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Department of Orthodontics, The Royal Hospitals, School of Dentistry, Grosvenor Road, Belfast BT12 6BA, Northern Ireland
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Abstract |
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 Top Abstract IntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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Various dimensions representative of dento-facial morphology were measured and the changes in dimensions over time were calculated and tested for significance with the one sample t-test.
In general, skeletal and dental relationships remained relatively stable. Face height and jaw length dimensions increased by small amounts.
Key words: Adult facial growth
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Introduction |
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TopAbstractIntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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Behrents et al.,
1989;
Bondevik, 1995).
Longitudinal studies on untreated, dentate subjects after the age of 20 years using cephalometric
radiographs report an increase in anterior face height, but a measure of disagreement exists as to
the
nature and amount of the changes in some other dimensions, notably incisor angulations (Forsberg, 1979;Sarnäs and Solow, 1980; Behrents, 1985;Forsberg et al., 1991; Bishara et al., 1994; Bondevik, 1995).
The purpose of the present investigation was to examine the changes in some dentofacial parameters in untreated, dentate subjects during the third decade of life.
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Subjects and Methods |
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TopAbstractIntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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The sample included ideal and good occlusions, and a variety of malocclusions. None had orthodontic treatment. All had intact lower arches, anterior to and including second molars, at all stages. Third molar status was variable and included congenitally missing, extracted, erupted, and impacted teeth.
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Measurements |
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TopAbstractIntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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The changes in measurements from T1-T2, T2-T3, and T1-T3 were calculated. Positive values indicated an increase in height and length dimensions, the inter-incisal and maxillary/mandibular planes angle, and proclination of incisors.
All radiographs were traced twice at an interval of at least 1 month by one individual (JG). Each tracing was digitized once and the error of measurement calculated between replicate tracings. The mean value was used for the calculations.
Statistical Tests
Systematic and random measurement errors were tested between replicate measurements by
means of
the one sample t-test and the coefficient of reliability (Houston, 1983).
Means and standard deviations for all measurements at T1, T2, and T3 were calculated for males and females separately.
Differences in measurements at T1, and differences in the change in measurements from T1 to T2 and T2 to T3 between males and females were tested with the independent samples t-test.
The significance of the changes in measurements between T1 and T2, T2, and T3, and T1 and T3, and the differences between the changes in inter-maxillary lengths (Ar/A-Ar/B) were tested with the one sample t-test.
Significance was set at the 5 per cent level.
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Results |
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TopAbstractIntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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At T1 (18 years) there were no significant differences in incisor inclinations between males and females. The maxillary-mandibular planes angle (ANS-PNS/Go-Me) was larger in females (5.53, P < 0.05).
Anterior and posterior face height and jaw length measurements were larger in males (Table 1).
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From T2 to T3 (Table 3) the incisor angulations did not change significantly in any of the groups. The maxillary/ mandibular planes angle (ANS-PNS/Go-Me) increased significantly in females (0.84 degree, P < 0.05). Anterior face height, upper (N/ANS-PNS), lower (Me/ANS-PNS) and total (N/Me) increased significantly in all groups. Posterior face height (Ar/Go) increased significantly in males (1.68 mm. P < 0.01) and the pooled sample (0.92 mm, P < 0.05), but not in females. Maxillary length (Ar/A) increased significantly in all groups. the changes in Ptm/A were non-significant. Mandibular length (Ar/B and Ar/ Pog) increased significantly in all groups. Mandibular body length (Go/Pog) increased significantly in females and the pooled sample but non-significantly in males.
The cumulative changes from T1 to T3 are shown in Table 4. The differences between the changes in inter-maxillary lengths (Ar/A-Ar/B) were non-significant (Table 5).
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Discussion |
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TopAbstractIntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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The inclination of both upper and lower incisors did not change significantly between 18 and 28
years
with the exception of the maxillary incisors in females which retroclined on average by 0.9
degree in the
earlier part of the observation period between 18 and 21 years. Bondevik (1995)
reported retroclination of maxillary incisors of 1.44 degrees in females in the later age group
between
22 and 33 years, although Sarnäs and Solow (1980) found no
significant change
in incisor inclinations between 21 and 26 years.
