Post operative complications of periodontal surgery

1. Dr. Ritam Kundu. MDS PGT
Dr. R. Ahmed Dental College & Hospital, Kolkata

2. Factors responsible for bleeding associated with a surgical
procedure:
1. Extent of flap reflection or size of the surgical site
2. Inflammation of tissues and soft tissue management
3. Presence of unhealthy granulation tissues
4. Accidental perforation of any major blood vessel in the surgical
site
5. Time to complete the treatment
6. Vasoconstrictor used in the surgery
7. Blood pressure and medications used by the patients
Approximate amount of blood in an adult human: 4 – 7 L.
During blood donation amount given: 473 ml.
With loss of >30% of blood volume, symptoms of hypovolemic shock
might develop.

3.  McIvor and Wengraf (1966) reported that the maximal volume of
blood loss during periodontal surgery was 62 mL, and the minimal was
0.5 mL.
 Baab et al. (1977) determined that, on average, 134 ml blood was
lost (range: 16 to 592 ml) during one sextant of periodontal surgery.
 Barganza et al. (2005) reported that the intraoperative bleeding
ranged from 17.8 – 9.6 to 31.9 – 15.7 mL (depending on preoperative
NSAID intake)
Blood loss during different surgical procedures
Labour (Ramadani H. 2004) 300 – 500 ml
Caesarean sections 750 – 1000 ml
Maxillofacial surgery (Yu CN et
al. 2000, Pineiro-Aguilar A et al.
2011)
617.6 ± 438 ml

4.  Flanagan D. (2003) reported that 420 ml blood can be lost in 30
minutes from an artery 2 mm in diameter with an estimated blood
flow of 0.2 ml per beat (70 beats per minute). (0.2 X 70 X 30 = 420 ml)
 Several types of hemorrhagic patches can develop as a result of
injury: petechiae (<2 mm in diameter), purpura (2 to 10 mm), and
ecchymosis (>10 mm).
 These findings reflect blood within the tissue due to injury of small
capillaries and blood vessels in the skin or mucous membranes. These
patches are non-elevated, rounded, or irregular .
`
Moore et al. (2007) described that the intraoperative
hemorrhage ranged from 54.9 – 36.0 to 70.2 – 53.0 mL (depending
on epinephrine concentration in the local anesthetic).
 Zigdon et al. (2012) found that the blood loss during periodontal
flap surgery ranged from 6.0 to 145.1 mL, with an over all mean loss
of 59.47 – 38.2mL.

5. These are initially of red-blue color, reflecting the presence of
blood.
After 1 to 2 days, the sites appear black and blue (purple).
Day 6 - the color changes to green, and this reflects the presence
of biliverdin.
Day 8 – 9 : Yellowish-brownish denoting the presence of bilirubin.
2 -3 weeks: Discoloration usually fades in 2 to 3 weeks.
Color changes of ecchymosis from Day 0 to Day 21

6. During periodontal Flap Surgery, the incidence of hemorrhagic
patches can be reduced with careful soft tissue management.
1. When possible, vertical releasing incisions should be avoided
because they severe blood vessels and result in increased
bleeding.
2. During flap elevation, elevators should rest on bone and not on
soft tissue
3. Suctioning should be done on bone as opposed to soft tissue.
4. Apply pressure to the tissue for several minutes to minimize
blood clot thickness and to ensure bleeding has stopped.
These actions will reduce ecchymosis and hematoma formation.
The finding of an ecchymosis does not require therapy. Verbal and
written postoperative instructions should inform and reassure a
patient that this sequela is not a problem.

7. Bleeding during Free mucosal grafting from
palate
 It occurs due to damage to the greater palatine artery or one of its
branches.
 Proper medical history will prevent emergencies of this type.
 The proper area for the donor incision is the lateral third of the palate
near the teeth, as far as possible from the large vessels coming out from
the greater palatine foramen.
 Packing the palate with gauze sponges and having the patient exert
pressure upward with the tongue frequently suffices to initially control
the bleeding. Application of pressure, helps to reduce the bleeding -
improved visualization - better control over the situation.
 A properly fitting removable partial or full denture serves very nicely
as a stent. If the patient has such an appliance, care should be taken to
obtain the donor graft from within the denture-bearing area of the
palate.

