Dentoalveolar

Question 1

What are Infratemporal fossa boundaries?

Answer 1

• Anteriorly: posterior surface of the maxilla
• Posteriorly: styloid process and part of mastoid process
• Medially: lateral pterygoid plate
• Laterally: zygomatic arch
• Superiorly: greater wing of sphenoid bone
• Inferiorly: maxilla and palatine bone

Question 2

• What are the anatomical structures in Infratemporal fossa?

Answer 2

• Medial and lateral pterygoid muscles
• Maxillary artery
• Middle meningeal artery
• Deep temporal artery
• Pterygoid plexus
• Trigeminal nerve
• Corda tympani
• Otic ganglion
• Auriculotemporal nerve

Question 3

Anatomy of the buccal fat pad

Answer 3

• The BFP is located within the masticatory space.
• Weight 9.7 g
• 5 × 4 cm defects (medium-sized)
• The BFP is also described as having 3 lobes.
• Anterior
• Intermediate
• Posterior lobe.
  - Posterior lobe has main body and 4 extensions.
  - Buccal
  - Pterygoid
  - Pterygopalatine
  - Temporal.
• The main body and the buccal extension compose 50% to 70% of the BFP total weight.

Vascularization of the buccal fat pad
- Derived from 3 branches of the maxillary artery:
- Deep temporal, buccal, and superior posterior alveolar arteries.
- Transverse facial artery

• The venous drainage is provided by the facial vein. The BFP flap is therefore categorized as an axial flap.

Function: gliding function between the muscles of mastication during function. This is termed a syssarcosis action.

Question 4

Eugenol

Answer 4

Eugenol is a natural compound found in clove oil, and it is known for its analgesic (pain-relieving) and antiseptic properties.

Question 5

Hemostatic agents

Answer 5

• Floseal – gelatin matrix & thrombin
• Thrombin – serine protease, activates factor IIA, converting to fibrin
• Gelfoam – purified porcine, matrix for blood clot
• Avitene – microfibrillar collagen, aggregates platelets into fibrils
• HemCon (chitosan) – shellfish, acts as scaffold
• Surgicel – oxidized methylcellulose – binds platelets, precipitate fibrin. Negative PH bacteriostatic (** don’t place over nerve as acidic)
• Collaplug – cross linked collagen promotes plt aggregation
• Amicar – stabilizes clot by inhibits plasmin
• TXA rinse – antifibrinolytic, inhibits conversion into plasmin

Question 6

Describe your Neurosensory testing?

Answer 6

• I start by mapping the area of altered sensation with a 27-gauge needle, moving from normal to abnormal areas, and marking it with a skin pen.
• I divide the lower lip and chin based upon the midline and labiomental fold into four quadrants and begin testing on the normal side to establish a baseline, then compare it to the affected side.
• First, I test Level A (A-alpha, A-beta fibers large myelinated) for two-point discrimination and brush stroke direction, performing ten attempts and recording the results.
• Next, I test Level B (A-beta fibers mechanoreception) for light touch using a cotton applicator; normal is feeling the touch without pressure, while needing pressure indicates an increased threshold.
• Finally, I test Level C (C-fibers unmyelinated nociception ) for thermal sensation with ethyl chloride and for pinprick sensation by asking if the patient feels sharp or dull.

Question 7

Define Wallerian degeneration?

Answer 7

• Distal degeneration of the axon and its myelin sheath after injury due to lack of nutrient supply.

Question 8

Seddon and Sunderland Classification of Nerve Injury

Answer 8

Seddon: classified severity of nerve motor nerve injuries based on histology

1. Neuropraxia
2. Axonotmesis
3. Neurotmesis

Sunderland: Sunderland’s classification basis the injury on level of anatomic injury
1-6
Neuropraxia&raquo_space; 1
Axonotmesis&raquo_space; 2,3,4
Neurotmesis&raquo_space; 5
Neuroma&raquo_space; 6

