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PRINCIPLES AND CONCEPT OF
ANDREW’S PREADJUSTED
EDGEWISE APPLIANCE
www.indiandentalacademy.com
INTRODUCTION
For over 100 years orthodontists have always followed a
classic guideline given by Angle in diagnosis - The m...
So, Andrew decided to collect data about what was
significantly characteristic in models which needed no
orthodontic treat...
SIX KEYS TO OPTIMAL OCCLUSION
Key 1 : Interarch relationship
This key consists of seven points.
1. The mesiobuccal cusp of...
4. The buccal cusps of the maxillary premolars have a cusp-
embrasure relationship with the mandibular premolars.
5. The l...
As seen in this diagram, closer the
distobuccal cusp of the upper first
molar occluded with mesial
surface of the mesiobuc...
Key 2 : CROWN ANGULATION
The Mesiodistal tip of the crown.
The degree of crown tip is
the angle between the long axis of
t...
Key 3 : CROWN INCLINATION
Labiolingual or Buccolingual inclination.
Crown inclination is determined from the mesial or dis...
When the upper anterior crown
are insufficiently inclined, upper
posterior crowns are forward of
their normal position.
Bu...
The pattern of upper posterior
crown inclination was consistent
in non orthodontic normal
models. A minus crown
inclinatio...
Key 4 : ROTATIONS
The fourth key to normal
occlusion is that the teeth
should be free of rotations,
because if molars rota...
Key 6 : OCCLUSAL PLANE
The planes of occlusion found in
the non orthodontic models
ranged from flat to slight curve of
spe...
1. Andrews Plane
The surface or a plane on which the
mid transverse plane of every crown
in an arch will fall when teeth a...
3. Facial Axis of the Clinical
Crown [FACC]
For all the teeth except molars, the
most prominent portion of the central
lob...
5. Midsagittal Plane
An imaginary line that separates the crown mesio-distally at the
facial axis of the clinical crown (F...
MEASUREMENTS
After determining the 6 keys of occlusions Andrew made
certain measurements in the non orthodontic modles whi...
• Bracket area
• Vertical contour
• Angulation
• Inclination
• Maxillary molar
• offset
• Horizontal contour
• Facial prom...
The average findings for the maxillary teeth are:
ANGULATION
INCLINATION
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The average findings for the maxillary teeth are:
CROWN PROMINENCE
MAXILLARY MOLAR OFFSET
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The average findings for the maxillary teeth are:
ANGULATION
INCLINATION
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No offset was needed for mandibular molar
because the middle & mesiobuccal cusps are
equal in prominence. The curve of spe...
After making the measurements, Andrew compared the 120 non
orthodontic models with the treated 1150 models.
ie best in nat...
KEY III – Inclination
Inter incisal FACC – In optimal – more than 180 degrees in 78%
In treated - Less than 180 degrees in...
These evidence showed that only few post treatment results met
the six key standards. So a quarter century of research don...
NORMALITY – ABNORMALITY & OPTIMALITY
In this point of time Andrew spoke about what exactly
Normality, Abnormality & Optima...
So both the naturally optimal & the normal malocclusion
fall under a same category where they are differentiated only
thro...
SHORTCOMINGS OF EDGEWISE APPLIANCE
The edgewise appliance designed by Angle is “Non
programmed” because of the bilaterally...
1. Perpendicular bases :
The base of the non –
programmed bracket is
perpendicular to the stem. This
feature can acuse pro...
Each crown in an arch has
it’s own optimal amount of
inclination. Therefore brackets
having bases that are perpendicular
t...
2. Bases not contoured
occlusogingivally
Occluso gingivally the bracket is
flat but the facial surface of a
crown is curve...
3. Slots not angulated
The brackets slots of the edgewise
brackets are non angulated.
When the vertical components of
the ...
4.Stems of equal prominence
Distance between bracket base &
center of slot is same in each
brackets.
Therefore when the br...
5. Maxillary molar offset not
built in
Since the maxillary molar offset is
not built in, the midsagittal plane
of the slot...
Non programmed brackets are simple in design, easily
manufactured and inexpensive. Unfortunately they are difficult
to use...
FIRST-ORDER WIRE BENDING FOR FACIAL
PROMINENCE
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SECOND-ORDER WIRE BENDING FOR ANGULATION
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SECOND-ORDER WIRE BENDING FOR
OCCLUSO-GINGIVAL SLOT POSITION
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THIRD-ORDER WIRE BENDING FOR
INCLINATION
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To achieve optimal tooth position and to avoid mesiodistal
“rocking” picture the teeth in both arches optimally positioned...
When the brackets are sited on a full complement of
optimally positioned teeth, the final ‘IDEAL’ archwire will
require 76...
2. SECONDARY WIRE BENDS
Secondary wire bends are any bends for tooth guidance
that are not primary bends. Secondary bends ...
INDIVIDUALIZED BRACKETS-BRACKET
SITING-SLOT SITING
1927 Angle has suggested angulating the entire bracket.
Holdaway in 195...
1.Individualized and customized brackets
Individualized brackets : It is used for both shape and optimal
position are simi...
2.Bracket siting
A suitable bracket site has three criteria :
• Bracket located there will not interfere with either gingi...
The site that meets these
requirements is the area in
immediate proximity to
Crown’s FA Point. The FA
point always falls o...
Crown prominence from
embrasure line differ from
each tooth type, with
prominence in molar being
the maximum.
3.Slot sitin...
In this diagram, the distant
between the embrasure line [a]
& the slot point [c] is equal
from incisors to molar. But
sinc...
FULLY PROGRAMMED STANDARD BRACKETS
The standard brackets are the one which are designed to guide
the tooth without any wir...
1. SLOT SITING FEATURES
There are totally 8 slot siting features for the standard brackets :
Feature 1:
Mid transverse pla...
Feature 3:
Each bracket’s inclined base
must be contoured occluso
gingivally to match the
curvature of the crown. These
3 ...
Feature 4 :
Mid sagittal plane of slot, stem
& crown must be the same.
Feature 5:
Plane of the bracket base at it’s
base p...
