Abstracts
of the August 2007 Issue
Clinical reversal of root caries using ozone: 6-month results
Aylin Baysan,
bds,
msc, phd,
mfds, rcsed & Edward Lynch,
ma, bdentsc, fds,
phd
Abstract: Purpose: To assess the safety
and efficacy of ozone either with or without a root sealant, for
the management of leathery root caries. Methods: 79
subjects with 220 root caries lesions were recruited into four
study groups in this randomized, controlled trial. At baseline
and after 1, 3, and 6 months, the ECM III and DIAGNOdent were
employed. Subsequently, the root caries lesions were clinically
assessed for color, hardness, cavitation, dimensions, distance
from the gingival margin, and severity index. Modified USPHS
criteria were also performed after 1, 3, and 6 months. These
groups were as follows: Group 1: Ozone application was
performed for a period of 10 seconds on caries lesions; Group 2:
There was neither ozone nor root sealant application on root
caries; Group 3: Ozone treatment and a root sealant were applied
to root caries lesions; and Group 4: Only root sealant was
applied to root caries. Results: At the 6-month recall,
78 subjects were examined. There were no observed adverse
events. 38.1% of lesions became hard in the ozone only group,
while none of the lesions became hard in the control group (P<
0.001). Noncavitated lesions were more likely to reverse than
cavitated lesions. 38.4% of noncavitated lesions became hard,
while only 5.7% of cavitated lesions became hard in the ozone
only group. Modified USPHS criteria revealed that there were
66.6% intact sealants in the ozone and sealant group and 45.5%
intact sealants in the sealant only group (P< 0.05). After 1, 3,
and 6 months, the ECM and DIAGNOdent readings showed
improvements in the ozone only group when compared to the
control group (P< 0.001). The ozone and sealant group also had
greater improvements in the ECM and DIAGNOdent values when
compared to the sealant only group (P< 0.05). (Am J Dent
2007;20:203-208).
Clinical significance: The clinical
implications of the ECM and DIAGNOdent are promising for
detecting the severity of root caries lesions. Noncavitated
leathery root caries lesions can be treated non-operatively by
the employment of ozone for a period of 10 seconds. The root
sealant showed a reduced retention at 6 months but was retained
better on ozone-treated root caries lesions.
Address: Dr. Aylin
Baysan, Adult Oral Health, The Institute of Dentistry, Barts and
The London Queen Mary's School of Medicine and Dentistry, Turner
Street, London E1 2AD, United Kingdom. E-:
aylin.baysan@kcl.ac.uk
Desensitizing efficacy of a new
toothpaste containing 5.5% potassium citrate:
A 4-week clinical study
Rafaella Docimo,
md, dds,
Luigi Montesani,
md, dds,
Paolo Maturo,
dds,
Micaela Costacurta,
dds,
Martina Bartolino,
dds,
William DeVizio,
dmd,
Yun Po Zhang,
msc, phd
& Serge Dibart,
dmd
Abstract: Purpose: To
evaluate the desensitizing capabilities of a new toothpaste
containing 5.5% potassium citrate (Colgate Sensitive Multi
Protection Toothpaste) to another toothpaste containing 3.75%
potassium chloride (Sensodyne Total Care F Toothpaste).
Methods: A 4-week clinical study was conducted in 75
subjects at the University of Rome, at Tor Vergata, in Rome,
Italy, using a double blind, stratified, two treatment design.
Tactile sensitivity as well as air blast sensitivity assessment
was used to compare the efficacy of the two products.
Results: There was no statistically significant difference
in tactile sensitivity scores and air blast sensitivity scores
between the tested toothpastes at baseline, 2 weeks and 4 weeks.
Both toothpastes provided statistically significant improvement
in tactile sensitivity scores and air blast sensitivity scores
after 2 weeks of use and 4 weeks of use as compared to baseline
scores. (Am J Dent 2007;20:209-211).
Clinical significance: Colgate
Sensitive Multi Protection Toothpaste was as effective as
Sensodyne Total Care F Toothpaste in decreasing dentin
hypersensitivity and providing subjects relief.
