Literature Review Writing 2021: How to write a review of Literature fast WITH example in 30 minutes. (Ways to find literature to review)
Welcome, you were probably redirected here from YouTube to view an example of a literature review. However, if you are not from YouTube, you need to click here and watch the video first.
I promised several things in that video, one of which is a template that I use for my data extraction. I apologise for the nature of this website, there will be an upgrade soon. You can copy the template or modify it. Use either excel, word doc or google docs but I love excel best.
Now to the example I promised, just scroll down and read through. That was the chapter 2 for my masters thesis, so don't bother thinking about copying it. It won't end well. This is the first example, the link to the second example is in my YouTube description box. Make sure to head back there and check it out.
CHAPTER
TWO
LITERATURE REVIEW
Dental
caries remains a major global health problem with a skewed distribution and
massive economic and health implications (Balaji, 2018). For the prevalence to
be controlled, there is a need to determine the effectiveness of the commonly
used fluoridation technique, particularly in the low and middle-income
countries where funding is of utmost importance. Over the years, researchers
have tried to reduce the prevalence of dental caries with various fluoridation
methods of which water fluoridation and fluoridated toothpaste are the most
common. These techniques have been applied in various settings like schools,
communities and families (Innes and Robertson, 2018; Kapoor,2014).
Iheozor-Ejiofor
et al. (2015) conducted a systematic review on water fluoridation for the
prevention of dental caries. Iheozor-Ejiofor et al. (2015) included a total of
155 studies in the review while 107 of the studies had sufficient data for
quantitative synthesis. Although with very little contemporary evidence meeting
the inclusion criteria. The result showed that the introduction of water
fluoridation caused a reduction in caries severity. However, 71% of these
included studies were conducted before 1975 and the widespread use of fluoride
toothpaste. There might have been temporal changes in the effect because of
changes in several factors. Also 97% of the studies had high risk of bias and a
significant between-study variation. There is insufficient evidence to evaluate
the effect of stopping water fluoridation will have on caries level. The
reviewers stated that the observational nature of the study designs limits the
confidence level in the size of the effect estimated.
Putting
into consideration the effect diet has on dental caries, Armfield et al. (2013)
compared the association between sugar-sweetened beverage (SSBs), dental caries
and water fluoridation among children in Australia between ages 5 to 16 years.
The aim of the study was to determine whether exposure to water fluoridation
modifies the effect of SSBs on dental caries. The study used a stratified
clustered sampling method involving 16,508 children. Their caries activity was
assessed by dental staffs and the study utilized a questionnaire filled by
parents to gather other history of sugar consumption about the child. The use
of a questionnaire exposes the study to bias because of self-reporting. The
study confirms the effectiveness of water fluoridation even though consumption
of SSBs is a major risk factor for dental caries. Increased exposure to fluoridated
water decreased the association between SSBs consumption and dental decay.
The effectiveness of water
fluoridation even in high-risk caries areas was confirmed in a cross-sectional
study conducted by Koh et. al (2015) evaluated the pre and post-water
fluoridation effect on caries experience in primary dentition in a
community-based setting. The pre-fluoridation group consisted of 201 children,
age 4.0 to 9.9 years that were randomly selected while the post-fluoridation
consisted of 256 children of the same age range and data gotten from the same
clinic. However, it was not stated if the post-fluoridation group were randomly
selected and, the sex distribution was not indicated. The period between
pre-fluoridation (1998 to December 2008) and post-fluoridation (January 2011 to
December 2012) is wide as factors may have changed over time. The dental caries
prevalence and experience was measured using the DMFT/dmft index which is a
valid standardised tool by the World Health Organization for use in epidemiological
studies (Khamis, 2016). The study was single-blind peer reviewed with only one
reviewer. The study concluded that water fluoridation caused a reduction in
caries prevalence from 87% to 75% and a 19% drop in caries experience. These
are quite significant. However, this study was done in a community in
Australia, therefore cannot be generalised worldwide.
The frequency of dental
healthcare services following water fluoridation was also used to assess the
effectiveness of water fluoridation. Cho et al. (2016) conducted a cohort study
on healthcare utilization for dental caries based on implementation of dental
care services in North Korea. The sampling data used in the study was from the
national health insurance to evaluate the impact of water fluoridation on the
nation. The study concluded that the implementation of water fluoridation is
associated with reduction in the utilization of dental health care services and
improved oral health especially dental caries. However, there was no specific
data indicating the reduction in severity of dental caries or the tool used to
measure the caries in the sample. Furthermore, other factors that could affect
health outcomes like type of toothpaste, frequency of tooth brushing, and
lifestyles were not considered. The fluoride level in the water and actual
volume consumed were not considered. The data included 472, 250 patients but
the gender of these patients were not revealed. The study was carried out in
North Korea. Therefore, it cannot be generalised to the rest of the world.
