Chapter 25: Dentoalveolar & Preprostethic Surgery Flashcards
(86 cards)
1
Q
Why is it necessary to use a bite block when removing mandibular 3rd molars?
A
To diminish pressure on the contralateral TM joint
2
Q
Why is distilled water not used for irrigation?
A
Distilled water is a hypotonic solution and will enter cells down the osmotic gradient. This will cause cell lysis and rapid death of bone cells
3
Q
What is the anatomic structure that can interfere with efficient removal of a maxillary first molar?
A
Root of zygoma
4
Q
What anatomic layers are penetrated or contacted when performing an IAN block?
A
Mucosa, buccinator, pterygomandibular space and periosteum
5
Q
What muscles insert on the pterygomandibular raphe?
A
Buccinator & superior pharyngeal constrictor
6
Q
What two structures form a V-shaped landmark for an IAN block?
A
Deep tendon of temporalis muscles and the superior pharyngeal constrictor
7
Q
What is the orthodontic indication for removal of an impacted third molar?
A
Facilitate distal movement of the second molar
8
Q
What is the SLOB rule?
A
Same lingual (palate), opposite buccal. Used to determine location of impacted tooth
9
Q
What is the advantage of an apically positioned mucoperiosteal flap for exposure of a buccally positioned impacted canine?
A
This flap design allows for the impacted tooth to erupt into attached mucosa and minimizes possible development of periodontal defects and pocket formation
10
Q
Where is the IAN most often located in relation to the roots of the mandibular 3rd molar?
A
Buccal to the roots and slightly apical
11
Q
The root of which tooth is most often dislodged into the maxillary sinus during extraction?
A
Palatal root of the maxillary first molar
12
Q
When the root tip of a mandibular third molar disappears from vier, where might it be dislodged?
A
- IAN canal
- Cancellous bone space
- Submandibular space
13
Q
What is the usually recommended sequence of extractions?
A
Maxillary teeth before mandibular teeth, posterior before anterior
14
Q
What complications are associated with the removal of freestanding, isolated maxillary molar?
A
- Alveolar process fracture
2. Maxillary tuberosity fracture
15
Q
How do you minimize the chance of dislodging an impacted max 3rd molar into the infratemporal fossa during surgical removal?
A
A FTMP flap that is up to the 2nd molar for appropriate visibility. Use a broad retractor distal to the molar while elevating it.
16
Q
When performing a surgical removal, should you completely section through the mandibular molar?
A
No. The lingual plate is often thin, and completely sectioning may perforate the plate and injure the lingual nerve.
17
Q
How is bleeding from pulsating nutrient blood vessels controlled following surgery on alveolar bone.
A
- Burnish bone
- Crush bone with rongeurs
- Bone wax
18
Q
What are some common causes of postoperative bleeding following dental extractions?
A
- Failure to suture
- Failure to remove all granulation tissue
- Rebound blood vessel dilation following use of LA with a vasoconstrictor
- Torn tissue
- Torn surgical flaps
19
Q
Why is a mucoperiosteal flap designed to be broad at the base?
A
To ensure adequate blood supply to the flap margin
20
Q
What are the two basic flaps used in dentoalveolar surgery?
A
- full thickness
2. split thickness
21
Q
What are the two basic types of full thickness flaps?
A
- envelope
2. envelope with a releasing component
22
Q
Where are releasing incisions contraindicated?
A
- palate
- through muscle attachments
- lingual surface of the mandible
- in the region of the mental foramen
- Canine eminence
23
Q
What is Gelfoam and how does it aid in homeostasis?
A
Absorbable gelatin sponge. Gelatin sponges form a matrix or scaffold upon which the clot can form. It is not incorporated into the clot. Does not delay healing
24
Q
What is Surgicel and how does it aid in homeostasis?
A
Oxidized regenerated cellulose. Like Gelfoam, it forms a matrix or scaffold upon which a clot can form. It is incorporated into the clot and can delay healing (unlike Gelfoam); however, it is a better hemostatic agent
25
What is Avitene and how does it aid in homeostasis?
Microfibrillar collagen. Unlike Gelfoam or Surgicel, Avitene produces an actual collagen matrix which then attracts platelets and triggers thrombus formation. It thus assumes an active rather than passive role in homeostasis.
26
Why are conventional dental handpieces that expel forced air contraindicated when performing dentoalveolar surgery?
Can cause tissue emphysema or air embolism. An air embolism can be fatal.
27
What are the cardinal signs and symptoms of localized osteitis (dry socket)?
