Cervical vertebrae maturation method:

Poor reproducibility

Daniel B. Gabriel,a Karin A. Southard,b Fang Qian,c Steven D. Marshall,d Robert G. Franciscus,e

and Thomas E. Southardf

Okinawa, Japan, and Iowa City, Iowa

Daniel Gabriel: Major, US airforce, Okinawa, Japan

Karin Southard: Professor, Univerity Iowa

Fang Quan: research scientist, university Iowa

Steven Marshall: visiting associate professor, University Iowa

Robert Franciscus: Associate professor Anthropology, Univeristy Iowa

Thomas Southard: Head of Ortho department, Univeristy Iowa

Am J Orthod DentofacialOrthop 2009;136:478.e1-478.e7 (on-line only)

Abstract by Don McGann, January 2011

What’s this about?

Due to concerns over the amount of radiation exposure taking the wrist x-ray, some have recently suggested that Cervical vertebra C2-3-4 classification of growth stages is enough. So this group decided to setup a study to see if CVM was enough, or the wrist x-ray is still the needed standard to establish the stages of skeletal maturation.

Concepts

  • excellence in orthodontics is predicated on proper management of growth for patients with skeletal jaw discrepancies.
  • The ability to predict future growth would make for better treatment decisions, make for better timing of treatment, appliance selection, extraction patterns, retention and the possible need for surgery. Treatment to optimal results could be tailored for the individual patient and results could be achieved in shorter amounts of time.
  • Some have completely rejected (or given up) on the concept of facial growth prediction
  • Standards have been created for CVM and this has been correlated to the hand-wrist x-ray (Lamparski). He stated that CVM is just as accurate an indicator of skeletal maturity as the hand-wrist x-ray. Others have correlated CVM to mandibular growth.
  • Most of the studies on CVM state that intra-observer reproducibility is 90% or more. In other words, different orthodontists would agree on the classification of maturation stage. But they say most of these studies used tracings of the CVM, not simply looking at the ceph, and some had ‘research-level” skills being the authors of the study. So will this work in clinical practice?
  • CVM clinical guidelines have been established for the treatment of malocclusions (Baccetti), but to make this work, you need to accurately determine the stage of maturation.

The study

They took 10 experienced orthodontists in an average of 19 years in private practice and trained them in the CVM method. They gave them reference materials on CVM classification to use as they classified 30 cephs from untreated patients, cropped so you could only see the CVM were given to each orthodontist to classify the stages. Then they gave them another 30 cases with 2 serial cephs taken within 2 years of each other, for each case, so they had a comparison to help them classify. Last, they had the orthodontists back 3 weeks later, retrained them, mixed up the cephs and had them do it again.

You can see that the classification (Baccetti) is a little different than the one we use. We would classify CS1 and CS2 BOTH as stage 1. Then the others are basically the same, just one number off.

Results:

An orthodontist can be expected to agree with his/her OWN CVM staging only 62% of the time when they look at the same ceph 3 weeks later. Most disagreements were 1 stage apart, but there were many that were 2 stages apart!! 34%. OMG!

Between orthodontists, only 10% of the cases had agreement! Disagreements of 2 or more stages were found 26% of the time! Inter-observer agreement was below 50% (as in flip a coin?).

At the clinical level, CVM staging of maturation should only be used to add to the orthodontists other observations when making clinical decisions.

McGann comments

Whenever an x-ray is taken, it should be the ordering doctor’s responsibility to know that there is a good reason for this and the radiation exposure warrants the information gathered. I am in agreement with the difficulty of classifying growth stages by cervical vertebra, as I have experienced this myself and reviewing cases from others. I have no reason to expect that our POS training would be any better than the training given to the experienced orthodontists in this study, and therefore must expect a similar lack of agreement when classifying cases using CVM. We need more, a protocol for adding the hand-wrist x-ray to the records on our cases.

I also understand the ‘research–level” understanding that is gained by looking at thousands of x-rays and determining the classification. This skill level will be rare in POS. So hand-wrist x-rays will be a part of our system to supplement the CVM method.

In the McGann growth system, it is very important in the cases where growth is added to our diagnosis through the dental vto that we understand the skeletal maturation staging of the patient. Stage 3 is the most important time period, as this when we add growth to ALL patients’ dental vto prediction. Stage 4 is important to determine if the patient is ready for debanding, to improve the retention experience, but there are other ways of doing this (eruption of 7s, start menarche, voice and beard changes, decreasing height velocity). Stage 2 is an important time to identify, and may become more important as the growth system is refined, but do we need a hand-wrist x-ray for this? Not really, since stage 2 is quite easy to determine by CVM (from stage 3).

So let’s define when the hand-wrist x-ray SHOULD be taken when working within the McGann growth system as it stands now, (Chronologic ages since you need to make this decision in the clinic, often without much growth information)

  1. Class III patients
  2. Girls: age 10-12 who show at least stage 2 on CVM, age 11-12 without the availability of the starting ceph to determine stage 2 has been reached. To determine how much extra horizontal growth to add and to manage the timing of treatment.
  3. Girls: age 13-14 to determine if late growth may be coming that will disrupt the final occlusion. Menarche has started, looking at the radius and ulna bone if there is ‘union’ everywhere else. Height measurement information can also be helpful here if you have a history.
  4. Boys: age 12-14.5 who show at least stage 2 on CVM, age 13-14.5 without the availability of the starting ceph to determine if stage 2 has been reached. To determine how much extra horizontal growth to add and to manage the timing of the treatment.
  5. Boys: age 15-16 to determine if lage growth may be coming that will disrupt the final occlusion. Looking a the radius and ulna bone if the hand is already mature. Height measurement information can also be helpful if you have a history.
  6. class II patients
  7. Girls: age 10-12. we will definitely be using growth to help us, so might as well just take the x-ray. You could wait on a 10 year old, but there are a lot of girls that mature early. After menarche starts (on the downward velocity slope), you have generally missed it.
  8. Boys: age 12-14.5. growth will be an important factor included in the diagnosis.
  9. class I patients

Generally we will simply go with CVM and not a wrist x-ray, but the most complete would be to take a wrist x-ray at age 11-12 in girls and 13-14 in boys to better establish stage 3. The importance in establishing stage 3 may be to plan the timing of treatment so that you can deband when you want.

It should be noted that the g6 treatment plans will simply state in additional records to take a wrist x-ray to “better define stages 2-3-4”. This assumes you already have a lateral ceph and have questions about the exact stage of growth.

** Ulna (large bone) and radius, lack epiphyseal union, so late horizontal growth could be coming in this 15 year old boy even thought he hand was fully matured (and growth did continue!!)