8. Management of Intra-operative bleeding :
1. Fabricate a surgical stent preoperatively whenever a connective
tissue graft is to be harvested from the palate.
2. If the palatine artery is cut. inject a local anaesthetic into the
greater palatine canal and apply pressure to the wound to
achieve initial haemostasis.
3. After haemostasis has been achieved. decide whether the patient
should be admitted to the hospital for monitoring.

10.  The harvesting of autogenous bone
grafts from the mandibular angle is a safe
procedure with a low rate of complications.
 Because these grafts consist mainly of
cortical bone, only small areas of cancellous
bone are exposed in the donor region.
 Any major bleeding from bone graft
harvesting should absolutely be stopped
before suturing to prevent hematoma
resulting from postoperative bleeding into
the surrounding tissues.
 A very effective way to do this is to apply
an absorbable hemostat agent, such as
oxidized regenerated cellulose (Tabotamp).
until hemostasis has been achieved.

11. Bleeding during implant placement
Cautiousness while placing implants with the presence of a
submandibular or sublingual concavities in the mandible; if there is a
large undercut the lingual plate can be inadvertently perforated,
resulting in hemorrhage.
Lingual concavities with a depth of 6 mm were reported in 2.4% of
assessed jaws in CT scans. Quirynen M 2003
The bleeding can cause swelling, and the tongue may be displaced
superiorly and posteriorly, obliterating the airway and resulting in
tachypnea, dyspnea. Kalpidis CD 2004
Clinicians should be aware that there may be a latency period after
arterial trauma, and hemorrhage can occur several hours later. ten
Bruggenkate CM et al. 1993
When there are concerns regarding the topography of the mandible,
obtain a CT scan.
Digitally palpate the submandibular and sublingual areas before and
after flap elevation to determine the extent of the undercut.

12. Goodacre et al. 2003 indicated that postoperatively approximately
24% of all dental implant sites manifest an ecchymosis.
The location of an ecchymosis can be influenced by gravity. It may be
noticeable only at the site of injury, or it may extend to the inferior
border of the mandible or onto the chest. It reflects that the bleeding
under the flap and blood transcended along the fascial planes.
Ecchymosis extending to the pectoralis
muscles after removal of a maxillary
bone cyst.

13. Moderate to severe cases of chronic periodontitis may warrant
periodontal surgical procedures Powell CA et al. 2005
Sources of infection during surgery in oral cavity include:
Improperly sterilized surgical instruments
Contaminated hands of surgeon and assistant due to improper
asepsis protocol
Air of the operatory
Patient’s perioral skin, nostrils, and saliva

14. As postoperative infection can have a significant effect on the
surgical outcome, preventive measures like strict aseptic protocol,
anti-infective measures like proper sterilization, disinfection, barrier
techniques, and other measures should be taken.
Pack PD, Haber J. 1983. Checchi L, Trombelli L, Nonato M. 1992.
The prevalence of infections after a variety of periodontal procedures
ranged from 1% to 5.4%; in the same studies, patients not receiving
antibiotics before, during, or after surgery had an infection rate that
ranged from 2.33% to 5.4%.
Abu-Ta’a M et al. 2008, If proper asepsis protocols are taken, there is
a very low rate of postoperative infection following periodontal
surgery, thereby obviating the need for using antibiotics as a
prophylactic measure.

15. Studies conducted by Demolon et al, Loos et al. have concluded that
use of antibiotics may have helped to control initial inflammation,
but had no direct effects of clinical significance on bone regeneration
or soft tissue attachment at 12 months.
Studies conducted by Scopp IW et al. (1977) and Tseng CC et al.
(1993) supprted the postoperative prophylactic use of antibiotic to
reduce postoperative infection and associated complications.
Hence, the judgment must be made by the clinician as to the
necessity of prescribing antibiotic coverage after a surgery, after
consideration of different factors.
(e.g., if a surgical procedure is complicated, multiple implants are
placed, implant placement takes a prolonged period of time, bone
grafts were placed, or the patient is medically compromised).

16. It can occur secondary to impaired wound healing.
This can be caused by increased bacterial colonization of the wound
or reduced local or systemic resistance.
In the case of secondary intention wound healing, the response to
increased bacterial colonization of the wound is - increased wound
secretion.

17. In Esthetic periodontal and implant surgery, most of the surgical
wounds heal by suture-assisted, primary intention healing.
If postoperative wound infection occurs, the wound secretions
collect in the closed wound space. The bacteria and degradation
products cannot flow out and therefore collect in the surrounding
tissues, which frequently results in the spread of infection and
abscess.
The consequential increase in tissue pressure impairs the blood
supply to the region, thus promoting the further spread of infection.
Once the wound margins are separated, the secretions can drain,
decreasing tissue pressure and allowing wound healing by secondary
intention.

