This document provides biographical information on Charles Henry Tweed and Lester Levern Merrifield, and summarizes the Tweed-Merrifield edgewise technique. It describes how Tweed formed a study club in 1941 that later founded the Charles H. Tweed Foundation. It outlines Tweed's contributions including objectives of treatment and emphasis on mandibular incisors. It then discusses Lester Merrifield and the sequential appliance placement, tooth movement, and mandibular anchorage preparation concepts he introduced. The document concludes by noting the enduring legacy of the Tweed-Merrifield edgewise appliance.

1. Tweed Merrifield Edgewise
Philosophy
(Part II)
Dr. Priyal Billaiya

2. “I have finished my work, it is as
perfect as I can make it”

3. Contents
• Charles Henry Tweed
• Lester Levern Merrifield
• Tweed Merrifield Edgewise
• References

4. Charles Henry
Tweed
(1895-1970)

8. Tweed decided to form a study club. His first "course" was held asa study
club meeting in 1941. Thirty-sixorthodontists met for instruction at the first
session. The group elected SamLewisto be its president. In attendance at the first
meeting were Robert Strang,CecilSteiner,BillDowns,HerbMargolis,PaulLewis,
andHaysNance.
It was at meeting in 1947 that the group proposed the founding of the
Charles H. Tweed Foundation for Orthodontic Research.
http://www.tweedortho.com

9. Tweed’s most notable
contributions
1. Four objectivesof orthodontic treatment—
• Aesthetics
• Health
• Function
• Stability
2.Positioningteethover basalbonewith emphasison the
mandibularincisors.
3.Extractionofteethfororthodontic correction
4.Clinicalapplicationof cephalometrics

10. 5. Diagnostic facialtriangle
6. Anchorage preparation as amajor step in
treatment.
7. Preorthodontic guidance program
Emphasized on stable anchorage as the fundamental factor
successful orthodontic treatment
Orthodntics.Current Principles and
Techniques.Graber.Vanarsdall.Vig

11. DRAWBACKS OF THE TWEED’S
PHILOSOPHY
• Heconcentrated on the antero-posterior & vertical trend of growth on the basis of
which he formulated the growthtrends.
• En masse tooth movementdid notnecessarily translate into precison and control.
• Mandibular anchorage was prepared with Class III elastics and with all
compensatory bends placed in the arch wire resulting in labially flared and
intruded mandibular incisors.

12. Charles Tweed, one of orthodontics’ most
brilliant innovators, kept his promise to his
mentor, Edward Hartley Angle. He devoted 42
years of his life, from 1928 until his death on
January 11, 1970, to the advancement of the
edgewise appliance.

13. Lester Levern
Merrifield
(1921 – 2000)

14. The Tweed Merrifield philosophy
• An anterior limitexists.
• A posteriorlimitexists.
• A laterallimitexists.
• A verticallimitexists

15. Diagnostic Concepts
• Dimension of dentition
• Dimensions of the lower face
• Total SpaceAnalysis
• Guidelines for space management to achieve
the following
1. maximum orthodontic correction
2. areas of disharmony

16. • Posterior bands and Anterior meshpads with single,
double width 0.022 brackets on the six anterior teeth.
• Intermediate single width brackets onthe premolar
bands.
• Twin brackets on the first molars.
• Heavy edgewise 0.022 tubes with mesial hooks on the
second molars.
• Lingual hooks and cleats arealso provided onmolars
and premolars
Bracket and tubes

17. Arch Wires Used
Rectangular
• .017 X .022
• .018 X .025
• .019 X .025
• .020 X .025
• .021 X .028

18. Treatment concepts
• Sequentialappliance placement
• Sequentialtooth movement
• Sequentialmandibularanchorage preparation.
• The organization of treatmentinto four orderly steps.

19. • Less traumaticto patient.
• Easier and less time consuming for the orthodontist
• Great efficiency in the action of arch wire
• Orthodontist can insert a wire of larger dimension
Sequential appliance
placement

20. • In a 1st premolar extractionpatient, second molars and 2nd
premolars are banded.
• Initially1st molars are leftunbanded.
• Incisors and caninesare bonded, anymalalignedanteriors
are not ligatedto the archwire.
• After the engagedteethrespond to forces ofarchwire and
auxiliaries, the maxillary and thenmandibular1st molars are
banded.
2nd Molar and
2nd PM
Anterior teeth
1st Molar max
then mand

21. • Teethmoved individually or in smallunits.
Advantages :
• More rapid tooth movement.
• More precision involved.
Sequential tooth movement

22. • UnlikeTweed who prepared mandibular anchorage using
Class III elasticsand place allthe compensation bends in the
archwire at one time.
• Merrifield’s technique allows mandibular anchorage to be
prepared quickly and easily,tipping only two teeth at a time.
• He used High Pull headgear.
• 10 teeth as “Anchorage unit” totip 2 teeth. Known as
Merrifield “10-2” system.
Sequential Mandibular Anchorage
Preperation
2nd molar
1st
molar
2nd PM

