Treatment Planning help for Ortho Resident!!!

[Orthoresma]

Hello everyone,

I hope some of my fellow ortho residents can comment upon the following treatment plan and critique it.

Case:
32 year old female with complaint of increased overjet

Overjet 6mm
U1/MxPl 109
L1/MnPl 91
High MPA
Class II Half unit malocclusion
Upper arch well algined
Lower arch has 6mm posterior crowding (3mm per quadrant)
Lower first bicuspids are endodontically involved.
Gingiva and bone overlying lower incisors are thin

My treatment plan...(please critique!!!!) is to extract all first bicuspids
Each bicuspid is 8mm in mesiodistal width. The treatment objectives are to reduce the overjet to 2mm and maintain lower incisor position. This has been agreed upon by my supervisor but i have some problem with the space management.......

My questions are

1) what is my upper anchorage demand??? and
2) what is my lower anchorage demand???

My dilemma stems from this

Some of my tutors advocate treating the upper arch maximum anchorage and the lower arch minimum anchorage. I agree with the lower arch demand.

Now to retract the upper anteriors to an ideal overjet of 2mm will require 4mm of space per quadrant which is 50% of the space....this should just be moderate anchorage demand no?

Some seniors have told me that when i attempt to drag the lower 2nd premolar and then the 1st molar forward the lower anteriors will retract. So that means even if they retract 2mm i will need to retract the upper anterior teeth 6mm. This is 75% of the extraction space so this amount of retraction will require maximum anchorage in the upper arch e.g...nance, band 7s etc

But my thinking is as follows......

I can place lingual root torque on the lower incisors and tie the lower 6 anterior teeth together and then pull the lower 2nd premolars forward. I can now fit a lingual arch across the 8 teeth in the anterior segment and pull the lower molar forward.

Now since there was 3mm of posterior crowding per quadrant in the lower arch and the extraction space is 8mm per quadrant...i need to protact the lower 2nd premolar and lower first molar 5mm....so lets say i end up retracting the lower anteriors 40% of the space which is 2mm. Hopefully with all the precautions i shouldnt retract the lower anteriors more than that.

Now lets say i have retracted the upper anteriors with reciprocal space closure in the upper and retracted the upper anteriors 4mm. Since we started with an overjet of 6mm and the lower incisors retracted a bit (lets say 2mm as discussed above) we will end up with an overjet of 4mm.

Now i can ask the patient to wear some class II elastics to mesialise the lower incisors 2mm to achieve and ideal overjet of 2mm...in other words..."regain the anchorage" i lost from the lower anterior segment as it retracted while i closed the lower space. Now some may feel this is round tripping....but i disagree as i have tried everything to prevent the lower anteriors from moving back and the alternative is to leave them in a retracted position. So "it is what it is" so to speak!

I feel the advantage of my plan is that i will finish with my lower incisors and upper incisors at the position we aimed for.

I know this is a high angle case so i can place a step down bend on the wire mesial to the lower 6 to prevent the lower molar from extruding with the class II elastics. Plus the elastics shouldnt be in place more than a few months so i dont think the vertical effects will be too bad...do you agree?

My critique of the other treatment plan that called from maximum anchorage in the upper arch is that it takes into account that the lower anteriors will retract while closing the lower space. So this treatment will finish with lower incisors posterior to their original starting position and upper incisors retracted to this posterior lower incisor position. We thus fail to meet our objectives.

I would love to know what you all think of my logic and whether you feel i am correct in my thinking?

Thanks,

Peter.

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[Dr. Dai Phan]

Are you speaking English? DP

 

[Orthoresma]

thanks for constructively contributing

 

[Dr. Dai Phan]

thanks for constructively contributing

You are welcome. The ideal occlusion for natural dentition is all simutaneous contacts of functional cusps to marginal ridges in Centric Relation and Maximum Intercuspation. Anterior couplings from #6-11 and canine rise or anterior guidance in protrusive and lateral excursions. The incisal guidance should be no more than 15 degrees of the condylar inclination. DP

 

[BlueToothHunter]

How is her maxilla related to her cranial base?
How does she look in her soft tissue/hard tissue numbers?
Would you want to improve her facial profile?
How does she look when she smiles?
____________________________________________
Without looking at any clinical photos or models... it is hard to offer any realistic suggestions... but here it goes anyway.

Given that her profile was retrognathic (6mm OJ), Molars were class II, lower arch crowding...

Extract lower first bicuspids
Close the extraction spaces using maximum anchorage
Mandibular advancement surgery (+/- sliding genioplasty)
(or depending on your surgeon, sub-apical mandibular body osteotomy)

If pt wants non-surgical, it would have to be four first bicuspids extraction and maximum anchorage (A+) in the upper using temporary anchorage devices (TADs) and B anchorage in the lower arch.

