Controlled Space Closure with
a Pre-adjusted Appliance
System
INDIAN DENTAL ACADEMY
Leader in continuing dental education
...
Mechanics of Space Closure
• Extraction of four premolars is commonly
believed to be necessary for the proper
management o...
• Orthodontists have been able to reduce
the use of closing loops and, because of
the level slot lineup, enjoy the advanta...
• Hooks of .024 " stainless steel or .028 "
brass are soldered to the upper and lower
arch wires .
• The average distances...
Fig. 1 Upper and lower working archwires with
most common hook positions
www.indiandentalacademy.com
• The force required for space closure is delivered
by elastic "tiebacks" An elastic module
stretched by 2-3mm (to twice i...
Fig. 2 Elastic "tiebacks" delivering 50-150g
of space-closing force
www.indiandentalacademy.com
Effects of Overly Rapid Space
Closure
• Space closure typically occurs more easily in
high-angle patterns with weak muscul...
• Loss of torque control results in upper
incisors being too upright at the end of
space closure with spaces distal to the...
Fig. 3 A. Too rapid incisor retraction leaves upper
incisors with inadequate torque
B. Too rapid mesial movement of molars...
• Reduced rotation control can be seen mainly in
the teeth adjacent to extraction sites, which also
tend to roll in if spa...
Fig. 4 With overly rapid space closure, teeth
adjacent to extraction sites tend to "roll in"www.indiandentalacademy.com
Fig. 5 Too rapid space closure produces lower
molar tipping, with extrusion of distal cusps.
Soft-tissue build-up can prev...
Inhibitors to Sliding Mechanics
• Proper alignment of bracket slots is essential to
eliminate frictional resistance to sli...
Fig. 6 A. Rectangular .019" x 0.025" arch wire tied
passively until completion of leveling and aligning
www.indiandentalac...
Fig. 6 B. Elastic tiebacks placed to begin sliding
mechanics with low-friction, level slot alignment
www.indiandentalacade...
• There are three primary sources of friction
during space closure . First-order or rotational
resistance at the mesiobucc...
• Second-order or tipping resistance at the mesio-
occlusal and distogingival aspects of the
posterior bracket slots is ca...
• Third-order or torsional resistance occurs
at any of the four areas of the bracket slot
where the edges of the archwire ...
Fig. 7 Sources of friction during space closure
A. First-order or rotational resistance
B. Second-order or tipping resista...
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
Problems During Space Closure
• Since forces are directed from the first molars to anterior
hooks on the archwire, small s...
Fig. 9 Methods of preventing or correcting space opening
between first and second molars.
A. Ligature tie from second to f...
• Interference from opposing teeth sometimes restricts
lower arch space closure, particularly if bracket
placement was inc...
Fig. 10 Upper premolar bracket positioned
too far gingivally, preventing lower space
closure
www.indiandentalacademy.com
Anchorage Control
• "Anchorage loss" is the term traditionally
used for mesial movement of the molars in
the sagittal plan...
• In the maxilla, extracting the first premolars
instead of the second premolars provides more
anchorage gain. The effect ...
Fig. 11 Extraction of lower premolars can lead to
narrowing (hourglass shape) of remaining cortical
bone, providing only n...
• Intermaxillary elastics are a convenient
and effective method of anchorage control.
They can be used routinely at force ...
• Rigid, soldered palatal and lingual arches
can support anchorage during the leveling
and aligning phase and during resol...
• Reverse headgears (or facial masks) have
been well accepted by some patients and
have been effective in "losing" anchora...
• With good cooperation, lip bumpers can
provide maximum support of lower
anchorage. However, they have found lip
bumpers ...
• Archwire thinning is effective, but they
have discarded it because of reduced
tooth control in the thinned areas.
Select...
Fig. 12 Selective application of torque in
rectangular arch wires can affect anchorage
balance in both anterior and poster...
Conclusion
• Attention to detail in mechanics-especially
regarding arch wire size and design and
levels of force-is essent...