Feature 6 :
The base of the bracket must
be contoured to match the
mesio distal radius of the area
of the crown it is desi...
Feature 8 :
Within an arch, all slot points must have the same distance
between them & the crown’s embrasure line. This fa...
2. CONVENIENCE FEATURES
Convenience features are the designs incorporated into the
brackets that facilitates use by orthod...
3. AUXILIARY FEATURES
Contribute to the biological aspect of treatment, but not involved
in slot siting. E.g. – Power arms...
• For the maxillary central incisor, an unpublished study by Andrews
(1968) of 100 cephalograms showed an average differen...
Class I interjaw conditions the inclination of
the maxillary incisor must be approximately
25°; this, minus 18°, converts ...
In the measurement study, the maxillary lateral incisor’s
inclination was found to average 4° less than that of the maxill...
The maxillary
lateral bracket that
is the mate for the
2° central incisor
bracket in class II
base inclination.
Maxillary ...
The maxillary
lateral bracket that
is the mate for the
12° central incisor
bracket in class III
base inclination.
Maxillar...
These are the following prescriptions for fully programmed
standard brackets :
MAXILLARY BRACKETS
Central Incisors 3 types...
Lateral Incisors : 3 types
Class II -Angulation : 9 degrees
Inclination : -2 degrees
Prominence : 2.25 mm
Class I - Inclin...
Canine
Angulation : 11 degrees
Inclination : -7 degrees
Prominence : 1.4 mm
First & Second premolars
Angulation : 2 degree...
Central & Lateral Incisors
Class II -Angulation : 2 degrees
Inclination : 4 degrees
Prominence : 2.3 mm
Class I - Inclinat...
Canine
Angulation : 5 degrees
Inclination : -11 degrees
Prominence : 1.6 mm
Premolars
First premolar :
Angulation : 5 degr...
Molars
First molar :
Angulation : 2 degrees
Inclination : -30 degrees
Prominence : 1mm
Second molar :
Inclination : -35 de...
FULLY PROGRAMMED TRANSLATION BRACKETS
Translation Problems
Translation is defined as “uniform motion of a body in a
straig...
1. The bracket is occlusal to the
tooth’s center of resistance, so
when a mesial or distal force is
applied, the tooth, in...
Translation Solution
There are two fundamental methods of moving a tooth
mesially or distally, and they involve different ...
The fully programmed translation brackets have all the
qualities of standard brackets plus a Power arm and three
additiona...
• When a mesial force is
applied, the resultant Rotation
movement M is counteracted
by counter moment CM
produced by rotat...
3 categories of translation brackets are there for counter
rotation
• Minimum - 2 degree slot rotation
• Medium - 4 degree...
Various of Types of Counter Rotation
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2. Counter Mesiodistal tip
This is the slot feature that counters mesial or distal tipping
during translation and overcorr...
• Even when power arm is
introduced, there is imbalance
since length of power arm is
shorter than the distance between
cen...
3. Counter Buccolingual tip:
This slot siting feature is only for
maxillary molars that counteracts
Buccolingual tip durin...
MAXILLARY BRACKETS
Maxillary Canine
Medium translation
Angulation : 14 (11 + counter
M-D tip of 3)
Rotation : 4
Inclinatio...
Maxillary First Premolar
Medium translation
Angulation : 5 (2 + counter
M-D tip is 4)
Rotation : 4
Inclination : -7
www.in...
Maxillary Second premolar
Minimum translation
Angulation : 0 (2 + counter
M-D tip of -2)
Rotation : 2
Inclination : -7
Med...
Maxillary First & Second Molars
Minimum translation
Angulation : 3 (5 + counter
M-D tip of -2)
Rotation : 12 (10 + counter...
Mandibular canine
Medium translation
Angulation : 8 (5 + counter
M-D tip of 3)
Rotation : 4 (0 + Counter
rotation 4)
Incli...
Second Premolar
Minimum translation
Angulation : 0 (2 + counter
M-D tip of -2)
Rotation : 2 (0 + 2)
Inclination : -22
Medi...
Mandibular First Molar
Minimum translation
Angulation : 0 (2 + counter
M-D tip of -2)
Rotation : 2
Inclination : -30
Mediu...
Mandibular Second Molar
Minimum translation
Angulation : 0 (2 + counter
M-D tip of -2)
Rotation : 2
Inclination : -35
Medi...
FULLY PROGRAMMED APPLIANCE PRESCRIPTION
Selecting a most suitable Straightwire brackets for each
tooth in an arch begins w...
www.indiandentalacademy.com
To make these distinctions, first measure the discrepancy
between the size of the teeth & space available for them within ...
TYPE SPACED
3 Subtypes – All non extraction
Subtype 0 to 4 mm
Advance molars & premolars
0 to 2
mm per side
Subtype 5 to 8...
TYPE CLASSIC (zero space)
1 Subtype – Non extraction
1 Alternative – extraction
Subtype – Non extraction
Some tooth reposi...
TYPE CROWDED
6 extractions & 1 non-extraction
Subtype 0 to 6 – non extraction
Molars, premolars & canines
Tipped distally ...
Subtype – 9 to 10 mm
Extraction of first premolars
Subtype – 11 to 13mm
Extraction of first premolars
www.indiandentalacad...
Subtype 14 mm
Extraction of first premolars
Retract only the canines
Alternate 14 mm
Only for Maxillary arch.
When class I...
Even though this series of brackets given by Andrew
were used initially, now they are not used because of the
following di...
CONCLUSION
Straight wire appliance is not a computer software which
can be downloaded from the bracket case and executed i...
