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Title: The effect of insertion rates on fill length and adaptation of a thermoplasticized gutta-percha technique Author: Levitan et al Journal: JOE vol. 29, No.8 August 2003; 505-508 Reviewer: Sang Shin, D.M.D. Purpose: To determine the effect of the insertion rate of a thermoplasticized gutta-percha obturation technique (Thermafil Plus) on the quality of the root canal obturation. Methods and Materials: A calibrated practitioner obturated the tooth in each of three groups with insertion rates of 18, 6, 3 mm/s (Duration of insertion 1s, 3s, 6s), respectively. The quality of the obturation was assessed by measuring the length of fill and the replication of induced canal irregularities, consisting of dimples and grooves. All measurements were made on a single tooth, with a working length of 18 mm from the canal orifice, embedded in a split mold, with 20 measurements for each insertion rate. Measurements were made under a low-power microscope, with the images recorded on videotape. Results: The length of fill decreased with decreasing the insertion rate, from a mean overextention of +0.88 mm (SD 1.12 mm) for the 18 mm/s rate to a mean underfill of -0.13 mm (SD 1.03 mm) for the 3 mm/s rate. A trend of decreasing fill with decreasing insertion rate was observed, with the difference between the insertion rates of 18 mm/s and 3 mm/s being statistically significant at p < 0.05 using a single comparison test. Replication of dimples decreased with decreasing the insertion rate from a mean reproduction of 99% for the 18 mm/s rate to a mean reproduction of 90% for the 3 mm/s rate. The replication of grooves also decreased with decreasing the insertion rate from a mean reproduction of 100% for the 18 mm/s rate to a mean reproduction of 88% for the 12 mm/s rate. Statistical analysis of the data for both the dimples and the grooves using a paired comparison post hoc Scheffe test found these differences are significant at p < 0.05. Conclusion: Although faster insertion led to better replication of irregularities in the extreme apical region, it seemed to come with the loss of control over final length of fill by consistent overextension beyond working length (+0.88mm). If quality of apical replication and length of fill are equally important, one could insert at the faster rate but stop short of working length (0.88mm), allowing the thermoplaticized gutta-percha to flow to the desired working length.
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Author:
Guess et. al. Journal:
JOE 2003;29(8):509-512 Reviewer: Jessy Tseng, D.D.S. Purpose: To analyze the adaptation of gutta-percha
(GP) to prepared root canal walls using two obturation Materials and Methods:
Results:
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Authors: Siqueira, J.F.
et. al. Journal: Journal of Endodontics. 29 (8), 2003 Reviewer: Brett Strong Purpose: To evaluate the effectiveness of four intracanal medications ((Ca(OH)2/Glycerin,
Ca(OH)2/0.12% chlorhexidine digluconate, Ca(OH)2/camporated paramonochlorophenol(CMCP)/glycerin, 0.12% chlorhexidine digluconate/zinc
oxide) in disinfecting the root dentin of bovine teeth experimentally
infected with Candida albicans. Materials
and Methods:
Results:
Discussion: As shown in previous studies both C.
albicans and E. faecalis resist elimination when challenged
with calcium hydroxide suspended in an inert vehicle (glycerin, saline,
water). Therefore, the antibacterial
effects of Ca(OH)2 combined with other
antimicrobial medications is being investigated in this and other
experiments. Prior papers have demonstrated that a Ca(OH)2/chlorhexidine
combination is equally as inefficient in eliminating In this study both Ca(OH)2/CMCP/glycerin and 0.12% chlorhexidine digluconate/zinc oxide were effective in eliminating C. albicans in less than 1 hour. However, at this time the authors only recommend a mixture containing Ca(OH)2 because chlorhexidine has not been as thoroughly tested with regard to its sequelae when placed as an interappointment medicament.
