TMJ

Question 1

“Locked Jaw Syndrome in Dogs and Cats: 37 Cases (1998-2005)” by Matthieu Gatineau, Alexander O. El-Warrak, Sandra Manfra Marretta, Kamiya D, Maxime Moreau. JVD 2008.

According to this study what where the most common causes? (Name four)

Answer 1

cases that couldn’t open/close mouth are included in locked jaw syndrome

Diagnoses:
* 10 dogs had fractures (32%)
* 7 dogs had MMM (23%)
* 4 dogs had trigeminal nerve paralysis (13%)
* 4 had OSA (13%)

In results sort of split locked jaw syndrome into “TMJ ankylosis and trismus”

They defined ankylosis as intra or extraarticular lesions that prevented opening of the mouth – included fractures of zygomatic, coronoid, neoplasia etc.

They defined trismus as a muscular lesion preventing closure – maybe.

Most common cause of locked jaw syndrome was TMJ ankylosis in 54% of dogs. 90% of these were false ankylosis and only 2 (10%) were true intraarticular ankylosis.

Also looked at ‘trismus’ which included neuropathies and MMM.

Most common cause of trismus was MMM (41% of trismus categories).

The numbers in this paper are hard to interpret – not outlined neatly how cases were assigned to various categories

Question 2

“Maxillofacial Injuries and Diseases That Cause an Open Mouth in Cats”. Marika E. Constantaras. JVD 2014.

what are the DDs?

Answer 2

• TMJ luxation
• TMJ fracture
• caudal mandibular fracture
• impingement of the coronoid process of the mandible on the zygomatic arch
• mechanical obstruction
• Neuropathy

Question 3

JVD 2024 Renner et al TMJ Gape Angles in Normal and Painful Domestic Felines

What was the overall mean feline TMJ gape angle?

Answer 3

Significant increase (P < 0.001) in gape angle under anesthesia
* 45.3° (±8.6°) in conscious cats
* 50.8° (±6.2°) in anesthetized cats

no significant difference between painful and non-painful feline gape angles during conscious or anesthetized evaluations

Question 4

JVD 2024 Renner et al TMJ Gape Angles in Normal and Painful Domestic Felines

Was there a sig dif in gape angles between painful and non-painful cats? Age infuence?

Answer 4

no
no

Question 5

JVD 2024 Renner et al TMJ Gape Angles in Normal and Painful Domestic Felines

How did anesthesia affect the gape angle?

Answer 5

Non-painful cats: Increase of 4.3°
Painful cats: Increase of 6.4°

mean feline gape angle was 45.3° in conscious cats, 50.8° in anesthetized cats (significant difference).

no significant difference between painful and non-painful feline gape angles during conscious or anesthetized evaluations (the feline gape angle is not a useful indicator of oral pain).

Question 6

JVD 2024. Paran et al. “Morphological Assessment of the TMJ in Asymptomatic Barchycephalic Dogs Using CT”.

1. What TMJ variations were observed among the breeds?
2. Which breeds had the highest prevalence of severe TMJ dysplasia?
3. Did any breeds show mostly normal TMJ morhphology?

Answer 6

1. There was a wide spectrum of variations, ranging from a rounded, concave TMJ with a long retroarticular process to a flattened TMJ with an absent retroarticular process.
2. severe TMJ dysplasia (grades B3 and C): in 69.2% of Cavalier King Charles Spaniels (CKCS), 53.8% of French Bulldogs.
3. Boxers, English Bulldogs, Staffordshire Bull Terriers (SBTs), and Lhasa Apsos were more likely to have normal TMJs (grade A or mild B1 dysplasia).

Question 7

JVD 2024. Paran et al. “Morphological Assessment of the TMJ in Asymptomatic Barchycephalic Dogs Using CT”.

1. Were TMJ abnormalities always bilateral?
2. What was the relationship between TMJ grade and mandibular shape?

Answer 7

1. No.
   33/153 (21.5%) dogs had different TMJ grades on the left and right sides, though these differences were usually between adjacent grades (A vs B1, B2 vs B3). Even if some differences were appreciated in 33 dogs, the right and left TMJ grades are dependent variables.
2. Grade A (normal TMJ): Rounded mandibular head, concave mandibular fossa, long retroarticular process.
   Grade B1/B2 (mild to moderate dysplasia): Flattened mandibular head and fossa, some retroarticular process shortening.
   Grade B3/C (severe dysplasia): Square mandibular head, flat mandibular fossa, blunted or absent retroarticular process.

Question 8

JVD 2024. Paran et al. Morphological Assessment of the TMJ in Asymptomatic Barchycephalic Dogs Using CT.

Did any unexpected findings appear on CT scans?

