Extraoral vs Intraoral Appliance for Distal Movement of Maxillary First Molars

Flashcards summarizing the key points from a study comparing extraoral and intraoral appliances for distal movement of maxillary first molars.

What was the aim of the study?

To evaluate and compare the treatment effects of an extraoral appliance (EOA) and an intraoral appliance (IOA) for distal movement of maxillary first molars using randomized controlled trial methodology.

What were the inclusion criteria for patients participating in the study?

Nonextraction treatment plan, Class II molar relationship, and maxillary first molars in occlusion with no erupted maxillary second molars.

What outcome measures were assessed in the trial?

Treatment time, cephalometric analysis of distal molar movement, anterior movement of maxillary central incisors (anchorage loss), and sagittal and vertical skeletal positional changes of the maxilla and mandible.

How did the treatment time differ between the IOA and EOA groups?

The molars were distalized during an average time of 5.2 months in the IOA group, whereas in the EOA group the corresponding time was 6.4 months (P < .01).

How did the mean amount of distal molar movement differ between the IOA and EOA groups?

The mean amount of distal molar movement was significantly higher in the IOA than in the EOA group, three mm vs 1.7 mm (P < .001).

What impact did the IOA and EOA have on overjet?

Moderate anchorage loss was produced with the IOA implying increased overjet (0.9 mm) whereas the EOA created decreased overjet (0.9 mm).

What conclusion was reached regarding the effectiveness of the IOA compared to the EOA?

The IOA was more effective than the EOA to create distal movement of the maxillary first molars.

What is the purpose of distal molar movement?

To correct a Class II dental malocclusion or to create space in the maxillary arch by a nonextraction protocol.

What are some intraoral devices used for distal molar movement?

Wilson arches, Hilgers pendulum appliances, repelling magnets, and superelastic coils.

What was the force used with the Kloehn cervical headgear (EOA)?

400 g was used for the first two weeks, after which it was increased to 500 g.

How many hours per day were patients instructed to use the EOA?

At least 12 h/d.

What was the average time of use of the EOA?

An average time of 10.8 h/d (SD 0.72).

What components were used in the IOA design?

Bands placed bilaterally on the maxillary first molars and on either the second deciduous molars or first or second permanent premolars, a lingual archwire that united a Nance acrylic button, and Ni-Ti coil springs.

What force was provided by the compressed Ni-Ti coil in the IOA?

Approximately 200 g of maximal force initially, which fell to approximately 180 g as the molars moved distally.

Was there a need for further activation of the coils during the molar distalization period with the IOA?

No, there was no need for further activation of the coils during the molar distalization period.

What skeletal effects can be produced by the EOA using higher forces?

Restricted forward growth of the maxilla.

What advantages does the IOA offer over the EOA?

Higher effectiveness in distal molar movement. Single activation because the Ni-Ti coils demonstrate a wide range of superelastic activity with a small fluctuation of load.

What is a disadvantage of using the IOA for molar distalization?

Anchorage loss or forward movement of one to two mm of the anterior teeth.