Older Adults’ Facial Characteristics Compared to Young Adults’ in Correlation With Edentulism: A Cross Sectional Study

doi:10.21203/rs.3.rs-1512441/v1

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Older Adults’ Facial Characteristics Compared to Young Adults’ in Correlation With Edentulism: A Cross Sectional Study

https://doi.org/10.21203/rs.3.rs-1512441/v1

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BACKGROUND. Facial ageing is a result of superficial wrinkling and the changes of the underlying soft tissues and skeleton. The influence of tooth loss as geriatric characteristic on facial appearance is still poorly explained. The aim was to evaluate the facial characteristics of older adults in correlation with the dentition and compare them with young adults using a non-invasive 3D methodology.

METHODS. 90 participants older than 65 years, classified into 3 subgroups (edentulous, partially edentulous, toothed) and 30 young adults were evaluated. Their faces were scanned with an optical Artec 3D-scanner. Cephalometric analyses were determined using the computer program RapidForm. An independent t-test and ANOVA were used for the comparisons. The pair-wise post-hoc tests were applied with respect to the significant differences (P < 0.05).

RESULTS. Older adults' faces are wider and longer because of a longer middle facial height. Older adults have longer upper lip, larger nose, smaller nasolabial angle due to the nasal ptosis, narrower upper and lower lip vermilions and larger facial and lower facial height angles, resulting in a flat facial profile.

The ageing facial changes are the most pronounced in the edentulous. In comparison with the toothed they have a smaller facial height due to the smaller lower facial height, larger nasolabial angle, smaller mouth width, shorter upper lip and narrower lip vermilions. Their profile is more flat and lips more retruded.

CONCLUSIONS. The whole face proportions are changed in older adults and they are the most expressed with the tooth loss.

facial measurements

older adult

dentition

edentulous patients

The face is the most important part of the human body in the psychosocial sense. Negative influence of sun exposure, smoking and a low BMI on facial ageing are known and quite opposite to the high social status, low depression score and being married which are associated with a younger look (1). The influence of tooth loss as geriatric characteristic on facial appearance and their psychosocial consequences are still poorly explained. The geriatric dental medicine has been focused to maintain and restore good oral function. Not only eating also facial appearance was claimed as most important factor to oral health related quality of life (2). Nowadays, when life expectancy is increasing also age discrimination due to older people appearance is increasing (3).

Facial ageing represents the transition from youth, where there is an optimal relationship between bone morphology and the volume of the soft-tissue envelope, to the imbalances between these components that lead to the stigma of an aged face (4). It is the result of both superficial textural wrinkling of the skin and changes in the three-dimensional (3D) topography of the underlying structures, both the soft-tissue envelope and the underlying facial skeleton (5), which is important for the overall facial 3D contour and suspension of the soft tissues.

The irreversible alveolar ridge resorption of both jaws follows the loss of teeth, while the mean number of lost teeth increases with age (6). The loss of incisors and canines generally results in a concave facial profile (7). Reduced height of the tooth crown due to attrition strongly affects the aesthetics of the mouth.

The loss of supporting bones and teeth strongly influences the covering soft tissues and leads to the formation of wrinkles and compensatory mechanisms of the mimic muscles (8). Senile ptosis of the upper eyelid and inferiorly movement of the eyebrows leads to a prolongation of the upper-face third (9). Soft-tissue changes in the middle facial third are dropping the line between the cheek and the lower eyelid, and leading to the presence of medial fat pads in the malar area. The prolongation of the nose is a result of a smaller nasolabial angle and ptosis of the tip of the nose (10). The most obvious changes of lower facial third are due to the resorption of jaws and face sagging. The upper lip lengthens and sags, while the lower lip becomes shorter (11). The lip vermilions become narrower, due to resorption of the upper and lower jaws, the atrophy of the orbicularis oris muscle and their inversion (12). Typically, there is chin ptosis and jowl formation (13), nasolabial fold appearance (14) and mouth commissures depression.

So far there is no reliable study that would determine the influence of edentulism on the facial appearance of older adults. The aim of our research was to objectively evaluate the characteristics of the older adults´ face in correlation with dentition and compare them with the young adults´ face with a non-invasive 3D methodology.

