Orthodontic postretention stability and relapse of extraction versus nonextraction and early versus late extraction treatment: review of the literature
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Abstract
This thesis examines the posttreatment stability and relapse in long- and
short-term studies. It attempts to identify potential predictors of relapse by
specifically evaluating the stability and relapse associated with nonextraction
treatment, extraction versus nonextraction treatment, and early versus late
extraction treatment. It provides values for the percent relapse and rate of
relapse of the parameters evaluated and compares the long-term and short-term
studies in order to potentially provide information about the effectiveness or
shortcomings of the various treatment types in maintaining a stable
posttreatment outcome and about the progression of relapse over time.
The results yielded the following findings. Among the significant
posttreatment results, no parameter showed consistency in the posttreatment
outcome with any specific treatment type. The parameters that were found to
undergo the greatest percent relapse were the mandibular intercanine width,
following by mandibular arch length, and mandibular interfirst molar width,
while those with the highest rate of relapse were the mandibular intercanine
width, following by the mandibular arch length, and the mandibular incisor
irregularity. Overall, the long-term studies experienced greater percent relapse
than the short-term studies. On the other hand, greater rates of relapse were
noted in the short-term studies compared to the long-term studies. The rate of
relapse was greater in the extraction patients compared to the nonextraction
patients ( excluding the results for the overbite and the mandibular intersecond
premolar width). In addition, both the percent relapse and rate of relapse were
greater in the late extraction group compared to the early extraction group
(excluding the mandibular intercanine width).
In conclusion, the long-term versus short-term results suggest that relapse
continues to occur several years postretention and suggests that greater relapse
occurs soon after the end of the retention phase and gradually less as time
passes. In addition, the rate of relapse results suggest that nonextraction
treatment is more stable than extraction treatment. Lastly, the percent relapse
and rate of relapse results suggest that early extraction treatment is more stable
than late extraction treatment.
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Copyright by GIUSEPPINA VERDE 2010. This work is being made available in OpenBU by permission of its author, and is available for research purposes only. All rights are reserved to the author.