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Title:
Crown-down tip design and shaping Authors:
de Leon, T.P. et. al. Journal: Journal
of Endodontics:29(8)513, August 2003 Reviewer:
Vahid Atabakhsh, D.D.S. Purpose: Materials
and Methods: Curved plastic canals size 25, 0.02 taper were
used. A 25 Flex-R was fitted to the
apex in each canal, and radiographed. The working length (WL) ranged from 16.5 to
18.5 mm. Each radiograph was magnified
10 times and file path traced on cephalometric
paper. Curvature angle was determined
with the Schneider method and demonstrated at 30 to 44 degrees. All canals were instrumented to 7 mm of
apex with #2-6 Gates Glidden, each shaping 2 mm of the coronal canal. Canals were divided to 3 similar groups,
each with 30 specimens. Two clinicians
participated, shaping 15 specimens for each group. The above three brands of stainless steel
(SS) files sizes 60 to 25 were used ( with crown down technique- using 60
first). Each resin block was mounted
and radiographed.
The apical 7 mm were instrumented using one of the 3 files. Crown-down from #60, clockwise rotation
with water as irrigant and recapitulation was done
after each file with a #25.
Radiographs were digitized, and NIH image software used to measure the
longitudinal cross section in the apical 7 mm. Data were analyzed by single-factor
ANOVA. Results: Of the 210 possibilities per instrument group (files #60, 55, 50, 45, 40, 35, 25 = 7 files X 30 canals per group):
The average cross sectional area created by the 3 files in the apical 7mm of the canal space were:
ANOVA showed significance at P<0.001. Moreover, canals instrumented with Flex Mor-Flex and Flex-O showed more transportation than
Flex-R. ANOVA showed significance at
P<0.001 again. Discussion/Conclusion: Both operators concluded that it was more
difficult to shape with a pyramidal tipped file as it; required more pressure
to advance, threaded the canal rather than shaping it, ledged, required more
bypass procedures and was damaged more during instrumentation. The ridges on the face of a pyramidal
shaped tip give it the ability to cause ledging. Conical shaped tips prevent ledging, but transport and fail to shape the inner
wall to the instrument tip. The biconical tip tends to shape the inner wall
to instrument tip. The incidence of
transportation and ledging increases as smaller
files go successively deeper and make greater deflection from a straight
path. Thus, crown-down not only frees
each instrument from coronal contacts, but also causes the radius of
curvature to become less. The biconical tip reduces the final canal diameter and
incidence of transportation relative to the other two tips at all levels
(ANOVA, P<0.001). There were more
damaged biconical tipped files which may be due to
the fact that the clinicians were unfamiliar with crown-down clockwise
rotational instrumentation initially and that unfamiliarity is reflected in
the first experimental group, the biconical
group. The biconical
tip’s lack of transition angles and formation of lands allows the canal to
reorient the tip through curvatures and the file stays centered, thus cutting
all sides more evenly. Thus, ledges
are eliminated and transportation is reduced. There have been other studies that show
the same biconical tip design to be superior for
curved canals. (Powell, et al. and Sabala et al.) |
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Title: Pattern
of vertical root fracture: factors affecting stress distribution in the root
canal. Author : Lertchirakarn et al. Journal : Journal of Endodontics Vol.29 (8), 2003 Reviewer : Sahrip Kim, D.D.S. Purpose: To compare quantitatively the tensile-stress distribution from various models of simulated canal sections, and to relate stress patterns to fracture patterns observed in teeth subjected to clinical or experimental vertical root fracture. Material
and Methods: -FEA was used for analysis of stress distribution. -Developed 6 idealized simple models of dentin and canal Model I : Cylindrical root and canal 1N( -Developed models based on fractured roots (digitized cross-section at level of vertical root fracture - VRF) Model VII : Mandibular Incisor (bucco-lingual fracture) 6N applied perpendicular to canal surfaces. Distribution of stresses in relation to fracture pattern examined. -Graphical representations of stress variation in a mid-level cross-section were obtained and maximum tensile stress was computed for each model. Results: Simple Dentin models:
Fractured tooth roots : Model VII :
Model VIII :
Discussion:
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Title: Identification of resected
root-end dentinal cracks: a comparative study of visual agnification. Author:
Slaton et. al. Journal: Journal of Endodontics 29(8),
2003 Reviewer: Hung Do, D.D.S. Purpose: To evaluate and compare the effectiveness
of visual enhancements as aids in correctly identifying artificially created
dentinal cracks in resected root ends. Materials and Methods:
1.
unaided/corrected vision (group 1) Results: ·
The accuracy of correct identification of cracks using:
1.
unaided/corrected vision = 39% ·
Three types of cracks were seen:
1.
canal cracks (both complete and incomplete) Discussion: The study found that with increasing
magnification, accuracy gets improved.
