Research Article
Digital image color analysis compared to direct
dental CIE colorimeter
assessment under different ambient conditions
Michael KnÖsel, dr med dent, Rengin Attin, dr med dent, Klaus Jung, dr Rer Nat, Edgar Brunner, prof dr Rer Nat, Dietmar Kubein-Meesenburg, prof dr med dent & Thomas Attin, prof dr med dent
Abstract: Purposes: To evaluate the concordance and repeatability of two in vivo methods for dental color assessment
and to clarify the influence of different ambient light conditions and
subject’s head position on the assessed color variables. Methods: Color assessments were performed by two examiners on 16
arbitrarily selected subjects under two different, standardized conditions of
illumination and at two different standardized head angulations. CIE (L*a*b*)
data for upper and lower central incisors were recorded in two different ways:
(1) by an intra-oral contact dental colorimeter and (2) by processing digital
images for performing color calculation using Adobe Photoshop software. The
influence of the different ambient conditions on both methods, as well as the
concordance of measurements was analyzed statistically using several mixed
linear models. Results: Ambient
light as a single factor had no significant influence on maxillary L*, a* and
b* values, but it did have an effect on mandible assessments. Head angulation variation resulted in significant L* value
differences using the photo method. The operator had a significant influence on
values a* and b* for the photo method and on a* values for the colorimeter
method. In fully lit ambient condition, the operator had a significant
influence on the segregated L*, a*, and b* values. With dimmed lights, head angulation became significant, but not the operator.
Evaluation of segregated L* values was error prone in both methods. Comparing
both methods, DE values did not exceed 2.85
units, indicating that color differences between methods and recorded under
varying ambient conditions were well below the sensitivity of the naked eye. (Am J Dent 2009;22:67-72).
Clinical significance: Both methods were appropriate
for clinical color assessment and their accuracy exceeded visual control.
Slight changes in ambient light did not affect upper
incisor color assessment, but were more critical when lower incisors were the
objective. Especially in half-lit ambient conditions, additional variations in
head angulations must be avoided, to maintain measurement reliability.
*: Dr. Michael Knösel, University of Göttingen, Center of Dentistry, Department of Orthodontics, Robert-Koch-Str. 40, 37099 Göttingen, Germany. E-*: mknoesel@yahoo.de
Research Article
Color difference
of all-ceramic materials by the change of illuminants
Bin Yu, mche & Yong-Keun Lee, dds, phd
Abstract: Purpose: To
determine the differences in color and color parameters (lightness, chroma and hue) of simulated layered all-ceramic specimens
at a clinically relevant thickness under three CIE standard illuminants. Methods: Seven all-ceramic core
materials of A2-corresponding shade, one sintering ceramic and one alloy core
as references were prepared in clinically relevant thicknesses (0.4 to
Clinical
significance: Color
difference of all-ceramics by the change of illuminants was higher than that of
natural dentin, and also was higher than the clinically perceptible level
(∆E*ab >3.7) in several
conditions. Therefore, these color discrepancies by the change of illuminants
should be considered in clinical shade matching, and shade matching should be
performed under the light most clinically relevant.
*: Dr. Yong-Keun Lee, Department of Dental Biomaterials Science, Dental Research Institute and BK 21 Program, School of Dentistry, Seoul National University, 28 Yeongeon-dong, Jongro-gu, Seoul, Korea. E-*: ykleedm@snu.ac.kr
Influence of
Abstract: Purpose: To evaluate
the influence of CAD/CAM scanning method (wax-up digitization vs. direct scanning of tooth
preparation) and finish line type (chamfer vs. shoulder) on the vertical fit of zirconia frameworks
for three-unit posterior-lower bridges. Methods: 30 sets of two stainless steel master dies were prepared with different
marginal designs (chamfer and shoulder) around the contour of each abutment.
Over these samples, 30 structures for three-unit posterior-lower bridges were
made with Cercon Smart Ceramics CAD/CAM system (Dentsply). An optical laser digitized the wax patterns of
15 bridge structures, and 15 pairs of master dies were directly scanned for
designing by computer the remaining half of frames. All zirconia milled structures were luted onto the metallic models
with a special clamp made-up to maintain constant seating pressure. Vertical
discrepancy around the margins was assessed under scanning electron microscopy
(SEM). Misfit data was analyzed using two-way ANOVA and Tukey’s test for multiple comparisons at α = 0.05. Results: Vertical discrepancy of the wax-up/digitized bridge
structures was significantly higher than that of the computer-designed
frameworks (P< 0.0001). No statistically significant differences were found
between the chamfer and shoulder vertical misfit values assessed around the
metallic models margins (P= 0.55). (Am J
Dent 2009;22:79-83).