www.indiandentalacademy.com
Thank you
For more details please visit
www.indiandentalacademy.com
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Controlled space closure with a pre adjusted appliance system /certified fixed orthodontic courses by Indian dental academy

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Controlled space closure with a pre adjusted appliance system /certified fixed orthodontic courses by Indian dental academy

  1. 1. Controlled Space Closure with a Pre-adjusted Appliance System INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Mechanics of Space Closure • Extraction of four premolars is commonly believed to be necessary for the proper management of some malocclusions. • The 7mm of space gained in each quadrant is used in one or more of three ways: relief of crowding, retraction of incisors, or mesial movement of molars www.indiandentalacademy.com
  3. 3. • Orthodontists have been able to reduce the use of closing loops and, because of the level slot lineup, enjoy the advantages of sliding mechanics. • This minimizes the need to monitor individual tooth movements, allowing greater attention to be paid to other important factors such as anchorage control, overbite control, overjet reduction, skeletal management, and facial profile. www.indiandentalacademy.com
  4. 4. • Hooks of .024 " stainless steel or .028 " brass are soldered to the upper and lower arch wires . • The average distances between hooks- 38mm in the upper arch and 26mm in the lower arch-suit the clinical requirements of more than half patients, so they have had wires prefabricated to this size. • Additional sizes of 35mm and 41mm (upper) and 24mm and 28mm (lower) cover most of the remaining cases. www.indiandentalacademy.com
  5. 5. Fig. 1 Upper and lower working archwires with most common hook positions www.indiandentalacademy.com
  6. 6. • The force required for space closure is delivered by elastic "tiebacks" An elastic module stretched by 2-3mm (to twice its normal length) usually delivers .5-1.5mm of space closure per month. Group movement and sliding mechanics are combined for gentle, controlled space closure, so that about .5mm of incisor retraction and .5mm of mesial molar movement can be seen each month. • The tiebacks are replaced every four to six weeks. www.indiandentalacademy.com
  7. 7. Fig. 2 Elastic "tiebacks" delivering 50-150g of space-closing force www.indiandentalacademy.com
  8. 8. Effects of Overly Rapid Space Closure • Space closure typically occurs more easily in high-angle patterns with weak musculature than in low-angle patterns with stronger musculature. • The rate of closure can be increased, particularly in high-angle cases, by slightly raising the force level or using thinner archwires. However, more rapid space closure can lead to loss of control of torque, rotation, and tip. www.indiandentalacademy.com
  9. 9. • Loss of torque control results in upper incisors being too upright at the end of space closure with spaces distal to the canines and a consequent unesthetic appearance. • The lost torque is difficult to regain. Also, rapid mesial movement of the upper molars can allow the palatal cusps to hang down, resulting in functional interferences, and rapid movement of the lower molars causes "rolling in". www.indiandentalacademy.com
  10. 10. Fig. 3 A. Too rapid incisor retraction leaves upper incisors with inadequate torque B. Too rapid mesial movement of molars cause functional interferences; molars need additional torque to reach ideal angulations www.indiandentalacademy.com
  11. 11. • Reduced rotation control can be seen mainly in the teeth adjacent to extraction sites, which also tend to roll in if spaces are closed too rapidly. • Reduced tip control produces unwanted movement of canines, premolars, and molars, along with a tendency for lateral open bite. • In high-angle cases, where lower molars tip most freely, the elevated distal cusps create the possibility of a molar fulcrum effect. In some instances, excessive soft-tissue hyperplasia occurs at the extraction sites.www.indiandentalacademy.com
  12. 12. Fig. 4 With overly rapid space closure, teeth adjacent to extraction sites tend to "roll in"www.indiandentalacademy.com
  13. 13. Fig. 5 Too rapid space closure produces lower molar tipping, with extrusion of distal cusps. Soft-tissue build-up can prevent full space closure or allow spaces to reopen after treatmentwww.indiandentalacademy.com
  14. 14. Inhibitors to Sliding Mechanics • Proper alignment of bracket slots is essential to eliminate frictional resistance to sliding mechanics. The common procedure is to use .018" or .020 " round wire for at least one month before placing .019"´.025" rectangular wires. • It became clear to us that leveling and aligning continues for at least a month after insertion of the rectangular wires, and that space closure cannot proceed during that period. www.indiandentalacademy.com
  15. 15. Fig. 6 A. Rectangular .019" x 0.025" arch wire tied passively until completion of leveling and aligning www.indiandentalacademy.com
  16. 16. Fig. 6 B. Elastic tiebacks placed to begin sliding mechanics with low-friction, level slot alignment www.indiandentalacademy.com
  17. 17. • There are three primary sources of friction during space closure . First-order or rotational resistance at the mesiobuccal and distolingual aspects of the posterior bracket slots is produced by rotational forces on the buccal aspects of the posterior teeth. • The most effective way to counteract this resistance is to apply intermittent lingual elastic forces-one month from cuspid to first molar, the next month from cuspid to second molar. www.indiandentalacademy.com
  18. 18. • Second-order or tipping resistance at the mesio- occlusal and distogingival aspects of the posterior bracket slots is caused by excessive and overactivated tieback forces, which lead to tipping of the posterior teeth, inadequate rebound time to upright these teeth, and a resultant binding of the system. • The importance of light forces (50-150g) and minimal activation length (to provide time for uprighting) cannot be overemphasized. www.indiandentalacademy.com
