Crowding and third molars

[JesseBrad3]

So last week I was surprised to hear while sitting on a local study club for dentists that apparently third molars don't actually cause crowding. They explained that the amount of force created by the thirds coming in is too small to cause major ortho shifts, which makes sense. Any thoughts, comments?

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[Blue Tooth]

Yeah that's right. It was the common held belief and one of the reason given for extraction of thirds. We were taught that by Lysle Johnston, one of the ortho bigges, and what he said was there was mounting evidence for crowding of lower anteriors as we age from the anterior component of force. Basically as we bite, the force is directed mesially, not distally. And over time, this mesial force pushes everything anteriorly, hence crowding.

 

[toothie]

i had a perfect set of teeth with no crowding till my third molars tried erupting .
i agree with what ure saying but is it posssible that even by the age of 18 there is adequate stress on the teeth to cause minor anterior crowding , or it coincidental that the the crowding and eruption happened simultaneously ...

 

[SPBest]

Here an Nova they drill that into our head that thirds do not cause crowding. Can anyone at UNC tell us what Dr Proffit has to say on the matter?

 

[JesseBrad3]

Does growth spurts, or continued growth into adulthood, play any part in crowding since the jaw and teeth are still developing and going under change?

 

[DcS]

The explanation to your question, as taught to me by Dr. Proffit, is called "late mandibular growth". The mandible in many cases continues to grow into 20s and in some people 30s. As the mandbile continues to grow, there is a compensatory retroclining of the mandibular incisors (they tip back) in an attempt to maintain their relationship with the upper incisors. When they retrocline, there is a loss of arch space and the end result is crowding.

 

[toofache32]

The explanation to your question, as taught to me by Dr. Proffit, is called "late mandibular growth". The mandible in many cases continues to grow into 20s and in some people 30s. As the mandbile continues to grow, there is a compensatory retroclining of the mandibular incisors (they tip back) in an attempt to maintain their relationship with the upper incisors. When they retrocline, there is a loss of arch space and the end result is crowding.

I knew the answer was "late mandibular growth" but I didn't know all the theory behind it. I think there is a huge coincidence because this spurt often happens around age 19-20....which is also when your third molars are coming in.

You have to remember that coincidence is not science. This is where "old wives' tales" come from. When my wife was pregnant, another girl actually said to her, "I didn't like strawberries while I was pregnant and I had a girl. If you don't like strawberries you'll probably have a girl also." These things are easily perpetuated when it's 50/50 (girl/boy).

I had my thirds out when I was 16, went through full ortho, and I still had lower anterior crowding around age 20.

 

[DcS]

I knew the answer was "late mandibular growth" but I didn't know all the theory behind it. I think there is a huge coincidence because this spurt often happens around age 19-20....which is also when your third molars are coming in.
.

FYI...not trying to pick a fight, but want to clarify something. Late mandibular growth isn't a "spurt", it is simply continuous growth through puberty and past puberty. It's not synonymous with a growth spurt, where there is accelerated growth. It simply keeps on growing at a slow rate.

 

[toofache32]

FYI...not trying to pick a fight, but want to clarify something. Late mandibular growth isn't a "spurt", it is simply continuous growth through puberty and past puberty. It's not synonymous with a growth spurt, where there is accelerated growth. It simply keeps on growing at a slow rate.

Sounds good to me. I stand corrected.

 

[tx oms]

Sounds good to me. I stand corrected.

Stupid (sorry, cheap shot)

 

[VancouverDoc2b]

The explanation to your question, as taught to me by Dr. Proffit, is called "late mandibular growth". The mandible in many cases continues to grow into 20s and in some people 30s. As the mandbile continues to grow, there is a compensatory retroclining of the mandibular incisors (they tip back) in an attempt to maintain their relationship with the upper incisors. When they retrocline, there is a loss of arch space and the end result is crowding.

Based on your explanation it seems that anterior crowding is inevitable, even AFTER orthodontic treatment. If this continues into your 20s or 30s, what is the appropriate treatment? Will people have to do ortho all over again?? Extractions?? Surgery?? Or are there other reasonable treatment options.

