Vertical dimension - A dynamic concept based on facial form

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V e r t i c a l d i m e n s i o n : A d y n a m i c c o n c e p t b a s e d on f a c i a l f o r m 
and o r o p h a r y n g e a l f u n c t i o n 
M. R o b e r t M a c k , D D S 
Ft. Lauderdale, Fla. 
Craniofacial vertical dimension is a more accurate measure of facial proportion 
than mere measurement of the mid and lower part of the face. Craniomaxillary 
dimension is skeletally determined, whereas facial height of the lower part of the 
face is partly dependent on the vert ical dimension of occlusion. Alterat ions in the 
vertical dimension of occlusion can dramatically affect the esthet ics of the soft 
facial tissue. The "Golden Proportion" quantitatively defines ideal measured 
relat ionships and encourages a scientific appreciation of beauty. Faces with 
deficiencies in lower facial balance (brachyfacial) often exhibit insufficient height 
of the occlusal plane. The scientific literature has suggested a pliability of skeletal 
muscle allowing for physiologic var iance in vertical facial height. Temporomandib- 
ular joint compliance is demonstrated with elevations in rest ing muscle length. 
Facial balance and location of the occlusal planes are the primary determinants for 
es tabl i sh ing an appropriate vertical dimension of occlusion. (J PROSTHET DENT 
1991;66:478-85.) 
A clear clinical concept of vertical dimension re- 
mains elusive despite frequent discussions in the dental 
literature. 14 Nevertheless, authors agree on the relation- 
ship of normal oropharyngeal function and pleasing 
esthetics to an ideal vertical dimension of occlusion 
(VDO).~ -1~ \ 
The facial VDO is determined by the measurement of the 
distance between two arbitrarily selected points; one on the 
maxillae and another on the mandible. If vertical dimen- 
sion is referred to only as a measure of facial proportion, it 
is a misleading concept in view of the intimate relationship 
of the cranium to the mid and lower part of the face. Es- 
thetic evaluation of a patient should involve the entire 
craniofacial complex, according to Ricketts. 14 The rela- 
tionship of the craniomaxillary segment to the lower part 
of the face is confirmed by using the "Golden Proportion" 
to analyze what is instinctively appreciated as a beautiful, 
well-balanced face. 
Prevailing literature regarding oral reconstruction sug- 
gests a reasonably static lower facial height, limited by the 
clinical rest position of the mandibleJ 5-2° Changes in rest 
position are considered slight and clinically difficult to 
measure with the passage of time. However, the literature 
is replete acknowledging that facial height is neither static 
nor limited by the clinical resting length of the masticatory 
muscles. 2123 An immediate increase in resting facial height 
can be correlated to an elevation in the VDO. 24, 25 An 
interocclusal distance obliterated by an increased VDO is 
evident after a single occlusal contact occurs. Immediate 
change in the resting length of the muscles is under neuro- 
muscular control and consistent with efficient function. 2d 
10/1 /24179 
Prolonged physiologic acceptance to this alteration is ap- 
parent if initial functional adaptation proceeds to struc- 
tural adaptation after approximately 21 days. 27 
Electromyographic (EMG) studies of muscle activity 
also verified physiologic acceptance to increased muscle 
resting length by demonstrating diminished electrical ac- 
tivity as muscle length was expanded beyond clinical 
rest. 2s-3° A point of muscle elongation was finally reached 
confirming minimal integrated EMG activity, and this po- 
sition was referred to as EMG or physiologic rest. It was not 
a dimension of facial height of clinical significance but 
simply a physiologic property of muscle. Beyond this posi- 
tion, reflex muscle contracture occurred as a protective 
mechanism. 26 In measurement of total facial height, EMG 
rest was approximately 5 to 12 mm beyond the VDO, 
whereas clinical rest was 1 to 3 mm beyond the VDO. 31, 32 
The individual differences in these measurements confirm 
the adaptability of the facial mask to sensitive changes in 
the VDO. This was documented with the correction of dra- 
matic facial deficiencies by orthognathic surgery relocating 
the dentoalveolar process to increase facial height. 33, 34 
Sicher is and Behrents 35 have suggested that wear in the 
dentition reducing the VDO was compensated by growth in 
the dentoalveolar complex, maintaining a constant facial 
height. Two restorative dilemmas then become evident: (1) 
the patient with a short face where the dentoalveolar height 
has always been inadequate, 36 and (2) the patient with a 
balanced facial proportion but extreme tooth wear that is 
inadequately compensated. For these patients, examina- 
tion of facial form and proportional balance is critical for 
evaluating vertical dimension. Analysis of mounted casts 
for occlusal plane position without the benefit of a facial 
tissue matrix denies the patient the potential for "holistic" 
esthetics. 