18. Postoperative Wound
Dehiscence
Postoperative wound dehiscence secondary to infection is characterized
by the separation of the wound margins and the drainage of secretions
out of the wound as a result of increased tissue pressure.
This can result in increased pain and swelling in the surgical
region.
It affects the desired esthetic outcome of periodontal plastic
surgery
Wound dehiscence can also occur as a primary entity independent of
wound infection.
• Both infectious and non-infectious wound dehisence have the
same clinical consequences

19. Potential causes of non-infectious, primary wound dehiscence include a
compromised blood supply to the region, inadequate flap mobility,
insufficient sutures, poor suturing techniques, and iatrogenic trauma.
To achieve tension free flap mobility, the flap should be released by
giving periosteal incision, so that the buccal margin can be advanced
over the lingual margin by 2 to 3 mm to facilitate tension free closure.
Mattress sutures in conjunction with interrupted sutures can be used to
offset muscle pull and possibly inhibit wound dehiscence.
.

20. Management:
1. Symptomatic local treatment with 0.1% chlorhexidine solution and
topical 1% chlorhexidine gel
2. The sutures should be left in place until satisfactory healing has
occurred.
3. If the patient shows signs of poor general health, systemic
antibiotics should be administered to decrease the risk of abscess.
4. In many cases, it will be necessary to repeat the procedure after the
site has healed.
5. Wound dehiscence following implantation and hard tissue
augmentation can result in the exposure of barrier membranes. In
these cases, the surgery can be repeated after complete healing has
occurred.

21.  Flap perforation is a potential complication that most frequently
occurs during partial-thickness flap elevation.
 The thinner the soft tissue, the more difficult the flap elevation.
 The risk of perforation is higher while elevating partial thickness flap,
at the mucogingival junction due to relative thinness of the tissue at this
region.
 The presence of scar tissue from previous surgery (eg, apicoectomy)
further complicates the procedure as it adheres the flap with the
underlying periosteum.
 Flap perforation can increase the risk of flap necrosis by impairing
local blood flow.
 The use of a perforated flap to cover a connective tissue graft can
have negative consequences for graft integration due to compromised
vascular supply.

22. 1. The flap elevation must be done in a slow and very controlled
manner to complete the flap dissection without enlarging the
perforation.
2. In case of full thickness flap, further dissection in the
perforation area should be done by pressing the blade to the
underlying bone with relatively heavy pressure.
3. After completion of flap elevation, the tear may be left open or
closed with sutures, depending on the size of the perforation.
4. If sutures are placed, fine suture material (6-0, 7-0) be used to
prevent the suture from tearing the flap and enlarging the
perforation.
5. The surgical procedure itself is completed as originally planned
Management:

23.  Grafts that are too thick will result
in an exaggerated tissue profile in
the area.
 Such bulky tissue may be easily
traumatized during brushing.
 A large graft may extend beyond
the margins of the recipient site and,
if not properly trimmed at the time
of surgery, marginal necrosis may
ensue.

24.  Scar formation although rare but if happens, predictable
prevention of scars from horizontal incisions is not possible.
 Unlike vertical scar correction, horizontal scar correction is rarely
successful. Therefore. horizontal incisions in the esthetic zone
should be avoided if at all possible.
 An attempt can be made to reduce vertical incision scars or thick
grafted tissue with a rough diamond or scalpel.

25.  Flap necrosis is a relatively rare
complication and if it happens, it
leads to a negative effect on
healing.
 Full or partial flap necrosis
requires immediate sharp
dissection of the necrotic tissue
with a scalpel or surgical scissors.
 Any areas of exposed bone
should be covered with
chlortetracycline-soaked strips and
a periodontal dressing.
 Secondary surgery, if needed,
must be postponed until complete
healing is achieved.
Day 1
• Diffusion of nutrients from
the recipient bed
Day 3
• Revascularisation
• New capillary anastomosis
Day 21
• Graft integration

26.  If only parts of the graft are
necrotic, only the necrotic areas need
to be removed; this can be done with
surgical scissors or a scalpel.
 If the graft is completely necrotic,
removal of the entire graft is
indicated.
 If full or partial necrosis of an
autologous connective tissue grafts
occurs, achievement of the desired
surgical outcome cannot be expected.
Secondary surgery normally must be
postponed for at least 3 months until
complete healing has been achieved.

