Dens invaginatus. Part 1: classification, prevalence and aetiology.

By Alani A, Bishop K.

Date: 05/2009
Journal: JOE

Summary:  

•Purpose: To review etiology, prevalence, and classification of dense invaginatus and its morphology and nomenclature.

Highlights:

•Developmental anomaly that results from invagination of the enamel organ to the dental papilla prior to calcification.

Dens invaginatus was named by this term to describe the infolding of enamel into dentine to form pocket or dead space Fig.a.

•Other terms have been suggested such as dense in dent; describing the tooth within tooth appearance, dilated composite odontome; informs the dilation of dental papilla, and gestant anomaly.

Classification:

•The most commonly used classification is Oehlers’s classification divided in to 3 types based on radiographic appearance of the invagination extension to the root.

Type I:  Confined to the crown doesn’t extend beyond CEJ Fig.1.

Type II: Extends to the pulp chamber doesn’t communicate with the PDL Fig.b and Fig.2.

Type III A: Extends through the root; communicate with the PDL through pseudo foramen; no communication to the pulp. Fig.3

Type III B: Extends through the root; communicate with the PDL through the apical foramen; no communication to the pulp. Peri-invagination periodontitis can occur in class III if there any infection in dense invaginatus. Fig.4

•Commonly found: Type I > Type II > Type III

Prevalence:

•Observed in 0.25% to 26.1% •Most affected tooth is max lateral incisor

Etiology:

•Stimulation of ingrowth of enamel organ cells

•Retardation of focal groups of cells

•External forces such as; trauma, infection, and adjacent tooth germ

Genetic

•Nature of the invagination:

•Invagination contains remnant of dental papilla and periodontal connective tissue which becomes necrotic and nutritious environment for bacteria

•Dense invaginatus complicates the canal morphology (irregular cross section and wave like constriction and dilation) Fig.4.

•Invagination surface has defected enamel with different chemical structure than normal enamel (absence of magnesium and ↑↑ calcium and phosphate ions); acts as a direct bacterial portal to the pulp

Conclusion:

•The condition is associated with an increased prevalence of pulp disease and that any necessary endodontic treatment may be difficult because of aberrant anatomy