1. throbbing pain (often radiating)
2. bad taste
3. fetid/foul odor
4. Poorly healing extraction site w/clot loss and exposure of bone.
28
What causes a dry socket?
Etiology is not fully clear but is thought to be increased fibrinolytic activity causing lysis of the clot. Thought to have a bacterial component but known risk factors include:
1. smoking
2. premature, forceful mouth rinses
3. trauma
4. oral contraceptives
5. female predilection
29
Why should flaps be repositioned and sutured over sound bone?
Unsupported flaps can collapse into bony defects causing tension on the sutures; the sutures subsequently will pull through the tissue, allowing the suture line to open and the wound to dehisce.
30
What percentage of dentoalveolar injuries include the primary maxillary central incisor?
70%
31
How do you treat an avulsed primary tooth?
No treatment; replantation is not indicated in deciduous teeth.
32
How is an extruded primary tooth treated?
If grossly mobile or interfering with opposing tooth => extraction
If minimal mobility without interference =>repositioning (without fixation) or observation
33
What is the incidence of pulp necrosis after intrusion injuries of teeth?
Depends on apex. If closed ~95%, if open and immature then 65%.
34
How long should dentoalveolar fractures be splinted?
4-6 weeks
35
Which media can be used to transport avulsed teeth?
1. Saliva
2. Milk
3. hanks balanced salt solution
36
What will transporting an avulsed tooth in water do?
Water is a hypotonic solution and can cause PDL cell death becuase it enters cells down the osmotic gradient and cell lysis
37
What is the general time frame that an avulsed tooth is attempted to be replanted?
Greater than 60 minutes has very poor prognosis and replantation isn't recommended
38
How long should an avulsed or extruded tooth be splinted for?
2-3 weeks
39
What are the significant radiographic predictions of a close relationship between IAN canal and an impacted third molar?
1. Darkening of root
2. Deflected roots at region of canal
3. Interruption of canal outlines
4. Diversion/deflection of canal from it's normal course
5. Narrowing of root
6. Narrowing of canal outlines
40
What are the most important signs that may increase potential nerve injury with extraction of impacted mandibular third molars?
1. Darkening of root
2. Interruption of canal border outlines
3. Diversion of canal
41
How do you manage displaced root tip(s) into the submandibular space?
Immediate manual lateral and upward pressure should be applied to the lingual aspect of the floor of the mouth in an attempt to force the root back in the socket. If not visible, a FTMP flap should be reflected on the lingual aspect until the root tip is identified and retrieved.
42
How do you manage displaced root tip(s) into the submandibular space if root is not visualized due to location or bleeding?
Usually a secondary procedure when fibrosis occurs and stabilizes the root in a firm position (usually 4-6 weeks). A course of abx is customary.
43
How do you manage displaced root tip(s) into the IAN canal?
PA or cone beam CT to verify location because the root tip may also be dislodged into the large marrow space or beneath the buccal mucosa. If root is visualized, careful removal is indicated. If not visualized, delayed removal is recommended as necessary.
44
When is delayed removal of a displaced root tip(s) into the IAN canal?
Indicated when there is persistent infection or nerve paresthesia. If fragment is small (>4mm) and asymptomatic without paresthesia then leaving alone is viable.
45
How is a root that is displaced in the maxillary sinus managed?
1. Sit pt upright to prevent posterior displacement
2. Imaging (CT or radiograph to determine location/size)
3. Local measures:
- have pt blow nose with nostrils closed to force root through perforation
- use a fine tip suction to bring root back into defect
- antral lavage with saline in effort to flush root through the defect
46
How is a root that is displaced in the maxillary sinus managed after failed local measures?
Direct entry into the maxillary sinus via Caldwell-luck approach. Post operative management included: sutures over socket, sinus precautions, abx regimen and nasal spray
47
How are oro-antral communications managed?
For openings <2mm: no surgical tx necessary with adequate hemostasis. Sinus precautions
For openings 2-6mm: conservative treatment including sutures over socket, sinus precautions
For openings >6mm: primary closures vial buccal or palatal flap placement. Likely will require additional procedure (buccal fat pad advancement)
48
How is a tooth that is displaced into the infratemporal fossa managed?
If appropriate access and light, a single cautious effort to retrieve the tooth with a hemostat can be made, if unsuccessful or if the root is not visualized, the incision should be closed, pt informed and prophylactic abx should be prescribed.
A secondary procedure in 4-6 weeks with CBCT. A spinal needle can be used to locate the tooth. Careful dissection of along the needle until tooth is visualized and removed. Some surgeons prefer to remove in the OR.
