View
662
Download
0
Category
Preview:
DESCRIPTION
ORTHODONTICS The art and practice of dentofacial enhancementSpring Summer 2012 Volume
Citation preview
POST-TREATMENT STABILITY IN CLASS II NON-EXTRACTION AND TWO-MAXILLARY
PREMOLAR EXTRACTION PROTOCOLS
G Janson, J Araki, L Camardella
It has been shown that the two-maxillary premolar extraction protocol has a greater
efficiency than the non-extraction treatment of Class II malocclusions (JANSON 2007)
Introduction
Nonextraction 2 premolar extractions
Studies comparing stability of Class II malocclusion treatment with 4- premolar extractions and non-extraction or 2-
premolar extractions have not found any significant difference in stability between
these protocols (UHDE 1983, LITTLE 1988, SADOWSKY 1982, ELMS 1996, JANSON 2004, PAQUETTE 1992, FIDLER 1995, ARTUN 1996, BIRKELAND
1997, JANSON 2009)
Introduction
Similar studies comparing the 2-maxillary premolar extraction protocol long-term
stability to the non-extraction approach have not been performed (MIHALIK 2003)
Recently, only one study showed similar occlusal stability when comparing non-
extraction and the 2-maxillary premolar extraction protocol (JANSON 2010)
Introduction
Introduction
Stability Class II malocclusions treated with 2-maxillary premolar extractions is
considered to be suspicious by some authors.(LOUGHLIN 1952; REITAN 1958; MAILANKODY 2004)
Objective
The purpose of this study was to compare the cephalometric stability of the overjet,
overbite, molar and canine relationships of Class II malocclusions treated with and
without extractions of 2-maxillary premolars.
Material
180 lateral cephalograms of 60 Class II patients evaluated at T1, T2 and T3, with matching characteristics and divided into
2 groups:
Group 1: non-extraction Group 2: 2-maxillary premolar extractions
MethodsSkeletal and dental relationship
measurements
Pretreatment cephalograms (T1)
Posttreatment cephalograms (T2)
Long-term posttreatment cephalograms (T3) – mean of 8.2 years after the end of treatment.
STABILITY EVALUATION =
Long-term posttreatment stage (T3)
MINUS
Posttreatment stage (T2)
The greater the difference, the greater the relapse.
Methods
Table 1 – INTERGROUP COMPARISON: Results of the intergroup compatibility tests (t and chi-square tests)
Group 1 (n=30)Non-extraction
Group 2 (n=30)2- extractions
Mean sd Mean sd pAGE1 (years) 12.14 1.36 12.87 1.49 0.05AGE2 (years) 14.82 1.55 15.40 1.71 0.17AGE3 (years) 21.98 3.38 24.65 4.05 0.01*Treatment time (years) 2.68 1.04 2.53 0.72 0.94Long-term post-treatment time (years) 7.15 3.26 9.25 3.52 0.02*
Sex distribution(Chi-square tests)
Male (n) Female (n) Male (n) Female (n)0.80
14 16 17 13
Results
Group 1 (n=30)Non-extraction
Group 2 (n=30)2- extractions
TREATMENT changes
Growth Pattern Mean sd Mean sd p
FMA -0.30 2.44 0.59 2.33 0.16SN.GoGn -0.43 2.30 -0.21 2.26 0.71SN.OcclPlane -0.11 6.11 -2.19 6.59 0.21
Table 2 – INTERGROUP COMPARISON: Intergroup comparison of treatment (T2-T1) and long-term post-treatment changes (T3-T2)
Results
Group 1 (n=30)Non-extraction
Group 2 (n=30)2- extractions
TREATMENT changes
Dental Relationships Mean sd Mean sd p
Overjet (mm) -5.01 2.85 -4.33 2.47 0.33Overbite (mm) -2.92 1.50 -2.73 2.53 0.73Molar relationship (mm) -4.44 1.20 0.44 0.69 0.00*Canine relationship (mm) -3.80 1.48 -6.02 1.56 0.00*
Table 2 – INTERGROUP COMPARISON: Intergroup comparison of treatment (T2-T1) and long-term post-treatment changes (T3-T2)
Results
Group 1 (n=30)Non-extraction
Group 2 (n=30)2- extractions
LONG-TERM POST-TREATMENT changes
Growth patternMean sd Mean sd p
FMA -0.78 2.61 -2.39 2.99 0.03*SN.GoGn -1.42 2.47 -2.14 2.92 0.31SN.OcclPlane -2.23 6.16 -1.29 6.00 0.55
Table 2 – INTERGROUP COMPARISON: Intergroup comparison of treatment (T2-T1) and long-term post-treatment changes (T3-T2)
Results
Group 1 (n=30)Non-extraction
Group 2 (n=30)2- extractions
LONG-TERM POST-TREATMENT changes
Dental Relationships Mean sd Mean sd p
Overjet (mm) 0.19 0.97 0.55 1.19 0.21Overbite (mm) 0.98 1.07 1.04 1.26 0.83Molar relationship (mm) 0.16 0.77 0.11 0.96 0.82Canine relationship (mm) 0.19 1.35 1.23 1.51 0.00*
Table 2 – INTERGROUP COMPARISON: Intergroup comparison of treatment (T2-T1) and long-term post-treatment changes (T3-T2)
Results
Table 3 – INTERGROUP COMPARISON: Comparison of long-term post-treatment changes (T3-T2) in subgroups with similar post-treatment canine relationship at T2
Results
Group 1 (n=17)Non-extraction
Group 2 (n=16)2- extractions
POST-TREATMENT stageMean sd Mean sd p
Overjet (mm) 3.06 0.88 3.34 0.66 0.31Overbite (mm) 2.26 1.29 1.97 0.99 0.47Molar relationship (mm) -1.24 0.98 4.04 0.65 0.00*Canine relationship (mm) -0.98 0.58 -1.50 0.92 0.06
Table 3 – INTERGROUP COMPARISON: Comparison of long-term post-treatment changes (T3-T2) in subgroups with similar post-treatment canine relationship at T2
Results
Group 1 (n=17)Non-extraction
Group 2 (n=16)2- extractions
LONG-TERM POST-TREATMENT changes Mean sd Mean sd p
Overjet (mm) 0.26 0.80 0.49 0.93 0.46Overbite (mm) 1.06 0.92 1.24 1.07 0.61Molar relationship (mm) 0.34 0.89 0.42 0.95 0.80Canine relationship (mm) 0.21 1.41 0.81 1.39 0.22
Conclusion
Treatment of Class II malocclusion with or without 2-maxillary premolar extractions have a similar long-term
posttreatment stability.
Recommended