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Week of February 2, 2001

Title: Comparison of Laterally Condensed and Low Temperature Thermoplasticized Gutta-Percha Root Fillings.

Author: Al-Dewani, N. et al.

Journal: JOE 26(12):733. December 2000.

Prepared by: G. Altenburg

Purpose: To evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta-percha or low-temperature thermoplasticized gutta-percha (Ultrafil).

M&M:

• One hundred freshly extracted human, mature single-rooted teeth were divided into four identical groups of 25 teeth on the basis of root canal shape.
• The root canals of two groups were prepared in such a way to produce a relatively parallel shape with little or no flare toward the coronal orifice.
• The root canals of the other two groups were prepared in such a way as to produce a canal shape that was deliberately more flared to ensure that they were wider at the orifice than at the end point of the preparation.
• All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer.
• The canals of one flared group and one parallel group were obturated using cold lateral condensation, and the canals of the other two groups were obturated using low-temperature thermoplasticized gutta-percha.
• The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a 4-point scale.

Results:

• Canals filled with thermoplasticized gutta-percha had significantly less apical dye penetration than those obturated by lateral condensation.
• Lateral condensation achieved significantly better scores for radiographic quality than thermoplasticized gutta-percha from both the buccolingual and mesiodistal views.
• Low-temperature thermoplasticized gutta-percha root fillings were associated with significantly more apical extrusion of sealer and gutta-percha.

Conclusions: Under laboratory conditions the low-temperature thermoplasticized gutta-percha had better sealability but poorer radiographic quality than lateral condensation.

Title: Shaping ability of three ProFile rotary instrumentation techniques in simulated resin root canals

Author: Kum, Ki-Yon et al

Journal: JOE 26: 12; pg. 719, Dec., 2000

Reviewer: M.Oller

Purpose: To compare the shaping effect of the ProFile .04, the ProFile .04 in combination with the .06 taper, and ProFile GT in combination with ProFile .04 taper in simulated resin canals.  Prevalence of canal aberrations, change in working length, and instrumentation time were recorded.

Materials and Methods: 48 resin simulated root canal blocks (Endoblock, Maillefer) were divided into 4 groups with 12 canals each. All canals had a mean curvature of 40 degrees.

-All rotary prepared groups were instrumented using a 1:16 high-torque handpiece powered by an electric motor at a speed of 280rpm for the ProFile .04 and .06 taper and 150 for the ProFile GT files. The final apical preparation was set for #35 for all canals. Irrigation and patency files were used. Groups:

1. ProFile .04 taper: A #25 /.04 file was placed 1/2 -2/3 down the canals followed by a #30/.04 to the same length. A #20 was then placed 2/3 down the canals and followed by a step-back of #15 to the working length (W.L.) to a size #35
2. ProFile .04 and .06 taper: For coronal shaping, a serial use of orifice shaper #3, #2, Profile #25/.06 and Profile #20/.06 were used to 1/2 of the canals. Instrumentation then proceeded in a similar manner to the ProFile .04 taper group.
3. ProFile GT w/ .04 taper: For coronal flaring, GT’s #20/.12, #20/.10, #20/.08, and #20/.06 were used sequentially from 1/2 to 2/3’s of the estimated W.L. Instrumentation proceeded similar to that of Group 1.
4. Control Group (Step back Method): Radicular access was achieved by Gates-Glidden drill #2 to #4. Apical preparation was then done by using stainless steel .02 taper K –files (Flexofile) to the W.L. -  #15 - #35 files were precurved and placed to the W.L. with a combination of filing and reciprocal reaming (watch-winding). A step back filings were done to 1mm short of the previous file to a size #60.

- The preparation time and change in W.L. was noted. To compare the enlarging efficiency, pre- and postcanal scanned images were made using a Corel Photopaint program and then the amount of coronal substance the instruments removed was calculated two-dimensionally on digitalized images with the Brain C software.

Results:

• A significantly greater instrumentation time, loss of W.L., elbows and zips created was noted with the hand file group as compared to the 3 rotary groups (7/36 of the canals prepared by rotary had zips/elbows)
• There was no significant differences between the three rotary groups in terms of time, loss of W.L. and elbows created.
• The amount of coronal tooth structure removed in the ProFile .04 taper was significantly smaller when compared w/ the other instrument groups.

Conclusions: The combined use of the ProFile .06 taper and orifice shapers or ProFile GT files improved canals shape for a suitable obturation and did not increase the incidence of canal aberrations in simulated canals (The additional file changes did not increase the instrumentation time).

- The use of larger and higher taper file in the apical part of severely curved root canals should be considered carefully because they tend to introduce aberrations in the canal shape.

