Effect of Essential Oils on the Setting Time of Kerr Pulp Canal Sealer
Kaplowitz
New Electronic Canal Measuring Device Based on the Ratio Method
Kobayashi and Suda
Endodontic Retreatment of Thermafil Versus Laterally Condensed Gutta-percha
Wilcox and Juhlin
Dentin Permeability to Bacterial Proteins In Vitro
Pissiotis and Spångberg
Apical Seal of Teeth Obturated by the Laterally Condensed Gutta-percha, the Thermafil Plastic and Thermafil Metal Obturator Techniques after Post Space Preparation
Ricci and Kessler
Alteration of Biological Properties of Bacterial Lipopolysaccharide by Calcium Hydroxide Treatment
Safavi and Nichols
Dental Pain Evoked by Hydrostatic Pressures Applied to Exposed Dentin in Man: A Test of the Hydrodynamic Theory of Dentin Sensitivity
Ahlquist, Franzén, Coffey, and Pashley
Effect of Essential Oils on the Setting Time of Kerr Pulp Canal Sealer
Gary J. Kaplowitz, DDS, MA, MEd
Setting times were determined for Kerr pulp canal sealer and the powder component of Kerr pulp canal sealer mixed with different liquid essential oils. The mean setting time of Kerr pulp canal sealer was 16.5 min. The mean setting times for the powder component of Kerr pulp canal sealer mixed with pure eugenol or for the standard liquid component of Kerr pulp canal sealer with rectified turpentine oil were 16.5 and 18.0 min, respectively. There was no significant difference in setting times among the three groups. The addition of rectified turpentine oil to the liquid component of Kerr pulp canal sealer did not have a significant effect on setting time.
New Electronic Canal Measuring Device Based on the Ratio Method
Chihiro Kobayashi, DDS, PhD, and Hideaki Suda, DDS, PhD
The most striking disadvantage of most apex locators is that if there are electrolytes in the canal the meter shows a reading which is too short or sometimes the measurement itself becomes impossible. To overcome this drawback, a new concept for electrically measuring the root canal length has been developed. The device simultaneously measures two impedances of the canal using current sources with two different frequencies. Then the ratio between the two electric potentials proportional to each impedance is calculated. The quotient is shown on the device's meter and represents the position of a file tip in the canal. The present study found that the quotient was only negligibly influenced by the electrolyte present in the canal and decreased considerably as the file tip approached the apical foramen.
Endodontic Retreatment of Thermafil Versus Laterally Condensed Gutta-percha
Lisa R. Wilcox, DDS, MS, and Jon J. Juhlin, DDS, MS
The Thermafil device is becoming a popular obturating material. Because endodontic failures inevitably occur with all techniques, questions of retreatment of Thermafil-obturated teeth will also arise. The purpose of this study was to compare retreatment of Termafil and laterally condensed gutta-percha. Thirty-five mandibular incisors were prepared with a stepback flare technique and divided into two groups. One group (n = 20) was obturated using Thermafil, the other group (n = 15) was obturated with laterally condensed gutta-percha. The teeth were stored in a humidor for 3 months to allow sealer to set. Retreatment of both groups was accomplished using a combination of heat and chloroform solvent. The time for retreatment was recorded. The teeth were split longitudinally and the amount of gutta-percha remaining in the root canal was measured and analyzed statistically. The results showed that in the coronal one-third of the canal, use of the Termafil device resulted in significantly more remaining gutta-percha than use of laterally condensed gutta-percha. However, in the apical and middle one-third of the canal the difference in remaining gutta-percha between Thermafil and laterally condensed gutta-percha was not signficant. The metal carrier was easily removed and the mean time for retreatment was 6.3 min for Thermafil compared with 5.7 min in the lateral condensation group.
