February 2010
Research Article
Effect of cigarette
smoke and whiskey on the color stability of dental composites
Mariana de Souza AraÚjo Wasilewski, dds,
mds, Marcos Kenzo Takahashi, dds, mds, phd,
Giovanna Andraus Kirsten, dds, mds & Evelise Machado de Souza, dds, mds, phd
Abstract: Purpose: To evaluate
the effect of cigarette smoke and whiskey on the color stability of resin
composites. Methods: Disk-shaped
specimens (8 mm x 1 mm) were prepared with five composites in two different shades
(n=10). After light-curing, the specimens were stored in dark containers with
artificial saliva at 37ºC for 24 hours. Baseline color was measured by
CIEL*a*b* using a colorimeter (Easy-Shade, VITA). Half of the specimens were
subjected to a discoloration process in a cigarette smoking machine (SM) and
the other half to an immersion in whiskey (WH) for 24 hours. Another color
measurement was performed for discolored specimens. The samples subjected to
smoking were immersed in whiskey (SM/WH) and those subjected to whiskey
immersion were subjected to cigarette smoking (WH/SM) followed by another color
measurement. Color changes (∆E*) were calculated and submitted to
repeated measures 4-way ANOVA and Tukey tests (P< 0.05). Results: The most significant color
change was observed after WH/SM (∆E*= 22.8-31.5) discoloration process,
followed by SM (∆E*= 7.0-18.0), SM/WH (∆E*= 4.9-16.5) and WH
(∆E*= 2.0 to 9.5). Translucent shades were more susceptible to
discoloration than enamel shades. All the groups, with the exception of two,
showed a significantly high perceptible color change (∆E*> 3.3). Based
on the results, the color stability of dental composites was affected by the
discoloration process and was material and shade dependent. (Am J Dent 2010;23:4-8).
Clinical significance: Resin composites are
susceptible to discoloration by oral habits such as cigarette smoking and
alcoholic beverage drinking. This in
vitro study suggested that the association of both habits can exacerbate
the color changes of composites, mainly when translucent shades are used.
Address: Dr. Evelise Machado de Souza,
School of Dentistry, Post-graduate Program, Pontifical Catholic University of
Parana, R. Imaculada Conçeicão, 1155, Prado Velho Curitiba, PR, 80215-901,
Research Article
Prevalence and severity of gingivitis in
American adults
Yiming Li, dds,
msd, phd, Sean Lee, dds, Philippe Hujoel, dmd, phd, Mingfang Su, dds, ms, Wu Zhang, md,
Abstract: Purpose: To
investigate prevalence and severity of gingivitis in representative American
adults. Methods: Subjects (1,000) in
Loma Linda, California; Seattle, Washington; and Boston, Massachusetts were
examined for Löe-Silness Gingivitis Index (GI). Mann-Whitney rank sum test was
used to determine significances in the GI between genders. The data among study
sites and races were compared using the Kruskal-Wallis one-way ANOVA on ranks.
The correlation of the GI and age was examined by the Spearman rank order
correlation. Age differences among three sites were analyzed using the one-way
ANOVA. Results: The race composition
of the subjects (mean age 37.9) approximated to the 2004 U.S. Census data. The
overall average GI was 1.055. Only 6.1% of subjects showed mean GI <0.50;
most (93.9%) were ≥ 0.50, with 55.7% ≥ 1.00. There was a
significant correlation (P< 0.001) between the age and GI. The males’ GI was
significantly higher (P< 0.001) than the females’; African-Americans showed
a significantly higher GI (P< 0.05) than other races except for the
Native-Americans. (Am J Dent 2010;23:9-13).
Clinical
significance: The average GI in adults recruited in three cities is slightly ≥1.0; age,
gender, race and subject source can influence the prevalence and severity of
gingivitis. For gingivitis studies, proper subject source, age, gender and race
compositions need to be considered for recruiting a representative study
population.