4 7 8 OCTOBER 1991 VOLUME 66 NUMBER 4 
VERTICAL DIMENSION: DYNAMIC CONCEPT 
Occlusal plane position is ultimately the determining 
factor in restoring necessary facial height. The location of 
maxillary and mandibular occlusal planes is well defined in 
the literature. 3739 When the functional and esthetic re- 
quirements of the occlusal plane and craniofacial balance 
are restored, the vertical dimension becomes a dynamic 
concept providing the dentist the opportunity of improv- 
ing facial beauty beyond mere restoration of the dentition. 
N E U R O M U S C U L A R I N F L U E N C E S ON 
F A C I A L H E I G H T 
Evaluation of the vertical dimension by use of the 
dynamics of facial balance implies an understanding of the 
effect of neuromuscular determinants on facial height. 
Tonic muscle resting length is considered the limiting fac- 
tor for increases in the VDO. 15 Detailed investigations of 
skeletal muscle physiology and its application to the gnath- 
ostomatic system revealed the Pliability of muscle l eng thy 
This adaptive capacity of the muscle cell or sarcomere to 
modification of its resting length provides some latitude for 
the dentist in restoring the teeth of patients at an increased 
vertical facial height. 
Facial height, or vertical dimension, consists of two 
components: (1) the more objective VDO, which is the 
shortest measure of facial height involving centric occlu- 
sion contacts; and (2) a more subjective measure of facial 
height termed rest position without tooth contact. 4° Neu- 
romuscular posturing of the mandible establishes this 
slightly greater measure of facial proportion. Muscular ac- 
tivity further divides the rest position into two compo- 
nents, clinical and EMG rest. If the total facial height is 
considered beyond the VDO, the clinical rest position is less 
add only 1 to 3 mm greater than the VDO. This interoc- 
clusal distance varies as it is controlled by tonic muscle ac- 
tivity. 22 Airway, posture, and tension can influence this 
position, 4143 but all normal functional movements of the 
mandible originate from clinical rest. 
AS facial height increases, integrated EMG masticatory 
muscle activity diminishes to a point of minimal energy. 
This is the elastic limit of the sarcomeres and their invest- 
ing connective tissue sheaths; thus, beyond this point mus- 
cle energy increases to protect against possible damage. 
The position of greatest facial height is referred to as an 
EMG or physiologic rest. Although minimal integrated 
EMG activity is apparent, it is a physiologic phenomena of 
individual muscles and not a functional position under 
fusimotor control. Esthetics are also compromised at this 
facial height; notably there is a lack of lip competence and 
an excessive proportion of the lower part of the face. Van 
Sickles et al . 32 recorded an interocclusal distance of 5 to 12 
mm for EMG rest. 
The intimate relationship of clinical rest position to the 
VDO has ledto beliefs that the VDO must be extrapolated 
from observed clinical rest minus an adequate measure- 
ment for interocclusal distance. 
