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\