 

[SPBest]

Based on your explanation it seems that anterior crowding is inevitable, even AFTER orthodontic treatment. If this continues into your 20s or 30s, what is the appropriate treatment? Will people have to do ortho all over again?? Extractions?? Surgery?? Or are there other reasonable treatment options.

Lingual bonded retainers are great, if the pt. has good hygiene.

 

[saahakhan]

will 3rd molar cause crowding in anterior teeth if its crown is directed mesially and is placed horizontally??

 

[toofache32]

Stupid (sorry, cheap shot)

...I had it coming...

 

[JesseBrad3]

The orthodontist who brought up the issue said that wearing your retainer occasionally through adulthood should prevent inevitable crowding. He went on to say he prefers not to use bonded retainers except in cases where the patient is non-compliant with wearing their retainer. Problem is he said, is that the kids who don't wear their retainer also are usually the ones with the worst hygiene.

 

[DcS]

will 3rd molar cause crowding in anterior teeth if its crown is directed mesially and is placed horizontally??

No, it can never generate enough force to effect the anteriors.

 

[DcS]

Based on your explanation it seems that anterior crowding is inevitable, even AFTER orthodontic treatment. If this continues into your 20s or 30s, what is the appropriate treatment? Will people have to do ortho all over again?? Extractions?? Surgery?? Or are there other reasonable treatment options.

As has been mentioned, either a removable or bonded retainer. Once it happens, the tx depends on the degree. In many cases, the incisors can be disked (sides shaved off very slightly), and then have a retainer made to guide them back into ideal placement. If they have shifted a lot, ortho will be needed.

 

[DrJeff]

Overall I'd say that this topic is the 2nd biggest dental myth out there in the general population. Myth #1 hands down is the patient who says "I have cavities because my teeth are soft"

As for the research aspect, this topic and a significant lit review and retrospective case analysis made up about 50 pages of my wife's masters thesis during her ortho residency. Short version as I tell it to patients is "it's not your wisdom teeth, its plain and simply that you're getting old!

True story, I had a female patient in her mid thirties. I was doing the hygiene check on her (she'd been a regular patient of my partner for 15 years and he was out of the office that day). She said to me "I'm getting a wisdom tooth since my bottom front teeth are getting crooked" After showing her the set of radiographs(including a panorex) that had been taken 30 minutes before, I asured her that she was not getting a wisdom tooth, and then talked about in general terms mesial drift, etc. She became quite adamant that she must be getting a wisodm tooth or that it must be a result of her wisdom teeth in the past. I then looked back through her chart, and low and behold what did I see in her inital exam chart entry with respect to her wisdom teeth "congenitally missing #'s 1,16,17,32"

The funny yet true thing about this, is that you will see situations similar to this (and even more outrageous/ humorous) the longer that you practice!

 

[DcS]

Overall I'd say that this topic is the 2nd biggest dental myth out there in the general population. Myth #1 hands down is the patient who says "I have cavities because my teeth are soft"

Yup, had that occur yesterday. 30 y/o female, we tx planned full upper extractions for a full, and lower posteriors for a partial. She told me that "gosh darn my grammy and mamma took care of their teeths, but dem sure got dem cavities. we've always said we got dem soft teeths that fall apart cause they be weak".

 

[DrJeff]

Yup, had that occur yesterday. 30 y/o female, we tx planned full upper extractions for a full, and lower posteriors for a partial. She told me that "gosh darn my grammy and mamma took care of their teeths, but dem sure got dem cavities. we've always said we got dem soft teeths that fall apart cause they be weak".

The best one's with "soft teeth" are those that come in and have either:
1) Kool-aid tongue (kids and teens with "soft teeth")
2)The bottle of Coke/Pepsi/Mt Dew that the put down in the operatory
3)The extra, extra large extra, extra, extra,extra,extra light and sweet vat of coffee that they put down in the operatory

When these patients ask me what will happen to their teeth if they don't kick their sugar habit, I look them in the eye and tell them "you'll be making multiple really nice contributuions to my new boat fund!"