Dentin Permeability to Bacterial Proteins In Vitro
Eleftheria Pissiotis, DDS, MDSc, and Larz S.W. Spångberg, DDS, PhD
Passage of bacterial components through dentin is a subject of recent research with in vitro as well as with in vivo models. Diffusive transport of Porphyromonas gingivalis ATCC 33277 proteins has been demonstrated by the authors with an in vitro setup closely simulating the pulp chamber. The purpose of this investigation was to study the filtration of these proteins through dentin, measure possible concentration changes resulting from the filtering, and elaborate on the physical aspects of the binding process. The hydraulic conductance (Lp) of 10 dentin spcimens was determined in three experiments using standard procedures: initially with phosphate-buffered saline, subsequently with a P. gingivalis ATCC 33277 suspension (200 µg/ml of protein), and finally with phosphate-buffered saline. The results showed significant, nonpermanent, alterations of the Lps of the dentin disks, and variable retention of the bacterial proteins among samples. A positive correlation between the bacterial protein retention and reduction of Lps was also demonstrated. The reduction of the Lps of the dentin samples was attributed to microstructural changes of the dentin, while the bacterial protein retention was considered to take place either on the surface of the disk or intratubularly. The intratubular interactions in the present experiment seemed to have a mechanical rather than a chemical basis.
Apical Seal of Teeth Obturated by the Laterally Condensed Gutta-percha, the Termafil Plastic and Termafil Metal Obturator Techniques after Post Space Preparation
Ernest R. Ricci, BS, DDS, and Joel R. Kessler, BA, MS, DDS
This in vitro study was conducted to determine the effect of post space preparation on teeth obturated with the Thermafil technique, both plastic and metal carriers, and the lateral condensation method. Three groups of 30 teeth each were obturated using the lateral condensation technique and the Thermafil plastic and metal techniques. Post space preparations were accomplished on the obturated groups. All specimens were submerged in India ink under a vacuum for 15 min and then soaked for an additional hour at atmospheric pressure. The teeth were decalcified and cleared to permit visualization and measurement of the extent of dye penetration. There was approximately three times more dye penetration in group 2 (plastic carrier) when compared with group 1 (lateral condensation) and group 3 (metal carrier). This was statistically significant at the 99% confidence level.
Alteration of Biological Properties of Bacterial Lipopolysaccharide by Calcium Hydroxide Treatment
Kamran E. Safavi, DMD, MEd, and Frank C. Nichols, DDS, PhD
Bacterial lipopolysaccharide (LPS) plays a major role in the development of periapical bone resorption. Although the chemical properties of LPS are altered by treatment with an alkali such as calcium hydroxide, the effects of calcium hydroxide on the biological properties of LPS are not known. The purpose of this study was to investigate whether treatment of LPS with calcium hydroxide alters its biological action as measured by human monocyte secretion of prostaglandin E2. Monocyte cell cultures were stimulated with LPS or calcium hydroxide-treated LPS and culture supernatants were analyzed for prostaglandin E2 content using gas chromatography-mass spectrometry. Prostaglandin E2 was identified in supernatants of LPS-stimulated monocytes but not in those stimulated with calcium hydroxide-treated LPS. It was concluded that the treatment with calcium hydroxide may alter biological properties of bacterial LPS.
Dental Pain Evoked by Hydrostatic Pressures Applied to Exposed Dentin in Man: A Test of the Hydrodynamic Theory of Dentin Sensitivity
ichael Ahlquist, DDS, PhD, Ove Franzén, PhD, James Coffey, DDS, MS, and David Pashley, DMD, PhD
The hydrodynamic theory of dentin sensitivity holds that pain is evoked by stimuli producing minute shifts in tubule fluid. In human volunteers hydrostatic pressures were applied to prepared dentinal cavities. The subjects reported the magnitude and quality of their sensations of pain by means of an intermodal matching technique in combination with verbal descriptors.
No pain could be elicited when the smear layer was present. After removal of this layer, pressure stimuli of either direction evoked sharp pain. Rapid changes in pressure induced higher pain intensities than slow changes, indicating that the dental A-delta system is dynamic and gradient dependent.
These results provide support for the hydrodynamic theory of dentin sensitivity and also lend credence to the notion that the movement of fluid across dentin induces a selective activation of the A-delta nerves in healthy pulps which is highly correlated with a sensation of sharp and/or shooting pain.