1. Truly Invisible Braces: The Story of Serial Disking
Dr Jabbarifar
Associate Professor
IsfahanUniversity School of Dentistry 2009

2. objective
part 1
Discuss the transition of the primery dentition to the permanent dentition.
part 2
Review a simplified Mixed Dention
Analysis procedure.
part 3
Discuss indications and procedures for
Serial disking .

3. Part 1 - Transition From Primary to Permanent Teeth
Transition of molar relationships
Transition of Incisors
Transition of Buccal Segment
Leeway Space
Late Mesial Shift

4. Flush Terminal Plane
Distal
Mesial

5. Mesial Step
Distal
Mesial

6. Disto Step
Distal
Mesial

7. Mesio Step
Distal
Mesial

8. Incisor Liability Permanent incisors are larger than primary incisors
This difference in size is termed "incisor liability“
How does the body create enough room for the larger, permanent incisors?

9. Overcoming Incisor Liability
Interdental spacing of primary incisors
Intercanine arch width growth
Labial positioning of the permanent incisors
Favorable size ratio between the primary and permanent incisors

10. Arch Length Prediction from Alignment of Primary Teeth

11. Good Spacing

12. No Primary Spacing

13. Fair Spacing

14. Leeway Space Sum of (c-d-e) > (3-4-5)
This allows more space for 3-4-5
This "leeway space" averages 1.7 mm. in the mandibular buccal segment; 0.9 in the maxillary buccal segment

15. “E” Space

16. Late Mesial Shift Refers to mandibular permanent molar moving mesially
Good news - if permanent molars are ETE, late mesial shift allows mandibular molar to move into a Class I occlusion
Bad news - the above reduces arch length

17. Late Mesial Shift (cont.)
FTP
Molar moves into
this space...
Class I

18. Late Mesial Shift (cont.)

19. Part 2 Mixed Dentition Analysis
Purpose: predict amount of crowding after permanent teeth come in
Timing: mixed dentition
Materials: Boley gauge
Where: At the chair

20. 4 Step Simplified MDA Basic Steps Mentally align incisors
In other words…. “how far over onto the primary cuspid will it take to make the incisors straight?”
Measure space left over for C, B1, B2
Predict size of C, B1, B2
Compare size vs. space for C, B1, B2 to determine amount of crowding

21. Step 1 MDA Methodology
Measure mesial-distal diameter of the mandibular incisors, sum and divide by two

23. Step 1 Example

24. Step 2 MDA Methodology Select a midline point
Expand the Boley gauge to the amount determined in Step 1
Mark the point on each primary cuspid from the midline point
This represents the space required for well aligned incisors

25. 11.7 mm
11.7 mm

26. Step 3 MDA Methodology
Measure from the point on each cuspid (derived in Step 2) to the mesial of the first permanent molar
This represents the space available for the permanent cuspid and bicuspids (C, B1, B2)

27. 22.4 mm
22.7 mm

28. Step 3 Example

29. Step 4 MDA Methodology
To the number derived in Step 1, add 10.5 mm for the mandibular teeth
This represents the size of the permanent cuspid and bicuspids in each quadrant
Subtract the number determined in Step 4 (the predicted size of C, B1, B2) from the number determined in Step 3 (the amount of space for C, B1, B2) for both sides of the arch

30. MDA Methodology
If the space available is less than the amount of tooth mass, a negative number will result
This number is the predicted amount of crowding

31. Step 4 Example

32. Allowance for Late Mesial Shift
If permanent molars are end to end, mandibular molar should move mesially to obtain Class I interdigitation.
This will decrease the arch length available for
Figure 1.7 mm. per side with ETE relationship.

33. MDA Procedure Maxillary Arch
Mentally align the maxillary incisors as was done in the mandibular arch
Measure the space left over for the maxillary C, B1, B2
Add 11.0 mm. to 1/2 the sum of the MANDIBULAR INCISORS to predict the size of the maxillary C, B1, B2
Subtract the predicted size from the space available

34. Part 3 Serial Disking Result without treatment
Description of Ideal Patient
Description of Technique
Steps in Serial Disking

35. What Happens With No Intervention?

36. Cuspid Labial Eruption No anterior alignment

37. 1st Premolar Eruption Distal cuspid movement?

38. 2nd Premolar Eruption Late mesial shift of 1st molar

39. Spaces close from posterior!!!
2nd Premolar Eruption Late mesial shift of 1st molar
Spaces close from posterior!!!

40. Result Without Disking
Same anterior crowding
Blocked out cuspids
Less arch length to work with

41. Ideal Patient for Serial Disking
Class I molars and cuspids (Not FTP)
Normal overbite and overjet
3 mm or less of anterior crowding

43. Serial Disking Technique
699, 169 carbide bur or tapered diamond
Anesthetic considerations
local
electronic
none
Prepare mesial surface as stainless steel crown prep
No ledges!…. Feather edge margin

44. Serial Disking Steps: Mandibular Arch
Lateral incisor eruption - disk mesial of primary cuspids
Permanent cuspid eruption - disk mesial of either 1st or 2nd primary molar

45. Mild Anterior Crowding Disk Primary Cuspids

46. Mild Anterior Crowding Disk Primary Cuspids

52. Cuspid Eruption Extract 1st Primary Molar?

53. Cuspid Eruption Extract 1st Primary Molar?

54. 1st Premolar Eruption Disk 2nd Primary Molar

55. 1st Premolar Eruption Disk 2nd Primary Molar

61. Disk 2nd Primary Molar

67. Class I Molars Preferred No late mesial shift required

68. 2nd Premolar Eruption

69. End to End Molars No late mesial shift

70. If You Can’t Disk Enough… and <5 mm. Crowding...
Extract mandibular primary cuspids
Support with bilateral holding arch
Mandibular incisors will generally align
Just because 5 mm. of crowding is predicted does not mean it is an extraction case! Why?
NEXT SLIDE

71. Other Factors to Consider
Tooth size prediction is at approximately 75 percentile
therefore….. Tendency is to overestimate crowding
MDA does not take into account:
angulation of incisors
arch form
Curve of Spee

74. Visit Us on the Web!
Creighton University Creighton School of Dentistry ASDC Web site