49
When a tooth is displaced into the infratemporal fossa, where is it usually in relation to the lateral pterygoid plate and the lateral pterygoid muscle.
Usually displaced through the periosteum and located lateral to the lateral pterygoid plate and inferior to the lateral pterygoid muscle
50
Can a displaced tooth in the infratemporal fossa be left alone?
Yes. If no functional problems exist after displacement. Proper documentation is essential.
51
How is postoperative or secondary bleeding for ext sites managed?
1. direct pressure
2. anesthetic with vasoconstrictor
3. removal of sutures and curettage of clot (possibly liver clot)
4. local packing: absorbable gelatin, oxidized cellulose, microfibrillar collagen
5. TXA (transexamic acid) soaked packing
6. further work up
52
What does transexamic acid bind to?
Plasminogen. It disrupts the t-PA, plasminogen complex that binds to fibrin and causes fibrinolysis
53
What is the difference between incisional and excisional biopsy?
Incisional biopsy: removes only a representative portion or portions of a lesion with a representation of adjacent normal tissue
Excisional biopsy: removal of entire lesion with 2mm borders of normal marginal tissue. Used for lesions <1cm in size
54
What are the indication for performing a partial odontectomy (coronectomy)?
Risk of IAN injury or jaw fracture
55
When a biopsy is being performed, why is it necessary to incision parallel to the long axis of any muscle fibers beneath the lesion?
If appropriate, incisions that are oriented parallel to the line of muscle tension will minimize scaring and wound dehiscence.
56
What are the requirements for a coronectomy tooth selection?
1. Asymptomatic tooth
2. No associated periapical pathology
3. Must not interfere with future restorative procedures or orthodontic treatment
57
What are the requirements for a coronectomy retained root (after sectioned crown)
1. no root mobility
2. no residual enamel
3. 3mm below alveolar ridge
58
What is the Pell and Gregory impacted mandibular third molar classification?
Class I: sufficient space between ramus and 2nd molar (likely 3rd molar can erupt)
Class II: half the 3rd molar is covered by the ramus
Class III: the entire 3rd molar is covered by the ramus
Class A: occlusal surface of 2nd and 3rd molars are about same level
Class B: occlusal surface of 3rd molar is between the occlusal surface and CEJ of the 2nd molar
Class C: occlusal surface of the 3rd molar is below the CEJ of the 2nd molar
59
What teeth are most commonly impacted?
1. Mandibular 3rd molars
2. Maxillary 3rd molars
3. Maxillary canines
4. Mandibular premolars
5. Mandibular canines
60
What is LMWH?
Standard unfractionated heparin is formed from a heterogeneous combination of sulfated mucopolysaccharides. Its anticoagulation activity is unpredictable, so it must be monitored carefully with partial thromboplastin time testing.
LMWH (fractionated heparin) is formed from depolymerization of heparin into lower molecular weight forms. It has increased bioavialaibility (compared to UFH), it can be given as a fixed dose without monitoring.
61
How is LMWH used in OMFS?
Can be used for high risk patients who cannot discontinue or reduce anticoagulation therapy. Warfarin is held for INR to normalize, LMWH given to maintain anticoagulation therapy. LMWH is held AM of procedure and resumed in the evening day of procedure. Warfarin can be resumed POD 1. LMWH used until INR is therapeutic
62
Should patients discontinue aspirin or clopidogrel for routine dentoalveolar surgery?
While each patient is an individual basis, it is generally not indicated to stop aspirin or plavix for dentoalveolar surgery including multiple extractions.
Risks including, recurrent MI or stroke outweigh risk of post operative bleeding in most cases.
For more extensive procedures consider LMWH
63
What are NOACs or DOACs? Is there a lab used to monitor?
adjusted for patients undergoing surgery?
Direct factor Xa: rivaroxaban (xarelto) or apixaban (eliquis)
Direct thrombin inhibitor: dabigatran (pradaxa)
Neither will change INR nor PT levels.
64
How are DOACs adjusted for patient undergoing surgery?
The half life of DOACs is relatively short and they can be held 1-2 days prior to surgery.
As a general rule, for medications given BID (shorter half life), hold 1 day prior to surgery. For medications given QD (longer half life) hold for 2 days prior to surgery
65
How does the blood supply of the edentulous mandible differ from that of the dentate mandible?
As edentulous bone loss progresses, the blood supply changes from CENTRIFUGALLY to CENTRIPETALLY. The IA artery becomes smaller and the periosteum becomes the primary blood supply. Elevation of the periosteum on mandibles with severe bone loss can compromise blood supply.
