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December 2016 Abstracts
Clinical evaluation of a toothpaste
containing lysozyme for the treatment of
Yanxiong Shao, mmed & Haiwen
Zhou, dds
Abstract: Purpose: To assess the efficacy and safety
of a toothpaste containing lysozyme for the treatment of minor recurrent
aphthous stomatitis (MiRAS) in a 3-month clinical trial. Methods: 71 participants with MiRAS were recruited to this
randomized, parallel-controlled, double-blind clinical trial. Participants were
allocated randomly to the test group or the control group. Demographic data and
pain score (visual analogue scale, VAS) were recorded at baseline. Healing time
of MiRAS, recurrence frequency and side effects were recorded at the 1-, 2- and
3-month follow-up visits. All data were analyzed using SAS software version
8.0. Results: There was no
significant difference (P> 0.05) in pain score between the treatment group
(3.00 ± 1.66) and the control group (2.66 ± 1.51). The average healing time was
significantly reduced (P< 0.01) in the treatment group (5.66 ± 2.02)
compared with the control group (7.46 ± 2.69), while the recurrence frequency
also showed a significant reduction from 4.40 ± 2.89 in the control group to
3.06 ± 1.48 in the treatment group (P< 0.05). No obvious side effects were
observed. (Am J Dent 2016;29:303-306).
Clinical significance: The results of this clinical
study supported the conclusion that a toothpaste containing lysozyme was
effective in promoting healing and reducing recurrence frequency without
significant side effects in the treatment of minor recurrent aphthous
stomatitis.
Mail: Dr. Haiwen Zhou, Department
of Oral Mucosal Diseases, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong
University School of Medicine, 500 Qu-xi Road, Shanghai, 200011, PR China. E-mail:
haiwen39@126.com
The influence of the utilization time of brush heads
from different types
Jan Schmickler, Sabine Wurbs, dr med dent, Susanne
Wurbs, dr med dent, Katharina Kramer, dr rer nat,
Abstract: Purpose: This randomized clinical trial
investigated the influence of the utilization time of brush heads from
different types of power toothbrushes [oscillating rotating (OR) and sonic
action (SA)] on oral hygiene (plaque accumulation and gingival inflammation)
over a 6-month observation period. Methods: 49 participants were randomly allocated into two groups: use of the same brush
head over 6 months (NR: non-replacement) or replacement of brush head every 4
weeks over 6 months (R: replacement). Each group was subdivided into two
subgroups according to kind of toothbrush (TB) used (OR and SA). Modified
Quigley-Hein plaque index (QHI), papilla bleeding index (PBI), and gingival
index (GI) were recorded at baseline and 2, 8, 12, 16, and 24 weeks after
baseline. After 24 weeks, participants of both groups (R and NR) received a new
brush head. At week 26, final QHI, PBI, and GI were recorded. Results: QHI decreased between baseline
and follow-up visits in R groups (P< 0.05), with the exception of week 12 (P=
0.26). In NR groups, no significant decrease was detected (P> 0.05). There
was no significant effect of time on PBI or GI in any of R subgroups (P> 0.05).
In NR oscillating/rotating TB: significant increase in PBI and GI was detected
24 weeks after baseline (PBI: P= 0.02, GI: P= 0.03); sonic action TBs showed
significant decrease in PBI at every follow-up visit (P< 0.05), except at 24
weeks after baseline (P= 0.73). GI was significantly decreased at 2 weeks after
baseline only (P< 0.01). (Am J Dent 2016;29:307-314).
Clinical significance: Six-month use of the same brush
head reduced effectiveness in removing plaque, and gingival inflammation
appeared to increase after a utilization time of over 4 months. Replacing brush
heads is advised after 4 months.
