|Inclusion Criteria||Exclusion Criteria|
1. Observation studies (cross-sectional, case-control, retrospective cohort, or prospective cohort).|
2. Studies assessing primary teeth.
3. Studies reported in the English language.
4. Studied having the following PECOs:
a. Population: children with primary or mixed dentition.
b. Exposure: black stains of any amount or extent related to primary teeth.
c. Comparators: children without dental black stains.
d. Outcomes: Occurrence of dental caries, number of teeth affected, number of surfaces affected.
1. Studies where caries parameters are not described in terms of the type of dentition.|
2. Self-reported dental caries or black stains.
3. Studies that were conducted on medically compromised or institutionalized children.
4. Case-reports and case-series.
5. Editorials, and commentaries.
6. Secondary literature sources (such as books or reviews)