EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...
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CHAPTER 3. MATERIALS AND METHODS<br />
Sample Selection<br />
Data consisted of orthodontic records that included facial photographs,<br />
panoramic and cephalometric radiographs, and plaster casts of 236 individuals,<br />
all of whom had received comprehensive orthodontic treatment. Records were<br />
available at three time intervals for each patient: pretreatment (T1), end of<br />
treatment (T2), and at long-term posttreatment recall examination (T3). The<br />
records were collected by Dr. George S. Harris (Menominee, Michigan) from<br />
private practitioners across the North American continent who use standard<br />
Edgewise mechanics and were members of the Charles H. Tweed International<br />
Foundation. With financial support from the Charles H. Tweed International<br />
Foundation, the Tweed Foundation Research Committee was formed. The goal<br />
of the committee was to have every member provide ten sets of records,<br />
including pretreatment, retention, and 10 year post-treatment recall records<br />
(Harris 1985). Members were asked to submit records of cases that were a<br />
minimum of 10 years out of treatment, regardless of treatment outcome. This<br />
would allow the establishment of a broad based sample to describe the quality of<br />
the cases and to allow members to learn from treatment failures as well as<br />
successes. Data files containing these cases were created by Dr. George S. Harris<br />
and Dr. James L. Ferguson. The Foundation’s plan was to evaluate the long-term<br />
orthodontic stability of people treated with standard Edgewise mechanics. These<br />
records (dental casts and cephalograms) were digitized and measured by Donna<br />
Niemczyk with guidance from George Harris and James Ferguson using<br />
DentoFacial Planner ® software (DentoFacial Planner, Toronto, Ontario, Canada).<br />
Cases in the present study (n = 166) were a subset of the larger series<br />
collected by the Tweed Foundation Research Committee. We used just those<br />
cases where, from inspection of the posttreatment casts, there was or was not a<br />
fixed lingual retainer—that is, the posttreatment retention protocol consisted<br />
either of (A) a maxillary Hawley retainer in combination with either a fixed<br />
mandibular canine-to-canine or first premolar to first premolar retainer or (B)<br />
maxillary and mandibular Hawley retainers. Of the original data from 236 longterm<br />
recall study cases received from Dr. George Harris and Dr. James Ferguson<br />
(Figure 3-1), 51 cases were excluded because the recall records did not meet the<br />
minimum 10 years posttreatment criterion, 6 cases were found to still have fixed<br />
retainers in place at the recall appointment, 8 cases did not have recall records<br />
present, 1 case was treated by serial extraction only and received no banded<br />
treatment, and 4 cases were excluded due to incomplete records or uncommon<br />
extraction patterns.<br />
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