Lupine Publishers | Journal of Pediatric Dentistry
Abstract
Dental technology that depended on the standardized lost-wax
casting technology has been greatly improved with the
introduction of dental CAD ⁄ CAM systems. The aim of the present study
was to compare between the color changes of CAD/CAM
acrylic and manually performed acrylic bridges used for pediatric
patients. Forty study casts of children aged 2 - 4 years old of both
genders, with prematurely lost one of the maxillary central incisors and
the adjacent lateral incisor was carious and considered to
be abutment tooth were involved in this study for construction of
cantilever bridges. For each cast, two bridges were constructed;
1st one is CAD/CAM acrylic bridge and the other one is manually
performed acrylic bridge. After immersing the bridges in saturated
chocolate solution for different time intervals, color changes of the
bridges were measured using 3Shape scanner system.
Keywords: Color; Changes; CAD/CAM; Bridges; Pediatric; Patient
Introduction
Trauma and/or dental caries is the common causes those
result in premature loss of teeth in children. Cosmetic/aesthetic
restoration of such condition considers to be challenging in the
pediatric dental field. In case of premature tooth loss in anterior
incisal segment there will result in arch space loss and teeth’s
inclination that causing a collapse of the anterior teeth and
midline shifting [1], as well as may lead to parafunctional habits
[2]. Mahmoud (2009) found that anterior tooth loss had effect on
patient’s quality of life and gave negative effects on him/his [3]. Al
Rawi (2017) found that placement of cantilever acrylic bridges for
restoring the aesthetic dental appearance of preschool children
resulted in positive successes both to the child and parents [4].
Extrinsic discoloration of teeth and oral prostheses is stains caused
by foods or beverages. In pediatric patients such stain mostly
occurred due to colored foods such as beets or chocolate as well as
berries and candies [5, 6]. This study considered to be the first step
of our series studies deal with determining different physical and
mechanical properties of the prostheses used for pediatric patients
we planned to carry out (
in vitro and in vivo studies). Starting
with the present study that aimed to compare between the color
changes of CAD/CAM and manually performed acrylic bridges used
for pediatric patients. After immersing the bridges in chocolate
solution for different time intervals, color changes of the bridges
were measured using 3Shape scanner system.
Material and Methods
This study starting with collection of forty study casts of children
aged 2-4 years old of both gender, with prematurely lost one of
the maxillary central incisors and the adjacent lateral incisor was
carious and considered to be abutment tooth were involved in this
study for construction of cantilever bridges (Figure 1). For each cast,
two bridges were constructed; 1st one is CAD/CAM acrylic bridge
and the other one is manually performed acrylic bridge (Figure 2).
Construction CAD/CAM bridge: The cast was 3D scanned by special
scanner (710 3D) (smart optics Sensortechnik GmbH, Germany).
The design of the bridge was carried out using Exocad Program
(smart optics Sensortechnik GmbH, Germany). Acrylic block
(Poly-methyl methacrylate) of classic shade A1 (Ivoclar vivadent,
Switzerland) was used for fabrication of the bridge using CAD/
CAM machine (Charly dental, ZI Fonlabour, France). The bridge
was finished and polished very well [4]. Construction of manually
acrylic bridge: Wax pattern was fabricated on cast then followed
the technique of typical wax loss; the heat-cure acrylic (Ivoclar
vivadent, AG, FL-9494 Schaan/Liechtenstein) of classic shade A1 was used for bridge fabrication. Finally, surface finishing and
polishing was done [7]. Saturated chocolate solution was prepared
using 15g chocolate powder (MacChocolate TM, Malaysia) with
100ml distilled water. Baseline color readings for acrylic bridges
were taken then immersed in chocolate solution for different time
intervals (one week and two weeks) and maintained in incubator
of 37 °C, Fresh chocolate solution was prepared every day. Before
color measurements after one week and two weeks’ time intervals,
the bridges were rinsed with distilled water for 30 seconds, cleaned
with a soft bristle toothbrush and then dried with tissue paper [8].
Color measurement was carried out in the facial surfaces at the
center third of the abutment and the center third of the pontic part
of each bridge as shown in Figure 3. Color measurements of the
bridges were measured using 3Shape scanner system (3 Shape A/S,
Holmens Kanal 7.1060 Copenhagen K Denmark) and according to
the software program of the system, Classic shade (Ivoclar vivadent,
Switzerland) was depended.
