Classifications of mandibular canal branching: A review of literature

Table 1 Classifications of mandibular canal branching (1971-2010)

Ref.	Exam	Sample	Prevalence (mandibular canal branching)	Classification	Frequency of the types	Region of origin	Aspect	Direction	Local of termination
Carter et al[10] (1971)	Unilateral radiographs and dissection	80	38.75%	Type I	61.25%	Ramus region, from a single Mandibular Foramen	Single large structure with very short dental branches	Superior to the tips of molars roots	Mental arborization
				Type II	13.75% (types 1 or 2)	Ramus region, from a single Mandibular Foramen	Substantially lower down, with dental branches given off more posteriorly, longer and oblique	Oblique, toward the tips of molars roots	Mental arborization
				Type III	25% (types 2 or 3)	Ramus region, from a single Mandibular Foramen	Two large branches initiated posteriorly	Uppers like alveolar branches	Upper to the tips of the roots; Lower to mental forame
Nortjé et al[1] (1977)	Panoramic radiographs	3612	0.9	Type Ia	30.3% of duplication cases	Ramus region, from a single Mandibular Foramen	Two canals of a similar width (lower slightly narrower)	Inferior narrower
				Type Ib		Ramus region, from a single Mandibular Foramen	Double (Superior narrower)	Anterior
				Type II		Ramus region, from a single Mandibular Foramen	Duplo (Superior shorter)	Anterior	Superior: toward 2nd and 3rd molars and inferior: toward mental foramen
				Type III		Ramus region, from separated Mandibular Foramens	Double (Join in the molars region)	Anterior	Molars region
Nortjé et al[9] (1977)		3612		Type IV		Ramus region, from a single Mandibular Foramen	Double (Superior narrower than the main canal)	Anterior	Ramus region
Langlais et al[11] (1985)	Radiografias panorâmicas convencionais	6000	0.95	Type I	38.6%	Ramus region, from a single Mandibular Foramen	Double (Superior shorter)	Anterior	3rd molar and adjacente region
				Type II	54.4%	Ramus region, from a single Mandibular Foramen	Double (Joining anteriorly)	Anterior	Ramus or mandibular body regions
				Type III	3.5%	Ramus region, from a single Mandibular Foramen	Double (Combination of types II and III)	Anterior	Ramus, retromolar ou 3rd molar regions
				Type IV	3.5%	Ramus region, from separated Mandibular Foramens	Double (Joining anteriorly)	Inferior	Ramus region
Kieser et al[12] (2005)	Oclusal and unilateral radiographs and dissection	107 mandibles (25 radiographic exams)	0%	Type I (detected by mean of dissections and radiographs)		Ramus region, from a single Mandibular Foramen	Single, without branches	Anterior	Mental foramen region
				Type II (detectado em dissecações)		Mandibular body region	Series of individual branches	Superior	Alveolar process (Edentulous mandibles)
				Type III (detectado em dissecações)		Molars region	Molar plexus	Superior	Molar region (Edentulous mandibles)
				Type IV (detectado em dissecações)		Distal and proximal regions	Distal and proximal plexus	Distal plexus forward. Proximal plelxus toward superior	Alveolar process (Edentulous mandibles)
Naitoh et al[15] (2009)	CBCT	122	65%	Type I Retromolar	29.8%	Ramus region	Superior	Superior	Retromolar region
				Type II Dental Canal (3º molar)	7%	Ramus region	Superior	Anterior	Root Apex of the third molar
				Type II Dental Canal (2º molar)	1.8%	Ramus region	Superior	Anterior	Root Apex of the second molar
				Type III Forward Canal (with confluence)	4.5%	Ramus region	Superior (Joining to the main canal)	Anterior	Mandibular body
				Type III Forward Canal (without confluence)	55.3%	Ramus region	Superior	Anterior	Mandibular body
				Type IV Buccal or lingual canal	1.8%	Ramus region	Lateral	Inferior (Buccal or lingual)	Ramus region
Kuribayashi et al[14] (2010)	CBCT	301 unilateral exams from 252 patients	15.60%	Less than 50% of the diameter of the main canal	51%		Narrower (Less than 50% of the diameter of the main canal)
				Equal or bigger than 50% of the diameter of the main canal	49%		Equal or bigger than 50% of the diameter of the main canal

CBCT: Cone beam computed tomography.