Effect of the wicking behavior of multifilament sutures.

The purpose of this study was to compare the wicking propensity of multifilament sutures. Dexon II, Vicryl, and black silk suture (BSS) were dipped in saline or soaked for 48 h, then suspended on a microscope slide. Fluorescein isothiocyanate-dextran (FITC-D) was placed at the suture mid points, and its movement was observed using fluorescence microscopy. The experiment was repeated, replacing the FITC-D with mixture of S. salivarius and saline, incubating the suture specimens in culture medium, and evaluating microbial growth. Dipped sutures showed FITC-D movement in the Dexon II group only. All 48-h soaked sutures demonstrated FITC-D movement with significant (p < 0.005) differences in mean times: BSS 179 +/- 42 s; Vicryl 120 +/- 26 s; and Dexon II 32 +/- 2 s. Dexon II suture demonstrated wicking of S. salivarius, whereas Vicryl and BSS did not (p < 0.05). These results suggest that BSS and Vicryl sutures do not wick as readily as Dexon II does.

Sealing ability of Dyract, Geristore, IRM, and super-EBA as root-end filling materials.

The purpose of this study was to evaluate the apical sealing ability of two compomers (Dyract and Geristore), IRM, and Super-EBA. Forty single canal roots from human teeth were instrumented until a size 40 file extended 1 mm beyond the apex. One millimeter of root apex was removed and a preparation 3-mm deep was prepared. Roots were divided into 4 groups of 10 roots each and filled with IRM, Super-EBA, Dyract, or Geristore. Canals were not obturated to ensure that any leakage was due to the apical filling material alone. Each root was then affixed to a fluid filtration device and subjected to a pressure of 14 cm of H2O, which has been determined to be the normal pulpal tissue pressure. The integrity of the seal was evaluated for 5 min at 1, 7, 30, and 180 days. Data were analyzed at each time point using one-way analysis of variance on ranks. The results of this study suggest that the new compomers Dyract and Geristore are equal or superior to IRM and equivalent to Super-EBA in their ability to reduce apical leakage when used as retrofilling materials.

Evaluation of regional bond strength of resin cement to endodontic surfaces.

The purpose of this study was to test the feasibility of adapting a new microtensile testing technique to measure resin cement bond strengths to the cervical, middle, and apical thirds of root canals. Post spaces were created in extracted human teeth, and the roots were ground flat on one side to expose the canal and permit ideal placement of one of two resin cements (Panavia 21 or C&B Metabond). After 48 h of storage, serial 1-mm-thick cross-sections were cut to create 6-10 specimens per root. The first three specimens were from the cervical third, the next three were from the middle third, and the last three were from the apical third of the root. Each 1 x 1 x 8 mm specimen was pulled to failure in a miniature testing machine. The results indicated that both resin cements produced high bond strengths (12-23 MPa), and that bond strengths to the apical third were significantly higher (p < 0.05) than to the cervical or middle third with either cement. This new method shows promise for evaluating resin bond strengths within root canals.

An inexpensive device for transillumination.

Patients with cracked-tooth syndrome often present with a chief complaint of vague pains while eating that they cannot localize, making the diagnosis difficult. Frequently practitioners are unable to discover the cause of their symptoms, so treatment is delayed, which can result in apical propagation of the crack, leading to unrestorable vertical root fracture. Transillumination is a valuable aid to diagnosis, but suitable diagnostic lights are difficult to obtain, most being cumbersome and expensive. A portable inspection/bore light that serves as an ideal device for transillumination is available for approximately $10.

Effect of light-enhanced bleaching on in vitro surface and intrapulpal temperature rise.

PURPOSE: This study investigated the effect of the presence, absence, and aging of a heat-enhancing compound (colorant) added to bleaching gel on the temperature rise of the gel itself, as well as the temperature rise within the pulp chamber, when a tooth was exposed to a variety of light-curing units in vitro. MATERIALS AND METHODS: An extracted human upper central incisor was fitted with thermocouples placed in the pulp chamber as well as on the facial tooth surface. A temperature-controlled simulated intrapulpal fluid flow was provided to the tooth, and bleaching agent (Opalesence XTRA, Ultradent) containing heat-enhancing colorant, aged colorant, or no colorant was applied to the facial surface. The tooth and light-curing unit were placed in a thermostatically controlled oven at 37 degrees C, and real-time gel and intrapulpal temperature values were recorded digitally. Light-curing units used were a plasma arc light (PAC) (PowerPac, ADT), a conventional quartz tungsten halogen source (QTH) (Optilux 501, Demetron/Kerr), the QTH light used in high-power (bleaching) mode, and an argon ion laser (AccuCure 3000, LaserMed). An exposure scenario simulating light-enhanced bleaching of 10 upper teeth was developed. Temperature rise over the pre-exposure, baseline value associated with the last light exposure in the bleaching sequence was calculated for each curing and bleaching combination. Five replications for each test condition were made. Temperature rise values were compared using analysis of variance (ANOVA) at a preset alpha of 0.05. RESULTS: When fresh colorant-containing bleach was used, the PAC light increased bleach temperature 39.3 degrees C above baseline. With no added colorant, temperature rise was 37.1 degrees C. The QTH light in bleach mode resulted in gel temperature 24.8 degrees C above baseline, whereas the temperature increase was only 11.5 degrees C when no colorant was used. Conventional QTH light use increased fresh bleach temperature by 17.7 degrees C, whereas an increase of only 11.1 degrees C was measured without colorant. The argon ion laser produced equivalent temperature rise regardless of the presence or freshness of the colorant, approximately 9.4 degrees C. Intrapulpal temperatures were all significantly lower than those recorded in the bleaching gel and ranged from 5 degrees to 8 degrees C. As a rule, the presence of fresh heat-enhancing colorant in the bleaching gel resulted in a significant intrapulpal temperature increase (approximately 1 degrees C) over that reached using other lights. The PAC and the QTH light used in bleach mode induced greater intrapulpal temperature rise than the laser. CLINICAL SIGNIFICANCE: Freshness of bleaching agent incorporating light-activated, heat-enhancing colorant influences temperature rise of bleaching gel and also may increase intrapulpal temperature values. Use of intense lights does elevate bleach temperature and also results in increased intrapulpal temperature that may further impact on patient sensitivity and pulpal health resulting from this treatment.