Mail: PD Dr. Dirk Ziebolz, Dept.
of Cariology, Endodontology and Periodontology, University Leipzig, Liebigstr. 12,
D 04103 Leipzig, Germany. E-mail:
dirk.ziebolz@medizin.uni-leipzig.de
Antimicrobial and antibiofilm activity of silver,
titanium dioxide
Fatemeh Lavaee, dmd, phd, Kiana Faez, Kioumars Faez, Nahal Hadi, bsc, msc, phd
Abstract: Purpose: To compare the antimicrobial effects of chlorhexidine,
penicillin, erythromycin, clindamycin, tetracycline and vancomycin with silver,
titanium dioxide and iron nanoparticles and also to consider the synergistic
antibacterial and antibiofilm effects of nanoparticles in clinical and standard
strains of Streptococcus mutans and Streptococcus sanguinis. Methods: The specimens collected from
66 3-5 year-old children with detected S.
mutans and S. sanguinis by PCR
were then exposed to the antimicrobial activity of chlorhexidine, penicillin,
erythromycin, clindamycin, tetracycline and vancomycin with silver, titanium
dioxide and iron nanoparticles measured by microdilution and disc diffusion
tests and the colony counted after 1 to 5 minutes. The antibiofilm activity was
examined by microtiter test. Results: Use of nanoparticles alone showed higher minimum inhibitory concentration (MIC)
than using them synergistically. The most effective synergistic solution was
the one containing TiO2, Ag and Fe3O4 showing 0.019 μg/ml in S. mutans and S. sanguinis. Furthermore,
this solution had the lowest biofilm inhibitory concentration (BIC) and colony
forming units than the other antibiotics and chlorhexidine. (Am J Dent 2016;29:315-320).
Clinical significance: The solution containing TiO2,
Ag and Fe3O4 showed the lowest inhibitory and antibiofilm
concentration against S. mutans and S. sanguinis compared to those of other
nanoparticle containing solutions, antibiotics and chlorhexidine, thus it may
be used for treating dental caries, dental plaque and oral infections.
Mail: Dr. Farzan Modaresi, Department
of Microbiology, School of Medicine, Jahrom University of Medical Sciences,
Jahrom, Iran. E-mail: Farzanmodaresi@jums.ac.ir, Modarresifarzan@gmail.com
Quantitation of endotoxin and lipoteichoic acid
virulence using toll receptor
Tom Huggins, phd, John CHRISTIAN Haught, phd, Sancai Xie, phd, Cheryl S. Tansky, ms,
Abstract: Purpose: To apply quantitative
Toll-like receptors (TLR) cell assays to compare lipopolysaccharides (LPSs) and
lipoteichoic acids (LTAs) from different oral bacterial strains for potential
pathogenicity in vitro. Methods: The
potency of LPS and LTA from different bacteria on activation of TLR reporter
genes in HEK-tlr cell lines was examined. P.
gingivalis LPS mix, P. gingivalis 1690 LPS, P. gingivalis 1435/50 LPS, E. coli LPS (E. coli K12), B. subtilis LTA, S. aureus LTA, E. hirae LTA and S. pyogenes LTA were examined in both TLR2 and TLR4 HEK cell line reporter assays.
Solutions of LPS and LTA from selected bacteria were applied in a dose response
fashion to the TLR reporter cells under standard culture conditions for
mammalian cells. Reporter gene secreted-embryonic-alkaline-phosphatase (SEAP)
was measured, and half maximal effective concentration (EC50) was determined
for each sample. Concentration dependent TLR activation was compared to similar
responses to LPS and LTA for commercial BODIPY-TR-Cadaverine and LAL
biochemical (non cell based) assays. Results: All LPS from P. gingivalis activated
both TLR2 and TLR4 responses. E. coli LPS is a strong activator for TLR4 but not for TLR2 responses. In contrast,
both B. subtilis and S. aureus LTA provoked responses only in
TLR2, but not in the TLR4 assay. Interestingly, E. hirae LTA and S. pyogenes LTA
did not stimulate strong TLR2 responses. Instead, both E. hirae LTA and S. pyogenes LTA mounted a reasonable response in TLR4 reporter gene assay. Both LPS and LTA
showed deactivation of fluorescence in BODIPY-TR-Cadaverine while only LPS was active in LAL. As with biochemical
assays, an EC50 could be determined for LPS and LTA from various bacterial
strains. The EC50 is defined as a concentration of LPS or LTA that
provokes a response halfway between the baseline and maximum responses. Lower
EC50 means higher potency in promoting TLR responses, and in principle indicates greater toxicity to the host. (Am J Dent 2016;29:321-327).