Answer 8

8 dogs had subchondral cysts in the mandibular head, but no signs of osteoarthritis were present. These were considered incidental findings.

Question 9

“Morphometry and Morphology of the Articular Surfaces of the Medial Region of the Temporomandibular Joint in the Felis Catus (Domestic cat) - A Cone Beam Computed Tomography Study”. Lenin A. Villamizar-Martinez et al. JVD 2023.

What was the mean degree of TMJ coverage?

Answer 9

171°

Question 10

“Morphometry and Morphology of the Articular Surfaces of the Medial Region of the Temporomandibular Joint in the Felis Catus (Domestic cat) - A Cone Beam Computed Tomography Study”. Lenin A. Villamizar-Martinez et al. JVD 2023.

How did the articular head appear?

Answer 10

96.6% of TMJs had a well-defined, rounded articular head that fit deeply into the mandibular fossa.

3.4% had an irregular articular head countour, which could indicate natural variation or postmortem changes.

Question 11

“Morphometry and Morphology of the Articular Surfaces of the Medial Region of the Temporomandibular Joint in the Felis Catus (Domestic cat) - A Cone Beam Computed Tomography Study”. Lenin A. Villamizar-Martinez et al. JVD 2023.

on what side of the TMJ was the retroarticular process prominent? the articular eminence? how does this relate to TMJ luxation?

Answer 11

retroarticular process:

• prominent on the medial aspect
• prevents caudoventral dislocation of the TMJ

articular eminence:

• prominent on the lateral aspect of the joint, poorly developed on the medial
• prevents rostrodorsal dislocation of the TMJ

<br></br>bilateral symmetrical

Question 12

“Morphometry and Morphology of the Articular Surfaces of the Medial Region of the Temporomandibular Joint in the Felis Catus (Domestic cat) - A Cone Beam Computed Tomography Study”. Lenin A. Villamizar-Martinez et al. JVD 2023.

How does feline TMJ morphology compare to that of dogs?

Answer 12

Cats have a higher degree of TMJ coverage (171°) than dogs, meaning their TMJ is more stable and tightly articulated.

• In a similar study performed in dogs (Lenin A. Villamizar-Martinez et al. JVD 2016), an angle of 96.5° was associated with shallow mandibular fossae, small or absent retroarticular process and irregular articular head joint surface.

As a strict carnivore, TMJ congruence in the cat and the transversal disposition of the articular head into the mandibular fossa result in restricted movements of the mandibles in the sagittal plane, which allows cutting of food into small pieces before swallowing. The congruence of the TMJ may avoid dislocation of the condylar process from the mandibular fossa during the grasping of prey.

Question 13

“Morphometry and Morphology of the Articular Surfaces of the Medial Region of the Temporomandibular Joint in the Felis Catus (Domestic cat) - A Cone Beam Computed Tomography Study”. Lenin A. Villamizar-Martinez et al. JVD 2023.

What were the mean width and depth of the mandibular fossa?

Answer 13

• mean mandibular fossa width 6.1 mm
• mean mandibular fossa depth 2 mm

Question 14

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

what bones compromise the TMJ? What is its function?

Answer 14

The TMJ in dogs is a synovial joint with 2 articular surfaces:

• the mandibular fossa of the squamous portion of the temporal bone
• the articular head of the condylar process of the mandible

opening and closing the jaw

Question 15

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

what are the 3 skull conformations in dogs?

Answer 15

• mesaticephalic (mesocephalic)
• brachycephalic
• dolichocephalic

Question 16

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

what are some disorders of the TMJ listed?

Answer 16

• osteoarthritis
• fractures
• dysplasia
• ankylosis

Question 17

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

name 1, 2, 3, 4, and *.

Answer 17

1: mandibular fossa
2: retroarticular process
3: articular eminence
4: nuchal crest
*: EARCP=estimated axis of rotation of condylar process

Question 18

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

what was measured?

Answer 18

17 mesaticephalic dogs, 31 brachycephalic dogs

• width and depth of mandibular fossa
• Angle 1 (degree of ventral extension of retroaticular process in relation to articular head of condylar process)
• Angle 2 (congruence between mandibular fossa and articular head of condylar process)

Question 19

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

what dog breeds were represented?

Answer 19

17 mesaticephalic:
* Labrador retriever
* cocker spaniel
* German shepherd

31 brachycephalic:
* boxer
* Cavalier King Charles spaniel
* English bulldog
* shih tzu
* pug

Question 20

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

overall, the mandibular fossa and retroarticular process measurements revealed what?

Answer 20

mandibular fossa:

• wider and deeper in labs, GSD, English bulldogs, and boxers
• shallower in cockers, shih tzus, and lone pug
• CKCS had shallowest of all mandibular fossa

retroarticular process:

• prominent in labs, GSDs, boxers, bulldogs
• less developed in cockers, shih tzus, and pug
• CKCS had small or absent retroarticular process

Question 21

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

what conclusions were drawn about the condylar process?

