IMPACTED MANDIBULAR THIRD MOLARS

INCISION

The method of gaining acess through

mucoperiosteal flap dates back to year

1849, when John Tomes first described the

technique to remove impacted third molar

After placing an incision with a

sharp 15 no. blade, a mucoperiosteal flap is raised for

appropriate acess

Mark the incision with marking ink making a rough

outline.

FLAP DESIGNSEnvelope flapIt starts on the ascending ramus following the centre of the 3rd molar shelf to the distobuccal surface of 2nd molar and then extends as a sulcular incision to the mesiobuccal corner of the 2nd molar.Indicated for mesioangular/soft tissue impactionsAlso known as 2nd molar sulcus incision

The incision extending to the mesiobuccal surface of 1st molar is a 2nd & 1st molar sulcus incision. Its best for linguoangular impactions as it provides better visibility. Three cornered/triangular/bayonet flap Envelope incision + anterior vertical releasing incision Most commonly used.

Incision begins 6.4mm in the buccal sulcus at the junction of middle & posterior third of 2nd molar.Passed upwards to the distobuccal angle of 2nd molarCervically behind tooth to midline of its posterior surface.Taken back and laterally to prevent vessel injury in retromolar area.In final continuation it penetrates the mucosa of cheek.This is k/a tailing of incision (2-3mm)Total length 25.4mm

Modifications of three-cornered flap (Terrence Ward’s incision)

Minor modification in terrance ward’s incision

Its for partially erupted teeth which includes the posterior limb is extended to cervical area of partially erupted tooth before continuing it backwards and laterally.

Modified Ward’s

Anterior incision is commenced at the distobuccal corner of the crown of mandibular 1st molar instead of 2nd molar.

“L” shaped flap

Incision is a few mm away from the marginal gingiva.Also called as “PARAMARGINAL FLAP”Helps in an intact marginal attachment distal to 2nd molar.

Triangular flap (szmyd incision)

A small ‘V’ shaped incision, made with one point at distobuccal line angle of the second molar. One vertical limb followed the external

oblique ridge, and the other avoided the gingival sulcus and extended down to the mucogingival junction, doen’t involve papilla of mandibular 2nd molar.

Lingual Flap

Used when lingual approach is used for removal of third molars. Incision starts at ascending ramus aiming at the distobuccal corner of second molar as sulcular incision and then continued ligually to the first molar.

A sulcular incision is made along the buccal aspect of second molar.

Comma shaped incision

Starting from a point at the depth of stretched vestibular reflection posterior to the distal aspect of the preceding second molar, the incision is made in an anterior direction. The incision is made to a point below the second molar, from where it is smoothly curved up to meet the gingival crest at the distobuccal line angle of the second molar. The incision is continued as a crevicular incision around the distal aspect of the 2nd molar.

allows reflection of a distolingually based flap adequately exposing the entire 3rd molar area.

Reflection of periosteal flap

Sharp point of periosteal elevator is used to elevate a mucoperiosteal flap beginning at the point of incision at the level of second molar and down the releasing incision.

The flatter end of periosteal elevator is then used to elevate the periosteum posteriorly to the ascending ramus of the mandible.

Bone removalIt is done to•Expose the crown by removing the

bone overlying it.•To remove the bone obstructing the

pathway for removal of the tooth.•To create a fulcrum for engagement

of an elevator

Techniques of bone removal•With help of bur•-postage stamp method•-Moore Gilbee’s Collar

technique/guttering/channel•Chisel and mallet technique

No. 7 or 8 round bur can be used in the range of 5000-10,000 rpm.

Use of bur should always be done with copious saline irrigation to prevent thermal injury.

Bone should be removed from The occlusal surface of the tooth. A channel is formed in the bone lateral and posterior to

the impacted third molar to the cervical level of the crown contour.

Adequate amount of trough should be created to remove any bony obstruction for exposure and delivery of the tooth.

Careful bone removal should be done around the distal and distolingual aspect of the tooth without damaging the lingual nerve which lies in the vicinity of the lingual plate adjacent to the third molar

Moore Gilbee’s Collar technique

Postage stamp method

Adequate cutting of bone on buccal aspect of tooth is done in the shape of postage stamp & adequate space for application of elevator is created.

Chisel and mallet technique

First step is placement of vertical stop cut with a 3mm/5mm chisel vertically at the distal aspect of second molar with the bevel facing posteriorly.

Second step is placement of the chisel at the base of vertical stop at an angle of 45 H with bevel facing occlusally and oblique cut is made till distal aspect of third molar.

Then 2nd vericle cut is placed at the point where entire buccal aspect of third molar is ending (apprx 4mm).

This results in removal of buccal plate distal to the second molar.

Additional piece of bone can be removed at the junction of vertical and oblique cut for making a purchase point.Final step is removal of the distal bone so that during elevation there is no bony obstruction.

Lingual split bone technique

First developed by Sir William

Kelsey Fry (1933) but originally described by

Terrence Wards in 1956.

Indicated for mandibular third

molars especially, which

are placed lingually.

