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Effects of adenoidectomy on dentition and nasopharynx
American Journal of ORTHODONTICS Volume 65, Number
ORIGINAL
Effects of adenoidectorny and nasopharynx Sten Under-Aronson, Orebro, Sweden
1, January,
1974
ARTICLES
on den&ion
D.D.S., Ph.D.
A
denoids and the mouth breathing which they induce are associated with a narrow upper arch, a high incidence of cross-bite or a tendency to crossbite, retroclined upper and lower incisors, and small sagittal depth of the nasopharynx.3 A narrow upper arch and high frequency of cross-bite among children with large adenoids were judged as parallel phenomena to the narrow facial type of these individuals, along with a small nasopharyngeal cavity and narrow nose. There may also be some causal relationship between the width of the upper arch and the mouth breathing and low tongue position associated with adenoids. The retroclination of upper and lower incisors in the mouth breathers was interpreted in the same study as a consequence of increased tension in the lip musculature due to the mouth being kept open. A small nasopharyngeal space in conjunction with adenoids is usually followed by mouth breathing. Thus, the size of the nasopharynx is considered to be uninfluenced by whether breathing occurs through the nose or through the mouth. The question of whether a causal relationship exists between adenoids plus mouth breathing on the one hand and, on the other, the dentition and a small nasopharynx in particular is best approached by means of longitudinal studies of conditions before and after adenoidectomy. The purpose of the present study was to determine whether adenoidectomy (and hence a change to nose breathing) is followed by (1) a change in the From the Stockholm,
Orthodontic Sweden.
Department,
Odontologic
Faculty,
Karolinska
Institutet,
1
Am. J. Orthod. Janunry 1974
Table
I. Group
means
for
angle
of upper
incisors
to
nasion-sello
line
initially
and
1 year
later
Group
Initialljy
Controls Adenoidectomy children Difference between the groups’ t value “Significance
at 1 per
“““Significance
+ 1.13
37
104.82
t 3.14
37
+ 0.29 + 0.26
37
1.11
100.53
t 1.08
37
102.55
5 1.10
37
+ 2.03 ? 0.56
3i
3.64”“”
4.00 + 1.56 2.56”
at 5 per
““Significance
104.53
cent cent
:tt 0.1 per
2.27 t 1.58 1.43
- 1.74 rt 0.62 - 2.79””
- 2.79=
level. level. cent
level.
inclination of upper and lower incisors, (2) a change in the width of the upper arch, (3) an effect on the sagittal depth of the bony nasopharynx. Material
and
methods
The study was made on the clinical ma.terial presented in an earlier work.” For the present investigation the children have been divided into two groups only-the thirty-seven who underwent adenoidectomy and thirty-seven controls. All the children were at least 8 years old, and their upper and lower incisors had erupted before the initial examination, which was followed by adenoidectomp. A second examination was made 1 year later. The variables are the same as were used in the previous study.” Radiographic analysis. Lateral ra.diographs taken initially and 1 year later were used to measure the inclination of upper and lower incisors (A 46 and A 48, respectively) and the sagittal depth of t,he bony nasopharynx (A 92) from the reference points and lines reported in 1970, using the same apparatus, settings, and film.” Amlysis from casts. The following measurements were ma.de on plaster models produced from impressions of the upper and lower arches taken in “Tissuetex” alginate material : 1. Width of upper and lower dental arches between first molars (A 49, A 50). 2. Transverse relationships between the jaws were expressed by means of the relationship between the widths of the lower and upper dental arches. Index values close to 100 denote cusp-to-cusp dentition and higher values denote cross-bite : Arch width MI - MI lower (A 50) x loo (A 63) Arch width M, - M, upper (A 49) Dental arch width was measured (to within t 0.1 mm.) with sliding calipers at the first molars in accordance with the method of LundstrGm.” XWisCical methods. Means and standard deviations were calculated from values for the variables in the adenoidectomy and control children. The differences between group means were tested for significance with the t test.
Efects Table
II.
children
Change who
Mode InitiaZZy -
after
II
NO%3
Nose Mouth
III.
cent
Correlations Change
angle
of
upper
incisors
(A
46)
later
I
t calue
,
3.58 1.96 1.25
in thirty-seven
,
2.07 2.53” 2.04
No. of children 6 23 8
level. between
after
in mean A 46 (degrees)
for
2 year
at 5 per
mean
3
Change
of breathing
Mouth Mouth
Table
in
adenoidectomy
adenoidectomy
Nose
*Significance
1 year
underwent
of
changes
1 year Upper
1 year
Mode of breathing (unchanged from mouth to nose = - 1) Size of adenoids (A 32)
after
=
0, switch
in&or/Nasion-sella
line
- 0.18 - 0.19
Relationships between the variables were studied with the aid of correlation analysis and multiple regression analysis. An account of the statistical methods will he found in Chapter 5 and the Appendix in the 1970 work of LinderAronson3 Results
Allgle of upper incisors to nasion-selln l&e (A 46). Group means for the angle of the upper incisors to the nasion-sella line initially and 1 year later (1 year postoperatively for the adenoidectomy children) are compared in Table I. Initially the angle of the upper incisors to the nasion-sella line was smaller, on the average, in the children who underment adenoidectomy than in the controls, the difference being significant at the 5 per cent level (p < 0.05). At the follow-up 1 year later, the difference is no longer statistically significant, the closer agreement between the groups being a consequence of a significant increase in the angle of the upper incisors in the children who underwent adenoidectomy. The change in the angle of the upper incisors between the two examinations differs significantly between the two groups (p < 0.01). The children who switched from mouth to nose breathing after adenoidectomv (Table II) display much the same mean change in the angle of the upper incisors as that for the adenoidectomy group as a whole in relation to the controls, though the difference is no more than almost significant (p < 0.05). It will also be seen from Table II that six of the children who underwent adenoidectomy breathed through the nose initially. The change in the angle of the upper incisors for this subgroup does not differ statistically from 0. A change of as much as 11 degrees in one of these children helps to explain why the mean change is as high as 3.58 degrees. In the eight children who were still mouth breathers I year after adenoidectomy, the change in the mean angle of the upper incisors did not differ significantly from 0 either.
4
Linder-Aronson
Table
Am. J. Orthod. January 1974
IV. Regressand:
Change
after
1 year
in angle
Standard
ewor
of upper
incisors
to
nasion-sella
line
(A 46) Reqressor
1
Constant Rz = 0 ; R.S.D.
Table
I
Coefficient
1.1824
I
t value
0.3270
rpartiaz
rmrelntion
-
3.62
zz 2.81
V. Group
means
for
angle
of
lower
incisors
to
mandibular
line
initially
and
1 year
later
No.
Difference after 1 year
No.
t value for diference
1 year Group
Initially
Controls Adenoidectomy children Difference between the groups’ t values “Significance ““Significance “‘“Significance
at 5 per at 1 per
No.
95.31? 88.73
0.97
37
95.74
f. 1.00
37
+0.43
2 0.24
37
1.79
2 1.17
37
90.80
* 1.05
37
+2.07
+ 0.55
37
3.77”“”
6.582 4.33”“” cent cent
at 0.1 per
later
1.52
4.94 + 1.45 3.41””
-1.64 2 0.60 -2.74””
- 2.74””
level. level. cent
level.
correlation analyses of changes after 1 year are shown in Table III for mode of breathing and size of adenoids in relation to the angle of the upper incisors to the nasion-sella line. In neither case was any significant correlation obtained, a result that was presaged by the data in Table II, where the mean change in the angle of the upper incisors in the twenty-three children who switched from mouth to nose breathing after adenoidectomy was significant only at the 5 per cent level. The low correlations also reflect the circumstance that the angle of the upper incisors changed markedly in one child, even though the mode of breathing remained the same in this case after adenoidectomy. SIMPLE
MULTIPLE
CORRELATION
REGRESSION
ANALYSIS.
ANALYSIS.
Simple
REGRESSAND:
CHANGE
AFTER
1 YEAR
IN
ANGLE
(A 46). The analysis presented in Table IV comprises seventy-four persons and the regressand is the variable for the change after 1 year in the angle of the upper incisors to the nasion-sella line. The regressors were the clinical status variable A 15, adenoid variables A 20 and A 32, dentition variable A 48, and skeleton variable A 92. None of these regressors proved to be significant at the 5 per cent level. The total correlation or coefficient of determination (R2) and the standard deviation of the residuals (R.S.D.) are given in Table IV with the regression equation, the standard error of the coefficients, t values, and the partial correlation between the regressand and each of the regressors with allowance made for the other regressors. As none of the regressors included in the analysis attained the 5 per cent level of significance, no explana,tion has been found for the change after 1 year in the angle of the upper incisors to the nasion-sella line.
