Mechanotransduction as a means of remodeling the facial skeleton throughout life.

1. Aesth Plast Surg (2010) 34:603–611
DOI 10.1007/s00266-010-9519-5
ORIGINAL ARTICLE
Mechanotransduction: The Missing Link in the Facial Aging
Puzzle?
Safa E. Sharabi • Daniel A. Hatef • John C. Koshy •
Larry H. Hollier Jr. • Michael J. Yaremchuk
Received: 25 November 2009 / Accepted: 26 March 2010 / Published online: 4 May 2010
Ó Springer Science+Business Media, LLC and International Society of Aesthetic Plastic Surgery 2010
Abstract and position reflect these skeletal changes. Changes in
Background Craniofacial bony remodeling has been facial muscle function through the process of mechano-
recognized as an important contributor to the facial aging transduction may be responsible for these skeletal changes.
process. Multiple studies have demonstrated significant
craniofacial skeletal changes with age. However, no review Keywords Craniofacial bony remodeling Á Craniofacial
has assembled this information in a concise, cogent fash- skeleton Á Facial aging Á Facial rejuvenation Á
ion. Furthermore, the etiology of these skeletal changes has Mechanotransduction
not been elucidated. This information is important for
understanding the mechanisms of facial aging and for
further development of facial rejuvenation. Aging faces demonstrate common changes in contour and
Methods A literature review of all articles discussing the position of anatomic landmarks. These changes include
remodeling of the craniofacial skeleton with age was per- descent of the brow [1], changes in the contour of the upper
formed. Studies that used objective measurements of cra- eyelid [1], medialization of the lateral canthus [2], descent
niofacial skeletal parameters for different age groups were of the lower eyelid [3], deflation of the infraorbital skin
collected and analyzed. envelope [1], increased visibility of the lid–cheek junction
Results The studies demonstrated consistent morphologic and nasojugal crease [1], increased prominence and depth
changes in the craniofacial skeleton with age. These of the nasolabial fold [4], and increased prominence of the
changes included trends toward increased facial bony labiomandibular crease [5]. These changes are the most
width in women; contour changes of the orbit, anterior recognized changes of facial aging and the targets of cur-
maxilla, and mandibular body; and decreased dimensions rent facial rejuvenation procedures.
of the glabellar, pyriform, and maxillary angles. The visible signs of facial aging are most commonly
Conclusions The craniofacial skeleton remodels with attributed to changes in the skin and soft tissue. With age,
aging. Many of the observed changes in soft tissue contour the thickness and elasticity of skin decrease, the amount
and position of the subcutaneous tissue change, and the
adherence of the soft tissue envelope decreases [6]. Com-
Electronic supplementary material The online version of this bined with the presence of gravity and environmental
article (doi:10.1007/s00266-010-9519-5) contains supplementary factors such as smoking and sun exposure, these factors are
material, which is available to authorized users. considered by many to be the main contributors to the
typical aged facial appearance [7].
S. E. Sharabi Á D. A. Hatef Á J. C. Koshy Á L. H. Hollier Jr. (&)
Division of Plastic Surgery, Baylor College of Medicine, 6701 In addition to the soft tissue changes, remodeling of the
Fannin Street, CC.610.00, Houston, TX 77030, USA craniofacial skeleton with age has been demonstrated.
e-mail: larryh@bcm.edu Separate studies have shown bony remodeling in the orbit
(changes in contour of the superior and inferior orbital
M. J. Yaremchuk
Division of Plastic Surgery, Massachusetts General Hospital, rims) [8, 9], maxilla (retrusion and apparent clockwise
Boston, MA, USA rotation) [10–16], and mandible (changes in contour) [17].
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2. 604 Aesth Plast Surg (2010) 34:603–611
Unlike the extensively studied soft tissue envelope, these objective measurement tools or did not compare
there is neither a review that assembles the information groups in either of these ways were not included.
addressing the remodeling of the facial skeleton in a con-
cise cogent fashion nor an understanding of why this
remodeling occurs. This report presents a systematic Results
review of the literature addressing the morphologic chan-
ges that occur in the craniofacial skeleton with aging. It The study results are presented in Table 1.
concludes that the craniofacial skeleton remodels with
aging. Many of the observed changes in soft tissue contour Facial Height
and position reflect these skeletal changes. Supported by
data showing that compromised facial muscle function has Two studies found an increased facial height in males.
an impact on facial skeletal contour in a way similar to that Pessa et al. [13] found an increase in midface height that
seen with aging, the authors hypothesize that mechano- did not reach statistical significance. Shaw et al. [19] found
transduction, the process of skeletal remodeling due to an increase in total facial height that did reach statistical
mechanical forces of soft tissue on bone, causes the significance. Barlett et al. [10] found a decrease in height of
changes seen in the craniofacial skeleton with age [18]. the midface, but it was found to be very strongly correlated
with edentulousness.