Clinical significance: Vertical discrepancy of zirconia structures depended on the scanning method.
Precision was higher when direct scanning of prepared abutments was performed
instead of wax-up digitization, even when every group of frameworks tested can
be considered clinically acceptable in terms of vertical misfit. However, the
finish line type (chamfer or shoulder) seemed to have no effect on the marginal
adaptation of zirconia structures.
*: Prof.
Research Article
Laboratory evaluations of a
bi-level, extremely tapered bristled toothbrush
and a conventional uniform
bristled toothbrush
Caren M. Barnes, rdh, ms, David A. Covey, dds,
ms, Xiuren Shi, dds & Samuel L. Yankell, phd, rdh
Abstract: Purpose: To compare
a uniquely shaped tapered-bristle manual
toothbrush to a toothbrush with bristles uniform in height and diameter for the
ability to remove artificial plaque deposits in areas of the mouth that are
difficult to access; interproximal areas, the
gingival margin and subgingival. Methods: This study compared a GUM Summit+ Compact toothbrush
featuring extremely tapered bristles and conventional bristle ends in a
bi-level design. The upper, longest tapered bristles have the final 6 mm
tapered to 0.01diameter mm at the end. The conventional rounded end bristles
have less than 0.5 mm tapered down to 0.02 mm diameter. The comparison manual
toothbrush (Oral-B 40 Indicator) has bristles that are uniform in height and
diameter. Interproximal access efficacy was evaluated
using a pressure-sensitive artificial plaque substrate placed around simulated
anterior and posterior teeth. Subgingival access and gingival margin
cleaning were determined by using simulated gingiva prepared with a 0.2 mm space between the gingiva and
the artificial plaque substrate on tooth surfaces and results were recorded as
the artificial plaque removed below the gingiva or
around the gingival margin. Results: Interproximal access values were significantly (P<
0.001) higher for the GUM Summit+ Compact than for the Oral-B 40 Indicator. The
mean value for gingival margin cleaning efficacy of the GUM Summit+ Compact was
significantly (P < 0.001) superior compared to the Oral-B 40 Indicator. The
Gum Summit + Compact had a significantly superior subgingival access (P< 0.001) mean value when compared to the Oral-B 40 Indicator. In
this laboratory study, the GUM Summit+ Compact toothbrush was statistically
significantly more effective for removing plaque from the interproximal areas, at the gingival margin and subgingivally than
the Oral-B 40 Indicator toothbrush. (Am J
Dent 2009;22:84-88).
Clinical significance: The GUM Summit+ Compact
toothbrush was statistically significantly more effective for cleaning in interproximal areas, at the gingival margin and subgingivally than the Oral-B 40 Indicator toothbrush. It
is important for dental healthcare providers to be familiar with toothbrush
designs to guide toothbrush selection that best meets the patient's individual
needs.
*: Dr. Caren M. Barnes, UNMC College of Dentistry, 40th & Holdrege, Lincoln, NE 68583,
USA. E-*:
cbarnes@unmc.edu
Research Article
Sealant
adaptation and penetration into occlusal fissures
Barbara Kane, bs, Jordan Karren,
bs, Cristina
Garcia-Godoy, dds & Franklin
Garcia-Godoy, dds, ms
Abstract: Purpose: To evaluate the adaptation and penetration into occlusal fissures of two different types of fissure
sealants. Methods: Extracted third
molars (n=10) with evident occlusal fissures were
cleaned with a pumice/water slurry and randomly divided into two groups and
sealed following the manufacturers’ directions as follows: Group 1 - Embrace
fissure sealant (Pulpdent). Surfaces were cleaned and
dried, then etched for 15 seconds. Excess water was removed leaving the surface
slightly moist. Sealant was applied from cusp to cusp without covering marginal
ridges and light cured for 20 seconds using a halogen light at
500 mW/cm2. Group
2 - ClinPro (3M Espe). Surfaces
were cleaned and dried then etched for 15 seconds. The etched surface was
rinsed and thoroughly dried. Dried surfaces appeared frosty white. Sealant was
placed making sure not to go beyond etched area, and light cured for 20
seconds. Teeth were thermocycled (500x)
and sectioned with an Isomet in a mesio-distal
direction (4 slices per tooth). The sections were
examined under the SEM. The marginal adaptation of the sealants was evaluated
under the SEM using the following criteria: 1 = Smooth adaptation. Sealant
flows with enamel. No ledges; 2 = Sealant is not well adapted. Ledge may be
present. The penetration ability of the sealants was evaluated under the SEM
using the following criteria: 1 = Sealant penetrated 1/3 the total length of
the fissure; 2 = Sealant penetrated 1/2 the total length of the fissure; 3 =
Sealant penetrated the total length of the fissure. The results were
statistically analyzed using a t-test. Results: Embrace showed
consistently more intimate marginal adaptation than ClinPro in fissures of the same approximate width and depth (P< 0.05). (Am J Dent 2009;22:89-91).
