Truly Invisible Braces: Truly Invisible Braces: The Story of Serial DiskingThe Story of Serial Disking

Dr Jabbarifar Dr Jabbarifar Associate ProfessorAssociate Professor

IsfahanUniversity School of Dentistry 2009IsfahanUniversity School of Dentistry 2009

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 .

Part 1 - Transition From PrimaryPart 1 - Transition From Primary to Permanent Teethto Permanent Teeth

Transition of molar relationships Transition of molar relationships Transition of Incisors Transition of Incisors Transition of Buccal Segment Transition of Buccal Segment

Leeway Space Leeway Space Late Mesial Shift Late Mesial Shift

Distal Mesial

Flush Terminal PlaneFlush Terminal Plane

Distal Mesial

Mesial Mesial StepStep

Distal Mesial

Disto Disto StepStep

Distal Mesial

Mesio Mesio StepStep

Incisor LiabilityIncisor Liability

Permanent incisors are Permanent incisors are larger than primary larger than primary incisorsincisors

This difference in size is This difference in size is termed "incisor liability“termed "incisor liability“

How does the body How does the body create enough room for create enough room for the larger, permanent the larger, permanent incisors?incisors?

Overcoming Incisor LiabilityOvercoming Incisor Liability

Interdental spacing of primary incisors Interdental spacing of primary incisors Intercanine arch width growth Intercanine arch width growth Labial positioning of the permanent incisors Labial positioning of the permanent incisors Favorable size ratio between the primary Favorable size ratio between the primary

and permanent incisorsand permanent incisors

Arch Length Prediction fromArch Length Prediction from Alignment of Primary TeethAlignment of Primary Teeth

Primary Alignment Permanent Outcome

Crowding Almost certain extraction

No spacing Possible extraction

Fair spacing Mild to Moderatecrowding

Good spacing No or mild crowding

Excess spacing No crowding/excess

Good SpacingGood Spacing

No Primary SpacingNo Primary Spacing

Fair SpacingFair Spacing

Leeway SpaceLeeway Space

Sum of (c-d-e) > (3-4-5) Sum of (c-d-e) > (3-4-5) This allows more space for 3-4-5 This allows more space for 3-4-5 This "leeway space" averages 1.7 mm. in This "leeway space" averages 1.7 mm. in

the mandibular buccal segment; 0.9 in the the mandibular buccal segment; 0.9 in the maxillary buccal segmentmaxillary buccal segment

““E” SpaceE” Space

Late Mesial ShiftLate Mesial Shift

Refers to mandibular permanent molar Refers to mandibular permanent molar moving mesially moving mesially

Good news - if permanent molars are ETE, Good news - if permanent molars are ETE, late mesial shift allows mandibular molar to late mesial shift allows mandibular molar to move into a Class I occlusion move into a Class I occlusion

Bad news - the above reduces arch lengthBad news - the above reduces arch length

FTP

Class IMolar moves into this space...

Late Mesial Shift (cont.)Late Mesial Shift (cont.)

Late Mesial Shift (cont.)Late Mesial Shift (cont.)

Part 2 Mixed Dentition AnalysisPart 2 Mixed Dentition Analysis

Purpose: predict amount of crowding after Purpose: predict amount of crowding after permanent teeth come in permanent teeth come in

Timing: mixed dentition Timing: mixed dentition Materials: Boley gauge Materials: Boley gauge Where: At the chairWhere: At the chair

4 Step Simplified MDA4 Step Simplified MDA

Basic Steps Basic Steps – Mentally align incisors Mentally align incisors

» In other words…. “how far over onto the primary In other words…. “how far over onto the primary cuspid will it take to make the incisors straight?” cuspid will it take to make the incisors straight?”