Comments: Not truly an original study as similar studies have been done before (Bryant et al). The results were not unexpected, as there was no coronal shaping in the ProFile .04 group. Authors note that the images are only 2 dimension and the resin blocks may not adequately simulate dentin during instrumentation.

Title: Correlation between remaining length of root canal fillings after immediate post space preparation and coronal leakage

Author: Metzeger et al.

Journal: JOE 26(12)724-728, Dec 2000.

Prepared by: Tom Goebel

Purpose: To study the seal provided by root canal fillings after post space preparation using a pressure-driven radioactive tracer assay.

M & M:

• 105 extracted single-rooted teeth were sectioned coronally to length of 14 mm
• teeth were instrumented to #40 master apical file @ 0.5 mm from apical foramen
• patency was confirmed with #30 file
• prior to obturation, Gates Glidden #4 was used to prepare root canal to length of 3, 5, 7 or 9 mm short of working length (WL) -depending on group tooth was from, to facilitate Gutta perch  removal via hot plugger post-obturation
• teeth were obturated with GP & Roth’s sealer via lateral condensation
• post space was made immediately following obturation to predetermined depth
• teeth were stored for 7 days @ 37° C in 100% humidity to allow sealer to set
• coronal leakage of root filling was studied by:

1. using pressure-driven radioactive tracer by using 3H-thymidine with 130 mm Hg pressure
2. no pressure applied to radioactive tracer (normal atmospheric pressure)

• leakage of tracer solution through the obturated canals was monitored daily via scintillation

Results:

• non-obturated teeth had maximal leakage – 41,000 cpm
• passive system (no leakage for 9 days, leakage started on day 10):
  scores by day 14 were:               day 28

3 mm filling = 95 cpm 552

5 mm filling = 85 cpm 302

7 mm filling = 39 cpm 303

9 mm filling = 28 cpm 188

                  14 mm (intact) = 37 206

• pressure driven system (no leakage for 4 days) :
  leakage by day 14:                       day 28

3 mm filling = 1,082 cpm 3,766

5 mm filling = 1,016 cpm 2,571

7 mm filling = 249 cpm 1,190

9 mm filling = 117 cpm 669

14 mm (intact) = 227 602

• the kinetics of leakage were statistically different between the passive system & the pressure-driven system
• difference between root end fillings of 3 & 5 mm were not statistically different
• differences between 3, 5 mm & 7, 11, 14 mm (intact) groups were statistically different

Conclusion:

• root canal fillings of 3, 5, 7 mm have an inferior seal, compared with an intact filling
• sealing is proportional to the length of the remaining filling
• the passive system is unable to detect these differences, despite the 28 day time frame

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Week of February 9, 2001

Title: A description of an alternative method of lateral condensation and a comparison of the ability to obturate canals using mechanical or traditional lateral condensation.

Author: Gound T, et al.

Journal: JOE 26(12): 756, December 2000.

Reviewed by: Barry Hoch

Purpose: To describe the mechanical lateral condensation (MLC) technique and to compare the weight of
gutta-percha resulting when the same number, size, and type of gutta-percha cones are compacted into a
simulated canal using the MLC or traditional lateral condensation (LC).

Materials and Methods:

• 40 clear resin blocks (20 straight and 20 with a 30⁰ curvature) with simulated 16 mm canals were enlarged to a size 40 master apical file and flared to size 80 using a step-back technique.
• 2 investigators obturated the canals either using the MLC or LC technique, with no sealer.
• LC technique – a 40 master cone was fit to length and then a medium-fine Ni-Ti finger spreader was advanced to within 1mm of the working length, kept with apical pressure for 1 minute, and then removed and a fine-fine accessory cone subsequently place. The process was repeated 3 times.
• MLC technique – a similar technique as LC, but a Ni-Ti finger spreader is placed in a reciprocating handpiece and activated for 5 seconds once at 1mm from the working length.
• Blocks were sectioned and the gutta-percha mass was weighed.

Results:

• The obturations using the MLC technique were significantly heavier on average than those fills with LC.
• There was no significant difference between the weight of fills in straight or curved canals.

Discussion:

• Under the conditions of the present study MLC was found to be superior in its ability to produce a heavier fill, regardless of whether the canal is straight or curved or whether the operator produces heavier or lighter fills.
• This article does not discuss why the criteria for a heavier fill would correlate to a better fill, and if heavier can translate into increased success.

Title: Bradykinin Levels in Dental Pulp by Microdialysis

Author: Lepinski, AM. et al

Journal: Journal of Endodontics, 26(12): 744-747, December 2000

Prepared by: Andrew W. Chan, DDS

Purpose: To examine extracellular levels of bradykinin in human dental pulp.

Materials & Methods:

                 - CMA/20 microdialysis probe was used in this study.

                 - Bradykinin was collected using both radiolabelled bradykinin and standardized solutions of bradykinin.