Address: Dr. Serge
Dibart, Boston University School of Dental Medicine, 100 East
Newton Street, Suite G-217, Boston, MA 02118, USA. E-:
sdibart@bu.edu
Effect of dentifrice containing
5000 ppm fluoride on non-cavitated
fissure carious lesions in vivo after 2
weeks
Jörg Fabian Schirrmeister,
dds, dr
med dent,
Jens Peter Gebrande,
dds,
Markus Jörg Altenburger,
dds, dr
med dent,
Jürgen Schulte Mönting,
prof,
dr rer nat &
Elmar Hellwig,
dds, prof,
dr med dent
Abstract: Purpose: This
randomized clinical trial compared the ability of two
dentifrices, one containing 5000 ppm fluoride (Duraphat) and the
other 1450 ppm fluoride (Caries Protection, control) to reverse
non-cavitated fissure carious lesions. Methods: 30 adults
having occlusal lesions with DIAGNOdent values between 10 and 20
were randomly assigned to two groups of 15 participants each.
DIAGNOdent measurements were performed after cleaning the teeth
with cleaning brushes and after additional cleaning using an
airflow device. The participants were instructed to brush their
teeth three times a day for 3 minutes after the meals with a 2
cm line of their assigned dentifrice. After a period of 2 weeks,
the teeth were cleaned again with the airflow device and laser
fluorescence measurement was performed. Results: The
group using the dentifrice containing 5000 ppm showed a
significantly higher decrease in laser fluorescence (21%) over
the test period than the control group (4%; P< 0.001; repeated
measures ANOVA). The decrease in laser fluorescence in the test
group was significant (P< 0.001; Wilcoxon signed-rank test). The
difference between cleaning the teeth with cleaning brushes and
additional cleaning with airflow before DIAGNOdent measurement
was not statistically different (P> 0.05; Wilcoxon signed-rank
test). (Am J Dent 2007;20:212-216).
Clinical significance: The
dentifrice containing 5000 ppm fluoride was significantly better
than the dentifrice containing 1450 ppm fluoride regarding
reversal of non-cavitated fissure carious lesions.
Address:
Dr. Jörg F. Schirrmeister. Department of
Operative Dentistry and Periodontology, Albert-Ludwigs-University
Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany. E-:
joerg.schirrmeister@uniklinik-freiburg.de
Treatment of root sensitivity after
periodontal therapy
Maria F. Fiocchi,
dds, ms, ms,
Antonio J. Moretti,
dds, ms,
John M. Powers,
phd
& Terry Rives,
drph
Abstract:
Purpose: To compare the effectiveness of an agent that
promotes deposition of amorphous calcium phosphate (Quell
Desensitizer) to a commonly used product, sodium fluoride
solution (Nupro Neutral), in the reduction of root sensitivity
after periodontal therapy, in a prospective, convenient sample,
double-blind clinical trial. Methods: Thirty patients
were enrolled and treated, resulting in 40 teeth treated with
the test product and 40 teeth treated with the control product.
The clinical parameters tested at baseline and in the follow-up
visits (1, 2, and 4 weeks after treatment) were the following:
plaque index, gingival index, gingival recession, and response
to mechanical and cold stimulation with airblast and ice.
Patients were also asked to report the grade of pain response on
a Visual Analogue Scale (VAS) on the same schedule as the
clinical parameters. Results: Plaque index and gingival
index were not significantly different between test and control
groups throughout the study. Most recession was observed on
midbuccal surfaces. Buccal surfaces evoked higher pain response
compared to lingual surfaces. It was concluded that both control
and test treatments reduced root sensitivity response reported
with mechanical or cold stimulation. No statistically
significant differences were observed when the data of both
groups were compared by a Student’s t-test at the 0.05
level of significance. (Am J Dent 2007;20:217-220).
Clinical
significance: There was no difference between test and
control treatment (i.e. amorphous calcium phosphate and
sodium fluoride) in reducing root sensitivity after scaling and
root planing.
Address:
Dr.
