Anterior Analysis and Restorative System (AARS)
Case study continued ...
STEP TWO - Review the numbers and make a preliminary assessment.
Note that the UL2 is smaller than the UR2, and the UL2 Distal gap is almost 1mm smaller than the UR2 mesial gap. Because of this there is no way one can simply halve the gaps and add half to each tooth on either side without creating the UR1 and UR2 larger than the left hand side.
Let us check the numbers to see how significant this is:
If we simply halve the gap at the UR1-UR2, this would add 1.17mm to each surface
of the adjacent teeth. If we halve the gap at the midline, the UR1 would
then be 8.75mm + 1.2mm + 1.17mm = 11.12mm wide. Compare this to the UL1 which
would now be 8.72mm +1.2mm wide = 9.92mm. There is obviously a drastic disparity
between the widths of the central incisors, which would look very unfortunate.
We therefore need a way to calculate the desired widths of the anterior teeth,
given that:
- UR1 should equal UL1 width
- UR2 should equal UL2 width
- Lateral incisors should be 77% of the width of the central incisors (on average)
- Teeth should be the appropriate widths so there are no gaps left.
Section 4 of the Dentagauge instruction booklet shows how this is done.
STEP THREE - Quantify the length of the line of contact.
Add up all the tooth widths and gaps to get the total distance measured on the curve through the buccal side of the contact area. The sum of this addition is the length of the line of contact that is necessary for secondary assessment.
Future additions to the Dentagauge booklet will also have the ability to measure from the first pre-molar to the same tooth on the other side, so that the canines can be included in these calculations. This will be especially useful for those patients who have impacted or missing canines. If you have a case where the canine has substituted for the lateral incisor, and you are going to convert it to an incisor, then measure from the premolar as though it was the canine. - In this mannequin case the total width from canine to canine is 36.52mm.
Note that we have measured four teeth and three gaps to obtain this number. These three gaps were all in excess of 0.8mm, however if the gaps in a clinical case were less than 0.8mm, you could not use the Dentagauge 2 due to the finite amount of metal that must be employed to give the tips some rigidity. As an alternative you could either use the Raintree Essix feeler gauges, or you could put flowable composite into the gaps, and cut in an embrasure-like groove with a fine pointy diamond bur, and then measure to that groove. This effectively creates two wider teeth with the same total distance as two teeth plus a gap. The point is that we just need to measure the distance from canine to canine through the contact area of the teeth and it doesn't really matter how you do it as long as it's accurate.
STEP FOUR - Chart reference
Using a canine
to canine distance of 36.52mm we then refer to the table in section 4
of the Dentagauge booklet, read across from 36.5mm to columns 2+3 to
get the lateral incisor width of 8.1mm and the central incisor width
of 10.2mm.
This latter number is a lot more aesthetic than the previous simplistic proposed width of 11.12mm. The widths in the booklet have been calculated using the formula:
A=2B+0.77(2C) where A= Inter canine width, B= central incisor width, and C= lateral incisor width.
To save dentists and technicians doing messy calculations, the booklet chart contains the calculated, resultant incisor widths for common inter-canine distances in 0.1mm increments. If you wanted to include canines in your reconstruction, then you would use the formula P= 2a + 0.77(2b) + 0.89(2c) , where p= first premolar to first premolar distance through the buccal side of the contact areas, a = central incisor width, b = lateral incisor width and c = canine width. Although this formula looks a little daunting, all it says is that two lots of centrals of the same width, plus two lots of laterals 77% as wide as the centrals, plus two lots of canines 89% as wide, will equal the premolar to premolar width. All you need to do is determine P and the other numbers can be calculated.
To summarize so far, we have determined what widths the incisors should be. We now use this information in the construction phase.
Product Information:
Shopping
Communication:
