title: Dental crowding as a caries risk factor: a systematic review.
abstract: BACKGROUND
  The association between dental crowding and dental caries has long been accepted because of increased food accumulation and plaque retention in areas of crowding. The aim of this review was to evaluate this potential causal relationship systematically.
  
  
  METHODS
  Six electronic databases were accessed, supplemented by manual searching of the references of the relevant retrieved articles, peer-reviewed orthodontic journals, and gray literature. Search terms included caries, decay, crowding, and irregularity. Non-English articles were excluded from the review in the study-selection stage. Data extraction and evaluation of primary studies were performed independently by 2 reviewers.
  
  
  RESULTS
  The initial search retrieved 6914 citations. However, only 18 articles met the inclusion criteria. The qualitative systematic review included 8 studies, with articles of low or moderate quality. No association between crowding and caries was reported in 4 studies, a significant negative correlation was found in 2 studies, 1 study showed a direct and significant relationship, and another study showed a positive association in the mandibular anterior region but an inverse correlation in the maxillary posterior region.
  
  
  CONCLUSIONS
  To date, there are no high-quality studies to resolve the possible association between dental crowding and caries; further high-quality longitudinal studies are needed to clarify this relationship.
authors.affiliation: Department of Orthodontics, Oral and Dental Research Division, National Research Center, Giza, Egypt.
authors.forename: Hend Salah
authors.initials: HS
authors.lastname: Hafez
authors.forename: Sherif Mohamed
authors.initials: SM
authors.lastname: Shaarawy
authors.forename: Ahmed Awadh
authors.initials: AA
authors.lastname: Al-Sakiti
authors.forename: Yehya Ahmed
authors.initials: YA
authors.lastname: Mostafa
mesh_terms: D003731:Dental Caries / Q000209:etiology*; D003773:Dental Plaque / Q000209:etiology; D006801:Humans; D008310:Malocclusion / Q000150:complications*; D012307:Risk Factors