Maria F. Fiocchi, 6516 M.D. Anderson Blvd., Suite 306, Houston,
TX 77030 USA. E-:
Maria.F.Fiocchi@uth.tmc.edu
Penetration of radiopaque dental
restorative materials
using a novel ultrasound imaging system
Rahul S. Singh,
phd,
Martin O. Culjat,
phd,
Jason C. Cho,
bs,
Ratnakar R. Neurgaonkar,
phd,
Douglas C. Yoon,
dds,
Warren S. Grundfest,
md,
Elliot R. Brown,
phd
& Shane N. White,
bdentsc, phd
Abstract:
Purpose: To determine whether a novel ultrasound imaging
system could detect 25 µm thick cracks beneath gold, silver
amalgam, and porcelain restorations on tooth phantoms.
Methods: Tooth phantoms were constructed using
acoustically-matched composite to simulate dentin, with 25 µm
thick water-filled cracks located ~ 1 mm inside the simulated
dentin. Porcelain and gold restorations were bonded using
resinous cement, and an amalgam restoration was attached using
mechanical retention. A portion of the gold restoration was left
unattached to simulate cement washout. A novel monostatic
pulse-echo ultrasound system with a 19 MHz single-element PLZT
transducer, custom transmit/receive electronics and signal
processing with a Ga-In alloy couplant was used to measure the
relative return echo amplitude from restoration surfaces,
simulated dentin/restoration interfaces, and cracks. Extracted
teeth were also used to demonstrate that the system was capable
of detecting cracks in real teeth. Results: Cracks were
detected beneath porcelain and amalgam, and within a human
molar. Cracks were not detected in simulated dentin beneath
gold; however, simulated cement washout directly beneath gold
was identified. The ability to detect defects in the phantom was
dependent on the acoustic reflection coefficient between
interfaces, the attenuation of each material, acoustic clutter
within the phantom, and geometry. Gold restorations transmitted
minimal acoustic energy due to their large acoustic impedance;
however, the ability to distinguish the gold/cement interface
from the gold/washout interface indicated that ultrasound can
detect density changes immediately below restorations, such as
caries, fractures, or debonding. The ability to penetrate
resin-composite was also demonstrated. (Am J Dent
2007;20:221-226).
Clinical
significance: The ability to detect cracks or cement washout
beneath radiopaque restorations would greatly aid dentists in
diagnosis and in providing appropriate clinical interventions.
Address:
Dr.
Shane N. White, UCLA School of Dentistry, CHS 23-010, Los
Angeles, CA 90095-1668, USA. E-:
snwhite@ucla.edu
Extrinsic stain removal efficacy of a
dual-phase dentifrice
YuCheng Li, dds, Tao He, dds, phd,
Lili Sun, ms, Yuqing Zhang, ms, Xin Li, bs,
Yan Wang, dds,
Shouliang Zhao, dds & RongYin Tang, dds
Abstract:
Purpose: To evaluate the extrinsic stain removal benefit of
a sodium hexametaphosphate containing dual-phase dentifrice
(Crest Vivid White) relative to a marketed negative control
(Colgate Cavity Protection). Methods: This was a parallel
groups, examiner-blind, randomized and controlled clinical
trial. A total of 200 healthy adults with natural stain on their
anterior teeth were enrolled into the study. Following baseline
examination, subjects were randomly assigned to one of the two
treatment groups based on baseline Lobene composite scores,
smoking status (yes/no), tea/coffee consumption (yes/no), and
gender. Subjects brushed twice daily, at least 1 minute every
time over 6 weeks. Clinical examinations including extrinsic
stain evaluation and oral soft tissue examination were conducted
at BL, Weeks 3 and 6. Extrinsic stain removal was evaluated on
the anterior teeth by a dental examiner using Lobene stain
index. Results: Of the 200 subjects who were randomized
to treatment, 195 were available for the 3-week examination and
193 subjects completed the study. The dual-phase dentifrice
exhibited a statistically significant (P< 0.01) reduction in
Lobene stain composite scores when compared to the negative
control dentifrice at Week 6. Adjusted mean Lobene composite
reduction for the dual-phase dentifrice group (0.32) was twice
as big as the negative control group (0.16). Change in Lobene
stain extent (area) contributed primarily to the overall
composite score reduction. All test products were well tolerated
over the 6-week treatment period. (Am J Dent
2007;20:227-230).
Clinical
significance: The research demonstrated the superior
extrinsic stain removal efficacy of the dual-phase dentifrice
relative to a negative control dentifrice.