The study included 90 participants older than 65 years (41 males and 49 females) and 30 controls (15 young males and 15 young females). The inclusion criteria were no craniofacial anomaly, no history of major facial trauma, no history of plastic or orthognathic surgery, no facial paresis and no tremor. Male participants with facial hair were excluded to avoid artefacts. Older adults were classified into three subgroups. The first subgroup consisted of completely edentulous participants (15 males and 15 females), the second subgroup consisted of partially edentulous participants (13 males and 17 females) and the third subgroup were toothed participants (13 males and 17 females). The edentulous subgroup contained participants who had lost all their teeth at least 5 years ago (men 21 ± 9 years, women 22 ± 12 years). In the partially edentulous subgroup were participants with 5 or more teeth. The average number of teeth in partially edentulous women was 11 ± 5 teeth and in partially edentulous men 9 ± 4 teeth. Two-thirds of these teeth were in the intercanine region and one-third in transcanine region. Missing teeth were not replaced with fixed prosthodontics, but the participants had partial dentures. In the toothed subgroup were participants with stable occlusion, repeatable intecuspal position and the vertical dimension of the occlusion was maintained. They had all the teeth in the intercanine region and 3 or more functional dental units of posterior teeth. Premolar in occlusal contact was counted as 1 occlusal unit and the whole molar crown in occlusal contact was counted as 2 occlusal units. They had no removable dentures. Subjects in control group had complete dentition with second molars. The sex, age and body-mass index of the participants in the three research subgroups and the control group are presented in Table 1.

Table 1. Basic descriptive statistics of the study sample; number (N), average age in years with standard deviation (SD), median age and average body-mass index (BMI) with standard deviation (SD) for both sexes.

		N	age			BMI
			mean	SD	median	mean	SD
Controls M		15	24.6	2	24.8	24.2	3.7
Older adults	all	41	74.5	8	73.4	27.2	4.0
	toothed	13	72.5	10	68.1	27.4	4.0
	partially edentulous	13	75.8	6	75.1	29.2	4.3
	edentulous	15	75.0	7	74.7	25.5	3.2
Controls F		15	24	2		20.3	1.8
Older adults	all	49	78.1	9	78.7	26.6	4.3
	toothed	17	76.9	11	76.5	25.4	3.3
	partially edentulous	17	80.1	6	80.6	28.8	4.8
	edentulous	15	77.1	8	76.2	25.4	4.1

M-male, F-female

The 3D facial scans were obtained in all participants using an Artec 3D scanner, which uses the flying triangulation method for surface scanning (15). It is a safe, non-invasive and repeatable method (16). Before the study, the intra-rater reliability was verified with intraclass correlation and we proved that the method is reliable and that it does not introduce any bias.

During the acquisition, special attention was addressed to positioning the participant and relaxing the facial musculature. The participants were sitting in a relaxed posture with a natural head position, looking in front of themselves with a relaxed closed-mouth position (without contractions of mouth muscles), while the instructions were to not to swallow and keep both eyes open during image acquisition, which was less than 10 seconds. The natural head position was achieved by moving the head up and down a few times and then stopping the movement and looking into the distance. The relaxed closed-mouth position was achieved with repeated wide opening and closing of the mouth until light contact of the lips. All dentures were removed from the mouth.

The 3D surface images were then processed further using Artec Studio software to obtain 3D scans in the STL format. A further analysis was conducted using the computer program RapidForm 2006 (INUS Technology Inc.). The 3D cephalometric analyses of 39 superficial facial landmarks were determined on 3D facial scans (Table 2 and Figure 1). The coordinates of the points (x,y,z) were imported into Microsoft Excel to calculate the values of the different parameters.

The distances, lines, angles and ratios determined by the cephalometric landmarks are listed and described in Table 3 and presented in Fig. 2 and 3. The obtained values of the observed changes and parameters were exported to Excel and SPSS (version number: 18) for further analyses. An independent t-test was used to compare the average values of the parameters between older adults and the control group separately for men and women. We compared the average values of the parameters between the three different subgroups and the control group and the three subgroups mutually using analysis of variance (ANOVA) statistics. If the differences between the subgroups were significant, we applied pair-wise post-hoc tests with appropriate multiple comparison correction. The statistical significance was set at P < 0.05.

Table 2. List of facial landmarks (cephalometric points) used in the analyses.