Clinical significance: InvivoGen TLR2 and TLR4 assays
distinguish specific types of microbial products, such as LPS and LTA from
different bacteria. Application of EC50 determinations creates a means for
quantitative and comparisons of LPS and LTA virulence in a cellular-based assay
and combinations of TLR reporter cell assays along with biochemical evaluation
of LPS/LTA in BODIPY-TR-Cadaverine and LPS in LAL assays provides a means to
quantitate virulence of plaque samples with respect to both LPS and LTA. These
learnings have long-term implications for patient care in that understanding
the virulence of patients’ plaque provides important information to assess risk
of oral diseases.
Mail: Dr. Tom
Huggins, Procter & Gamble, Mason Business Center, 8700 Mason-Montgomery
Road, Mason, OH, 45040, USA. E-mail: huggins.tg@pg.com
Lipopolysaccharide and lipoteichoic acid binding by
antimicrobials
John Christian Haught, phd, Sancai Xie, phd, Ben Circello, phd, Cheryl S. Tansky, ms, Deepa Khambe, ms,
Abstract: Purpose: To study the reactivity of lipopolysaccharide
(LPS) and lipoteichoic acid (LTA) with the cationically charged agents cetylpyridinium chloride, stannous fluoride, and the
non-cationic agent triclosan. We also assessed the effect of these agents to
inhibit LPS and LTA binding to cellular Toll-like Receptors (TLRs) in vitro. Methods: The ability of these
antimicrobials to bind with LPS and/or LTA was assessed in both the Limulus
amebocyte lysate and BODIPY-TR-cadaverine dye assays. Mass spectroscopy was
then used to confirm that stannous fluoride directly binds with LPS and to
determine stoichiometry. Lastly, we
looked for possible inhibitory effects of these antimicrobial agents on the
ability of fluorescently conjugated LPS to bind to TLR4 expressed on HEK 293
cells. Results: Cetylpyridinium
chloride (CPC) and stannous salts including stannous fluoride interfered with
LPS and LTA reactivity in both dye assays, while triclosan had no effect. Mass
spectroscopy revealed direct binding of stannous fluoride with E. Coli LPS at
1:1 stoichiometric ratios. In the cellular assay, cetylpyridinium chloride and
stannous fluoride, but not triclosan, inhibited LPS binding to TLR4. (Am J Dent 2016;29:328-332).
Clinical significance: These results support a
potential mechanism of action for stannous fluoride and CPC formulated in oral
products in which these ingredients bind bacterial toxins and potentially render
them less toxic to the host. These results may influence home care
recommendations for patients at risk for plaque-related diseases.
Mail: Dr. Chris Haught, The Procter & Gamble
Company, 8700 Mason Montgomery Road, Mason, OH 45040, USA. E-mail: haught.c@pg.com
The new generation of conventional
and bulk-fill composites do not reduce
Laís Rani Sales Oliveira Schliebe, dds, Stella Sueli Lourenço Braga, dds, ms,
Abstract: Purpose: To compare flowable and regular
paste bulk-fill resin composites with old and new generation conventional
composites that use incremental filling techniques for direct restoration of endodontically-treated
teeth. Methods: Four resin composites
produced by the same company (3M-ESPE) were used: two conventional resin composites
(old formulation, Z100, and new nanofilled formulation, Filtek Supreme XT); and
two bulk-fill resin composites (flowable composite, Filtek Bulk-fill Flowable
associated with Filtek Supreme, and regular paste, Filtek Bulk-fill Posterior).