Address:
Dr. Yiming Li, Center for Dental Research, Loma Linda University School of
Dentistry, 24876 Taylor Street, Loma Linda, CA 92350, USA. E-mail:
yli@llu.edu
Research Article
The effect of curing mode on extent of
polymerization and microhardness of dual-cured, self-adhesive resin cements
Milena Cadenaro, dds, phd, Chiara Ottavia Navarra, dds, phd, Francesca Antoniolli, eng, phd,
Annalisa Mazzoni, dds, phd, Roberto Di Lenarda, dds, Frederick Allen Rueggeberg, dmd, ms
& Lorenzo Breschi, dds, phd
Abstract: Purpose: To compare
the effect of curing mode (self- or light-cure) on the extent of polymerization
(%EPl as measured using differential scanning calorimetry, (DSC) and
microhardness of two dual-cured, self-adhesive resin cements, using a conventional,
dual-cured resin cement as control. Methods: Small amounts of the commercial self-adhesive cements Maxcem and RelyX Unicem
or Panavia F2.0 dual-cure resin based cement used as control were polymerized
within the DSC chamber at 35°C under a nitrogen atmosphere. 10 specimens were
light-cured immediately (20 seconds, 600 mW/cm2) and left
undisturbed for 2 hours and 10 additional specimens were left to self-cure in
the dark for 2 hours. Following DSC treatment, microhardness of the specimens
was measured (Vickers). For each test parameter, data were analyzed with a
two-way ANOVA and the Tukey post hoc test. Results: %EP and microhardness
of all cements were higher when the light-cure mode of dual-activation was used
(P< 0.05) instead of only self-curing. No significant difference in %EP was
found between either self-adhesive cement or the control using either the
light- or self-curing modes. In the light-activated mode, the conventional,
dual-cure control cement demonstrated lower microhardness than the self-adhesive
cements (P< 0.05). (Am J Dent 2010;23:14-18).
Clinical
significance: Dual-cured,
self adhesive resin cements showed an extent of polymerization comparable to
the conventional, dual-cured resin cement tested.
Address:
Prof. Lorenzo Breschi, Department of Biomedicine, Unit of Dental Sciences and
Biomaterials, University of Trieste, Piazza Ospedale 1, I-34129 Trieste, Italy. E-mail: lbreschi@units.it
Research Article
Effect of hydrogen peroxide on
microhardness and color change of resin nanocomposites
Yong Hoon Kwon, phd, Dong-Hee Shin, dds, ms, Dong-In Yun, dds, ms, Young-Joon Heo, dds,
Hyo-Joung Seol, phd & Hyung-Il Kim, dds, phd
Abstract: Purpose: To examine
the effect of hydrogen peroxide on the microhardness and color change of resin composites
containing nanofillers. Methods: Three resin nanocomposites with three different shades and two different tooth
whitening agents were used. The specimens were given a 3-week treatment with
one of three protocols: (1) 7 hours/day treatment of carbamide peroxide (CP) +
17 hours/day immersion in distilled water (DW); (2) 1 hour/week treatment of
hydrogen peroxide (HP) + immersion in DW for the rest of the week; and (3)
immersion in DW for 24 hours/day. The microhardness and color changes were
measured after treatment. Results: After treatment with the whitening agents, there was an 8.1~10.7% decrease in
the original microhardness. These values were similar to those obtained from
the samples treated with distilled water. In the same resin product, the
decrease was similar regardless of the test agents used. In most cases, the
color change was only slight (ΔE*=0.5~1.4). Hydrogen peroxide enhanced the
color change but the absolute color change values were similar in the same
product and shade, regardless of the test agent used. (Am J Dent 2010;23:19-22).
Clinical
significance: Within the
limits of this study, carbamide peroxide and hydrogen peroxide had no
additional effect on the microhardness and color change of resin nanocomposites
compared with the samples treated with distilled water.