Address:
Dr. RongYin Tang, College of Stomatology, Fourth
Military Medical University, Xi’an, China. E-:
tangry@fmmu.edu.cn
Effect of adhesive systems and
surface treatment of methacrylate
resin-based fiber posts on post-resin-dentin bonds
Francesca Monticelli,
dds, ms, phd,
Raquel Osorio,
dds, phd,
Alberto Albaladejo,
dds, phd,
Fátima S. Aguilera,
dds, phd,
Franklin R. Tay,
bdsc(hons), fadm, phd,
Marco Ferrari,
md, dds, phd
& Manuel Toledano,
md, dds, phd
Abstract:
Purpose: To evaluate the effect of different fiber post
surface treatments on bond strength. Methods: Extracted
endodontically-treated premolars were prepared for the
cementation of a methacrylate resin-based fiber post (FRC Postec).
The posts received one of the three surface pre-treatments:
silane application; hydrofluoric acid-etching and silane
application or no treatment. A light-cured composite was used
with one of the three dentin adhesives for luting: Single Bond;
Clearfil Photo Bond and Clearfil New Bond, followed by a
light-cured composite core build-up. Specimens were serially
sliced into 0.8 x 0.8 mm-thick beams and loaded in tension until
failure. Results: Significant differences in bond
strengths were recorded among the dentin adhesives (P< 0.05).
However, post pre-treatment did not affect the bonding efficacy
of the adhesives except for Clearfil New Bond. (Am J Dent
2007;20:231-234).
Clinical
significance: Adhesion of luting composites to methacrylate
resin-based fiber posts can be improved by the application of
dentin adhesives. The interface between resin and intraradicular
dentin still remains the weakest bond.
Address:
Prof. Manuel Toledano, Avda. de las Fuerzas Armadas n. 1, 1°B,
18014 Granada, Spain. E-:
toledano@ugr.es
Dental enamel dissolution after
alendronate treatment
Maria G. Gandolfi,
bd, phd,
Cesare Nucci,
md, dds, phd,
Carlo Prati,
md, dds, phd
& Romano Mongiorgi,
ms
Abstract:
Purpose: To evaluate the effect of treatment with a
bisphosphonate (alendronate) on human dental enamel dissolution
in vitro. Methods: The dissolution of each enamel
sample was evaluated by monitoring the calcium release in 0.1M
lactic acid solution at pH 4.5 (acidic solution) during
dissolution tests, after topical alendronate treatment with 0.1M
alendronate solutions at pH 5.0, pH 7.4 and pH 9.0. Results:
Data showed that alendronate treatment, both at pH 5.0 and
pH 7.4, obtained a statistically significant reduction of enamel
demineralization during dissolution test reaction time (45
minutes). The protective effect was not present after treatment
at pH 9. (Am J Dent 2007;20:235-240).
Clinical
significance: Resulting data concerning the reduction of
demineralization in acidic environment suggest the possible
inclusion of alendronate in formulations of oral hygiene
products to prevent enamel demineralization.
Address: Dr. Maria G. Gandolfi, Piazza di
Porta San Donato 1, 40126 Bologna, Italy. E-
mgiovanna.gandolfi@unibo.it
Recovery of genomic DNA from lingual
mucosal cells in sufficient
quantity and quality
Yasuhiro Imamura,
phd,
Syuhei Usui,
dds,
Yuriko Oomori,
dds,
Yoshihisa Fujigaki,
dds,
Norio Ota,
dds, phd
&
Pao-Li Wang,
dds, phd
Abstract: Purpose: To
investigate whether genomic DNA can be purified in sufficient
quantity and quality from the oral cavity. Methods: One
milliliter of peripheral blood and saliva were collected. The
buccal and lingual mucosal cells were also obtained using 10
strokes with a swab or a toothbrush, respectively. All materials
were centrifuged and the cells were lysed by adding sodium
dodecyl-sulfate and proteinase K. The DNAs were extracted with
phenol and precipitated with ethanol followed by
electrophoresing on 0.8% agarose gel. The purified DNAs were
digested with restriction enzyme Dpn I and Mbo I, respectively.
Amplification of the IL-1A gene by PCR was carried out using the
purified DNAs and electrophoresing on polyacrylamide gel.
