Summary:
•Purpose: to summarize prevalence and etiology of accessory roots and root canals in anterior teeth, clinical and radiographical detection by conventional and contemporary tools, and treatment modifications and clinical outcome.
•Materials/Methods:
•Electronic search for articles published in Jan. 1970 to Nov. 2014 in 5 major endodontic journals; Australian Endodontic Journals, Dental Traumatology; International Endodontic Journal, Journal of Endodontics, and Oral Surgery Oral Medicine Oral Pathology.
•n: 86 Inclusion criteria; exclusion criteria:
Table.1
Highlights:
•Maxillary anterior teeth:
•Most common root canal configuration is type IV (2-2) mostly in M-D direction
•Mandibular anterior teeth:
•More complex root canal configuration than their maxillary counterparts •Most common root canal configuration is type IV (2-2) and type V (1-2) mostly in labiolingual direction
•Dense invaginatus:
•invagination of the enamel organ into the dental papilla prior to calcification Prevalence: ranges from<1% to > 26%
•Types:
•1- Type I: Most common; confined enamel form to the crown and do not extend to the CEJ
•2- Type II: Confined enamel form extend to the root as a blind sac ± pulp communication. Radiographic appearance is a RL tear drop shape surrounded by RO border
•3- Type III: The invagination perforate the root showing a second foramen; cementum is frequently found; no immediate communication to the pulp. Radiographic appearance is a blunderbuss opening to the PDL (pseudo canal)
•Found mostly maxillary lateral > maxillary central > mandibular incisors and canine

Highlights:
•Palato-gingival groove (radicular lingual groove; disto-lingual groove): •Prevalence: ranges from <1% to >18% •Primary maxillary canine has more prevalence of Double roots than their mandibular counterparts
Strengths: Overview of accessory roots’ prevalence, canal configuration type, radiographic appearance and treatment options.
Weakness: Did not state the sample size directly instead presented it in tables and inter/intra reviewer reliability were not mentioned.