Frontiers 2019: Fracture Limits of Maxillary Fourth Premolar Teeth in Domestic Dogs Under Applied Forces REITER, SOLTERO RIVERA ET AL Flashcards
Authors?
M. Soltero-Rivera
A. Reiter et AL
Type and purpose of the study?
- cadaveric study on 24 Mx PM4 of dogs
- Aim:
- investigate external mechanical forces required to fracture Mn PM4 in dogs;
- describe a clinically relevant model of chewing forces placed on functionally important teeth in which fracture patterns correspond to AVDC fracture descriptions;
- determine impact of dog signalment (breed, age, weight) and tooth caracteristics (crownh height, crown diam., crown height/crown diam. ratio) on force needed to fracture.
- Use info for future studies to establish criteria for chewing textures of treats and toys.
What is the reported prevalence of tooth fracture ? To what percentage the prevalence increase in maxillofacial trauma patients?
- Prevalence of tooth fracture: 20-27%
- increases to 67-85% in MF trauma.
According to literature and previous study,
What is the voluntary bite forces of dogs?
What is the pulling force of dogs when all 4 canine teeth are involved?
What is the maximum potential bite forces for dogs under peak model?
- Biting forces: 13 to 1394 N (proportional to size)
- Pulling force: 480 - 1200 N
- Peak model bite forces: >3400 N (molar teeth)
In Soukup study (JOVD 2015), what was the force to fracture of canine teeth in dog?
- Force to fracture of canine teeth (at 45 angle) : 494 - 630 N depending on crown height/diam. ratio (lower ration = higher resistance)
- Previously approximate fracture force of PM4: 890 N
What was the mean maximum force sustained by the teeth at the point of fracture and what was the impact angle?
Is this force similar to what was previously suggested for Mx PM4?
- Force: 1281 N (± 403 N); Angle: 59.7◦ (± 5.2◦)
- No previous suggested force to fracture for Mx PM4: 890 N
In descending order of frequency of occurrence what were the most common fractures?
- Complicated crown fracture (50%)
- Uncomplicated crown fracture ( 25%)
- Complicated crown/root fracture (20.8%)
- Uncomplicated crown root fracture (4.2%)
Which of the following factors were found as significant independent variable on maximum force to fracture?
A) Impact angle
B) Crown height
C) Crown diameter
D) Crown height/Diam ratio
E) Dog age
F) Dog weight
G) Fracture type
D) crown height to diameter ratio; decreased ratio increases tooth fracture resistance.
Dog age, weight, fracture type and crown diam. show trends for association but not as independant variables.
How did crown height to diameter ratio affect the maximum force to fracture?
For every one unit increase in the crown height to diameter ratio, the maximum force was decreased by 3137 N
What is this device and what does it do?
A) Computer-generated drawing that depicts the aluminum jig used to create compressive loading in a controlled manner. The device was holding each pot at an angle of 60° (θ) with respect to the ground.
B) Right maxillary fourth premolar tooth with surrounding alveolar bone seated inside a polycarbonate cylinder filled with PMMA. The pot is held by the aluminum device, and the steel actuator is coming into contact with the occluso-palatal aspect of the main cusp of the tooth at the onset of mechanical testing.
What was a limitation of the study and how could this be addressed in the future?
- The study is limited by the use of point force application and testing to load to failure.
- This could be improved by using a 4-point bending model and cyclic loading to failure. A 4-point bending model would employ forces on the cusps of maxillary fourth premolar teeth to provide downward force vectors on the outside of the object while the cusps of mandibular first molar teeth would provide an upward force vector on the inside of the object.
When a dog chew on an object, does the impact angle with the Mx PM4 always the same?
No, it depends on how for the object is inserted into the mouth and the form of the object.
