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Class II div 1 complicated by over-retention primary molar

drhermanchung  

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hello my dear colleagues, I am new to ortho field ,recently got a case like this and want to discuss the diagnosis and treatment plan with you guys!
the patient is 14 y.o female, seek to correct the protrusive lip.
Initially before reading the xray ,I though this would be a straight forward class II div 1 case which would be a good candidate for class II corrector like Herbst appliance/Twin block . However it is a bit more complicated than I though. I think it would be nice to discuss here and get some new insight!
1. Why would both the canine and molar be in class II( and that huge overjet!) while the skeletal base is in class I ? what would be the cause and diagnosis here?
2. I think extraction is needed at upper for overjet reduction ,while the lower space could be gained by IPR , hence I plan to extract 14,24 ,while lower IPR 75,85 .
Since the upper molars are already in 3/4 unit class ii position, I do not wish to further mesialize it ,hence I planned to make use of TAD for absolute anchorage ,however, if I am to do absolute anchorage, the canine will end up be in class III position even if lower canine is distalized for few mm after IPR ,I think the major problem is caused by 75,85 retention. what should I do in such a case?
a. should I avoid TAD, plan max anchorage and end the molar in a 'super' class II relationship
b. should I keep TAD, maximize distalization by IPR (will it even work?)
c. should I keep TAD, extract lower primary molar and distalize lower canine into class I and space maintenance by retainer (But vital tooth is the best retainer isn't it?)

(headgear is not an option here, as patient and her parents declined that)

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Dr.Suki

Dental classification and skeletal classification can be thought separately. I think that all treatment plans are confused because of the retained deciduous molar. You need to decide whether to do space closure after extraction of the deciduous molar or not. If you decide not to extract the deciduous molar, the molar key will not set exactly. If 14, 24, 75, 85 are extracted, it is needed mandibular molar mesialization and the TAD for maxillary teeth.