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April 2024 Abstracts
Surface
deterioration of resin composites and enamel
Mediha Büyükgöze Dindar, dds & Meltem Tekbaş-Atay, dds, phd
Abstract: Purpose: To investigate the effect of
toothbrushing with new and used toothbrushes on the surface of resin composites
and dental enamel. Methods: The extracted human incisors were selected
after vestibular enamel surfaces (ES) were examined. Disc-shaped specimens of
direct composite (DC) and indirect composite (IC) were fabricated.
Computer-aided design-computer-aided manufacturing (CAD-CAM) composite blocks
(CC) were sliced in 2 mm thickness (n= 8). The surface roughness, gloss, and
color were measured. The measurements were performed before and after 3 months
of toothbrushing simulation (TBS) for 2,500 circular cycles. The wear index was
calculated by using the ImageJ program. The specimens were subjected to an
additional 2,500 cycles and the same measurements were repeated. Results: No significant increase in surface roughness values was observed in DC, IC, and
CC groups after 3 and 6 months of TBS except in the ES group. The highest
change in surface gloss was observed in the DC group. Although the wear index
of toothbrushes increased over time, only the increase in the IC group was
statistically significant (P= 0.033). (Am J Dent 2024;37:59-65).
Clinical significance: Changes in surface roughness, gloss, and
discoloration of the dental enamel and restorations and wear of toothbrush
bristles were increased over time.
Mail: Dr. Mediha Büyükgöze Dindar, Health
Science Vocational College, Trakya University, Edirne, Turkey. E-mail: medihabuyukgoze@hotmail.com
Salivary,
acidic and enzymatic degradation of resin composite
Lais M. Berri, Evelin V.M.
Keese, Fabiana M.G. França, dds, ms, phd, Roberta
T. Basting, dds, ms, phd,
Abstract: Purpose: To evaluate the effect of different finishing and
polishing systems on the surface roughness of a resin composite subjected to
simulated saliva-, acid-, and enzyme-induced degradation. Methods: 160
specimens (n= 40) were fabricated with Filtek Z350 XT nanofilled composite and
analyzed for average surface roughness (Ra). The specimens were finished and
polished using: AD - Al2O3-impreginated
rubberized discs (medium, fine, and superfine grit, Sof-Lex); SD - silicon
carbide and Al2O3-impregnated rubberized discs (coarse,
medium and fine grit, Jiffy,); MB - 12- and 30-multiblade burs. The control
group (CT) (n= 40) comprised specimens with a Mylar-strip-created surface.
Specimens from each group were immersed in 1 mL of one of the degradation
methods (n= 10): artificial saliva (ArS: pH 6.75), cariogenic challenge (CaC:
pH 4.3), erosive challenge (ErC: 0.05M citric acid, pH 2.3) or enzymatic
challenge (EzC: artificial saliva with 700 µg/mL of albumin, pH 6.75). The
immersion period simulated a time frame of 180 days. Ra measurements were also
performed at the post-polishing and post-degradation time points. The data were
evaluated by three-way ANOVA for repeated measures and the Tukey tests. Results: There was significant interaction between the finishing/polishing system and
the degradation method (P= 0.001). AD presented the greatest smoothness,
followed by SD. After degradation, CT, AD and SD groups became significantly
rougher, but not the MB group, which presented no difference in roughness before
or after degradation. CT and AD groups showed greater roughness in CaC, ErC and
EzC than in ArS. The SD group showed no difference in roughness when the
specimens were polished with CaC, EzC or ArS, but those treated with ErC had
greater roughness. In the MB group, the lower roughness values were found after
using CaC and EzC, while the higher values were found using ErC or ArS. (Am
J Dent 2024;37:66-70).
Clinical significance: As far as degradation resistance of nanofilled
composite to hydrolysis, bacterial and dietary acids and enzymatic reactions is
concerned, restorations that had been finished and polished with Al2O3-impregnated
discs had the smoothest surfaces.
