Surveyed Crowns

Question 1

what do you look for in survey crowns

Answer 1

• condition of all the remaining teeth: periodontal/caries
• condition of the ridges
• inter occlusal space
• supra eruption of teeth
• occlusion: attrition/wear facets, interferences

Question 2

which teeth require surveyed crowns

Answer 2

• abutment teeth with large restorations
• abutment teeth with existing crowns that cannot be modified
• supra erupted teeth
• teeth without the needed contours (guide planes, undercuts, etc)

Question 3

what are the things to do prior to cutting the survey crown

Answer 3

• design the RPD
• identify any necessary changes in the occlusal plane
• make RPD preparations on the other teeth involved
• fabricate a complete arch custom tray

Question 4

what are the considerations in preparing the crown

Answer 4

• minimal changes from a conventional crown prep
• additional reduction to allow space for rest seats or to allow for guide planes on teeth that have drifted
• evaluate and identify the appropriate occlusal plane and adjust occlusal reduction as needed ( warn pt of a possible pulpal exposure and need for RCT or TE)

Question 5

what are the steps in evaluating and preparing the model work

Answer 5

• survey the cast and draw tripod marks
• if there are no posterior steps, an additional appointment will be needed to record the VDO/jaw relation with a wax rim

Question 6

how do you fabricate an occlusal registration when posterior occlusion is not present

Answer 6

• the lab should provide a pindexed model and a static model
• a wax rim should be fabricated on the static cast
• a wax rim may also be necessary for the opposing arch is minimal natural occlusion is present
• pt returns and provisional is removed
• wax rim placed and occlusion record made with regisil
• provisionals recemented and pindexed model articulated using the wax rim and occlusal registration

Question 7

what needs to be included in the lab script

Answer 7

RPD modifications such as guide planes, rest seats, and designed undercuts

Question 8

what is done during cementation

Answer 8

• utilize the same techniques used with traditional crowns
• evaluate interocclusal clearance with rest seats
• verify guide planes and undercuts with other abutment teeth

Question 9

the use of the plane created with the anterior teeth and the retromolar pads only work if:

Answer 9

the anterior teeth have not supra erupted

Question 10

what do you need to do if the anterior teeth have supra erupted

Answer 10

a maxillary wax rim or maxillary denture wax try in will need to be completed first followed by fabrication of anterior surveyed crowns or enameloplasty to ensure proper height

Question 11

what are the steps to fabricate a surveyed crown to correct an issue with supra eruption

Answer 11

• wax an opposing tooth to an ideal occlusal height
• reduce the occlusion of the supra erupted tooth on a duplicate cast to the ideal waxed occlusion
• make a vacuum form matrix on the cast with the corrected occlusion
• utilize the clear matrix to evaluate for adequate reduction

Question 12

the prognosis of an RPD is only as good as:

Answer 12

its weakest abutment