Impacted third molars Flashcards
What is impaction?
when there is prevention of complete eruption into a normal functional position due to lack of space or development in an abnormal position
ectopic meaning
malpositioned if due to congenital factors
displaced meaning
malpositioned due to presence of pathology
explain a completely unerupted tooth
entirely covered by soft tissue and also partially/totally covered in alveolar bone
explain an ankylosed tooth
fused with alveolar bone, rare with 8’s, occurs after middle age
what causes impacted teeth?
lack of space in the arch as a consequence of evolutionary changes and lack of an abrasive diet
which teeth are most commonly impacted
mandibular third molars, maxillary canines, mandibular premolars/ canines, maxillary incisors and maxillary third molars
when to mandibular third molars emerge?
18-24 years old
what ratio of mandibular third molars fail to develop?
1:4
percentage of mandibular molars impacted
72%
mandibular third molars indications for removal
pericoronitis, unrestorable caries, cellulitis/osteomyelitis, periodontal disease, orthodontic reasons
What is pericoronitits?
inflammation of the tissues around the crown of any partially erupted/ impacted tooth
Features of pericoronitis
trismus, pain, dysphagia, signs of inflammation of pericoronal tissues, cheek biting, halitosis, food packing
treatment for pericoronitits
local measures - irrigation, OH, remove trauma ie extract upper 8s or grind cusps
general measures - analgesics, antibiotics, admission in severe life threatening cases
Is periocoronitis predominantly aerobic or anaerobic?
anaerobic
Bacteria involved in pericoronitits
streptococci, actinomycetes, propionibacterium, beta-lactamase
Bacteria involved in increased incidence of second and third molar periodontal pockets deepening?
prevotella intermedia and campylobacter rectus
Treatment choices for mandibular third molars third molars
conservative, removal and coronectomy. Operculotomy is not recommended
Factors influencing decision of treatment choices for mandibular third molars
systemic disease, age, anatomical position of tooth and root morphology, adjacent teeth and structures, limited access, patient compliance, quality of bone, presence of infection or pathology, TMJ problems
What radiograph would you take to assess mandibular third molars
OPG (PA ca show root apices in relation to IDC)
what are you looking for on the radiograph when assessing the mandibular third molars?
depth, relation, angulation to adjacent teeth, proximity to ID nerve
To assess depth what colours (Winter lines) ?
white, amber and red
What angulations to adjacent teeth can you have?
vertical, mesioangular, distoangular, horizontal, transverse, aberrant
most common angle of impaction
mesial (40%)
radiographic signs of close relationship between lower third molar and the IDC
diversion of the IDC, darkening of root as it is crossed by the IDC, loss of lamina dura of IDC, narrowing of IDC, deflection of roots of lower third molar, juxta apical area
Post operative alteration in sensation where in mouth?
lower lip and tongue
What is the alternative surgery if there is a high risk to the IDN?
coronectomy
What does a coronectomy involve?
remove the crown and leave the roots in place. if the roots are mobile at the time of the coronectomy remove them
5 points planned from radiograph ?
what would be the path of eruption
extrinsic/instrinsic obstacles of removal
required bone removal
point of application
flap design
What is a triangular flap
distal relieving incision up the ascending rams
what is a envelope flap
no mesial relieving incision
what are 2 intrinsic obstacles - root form/
convergent roots
divergent roots
Why after surgery would the flap rest on bone
to avoid wound breakdown
what is the most important suture
the one placed from the buccal tissues to the lingual tissues
Why is it better to place fewer sutures
better to secure primary closure and haemostats
materials used for suturing flap
3/0 vicryl rapide
Post op regime?
analgesics, HSMW, soft diet, topical ice packs, suture removal at one week if not restorable
What are complications of impacted third molars xla?
heamorrhage (primary or secondary), loose teeth or damage to adjacent teeth, fracture mandible, dry socket, sensory deficit, complications generally associated with xla
Maxillary third molar features
majority MA or V impacted, thin cortical bone ad short single root 74% cases
Maxillary third molars extraction process if erupted?
elevation or forceps extraction
Maxillary third molars unerupted process for xla?
raise buccal flap, thing friable bone removed, one suture to reposition flap