Mail: Dr. Cecilia Pedroso Turssi, São
Leopoldo Mandic Institute and Dental Research Center, Rua José Rocha Junqueira,
13 - CEP 13045-755 Campinas, SP, Brazil. E-mail: cecilia.turssi@slmandic.edu.br
Effect
of low power Er:YAG laser irradiation of CAD-CAM
Yukari Odagiri, dds, Taku Horie, dds, phd, Kazuho
Inoue, dds, phd, Keiko
Sakuma, dds, phd,
Abstract: Purpose: To investigate the effect of
painless low-power Er:YAG laser irradiation of
conventional and polymer-infiltrated ceramic network (PICN) type CAD-CAM
resin-based composites (RBCs) on resin bonding. Methods: An Er:YAG laser system, phosphoric acid etchant, universal
adhesive, RBC, and two types of CAD-CAM RBC block were used. Microtensile bond
strength, fracture mode, scanning electron microscopy (SEM) observations of
bonding interfaces and CAD-CAM surfaces, and surface roughness of ground and
pretreated surfaces were investigated. As pretreatment methods, low-power Er:YAG laser irradiation and air-abrasion with alumina
particles were used. Results: The effect of low-power Er:YAG laser irradiation of CAD-CAM RBCs on bonding to repair resin varied depending
on the type of CAD-CAM RBCs. (Am J Dent 2024;37:71-77).
Clinical significance: The low-power Er:YAG laser irradiation of the conventional CAD-CAM RBCs was shown to be effective as
a surface pretreatment for resin bonding, while the laser irradiation of
PICN-type CAD-CAM RBCs was not effective.
Mail: Dr. Taku Horie, Department of
Operative Dentistry, School of Dentistry, Aichi Gakuin University, 2-11
Suemori-dori, Chikusa-ku, Nagoya, 464-8651, Japan. E-mail: lifedoor@dpc.agu.ac.jp
Effect
of fluoride or chitosan toothpaste and at-home bleaching
Waldemir Francisco
Vieira-Junior, dds, msc, phd, Alexandre
Magno Lucon, dds,
Abstract: Purpose: To evaluate how fluoride- or chitosan-based toothpaste
used during at-home bleaching affects enamel roughness, tooth color, and
staining susceptibility. Methods: Bovine enamel blocks were submitted to
a 14-day cycling regime considering a factorial design (bleaching agent ×
toothpaste, 2 × 3), with n=10: (1) bleaching with 16% carbamide peroxide (CP)
or 6% hydrogen peroxide (HP), and (2) daily exposure of a fluoride (1,450 ppm
F-NaF) toothpaste (FT), chitosan-based toothpaste (CBT), or distilled water
(control). Then, 24 hours after the last day of bleaching procedure the samples
were exposed to a coffee solution. Color (ΔEab, ΔE00,
L*, a*, b*) and roughness (Ra, µm) analyses were performed to compare the
samples initially (baseline), after bleaching, and after coffee staining. The
results were evaluated by linear models for repeated measures (L*, a*, b*, and
Ra), 2-way ANOVA (ΔEab and ΔE00) and Tukey’s
test (α= 0.05). Results: After the at-home bleaching procedure
(toothpaste vs. time, P< 0.0001), the toothpaste groups presented a
statistically lower Ra than the control (CBT<FT<control). Neither
toothpaste affected the bleaching efficacy with color variables like the
control (bleaching agent vs. toothpaste vs. time, P> 0.05). After coffee
exposure, CBT presented lower ΔEab and ΔE00 values in the HP groups (toothpaste, P< 0.0001), and lower b* and a* values
in the CP groups (toothpaste vs. time, P= 0.004). (Am J Dent 2024;37:78-84).
Clinical significance: Fluoride or
chitosan delivered by toothpaste can reduce surface alterations of the enamel
during at-home bleaching, without affecting bleaching efficacy.
Mail: Dr.