OF UPPER
INCISORS
TO NASION-SELLA
LINE
Effects
Volume Number
65 1
Table
VI. Change
children
who
after
underment
1 year
1 year
angle
Change
in mean (A 48)
for
VII. Correlations Change
between after
1 year
Mode of breathing Size of adenoids (A 32) “““Significance
lower
incisors
(A
48)
in
thirty-seven
No. of
(degrees)
later
Nose Nose Mouth Nose Mouth Mouth XSignificance at 5 per cent level. ““Significance at 1 per cent level. Table
of
5
adenoidectomy
Mode of breathing Initially
in mean
adenoidectomy
of
1.50 2.13 2.54
changes
after
children
t value
6 23 8
1.63 2.51” 3.58’”
1 year Lower
inctior/.Mandibular
line
- 0.20 - 0.41’“”
at 0.1 per cent level.
Angle of lower incisors to mandibular line (A 48). Group means for the angle of the lower incisors to the mandibular line initially and 1 year later (1 year postoperatively for the children who underwent adenoidectomy) are compa,red in Table V. Initially, the mean angle of the lower incisors to the mandibular line was much smaller in the children who underment adenoidectomy than in the controls, the difference being significant (p < 0.001). At the follow-up 1 year later the difference is still significant, despite the fact that the angle increased very much more in the adenoidectomized children than in the controls. The difference between the changes in the group means after 1 year is significant (p < 0.01). The mean change in the angle of the lower incisors in the children who switched from mouth to nose breathing after adenoidectomy (Table VI) reflects the difference between the adenoidectomy and control groups according to Table V. It is remarkable, however, that the mean change in the eight children who remained mouth breathers after adenoidectomy differs significantly from the initial value. A large part of the difference in this subgroup is attributable to one child. SIMPLE CORRELATION ANALYSIS. Simple correlation analyses of changes after 1 year are shown in Table VII for mode of breathing and size of adenoids in relation to the angle of the lower incisors to the mandibular line. No significant correlation was found between changed mode of breathing and changed angle of lower incisors in relation to the mandibular line, but changed size of adenoids did correlate significantly (p < 0.001) with changed angle of lower incisors. The negative correlation coefficient (Table VII) indicates that the children whose adenoids were reduced in size displayed an increase in the average angle of the lower incisors to the mandibular line. Considering that the relationship between changed size of adenoids and changed angle of lower
6
Table line
Am. J. Orthod. Januarv1974
Limier-Aronsola VIII.
Regressand:
Change
after
1 year
in
angle
of
lower
incisors
to
mandibular
(A 48)
Rearessor
Constant Size of adenoids (A 20), change after 1 year Sagittal depth of nasopharynx (A 92), change after 1 year R* = 0.23 ; R.S.D. = 2.44
Coe#ident
Standard error
0.4653
Partial t value
correlation
0.3950
1.18
-
- 1.1131
0.2461
- 4.52”’
- 0.47
- 0.9645
0.4341
- 2.222
- 0.25
%ignificance at 5 per cent level. x%ignifieance at 0.1 per cent level.
incisors could conceivably be explained via changed mode of breathing, it is surprising that a significant correlation was not obtained between changed mode of breathing and changed angle of lower incisors. A conceivable explanation for the low correlation is that even children who did not change their mode of breathing after adenoidectomy displayed a change in the angle of the lower incisors 1 year after this operation (Table VI). Some uncertainty in the registration of mode of breathing may likewise have contributed to the low correlation. The registration of size of adenoids, on the other hand, was highly reliable. MULTIPLE REGRESSION ANALYSIS. REGRESSAND: CHANGE AFTER 1 YEAR IN ANGLE OF LOWER INCISORS TO MANDIBULAR LINE (A 48). The analysis presented in Table
VIII comprises seventy-four persons, and the regressand is the variable for the change after 1 year in the angle of lower incisors to the mandibular line. The regressors were variables for clinical status A 15, adenoids A 20 and A 32, dentition A 46, A 49, A 53, and A 63, and skeleton A 92. The regressors A 20 and A 92 were introduced first in that order, and none of the others listed above proved to be significant at the 5 per cent level. The results are presented in Table VIII. According to this regression analysis, changed size of adenoids as assessed from lateral radiographs (A 20) provides the largest explanation for the change after 1 year in the angle of lower incisors to the mandibular line. The regression coefficient is significant (p < 0.001) and has the expected sign. The other explanatory variable included in the analysis is the change in sagittal depth of the nasopharynx (A 92)) but here the regression coefficient is no more than almost significant (p < 0.05). The coefficient of determination for the regressors included in the analysis (R* = 0.23) is weak. For A 20 alone, R* equals 0.17, indicating that most of the explanatory value lies in changed size of adenoids. The analysis indicates that the children displaying the greatest reduction in size of a#denoids had the largest increase in the angle of the lower incisors to the mandibular line. This relationship would appear to be indirect, acting probably via altered position of the lips and tongue.
Volume Number
65 1
Table
IX.
EfSects Group
means
for
upper
arch
width
Group
between
first
later
I I
1 year
molars
of adenoidectomy
and 1 year later
initially
t value for
No.
Difference after 1 year
I No.
I
diderence
Controls Adenoidectomy children Difference between the groups’ t values
45.09
f 0.37
37
45.61 + 0.38
37
+ 0.53 f 0.07
37
7.53””
44.15
2 0.46
37
45.03
37
+ 0.88 + 0.10
37
9.10=*=
“Significance
cent
at 5 per
TSignificance
at 1 per
“““Significance
X.
seven
children
Change
width
during
of
Nose Mouth Mouth
in upper
arch
TSignificance
Xl.
at 5 per at I per
(values
1 year
later
Change in mean for (A 49) (mm.)
cent
0.44 0.39 0.18
““Significance
at 5 per at 1 per
first
reduced
molars for
(A 49)
normal
in thirty-
increase
in
t value
No. of children
2.84-” 2.92’= 0.73
8 23 6
level.
cent
level.
between after
cent cent
changes
after
1 year
Mode of breathing (unchanged mouth to nose = - 1) Size of adenoids (A 32) “Significance
between
mm.)
Correlations Change
width
adenoidectomy
Nose Nose Mouth
“Significance
Table
1 year
breathing 1 I
- 3.00””
level.
underwent
1 year-O.53
Mode
- 0.35 + 0.12 - 3.00x=
level.
cent
after who
0.58 + 0.59 0.98
level.
cent
at 0.1 per
Table
Initially
0.94 2 0.59 1.57
2 0.45
7
=
1 year H,-M,
0, switch
from
upper - 0.27’ - 0.37”
level. level.
Width of upper arch between first molars (A 49). Group means for the width of upper arch between first molars initially and 1 year later (1 year postoperatively for the adenoidectomy children) are compared in Table IX. The mean increase in arch width during 1 year amounted to 0.53 + 0.07 mm. in the controls, which differs significantly from 0, and to 0.88 + 0.11 mm. in the adenoidectomy group. The difference between these mean increases-O.36 rf: 0.12 mm. more for the adenoidectomy group-is significant (p < 0.01). The means presented in Table X for the thirty-seven children who underwent adenoidectomy have been reduced by the increase in upper arch width during 1 year for the control group (that is, 0.53 + 0.07 mm.), which has been taken to represent a normal increase at this age (Table IX).
8
Am. J. Ortbod. Januar?/1974
Linder-Aronson
Table
XII.
Change
after
1 year
in upper
arch
width
between
first
molars
(A 49) Pm-tin1
Regressor Constant Size of adenoids (A ZO), change after 1 year Re I 0.16 ; R.S.D. “““Significance Table
XIII.
initially
and
=
“xxSignificance
6.50
- 0.1766 0.50
0.0479
- 3.69”“”
cent
correlation
- 0.40
level. between
lower
and
upper
arch
widths
between
first
molars
later
1 year
later
No.
Difference after 1 year
No.
difference
I! 0.52
37
89.40
2 0.49
37
- 0.45 r 0.14
37
- 3.32*’
92.62 -+ 0.97
37
91.19
? 0.93
37
- 1.43 + 0.21
37
- 6.80”’
89.85
- 2.772 1.10 - 2.52’
at 5 per
t value
No.
Initially
Controls Adenoidectomy children Difference between the groups’ t values
““Significance
value
0.0791
Relationship 1 year
t
error
0.5138
at 0.1 per
Group
“Significance
Standard
Coefficient
cent
at 1 per
0.98 It 0.25 3.87”“”
3.87”’
level.
cent
at 0.1 per
- 1.79 r 1.05 - 1.70
for
level
cent
level.
It will be seen that it is primarily the children who changed from mouth to nose breathing after adenoidectomy who ,display an above-normal average increase, differing significantly from 0 at the I per cent level. At the same time, it is remarkable that the eight children who were nose breathers initially as well as 1 year later also display an above-normal increase in upper arch width, though this is no more than almost significant (p < 0.05). SIMPLE CORRELATION ANALYSIS. Simple correlation analyses of changes after 1 year are shown in Table XI for mode of breathing and size of adenoids in relation to the upper arch width between first molars. The simple correlation analysis in Table XI points to a probable relationship between a change from mouth to nose breathing and an increase in upper arch width between first molars. According to this analysis, then, a change in size of adenoids and probably also in mode of breathing (from mouth to nose) after adenoidectomy is associated with an increase in upper arch width between first molars. MULTIPLE
REGRESSION
ANALYSIS,
REGRESSAND:
CHANGE
AFTER
1 YEAR
IN
UPPER
(A 49). The analysis presented in Table XII comprises 74 individuals and the regressand is the change in upper arch width between first molars 1 year after the initial examination. The regressors were variables for anamnesis and clinical status A 15, adenoids A 20 and A 29, dentition A 46, A 48 and A 55, and skeleton A 91, A 92, A 102 and A 115.
