Effect of calcium hydroxide dressing on seal of permanent root filling.

Low apical leakage along root fillings following an application of calcium hydroxide was reported in a few methylene blue dye penetration studies. It has been found recently that methylene blue is decolored by calcium hydroxide, indicating that the short penetration of methylene blue may not be due to a tight seal only. Of the 80 roots of human maxillary central incisors used in this study, 40 roots (group 1) received calcium hydroxide root canal dressing whereas another 40 roots (group 2) did not.

Microleakage along apical root fillings and cemented posts.

Statement Of Problem: Coronal leakage of endodontically treated teeth has been found to result in a high failure rate.

Purpose: This study tested leakage along apical root fillings remaining after post space preparation and cemented posts in root canals.

Material And Methods: A total of 120 human roots were used in the study and divided into six groups, 20 roots for each group.

Effect of sealer thickness on long-term sealing ability: a 2-year follow-up study.

Long-term sealing ability of root-canal sealer is of clinical importance. We compared the performance of five sealers and a dentine bonding agent, at thicknesses of 0.05 mm (thin layer) and 0.

Leakage of AH26 and Ketac-Endo used with injected warm gutta-percha.

Condensing warm gutta-percha (GP) can greatly reduce the distance between the GP and the root canal walls (RCW). Different sealers with different film thicknesses may seal such close fits differently. With the use of a fluid transport model, leakage of AH26 and Ketac-Endo used with injected warm GP to fill root canals was measured.

Developmental and regional expression pattern of a novel NMDA receptor-like subunit (NMDAR-L) in the rodent brain.

A novel NMDA receptor-like (NMDAR-L) cDNA was isolated that contained an open reading frame coding for a predicted polypeptide of 1115 amino acids that shares approximately 27% identity with NMDA receptor subunits. In situ hybridization experiments indicated that NMDAR-L mRNA was expressed in the developing rodent CNS. On postnatal day 1 (P1), NMDAR-L mRNA expression was pronounced in the entorhinal cortex, the subiculum and the thalamus, in layer V of the developing neocortex, in the superior and inferior colliculi, and various regions of the hindbrain, excluding the cerebellum.

Effect of thickness on the sealing ability of some root canal sealers.

A fluid transport model study was used to evaluate the sealing ability of five root canal sealers, AH 26, Sealapex, Ketac Endo, Roth, and Kerr EWT, and a dental bonding agent at thicknesses of 0.05 mm (thin layer) and 0.3 mm (thick layer) with 270 standard human root sections obturated with sealer combined with standard gutta-percha cylinders.

A 1-year follow-up study on leakage of four root canal sealers at different thicknesses.

Determination of leakage using a fluid transport model allows measurement of leakage in a longitudinal manner. Leakage of four sealers at three different thicknesses in 225 bovine root sections, after storage in water for 1 year, was measured again using the same methodology. The change in seal over time for each sealer was observed.

Efficacy of three techniques in cleaning the apical portion of curved root canals.

Various techniques for root canal instrumentation may have different effects in cleaning curved root canals, especially their apical portions. One hundred thirty-five mesiobuccal canals with an average curvature of 25 degrees from human mandibular molars were treated with step-back, crown-down pressureless, or balanced-force techniques with 2% sodium hypochlorite used as an irrigant. The cleaning efficacy of these techniques was evaluated by counting the remaining surface debris under a stereomicroscope with a calibrated eyepiece micrometer.

Leakage of four root canal sealers at different thickness.

Sealers play a key role in sealing the root canal system. Fluid transport under a headspace pressure of 50 kPa (0.5 atm) through four sealers, AH26, Ketac-Endo, Sealapex and Tubli-Seal at a thickness of 0.

Sealing properties of Ketac-Endo glass ionomer cement and AH26 root canal sealers.

