Abstracts
of the June 2007 Issue
Effect of LED light-curing time for
the adhesive resin
on the modulus of elasticity
Pisol Senawongse,
dds, msc,
phd,
Choltacha Harnirattisai,
dds,
phd,
Masayuki Otsuki,
dds,
phd
& Junji Tagami,
dds,
phd
Abstract:
Purpose: To evaluate the elastic modulus of successive
layers where an adhesive resin was cured by different
light-curing times. Methods: Eighty dentin discs which
were 2 mm thick were prepared from 40 sound third molars. The
dentin discs were further divided into four groups and bonded
with 3M Single Bond 2 and cured with an LED for 5, 10, 15 and
20s. Bonded specimens were restored with a microhybrid resin
composite. Specimens were cut perpendicular to the resin dentin
interface, embedded in epoxy resin, and polished. Polished
specimens were evaluated for the elastic modulus at the layer of
dentin, hybrid layer, adhesive resin, and resin composite at 24
hours after preparation. Results: Light-curing times
influenced the elastic modulus of hybrid layer and adhesive
resin. The significant differences of elastic modulus among
successive layers were found. The results suggested that
extension of light-curing times of adhesive resin from 5 to 20
seconds increased the mechanical properties of the resin dentin
interface. (Am J Dent 2007;20:139-141).
Clinical
significance: Extending the light-curing time of adhesive
resin from 5 to 15 seconds increased the modulus of elasticity
of hybrid layer and adhesive layer at resin-dentin interfaces
that might have a benefit on the durability of adhesive
restorations.
:
Dr. Pisol Senawongse, Department of Operative Dentistry, Faculty
of Dentistry, Mahidol University, 6 Yothi Street, Phayathai,
Bangkok, 10400, Thailand. E-:
dtpse@mahidol.ac.th
Spectrophotometric and visual shade
measurements of human teeth using three shade guides
Gabriele Fani,
dds,
Alessandro Vichi,
dds, phd
& Carel L. Davidson,
md, phd
Abstract:
Purpose: To compare spectrophotometric vs. visual
color identification of tooth shade on the basis of three
different commercially available shade guides. Methods:
On 54 subjects, two operators (with >10 years experience)
independently selected the best match of the middle third of one
of the patient’s upper central incisors, using consecutively
three shade guides (Vita Lumin Vacuum, Chromascop, Vita 3D
Master). After each individual shade match, the same operator
performed a shade measurement with a SpectroShade
spectrophotometer. Results: The Vita Lumin shade guide
appeared to provide the most consistent results between human
and spectrophotometrical evaluation, although Vita 3D Master
offered a greater variety of colors. In approximately 47% of the
cases, the spectrophotometer provided more accurate results than
visual selection. From a clinical point of view, this is a
noteworthy improvement in the complex process of color match for
indirect restoration. (Am J Dent 2007:20:142-146).
Clinical
significance: Spectrophotometric shade selection correlated
closely with visual shade selection, in particular with regard
to the Value (L) dimension of color.
:
Dr. Gabriele Fani, Viale Edmondo De Amicis, 25, 50127 Firenze,
Italy. E-:
fanig@tin.it
The effects of two monofunctional
diluent monomers and two photoinitiator systems on the
properties of UDMA-based composites
Nicola D. Richards,
dds,
phd
& Joseph M. Antonucci,
phd
Abstract:
Purpose: To compare the effects of two types of
monofunctional co-monomers and two types of photoinitiator
systems on the properties of urethane dimethacrylate (UDMA)
based dental restorative composites. Methods: The resin
blends consisted of UDMA and a diluent co-monomer at a molar
ratio of 9:1. The diluent comonomers were neo-decyl vinyl ester
(Neo 10) or n-hexyl methacrylate (HMA). The photoinitiator
system consisted of a bis-acyl phosphine oxide (BAPO) or
camphorquinone plus ethyl 4-(dimethylamino)benzoate (CQ/4E).
Each initiator system was utilized at 1% or 2% by mass of the
resin blend. These resin blends were mixed by hand with
silanized zirconia glass (85.7% by mass) to make the various
composites. Flexural strength (FS) specimens, made from these
pastes by visible light photopolymerization, were tested to
failure after 24 hours water storage. Mercury dilatometry was
used to evaluate the shrinkage, and the degree of double bond
conversion was evaluated using near infrared spectroscopy (NIR).
