Module 5 Case 2 Prompt 5

[Chad Carter (Course Director)]

Lily,

This is referring to the “high-pull headgear effect” of Herbst. Sometimes I think of a Herbst as a non-compliant head-gear functional appliance.

There is opening of the anterior bite but it’s not from extrusion of the 6s. It comes through holding/intruding in the maxilla and proclining the lower incisors which open the bite.

Studies have shown that the intrusion of the 6s is not a long-term effect and that after discontinuing the Herbst they extruded unless there is a fullcoverage (Essix) form of retention.

Does that make sense?

Thanks

CBC

[Maria]

Jumping into this discussion. I also had the same problem thinking that functional appliances cause extrusion of maxillary molars and clockwise rotation of the mandibular plane opening the bite.

Could you please share if there is any source which we could refer to for this intrusion of molars with Herbst appliance?

[Chad Carter (Course Director)]

From the ABO Boards Reading list:

Treatment and posttreatment effects induced by the Forsus appliance: A controlled clinical study

Giorgio Cacciatorea; Luis Tomas Huanca Ghislanzonib; Lisa Alvetroc; Veronica Giuntinid; Lorenzo Franchie

This article refers to the effect and then has other sources it sites about the herbst specifically. It discusses functional appliances. It was article 74 on the list last year I believe.

[Maria]

Thank you so much for the reference!

I am attaching here the table with their findings and am I reading it wrong?

Sorry, I still cannot see the intrusion of maxillary molars. Isnt it positive values there in the table indicating extrusion of U6s? And the decrease on mandibular plane values in the table is bigger in the control group and almost zero in the functional appliance group, wouldnt that indicate a mild tendency of clockwise rotation with functional appliance therapy?

[Chad Carter (Course Director)]

It was not measured on their table. It’s written in the article. They were measuring different items in the study.

FROM ARTICLE:

This ‘‘headgear effect’’ has been described for both fixed rigid functional applianc- es (Herbst10,33 and MARA11,14)

So you can read this other article for further understanding: They all discuss that molar intrusion is a characteristic feature of the Herbst.

Interarch Maxillary Molar Distalization Appliances
for Class II Correction
MARK E. BERKMAN, DDS, MS
ANDRE HAERIAN, DDS, PHD
JAMES A. MCNAMARA, JR., DDS, PHD

or

McNamara, J.A. Jr.; Howe, R.P.; and Dischinger, T.G.: A comparison of the Herbst and Fränkel appliances in the treatment of
Class II malocclusion, Am. J. Orthod. 98:134-144, 1990.

[Maria]

Got it!

I will check the other articles!

I thought the headgear effect that they discussed in Cacciatore et al article was just discussing the decrease in SNA. But good to know! Thank you again 🙂