Table 1.

Summary of the most common human root malformations as against potentially affected processes of root development.

Root malformation	Processes of root formation
	Hertwig's epithelial root sheath				Dentinogenesis	Formation of furcation
	Formation (crown-root transition)	Apical proliferation (root elongation)	Induction of odontoblast differentiation	Disintegration, cementogenesis		Epithelial bridge formation	Interradicular dentinogenesis, cementogenesis
Short roots due to
direct trauma	Unaffected	Disrupted	Disrupted	Continues	Disrupted	n.a.a	n.a.a
radiotherapy	Unaffected	Disrupted	Disrupted	Continues	Continues	Delayed	Unaffected (?)
chemotherapy	Unaffected	Disrupted	Disrupted	Continues	Continues	Delayed (?)	Unaffected (?)
Root dilaceration	Delayed (?)	In wrong direction	Unaffected	Unaffected	Unaffected	Unaffected (?)	Unaffected (?)
Taurodontism	Unaffected	Unaffected	Unaffected	Unaffected	Unaffected	Delayed	Unaffected
Short root anomaly	Unaffected	Impaired	Unaffected	Unaffected	Unaffected	n.a.a	n.a.a
Root malformation with CMD	Unaffected	Impaired	Unaffected	Unaffected	Mechanically impaired	Disturbed	db: disrupted cc: excessive
Double teeth	Unaffected	Unaffected	Unaffected	Unaffected	Unaffected	n.a.a	n.a.a
Regional odontodysplasia	Unaffected	Impaired	Unaffected (?)	Unaffected	Impaired	Impaired	Impaired (?)
Hypophosphatasia	Unaffected	Unaffected	Unaffected	Disd: unaffected (?) ace: impaired ccf: unaffected (?)	Impaired (?)	Unaffected	Impaired (?)
Dentin dysplasia type I	Unaffected	Impaired	Unaffected	Unaffected	Mechanically Impaired	Impaired (?)	db: mechanically impaired

^anot applicable, because malformation largely occurs in single rooted teeth;

^bd, dentinogenesis;

^cc, cementogenesis;

^ddis, disintegration;

^eac, acellular cementum formation;

^fcc, cellular cementum formation.