Elastic modulus (E), Vickers hardness (VH), post-gel shrinkage (Shr), diametral
tensile strength (DTS) and compressive
strength (CS) were determined (n= 10) and statistically analyzed using ANOVA
and Tukey’s test (α=0.05). Shrinkage stresses were analyzed using
non-linear finite element analysis. Results: Filtek Bulk-fill flowable and Filtek Supreme XT had higher CS than Z100 and
Filtek Bulk-fill Posterior. Z100 and Filtek Supreme XT had higher DTS than Filtek Bulk-fill Posterior. Filtek Bulk-fill flowable had the lowest
values and Z100 the highest E and Shr. Z100 resulted in higher stresses in the
enamel and in root dentin close to the pulp chamber than the other filling
techniques. Filtek Bulk-fill Flowable resulted in lower stress than other resin
composites. (Am J Dent 2016;29:333-338).
Clinical significance: Using
bulk-fill composites, especially flowable resin composite, created lower
stresses in restored endodontically-treated teeth. Clinicians, when deciding
for direct restoration of endodontically-treated teeth, may choose the
bulk-fill composite to decrease undesirable effects of direct restoration while
simplifying filling procedure.
Mail: Dr.
Carlos José Soares, Federal University of Uberlândia, School of Dentistry,
Avenida Pará, 1720, Bloco 4L, Anexo A, Sala 42, Campos Umuarama, Uberlândia,
Minas Gerais, 38400-902 Brazil. E-mail: carlosjsoares@umuarama.ufu.br
Case-specific finite element analysis of dental
CAD/CAM prostheses
Davide Apicella, dds, phd, Tim Joda,
dmd, msc, Gianni
Bonadeo, dt, Roberto Sorrentino,
dds, msc, phd
Abstract: Purpose: To apply a design optimization
strategy to dental prostheses machining to verify whether this approach can
detect flaws occurring in the CAD process and to estimate the influence of the
type of material on the occurrence of fractures in restorations. Methods: The stereo lithography
interface format of a 4-unit (from canine to first molar) fixed dental
prosthesis designed by a conventional dental CAD process was converted into a
Finite Element Analysis (FEA) model. This basic model was coupled to the
mechanical properties of feldspathic ceramic, lithium disilicate ceramic (LS2)
and zirconia (ZrO2) to create three FEA models with different
mechanical properties. The models were constrained along the abutment housing
surfaces of the canine and the first molar, respectively. Finally, a simulated
load of 50 N was applied vertically to the occlusal surface of the first premolar. Results: The FEA showed a stress
peak concentration between the second connectors and the second premolar. The stress
peak overcame the ultimate tensile stresses of feldspathic and lithium
disilicate ceramics; conversely, the ultimate tensile stress of zirconia was
not overcome. A geometrical flaw was identified in the 4-unit fixed dental prosthesis.
The flaw was sensitive to tensional stress and could lead to failure of the
component. (Am J Dent 2016;29:339-344).
Clinical significance: The
results of the present investigation showed the importance and future impact of
the application of FEA in the daily practice of prosthodontics. A
FEA-implemented CAD process would allow proper prosthetic volumes with correct
dimensions of the framework, in order to withstand occlusal loads and
consequently reduce mechanical failures. FEA is a useful tool to simplify the
design of prosthetic frameworks and select esthetic ceramic materials with
strength enough to withstand occlusal stress.
