CHAPTER 10: MANAGEMENT OF IMPACTED TEETH

ppt + discussions + book

embedded tooth

those which are unerupted unusually because of lack of eruptive forces

unerupted teeth

includes both impacted teeth and teeth still developing/erupting

impacted tooth

fails to fully erupt into the dental arch within the expected time

those prevented from erupting by some physical barrier in eruption path

over-retained tooth

undue retention of deciduous tooth beyond the usual eruption age of their permanent successors

causes of impaction

abnormal tooth orientation

dense overlying bone

excessive soft tissue

genetic abnormalities

inadequate dental arch space

most common cause for third molar tooth impaction

inadequate space exists due to insufficient length of the jaw

most commonly impacted teeth

mx/mn 3rd molars

maxillary canines

mandibular second premolars

mx/mn third molars

because they are the last teeth to erupt; caused mostly by inadequate space for eruption

maxillary canines

erupts labial to arch

erupt after the lateral incisors and premolars thus eruption is prevented by crowding of these teeth

mn second premolars

may erupt buccally or lingually

erupt after first molar and canine thus space may be inadequate for proper eruption

general rule

remove all impacted teeth unless contraindicated

risks of leaving impacted teeth untreated

increased local tissue morbidity

damage or loss of adjacent teeth and bone

potential injury to nearby vital structures

risks increase with age

denser surrounding bone

higher surgical risk due to systemic disease

fully formed roots near structures such as IAN or MX sinus

eruption patterns of third molars

average completion: 20 years

eruption may continue until age 25 in some patients

• lower third molar rotation sequence:

  • horizontal → mesioangular → vertical

  • failure to rotate to vertical → most common cause of impaction

  • adequate space between anterior ramus and second molar is required for eruption

late eruption of third molars factors

root development may be incomplete

teeth covered only by soft tissue or slightly by bone

usually vertical and superficial relative to occlusal plane

space limitations often determine whether eruption occurs

ideal time for removal of an impacted tooth

mid-to-late teenage years (ages 16–20)

optimal when roots are 1/3 formed, before 2/3 formation

• advantages of early removal:

  • easier, less traumatic surgery

  • faster recovery and less morbidity

  • reduced risk if nerve injury occurs

  • better periodontal healing distal to second molar

indications for removal of impacted teeth

prevention of dental caries

prevention of pericoronitis

prevention of jaw fractures

optimal periodontal healing

prevention of root resorption

prevention of periodontal disease

facilitation of orthodontic treatment

treatment of pain of unexplained origin

impacted teeth under a dental prosthesis

prevention of odontogenic cysts and tumors

prevention of periodontal disease

early removal → better bone fill and periodontal healing

difficult-to-clean distal surfaces → gingivitis → periodontitis

impacted mandibular third molars reduce bone on distal second molar

maxillary third molars: distal furcation involvement accelerates disease

maxillary second molars

predispose to early furcation involvement

prevention of dental caries

partially or fully impacted teeth may allow bacterial colonization

caries can develop on distal second molar and third molar crown

prevention of pericoronitis

caused by bacterial colonization, trauma, food impaction

infection of soft tissue covering partially erupted teeth (operculum)

• mild cases → local irrigation with hydrogen peroxide, saline, chlorhexidine

• severe cases → systemic antibiotics (penicillin or clindamycin) and extraction

• prevention → remove third molar before eruption or soft tissue exposure

prevention of root resorption

impacted tooth may resorb adjacent tooth roots

removal can allow cemental repair; sometimes endodontic therapy needed

impacted teeth under a dental prosthesis

delayed removal increases risks due to age, systemic disease, and mandibular atrophy

removal before any prosthesis fabrication prevents ridge alteration & prosthesis dysfunction

alveolar bone resorption can expose impacted teeth under dentures, causing ulceration and infection

prevention of odontogenic cysts and tumors

follicular sac may develop dentigerous cyst if unerupted

larger cysts may need surgical intervention

rarely, tumors like ameloblastoma may develop

treatment of pain from unexplained origin

removal of unerupted tooth can relieve idiopathic mandibular pain

delaying removal may increase risk of TMJ disorders

prevention of jaw fractures

impacted MN third molars weaken the jaw by occupying bone space

fractures often occur at the site of impaction.

facilitation of orthodontic treatment

impacted 3rd molars may interfere with molar retraction

removal is recommended before orthodontic therapy

necessary when retromolar implants are planned for anchorage

optimal periodontal healing

best when patient is younger than 25

• factors influencing healing:

  • extent of preoperative distal bone loss on second molar

  • patient age

• older patients (>30 years) with asymptomatic bony impactions

  • may not benefit from removal

  • surgery may worsen periodontal outcomes

contraindications for removal of impacted teeth

risk to adjacent structures

compromised medical status

extremes of age (early or advanced)

early age

tooth buds may be visible radiographically by age 6

early removal is controversial; accurate prediction of future impaction is difficult

most surgeons defer removal until a clear diagnosis of impaction can be made

advanced age

most common contraindication to removal

recovery is slower; post-op sequelae more pronounced

asymptomatic, disease-free impacted teeth may remain in place

radiographic check every 1–2 years to detect late complications

bone is highly calcified, less flexible → more bone removal required during extraction

• removal indicated if:

  • cystic formation occurs

  • periodontal disease develops

  • tooth becomes symptomatic

  • tooth lies under prosthesis with thin overlying bone

compromised medical status

asymptomatic teeth are generally left in place

symptomatic teeth may require collaboration with the patient’s physician to minimize operative/postoperative risk

• medical conditions may make elective removal riskier:

  • cardiovascular or respiratory compromise

  • impaired immune response

  • acquired or congenital coagulopathy

risk to adjacent structures

if removal may injure nerves, adjacent teeth, or bridges, leaving the tooth may be prudent

• weigh risks against future complications:

  • younger patients: removal may be justified with precautions

  • older patients: asymptomatic teeth with low complication risk → avoid removal

• ex: older patient with distal periodontal defect on second molar; removing third molar could cause loss of second molar → do not remove

treatment planning considerations

• space in dental arch:

  • adequate room → consider deferring removal until eruption completes

  • insufficient space with soft tissue operculum → removal is indicated to prevent pathology

• patient age:

  • eruption usually completes by 20 years, may continue to 25 years

  • mesioangular impactions at age 17 may eventually erupt

  • age 18–19 → optimal time for asymptomatic 3rd molar removal if inadequate space exists

• status of adjacent teeth:

  • severely diseased second molar → leaving third molar may help guide eruption if second molar removed

• predictive limitations:

  • early predictions of impaction are unreliable

  • by age 18, clinician can reasonably predict eruption potential and make informed removal decisions

• goal of removal:

  • maximize soft tissue and bone healing

  • optimize long-term periodontal health of adjacent second molars

classification systems for mandibular third molar impactions

as to angulation

relationship to the occlusal plane

relationship with the anterior border of the ramus

classification based on angulation

most commonly used classification

determined by the angle between the long axis of the impacted third molar and the long axis of the adjacent second molar

4 classification based on angulation

mesioangular

horizontal

vertical

distoangular

mesioangular

least difficult, easiest to remove

most commonly seen type of impaction

crown is tilted towards the second molar in a mesial direction

horizontal

requires bone removal or sectioning

more difficult to remove than the mesioangular

tooth has a long axis perpendicular to that of the second molar

vertical

second most common impacted tooth

long axis of the impacted tooth is parallel to that of the second molar

distoangular

most difficult angulation for mandibular

pathway blocked by mandibular ramus

the crown of the tooth is tilted in a distal direction away from the second molar

classification based on relationship with the anterior border of the ramus

aka: Pell and Gregory classification (classes 1, 2 and 3)

determines the position of the mesiodistal diameter of the crown against the anterior border of the ramus.

3 classifications based on relationship with the anterior border of the ramus

pell and gregory class 1

pell and gregory class 2

pell and gregory class 3

pell and gregory class 1

easiest to remove

has a sufficient space for eruption

lower third molar is positioned anterior to the ramus

pell and gregory class 2

½ of the mesiodistal diameter of the crown is covered with the ramus

pell and gregory class 3

the most difficult to remove

impacted tooth is completely embedded in the bone of the ramus of the mandible

classification based on the relationship to the occlusal plane

aka: pell and gregory class A, B and C

this determined the vertical depth of the impacted tooth in relation to the occlusal plane

3 classification based on the relationship to the occlusal plane

pell and gregory class A

pell and gregory class B

pell and gregory class C

pell and gregory class A

occlusal plane is at the same level as the occlusal plane of the second molar

pell and gregory class B

occlusal plane is between the occlusal plane and the cervical line of the second molar

pell and gregory class C

impacted tooth is below the cervical line of the second molar

white winter’s lines

occlusal level of 2nd and 3rd molars

amber winter’s lines

amount of alveolar bone covering the tooth

red winter’s lines

depth of the tooth in the bone

factors affecting difficulty of impacted tooth removal

size of the follicular sac

nature of overlying tissue

density of surrounding bone

relationship to inferior alveolar nerve

contact with mandibular second molar

root morphology (length, width, number, shape)

root length

• optimal extraction time: roots 1/3–2/3 formed (teenage years).

