BORDERLINE CASES

CONTENTS

Introduction

History of extraction philosophy

Decision making aids

Effects of extraction and non extraction treatments

Non extraction treatments

Class III borderline

Conclusion

INTRODUCTION

Extraction of permanent

teeth is required to reach a

stable and functional

occlusion

When patient has good

facial esthetics that could be

disturbed by extractions

HISTORY OF EXTRACTIONS

DECISION-MAKING AIDS

1948, Downs

Acceptable ranges of ten

diagnostic variables

Earliest cephalometric

analyses

“Single readings are not so

important”

Vorhies and Adams

“difficulty of developing a

suitable mental picture.”

Organized data describing

acceptable ranges

Wigglegram

Efficient method to analyze

cephalometric measures

• Rody and Araujo

• Relationships of

dental, skeletal, and

facial cephalometric

measurements

• Extraction Decision-

Making Wigglegram

(EDMW)

Extraction decision-making wigglegram. J Clin Orthod 2002;36:510-519

DENTAL VARIABLES

Dental discrepancy

Curve of spee

Boltons discrepancy

Peck and peck analysis

Irregularity index

DENTAL DISCREPANCY

Carey 2.5mm to 5mm TASLD as borderline case

McNamara arbitrary borderlines of 3 to 6 mm

Luppanapornlarp and Johnston

1mm of crowding in either arch definitive non extraction

Definitive extraction therapy in maxillary and mandibular

arches was 5.8 and 7.3 mm, respectively

Proffit and Fields

Less than 4 mm ALD:

Extractions rare (only in incisor protrusion or posterior vertical

discrepancy)

ALD 5mm to 9 mm:

Extraction/non-extraction decision depends on characteristics

of patient

ALD 10mm or more:

Extractions always required

CURVE OF SPEE

1 mm of arch circumference for each millimeter of

curve of Spee

Recent studies suggest ratio1:3

• Woods- variable depending on type of mechanics used.

• Roth - 3 to 6 mm of curve of Spee mild

• Baldridge > 6 mm is severe

BOLTONS DISCREPANCY

4 mm limit to anterior reduction.

Extraction necessary discrepancy greater than this

Neff

Maxillary to mandibular cuspid-to-cuspid ratio -1.22

Anterior Bolton ratio of .772

PECK AND PECK ANALYSIS

An index between 88 -95 indicates good anatomical shape.

Index > 95 M-D width greater than buccolingual width.

Borderline patients with narrow lower incisors need extraction

IRREGULARITY INDEX-

LITTLE

Mandibular incisor alignment

Adding linear distances

between five adjacent

anatomical contact points

Perfectly aligned incisors-

zero.

Score > 6.5 millimeters

likelihood for extraction.

CEPHALOMETRIC VARIABLES

HORIZONTAL PLANES

FMA

SN-MP

PFH/AFH

FMIA

IMPA

1-A-POG LINE

UPPER AND LOWER CENTRAL INCISOR TO N-A AND

N-B LINE

HORIZONTAL PLANES

Highly divergent planes

favors extraction.

Parallel horizontal planes not

favor extraction.

INCISOR POSITION

Orthodontists may disagree which incisor is of greater

diagnostic value

Margolis IMPA 90+/-3 degrees in normal, balanced faces

Charles Tweed - “upright” and “vertical” lower incisors

85 and 95 degrees, according to ethnicity

Due to functional and esthetic impairment, an IMPA greater

than 96° is an indication for extraction

Frankfort mandibular

incisor angle (FMIA).

Norm 60-70°.

A value < 60°

indicates proclination

Value > 70° incisors

retroclined

McNamara

1 to 3 mms anterior to

(A-Pog)

Regardless of age

STEINER

Extraction more likely as

incisor positions and angles

exceed values Horizontal

planes

NB

NA

FACIAL VARIABLES

Profile of the patient

Lower lip to E –line

Lower lip to B-Line

Naso labial angle

Upper lip morphology

Midline Deviation

Lower lip to E –line

Age and sex

Standard deviation - 3mm

Lower lip to B-Line

2.5 ± 1.5mm anterior

EFFECT OF EXTRACTION ON LIPS

Ramos et al, for each 1 mm retraction upper lip retracts 0.75

mm

Talass et al 1/0.64

Massahud and Totti 1/0.5

Regarding lower lip, for 1 mm retraction, retracts 0.6 mm

Nasolabial angle

Burstone 73.8 degrees +/- 8

Recent studies range of 90

to 115 degrees.

Drobocky and Smith

Extraction of four bicuspids

increase nasolabial angle

5.2 degrees

Upper lip morphology

Thickness measured in two

different areas

Borderline patients with strained

lips

Incisors retracted without altering

soft tissue profile

Lip needs to reach normal form

before retraction

Lips would immediately follow

tooth movement in normal lips.

Effect of extraction on Soft tissue profile

L.A.Bravo, extractions of upper 1st premolars

3.4 mm backward movement of upper lip related to‘E’ line

3.7° increase in NLA

0.9 mm decrease in superior sulcus depth (Holdaway)

Extractions contraindicated

Nasolabial angle > 110°

Ls to Sn –Pog’ line < 3mm

Li to Sn-Pog’ line < 2mm

Ss to H line < 3mm

Li to H line < 0mm

Six Keys to Nonextraction Treatment

DAN COUNIHAN 2005 JCO

First Key: Leeway Space

7mm in lower arch and 5mm in upper arch

Lip bumper, lingual arch, or palatal bar before second

deciduous molars exfoliate

Second Key: Mesial Molar Rotations

Rotated upper molar occupy 12mm width, compared to

10mm for a properly oriented first molar

Third Key: Passive Uprighting

Constrictive forces of lips and cheeks removed

Studies shown 4mm increase in arch width

Achieved with lip bumpers or Fränkel appliances

Fourth Key: Active Uprighting

Fifth Key: Distal Movement

Sixth Key: Skeletal Modification

Borderline Class III Malocclusion

KERR ET.AL. ( BJO 1992)

Establish cephalometric yardsticks

Surgery performed

ANB angle < -4°

M/M ratio of 0.84

Inclination lower incisors 83°

Holdaway angle of 3.5°

STELLZIG-EISENHAUER

Formula developed

On basis on the four variables:

Wits appraisal

Length of anterior cranial base

M/M ratio

Lower gonial angle

Ind Score= -1.805+0.209Wits+0.044SN+5.689M/M ratio

0.056Go

Cr Score = - .023

< Orthodontic- orthognathic therapy

> Orthodontic therapy

CONCLUSION

Experience plays significant role

Any decision regarding need for extraction not only dependent

on presence or absence of space

Other issues

Proper malocclusion correction

Improvement of facial aesthetics

Result stability