Sealing capacity, setting shrinkage and setting time of a recently introduced glass ionomer cement Ketac-Endo were compared with that of a conventional sealer AH26. Sixty half-cylinders, 8 mm long, 4 mm in diameter, made from fresh bovine root dentine, had their smear layer removed before being cemented together while separated by 1-mm spacers. This resulted in a group of 15 cylinders cemented with Ketac-Endo and a similar group with AH26.

Fluid transport and dye penetration along root canal fillings.

Dye penetration along root canal fillings may be hindered by the presence of entrapped air. In this study, the sensitivity of a dye penetration method was compared with that of a fluid transport model. Sixty root sections from human maxillary central incisors were prepared and obturated by a modified technique to ensure a slight amount of leakage, and divided into three equal groups.

Fluid transport and bacterial penetration along root canal fillings.

Convective transport of water from the coronal to the apical end of obturated root canals was determined by the movement of an air bubble in a capillary glass tube connected to the apex of the experimental root section using a headspace pressure of 120 kPa (1.2 atm). Water transport through existing voids in the obturated canals could be measured reproducibly in this way.

Periapical status and prevalence of endodontic treatment in an adult Dutch population.

This study examined the prevalence of endodontic treatment in a group of 184 Dutch adults, and determined the periapical status of all teeth using panoramic radiographs. The results indicate that in this group, 2.3% of the teeth were root-filled, and that 5.

Endodontic leakage studies reconsidered. Part II. Statistical aspects.

The aim of many endodontic studies is to compare two or more treatment methods, techniques or materials, for example, to detect differences in mean leakage scores. As it is not feasible to study large populations, samples are taken. The important question then arises as to how large the sample sizes have to be in order to establish the 'true' (= populations') mean scores.

Endodontic leakage studies reconsidered. Part I. Methodology, application and relevance.

An increasing number of endodontic leakage studies have been published. In the 1990 volumes of Journal of Endodontics and International Endodontic Journal, there was one leakage study to every 4.3 scientific articles.

Quantitative microleakage study on a new retrograde filling technique.

An in vitro endodontic leakage model was used to compare the sealing ability of conventional retrograde amalgam fillings with a new retrograde filling technique by measuring dye leakage quantitatively. The new technique consisted of retrograde preparation of the root canal using the Endocursor, an endodontic handpiece. The canal was then filled with sealer and injection-moulded gutta-percha, using either the Hygenic Ultrafil system or the Unitek Obtura method.

Bactericidal effects of human neutrophils and sera on selected endodontic pathogenic bacteria in an anaerobic environment.

Phagocytosis by normal human neutrophils and the bactericidal activity of normal human pooled serum were measured under anaerobic conditions on six endodontic pathogenic bacterial species from the genera Actinomyces, Bacteroides, Fusobacterium, Peptostreptococcus and Streptococcus. The results revealed that Actinomyces viscosus was not killed either by human neutrophils or by 20 per cent serum; Peptostreptococcus anaerobius was not killed by either 20 per cent or 95 per cent serum; and Bacteroides intermedius was susceptible to both 20 per cent and 95 per cent serum, but was not killed by neutrophils after exposure for 20 minutes. The other species showed intermediate susceptibility patterns.

Capacity of anaerobic bacteria enclosed in a simulated root canal to induce inflammation.

In an effort to simulate the infected dental root canal, bacteria were enclosed in polyethylene tubes that were subcutaneously implanted into rats. Four different bacterial combinations, selected from nine oral species, were tested. The contents of 144 inoculated and implanted 'root canals' were analysed after 2 and 4 weeks of implantation.

Antibody formation to dog pulp tissue altered by a paste containing paraformaldehyde.

Pulpotomy treatment was performed weekly on the teeth of four dogs for 5 weeks. Antibody formation to pulp tissue altered by paraformaldehyde paste within the pulp cavity was measured by enzyme linked immunosorbent assays (ELISA). The results indicated that the reaction between antigen and antibody did occur when pretreatment or post-treatment serum reacted with the antigen of either the pulp tissue incubated with saline or that incubated with paraformaldehyde paste.