Question 9

Seddon and Sunderland Classification of Nerve Injury

Answer 9

1. Neuropraxia (Sunderland 1)
   Description: Temporary disturbance in nerve conduction, axon continuity preserved.
   Cause: Mild to severe compression or traction.
   Treatment: No treatment needed.
   Outcome: Spontaneous recovery within hours to 3 months.
2. Axonotmesis (Sunderland 2)
   Description: Loss of axonal continuity, endoneurium and perineurium intact.
   Cause: Forceful compression or traction (>25g), Wallerian degeneration distal to injury.
   Treatment: Surgery only if foreign body present.
   Outcome: Possible spontaneous recovery in 2–4 months.
3. Axonotmesis (Sunderland 3)
   Description: Endoneurium and axonal loss, perineurium intact.
   Cause: Severe crush, puncture, or chemical injury.
   Treatment: Microsurgery if no improvement in 3–4 months.
   Outcome: Recovery takes 3–4 months, but may be incomplete.
4. Axonotmesis (Sunderland 4)
   Description: Loss of endoneurium and perineurium, epineurium intact.
   Cause: Extreme crush, thermal, or chemical injury.
   Treatment: Microsurgery if no improvement in 3–4 months.
   Outcome: Recovery takes 3–4 months, unlikely to be complete.
5. Neurotmesis (Sunderland 5)
   Description: Complete nerve transection with or without neuroma formation.
   Treatment: Requires microsurgery.
   Outcome: No spontaneous recovery.
6. Neuroma (Sunderland 6)
   Description: Neuroma in continuity.
   Treatment: Requires microsurgery.
   Outcome: No spontaneous recovery.

Question 10

Nerve injuries facts

Answer 10

• Nerve recovery progresses slowly at 1 mm/ day or 1 in/month.
• The rate of permanent injury to the lingual nerve from third molar surgery 0.6%
• 2.8 mm below the crest and
  2.5 mm medial
• 21.0%, the lingual nerve is at or above the crest of the bone.
• 22% reported at lingual plate of bone.
• IAN injury is 1% after thirds
• Generally the nerve is located buccal and apical to impacted third molars.
• The incidence of persistent nerve impairment of the IAN 1 year after BSSO surgery is reported to be 33%
• Normal Two-Point Discrimination Distances:
  Tongue (Tip) 3.0 mm- 4.5 mm
  L Lip (Skin) 5.0 mm- 9.0 mm
  L Lip (Mucosa) 3.5 mm- 6.5 mm

IAN
18–21 fascicles
2.4 mm

Lingual
15–18 Fascicles
3.2 mm

Prognosis
* Overall success rate of around 50%.
* 70% of patients with painful neuromas are
helped regardless of surgical technique.

Question 11

Pain Terms

Answer 11

• Allodynia – pain from a non-painful stimulus.
• Anesthesia – absence of any sensation.
• Anesthesia dolorosa –
  pain felt in an area, which is completely anesthetic to touch.
• Hyperalgesia – increased response to stimulation that is normally painful.
• Hyperpathia – prolonged pain following a repetitive noxious stimulus that lingers beyond
  expected duration.
• Hypoalgesia – diminished response to a normally painful stimulus.
• Hypoesthesia – decreased sensitivity to stimulation.

Paresthesia – abnormal sensation, whether spontaneous or evoked and is not unpleasant.

Tinel sign – tingling or “pins and needles” sensation elicited upon tapping on the distribution of the nerve.

changes in taste parageusia

Question 12

Modified Medical Research Council Scale

Answer 12

This scale assesses sensory recovery in nerve injuries:

S0: No sensation.

S1: Deep cutaneous pain

S2: Some superficial pain and touch sensation.

S2+: Superficial pain and touch with hyperesthesia.

S3: Superficial pain and touch without hyperesthesia; two-point discrimination >15 mm (useful sensory function).

S3+: Same as S3 with better stimulus localization and two-point discrimination of 7–15 mm.

S4: Complete sensory recovery with two-point discrimination of 2–6 mm.

Question 13

Indications for nerve repair

Answer 13

Indications for nerve repair:
– Observed nerve transection
– Complete postoperative anesthesia
– Persistent anesthesia >1 month without improvement
– Presence or development of dysesthesia
– Paresthesia without improvement >3 months
– Foreign body in canal
– Patient unable to tolerate hypoesthesia

Question 14

Nerve repair surgeries:

Answer 14

• External neurolysis (decompression):
  exposing nerve from soft tissue bed without disruption of epineurium.
• Neuroma excision:
  Resect 3 mm proximal
  and distal. Examine fascicles under magnification for opacity and architecture and check for scarification by pressing on the nerve with micro forceps. Adequacy may also be tested by frozen sections 1 mm cross-section biopsies.

