|
Evaluation of intracanal sealer distribution with 5 different obturation techniques.
Quintessence Int. 2005 Oct;36(9):721-9.
Hugh CL, Walton RE, Facer SR.
OBJECTIVE: The aim of this study was to determine the distribution patterns of sealer
relative to the gutta-percha and the canal wall following the use of different obturation
techniques: vertical condensation, Obtura II, System B, SimpliFill, and Thermafil Plus;
lateral condensation was used as a comparison. METHODS AND MATERIALS: One hundred five
extracted single-rooted teeth were divided into 5 groups of 20 according to obturation
technique, with 5 in the lateral condensation group. Instrumentation technique and sealer
selection were based on the manufacturer's recommendations. Following obturation, teeth
were stored for 4 months at 37 degrees C in 100% humidity. Roots were split longitudinally
and halves were examined under a stereomicroscope (x 10) to determine the amount of
sealer coverage between the gutta-percha and canal wall. Coverage was categorized as
slight (0 to 1/3), low partial (1/3 to 2/3), high partial (2/3 to 9/10), and complete
(9/10 to 10/10). RESULTS: Different techniques showed different patterns, but no
obturation technique had sealer forming a continuous layer between the gutta-percha
and canal wall. The vertical condensation group generally had low partial coverage.
Obtura II was the only group to have slight coverage, which occurred in the coronal
half. Coronal and apical halves in both the System B and Thermafil Plus groups had
the most samples with high partial coverage. SimpliFill had the most samples with
complete coverage in both the coronal and the apical portions.
All lateral condensation samples showed low partial coverage.
CONCLUSION: Sealer distribution patterns were incomplete and inconsistent,
regardless of the obturation technique.
No technique had sealer forming a continuous layer between the gutta-percha and canal wall.
Effect of root canal filling/sealer systems on apical endotoxin penetration: a coronal leakage evaluation.
J Endod. 2005 Aug;31(8):599-604.
Williamson AE, Dawson DV, Drake DR, Walton RE, Rivera EM.
Endotoxin, elaborated by gram-negative organisms, is an important factor in apical
periodontitis. The objective of this study was to evaluate the magnitude of endotoxin
penetration through root canal treated teeth using a dual chamber model system.
Forty-four maxillary anterior teeth were prepared endodontically and canals filled either
by lateral condensation or a warm thermoplasticized technique in combination with either
Roth's 801 or AH 26 sealer. Teeth were suspended in the model system with a mixed anaerobic
bacterial suspension in the upper chamber and HBSS in the lower chamber. The QCL-1000 LAL
assay was used to measure endotoxin at 0, 1, 7, 14, and 21 days. Response feature analysis
using trapezoidal area under the curve was performed; the four treatment groups were
compared using nonparametric methods. Groups differed (p = 0.028), with thermoplasticized
root canal filling/Roth's 801 sealer permitting the least apical endotoxin penetration.
Results suggest that Roth's 801 sealer may have a role in inhibiting endotoxin penetration.
Determining the optimal obturation length: a meta-analysis of literature.
J Endod. 2005 Apr;31(4):271-4.
Schaeffer MA, White RR, Walton RE.
The purpose was to aid in determining termination of instrumentation and obturation.
A meta-analysis was conducted as to success/failure of different obturation lengths.
Inclusion criteria were (a) minimum follow-up of 2 yr, (b) data on obturation length,
(c) definition of success/failure, (d) available data on success/failure, (e) radiographic
evaluation. Correlations were made as to success/failure as related to length of obturation
from the apex. When comparing group A (obturated 0-1 mm from apex) versus group C
(obturated past apex) using the DerSimonian and Laird estimates, group A showed
a marginally better (p < 0.10) success rate than group C by 28.8%. Group A had better
success than group B (obturated >1 mm short); the difference was insignificant. The
results were similar after controlling for study quality using a single random effects
regression model. In conclusion, the meta-analysis indicated that
a better success rate is achieved when treatment includes obturation short of the apex.
Calcium hydroxide as an intracanal medication: effect on posttreatment pain.
J Endod. 2003 Oct;29(10):627-9.
Walton RE, Holton IF Jr, Michelich R.
Calcium hydroxide is advocated as an intracanal medication for various purposes,
including prevention of posttreatment symptoms. This study assessed whether calcium
hydroxide had a pain-controlling effect at different times when compared with no intracanal
medication. One hundred forty patients participated. Conditions diagnosed were
pulp/periapical pathosis with or without symptoms. At least partial cleaning and
shaping was completed. At random, either Ca(OH)2 plus H2O paste or a dry cotton
pellet was placed in the canals of half the teeth, respectively. All teeth were
temporized with Intermediate Restorative Material. Patients assessed posttreatment
pain up to 48 h as none, mild, moderate, or severe. The pain levels in each test
group [Ca(OH)2 versus cotton pellet] at each time period were compared
statistically with a multiple-regression analysis. There was no significant
difference in posttreatment pain between the two groups at any time period or
with any diagnosis or symptom. The use of calcium hydroxide as an intracanal
medication was unrelated to the incidence and/or severity of posttreatment pain.