SIGN	NAME	PROFILE DEFINITION	EN FACE DEFINITION
tr	Trichion	Line between scalp and forehead	Midpoint
g	Glabella	The most anterior point of the forehead	Midpoint
n	Soft tissue nasion	The most posterior point on the soft-tissue contour of the base of the nasal root at the level of the frontonasal suture	Midpoint of the nasal root
enL, enR	Endocanthion, left and right	/	Soft-tissue point located at the inner commissure of each eye fissure
exL, exN	Exocanthion, left and right	/	Soft-tissue point located at the outer commissure of each eye fissure
soL, soR	Supraorbitale, left and right	The most anterior point above the orbita	Midpoint between endocanthion and exocanthion
ioL, ioR	Infraorbitale, left and right	Prominent rim under the inferior eyelid	Midpoint between endocanthion and exocanthion
zyL, zyR	Zygoma, left and right	Point above lateral part of corpus ossis zygomatici before it straightens in the AP direction backwards
zypL, zypR	Zygoma prominenc, left and right	Intersection of vertical line through exL/R and transverse line through zyL/R
prn	Pronasale	The most anterior point of nasal tip	Midpoint of nasal tip
alL, alR	Ala nasi, left and right	/	The most lateral point on each alar contour
acL, acR	Alare curvature, left and right	/	Point at the facial insertion of each alar base
cm	Columella	/	Midpoint of the columella crest at the level of the nostril top points
sn	Subnasale	Contact of philtrum and columella
a	Subspinale	The most posterior point of the philtrum	Midpoint
lsL, lsR	Labiale superior, left and right	Midpoint of the vermilion line of the upper lip
St	Stomion	/	Midpoint of the horizontal labial fissure
liL, liR	Labiale inferior, left and right	Midpoint of the vermilion line of the lower lip
cphL, cphR	Crista philtri, left and right	/	Point at each crossing of the philtrum and cupids bow
chL, chR	Cheilion, left and right	Point at each labial commissure
b	Sublabiale	The most posterior midpoint on the labiomental soft-tissue contour that defines the border between the lower lip and the chin
pg	Pogonion	The most anterior midpoint of the chin
meL, meR	Menton, left and right	The point where the vertical point through chL/R reaches the lowest point of the chin
gn	Gnathion	The most inferior midpoint on the soft-tissue contour of the chin
goL, goR	Gonion, left and right	Ramus ascendens and corpus mandible tangents intersection	The most prominent point placed lateral and inferior to chL/R point

Table 3. List of cephalometric measurements used in the analyses.

FACIAL WIDTHS
Facial width (mm)	zyL-zyR
Mouth width (mm)	chL-chR
FACIAL HEIGHTS
Facial height (mm)	n - gn
Middle facial height (mm)	g - sn
Lower facial height (mm)	sn - pg
Upper-lip height (mm)	sn - st
Upper redness height (mm)	Ls - st
Lower redness height (mm)	St - li
Nose height (mm)	N - prn
FACIAL DISTANCES IN PROFILE (DEPTHS)
Distance between upper lip and E line (mm)
Distance between lower lip and E line (mm)
FACIAL ANGLES
Facial angle (°)	n-sn-pg
Soft-tissue ANB angle (°)	A-n-b
Angle of lower facial height (°)	Sn-st-pg
Nasolabial angle (°)	cm-sn-ls
FACIAL RATIOS (PROPORTIONS)
Facial width-to-height ratio	zyR-zyL/n-gn
Ratio between middle and lower facial height	g-sn/sn-pg
Ratio between upper lip height and lower facial height	sn-st/st-gn

The summarized results of the mean values and their SD for the observed parameters of both sexes are presented in Table 4. The results of the statistical comparison of subgroups are presented in Table 5.

Table 4

Mean values and their standard deviations (in brackets) for the observed parameters of the females and males.
	Cf (n = 15)	Sf (n = 49)	Tf (n = 17)	Pf (n = 17)	Ef (n = 15)	Cm (n = 15)	Sm (n = 41)	Tm (n = 13)	Pm (n = 13)	Em (n = 15)
Facial width (mm)	121.8 (4.0)	124.4 (6.9)	124.3 (7.2)	127.0 (7.0)	121.6 (5.5)	126.4 (6.4)	132.8 (5.6)	134.8 (4.5)	134.1 (6.5)	130.0 (4.7)
Mouth width (mm)	45.5 (4.9)	44.5 (5.7)	48.0 (5.0)	44.2 (4.9)	40.7 (4.9)	48.3 (2.1)	47.2 (5.3)	49.9 (5.9)	48.6 (2.9)	43.6 (4.5)
Facial height (mm)	112.4 (3.4)	111.8 (6.9)	114.8 (6.5)	113.1 (7.1)	107.1 (4.8)	117.6 (5.7)	124.3 (6.3)	128.3 (5.9)	124.3 (4.8)	120.8 (5.9)
Middle facial height (mm)	66.6 (3.9)	67.4 (4.5)	68.9 (4.1)	68.9 (3.1)	64.2 (4.6)	70.6 (4.5)	74.3 (4.6)	76.3 (5.5)	74.8 (4.2)	72.2 (3.2)
Lower facial height (mm)	52.0 (2.8)	50.9 (5.3)	53.0 (5.5)	50.8 (5.4)	48.7 (4.2)	55.1 (4.5)	55.9 (4.0)	57.5 (3.8)	57.2 (3.4)	53.5 (3.8)
Upper-lip height (mm)	19.5 (2.2)	20.1 (2.9)	21.8 (2.8)	19.6 (2.6)	18.7 (2.6)	21.4 (2.1)	22.9 (2.7)	24.0 (2.3)	22.8 (2.9)	22.0 (2.7)
Upper redness height (mm)	8.1 (1.1)	5.2 (1.6)	5.8 (1.4)	5.5 (1.5)	4.3 (1.4)	8.8 (1.4)	5.2 (1.7)	6.0 (1.9)	5.4 (1.7)	4.3 (1.1)
Lower redness height (mm)	9.0 (1.4)	6.2 (1.9)	7.0 (2.0)	6.2 (1.3)	5.2 (1.9)	8.7 (1.2)	6.5 (2.2)	6.1 (1.7)	7.7 (2.1)	5.8 (2.4)
Nose height (mm)	43.6 (3.2)	45.6 (3.9)	46.8 (4.3)	45.8 (3.9)	44.0 (3.0)	46.2 (3.9)	50.7 (4.3)	52.2 (4.5)	49.3 (4.1)	50.6 (4.1)
Distance upper lip to E line (mm)	6.9 (2.3)	10.8 (4.1)	7.6 (2.9)	10.8 (3.3)	14.5 (2.9)	7.3 (2.2)	12.3 (4.4)	9.2 (2.6)	13.1 (3.9)	14.3 (4.7)
Distance lower lip to E line (mm)	4.0 (1.6)	8.2 (4.1)	5.8 (2.9)	7.6 (3.2)	11.6 (3.9)	5.4 (2.6)	9.1 (3.9)	6.9 (2.6)	9.3 (4.0)	10.8 (4.1)
Facial angle (°)	165.6 (5.6)	173.1 (6.8)	167.2 (4.5)	176.2 (6.5)	176.1 (5.1)	164.9 (3.8)	172.8 (6.4)	171.6 (5.6)	174.6 (6.8)	172.4 (6.8)
Soft-tissue ANB angle (°)	5.9 (1.8)	2.0 (3.0)	4.4 (1.6)	1.2 (3.1)	0.2 (2.6)	6.3 (1.1)	1.6 (2.8)	3.3 (1.8)	1.1 (2.2)	0.7 (3.6)
Angle of lower facial height (°)	183.6 (8.9)	193.5 (14.8)	185.3 (9.5)	189.7 (11.6)	207.0 (14.2)	188.4 (7.0)	194.8 (15.9)	184.1 (7.5)	198.1 (14.4)	201.1 (18.4)
Nasolabial angle (°)	111.3 (13.0)	110.2 (14.0)	105.6 (8.8)	104.0 (12.4)	122.3 (13.4)	114.3 (8.9)	112.4 (15.1)	102.1 (11.4)	112.8 (16.4)	121.0 (11.6)
Facial width-to-height ratio	1.08 (0.04)	1.12 (0.08)	1.09 (0.08)	1.13 (0.10)	1.14 (0.05)	1.08 (0.06)	1.07 (0.05)	1.05 (0.04)	1.08 (0.04)	1.08 (0.06)
Ratio between middle and lower facial height	1.28 (0.11)	1.34 (0.16)	1.31 (0.16)	1.37 (0.15)	1.33 (0.17)	1.29 (0.12)	1.34 (0.12)	1.33 (0.13)	1.31 (0.11)	1.36 (0.11)
Ratio between upper lip and lower facial height	0.37 (0.03)	0.39 (0.04)	0.41 (0.04)	0.39 (0.05)	0.38 (0.04)	0.39 (0.02)	0.41 (0.03)	0.42 (0.03)	0.40 (0.04)	0.41 (0.03)

Cf – female controls, Sf – all older female, Tf – toothed female, Pf – partially edentulous female, Ef – edentulous female, Cm – male controls, Sm – all older male, Tm – toothed male, Pm – partially edentulous male, Em – edentulous male, n – number of participants.