Direct neurorrhaphy:
4–6 circumferential epineural sutures with 7.0–9.0 nylon sutures.
Lingual nerve gap of 1 cm and IAN gap of 5 mm possible for direct repair (without need for interpositional graft).
Minimal tension of 25 g or less to prevent axonal gapping and prevent axon downgrowth to the distal nerve.

Nerve grafting – requires 25% longer graft than defect due to shrinkage.

Processed allograft AxoGen Avance® is a non- immunogenic alternative that provides a
scaffold for nerve tissue to grow.

Entubulation – best for gaps <10 mm. Polyglycolic acid conduits start to break down in 3 months and are resorbed by 8 months.

Question 15

Define Coronectomy

Answer 15

Partial tooth removal leaving roots behind to prevent IAN damage.

Question 16

Contradictions of Coronectomy

Answer 16

1. Horizontal impaction
2. Inability to access or removal all enamel layer.
3. Infection of roots.
4. Plan for distalization of second molar.
5. Mobility of roots.

Question 17

Surgical technique of Coronectomy

Answer 17

• Removal of all enamel and root remnant 3 mm below the alveolar crestal bone.
• Primary closure
• Pano post op baseline
• Roots migrate about 30% of the time and can be appreciated in first 3 months appears as radiolucency below the roots with coronal migration.

Question 18

Define Impacted tooth

Answer 18

Tooth that cannot or will not erupt into its normal functioning position.

Question 19

Impacted teeth Facts

Answer 19

• Impacted third molars ~25%
• Most common missing teeth:
• Third molars followed by second premolars and maxillary lateral incisors.
• Most common impacted teeth:
• Third molars
• Maxillary canines
• Mandibular premolars
• Maxillary premolars
• Second molars.

Question 20

Development of Third Molars

Answer 20

• Age 6–9 – follicles become visible on radiography.
• Age 9 – molar germ visible.
• Age 11– cusp mineralization
• Age 14 – crown formation is done.
• Age 16 – 50% of root formed.
• Age 18 – root completely formed with an open apex.
• Age 24 – 95% of molars in final tooth position.
• Age 25 – little change in tooth positioning

Question 21

Theories of Tooth Impaction

Answer 21

1. Differential growth rate of mesial and distal roots
2. Arch length
3. Ectopic position
4. Late mineralization
5. Attrition: softer diet

Question 22

Classification for Mandibular Third Molars

Answer 22

• Pell and Gregory
  Classes A–C based on relation to second molar occlusal plane.
  Classes 1–3 based on relation to the anterior border of ascending ramus.
  A
  B
  C
  1. 2. 3.
• Winter’s Classification:
• Most commonly used
• Angle between the occlusal plane and the longitudinal axis of the third molar.
• <0° = inverted, rare. As is buccoangular and linguoangular.
• 0° and 30° horizontal impactions, ~10% of impactions.
• 31° and 60° mesioangular impactions, ~45% of impactions.
• 61° and 90° vertical impactions, ~40% of impactions.
• > 90° distoangular impactions, ~5%.

Question 23

Indication for Third Molar Removal

Answer 23

Pericoronitis
Orthodontic Needs or orthog
Pericoronal Pathology >3 mm
Caries
Fractures in contact sport
Unexplained pain 5%
Overlying Prosthesis
Periodontal Disease >5mm pocket

Question 24

Rood’s Criteria

Answer 24

Rood and Shehab, aka Rood’s Criteria, describing intimacy of Inferior Alveolar Nerve (IAN) with roots of mandibular third molar.
1. Darkening of root
2. Deflection of root
3. Narrowing of root
4. Bifid root apex
5. Diversion of canal
6. Narrowing of canal
7. Interruption in white line of canal

Question 25

What are the statistically significant criteria that can be seen on a panorex that relate to post operative paresthesia

Answer 25

Darkening of the root
Diversion of the canal
Interruption of the canal

Question 26

What irrigation should be used to clean the socket?

Answer 26

Saline irrigation is used to cleanse the socket.
(Distilled water is hypotonic and leads to cell death).

Question 27

Alveolar Osteitis

Answer 27

Alveolar Osteitis:
inflammation of the alveolar bone d/t increased fibrinolytic activity leading to break down of clot.

Incidence: 1% and 30%

Commonly seen at days 3–7 after extraction.