Address:
Prof. Yong Hoon Kwon, Department of Dental Materials, School of Dentistry,
Pusan National University, Yangsan 626-870, Korea. E-mail: y0k0916@pusan.ac.kr
Research Article
Microtensile bond
strength of etch-and-rinse and self-etch adhesive systems to demineralized dentin after the use of a papain-based chemomechanical method
Renato JosÈ Gianini, dds, FlÁvia
Lucisano Botelho do Amaral, dds, ms, FlÁvia MartÃo FlÓrio, dds, ms, scd
Abstract: Purpose: To evaluate
the in vitro microtensile bond
strength (µTBS) of etch-and-rinse and self-etch adhesive systems to
demineralized dentin after the use of a papain-based chemomechanical method. Methods: 36 demineralized human dentin
slabs were randomly distributed into two groups according to the method of
caries removal: (1). Mechanical removal with manual excavators; (2)
Chemomechanical removal with a papain-based gel (Papacárie). Subsequently,
three adhesive systems were applied (n=6): (a) an etch-and-rinse adhesive
system (Single Bond); (b) a two-step self-etch adhesive system (AdheSE); (c) a
one-step self-etch adhesive system (Adper Prompt). The slabs were restored with
a microhybrid resin composite and each resin-dentin block was sectioned into
1.0 mm2 thick slabs, which were kept in receptacles containing
distilled water at relative humidity, for 24 hours, at 37°C. After that, they
were subjected to tensile stress in a universal testing machine at a speed of
0.5 mm/minute. Data were submitted to two-way ANOVA and Tukey’s test at a 0.05
level of significance. The fractured specimens were observed under a stereomicroscope
to assess the failure mode. Results: The application of both chemomechanical and mechanical methods on demineralized
dentin yielded µTBS values that were statistically similar among them,
regardless of the adhesive system used. Caries removal with a chemomechanical
papain-based method did not interfere in the adhesion of the tested adhesive
systems to demineralized dentin. (Am J
Dent 2010;23:23-28).
Clinical significance: The use of a papain-based
chemomechanical method for caries removal did not affect the adhesion of
etch-and-rinse and self-etch adhesives to demineralized dentin.
Address: Prof. Dr. Roberta Tarkany
Basting, Faculty of Dentistry and Center for Dental Research São Leopoldo
Mandic, Department of Restorative Dentistry - Operative, Rua José Rocha
Junqueira, 13 Bairro Swift, Campinas, SP, CEP: 13045-755, Brazil. E-mail: rbasting@yahoo.com
Research Article
Effect of long-term water aging on
microtensile bond strength of self-etch adhesives to dentin
Ali I. Abdalla, phd
Abstract: Purpose: To evaluate
the effect of water storage on the microtensile dentin bond strength of one
total-etch and four self-etching adhesives to dentin. Methods: The adhesive materials were: one total-etch adhesive (Admira
Bond) and four self-etch adhesives (Clearfil S tri Bond, Hybrid Bond,
Futurabond NR, Adhe SE). Freshly extracted human third molar teeth were used.
For each tooth, dentin was exposed on the occlusal surface by cutting with an
Isomet saw and the remaining part was mounted in a plastic ring using dental
stone. After adhesive application, a composite resin (Grandio) was placed in
5-6 mm height to form a crown segment. For each tested adhesive, two test
procedures (n=6 teeth) were carried out. Procedure A: the teeth were stored in
water for 24 hours, and then sectioned longitudinally, buccolingually and
mesiodistally to get rectangular beams of 1 ± 0.1 mm thickness on which a
micro-tensile test was carried out. Procedure B: The specimens were stored in
water at 37°C for 3 years before sectioning and microtensile testing. During
microtensile testing the beams were placed in a universal testing machine and
load was applied at cross-head speed of 0.5 mm/minute. Results: For the 24-hour water storage groups, there was no
significant difference in the bond strength between the different adhesives.
After 3 years of water storage, the bond strength of all self-etch adhesives
was significantly reduced compared to the control groups (24 hours). In contrast,
the bond strength of Admira Bond was not significantly reduced. (Am J Dent 2010;23:29-33).
Clinical significance: Water storage for 3 years
significantly reduced the bond strength of tested self-etch adhesives to
dentin. The bond produced by the total-etch system was able to resist 3-year
water degradation.
Address: Dr. Ali I. Abdalla,
Department of Restorative Dentistry, Faculty of Dentistry, University of Tanta,
Tanta, Egypt. E-mail: ali_abdalla79@yahoo.com
Research Article
Indirect pulp treatment in primary teeth: 4-year
results
Luciano Casagrande, dds,ms, phd, LetÍcia Westphalen Bento, dds,
ms, DÉbora Martini Dalpian,dds, ms
Abstract: Purpose: To evaluate clinical and
radiographic outcomes of indirect pulp treatment (IPT) in primary molars after
long-term function (up to 60 months). Methods: Teeth with deep carious lesions without signs and symptoms of irreversible
pulpitis were divided by random allocation into two groups, according to the
capping material utilized over demineralized dentin: experimental group (1):
self-etching adhesive system (Clearfil SE Bond); and control group (2): calcium
hydroxide liner (Dycal). Both groups were filled with resin composite (Z250)
and submitted to a clinical and radiographic monitoring period until
exfoliation. Results: After the
follow-up period (up to 60 months), no statistical difference was found between
groups (P= 0.514). The overall success rate reached 78%. The failures occurred
after the first year period recall. (Am J
Dent 2010;23:34-38).
Clinical significance: The IPT provides an alternative
treatment of primary teeth with deep carious lesions representing a simple and
effective technique to maintain the pulp vitality.
Address: Dr. Luciano Casagrande, School
of Dentistry, Franciscan University Center (UNIFRA), Andradas 1614, Santa
Maria, RS 97010 032, Brazil. E-mail: lucianocasagrande@hotmail.com
Research Article
Effect of staining solutions on
discoloration of resin nanocomposites
Jeong-Kil Park, dds, phd, Tae-Hyong
Kim, dds, ms, Ching-Chang Ko, dds, phd, Franklin García-Godoy, dds, ms,
Abstract: Purpose: To examine
the effect of staining solutions on the discoloration of resin nanocomposites. Methods: Three resin nanocomposites
(Ceram X, Grandio, and Filtek Z350) were light cured for 40 seconds at a light
intensity of 1000 mW/cm2. The color of the specimens was measured in
%R (reflectance) mode before and after immersing the specimens in four
different test solutions [distilled water (DW), coffee (CF), 50% ethanol (50ET)
and brewed green tea (GT)] for 7 hours/day over a 3-week period. The color
difference (ΔE*) was obtained based on the CIEL*a*b* color coordinate
values. Results: The specimens
immersed in DW, 50ET and GT showed a slight increase in L* value. However, the
samples immersed in CF showed a decrease in the L* value and an increase in the
b* value. CF induced a significant color change (ΔE*: 3.1~5.6) in most
specimens but the other solutions induced only a slight color change. Overall,
coffee caused unacceptable color changes to the resin nanocomposites. (Am J Dent 2010;23:39-42).
Clinical
significance: Within the limits of this study, coffee can induce an unacceptable color change
in resin nanocomposites if used regularly for a long time.