23. • Hallmarkof modern Tweed –
Merrifield system
“Controlled forces that place the
teeth in the most harmonious
relationship with their
environment”
• Resultant of all the forces should
be upward & forward for a
favourable skeletal change
Directional force concept

24. • No vertical control.
– Lower incisors – off
basal bone
• Result
– Lengthened face
– Gummy smike
– Incompetent lips
– Recessive chin

25. • T/t should be initiatedat a timewhen treatment
objectives can be most readily accomplished.
• This may mean
• interceptivetreatmentin themixed dentition
• selected extractions in mixeddentition
• or waitingfor second molar eruptionbefore
startingactive treatment.
Timing of treatment

26. • Denture preparation
• Denture correction
• Denture completion
• Denture recovery
Steps in Treatment

27. Denture Preparation
Objectives
•Leveling
•Individual toothmovementand rotation correction
•Retraction of maxillaryand mandibularcanines.
•Preparation of terminal molars for stress resistance.
•approximately 6 months.

28. • U- 0.017 x 0.022
• L- 0.018 x 0.025
• Lower 2nd Molar- effective distal tip 15°
• Upper 2nd molar- effective distal tip 5°
• Offset placed mesial to 2nd premolar is in each archwire, to prevent outward expansion
of canines
• J hook headgear
Denture Preparation

29. • 1sr Molars Molars are banded
• Canine retraction continued using powerchains & headgear

30. • Bracketed and levelled.
• Canines should beretracted.
• Rotations corrected.
• Mandibular terminal molars must betipped to terminal anchorage
position.

31. Denture correction
•Spaces are closed with maxillary and mandibular closing loop archwires.
•Mandibular archwire: 019 x 025 working archwire with 6.5 mm vertical loops distal
to the lateral incisor brackets.
•Maxillary archwire: 020 x 025 archwirewith 7.5 mm vertical loops distal to lateral
incisor brackets.
•Stop loops in both arches areimmediately distal to brackets of 1st molars.
•Stop loop in mandibular archwireincorporates a compensation to maintain the 15
degreeterminal molar tip

32. • U- 020X .025”maxilla
• L- 019 X .025”mandibular
• Vertical loops distal to lateral incisors
• Complete space closure in both the arches
Denture correction

33. At the endof space closure:-
• Curve of occlusion should bemaintained
• Mandibular arch should be completely level
• Dentition is ready for mand. anchorageprep
• Class I intercuspation of canines & premolars

34. Sequential Mandibular Anchorage
Preparation
Objectives
•Complete space closure in both the arches
•Sequential anchorage preparation in mandibular arch
•Enhancedcurve of occlusion in maxillaryarch
•Class I intercuspation of canines and premolars

35. Sequential Mandibular Anchorage
Preparation
•Archwire produces an activeforce on only two teeth while remaining
passive to the other teeth in the arch, which act as anchoring units.
•Referred to as10-2 anchorage system
•Anchorage preparation is supported by high pull headgear worn on
anterior vertical spurs, soldered distal to mandibular central incisors

36. Sequential Mandibular Anchorage
Preparation
• 10-2 anchorage system
• “Readout” – Orthodontist checks –2nd molar is tipped 15° distal
• 5° to 8°distal inclination of 1st molar (after 1 month)
• 5° distal tip 1 mm mesial to 2nd premolar bracket
• 5° distal inclination of 2nd premolar

37. Orthodontic correction of Class II
dental relation
•Maxillary archwire(020 x 025) with 7.5 mmclosedhelical bulbous loops bent
flush against 2nd molar tubes is fabricated.
•Ideal 1st, 2nd order bends and 7 degrees ofprogressive lingual crown torque in
molar segment.
•Gingival spurimmediately distal to 2nd premolar.
•Gingival high pull headgearhooks soldered distal to central incisors.
•Class II “lay on hooks” with gingival extension for anterior vertical elastics are
soldered distal to lateral incisors.

38. Orthodontic correction of Class II
dental relation
•8 ounceClass IIelastic
•For1month– tomoveMaxillary2nd Molardistally
•1 mm ofactivationbyopening ofclosed helical activationloop
•2nd molarClassI relationship

39. •First molar is distalized using a coil spring wound and compressed
mesial to it, as well as E chain from secondmolar.
•Class II elastics, anterior vertical elastics and high pull headgear(14
hours per day) are continued.
•After 1st molars havebeen distalized into overcorrectedClass I
relationship, second premolars followed by canines are moved distally.