Results: DNA was obtained from lingual mucosal cells
collected with a toothbrush. Only about one-thirtieth of the
recovered DNA was of non-human origin (bacterial contaminants
from the oral cavity). Judging from the PCR amplifications of
the IL-1A gene, the DNA extracted from lingual cells was of
sufficient quality, in all respects indistinguishable from the
DNAs extracted from the other specimen, such as peripheral
blood, saliva and buccal mucosal cells collected with a swab,
and in sufficient quantity. Our results indicate that it is
possible to purify DNAs from lingual mucosal cells collected
with a toothbrush in a simple and safe manner. Compared to DNA
samples from patients by blood extraction, the described method
also had the advantage of being painless and not inducing mental
distress. (Am J Dent 2007;20:241-245).
Clinical significance: To obtain
genomic DNAs from subjects will be very important for analyzing
single nucleotide polymorphisms and gene diagnosis. Purification
of the DNA by this method can be performed simply and safely at
chair side, without mental distress or bodily pain for subjects.
Address: Prof. Pao-Li Wang, Department of Pharmacology,
Matsumoto Dental University, 1780 Gohbara, Hiro-oka, Shiojiri-city,
Nagano 399-0781, Japan. E-:
ohhourei@po.mdu.ac.jp
Effect of bleaching on the cemento-enamel
junction
Roberta Esberard,
dds, msc,
Renata R. Esberard,
dds,
Roberto M. Esberard,
dds, phd,
Alberto Consolaro,
dds, phd
& Cornelis H. Pameijer,
dmd,mscd, dsc, phd
Abstract: Purpose: To
evaluate the effect of various bleaching agents on the cemento-enamel
junction (CEJ) of human teeth by scanning electron microscopy (SEM)
analysis. Methods: 30 intact teeth were selected and
longitudinally sectioned, yielding 60 specimens. Thirty
specimens served as controls; the other 30 were divided into six
groups with five specimens each (n= 5) and bleached according to
six protocols (Group 1: External bleaching with 10% carbamide
peroxide; Group 2: External bleaching with 35% hydrogen
peroxide; Group 3: External bleaching with 35% hydrogen
peroxide; Group 4: Internal/external bleaching with 35% hydrogen
peroxide; Group 5: Internal/external bleaching with 35% hydrogen
peroxide; and Group 6: Intracoronal bleaching with a paste of
sodium perborate mixed with 9% hydrogen peroxide). After
treatment the specimens were prepared and examined in a scanning
electron microscope. Results: The bleaching agents used
in this study caused morphological changes in the CEJ and
increased dentin exposure. (Am J Dent 2007;20:245-249).
Clinical significance: Depending on
the type of bleaching agent, there appears to be an effect on
the CEJ when extracted teeth are exposed to various external and
internal bleaching protocols. This information may be helpful to
explain post-bleaching sensitivity symptoms.
Address: Dr. Roberta Esberard, Department of Pathology,
Bauru Dental School, University of Săo Paulo, Al. Octávio
Pinheiro Brisola, 9-75, Bauru , SP - 17012-901, Brazil.
E-:
roesberard@hotmail.com
Influence of thermal and mechanical
load cycling on the microtensile
bond strength of self-etching adhesives
Ali I. Abdalla,
dds, phd,
Ahmed A. El Zohairy,
dds, phd,
Moustafa M.N. Aboushelib,
dds
&
Albert J. Feilzer,
dds, phd
Abstract:
Purpose: To evaluate the influence of thermal and mechanical
load cycling on the microtensile dentin bond strength of two
self-etching and one total-etch adhesives. Methods: The
adhesive materials were: a two-step self-etch adhesive (Clearfil
SE Bond), a one-step self-etch adhesive (Hybrid Bond), and a
total-etch one-step adhesive (Admira Bond). Sixty freshly
extracted human third molars were used. In each tooth, a Class I
cavity (4 x 4 mm) was prepared in the occlusal surface with the
pulpal floor extending about 1 mm into dentin. The teeth were
divided into three groups (n=20). Each group was restored with
the resin composite Clearfil APX using one of the adhesives.