How is her TMJ? Is her CO=CR?

This will require a good patient management!

 

[Orthoresma]

Thanks blue tooth.

But i need to ask you about why it is B anchorage in the lower arch?? Surely it is minimal (type C)...ie we want to protract the lower molar forward??

Another question is this,

If we drag the lower molar forward and end up retracting the lower anteriors despite reinforcing lower anterior anchorage, why cant we then run some class II elastics to push the lower anteriors forward the amount they retracted during space closure. eg if the lower anteriors retracted 2mm, use class II elastics to push them forward 2mm!.

This way i meet the objective of maintaining the lower incisor position and do not need to use maximum anchorage in the upper arch.

What do you think about this?

Cheers.

 

[BlueToothHunter]

Thanks blue tooth.

But i need to ask you about why it is B anchorage in the lower arch?? Surely it is minimal (type C)...ie we want to protract the lower molar forward??

OK, B-/C+ anchorage. If you used bidimensional technique then it might be easier. You can use class II elastics too. Just watch out for lengthening your upper incisor segment. How does she look with OB? Is she starting off as deep overbite?

Another question is this,

If we drag the lower molar forward and end up retracting the lower anteriors despite reinforcing lower anterior anchorage, why cant we then run some class II elastics to push the lower anteriors forward the amount they retracted during space closure. eg if the lower anteriors retracted 2mm, use class II elastics to push them forward 2mm!.

This is called round-tripping. It's highly inefficient mechanics and it's best not to do or treatment plan this way. There is a greater chance for root resorption and especially when the periodontium is compromised (thin gingiva) I would not recommend this plan. Class II elastics can be used for upper 4/ lower 5 extraction pattern. But you will get eruption of the lower molar (as you pointed out) and simply placing gingival bends in the arch wire won't be enough to control your vertical, in my opinion. Given your high MPA, I would try to maintain your vertical, not increase it.

This way i meet the objective of maintaining the lower incisor position and do not need to use maximum anchorage in the upper arch.

What do you think about this?

If you want to maintain your lower incisors where they are, you should retract the canines separately before you retract the lower 2 to 2. That way, you will be staying off the lower incisors and not upright them too far or procline them. Also, consider referring to the periodontist prior to bonding for gingival grafting to increase the keratinized ginigval band surrounding the lower incisors. You'll be glad that you did. Cover your A$$!

Cheers.

 

[Orthoresma]

I thought she had half step class II? How much mesial movement do you need to make it class I? This you will have much better idea since you could see the lower arch occlusogram... anchorage needs are met by what kind of movement you need. So as I said, you could use C-type anchorage. It would probably better than B anchorage since you will be setting up for maximum protraction... sorry to confuse you.

If the patient has a half step class II....this means if the lower molar relocates forward the whole extraction space then the upper has to relocate half the extraction space, Lets say in this case 1 unit = 8mm. So a half unit class II is a 4mm class II and needs 4mm of anterior movement of the lower molar relative to the upper molar to achieve class 1. So if the lower moves forward 8mm, the upper moves 4mm. Now since each premolar is 8mm in width, if we need to move the upper molar 4mm forward and the lower 8mm forward it is type c in lower and type b in upper. Or do you still feel differently???


If you anticipate losing anchorage in the lower, then you are setting yourself up for a B anchorage from the start! Retracting lowers back and pushing them back again is called round tripping. Try to avoid this path of treatment planning! If you used good segmental mechanics or bidimensional mecehanics plans, then you will get maximum anterior anchorage...

yeah i anticipated you would hit back with the "round tripping argument"! Ok, think about this, if we actually end up retracting the lower back inadvertently what can we do??? Either we can accept the retracted lower incisor position or we can try to fix it. Your logic seems to indicate that you would just accept it - if i am not correct. I do not want the lowers incisors to retract, but as no biological system is perfect and if i am not using TAD in lower arch some incisor retraction might occur. If this occurs id rather push them forward with elastics than accept them in a retracted position, which then would require greater upper incisor retraction and type A anchorage as you identified. Could you explain why since our objective was to maintain lower incsior position, why if you inadvertently retracted them depsite all the efforts to avoid this, you would accept it and then retract the uppers even further???


I didn't quite follow your elaboration on the upper anterior needing only 4mm of space. I thought there was 6mm of overjet and you want ideally 1-2mm overjet.

In my department we aim for 2mm overjet, so we need 4mm/quadrant of retraction which is 50% of upper extraction space (2x 8mm premolar).