For more details please visit
www.indiandentalacademy.com
www.indiandentalacademy.com
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Principles and concept of andrew’s preadjusted edgewise appliance /certified fixed orthodontic courses by Indian dental academy

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Principles and concept of andrew’s preadjusted edgewise appliance /certified fixed orthodontic courses by Indian dental academy

  1. 1. PRINCIPLES AND CONCEPT OF ANDREW’S PREADJUSTED EDGEWISE APPLIANCE www.indiandentalacademy.com
  2. 2. INTRODUCTION For over 100 years orthodontists have always followed a classic guideline given by Angle in diagnosis - The mesiobuccal cusp of the upper first permanent molar should rest on mesiobuccal groove of the lower first permanent molar. Even though it was genuine & accurate, how sufficient it was? It has always remained a question over these years. Even though classification have been made about malocclusion, no one gave the criteria for ideal occlusion. In the early 60s Lawrence.F.Andrews noted that too many post treated models had obvious inadequacies, despite the acceptable molar relationship as described by Angle. Recognizing conditions in treated cases that were obviously less than ideal was not difficult, but neither it was sufficient.www.indiandentalacademy.com
  3. 3. So, Andrew decided to collect data about what was significantly characteristic in models which needed no orthodontic treatment. The concept was “ if one knew what constituted right, consistently & methodically identify & quantify what was wrong”. So 120 non orthodontic models were acquired from 1960 to 1964. Models selected were of the patients teeth which - • Had never had any orthodontic treatment • Pleasing in appearance • Had a bite that looked generally correct • Would not benefit from orthodontic treatment These 120 models were compared with 1150 treated cases which he collected from orthodontist all over USA. So the best in treatment results [1150 treated cases] & best in nature[120 non orthodontic models] revealed the differences between the right & wrong, which gave birth to SIX KEYS OF OPTIMAL OCCLUSION.www.indiandentalacademy.com
  4. 4. SIX KEYS TO OPTIMAL OCCLUSION Key 1 : Interarch relationship This key consists of seven points. 1. The mesiobuccal cusp of permanent maxillary first molar occludes in the groove between the mesial and middle buccal cusps of the permanent mandibular first molar as explained by Angle. 2. The distal marginal ridge of the maxillary first molar occludes with the mesial marginal ridge of the mandibular second molar. 3. The mesiolingual cusp of the maxillary first molar occludes in the central fossa of the mandibular first molar.www.indiandentalacademy.com
  5. 5. 4. The buccal cusps of the maxillary premolars have a cusp- embrasure relationship with the mandibular premolars. 5. The lingual cusps of the maxillary premolars have a cusp- fossa relationship with the mandibular premolars. 6. The maxillary canine has a cusp-embrasure relationship with the mandibular canine and first premolar. The tip of its cusp is slightly mesial to the embrasure. 7. The maxillary incisors overlap the mandibular incisors, and the midlines of the arches match. www.indiandentalacademy.com
  6. 6. As seen in this diagram, closer the distobuccal cusp of the upper first molar occluded with mesial surface of the mesiobuccal cusp of the lower second molar the better the opportunity for normal occlusion . MOLAR RELATIONSHIP When Angle described about molar relationship he stated that The mesiobuccal cusp of the upper first permanent molar should rest on mesiobuccal groove of the lower first permanent molar. But non orthodontic models consistently demonstrated that “Distal surface of the distobuccal cusp of the upper first molar occluded with the mesial surface of the mesiobuccal cusp of the lower second molar”. www.indiandentalacademy.com
  7. 7. Key 2 : CROWN ANGULATION The Mesiodistal tip of the crown. The degree of crown tip is the angle between the long axis of the crown & a line drawn 90 degrees from occlusal plane. “Positive” when gingival portion is distal to incisal portion. “Negative” when gingival portion is mesial to incisal portion. All the non orthodontic models had a distal inclination of the gingival portion of the crown. ie Positive readingwww.indiandentalacademy.com
  8. 8. Key 3 : CROWN INCLINATION Labiolingual or Buccolingual inclination. Crown inclination is determined from the mesial or distal perspective. Angle formed by a line 90 degree to occlusal plane & a line tangent to bracket site. “Positive” when gingival portion of tangent line is lingual. “Negative” when gingival portion of tangent line is labial or buccal. www.indiandentalacademy.com
  9. 9. When the upper anterior crown are insufficiently inclined, upper posterior crowns are forward of their normal position. But when the anterior crowns are properly inclined, one can see how the posterior teeth are encouraged into their normal positions. www.indiandentalacademy.com
  10. 10. The pattern of upper posterior crown inclination was consistent in non orthodontic normal models. A minus crown inclination existed in each crown from upper canine through the upper second premolar. A slightly more negative crown inclination existed in upper 1st & 2nd molar. In the lower teeth, a progressively greater minus crown inclination existed from lower canines through the lower second molars.www.indiandentalacademy.com
  11. 11. Key 4 : ROTATIONS The fourth key to normal occlusion is that the teeth should be free of rotations, because if molars rotated, would occupy more space than normal. So it will create a situation unreceptive to normal occlusion. Key 5 : TIGHT CONTACTS The fifth key is that the contact points should be tight, ie no spaces. Without exceptions contact points in the non orthodontic models were tight.www.indiandentalacademy.com
  12. 12. Key 6 : OCCLUSAL PLANE The planes of occlusion found in the non orthodontic models ranged from flat to slight curve of spee. Andrew believes that a flat plane should be treatment goal as a form of overtreatment since there is natural tendency for the curve of spee to deepen with time.www.indiandentalacademy.com
  13. 13. 1. Andrews Plane The surface or a plane on which the mid transverse plane of every crown in an arch will fall when teeth are optimally positioned. 2. Clinical crown The amount of visible crown in the late mixed dentition with gingiva that is healthy and not recessed. Orban defined clinical crown as anatomical crown minus 1.8 mm. Before we go further, we will see some of the landmarks given by Andrew which would help more to understand further details. www.indiandentalacademy.com