27. The exposure of barrier membranes, bone particles, bone graft
materials, bone blocks, bone plates, or fixation crew invariably results
in bacterial contamination and the consequent resorption of
augmented bone, ultimately leading to the failure of the entire
augmentation procedure.
Causes:
 Flap necrosis, wound dehiscence of inflammatory and non-
inflammatory origin.
 Mechanical stresses on the surgical site due to micro movements
caused by removable prostheses.
 Inadequate primary fixation of the graft to the recipient bed with
screws
 Failure to fill the spaces between the recipient bed and the graft
with bone particles or bone graft material.
 Membrane or Titanium mesh exposure

28. These factors could result in the downward growth of
connective tissue between the transplant and the recipient
bed, resulting in impaired integration of the bone graft.
Management:
 Bone graft exposure is extremely difficult to treat and has a
poor prognosis.
 It is not possible to repeat the graft procedure unless only a
small area is exposed and the soft tissues around the exposed
area have completely healed This generally is not the case until
at least 4 weeks after augmentation surgery.
 The exposed site should be treated with 0.2% chlorhexidine
solution or 1% chlorhexidine gel 4 times a day.

29.  Thoroughly remove the connective tissue and particulate
augmentation materials enveloped in connective tissue between the
graft and the recipient bed. The exposed bone must be debrided to
remove the bacterially contaminated bone tissue.
 In many cases, the buccal volume of the bone graft must be reduced
to achieve tension-free soft tissue closure.
 Seven-day systemic antibiotic treatment is also recommended in
these cases (amoxicillin, 500 mg three times daily, or clindamycin,
300 mg three times daily for patients allergic to penicillin). Even with
treatment, the chances of achieving complete coverage of the graft
and, thus, saving at least part of the augmented tissue are still poor.
 If this treatment attempt fails (and if there is extensive exposure),
removal of the entire graft (membrane, bone particles, bone
substitute material, and/or fixation screws) is indicated.
 The augmentation procedure can be repeated after complete healing
has been achieved.
 It will be necessary to wait another 6 months before implant
placement.

30. Even without membrane exposure, a certain amount of resorption
can always be expected when bone block grafts or bone plates are
used .
The prominence of the fixation screws beneath the mucosa during
the healing period is suggestive of excessive resorption.
After the suspicious site is opened on the day of surgery, it often
becomes apparent that entire sections of the fixation screws are
not covered by bone.

31. Signs and symptoms:
A. Paresthesia (numb feeling, burning, and prickling)
B. Hypoesthesia (reduced feeling)
C. Hyperesthesia (increased sensitivity)
D. Dysesthesia (painful sensation)
E. Anesthesia (complete loss of feeling of the teeth, the
surrounding skin, and mucosa)
 Intrusion into the inferior alveolar or
mental canal during osteotomy
development can cause transaction,
tearing, or laceration of nerves.
 In addition, within the soft tissue, the
lingual or mental nerve may be injured
by the scalpel, or needle penetration.

32. Tests to Discriminate Neurosensory Damage:
Hegedus F, Diecidue RJ 2006
1. Light touch test: a soft brush is applied to the lip, and the patient is
asked in which direction the stimulus was applied.
2. Pain test: a 27-gauge needle can be inserted to determine whether
the patient perceives pain.
3. Two-point discrimination test: Calipers are opened progressively at 2-
mm increments until the patient is able to discriminate the caliper ends
as two separate points of contact.
4. Ice or a heated mirror handle (Binahmed A 2005 et al.) can be used to
determine whether the patient is able to discriminate between hot and
cold.

33. Management:
 Radiographs should be taken to ascertain the implant’s position.
 If it is intruded into a nerve canal, that the implant be slightly
withdrawn a couple of turns or removed altogether.
 The next day, if a patient complains of symptoms of altered
perception, it needs to be determined whether they are due to the
presence of the implant in the nerve canal or sequelae of soft tissue
manipulation or edema.
 If the implant is the problem, it should be removed.
 If the twist drill or the implant did not encroach upon the canal, it is
possible that bone was compressed, thereby placing pressure on the
nerve. The implant should be slightly withdrawn several turns.

