Sagittal

  • Distalization of the upper posterior teeth.
  • Class II Elastic Jump — we can prescribe Class II elastic jumps in our ClinCheck plan to simulate the effects of our elastics on a growing teen patient.
  • Extraction of teeth, typically upper first premolars, to correct Class II Malocclusion.
  • IPR — this would be IPR performed in the upper buccal segments to create space for canine retraction into Class I coupling of the incisors when the patient presents with overjet.

These four areas are the non-surgical choices doctors have at their disposal. The next objective is to decide which of these to use to treat a patient’s condition. Here are some resources that doctors might find helpful:

“Correction of Class II Malocclusion with Class II Elastics: A Systematic Review by Janson et.al, March 2013, American Journal of Orthodontics and Dental Facial Orthopedics (AJODO.) — the authors start- ed by examining over 400 papers devoted to the topic of correction of Class II Malocclusions. Out of those 400 articles they selected 11 papers that fit their criteria. Four of the papers looked at the effects of Class II elastics alone in correcting malocclusion. The other seven papers com- pared the effects between Class II elastics and another method to cor- rect Class II Malocclusion — for example, fixed-functional appliances.

Now to examine the four papers on “elastics alone”:

  • Nelson Associates, 1999
  • Meistrell Associates, 1986
  • Tovstein, 1955
  • Combrink Associates, 2006

The authors concluded: Class II elastics are effective in correcting Class II Malocclusion through a combination of dento-alveolar and skeletal effects. The effects of Class II elastics in patients are:

Restraint of maxillary growth — the studies showed that in patients treated with Class II elastics the maxillary first molar tended to maintain its antero-posterior position at the same time that the SNA angle was reduced. In a sense, Class II elastics achieve a headgear effect.

Small amount of additional mandibular growth — the authors also found that when compared to untreated patients one could expect 1.2mm additional mandibular growth. Dentoalveolar effects — as far as the dental effects were concerned the studies found an average of 5.8mm overjet reduction. In summary, the authors concluded that Class II elas- tics work through 63 percent dental change in position of the teeth, and 37 percent were attributed to skeletal changes (e.g., headgear effect and a small additional contribution to mandibular growth).

Note: Because 37 percent of the sagittal correction can be attributed to skeletal change, I do not recommend using Class II elastic-jumps in non-growing adult patients. I don’t expect skeletal change, and that is why I feel it’s much less predictable in adults using Class II elastics than a growing teen patient.

The authors didn’t find any significant deleterious side effects with the use of CL II elastics. When they looked at vertical changes in both the maxilla and the mandible were within normal ranges. No significant change in occlusal or mandibular plane was observed.

Summary: My interpretation of this paper is that Class II elastics are safe and effective in correction of Class II malocclusion in growing teen patients.

CLASS II ELASTICS VS. FIXED-FUNCTIONAL APPLIANCES

The other seven articles compared the effects of CL II elastics to fixed-functional appliances. The seven articles are:

Serbesis-Tsarudis and Pacherz, 2008

Jones et al, 2008

Nelson et al, 2007

Uzel et al, 2007

Nelson et al, 2000

Ellen et al, 1998

Gianelly et al, 1984

Here is a summary of what those seven articles collectively described: Class II elastics are similar to the effects of fixed-functional appliances in the long term, placing two methods close to each other when evaluating treatment effectiveness. In other words, both functional appliances and Class II elastics are safe and effective at correcting Class II malocclusion.

Class II Elastics Protocol Specifics:

Based on this research, I use the following elastic protocol for routine correction of Class II malocclusion for growing teen pa- tients (image 6-1). Notice precision cut elastic hooks on the upper 3’s and the lower 6’s (for attaching Class II elastics) in addition to a 3mm-long, occlusally-beveled, rectangular attachment placed on the lower 6’s act as retention to prevent the aligner from dislodg- ing from the vertical component of force from the Class II elastics.

Note: If you prefer a button bonded to the lower molars, prescribe a cutout on the lower 6’s instead of an elastic hook.

Step 1: Place attachments at the first visit.

Note: If you choose not to place the attachments at the first visit, don’t start Class II elastics until you’ve placed the attachments. The aligners are not retentive enough to withstand the pull of the Class II elastics without attachments.

Step 2: Start with light elastics (1/2” 2 oz.)

