3rd molars Flashcards
Most common reasons for 3rd molars failing to erupt
Impacted- by adjacent tooth, alveolar bone, surrounding mucosal soft tissues
Nerves at risk during XLA8
Inferior alveolar
Lingual
Nerve to mylohyoid
Long buccal
Anatomy of lingual nerve
Close relationship to lingual plate in mandibular and retromolar area
Between 0-3.5mm medial to mandible
Indications for XLA8
Therapeutic indications: cysts, tumour, infection, external resorption of 7/8
Surgical indications: orthognathic
High risk of disease
Medical indication: immunosuppressed
Accessibility
Age
Autotransplantation
GA
What is pericoronotis
Inflammation around crown of PE
Food/debris trapped under operculum causing inflammation/infection
Transient/self limiting/usually occurs 20-40 yrs
Anaerobic microbes: actinomyces, fusobacterium, beta lacatamase producing prevotella
Signs and symptoms of pericoronitis
Pain, swelling, bad taste, pus discharge, occlusal trauma to operculum, ulceration of operculum, cheek biting, foetor oris, limited mouth opening, dysphagia, pyrexia, malaise, regional lymphadenopathy
Treatment of pericoronitis
- Incision of localised pericoronal abscess if required
- +- LA depending on pain/pt
- irrigation with warm saline/CH MW( 0.1-0.25ml with syringe and blunt needle)
- XLA8 if traumatising operculum
- Instruct pt on frequent use of warm saline/CH MW
- Advice regarding analgesia
- Instruct pt on high fluid intake/soft diet
- No antibiotics unless more severe pericoronitis, systemically unwell, EO swelling, immunocompromised
Predisposing factors to pericoronitis
- PE + vertical/distoangular impaction
- opposing molars causing mechanical trauma
- upper respiratory tract infection/stress
- poor OH
- white
- full dentition
Why do some health boards recommend not to use CH MW to irrigate
Due to cases of anaphylaxis
If considering surgery OPT take and Radiographic report for 3rd molars must include:
Presence/absence of disease
Anatomy of 3rd M
Depth/orientation of impaction
Working distance
Follicular width
Periodontal status
Relationship of U3M to maxillary antrum and lower to ID canal
Radiographic signs that 3M lies close to ID canal
Interruption of white lines/lamina dura of canal
Darkening of root where crossed by canal/dark and bifid root
Diversion/deflection of ID canal/deflection of root
Narrowing of ID canal/root
Juxta apical area
Radiographic signs associated with increased risk of nerve surgery during 3M surgery
Interruption of white lines of canal
Darkening of root where crossed by canal
Diversion canal
What should be considered when 3M and ID canal are close
Cone Beam Computed Tomography (CBCT)
Tx options for 3M
Common: referral, clinical review, XLA, coronectomy
Less common: operculectomy, surgical exposure, pre surgical ortho, surgical reimplantation/autotransplantation
Basic principles of surgical removal of 3M
Risk assessment- planning/MH
Aseptic Technique
Minimal trauma to soft and hard tissues
Surgical removal steps
Anaesthesia/access
Reflection
Retraction
Bone removal/tooth division as necessary
Debridement/suture/haemostasis/post-op instructions
Access step
Raise buccal mucoperiosteal flap +/- lingual flap
Reflection step
Raise flap at base of relieving incision
Free anterior papilla before proceeding with reflection distally
Reflect using periosteal elevator on bone- avoids disection occuring superficial to periosteum. Reduce st trauma
Instruments: mitchells trimmer, howarths pe, ash’s pe, wj e
Retraction steps
Access to operative field
Protection of soft tissue
Facilitated by flap design
Atraumatic retraction: rest firmly on bone, aware of adjacent structures e.g. mental nerve
Instruments: howarth’s pe, rake retractor, minnesota retractor
Bone removal
Electrical straight handpiece with saline cooled bur
Air driven handpieces may lead to surgical emphysema
Done on buccal side of tooth and distal aspect of impact
Intends to create deep, narrow gutter around crown of wisdom tooth
Allows correct application of elevators on mesial and buccal side of tooth
Tooth division
Horizontal crown sectioning: remove entire tooth section above enamel cement junction- leave some tooth behind for orientation/elevation
Vertical crown sectioning: removal of distal portion of root and distal crown followed by elevation of mesial portion and root
Debridement
Physical: bone file/handpiece to remove sharp bony edges- mitchells’s trimmer or victoria curette to remove soft tissue debris
Irrigation: sterile saline into socket and under flap
Suction: aspirate under flap to remove debris, check socket for retained apices
Suture: approximate tissue and compress blood vessels
Aim- reposition tissue, cover bone, prevent wound breakdown, haemostatsis
Coronectomy
Alternative to XLA when appears to be high risk of IAN damage
Warn pt about retained roots/coronectomy
If roots mobilised during crown removal, entire tooth must be removed
May result in infection
Slow healing/painful socket
Roots may migrate at later date and begin to erupt though mucosa and require XLA
Why would u preserve retained roots
Preserve bone height
Near IAN canal
Present for years with absence of disease
Gives pt options
Monitor to ensure caries free
Document discussion with pt
