Nerve injury in dentistry

Made by : Dr. Saya Mustafa Oral surgery department

1. Nerve supply 2. What is nerve injury ?3. Most common injured nerves4. Sign & symptoms5. Classification 6. Etiology7. Prognosis 8. Treatment

Content :

It has 3 branches : 1. opthalmic V1->sensory root 2.Maxillary V2-> sensory root 3.Mandibuler V3 -> sensory and motor roots

Trigeminal nerve V

1. Branchiomotor Component: controls the muscle of facial expression that has 5 branches : Temporal , zygomatic , buccal , mandibuler and cervical .

2. The special sensory component: fibers are carried by chordo tympani join the lingual nerve provide taste sensation to anterior 2/3 of tongue

Facial nerve VII

Nerve injury is most serious complication that may occur during oral surgical procedures especially when we are damaging large nerve branches such as during dental injections , RCT , insertion of dental implants , extraction of teeth & other surgical treatments ...etc.

1. What is nerve injury ?

The most common nerve injuries are of the inferior alveoler nerve , mental and lingual nerves of V3 branch of trigeminal nerve which cause sensory disturbance in the inerveted area .

Most common nerve injury

1. numbness or pain in the chin , lip , gums and tongue.

2.tingling or electric shok sensation 3.impaired speech 4.loss of taste 5. abnormal chewing 6.biting of tongue and lips 7.burning sensation 8.paralysis ( bells palsy )

Sign & symptoms :

1.Neurapraxia: has favorable prognosis & occur after simple contact with the nerve and nerve conduction failure is temporary and complete recovery which quite rapid and occurs gradually within few days to weeks.

2.Axonotmesis: this serious injury of the nerve resulting in degeneration of the nerve axons ,

regeneration & recovery is slower than neurapraxia & usually begins as paresthesia 6-8 weeks after the injury .

Classification

3.Neurotmesis :this is the gravest type of nerve injury resulting in discontinuation of conduction due to severance of the nerve or due to formation of scar tissue at the area of trauma and cause permanent damage to nerve function including paresthesia

1. During nerve block of IAN & Mental nerve ( deep dental injection ) .

2. While creating incision extend to mental formen & lingual vestibuler fold .

Etiology

3. during incision at the alveolar ridge of edentolous pt whose mental foramen located superficially due to bone resoption

4. during excessive flap retraction

5. when bone near the nerve is excessively heated ,if the surgical handpiece used without coolent ( water or saline solution )

6. in case of removel impacted tooth , root & root tips that are deep in the bone which is near the nerve.

7.during perforation & fracture of lingual cortical plate during sectioning of the roots and crown of impacted 3rd moler.

8.when a bur enters the mandibuler canal , during sectioning.

9.during displacement of a root tip inside the mandibuler canal during extraction attempt.

10. during cleaning of periapical lesion oa posterior teeth that are in direct contact with mand. canal .

11. or by chance Suturing of the Nerve .

12. during putting implant

13. during endodontic treatment because of proximity of the tooth to IAN by over-instrumentation or overfilling or irrigation.

Facial palsy : caused by trauma to the facial nerve .

-Sign & symptoms : 1. unilateral facial weakness 2. loss of taste 3. decreased salivation and tear secretion

Facial nerve paralysis

1. during surgury by incision such as parotidectomy : “removel of the parotid gland “ , or condylectomy: TMJ ankylosis , or surgical approach to the submandibuler gland .

2. Giving Anesthesia during Nerve block To parotid gland .

Causes :

Depends on the age of patient , type of the damage , time that elapsed till the management of injury , correct treatment.

Treatment : No treatment required for type 1 & 2 unless if there

foreign body or root tip compressing on the nerve we just prescribe analgesic & vitamin B to restore the sensation .

Treatment of the neaurotmesis is grafting to replace the injured part or suturing .

For bell’s palsy is often treated with the corticosteriod

Prognosis