Longitudinal changes of the natural craniofacial and dentoalveolar complex in the fourth decade of life

Introduction

This study aimed to longitudinally examine the changes in craniofacial and dentoalveolar regions during the third and fourth decades of life.

Methods

The data from this study constitute the cephalometric films and plaster models of 8 female and 8 male dental students or dentists. The mean chronological ages of the subjects at the first observation period was 22.09 years for females and 22.64 years for males. The material was collected over 3 intervals: 1985-1989, 1998-2000, and 2016-2017. The observation period was approximately 28 years. Acquired cephalometric recordings and dental models were assessed for subjects in their 20s (baseline), 30s, and 40s. Maxillary, mandibular, maxillomandibular, soft-tissue, and dentoalveolar cephalometric variables were measured with a cephalometric analysis software, and dental cast measurements were made with a digital caliper. Changes in the cephalometric films and dental casts were evaluated statistically.

Results

Statistical analysis showed that the length of the midfacial region increased with age. The height of the lower face increased significantly in females and the mandible can be seen mildly rotating to the posterior as it increased in length. The nose moved slightly forward and downward in males and females. Upper lip height was significantly increased in females; however, there was a significant reduction in upper lip thickness for males and females. Soft-tissue pogonion measurements showed a significant forward and downward chin movement in females. Overjet was significantly increased in females, whereas the mandibular arch length was significantly decreased for both sexes, although it was more prominent in females. There was a loss of space in the anterior segments of males and females, resulting in increased crowding. However, the loss of space was only significant in the mandible.

Conclusions

We observed significant changes in skeletal, soft-tissue, and dentoalveolar variables of subjects in their third and fourth decades of life. The fact that many changes have occurred throughout this study demonstrates that the process of maturation and aging is ongoing.

Highlights

•

Changes in skeletal tissue observed in the third and fourth decades of life.
•

Significant changes in soft-tissue occurred in the third and fourth decades of life.
•

The process of maturation and aging is ongoing.

The human face serves as the main source of identity, personality, and perception of beauty. Biologically, the face is constructed of both hard and soft tissues. As interrelated entities, hard-tissue modification may impact the manifestation of soft-tissue changes over time. However, alterations in craniofacial bone structure with age are not as well understood as those seen at the soft-tissue level.

Several studies in biological anthropology, orthodontics, and craniofacial surgery have examined macroscopic differences in craniofacial dimensions. These studies have noted that many of the bones of the face display increased thickness, length, and breadth over time. Moreover, it has been known that the craniofacial skeleton remodels through a differential growth process. ^,

Although there are studies describing postnatal craniofacial growth, less is known about craniofacial changes in adulthood. Longitudinal data from early and middle adulthood were not as sufficient as from growing subjects. The magnitude of changes in skeletal and soft-tissue craniofacial morphology after pubertal growth ends is minor but clinically significant. Few studies evaluating growth beyond the third and fourth decade have indications that facial changes are an ongoing process throughout life. Forward movement of the nose, lips retraction, and mandible posterior rotation were observed in 10-year longitudinal studies conducted in adulthood.

Generally, the follow-up studies showed a significant increase in anterior facial height and maxillary and mandibular dentoalveolar height. ^,

Changes in skeletal, soft-tissue, and tooth morphology may be minor in adults. However, the number of adults seeking orthodontic treatment and orthognathic surgery has increased. It is important to know the changes that normally occur in the adult craniofacial complex to determine whether there is a relapse or a natural physiological change after orthodontic treatment. Knowledge of the possible craniofacial changes might be evaluated in planning orthodontic or orthognathic surgery treatment. Therefore, this study aimed to longitudinally examine the changes in craniofacial and dentoalveolar regions during the third and fourth decades of life.

Material and methods

The data consisted of natural head position lateral cephalometric films and dental casts of 16 (8 female and 8 male) Turkish dental students and dentists from the Ankara University Faculty of Dentistry. The subjects were examined at 3 time intervals: 1985-1989 (T1), 1998-2000 (T2), and 2016-2017 (T3). The chronological ages of the subjects and the duration of the observation period are shown in Table I . Subjects were aged 22 years at T1, 32 years at T2, and 49 years at T3. Subjects with a history of orthodontic treatment and/or comprehensive prosthodontic rehabilitation, botox and/or dermal filler, maxillofacial and/or plastic surgery, and missing teeth (except third molars) were excluded from the study. Because of these criteria, data from 16 subjects were obtained at the end of the observation period. Ten of the subjects in the study had a Class I malocclusion, 6 had mild Class II molar relationship, and all subjects had orthognathic profiles without excessive protrusion or retrusion. The vertical skeletal pattern of the subjects was normodiverged. At T1, GoGn/SN was 29.80° ± 1.90° in females and 29.81° ± 2.98° in males.

Table I

Chronological age of the subjects and duration of the observation period

Subjects	T1	T2	T3	T2 − T1	T3 − T2	T3 − T1
Female (n = 8)	22.09 ± 2.53	32.66 ± 2.44	49.41 ± 2.51	10.45 ± 2.20	16.69 ± 0.58	27.05 ± 2.02
Male (n = 8)	22.64 ± 3.31	31.93 ± 3.87	49.03 ± 3.37	9.75 ± 1.54	18.58 ± 3.77	27.74 ± 3.73

The lateral cephalometric film recordings of 16 subjects were obtained at a standardized subject-to-film distance (155 cm), the teeth in centric occlusion, the Frankfurt horizontal plane parallel to the ground, and the head fixed with a cephalostat rod. T1 and T2 lateral cephalograms were obtained using Orthoceph 10E (Siemens AG, Berlin, Germany), whereas T3 lateral cephalograms were obtained using OrthophosXG plus Ds/Ceph (Sirona Dental Systems GmbH, Bensheim, Germany). Magnification adjustments were made between old and new films.

T1 and T2 lateral cephalograms were not found in digital form, so these films were scanned using an Epson Expression scanner (10000XL; Epson, Long Beach, Calif), per the manufacturer’s instructions. The professional mode was used with 16-bit gray scale, 300 dpi resolution, and 100% scale. The scanned films were saved as JPG files with 2750 × 3509 dimensions and 300 dpi resolutions. The PorDios (Purpose on Request Digitizer Input-Output system; Institute of Orthodontic Computer Science, Aarhus, Denmark) cephalometric analysis software was used to perform and include the cephalometric points, planes, and angles necessary for linear and angular measurements ( Fig 1 ). Maxillary, mandibular, maxillomandibular, soft-tissue, and dentoalveolar cephalometric variables were measured. Adjustments were made for the standard magnification and calibration with the help of the x-ray ruler. Anatomic reference points were marked by the same researcher (A.S.).

Dental casts were analyzed from T1, T2, and T3. Five parameters were directly measured for each arch on the dental casts using a digital caliper (Mitutoyo, Kanagawa, Japan). Dental cast measurements used in the model analysis were intercanine width (ICW), interpremolar width, intermolar width (IMW), arch length (AL), and arch length discrepancy (ALD) ( Fig 2 ). This study was approved by the Ankara University Faculty of Dentistry Research Ethics Committee (Decision Number: 10/19). Cephalometric films and dental models of subjects were obtained with their consent.

Statistical analysis

The data were analyzed using SPSS software (version 21.0; IBM, Armonk, NY). The reliability was assessed between measurements using interclass correlation coefficients with 95% confidence intervals. Regarding the parameters obtained because of the examination of the lateral cephalometric films and dental model measurements, Student t tests were performed for between-group comparison, whereas paired t tests were used for intragroup comparison. The significance level was set at P <0.05.

Results

All cephalometric landmarks and measurements were repeated after 4 weeks. The confidence intervals between the obtained and first measurements were evaluated and found to be clinically acceptable (0.94-0.99). The chronological age of the female and male subjects and the duration of the observation periods are given in Table I . Tables II-V show the statistical evaluation of intragroup and intergroup differences. The overall changes from T1 to T3 are illustrated in detail for both genders with mean facial diagrams ( Fig 3 ).

Table II

Skeletal measurements

Measurements	T1	P value	T2	P value	T3	P value	T2 − T1	T3 − T2	T3 − T1
SNA		NS		NS		NS
Female	80.96 ± 1.24		81.38 ± 1.33		81.05 ± 1.30
Male	79.44 ± 0.74		79.67 ± 0.79		79.89 ± 0.97		∗
A-Ver		NS		NS		NS
Female	64.37 ± 0.97		65.25 ± 1.06		66.28 ± 1.44		∗∗∗		∗
Male	67.29 ± 2.37		65.74 ± 1.97		68.60 ± 2.33				∗
A-Hor		NS		NS		NS
Female	48.92 ± 1.44		48.63 ± 1.08		48.35 ± 1.51
Male	52.91 ± 1.37		52.53 ± 1.85		52.41 ± 2.18
ANS-Ver		NS		NS		NS
Female	70.15 ± 0.97		70.91 ± 1.09		72.81 ± 1.92
Male	74.29 ± 2.96		72.51 ± 1.67		74.01 ± 3.55
ANS-Hor		∗		∗		NS
Female	42.74 ± 1.43		42.80 ± 1.27		42.69 ± 1.51
Male	46.82 ± 0.77		47.05 ± 0.94		45.33 ± 1.20				∗
PNS-Ver		NS		NS		NS
Female	18.02 ± 0.92		18.08 ± 0.91		19.16 ± 1.17
Male	16.97 ± 1.45		16.19 ± 1.34		16.09 ± 1.57
PNS-Hor		∗∗		∗		NS
Female	40.53 ± 0.85		41.05 ± 0.77		40.92 ± 0.99
Male	44.67 ± 0.88		44.05 ± 0.67		43.77 ± 1.40
SNB		NS		NS		NS
Female	77.89 ± 1.43		77.98 ± 1.54		77.48 ± 1.48
Male	77.56 ± 0.87		77.45 ± 1.13		77.68 ± 1.07
B-Ver		NS		NS		NS
Female	58.13 ± 2.04		58.65 ± 2.13		60.00 ± 2.31
Male	61.36 ± 2.67		59.77 ± 2.23		62.71 ± 3.20
B-Hor		∗∗		∗		∗∗
Female	84.34 ± 1.51		85.53 ± 1.51		84.70 ± 1.40
Male	93.56 ± 1.97		92.49 ± 2.38		93.60 ± 1.95
Pg-Ver		NS		NS		NS
Female	59.36 ± 2.45		60.12 ± 2.55		60.79 ± 2.89
Male	62.92 ± 3.01		61.50 ± 2.72		63.30 ± 3.28
Pg-Hor		∗∗		∗∗		∗∗
Female	97.48 ± 1.65		97.90 ± 1.66		99.04 ± 1.87
Male	108.27 ± 2.35		107.68 ± 2.27		110.58 ± 2.51
Me-Ver		NS		NS		NS
Female	54.04 ± 2.43		54.72 ± 2.50		54.27 ± 2.98
Male	56.45 ± 2.73		55.22 ± 2.78		56.83 ± 3.21
Me-Hor		∗∗∗		∗∗		∗∗
Female	103.85 ± 1.39		104.55 ± 1.31		104.63 ± 1.65
Male	115.30 ± 2.21		114.83 ± 2.28		115.63 ± 2.49
GoGn/SN		NS		NS		NS		∗
Female	29.80 ± 1.90		29.73 ± 2.10		31.02 ± 1.99
Male	29.81 ± 2.98		30.02 ± 3.28		29.84 ± 3.09
ANB		NS		NS		NS
Female	3.07 ± 0.84		3.40 ± 0.83		3.57 ± 1.01
Male	1.87 ± 0.77		1.93 ± 0.98		2.21 ± 0.66
N-ANS		∗		∗		NS
Female	51.33 ± 1.41		51.54 ± 1.27		51.16 ± 1.79
Male	55.82 ± 0.96		55.88 ± 1.04		54.71 ± 1.16
N-Me		∗∗∗		∗∗		∗∗
Female	112.92 ± 1.44		113.67 ± 1.33		114.23 ± 1.86			∗
Male	124.99 ± 2.41		124.33 ± 2.51		125.22 ± 2.57			∗
A-Me		∗∗		∗∗∗		∗∗	∗		∗
Female	56.14 ± 0.89		57.16 ± 0.78		57.88 ± 0.91
Male	63.45 ± 1.65		63.35 ± 1.38		64.81 ± 1.80
S-Go		∗		NS		∗
Female	75.05 ± 1.85		75.63 ± 2.00		74.38 ± 2.53
Male	84.24 ± 3.43		82.70 ± 4.04		84.70 ± 3.95			∗

Note. Values are presented as mean ± standard error of the mean.

NS , not significant.

∗ P <0.05

∗∗ P <0.01

∗∗∗ P <0.001.

Table III

Soft-tissue measurements

Measurements	T1	P value	T2	P value	T3	P value	T2 − T1	T3 − T2	T3 − T1
Pr-Ver		∗∗		∗∗		∗
Female	93.95 ± 1.05		94.85 ± 1.25		96.53 ± 1.87		∗		∗
Male	105.24 ± 2.97		102.04 ± 1.96		104.76 ± 3.14
Pr-Hor		∗		NS		NS
Female	37.71 ± 1.67		38.56 ± 1.82		38.92 ± 2.04
Male	43.55 ± 1.74		43.48 ± 1.61		42.14 ± 1.82
Sn-Ver		∗		∗		NS
Female	79.09 ± 1.02		79.27 ± 1.10		79.24 ± 1.44
Male	86.66 ± 2.56		84.65 ± 2.11		85.89 ± 2.96
Sn-Hor		∗		∗		NS
Female	47.85 ± 1.27		47.89 ± 1.47		48.31 ± 1.75
Male	52.16 ± 0.84		52.11 ± 1.20		50.73 ± 1.67
Ls-Ver		NS		NS		NS
Female	80.06 ± 1.22		80.42 ± 1.23		80.91 ± 1.51
Male	85.43 ± 2.31		84.03 ± 2.29		85.36 ± 2.80
Ls-Hor		∗∗		∗∗		NS
Female	62.07 ± 1.21		62.88 ± 1.41		64.99 ± 1.85			∗∗	∗∗
Male	69.64 ± 1.56		69.61 ± 1.48		70.84 ± 1.98
Li-Ver		NS		NS		NS
Female	76.76 ± 1.79		77.45 ± 1.87		78.08 ± 2.02
Male	82.00 ± 2.34		81.87 ± 2.32		83.38 ± 2.80				∗
Li-Hor		∗∗		∗		NS
Female	75.79 ± 1.43		76.19 ± 1.41		76.18 ± 1.72
Male	82.98 ± 1.59		82.39 ± 1.67		81.51 ± 2.12
B’-Ver		NS		NS		NS
Female	68.85 ± 2.10		69.33 ± 2.08		70.55 ± 2.34
Male	73.50 ± 2.60		72.06 ± 2.02		75.51 ± 3.13				∗
B’-Hor		∗∗		∗∗		∗
Female	83.55 ± 1.60		85.10 ± 1.51		86.05 ± 1.94
Male	92.59 ± 1.82		94.35 ± 2.22		94.51 ± 2.21
B-B’				∗∗		∗
Female	10.92 ± 0.54	∗	10.90 ± 0.35		11.10 ± 0.38
Male	12.37 ± 0.37		12.52 ± 0.33		13.02 ± 0.53
Pg _s-Ver		NS		NS		NS
Female	70.12 ± 2.41		71.13 ± 2.50		71.93 ± 2.76				∗∗
Male	75.97 ± 3.10		74.89 ± 2.55		77.73 ± 3.40
Pg _s-Hor		∗∗∗		∗		∗∗
Female	96.63 ± 1.49		98.39 ± 1.60		100.37 ± 1.52				∗
Male	107.55 ± 2.34		107.23 ± 2.60		110.77 ± 2.63
Pg-Pg _s		∗∗		∗∗∗		∗∗
Female	10.95 ± 0.61		11.19 ± 0.56		11.38 ± 0.69				∗
Male	13.15 ± 0.25		13.77 ± 0.17		14.52 ± 0.42				∗
L1i-Li		NS		NS		NS
Female	15.27 ± 0.50		15.48 ± 0.61		15.42 ± 0.62
Male	16.78 ± 0.93		17.49 ± 1.36		16.01 ± 0.56
U1i-Ls		NS				NS
Female	14.75 ± 0.83		14.17 ± 0.90	NS	12.50 ± 0.70			∗	∗∗
Male	16.79 ± 0.87		16.06 ± 0.79		14.21 ± 0.52			∗	∗
N _s-Sn		∗∗		∗		NS	NS
Female	57.32 ± 1.27		57.60 ± 1.51		58.09 ± 1.81
Male	62.79 ± 1.03		62.28 ± 1.28		60.67 ± 1.79
Sn-Me _s		∗∗∗		∗∗∗		∗
Female	67.27 ± 0.97		67.98 ± 0.98		68.68 ± 1.02		∗		∗
Male	78.17 ± 1.83		77.76 ± 1.89		76.96 ± 2.98