Objectives: The aim of this study was to evaluate the preferences of materials for posterior restorations
among Palestinian dentists and to assess whether postgraduate training or clinical experience had an
influence on their material preferences.
Methods: A cross-sectional study was carried out among 216 dentists in Palestine using an online
survey, which consisted of closed questions asking about sociodemographic variables, the level of
specialization and time since graduation. It further probed into the preferences for posterior restorations
through questions about the first choice of material, type of composite resin (if used), use of rubber dam
and preferences for curing.
Results: It was observed that 66.2% of the dentists preferred using composite. 72.9% preferred nano-
hybrid composite restorations over other types of composite material. However, the majority (88.4%) did
not prefer using a rubber dam. There was no significant association between the time of clinical training
or post-graduate training and their choices for the materials.
Conclusions : The study shows that composite was the preferred material for posterior restoration
among the Palestinian dentists, with nano-hybrid being their preferred type of composite. However,
these dentists seldom used rubber dam and their postgraduate training or time of training did not
influence their material choices.
Keywords: posterior restoration; composite resin; dentists; Palestine; cross-sectional study; material
choice.
Introduction
When comes to restoring the tooth, the modern era restorative dentist has adopted ways to restore
the tooth more conservatively, thanks to the rise of composite restorations with high success rates [1].
Direct restorations are being more preferred than indirect restorations. When comparing both, the former
has become preferable due to their low cost, less need for the removal of sound tooth substance and
their acceptable clinical performance [2, 3, 4, 5]. Amalgam has faced a constant decline in its use, owing
to dentists preferring composite for its advantages such as better aesthetics, enhanced adhesive
properties, leading to conservation of tooth structure [6], which in turn, leads to reinforcing the remaining
tooth structure [7]. The bonding of composite is also capable of alleviating the pain caused by a fractured
amalgam restoration [8]. Although composite has advantages, they have their own share of
disadvantages, such as increased susceptibility to secondary caries than amalgam [9, 10].
Recent advancements have led to the development of improved composite materials, with better
properties such as polishability, wear resistance and surface smoothness. Recently, nano-fillers have
been incorporated in resin composites, claiming to provide improved mechanical properties, combining
polishability and strength [11]. All of these factors have led to a gradual rise of popularity of composite
over amalgam. However, this has paved the way for dentists spending a significant amount of time
replacing restorations, contributing to the repetitive restorative cycle as said by Elderton [12].
Even though acceptable survival rates are achieved with Class I and II restorations in dental health
care, the replacement of failing restorations is still a relevant issue. Factors related to the patient,
operator, tooth, cavity size, and materials have been reported in the literature as potentially relevant for
restoration failures [2, 3, 9, 13-15], although evidence of this is still limited. Besides, the preferences and
attitudes of dentists towards restorative dentistry practice might vary from one geographical area to the
other. Hence, the aim of this study is to evaluate the preferences of materials for posterior restorations
among Palestinian dentists. A further aim was to assess whether postgraduate training or clinical
experience had an influence on their material preferences.
Materials and Methods
A cross-sectional study was designed to study the preferences of the materials for posterior
restorations among the Palestinian dentists. The study sample was determined to be the 300 dentists
registered with the Palestinian dental Association. An online survey request was sent to them and around
216 dentists responded with a response rate of 72%. The online survey had a questionnaire instrument
devised on the guidelines of a previous study [17]. It consisted of closed questions asking about
sociodemographic variables, the level of specialization and time since graduation. It further probed into
the preferences for posterior restorations through questions about the first choice of material (amalgam,
direct composite, indirect restoration), type of composite resin (microhybrid, microfilled, nanohybrid,
condensable, flow) and use of rubber dam (yes/no). Preferences for curing were also asked, such as the
average time taken for curing, the average time taken for etching and the most common light unit used for
curing. The study was approved by the Ethics committee of the Al Quds University.
Data were submitted to descriptive analyzes and the association existing between vital time since
graduation and post-graduation training was tested with chi-square or Fisher’s exact test. The analyzes
were carried out with Stata 10.0 software (StataCorp, College Station, TX, USA). A significance level of
α=0.05 was adopted for the study.
Results
The study sample consisted of 49.1% of male and 50.9% female. Considering the length of clinical
experience, 27.8% of the dentists had experience between 0-5 years, 40.5% had 6-9 years’ experience
and 31.5% had experience for more than 10 years. While 13.4% of the dentists had been trained in some
kind of formal continuing education (i.e., master’s degree, Ph.D. degree, specialization course), 86.6% of
the population did not undergo any such training.
