Functional Appliances

Question 1

Herbst vs MARA

Answer 1

Both Herbst and MARA:

• Steepen the occlusal plane
• Have headgear effect. Herbst HG effect > MARA HG effect
• Herbst: increase SNB
• MARA: decrease SNA and SNB

Herbst and MARA very similar except MARA has:

1) Less headgear effect
2) Less mandibular incisor proclination
3) Causes more increase in vertical dimension
4) Increase in PFH

Pangrazio-Kulbersh

Question 2

Twin Block

Answer 2

55% skeletal correction / 45% dental correction of molar relation and OJ due to: 1) increase in md length 2) increase in ramus height 3) posterior direction of condylar growth

Best time to use: late mixed dentition/during or slightly after onset of pubertal peak growth velocity
Best FA for controlling md plane angle
*Allows for horizontal growth of mandible = length of md increases

Allows VDO increase by removing acrylic from lower part - FALSE, upper part

Significant long term increase in md body length - FALSE

Significant increase in PFH with removal of acrylic over md molars - FALSE?

Prevention of proclination of lower anterior w/labial bow or acrylic coverage - TRUE

Question 3

Twin Block vs Herbst

Answer 3

Twin Block slightly more effective than Herbst in correcting:

1) molar relationship
2) sagittal skeletal differential/jaw discrepancy/ANB
3) elongation of md ramus