Table 5

Statistical comparison of the differences between the groups (P values) in the female and male sample.
	Cf- Sf^a	Cf- Tf^b	Cf -Pf^b	Cf- Ef^b	Tf- Pf^b	Tf- Ef^b	Ef- Pf^b	Cm-Sm^a	Cm-Tm^b	Cm-Pm^b	Cm-Em^b	Tm-Pm^b	Tm-Em^b	Em-Pm^b
Facial width (mm)	0.071	0.714	0.136	1.000	0.508	0.514	0.082	0.001	0.003	0.008	0.393	0.940	0.066	0.136
Mouth width (mm)	0.506	0.577	0.904	0.074	0.095	0.001	0.140	0.251	0.792	0.999	0.027	0.756	0.004	0.027
Facial height (mm)	0.655	0.726	0.991	0.101	0.741	0.005	0.034	0.001	0.000	0.025	0.490	0.205	0.004	0.252
Middle facial height (mm)	0.535	0.482	0.454	0.406	0.999	0.007	0.006	0.010	0.015	0.109	0.825	0.711	0.058	0.281
Lower facial height (mm)	0.293	0.951	0.908	0.291	0.461	0.069	0.511	0.514	0.442	0.589	0.722	0.965	0.020	0.038
Upper-lip height (mm)	0.433	0.090	0.999	0.892	0.061	0.008	0.649	0.061	0.072	0.538	0.937	0.527	0.149	0.717
Upper redness height (mm)	0.000	0.000	0.000	0.000	0.798	0.013	0.060	0.000	0.000	0.000	0.000	0.629	0.028	0.212
Lower redness height (mm)	0.000	0.021	0.000	0.000	0.409	0.017	0.256	0.003	0.032	0.823	0.008	0.190	0.933	0.084
Nose height (mm)	0.084	0.124	0.456	0.995	0.718	0.122	0.433	0.001	0.005	0.277	0.047	0.236	0.616	0.727
Facial angle (°)	0.000	0.875	0.000	0.000	0.000	0.000	0.999	0.000	0.545	0.001	0.000	0.046	0.005	0.732
Soft-tissue ANB angle (°)	0.000	0.380	0.000	0.000	0.003	0.000	0.538	0.000	0.731	0.034	0.001	0.241	0.023	0.549
Angle of lower facial height (°)	0.003	0.979	0.503	0.000	0.562	0.000	0.001	0.000	0.035	0.001	0.010	0.480	0.943	0.655
Nasolabial angle (°)	0.103	0.125	0.051	0.359	0.917	0.001	0.000	0.000	0.012	0.000	0.000	0.131	0.056	0.941
Distance upper lip to E line (mm)	0.000	0.916	0.004	0.000	0.014	0.000	0.006	0.043	0.852	0.275	0.072	0.057	0.013	0.857
Distance lower lip to E line (mm)	0.000	0.459	0.018	0.000	0.299	0.000	0.006	0.571	0.089	0.991	0.525	0.137	0.002	0.273
Facial width-to-height ratio	0.044	1.000	0.431	0.289	0.347	0.230	0.951	0.694	0.677	1.000	1.000	0.410	0.390	1.000
Ratio between middle and lower facial height	0.231	0.966	0.451	0.883	0.562	0.957	0.757	0.215	0.835	0.958	0.499	0.937	0.852	0.645
Ratio between upper lip and lower facial height	0.071	0.062	0.796	0.890	0.247	0.200	0.984	0.034	0.129	0.861	0.296	0.390	0.878	0.655
Cf – female controls, Sf – all female older adults, Tf – toothed female, Pf – partially edentulous female, Ef – edentulous female, Cm – male controls, Sm – all male older adults, Tm – toothed male, Pm – partially edentulous male, Em – edentulous male.
^a – by independent t-test
^b – by analysis of variance (ANOVA)
The statistical significant results are bolded.

