Third Molar Flashcards

1
Q

eruption

A
  • approx 18-24yrs, varies
  • may still be present and begin to erupt in elderly/edentulous pt
    CO denture rocking/no longer fits
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2
Q

crown and root calcification

A
  • crown: begins 7-10yo, completed by 18yo
  • root: completed btw 18-25yo
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3
Q

stats of missing

A
  • at least 1 missing in 25% adults
  • maxilla
  • female
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4
Q

guidance and their summary

A

SIGN 43 2000 - must justify the need of surgical removal
NICE 2000 - discourage removal unless pathology assoc.

most up to date (currently in use):
FDS RCS 2020 (Faculty of dental surgery, royal college of surgeons) - change from soley therapeutic approach to mixed intervention

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5
Q

nerves at risk during SR L8s

A

lingual
IAN
mylohyoid and long buccal - less common and effects less obvious

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6
Q

location of lingual n

A

varies

  • lies on superior attachment of mylohyoid muscle
  • at level of lingual plate in 15-18%
  • 0-3.5mm medial to mandible
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7
Q

impacted meaning

A

tooth eruption is blocked
- full/ partial functional position

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8
Q

incidence of impacted lower third molar

A

around 50%

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9
Q

consequence of impaction

A
  • caries
  • periconronitis
  • cyst formaiton
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10
Q

U removal indications

A
cheek biting/buccally erupted
overeruption
traumatising L operculum
PE and impacted
non-fct
pt undergoing GA
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11
Q

therapeutic indication of wisdom extraction

A
  • caries (8/7)
  • pericoronitis
  • periodontal disease (7d)
  • local bone infection
  • Dentigerous cyst
  • tumours
  • external root resorption of 7/8
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12
Q

SIGN vs NICE

A

SIGN - ≥1 episode of infection

NICE >1

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13
Q

imaging

A

OPT
(+/- PA)
+/- CBCT (3D relationship to nerve)

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14
Q

clinical assessment of M3M

A

eruption status - how many cusps seen
PD status - pockets distal to 7?
TMJ - rule out TMJ, similar pain to pericoronitis
exclude other causes
local infection
caries/resorption
occlusal relationship
regional LNs
any associated pathology
degree of surgical access
working space
STs

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15
Q

Types of imapction

A

- plus transverse (buccal / lingual)
- aberrant ( in odd place)

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16
Q

working space

A

distance between L7 and ascending ramus

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17
Q

radiological assessment

A
  • orientation and position (impaction)
  • impaction depth
  • relationship to IDC/MS

follicular width
working distance
crown - size, shape, caries
roots - number, morphology, apical hooks
bone levels
adjacent tooth
any surrounding pathology
- dentigerous cyst
- loss of bone distal to crown

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18
Q

when to consider when follicle turning to dentigerous cyst?

A

if follicle > 3mm size

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19
Q

3 key radiographic signs of M3M - possible increased risk to IAN

A

diversion/deflection of canal
darkening of root where crossed by canal
interruption of tram line / lamina dura of canal

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20
Q

8 radiographic signs of possible increased risk to IAN - M3M removal

A
diversion/deflection of canal
darkening of root
interruption of white lines/LD of canal
deflection of root
narrowing of IDC
narrowing of root
dark and bifid root
juxta apical area?
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21
Q

juxta apical area

A

well-defined radiolucent area adjacent that isn’t related to PA pathology
can appear corticated
lamina dura round tooth intact
lateral to root rather than apex

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22
Q

what is the most common orientation of impaction? M3M

A

mesial 40%

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23
Q

what is orientation of impaction measured against?

A

the curve of spee

  • curve of occlusal plane
  • draw lines through long axis of 7 and 8 and compare
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24
Q

what are the types of depth of impaction and what does it indicate?

