2016 #3 The Influence of Axial Grooves on the Dislodgment Resistance of Prosthetic Metal Crowns in Maxillary Fourth Premolar Teeth of Dogs Flashcards
What was the objective of the study?
To quantify the influence of axial grooves on the dislodgment resistance of full veneer metal crowns in dogs on the maxillary 4th premolar
How was the study designed?
2 groups with 15 crowns each 1 group with axial grooves 1 group without axial grooves
What percentage of injured teeth in dogs are premolars?
39%
What percentage of full metal crowns failed due to poor retention on maxillary 4th premolars?
20% (same as canine teeth but there is only 1 study with max 4th premolar and it was small sample size)
What is the natural CA of maxillary 4th premolars? What is the ideal CA?
43 degrees, ideal is 12 degrees
What were the dimensions of the ivorine tooth used in the study?
Height=5 mm Diameter = 7.5 mm H/D= 0.66
What was the CA of the tooth used in the study?
43 degrees
Where were the axial grooves placed?
Mesial and distal axial walls
What angle and what direction was the force applied in the study on the maxillary 4th premolar?
45 degrees (same as canine tooth study) Oblique direction (same as canine tooth study) Palatal to Buccal (canine was distal to mesial)
What were the results of the study on axial grooves for crowns for maxillary 4th premolar?
Force required to dislodge crowns No grooves = 1618 N (1175-1850) Grooves= 2437N (1961-2997) 1.5 times greater force necessary for crown dislodgment in teeth with grooves
How did grooves increase force necessary for dislodgment in canine teeth vs maxillary 4th premolar?
1.5 times greater with maxillary 4th premolar 6 times greater with canine
How did the overall force required compare between canine teeth vs maxillary 4th premolar?
Much higher force required for dislodgment of maxillary 4th premolar crowns ( 156N for canine tooth, 1618 N for maxillary 4th premolar)
What was the calculated CAlim? What was the CA used?
41 degrees, 43 degrees
What type of cement was used in this study on maxillary 4th premolar crowns?
Resin-Modified Glass Ionomer (same as canine crown study)
What are bite forces reported in conscious companion dogs? Working dogs?
13-1394 N for conscious companion dogs 180-1120N for conscious working dogs
What are the bite forces previously reported in anesthetized dogs using electric stimulation of the masseter and temporalis muscle?
canine teeth- 530- 960 N caudal teeth 208/309 and 108 /409- 1890-3400 N
What are the 2 proposed ways axial grooves increase crown retention in maxillary 4th premolars?
1 Increased surface area available for cement bonding 2 Decrease the effective CA of the crown prep by replacing the axial wall CA with the CA of the created axial groove
What is the arrow pointing at? Which wall were they placed for maxillary 4th premolars?
Axial grooves for increased retention of crowns
Mesial and Distal axial walls
What is ideal convergence angle (CA) ?
What was the calculated CAlim?
What was CA used in this study?
12 degrees
41 degrees
43 degrees
What were the height and diameter dimensions for the study of crown retention in maxillary 4th premolars?
Height= 5 mm
Diameter= 7.5 mm