Methods Facial Width
Strategy for Literature Review Three studies found increased facial width in females.
Barlett et al. [10] found a statistically significant increase in
For this study, MEDLINE, EMBASE, and the Cochrane facial width at all levels measured. Pessa et al. [14] also
Central Register of Controlled Trials were explored for all found an increase in facial width at all levels measured, but
articles discussing bony remodeling of the facial skeleton statistical significance was reached only in the measure-
secondary to aging. The search engines were analyzed from ment of the distance between the lateral orbits. Farkas et al.
their dates of inception (MEDLINE, 1966; EMBASE, 1974; [20] found statistically significant increases in width at the
Cochrane, 2005) through April 2009. The search using the levels of the zygomatic arch and the forehead.
search terms ‘‘aging’’[Mesh] AND ‘‘Face’’[mesh] AND For males, the results were not as consistent. Barlett
‘‘Facial Bones’’[Mesh] produced 142 articles, 7 of which et al. [10] found an increased facial width only at the level
satisfied the inclusion criteria. The search using the search of the frontozygomatic junction. The increase in width at
terms ‘‘Facial Bones/growth and development’’[Mesh] all levels found by Pessa et al. [14] did not reach statistical
AND ‘‘Aging’’[Mesh] produced 204 articles, 3 of which significance.
satisfied the inclusion criteria. All articles of interest were
reviewed to examine their discussion of objective bony Facial Depth
changes in the facial skeleton with age.
Facial depth was analyzed only in the study of Barlett et al.
[10], who found a statistically significant increase in the
Strategy for Manuscript Selection depth (anteroposterior dimension) of the cranial vault,
upper face, and midface in women. A statistically signifi-
The articles included in the study were those that used an cant decrease in distance from the cranial base to the
objective measuring tool to analyze the morphology of the anterior maxilla was found, but it was very strongly cor-
craniofacial skeleton, comparing a younger group with an related with edentulousness.
older group. It was necessary that the older group included
subjects older than 60 years to differentiate the aging Frontal Bone
process from the developmental processes of early and
mid-adulthood. Studies that included dental occlusion as a Both Pessa et al. [13] and Shaw and Kahn [16] found a
variable were not included. Only articles published in decrease in the glabellar angle. The glabellar angle is
English language journals were included. defined by the line that connects the maximum glabellar
The data of the highest significance were those that prominence with the nasofrontal suture compared with the
compared the same subjects over time. Other data of sig- horizontal (nasal-sellar) line. The result from the study of
nificance were those that compared subjects of different Pessa et al. [13] study can be applied only to males because
age groups at the same time. The articles that did not use only males were studied, and the findings did not reach
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3. Table 1 A summary of the main findings from the analyzed studiesa
Study Study design Facial height Facial width Facial depth Frontal bone Nose and pyriform Orbit Maxilla Mandible
(author, year) aperture
Barlett et al. Examination of Males and Females—increased Females only— Females—no Males and females— Males and females— Males and females—
[10] cadaveric females— at all levels; increased cranial changes; males— increased dacryon-to- decreased length no changes in
skulls: 80 decreased males—increased vault, upper, and increased frontozygomatic from cranial base to gonial angle
b
subjects ages height of dacryon-to- midface depth; nasofrontal angle junction distance anterior maxilla
20–45 and 80 anterior lower frontozygomatic Males and
subjects ages midface onlyb junction distance females—
70–91 only decreased distance
from cranial base to
anterior maxillab
Aesth Plast Surg (2010) 34:603–611
Pessa et al. CT scans of 14 Regression of maxilla
[11] males and 14 with age
females in two
age groups
(15–30 and 43–
57)
Pessa et al. CT scans of 20 Pyriform displaces
[21] males ages 16– posteriorly and
23 and 49–64 pyriform aperture
loses vertical
height
Zadoo and CT scans of 6 Demonstrated change
Pessa [12] males ages 18– in the contour of
24 and 6 males the anterior
ages 40–66c maxillary
horizontal
curvilinear form
with increased
anterior projection
of maxilla medially
(especially at the
nasomaxillary
junction)
Pessa [13] Stereolithography Increase in Decrease in Decreased pyriform Decrease in orbital Decreased maxillary
of 6 males ages midface height glabellar angle angle angle (superior to angle
19–24 and 6 (not significant) (not significant) inferior orbital rims
males ages 45– at orbital midpoint)
c
68 (Not significant)
Pessa [14] Sterolithography Increased facial Decreased pyriform Decreased maxillary
of 5 males and width at all levels angle angle
5 females ages (not significant
18–24 and 5 except for distance
males and 5 between lateral
females aged orbits in females)
45-74c
605
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4. Table 1 continued
606
Study Study design Facial height Facial width Facial depth Frontal bone Nose and pyriform Orbit Maxilla Mandible
(author, year) aperture
123
Pessa and Examination of Increased height of
Chen [8] cadaveric superior orbital rim
skulls of 10 medially and inferior
males aged 18– orbital rim laterally
30, 10 males
ages 46–50,
and 10 males
ages 74–80
Levine et al. Review of Orbital rim moves Maxilla moves
[22] Behrents anteriorly anteriorly and
modification of increases in vertical
Bolton length
Cephalometric
Study results
(cephalograms
in males and
females ages
17–83)
Farkas et al. Measurements Males— Females—increased
[20] taken from increased facial width at level of
bony surfaces height zygomatic arch;
of 600 patients increased forehead
ages 16–90 width
Mendelson CT scans of 31 No changes in Decreased maxillary
et al. [15] men and 31 anteroposterior angle
women ages length of orbital floor
21–70 or roof
Shaw and CT scans of 30 Decreased glabellar No changes in Decreased maxillary
Kahn [16] men and 30 angle pyriform angle, angle
women ages but significantly
25–85 increased
pyriform aperture
area
Kahn and CT scans of 30 Males and females—
Shaw [9] men and 30 orbital aperture width
women ages and area increase
25–85 with age; superior
orbital rim becomes
higher medial;
females—inferior
orbital rim moves
inferiorly on the
lateral aspect;
males—inferior
orbital rim moves
inferiorly uniformly
Aesth Plast Surg (2010) 34:603–611

5. Aesth Plast Surg (2010) 34:603–611 607
increased width and
in bigonial width or
Increased mandibular
especially laterally;
statistical significance. The result from the Shaw and Kahn
length; no changes
Change in shape of
mandible; loss of
mandibular body
angle; decreased
madibular body
[16] study was statistically significant.
ramus breadth
ramus height,
height, and
convexity,
Mandible
Nose and Pyriform Aperture
height;
Four of the studies analyzed the pyriform aperture. Two
studies by Pessa et al. [13, 14] found statistically significant
decreases in the pyriform angle, although only the 2001
study can be applied to both males and females. Shaw and
Kahn [16] found no change in the pyriform angle, but did
Maxilla
find a statistically significant increase in the area of the
pyriform aperture. A third study by Pessa et al. [21] in 1999
found that the pyriform aperture displaces posteriorly and
loses height with age. These changes lead to the appear-
ance of a retruded maxilla and an acute nasolabial angle
due to loss of support of the alar base.
Orbit
Orbit
Nose and pyriform
Six of the studies analyzed the orbital region. Barlett et al.
[10] found a statistically significant increase in the width of
aperture
the orbit (measured by the distance of the dacryon to the
frontozygomatic junction). Kahn and Shaw [9] similarly
found a significant increase in the width of the orbit.
Regarding the shape of the orbit, Kahn and Shaw [9]
Frontal bone
found an increase in the size of the orbit, an increase in the
height of the superior orbital rim, and an increase in the
height (inferior movement) of the interior orbital rim lat-
erally (in females) and uniformly (in males). These results
reached statistical significance. Pessa and Chen [8] also
found a significant increase in the height of the superior
Facial depth
orbital rim medially and the inferior orbital rim laterally,
but their study included only males.
With regard to the anteroposterior dimension of the
orbit, Mendelson et al. [15] found no significant changes in
the length of the orbital roof or floor. Levine et al. [22]
found that the entire orbital rim moved anteriorly and that
Facial width
the change was statistically significant.
Pessa [13] found a nonsignificant decrease in the orbital
angle. The orbital angle was defined by the line from the
superior orbital rim midpoint to the inferior orbital rim
All results are significant unless otherwise noted
Facial height
midpoint compared with the horizontal (nasal-sellar) line.
Strongly correlated with edentulousness
Maxilla
Only dentulous patients included
women aged 5–
same patients at
Cephalograms of
CT scans of 20
Eight studies analyzed the maxilla. Pessa et al. [13, 14],
8 men and 8
women ages
men and 20
ages 46–60
Study design
17 and the
Mendelson et al. [15], and Shaw and Kahn [16] found
20–65?
statistically significant decreases in the maxillary angle.
Table 1 continued
The maxillary angle is defined by the line between the
superior-to-inferior maxilla at the level of the articulation
(author, year)
Pessa et al.
Shaw et al.
of the inferior maxillary wing to the alveolar arch and the
horizontal (nasal-sellar) line. Levine et al. [22] concluded
[17]
[19]
Study
from trigonometric analysis that the maxilla moves
b
a
c
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6. 608 Aesth Plast Surg (2010) 34:603–611
anteriorly and simultaneously increases in length. Con-
versely, Pessa et al. [11] found that the maxilla regresses
with age at the level of the pyriform.
Zadoo and Pessa [12] demonstrated a change in the
contour of the anterior maxilla by measuring the antero-
posterior height of the maxilla at eight equidistant points
along the maxilla horizontally. The anterior maxilla
increase in anteroposterior height medially more than lat-
erally demonstrates differential growth in the maxilla with
age.
Mandible
Barlett et al. [10] found no significant changes in the gonial
angle and no indication that the shape of the chin projec-
tion is related to aging. Pessa et al. [17], in their longitu-
dinal study, found a significant decrease in the convexity Fig. 1 a The orbit demonstrating a youthful contour. b The aged
and loss of diminutivity of the mandible, especially in the orbit demonstrating increased height of the medial superior orbital
rim and lateral inferior orbital rim
lateral third, as well as an increase in mandibular height
and width. However, Shaw et al. [18] recently demon-
strated a decreased height of the mandibular body and
rami. In addition, their study showed an increase in the
mandibular angle.
General Appearance of Bony Prominences
Barlett et al. [10] found a subjective coarsening of the bony
prominences with insertions of the muscles of mastication
and a subjective softening of the bony prominences without
these insertions.
Discussion
The results of this review indicate that significant and
consistent changes occur as the craniofacial skeleton ages. Fig. 2 a Lateral view of the youthful skull. b The aged skull
demonstrating a decreased glabellar angle (angle between the sella-
The most consistent findings were decreased midface ver-
nasion line and the line between the glabellar prominence and the
tical height in edentulous patients, a change in contour of nasofrontal suture) and a decreased maxillary angle (angle between
the orbit (see Fig. 1 and Supplemental Digital Content 11), the sella-nasion and the line between the superior and inferior
an increased facial bony width in women, a decreased maxilla) with maxillary retrusion
glabellar angle, a decreased pyriform angle, and a
decreased maxillary angle (see Fig. 2 and Supplemental process of expansion, others such as Shaw and Kahn [16]
Digital Content 22). argued that it is a process of atrophy and volume loss. To
The underlying mechanism of craniofacial bony date, no studies have been published regarding changes in
remodeling was a point of contention among authors. actual craniofacial bone mass with age.
Whereas some authors such as Barlett et al. [10] and Pessa To Levine et al. [22], their analysis of Behrents Atlas of
[13] argued that craniofacial skeletal remodeling is a Growth in the Aging Craniofacial Skeleton indicated that
facial bone growth continues throughout adulthood. They
1
Supplemental Digital Content 1: A video demonstrating the concluded that it is soft tissue descent and volume loss that
changes in the bony orbit with age. Specifically, the orbit grows
leads to the associated changes of aging. Furthermore, they
wider superomedially and inferolaterally.