  14. 14. 3. Facial Axis of the Clinical Crown [FACC] For all the teeth except molars, the most prominent portion of the central lobe on each crown’s facial surface. For molars, buccal groove that separates the 2 large facial cusps. 4. FA Point The point on the facial surface that separates the gingival half of the clinical crown from the occlusal half.www.indiandentalacademy.com
  15. 15. 5. Midsagittal Plane An imaginary line that separates the crown mesio-distally at the facial axis of the clinical crown (FACC). 6. Mid Transverse Plane An imaginary line that separates occlusal half the crown from the gingival half of the crown. www.indiandentalacademy.com
  16. 16. MEASUREMENTS After determining the 6 keys of occlusions Andrew made certain measurements in the non orthodontic modles which helped in the development of a fully programmed appliance. The purpose was to learn the extent to which positions & in certain ways shape were constant within each tooth type & how relative size was consistent within an arch. The measurement were made with Protractor with adjustable readout arms, Boley gauge & template of circles. The measurements made are: www.indiandentalacademy.com
  17. 17. • Bracket area • Vertical contour • Angulation • Inclination • Maxillary molar • offset • Horizontal contour • Facial prominence •Curve of spee www.indiandentalacademy.com
  18. 18. The average findings for the maxillary teeth are: ANGULATION INCLINATION www.indiandentalacademy.com
  19. 19. The average findings for the maxillary teeth are: CROWN PROMINENCE MAXILLARY MOLAR OFFSET www.indiandentalacademy.com
  20. 20. The average findings for the maxillary teeth are: ANGULATION INCLINATION www.indiandentalacademy.com
  21. 21. No offset was needed for mandibular molar because the middle & mesiobuccal cusps are equal in prominence. The curve of spee ranged from flat to 2.5 mm. CROWN PROMINENCE This study revealed consistencies in the position, morphology & relative facial prominence for the crown of each tooth type with an arch except for incisor inclination. The differences in the incisor inclination were attributed to interjaw disharmony. Thus special considerations must be given in the bracket design to correlate the inclination of incisors with interjaw relationship.www.indiandentalacademy.com
  22. 22. After making the measurements, Andrew compared the 120 non orthodontic models with the treated 1150 models. ie best in nature Vs best in treatment. Comparison were made particularly in relation to the 6 keys of optimal occlusion:- KEY I – Inter-arch relationship In 80% of the treated models, Distal marginal ridge of maxillary molar I molar did not occlude with mesial marginal ridge of mandibular II molar. Whereas in the non orthodontic models, that relationship was optimal. KEY II – Angulation In 91% of the treated models, The crowns had one or more teeth whose angulation differed from those of optimal sample.www.indiandentalacademy.com
  23. 23. KEY III – Inclination Inter incisal FACC – In optimal – more than 180 degrees in 78% In treated - Less than 180 degrees in 81.5% KEY IV – Rotation Rotations were evident in 67% of post treated cases. KEY V – Tight contacts Spaces were seen in 43% of post treatment casts. KEY VI – Curve of spee More than 2.5 mm in 56% of post treatment casts.www.indiandentalacademy.com
  24. 24. These evidence showed that only few post treatment results met the six key standards. So a quarter century of research done by Andrew, devoted to naturally optimal & treated occlusions has yielded not only the six keys, but also several principles fundamental to the concept of fully programmed appliance. They are:- • Each normal tooth type is similar in shape from one individual to another. • The size of normal crowns within a dentition has no effect on their optimal angulation, inclination or prominence of their facial surface. • Most individuals have normal teeth regardless of whether their occlusion is flawed or optimal. • Jaws must be normal & correctly related to permit the teeth to be correctly positioned & related. • Dentitions with normal teeth and in jaws that are or can be correctly related can be brought to optimal occlusal standards.www.indiandentalacademy.com
  25. 25. NORMALITY – ABNORMALITY & OPTIMALITY In this point of time Andrew spoke about what exactly Normality, Abnormality & Optimality means. Abnormality : Individuals with abnormal jaws & teeth fall into this category. For example cleft palate, peg laterals, etc. treatment for this group always needs a multi disciplinary approach. ie only orthodontists can’t solve the problem. Naturally Optimal : Group with normal teeth & jaws who require no orthodontic treatment. 120 non orthodontic models can be included in this group. Normal malocclusion: Group with malocclusion which can be treated to Optimal standards.www.indiandentalacademy.com
  26. 26. So both the naturally optimal & the normal malocclusion fall under a same category where they are differentiated only through 6 keys of optimal occlusion. So when the normal tooth types are similar in shape & require similar positions for occlusions to be optimal, why should a clinician spend so much of their lives making virtually identical bends in identical wires each time striving to estimate the requirement for effective tooth guidance? It seemed feasible to design an appliance that could be readily applied to normal teeth with normal malocclusions & direct them to optimal goals. When correctly sited, the brackets would be designed to provide the guidance needed with few wire bends. The development of this appliance resulted partly from the 6 keys of optimal occlusion and partly from detailed analysis of limitations of edgewise appliance. www.indiandentalacademy.com
  27. 27. SHORTCOMINGS OF EDGEWISE APPLIANCE The edgewise appliance designed by Angle is “Non programmed” because of the bilaterally symmetric design. If located on the FA point & the FACC & used with unbent archwire, the brackets would cause the Inclination of the facial plane of each crown to be at 90 degrees to occlusal plane, the occluso gingival positions of each crown to be irregular, all crowns to have equal facial prominence & angulation of the FACC of each crown to be at 90 degree to the occlusal plane. The major shortcomings of edgewise appliance are: • Bracket bases are perpendicular to bracket stem • Bracket bases are not contoured occlusogingivally • Slots are not angulated • Bracket stems are of equal faciolingual thickness • Maxillary molar offset is not built in. • Bracket siting techniques are unsatisfactory. www.indiandentalacademy.com
  28. 28. 1. Perpendicular bases : The base of the non – programmed bracket is perpendicular to the stem. This feature can acuse problems for the slot inclination & occluso gingival position. www.indiandentalacademy.com