During the earlier period, between approximately 13 and 18-20 years several studies have shown
a
tendency for the incisors to upright (Björk and Palling, 1954; Siatowski,
1974; Persson et al., 1989; Love et
al., 1990; Foley and Mamandras, 1992) although
Sinclair and
Little (1985)
found no significant change in incisor inclination between 10 and 20 years.
Siatowski (1974) claimed that incisor uprighting was sufficient to
account for
the
increase in lower arch crowding, which commonly occurs in untreated subjects between 13 and
18
years. Increases in crowding averaging approximately 2.00 mm and ranging up to 6.0 mm have
been
reported during this period of more active growth (Richardson, 1979; Sampson et
al., 1893).
The relative stability of the incisor relationships in the present investigation is consistent with the
minor
changes in lower arch alignment reported in the same material (Richardson and
Gormley,
1998). Between 18 and 28 years the increase in lower arch crowding averaged only
0.3
mm in males
and 0.4 mm in females.
The maxillary/mandibular planes angle did not change significantly in males, but increased,
indicating
slight backward rotation of the mandible, by 0.84 degree in females between 21 and 28 years.
Sarnäs and Solow (1980), Bishara et al. (1994) and
Bondevik (1995) all reported no significant change in the
maxillary/mandibular
planes
angle in samples of minimum age 21 years, although half of the females in Bondevik's (1995) sample showed backward rotation.
Total anterior face height N/Me increased on average by 2.7 mm in the pooled sample from
T1-T3
with no significant difference between males and females. Most of the change 2.1 mm occurred
between T2 and T3 which is perhaps surprising since it might be expected that the change would
diminish with age. It is, however, not dissimilar to the 1.5 mm increase reported by Sarnäs
and
Solow (1980) between 21 and 26 years, but larger than those of Forsberg
(1979) who found increases of 0.4 and 0.6 mm between 24-29 years and
24-34 years,
respectively. According to Sarnäs and Solow (1980),
Fosberg's
(1979) figures suggest that the major part of the anterior face height
increase in
the third decade
takes place in the first half of the decade. The present findings, together with those of Bondevik (1995) who reported a 1.0-mm increase in anterior face height between 22
and
33 years, and
Bishara et al. (1994) who found a 1.9-mm increase between 25
and
46 years
refute this statement. Apparently, anterior face height increase continues well into the fourth
decade. In
all the above studies, including the present one and in those on earlier age groups from 14 to 20
years
(Love et al., 1990; Foley and Mamandras, 1992) most of the
anterior face height increase occurred in the lower face from ANS-PNS/Me. This, together with
the
relative stability of the maxillary/mandibular planes angle in males, suggests that the increase in
anterior
face height is probably largely due to continued tooth eruption. In females the slight increase in
the
maxillary/mandibular planes angle may contribute to the increase in anterior face height.
In females the posterior face height from Ar-Go did not increase significantly throughout the study in contrast to the anterior face height. This would account for the slight increase in the maxillary/mandibular planes angle. In males the posterior face height increased by almost as much as the anterior face height.
Bishara et al. (1994) measuring posterior face height in the same
way
from Ar
to Go found that anterior and posterior face heights increased by the same amount in females
with no
significant change in the mandibular planes angle from 25 to 46 years.
Length dimensions of both jaws increased in both sexes. The increases in Ar/A and Ar/B were
not
significantly different Table 5 indicating that there was no change in
antero-posterior jaw relationships
which is consistent with the relative stability of the incisor relationships. During the earlier
teenage years
Björk and Palling (1954) found that growth of the
mandible exceeds that of the
maxilla resulting in straightening of the profile and retroclination of the lower incisors which
may be one
of the reasons for the increase in lower arch crowding at that time.
Larger changes were found in Ar-Pog and Go-Pog probably due to increased chin prominence.