ARCH
WIDTH
BETWEEN
FIRST
MOLARS
EfSects of adenoidectomy Table
XIV.
Correlations
Change
between
after
Table arch
XV. widths
after
1 year
1 year
Mode of brea.thing (unchanged mouth to nose = - 1) Size of adenoids (A 32) “Significance “%ignificnnce
changes
=
0, switch
9
M, - M,
Lower
M, - M,
Upper
x 100
0.28’
from
0.33X’
at 5 per cent level. at 1 per cent level.
Regressand: between
Change first
molars
after (A
1 year
in
relationship
between
lower
and
upper
63) Partial
Regressor
Coefficient
Constant Size of adenoids (A 20), change after 1 year R2 = 0.24; R.S.D.
- 0.4321
0.1625
0.4676
0.0973
“““Significance
=
Standard
error
t
value
- 2.66
4.81”’
correlation.
-
0.49
1.02
at 0.1 per
cent
level.
Only the regressor A 20 proved to be significant at the 5% level. The result of the analysis is presented in Table XII. In this regression analysis, changed size of adenoids as assessed from lateral radiographs (A 20) proved to be the only variable of importance for the change in upper arch width between first molars 1 year after the initial examination. The coefficient of determination is weak (R2 = 0.16). The regressor A 20 is significant at the 0.1 per cent level and has the expected sign. Thus, the analysis indicates that in cases where size of adenoids is reduced by surgery, the upper arch width between first molars has increased 1 year after the operation. This relationship appears to be indirect, probably acting via changed mode of breathing and changed tongue position after adenoidectomy. Relationship between lower and upper arch widths between first molars (A 63). The relationship between lower and upper arch widths between first molars initially and 1 year later (1 year postoperatively for the children who underwent adenoidectomy) is compared in Table XIII. These data express the transverse relation between the lower and upper jaws, an increase in upper arch width resulting in a smaller index value. It will be seen from Table XIII that the index for the relationship between lower and upper arch widths differed almost significantly between the two groups at the initial examination (p < 0.05). At the follow-up 1 year later there was no significant difference in this respect. The greatest change in the interval occurred in the adenoidectomy group. The difference between the changes for the two groups during the year after the initial examination is highly significant (p < 0.001).
10
Linder-Aronsott
Table
XVI.
Group
Am. J. Orthod. January 1974
means
Group
for
sogittal
“Significance
at 5 per
at 7 per
t value for No.
differencr
+ 0.59
32
44.60
+ 0.61
32
+0.09
+ 0.08
32
1.07
42.10 _+ 0.73
30
42.85
5 0.73
30
+0.75
+ 0.16
30
4.74”“”
44.51
2.41 f 0.95 2.54” cent
1.75 -c 0.96 1.83
between after
cent
-0.66 It 0.18 -3.67”“”
-3.67”
level.
changes
after
0, switch
from
1 year
Sagittal
1 year
Mode of breathing (unchanged mouth to nose = - 1) Size of adenoids (A 32) at 5 per
later
Diference after 1 year
Correlations
“Significance
1 yeai
No.
Table
““Significance
and
later
at 1 per cent level. nt 0.1 per cent level.
Change
initially
1 year
““Significance “““Significance
XVII.
of nasopharynx
No.
Initially
Controls Adenoidectomy children Difference between the groups’ t valurs
depth
=
depth
of nusopharynx
-0.37” 0.23”
level.
cent
level.
SIMPLE CORRELATION ANALYSIS. Simple correlation analyses of changes after 1 year are shown in Table XIV for mode of breathing and size of adenoids in relation to t.he relationship between lower and upper arch widths between first molars. A probably significant correlation (p < 0.05) exists between a change from mouth to nose breathing and an altered relationship between the widths of the lower and upper arches. The positive correlation coefficient (r = 0.28) indicates that the cases with a change from mouth to nose breathing display a reduction of the index for this relationship. Such a reduction is noted when the width of the upper arch between first molars increases. The correlation between changed size of adenoids and an altered relationship between lower and upper arch widths is significant at the 1 per cent level. MULTIPLE
REGRESSION
ANALYSIS.
REGRESSAND:
CHANGE
AFTER
1 YEAR
IN
RELA-
(A 63). The analysis presented in Table XV comprises seventy-four persons, and the regressand is the change after 1 year in the relationship between lower and upper arch widths between first molars. The regressors were the variables for anamnesis and clinical status A 15, adenoids A 20 and A 32, and skeleton A 91 and A 92. Only the regressor A 20 proved to be significant at the 5 per cent level. The results of the analysis are presented in Table XV. As in the preceding analysis, changed size of adenoids as assessed from lateral radiographs (A 20) proved to be the only variable of importance for
TIONSHIP
BETWEEN
LOWER
AND
UPPER
ARCH
WIDTHS
BETWEEN
FIRST
MOLARS
Volume Number1
65
Table
XVIII.
Efects Regressand:
Change
after
1 year
in sagittal
depth
of adenoidectomy of
nasopharynx
(A 92) Partial correlation
Standard
Regressor
Coeffioient
error
t oahe
0.0974
0.1035
0.94
0.3014
0.0781
3.86’“”
Constant Mode of breathing (A 14) initially (0 = controls, nose breathers; 1 = nose breathers in adenoidectomy group ; 2 = mouth breathers in adenoidectomy group) Rz zz 0.17; R.S.D. = 0.64 “‘“Significance
at 0.1 per
cent
11
0.41
level.
explaining the regressand. Once again, the coefficient of determination is weak (R2 = 0.24). The regressor A 20 is highly significant (p < 0.001) and has the expected sign. The analysis shows that cases in which size of adenoids is reduced by surgery also undergo a reduction of the relationship between lower and upper arch widths between first molars, upper arch width increasing and/or lower arch width decreasing. This implies that a reduced tendency to cross-bite can be expected as a result of adenoidectomy. The explanation for this relationship is seen as lying in changed mode of breathing and changed tongue position after adenoidectomy. Sagittal depth of nasopharynx (A 92). Group means for the sagittal depth of nasopharynx initially and 1 year later (1 year postoperatively for the children who underwent adenoidectomy) are compared in Table XVI. Initially, the sagittal depth of the nasopharynx (A 92) was shorter on the average in the adenoidectomy group than in the controls, though the difference is only significant at the 5 per cent level. At the follow-up 1 year later, an increased depth was noted only for the adenoidectomy group, the increase differing significantly from 0. In relation to the control group, the increase for the adenoidectomy children is highly significant (p < 0.001). An increased sagittal depth of the bony nasopharynx can thus be envisaged as an effect of adenoidectomy. SIMPLE CORRELATION ANALYSIS. Simple COrrelation analyses of changes after 1 year are shown in Table XVII for mode of breathing and size of adenoids in relation to the sagittal depth of the bony nasopharynx. The simple correlation analysis in Table XVII points to a significant relationship at the follow-up 1 year later between a change from mouth to nose breathing and an increase in the sagittal depth of the bony nasopharynx. This relationship is significant (p < 0.01). There is also a probably significant relationship (p < 0.05) between reduced size of adenoids and increased depth of bony nasopharynx. MULTIPLE
REGRESSION
ANALYSIS.