Waldemir Francisco Vieira Junior, Faculty of Odontology, University of
Campinas, Av. Limeira, 901 - Areião, Piracicaba - SP, 13414-903, Brazil. E-mail:
waljr@unicamp.br
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Clinical Trial
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A randomized controlled clinical trial on
press and block lithium disilicate partial crowns: A 4-year recall
Edoardo Ferrari-Cagidiaco, dds, phd, Giulia
Verniani, dds, Andrew Keeling, BDS, phd, Ferdinando Zarone, md, dmd, Roberto Sorrentino, dds, phd, Daniele Manfredini,
dds, msc, phd & Marco Ferrari, md, dmd, phd
Abstract: Purpose: To evaluate clinical performances of two lithium
disilicate systems (Initial LiSi press vs Initial LiSi Block, GC Co.) using
modified United States Public Health Service (USPHS) evaluation criteria and
survival rates after 4 years of clinical service. Methods: Partial
adhesive crowns on natural abutment posterior teeth were made on 60 subjects
who were randomly divided into two groups: Group 1: Initial LiSi press and
Group 2: Initial LiSi Block. Fabrication of partial crowns was made with full
analog and digital procedure in Groups 1 and 2 respectively. The restorations
were followed-up for 1 and 4 years, and the modified USPHS evaluation was
performed at baseline and each recall together with periodontal evaluation.
Contingency tables to assess for significant differences of success over time
in each group and time-dependent Cox regression to test for differences between
the two groups were used and the level of significance was set at P< 0.05. Results: Regarding modified USPHS scores, all evaluated parameters showed Alpha or Bravo
and no Charlie was recorded. No statistically significant difference emerged
between the two groups in any of the assessed variables (P> 0.05). No
statistically significant difference between scores recorded at the baseline
and each recall. All modified USPHS scores were compatible with the outcome of
clinical success and no one restoration was replaced or repaired, and the
survival rate was 100% after 4 years of clinical service. No difference was
found between traditional and digital procedure to
fabricate the crowns. The two lithium disilicate materials showed similar
results after 4 years of clinical service. (Am J Dent 2024;37:85-90).
Clinical significance: The crowns made with the two tested lithium
disilicate materials with analog and digital procedures showed 100% survival
after 4 years of clinical service with no statistically significant difference using
the modified USPHS scores.
Mail: Prof. Marco Ferrari,
Department Prosthodontics and Biomaterials, University of Siena, Siena 53100,
Italy. E-mail: ferrarm@gmail.com
Effect
of light-, chemical-, and dual-cured universal adhesives
Hoda Saleh Ismail, bds, msd, phd, Mohamed Elshirbeny Elawsya,
bds, msd, phd & Ashraf Ibrahim Ali, bds, msd, phd
Abstract: Purpose: To compare the internal adaptation of restorative
systems bonded to mid-coronal and gingival dentin using light-cured,
chemical-cured, and dual-cured adhesives, both immediately and after aging. Methods: 60 molars were selected and received occluso-mesial preparations with dentin
gingival margins. Restorations were performed using different restorative
systems with light-cured, chemical-cured, and dual-cured adhesives. Internal
adaptation was assessed by examining the percentage of continuous margin (%CM)
at the pulpal and gingival dentin under a scanning electron microscope at ×200
magnification. Half of the teeth were stored in sterile water for 24 hours,
while the other half underwent 10,000 thermal cycles. Micro-morphological
analysis was conducted on representative samples at ×1,000 magnification. Results: The restorative system with light-cured adhesive exhibited significantly lower
%CM values at the gingival dentin, particularly after aging. Aging had a
negative impact on the %CM values of the pulpal and gingival dentin in
restorative systems with light-cured and dual-cured adhesives. Regional dentin
variations influenced the %CM values, especially after aging, regardless of the
restorative system used. The tested restorative system with chemical-cured
adhesive is preferable for achieving improved internal adaptation when bonding
to both mid-coronal and gingival dentin, compared to the other tested systems.
(Am J Dent 2024;37:91-100).
Clinical significance: The study highlights the
variations in adhesive performance between different regional dentin areas
using the tested restorative systems.