Answer 21

a more rounded condylar process (labs, GSD) had better congruence than a less rounded with more irregular subchondral bone.

Question 22

“Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography”. Lenin a. Villamizar-Martinez et al. JVD 2016.

what angle could partial or total loss of TMJ congruence be associated with?

Answer 22

angle 2 < 100

Question 23

JVD 2021. Thomson et al. Gape Angle in Asymptomatic Dogs with Normal Occlusion.

What’s the normal gape angle of an asymptomatic dog? Does it differ between the conscious and anesthetized patient?

Answer 23

A consistent gape angle of 44° exists in dogs not exhibiting overt signs of oral pain.
No significant difference between conscious and anesthetized patients.

Question 24

Kocsis et al. FVETS 2025.

what was the most used surgical technique for ankylosis? pseudoankylosis?

Answer 24

The surgical technique performed was significantly associated with the diagnosis

• GA (gap arthroplasty) was the most common in ankylosis cases
• EO (excisional ostectomy) was the most common in pseudoankylosis cases

“Outcomes of Surgical Management for Temporomandibular Joint Ankylosis and Pseudoankylosis: A Retrospective Report of 26 cases”. Kristin Kocsis, Stephanie Goldschmidt, Graham Paul Thatcher, Charles Lothamer, Lisa Alexandra Mestrinho. FVETS 2025.

Question 25

Kocsis et al. FVETS 2025. what complication can be seen with interpositional arthroplasty when utilizing temporalis myofascial graft as the interpositional material?

Answer 25

Temporal myofascial flap utilization can result in temporal muscle atrophy postoperatively in cats and dogs. Using alloplastic materials instead of autologous tissues for IA has been utilized in humans, with the goals of reducing donor site morbidity, decreasing ankylosis recurrence, and improving interincisal distance. ## Footnote *"Outcomes of Surgical Management for Temporomandibular Joint Ankylosis and Pseudoankylosis: A Retrospective Report of 26 cases". Kristin Kocsis, Stephanie Goldschmidt, Graham Paul Thatcher, Charles Lothamer, Lisa Alexandra Mestrinho. FVETS 2025.*

Question 26

Kocsis et al. FVETS 2025. what were the surgical treatment outcomes for ankylosis/pseudoankylosis in dogs and cats?

Answer 26

Sx outcomes were categorized with a proposed improvement score based on range of motion (ROM) improvement, requirement for revision surgery, and presence of transient or permanent complications. Sx outcomes were only assessed in patients with long-term follow-up (> 4 months, n = 13). * excellent in 53.8% (7/13) cases * good in 23.1% (3/13) cases * fair in 23.1% (3/13) cases * No poor outcomes were registered **mean ROM improved from 10.3 to 65.3 mm in dogs** (normal 107), and **from 5.71 to 33.6 mm in cats** (normal 62). ## Footnote *"Outcomes of Surgical Management for Temporomandibular Joint Ankylosis and Pseudoankylosis: A Retrospective Report of 26 cases". Kristin Kocsis, Stephanie Goldschmidt, Graham Paul Thatcher, Charles Lothamer, Lisa Alexandra Mestrinho. FVETS 2025.*

Question 27

Kocsis et al. FVETS 2025. what is the normal interincisal opening in dogs and cats? what was the improvemnt in ROM in dogs and cats surgically treated for ankylosis and pseudoankylosis?

Answer 27

Range of motion (ROM) was reported as an interincisal distance in mm. ROM improvement was noted among all patients. Mean (range) interincisal distance improved: * from 10.3 (2–30) to 65.3 (50–80) mm in dogs * from 5.71 (<1–20) to 33.6 (26–40) mm in cats Normal interincisal opening has been previously reported as: * 107 (range 40–180 mm) in dogs * 62 (range 41–84 mm) in cats. ## Footnote *"Outcomes of Surgical Management for Temporomandibular Joint Ankylosis and Pseudoankylosis: A Retrospective Report of 26 cases". Kristin Kocsis, Stephanie Goldschmidt, Graham Paul Thatcher, Charles Lothamer, Lisa Alexandra Mestrinho. FVETS 2025.*

Question 28

Kocsis et al. FVETS 2025. what was the complication rate following surgical treatment for ankylosis and pseudoankylosis in dogs and cats? what were the complications? what was associated with the need for revision surgery?

