Favourable and Unfavorable fractures of the mandible
Fractures of the mamdible are considered to be the most common type of fractures in the body and Angle of mandible being the most common in mandible fractures.
Fractures are divided into favorable and un favorable fractures due to the action of muscles attached to the fractured segments of the mandible. The action of the muscles sometimes helps the fracture segment anterior to the fracture line to stay in place and sometimes pulls the anterior or posterior segment away from the opposing bone due to the action of muscles like masseter, lateral pterygoid, medial pterygoid, temporalis, mylohyoid, geniohyoid, genioglossus and anterior belly of digastric which exert a centripetal force on the mandible.
Here we are going to list out the favorable and unfavorable fractures of mandible based on the Origin and Course of fracture line:
horizontal favorable fracture
1. Horizontally favorable fractures: The fracture line starts at the alveolar margin and extends forward or anteriorly and downwards till the lower border of mandible. The Elevator and Depressor Muscles act against each other and help in keeping the bones on either sides of the fracture line to be kept in position which helps in preventing unnecessary movements and decreases time of healing.
horizontal unfavorable
2. Horizontally unfavorable fractures: The fracture line starts at the alveolar margin and extends downwards and backwards till the lowest border of mandible is reached. The Elevator and Depressor Muscles act in the same direction and this causes the bones on either sides of the fracture line to move away from each other which causes unnecessary movements and increases time of healing.
Vertical fractures are seen from the top of the mandible or from the occlusal surface.
vertical favorable
3. Vertically favorable fractures: Fracture line starts at the buccal or outer border of the mandible and it extends obliquely backwards towards the lingual margin of mandible. The Elevator and Depressor Muscles act against each other and help in keeping the bones on either sides of the fracture line to be kept in position which helps in preventing unnecessary movements and decreases time of healing.
vertical unfavorable
4. Vertical unfavorable fractures: Fracture line starts at the lingual or inner border of the mandible extending obliquely backwards towards the buccal margin of the mandible. The Elevator and Depressor Muscles act in the same direction and this causes the bones on either sides of the fracture line to move away from each other which causes unnecessary movements and increases time of healing.
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I am Varun, a Dentist from Hyderabad, India trying my bit to help everyone understand Dental problems and treatments and to make Dental Education simplified for Dental Students and Dental fraternity. If you have any doubts feel free to contact me or comment in the post, thanks for visiting.
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thank you, for this explanation of mandible fractvre
thank u for sharing
tnks for this
thnkz 4 da clear concept.
lateral pterygoid is the only opener muscle amongest all the muscles of mastication . also the movement of the bone fragments occurs only if periosteum is stripped off and in the angle region,movement of fragments occur due to masseter muscle and medial pterygoid, of which the action of medial pterygoid is stronger. the medial pterygoid muscle pulls the posterior fragment lingually if the fracture is unfavourable
if the vertical direction of fracture line favours the unopposed action of medial pterygoid, posterior fragment will be pulled lingually.if horizontal direction of fracture line favours unopposed action of masseter and medial pterygoid in an upward direction the posterior frqgment will be displaced upwards. Vertically and horizontally unfavourable fractures may be undisplaced if periosteum is undisturbed
jiye bhutto :p
Which muscles pull mandible backwards in bilateral canine fracture?
Geniohyoid,genioglossus & digastric
& it’s inferiorly & backwards