The face is one of the most diverse parts of the human body. The distinction between race, ethnic origin, sex and age is reflected in the faces of everybody. In today's society, which is dictated by the general social acceptance and the associated aesthetics, the appearance of the face has an important role. On the other hand the influence of tooth loss on facial appearance is still very poor explained. Recognizing the characteristics of an older adults’ face and being able to differentiate between the changes as a result of an ageing face or as a result of tooth loss have a large impact on treatment planning. 3D facial analysis is not involved in the standard diagnostic procedures for the dental treatment. However, diagnostics of the whole face is possible with a 3D scan of the facial surface. The cephalometric analysis of a 3D scans is a well-established and proven method nowadays.

Our study involved 18 cephalometric parameters on the basis of 39 facial landmarks of the older and young adults. The inclusion criterion was 65 years and older, since this is the definition of an older adult. At the same time, the main skeleton changes happen before that age, between the 4th and 5th decades (17). Males and females were examined separately, due to the sexual dimorphism (18). Since the participants have been edentulous for more than 2 decades, the major part of alveolar bone loss due to atrophy has already occurred.

When comparing the older and younger adults we have to take into account the difference in body mass index; older adults had significantly higher BMIs than younger ones, but there were no obese subjects among them. There were no differences in BMI between our subgroups of old adults and there were no differences regarding the sex in the old adults group. Also, it is known that, for example, high BMI conditioned changes of the face are ethnically and racially conditioned (19). So we have to state that in our study all the participants were Slovenian with Caucasian ancestry.

Different studies have proven that the face is getting wider with age (20). Facial width was larger in both sexes compared to the control group. The difference in the male group was statistically significant (p = 0.001) and close to statistical significance (p = 0.071) in the female group. Wider, older adults’ faces could also be a consequence of the higher BMI in the older adults’ group, because the influence of BMI on transverse facial dimensions has been proven (21). We assumed that the loss of teeth had no great impact on the facial width, but surprisingly our study proved narrower faces in the completely edentulous participants, most probably as the consequence of cheek soft-tissue ptosis.

Among the facial heights we excluded the parameter known as the upper facial height, because of large variability in the position of the trichion point, especially in the male group. Some studies have found that total facial height increases with age and the same was proved in our study, but some studies have proved the consistency in facial height in spite of tooth loss (22). Older adults had longer faces than the control group, statistically significant (p = 0.000) in the male group. We assumed that posterior rotation of the mandible (23), the increase in the dentoalveolar height with age (24), the effect of gravity on the soft tissues, the loosening of muscle tonus and the ageing of the chin’s soft tissues (13) are the main causes. Older adults had a longer middle facial height in comparison to the control group, statistically significant only in the male group (p = 0.010). The position of the glabella point on a facial scan does not change with years (25), so we assume the prolongation to be a result of the clockwise rotation of the maxilla (26) and the changed position of the spina nasalis anterior and the subnasale point. Older adults have a larger lower facial height than the controls. Shimizu et. al. have found shorter upper facial height and longer lower facial height comparing older adults with younger (27).

Facial height and lower facial height were significantly smaller in the completely edentulous subgroup than in the toothed subgroup for both sexes. Barlett et al. have studied skull differences in the toothed and edentulous older adults and discovered a shortening in the facial height, because of a shortening of the lower facial height as a result of teeth loosening and atrophy in both jaws (20). When comparing different older adults’ subgroups with each other, we observed the trend of reducing the size of the middle facial height with the loss of teeth, which is statistically significant among the female subgroups and close to statistical significance among the male subgroups.

Apart from the eyes, the most recognizable part of every face is the mouth. Ageing has no impact on mouth width, but the tooth loss does. The completely edentulous participants of both sexes had statistically significant narrower mouths than the toothed. Sex dimorphism is observed for this parameter, with men having wider mouths than women (28). The upper lip height was longer in the older adults’ group, and close to statistical significance in the male group (p = 0.072). Some studies have already proven it to be a result of gravity (11), but not a decrease in soft-tissue volume (29). The height was the longest for the toothed, and the shortest in the completely edentulous subgroup. The teeth in the intercanine sector are preventing the lip from curling inwards. Upper and lower lip rednesses were statistically significantly narrower for the older adults’ group in both sexes, as has been already described (11). The completely edentulous subgroup had the most narrow rednesses, which has not been described yet.