Accuracy however was lower than expected. Two factors that can contribute to this are
light reflection and irregularities in the resected
root ends. |
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Title: Finite element analysis and strain-gauge studies of vertical root fractures Author: Lertchirakarn, et al. Journal: JOE: 29(8)529, Aug 2003 Reviewed by: J. Lee Purpose: Investigate the stress distribution generated in maxillary and mandibular incisors by forces applied with in the canal using finite element analysis (FEA) and to use stain-gauge techniques to validate the root surface strain results obtained from FEA. Materials and Methods: Ten maxillary and mandibular incisors were instrumented and obturated to mid-root level by lateral condensation. Strain gauges placed on buccal/lingual and mesial/distal walls of root surfaces ~apical and middle third of the root and placed in servohydraulic testing machine. Each tooth subject to increasing force with D11 spreader tip until fracture occurred. Results: Distribution of stress by FEA for both maxillary and mandibular incisors with similar results:
Distribution of strain on the outer root surfaces (FEA): mostly compressive stain on buccal/lingually and tensile strain on proximal. Strain measurement w/ strain-gauge technique: mostly compressive strain on the buccal/lingual and tensile stain on proximal. Proximal stain >> buccal/lingual stain. Discussion: Greater distribution of stress on buccal/lingual direction than proximal may be due to asymmetry of canal shape. Strain measurement by FEA and stain-gauge method with “good” correspondence. But still no predictable way to suggest patterns of root fractures.
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Title: Repair of perforating internal resorption with mineral trioxide aggregate: A case report. Author: Hsien et al. Journal: Journal of Endodontics Vol.29, No.8 August 2003 Reviewer: Rahul Gupta, D.D.S. Purpose: To show a case report of perforating internal resorption on a maxillary central incisor and its repair using mineral trioxide aggregate. Case Report: A 39 year old female with buccal swelling with sinus tract located on the attached gingival of maxillary left central incisor (tooth # 9) for several weeks was referred to the hospital dental clinic. Before coming to the hospital dental clinic the patient had gone to three local clinics for help, where the tooth was opened and debrided. But the symptoms and signs did not subside as expected, so she was referred to the hospital dental clinic. In the hospital dental clinic, on performing diagnostic tests the tooth had biting and percussion pain, tenderness on palpation, and mild mobility with normal probing depth. The patient’s medical history was noncontributory and dental trauma history was denied. A previous disto-palatal composite resin restoration with extensive secondary caries was noted on the tooth. Radiographic examination showed an oval radiolucent lesion that was later confirmed as internal resorption in the middle third of the canal. Access to the canal system was reestablished. The original canal was negotiable, but the canal could not be completely dried because of continuous exudation and hemorrhage. Surgical intervention was used. The apical third was obturated with gutta-percha, and the perforated lesion was repaired with mineral trioxide aggregate(MTA). A week later the patient returned, then the residual canal space coronal to the MTA was backfilled with a warm gutta-percha system and the tooth was restored with composite resin. A 2-week follow-up evaluation found that the sinus tract had healed. The patient was asymptomatic at the 1-year follow-up. Discussion: Mineral trioxide aggregate has many
favorable properties, including good sealing ability, biocompatibility, radiopacity, bacteriostatic
activity, and moisture resistance.
