Sandra Madison

An evaluation of coronal microleakage in endodontically treated teeth. Part III. In vivo study

Root canal therapy was performed on posterior teeth in monkeys using gutta-percha and various sealers for obturation. The access openings were restored with zinc oxide-eugenol. Seventy-two hours later, the temporary restorations were removed and the coronal openings exposed to the oral environment for 1 wk. Following removal, the teeth were placed in dye and cleared to allow visualization of dye penetration. The results showed the presence of dye in teeth in all groups with no significant differences among the groups.

An evaluation of coronal microleakage in endodontically treated teeth. Part I. Time periods

Loss of a temporary restoration or fracturing of a tooth following endodontic treatment exposes the coronal seal of the root canal to the oral cavity. The purpose of this study was to evaluate coronal microleakage over time when the obturation material was exposed to fluids. Seventy extracted human anterior teeth were randomly placed into six groups following chemomechanical preparation and obturation with gutta-percha and sealer. The sealer was allowed to set for 48 h, temporaries were removed, and the teeth were coated with sticky wax, leaving access openings and obturation material exposed to artificial saliva for 3 to 56 days. After exposure to artificial saliva the teeth were immersed in dye to demonstrate microleakage. Specimens were cleared and measurements made to the maximum point of dye penetration. While teeth not exposed to saliva showed no leakage, all experimental teeth exposed to saliva showed leakage ranging from 79 to 85% of the root. No statistically significant differences in leakage existed between the groups exposed to saliva.

An evaluation of coronal microleakage in endodontically treated teeth. Part II. Sealer types.

This study compared coronal microleakage in the root canals of teeth obturated with gutta-percha and either Sealapex, AH26, or Roths sealer. Following obturation the coronal access openings were exposed to artificial saliva for 1 wk and then placed into dye to demonstrate leakage. The specimens were decalcified and cleared and linear measurements were made from the cementoenamel junction to the point of maximum dye penetration. Statistical analysis of the data showed that the AH26 group demonstrated significantly more coronal microleakage than the other groups (p

Endodontic retreatment: evaluation of gutta-percha and sealer removal and canal reinstrumentation.

To examine the appearance of root canal walls after retreatment, 80 extracted teeth were chemomechanically prepared using a stepback flare technique and obturated with gutta-percha and either Roths 801 or AH26 sealers. Four techniques were used to remove gutta-percha and sealer: method 1—heat and files; method 2—heat, files, and Cavi-Endo; method 3—chloroform and files; and method 4—chloroform, files, and Cavi-Endo. The teeth were sectioned longitudinally and the amount of debris remaining was quantitated. The results showed that no technique removed all debris. When AH26 was the sealer, method 4 was significantly less effective. When Roths 801 was the sealer, method 1 was significantly less effective. Teeth obturated using Roths 801 sealer were significantly cleaner after reinstrumentation.

Cervical root resorption following bleaching of endodontically treated teeth

One year following root canal treatment and internal etching and bleaching of anterior teeth in dogs, the animals were sacrificed and the teeth prepared for stereomicroscopic or light microscopic examination. Evidence of cervical root resorption and ankylosis was noted on several teeth. The bleaching factors associated with the teeth exhibiting resorption were heat with 30% hydrogen peroxide. Resorption was not related to walking bleach or to internal etching alone.

Linear and volumetric analysis of apical leakage in teeth prepared for posts

The effect of post preparation on the apical seal of endodontically treated teeth was studied. The canals of extracted human teeth were instrumented and obturated with gutta-percha using the lateral condensation technique. Post spaces were prepared immediately or 48 h after obturation by removing the gutta-percha with either heated endodontic pluggers, chloroform and files, or Peeso reamers. Linear and volumetric measurements of resultant apical dye leakage revealed that no significant differences existed between the gutta-percha removal techniques at either of the two time intervals studied.

Intracanal placement of Ca(OH)2: A comparison of techniques

Ten extracted human maxillary first molars were selected with a variety of root curvatures. The distofacial roots were resected and the mesiofacial canals were instrumented to a size #25 K file. Three techniques were used to introduce Ca(OH)2 paste into the instrumented canals. These techniques were evaluated for their ability to carry the Ca(OH)2 to working length and also to produce a dense fill. The Lentulo spiral was most effective in carrying the paste to working length. The Lentulo spiral also produced the highest quality fill. The Calasept injection system followed by a #25 finger plugger was the second most effective technique. Counterclockwise rotation of a #25 K file was the least effective of the techniques tested.

An in vitro histological comparison of the step-back, sonic, and ultrasonic instrumentation techniques in small, curved root canals

The effectiveness of different methods of root canal instrumentation in small, curved canals was assessed by histological examination. Compared were the step-back hand instrumentation technique, sonic instrumentation with the Endostar 5, and ultrasonic instrumentation with the Cavi-Endo and PZ-KTec prototype systems. Eighty root canals in freshly extracted humanteeth were randomly placed into these four instrumentation groups of 20 teeth each. Five uninstrumented canals served as controls. Following canal preparation and histological processing, coronal, middle, and apical cross-sections were examined for areas of remaining debris and predentin, the percentage of planed canal walls, and percentage of increase in canal area. The results showed significant differences among the four canal preparation methods in all evaluation categories.

Comparison of ethylenediamine tetraacetic acid and sodium hypochlorite on the apical seal of endodontically treated teeth

This study evaluated the effect of a chelating agent on the apical seal of endodontically treated teeth. The root portions of freshly extracted, single-rooted, human teeth were instrumented while irrigating with a 2.5% solution of NaOCl. Step back flaring was done using either NaOCl alone or an aqueous solution of REDTA in combination with NaOCl for irrigation. The teeth were obturated with gutta-percha and Grossmans sealer. Apical leakage was evaluated by measuring the linear penetration of a 1% solution of methylene blue dye. The results showed no significant differences in dye penetration between the groups regardless of the irrigating solution used.

Multiphasic effect of morphine on the release of substance P from rat trigeminal nucleus slices

It is generally accepted that morphine acts presynaptically to inhibit substance P (SP) release from afferent terminals in the trigeminal nucleus. Recent studies, however, provide evidence that opioids produce both inhibitory and excitatory effects on SP release which are concentration- and receptor subtype-dependent. In the present study, we have examined a wide range of morphine concentrations on K(+)-evoked SP release from rat trigeminal nucleus caudalis slices. Immunoreactive SP was measured in perfusates. Morphine produced multiphasic effects on K(+)-evoked SP release without affecting basal release. A very low nanomolar concentration (1 nM) suppressed release, higher nanomolar concentrations (100-300 nM) facilitated release, a low micromolar concentration (3 microM) suppressed release, and a higher micromolar concentration (30 microM) facilitated release. These effects were abolished by opioid receptor blockade with naloxone (30 nM). Thus, morphine produces a complex bi-directional modulation of SP release from TNC which is concentration- and possibly receptor subtype-dependent.