Clinical significance: Embrace showed consistently
more intimate marginal adaptation than ClinPro in
fissures of the same approximate width and depth. The superior adaptation and
penetration of Embrace may produce longer lasting sealants.
*: Dr. Franklin Garcia-Godoy, College of Dental Medicine,
Nova Southeastern University, 3200 South University Drive, Fort Lauderdale,
Florida 33328, USA. E-*: fgarciagodoy@gmail.com
Research Article
Effect of heat on
the flow of commercial composites
Juliana da Costa, dds,
ms, Rose McPharlin, dmd, Thomas Hilton, dmd, ms & Jack Ferracane, phd
Abstract: Purpose: This study
compared the flowability of various commercial dental
composites to flowable composites in response to
warming in a composite warmer. Methods: 18 conventional resin composites and four flowable composites were tested at room temperature (23°C), and the conventional
composites were tested after pre-heating in a Calset unit (Addent) to 54°C or 68°C. Flowability was determined by placing uncured composite onto plastic sheets and loading for
180 seconds (4 kg load) while maintained at 36°C (conditioning temperature [n=3])
to simulate placing room temperature composite into a tooth. The composite was
light-cured for 40 seconds. The thickness of the specimens
were measured. Thickness/volume (T/V) were compared for the composites for the three temperatures, and between flowable and conventional composites at 23°C (one-way
ANOVA/Tukey's; P< 0.05). Results: At 23°C, the flowable composites
T/V were significantly less than the conventional composites (P< 0.001),
ranging from 0.46 mm/cm3 (Perma Flo HV) to
1.43 mm/cm3 (Point 4 Flow), except for Z100 (1.48 mm/cm3/±0.32),
Z250 (1.79 mm/cm3/±0.09), Gradia (1.53
mm/cm3/±0.07), and Grandio (1.98 mm/cm3/±0.07).
The T/V of the conventional composites were not significantly different at all
three temperatures (P> 0.05), except for Esthet-X
which showed the greatest T/V decrease at 68°C (3.84 mm/cm3/±0.3)
compared to 23°C (6.44 mm/cm3/±0.36) and 4 Seasons which showed the
greatest T/V decrease at 54°C (3 mm/cm3/±0.1) compared to 23°C (3.57
mm/cm3/±0.1.4). (Am J Dent 2009;22:92-96).
Clinical significance: Warming of certain composites
might increase their flowability, which may improve
the composite adaptation to a cavity preparation.
*: Dr. Juliana da Costa,
Department of Restorative Dentistry, Division of Operative Dentistry, OHSU School
of Dentistry, 611 S.W. Campus Drive, Portland, OR 97369, USA. E-*:dacostaj@ohsu.edu
Research Article
Light polymerization-dependent
changes in color and translucency
of resin composites
MarÍa del Mar PÉrez, phd, Arafa Saleh, phd, Rosa Pulgar, md, dds, phd & Rade D. Paravina,
Abstract: Purpose: To determine the influence of type of polymerization
light on changes in color and translucency of resin composites. Methods: 16 shades of commercial
composites were analyzed. Specimens were polymerized with
quartz-tungsten-halogen (QTH) and light-emitting diode (LED) polymerization
light. Color of non-polymerized and polymerized composites was measured against
white and black backgrounds using a spectroradiometer.
Changes in color (DE’), translucency (DTP’) and
color parameters (DL’, DC’ and Dh’) were
calculated for each polymerization light. The differences among DE’ values
and among DTP’ values obtained for each device were analyzed by
two-way ANOVA. Multiple regression analysis was used to determine the influence
of color parameters on DE’ and DTP’. Results: The results indicated that
there was significant difference among the DE’ and DTP’ values
obtained using QTH and LED light polymerization (P< 0.05). The prediction
equations for DE’ and DTP’ based on
the multiple regression analyses indicated that DE’ was
mainly caused by DC’ for both lights. However DTP’ was
mainly caused by Dh’ for LED light and by the DC’ for QTH
light. Changes in translucency significantly influenced the overall color
changes after polymerization. (Am J Dent 2009;22:97-101).