REGRESSAND:
CHANGE
AFTER
1
YEAR
IN
12
Linder-Aronson
Am. J. Orthod. January 1974
DEPTH OF NASOPHARYNX (A 92). The analysis presented in Table XVIII comprises seventy-four persons, and the regressand is the variable for the change after 1 year in sagittal depth of nasopharynx (A 92). The regressors were variables for anamnesis A 15, adenoids A 32, and dentition A 46, A 48-49, and A 63. Only the regressor A 15 proved to be significant at the 5 per cent level. The results of the analysis are presented in Table XVIII. The only variable to be included is the regressor A 15, indicating mout’h or nose breathing initially, which has a weak coefficient of determination (R” = 0.17). For the purpose of this analysis, mode of breathing was classified as indicated in Table XVIII. The analysis indicates that the children who were mouth breathers at, the time of adenoidectomy displayed the largest increase 1 year later in the sagittal depth of the nasopharynx. This relationship is significant at the 0.1 per cent level. SAGITTAL
Discussion
Do aden.oids affect the dentition? Ever since the report by TomeslO there has been discussion in the literature as to whether and, if so, how adenoids are related to a particular type of dentition.3 As reported earlier, relationships have been found between adenoids and a particular type of dentition characterized by low angles between the upper incisors and the nasion-sella line as well as between the lower incisors and the mandibular line, a narrow upper arch between t,he first molars, and a tendency to cross-bite.3 The retroclination of the upper and lower incisors was interpreted as a consequence of an influence from the lip muscles when the mouth is held open because nose breathing is obstructed by adenoids. The narrow upper arch and the tendency to cross-bite in the children who underwent adenoidectomy were explained as parallels to these children’s long, narrow type of face with a small nasopharynx and narrow nose. Some causal relationship was also considered conceivable, however, between upper arch width and adenoids that involve mouth breathing and a low tongue position. It was considered that a follow-up study after adenoidectomy would help to clarify this point. The present report concerns a follow-up of the seventy-four children whose upper and lower incisors and upper first molars had erupted at the time of the initial examination and were still in place at the follow-up. The presence of these teeth was considered essential for determining how soft tissues such as the tongue and lips may influence the dentition before and after adenoidectomy. The results demonstrate a clear reduction 1 year later in the significant differences obtained initially between the means for dentitional variables in the control and adenoidectomy groups, respectively (angle of upper and lower incisors to nasion-sella line and mandibular line, respectively, upper arch width between first molars, and relationship between lower and upper arch widths between first molars). The smaller differences point to a normalization of the
Volume Number
Effects
65 1
of
adenoidectomy
13
dentition after adenoidectomy. For all the dentition variables concerned, the changes after 1 year differed significantly between the control and the adenoidectomy children. The change after 1 yea,r in the inclination of the upper and lower incisors did not differ significantly from 0 in the control group, whereas it was highly significant (p < 0.001) for the adenoidectomy group. Upper arch width between first molars had increased by 0.53 + 0.07 mm. after 1 year in the controls, a change that differs significantly from 0. This annual increase in width is well in line with the figure of 0.6 mm. a year reported for corresponding ages in a longitudinal study by Moorrees.7 In the adenoidectomy group the corresponding increase in width 1 year after the operation averaged 0.88 L 0.10 mm., which is significantly different from the increase in the control group (p < 0.01). The study can therefore be said to verify clearly the effects of adenoidectomy on the dentition. Consequently, the size of adenoids and their relation to mouth or nose breathing are highly relevant in orthodontics. The values for these dentition variables in children 1 year after adenoidectomy differed only slightly from the corresponding data on the control children, suggesting that the normalization of the dentition after adenoidectomy occurs largely in the first year after the operation. How do adenoids afleet the dentition? Changed size of adenoids was included in the regression analyses reported above as an explanatory variable for the changes in all dentition variables except the one for the angle of the upper incisors to the nasion-sella line (A 46). It is hardly likely that adenoids affect the dentition directly. Instead, the influence is envisaged as coming via the mode of breathing and the muscles of the lips, cheeks, and tongue. In cases of mouth breathing due to nasal obstruction, the tongue is held lower than in the case of nose breathing.2p 3, 8, 9 This alters the balance between pressure from the tongue and cheeks against the upper first molars. A low tongue position reduces the buccal pressure from the tongue and, if the pressure from the cheek muscles remains unchanged, the upper molars will tend to shift in a palatinal direction. The altered inclination of the lower incisors in relation to the mandibular line after adenoidectomy is interpreted as a consequence of the change from mouth to nose breathing. As the mouth does not have to be kept open for breathing, the tension in the orbicularis oris muscle will be altered and, as a switch from mouth to nose breathing also results in a change in tongue position, the balance of pressure from lip and tongue muscles against the lower incisors will change after adenoidectomy. These mechanisms as a possible explanation for the influence of changed size of adenoids on the dentition can be illustrated schematically as follows:
Adenoidectomy
--
Reduced size of adenoids
-
Change from mouth to /raised nose breablling\
Tongue position \ Lips closed
,
Del*titiol*al
chwz=
14
Linder-Aronson
Am.
J. Orthod.
.Januaw1974
Support for this hypothesis was obtained in a previous investigation from a stepwise regression analysis on fifty-six children who underwent adenoidectomy for obstructed nose breathing as well as thirty controls who were judged to lack adenoids.” The effect of adenoideetomy on the dentition has been reported in the present study in terms of differences in group means. Although the differences are statistically significant, they are small numerically. The effect of adenoidectomp on the dentition is nevertheless relevant in orthodontics. Children who breathe through the mouth because of large adenoids, for instance, may possibly rid themselves of a traumatic cross-bite in that the width of the upper arch may normalize after adenoidectomy. The finding that the angle of the upper and lower incisors to the nasion-sella line and the mandibular line, respectively, increases after adenoidectomy provides further verification of the previous finding” that upper and lower incisors are more retroclined in mouth breathers than in nose breathers. This rules out the old theory that proclined incisors constitute a visual characteristic of mouth breathers. Since the combination of adenoids and mouth breathing appears to affect the dentition to some extent, assessments of the indications for adenoidect,omy should include an orthodontic evaluation. How does a change in mode of breathing affect the nasopharynx? Mode of breathing (oral or nasal) was included in the regression analysis as an explanatory variable for the change after 1 year in the sagittal depth of the nasopharynx. It is hardly likely that the size of the nasopharynx is affected dire&y by the mode of breathing, the mechanism being envisaged as acting instead via the lip and cheek muscles. It is conceivable that the ring of muscle formed by the orbicularis oris, buccinator, and constrictor superior muscles plays a part in this context. As already mentioned, the need to keep the mouth open in order to breathe will affect the tension in the orbicularis oris muscle. When the mouth is kept open, therefore, a change in tension may also be conveyed via this muscle ring to the constrictor superior muscle. The majority of children undergoing adenoidectomy become nose breathers after the operation.5 As the mouth can then be kept closed, it is envisaged that the tension in this muscle ring is then reduced. Summary
The purpose of the present study was to determine whether adenoidectomy (and hence a change to nose breathing) is followed by: (1) a change in the inclination of upper and lower incisors. (2) a change in the width of the upper arch, and/or (3) an effect on the sagittal depth of the bony nasopha,rynx. The clinical material comprised the children in a previous study who were at least 8 years old and in whom the upper and lower incisors had erupted before the initial examination, which was followed by adenoidectomy. A second examination was made 1 year later. The group undergoing adenoidectomy numbered thirty-seven children, and there were thirty-seven controls.
Efects
of adenoidectomy
15
All the children were examined with respect to forty-six variables, grouped under the headings of anamnesis, adenoids, dentition, airflow, and skeleton. Measurements were obtained for each child from lateral radiographs and casts, and the nasal airflow was recorded in liters per minute. Group means for the two examinations have been compared and relationships have been studied with the aid of simple correla,tion analysis and multiple regression analysis. It was found that in the year between the examinations, the, children who underwent adenoidectomy had undergone a significantly greater increase than the controls in the angle of the upper and lower incisors, respectively, to the nasion-sella and the mandibular lines. The adenoidectomy group also had a significantly greater increase in the mean width of the upper arch between the first molars, this width being enlarged most in the children who had switched from mouth to nose breathing after adenoidectomy. Furthermore, the mean sagittal depth of the nasopharynx had increased only for the children who underwent a,denoidectomy, the increment in this group being significantly different from 0. The study accordingly demonstrates that dentitional changes occur after adenoidectomy in children who were mouth breathers preoperatively because of nasal obstruction. The size of the nasopharyngeal cavity also changed in the children who switched from mouth to nose brea.thing after adenoidectomy. Since the dentition seems to be affected to some extent by the combined occurrence of adenoids and mouth breathing, an assessment of indications for adenoidectomy should include orthodontic evaluations. I wish Sweden, for
to express my sincere thanks to Associate Professor assisting with the statistical processing of the material.
Gunnar
Eklund,
Uppsala,
REFERENCES
1. Graber, T. M.: Orthodontics-Principles and practice, Philadelphia, lW1, W. B. Saunders Company, p. 97. 2, Holik, F.: Relation between habitual breathing through the mouth and muscular activity of the tongue, Cesk. Stomatol. 57: 170, 1957. 3. Linder-Aronson, S.: Adenoids-Their effect on mode of breathing and nasal airflow and their relationship to characteristics of the facial skeleton and the dentition, Acta Otolaryngol., Supp. 265, 1970. 4. Linder-Aronson, S. : Adenoida vegetationer och effekten av adenoidektomi, Sven. Tandllk. Tidskr. 64: 399, 1971. 5. Linder-Aronson, S.: Effects of adenoidectomy on mode of breathing, size of adenoids and nasal airflow, Pratt. Otolaryngol. (Ziirich)228: 285, 1973. 6. Lundstrom, A. : Tooth size and occlusion in twins, Basel, 1948, S. Karger. 7. Moorrees, C. F.: The dentition of the growing child, Cambridge, Mass., 1959; Harvard University Press. 8. Ricketts, R. M.: Respiratory obstructions and their relation to tongue posture, Cleft Palate Bull. 8: 3, lQ58. 9. Subtelny, J. D.: The significance of adenoid tissue in orthodontia, Angle Orthod. ‘24: 59, 1954. 10. Tomes, Ch. S.: On the developmental origin of the V-shaped contracted maxilla, Monthly Rev. Dent. Surg. 1: 2, 1872.