Mandible should be supported

during the entire technique.

A slight increase in the incidence

of transient lingual

anaesthesia during

postoperative period

complicates the use of this technique.

Steps Vertical stop cut is made by placing the chisel with

the bevel facing posteriorly, distal to 2nd molar buccaly.

2nd stop is made apprx 4mm distobuccal to 3rd molar crown

• With a chisel bevel upwards a horizontal cut is made backwards from a point just above the lower end of the vertical stop cut.

• This enables the buccal plate to be removed. • Distolingual bone plate is then fractured inwards by placing the

cutting edge of the chisel along the red line in the figure, with the chisel held at an angle of 45 H to the bone surface and pointing in the direction of lower second premolar of the opposite side.

- Keeping the cutting edge of the chisel parallel to the external oblique ridge, a few light taps with the mallet are made to separate the lingual plate from the rest of the alveloar bone and hinge it inwards on the soft tissues attached to it.- Keeping the chisel parallel to the internal oblique ridge may result in extension of lingual split to the coronoid process.

• A straight elevator is then applied on the mesial surface of tooth to displace the tooth upwards and the lingual plate is then lifted from the wound.

• Bone edges are smoothened, lingual plate is removed, wound is irrigated and closure is done

Lewis (1980) has modified the lingual split bone technique by incorporating following features:

- Minimal periosteal reflection- Preserving fractured lingual plate- Less buccal bone removal Leading to less lingual nerve damage, decreased

periodontal pocket formation and better wound healing chances

Hochwald, Kamanishi & Davis (1983) modified it by splitting distolingual bone in segments to allow better tactile control of osteotome to prevent its penetration into soft tissues.

This procedure can be employed to remove any

partially formed unerupted third molar.It has been employed to

remove such teeth from patients from 9 to 18

years of age.

It can be performed under GA or regional

anaesthesia with sedation.

Good technique for preservation of pre-

operative periodontal status of

2nd molar.

Lateral trepanation technique of Bowdler Henry

•The operation is performed as follows—

•Extended S-shaped incision is made from the retromolar fossa, across the external oblique ridge to the first molar.

•The soft tissues are readily elevated from the surface and retracted from the surface of bone and held away with Bowdler Henry retractor.

A round bur is used to trephine the position of the crypt of a third molar. When the anteriorposterior length of the crypt has been determined, the bur is used to make a vertical cut through the external plate at its anterior margin.

A second cut through the outer cortex is made at the posterior end of the crypt at an angle of 450.

A chisel applied in a vertical direction is used to out fracture the buccal plate, which is then delivered with a curved haemostat thus exposing the crown of the third molar lying in its crypt.

A warwick james elevator is applied to the occlusal surface of the tooth and used to deliver it. 

Any follicular remnants are removed.

The wound is irrigated and is sutured.

Simplified split bone technique Given by C - J Yeh in 1995 An incision is placed on the buccal side of anterior border

of ramus towards distal aspect of second molar and along the buccogingival sulcus to its mid point and reflect the flap.

Remove buccal bone to expose height of contour. Create an osteoperiosteal flap by making a cut with chisel

superiorly, distally & lingually to expose crown & root. Make a horizontal bone cut with chisel over the edge of

previously placed incision in Pdl space & then proceed lingually & distally

Separate rest of lingual plate by paralleling chisel with long axis of tooth.

Deliver the tooth in distolingual direction

Coronectomy

Coronectomy is the removal of crown of the tooth, leaving the roots “in situ” when applied to third molars or any unerupted posterior tooth in the mandible, It is a measure adopted to avoid damage to inferior alveolar nerve

The crown of the tooth is completely transacted with the help of a bur at an angle of 45° and the roots are reduced 3mm below the crest of buccal and lingual cortical plates. The exposed vital roots need not to be treated endodontically as bone formation occurs around these roots and osteocementum usually extends to cover the roots. If after coronectomy the roots migrate towards the alveolar crest or infection of roots occur then a second surgery is always possible for the removal of these roots.

Contraindications : horizontally impacted teeth, teeth with active infection, mobile

teeth, non vital teeth, teeth with periapical pathology , patients having pre-existing inferior alveolar nerve and lingual nerve disturbance and patients with compromised immune system.

Tooth removalAfter bone removal an elevator may be applied on mesial surface of the tooth and the tooth is removed along the path of removal.Lower border of mandible should be supported all the time.If there is hindrance in the path of removal then tooth sectioning should be opted for.

Tooth sectioning

INDICATIONS Tooth impaction Unfavourable root morphology To prevent injury to adjacent anatomical structures To avoid removal of large amount of boneADVANTAGES OF TOOTH SECTIONING Reduces the amount of bone removal Reduces the risk of jaw fracture Less post-operative trismus Avoidance of damage to anatomical structures.

Horizontal impaction

•Sectioning done in superoinferior direction preventing IAC

Horizontal impaction

•Removal of the crown.•Removal of the roots together or sectioning of roots and then removal of individual roots.

Mesioangular impaction

Distoangular impaction

Vertical impaction