Join me as I summarise Roberto’s lecture looking at transpositions.

Roberto describes 2 cases of true transpositions, treatment options, mechanics and methods of camouflage.

Transposition: defined an anomaly in which 2 adjacent teeth have interchanged their position in the arch Peck 1993

Classification: 1995 by Peck and Peck

1. True transposition: root and crown

2. False transposition: crown only

Up to 2003 the majority of orthodontists accept transposition and this figure changed as currently most orthodontist tend to correct transpositions.

Case 1 Maxillary canine-premolar transposition - camouflage

Treatment:

1. Interceptive early RME spontaneous correction of maxillary canine-premolar transposition Maspero 2016 86% corrected.

2. Premolar camouflage: Although Sandler 2017 no difference in canine and premolar aesthetics for professionals and lay people transposition are different:

· Gingival height of the canine high compared to the premolar, if we don’t grind the canine tip,

a. Check smile line, low smile line = result will be acceptable by the patient.

b. End with slight intrusion in the premolar – so gingival height matches the canine Build up the premolar to make It look longer

Case 2 Maxillary canine-premolar transposition, canine high - correction

Treatment:

· Cannot apply conventional mechanics through the center of resistance of the canine due to vertical position

· Sectional wire:

· Wire from 1st molar to 1st premolar (bypass canine)

· Bent back on itself to then engage the canine (in the premolar position)

· = Class 6 Geometry (burstone) allowing intrusion of the canine during meisalization and by passing the premolar

· Torque:  Need to keep the root palatal

· Apply couple one wire and with another wire he prevents the crown movement

· Auxiliary springs like warren spring or Goodman springs

· Single root torque to a tooth

Mandibular arch transpositions

· Less demanding to correct the lower arch transpositions due to decreased aesthetic requirements

· Word of caution to correct transition:  Limited bucco-lingual width

Danielsen JC, Karimian K, Ciarlantini R, Melsen B, Kjær I. Unilateral and bilateral dental transpositions in the maxilla—dental and skeletal findings in 63 individuals. Eur Arch Paediatr Dent [Internet]. 2015 Dec 1 [cited 2020 Nov 18];16(6):467–76. Available from: https://link.springer.com/article/10.1007/s40368-015-0196-6

Leonardi R, … MF-TEJ of, 2011 undefined. An association between sella turcica bridging and dental transposition. academic.oup.com [Internet]. [cited 2020 Nov 18]; Available from: https://academic.oup.com/ejo/article-abstract/33/4/461/398881

Maspero C, Giannini L, Galbiati G, … MF-M, 2016 undefined. Effect of rapid palatal expansion in early tratment and spontaneous correction of maxillary canine-first premolar transposition. europepmc.org [Internet]. [cited 2020 Nov 18]; Available from: https://europepmc.org/article/med/27075370

Shapira Y, Finkelstein T, Kadry R, Schonberger S, Shpack N. Mandibular Symmetrical Bilateral Canine-Lateral Incisors Transposition: Its Early Diagnosis and Treatment Considerations. Case Rep Dent [Internet]. 2016 [cited 2020 Nov 18];2016:1–6. Available from: https://www.hindawi.com/journals/crid/2016/5043801/abs/

Sandler P. Extraction of maxillary canines: Esthetic perceptions of patient smiles among dental professionals and laypeople. 2017 [cited 2020 Nov 19]; Available from: http://derbyhospitals-nhs.archive.knowledgearc.net/handle/123456789/1160