A
  1. superficial - 8 crown relate to 7crown
  2. moderate - 8 crown to 7 crown+root
  3. deep - 8 crown to 7 root
  • amount of bone removal required
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25
why is L. disto-angular 8s difficult to extract?
* bone removal required (ascending ramus dense bone) * vector of movement during elevation is distal so tooth has nowhere to go * roots of 8 often v close to roots of 7 - can make it difficult to get an application point to elevate (also care not to damage 7 roots during mesial bone removal)
26
pericoronitis definition
- Inflammation around the crown of a **PE** tooth - need communication with oral cavity if not visible careful probing 7d for comunication
27
pericoronitis aetiology
- food and debris get trapped under operculum - inflammation/infection
28
S+S of pericoronitis
``` pain swelling (IO or EO) bad taste pus discharge occlusal trauma to operculum ulceration of operculum evidence of cheek biting foetor oris limited mouth opening dysphagia pyrexia malaise regional lymphadenopathy ```
29
which LNs are often raised and palpable in pericoronitis?
SM or upper cervical chain
30
pericoronitis EO swelling
severe cases | often at angle of mandible and may extend into SM region
31
spread of infection of pericoronitis
laterally into cheek distobuccally under masseter (submasseteric abscess and profound trismus) sublingual SM area around tonsils and paraphyaryngeal space (dysphagia) less commonly - through anterior pillar of fauces area into SP (dysphagia)
32
tx of pericoronitis
- I+D of pericoronal abscess if required +/- IDB - irrigation - warm saline in 10-20ml syringe w blunt needle under operculum - ext U8 if traumatising operculum - usually no ABs unless severe systemically unwell EO swelling immunocompromised e.g. diabetic - if large EO swelling, systemically unwell, trismus, dysphagia - refer to MF/A+E - phone first for advice - pt instructions ``` - no removal of 8 until pericoronitis resolved - removal of periculum not recommended - will just grow back ```
33
pericoronitis pt instructions
freq warm saline or MW - teaspoon salt warm water analgesia keep fluid levels up and keep eating (soft diet)
34
pericoronitis astringent/antiseptic
e.g. talbots iodine - applied with college tweezers - one drop beneath operculum not if have incised a localised pus collection not on fresh/open wounds
35
ext of L8 pericoronitis
generally don't ext affected 8 until acute episode has resolved - unless in hospital with GA for I+D - ext tooth then
36
operculectomy
prev | no longer carried out - often grows back
37
predisposing factors for pericoronitis
PE (usually 20-25yrs) and vertical or distoangular impaction opposing maxillary 8 causing mechanical trauma contributing to recurrent infection **upper resp tract infections**, stress and fatigue PC poor OH Previous episodes of pericoronitis insufficient space between ascending ramus of L jaw and distal aspect of 7 white race a full dentition
38
SDCEP pericoronitis initial management (emergency ?)
determine if **airway compromised** - pt unable to swallow own saliva/push tongue forwards out of their mouth - yes: emergency care/999
39
SDCEP pericoronitis adults
recommend analgesia no ABs unless signs of spreading infection (e.g. limited mouth opening, facial swelling), systemic infection, IC pt, persistent swelling rinse 0.2% CHX MW seek urgent dental care
40
SDCEP pericoronitis children
optimal analgesia soft toothbrushing around area rinsing mouth after food
41
pericoronitis SDCEP subsequent care for adults
US scaling/debridement to remove any foreign body, under LA irrigate 0.2% CHX MW ext if repeated episodes ext/adjust an opposing tooth where there is trauma to the inflamed operculum if the position of the tooth suggests it is unlikely to achieve fct in future
42
local measures for pericoronitis
irrigation and debridement
43
1st line ABs for pericoronitis
metronidazole 400mg, 9 tablets, x3 daily | avoid alcohol, not if on warfarin
44
2nd line Abs for pericoronitis
amoxicillin 500mg, 9 capsules x3 daily | - hypersensitivity reactions
45
RCS FDS guidelines - factors regarding M3M status
pt age and medical status (complications and recovery) risk of complications (IAN/leaving M3M in situ) pt access e.g. military opposing contralateral 8 if having GA