Aside the dental service
utilization, an Iranian study has shown that age-sex specific and
sequela-specific disability-adjusted life years (DALYs) resulting from dental
caries is preventable through water fluoridation. The result of this study by
Abtahi et al. (2018) showed that approximately 20% of the national dental
caries DALYs were preventable by water fluoridation. The data on burden of
disease resulting from dental caries extracted from the Global Burden of
Disease study in 2016. The limitation of estimated data values from this
database also applies to this study. Also, certain sequela like difficulty in
eating because of tooth loss is not limited to dental caries only, as
periodontal disease may be the cause. The result gotten from this study is an
indication of the role water fluoridation plays in promoting dental public
health and compensate inequality at a national level.
An inequitable effect of
community water fluoridation on dental caries was demonstrated in the study by
McLaren et al. (2016a) in Calgary, Canada. The study compared socioeconomic
patterns of dental caries in children during a period of fluoridated water
supply (2009/2010) and following its discontinuation (2013/2014). The study
recorded increasing inequality in dental caries following discontinuation of
community water fluoridation. Although, the study had limited socio-economic
information available at both point in time (before and after cessation)
There had been so many debates
about cessation of water fluoridation and its effect with several countries
going ahead to implement it. McLaren et al. (2016b) explored the short-term
implication of water fluoridation cessation on dental caries in Alberta, Canada.
A pre-post cross-sectional study design was used involving grade 2
schoolchildren in 2004/2005 and 2013/2014 in two similar cities within Alberta.
This affected potential cofounders being ruled out because the comparative
analysis used pre-cessation data taken several years before cessation data was
collected. Furthermore, no data was collected on inter-examiner or
intra-examiner reliability even though the assessment team was reported to have
had extensive training and calibration. The result showed increased caries
activity in primary teeth during the cessation period. The dental caries
activity in permanent teeth was not worsened but this could be because of the
short-time frame of the study.
Similar to the result of water
cessation in the study by McLaren et al. (2016b), Seppa, Karkkainen and Hausen
(2000) conducted a study on the change in dmft score following cessation of
water fluoridation. It was a cross-sectional survey of two communities. One
community had never received fluoridated water supply while the other community
stopped water fluoridation in 1992 (after using since 1959). Although it was
difficult to draw conclusion because of the study design used. The caries score
was higher in the community that had previously been receiving fluoridated
water than the community that never did. This is an interesting result as it
would have been expected that the community who never received water
fluoridation should have higher caries rate.
From an economic perspective, Ran and Chattopadhyay (2016) conducted a systematic
review to determine if the intervention is of any cost benefit. 564 studies
were identified between 1995 and 2013 but only 10 studies met the inclusion
criteria. The result indicates that the economic benefit of water fluoridation
exceeds other intervention cost. However, there might have been an
underestimation of the costs and benefit because of the nature of the
intervention which resulted in estimation of the both values.
The most common adverse effect
of water fluoridation is dental fluorosis. This has been the main reason for
cessation of the intervention in some countries like China. Firmino et al. (2018) conducted an ecological
study to determine the relationship between dental caries, dental fluorosis and
water fluoridation among 12-year-old school children in Brazil. The survey took
place between 2009 and 2010 involving 7328 twelve-year olds of both gender. The
research showed a lower prevalence of dental caries with optimally fluoridated
water. However, the ecological study design limits the application of finding
at individual level but may be useful for international data comparison.
Furthermore, other sources of fluoride exposure like toothpaste were not
controlled
In
assessing the effectiveness of fluoride toothpastes, a systematic review and
meta-analysis of varying concentration of fluoride toothpaste for the
prevention of dental caries in children and adolescent was conducted by Walsh
et al. (2010) and included randomised controlled trials and cluster-randomised
controlled trial study design. 75 studies were included in the review while 66
of these studies met the meta-analysis criteria with publication date ranging
from 1955 to 2008. However, many these studies were categorised as 'unclear'
because they failed to give adequate information on the method of randomisation
and process of treatment allocation. Generally, the studies were largely
bias-free except for randomisation and allocation concealment. The result of
the meta-analysis showed that the preventive effect of fluoride toothpaste
against dental caries is increased significantly with higher fluoride
concentration. The review also had few studies examining the effect in
deciduous dentition.