Answer 28

Segmental mandibulectomy (SM) resulted in complications in all cases, with no excellent outcomes. Perioperative complications were rare * hypothermia in 1/26 cases (a cat) Postoperative complication rate was 50% (13/26) * malocclusion (26.9%; 7/26) * neuromuscular issues (19.2%; 5/26) * re-ankylosis requiring surgical revision (15.4%; 4/26) * callus formation not requiring surgical revision (3.8%; 1/26) Surgical revision was only required in patients initially treated with SM and GA. The need for revision surgery was significantly associated with the surgical technique, with 60% (3/5) of animals treated with SM requiring surgical revision. ## Footnote *"Outcomes of Surgical Management for Temporomandibular Joint Ankylosis and Pseudoankylosis: A Retrospective Report of 26 cases". Kristin Kocsis, Stephanie Goldschmidt, Graham Paul Thatcher, Charles Lothamer, Lisa Alexandra Mestrinho. FVETS 2025.*

Question 29

"Outcomes of surgical management for temporomandibular joint ankylosis and pseudoankylosis: a retrospective report of 26 cases". Kristin Kocsis et al. FVETS 2025. What percentage of cases required revision surgery due to re-ankylosis? What rough age were these patients?

Answer 29

Surgical revision due to re-ankylosis was required in 15.4% (4/26) cases: 2/14 cats, 2/16 dogs. All less than 1 year old Surgical revision was only required in patients initially treated with segmental mandibulectomy (SM) or gap arthroplasty (GA). The need for revision surgery significantly associated with the surgical technique, with 60% (3/5) of animals treated with SM requiring surgical revision.

Question 30

"Outcomes of surgical management for temporomandibular joint ankylosis and pseudoankylosis: a retrospective report of 26 cases". Kristin Kocsis et al. FVETS 2025. What rate of postoperative complications were seen?

Answer 30

50% (13/26) * malocclusion 26.9% (7/26) * neuromuscular issues 19.2% (5/26) * re-ankylosis requiring surgical revision 15.4% (4/26) * callus formation not requiring surgical revision 3.8% (1/26)

Question 31

"Outcomes of surgical management for temporomandibular joint ankylosis and pseudoankylosis: a retrospective report of 26 cases". Kristin Kocsis et al. FVETS 2025. What was the conclusion regarding when a segmental mandibulectomy (SM) would be most appropriate?

Answer 31

SM should be reserved only for cases at very high risk of iatrogenic complications with more extensive procedures. * SM was the technique associated with the highest number of complications, as they were noted to varying degrees in all five cases * 60% (3/5) of animals treated with SM required surgical revision (highest frequency of all surgical techniques)

Question 32

according to Arzi, JAVMA 2023. what bones are more frequently broken in TMJ fractures in dogs? cats?

Answer 32

* In dogs, the frequency of fractures of the mandibular fossa of the temporal bone or condylar process of the mandible is similar. * In cats, the condylar process of the mandible is the most fractured bone in the TMJ, with substantially lesser occurrence for the mandibular fossa of the temporal bone. * Intra-articular fractures tend to occur in most TMJ fractures of cats and to a lesser degree in dogs. In immature dogs, rostral mandibular trauma (symphyseal separation, rostral mandibular fractures) is significantly associated with articular surface fractures of the TMJ. ## Footnote *"Contemporary management of temporomandibular joint fractures in dogs and cats: review and expert insights on diagnostic imaging, treatment strategies, and long-term outcomes". Boaz Arzi. JAVMA 2023.*

Question 33

according to Arzi, JAVMA 2023. is TMJ trauma more severe when the trauma is sustained with an open or closed mouth?

Answer 33

It is speculated that trauma occurring with the mouth open facilitates the transmission of external force to the condylar process and the TMJ in general. When the mouth is closed, teeth in occlusion promote a defense against transmitting the trauma forces to the TMJ. ## Footnote *"Contemporary management of temporomandibular joint fractures in dogs and cats: review and expert insights on diagnostic imaging, treatment strategies, and long-term outcomes". Boaz Arzi. JAVMA 2023.*

Question 34

according to Arzi, JAVMA 2023. what is the difference in outcome following ORIF and closed treatment of TMJ fractures?

Answer 34

Both ORIF and closed treatment yield acceptable results. significant clinical differences in terms of occlusion, mouth opening, functionality, and pain in favor of open reduction. ## Footnote *"Contemporary management of temporomandibular joint fractures in dogs and cats: review and expert insights on diagnostic imaging, treatment strategies, and long-term outcomes". Boaz Arzi. JAVMA 2023.*

Question 35

Arzi, JAVMA 2023. prevalence of TMJ ankylosis in humans/dogs/cats?

