Dr Claudia Cruz and Roberto Stadi describe the predicability of aligners, indirect bonding for labial and lingual appliances

Summary

Aligners

Factors which reduce the predictability of aligners

· Manufacturing process: 0.1mm

· Force delivery

o Thermoforming force decay

o Inconsistent thickness of aligner

· Anatomy of teeth: Rounded teeth (Canines and Premolars / Bicuspids)

How to improve predictability

Clinical:

· Increase attachment size, alter attachment orientation, stage movements

Technological – not achieved yet!

· Use actual root information (CBCT), control thermoforming features, calculate forces required and ideal attachment for tooth movement

Indirect labial bonding

· Up to 1mm error in bracket placement in indirectly

· Up to 1 mm error in robotic archwire formation

· Outcomes worse than conventional direct bonding

· Tooth morphology anterior 2-2 will usually require manual wire bending

Lingual appliance

· Accurate to 40 and up to 1 mm

· Torque discrepancies manifest in greater 2nd order error than labial

· Extraction cases: more critical to control moment force ratio, if not = greater retroclination / loss of torque of upper labial segment

Conclusion:

New technology have discrepancies which the clinician should factor into treatment planning

References

Customised labial brackets accuracy

Alford, T.J., Roberts, W.E., Hartsfield Jr, J.K., Eckert, G.J. and Snyder, R.J., 2011. Clinical outcomes for patients finished with the SureSmile™ method compared with conventional fixed orthodontic therapy. The Angle Orthodontist, 81(3), pp.383-388.

Morphology of teeth and outcomes of orthodontics

Miethke, R.R. and Melsen, B., 1999. Effect of variation in tooth morphology and bracket position on first and third order correction with preadjusted appliances. American Journal of Orthodontics and Dentofacial Orthopedics, 116(3), pp.329-335.

Effectiveness of aligners

Papadimitriou, A., Mousoulea, S., Gkantidis, N. and Kloukos, D., 2018. Clinical effectiveness of Invisalign® orthodontic treatment: a systematic review. Progress in orthodontics, 19(1), p.37.

Accuracy of lingual appliances

Grauer, D. and Proffit, W.R., 2011. Accuracy in tooth positioning with a fully customized lingual orthodontic appliance. American Journal of Orthodontics and Dentofacial Orthopedics, 140(3), pp.433-443.

Loss of torque affects,labial and lingual

Liang, W., Rong, Q., Lin, J. and Xu, B., 2009. Torque control of the maxillary incisors in lingual and labial orthodontics: a 3-dimensional finite element analysis. American Journal of Orthodontics and Dentofacial Orthopedics, 135(3), pp.316-322.

Summary of Dr Elie's research regarding space closure mechanics for missing upper lateral incisors

· Patients with missing upper lateral incisors usually have hypoplastic maxilla

· Clinical trial investigating mechanics to advance maxilla and close space

P: Class 1 / class 3 cases, non-extraction lower arch

I: Fixed appliances to close space in the upper arch

C: Nil

O: Maxillary advancement and inclination change in the upper arch

Method

· TADs in lower 3-4 region

· Class 3 elastics from TAD to upper 7s

Results

· Advancement of maxilla, SNA increase by 1.3o

· No changes to upper incisor inclination

· Mesial movement of upper molars 5mm

Conclusion

· Using treatment protocol, it is possible to advance the maxilla and close space for missing upper lateral incisors

Critique

· Side affects of counter clockwise rotation of maxilla

Summary of webinar from the AAO, looking at lower incisor change and orthodontics

Expanding the Lower Arch Is it Really a Forbidden Frontier: Flavia Artese

· 4 indications to change lower incisor position:

1. Good profile with arch length discrepancy

2. Level lower arch curve of Spee

3. Class 3 dentoalveolar decompensation

4. Class 2 compensation

· 3 Factors which determine gingival recession for orthodontic patients

o Visible plaque – most important

o Amount of proclination – least understood

o Periodontal biotype / phenotype – can be altered

· 3 biotypes

o Thick -flat : Broad zone of KT, thick gingiva, square teeth

o Thick- scalloped:  Narrow zone of KT, Thick gingiva, Slender teeth

o Thin – scalloped: Narrow one of KT, thin ginviva, triangular teeth

· Assessment of biotype

o Clinical, including probe to assess translucency

o CBCT

§ CBCT studies show greatest recession in Canine and Premolar region

Conclusion

o Avoid expanding / proclining lower arch, if required then indication for periodontal surgery

#orthodontics #farooqahmed #almuzian  #morth #omg

@farooqahmed

 Mazyar Moshiri;s lecture from the AAO describes how to modify aligners and clinical pearls.

#orthodontics #orthodonticsmasterygroup #farooqahmed #almuzian #glasgoworthodonticacademy #morth #omg

@g_orthodontic_a

@farooqahmed

Modifications to consider to aligner

o Change attachment – changes tooth shape

o Change aligner shape – e.g. power ridge

o Change sequence of tooth movement

· Aligner force should be directed perpendicular to the resultant tooth movement required

· Vertical control is key

o if not can result in heavy anterior contact – curve of spee due to loss of vertical anchorage and a LATERAL OPENBITE

o Resolve with anterior intrusion

· Deep bite cases should be over treated to AOBs

· Clincheck is a force delivery representation, not a virtual treatment objective

· AOB cases

o Attachments on the occlusal aspect without composite, aids intrusion

· Class 3

o TADs in buccal shelf region

Summary of webinar looking at 2 phase treatment 

Functional shift

· Should be treated early

· Use of RME, bonded to Es

· More stable expansion in younger patients

Crowding (mandibular arch)

· Should be treated in up to 5mm of crowding and patient concerns

· Use of leeway space

· Tool: Lingual arch

Overjet

· Treat if patients have concerns

· Preferred method 1 phase for growth and reduced treatment times

Class 3

· Treat if maxillary deficiency only

· Protraction face mask – limited improvement

· Least favourable interceptive treatment

Orthodontics #farooqahmed #morth  #glasgoworthodonticacademy 

@farooqahmed

Summary of Nikhilesh Vaid's lecture at the AAO 2020 looking at technology in orthodontics.

#orthodontic

#farooqahmed

Summary of Chris Chan's lecture at the AAO, looking at TADs and their use.

#Orthodontics #farooqahmed #morth #omg #glasgoworthodonticacademy #omg

@g_orthodontic_a

@farooqahmed

Summary of the webinar exploring the role of the occlusal plane and the aetiology of the malocclusion

#orthodonticsinsummary

#orthodontics

#podcast

#farooq