Symptoms include referred pain to ear, eye, and temple region, foul odor, extreme tenderness to palpation.

Risk factors: tobacco smoke, increasing age, pericoronitis, birth control, female gender, inexperience of surgeon leading to traumatic extraction, inadequate irrigation, and increased medical comorbidities.

Some evidence show that chlorhexidine can reduce incidence.

Treatment is commonly with iodoform gauze or gel foam coated with eugenol that acts by inhibiting neural transmission.
should not be used when IAN exposed due to neurotoxic effects of eugenol. If concerned for IAN exposure, consider the use of topical lidocaine in place of eugenol.

Question 28

Displacement of Root into Sinus

Answer 28

Most commonly the palatal root of maxillary first molar; take PA to verify position.

Several local measures should be made:
(1) suctioning into sinus
(2) pack sinus with xeroform gauze and pull in one stroke (often root will attach to gauze), (3) perform antral lavage
(4) have patient block opposite nostril and blow nose to force into socket
(5) enlarge opening and explore.

If attempts fail, fragments 3 mm or less that are non-infected may be left in place and patient be informed.
Roots >3mm or those that presented with an infection/peri-apical pathology should be removed via a Caldwell- Luc approach is indicated.

Question 29

Oral Antral Communications (OAC)

Answer 29

Most small OACs will heal by themselves.

Openings of 3–6 mm can be managed by placing gel foam and closing with a figure-of-eight suture technique.

OAC >6 mm may require tension- free primary closure, excision of the fistulous tract, and inversion into the sinus. Consider treating larger OACs with a buccal fat pad closure, buccal finger flap, or tongue flap.

Sinus precautions for 2 weeks (decongestants, antibiotics that cover sinus flora, no heavy nose blowing, saline nasal spray)

Question 30

Displacement into Infratemporal Space

Answer 30

Likely due to lack of retractor protection with excessive force and poor visualization.

Position most commonly lateral and inferior to pterygoid plate.

May attempt to manipulate the tooth back manually into incision by placing finger high into vestibule near the plates and applying manual pressure.

If good access and lighting, may attempt to extend incision and retrieve with hemostat.

If primary efforts fail, allow 4–6 weeks to allow for fibrosis. Obtain a CT scan and use a spinal needle to identify, dissect along needle length.

Needle- guided fluoroscopy may also be used. It also has been reported to perform a hemicoronal incision to gain access to infratemporal space.

If no functional deficit and asymptomatic, may elect to leave in place.

Question 31

Aspiration of Foreign Object –

Answer 31

• Stope the procedure
• Suction the oral cavity
• Pack the surgical site
• May attempt Heimlich maneuver while patient is in beach chair position.
• If under anesthesia, deepen the level of sedation and attempt visualization and removal with Magill forceps.
• Cord pressure may help move objects caudally past the cords.
• If no respiratory distress, likely ingested, obtain abdominal and chest radiography to rule out.
• Always presume aspiration and place patient on right side in Trendelenburg.
• Continue monitoring and watch out for signs of hypoxia and respiratory distress. Refer to emergency room for removal.

Question 32

What syndromes may be associated with multiple impacted teeth?

Answer 32

Gardner’s Syndrome
Cleidocranial Dysplasia

both autosomal dominant inheritances.

Question 33

How would you determine the position of impacted teeth

Answer 33

SLOB rule (Same Lingual Opposite Buccal): taking consecutive periapicals of the region and shifting the collimator one direction of the other and noting whether the object in question moves the same direction or opposite to the collimator movement.

Question 34

What would be your anesthesia plan?

Answer 34

After assessing the patient’s level of anxiety, medical status, complexity and expected duration of the surgical procedures, I would offer the patient an office-based sedation

Question 35

What is Bio-Oss?

Answer 35

A xenograft (bovine). Particulate hydroxyappetite, very similar in physical characteristics to natural bone mineral. Processed to contain no proteins or organic material. It serves as an osteoconductive matrix only, there is no osteoinductive potential from the Bio-Oss alone.

Question 36

During your initial surgery tooth #1 disappears. Where could it have gone?

Answer 36

During your initial surgery tooth #1 disappears. Where could it have gone?

It may be displaced into the maxillary sinus, under your flap, or into the infratemporal fossa.