Antimicrobial activity of several calcium hydroxide preparations in root canal dentin.

The purpose of this study was to evaluate the antimicrobial activity of several calcium hydroxide (Ca(OH)2) preparations in root canal dentin infected with Enterococcus faecalis. Roots of extracted bovine incisors were prepared to standardized cylindrical test specimens of 5 mm in height; the smear layer was removed, and the specimens were incubated for 24 h at 37 degrees C in bacteriological culture medium that contained 7.0 x 10(4) colony forming units per milliliter of E. faecalis. The specimens were mounted in individual 4-mm diameter culture wells, and the test material was applied to fill the canal lumen. There were five treatment groups: group 1, a thick mixture of Ca(OH)2 USP (1.0 g/ml H2O); group 2, a thin mixture of Ca(OH)2 USP (0.1 g/ml H2O); group 3, Pulpdent TempCanal paste; group 4, sterile H2O (positive control); and group 5, 25 dentin specimens in sterile, uninoculated brain-heart infusion broth that were included as negative controls. Quantitative microbiological analysis of dentin at various depths was completed after 24 h. All groups showed a significant (p < 0.001) decrease in numbers of E. faecalis in all depths of dentin compared with the control. Groups 2 and 3 demonstrated significantly greater antimicrobial activity (73%-86% reduction) at all depths of dentin tested compared with group 1 (13%-26%) (p < 0.05). These results suggest that Ca(OH)2 can decrease the numbers of E. faecalis at all depths of dentinal tubules within 24 h and that thin preparations of Ca(OH)2 may be more effective in the elimination of E. faecalis from dentinal tubules than thick preparations.

Endodontics and dental readiness.

The primary mission of the Dental Corps--maintaining the dental health of our soldiers at an optimum level to ensure their readiness to deploy and fight--is more important than ever in today's downsized, high-operational-tempo Army. A review of the literature indicates that 20 to 25% of all soldiers will report on dental sick call during a 1-year deployment, and approximately half will require endodontic intervention. This could cost a division more than 18,000 man-days of combat effectiveness in a theater of battle, an unacceptable loss. Approximately three-fourths of these sick call visits could be prevented if selected conditions were identified and treated before deployment. Endodontic conditions, which result in the majority of dental sick call complaints, should be given priority for treatment in garrison, and the identified soldier should be placed in dental fitness class 3 until the tooth is definitively treated.

Root canal morphology of human maxillary and mandibular third molars.

The anatomy of third molars has been described as unpredictable. However restorative, prosthetic, and orthodontic considerations often require endodontic treatment of third molars in order for them to be retained as functional components of the dental arch. The purpose of this study was to investigate and characterize the anatomy of maxillary and mandibular third molars. One hundred fifty maxillary and 150 mandibular extracted third molars were vacuum-injected with dye, decalcified, and made transparent. The anatomy of the root canal system was then recorded. Seventeen percent of mandibular molars had one root (40% of which contained two canals), 77% had two roots, 5% had three roots, and 1% had four roots. Teeth with two roots exhibited highly variable canal morphology, containing from one to six canals, including 2.2% that were "C-shaped." Fifteen percent of maxillary molars had one root, 32% had two roots, 45% had three roots, and 7% had four roots. Teeth with one root demonstrated the most unusual morphology, with the number of canals varying from one to six. An in vivo study of the canal morphology of treated third molars is suggested to provide the practitioner with an understanding of the clinical implications of third molar root anatomy.

Determination of periodontal ligament cell viability in long shelf-life milk.