The nose is a very significant part of the face and has his own characteristics. In our study we have proven nose prolongation with age, no matter the shape and the size of the nose. Older men had statistically significant longer noses than the young adults, but no statistical significance was found in the female group (p = 0.084). The prolongation of the nose is a consequence of the intrinsic loosening of the lower lateral alar cartilages and the supporting ligaments (30). We discovered longer noses in the toothed than the completely edentulous adults. No such study comparing edentulism and nose length has been conducted before.

In the profile view of the scan we investigated the distance between the upper and lower lip and the aesthetic line (E-line). Ageing and tooth loss have an important influence on these two parameters. Older adults, especially the completely and partially edentulous, had statistically significant longer distances between the upper and lower lip and the E-line that means they have worse facial aesthetics.

The angles that we studied were the facial angle, the soft-tissue ANB angle, the angle of the lower facial height and the nasolabial angle. Older adults have a statistically significant (p = 0.000) larger facial angle than the young adults, which means a more flat profile. The largest facial angle is found for the completely edentulous participants, and this is statistically significant in the females.

In our study we placed the soft-tissue points a, n, b corresponding to the bone points in skeletal angle ANB. In a systematic review of the existing literature we did not find any study about the soft-tissue ANB angle changes in connection with dentition. The soft-tissue ANB angle was significantly (p = 0.000) smaller in the older adults’ group in comparison with the control group. This is a result of a narrowing of the upper lip and changing the a point position. The change was larger in the female group, because of the more voluminous upper lip. The soft-tissue ANB decreases with tooth loss as a result of maxilla and mandibular atrophy. After loosening of the teeth, especially in the upper jaw, the upper lip is retruded. The statistically significant differences were just in the female subgroups, which means that it is a sex-dependent parameter.

The lower facial height angle was significantly greater in the older adults’ group and shows the retrusion of the perioral tissues. With tooth loss there was a tendency to increase the angle. Studies have shown that the skeletal angle ANB, the inclination of the incisors and canines – supporting the upper lip and ptosis of tip of the nose – have the main impact on the nasolabial angle (31). We have proven a smaller angle in the older adults’ group, but it is not statistically significant. A smaller angle is especially significant in toothed and partially edentoulous participants, but the edentoulous groups of both sexes have significantly greater nasolabial angle, which means that tooth loss greatly affects it.

We wanted to simplify the ageing facial changes with facial ratios, which did not prove to be a good indicator. For the ratio between the facial height and the width there were no statistically significant differences, because of the changes in both directions.

Our goal was to determine the facial changes as their proportions observed for an ageing face; we wanted to evaluate the influence of edentulism. Age importantly influences on a larger facial width and a longer total facial height as a result of a longer middle facial height. The upper lip is longer and the nose is larger in the elderly. Upper and lower lip rednesses are narrower. The facial and the lower facial height angles are larger, resulting in a flat facial profile. The nasolabial angle is smaller due to the nose ptosis.

The facial changes in the elderly are the most pronounced in the completely edentulous. In comparison with the toothed group they have a smaller facial height due to the smaller lower facial height and the bigger nasolabial angle. Mouth width is smaller, the upper lip shorter, and there is a narrower upper and lower lip redness. Their profile is more flat and both lips more retruded than in the toothed.

Our study confirmed the influence of edentulism on the facial characteristics of older adults.

Ethics approval and consent to participate

Protocol of the study has been approved by the Slovenian National Medical Ethics Committee (MZ 0120-392/2016-2, KME 64/08/16). All methods were performed in accordance with the Declarations of Helsinki.

Written informed consent to participate in research was obtained from all the subjects.

Written informed consent for publication of their clinical details and clinical images was obtained from the participants.

Consent for publication

Written informed consent for publication of their clinical details and clinical images was obtained from the participants.

Availability of data and materials

All data generated and analysed during this study are included in this published article and its supplementary information files.

Competing interests

The authors declare that they have no competing interests.

Funding

Not applicable

Authors’ contributions

Our manuscript is a teamwork of four authors. ZS and DK have done a substantial contribution to conception and design of the manuscript. They collected the data, helped with statistical analysis and have drafted the article. MV work was based on the analysis of facial scans in RapidForm computer program, statistics and interpretation of the data. NIH was the menthor. She has helped us in all steps of our study and later she helped us to publish the manuscript. All authors read and approved the final manuscript.

Acknowledgements

Not applicable

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No competing interests reported.

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Older Adults’ Facial Characteristics Compared to Young Adults’ in Correlation With Edentulism: A Cross Sectional Study

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