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Anterior Open Bite Correction- Conventional Treatment vs. TADs Jae Hyun Park. AAO June 2021

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Farooq Ahmed

 

Anterior Open Bite Correction: Conventional Treatment vs. TADs  Jae Hyun Park

Tooth movement for AOB correction in orthodontics

·      Extrusion of anterior teeth

o   Normal or decreased posterior alveolar bone

o   No excessive gingival show

·      Intrusion of posterior teeth

o   Increased LAFH

o   Excessive gingival display

Extrusion of anterior teeth

·      Gingival show on smiling investigated Kokich 1999

o   Lay people acceptable up to 4mm

o   Orthodontists acceptable up to 2mm

Facial pattern effect perception of gingival exposure whilst smiling? Lima 2019

·      Long face pattern 3mm gingival show acceptable

·      Balanced face pattern: 5mm gingival show acceptable

TAD and AOB management

·      AOB closure conventional mechanics Vs TADs Deguchi 2020

·      Conventional AOB closure: anterior extrusion

o   Anterior extrusion upper 3mm, lower 2mm, increase LAFH 3mm

·      TADs AOB closure: posterior intrusion

o   Intrusion of upper molar 2mm, lower molar 1mm, anticlockwise rotation of mandible

 

·      Stability of posterior intrusion with TADs

·      Less stability in TAD group with extrusion of molars following treatment

·      If TADs used in mandible, TADs should be used in retention

·      30% relapse after 1 year in TAD group

·       Position and number of of TADs for posterior intrusion

·      Options for position of TADs

o   Buccal – reduced interradicular distance ()reduces further as teeth intrude)

o   Palatal – greater interradicular distance 6mm

o   Between 6-7 preferred to 5-6 as greater moment generated between 6-7 and more efficient intrusion

·      1 Vs 2 TADs

o   Forces better distributed with 2 TADs when compared to 1 TAD

·      TAD mechanics

·      Modified TPA

o   Arms connected to parasagittal TADs

o   Powerchain from TADs to molars

·      TAD  and TPA design Cifter 2011

o   1 TAD and TPA, 2 TADS and 1 TPA, 2 TADS and 2 TPAs

§  2 TADs gave greater control of molars and force distribution

·       Occlusal plane changes with TAD intrusion

·      Upper posterior intrusion = steepen occlusal plane

o   Can prevent by intrusion of the lower molar intrusion as well

o   If intrude upper molars only, lower molars will over erupt, no overall change to LAFH

·      Posterior intrusion results in autorotation, can result in premature anterior contact

o   Solution retraction of the lower incisors prior to autorotation

Conclusion

·      Increase LAFH with excessive gingival show = Posterior intrusion with TADs

o   Posterior intrusion should be upper and lower

o   Posterior TAD placed more distally = more efficient intrusion\

 

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