After restoration, 10 teeth in each group were thermocycled
between 5şC and 55şC, (dwell time 3 minutes, 5,000 cycles). The
same teeth were then mounted in a fatigue loading machine to
receive an intermittent load of 125 N at 52 cycles/minute for
4,000 cycles. Subsequently, each tooth was sectioned
longitudinally, bucco-lingually and mesio-distally to get
rectangular slabs 1–1.2 mm in thickness for the microtensile
test. Each slab was then placed in a universal testing machine
and tensile load was applied at a cross-head speed of 0.05
mm/minute. Results: Without loading procedures, there was
no significant difference in the bond strength of the tested
adhesives. In contrast to Admira Bond and Clearfil SE Bond,
fatigue loading resulted in a significant reduction of the bond
strength for Hybrid Bond when compared to the unloaded
restorations. (Am J Dent 2007;20:250-254).
Clinical
significance: The total-etch and the two-step self-etch
adhesives used in this study showed better tolerance to thermal
and mechanical loading compared to the one-step self-etch
system.
Address:
Dr. Ali I. Abdalla, Department of Restorative Dentistry, Faculty
of Dentistry, University of Tanta, Tanta, Egypt. E-:
aliebraheem01@yahoo.com
Effect of LED curing modes on the
microleakage of a pit and fissure sealant
Adil Nalçacı,
dds, phd,
Nuran Ulusoy,
dds, phd
& Çiğdem Küçükeşmen,
dds, phd
Abstract: Purpose: To evaluate in vitro the
curing effect of a very high intensity light-emitting diode
(LED) unit and a conventional LED unit (including “soft-start”
modes) on the microleakage of a pit and fissure sealant.
Methods: 120 intact caries-free human molars were randomly
divided into six groups (n=20), sealed with Fissurit-F and
polymerized using either a conventional halogen unit (Optilux)
(Control group) in standard mode (40 seconds @ 600 mW/cm2);
a very high intensity LED unit (Mini LED) in fast (10 seconds @
1,100 mW/cm2)
or soft-start mode (pulse mode: ten 1-second flashes @ 1,100 mW/cm2;
exponential mode: exponential increase from 0 to 1,100 mW/cm2
within 10 seconds followed by 10 seconds @1,100 mW/cm2);
or a conventional LED unit (Elipar Freelight) in standard (40
seconds @ 400 mW/cm2)
or exponential mode (exponential increase from 0 to 400mW/cm2
within 12 seconds followed by 28 seconds @ 400 mW/cm2).
Restored specimens were stored in distilled water at 37°C for 24
hours. Specimens were then immersed in a 0.5% fuchsin dye
solution for 24 hours, with half of the specimens from each
group subjected to thermocycling (5/55°C; x1000) prior to dye
immersion. After removal from the dye solution, specimens were
sectioned and the degree of dye penetration scored. Data was
statistically analyzed using the Kruskal-Wallis H test and the
Mann-Whitney U-test (P< 0.05). Results: There was no
statistically significant difference in microleakage of pit and
fissure sealant polymerized using various curing techniques.
Thermocycling regimens had no effect on either LED- or
halogen-cured specimens. (Am J Dent 2007;20:255-258).
Clinical
significance: High-power LED lights are an effective means
of providing a strong marginal seal with pit and fissure
sealants and may therefore be preferred for the overall time
savings as well as reduced chair time.
Address:
Dr. Adil Nalçacı, Kennedy Caddesi, 23/1, 06680, Kavaklıdere,
Ankara, Turkey. E-:
analcaci@dentistry.ankara.edu.tr
Microtensile bond strength of
self-etching adhesive systems to
differently prepared dentin
Benyarat Pangsrisomboon,
dds,
Choltacha Harnirattisai,
dds, phd,
Kanitha Nilsri,
dds
& Michael F. Burrow,
bds, mds, phd
Abstract: Purpose: To evaluate the microtensile bond
strength (µTBS) of three self-etching adhesive systems with
different degrees of acidity (Clearfil SE Bond, One-Up Bond F,
and Xeno III) to dentin prepared with three different methods.
Methods: Forty-five extracted human third molars were
ground flat to expose occlusal dentin and polished with 600-grit
abrasive paper. All teeth were randomly divided into three
groups according to the preparation method: baseline surface
(AP#600), steel fissure bur (SB) and regular grit diamond bur
(DB). Dentin surfaces were bonded with one of the three
adhesive systems; then resin composite was incrementally built
up. After storage in 37°C water for 24 hours, specimens were cut
and trimmed to create an hourglass shape with cross sectional
area of approximate 1 mm2.