66
Does alveolar bone resorb more quickly in the mandible or maxilla?
Maxilla usually has more rapid and severe edentulous bone loss. It has been posited that this is 2/2 no muscular attachment to the maxilla and lack of functional stimulus
67
What skeletal relationships result from edentulous bone loss
A pseudo class III. Most edentulous bone loss in the maxilla takes place on the lateral and inferior aspects of the ridge. So the maxilla resorbs posteriorly and superiorly. As the height and width of the mandibular ridge deteriorates, the crest moves further anteriorly. As vertical dimension collapses, the mandible auto-rotates forward as well.
68
What is combination syndrome?
Excessive resorption of the edentulous alveolar ridge of the anterior maxilla caused by the forces generated by opposition of the natural mandibular anterior teeth
69
How can abnormal frenum be excised?
z-plasty, v-y advancement, diamond excision
70
```
What is the average size of the maxillary sinus?
Volume?
Width?
Height?
Depth?
```
V: 14.75 cc with a range of 9.5-20 cc
W: 2.5 cm
H: 3.75 cm
D: 3 cm
71
How should tears of the sinus membrane be managed during a sinus lift?
Tears over the corticocancellous grafts will heal; particulate grafts may be lost if they migrate through the perforation. Small tears may not pose a problem because the membrane folds over itself as it is lifted. Larger tears should be patched with a material such as surgicel or collatape
72
How much native bone is required for immediate placement of implants with a sinus lift?
A minimum of 4mm
73
What is the proper size of the window for a sinus lift?
The window for a sinus lift be approximately 20mm in an AP direction and 10-15mm in height
74
What is the desired thickness of a split-thickness skin graft?
Vary in thickness but all STSG is composed of epidermis layer and part of the dermis. Usually ranges between 0.010 and 0.025 inches
75
Which types of skin grafts contract the most? The least?
Contraction is related to graft thickness. Contraction is greatest in thin then intermediate then thick; there is almost no contraction in a full thickness graft.
76
What is the difference between primary contraction and secondary contraction? When do they occur?
Primary contraction is caused by elastic fibers as soon as it is harvested. This is overcome by suturing the graft in place
Secondary contraction begins about POD 10 and can last for ~6 months
77
What is plasmic imbibition?
The process by which a skin graft absorbs plasma-like fluid from the underlying recipient bed. It is absorbed into the capillary network by capillary action. This process is initial survival of the skin graft and continues for ~48 hours.
78
Does grafted skin resemble the donor or recipient site?
Grafted skin maintains most of its original characteristics.
However, sensation and sweating more closely resemble the recipient site
79
What are two characteristics that a skin graft resembles the recipient site more than the donor site?
Sensation and sweating
80
What are the goals of a vestibuloplasty?
Increase the depth of the sulcus/vestibule which helps control lateral displacement of the denture. The skin graft provides additional attached tissue.
81
What are the possible graft donor sites for vestibuloplasty?
Skin, palatal mucosa, buccal mucosa
82
What are the advantages of using a stent to secure a graft in place for vestibuloplasty?
1. Adapt the skin with accuracy to any contour and undercuts in the lingual area.
2. Graft stabilization
3. Graft protection from trauma
83
What is the lip-switch procedure?
A transpositional flap vestibuloplasty. An incision is made in the labial mucosa. A thin mucosal flap is elevate continuing into a supra-periosteal flap up to the crest of the ridge. The mucosal flap is then sutures to the depth of the vestibule covering the anterior aspect of the mandible. The denuded tissue on the inner surface of the lip heals via secondary intention
84
What is the minimum distance from the inferior border that the mentalis must remain attached, during vestibuloplasty, to prevent a sagging chin?
A minimum of 10 mm of muscular tissue must remain attached
85
What is a submucous vestibuloplasty?
Used for improvement of the maxillary vestibule when there is minimal ridge absorption but mucosal and muscle attachments exist near the crest of the ridge.
Through a midline incision, submucosal and supra-periosteal dissections are made and tissue between the two tunnels are cut. A splint is relined and secured in place for 7-10 days
86
How is a floor of mouth lowering performed?
An incision is made on the lingual aspect of the alveolar ridge. A supra-periosteal dissection is carried. The mylohyoid and genioglossus are sharply dissected from their insertions. No more than half the superior aspect of the genioglossus muscle should be released. The mucosal margins are sutured to their new depth, with sutures passed externally or in a circummandibular fashion