ORIGINAL
Effects of adenoidectorny and nasopharynx Sten Under-Aronson, Orebro, Sweden
1, January,
1974
ARTICLES
on den&ion
D.D.S., Ph.D.
A
denoids and the mouth breathing which they induce are associated with a narrow upper arch, a high incidence of cross-bite or a tendency to crossbite, retroclined upper and lower incisors, and small sagittal depth of the nasopharynx.3 A narrow upper arch and high frequency of cross-bite among children with large adenoids were judged as parallel phenomena to the narrow facial type of these individuals, along with a small nasopharyngeal cavity and narrow nose. There may also be some causal relationship between the width of the upper arch and the mouth breathing and low tongue position associated with adenoids. The retroclination of upper and lower incisors in the mouth breathers was interpreted in the same study as a consequence of increased tension in the lip musculature due to the mouth being kept open. A small nasopharyngeal space in conjunction with adenoids is usually followed by mouth breathing. Thus, the size of the nasopharynx is considered to be uninfluenced by whether breathing occurs through the nose or through the mouth. The question of whether a causal relationship exists between adenoids plus mouth breathing on the one hand and, on the other, the dentition and a small nasopharynx in particular is best approached by means of longitudinal studies of conditions before and after adenoidectomy. The purpose of the present study was to determine whether adenoidectomy (and hence a change to nose breathing) is followed by (1) a change in the From the Stockholm,
Orthodontic Sweden.
Department,
Odontologic
Faculty,
Karolinska
Institutet,
1
Am. J. Orthod. Janunry 1974
Table
I. Group
means
for
angle
of upper
incisors
to
nasion-sello
line
initially
and
1 year
later
Group
Initialljy
Controls Adenoidectomy children Difference between the groups’ t value “Significance
at 1 per
“““Significance
+ 1.13
37
104.82
t 3.14
37
+ 0.29 + 0.26
37
1.11
100.53
t 1.08
37
102.55
5 1.10
37
+ 2.03 ? 0.56
3i
3.64”“”
4.00 + 1.56 2.56”
at 5 per
““Significance
104.53
cent cent
:tt 0.1 per
2.27 t 1.58 1.43
- 1.74 rt 0.62 - 2.79””
- 2.79=
level. level. cent
level.
inclination of upper and lower incisors, (2) a change in the width of the upper arch, (3) an effect on the sagittal depth of the bony nasopharynx. Material
and
methods
The study was made on the clinical ma.terial presented in an earlier work.” For the present investigation the children have been divided into two groups only-the thirty-seven who underwent adenoidectomy and thirty-seven controls. All the children were at least 8 years old, and their upper and lower incisors had erupted before the initial examination, which was followed by adenoidectomp. A second examination was made 1 year later. The variables are the same as were used in the previous study.” Radiographic analysis. Lateral ra.diographs taken initially and 1 year later were used to measure the inclination of upper and lower incisors (A 46 and A 48, respectively) and the sagittal depth of t,he bony nasopharynx (A 92) from the reference points and lines reported in 1970, using the same apparatus, settings, and film.” Amlysis from casts. The following measurements were ma.de on plaster models produced from impressions of the upper and lower arches taken in “Tissuetex” alginate material : 1. Width of upper and lower dental arches between first molars (A 49, A 50). 2. Transverse relationships between the jaws were expressed by means of the relationship between the widths of the lower and upper dental arches. Index values close to 100 denote cusp-to-cusp dentition and higher values denote cross-bite : Arch width MI - MI lower (A 50) x loo (A 63) Arch width M, - M, upper (A 49) Dental arch width was measured (to within t 0.1 mm.) with sliding calipers at the first molars in accordance with the method of LundstrGm.” XWisCical methods. Means and standard deviations were calculated from values for the variables in the adenoidectomy and control children. The differences between group means were tested for significance with the t test.
Efects Table
II.
children
Change who
Mode InitiaZZy -
after
II
NO%3
Nose Mouth
III.
cent
Correlations Change
angle
of
upper
incisors
(A
46)
later
I
t calue
,
3.58 1.96 1.25
in thirty-seven
,
2.07 2.53” 2.04
No. of children 6 23 8
level. between
after
in mean A 46 (degrees)
for
2 year
at 5 per
mean
3
Change
of breathing
Mouth Mouth
Table
in
adenoidectomy
adenoidectomy
Nose
*Significance
1 year
underwent
of
changes
1 year Upper
1 year
Mode of breathing (unchanged from mouth to nose = - 1) Size of adenoids (A 32)
after
=
0, switch
in&or/Nasion-sella
line
- 0.18 - 0.19
Relationships between the variables were studied with the aid of correlation analysis and multiple regression analysis. An account of the statistical methods will he found in Chapter 5 and the Appendix in the 1970 work of LinderAronson3 Results
Allgle of upper incisors to nasion-selln l&e (A 46). Group means for the angle of the upper incisors to the nasion-sella line initially and 1 year later (1 year postoperatively for the adenoidectomy children) are compared in Table I. Initially the angle of the upper incisors to the nasion-sella line was smaller, on the average, in the children who underment adenoidectomy than in the controls, the difference being significant at the 5 per cent level (p < 0.05). At the follow-up 1 year later, the difference is no longer statistically significant, the closer agreement between the groups being a consequence of a significant increase in the angle of the upper incisors in the children who underwent adenoidectomy. The change in the angle of the upper incisors between the two examinations differs significantly between the two groups (p < 0.01). The children who switched from mouth to nose breathing after adenoidectomv (Table II) display much the same mean change in the angle of the upper incisors as that for the adenoidectomy group as a whole in relation to the controls, though the difference is no more than almost significant (p < 0.05). It will also be seen from Table II that six of the children who underwent adenoidectomy breathed through the nose initially. The change in the angle of the upper incisors for this subgroup does not differ statistically from 0. A change of as much as 11 degrees in one of these children helps to explain why the mean change is as high as 3.58 degrees. In the eight children who were still mouth breathers I year after adenoidectomy, the change in the mean angle of the upper incisors did not differ significantly from 0 either.
4
Linder-Aronson
Table
Am. J. Orthod. January 1974
IV. Regressand:
Change
after
1 year
in angle
Standard
ewor
of upper
incisors
to
nasion-sella
line
(A 46) Reqressor
1
Constant Rz = 0 ; R.S.D.
Table
I
Coefficient
1.1824
I
t value
0.3270
rpartiaz
rmrelntion
-
3.62
zz 2.81
V. Group
means
for
angle
of
lower
incisors
to
mandibular
line
initially
and
1 year
later
No.
Difference after 1 year
No.
t value for diference
1 year Group
Initially
Controls Adenoidectomy children Difference between the groups’ t values “Significance ““Significance “‘“Significance
at 5 per at 1 per
No.
95.31? 88.73
0.97
37
95.74
f. 1.00
37
+0.43
2 0.24
37
1.79
2 1.17
37
90.80
* 1.05
37
+2.07
+ 0.55
37
3.77”“”
6.582 4.33”“” cent cent
at 0.1 per
later
1.52
4.94 + 1.45 3.41””
-1.64 2 0.60 -2.74””
- 2.74””
level. level. cent
level.
correlation analyses of changes after 1 year are shown in Table III for mode of breathing and size of adenoids in relation to the angle of the upper incisors to the nasion-sella line. In neither case was any significant correlation obtained, a result that was presaged by the data in Table II, where the mean change in the angle of the upper incisors in the twenty-three children who switched from mouth to nose breathing after adenoidectomy was significant only at the 5 per cent level. The low correlations also reflect the circumstance that the angle of the upper incisors changed markedly in one child, even though the mode of breathing remained the same in this case after adenoidectomy. SIMPLE
MULTIPLE
CORRELATION
REGRESSION
ANALYSIS.
ANALYSIS.
Simple
REGRESSAND:
CHANGE
AFTER
1 YEAR
IN
ANGLE
(A 46). The analysis presented in Table IV comprises seventy-four persons and the regressand is the variable for the change after 1 year in the angle of the upper incisors to the nasion-sella line. The regressors were the clinical status variable A 15, adenoid variables A 20 and A 32, dentition variable A 48, and skeleton variable A 92. None of these regressors proved to be significant at the 5 per cent level. The total correlation or coefficient of determination (R2) and the standard deviation of the residuals (R.S.D.) are given in Table IV with the regression equation, the standard error of the coefficients, t values, and the partial correlation between the regressand and each of the regressors with allowance made for the other regressors. As none of the regressors included in the analysis attained the 5 per cent level of significance, no explana,tion has been found for the change after 1 year in the angle of the upper incisors to the nasion-sella line.