All specimens were subjected to microtensile bond strength
testing. The bond strength data were analyzed with one and
two-way ANOVA and Dunnett Multiple comparisons test at P< 0.05.
Results: For Xeno III and One-Up Bond F, the µTBS to
dentin prepared with the different methods were not
significantly different. However, the µTBS of Clearfil SE Bond
to dentin prepared with the diamond bur was significantly lower
than the other preparation methods. Xeno III produced the lowest
µTBS that were statistically different from the other adhesive
systems when each preparation method was compared (P< 0.01). SEM
observation of the prepared dentin surfaces showed that the
diamond bur group produced a thicker smear layer that followed
by steel bur and 600-grit paper. Therefore, the smear layer from
diamond burs had a greater influence in decreasing µTBS of
Clearfil SE Bond that has the weakest acidity self-etching
adhesive systems evaluated. (Am J Dent 2007;20:259-262).
Clinical
significance: When using the self-etching adhesive system
tested to bond to dentin, a higher bond strength was obtained
when the dentin surface was prepared using steel bur which
produced a thinner smear layer compared with that of a diamond
bur.
Address:
Dr. Choltacha Harnirattisai, Department of Operative Dentistry,
Faculty of Dentistry, Mahidol University, 6 Yothee Road,
Rajthewee, Bangkok 10400, Thailand. E-:
dtchn@mahidol.ac.th
Quality of curing in relation to hardness,
degree of cure and
polymerization depth measured on a nano-hybrid composite
Nicoleta Ilie,
grad
eng, dr rer hum biol &
Reinhard Hickel,
dds, prof
dr med dent
Abstract:
Purpose: To analyze the curing behavior and the curing
quality of a nano-hybrid composite material (Tetric EvoCeram) in
relation to degree of cure, variation of hardness with depth and
polymerization depth. Methods: The composite was
evaluated after polymerizing the material with 13 different
curing regimens of two LED devices and one halogen curing unit
by assessing in real time the degree of cure at depths of 2 and
6 mm, the variation of hardness with depth and the
polymerization depth. The sample preparation simulated the
clinical incremental technique as well as a bulk fill procedure.
Results: No correlation was found for the tested curing
regimens between polymerization depth and surface hardness
respectively between surface hardness and radiant exposure,
whereas the polymerization depth was strongly dependent on
polymerization time and radiant exposure. It can be therefore
concluded that the surface hardness is not a reliable indicator
of the quality of curing. The degree of cure was strongly
influenced by depth and curing time, whereas the influence of
the curing regimen and of the interaction products between these
three factors was low. The higher effect on the variation of the
Vickers hardness, measured 24 hours after polymerization, was
exercised also by the depth, followed by curing regimen and
curing time. (Am J Dent
2007;20:263-268).
Clinical
significance: The increase of polymerization time
considerably improved the polymerization depth for all curing
units without changing the surface hardness. Considering a short
polymerization time (10 seconds), the highest depth of cure was
reached by using the warmer halogen curing unit and the pulse
program of a LED curing unit, whereas the polymerization depth
after curing with the other units did not exceed 2.5 mm. An
incremental reconstruction will be necessary for deeper
cavities. Extending the polymerization time (40 seconds), layers
up to 5.2 mm were cured, however, a potential increase of
shrinkage stress at the interfaces in a clinical situation must
be taken into consideration.
Address:
Dr. Nicoleta Ilie, Department of Restorative Dentistry, Dental
School of the Ludwig-Maximilians-University, Goethestr. 70,
80336 Munich, Germany. E-:
nicoleta.ilie@dent.med.uni-muenchen.de
Effect of post-retained composite
restorations and amount of coronal
residual structure on the fracture resistance of
endodontically-treated teeth
Roberto Sorrentino,
dds, phd,
Francesca Monticelli,
dds, phd,
Cecilia Goracci,
dds, phD,
Fernando Zarone,
md, dds,
Franklin R. Tay,
bdsc
(Hons), fadm, phd,
Franklin García-Godoy,
dds, ms
& Marco Ferrari,
dds, phd
Abstract:
Purpose: To compare the fracture resistance and failure
patterns of endodontically-treated teeth with a progressively
reduced number of residual walls restored using resin
composites, with or without translucent glass fiber posts.