2 believed that the negative vector eyelid or polar bear
Supplemental Digital Content 2: A video demonstrating the
changes in the profile of the facial skeleton with age. Specifically, appearance seen in some individuals results from a hori-
the glabellar and maxillary angles become more acute. zontal maxillofacial deficiency present throughout life that
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7. Aesth Plast Surg (2010) 34:603–611 609
is unmasked by the soft tissue changes of aging. Levine orthognathic disharmony also demonstrate a decreased
[23] contended that the cohort comparison studies of Pessa nasolabial angle, indicating that bony abnormalities may
[13] and Shaw and Kahn [16] using statistical analyses of play a role as well [13].
three-dimensional images are unsound because they are not In a discussion of Pessa’s work, Lambros [25] pointed
longitudinal (i.e., they did not study any one individual out that although soft tissue repositioning secondary to
over time) [23]. Pessa countered that Levine’s longitudinal bony remodeling clearly occurs, to impute all facial aging
analysis of cephalometric tracings is unsound because it is to bony changes may be inaccurate. Lambros argued that
based on angular measurements, which can be interpreted although the female craniofacial skeleton is shown to
in different ways depending on the point of reference [24]. widen with age, the soft tissue (due to downward dis-
Pessa [14] presented the theory that the maxilla rotates placement) creates the illusion of a narrower face. Because
clockwise in relation to the cranial base. In other words, the the overall gestalt of the female face lengthens and narrows
superior maxilla displaces anteriorly, whereas the inferior with age (instead of widening), Lambros believed that soft
maxilla moves posteriorly. Levine et al. [22] claimed that tissue changes probably outweigh bony changes.
this is not possible because the posterior palate moves
anteriorly with age. For these two processes to occur Mechanotransduction as a Role in Craniofacial Skeletal
simultaneously, the inferior maxilla would collide with the Aging
posterior palate. This would not be possible without an
aerodigestive process also occurring [25]. However, the The functional matrix hypothesis states that ‘‘epigenetic,
aerodigestive process that would have to occur does not extraskeletal factors and processes are the prior, proximate,
necessarily disprove Pessa’s [14] theory of the maxilla’s extrinsic, and primary cause of all adaptive secondary
clockwise rotation. responses of skeletal tissues and organs’’ [26]. This is, in
A study by Zadoo and Pessa [12] demonstrated that the essence, a restatement of ‘‘Wolff’s law,’’ which states that
anterior maxilla changes in contour with age, in addition to long bone changes its external shape and internal archi-
changing position. This study [12] illustrates that the process tecture in response to stresses acting on it. A recent revi-
of differential growth, conventionally thought to be limited to sion of the functional matrix hypothesis stresses the
adolescence and early adulthood, may be present throughout importance of mechanotransduction, defined as the process
life. Therefore, the craniofacial skeleton may remodel in a of intercellular transduction of mechanical information into
way that is reactive and adaptive to its environment. osteoblastic changes [18].
Regardless of the cause, it remains evident that the This is not merely theoretical information because sev-
maintenance of bone volume and contour is necessary to eral studies have demonstrated craniofacial changes as a
preserve soft tissue relationships. This concept is not lim- result of facial muscle and nerve ablation. Sinsel et al. [27]
ited to aging. Bony trauma, congenital bony abnormalities, performed nerve ablation (of buccal branches of the facial
and bone degenerative disease also result in soft tissue nerve) and muscle ablation (of muscles innervated by these
distortion. Pessa’s [13] algorithm of aging considers skel- branches) in rabbits and demonstrated a misdirection of
etal remodeling as one among four components of facial bony growth and change in bony shape. The nasal and
aging (skin aging, subdermal fat loss, skeletal remodeling, maxillary regions were the most affected, with an overall
and fat deposition). According to the algorithm, increased deviation of the snout toward the side managed surgically.
facial muscle tone and soft tissue repositioning are a direct Similarly, Matic et al. [28] performed paralysis of the
and unique result of skeletal remodeling. masseter muscle unilaterally with botulinum toxin in rab-
Pessa et al. mentioned three discrete reasons why facial bits. This did not cause a change in skeletal shape but
aging cannot be uniquely due to soft tissue changes and caused a decrease in overall bone volume (mandibular and
gravity. First, scleral show and downward disposition of zygomatic) on the side managed surgically.
the lower lid, which are significant contributors to the This topic also is of interest and importance in the field
senescent appearance, can be present in young patients, of orthodontics. Proffit et al. [26] demonstrated a correla-
especially in those with craniofacial skeletal abnormalities. tion between maximal occlusive force of the jaw and
Second, there is the concept that facial muscle laxity and ‘‘long-faced’’ individuals. The ‘‘long-faced’’ individuals,
weakness cause a downward displacement of soft tissue. If chosen by subjective and objective findings on cephalo-
this were completely true, why then would facial muscle grams, had a lower maximal occlusive force than patients
paralysis cause softening of the corrugator, nasolabial, of normal facial length. Although this study supports the
periorbital, and labiomandibular creases and improvement idea that muscular forces influence bony remodeling, an
in senescent appearance? Third, a decreased nasolabial important factor to consider is that the patients in the
angle is thought to be secondary to nasal ptosis caused by ‘‘long-faced’’ group had obvious differences in anatomy of
gravity. However, patients with facial clefts and the mandible and maxilla. In effect, these bony differences
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8. 610 Aesth Plast Surg (2010) 34:603–611
could have accounted for the decrease in maximal occlu- decreased muscle strength that occurs primarily with aging.