Straight line access and coronal flaring: effect on canal length.
J Endod. 2002 Jun;28(6):474-6.
Schroeder KP, Walton RE, Rivera EM.
The object of this study was to determine if canal length is altered as a result of
straight-line access (SLA) and coronal flaring (CF). Selected were 86 canals of extracted
molars and premolars from two groups: straight or severely curved (Schneider curvature
<5 degrees and >20 degrees). The reference cusp tip and root-end were flattened to produce
reproducible measurements. A #10 file was placed such that the tip extended slightly beyond
the apex, with the handle on the referenced cusp. The amount of file protrusion was
measured with a stereomicroscope. Then, SLA and CF were performed and the corresponding
file replaced to the same coronal reference position. Apical file protrusion was
measured again. The change in canal length was determined by the difference in the
pre- and post-SLA/CF measurements. A Wilcoxon signed rank test statistically verified
that there was a measurable, significant (p < 0.001) change in canal length after SLA
and CF. The mean change overall was slight, with a decrease of 0.17 mm.
Severe curvature had a slightly greater, significant effect on the amount of change.
Tooth type had no significant effect. Changes in working length from SLA and CF,
although statistically significant, were very small and clinically unimportant.
Relationship between number of proximal contacts and survival of root canal treated teeth.
Int Endod J. 2002 Feb;35(2):193-9.
Caplan DJ, Kolker J, Rivera EM, Walton RE.
AIM: The present study tested the hypothesis that having two proximal contacts (PCs)
at access is associated with improved survival of root canal treated (RCT) teeth,
controlling for important presenting conditions, endodontic variables and restorative factors.
METHODOLOGY: A treatment database at the University of Iowa College of Dentistry was used
to identify permanent teeth undergoing obturation between 1 July 1985 and 31 December 1987.
The list was restricted to teeth of patients with at least one dental visit in each
two-year interval from 1985 to 1996, and a simple random sample of 280 patients
(n = 400 teeth) was selected. Dental charts, radiographs, and computerized databases
were examined to ascertain variables of interest and to verify study inclusion criteria.
Kaplan-Meier survival estimates were generated for the 221 teeth satisfying study
inclusion criteria. Multivariate Cox models were developed, with standard errors
adjusted to account for clustering of teeth within patients. RESULTS:
The final Cox model showed that teeth with < or =1 PC at access were lost at a rate
three times that of teeth with 2 PCs
(hazard ratio = 3.1; 95% confidence interval = 1.9-5.1), controlling for tooth type,
presence of radiographic caries at access, and presence of a crown before or after
obturation. CONCLUSIONS: Because RCT teeth with two PCs at access experienced
substantially better survival than teeth with fewer than two PCs, the influence
of PCs on prognosis should be recognized during treatment planning.
Future research should employ prospective study designs,
capture additional variables, and provide data to support endodontic treatment decisions.
Apical terminus location of root canal treatment procedures.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2000 Jan;89(1):99-103.
Wu MK, Wesselink PR, Walton RE.
The apical termination of root canal treatment is considered an important factor
in treatment success. The exact impact of termination is somewhat uncertain; most
publications on outcomes are based on retrospective findings. After vital pulpectomy,
the best success rate has been reported when the procedures terminated 2 to 3
mm short of the radiographic apex. With pulpal necrosis, bacteria and their byproducts,
as well as infected dentinal debris may remain in the most apical portion of the canal;
these irritants may jeopardize apical healing. In these cases, better success
was achieved when the procedures terminated at or within 2 mm of the radiographic
apex (0 to 2 mm). When the therapeutic procedures were shorter than 2 mm from or
past the radiographic apex, the success rate for infected canals was
approximately 20% lower than that when the procedures terminated at 0 to 2 mm.
Clinical determination of apical canal anatomy is difficult.
An apical constriction is often absent. Based on biologic and clinical principles,
instrumentation and obturation should not extend beyond the apical foramen.
Scanning electron microscope study comparing four root canal preparation techniques in small curved canals.
Int Endod J. 1997 Sep;30(5):323-31.
Heard F, Walton RE.
Various instrumentation techniques have been proposed and examined with conflicting results.
They include hand and ultrasonic techniques and combinations of the two.
In the present study we assessed the effectiveness of four preparation methods for cleaning
small, curved root canals, using backscattered-imaging scanning electron microscopy (SEM).
The methods were: (i) step-back without initial coronal flaring; (ii) step-back with
coronal flaring; (iii) step-back with initial coronal flaring and finished by ultrasonic
irrigation; and (iv) ultrasonics only. Eighty freshly extracted maxillary and mandibular
molars were randomly placed into four treatment groups of 20 teeth each.
After preparation, roots were sectioned longitudinally and examined wet by SEM.
Each canal was qualitatively evaluated and the groups compared for removal of
debris and smear layer, both overall and at each level (apical, middle and coronal).
There were no statistically significant differences between the techniques,
either overall or within any of the regions. When comparing regions
(regardless of technique) the middle level was cleaner than the apical or coronal
levels. In conclusion, efficacy differed little among the
techniques; none of them completely removed smear layer and all left debris.
|
|
|