Slightly smaller jaw length increases were noted by Sarnäs and Solow (1980)
between 21 and 26 years, Bishara et al. (1994) between 25 and
46
years and
by Bondevik (1995) between 22 and 33 years.
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Conclusions |
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TopAbstractIntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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).
The clinical significance of these findings relates to postretention changes in orthodontically
treated
subjects, often attributed to late growth (Sarnäs and Solow, 1980; Behrents et al., 1989; Bondevik, 1995).
The
nature and extent of the
changes in the present untreated sample suggest that growth is unlikely to be a major cause of
postretention changes after the age of 20 years. It should be pointed out that these observations
are
based on average figures and do not preclude the possibility of changes in incisor inclination
leading to
lower incisor crowding in individual subjects, treated or untreated.
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Acknowledgments |
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Notes |
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References |
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TopAbstractIntroductionSubjects and MethodsMeasurementsResultsDiscussionConclusionsReferences |
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Behrents, R. G., Harris, E. F., Vaden, J. L., Williams, R. A. and Kemp, D. H. (1989) Relapse of orthodontic treatment results: growth as an etiologic factor,Journal of the Charles H Tweed Foundation , 17,65 –80.
Bishara, S. E., Treder, J. E. and Jakobsen, J. R. (1994) Facial and dental changes in adulthood,American Journal of Orthodontics and Dentofacial Orthopedics , 106,175 –186.[Medline]
Björk, A. and Palling, M. (1954) Adolescent age changes in saggital jaw relation, alveolar prognathy and incisal inclination,Acta Odontologica Scandinavica , 12,201 –232.
Bondevik, O. (1995)
Growth changes in the cranial base and the face: a longitudinal cephalometric study of linear and
angular
changes in adult Norwegians,European Journal of Orthodontics
, 17,525
–532.
Foley, T. F. and Mamandras, A. H. (1992) Facial growth in females 14 to 20 years of age,American Journal of Orthodontics and Dentofacial Orthopedics , 101,248 –254.[Medline]
Forsberg, C-M. (1979)
Facial morphology and ageing: a longitudinal cephalometric investigation in young adults,European Journal of Orthodontics
, 1,15
–23.
Forsberg, C-M., Eliasson, S. and Westergren, H. (1991)
Face height and tooth eruption in adults—a 20-year follow-up investigation,European Journal of Orthodontics
, 13,249
–254.
Houston, W. J. B. (1983) The analysis of errors in orthodontic measurements,American Journal of Orthodontics , 83,382 –390.[Medline]
Love, R. J., Murray, J. M. and Mamandras, A. H. (1990) Facial growth in males 16 to 20 years of age,American Journal of Orthodontics and Dentofacial Orthopedics , 97,200 –206.[Medline]
Persson, M., Persson, E. C. and Skagius, S. (1989)
Long-term spontaneous changes following removal of all first premolars in Class 1 cases with
crowding,European Journal of Orthodontics
, 11,271-
282.
Richardson, M. E. (1979)
Late lower arch crowding: facial growth or forward drift?European Journal of Orthodontics
, 1,219
–225.
Richardson, M. E. and Gormley, J. S. (1998)
Lower arch crowding in the third decade,European Journal of Orthodontics
20,597–607.
Sampson, W. J., Richards, L. C. and Leighton, B. C. (1983) Third molar eruption patterns and mandibular dental arch crowding,Australian Orthodontic Journal , 8, 10 –20.[Medline]
Sarnäs, K-V. and Solow, B. (1980)
Early adult changes in the skeletal and soft tissue profile,European Journal of Orthodontics
, 2,1
–12.
Siatkowski, R. E. (1974) Incisor uprighting: Mechanism for late secondary crowding in the anterior segments of the dental arches,American Journal of Orthodontics , 66,398 –410.[Medline]
Sinclair, P. M. and Little, R. M. (1985) Dentofacial maturation of untreated normals,American Journal of Orthodontics , 88,146 –156.[Medline]
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