The first hypothesis tested was that use of Neo 10 in a UDMA
composite would not have an effect on properties compared to the
methacrylate HMA. The second hypothesis tested was that the BAPO
initiator would not have an effect on the properties of a UDMA-based
composite compared to the CQ/4E initiator. Results: The
hypotheses were tested at α= 0.05 and β= 0.20. The major finding
was that the lower level (1% by mass) of BAPO resulted in lower
FS, lower conversion and lower shrinkage (rejecting the
hypothesis that there was no difference due to initiator used)
than composites formulated with the higher level of this
initiator or either level of the CQ/4E initiator system,
regardless of the comonomer used. The effects of two comonomers
used were not differentiated in this study with respect to the
properties examined (accepting the hypothesis that there was no
difference due to diluent monomer). (Am J Dent
2007;20:147-152).
Clinical
significance: The lower level of BAPO had such low flexural
strength and conversion that it should not be used clinically.
As the higher level of BAPO performed as well as the CQ/4E
system, this class of initiators may hold promise for use in
dental composites.
:
Dr. Joseph M. Antonucci, National Institute of Standards
and Technology (NIST), Stop 8545, 100 Bureau Drive,
Gaithersburg, MD 20899-8545 USA. E-:
joseph.antonucci@nist.gov
Clinical and microbiological effects
of a combined mechanic-antibiotic therapy in subjects with
Actinobacillus actinomycetemcomitans-associated
periodontitis
Bettina Dannewitz,
dr
med dent,
Sabine Pohl,
dr
med,
Peter Eickholz,
prof,
dr med dent
& Ti-Sun Kim,
dr
med, dr med dent
Abstract: Purpose: To evaluate the clinical and
microbiological effects of a combined mechanic-antibiotic
periodontal therapy in subjects that were tested positive for
subgingival Actinobacillus actinomycetemcomitans (A.a.).
Methods: The postoperative follow-up ranged from 12-115
months (average 39.2 months). This follow-up study analyzed the
data of 53 subjects (37 females) aged from 16-59 years, who
underwent systemic periodontal therapy with adjunctive systemic
antibiotics between 1992-2001 and had their last re-examination
including microbiological analysis done in 2003. The antibiotic
regime was either amoxicillin/metronidazole or ciprofloxacine/metronidazole.
During this study, A.a. was detected with two gene probe tests (IAI
PadoTest 4.5 and DMDx/PathoTek) and cultivation on TSBV agar
plates. The clinical situation was characterized with the help
of pocket probing depths and subsequent categorization into
three different groups (
4 mm, 5-6 mm and
7 mm). Results: After therapy, A.a. was detected with IAI
PadoTest 4.5 in a magnitude between 3.0 x 103
up to 2.06 x 105
counts per specimen in 9 out of 53 subjects. Only two subjects
tested positive for A.a. with the DMDx/PathoTek-assays and the
agar cultivation. The clinical situation improved significantly
in all subjects after systemic periodontal therapy. The
treatment results remained stable during the course of the
postoperative follow-up. Concerning the clinical data, no
differences were found between the subjects that were tested
positive and negative for A.a in the postoperative period.
(Am J Dent 2007;20:153-156.
Clinical
significance: Positive test results for A.a. after completed
periodontal therapy should be evaluated critically in the
context of the clinical situation. These subjects should undergo
a regular supportive periodontal therapy to diagnose any
reinfection as early as possible and to plan the treatment
accordingly.
:
Priv. Doz. Dr. Ti-Sun Kim, Section of Periodontology, Dental
Clinic, INF 400, 69120 Heidelberg, Germany.