Mail: Prof. Dr. med. dent. Marco Ferrari, Department of Prosthodontics & Dental Materials,
School of Dental Medicine, University of Siena, Viale Bracci 1, 53100 Siena, Italy. E-mail: ferrarm@gmail.com
Effects of desensitizing toothpastes on the
permeability of dentin
Meng Yang, ms, Hong Lin, dds, phd, Ruodan Jiang, ms & Gang
Zheng, dds, phd
Abstract: Purpose: To investigate the effects of
three commercially available desensitizing toothpastes on dentin permeability,
and compare the efficacy of each product for reducing dentin permeability in
the short term according to the frequency and duration of usage. Methods: 100 dentin discs with no
caries were prepared from freshly extracted human third molar teeth. The dentin
discs were brushed with three desensitizing toothpastes or with a
non-desensitizing toothpaste and distilled water, which served as control. The
100 dentin slices were randomly divided into two groups (n= 50): one group
underwent continuous brushing (brushed for 3 minutes continuously), and the
other group underwent discontinuous brushing (brushed three times, each time
for 1 minute). Then, the two groups were divided into five subgroups (n = 10)
for the five brushing applications. Dentin permeability was measured with a
hydraulic permeability system before and after brushing. Results: All desensitizing toothpastes reduced dentin permeability
significantly after treatment. Sensodyne Repair & Protect (calcium sodium
phosphosilicate) and discontinuous brushing reduced dentin permeability
significantly compared with continuous brushing. Dentin permeability values
showed no significant difference between the three toothpastes after 3 minutes
of continuous brushing. When comparing the three toothpastes under
discontinuous brushing conditions after 3 minutes, Sensodyne Repair &
Protect (calcium sodium phosphosilicate) reduced dentin permeability
significantly. (Am J Dent 2016;29:345-351).
Clinical significance: Sensodyne Repair & Protect
(calcium sodium phosphosilicate) and discontinuous brushing reduced dentin
permeability significantly compared with continuous brushing. Moreover,
brushing with Sensodyne Repair & Protect (calcium sodium phosphosilicate)
resulted in the lowest dentin permeability compared with those of the other two
toothpastes. These results indicated that Sensodyne Repair & Protect may
relieve dentin hypersensitivity.
Mail: Dr. Gang Zheng, Department
of Dental Materials, School of Stomatology, Peking University, 22 South
Zhongguancun Avenue, Haidian District, Beijing 100081, PR China. E-mail: gangzheng101@yahoo.com
Effect of radiotherapy, adhesive systems and
doxycycline on the bond
Eveline Freitas Soares, dds,
ms Lucas
Zago Naves, dds, ms, phd, Américo
Bortolazzo Correr, dds, ms, phd,
Abstract: Purpose: To investigate the effect of radiotherapy, doxycycline
and adhesive systems on the microtensile bond strength (μTBS) of the
dentin-composite interface. Methods: 60 human third molars were sectioned to expose middle dentin surface and
distributed according to: (1) adhesive system (Adper Scotchbond MP and Clearfil
SE Bond) applied, (2) application or not of doxycycline, and (3) submission to
60 Gy total radiation (2 Gy daily doses, 5 days/week for 6 weeks) before
restoration procedure (RtRes); after restoration procedure (ResRt) or not
submitted to radiotherapy (Control group). Specimens were tested for μTBS
and mode of failure were evaluated under optical
microscopy. The bonding interface was evaluated with a scanning electron
microscope (SEM). Data was submitted to three-way ANOVA and Tukey’s test
(α= 0.05). Results: There was
no significant difference between the μTBS (MPa) of Adper Scotchbond MP
(25.5±11.1) and Clearfil SE (27.6±9.1). Control (30.5±10.9) and ResRt
(29.2±10.4) presented μTBS significantly higher than RtRes (23.1±7.2).
Doxycycline (21.7±7.6) significantly reduced μTBS compared to groups
without doxycycline application (33.6±8.6). Dentin cohesive failure mode was
predominant for RtRes and mixed failure mode for ResRt. Mixed and adhesive
failures were frequently observed in control groups. SEM showed adhesive
penetration in dentin tubules in all groups, regardless of the radiotherapy and
the application of doxycycline. The radiotherapy before composite restoration
procedure decreased the µTBS. No statistical difference was observed between
the adhesive systems. The doxycycline reduced µTBS regardless of the other
conditions. (Am J Dent 2016;29:352-356).
Clinical significance: Composite
restoration procedure should be done before radiotherapy, regardless of the
adhesive system used.
Mail: Dr. Lourenço Correr-Sobrinho, Limeira Avenue, 901,
Vila Rezende, Areiao, Piracicaba, São Paulo, Brazil, 13414-903. E-mail:
sobrinho@fop.unicamp.br