If you setup for B anchorage in the upper, your molars will get worse to a full-cusp class II. Then your lower molars will need to protract even further to obtain class I occlusion. At best she will stay in half-cusp class II but in your description, "B" anchorage will give you full class II. Listen, you can't say you can "regain the lost anchorage". Once it's gone, it's gone! Try to be more efficient. Maximum anchorage for en masse retratction, or separate canine retraction using segmental mechanics (e.g. TPA, judicious use of Class II elastics, headgear at night only...) As for lower, you can place closing loops closer to the anterior segment in full size rectangular wire. Or, use 018 size brackets in the anterior and then 022 in the posterior segments with elastomeric closing chains.

A half step molar relationship means that if the lower relocates the whole extraction space, the upper needs to relocate half the extrcation space...explained above....so how will using type b cause more than a full step class II????


Are you a first year resident? This is one of the most common treatment plan errors that we come across in the beginning of ortho programs. Talk to your seniors and faculty about how to make your tx plan more efficient. You don't want to keep this lady in braces for more than 36 months...

Im going into 3rd yr and just thinking about mechanics. It seems to me if our objective was to maintain the lower incisor position we would use type c in lower. lets say depsite best efforts we retracted the lower incisor.....and we did type B in upper...we will have overjet remaining right. Why does this overjet occur...because the lower incisors retracted. But we didnt want this to happen. So why not use class II elastics to mesialise them to the correct position?

Cheers.[/quote]

[/quote]


Cheers and thanks for sharing your thoughts!!!!

PS what year in training are you in?

 

[vorosvirag]

Treatment planning over the internet is not ideal.

Orthoresma, are you an ortho resident? Why come to SDN w/ this case?

 

[aphistis]

To the OP: Do you have radiographs and/or models you can post? A picture is worth a thousand words, and even though this is way out of my league, it might help your discussion.

 

[NUKE]

I agree with your anchorage plan; however, this type of case requires a new diagnosis at every visit. It seems you have thought out the reasoning behind the diagnosis. Just take it from here and be willing to change things up every 5-6 weeks. Hope everything goes well.

 

[Jone]

i suggest you post this on DentalTown. there a lot of practitioners on there who post cases, complete with Cephs, models, etc to discuss diagnosis and tx planning. you may also consider joining an ortho study club in your area.

 

[bknight77]

hi peter.well regarding mesializing your lower molars.why do it in the first place?why not just extratct the upper first bicuspids finish the case in a canine class 1 and molar end on.its still a stable occlusion.plus the lower antriors are still upright,the MPA is still where it is and you would get the required esthetic result.

 

[Firm]

You really should post pics on dentaltown. You could extract or not extract depending on the face. Do the lower first PM have root canals, or need endo? Not sure what you meant by endodontically involved. If they need endo, then extract. If extraction means that you are going to end up with 10+ mm to close, you might want to think again. The beauty of a residency is it really doesn't matter what you do, just learn from it.

 

[doc toothache]

Case:
32 year old female with complaint of increased overjet

Overjet 6mm
U1/MxPl 109
L1/MnPl 91
High MPA
Class II Half unit malocclusion
Upper arch well algined
Lower arch has 6mm posterior crowding (3mm per quadrant)
Lower first bicuspids are endodontically involved.
Gingiva and bone overlying lower incisors are thin


I would love to know what you all think of my logic and whether you feel i am correct in my thinking?

Thanks,

Peter.

As others have pointed out it is difficult to critique a treatment plan without at least the advantage of diagnostics casts. However, some generalizations may apply.

With 4 bi extraction whether 1st or 2nd is probably not going to improve the class II relationship. It is not uncommon to see finished cases that are still class II after 4 bi extraction. You didn't say much about the crowding in the lower arch. Is due to misalignment of the premolar, canine, linguoversion? You do indicate that the lower incisors are in an ideal alignment. If you are dead set on the 4 bi extraction approach you may want to consider extracting the lower 2nd bis rather than the 1st. You will at least not have to worry about "dragging" both the second bis and the first molar anteriorly (assuming the 2nd molars are missing). Mesializing molars if going to be a challenge. Tieing the lower anterior is not going to help much in preventing retraction of the anterior segment. If you can resolve the crowding issue on the lower without extraction, you might want to just extract the upper 1st bis. This will obviate the need to advance the mandible forward into class I with class II elastics, (which ortho purists do not like to do) or surgically. No matter how you look at it this is going to be a case requiring some compromise.

There is nothing wrong with your thinking. The problem is that teeth have a mind of their own and are not good at following directions.

 

[ORTHODON]

I think I am abit late in the discussion, However, we would love to know what was decided in the end....