This study compared the long-term stability of Class II malocclusion treatments with and without extraction of two maxillary premolars. 60 patients were divided into two groups - one treated with non-extraction and the other with extraction of two premolars. Cephalograms were taken before, after treatment, and 8 years post-treatment on average. The results showed similar stability between the two protocols for overjet, overbite, and canine and molar relationships over the long-term. However, the extraction group showed greater counterclockwise rotation compared to the non-extraction group. The conclusion was that both protocols provide similar long-term stability for treating Class II malocclusions.

1. POST-TREATMENT STABILITY IN CLASS II
NON-EXTRACTION AND TWO-MAXILLARY
PREMOLAR EXTRACTION PROTOCOLS
G Janson, J Araki, L Camardella

2. Introduction
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)
Nonextraction 2 premolar extractions

3. Introduction
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)

4. 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)

5. 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)

6. 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.

7. 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

8. Methods
Skeletal 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.

9. Methods
STABILITY EVALUATION =
Long-term posttreatment stage (T3)
MINUS
Posttreatment stage (T2)
 The greater the difference, the
greater the relapse.

10. Results
Table 1 – INTERGROUP COMPARISON:
Results of the intergroup compatibility tests (t and chi-square tests)
Group 1 (n=30) Group 2 (n=30)
Non-extraction 2- extractions
Mean sd Mean sd p
AGE1 (years) 12.14 1.36 12.87 1.49 0.05
AGE2 (years) 14.82 1.55 15.40 1.71 0.17
AGE3 (years) 21.98 3.38 24.65 4.05 0.01*
Treatment time (years) 2.68 1.04 2.53 0.72 0.94
Long-term post-
7.15 3.26 9.25 3.52 0.02*
treatment time (years)
Sex distribution Male (n) Female (n) Male (n) Female (n)
0.80
(Chi-square tests) 14 16 17 13

11. Results
Table 2 – INTERGROUP COMPARISON:
Intergroup comparison of treatment (T2-T1) and long-term post-
treatment changes (T3-T2)
Group 1 (n=30) Group 2 (n=30)
Non-extraction 2- extractions
TREATMENT changes
Growth Pattern
Mean sd Mean sd p
FMA -0.30 2.44 0.59 2.33 0.16
SN.GoGn -0.43 2.30 -0.21 2.26 0.71
SN.OcclPlane -0.11 6.11 -2.19 6.59 0.21

12. Results
Table 2 – INTERGROUP COMPARISON:
Intergroup comparison of treatment (T2-T1) and long-term post-
treatment changes (T3-T2)
Group 1 (n=30) Group 2 (n=30)
Non-extraction 2- extractions
TREATMENT changes
Dental Relationships
Mean sd Mean sd p
Overjet (mm) -5.01 2.85 -4.33 2.47 0.33
Overbite (mm) -2.92 1.50 -2.73 2.53 0.73
Molar 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*

13. Results
Table 2 – INTERGROUP COMPARISON:
Intergroup comparison of treatment (T2-T1) and long-term post-
treatment changes (T3-T2)
Group 1 (n=30) Group 2 (n=30)
Non-extraction 2- extractions
LONG-TERM POST-TREATMENT changes
Growth pattern
Mean 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 0.31
SN.OcclPlane -2.23 6.16 -1.29 6.00 0.55

14. Results
Table 2 – INTERGROUP COMPARISON:
Intergroup comparison of treatment (T2-T1) and long-term post-
treatment changes (T3-T2)
Group 1 (n=30) Group 2 (n=30)
Non-extraction 2- extractions
LONG-TERM POST-TREATMENT changes
Dental Relationships
Mean sd Mean sd p
Overjet (mm) 0.19 0.97 0.55 1.19 0.21
Overbite (mm) 0.98 1.07 1.04 1.26 0.83
Molar relationship (mm) 0.16 0.77 0.11 0.96 0.82
Canine relationship (mm) 0.19 1.35 1.23 1.51 0.00*

15. Results
Table 3 – INTERGROUP COMPARISON:
Comparison of long-term post-treatment changes (T3-T2) in subgroups
with similar post-treatment canine relationship at T2
Group 1 (n=17) Group 2 (n=16)
Non-extraction 2- extractions
POST-TREATMENT stage
Mean sd Mean sd p
Overjet (mm) 3.06 0.88 3.34 0.66 0.31
Overbite (mm) 2.26 1.29 1.97 0.99 0.47
Molar 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

16. Results
Table 3 – INTERGROUP COMPARISON:
Comparison of long-term post-treatment changes (T3-T2) in subgroups
with similar post-treatment canine relationship at T2
Group 1 (n=17) Group 2 (n=16)
Non-extraction 2- extractions
LONG-TERM POST-TREATMENT changes
Mean sd Mean sd p
Overjet (mm) 0.26 0.80 0.49 0.93 0.46
Overbite (mm) 1.06 0.92 1.24 1.07 0.61
Molar relationship (mm) 0.34 0.89 0.42 0.95 0.80
Canine relationship (mm) 0.21 1.41 0.81 1.39 0.22

17. Conclusion
Treatment of Class II malocclusion
with or without 2-maxillary premolar
extractions have a similar long-term
posttreatment stability.