  19. 19. • Third-order or torsional resistance occurs at any of the four areas of the bracket slot where the edges of the archwire make contact. Like tipping resistance, this is produced mainly by excessive and overactivated tieback forces, which cause the upper posterior lingual cusps to drop down and the lower posterior teeth to roll in lingually. www.indiandentalacademy.com
  20. 20. Fig. 7 Sources of friction during space closure A. First-order or rotational resistance B. Second-order or tipping resistance C. Third-order or torsional resistance www.indiandentalacademy.com
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  26. 26. Problems During Space Closure • Since forces are directed from the first molars to anterior hooks on the archwire, small spaces occasionally open between the first and second molars. This can be managed in one of three ways: • The first and second molars can be tied together before beginning space closure ; a "K-2" elastic can be extended from the second molar to the archwire hook, in addition to the elastic or wire tieback to the first molar; or the tieback can be extended to the archwire hook from the second molar instead of the first molar. The third method is particularly effective after the extraction sites and all other spaces have been closed. www.indiandentalacademy.com
  27. 27. Fig. 9 Methods of preventing or correcting space opening between first and second molars. A. Ligature tie from second to first molar. B. "K-2" elastic from second molar to archwire hook. C. Elastic tieback from second molar instead of first molarwww.indiandentalacademy.com
  28. 28. • Interference from opposing teeth sometimes restricts lower arch space closure, particularly if bracket placement was incorrect or a full-unit Class II molar relationship existed. • Certain tissue factors can hinder full space closure with any kind of mechanics. Soft-tissue build-up can result from poor plaque control or overly rapid space closure. The alveolar cortical plate, mesial to the lower first molars, tends to narrow after extraction of the second premolars, especially in lower-angle situations. Retained roots, ankylosed teeth, and bone sclerosis are other possible factors to be considered. www.indiandentalacademy.com
  29. 29. Fig. 10 Upper premolar bracket positioned too far gingivally, preventing lower space closure www.indiandentalacademy.com
  30. 30. Anchorage Control • "Anchorage loss" is the term traditionally used for mesial movement of the molars in the sagittal plane. "Anchorage gain" describes distal movement of the incisors. We will use these terms in this way, even though they are not always logical; for example, "anchorage loss" in the maxilla is often beneficial in Class III cases. www.indiandentalacademy.com
  31. 31. • In the maxilla, extracting the first premolars instead of the second premolars provides more anchorage gain. The effect is less pronounced in the mandible, because of a tendency for the cortical bone to form an hourglass shape, especially in lower-angle cases, which restricts mesial movement of the first molars . • Our usual choice in balancing anchorage control is to extract upper 5s and lower 4s in Class III cases and upper 4s and lower 5s in Class II, division 1 cases. www.indiandentalacademy.com
  32. 32. Fig. 11 Extraction of lower premolars can lead to narrowing (hourglass shape) of remaining cortical bone, providing only narrow area of alveolus for mesial movement of first molars www.indiandentalacademy.com
  33. 33. • Intermaxillary elastics are a convenient and effective method of anchorage control. They can be used routinely at force levels of l00g in average or low-angle cases. • Much more care is needed in high-angle patterns, where muscular forces are less able to resist the extrusive component of intermaxillary force. In such cases, elastics can be used selectively for short periods, sometimes only at night, with force levels reduced to 50-70g. www.indiandentalacademy.com
  34. 34. • Rigid, soldered palatal and lingual arches can support anchorage during the leveling and aligning phase and during resolution of crowding. • The facebow of conventional combination headgear, worn at night, can be used to control upper molars. In cases requiring intrusive force on the incisors, a J-hook headgear can be applied directly to upper archwire hooks. www.indiandentalacademy.com
  35. 35. • Reverse headgears (or facial masks) have been well accepted by some patients and have been effective in "losing" anchorage. The elastics are applied either directly to molar hooks or to archwire hooks after modification. A reverse headgear can deliver an asymmetrical force in cases of unilateral problems or midline shifts. www.indiandentalacademy.com
  36. 36. • With good cooperation, lip bumpers can provide maximum support of lower anchorage. However, they have found lip bumpers more effective in nonextraction cases where uprighting or distal tipping of the lower molars is required. • They occasionally use lower utility arches for incisor intrusion and molar uprighting. This type of mechanics also provides additional lower anchorage. www.indiandentalacademy.com
  37. 37. • Archwire thinning is effective, but they have discarded it because of reduced tooth control in the thinned areas. Selective torque application is more effective, especially in the incisor regions. • Flat wires can be adjusted quickly and easily at chairside to carry a customized 10-15° of incisor torque. Likewise, molar torque can be selectively applied to resist mesial movement of the molars and create a basis for sound functional movements. www.indiandentalacademy.com
  38. 38. Fig. 12 Selective application of torque in rectangular arch wires can affect anchorage balance in both anterior and posterior regions www.indiandentalacademy.com
  39. 39. Conclusion • Attention to detail in mechanics-especially regarding arch wire size and design and levels of force-is essential to produce consistent results. • Overly rapid space closure and possible inhibitors to sliding mechanics must be avoided. • Level slot lineup, implying careful leveling and aligning techniques, is a key. www.indiandentalacademy.com
  40. 40. www.indiandentalacademy.com Thank you For more details please visit www.indiandentalacademy.com

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