Figure 1: One of the study casts involved in this study
Figure 2: One of the study casts involved in this study
Figure 3: Demonstrated the color shade measurement of the abutment and pontic portions of the acrylic bridge.
Results
Table 1 demonstrated the color shade of all samples at the
baseline and after one-week and two weeks-time intervals. The
results of the present study revealed that for all samples, the color
measurement demonstrated that in CAD/CAM group even with
using A1 shade acrylic block but at the baseline measurement the
abutment revealed A0 shade while the pontic revealed A1 shade.
Meanwhile, in manual group the abutment measured to be A1 shade
and the pontic gave B1 shade. The results demonstrated that for all
samples there were no changes in the color shade of CAD/CAM and
manually fabricated acrylic bridges after one-week time interval,
meanwhile, there were significantly color changes of all abutment
and pontic portions of all samples of both bridge types after two
weeks-time interval immersed in chocolate solution (Figure 4 & 5).
Figure 4: color shade measurement of CAD/CAM acrylic bridge after two weeks.
Figure 5: Color shade measurement of manual acrylic bridge after two weeks.
Table 1: Demonstrated the color shade of all samples at the baseline and after one-week and two weeks-time intervals.
Discussion
Restorations in the oral cavity are exposed to several factors
that make them vulnerable to color changes, such as temperature,
humidity, food and beverages. In the oral environment, restorative
materials are also subjected to numerous other liquids, to
temperature and load stress, and to tooth brushing. The success
of restorations depends not only on mechanical and physical
properties, but also on the esthetic appearance [9]. The color
measurement in this study demonstrated that in CAD/CAM
group even with using A1 shade acrylic block but at the baseline
measurement the abutment revealed A0 shade while the pontic
revealed A1 shade. These occurred because the thickness of the
abutment was only about 0.5mm lead to that the color measured
of the abutment was lighter than the pontic portion. Meanwhile,
in manual group the abutment measured to be A1 shade and the
pontic gave B1 shade. These results agreed with other studies those
found the thickness of the material significantly affected the color
shade of the prostheses [10,11].
The results demonstrated that the color changes demonstrated
only after two weeks-time intervals immersed in chocolate solution.
Even the color shades recorded in the CAD/CAM group considered
to be lighter than in manual fabricated group, the discoloration
from chocolate solution was probably due to adsorption of color
colorant of chocolate solution at the surface of the prostheses.
The CAD/CAM bridges fabricated from blocks of pre-polymerized
acrylic resin those had a hydrophobic surface that repels water
[12]. As well as, perfect polishing surfaces of the bridges involved
in this study revealed the limited discoloration that occurred
agreed with other research [13]. As the duration of immersion
increased, the color change values of both types of prostheses were
recorded by 3Shape scanner system. Thus, the time is considered
to be important factor in the staining of the dental prostheses and
these results agreed with others [14,15]. Fabrication of dental
prostheses with the help of CAD/ CAM technology is related to the
advantages of high-density polymers based on highly cross linked
polymethylmethacrylate [16]. Those advantages include; good
esthetic, low water solubility and absorption, sufficient strength,
low toxicity, easy repair with simple fabrication technique [17]. The
using of hot cure acrylic for fabrication of dental prostheses even
of some advantages but the main disadvantages include porosity
with the presence of residual monomer which is a potential
allergen, increased finishing time, brittle and uneven thickness
[18]. A limitation of this study is that it was an
in vitro study and
need to be collected with in vivo study to measure the degree of
color changes of the prostheses with presenting the effect of saliva
and oral hygiene measures. Further clinical and
in vitro studies are
necessary to evaluate the susceptibility of CAD/CAM and manually
acrylic bridges to discoloration by other beverages and nutrients.
Conclusion
Color considered as the most important factors for aesthetic
appearance of dental restorations. In addition to the optimal chemo
mechanical properties of acrylic resins, their availability in different
color-shades has increased their application in fixed and removable
prostheses. Acrylic resins can have acquired discoloration over time
because of the process of adsorption and liquid molecules adhere
to resin materials which was decreased their effect with using of
CAD/CAM technology over conventional methods of acrylic resin
prostheses fabrication.
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