Answer 35

* in a study evaluating trauma in imature dogs, 36% exhibited articular surface fractures, none developed TMJ ankylosis. * 0.4% occurrence of TMJ ankylosis in people following TMJ fractures. * 11% in cats, with no significant relationship between age and the development of ankylosis, mainly in fractures affecting the condylar process and mandibular fossa combined. ## Footnote *"Contemporary management of temporomandibular joint fractures in dogs and cats: review and expert insights on diagnostic imaging, treatment strategies, and long-term outcomes". Boaz Arzi. JAVMA 2023.*

Question 36

"Comparison of unilateral rostral, middle and caudal segmental mandibulectomies as an alternative treatment for unilateral temporomandibular joint ankylosis in cats: an ex vivo study". Lenin A Villamizar-Martinez, Han Chia, James B Robertson, Cristian M Villegas, Alexander M Reiter. JFMS 2021. what was the recovered VROM in cats following unilateral rostral, middle, and caudal segmental mandibulectomy?

Answer 36

The mean postoperative recovered VROM (percentage of normal mouth opening) * rostral segmental mandibulectomy 50.4% (2.29 vs 4.67 cm) * middle segmental mandibulectomy 81.9% (3.55 vs 4.33 cm) * caudal segmental mandibulectomy 90.4% (4.2 vs 4.66 cm)

Question 37

"Comparison of unilateral rostral, middle and caudal segmental mandibulectomies as an alternative treatment for unilateral temporomandibular joint ankylosis in cats: an ex vivo study". Lenin A Villamizar-Martinez, Han Chia, James B Robertson, Cristian M Villegas, Alexander M Reiter. JFMS 2021. why was the recovered VROM in cats following unilateral rostral mandibulectomy 50.4%?

Answer 37

The decreased VROM following rostral segmental mandibulectomy was associated with tension over the mucoperiosteal flap. While opening the mouth, most of the lingual alveolar mucosa remained attached to the remaining ‘ankylosed’ mandible, decreasing the flap′s elasticity. In a clinical setting, the tension generated while opening the mouth would cause poor wound healing, dehiscence and failure of the surgical procedure.

Question 38

"Comparison of unilateral rostral, middle and caudal segmental mandibulectomies as an alternative treatment for unilateral temporomandibular joint ankylosis in cats: an ex vivo study". Lenin A Villamizar-Martinez, Han Chia, James B Robertson, Cristian M Villegas, Alexander M Reiter. JFMS 2021. what was the length of bony segment required to achieve nearly full recovery of presurgical mouth opening in cats following unilateral caudal segmental mandibulectomy?

Answer 38

removal of a minimum of 1.2cm of the caudal mandibular body was required to achieve nearly full recovery of presurgical mouth opening

Question 39

"Comparison of unilateral rostral, middle and caudal segmental mandibulectomies as an alternative treatment for unilateral temporomandibular joint ankylosis in cats: an ex vivo study". Lenin A Villamizar-Martinez, Han Chia, James B Robertson, Cristian M Villegas, Alexander M Reiter. JFMS 2021. what should be expected to occur following segmental mandibulectomy for TMJ ankylosis in cats?

Answer 39

all the specimens presented postoperative lateral instability of the remaining non-ankylosed (contralateral) mandible (mandibular drift).

Question 40

"Comparison of unilateral rostral, middle and caudal segmental mandibulectomies as an alternative treatment for unilateral temporomandibular joint ankylosis in cats: an ex vivo study". Lenin A Villamizar-Martinez, Han Chia, James B Robertson, Cristian M Villegas, Alexander M Reiter. JFMS 2021. would a bilateral segmental mandibulectomy be suitable for cats with bilateral TMJ ankylosis?

Answer 40

Bilateral segmental mandibulectomy may not be suitable for cats affected by bilateral TMJA owing to a hanging effect of the mandibles′ remaining rostral portion.

Question 41

"Vertical Mandibular range of Motion in anesthetized Dogs and cats". Margherita Gracis, Eric Zini. FVETS 2016. mean vmROM in cats?

Answer 41

mean vmROM of cats 62 mm (median 63, range 41–84)

Question 42

"Vertical Mandibular range of Motion in anesthetized Dogs and cats". Margherita Gracis, Eric Zini. FVETS 2016. mean vmROM in dogs? dogs according to weight groups?

Answer 42

mean vmROM of all dogs 107 mm (median 109, range 40–180) * ≤5.0 kg, 67 mm * 5.1–10 kg, 93 mm * 10.1–25 kg, 115 mm * >25.1 kg, 134 mm

Question 43

"Vertical Mandibular range of Motion in anesthetized Dogs and cats". Margherita Gracis, Eric Zini. FVETS 2016. influence of age/weight/sex on vmROM in cats/dogs?

Answer 43

vmROM in dogs did not correlate with age, in cats a weak positive correlation was found. vmROM and body weight were positively correlated in both populations, except in dogs weighing 5.1-10 kg. * mean vmROM and body weight were significantly higher in male than in female, both in dogs and in cats. * however, vmROM did not differ between sexes in any of the canine subgroups, and only in subgroup 4 (>25.1 kg) male dogs were significantly heavier than females.