E-:
ti-sun_kim@med.uni-heidelberg.de
The role of oxygen inhibition of a
self-etch adhesive on self-cure
resin composite bonding
Tatsuo Endo,
dds,
phd
Werner J. Finger,
dr
med dent,
phd,
Marcus Hoffmann,
dr
rer nat,
Masafumi Kanehira,
dmd,
phd
& Masashi Komatsu,
dds,
phd
Abstract: Purpose: To evaluate the bond strengths on
enamel and dentin with a self-etch adhesive (iBond), with or
without oxygen-inhibited surface layer, or covered with
intermediate self-curing resin, in combination with
chemical-cured composite (Core Paste). Methods: Bond
strengths on human enamel and dentin (n = 8) were determined
according to the following procedures: 1. Adhesive cured under
ambient air. 2. Inhibited surface wiped with ethanol. 3.
Adhesive cured under nitrogen. 4. Adhesive covered with glycerol
during activation. 5. Adhesive coated with glycerol for 1 minute
after activation. 6. As 5, but covered for 5 minutes. 7. Cured
adhesive coated with intermediate self-curing resin. 8. As 7,
but intermediate resin’s amine component loaded with anion
exchange resin in OH-
form. Shear bond strengths (SBS) were measured
after 24-hour storage in 37°C water. Results: SBSs on
enamel (7.1 to 25.6 MPa) were, by ranking order (P< 0.05): 4 <
3, 5, 6 < 1, 2, 3, 6 <1, 2, 3, 7 < 1, 7, 8; SBSs on dentin (1.0
to 19.6 MPa): 1, 4, 5, 6 < 1, 2, 6 < 2, 3, 7 < 8. Oxygen
inhibition had no adverse effect on enamel bond strengths. On
dentin, all groups, apart from the anion exchange resin group
(mean 19.6 MPa), showed bond strengths < 8 MPa. Dentin SBS of
self-etch adhesive combined with self-cured resin was low,
irrespective of the presence of an oxygen-inhibited layer.
Deprotonization of the acidic adhesive monomer with an admixed
anion exchange compound, added to an intermediate self-cured
resin, was effective at overcoming the incompatibility. (Am J
Dent 2007;20:157-160).
Clinical
significance: Bond strength on dentin was severely
compromised when the self-etch adhesive iBond was used in
combination with chemical-cured resin composite.
:
Dr. Werner J. Finger, Department of Preclinical Dentistry,
School of Dental Medicine, University of Cologne, Kerpener
Strasse 32, D-50931 Cologne, Germany. E-:
wjfinger@aol.com
Micro-tensile and micro-shear bond
strengths of current self-etch adhesives
to enamel and dentin
Ayano Ishikawa,
dds,
Yasushi Shimada,
dds,
phd,
Richard M. Foxton,
bds, phd,
mfds rcs (Ed)
& Junji Tagami,
dds,
phd
Abstract:
Purpose: To evaluate the micro-tensile and
micro-shear bond strengths of self-etch adhesives to enamel and
dentin. Methods: Extracted human molars were ground to
expose flat enamel or dentin surfaces using wet #600 grit SiC
paper. The enamel and dentin surfaces were assigned to four
groups of four adhesives: three one-step self-etch adhesives (Clearfil
S3 Bond; AQ Bond Plus, G-Bond) and a two-step self-etch adhesive
(Clearfil SE Bond). Each of the adhesives were applied to the
enamel or dentin surfaces in accordance with the manufacturers’
instructions and restored with resin composite (Clearfil AP-X).
The bonded teeth were then prepared for either micro-tensile or
micro-shear bond strength tests. After storage in saline at 37°C
for 24 hours, specimens were stressed at a crosshead speed of 1
mm/minute. Mean bond strengths and modes of failure were
analyzed using one-way ANOVA followed by Scheffe’s F test and
the Chi-square test, respectively, at a 95% level of confidence.
Results: SE Bond produced significantly higher values
than the one-step adhesives in the micro-shear bond test to
enamel (P< 0.05), while no significant differences were found
among the adhesives in the micro-tensile bond test (P> 0.05).
For dentin, SE Bond showed the highest bond strengths in both
micro-tensile and micro-shear bond tests; values were
significantly higher than both AQ Bond Plus and G-Bond (P<
0.05). (Am J Dent 2007;20:161-166).
Clinical
significance: The two-step self-etch adhesive showed higher
bond strength values than the one-step adhesives in both the
micro-tensile and micro-shear bond tests.