– Measure space left over for C, B1, B2 Measure space left over for C, B1, B2 – Predict size of C, B1, B2 Predict size of C, B1, B2 – Compare size vs. space for C, B1, B2 to Compare size vs. space for C, B1, B2 to

determine amount of crowdingdetermine amount of crowding

Step 1 MDA MethodologyStep 1 MDA Methodology

Measure mesial-distal diameter of the Measure mesial-distal diameter of the mandibular incisors, sum and divide by twomandibular incisors, sum and divide by two

Tooth Number Measurement

23 6.1

24 5.6

25 5.5

26 6.2

Sum 23.4

½ Sum 11.7

Step 1 ExampleStep 1 Example

Step 2 MDA MethodologyStep 2 MDA Methodology

Select a midline point Select a midline point Expand the Boley gauge to the amount Expand the Boley gauge to the amount

determined in Step 1 determined in Step 1 Mark the point on each primary cuspid from Mark the point on each primary cuspid from

the midline point the midline point This represents the space required for well This represents the space required for well

aligned incisors aligned incisors

11.7 mm 11.7 mm

Step 3 MDA MethodologyStep 3 MDA Methodology

Measure from the point on each cuspid Measure from the point on each cuspid (derived in Step 2) to the mesial of the first (derived in Step 2) to the mesial of the first permanent molarpermanent molar

This represents the space available for the This represents the space available for the permanent cuspid and bicuspids (C, B1, B2)permanent cuspid and bicuspids (C, B1, B2)

22.4 mm 22.7 mm

Step Left Side Right Side

½ Sum of lowerincisors 11.7 11.7

Space Available(C, B1, B2)

22.7 22.4

Tooth Size = 11.7 +10.5 (C, B1, B2)

Crowding/ quadrant

Sum of Crowding

Step 3 ExampleStep 3 Example

Step 4 MDA MethodologyStep 4 MDA Methodology

To the number derived in Step 1, add 10.5 To the number derived in Step 1, add 10.5 mm for the mandibular teethmm for the mandibular teeth

This represents the size of the permanent This represents the size of the permanent cuspid and bicuspids in each quadrantcuspid and bicuspids in each quadrant

Subtract the number determined in Step 4 Subtract the number determined in Step 4 (the predicted size of C, B1, B2) from the (the predicted size of C, B1, B2) from the number determined in Step 3 (the amount of number determined in Step 3 (the amount of space for C, B1, B2) for both sides of the archspace for C, B1, B2) for both sides of the arch

MDA MethodologyMDA Methodology

If the space available is less than the If the space available is less than the amount of tooth mass, a negative number amount of tooth mass, a negative number will resultwill result

This number is the predicted amount of This number is the predicted amount of crowdingcrowding

Step 4 ExampleStep 4 Example

Step Left Side Right Side

½ Sum of lowerincisors 11.7 11.7

Space Available(C, B1, B2)

22.7 22.4

Tooth Size = 11.7 +10.5 (C, B1, B2) 22.2 22.2

Crowding/ quadrant + 0.5 + 0.2

Sum of Crowding + 0.7

Allowance for Late Mesial ShiftAllowance for Late Mesial Shift

If permanent molars are end to end, If permanent molars are end to end, mandibular molar should move mesially to mandibular molar should move mesially to obtain Class I interdigitation.obtain Class I interdigitation.

This will decrease the arch length available This will decrease the arch length available for 3-4-5.for 3-4-5.

Figure 1.7 mm. per side with ETE Figure 1.7 mm. per side with ETE relationship.relationship.

MDA Procedure Maxillary ArchMDA Procedure Maxillary Arch

Mentally align the maxillary incisors as was done Mentally align the maxillary incisors as was done in the mandibular arch in the mandibular arch

Measure the space left over for the maxillary C, Measure the space left over for the maxillary C, B1, B2 B1, B2

Add 11.0 mm. to 1/2 the sum of the Add 11.0 mm. to 1/2 the sum of the MANDIBULAR INCISORS to predict the size of MANDIBULAR INCISORS to predict the size of the maxillary C, B1, B2the maxillary C, B1, B2

Subtract the predicted size from the space Subtract the predicted size from the space availableavailable

Part 3 Serial DiskingPart 3 Serial Disking

Result without treatment Result without treatment Description of Ideal Patient Description of Ideal Patient Description of Technique Description of Technique Steps in Serial DiskingSteps in Serial Disking

What Happens With No What Happens With No Intervention?Intervention?