46
RCS FDS guidelines - diseased/high risk of disease development and asymptomatic
assess likelihood of disease development - high/low risk **high risk - consider surgical** if any doubt and tooth has higher risk of surgical complications - **active surveillance** until symptoms develop/early disease progression has been proven quiescent pathology may inc undiagnosed 7/8: - caries - PDD - resorption (internal or external) - cysts or tumours
47
RCS FDS guidelines - diseased/high risk of disease development and symptomatic
consideration for therapeutic exts is indicated for: single severe acute or recurrent subacute pericoronitis unrestorable caries of M3M or to assist Rx of adjacent tooth PDD compromising M3M and/or adjacent tooth resorption of M3M and/or adjacent tooth fractured M3M M3M periapical abscess, irreversible pulpitis or acute spreading infection surrounding pathology (cysts/tumours) associated w M3M tx to be considered: - therapeutic removal of M3M (or coronectomy) - removal of U3M
48
RCS FDS guidelines - non-diseased/low risk of development and asymptomatic
clinical review and radiographs if indicated. Make assessment of risk of disease and review interval factors for consideration for prophylactic removal - medical: planned medical tx/therapy that may complicate the likely surgery of M3Ms inc: pharmaceutical therapy (bisphosphonates, antiangiogenics, chemo), radio of HandN, immunosuppressant therapy - surgical: M3M lies within perimeter of a surgical field: mandibular fractures, orthognathic surgery, resection of disease (benign and malignant lesions)
49
RCS FDS guidelines - non-diseased/low risk of development and symptomatic
leave deeply impacted M3Ms with no associated disease manage other diagnoses causing pain in the region - TMD - parotid disease - skin lesions - migraines or other primary headaches - referred pain from angina, cervical spine - oropharyngeal oncology
50
RCS FDS guidelines - main reason for removal
infection
51
RCS FDS guidelines - significant radiological signs of risk to IAN
diversion of IAN canal darkening of root interruption of cortical white line
52
RCS FDS guidelines - CBCT
not routinely evidence it doesn't offer benefit in reducing incidence of IAN neurosensory disturbance - if findings expected to alter tx decision - see if direct contact or bony wall between
53
RCS FDS guidelines - common tx
``` referral clinical review removal of M3M ext of U8 coronectomy ```
54
RCS FDS guidelines - less common tx
operculectomy surgical exposure presurgical ortho surgical reimplantation/autotransplantation
55
RCS FDS guidelines - comment on NICE 2000
discouraged prophylactic removal | - but evidence this isn't always best - delays surgery and damage to 7
56
RCS FDS guidelines - why do coronectomy?
if close to IAN, reduce risk of injury
57
RCS FDS guidelines - coronectomy risks
pain and infection | potential future need for removal of the roots
58
RCS FDS guidelines - coronectomy contraindications
``` non-vital caries with risk of pulpal involvement tooth mobility apical disease association with cystic tissue that is unlikely to resolve if root left in situ tumours IC prev radio to H+N/tx before radio NM disorders diabetes unable to return for tx easily should complications occur ```
59
RCS FDS guidelines - CHX benefits
effective (gel more) - prevents alveolar osteitis
60
RCS FDS guidelines - adverse events of CHX
``` staining altered taste burning sensation hypersensitivity mucosal lesions ```
61
RCS FDS guidelines - routine radiographic screening of UE8s with no disease or symptoms
not recommended
62
RCS FDS guidelines - clinical review
just reviewing S+S only xray if clinical S/S of disease - routine BWs should inc distal of 7
63
RCS FDS guidelines - active surveillance
non-op management strategy for retained M3Ms - prescribed, regularly scheduled set of follow up visits that inc both clinical and radiographic examinations
64
explaining procedure to pt
flap - small cut in gum to get access sectioning - cut tooth into smaller pieces to remove it possible drilling sutures (stitches) - whether dissolvable
65
intra-op complications