Clinical significance: The type of
polymerization light (LED or QTH) influences polymerization-dependent changes
in color and translucency of resin composites. Therefore, dental professionals
should be aware that the final color and translucency of composite restoration
may vary based on the type of light polymerization used.
*: Dr. María
Research
Article
Subjective and objective
perceptions of specular gloss and surface
roughness of esthetic resin composites
before and after artificial aging
Nadine Barucci-Pfister, med dent & Till N. GÖhring,
pd, dr med dent
Abstract: Purpose: To correlate measurements of specular gloss and surface roughness of resin composite materials with subjective
perception of luster before and after artificial aging. Methods: Polished specimens of eight composites were compared with
human enamel (HE): microfilled SR Adoro (SR); microhybrid Artemis (AR), Enamel HFO (EHFO), Miris (MI), Tetric Ceram (TC),
Venus (VE); and nanohybrid CeramX (CX) and nanofilled Filtek Supreme (FS). Before, during and after artificial aging (6000 thermal changes
between 5°C and 50°C in an artificial oral environment, 240 hours storage in a
container with ethanol, 300 minutes of toothbrushing), specular gloss and surface roughness were measured.
Initial and endpoint gloss results were correlated with subjective luster
rankings of 10 individuals. Results: Artificial aging resulted in minor (EHFO, CX, FS), moderate (SR, MI, TC, VE) to
high (AR) increases in surface roughness. Specular gloss decreased linearly for SR and FS, but decreased after an initial increase
for all other materials. Subjectively, AR and FS were rated more and TC, VE and
CX less lustrous than HE at baseline. After aging, luster of EHFO and FS was
ranked higher and AR, TC, and VE lower than HE. Surface roughness was
consistent with subjective perceptions (correlation coefficient: initial r =
0.913; endpoint r= 0.944, P≤ 0.0006), whereas specular gloss was consistent with subjective perceptions only after artificial aging
(initial r= 0.616, P= 0.1084; endpoint r= 0.834, P = 0.0072). (Am J Dent 2009; 22:102-110).
Clinical significance: Whereas
surface roughness increased during artificial aging, specular gloss showed an initial increase for most materials before subsequent decrease.
Only a poor correlation was found between these objective measurements. However
they corresponded well with subjective perception after artificial aging when
differences in luster became more obvious.
*: Priv.-Doz. Dr. Till N. Göhring,
Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental and Oral Medicine, University
of Zurich, Plattenstrasse 11, CH-8028 Zurich, Switzerland. E-*:
till.goehring@zzmk.uzh.ch
Research Article
Evaluation of different flowable materials for bonding brackets
AscensiÓn Vicente, dds, phd & Luis A. Bravo, md, dds, ms, phd
Abstract: Purpose: To compare the shear bond
strength and the adhesive remnant on the tooth after debonding of brackets bonded with a traditional orthodontic resin (Transbond XT), a flowable composite (X-Flow), a flowable compomer (Dyract Flow) and a flowable giomer (Beautifil Flow). Methods: 105 extracted human premolars
were used. They were divided into four groups: (1) Transbond XT, (2) X-Flow, (3) Dyract Flow, and (4) Beautifil Flow. Shear bond strength was measured using a
universal testing machine with a cross-head speed of 1 mm/minute. The adhesive
remnant on the tooth after debonding was quantified
using image analysis. Results: No
significant differences were found between the shear bond strengths of the
different groups evaluated (P> 0.05). Transbond XT
left significantly more adhesive on the tooth than the three flowable materials, and among the flowable materials, X-Flow left significantly less adhesive than Beautifil Flow (P< 0.008). (Am J Dent 2009;22:111-114).
Clinical
significance: The flowable composite, flowable compomer and flowable giomer evaluated in this study all achieved bond strengths
similar to that of traditional bond systems for brackets and left significantly
less adhesive remnant on teeth after debonding. They
may therefore be considered suitable materials for bracket bonding although in vivo studies are necessary in order
to confirm this. Furthermore, their flowable characteristics did not affect the adequate positioning of brackets.
*:
Dr. Ascensión Vicente, Orthodontic Teaching Unit,
Dental Clinic, The University of Murcia, Hospital Morales Meseguer,
2nd Floor, C/. Marqués de los Vélez, s/n, 30008 Murcia, Spain. E-*: ascenvi@um.es
Research Article
The in vitro effect of a collagenolytic enzyme inhibitor on lesion
development in root dentin
Yasushi Fukuda, phd, Syozi Nakashima, Phd & Takashi Ujiie, msc
Abstract: Purpose: To evaluate the effects of a new
active collagenase inhibitor, Pirocton Olamine (PO), on acid demineralization in dentin and to
investigate possible mechanisms of the inhibitory effects. Methods: Demineralized bovine dentin
sections were cyclically exposed to one of the test solutions containing PO (0
- 0.33%) and NaF (0.07%) for 3 minutes, then to a Clostridium histolyticum (Ch-collagenase) collagenase solution for 16 hours and finally to an acetate buffer solution for 6 hours for
further demineralization within a single day. This cyclic treatment was
repeated three times for 3 days. Changes in the mineral loss and lesion depth
were quantified by transverse microradiography, and
the extent of the degradation by the collagenase in
the collagen matrix was measured by microscopic observation after the
completion of the 3-day cyclic treatments. Possible mechanisms of PO inhibitory
effects on collagen matrix degradation were tested by incubating
Clinical significance: Inhibition of collagen matrix
degradation could contribute to inhibiting acid demineralization of dentin by
preserving the dentin matrix and possibly enhancing fluoride retention in the
collagen matrix of demineralized dentin. The combined
use of
*: Dr. Yasushi Fukuda, Oral-Care
Research Laboratories, Lion Corporation, 100 Tajima, Odawara-shi,
Kanagawa 256-0811,
Research Article
Influence of different luting concepts on long
term retentive strength
of zirconia crowns
Claus-Peter Ernst, prof dr, Erwin Aksoy, dr, Elmar Stender, dr & Brita Willershausen, prof dr
Abstract: Purpose: To evaluate
the retentive strength of a resin cement in combination with a conventional
adhesive (Variolink II/Syntac Classic), two resin cements with self-etching adhesives (Panavia F 2.0/ED Primer, Multilink/Multilink Primer A/B), two self-adhering cements (RelyX Unicem Aplicap, Maxcem), and a resin-modified glass-ionomer cement (FujiCem) after
cementation of zirconium-oxide ceramic crowns (LAVA) on extracted human teeth. Methods: 160 extracted teeth (n=20)
were prepared in a standardized manner (10°, h= 3 mm). The crowns’ inner
surfaces were air-abraded/sandblasted (Rocatec Pre).
Additional pretreatment was carried out with Multilink (metal primer or Monobond S). With RelyX Unicem Aplicap, an additional
group that also received Rocatec Plus pretreatment
was examined. Immediately after thermocycling (x5000,
5/55°C), 50% of the luted ceramic crowns (n = 10)
were pulled off along the path of insertion (Zwick 1425); the remaining samples (n = 10) were tested after 1 year of water
storage. Statistical analysis was performed using the Wilcoxon Mann-Whitney U-test and Bonferroni adjustment at the
5% level of significance. Results: The retentive strength values (N/mm2) after 1 year of water storage
were (Min/Q1/Median/Q3/Max): Variolink II/Syntac: 1.0/1.9/2.5/3.3/5.2, Panavia F 2.0: 1.5/1.8/2.1/3.6/5,4, Multilink/Metallprimer:
2.9/4.6/5.3/9.4/11,7, Multilink/Monobond S:
4.1/4.8/5.4/7.7/12.6, RelyX Unicem Aplicap: 3.9/6.3/7.5/9.0/10.7, RelyX Unicem Aplicap/Rocatec Plus: 4.4/5.8/7.2/9.4/11.9, Maxcem:
0.9/2.2/3.0/3.3/4.5, FujiCem: 1.6/2.7/4.3/5.4/6.7. RelyX Unicem Aplicap and Multilink showed the highest median retentive strength values. Long-term
water storage did not affect the retentive strength. (Am J Dent 2009;22:122-128).
Clinical significance: Some simplified “self adhering
cements” are certainly able to provide retentive strengths between zirconia crowns and dentin stumps that are comparable to
those mediated by classical adhesive luting materials.
*: Prof. Dr. Claus-Peter Ernst, Department of Operative
Dentistry, Augustusplatz 2, 55131