sive force instead of the latter causing the former. This data In other words, normal facial muscle strength is necessary
cannot determine the causality of the relationship between for the maintenance of the youthful craniofacial skeleton,
muscular force and bone remodeling. and the loss of muscle strength with aging is a primary
More convincing evidence that the musculature is the cause for craniofacial skeletal changes.
cause of bony changes is exemplified in the study of Using this model, the soft tissue changes (repositioning
Moebius syndrome. Patients with Moebius syndrome have and downward displacement), which are the main focus of
congenital facial paralysis. It is believed that the syndrome facial rejuvenation surgery, are a tertiary result of aging.
is neuromuscular in nature and that no primary bone This suggests that there may be more successful anti-aging
abnormality exists. The facial paralysis in Moebius syn- interventions that target the primary (muscular) or sec-
drome usually is bilateral and usually involves cranial ondary (skeletal) changes with aging in addition to the
nerves 6 and 7. In a subset of Moebius patients, cranial tertiary changes that are the current targets of facial reju-
nerve 5 also is involved, with subsequent paralysis of the venation techniques.
muscles of mastication.
Instrum [29] demonstrated craniofacial skeletal changes
on cephalograms of patients with Moebius syndrome. The Conclusions
subset of patients with cranial nerve 5 involvement in
addition to cranial nerves 6 and 7 demonstrated more The literature supports the view that there are consistent
pronounced craniofacial changes than those with only morphologic changes of the craniofacial skeleton with age.
cranial nerve 7 involvement. Specifically, they exhibited an This remodeling includes trends toward increased facial
‘‘extreme pattern of vertical growth, clockwise rotation of bony width in women; contour changes in the orbit, ante-
the mandible, and an anterior open bite.’’ rior maxilla, and mandibular body; and decreases in the
Patients with spinal muscular atrophy and myotonic dimensions of the glabellar, pyriform, and maxillary
dystrophy (syndromes that also cause decreased strength of angles. An overview shows that most of these changes are
the muscles of mastication) also exhibit craniofacial skel- consistent with skeletal atrophy. Many of the observed
etal changes including significant lengthening of the face changes in soft tissue contour and position reflect these
and an anterior flare of the upper incisors. The upper skeletal changes.
incisor flare, which causes an anterior open bite also The authors hypothesize that mechanotransduction, the
present in Moebius syndrome, is thought to be caused by a process of skeletal remodeling due to mechanical forces of
lack of posteriorly directed pressure on the maxilla by the soft tissue on bone, causes the changes seen in the cra-
superior portion of the orbicularis oris [30, 31]. This niofacial skeleton with age [18]. This implies that
demonstrates the concept that muscles not only may cause decreased muscle function results in changes to the facial
a sheer force of pulling on a bone but also may provide a skeletal contour that contribute to the aged appearance. The
retaining force that affects bone remodeling. It should not visible manifestations of facial aging are therefore the
be ignored that the muscles of facial expression insert not result of changes to both the soft tissue envelope and the
only onto the bone but also into the superficial soft tissues. underlying skeleton, which are interrelated and have an
Similar to the effect on bony remodeling, the change in impact on one another. Although based solely on obser-
muscle functionality also may cause changes in the com- vations of existing disease pathology and objective studies
position of soft tissues. at variance with one another, the concept of mechano-
These results clearly demonstrate the importance of transduction is a novel way to view one potential cause of
muscle functionality and the development of the bones on the common facial changes seen with aging. Nevertheless,
which they insert. However, no study has applied the maintenance of the facial skeletal contours through muscle
specific concept of mechanotransduction to facial aging. In exercise and nutrition and restoration of facial skeletal
the juxtaposition of the craniofacial skeletal changes with contours with alloplastic augmentation should be consid-
aging and the cranial skeletal abnormalities seen in neu- ered as measures for rejuvenating the aging face.
romuscular syndromes, it becomes apparent that the two
are quite similar, specifically, an increased facial height
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