الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Dental caries is the most common chronic disease worldwide. It is a complex multifactorial disease that involves the interaction of many risk factors. It negatively affects the quality of life of individuals and causes a huge economic burden due to treatment expenses as well as decreased productivity.
On the other hand, black stain is a special type of extrinsic discoloration that appears as dark, discrete dots or lines on the enamel surface, and is commonly seen in pediatric patients. Children with this type of discoloration has been frequently reported to experience less dental decay.
This systematic review aimed to confirm if there is a relationship between the presence of black stain in primary teeth and the prevalence or the severity of dental decay, by systematically reviewing available literature, and performing meta-analyses.
A preliminary search was done to identify relevant databases, and optimize the search strategy. Afterward, a systematic search was conducted in the following databases: (PubMed, Web of Science, Scopus, Google Scholar, OpenGrey, and Egyptian Universities Libraries Consortium). Additionally, reference lists of all eligible records were searched manually.
Inclusion criteria were:
• Observation studies (cross-sectional, case-control, retrospective cohort, or prospective cohort).
• Studies assessing primary teeth.
• Studies reported in the English language.
• Studies having the following PECOs:
Population: Children with primary or mixed dentition.
Exposure: Black stains of any amount or extent related to primary teeth.
Comparators: Children without dental black stains.
Outcomes: Caries prevalence or severity
Exclusion criteria were:
• When caries parameters are not described in terms of the type of dentition.
• Self-report of dental caries or black stains.
• Studies that were conducted on unhealthy children.
• Types of studies other than those specified.
No time restrictions were applied, since publication date was not going to jeopardize the validity of the findings. Both initial and full-text screening of the studies against the eligibility criteria, were done by two independent investigators each, and disagreements were resolved by a third investigator.
Information regarding authors, date of publication, study type, number of participants, age of participants, country, setting, prevalence of BS in the sample population (for cross-sectional studies), and effect size measures for children with and without BS were extracted from each of the included studies into predesignated forms.
A modified version of Downs and Black checklist was used to assess the methodological quality of the studies included. Data extraction and quality assessment were also done by two reviewers independently, and disagreements were resolved by a third reviewer.
In this systematic review, 1970 records were identified. After removal of duplicated records 1424 records were assessed for eligibility. Twelve relevant studies met the inclusion criteria. Seven of which were cross-sectional studies, five were case-control studies, and no cohort studies were identified. Seven studies reported caries prevalence (tooth-level outcome measures), two studies reported caries severity (surface-level outcome measures), two studies reported both, and one study reported the percentages. None of the studies were excluded on grounds of methodological quality, but two of the twelve studies were further excluded from the meta-analyses due to the difficulty of analyzing their results.
There was a statistically significant association between the presence of BS and lower prevalence of dental caries (Random effects model: MD [95% CI]: –0.98 [–1.54; -0.42]; I2 = 79%; p < 0.01; τ2 = 0.44). There was also a statistically significant association between the presence of BS and lower severity of dental caries (Fixed-effect model: MD [CI]: –1.12 [–1.57; -0.68]; Random-effects model: MD [95% CI]: –2.34 [–4.23; -0.44]; I2 = 85%; p < 0.01; τ2 = 2.93).
There was a considerable degree of heterogeneity between the studies, and publication bias is suspected; however, the small number of studies did not allow for further investigations.