OF UPPER
INCISORS
TO NASION-SELLA
LINE
Effects
Volume Number
65 1
Table
VI. Change
children
who
after
underment
1 year
1 year
angle
Change
in mean (A 48)
for
VII. Correlations Change
between after
1 year
Mode of breathing Size of adenoids (A 32) “““Significance
lower
incisors
(A
48)
in
thirty-seven
No. of
(degrees)
later
Nose Nose Mouth Nose Mouth Mouth XSignificance at 5 per cent level. ““Significance at 1 per cent level. Table
of
5
adenoidectomy
Mode of breathing Initially
in mean
adenoidectomy
of
1.50 2.13 2.54
changes
after
children
t value
6 23 8
1.63 2.51” 3.58’”
1 year Lower
inctior/.Mandibular
line
- 0.20 - 0.41’“”
at 0.1 per cent level.
Angle of lower incisors to mandibular line (A 48). Group means for the angle of the lower incisors to the mandibular line initially and 1 year later (1 year postoperatively for the children who underwent adenoidectomy) are compa,red in Table V. Initially, the mean angle of the lower incisors to the mandibular line was much smaller in the children who underment adenoidectomy than in the controls, the difference being significant (p < 0.001). At the follow-up 1 year later the difference is still significant, despite the fact that the angle increased very much more in the adenoidectomized children than in the controls. The difference between the changes in the group means after 1 year is significant (p < 0.01). The mean change in the angle of the lower incisors in the children who switched from mouth to nose breathing after adenoidectomy (Table VI) reflects the difference between the adenoidectomy and control groups according to Table V. It is remarkable, however, that the mean change in the eight children who remained mouth breathers after adenoidectomy differs significantly from the initial value. A large part of the difference in this subgroup is attributable to one child. SIMPLE CORRELATION ANALYSIS. Simple correlation analyses of changes after 1 year are shown in Table VII for mode of breathing and size of adenoids in relation to the angle of the lower incisors to the mandibular line. No significant correlation was found between changed mode of breathing and changed angle of lower incisors in relation to the mandibular line, but changed size of adenoids did correlate significantly (p < 0.001) with changed angle of lower incisors. The negative correlation coefficient (Table VII) indicates that the children whose adenoids were reduced in size displayed an increase in the average angle of the lower incisors to the mandibular line. Considering that the relationship between changed size of adenoids and changed angle of lower
6
Table line
Am. J. Orthod. Januarv1974
Limier-Aronsola VIII.
Regressand:
Change
after
1 year
in
angle
of
lower
incisors
to
mandibular
(A 48)
Rearessor
Constant Size of adenoids (A 20), change after 1 year Sagittal depth of nasopharynx (A 92), change after 1 year R* = 0.23 ; R.S.D. = 2.44
Coe#ident
Standard error
0.4653
Partial t value
correlation
0.3950
1.18
-
- 1.1131
0.2461
- 4.52”’
- 0.47
- 0.9645
0.4341
- 2.222
- 0.25
%ignificance at 5 per cent level. x%ignifieance at 0.1 per cent level.
incisors could conceivably be explained via changed mode of breathing, it is surprising that a significant correlation was not obtained between changed mode of breathing and changed angle of lower incisors. A conceivable explanation for the low correlation is that even children who did not change their mode of breathing after adenoidectomy displayed a change in the angle of the lower incisors 1 year after this operation (Table VI). Some uncertainty in the registration of mode of breathing may likewise have contributed to the low correlation. The registration of size of adenoids, on the other hand, was highly reliable. MULTIPLE REGRESSION ANALYSIS. REGRESSAND: CHANGE AFTER 1 YEAR IN ANGLE OF LOWER INCISORS TO MANDIBULAR LINE (A 48). The analysis presented in Table
VIII comprises seventy-four persons, and the regressand is the variable for the change after 1 year in the angle of lower incisors to the mandibular line. The regressors were variables for clinical status A 15, adenoids A 20 and A 32, dentition A 46, A 49, A 53, and A 63, and skeleton A 92. The regressors A 20 and A 92 were introduced first in that order, and none of the others listed above proved to be significant at the 5 per cent level. The results are presented in Table VIII. According to this regression analysis, changed size of adenoids as assessed from lateral radiographs (A 20) provides the largest explanation for the change after 1 year in the angle of lower incisors to the mandibular line. The regression coefficient is significant (p < 0.001) and has the expected sign. The other explanatory variable included in the analysis is the change in sagittal depth of the nasopharynx (A 92)) but here the regression coefficient is no more than almost significant (p < 0.05). The coefficient of determination for the regressors included in the analysis (R* = 0.23) is weak. For A 20 alone, R* equals 0.17, indicating that most of the explanatory value lies in changed size of adenoids. The analysis indicates that the children displaying the greatest reduction in size of a#denoids had the largest increase in the angle of the lower incisors to the mandibular line. This relationship would appear to be indirect, acting probably via altered position of the lips and tongue.
Volume Number
65 1
Table
IX.
EfSects Group
means
for
upper
arch
width
Group
between
first
later
I I
1 year
molars
of adenoidectomy
and 1 year later
initially
t value for
No.
Difference after 1 year
I No.
I
diderence
Controls Adenoidectomy children Difference between the groups’ t values
45.09
f 0.37
37
45.61 + 0.38
37
+ 0.53 f 0.07
37
7.53””
44.15
2 0.46
37
45.03
37
+ 0.88 + 0.10
37
9.10=*=
“Significance
cent
at 5 per
TSignificance
at 1 per
“““Significance
X.
seven
children
Change
width
during
of
Nose Mouth Mouth
in upper
arch
TSignificance
Xl.
at 5 per at I per
(values
1 year
later
Change in mean for (A 49) (mm.)
cent
0.44 0.39 0.18
““Significance
at 5 per at 1 per
first
reduced
molars for
(A 49)
normal
in thirty-
increase
in
t value
No. of children
2.84-” 2.92’= 0.73
8 23 6
level.
cent
level.
between after
cent cent
changes
after
1 year
Mode of breathing (unchanged mouth to nose = - 1) Size of adenoids (A 32) “Significance
between
mm.)
Correlations Change
width
adenoidectomy
Nose Nose Mouth
“Significance
Table
1 year
breathing 1 I
- 3.00””
level.
underwent
1 year-O.53
Mode
- 0.35 + 0.12 - 3.00x=
level.
cent
after who
0.58 + 0.59 0.98
level.
cent
at 0.1 per
Table
Initially
0.94 2 0.59 1.57
2 0.45
7
=
1 year H,-M,
0, switch
from
upper - 0.27’ - 0.37”
level. level.
Width of upper arch between first molars (A 49). Group means for the width of upper arch between first molars initially and 1 year later (1 year postoperatively for the adenoidectomy children) are compared in Table IX. The mean increase in arch width during 1 year amounted to 0.53 + 0.07 mm. in the controls, which differs significantly from 0, and to 0.88 + 0.11 mm. in the adenoidectomy group. The difference between these mean increases-O.36 rf: 0.12 mm. more for the adenoidectomy group-is significant (p < 0.01). The means presented in Table X for the thirty-seven children who underwent adenoidectomy have been reduced by the increase in upper arch width during 1 year for the control group (that is, 0.53 + 0.07 mm.), which has been taken to represent a normal increase at this age (Table IX).
8
Am. J. Ortbod. Januar?/1974
Linder-Aronson
Table
XII.
Change
after
1 year
in upper
arch
width
between
first
molars
(A 49) Pm-tin1
Regressor Constant Size of adenoids (A ZO), change after 1 year Re I 0.16 ; R.S.D. “““Significance Table
XIII.
initially
and
=
“xxSignificance
6.50
- 0.1766 0.50
0.0479
- 3.69”“”
cent
correlation
- 0.40
level. between
lower
and
upper
arch
widths
between
first
molars
later
1 year
later
No.
Difference after 1 year
No.
difference
I! 0.52
37
89.40
2 0.49
37
- 0.45 r 0.14
37
- 3.32*’
92.62 -+ 0.97
37
91.19
? 0.93
37
- 1.43 + 0.21
37
- 6.80”’
89.85
- 2.772 1.10 - 2.52’
at 5 per
t value
No.
Initially
Controls Adenoidectomy children Difference between the groups’ t values
““Significance
value
0.0791
Relationship 1 year
t
error
0.5138
at 0.1 per
Group
“Significance
Standard
Coefficient
cent
at 1 per
0.98 It 0.25 3.87”“”
3.87”’
level.
cent
at 0.1 per
- 1.79 r 1.05 - 1.70
for
level
cent
level.
It will be seen that it is primarily the children who changed from mouth to nose breathing after adenoidectomy who ,display an above-normal average increase, differing significantly from 0 at the I per cent level. At the same time, it is remarkable that the eight children who were nose breathers initially as well as 1 year later also display an above-normal increase in upper arch width, though this is no more than almost significant (p < 0.05). SIMPLE CORRELATION ANALYSIS. Simple correlation analyses of changes after 1 year are shown in Table XI for mode of breathing and size of adenoids in relation to the upper arch width between first molars. The simple correlation analysis in Table XI points to a probable relationship between a change from mouth to nose breathing and an increase in upper arch width between first molars. According to this analysis, then, a change in size of adenoids and probably also in mode of breathing (from mouth to nose) after adenoidectomy is associated with an increase in upper arch width between first molars. MULTIPLE
REGRESSION
ANALYSIS,
REGRESSAND:
CHANGE
AFTER
1 YEAR
IN
UPPER
(A 49). The analysis presented in Table XII comprises 74 individuals and the regressand is the change in upper arch width between first molars 1 year after the initial examination. The regressors were variables for anamnesis and clinical status A 15, adenoids A 20 and A 29, dentition A 46, A 48 and A 55, and skeleton A 91, A 92, A 102 and A 115.
