for microscopical evaluation. Severe inflammatory reactions with differing extensions of necrosis were observed with Apexit on the 5th and 15th days. The intensity of the reaction had diminished by the 60th day, and this reduction continued progressively through the 120th day. It was characterized by the presence of connective tissue with a few macrophages. Moderate to severe inflammation with confined areas of necrosis was observed in the Pulp Canal Sealer specimens on the 5th day. The intensity of the reaction diminished by the 15th, 60th, and 120th days, but remained slightly greater than Apexit through longterm observation periods.

Antiproliferative Effect of Mineral Trioxide Aggregate, Zinc Oxide-Eugenol Cement, and Glass-Ionomer Cement Against Three Fibroblastic Cell Lines

An important requirement for dental materials placed in direct contact with living tissues is biocompatibility. The purpose of this study was to evaluate the antiproliferative activity of three dental materials (mineral trioxide aggregate, zinc oxide-eugenol cement, and glass-ionomer cement) against a panel of established fibroblastic cell lines (L929, BHK21/C13, and RPC-C2A). The materials were prepared according to the manufacturers instructions and were tested in insert wells for 12, 24, and 48 h. Cell number fraction was estimated by the sulforhodamine-B assay, in reference to controls. The degree of antiproliferative effect in ascending order was mineral trioxide aggregate, glass-ionomer cement, and zinc oxide-eugenol cement in all cell lines tested.

Experimental study of the biocompatibility of a new glass-ionomer root canal sealer (Ketac-Endo)

Ketac-Endo, a new glass-ionomer cement for endodontic use as root canal sealer, and Tubli-Seal were tested for tissue biocompatibility in rat connective tissue. Forty-four white female Wistar-Furth rats were used. Each sealer was placed in Teflon tubes and implanted subcutaneously. The implants were removed after 5, 15, 60, and 120 days; fixed; and histologically prepared for microscopical evaluation. Mild inflammatory reaction was observed with Ketac-Endo on the 5th day. The connective tissue was infiltrated with plasma cells. Lymphocytes and macrophages were observed. The intensity of the reaction diminished by the 15th day, and this reduction continued progressively through the 60th and 120th days. Severe inflammation with differing extensions of necrosis was observed with Tubli-Seal on the 5th and 15th days, and the material remained irritating even after long-term implantation periods (60 and 120 days).

Top-cited Articles in Endodontic Journals

INTRODUCTION The purpose of this study was to identify the 100 top-cited articles published in journals dedicated to endodontology and analyze their characteristics to describe the quality and evolution of research in the field of endodontology. METHODS The Institute for Scientific Information Web of Knowledge Database and the Journal Citation Report Science Editions were used to retrieve the 100 most cited articles published in journals dedicated to endodontics. The top-cited articles were selected and analyzed with regard to journals, authors, institution, country of origin, publication title and year, number of citations, article type, study design, level of evidence, and field of study. RESULTS The top 100 articles were cited between 87 and 554 times. These articles appeared in 4 different journals, with more than half in the Journal of Endodontics, followed by the journals Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, the International Endodontic Journal, and Endodontics & Dental Traumatology. Forty-eight articles were published between 1990 and 1999. All articles were published in English and primarily originated from the United States (n = 52). The majority of articles were basic science articles (n = 55), followed by clinical research studies (n = 28) and nonsystematic reviews (n = 17). Uncontrolled case series with level IV of evidence and narrative reviews with level V of evidence were the most frequent types of study design. The main topics covered by the top-cited articles were microleakage and endodontic microbiology. CONCLUSIONS This analysis of citation rates reveals useful and interesting information about scientific progress in the field of endodontics. Basic research and observational studies published in high-impact endodontic journals had the highest citation rates.

Shear bond strength of AH-26 root canal sealer to dentine using three dentine bonding agents

OBJECTIVE The purpose of the study was to compare the bond strength of AH-26 root canal sealer to human root canal dentine exposed to different intracanal medications both with and without the use of three bonding agents. The materials used were AH-26 sealer, two one-bottle bonding agents (Single Bond, Bond-1) and one self-etching bonding agent (Clearfill SE Bond). METHODS The dentine substrate was obtained from single rooted human teeth. The dentine specimens were treated either with EDTA 15% or phosphoric acid 37% to achieve the removal of smear layer. The AH-26 sealer was placed on the dentine surfaces both with and without the use of the bonding agents. Bond strength was tested using a single plane shear test assembly. RESULTS The SBS values were (MPa): Group A (EDTA-AH-26) 3.678+/-0.853, Group B (Phosphoric acid-AH-26) 3.470+/-0.834, Group C (EDTA-Single Bond-AH-26) 4.8+/-0.865, Group D (Phosphoric acid-Single Bond-AH-26) 5.043+/-1.022, Group E (EDTA-Bond 1-AH-26) 4.939+/-0.877, Group F (Phosphoric acid-Bond 1-AH-26) 5.101+/-1.117, Group G (Clearfill SE Bond-AH-26) 6.975+/-1.694. The use of dentine bonding agents improved significantly (p<0.05) the adhesion of AH-26 sealer with the root canal dentine. However, the best results were obtained with the self-etching system. Similar results were observed from the pretreatment of dentine either with phosphoric acid 35% or EDTA 15%. CONCLUSIONS The use of dentine bonding agents gave higher shear bond strengths of AH-26 sealer to human root canal dentine.

In vitro release of hydroxyl ions from calcium hydroxide gutta-percha points.

In endodontic practice, calcium hydroxide is widely used for a number of reasons associated with its high pH. The purpose of the present study was to determine in vitro the alkalizing potential of newly introduced calcium hydroxide gutta-percha points that are proposed for temporary filling of root canals. The materials tested were: calcium hydroxide gutta-percha points; chemical pure calcium hydroxide powder mixed with distilled water; and Reogan rapid, a nonsetting calcium hydroxide preparation. The materials were placed into dialysis tubing and transferred into plastic vials containing bidistilled water. Measurements were taken by a digital pH meter after 10, 20, and 30 s; 1, 15, and 30 min; and 1, 2, 3, 24, 48, 72, 96, and 120 h. The calcium hydroxide containing gutta-percha points showed a significantly lower alkalizing potential than Reogan rapid and calcium hydroxide mixed with distilled water (p < 0.05).

Shear bond strength of AH-26 and Epiphany to composite resin and Resilon.

The aim of this study was to evaluate the relative bond strengths of AH-26 and Epiphany sealers to both Resilon and composite resin. Four groups of substrate/bonded sealer combinations were tested: group A, composite resin substrate + Epiphany sealer; group B, composite resin substrate + AH-26 sealer; group C, Resilon substrate + Epiphany sealer; and group D, Resilon substrate + AH-26 sealer. Bond strength was evaluated in shear mode by using a universal testing machine at a crosshead speed of 0.5 mm/min. Statistical analysis (Kruskall-Wallis and Dunn tests) showed that the bond strength of AH-26 to both substrates was significantly greater than the bond strength of Epiphany. Therefore, the monoblock in the root canal might be more effectively achieved by combining Resilon core material with the epoxy resin-based sealer (AH-26) rather than Epiphany sealer.