Prepared By

Dr.Yamen Nouh

BDS, DIP-ANT

Anatomical variations ofMental nerve

Who may be interested?

Oral surgeons Dental implantologists

Digital radiology lab’s

guided implantology lab’s

General practioners

Radiologists

1- Mand. Incisive canal

Radiographic expression

Occurrence rate in literature

- occurrence 11 to 92% of cases pending the examination method used (so it is not uncommon!!)- Panoramic radiographs have the least accuracy (11%)

2- Ant. Loop of mental nerve

Radiographic expression

Occurrence rate in literature

Solar et al. detected an AL in 60% (22 of 37) of dissected cadaver mandibles, ranging in length from 0.5 to 5 mm (mean 1 mm).

Neiva et al. reported the AL was present 88% of 22 cadavers and its length ranged from 1 to 11 mm (mean 4.13 mm).

Rosenquist detected AL in 24% (15 of 58) of cadaveric mandibles with loop length variations from 0 to 1 mm.

Seems to be not uncommon as well!!!

3- Accessory mental foramen

Accessory mental nerve (Triple)

Occurrence rate in literature

Gershenson et al. (1986) who examined 525 dry mandibles reported that 4.3% mandibles had double mental foramina, and 0.7% mandibles had triple mental foramina. Finally they found one mandible that had four mental foramina on one side (0.1%)

Serman (1989) examined 408 dry human mandibles and found one extra foramen on one side in seven mandibles constituting 1.7%.

Sawyer et al. In 1998 reported 5.9% accessory mental foramen in four ethnic groups.

Katakami et el. (2008) examined 150 patients retrospectively with limited cone-beam computed tomography and depicted 16 double foramina (10.6%) and triple mental foramina on one side (0.6%)

- A double mental foramen appears in approximately 1% in Egyptians.- Which means that one of this will visit your clinic someday.

4- Absence of mental foramen

Occurrence rate in literature

- THIS IS ULTIMATELY RARE.

5- Position of mental foramen

Occurrence rate in literature

- It varied from mesial to the 1st premolar apex to below the 1st molar apex.- It is very uncommon to pass mesially the apex of the canine.

RACE

- in Mongoloid population, the mental foramen was located in line with the longitudinal axis of the lower second premolar teeth.

- In Caucasians, the mental foramen was more medially located, between first and second premolar.

- in Black populations it was found to be more posterior, between second premolar and first molar.

Why should I know about these variations?

To avoid X-ray misdiagnosis..

Better implant planning..

To better expect and manage surgical complications..

references

Juodzbalys G, Wang HL, Sabalys G. Anatomy of Mandibular Vital Structures. Part II: Mandibular Incisive Canal, Mental Foramen and Associated Neurovascular Bundles in Relation with Dental Implantology. J Oral Maxillofac Res 2010 (Jan-Mar);1(1):e3.

Anwar Ramadhan, Elias Messo, Jan-Michaél Hirsch. Anatomical Variation of Mental Foramen. A case report. Stomatologija, Baltic Dental and maxillofacial Journal, 12: 93-6, 2010.

Tabinda Hasan. Bilateral caroticoclinoid and absent mental foramen: rare variations of cranial base and lower jaw. ITALIAN JOURNAL OF ANATOMY AND EMBRYOLOGY (IJAE). Vo l. 118, n . 3: 28 8 -297, 2013.

Tabinda HASAN, Mahmood FAUZI, Deeba HASAN. Bilateral absence of mental foramen – a rare variation. International Journal of Anatomical Variations (2010) 3: 167–169.