:
Dr. Ayano Ishikawa, Cariology and Operative Dentistry,
Department of Restorative Sciences, Graduate School, Tokyo
Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo
113-8549, Japan. E-:
ishikawa.ope@tmd.ac.jp
Push-out bond strengths of endodontic
posts bonded with different
resin-based luting cements
Lionel Huber,
dmd,
Maria Cattani-Lorente,
phd,
Ligia Shaw,
dmd,
Ivo Krejci,
dmd,
phd
& Serge Bouillaguet,
dmd,
phd
Abstract: Purpose: To compare the push-out bond strengths of
endodontic posts bonded with different resin-based luting
cements and to verify that bond strengths did not vary with
cement thickness. Methods: 48 root canals were shaped
using 6% NiTi rotary files, obturated with gutta-percha and AH
Plus sealer and prepared for post cementation using Panavia F,
Parapost cement, SuperBond and Unicem Rely X. All roots were
sectioned into 0.7 mm thick slices and digital photographs of
each slice were analyzed using Scion Image to measure the
surface area of the luting cement. The root slices were stressed
to failure at 1 mm/minute using a push-out test. Push-out
strength was calculated as the force at failure divided by the
bonded surface area. Least squares linear regression analysis
was used to assess the effect of cement thickness on bond
strength. Fractured specimens were further observed under the
SEM. Results: Mean push-out bond strengths were: Panavia
F (8.8
3.6 MPa), Parapost cement (9.1
4.4
MPa) SuperBond (14.6
2.9 MPa) and Rely X Unicem (12.4
3.3
MPa). The Panavia F and the Parapost cement were not
significantly different from each other, but both were
significantly lower (P ≤ 0.05) than SuperBond and Rely X Unicem.
Although there were large variations in cement thickness, the
cementation of fiber posts with thicker cement layers did not
affect the performance of the adhesive luting cements applied to
root canal dentin. (Am J Dent 2007;20:167-172).
Clinical
significance: Although the thickness of the luting cement
observed after post cementation was variable, it did not
influence the bonding performances of the resin-based luting
cements tested to root canal dentin.
:
Dr. Serge Bouillaguet, Section of Dental Medicine, 19 rue B.
Menn, 1205 Geneva, Switzerland. E-:
serge.bouillaguet@medecine.unige.ch
Susceptibility of bleached enamel and
root dentin to artificially
formed caries-like lesions
Márcio de Menezes
dds,
Cecilia Pedroso Turssi,
dds, ms,
phd,
Juliana Jendiroba Faraoni-Romano,
dds, ms
& Mônica Campos Serra,
dds, ms,
phd
Abstract:
Purpose: To evaluate in vitro the
susceptibility of caries-like lesion formation on enamel and
root dentin that had been bleached with carbamide peroxide
agents. Methods: 150 slabs of bovine enamel and root
dentin were ground flat and polished. According to a randomized
complete block design, the specimens were then allocated to be
bleached with agents (Rembrandt) containing 12% [CP12], 16%
[CP16], 22% [CP22] or 30% [CP30] of carbamide peroxide over 21
days. The control group remained unbleached. Afterwards, all
specimens were randomly distributed between two sub-groups (n=
15): one was subjected to alternating demineralizing and
remineralizing solutions to induce caries-like lesions and the
other was not. Enamel specimens were cycled four times in
demineralizing (pH 5.0) and remineralizing solutions (pH 7.0),
while root dentin specimens were cycled twice. Microhardness
measurements were carried out at the post-bleaching and at the
post-caries lesion formation phases. Results: In the
post-bleaching condition, microhardness values for both enamel
and root dentin were dependent on the bleaching agent used. At
the post-caries formation stage, there was a significant
interaction between the bleaching treatment and substrate
condition (carious or noncarious) for enamel and root dentin.
Regardless of the bleaching agent, carious enamel and root
dentin presented significantly lower microhardness values as
compared to the noncarious counterparts. For carious enamel,
those specimens exposed to CP16 exhibited higher microhardness
values than the subset group formed by CP22, CP30 and unbleached
samples. Both subsets did not differ from CP12. For carious root
dentin, no difference was observed among the microhardness
values attained as a result of the different bleaching
treatments. (Am J Dent 2007;20:173-176).