                 - Flow rates were determined for optimal collection of bradykinin from a known concentration of                      bradykinin standard.

                 - A modified Locke-Ringer’s buffer was perfused through the microdialysis probes.

                 - Patients were selected from two categories: those with a diagnosis of normal pulp or those with a                      diagnosis of irreversible pulpitis.

                 - A rubber dam was placed and a standard endodontic access preparation was made in the tooth, stopping                      short of the pulp chamber. The pulp was entered by creating a small opening and the microdialysis probe                      was placed through this opening into the pulp so that the entire 4mm length was surrounded by pulpal                      tissue.

                - The microdialysis probes were perfused with a sterile modified Locke-Ringer’s buffer at a rate of 5ul/min.                      One hour was allowed for collection of pulpal perfusates.

                - Radioimmunoassay was used to determined levels of immunoreactive bradykinin (iBK) in the collected                      samples.

Results:

              - Levels of immunoreactive bradykinin collected by microdialysis are shown with a higher level in the                    irreversibly inflamed pulp versus the normal pulp.

              - Levels of iBK in the irreversibly inflamed pulp were 13 times greater than levels found in the normal pulp. A                   statistically significant difference in the level of iBK was found between the two groups.

Discussion: Extracellular levels of bradykinin are significantly elevated during irreversible pulpitis. The mean extracellular levels of bradykinin are higher in those patients who have reported pain in the past, compared with the patients who were having pain at the time of bradykinin collection.

This study demonstrated that pulpal levels of iBK are significantly elevated in teeth with a diagnosis of irreversible pulpitis, compared with controls.

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Week of February 16, 2001

Title: Bacterial leakage in coronally unsealed root canals obturated with 3 different techniques

Author: Jose F. Siqueira et al.

Journal: Oral Surgery,Oral Medicine, and Oral Pathology Nov. 2000 pp. 647-650

Prepared by: Greg Dearing, D.M.D.

Purpose: To investigate the coronal leakage of saliva into root canals obturated with 3 different methods:

• continuous wave of condensation technique (system B) w/ backfill (Warm vertical/lateral)
• thermafil technique
•   lateral condensation

Materials and Methods:

• 70 intact, caries free, mand. incisors w/ straight roots and single canals were used.
• Teeth were instrumented and obturated 1 mm from the radiographic apex to a size #35
• 4% NaOCL irrigation was used as well as 17% EDTA
• 20 teeth in each category X 3 categories for obturation =60 teeth
• The remaining 10 teeth were used as +/- controls. 5 = Lateral condensation w/o sealer and another 5 with intact crowns served as the negative control
• In all experimental and control groups, no coronal sealing was done
• Grossman’s sealer was used in all 3 techniques
• For standardization, the filling material was removed until the length of 10 mm of filling remained in the root canal. X-rays were taken to eval. quality of fill.
• The apparatuses used to evaluate saliva leakage were glass assay tubes with rubber stoppers in which insulin syringes with rubber tubes, attached to the teeth, were sealed within the assay tubes with cyanoacrylate
• The testing apparatus was sterilized w/ ethylene oxide gas
• The glass assay tubes were then filled w/ sterile trypticase-soy broth so that 2mm of the root apex was immersed in the broth
• The reservoir was next filled with human saliva mixed w/ TSB
• The whole apparatus was incubated @ 37^o and checked for turbidity for 60 days

Results:

Regardless of the technique used, a significant # of specimens were contaminated after 30 and 60 days. No significant differences were noted among the techniques

Conclusions:

Results indicate that none of the techniques tested could predictably produce a coronal bacteria-tight seal of the root canal after direct saliva challenge

Title:  Comparison of methods measuring root and mucogingival sensitivity

Author:  Walline, BW

Journal: OOO 2000; 90:641-6

Prepared by:  Nima Dayani, D.M.D.

Objective: The aim of this study was to compare the variability of measurements of roots and mucogingival sensitivity over a 24-hour period.   Three commonly used stimuli for root and mucosal sensitivity testing (electricity, pressure and cold) were examined.

Materials and Methods:

Potential subjects were recruited and then screened for at least 1 tooth with > = 2 mm recession and a painful reaction to ethyl chloride-soaked pellet placed on the exposed root surface. Sixteen individuals were tested for pain thresholds with calibrated electrical stimulation of the root and adjacent mucosa, pressure on mucosa and cold on the root at base line, and after 4, 8 and 24 hours.

Subjects were excluded if they had extensive restorations, active caries, orthodontic treatment, or periodontal pathosis.

The sequence of test was varied using Latin square randomization. Electric on both the test root and adjacent mucogingival junction area were performed by using an electric pulp tester (Analytic)

Cold testing was performed by using a prototype thermocoupler cold testing device. The temperature was slowly decreased in 2.5°C form 25°C to 0°C. The probe was placed for 5 sec intervals or until pain was felt. Pts were instructed to raise their hand if they perceived cold sensation of mild or moderate pain as compare with no pain. These thresholds were recorded. Pts also marked the pain response on a 10cm VAS, when they requested testing to be discontinued.