Question 44

"Management of Septic Arthritis of the Temporomandibular Joint in Dogs". Boaz Arzi, Natalia Vapniarsky, Amy Fulton, Frank J. M. Verstraete. FVETS 2021. clinical presentation of septic arthritis of the TMJ? TMJ-OA?

Answer 44

* Osteoarthritis of the TMJ (TMJ-OA) is symptomatic and associated with mild to moderate pain or merely discomfort in only ∼25% of the cases. * Septic arthritis of the TMJ is a “high inflammatory” arthritis presented with pronounced pain (periauricular pain, pain when opening/closing the mouth) and dysfunction (limited VROM), stiffness, swelling, and potentially the presence of a draining tract. Unlike degenerative TMJ disease, septic arthritis requires urgent intervention.

Question 45

"Management of Septic Arthritis of the Temporomandibular Joint in Dogs". Boaz Arzi, Natalia Vapniarsky, Amy Fulton, Frank J. M. Verstraete. FVETS 2021. what are the etiologies of septic arthritis of the TMJ?

Answer 45

* local dissemination of infection from adjacent anatomical structures, such as the inner ear/tympanic bulla that acts as a continuous focus of infection * trauma (direct inoculation by a dog bite) * penetrating stick injury to the pharyngeal area * hematogenous spread from a distant site The precise cause may not always be identified.

Question 46

"Management of Septic Arthritis of the Temporomandibular Joint in Dogs". Boaz Arzi, Natalia Vapniarsky, Amy Fulton, Frank J. M. Verstraete. FVETS 2021. what are the purposes of surgical approach to the TMJ in cases of septic TMJ arthritis?

Answer 46

* obtain diagnostic samples for culture and sensitivity and histopathology * decompress the joint and the associated abscess (if present) * remove joint debris * copiously irrigate the dorsal and ventral compartments of the joint with sterile saline to reduce the inflammatory burden

Question 47

"Etiology, clinical presentation, and outcome of temporomandibular joint luxation in cats: 21 cases (2000–2018)". Jin W. Jung, Ana C. Castejón-González, Darko Stefanovski, Alexander M. Reiter. FVETS 2023. what were the etiologies for TMJ luxation?

Answer 47

* altercation with a dog (38%) * HBC (19%) * unknown (19%) * fall (19%) * ran into inanimate object (5%)

Question 48

"Etiology, clinical presentation, and outcome of temporomandibular joint luxation in cats: 21 cases (2000–2018)". Jin W. Jung, Ana C. Castejón-González, Darko Stefanovski, Alexander M. Reiter. FVETS 2023. how many of the luxations were rostrodorsal? caudoventral?

Answer 48

* rostrodorsal luxation 19/21 (90.5%) * caudoventral luxations 2/21 (9.5%) Cats with fracture of the condylar process or mandibular fossa on the same side of TMJ luxation were excluded.

Question 49

"Etiology, clinical presentation, and outcome of temporomandibular joint luxation in cats: 21 cases (2000–2018)". Jin W. Jung, Ana C. Castejón-González, Darko Stefanovski, Alexander M. Reiter. FVETS 2023. what concurrent injuries were seen in cats with TMJ luxation?

Answer 49

90.5% cats had concurrent injuries * lip/oral mucosal bruising or laceration 47.6% (10/21) * tooth fracture 42.9% (9/21) * symphyseal separation 42.9% (9/21) in 5/9 (55.6%) cats following altercation with a dog * maxillary fracture 19% (4/21) in 2/4 (50%) cats following HBC * ocular and orbital injury 19% (4/21) * tongue injury 14.3% (3/21) * mandibular fracture 14.3% (3/21) * other intra-articular TMJ injury such as condylar process fracture on the opposite side of TMJ luxation 4.8% (1/21) * lip avulsion 4.8% (1/21)

Question 50

"Etiology, clinical presentation, and outcome of temporomandibular joint luxation in cats: 21 cases (2000–2018)". Jin W. Jung, Ana C. Castejón-González, Darko Stefanovski, Alexander M. Reiter. FVETS 2023. what was the success rate for reduction of the TMJ luxation? what was the only factor significantly associated with successful reduction of the TMJ luxation?

Answer 50

Reduction was successful in 94.7% of the cases. significantly associated with time from injury to treatment (if the luxation is not reduced in a timely manner, inflammatory and fibrotic changes may occur in the joint capsule and articular disc that could interfere with the success of joint reduction and overall TMJ health).