  29. 29. Each crown in an arch has it’s own optimal amount of inclination. Therefore brackets having bases that are perpendicular to their stem & sited base point of each crown, will target their slots to that many different inclination & occlusogingival levels. even when the base point of the bracket is sited on the FA point of the crowns, occlusogingivally the slots are poorly aligned relative to Andrew’s plane. Now as seen in this diagram, the effect when the brackets are aligned with unbent archwire. Dotted lines represents the required ideal position. www.indiandentalacademy.com
  30. 30. 2. Bases not contoured occlusogingivally Occluso gingivally the bracket is flat but the facial surface of a crown is curved. So when such a bracket is being attached to the crown, it can unintentionally be rocked occlusally or gingivally. So there will be irregular slot siting in each arch caused by vertically flat based brackets. Only a part of the bracket will be touching the crown. This diagram shows the effect of the irregularly placed brackets. The dotted line indicates the optimal tooth position required.www.indiandentalacademy.com
  31. 31. 3. Slots not angulated The brackets slots of the edgewise brackets are non angulated. When the vertical components of the brackets are sited parallel to FACC & base point sited at FA point, the angle of the slot vary to many different angulation This diagram shows the effects when the brackets are placed without slot angulation. Dotted line indicates the ideal requirementwww.indiandentalacademy.com
  32. 32. 4.Stems of equal prominence Distance between bracket base & center of slot is same in each brackets. Therefore when the brackets are placed they become as irregular in the facial prominence as the crown. So, with the unbent archwire the facial surface of the each crown becomes equidistant from the embrasure line, which is undesirable.www.indiandentalacademy.com
  33. 33. 5. Maxillary molar offset not built in Since the maxillary molar offset is not built in, the midsagittal plane of the slot is angular to the mid sagittal plane of the crown. This will lead to rotational effect of the molars. So a first order bends must be installed into archwire to accommodate these differences. 6.Unsatisfactory landmarks Most of the authors & practitioners seldom agreed about which landmarks are best for bracket siting and each required a different wire bending.www.indiandentalacademy.com
  34. 34. Non programmed brackets are simple in design, easily manufactured and inexpensive. Unfortunately they are difficult to use because considerable wire bending is needed throughout the treatment. There are three types of wire bending. 1. PRIMARY WIRE BENDING 2. SECONDARY WIRE BENDING 3. TERTIARY WIRE BENDING 1. PRIMARY WIRE BENDING Which includes, • First-order • Second-order • Third-order bends for the most direct movement of teeth.www.indiandentalacademy.com
  35. 35. FIRST-ORDER WIRE BENDING FOR FACIAL PROMINENCE www.indiandentalacademy.com
  36. 36. SECOND-ORDER WIRE BENDING FOR ANGULATION www.indiandentalacademy.com
  37. 37. SECOND-ORDER WIRE BENDING FOR OCCLUSO-GINGIVAL SLOT POSITION www.indiandentalacademy.com
  38. 38. THIRD-ORDER WIRE BENDING FOR INCLINATION www.indiandentalacademy.com
  39. 39. To achieve optimal tooth position and to avoid mesiodistal “rocking” picture the teeth in both arches optimally positioned with ideal rectangular archwires that passively fit all bracket slots. The number and magnitude of primary first-second and third- order bends in those arch wire can be quantified. For the maxillary and mandibular teeth 26 second-order ANGULATION bends needed, totaling 112°. In addition 16 primary second-order OCCLUSOGINGIVAL bends are needed, totaling approximately 2.36mm. For INCLINATION 16 primary third-order bends are required, totaling 215°. For CROWN PROMINENCE 14 first order bends are needed, totaling 6.5mm. And for maxillary molars, there must be 4 first order offset bends totaling 40°. www.indiandentalacademy.com
  40. 40. When the brackets are sited on a full complement of optimally positioned teeth, the final ‘IDEAL’ archwire will require 76 primary wire bendings if it is to be placed passively into the slots. This number includes 46 bends (totaling 484°) for angulation, inclination, and offset, and 30 bends (totaling 24.3mm) for prominence and occlusogingival slot position error. ABOVE STATEMENT PROVED THAT IT IS IMPOSSIBLE TO INCORPORATE ALL THESE BENDS INTO THE ARCHWIRE FOR THE OPTIMAL TOOTH POSITION GIVEN BY ANDREWS. www.indiandentalacademy.com
  41. 41. 2. SECONDARY WIRE BENDS Secondary wire bends are any bends for tooth guidance that are not primary bends. Secondary bends are needed to compensate for slot-siting irregularities caused by bracket design and unreliable bracket-siting techniques, wire bending and wire- forming side effects. 3. TERTIARY WIRE BENDS A tertiary bend is are placed for any reason other than guidance. Examples are Omega loops for steps, loops for increasing wire flexibility and loops for elastics. www.indiandentalacademy.com
  42. 42. INDIVIDUALIZED BRACKETS-BRACKET SITING-SLOT SITING 1927 Angle has suggested angulating the entire bracket. Holdaway in 1952 suggested bracket overangulation for teeth on either side of an extraction site, 1957 Jarabak incorporated slot inclinication to reduce the used for third order bends he also recommended bracket angulation. The concept of forming a fully programmed appliance is that “When the bracket were correctly sited on the crowns, would be as malpositioned as the teeth. Such an appliance, when used with progressively larger unbent archwires, would flex each archwire only to diminishing extent that the slots & the teeth remained incorrectly positioned, until gradually the teeth, slots & wires become aligned or STRAIGHT”. This involved, • Whether bracket could be individualized or customized • Developing a scientific bracket technique • Determining where the slot must be placed for each tooth type.www.indiandentalacademy.com
  43. 43. 1.Individualized and customized brackets Individualized brackets : It is used for both shape and optimal position are similar nearly all individuals with normal teeth. Customized brackets : Shape and optimal position of each tooth type vary sufficiently among individuals. • That is whether we should use a universal bracket system for all the individuals or brackets are customized for every individual according to his tooth type & treatment plan. • The only disadvantage of individualized bracket system is that there might be a need of some wire bending at the end of the treatment for individuals whose teeth differ from the shape or intended position programmed into the brackets. • But a customized appliance would require a second set of cast to construct each patient’s customized appliance & lost brackets could require additional impressions & casts. • So if individualized or universal brackets could produce satisfactory results without wire bending for a high percentage of patients, then it would be the obvious choice. www.indiandentalacademy.com