Clinical
significance: Bleaching does not seem to pose any extra risk
to caries lesion formation in enamel and root dentin.
:
Dr. Cecilia Pedroso Turssi, Department of Restorative Dentistry,
Faculdade de Odontologia de Ribeirão Preto – USP, Av. do Café,
s/n Monte Alegre, Cep: 14040-904, Ribeirão Preto, SP, Brazil.
E-:
cturssi@yahoo.com
Shear bond characteristics of a
tooth-colored temporary coating material to enamel
Chieko Imamiya,
dds,
Yasushi Shimada,
dds,
phd,
Michael F. Burrow,
mds,
phd
& Junji Tagami,
dds,
phd
Abstract:
Purpose: To evaluate the bonding performance of a coating
material “White Coat” (Kuraray) to enamel. Methods:
Effect of surface treatment on bonding, durability of bonding,
as well as re-bonding as a repeated treatment were investigated
using extracted human incisors. To evaluate the effect of
surface treatment, intact or ground enamel surfaces were treated
using White Coat primer for 20 seconds or 40% phosphoric acid
(K-etchant) for 10 or 60 seconds, as well as combination usage
of White Coat primer and 40% phosphoric acid. Small resin
cylinders of the base-coat of White Coat were bonded to the
treated surfaces and irradiated for 30 seconds. For the
durability test, small resin cylinders of base coat were bonded
to intact enamel using White Coat primer and stored in 37°C
saline for 1 day, 1 week, 1, 3, and 6 months. Furthermore, to
investigate the effect of re-bonding after the removal,
re-bonding was done after various removal regimens. A
micro-shear test was used to assess the bond strength of all
specimens. Results: Application of the primer for 20
seconds to intact enamel produced a mean micro-shear bond
strength of 28 MPa for intact and ground enamel. Values were
similar to 10 seconds phosphoric acid etching to ground enamel
(P> 0.05). The bond strength of the primed intact enamel did not
decrease up to 3 months (P> 0.05), but decreased significantly
by 6 months (P< 0.05). The removal and rebonding of the coating,
as well as the storage time showed no significant influence on
the bonding of the coat (P> 0.05). Consequently, White Coat was
considered an acceptable temporary coating material for no
longer than 3 months. (Am J Dent 2007;20:177-181).
Clinical
significance: Within the limitations of this study, the
coating material White Coat showed acceptable bonding as a
temporary restoration in vitro for up to 3 months using
the associated primer. This material also showed no decrease of
the bond after repeated debonding and reapplication with no
enamel fracture being observed.
:
Dr. Chieko Imamiya, Cariology and Operative Dentistry,
Department of Restorative Sciences, Graduate School, Tokyo
Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo
113-8549, Japan. E-:
imamiya.ope@tmd.ac.jp
Clinical and radiographic evaluation of
adhesive pulp capping in primary molars following hemostasis
with 1.25% sodium hypochlorite:
2-year results
Tahsin Demir,
dds
& Zafer C.
Çehreli,
dds,
phd
Abstract:
Purpose: To evaluate, prospectively, the clinical and
radiological response of primary molars, pulp-capped with
calcium hydroxide and different adhesive systems after
hemorrhage control with 1.25% sodium hypochlorite (NaOCl).
Methods: 100 primary molar teeth were pulp-capped in 67
children who met inclusion criteria. Hemorrhage at the exposure
site was controlled with 60 seconds application of 1.25% NaOCl.
Teeth were randomly assigned into five groups (n=20 each) with
respect to the material/technique used for capping: (1) calcium
hydroxide cement (Dycal); (2) acetone-based total-etch adhesive
(Prime&Bond NT); (3) a non-rinse conditioner (NRC) and
Prime&Bond NT; (4) total-etching with 36% phosphoric acid
followed by Prime&Bond NT; and (5) a self-etch adhesive system (Xeno
III). Teeth in Group 1 were restored with amalgam and Groups 2-5
with polyacid-modified resin-based composite (Dyract AP). The
teeth were evaluated clinically and radiographically for 24
months. Marginal integrity of the restorations was also recorded
at recall periods using modified USPHS/Ryge criteria.