Methods: Ninety extracted human single-rooted maxillary
premolars were used. After endodontic treatment, the following
groups were created: Group 1 (control group): endodontically-treated
single-rooted maxillary premolars with four residual walls;
Group 2: three residual walls; Group 3: two residual walls;
Group 4: one residual wall, and Group 5: no residual wall.
Groups 2-5 were each divided into two subgroups: subgroups “a”
were restored with resin composites, while subgroups “b” were
restored with translucent glass fiber posts and resin
composites. Static fracture resistance tests and statistical
analyses (P= 0.05) were performed. Results: The mean
failure loads (N) were 502.4±152.5 (Group 1), 416.4±122.2 (Group
2a), 423.0±103.3 (Group 2b) 422.1±138.9 (Group 3a) 513.2±121.7
(Group 3b), 488.7±153.7 (Group 4a) 573.4±169.2 (Group 4b),
856.7±112.2 (Group 5a) and 649.5±163.5 (Group 5b), respectively.
The samples restored with fiber posts exhibited predominantly
restorable fractures. The number of residual cavity walls
influenced the mechanical resistance of endodontically-treated
teeth. (Am J Dent 2007;20:269-274).
Clinical
significance: The results of the present study would allow
clinicians to make an informed choice from among available
materials to restore endodontically-treated teeth, in order to
decide in which clinical situations it would be advisable to use
fiber posts.
Address: Prof. Marco Ferrari, Department of Dental Sciences,
School of Dental Medicine, University of Siena, Policlinico Le
Scotte, Viale Bracci, 53100 Siena, Italy. E-:
ferrarimar@unisi.it
Extent of polymerization of dental
bonding systems on bleached enamel
Lorenzo Breschi,
dds, phd,
Milena Cadenaro,
dds, phd,
Francesca Antoniolli,
DEng,
Erika Visintini,
dds,
Manuel Toledano,
dds, phd
& Roberto Di Lenarda,
dds, phd
Abstract:
Purpose: To analyze the extent of polymerization of four
adhesive systems on whitened enamel immediately after bonding or
delayed for 24 hours and 2 weeks. The effect of prolonged
light-curing was also analyzed. Methods: One adhesive of
each class was investigated: Adper Scotchbond Multi-Purpose
(three-step etch-and-rinse), One-Step (two-step etch-and-rinse),
Clearfil Protect Bond (two-step self-etching) and Xeno III
(one-step self-etching). Enamel fragments were treated with
Opalescence Xtra Boost for 30 minutes, powdered and pressed into
aluminum pans. Specimens were bonded immediately after
bleaching, after 24 hours or after 14 days of storage in 100%
humidity at 37°C. Unbleached enamel powder was prepared as
control. Extent of polymerization of bonded interfaces was
obtained with differential scanning calorimetry (DSC) at 20, 40
and 60 seconds and data were statistically analyzed with 3-way
ANOVA and Tukey’s post-hoc test. Results: The extent of
polymerization obtained from DSC exotherms of adhesives applied
immediately after bleaching was significantly lower compared to
controls. Increased extent of polymerization after storage was
confirmed for all adhesives and no difference with controls was
found after 14 days. Prolonged irradiation time increased curing
rate for all the tested adhesives. This study supported the
hypothesis that polymerization of the adhesive is reduced after
enamel bleaching and delayed adhesive application reverses the
polymerization inhibition. Prolonged polymerization intervals
may counteract the inhibition of polymerization due to the
bleaching procedure; nevertheless further clinical studies
should validate this hypothesis. (Am J Dent
2007;20:275-280).
Clinical
significance: This in vitro study supported the
hypothesis that adhesive restorations should not be performed
immediately after enamel bleaching and that dental adhesives
should be polymerized for longer curing times than those
recommended by manufacturers.
Address: Prof. Lorenzo Breschi, Division of Dental Sciences
and Biomaterials, Department of Biomedicine, University of
Trieste, Via Stuparich 1, 34129 Trieste, Italy. E-:
lbreschi@units.it |