  44. 44. 2.Bracket siting A suitable bracket site has three criteria : • Bracket located there will not interfere with either gingiva or with opposing teeth during occlusion. • Angulation & inclination of the crown at the bracket site will have a consistent angular relationship to the plane of each tooth’s occlusal surface at all times & to the occlusal plane of arch when the teeth are optimally positioned. • The middle of each bracket must share the same plane or surface when the teeth in an arch is optimally positioned.www.indiandentalacademy.com
  45. 45. The site that meets these requirements is the area in immediate proximity to Crown’s FA Point. The FA point always falls on the Andrew’s plane when the teeth are optimally positioned. Therefore the ideal place for bracket siting will be the mid point of FACC on the FA point. www.indiandentalacademy.com
  46. 46. Crown prominence from embrasure line differ from each tooth type, with prominence in molar being the maximum. 3.Slot siting Accurate bracket siting is of limited value unless each bracket positions it’s slot with equal accuracy at a site that would allow it to passively receive an unbent archwire when teeth are optimally positioned. Therefore when an appliance is designed, it should be designed in such a way that the difference between embrasure line & slot target point should be equal for all teeth in an arch. www.indiandentalacademy.com
  47. 47. In this diagram, the distant between the embrasure line [a] & the slot point [c] is equal from incisors to molar. But since the prominence of molar is more, the distance between the most prominent point on the crown[b] & the slot target point is less than the anterior teeth. This means that the bracket stem thickness is reduced in the molar brackets & it is increased in the anterior brackets.www.indiandentalacademy.com
  48. 48. FULLY PROGRAMMED STANDARD BRACKETS The standard brackets are the one which are designed to guide the tooth without any wire bending. But translation or bodily movement cannot be done with standard brackets. There is one standard bracket for each tooth type, except incisors which has 3 and molar has 2. The fully programmed programmed standard bracket include: 1. SLOT SITING FEATURES 2. CONVENIENCE FEATURES 3. AUXILIARY FEATURES www.indiandentalacademy.com
  49. 49. 1. SLOT SITING FEATURES There are totally 8 slot siting features for the standard brackets : Feature 1: Mid transverse plane of slot, stem & the crown must be in the same plane. In the diagram the midtransverse plane is represented in dotted line. Feature 2 : The base of the bracket for each tooth type must have the same inclination as the facial plane of the crown at FA point.www.indiandentalacademy.com
  50. 50. Feature 3: Each bracket’s inclined base must be contoured occluso gingivally to match the curvature of the crown. These 3 features eliminate the need for 1st & 2nd order bends to deal with occlusogingival disharmony in slot siting, 3rd order bends for inclination & other bends to deal with inherent side effects of wire bending. www.indiandentalacademy.com
  51. 51. Feature 4 : Mid sagittal plane of slot, stem & crown must be the same. Feature 5: Plane of the bracket base at it’s base point must be the same to the facial plane of the crown’s FA point. In all the crowns, this plane bears 90 degree to mid sagittal plane, whereas in molars it is 100 degree due to unequal faciloa prominence of molar cusps.www.indiandentalacademy.com
  52. 52. Feature 6 : The base of the bracket must be contoured to match the mesio distal radius of the area of the crown it is designed to fit. Feature 7: The vertical components of the bracket should be parallel to one another. The bracket’s horizontal components are superior & inferior sides of the bracket stems. When these components are sited equidistance from crown’s gingva & cusp tip, the base point of the bracket will be in line with the FA point. www.indiandentalacademy.com
  53. 53. Feature 8 : Within an arch, all slot points must have the same distance between them & the crown’s embrasure line. This factor eliminates the first order wire bends to accommodate for varying crown prominence. www.indiandentalacademy.com
  54. 54. 2. CONVENIENCE FEATURES Convenience features are the designs incorporated into the brackets that facilitates use by orthodontists or promotes comfort for the patients, but does not contribute to the biological aspect of treatment. For example: • Gingival tie wings are designed to extend laterally so that there will not be any gingival impingement • The facial surface of the incisor & canine brackets are designed parallel to their bases which in turn parallel to crown. This feature is for Lip comfortwww.indiandentalacademy.com
  55. 55. 3. AUXILIARY FEATURES Contribute to the biological aspect of treatment, but not involved in slot siting. E.g. – Power arms, hooks, facebow tubes, etc… PRINCIPLES BEHIND THE INCISOR BRACKETS DESIGN • As reported in the measurement study the inclination range for the incisors are greater than for other teeth. • According to the different skeletal pattern there must be a three standard brackets, each with different base inclination to accommodate one of the three acceptable but different post treatment interjaw relationships. • Of the three brackets designed for maxillary central incisors, one is to used when the interjaw relationship is anticipated to be Class I another is for Class II and the third is for Class III tendencies.www.indiandentalacademy.com
  56. 56. • For the maxillary central incisor, an unpublished study by Andrews (1968) of 100 cephalograms showed an average difference of 18° between the inclination of the facial axis of the crown and that of the long axis of the tooth. The correct maxillary incisor bracket can be selected by subtracting 18° from the post treatment inclination of the tooth`s long axis, relative to a line 90° to the occlusal plane. For example, if the post treatment long axis is projected to be 20° from a line 90° to the occlusal plane, 18° subtracted from the 20° indicates that a bracket with 2° of base inclination should be prescribed. THIS INCLINATION APPLED WHEN THE INTERJAW RELATIONSHIP TENDS TO BE CLASS II.www.indiandentalacademy.com
  57. 57. Class I interjaw conditions the inclination of the maxillary incisor must be approximately 25°; this, minus 18°, converts to a bracket- base inclination of 7°. Class III interjaw conditions, when the tooth’s long-axis inclination is 30°, the bracket-base inclination should be 12°. www.indiandentalacademy.com