(27) What could have caused this?
Excessive forces, inappropriately directed forces, poor access and visualization, small tooth size and proximity to sinus or thin buccal plate.

Question 37

A patient calls your office the next day with profound numbness of the right lower lip and chin. What actions would you take?

Answer 37

Examine the patient that day and document a thorough neurosensory examination in the chart.

Take a radiograph (Panorex) to rule out any tooth root structure impinging on the IAN.

Start the patient on corticosteroids. I use Medrol dose-pack (methylprednisolone) which comes in a convenient package with 21 4mg tablets and instructions for use. Methylprednisolone is a corticosteroid used primarily as an anti-inflammatory or immunosuppressant agent.
it decreases inflammation by suppression of migration of PMN’s and reversal of increased capillary permeability. Minimizing the inflammatory response around an injured nerve may minimize the severity of injury to the nerve.

It is also important to discuss the diagnosis of nerve injury with the patient and relate the clinical findings of the neurosensory exam.

A combination of B complex vitamins and Vitamin E can be beneficial for nerve injuries, as B vitamins are crucial for nerve health and function, while Vitamin E acts as an antioxidant to protect nerves from further damage;

Question 38

What do you know about Gardner’s Syndrome?

Answer 38

Autosomal dominant disorder characterized by GI adenomatous polyps, osteomas, fibrous tumors, skin cysts, and occasionally impacted teeth, supernumerary teeth, or odontomas.

Question 39

What is the defective gene in Gardner’s Syndrome and on which chromosome is it found?

Answer 39

Adenomatous polyposis coli gene found on the long arm of chromosome 5

Question 40

What is the greatest medical risk for patients with Gardner’s syndrome and how is this prevented or treated?

Answer 40

Adenomatous polyps of the GI tract which have a virtually 100% chance of transforming to adenocarcinoma unless prophylactic colectomy is performed

Question 41

Your patient who has undergone a sinus floor elevation using the Summer’s technique calls in 2 days after the procedure complaining of dealing with dizzy spells every morning. What
do you want to know?

Answer 41

Inquire about constitutional symptoms (fever, chills, nausea, or cold-/flu-like symptoms), ear ache, or tinnitus. Has she ever experienced this before and if so has she ever been worked up for these symptoms? (rule in/out idiopathic endolymphatic hydrops?) Are the symptoms brought upon when she first wakes up from bed form a supine to upright position? How long do they last? Does she experience any nystagmus with these dizzy spells?

Question 42

This has never happened before. She has no flu-like symptoms. She usually experiences a self-limiting dizzy spell from about 30 seconds when she gets up from bed. Her husband notes her eyes tend to shake when this happens. What next?

Answer 42

Benign paroxysmal positional vertigo is a known complication of sinus floor elevation and would be my working diagnosis. I would attempt to control her symptoms with antihistamines such as meclizine 50 mg PO BID.

I would reassure her that this likely would self-correct. If symp- toms continue for a prolonged period, I would refer her to an ENT colleague for workup and canalith repositioning procedure (Epley maneuver).

Question 43

What are the causes of canine impaction:

Answer 43

• Genetic theory
• Guidance theory: Lack of normal contact between the root of lateral incisor and erupted canine

Question 44

Materials use during exposed and bond

Answer 44

Phosphoric acid 37% for 30 second

Glass ionomer:
- Release florid
- Work in wet environment
- Minimal dimensional change

Resin cement:
- High retention
- High adhesive quality
- Low solubility

Question 45

what percentage of canines are impacted?

Answer 45

Max ~2%, mand 0.4%

Question 46

What are some orthodontic considerations prior to performing an expose and bond for a maxillary canine?

Answer 46

• There should be adequate spacing for eruption of the maxillary canine
  Average mesial-distal dimension of maxillary canine is 7.5 mm
• The more perpendicular the canine is to the lateral incisor, the more likely it should be extracted as opposed to expose and bond
• Orthodontic hardware should be placed prior to procedure

Question 47

What are treatment options for expose and bond?

Answer 47

• Interceptive: take out the primary canine before age 11
• Apically positioned flap: Labial impactions without mesial/distal displacement, don’t use for high impactions, use if less than 3 mm of keratinized gingiva is expected after an open window
  technique.
• Open exposure (window): crown is uncovered and left exposed
• Closed: used when you can’t do an apical flap or the tooth is far from the alveolar ridge