Direct composite resin was selected by 66.2% as the first-choice material for restoration of posterior
teeth, while amalgam was preferred by 31.9% of the dentists, followed by indirect composite resins
(1.9%)(Figure 1). Regarding the type of direct composite, nano-hybrid resins were selected by 74.5% of
the dentists, followed by microhybrid chosen by 13.8%, condensable preferred by 11.9%, whereas,
microfilled resins were preferred only by 1.9% of the professionals (figure 2). Eighty-nine percent of the
dentists did not use rubber dam isolation in daily practice for placement of posterior restorations, 5%
never used rubber dam and 6% used it occasionally. When comes to curing, the majority (42.1%)
preferred curing for 10 seconds and when given a choice between halogen and LED for curing light,
almost all preferred LED. 15 Seconds was the average etching time the majority of dentists (72.7%)
preferred. When comes to the use of liner or base, 70.4% chose it based on the requirements of the case,
only 28% used it always irrespective of the case.
Table 1 summarizes the association of restorative procedures and the years of experience in clinical
practice of dentists. No significant association between the variables was observed. Table 2 summarizes
the association of restorative procedures and the level of specialization of dentists. Most participants did
not use rubber dam; the study did not show any significant differences in non-usage of rubber dam
between specialists (75.9%) compared with non-specialists (90.4%).
Discussion
To the best of our knowledge, this is the first study in Palestine examining the attitude of dentists
towards preferences of materials for posterior restorations. We observed that the majority of the dentists
preferred composite over amalgam; this in accordance with various studies, where, composite was seen
as the material of choice for posterior restorations. In a similar study conducted in the United Kingdom,
the majority of dentists surveyed placed load bearing posterior composite restorations regularly [16]. Their
choice of restorative material was influenced by clinical indications and the patient's aesthetic demands. It
was also seen that the techniques used were appropriate, although there was confusion around the need
for rubber dam and the most appropriate method to line the cavity.
Another study conducted in Brazil showed that for the majority of dentists direct composite was the
first choice for posterior restorations and the use of rubber dam for composite resin placement in posterior
teeth was not frequent. However, in this study, it was seen that microhybrid was the preferred type of
composite and time since graduation and level of specialization affected dentists’ choices [17]. However,
in our study, we observed that clinical experience and postgraduate study did not have an influence on
the material choices. This can be due the increased attitude of the dentists to prefer composite universally
[18, 19], irrespective of training or experience. It has been considered that a growing number of dentists
are restricting their practices to the use of composites as opposed to amalgam in the UK [18], US [19]
and Europe [20, 21, 22]. Composites offer a number of advantages over amalgam in the restoration of
posterior teeth. Among these are the ability to achieve an aesthetically pleasing restoration, the need to
remove less tooth structure because adhesive technology is being employed, and reduced microleakage
by using bonding agents. Other problems, such as the poor wear resistance of early composite materials,
appear largely to have been overcome, with a reduction in the size of filler particles leading to improved
polishability and higher filler loading values [23].
In our study, it was seen that the dentists preferred nanohybrid. This can be attributed to the
improved material properties such as better polishability and strength. According to Mitra et al, nanofilled
composites had mechanical properties similar to hybrid composites and polishability and esthetics equal
to microfilled composites [24]. This was followed by a preference for microhybrid composites as they are
considered universal materials and may be used in both anterior and posterior teeth, as they imbibe both
the mechanical properties of hybrid composites and the polishing characteristics of microfilled composites
[5, 13, 14]. The very less preference of microfilled composites among the dentists might be attributed to
its properties such as reduced physical strength which prove insufficient in stress-bearing areas.
However, due to their high polishability, they are used in anterior teeth or Class V restorations in posterior
teeth.
With regards to the usage of rubber dam, rubber dam usage is seemingly low as indicated in many
studies. A survey showed that 73, 63, and 55 percent never or seldom used a rubber dam when placing
amalgam, anterior, or posterior direct resin composite restorations, respectively [25]. Similarly another
study showed that 53, 45, 39 percent of the dentists never used a rubber dam when placing amalgam,
anterior, or posterior direct resin composite restorations, respectively [26]. In a study by Edward Hill, the
reasons for infrequent usage for rubber dam was probed into, the most common reasons were the
following: inconvenience (40 percent); unnecessary (28 percent); other (12 percent); patient refusal (11
percent); and time (9 percent) [27].
The limitation of the study is the cross-sectional nature of the data. Future studies should conduct
research with a larger sample, and evaluate the effect of bias of previously perceived notions of the
dentists. Longitudinal studies evaluating the attitudes and preferences over longer periods of time will
help in concluding the results better.
Conclusions
The study shows that composite was the preferred material for posterior restoration among the
Palestinian dentists, with nano-hybrid being their preferred type of composite. However, these dentists
seldom used rubber dam and their postgraduate training or time of training did not influence their
material choices. This study emphasizes the rising trend among the dentists to prefer composite over
amalgam and the gradual demise of amalgam usage in dentistry. The present reduced usage of rubber
dam is, however, unwarranted and the dental educators and organizations should implicate better
means to improve its popularity among dentists.