Question 51

"Etiology, clinical presentation, and outcome of temporomandibular joint luxation in cats: 21 cases (2000–2018)". Jin W. Jung, Ana C. Castejón-González, Darko Stefanovski, Alexander M. Reiter. FVETS 2023. what was the most common complication?

Answer 51

* development of permanent malocclusion (24%) * reduced VROM (5%) There were no significant associations between complications, malocclusion or reduced VROM, and the presence of maxillary fractures or articular and non-articular mandibular fractures. Considering that all but one of the cases that had complications sustained mandibular or maxillary fractures, it is possible that those injuries were responsible for the malocclusion or decreased VROM instead of the TMJ luxation. Also, other non-diagnosed injuries of the TMJ that are separate from luxation, may have contributed to these findings.

Question 52

Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020. At initial presentation, which quantitative finding best characterized the severity of functional impairment in the majority of cats with TMJ ankylosis?

Answer 52

severly restricted mouth opening approximately 2–3 mm in 6/7 cats ## Footnote *"Temporomandibular Joint Gap Arthroplasty in Cats". Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020.*

Question 53

Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020. which cone-beam CT finding was consistently associated with ankylosed temporomandibular joints in the studied cats?

Answer 53

joint space narrowing to complete loss with bridging bone ## Footnote *"Temporomandibular Joint Gap Arthroplasty in Cats". Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020.*

Question 54

Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020. in how many cats undergoing gap arthroplasty for extensive TMJ ankylosis was temporary tracheostomy intubation required?

Answer 54

6/7 (85.7%) cats required temporary tracheostomy intubation due to decreased VROM ## Footnote *"Temporomandibular Joint Gap Arthroplasty in Cats". Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020.*

Question 55

Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020. what was found on follow-up CBCT in all cats that had one after gap arthroplasty?

Answer 55

new bone formation leading to pseudoarthrosis or pseudoankylosis in 3/3 cats that had follow-up CBCT * 2/3 with decreased VROM * 1/3 with normal VROM ## Footnote *"Temporomandibular Joint Gap Arthroplasty in Cats". Armeti Aghashani, Frank J. M. Verstraete, Boaz Arzi. FVETS 2020.*

Question 56

Ankylosis and pseudoankylosis of the temporomandibular joint in 10 dogs Peter C. Strøm1; Boaz Arzi2; Derek D. Cissell2; Frank J. M. Verstraete2 Vet Comp Orthop Traumatol . 2016 What are the most common tumours of the TMJ in dogs?

Answer 56

osteosarcoma and multilobular tumour of bone

Question 57

Ankylosis and pseudoankylosis of the temporomandibular joint in 10 dogs Peter C. Strøm1; Boaz Arzi2; Derek D. Cissell2; Frank J. M. Verstraete2 Vet Comp Orthop Traumatol . 2016 In this paper how many dogs achieved a normal/near normal range of motion after surgery? How many regained the ability to open their mouths? How many required revision surgery?

Answer 57

normal/near normal range of motion after surgery = 2/9 (NOTE: Surprisingly low) How many regained the ability to open their mouths? 8/9 How many required revision surgery? 1/9

Question 58

Ankylosis and pseudoankylosis of the temporomandibular joint in 10 dogs Peter C. Strøm1; Boaz Arzi2; Derek D. Cissell2; Frank J. M. Verstraete2 Vet Comp Orthop Traumatol . 2016 Was ankylosis or pseudoankylosis more common in this study? How commonly was the zyogmatic arch part of the problem?

Answer 58

Ankylosis only in 2/10 Pseudoankylosis in 7/10 (1/10 had both) Zygomatic arch involvement 6/10

Question 59

"Combined Gap and Interpositional Arthroplasty Utilizing Three-Dimensional Printed Model in a Dog with TMJ Ankylosis and Pseudoankylosis". Renner and Thatcher. JVD 2022. What was the immediate result of the surgery?

Answer 59

improvement in * inter-incisal distance: from 7 mm pre-op to 70 mm 20 days post-op, and 76 mm 3 months post-op * ability to pant * ease of chewing

Question 60

"Repair and remodeling of the mandibular head of the condylar process in four immature dogs". Christopher P. Sauvé, Nadine Fiani, Santiago Peralta, David C. Hatcher, Boaz Arzi. FVETS 2023. collagen in fibrocartilage vs hyaline cartilage? which one is present in the articular surfaces of the TMJ?

Answer 60

The TMJ comprises two separate, non-communicating compartments: the dorsal (temporal) and ventral (mandibular), separated by an intraarticular fibrocartilaginous disc. The articular surfaces of the TMJ consists of fibrocartilage, containing both Type I and II collagen, which contrasts with hyaline cartilage that is predominately composed of type II collagen.