34.  In the event of uncertainty with regard to implant penetration into a nerve
canal, a CT scan may be needed to provide additional information.
 The clinician should ascertain the depth and extent of the sensory
dysfunction. Altered sensation regarding the lip and tongue and drooling
should be documented.
 Numbness for 6 weeks suggests that the nerve sheath was disrupted, and
the patient should be referred for possible microsurgery. Day RH 1994
 When an implant is not within a nerve canal, Kraut and Chahal suggested
that altered sensation can be due to an inflammatory reaction; they
prescribed steroid therapy or anti-inflammatory medication (ibuprofen, 800
mg, three times a day)for 3 weeks. They recommended referral to a
neurosurgeon if improvement was not seen at 2 months.
 To avoid nerve injuries, the location of the inferior alveolar nerve and
mental foramen must be determined prior to osteotomy development.
Evaluate periapical and OPG; if needed, a CT scan should be obtained

35. Periapical Implant Pathosis and Endodontic
Considerations
Quirynen et al. 2003 reported that 1% of implants placed during a 5-
year period developed periapical pathosis. The condition is also referred
to as retrograde peri-implantitis.

36. Causes:
•Incorrect positioning of an implant
• Striking an adjacent tooth
• Impinging on the tooth’s blood supply
• Overheating of the bone during the osteotomy
In such cases, the damaged tooth will need endodontic therapy, an
apicoectomy, or an extraction.
Preventive Measures:
 The angulation of adjacent teeth and dilacerations of roots need to
be radiographically assessed prior to implant placement.
 1.5 to 2 mm of bone should be present between an implant and the
adjacent tooth.
 Inspection of a radiograph with a guide pin at a depth of 5 mm
facilitate osteotomy angulations corrections.

37. Teeth adjacent to an implant site that need endodontic treatment
should be treated prior to implant placement. Flanagan D. 2002
Treatment for retrograde peri-implantitis:
1. Inactive lesions are asymptomatic and, according to Quirynen et al.
2003 require no therapy when the radiolucency size remains stable.
2. In contrast, Flanagan 2002 suggested that any periapical implant
radiolucency should be surgically debrided to preclude exacerbation
of the lesion and implant loss.
3. If a site is infected, the patient may present with pain, tenderness,
swelling,and a fistulous tract. Periapical lesions around implants that
are symptomatic need to undergo surgical debridement and
antibiotic therapy.

38.  A potential, although uncommon,
complication of implant placement is
fracture of an atrophic mandible.
 Tolman and Keller (1991)
concluded that fractured mandibles
detected shortly after implant
placement were due to stress
fractures at weakened sites where
implants were placed.

39. Treatment consideration:
1. Optimum balance between selection of implant size and
consideration of available bone volume.
2. Park and Wang 2005 cautioned that there is increased
vulnerability to fracture once the resorbed mandible has <7 mm
of bone height and <6 mm of width.
3. When a fracture occurs, Laskin 2003 suggested that the degree of
displacement is the critical determinant in selecting the
appropriate treatment. If the fracture manifests minimal mobility
or displacement, the implant should be maintained. However, if
there is a large amount of displacement, closed or open fracture
reduction is needed with or without retention of an implant along
the fracture line.
Predisposing factors:
•Osteoporosis
•stress at the implant location and trauma.
•Insertion of long and wide implants in an atrophic mandible

40. Inadvertent Penetration Into Maxillary Sinus or
Nasal Fossa
Unintentional penetration into the maxillary sinus or the nasal cavity
with the drill or the fixture is one of the complications associated with
maxillary implant placement.
Insertion of an implant several millimeters into the sinus or nasal cavity
is usually well tolerated. Bra°nemark PI et al. 1984.
However, in these situations it is prudent to prescribe an antibiotic and
a decongestant.

41. Complications Associated With Sinus Elevation
The most common problem is perforation of the Schneiderian
membrane during its elevation (occurrence: 25% to 40%)
Perforations should be occluded with a bioabsorbable barrier
membrane prior to placing graft material. Barone A et al. 2006,
Schwartz-Arad D et al. 2004
.
Ardekian L et al. 2006 concluded
that intraoperative complications,
such as membrane perforation, did
not detrimentally influence implant
survival.

42. Complications associated with Lateral window
approach
Elian et al. 2005 recently reported that 20% of the time intraosseous
arteries are <16 mm from the crest of the ridge and may present a
complication during lateral window preparation.
Septa may be encountered in the
maxillary sinus and complicate
membrane elevation. They have
been detected in 31.7% of patients,
and most were found between the
second premolar and the first molar.
When septa are encountered on the
antral floor, Boyne and James - 1980
recommended cutting them with a
narrow chisel and removing them
with a hemostat.