There are many studies or clinical case reports of iatrogenic
perforation repair with MTA. This case
report demonstrates successful repair of perforating internal resorption with MTA. |
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Title: Effect of MTAD on enterococcus faecalis –
contaminated root canals of extracted human teeth Author:
Shabahang, S and Torabinejad,
M Journal: JOE, vol. 29 (9) September 2003 Reviewer: Michael Moreno, D.M.D. Purpose: The purpose of this study was to compare the antimicrobial effect of MTAD with that of NaOCl with and without EDTA. Materials and Methods: Eighty-five single rooted human anterior teeth were accessed and sterilized after removing the pulp with a barbed broach. The teeth were immersed in an inoculum of E. faecalis for four weeks under aerobic conditions at 37 degrees F. After biomechanical instrumentation to size 35 using 1.3% or 5.25% NaOCl as root canal irrigant, the root canal and the external surface of each tooth were exposed to a 5-min application of MTAD, 1.3% NaOCl, 5.25% NaOCl or a 1-min application of EDTA followed by irrigation with 5 ml of 1.3% NaOCl or 5.25% NaOCl. Teeth or dentin shavings were cultured to determine presence or absence of the test bacteria. Results: Conclusion: Fisher’s exact test showed that the combination of 1.3% NaOCI as a root canal irrigant and MTAD as a final rinse was significantly more effective against E. faecalis than the other regimens.
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Title: Effectiveness of selected materials against enterococcus faecalis: part 3. the antibacterial effect of calcium hydroxide and chlorhexidine on enterococcus faecalis. Author: Lin et. al. Journal: Journal of Endodontics 29(9), 2003 Purpose: To evaluate the antibacterial effect of calcium hydroxide, chlorhexidine, and a combination of the on two enterococcus faecalis versus an ampicillin control. Materials & Methods: Ten agar plates were swabbed with E. Faecalis, and filter paper points saturated with the following test agent(s) were placed on the plates and incubated for 72 hours: o Group 1: calcium hydroxide powder with sterile water. o Group 2: Pulpdent® (calcium hydroxide paste) with sterile water. o Group 3: Peridex® (0.12% chlorhexidine) o Group 4: calcium hydroxide powder with Peridex® o Group 5: Pulpdent® with Peridex®. o Control: Ampicillin Zones of inhibition were measured from periphery of the paper disk after 24 and 72 hours. Results: No changes in size of inhibition after 24 hours. After 72 hours: o There was no significant difference between the calcium hydroxide powder and Pulpdent®. o Peridex® alone and the combination with either of the calcium hydroxide preparations showed significantly better antibacterial effect than either of the calcium hydroxide preparations alone. o There was no significant difference between Peridex® alone and Peridex® combined with either of the calcium hydroxide preparations. Discussion: Although there was a significant difference between the use of calcium hydroxide and chlorhexidine the authors of the article stated that this might have resulted from the experimental method used. None-the-less, in this study chlorhexidine showed significantly better antibacterial activity against E. Faecalis than calcium hydroxide, and the addition of calcium hydroxide to chlorhexidine did not enhance the antibacterial effect.
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Title: The effect of passive ultrasonic activation of 2% chlorhexidine or 5.25% sodium hypochlorite irrigant on residual antimicrobial activity in root canals Author: Weber, C.D. et al. Journal: JOE, 29 (9) 2003, 562-564. Reviewer: Allyson Byrne, D.M.D. Purpose: To evaluate the effect of passive ultrasonic activation of 2% chlorhexidine (CHX) and 5.25% NaOCl irrigant on residual antimicrobial activity in root canals. Materials & Methods: 94 freshly
extracted single canal teeth were used.
Instrumentation was completed using the step-down technique. Between file sizes, teeth were irrigated w/ 1mm of either 2% chlorhexidine
or 5.25 % NaOCl.
Teeth were divided into 5 groups.
After instrumentation was completed, canals were further enlarged with a parapost drill to provide a standardized reservoir depth of 8mm, and the apical 3-5mm was covered w/ nail polish. (the majority of apical ramifications are in the apical 3-5mm). Canals were then rinsed w/ sterile saline (PBS), dried, refilled with PBS and stored. 6hrs after instrumentation, 20 ml of fluid was pipetted from each canal and placed into wells on agar plates, which were inoculated w/ Streptococcus sanguinis. The plates were incubated and zones of inhibition were measured. Canals were then rinsed, refilled w/ PBS and stored. Sampling was repeated 24, 48, 72, 96, 120, 144, and 168 h. Results:
Conclusion: Residual antimicrobial activity with 2% CHX was statistically significantly superior to 5.25% NaOCl with irrigation alone and with final passive ultrasonic activation. CHX groups showed antimicrobial activity for as long as 168 h.
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