``` fracture of tooth, root, alveolar plate, tuberosity TMJ dislocation haemorrhage ST damage OAC loss of tooth/root broken instruments damage to Rx in 7 if edentulous/atrophic mandible, aberrant 8 close to lower border, large cystic lesion associated w 8 - explain risk of jaw fracture - because your L jaw is thin - it is rare but could break, we would arrange for it to be sorted - break can sometimes happen post-op direct trauma to IA NV bundle ```
66
loss of tooth/root into:
lingual space MS pterygoid space
67
ST damage
puncture/laceration with instruments - gingivae/FOM/palate burns - from handpiece resting on L lip crush - papillae/lip tears - gingivae/palate
68
damage to Rx in 7
if this happens temp Rx placed at time then back for permanent Rx
69
post-op complications of M3M extraction
pain swelling bruising bleeding infection with pus jaw stiffness/limited mouth opening dry socket (localised osteitis) Nerve damage : - numbness (anaesthesia) or - tingling (paresthesia) of L lip, chin, side of tongue usually temporary - recovery up to 18-24m - dysaesthesia (rare) - reduced sensation - hypoaesthesia - heightened sensation - hyperaesthesia altered taste (rare)
70
rare post-op complications
Osteomyelitis Osteoradionecrosis MRONJ actinomycosis
71
how to explain dry socket to a pt
a slower healing painful socket 1-2wks to settle come and see us
72
why can altered taste result?
chorda tympani arises from facial nerve, taste buds from ant 2/3 tongue, carries fibres via lingual nerve
73
how to explain dysaesthesia to a pt
painful, uncomfortable, unpleasant sensation of L lip, chin, tongue, sometimes neuralgic type pain
74
should you do CBCT?
if concerns of close proximity from radiograph - offer CBCT | - but would scan change tx?
75
damage to IDN stats
``` temporary (weeks/months) - average 10-20% permanent - average 1% and under - higher 5% and above if IDC and roots close proximity ```
76
discussing risks to nerves
can recover up to **18-24m** but after this time not much hope for any further recovery often discuss warnings as one e.g. lip/chin and side of tongue - %s similar if close proximity suggested by xray/confirmed by CBCT - explain in relation to the nerve that supplies lip/chin/teeth/gums on that side explain risks to side of tongue remain average because nerve runs in STs and can't be seen on xrays talk about IDC to pt (canal nerve runs in) - can only see bony canal
77
tx options
``` do nothing - monitor - may need local measures - irrigate, review, pt advice, risk of recurrence, food trap (surgical) extraction CBCT coronectomy ```
78
surgical access - flap design principle
max access with min trauma larger flaps heal just as quickly as smaller ones wide-based incision - circulation use scalpel in one firm continuous stroke no sharp angles adequate sized flap flap reflection should be down to bone and done cleanly minimise trauma to papillae no crushing keep tissue moist ensure flap margins and sutures will lie on sound bone ensure wounds aren't closed under tension aim for healing by primary intention - minimise scarring
79
stages of surgery of M3M ext
``` anaesthesia access bone removal and tooth division as necessary debridement suture haemostasis POIs post-op medication ```
80
access
buccal mucoperiosteal flap | +/- lingual flap (debate)
81
ST retraction/reflection
access | protect STs
82
retraction
should be on bone at all times not on STs - needs to go under periosteum avoid dissection occurring superficial to periosteum - reduce ST bruising/trauma may get post-surgery tingling due to pressure on nerve (temp)
83
what facilitates retraction?
flap design
84
where should you commence flap-raising?
commence flap raising at base of relieving incision (already gaping/bone visible)
85
instruments for ST retraction
minnesota retractor rake retractor howarth's periosteal elevator
86
instruments for ST reflection
Ash periosteal elevator Howarth's periosteal elevator Curved Warwick james elevator Mitchell trimmer
87
most difficult reflection - reflect with min trauma
papilla - tend to be well-tethered - try to release it before proceeding with reflection distally (avoid tears) mucogingival jct
88
why raise flap?
access to surgical site improve visibility, visualise application point facilitate bone removal
89
flap considerations
important structures (esp for relieving incision) e.g. nerves blood supply and healing aesthetics ease of suturing post-op
