ABSTRACT

ABSTRACT

Aim: to quantify the effect of presence of enamel wall and thermocycling on
marginal microleakage of class V cavities restored with preheated bulk-fill or preheated
nano-filled composite.

Methods: Class V cavities were prepared on the buccal surface
of forty-eight extracted maxillary first premolars. The teeth were divided into two groups
according to the type of preheated composite used (either bulk-fill or Nano-filled) and
further subdivided according to thermocycling or no thermocycling. The teeth were
immersed in 0.5% methylene blue dye solution for 24 hours at room temperature
and then sectioned buccolingually to examine the extent of microleakage by dye
penetration. Microleakage was assessed by a stereomicroscope at 40x magnification
and measured in micrometers depending on the extent of dye penetration for both
occlusal and gingival walls separately. Statistical analysis was done by Kruskal-Wallis
test for comparison between groups and Mann-Whitney test for comparing occlusal
and gingival dye penetration in each group.

Results: preheated Nano-filled composite
subjected to thermocycling showed more significantly microleakage than other groups
(P < 0.05). Microleakage was significantly more (P < 0.05) in gingival (cervical)
walls of teeth compared to occlusal walls in all groups except preheated Nano-filled
composite directed to thermocycling which showed no significant difference between
gingival and occlusal walls (P > 0.05).

Conclusions: thermocycling of preheated Nanofilled
composite produced more microleakage than thermocycling of preheated bulkfilled
composite. More microleakage was recorded in cervical areas than occlusal areas
of class V cavities.

Abstract:

Objectives: The disinfection of fabricated prostheses is crucial to prevent crossinfection
between dental laboratories and clinics. However, there is a lack of information
about the effects of chemical disinfection on 3D-printed denture base resins. This study
aimed to evaluate the impact of different disinfectants on the flexural strength, elastic
modulus, micro-hardness, surface roughness (Ra), and change in color of 3D-printed and
conventional heat-polymerized (HP) denture base resins (DBRs).

Methods: A total of
240 specimens (80 bar-shaped (64 × 10 × 3.3 mm) and 160 disk-shaped (10 × 2 mm))
were made from HP and 3D-printed DBRs. For each resin, the specimens were divided
into four groups (n = 10) according to the disinfectant solution. One remained in water
without disinfection as a control group, while the other three groups were disinfected
using 1% sodium hypochlorite, 2% glutaraldehyde, or 10% Micro 10+ for 30 min. The
flexural strength, elastic modulus, micro-hardness, Ra, and color change were measured.
The collected data were statistically analyzed using a two-way ANOVA and Tukey’s post
hoc test (α = 0.05).

Results: A significant decrease in flexural strength, elastic modulus, and
hardness was found with sodium hypochlorite (p < 0.05). When comparing the resins per
solution, the 3D-printed resin showed a significant decrease in flexural strength, elastic
modulus, and hardness compared with PMMA (p < 0.001), while no change was found in
the Ra of both resins with all disinfectants (p > 0.05). Disinfecting with sodium hypochlorite
resulted in a significant increase in color change for both resins (p < 0.05); however, all the
changes were within clinically acceptable limits. Sodium hypochlorite showed the highest
color change, while 2% glutaraldehyde and 10% Micro 10+ showed no significant changes
in the tested properties (p > 0.05).

Conclusions: Neither resin showed a change in surface
roughness with immersion in disinfectants. Sodium hypochlorite had an adverse effect on

ABSTRACT
 

Aim: This investigation was conducted to compare the impact of three distinct toothpastes on
mineral deposition and dentinal tubules occlusion.
 

Material and Methods: Sixty dentin samples were prepared from sixty extracted molar. The
samples demineralized by submerging in 6% citric acid for two minutes. Then assigned into three
groups (n=20) according to the three different toothpastes utilized: Group A1: Fluoride containing
toothpaste. Group A2: Nano-hydroxyapatite containing toothpaste. Group A3: Nano-hydroxyapatite
with Fluoride containing toothpaste. For a total of two weeks, brushing was repeated twice a day
with a 12-hour interval between each session. Each sample were quantitatively assessed the ion
concentrations (atom%) on the dentin surface using Energy-dispersive Analytical X-ray (EDAX)
and qualitatively examined the dentinal tubules occlusion using Scanning Electron Microscope
(SEM).
 

Results: The lowest mean value of (Ca) % was found in (A1). The lowest mean (P) % value
observed in (A1). The lowest mean value of (F) % was recorded in (A2), while the greatest mean
value was identified in (A1 and A3).
 

Conclusion: Toothpastes containing nano-hydroxyapatite, both with and without fluoride,
show similar effects on mineral deposition and blockage of dentinal tubules.

ABSTRACT

Aim: This investigation was carried out to assess and evaluate the remineralization ability of
artificial enamel carious lesions by (n-HAP) tooth paste in comparison with (F) tooth paste.
 

Material and Methods: sixty healthy extracted teeth, the roots were cut and sectioning
crowns. The samples were placed in acrylic resin blocks, covered with nail varnish except a 3x3
mm of exposed enamel. The samples were divided into three groups based on the toothpaste
used: GA1 (n-hap), GA2 (F) and GA3 (n-hap+ F). The initial enamel lesion was produced using
a demineralizing solution. Applying toothpaste for 30 cycles twice daily, and washing them under
running water. In pH-cycling models, samples were demineralized twice daily for three hours,
followed by a two-minute treatment with a remineralizing agent slurry twice daily over a 24-hour
cycle. After two weeks and one month of brushing, specimens were examined utilizing (EDAX)
and (SEM).
 

Results: At baseline and after demineralization, there was no statistically significant difference
found between the three tested toothpastes, respectively, while after 2 weeks, the statistical analysis
showed G A1 (n-hap) was significantly higher than of GA2 (F) and GA3 (n-hap+ F). After 1 month,
there was a statistically significant difference as G A1 (n-hap) was significantly higher than GA2
(F) and GA3 (n-hap+ F).
 

Conclusions: Nanohydroxyapatite-containing toothpaste exhibits superior remineralizing
potential as compared to fluoride-containing toothpaste