Question 61

"Repair and remodeling of the mandibular head of the condylar process in four immature dogs". Christopher P. Sauvé, Nadine Fiani, Santiago Peralta, David C. Hatcher, Boaz Arzi. FVETS 2023. what is the role of the TMJ disc in regeneration of the mandibular head of the condylar process?

Answer 61

In comparison to long bones, the mandible displays enhanced osteogenic potential due to its elevated angiogenic capabilities and enhanced bone-forming gene expression in mandibular bone marrow stromal cells (BMSC), in contrast to femur-derived BMSC. The TMJ disc is believed to play a significant role in regeneration of the mandibular head of the condylar process by stimulating differentiation of periosteal cells primarily situated in the medial region of the ramus, collectively referred to as a blastema. When a TMJ disc is absent following condylectomy there is failure to regenerate the mandibular head of the condylar process, leading to intraarticular fibrous ankylosis. Therfore, preservation of the TMJ disc during condylectomy appears crucial to prevent intraarticular fibrous ankylosis.

Question 62

"Repair and remodeling of the mandibular head of the condylar process in four immature dogs". Christopher P. Sauvé, Nadine Fiani, Santiago Peralta, David C. Hatcher, Boaz Arzi. FVETS 2023. what was seen on CT/CBCT of the cases in this report?

Answer 62

CT/CBCT images demonstrate a condyle-like shaped bony structure with irregular margins (repair and remodeling of the osseous tissues of the mandibular head of the condylar process). Modeling of the mandibular head of the condylar process involves an uncoupled osteoblastic and osteoclastic function, allowing the bone to enlarge and drift in 3D space. Remodeling of the mandibular head of the condylar process involves a coupled osteoblast–osteoclast function within the bone’s internal anatomy to allow it to maintain its structure.

Question 63

"Management of Temporomandibular Joint Luxation in a Cat Using a Custom-Made Tape Muzzle". Amy J. Somrak, Sandra Manfra Marretta. JVD 2015. which way does the mandible shift (away or towards affected TMJ) in caudovental luxation and rostrodorsal luxation (unilateral)?

Answer 63

* impingement of the mandibular coronoid process lateral to the zygomatic arch: a wide opened mouth and the mandibles slightly protruded. The canine and incisor teeth on the affected side rest more ventrally than normal, with no contact between the maxillary and mandibular canine teeth. The malpositioned coronoid process may be palpated lateral to the zygomatic arch. * unilateral rostrodorsal TMJ luxation: the mandibles shift to the side opposite the luxation. * bilateral luxations: both mandibles are displaced rostrally. * unilateral caudoventral luxation: the mandibles shift caudally and toward the luxated side.

Question 64

"Management of Temporomandibular Joint Luxation in a Cat Using a Custom-Made Tape Muzzle". Amy J. Somrak, Sandra Manfra Marretta. JVD 2015. What are contraindications for tape muzzle therapy?

Answer 64

Contraindications for tape muzzle application: * patients with canine tooth fractures that prevent the canine teeth from remaining interdigitated * brachycephalic breeds * pre-existing or post-traumatic respiratory distress * vomiting or regurgitation * bilateral mandibular fracture * complicated, severely displaced or comminuted fractures

Question 65

"Management of Temporomandibular Joint Luxation in a Cat Using a Custom-Made Tape Muzzle". Amy J. Somrak, Sandra Manfra Marretta. JVD 2015. for how long should TMJ movement be resreicted following resuction of TMJ luxations?

Answer 65

When reduction of TMJ luxation is easy and the joints are stable, restricting motion of the TMJs during healing is not generally required post-reduction. If additional security is desired, a tape muzzle or other method to restrict joint movement may be applied for 2-3 weeks. TMJ movement should be restricted for 1-4 weeks during the healing period following difficult or unstable reductions with rigid maxillomandibular fixation or non-rigid fixation, such as a tape muzzle.

Question 66

EVDC Webinar Boaz Arzi TMJ What innervates the TMJ?

Answer 66

Auriculotemporal nerve, a branch of the mandibular portion of the trigeminal. Masseteric nerve, a branch of the maxillary portion (V2) of the trigeminal nerve, innervates the rostromedial capsule

Question 67

EVDC Webinar Boaz Arzi TMJ What is Hilton's law and what is it's significance in relation to TMJ fractures?

Answer 67

Hilton's Law: Muscles that move the joint are innervated by the same nerves that move the joint. = hard to tell the difference between muscle pain and joint pain (eg humans with masseter pain may have tmj fracture (masseter contraction to protect tmj)

Question 68

EVDC Webinar Boaz Arzi TMJ (Wolfs et al, frontiers) What fracture location is significantly associated with TMJ fractures (at least in immature dogs)?

Answer 68

Rostral mandibular fractures significantly associated with TMJ articular surface fractures (p=0.016)