43. During implant insertion, if an implant is inadvertently displaced into the
sinus cavity, it must be retrieved by creating a lateral window.
After a sinus lift, if an infection develops (pain, redness, and
tenderness)with out fluctuance, antibiotics are administered. Once
there is fluctuance, incision and drainage are performed in conjunction
with prescribing systemic antibiotics.
A persistent infection dictates that the graft material might be infected
and hence should be removed and the sinus flushed out.

44. Symptoms of sinusitis:
• Fever
• Facial pain (that increases on leaning forward)
• Yellow-green purulent discharge from the nose, which may drain
posteriorly causing a cough and malaise.
• Popping of the ears and muffled hearing
• Swelling of the periorbital tissues
• Referred pain to the maxillary teeth.
Sinus infections can have serious consequences .Uncommonly, they can
progress to unilateral or bilateral pan-sinusitis or to cavernous sinus
involvement.
CT scans are an important diagnostic aid in predetermining the
dimensions of the maxillary sinus and the presence of unexpected
findings(e.g.,tumors and intraosseous arteries).

45. When the skin is palpated, it usually produces a crackling sensation as
the gas is pushed through the tissue. This is referred to as crepitus. The
crackling sound is pathognomonic for tissue emphysema, and pain is not
a usual feature of tissue emphysema.

46.  It is caused by inadvertent introduction of air into tissues under
the skin or mucous membranes. Air from a high-speed handpiece,
air/water syringe or air polishing or air abrasive device can be
forced into a sulcus, surgical wound, or a laceration in the mouth.
 The air can follow the fascial planes and create a unilateral
enlargement of the facial and/or submandibular regions.
 The clinical presentation is typically a facial or cervico-facial
swelling coincident with dental treatment.
 Swelling can close the eye, and it can appear several hours after
therapy.
 It is also possible to have tissue emphysema and no crepitus.

47. Treatment:
1. Antibiotic and mild analgesic therapy, Antibiotics are prescribed
because bacteria may have been introduced into the tissue with
the compressed air.
2. Close observation, and reassurance.
3. Once a large amount of air is projected into the tissues, it may
tract into the mediastinum and pleural space.
4. The possibility of mediastinal involvement should be recognized,
and the patient should be monitored appropriately.
5. If a patient reports any airway distress, he/she needs to be sent
to a hospital.
6. Symptoms usually subside in 3 to 10 days.

48. Intraoperative ingestion or aspiration of a dental screwdriver or an
implant can present a life-threatening complication.
If a device is aspirated, it is necessary to refer the patient to an
otolaryngologist for evaluation and treatment.
Usually aspiration of a foreign body will be accompanied by coughing;
however, it is possible for a patient to aspirate an object without
coughing.
 Worthington (Int J Oral Maxillofac Implants 1996) reported a
situation in which a hex driver was swallowed, resulting in potentially
serious consequences, including infection and blockage. It was noted
that the instrument may pass naturally; however, these patients should
be referred to a gastroenterologist for evaluation and possible
endoscopy to remove the object.

49. In this regard, Munter DW (2008) indicated that once an object is past
the esophagus and is<20 mm in length, it has a 90% chance of passing
uneventfully.
These types of mishaps can be avoided if a piece of silk suture is tied
to the screwdriver or another device before it is inserted into the
mouth.
 This provides the clinician a fast way to identify and retrieve a
dropped instrument.
In addition, it is sensible to place a large piece of gauze into the
patient’s mouth so that when an object is dropped, it is easily retrieved

50. Postoperative discomfort after periodontal and dental implant insertion
can be reduced
 if incisions are neat
 intact periosteum is reflected
 tissues are handled gently
 flaps are sutured so healing occurs by primary intention.
It is recognized that careful manipulation of hard tissue (i.e., bone)
also reduces postoperative pain. Hence osteotomies with sharp burs
and avoiding excessive pressure while drilling.
If the temperature exceeds 47°C for 1 minute and the bone is burnt
(brown color seen), the patient may experience postoperative
discomfort because there will be bone necrosis.
Eriksson AR, Albrektsson T. Temperature threshold levels for heat-induced bone tissue injury:
A vitalmicroscopic study in the rabbit. J Prosthet Dent 1983

51. Sometimes, color changes cannot be seen because the thermal insult is
occurring in the deeper portions of the osteotomy. Careful attention to
irrigation protocols and intermittent drilling pressures are important .