Accurate Model Measuring in D-Cad Prepared by Drs Jeffery Taylor and David Dana

YOU need a mouse if you only have a touch pad! Using a touch pad is not accurate to place the points Use a Mouse!

Typical Scan of upper arch, anterior segment http://www.dentalemodels.com/

Note contact point shown by arrow

Now note point of transition from incisal edge to proximal surface

Here are the same points shown in black and white respectively, same model rotated to show incisal edge view

Most common error is to locate DentCad points at the white locations when they should be at the black ones.

Zoom view of same Dcad file

With tooth outlines moved NOT HERE Place point here

Incorrect point placement = Incorrect tooth size, incorrect amount of crowding, inadequate vto, and wrong loop size selection AND MOST IMPORTANT INCORRECT DIAGNOSIS AND TREATMENT PLAN

Model analysis It is extremely important that the model analysis represent what you see clinically If you see 5 mm crowding, then the model analysis should have 5 mm crowding

Example This case has 10mm crowding on the lower and 10 mm on the upper

Arch wire was placed correctly, on the incisal edges, and points were placed incorrectly making the analysis to show 2mm crowding lower and 0 upper

This is the most common error made Not to confirm that the model represents what is seen clinically Points should be at the widest mesi-distal width of the tooth If the teeth have contact points the vectors should touch each other

The arrows mark areas of incorrect point placement

The widest part of the bicuspids is not at the central grove -it is at the buccal line angles Notice the incisors vectors in blue contacting (same as the teeth)

The real point is the white center in the blue dot, not the edge of the Blue/Green dot

If the incisors have a normal contact the mesial and distal dots will overlap Notice 31 and 41 points are on top of each other as they share a contact that is not broken

VTO OBTAINED FOR INCORRECT MODEL ANALYSIS LEADING TO INCORRECT DIAGNOSIS

After alignment the incisors advance a significant amount and plan had to be changed to extraction

Accurate model measurement lead to accurate VTO

Incorrect model = incorrect Correct model = VTO Correct VTO

Therefore the moral of the story is to place the points for the incisors on a line bisecting the incisal edge but at the point in space representing the contact point. In this way you will tell the software the actual width of each incisor. This is very important to obtain accurate data that you will receive from DentalCad. Confirm the measurements before proceeding