LAop: Surgical procedure

 

1.    Reflect adequate mucoperiosteal flaps for accessibility

>       Difficulty of removing an impacted tooth depends on accessibility

>       Reflection of flap must allow placement & stabilization of retractors and instruments for bone removal, and soft tissue retraction without damaging the flap

>       Envelope flap

                       i.     Quicker to close, heals better than 3-cornered flap

                      ii.     How?
Mandbular: Mesial papilla of 6, around necks of teeth, to db line angle of 7,
posteriorly to and laterally up anterior border of mandibular ramus.
Maxillary: Posteriorly over tuberosity from distal of 7,  anteriorly to mesial of 6

                     iii.     Carefully palpate retromolar area before beginning incision.

Incision extends laterally posteriorly as mandible diverges laterally. Straight extension of incision will fall off the bone and into sublingual space, may damage lingual nerve.

                    iv.     Flap reflected laterally to expose external oblique ridge with periosteal elevator.

                     v.     Surgeon should not reflect more than a few mm beyond EOR as this results in increased morbidity and complications.

                    vi.     Retractor (Austin, Minnesota) placed on buccal shelf, lateral to EOR, stabilized by applying pressure towards bone.

>       3-cornered flap: Envelope flap with releasing incision

                       i.     Allows greater access to more apical areas of tooth without risk of tearing

                      ii.     Flap must have a broad base

>       Incision principles

                       i.     Smooth stroke of scalpel

                      ii.     Keep in contact with bone throughout entire incision so that mucosa and periosteum are completely incised = Full-thickness mucoperiosteal flap raised

                     iii.     Incision should be designed so that it can be closed over solid bone rather than bony defect = Extend incision at least one tooth anterior (mesial of 7) to surgical site

                    iv.     Avoid vital anatomic structures

2.    Remove overlying bone

>       Principles

                       i.     Balance bone removal & tooth sectioning to hasten healing & minimise time of surgery.
All impacted teeth can be removed without sectioning if large amount of bone removed, but removal of excessive bone prolongs healing period and may weaken jaw. Removal of small amount of bone with multiple divisions of tooth may prolong operation unnecessarily.

                      ii.     Amount of bone removed varies with impaction depth, root morphology, & tooth angulation.

                     iii.     Remove bone on occlusal, buccal and distal down to cervical of tooth.
Not removed from lingual aspect to avoid lingual nerve.

                    iv.     Burs: No.8 end cutting bur, used effectively for drilling with a pushing motion.

>       Steps

                       i.     Remove bone on occlusal to expose tooth crown

                      ii.     Cortical bone on  buccal aspect removed down to cervical line

                     iii.     Bur to remove bone between tooth & cortical bone in cancellous bone = Ditching

                    iv.     Provides access for elevators and creates tooth delivery pathway

                     v.     Maxillary: Bone removal usu unnecessary. When required, bone removed on buccal aspect of tooth, down to cervical line to expose entire clinical crown. Usually via periosteal elevator (not bur). Mesial bone might be removed to allow elevator access.

3.    Section tooth

>       Direction in which impacted tooth should be divided depends primarily on impacted tooth angulation. Also divergent roots presence, depth of impaction.

>       Technique

                       i.     Tooth sectioned 3/4^th s way towards lingual aspect

                      ii.     Bur not used to section tooth completely through lingual direction (avoid lingual nerve)

                     iii.     Straight elevator inserted into slot made by bur, rotated to split tooth.

>       Mesioangular impaction
Distal half of crown sectioned off at buccal groove to just below cervical line on distal aspect. Remaining tooth removed with No. 301 elevator placed at mesial aspect of cervical line.
OR prepare purchase point in tooth with bur, use crane pick elevator to elevate tooth.

>       Horizontal impaction

Divide crown from roots at cervical line. Crown removed, roots displaced with cryer elevator into space previously occupied by crown. Divergent roots might require sectioning into 2 portions to be delivered individually.

>       Vertical impaction

Occlusal, buccal & distal bone removed. Distal half of crown sectioned and removed. Tooth elevated by applying elevator at mesial aspect of cervical line of tooth.  Posterior aspect of crown elevated first with cryer, mesial aspect elevated with straight elevator. More difficult than mesioangular removal because access around 7 hard, requires more bone removal on b & d.

>       Distoangular impaction

Section crown from roots just above cervical line. Entire crown usually removed as it interferes with visibility and access to tooth root structure. If roots are fused, cryer/ straight elevator used to elevate tooth into space previously occupied by crown. If roots divergent, sectioned then delivered. More distal bone removed,

>       Impacted maxillary teeth rarely sectioned as overlying bone thin and elastic.

>       Impacted teeth elsewhere usually sectioned only at cervical line as this permits removal of crown of tooth, displacement of root into where crown was, removal of root.

4.    Deliver tooth with elevator

>       Elevators: Not to deliver excessive force.
To engage tooth or tooth root and to apply force in proper direction.
Impacted tooth has never sustained occlusal forces, thus PDLs are weak and permit tooth displacement if appropriate bone is removed and force is delivered in proper direction.

>       Commonly used: Straight elevator, Cryer, Crane pick.

>       Difference between extraction and impacted tooth removal.
No luxation of tooth occurs for purpose of expansion of buccal or linguocortical plate. Instead, bone is removed and teeth are sectioned to prepare unimpeded path for tooth delivery.

>       Excessive force may cause unfavouring fracturing of tooth/ buccal bone/ 7/ mandible.

5.    Prepare for wound closure

>       Bone file: Remove any sharp, rough bone edges particularly where elevator was in contact

>       Irrigate with saline to remove all particulate bone chips and debris from wound and under reflected oft tissue flap.

>       Mosquito haemostat: To remove any remnants of dental follicle.
Grasp follicle, lift with slow, steady pressure à Pulls free from surrounding hard&soft tissue.

>       Final irrigation and thorough inspection

>       Suture: Primary closure.
Initial suture: Through attached tissue on posterior aspect of 7.
Additional sutures placed posteriorly from that position, anteriorly through papilla on mesial of 7/6.

>       Check for adequate haemostasis.
Bleeding can occur from vessel in flap, bone marrow cut with bur, or inferior alveolar vessels.
Specific bleeding points controlled.
Brisk generalised oozing, apply firm pressure with small, moistened gauze pack.

>       Antibiotic application (tetracycline) to help prevent osteitis sicca.