The purpose of this study was to determine the ability of long shelf-life milk to serve as a temporary storage medium for the maintenance of periodontal ligament (PDL) cell viability on avulsed teeth. PDL cells were plated onto 24-well culture plates and allowed to attach for 24 h. Minimal Essential Medium was replaced with regular pasteurized milk (refrigerated milk), long shelf-life milk (Parmalat), or Save-A-Tooth. Tap water served as the negative control, and Minimal Essential Medium served as the positive control. The tissue culture plates were incubated at 37 degrees C for 1, 2, 4, or 8 h. Cell viability was determined using a cell proliferation assay (CellTiter 96 AQ Assay) and absorbance read at 490 nm. ANOVA indicated that all media performed significantly better than tap water at all time periods. At 8 h, PDL cell viability in regular pasteurized milk and long shelf-life milk were significantly greater than in Save-A-Tooth (p < or = 0.001). There was no significant difference between regular pasteurized milk and long shelf-life milk at any time period. These results suggest that long shelf-life milk, which has the advantage of not requiring refrigeration, is as effective a storage medium for avulsed teeth as regular pasteurized milk and more effective than Save-A-Tooth.

Increased density of gutta-percha using a controlled heat instrument with lateral condensation.

The purpose of this study was to compare quantitatively the density of standard cold lateral gutta-percha condensation and warm lateral gutta-percha condensation using the System B heating instrument in a low-heat warm lateral condensation technique in an artificial root canal in vitro. Thirty-degree simulated root canals in 30 transparent acrylic blocks were instrumented using Gates-Glidden burs and Quantec (NT Company, Chattanooga, TN) rotary files. The canals were then obturated with gutta-percha using standard cold lateral condensation without sealer. Warm lateral condensation without sealer using the System B instrument at 101 degrees C was then performed on the same 30 canals. A second treatment of warm lateral condensation was then applied to these same canals. The blocks were weighed after the initial canal preparation and after each obturation treatment. Results showed warm lateral condensation of gutta-percha using the System B resulted in a significant increase in density by weight when compared with standard cold lateral condensation. A 23.97% increase in weight was realized after the first heat application, compared with standard lateral condensation. A second heat application produced an additional 2.59% increase in weight over that produced by the first heat application. Data were analyzed using a t test for repeated measures. Both increases were statistically significant (p < 0.001). Warm lateral condensation using the System B instrument results in denser gutta-percha fills by weight when compared with standard cold lateral condensation.

Use of the microscope in endodontics: a report based on a questionnaire.

A survey regarding operating microscope (OM) usage and training was mailed to 3356 active members of the American Association of Endodontists (AAE) in the United States. Data from 2061 questionnaires indicate that 52% of the endodontists surveyed have access to and use the OM in their practice. The frequency of use as a function of years since completing endodontic training was as follows: < 5 yr, 71%; 6 to 10 yr, 51%; and > 10 yr, 44%. The OM was used most often for retrieval of separated instruments, root-end preparations, and root-end fillings. Of the respondents who use the OM, 36% report they do not use it as often as anticipated. The most common reasons reported were positional difficulties, inconvenience, and increased treatment time. The information collected from the survey reveals that the more training the operator has on the microscope, the more likely he or she is to use it for all procedures.

Effect of bisphosphonates and gallium on dentin resorption in vitro.

Replacement resorption may follow the replantation of an avulsed tooth. Currently there is no effective treatment for replacement resorption. The purpose of this study was to investigate the effect of bisphosphonates and gallium nitrate, which have been shown to reduce bone resorption, on cells which resorb dentin. Osteoclast-like cells were obtained by culturing cells from prenatal chick tibeas. These cells were seeded onto slices of human dentin which had been soaked in either saline (control), or solutions of 10(-5) M 1-hydroxyethylidene-1, 1-bisphosphonic acid (EHBP), 10(-6) M dichloromethylene bisphosphonic acid (Cl2MBP), or 10(-6) M gallium nitrate. Resorption was measured by counting the number of resorptive lacunae produced by the cells. Results indicated that the experimental groups did not differ significantly from each other, but each exhibited significantly reduced resorption compared with saline controls (p < 0.01). These results suggested that the experimental treatment reduced dentinal resorption by the osteoclast-like cells, and that these agents might be useful to prevent or at least postpone replacement resorption in avulsed teeth.

Improved density of gutta-percha after warm lateral condensation.

Simulated straight root canals in 30 transparent acrylic blocks were instrumented and obturated with gutta-percha without sealer using standard lateral condensation (group A). The "zap and tap" method of warm lateral condensation was then used on the same 30 canals (group B). A second treatment of warm lateral condensation was then applied to these same canals (group C). The acrylic blocks were weighed after initial canal preparation and after each subsequent obturation. A 14.63% increase in weight of the gutta-percha occurred in group B compared with group A, and a 2.43% increase in weight occurred in group C compared with group B. Both differences were statistically significant (p < 0.001).

Obturation of a C-shaped canal using an improved method of warm lateral condensation.

Pilot studies conducted by the authors seem to indicate that obturation of a root canal system by the lateral condensation of gutta-percha using an electrically heated spreader results in a more homogeneous mass of gutta-percha than standard lateral condensation. This article describes an improved variation which prevents inadvertent dislodgement of the mass of gutta-percha during the obturation. The authors refer to this technique as "zap and tap" and a case report describes its use to obturate a C-shaped canal system of a mandibular second molar.