90
flaps and papillae
need to either include or exclude papillae
91
atraumatic/passive retraction
rest firmly on bone | aware of adjacent structures e.g. mental n
92
3-sided flap
Distal relieving incision - runs out buccally to avoid RM pad as sometimes lingual nerve runs there intracrevicular incision mesial relieving incision - better to include papilla as easier to suture back up
93
lingual flap and risk
variable use depends on procedure, visibility, access, amount and area of bone removal and surgeon can lead to stretching of **lingual n** which runs close to lingual aspect of L8s more morbidity with less experienced operators
94
envelope flap
Pros: - easier to suture back - lower risk of damage to vital structures - Reduced scarring - wider base assures vascularity Cons: - reduced access, challenging to reflect - tearing - periodontal damage and recession due to sulcular incision
95
what blade to cut a flap?
number 15
96
how to cut a flap?
incise with firm continuous stroke - feel area with finger first - pen grip - finger rest on sound support - use non-dominant index finger to apply tension to mucosa full thickness through mucosa and periosteum to bone
97
crevicular incision
hold scalpel in LA of tooth blade kept immediately against tooth surface
98
relieving incision
typically anterior to papilla draw blade downward/forwards across mucogingival jct draw blade forward more horizontally having crossed MGJ (to level of apices of teeth) - to make wider base so better blood supply
99
drilling
electrical straight handpiece with saline cooled bur - avoid surgical emphysema (air driven/ turbine) - can get infected round or fissure SS (often bone) and tungsten carbide (often teeth) burs protect STs
100
buccal gutter
start distal (just in front of lingual plate) and bring bur buccally and mesially for safety of lingual n (prevent drill slipping into lingual space) on buccal aspect of tooth and onto distal aspect of impaction aim - deep narrow gutter (at least as deep as bur head) - need to get to bleeding cancellous bone irrigate - visibility/avoid bony necrosis away from important structures where possible usually create gutter extending MD with position of application point dependant on root morphology/access
101
aim of bone removal
allow correct application of elevators on M and B of tooth, better visual access
102
when would you section a tooth?
if tooth removal still not possible with elevators +/- forceps and adequate bone removal
103
horizontal tooth sectioning
make cut higher than for a coronectomy so easier to get roots above CEJ only drill approx 5/6 through - leave E to protect adjacent structures then use and twist elevator to snap. Lever off
104
vertical tooth sectioning
works best on 2 rooted teeth elevate M+D aspects separately be v careful of roots of 7 occ need to section each root
105
lingual split technique
old technique prev used under GA, often in younger pts requires lingual flap lingual wall of 8 socket removed using a mallet and chisel can remove tooth in one piece by rotating it lingually takes away some bone behind tooth - good for distally impacted teeth
106
forceps commonly used for L
molars, cowhorns, universal, roots
107
forceps commonly used for U
8s, molars, universal, roots, Bayonet
108
types of debridement
physical irrigation suction
109
physical debridement
bone file/handpiece to remove sharp bony edges Mitchell's trimmer/Victoria Curette to remove ST debris don't scrape right at bottom of socket - risk IDN debris and any follicular or granulation tissue from chronic infection should be curetted - esp if hidden behind 7
110
irrigation debridement
sterile saline into socket and under flap | must irrigate below flap before you reposition it
111
suction debridement
aspirate under flap to remove debris | check socket for retained apices etc
112
2 methods of suturing
flap closure anatomical repositioning
113
When do you do flap closure
some suture flap across socket to lingual side, effectively closing the wound completely - do if on bisphosphonates/MRONJ risk
114
anatomical repositioning
most prefer to return flap to its original position, leaving a socket
115
aims of suturing
``` reposition tissues cover bone prevent wound breakdown achieve haemostasis encourage healing by primary intention ```
