EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

with Class I molar were found to maintain the Class I relationship more that 30
years later. In contrast, the Class II relationships were found to become more
Class II (exhibit greater distoclusion), and the Class III cases shifted significantly
to greater mesioclusion. Harris and Behrents concluded that a Class I molar
relationship was the most stable, while Class II and Class III relationships of
molars rarely self-correct, but likely will progressively worsen over time.
Riedel (1976) questioned the importance of treating all patients to mean
cephalometric parameters as advocated by Tweed (1945) and suggested that the
pretreatment incisor position is likely the most stable position for that particular
anterior segment. Other studies (Shields et al. 1985; Houston and Edler 1990)
have also supported this. Research by Weinstein et al. (1963) and Mills (1966)
suggests that the mandibular incisors lie in a narrow zone of stability in
equilibrium between opposing muscular pressures, and that the pretreatment
labiolingual position of the incisors should be accepted and not altered by
orthodontic treatment (Blake and Bibby 1998). The importance of occlusion also
comes into question when it is realized that a normal posttreatment occlusion
may only be temporary, since the stability of teeth are often influenced by many
factors, such as posttreatment growth that cannot be accounted for. It has also
been realized that a settling of the occlusion usually occurs to some extent
following treatment. Although it is usually anticipated that this posttreatment
settling results in more occlusal contacts and thus a more stable occlusion
(Razdolsky et al. 1989; Sullivan et al. 1991), this certainly cannot occur in all cases
and it has been shown that the degree and amount of posttreatment settling can
vary (Morton and Pancherz 2009).
Sauget et al. (1997) compared the occlusal changes occurring between
patients who wore a Hawley retainer and patients who wore a clear overlay
retainer full-time only for the first three days (except during meals), followed by
nighttime wear only. There was a statistically significant increase in the amount
of settling that occurred in the Hawley group than in the clear overlay group
after three months of retention. There was a mean difference of 6.5 occlusal
contacts between opposing teeth in the two groups. However, the authors did
not elaborate as to whether or not these additional contacts were in the correct
locations.
According to Alexander (2008), ideal occlusal contacts play an important
role in maintaining occlusal stability. Reitan (1959) found that less relapse of
mesiodistal movement occurs in the absence of occlusal stress and parafunction,
suggesting that contact points must be in the correct locations. Dawson (2007, p
12) claimed that, “the use of long-term retainers to maintain post-orthodontic
tooth alignment could be dramatically reduced if occlusal principles were better
understood.” Without stable stops on all teeth when the condyles are in centric
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