ARCH
WIDTH
BETWEEN
FIRST
MOLARS
EfSects of adenoidectomy Table
XIV.
Correlations
Change
between
after
Table arch
XV. widths
after
1 year
1 year
Mode of brea.thing (unchanged mouth to nose = - 1) Size of adenoids (A 32) “Significance “%ignificnnce
changes
=
0, switch
9
M, - M,
Lower
M, - M,
Upper
x 100
0.28’
from
0.33X’
at 5 per cent level. at 1 per cent level.
Regressand: between
Change first
molars
after (A
1 year
in
relationship
between
lower
and
upper
63) Partial
Regressor
Coefficient
Constant Size of adenoids (A 20), change after 1 year R2 = 0.24; R.S.D.
- 0.4321
0.1625
0.4676
0.0973
“““Significance
=
Standard
error
t
value
- 2.66
4.81”’
correlation.
-
0.49
1.02
at 0.1 per
cent
level.
Only the regressor A 20 proved to be significant at the 5% level. The result of the analysis is presented in Table XII. In this regression analysis, changed size of adenoids as assessed from lateral radiographs (A 20) proved to be the only variable of importance for the change in upper arch width between first molars 1 year after the initial examination. The coefficient of determination is weak (R2 = 0.16). The regressor A 20 is significant at the 0.1 per cent level and has the expected sign. Thus, the analysis indicates that in cases where size of adenoids is reduced by surgery, the upper arch width between first molars has increased 1 year after the operation. This relationship appears to be indirect, probably acting via changed mode of breathing and changed tongue position after adenoidectomy. Relationship between lower and upper arch widths between first molars (A 63). The relationship between lower and upper arch widths between first molars initially and 1 year later (1 year postoperatively for the children who underwent adenoidectomy) is compared in Table XIII. These data express the transverse relation between the lower and upper jaws, an increase in upper arch width resulting in a smaller index value. It will be seen from Table XIII that the index for the relationship between lower and upper arch widths differed almost significantly between the two groups at the initial examination (p < 0.05). At the follow-up 1 year later there was no significant difference in this respect. The greatest change in the interval occurred in the adenoidectomy group. The difference between the changes for the two groups during the year after the initial examination is highly significant (p < 0.001).
10
Linder-Aronsott
Table
XVI.
Group
Am. J. Orthod. January 1974
means
Group
for
sogittal
“Significance
at 5 per
at 7 per
t value for No.
differencr
+ 0.59
32
44.60
+ 0.61
32
+0.09
+ 0.08
32
1.07
42.10 _+ 0.73
30
42.85
5 0.73
30
+0.75
+ 0.16
30
4.74”“”
44.51
2.41 f 0.95 2.54” cent
1.75 -c 0.96 1.83
between after
cent
-0.66 It 0.18 -3.67”“”
-3.67”
level.
changes
after
0, switch
from
1 year
Sagittal
1 year
Mode of breathing (unchanged mouth to nose = - 1) Size of adenoids (A 32) at 5 per
later
Diference after 1 year
Correlations
“Significance
1 yeai
No.
Table
““Significance
and
later
at 1 per cent level. nt 0.1 per cent level.
Change
initially
1 year
““Significance “““Significance
XVII.
of nasopharynx
No.
Initially
Controls Adenoidectomy children Difference between the groups’ t valurs
depth
=
depth
of nusopharynx
-0.37” 0.23”
level.
cent
level.
SIMPLE CORRELATION ANALYSIS. Simple correlation analyses of changes after 1 year are shown in Table XIV for mode of breathing and size of adenoids in relation to t.he relationship between lower and upper arch widths between first molars. A probably significant correlation (p < 0.05) exists between a change from mouth to nose breathing and an altered relationship between the widths of the lower and upper arches. The positive correlation coefficient (r = 0.28) indicates that the cases with a change from mouth to nose breathing display a reduction of the index for this relationship. Such a reduction is noted when the width of the upper arch between first molars increases. The correlation between changed size of adenoids and an altered relationship between lower and upper arch widths is significant at the 1 per cent level. MULTIPLE
REGRESSION
ANALYSIS.
REGRESSAND:
CHANGE
AFTER
1 YEAR
IN
RELA-
(A 63). The analysis presented in Table XV comprises seventy-four persons, and the regressand is the change after 1 year in the relationship between lower and upper arch widths between first molars. The regressors were the variables for anamnesis and clinical status A 15, adenoids A 20 and A 32, and skeleton A 91 and A 92. Only the regressor A 20 proved to be significant at the 5 per cent level. The results of the analysis are presented in Table XV. As in the preceding analysis, changed size of adenoids as assessed from lateral radiographs (A 20) proved to be the only variable of importance for
TIONSHIP
BETWEEN
LOWER
AND
UPPER
ARCH
WIDTHS
BETWEEN
FIRST
MOLARS
Volume Number1
65
Table
XVIII.
Efects Regressand:
Change
after
1 year
in sagittal
depth
of adenoidectomy of
nasopharynx
(A 92) Partial correlation
Standard
Regressor
Coeffioient
error
t oahe
0.0974
0.1035
0.94
0.3014
0.0781
3.86’“”
Constant Mode of breathing (A 14) initially (0 = controls, nose breathers; 1 = nose breathers in adenoidectomy group ; 2 = mouth breathers in adenoidectomy group) Rz zz 0.17; R.S.D. = 0.64 “‘“Significance
at 0.1 per
cent
11
0.41
level.
explaining the regressand. Once again, the coefficient of determination is weak (R2 = 0.24). The regressor A 20 is highly significant (p < 0.001) and has the expected sign. The analysis shows that cases in which size of adenoids is reduced by surgery also undergo a reduction of the relationship between lower and upper arch widths between first molars, upper arch width increasing and/or lower arch width decreasing. This implies that a reduced tendency to cross-bite can be expected as a result of adenoidectomy. The explanation for this relationship is seen as lying in changed mode of breathing and changed tongue position after adenoidectomy. Sagittal depth of nasopharynx (A 92). Group means for the sagittal depth of nasopharynx initially and 1 year later (1 year postoperatively for the children who underwent adenoidectomy) are compared in Table XVI. Initially, the sagittal depth of the nasopharynx (A 92) was shorter on the average in the adenoidectomy group than in the controls, though the difference is only significant at the 5 per cent level. At the follow-up 1 year later, an increased depth was noted only for the adenoidectomy group, the increase differing significantly from 0. In relation to the control group, the increase for the adenoidectomy children is highly significant (p < 0.001). An increased sagittal depth of the bony nasopharynx can thus be envisaged as an effect of adenoidectomy. SIMPLE CORRELATION ANALYSIS. Simple COrrelation analyses of changes after 1 year are shown in Table XVII for mode of breathing and size of adenoids in relation to the sagittal depth of the bony nasopharynx. The simple correlation analysis in Table XVII points to a significant relationship at the follow-up 1 year later between a change from mouth to nose breathing and an increase in the sagittal depth of the bony nasopharynx. This relationship is significant (p < 0.01). There is also a probably significant relationship (p < 0.05) between reduced size of adenoids and increased depth of bony nasopharynx. MULTIPLE
REGRESSION
ANALYSIS.