Results: After 2 years, the overall success rate of direct
pulp capping was approximately 93% (78/84 teeth, excluding
exfoliations). The Dycal and Prime&Bond NT groups did not
exhibit any clinical or radiographic failure. A majority of
failures were observed in teeth that received NRC and phosphoric
acid pretreatments (Groups 3 and 4). Clinical symptoms were
seldom associated with failed teeth. Only one tooth failed in
the Xeno III group. Marginal integrity scores were not
compatible with the clinical/ radiographic outcome. (Am J
Dent 2007;20:182-188).
Clinical
significance: For primary molars with Class I cavities that
are expected to exfoliate within 2 years, direct pulp capping
with prior NaOCl hemostasis can be performed using calcium
hydroxide or the tested total- and self-etch adhesives. However,
in pulp capping, the tested total-etch adhesive (Prime&Bond NT)
must not be used in conjunction with phosphoric acid or NRC.
:
Dr. Zafer C. Çehreli, Gazi M. Kemal Bulvari, 61/11, 06570
Maltepe, Ankara, Turkey. E-:
zcehreli@yahoo.com
Clinical and radiographic evaluation of
indirect pulp treatment
in primary molars: 36 months follow-up
Renata Franzon,
dds,
Luciano Casagrande,
dds, ms,
Alice Souza Pinto,
dds, ms,
Franklin García-Godoy,
dds, ms,
Marisa Maltz,
dds, ms,
phd
&
Fernando Borba de Araujo,
dds, ms
phd
Abstract:
Purpose: To evaluate the clinical and radiographic
changes in primary teeth submitted to indirect pulp treatment (IPT)
over a 36-month period. Methods: Thirty-nine
primary molars with deep caries, but without pre-operative signs
and symptoms of irreversible pulpits, received IPT. The teeth
were randomly divided into two groups, according to the material
used for protection of the dentin-pulp complex: (1) a calcium
hydroxide liner (Hydro C) and (2) a gutta-percha sheet. Both
groups were restored with Z250 resin-based composite.
Results: After 36 months, Group 1 showed a success rate
of 73.3% and Group 2, 85.7%. The overall success rate was 79.3%,
with no statistically significant difference between the groups
(P = 0.36). (Am J Dent 2007; 20:189-192).
Clinical
significance: The results of this study suggested that
indirect pulp treatment of primary teeth restored with a
resin-based composite may arrest the progression of the
underlying caries, regardless of the material used as a liner.
:
Dr. Fernando Borba de Araujo, Department of Pediatric Dentistry,
Faculty of Dentistry, UFRGS, Rua Ramiro Barcelos, 2492, Bom Fim,
Porto Alegre, Rio Grande do Sul, CEP: 90035-003, Brazil.
E-:
fernando.araujo@ufrgs.br
Effect of a 40% chlorhexidine varnish
on demineralization
of dentin surfaces in situ
Mozhgan Bizhang,
dds, dr
med
dent,
Rainer Seemann,
dds, phd,
dr med dent,
Gregor Römhild,
dds,
Yong-Hee P. Chun,
dds, ms, dr
med
dent,
Niklas Umland,
dds, dr
med
dent,
Hermann Lang,
dds,
phd
&
Stefan Zimmer,
dds, phd,
mphd
Abstract:
Purpose: To evaluate the effect of varnish with different
chlorhexidine concentrations on the demineralization of dentin
surfaces in situ. Methods: An intraoral model was
used to study the ability of chlorhexidine to prevent
demineralization. Dentin specimens from extracted human teeth
were treated with chlorhexidine varnish and exposed to the oral
environment of 47 subjects. The dentin specimens were prepared
from the cervical regions of 47 third molars, sterilized by
irradiation with 60 GY and mounted in intraoral appliances worn
by the subjects. Before the delivery of the appliance, the
specimens and participants were treated once with one of the
three different varnishes (according to the manufacturer’s
instructions). All participants were randomly assigned to one of
the three groups: (1) EC 40 (n=16), (2) Cervitec (n=15), or (3)
ChemFil Varnish (control group, n=16). The appliances were worn
day and night for 3 weeks. At mealtimes, the appliance was
stored in 10% sucrose solution. After exposure to
demineralization, the dentin surface was evaluated by
microradiography to assess the depth of the lesion (µm) and the
loss of mineral (Vol% µm). Data analysis was accomplished using
one-way ANOVA plus LSD testing (P< 0.05). Results: Both
chlorhexidine varnishes EC 40 and Cervitec resulted in
significantly decreased mineral loss and lesion depth in dentin
than the control. In addition, EC 40 treated specimens
demonstrated significantly reduced lesion depth compared to
Cervitec® and the control (109.22 µm vs. 139.23 µm and
178.21µm). (Am J Dent 2007;20:193-197).