116
how to suture flap
usually use mesial suture first as your positioning suture - can redo it more securely at end need suture in each papilla put a suture in the vertical relieving incision if risk of bleeding normally use resorbable
117
post-op advice
pain - expect it - take analgesia before LA wears off aid healing - don't rinse for several hrs, then hot salty MW - softer/cooler foods for rest of day, softer foods for next week, eat on other side - don't explore socket with fingers/tongue - be careful not to bite/burn L lip whilst numb - brush rest of teeth as normal - no smoking/avoid as long as can - increased risk of dry socket regardless - CHX MW x2 daily - not straight after brushing/around eating - avoid alcohol and exercise that day (increase bp - bleed) deal w bleeding - damp gauze/tissue and bite for 20-30mins - contact details - you/A+E other symptoms to expect - swelling - peak 48hrs, resolves 7-10days, if develops after 2-3 days likely infection, ice packs 5mins on off for 1hr that day - bruising - settles 1-2wks - jaw stiffness/limited opening, usually settles 1-2wks, keep eating and drinking sutures - usually resorbable - may take a few days up to 2 wks to resorb - if non-resorbable (prolene) - warn pt they need removed *contact details
118
indications for coronectomy
high risk of IAN injury vital M3M healthy non-IC pt access to care for (and understanding of) related coronectomy risks
119
Tara Renton paper 2005
Randomised controlled trials shows much lower risk to IAN with coronectomy compared to SR
120
principles of coronectomy
remove all enamel tooth roots must not be mobile after decoronation smooth finish to decoronated tooth and surrounding bone
121
what is coronectomy?
alternative to SR of entire tooth when there appears to be an increased risk of IAN damage with SR crown removed with **deliberate retention** of root adjacent to IAN
122
aim of coronectomy
reduce risk of IAN damage
123
risks of coronectomy
if root is mobilised during crown removal the entire tooth must be removed (more likely with conical fused roots) leaving roots could result in infection (rare) can get a slow healing/painful "socket" roots may migrate later and begin to erupt through the mucosa, may require ext
124
Abs
not used routinely - consider for prolonged, difficult procedures or in IC pts e.g. diabetic can administer pre, peri or post op under GA sometimes one IV dose given peri-op amoxicillin/metronidazole - 3/5/7 days
125
coronectomy procedure
LA raise flap - generally standard 8 designs (bone removal) transection of tooth 3-4mm below the E of the crown into D elevate/lever crown off without mobilising the roots - only go 2/3-3/4 through with drill as if cut all way through risk to lingual nerve and artery pulp left in place untxed if necessary - further reduction of roots with a rosehead bur to 3-4mm below alveolar crest - not always possible irrigate socket flap replaced - some reposition flap leaving socket open, some close flap completely (primary closure with periosteal release if necessary) HAPOI
126
follow up of coronectomy
variable review 1-2wks, 3-6m, 1yr some review at 2yrs but most discharge back to GDP after 6m/1yr radiographic review - 6m or 1yr or both - after that if symptomatic - some take an immediate or 1wk post-op radiograph
127
U8s ext
generally easier to remove can do in practice but occ v difficult remove by elevation (Wj, Couplands) +/- forceps (U8s) support tuberosity w finger and thumb - if undue resistance to elevation/ext then excessive force can fracture the tuberosity - use forceps and support to reduce risk if not possible to get access to a PE U8 - can raise a buccal flap +/- bone removal
128
peri-op control of bleeding
``` pressure LA w vasoconstrictor artery forceps diathermy bone wax ```
129
post-op control of bleeding
pressure (finger/swab) LA w vasoconstrictor infiltration in STs, inject into socket or on a swab diathermy haemostatic agents - surgicel/kaltostat sutures bone wax smeared on socket wall with a blunt instrument haemostatic forceps/artery clips
130
Contraindication of coronectomy
◦ Immunosuppressive ◦ Carious tooth ◦ Periodontal involved (mobile) ◦ Career wouldn’t allow regular checkup ( military )