40. •After overcorrection of maxillary posterior segment, an 020 x 025 maxillary
archwire with 7.5 mm closing loops distal to lateral incisors is fabricated.
•Closing loop is activated by oppning 1 mm pervisit Light Class II elastics – 4 to6
oz,anterior vertical elastics and high pull headgear areused

41. Denture completion
•Ideal 1st 2nd 3rd order –U / L 0215 x 028 resilient archwires.
•Lower archwire duplicates the previous wire used.
•Upper archwirehas artistic bends and hooks for highpull headgear, anterior
vertical elastics and Class II elastics.
•This stage can be regarded as a mini treatment of the malocclusion.

42. At the endof this stage the following objectives should beachieved:
•Alignment of incisors.
•Occlusionovertreated toClass I relation.
•Anterior teeth edge to edge.
•Maxillary canines and 2nd premolars locked tightly into Class I relation.
•Mesiobuccal cusp of upper1st molar occluding in mesiobuccal grooveoflower 1st
molar.
•Distal cusps of 1st molars as well as 2nd molars out of occlusion.
•All spaces from 2nd premolarforward closed tightly

43. Denture Recovery
•Orthodontist should not strive for ideal final result at the end of
treatment.
•This ideal result willoccur after all treatment mechanics are
discontinued anduninhibited functional and environmental
influences in the post treatment period stabilize and finalize the
position of the total dentition.
•Recovery phase - when allappliances are removed and retainers are
placed.

44. Transitional occlusion
• Concept of overtreatment
• 2nd molar disclusion at completion of treatment.
• Often referredto as Tweed occlusion, butproperly identified as transitional
occlusion.

45. Stable occlusion achieved

46. Levern Merrifield dedicated more than
45 years of his life to the growth and
development of another man’s
foundation...asking for nothing in
return.
American Journal of Orthodontics and Dentofacial
Orthopedics/April 2000

47. Theedgewise appliance has endured the test of time.
Angle was determined to use it to correct malocclusions while
preserving the ‘full complement of teeth’.
Hecollaborated with Charles H. Tweed, whoafter countless failures,
introduced the extraction of four first premolars and anchorage preparation to
produce facial balance.
It continued through many more years of modifications till Levern Merrifield
Sequential wire manipulation treatment

48. Since Angle through Tweedand to date with Levern Merrifield, the
Edgewise appliance has endured the test oftime. Although the Tweed Merrifield
appliance is the direct descendant of Angle’s original appliance in 1928, it is used
with a totally different philosophy of treatment.
Theintroduction of concepts of differential diagnosis, directional force
and sequential wire manipulation have madeit the most precise and efficient
instrument for the correction of major malocclusions, that exists in the world
today.
Conclusion

49. Thank You

50. • Technique and treatment with the edgewise appliance. Thurow, Raymond C.
• Treatment of malocclusion of the teeth. Angle EH.
• Orthodontics: Current Principles and Techniques. T.M. Graber,B.F. Swain.
• Contemporary Orthodontics, 5th Edition. William R. Proffit, Henry W. Fields & David M.
Sarver
• Orthodontics, Current Principles and Techniques.5th Edition. Graber, Vanarsdall & Vig.
• A Biographical Portrait of Edward Hartley Angle, the First Specialist in Orthodontics, Part
1.Sheldon Peck. (Angle Orthod. 2009;79:1021–1027.)
References

51. • Angle EH.Thelatestandbest in OrthodonticMechanism.Dental Cosmos1928;70:1143-56.
• Angle EH.Thelatestandbest in OrthodonticMechanism.Dental Cosmos1929;71:164-74.
• Angle EH.Thelatestandbest in OrthodonticMechanism.Dental Cosmos1929;72:260-70.
• Angle EH.Thelatestandbest in OrthodonticMechanism.Dental Cosmos1929;73:409-21
• Dr.EdwardH.Angle's Pin andTubeAppliance.CurrentOrthodonticLiterature.
• ClassificationofMalocclusion. EdwardH.Angle. The Dental Cosmos.
• History & EvolutionofEdgewiseOrthodontics.RjeevKumarMishra.

52. • Orthodonticsin 3 millennia.Chapter1:Antiquitytothemid-19century.NormanWahl.Am J
OrthodDentofacialOrthop2005;127:255-9).
• Orthodonticsin 3 millennia. Chapter2: Enteringthemodernera. NormanWahl.(Am J Orthod
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andearly20th-centuryappliances.NormanWahl.(Am J OrthodDentofacialOrthop
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• CharlesH. Tweed,1895-1970.JamesL. Vaden.Cookeville,Tenn.(Am J OrthodDentofacial
Orthop2015;147:S171-9)
• In Memoriam.LesterLevern Merrifield, Feb1, 1921toJan15, 2000. Am J OrthodDentOrthop
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• The profileline asanaidin critically evaluatingfacial esthetics.Levern Merrifield.(Thesis-ABO)