  58. 58. In the measurement study, the maxillary lateral incisor’s inclination was found to average 4° less than that of the maxillary central incisor. So whatever bracket-base inclination is prescribed for the maxillary central incisor, the lateral’s bracket-base inclination should be 4° less. For example, the maxillary lateral bracket that is the mate for the 7° central incisor bracket in class I base inclination. www.indiandentalacademy.com
  59. 59. The maxillary lateral bracket that is the mate for the 2° central incisor bracket in class II base inclination. Maxillary central incisor Maxillary lateral incisor www.indiandentalacademy.com
  60. 60. The maxillary lateral bracket that is the mate for the 12° central incisor bracket in class III base inclination. Maxillary central incisor Maxillary lateral incisor www.indiandentalacademy.com
  61. 61. These are the following prescriptions for fully programmed standard brackets : MAXILLARY BRACKETS Central Incisors 3 types Class II -Angulation : 5 degrees Inclination : 2 degrees Prominence : 1.8 mm Class I - Inclination : 7 degrees Class III - Inclination:12 degrees www.indiandentalacademy.com
  62. 62. Lateral Incisors : 3 types Class II -Angulation : 9 degrees Inclination : -2 degrees Prominence : 2.25 mm Class I - Inclination : 3 degrees Class III - Inclination : 8 degrees www.indiandentalacademy.com
  63. 63. Canine Angulation : 11 degrees Inclination : -7 degrees Prominence : 1.4 mm First & Second premolars Angulation : 2 degrees Inclination : -7 degrees Prominence : 1.5 mm First & Second molars Class I : Angulation : 5 degrees Inclination : -9 degrees Prominence : 1mm Offset : 10 degrees Class II : Angulation : 0 degree No Offset www.indiandentalacademy.com
  64. 64. Central & Lateral Incisors Class II -Angulation : 2 degrees Inclination : 4 degrees Prominence : 2.3 mm Class I - Inclination : -1 degrees Class III - Inclination :-6 degrees MANDIBULAR BRACKETS www.indiandentalacademy.com
  65. 65. Canine Angulation : 5 degrees Inclination : -11 degrees Prominence : 1.6 mm Premolars First premolar : Angulation : 5 degrees Inclination : -17 degrees Prominence : 1.6 mm Second premolar : Inclination : -22 degreeswww.indiandentalacademy.com
  66. 66. Molars First molar : Angulation : 2 degrees Inclination : -30 degrees Prominence : 1mm Second molar : Inclination : -35 degrees The incisors have 3 different types because the inclination range for incisors was greater than any teeth mainly because of skeletal class I, classII & class III discrepancies. For maxillary molars, 2 different types are given for class I and class II.www.indiandentalacademy.com
  67. 67. FULLY PROGRAMMED TRANSLATION BRACKETS Translation Problems Translation is defined as “uniform motion of a body in a straight line”. For such movement to occur, the force must be applied to the object’s center of resistance. Unfortunately, a tooth’s center of resistance is in its root. From the standpoint of physics, a bracket located on a crown’s face is in the “wrong” place in two ways. www.indiandentalacademy.com
  68. 68. 1. The bracket is occlusal to the tooth’s center of resistance, so when a mesial or distal force is applied, the tooth, instead of translating, will tend to tip around its horizontal center of rotation. 2. The bracket is also located laterally tooth’s center of resistance, so instead of translating when a mesial or distal force is applied, the tooth will tends to rotate around its vertical center of rotation.www.indiandentalacademy.com
  69. 69. Translation Solution There are two fundamental methods of moving a tooth mesially or distally, and they involve different amounts of force, bone, and efficiency. The two methods are 1. Pure translation 2. Tipping and then Angulating. www.indiandentalacademy.com
  70. 70. The fully programmed translation brackets have all the qualities of standard brackets plus a Power arm and three additional slot siting features which helps in translation: • Counter Rotation • Counter Mesio distal tip • Counter Bucco lingual tip 1. Counter rotation It is the slot siting feature that counteracts the tooth rotation during translation and then overcorrect. This feature when coupled with flex of the archwire counteracts the tooth rotation caused by the mesial or distal force during mesial or distal movement and overcorrects when the mesial or distal movement is complete. www.indiandentalacademy.com
  71. 71. • When a mesial force is applied, the resultant Rotation movement M is counteracted by counter moment CM produced by rotated slot & flexed archwire. • When translation is complete, the rotated slot provides rotation overcorrection. www.indiandentalacademy.com
  72. 72. 3 categories of translation brackets are there for counter rotation • Minimum - 2 degree slot rotation • Medium - 4 degree slot rotation • Maximum - 6 degree slot rotation www.indiandentalacademy.com
  73. 73. Various of Types of Counter Rotation www.indiandentalacademy.com
  74. 74. 2. Counter Mesiodistal tip This is the slot feature that counters mesial or distal tipping during translation and overcorrects. • Mesial slot length “a” is less than the distance between the bracket & the tooth’s center of resistance. • So when a mesial force is applied to the bracket , the countermoment CM & moment M are out of balance & teeth ends in tipping.www.indiandentalacademy.com
  75. 75. • Even when power arm is introduced, there is imbalance since length of power arm is shorter than the distance between center of resistance & the brackets. • When slot angulation is increased, CM is equal to M and results in Translation. This is because when both power arm & slot are activated, the combined width of both of them is equal to the distance between slot & center of resistance. www.indiandentalacademy.com
  76. 76. 3. Counter Buccolingual tip: This slot siting feature is only for maxillary molars that counteracts Buccolingual tip during translation & then overcorrects. This is because the maxillary molars are the only 3 rooted teeth & their translation needs special consideration This is achieved by giving more negative inclination than standard -9 degrees. So here is the various altered values for various tooth types in the fully programmed translation brackets. www.indiandentalacademy.com
  77. 77. MAXILLARY BRACKETS Maxillary Canine Medium translation Angulation : 14 (11 + counter M-D tip of 3) Rotation : 4 Inclination : -7 Maximum translation Angulation : 15 (11 + counter M-D tip of 4) Rotation : 6 Inclination : -7www.indiandentalacademy.com
  78. 78. Maxillary First Premolar Medium translation Angulation : 5 (2 + counter M-D tip is 4) Rotation : 4 Inclination : -7 www.indiandentalacademy.com