Step 3: I’ll increase up to heavy (1/2” 4 oz.) — if necessary. I’ll do this in cases where the Class II discrepancy is greater than 3mm or if the teeth or the malocclusion doesn’t seem to be progressing toward Class I within a reasonable amount of time, which would be four to six months.

On the Invisalign prescription form, see no. 4 on your prescription: Anterior-Poster (A-P) Relationship.

See Correction to Class I. Click on the two radial buttons directly across on that row — click radial buttons R and L.

Next, click on radial button: Tooth Movement Options. Click on square button: Class II/III Correction Simulation (Elastics Required).

See “Precision Cuts — may compromise aligner strength and dura- bility” and below it reads Yes or No, click on Yes (image 6-2).

CASE STUDY NO. 1 — ABBY

Abby presented as a 16-year-old female with a Class II, Division I Malocclusion in the permanent dentition. She has a normal overbite and a large overjet, mild upper and lower crowding, a V-shaped maxillary arch, and a normal profile (images 6-3 through 6-5). Her case will be an example of a case where we prescribe a Class II elastic-jump. Her skele- tal pattern is normal. Her cephalometric radiograph reveals protrusive maxillary anterior teeth and a normal skeletal pattern. Her panoramic radiograph is normal. The SAGITTAL section of the ClinCheck list for Abby looks like this:

TREATMENT PLAN

A Class II elastic-jump was prescribed to address the sagittal discrepancy. A CL II elastic-jump is a ClinCheck simulation that occurs at the last stage to simulate the correction of the malocclusion Class I in order to determine if the final occlusion is acceptable. Four oz. elastics were selected​ in this case due to the large amount of sagittal correction required to achieve CL I.

CLINCHECK TREATMENT PLAN

As you can see in Abby’s ClinCheck plan, there are precision-cut hooks on the U3’s and L6’s, along with retentive 3mm-long, occlusal- ly-beveled, rectangular attachment on the lower 6’s. Also note the CL II elastic jump (image 6-6).

Here are pictures (image 6-7) of Abby in treatment wearing her aligners and using 4oz. 1/2” elastics. As is typical for my Invisalign Teen patients, her hygiene is excellent, her tracking looks good, and she is progressing normally.

Note: Abby was going into her senior year of high school and she was a dancer and performer. She told her parents that if she couldn’t be treat- ed with Invisalign clear aligners she would rather keep her overbite and malocclusion the way it was previous to treatment. Therefore, for Abby’s case Invisalign treatment was the only option. When she came to my office, I told her parents she would be an excellent Invisalign candidate provided that she was compliant. She had to wear her aligners and elas- tics the required 22 hours per day — and I was confident we could get her case corrected. Most teens are compliant because they are motivated. If you treat enough teens with Invisalign you start to realize that in the teenage population, it is just as much about psychology as it is biology. If they are motivated, as in Abby’s case where she didn’t want to go into senior pictures or the prom wearing braces, this motivation keeps her wearing her aligners and elastics and makes her a terrific patient.

Progress

One year into treatment you can appreciate Abby’s progress (image 6-8) with her Class II Malocclusion. She’s not quite Class I yet, but she is pro- gressing well. Continuing on through 16 months of treatment the progress (image 6-9), you can see her sagittal correction continues to improve.

RESULTS

At the end of treatment (images 6-10 through 6-12) her malocclusion has been corrected from Class II to Class I. She has excellent arch align- ment and normal overbite and over-jet with excellent esthetics. Her final panoramic radiograph is normal. Comparing her initial cephalometric radiograph to her final you can see significant change to the position of the upper incisors, and significant retraction and resolution of her overjet. She has excellent smile esthetics.

Summary: Total treatment time is 22 months, 25 aligners, 20 refine- ment aligners, and 4 oz. Class II elastics.

CASE STUDY NO. 2 — EMMA

Emma (images 6-13 through 6-15) presented as a 12-year-old female in the late mixed dentition. She has a Class II, Division I Malocclusion; she has a deep overbite; upper and lower crowding and severe lingual inclination of the upper and lower anterior teeth. If you look at image 6-13, you can appreciate the significant amount of lower incisor crowd- ing. Her right and left lower incisors are blocked out to the lingual. We can also observe her deep overbite as well as the lingual inclination of the upper and lower anterior teeth. Her panoramic radiograph is within normal limits and her cephalometric radiograph reveals a mild hypodi- vergent skeletal pattern and upright upper and lower incisors.

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May 6, 2017 | Posted by in Orthodontics | Comments Off on Sagittal
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