Pressure testing occurred by applying sequentially increasing pressure in 10gm increments to the mucogingival junction of the test tooth. Subjects differentiated between pressure (no pain,) mild or moderate pain. They also marked on a VAS chart different gram increments.

Results/Discussion:

Electric stimulation of the root produced the least consistent response across time within subjects. Sensation to electric stimulation of the mucosal pain and pain thresholds to pressure stimulation of mucosa were more consistent across 24-hour test period. Pain responses to calibrated cold stimulation were the most consistent across time.

The results reported that intra-subject pain response variability was highest with electric stimulation of the roots and least variable with cold stimulation of the roots, when the intensity of verbal description of "mild pain" and "moderate pain" were used to determine thresholds. However, VAS measurement of cold stimulation was more variable within subjects.

The author concluded that, first, electric stimulation of the exposed dentin may not be sensitive enough to detect changes because of the high intra-subject variability. Second, tests with intermediate variability (electric and pressure on mucosa) would benefit form a run-in/washout period before clinical trials to establish sensitivity levels and to eliminate erratic or inconsistent responders. Finally cold stimulation with known and clinically relevant temperatures may provide the most sensitive measure of therapy effect.

Title: The Effect of Ethylenediamine-tertaacetic acid on Candida albicans

Author:  Sen, Bilge Hakan

Journal: OOO Vo. 90, No. 5, Nov. 2000

Reviewed by: Kimberly Pham, D.M.D.

Purpose:  The purpose of this study was to evaluate the antifungal effect of EDTA on Candida albicans, comparing with that of various disinfectants and common antifungal agents.

Materials & Methods:
      Organisms:   Clinical Candida strains OC-170 from the oral cavity; RC-189 from root canal; and C.albicans ATCC 10239 were used.
         Test solutions:

• NaOCl 5% & 2.5%
• 17% EDTA
• Klorhex (CHX 0.2%)
• Cetrexidin ( CHX 0.2%, cetrimide 0.2%)
• Sacrolin (CHX 1.5%, cetrimide 15%)
• Heksoral (Hexidine 1%)
• Hekzoton (Hexidine 1.0%)
• Zefiran (Benzakonium chloride 1.0%)
• Proviod (polyvinyl-pyrrolidone iodine 10%)
• Biokadin (providone-iodine 10%)
• Mikostatin (nystatin 0.5 mg/ml)
• Ketoral (ketokonazole 0.5 mg/ml)
  
  Susceptibility testing procedure:
  
  C. albicans suspensions were inoculated in Sabouraud’s dextrose agar in petri dishes. Paper disks containing antimicrobial solutions were placed on plates. Plates were incubated at 37° C for 48 hs. Zones of inhibition were measured across 2 diameters perpendicular to each other. The tests were repeated in duplicate. The means were calculated.

Results & Discussions:

1. EDTA demonstrated the most effective antifungal activity. Routine antifungal agents, nystatin and ketoconazole, and concentrated solution of CHX (Savrolin) had the next most effective activity. Antifungal properties of 5% and 2.5% NaOCl solutions followed these groups, respectively.
2. The antibacterial properties of EDTA are limited when compared with other endodontic irrigating solutions. However, by chelating calcium ions, EDTA can reduce the adherence capacity of C. albicans to various extracellular matrix proteins in a dose dependent manner. EDTA also reduces the growth of C. albicans by removing calcium from the cell walls and causing collapes in the cell wall and by inhibiting enzyme reaction.
3. The oral cavity strain (OC-170) showed more resistance to disinfecting solutions. Environment changes such as pH, temperature, and nutritional source may cause phenotypic switching of C albicans and in turn alter the sensitivity of the organisms to common antifungal agents, which has dramatic effect on cell wall composition.
4. The local ecological conditions lacking host defense factors (e.g. root canals) may not be as challenging for the survival of C albicans as in the oral cavity. Phenotypic switching and resistance mechanism may explain the difference in the sensitivity of oral and root canal isolates.
5. Direct extrapolations should not be made from these in vitro studies with isolated single microorganisms to clinical situations with polymicrobial endodontic infections. C. albicans co aggregation reactions with other organisms in a mixed infection play a predominant role in the formation of complex biofilm, increasing microbial resistance to drugs and host defense mechanisms

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Temple University School of Dentistry. All contents copyright (C) 1996. All rights reserved.
Created: September 20, 2000 Revised: URL:

Roy H. Stevens, DDS, MS; Wanda Gordon, D.M.D. - Comments to author:	wgordon@dental.temple.edu
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