  • blunt root ends → easier removal

• fully formed roots

  • may fracture during extraction or impede delivery

• immature roots (<1/3 formed):

  • tooth may roll like a marble, making elevation difficult

root number and shape

• fused, conical roots

  • easier to remove

• separated, divergent roots:

  • harder; may require tooth sectioning

• curved/dilacerated roots:

  • increase difficulty; hooked apices especially challenging

• direction of curvature:

  • mesioangular teeth with distal-curved roots → easier removal

  • roots curved mesially → higher fracture risk if not sectioned

root width

• wider roots than cervical width:

  • more bone removal or sectioning needed

periodontal ligament (PDL) space

• wider PDL:

  • easier extraction

• older patients (>40 years) often have narrower PDL:

  • more difficult extraction

size of the follicular sac

• wide follicle:

  • less bone removal, easier extraction

• narrow/no follicle:

  • more bone removal needed, harder extraction

density of surrounding bone

• younger patients (<25 years):

  • less dense, pliable bone → easier removal

• older patients (>25 years):

  • denser bone → more difficult, longer bone removal, higher fracture risk

• gender effect:

  • males often have denser bone

contact with mandibular second molar

• space between second and third molars:

  • easier extraction

• contact (esp. distoangular or horizontal impactions):

  • higher risk of second molar damage

relationship to inferior alveolar nerve

• roots close to or superimposed on the nerve:

  • higher risk of nerve injury → increases difficulty

  • temporary or permanent paresthesia of the lower lip and chin

  • preoperative CBCT can help visualize this relationship

classification based on overlying tissue (insurance-oriented)

partial bony impaction

soft tissue impaction

complete bony impaction

partial bony impaction

more difficult

tooth partially covered by bone

requires soft tissue flap + bone removal + possible sectioning

soft tissue impaction

usually easiest

tooth covered only by soft tissue

requires incision & flap reflection

complete bony impaction

often most complex

tooth completely encased in bone

requires extensive bone removal + almost always sectioning

factors that make impaction surgery less difficult

fused conical roots

separated from IAN

soft tissue impaction

roots 1/3 - 2/3 formed

mesioangular position

large follicle, elastic bone

wide periodontal ligament

separated from second molar

pell and gregory class 1 ramus

pell and gregory class A depth

[ present in the young patient ]

factors that make impaction surgery more difficult

distoangular position

dense, inelastic bone

divergent, curved roots

complete bony impaction

long, thin roots, thin follicle

contact with second molar

narrow periodontal ligament

close to inferior alveolar canal

pell and Gregory class 2 or 3 ramus

pell and Gregory class B or C depth

classification systems for maxillary third molar impactions

vertical

distoangular

mesioangular

rare positions

vertical

easier for maxillary

often straightforward removal

long axis parallel to second molar

distoangular

easier for maxillary

crown angled distally; withdrawal path generally accessible

mesioangular

most difficult for maxillary

opposite of mandible → overlying posterior bone is thicker, access limited by second molar

[ for maxillary teeth, mesioangular impactions are the most difficult, while vertical/distoangular are easier ]

rare positions

transverse, inverted, horizontal

buccolingual position

labial position → easier surgical access

palatal or intermediate → more difficult to remove

surgical procedure for impacted teeth

adequate exposure (flap reflection)

removal of overlying bone

sectioning the tooth

delivery of the tooth

wound preparation and closure

envelope or three-cornered flap

the most commonly used flap for the removal of mx impacted teet

incisions must stay over bone to avoid nerve injury (esp lingual nerve)

• for mandibular 3rd molar:

  • envelope incision from mesial papilla of first molar to anterior border of ramus

• for maxillary 3rd molar:

  • envelope incision over tuberosity from distal of second molar to mesial of first molar

instrument used for flap reflection

austin and minnesota

removal of overlying bone

• for mandibular 3rd molar:

  • remove bone in occlusal, buccal, distal aspects down to cervical line.