REGRESSAND:
CHANGE
AFTER
1
YEAR
IN
12
Linder-Aronson
Am. J. Orthod. January 1974
DEPTH OF NASOPHARYNX (A 92). The analysis presented in Table XVIII comprises seventy-four persons, and the regressand is the variable for the change after 1 year in sagittal depth of nasopharynx (A 92). The regressors were variables for anamnesis A 15, adenoids A 32, and dentition A 46, A 48-49, and A 63. Only the regressor A 15 proved to be significant at the 5 per cent level. The results of the analysis are presented in Table XVIII. The only variable to be included is the regressor A 15, indicating mout’h or nose breathing initially, which has a weak coefficient of determination (R” = 0.17). For the purpose of this analysis, mode of breathing was classified as indicated in Table XVIII. The analysis indicates that the children who were mouth breathers at, the time of adenoidectomy displayed the largest increase 1 year later in the sagittal depth of the nasopharynx. This relationship is significant at the 0.1 per cent level. SAGITTAL
Discussion
Do aden.oids affect the dentition? Ever since the report by TomeslO there has been discussion in the literature as to whether and, if so, how adenoids are related to a particular type of dentition.3 As reported earlier, relationships have been found between adenoids and a particular type of dentition characterized by low angles between the upper incisors and the nasion-sella line as well as between the lower incisors and the mandibular line, a narrow upper arch between t,he first molars, and a tendency to cross-bite.3 The retroclination of the upper and lower incisors was interpreted as a consequence of an influence from the lip muscles when the mouth is held open because nose breathing is obstructed by adenoids. The narrow upper arch and the tendency to cross-bite in the children who underwent adenoidectomy were explained as parallels to these children’s long, narrow type of face with a small nasopharynx and narrow nose. Some causal relationship was also considered conceivable, however, between upper arch width and adenoids that involve mouth breathing and a low tongue position. It was considered that a follow-up study after adenoidectomy would help to clarify this point. The present report concerns a follow-up of the seventy-four children whose upper and lower incisors and upper first molars had erupted at the time of the initial examination and were still in place at the follow-up. The presence of these teeth was considered essential for determining how soft tissues such as the tongue and lips may influence the dentition before and after adenoidectomy. The results demonstrate a clear reduction 1 year later in the significant differences obtained initially between the means for dentitional variables in the control and adenoidectomy groups, respectively (angle of upper and lower incisors to nasion-sella line and mandibular line, respectively, upper arch width between first molars, and relationship between lower and upper arch widths between first molars). The smaller differences point to a normalization of the
Volume Number
Effects
65 1
of
adenoidectomy
13
dentition after adenoidectomy. For all the dentition variables concerned, the changes after 1 year differed significantly between the control and the adenoidectomy children. The change after 1 yea,r in the inclination of the upper and lower incisors did not differ significantly from 0 in the control group, whereas it was highly significant (p < 0.001) for the adenoidectomy group. Upper arch width between first molars had increased by 0.53 + 0.07 mm. after 1 year in the controls, a change that differs significantly from 0. This annual increase in width is well in line with the figure of 0.6 mm. a year reported for corresponding ages in a longitudinal study by Moorrees.7 In the adenoidectomy group the corresponding increase in width 1 year after the operation averaged 0.88 L 0.10 mm., which is significantly different from the increase in the control group (p < 0.01). The study can therefore be said to verify clearly the effects of adenoidectomy on the dentition. Consequently, the size of adenoids and their relation to mouth or nose breathing are highly relevant in orthodontics. The values for these dentition variables in children 1 year after adenoidectomy differed only slightly from the corresponding data on the control children, suggesting that the normalization of the dentition after adenoidectomy occurs largely in the first year after the operation. How do adenoids afleet the dentition? Changed size of adenoids was included in the regression analyses reported above as an explanatory variable for the changes in all dentition variables except the one for the angle of the upper incisors to the nasion-sella line (A 46). It is hardly likely that adenoids affect the dentition directly. Instead, the influence is envisaged as coming via the mode of breathing and the muscles of the lips, cheeks, and tongue. In cases of mouth breathing due to nasal obstruction, the tongue is held lower than in the case of nose breathing.2p 3, 8, 9 This alters the balance between pressure from the tongue and cheeks against the upper first molars. A low tongue position reduces the buccal pressure from the tongue and, if the pressure from the cheek muscles remains unchanged, the upper molars will tend to shift in a palatinal direction. The altered inclination of the lower incisors in relation to the mandibular line after adenoidectomy is interpreted as a consequence of the change from mouth to nose breathing. As the mouth does not have to be kept open for breathing, the tension in the orbicularis oris muscle will be altered and, as a switch from mouth to nose breathing also results in a change in tongue position, the balance of pressure from lip and tongue muscles against the lower incisors will change after adenoidectomy. These mechanisms as a possible explanation for the influence of changed size of adenoids on the dentition can be illustrated schematically as follows:
Adenoidectomy
--
Reduced size of adenoids
-
Change from mouth to /raised nose breablling\
Tongue position \ Lips closed
,
Del*titiol*al
chwz=
14
Linder-Aronson
Am.
J. Orthod.
.Januaw1974
Support for this hypothesis was obtained in a previous investigation from a stepwise regression analysis on fifty-six children who underwent adenoidectomy for obstructed nose breathing as well as thirty controls who were judged to lack adenoids.” The effect of adenoideetomy on the dentition has been reported in the present study in terms of differences in group means. Although the differences are statistically significant, they are small numerically. The effect of adenoidectomp on the dentition is nevertheless relevant in orthodontics. Children who breathe through the mouth because of large adenoids, for instance, may possibly rid themselves of a traumatic cross-bite in that the width of the upper arch may normalize after adenoidectomy. The finding that the angle of the upper and lower incisors to the nasion-sella line and the mandibular line, respectively, increases after adenoidectomy provides further verification of the previous finding” that upper and lower incisors are more retroclined in mouth breathers than in nose breathers. This rules out the old theory that proclined incisors constitute a visual characteristic of mouth breathers. Since the combination of adenoids and mouth breathing appears to affect the dentition to some extent, assessments of the indications for adenoidect,omy should include an orthodontic evaluation. How does a change in mode of breathing affect the nasopharynx? Mode of breathing (oral or nasal) was included in the regression analysis as an explanatory variable for the change after 1 year in the sagittal depth of the nasopharynx. It is hardly likely that the size of the nasopharynx is affected dire&y by the mode of breathing, the mechanism being envisaged as acting instead via the lip and cheek muscles. It is conceivable that the ring of muscle formed by the orbicularis oris, buccinator, and constrictor superior muscles plays a part in this context. As already mentioned, the need to keep the mouth open in order to breathe will affect the tension in the orbicularis oris muscle. When the mouth is kept open, therefore, a change in tension may also be conveyed via this muscle ring to the constrictor superior muscle. The majority of children undergoing adenoidectomy become nose breathers after the operation.5 As the mouth can then be kept closed, it is envisaged that the tension in this muscle ring is then reduced. Summary
The purpose of the present study was to determine whether adenoidectomy (and hence a change to nose breathing) is followed by: (1) a change in the inclination of upper and lower incisors. (2) a change in the width of the upper arch, and/or (3) an effect on the sagittal depth of the bony nasopha,rynx. The clinical material comprised the children in a previous study who were at least 8 years old and in whom the upper and lower incisors had erupted before the initial examination, which was followed by adenoidectomy. A second examination was made 1 year later. The group undergoing adenoidectomy numbered thirty-seven children, and there were thirty-seven controls.
Efects
of adenoidectomy
15
All the children were examined with respect to forty-six variables, grouped under the headings of anamnesis, adenoids, dentition, airflow, and skeleton. Measurements were obtained for each child from lateral radiographs and casts, and the nasal airflow was recorded in liters per minute. Group means for the two examinations have been compared and relationships have been studied with the aid of simple correla,tion analysis and multiple regression analysis. It was found that in the year between the examinations, the, children who underwent adenoidectomy had undergone a significantly greater increase than the controls in the angle of the upper and lower incisors, respectively, to the nasion-sella and the mandibular lines. The adenoidectomy group also had a significantly greater increase in the mean width of the upper arch between the first molars, this width being enlarged most in the children who had switched from mouth to nose breathing after adenoidectomy. Furthermore, the mean sagittal depth of the nasopharynx had increased only for the children who underwent a,denoidectomy, the increment in this group being significantly different from 0. The study accordingly demonstrates that dentitional changes occur after adenoidectomy in children who were mouth breathers preoperatively because of nasal obstruction. The size of the nasopharyngeal cavity also changed in the children who switched from mouth to nose brea.thing after adenoidectomy. Since the dentition seems to be affected to some extent by the combined occurrence of adenoids and mouth breathing, an assessment of indications for adenoidectomy should include orthodontic evaluations. I wish Sweden, for
to express my sincere thanks to Associate Professor assisting with the statistical processing of the material.
Gunnar
Eklund,
Uppsala,
REFERENCES
1. Graber, T. M.: Orthodontics-Principles and practice, Philadelphia, lW1, W. B. Saunders Company, p. 97. 2, Holik, F.: Relation between habitual breathing through the mouth and muscular activity of the tongue, Cesk. Stomatol. 57: 170, 1957. 3. Linder-Aronson, S.: Adenoids-Their effect on mode of breathing and nasal airflow and their relationship to characteristics of the facial skeleton and the dentition, Acta Otolaryngol., Supp. 265, 1970. 4. Linder-Aronson, S. : Adenoida vegetationer och effekten av adenoidektomi, Sven. Tandllk. Tidskr. 64: 399, 1971. 5. Linder-Aronson, S.: Effects of adenoidectomy on mode of breathing, size of adenoids and nasal airflow, Pratt. Otolaryngol. (Ziirich)228: 285, 1973. 6. Lundstrom, A. : Tooth size and occlusion in twins, Basel, 1948, S. Karger. 7. Moorrees, C. F.: The dentition of the growing child, Cambridge, Mass., 1959; Harvard University Press. 8. Ricketts, R. M.: Respiratory obstructions and their relation to tongue posture, Cleft Palate Bull. 8: 3, lQ58. 9. Subtelny, J. D.: The significance of adenoid tissue in orthodontia, Angle Orthod. ‘24: 59, 1954. 10. Tomes, Ch. S.: On the developmental origin of the V-shaped contracted maxilla, Monthly Rev. Dent. Surg. 1: 2, 1872.