A RCT conducted by Tickle et
al. (2017) to prevent children from becoming caries active over a 36-month
period. Randomisation was done using computer-generated random numbers and
there was allocation concealment. Total
of 1248 children were recruited but 1096(549 intervention and 547 control) were
used in final analysis. The interventions were fluoride varnish, toothbrush,
50ml tube of 1450ppm fluoride and standardized oral hygiene instructions while
the control was advice only. Examiners bias was avoided because the external
examiners were calibrated and blinded to the study groups. The result showed
that 34% of the intervention group became caries active compared to 39% in the
control group. More significantly, the
caries activity measured by the standardised dmft index in the intervention
group was 7.2 while it was 9.6 in the control group. However, the study failed to evaluate if the
children were caries-free but showed a slow caries progression in those who had
caries.
Petersen et al. (2015)
conducted a non-randomised controlled trial in a two-year school-based intervention to assess oral
health promotion program combined with supervised tooth brushing using a
toothpaste containing 1450ppm fluoride concentration. A total of 3,706
pre-school children were recruited from 15 south Thailand schools: 8 schools
consisting of 1,766 children as controls and 7 schools with a total of 1,940
children belonged to the intervention groups. The intervention schools were
further classified into cooperative schools (5) and non-cooperative schools (2)
based on their adherence and participation to the tooth brushing activities.
The sex distribution was not stated. The study documented a significant effect
from use of fluoridated toothpaste with approximately 41% caries incidence
reduction in the cooperative schools.
A randomised clinical study by
Newby et al. (2013) to compare the effect of three varying concentration of
fluoride toothpaste to placebo in halting dental caries progression. The
varying concentration were 1,426 ppm fluoride, 1000 ppm fluoride, 500ppm
fluoride and 0ppm fluoride (placebo). It
was a single-blind, crossover study involving 55 subjects, 24 males and 31 females
within the age range of 11 to 14 years. The test result showed that all three
concentration of fluoride toothpaste increased enamel remineralisation,
fluoride uptake and acid resistance following a single brushing thereby capable
of preventing caries progression. However, the duration immediate effect seen
in this study is somewhat questionable. There is a conflict of interest as four
of the nine authors are employees of GlaxoSmithKline Consumer Healthcare, a
company that funded the study.
Another systematic review
conducted by Wright et al. (2014) confirmed the efficacy of fluoride toothpaste
in children younger than 6 years old. The reviewed further showed a decrease in
fluorosis when fluoride toothpaste was commenced after the age of 2 years. The
review includes 17 clinical trials and not RCTs. The result gotten from this
review may not be generalised to all children as most of the studies were
conducted in high risk populations. Another limitation in this review is that
the studies included were at high risk of bias because of the study designs.
Fluorosis as an adverse effect
of fluoridation is commoner in water fluoridation than fluoride toothpaste. In
measuring fluorosis in Mexican children, Molina-Frechero et al. (2015)
evaluated 239 students. Mean age was 11 ± 0.82 and 51% were male. More than
half of the population had a type of fluorosis. 29.3% had very mild fluorosis,
20.9% had mild fluorosis, 6.7% had moderate fluorosis while 2.1% had severe
type of fluorosis. The mean fluorosis score was 0.887 ± 0.956. The study
concluded that the association between frequent brushing using toothpaste high
in fluoride concentration and lack of parental supervision during toothbrushing
may be a contributing factor to the severity of fluorosis. However, one
limitation of the study is that the data used to determine frequency of
brushing, type of toothpaste and supervision during study was obtained from a
questionnaire filled by the parent. The data collected is prone to self-report
bias. Additionally, the study was conducted for a small fraction of Mexico children
and cannot be generalised to the rest of the world. Contrary to the findings of
Molina-Frechero, a review by Pretty (2016) presented available evidence to
promote the use of high concentration of fluoride in toothpaste particularly in
high caries risk children. The systematic review showed good level of support
to toothpaste up to 2800ppmF.
Several literatures have
explored either water fluoridation or fluoride toothpaste and has found them
effective against caries prevention. Various concentrations have also been
explored with several conclusions been drawn. Majority of the reviews available
on water fluoridation and fluoride toothpaste made use of studies that were
conducted several decades ago. However, there is no review that has evaluated their
effectiveness using studies done within the last decade. There is a need fro a
review that can be related to the state of this present society. As the two
most popular and commonly used form of fluoridation, it is important to compare
their effectiveness against dental caries prevalence as it will help health
policy and decision makers make informed decisions.
Don't forget to head back to YouTube for the second example. Cheers.
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