  • use round burrs (#8) or fissure burrs (#703)

  • use ditch maneuver in cancellous bone to create pathway for elevators.

  • avoid lingual bone removal to protect lingual nerve.

• for maxillary 3rd molar:

  • bone removal usually unnecessary

  • minimal buccal bone removal is usually needed

  • if needed, remove primarily on buccal aspect to expose the crown.

  • periosteal elevator often sufficient

  • remove bone on mesial aspect to provide purchase for elevators

instruments used in removing overlying bone

no. 8 large round burs → effective for end-cutting bone

no. 703 fissure burs → effective for lateral bone removal and tooth sectioning

sectioning the tooth

• purpose:

  • allows removal of parts of the tooth individually through the surgical opening, minimizing excessive bone removal

  • sectioning direction depends on tooth angulation and root curvature

• technique:

  • required for impacted mn 3rd molars

  • use a burr to section the tooth ¾ toward the lingual aspect

  • avoiding complete lingual penetration to protect the lingual nerve

  • insert a straight elevator into the slot to split the tooth

  • maxillary impacted teeth are rarely sectioned due to thin, elastic bone

sectioning the mesioangular impacted tooth

easiest

remove distal half of crown at buccal groove just below cervical line

elevate remainder with a no. 301 elevator or crane pick

sectioning the horizontal impacted tooth

remove occlusal and buccal bone to cervical line

divergent roots may require separate sectioning

section crown from roots; remove crown, elevate roots with cryer elevator

sectioning the vertical impacted tooth

more difficult for the mandibular

remove occlusal, buccal, distal bone

section distal half of crown; elevate remaining tooth mesially

requires more bone removal due to limited access

sectioning the distoangular impacted tooth

most difficult

remove buccal, occlusal, distal bone

section crown from roots; remove crown first

tooth tends to rotate distally; careful elevation needed

roots delivered individually or together depending on fusion/divergence

delivery of the tooth

• for mandibular 3rd molar:

  • elevators used: straight elevator, cryer elevators, crane pick

  • use root tip picks for sectioned roots if needed

  • little to no luxation is performed; pathway created by bone removal and sectioning

  • avoid excessive force to prevent:

    • tooth fracture

    • buccal bone damage

    • injury to adjacent molar or mandible

• for maxillary 3rd molar:

  • angled elevators (potts, miller, warwick) may aid access

  • insert tip at mesial cervical line, apply pressure in proper direction

  • small straight elevators luxate tooth (rotary-and-lever motion) distobuccally

ditching

removal of bone between the tooth and cortical plate

to provide purchase point for the instrumentation for the delivery of the tooth

bone and wound preparation

• smooth sharp bone edges:

  • with a bone file, esp where elevators contacted bone

• remove bone chips and debris:

  • via vigorous sterile saline irrigation under the flap

• use a hemostat:

  • to remove remnants of the dental follicle, if present

  • check hemostasis: control bleeding from flap vessels, bone marrow, or inferior alveolar vessels

  • firm pressure with moistened gauze may be applied if generalized ooze occurs

• optionally, tetracycline may be placed:

  • in mn 3rd molar sockets

  • to prevent osteitis sicca (dry socket)

flap closure

usually primary closure if the flap is well-designed and intact

• suturing technique for mandibular third molars:

  • first suture through attached tissue on the posterior aspect of the second molar

  • additional sutures posteriorly and anteriorly through mesial papilla

  • typically, 2-3 sutures suffice for an envelope flap

  • releasing incision: ensure proper closure of that portion

• maxillary third molar: flap may rest passively; sutures sometimes unnecessary

expected postoperative course

pain

trismus

edema or swelling

swelling

peaks over 3-4 days and resolves by 5-7 days

severity depends on surgical trauma & patient variability

ice packs may improve patient comfort, though limited evidence for swelling reduction

• corticosteroids

  • can reduce edema

  • 8mg dexamethasone IV pre-op, oral doses for 2–3 days

pain

usually modest

mild soreness may persist for 2-3 weeks

controlled with oral analgesics usually for 2-3 days

trismus

common after mn 3rd molar surgery

patients should be warned preoperatively

resolves gradually; normal opening returns in 7-10 days

coronectomy

only the crown (top part) of a tooth is removed and the roots are intentionally left in place

mainly used for mn 3rd molars when the roots are very close to important structures (IAN)