Address:
Prof. Yong Hoon Kwon, Department of Dental Materials, School of Dentistry,
Pusan National University, Yangsan 626-870, Korea. E-mail: y0k0916@pusan.ac.kr
Research Article
Push-out strength of modified Portland
cements and resins
Francesco
Iacono, dds, ms, Maria
Giovanna Gandolfi, mbiol, dsc, mbio, phd, Bradford Huffman, bs,
Carlo
Prati, md, dds, phd & David
Pashley, dmd, phd
Abstract: Purpose: Modified
calcium-silicate cements derived from white Portland cement (PC) were
formulated to test their push-out strength from radicular dentin after
immersion for 1 month. Methods: Slabs obtained from 42 single-rooted extracted teeth were prepared with
Clinical significance: Incorporation of
phyllosilicate in the experimental
Address:
Dr. Francesco Iacono, Department of Oral Sciences, Alma Mater Studiorum,
University of Bologna, Via San Vitale 59, 40125 Bologna, Italy. E-mail: francesco.iacono@hotmail.it
Research Article
Resistance to degradation of bonded restorations to
simulated caries-affected primary dentin
Marcela Marquezan, dds,
ms, phd, Raquel Osorio, dds, ms, phd, Ana Lidia Ciamponi, dds, ms, phd
& Manuel
Toledano,
Abstract: Purpose: To investigate the resistance to degradation of resin
modified glass-ionomer cement (RMGIC) and adhesive/composite restorations in
sound and simulated caries-affected dentin of primary teeth subjected to
carious challenge using a pH-cycling model and load-cycling, by means of a
microtensile test. Methods: Occlusal
cavities were prepared in 60 sound exfoliated primary second molars. Half the
specimens were submitted to pH-cycling to induce simulated caries lesion. The
teeth were randomly restored with one of the two materials: (1) a RMGIC
(Vitremer) and (2) a total-etch adhesive system (Adper Single Bond 2) followed
by resin composite (Filtek Z100). After storage in distilled water at
Clinical significance: The use of Vitremer (RMGIC) is
encouraged for pediatric patients with caries activity, since it satisfactorily
bonded to simulated caries-affected dentin and resisted caries challenge.
Address:
Dr. Raquel Osorio, Avda. de las Fuerzas Armadas 1, 1B, 18014 Granada,
Spain. E-mail: toledano@ugr.es
Research Article
The occlusal precision of laboratory versus CAD/CAM
processed
all-ceramic crowns
Sven Reich, priv-doz, dr med dent, Beate Brungsberg, dentist, Hubertus Teschner, dentist
& Roland Frankenberger, prof, dr med dent
Abstract: Purpose: The null
hypothesis was tested: There is no difference between two all-ceramic crown
systems, the Cerec method (CHAIR) and the IPS Empress method (LAB), with
respect to occlusal precision and time expenditure for the dentist. Methods: 20 casts representing clinical
situations were mounted in semi-adjustable articulators to serve as simulation
models. The left lower first molars were prepared to receive feldspathic
ceramic crowns. The minimum number of three (Min3) occlusal contacts and their
desired location was defined on each crown before preparation. Two crowns were
produced on each die: (CHAIR) was applied in order to simulate a chair-side
treatment and [LAB] was applied to simulate the laboratory/clinical mode of
production. Additionally the time required to perform the occlusal adjustment
was measured. For occlusal analysis, the (Min3) were divided by the contacts
that were “actually achieved” (ACT). Mean quotients for (LAB) and (CHAIR) were
calculated (n = 20 each). The Wilcoxon signed rank test at P≤ 0.05 was
applied to determine statistical significance. Results: The mean quotients MEAN QU (Min3)/(ACT) of 0.87 for
(CHAIR) and 0.94 for (LAB) and the time expenditure for simulating intraoral
occlusal adjustment of 3.44 minutes for (CHAIR) and 3.79 minutes for (LAB) did
not differ significantly. (Am J Dent 2010;23:53-56).
Clinical significance: The clinical simulation showed
that it was possible to achieve satisfactory occlusal precision either by the
use of the conventional laboratory (LAB) and the CAD/CAM (CHAIR) method within
similar time expenditure.
Address: Priv.-Doz. Dr. Sven Reich, Department of
Prosthodontics and Dental Materials, Medical Faculty, RWTH Aachen University,
Pauwelsstrasse 30, D-52074 Aachen, Germany. E-mail: sreich@ukaachen.de
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