Clinical
significance: The results suggested that dentin treatment
with either EC 40 or Cervitec prevents mineral loss and lesion
depth. Therefore, chlorhexidine treatment of dentin might be a
favorable regimen to prevent demineralization in patients at
high risk for root caries.
:
Dr. Mozhgan Bizhang, Heinrich-Heine-Universität, Dept. of
Operative and Preventive Dentistry and Endodontics, Moorenstr.
5, 40225 Düsseldorf, Germany. E-:
mozhgan.bizhang@med.uni-duesseldorf.de
Retention of three endodontic post
systems
John Peters,
dds,
Gad Zyman,
dds, Enrique Kogan,
dds,
Sergio Kuttler,
dds &
Franklin García-Godoy,
dds, ms
Abstract: Purpose: To evaluate the retention of three post
systems using one adhesive and one cement. The hypothesis
tested was that there was no significant difference among the
posts. Methods: 90 freshly extracted single rooted lower
bicuspids were evaluated for similar root morphology. The teeth
were decoronated using an Isomet saw leaving a 15 mm-long
sample. Preoperative digital radiographs were taken of all
samples from the buccal and mesial direction. A glide path was
established with #15K type file. Roots were then instrumented to
working length to a size #40 .04 using Profile nickel titanium
files. 1cc of distilled water was used as an irrigant after each
file to remove dentinal debris. The teeth were then obturated
with custom fit #40 0.04 taper gutta percha points and AH Plus
as a sealer, using a warm vertical compaction technique.
Residual gutta percha of 5 mm was left. The samples were divided
into three experimental groups to receive posts. Group 1: Fiber
White Para-Post No. 2 red; Group 2: No. 1 DT Light Post; Group
3: PeerlessPost No. 3. Post spaces were created in Groups 1 and
2 with the appropriate drills supplied by the manufacturer using
a slow speed handpiece. The post spaces from Group 3 required no
further preparation after endodontic treatment. All posts were
cemented with Nexus 2 Universal Luting System. A layer of excess
cement was left in the most coronal portion of the tooth for
visual confirmation of tensile strength failure. Using an
Instron the teeth were mounted in a custom-made jig to prevent
crushing of the post and to ensure extension perpendicular to
the long axis of the post. Samples were then subjected to
tensile stresses until failure occurred. Failure was defined as
the maximum load produced under tensile load that corresponded
to visual separation of the post from the tooth.
The maximum load at failure in kilograms
was recorded. The average of each group was compared for
significant difference. Data was analyzed using ANOVA at a
significance level of P= 0.016 (Bonferroni correction for
multiple t-tests). Results: Maximum load at
failure, measured in kilograms, were as follows: PeerlessPosts
126.07 kg, Fiber White Posts 90.14kg, and DT Light Posts 88.46
kg. ANOVA revealed a statistically significant difference among
the three posts systems. PeerlessPosts required statistically
significantly higher force to be removed while there was no
statistically significant difference between the Fiber White
Posts and the DT Light Posts; therefore, the hypothesis was
rejected. (Am J Dent 2007;20:198-200).
Clinical
significance: The PeerlessPost required more force to be
removed from single-rooted extracted bicuspids than the Fiber
White Posts and DT Light Posts (P= 0.0044, ANOVA and t-test
with Bonferroni correction). Furthermore, the PeerlessPost
required no canal preparation after the completion of root canal
therapy unlike the DT Light and the Fiber White posts.
:
Dr. Sergio Kuttler, College of Dental Medicine, Nova
Southeastern University, 3200 South University Drive, Fort
Lauderdale, Florida 33328, USA. E-:
skuttler@nova.edu |