Cuspid Cuspid Labial EruptionLabial EruptionNo anterior alignmentNo anterior alignment

1st Premolar Eruption1st Premolar EruptionDistal cuspid movement?Distal cuspid movement?

2nd Premolar Eruption2nd Premolar EruptionLate mesial shift of 1st molar Late mesial shift of 1st molar

Spaces close from posterior!!!

2nd Premolar Eruption2nd Premolar EruptionLate mesial shift of 1st molar Late mesial shift of 1st molar

Result Without DiskingResult Without Disking

Same anterior crowding Same anterior crowding Blocked out cuspids Blocked out cuspids Less arch length to work withLess arch length to work with

Ideal Patient for Serial DiskingIdeal Patient for Serial Disking

Class I molars and Class I molars and cuspids (Not FTP) cuspids (Not FTP)

Normal overbite Normal overbite and overjet and overjet

3 mm or less of 3 mm or less of anterior crowdinganterior crowding

Serial Disking TechniqueSerial Disking Technique

699, 169 carbide bur or tapered diamond 699, 169 carbide bur or tapered diamond Anesthetic considerations Anesthetic considerations

local local electronic electronic none none

Prepare mesial surface as stainless steel Prepare mesial surface as stainless steel crown prep crown prep

No ledges!…. Feather edge marginNo ledges!…. Feather edge margin

Serial Disking Steps:Serial Disking Steps:Mandibular ArchMandibular Arch

Lateral incisor eruption - disk mesial of Lateral incisor eruption - disk mesial of primary cuspids primary cuspids

Permanent cuspid eruption - disk mesial of Permanent cuspid eruption - disk mesial of either 1st or 2nd primary molareither 1st or 2nd primary molar

Mild Anterior CrowdingMild Anterior CrowdingDisk Primary CuspidsDisk Primary Cuspids

Mild Anterior CrowdingMild Anterior CrowdingDisk Primary CuspidsDisk Primary Cuspids

Cuspid Cuspid EruptionEruptionExtract 1st Primary Molar?Extract 1st Primary Molar?

Cuspid Cuspid EruptionEruptionExtract 1st Primary Molar?Extract 1st Primary Molar?

1st Premolar Eruption1st Premolar EruptionDisk 2nd Primary MolarDisk 2nd Primary Molar

1st Premolar Eruption1st Premolar EruptionDisk 2nd Primary MolarDisk 2nd Primary Molar

Disk 2nd Primary MolarDisk 2nd Primary Molar

Class I Molars

Class I Molars PreferredClass I Molars PreferredNo late mesial shift requiredNo late mesial shift required

2nd Premolar Eruption2nd Premolar Eruption

End to End MolarsEnd to End MolarsNo late mesial shiftNo late mesial shift

NEXT SLIDENEXT SLIDE

If You Can’t Disk Enough…If You Can’t Disk Enough…and <5 mm. Crowding...and <5 mm. Crowding...

Extract mandibular primary cuspids Extract mandibular primary cuspids Support with bilateral holding arch Support with bilateral holding arch Mandibular incisors will generally align Mandibular incisors will generally align Just because 5 mm. of crowding is Just because 5 mm. of crowding is

predicted does not mean it is an extraction predicted does not mean it is an extraction case! Why?case! Why?

Other Factors to ConsiderOther Factors to Consider

Tooth size prediction is at approximately 75 Tooth size prediction is at approximately 75 percentile percentile therefore….. Tendency is to overestimate therefore….. Tendency is to overestimate

crowding crowding

MDA does not take into account: MDA does not take into account: angulation of incisors angulation of incisors arch form arch form Curve of SpeeCurve of Spee

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