Mail: Dr. Hoda Saleh Ismail,
Conservative Dentistry Department, Faculty of Dentistry, Mansoura University,
Algomhoria Street, PO Box 35516, Mansoura, Aldakhlia, Egypt. E-mail: hoda_saleh@mans.edu.eg
Effect
of toothbrushing with conventional and whitening dentifrices
Stephanie Francoi Poole, dds, msc, Lívia Fiorin, dds, msc, phd, Alia Oka Al Houck, dds, msc,
Abstract: Purpose: To evaluate the effect of toothbrushing with
conventional and whitening dentifrices on the color difference (∆E00),
gloss (∆gloss), and surface roughness (SR) of stained stabilized zirconia
with 5 mol% of yttrium oxide (5Y-TZP) after polishing or glazing. Methods: Specimens were divided into four groups (n=20): C (control), S (staining), SG
(staining and glazing) and SP (staining and polishing). 50,000 toothbrushing
cycles were performed with conventional (n=10) and whitening (n= 10) dentifrice
slurries. The ΔE00 and Δgloss were measured using a
spectrophotometer and CIEDE2000 system while SR was measured by laser confocal
microscope. The ΔE00 and Δgloss data were analyzed using
2-way ANOVA, and SR data were analyzed using the linear repeated measures
model, with Bonferroni's complementary test (α= 0.05). Results: The
ΔE00 values were beyond the acceptability threshold and no
differences were found among the groups. There was no difference among groups
to Δgloss after toothbrushing with conventional dentifrice while SP
presented the highest values of Δgloss after toothbrushing with whitening
dentifrice. Conventional dentifrice decreased the SR of stained groups and
whitening dentifrice decreased SR of S and SG. The toothbrushing with
conventional and whitening dentifrices promoted color difference, but did not
impair gloss and surface roughness of stained 5Y-TZP. (Am J Dent 2024;37:101-105).
Clinical significance: Monolithic
zirconia has been routinely used for aesthetic restorations, however the type
of finishing procedures that is carried out on it must be taken into
consideration, in addition to the fact that brushing can influence the color
difference of the material as well as interfere with surface roughness and
gloss.
Mail: Prof. Adriana Cláudia Lapria Faria, Av. do Café,
s/n, 14040-904, Ribeirão Preto - SP, Brazil. E-mail: adriclalf@forp.usp.br
Laboratory study
of fracture resistance and failure mode of porcelain
Amirhossein
Samiee Dehpagaee, dds & Omid Tavakol, msc, dmd
Abstract: Purpose: To compare the fracture resistance and failure mode of
porcelain laminate veneers with different preparation depths in endodontically
treated teeth. Methods: Root canal treatment was performed for 40
maxillary central incisors, and then the teeth were divided into four groups
(n= 10). The preparation depths were as follows: Group A: 0.9 mm, Group B: 0.6
mm, Group C: 0.3 mm, and in all three groups, 2 mm butt joint incisal
reductions were performed; Group D was a control group with no preparation.
Then 30 lithium disilicate porcelain veneers were milled by CAD- CAM method and
cemented. After that, all specimens were subjected to cyclic loading and
thermal cycling and finally were tested by a universal testing machine until
failure occurred. Results: The mean failure loads (N) after exposure to
continuous load were as follows: Group A: 625.70 (401.45-1037.77), Group B: 780.32
(222.93-1391.82), Group C: 748.81 (239.68-1241.87) and Group D (control): 509.88
(84.42-1025.85) and P= 0.216. Analysis of failure mode in four groups showed
that P= 0.469. There was no significant difference between the control and the
other groups. In this study, 0.3, 0.6 and 0.9 mm depths
of preparation for porcelain laminate veneers for endodontically treated teeth
had no significant difference in fracture resistance and failure mode with
non-prepared teeth. (Am J Dent 2024;37:106-112).
Clinical significance: Reasonable
consideration might be given to porcelain laminate veneer treatment for teeth
that have become discolored and resistant to bleaching (such as instances where
discoloration is severe following root canal treatment). This approach is
considered to be on the conservative side, and has
demonstrated that a labial preparation depth reduction of up to 0.9 mm does not
have any impact on the failure mode or fracture resistance of
endodontically-treated teeth.
Mail: Dr. Omid
Tavakol, Department of Prosthodontics, School of Dentistry, Shiraz Branch,
Islamic Azad University, Shiraz, Iran. E-mail:
omidtavakkol@yahoo.com
