The Morphology of Impacted Maxillary Central Incisors: A Systematic Review

Background and Objectives: The knowledge of the morphology of impacted maxillary central incisors may lead to more effective treatment. Therefore, this systematic review aimed to evaluate the morphology of impacted maxillary central incisors and compare them with contralateral teeth. Material and methods: This systematic review adhered to the PRISMA statement. The literature search was carried out using PubMed (Medline database), Cochrane Library, ProQuest, Web of Science and Science Direct electronic databases with no publication date restrictions up to July 2021. Data assessing the morphology of unilaterally impacted maxillary central incisors (ICI) evaluated with CBCT were extracted, and the quality of the studies was evaluated. Crown length, root length, and root dilaceration of impacted maxillary central incisors were compared with contralateral unimpacted teeth. Results: The initial database search identified a total number of 287 studies. After applying the selection criteria, 21 articles were selected for a full-text analysis, and four retrospective studies involving 205 patients were included in the systematic review. According to the Newcastle-Ottawa Scale (NOS), two of included articles were graded as "Good" and the remaining two as "Fair" quality. The results showed no difference between impacted teeth and their contralateral crowns, or a minor decrease in ICI crown length (from 0.15 to 0.56 mm). The root lengths of impacted maxillary central incisors were considerably shorter than contralateral incisors (from 2.13 to 3.22 mm) and, as dental age increased, root growth decreased and the incidence of root dilaceration was more frequent. Conclusions: The root lengths of impacted maxillary central incisors were considerably shorter compared to the contralateral incisors. Root dilacerations frequency and severity increased as dental age increased.