  79. 79. Maxillary Second premolar Minimum translation Angulation : 0 (2 + counter M-D tip of -2) Rotation : 2 Inclination : -7 Medium translation Angulation : -1 (2 + counter M-D tip of -3) Rotation : 4 Inclination : -7 Maximum translation Angulation : -2 (2 + counter M-D tip of -4) Rotation : 6 Inclination : -7www.indiandentalacademy.com
  80. 80. Maxillary First & Second Molars Minimum translation Angulation : 3 (5 + counter M-D tip of -2) Rotation : 12 (10 + counter rotation 2) Inclination : -13 (-9 + counter buccolingual tip of -4) Medium translation Angulation : 2 (5 + counter M-D tip of -3) Rotation : 14 (10 + 4) Inclination : -14 (-9 + -5) Maximum translation Angulation : 1 (5 + counter M-D tip of -4) Rotation : 16 (10 + 6) Inclination : -15 (-9 + -6) www.indiandentalacademy.com
  81. 81. Mandibular canine Medium translation Angulation : 8 (5 + counter M-D tip of 3) Rotation : 4 (0 + Counter rotation 4) Inclination : -11 Maximum translation Angulation : 9 (5 + counter M-D tip of 4) Rotation : 6 (0 + 6) Inclination : -11 First Premolar Medium translation Angulation : 5 (2 + counter M-D tip of 3) Rotation : 4 (0 + 4) Inclination : -17www.indiandentalacademy.com
  82. 82. Second Premolar Minimum translation Angulation : 0 (2 + counter M-D tip of -2) Rotation : 2 (0 + 2) Inclination : -22 Medium translation Angulation : -1 (2 + counter M-D tip of -3) Rotation : 4 (0 + 4) Inclination : -22 Maximum translation Angulation : -2 (2 + counter M-D tip of -4) Rotation : 6 (0 + 6) Inclination : -22www.indiandentalacademy.com
  83. 83. Mandibular First Molar Minimum translation Angulation : 0 (2 + counter M-D tip of -2) Rotation : 2 Inclination : -30 Medium translation Angulation : -1 (2 + counter M-D tip of -3) Rotation : 4 Inclination : -30 Maximum translation Angulation : -2 (2 + counter M-D tip of -4) Rotation : 6 Inclination : -30www.indiandentalacademy.com
  84. 84. Mandibular Second Molar Minimum translation Angulation : 0 (2 + counter M-D tip of -2) Rotation : 2 Inclination : -35 Medium translation Angulation : -1 (2 + counter M-D tip of -3) Rotation : 4 Inclination : -35 Maximum translation Angulation : -2 (2 + counter M-D tip of -4) Rotation : 6 Inclination : -35www.indiandentalacademy.com
  85. 85. FULLY PROGRAMMED APPLIANCE PRESCRIPTION Selecting a most suitable Straightwire brackets for each tooth in an arch begins with deciding which teeth must be moved mesiodistally & how far they must be moved. The next step is to determine whether those teeth should be tipped or translated. The teeth to be translated will need translation brackets – Minimum, medium or maximum depending upon the teeth to be moved. The other teeth may need only standard brackets. www.indiandentalacademy.com
  86. 86. www.indiandentalacademy.com
  87. 87. To make these distinctions, first measure the discrepancy between the size of the teeth & space available for them within the existing arch. Then add or subtract the amount of space that would result from any proposed changes which can be achieved without mesial or distal movement. The result would give the interim core discrepancy – ICD. Depending upon the value of ICD, treatment plan can be made for the mesial or distal movement of the teeth, with or without extraction. Andrew gave 12 possibilities for maxillary arch & 11 for the mandibular arch. Depending upon the value of ICD, he made 3 types of natural divisions- Spaced, classic & crowded. The prescriptions were extraction or non extraction depending upon the discrepancy, which is given in the chart. So these are the following prescriptions which Andrew gave for each situations:- S indicates standard brackets, 1 indicated minimum translation brackets, 2 indicates medium & 3 indicated maximum translation brackets. www.indiandentalacademy.com
  88. 88. TYPE SPACED 3 Subtypes – All non extraction Subtype 0 to 4 mm Advance molars & premolars 0 to 2 mm per side Subtype 5 to 8 mm Advance molars & premolars 2.5 mm to 5 mm per side Subtype 9 to 14 mm Advance molars & premolars 4.5 to 7 mm per side www.indiandentalacademy.com
  89. 89. TYPE CLASSIC (zero space) 1 Subtype – Non extraction 1 Alternative – extraction Subtype – Non extraction Some tooth repositioning is required- Angulation, inclination, rotation, Tipping, intrusion or extrusion. Alternate – extraction of first premolars www.indiandentalacademy.com
  90. 90. TYPE CROWDED 6 extractions & 1 non-extraction Subtype 0 to 6 – non extraction Molars, premolars & canines Tipped distally to neutralize ICD Alternate – exactly 6 mm Extraction of first premolars Translate molars 3 mm mesially Premolar & canines 3mm distally Subtype 7 to 8mm Extraction of first premolars Advance molars & premolars Retract canines www.indiandentalacademy.com
  91. 91. Subtype – 9 to 10 mm Extraction of first premolars Subtype – 11 to 13mm Extraction of first premolars www.indiandentalacademy.com
  92. 92. Subtype 14 mm Extraction of first premolars Retract only the canines Alternate 14 mm Only for Maxillary arch. When class II molar relation is left that way www.indiandentalacademy.com
  93. 93. Even though this series of brackets given by Andrew were used initially, now they are not used because of the following disadvantages:- • Undesirable force vectors,[especially tip of the canines] are increased in the early stages of treatment. • When light forces are used, the overcorrection built into extraction series brackets is not necessary. • There is a need for substantially increased band & bracket inventory, or else a need to weld brackets at the chairside with inherent possibilities of inaccuracy. • More than that this also gives different types of prescriptions for various situations. But it is always better to have a universal system of bracket prescription instead of some 12 prescriptions. So these disadvantages gave rise to lot of modifications in the prescriptions in the following years. www.indiandentalacademy.com
  94. 94. CONCLUSION Straight wire appliance is not a computer software which can be downloaded from the bracket case and executed in the teeth to get desired results. Preadjusted edgewise appliance will not diagnose cases, it will not set up treatment plan, and will not figure out the mechanics needed to correct the malocclusion. But a properly placed Straight wire appliance will detail the tooth positions better, more consistently, and faster than one can be bending offsets into the archwire. The key is to get the brackets properly placed. This requires lot of self discipline and persistence, but the benefits are well worth of the efforts. It allows one to detail and finish cases more accurately. www.indiandentalacademy.com
  95. 95. For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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