Hellsing 25 confirmed that clinical rest position varied 
with changes in the VDO. He increased contact vertical di- 
mension with splints and maintained a preexisting interoc- 
clusal distance. Initially the immediate adaptation of rest 
position was by neuromuscular response. 26 Physiologic ac- 
ceptability of increases in resting muscle length are evi- 
denced by the structural reordering occurring in the con- 
tractile protein elements of the sarcomeres. 27 After 21 days 
this structural change becomes apparent, preserving the 
efficiency of the neuromuscular system. 44 
This physiologic behavior of muscles is critical in restor- 
ative treatment of patients with inadequate lower facial 
height. The suppleness of the mandibular sling muscles 
short of their elastic limit allows the dentist an expanded 
concept of vertical dimension, embracing facial form, the 
location of the occlusal plane, and neuromuscular determi- 
nants. 
F A C I A L P R O P O R T I O N A N D SOFT 
T I S S U E FORM 
Familiarity with the Golden Proportion is necessary for 
the dentist in using facial proportion to evaluate vertical 
dimension. 45 This term was first described by Phidias, the 
Greek sculptor, and refers to an ordered relationship of 
spacially related parts in nature that are instinctively ap- 
preciated as beautiful. This proportional harmony or 
rhythmic relationship of segments was described mathe- 
matically by Fabonacci in the ratio of 1.618 to 1. When a 
face is pleasing to the eye, it commonly conforms to the Phi 
(¢) relationship. 
Ricketts 14 presented this facial analysis in all planes in- 
cluding cephalometric skeletal evaluation. Shoemaker 46 
provided a clinical tool, the golden link caliper (GLC), to 
accurately measure this proportion. The GLC is especially 
useful for clinically relating tooth size to existing anatomic 
form. Although documented by measurement, mathemat- 
ics, or geometric theorem, the Golden Proportion is more 
evident in an innate sense of beauty. 
Figs. 1 through 3 demonstrate this proportionality in the 
frontal plane, with vertical (Figs. 1 and 2) and horizontal 
(Fig. 3) elements of balance. Measurements of facial 
esthetics help the dentist to appreciate the impact of 
diminished lower facial height. By evaluation of the pa- 
tient's features both in repose and in the vertical dimension 
of occlusion, a suitable anatomic balance can be compared 
with facial asymmetry caused by an overclosure of the 
lower part of the face (Figs. 4 through 7). 
Soft tissue measurements from the forehead (trichion), 
to the alar rim (AL) are related by anatomic determinants, 
but measurement of the lower part of the face from the alar 
rim to soft tissue menton (ME) is dependent on the VDO 
and related to clinical rest (Fig. 1). Deficiencies in the VDO 
can result from collapse of the occlusion or uncompensated 
attrition (Figs. 8 and 9) and hypoplasia of the mandible or 
a deficient dentoalveolar mass (Fig. 4). 
All ¢ relationships in the vertical plane involve the 
dimension of the lower part of the face from the alar rim 
THE JOURNAL OF PROSTHETIC DENTISTRY 4 7 9 
MACK 
~ ~ i ! ¸ , 
il ........ 
.0 
1.0 
1.0 
Fig. 1. Related harmony of balance in entire craniofacial 
mask. Trichion (TRI), intersection of vertical and horizon- 
tal planes of skull; lateral canthus of eye (LC); superior 
border of alar curve of nose (AL); stomion (ST), intersec- 
tion of lips; soft tissue menton (ME), lowest point on chin. 
1.618 
l.O 
1.0[ ~ 1.6181 
Fig. 2. Interrelationship of balance point between mid 
and lower region of face. Change in VDO can dramatically 
affect this harmony if present, or improve it, if deficient. 
of the nose to soft tissue menton (AL to ME) (Figs. 1 and 
2). Harmony from AL to ME to total facial measurement, 
TRI to ME, is critical for proportional facial balance (Fig. 
1). A decrease from AL to ME affects lip form, resulting in 
wider and thinner appearing lips (Figs. 10 and 11) because 
j 
Fig. 3. Lateral border of nose (LN); commissure of mouth 
(CH); lateral canthus of eye (LC); temporal soft tissue at 
level of eyebrow (TS). 
the lips are compressed. An outward turning of the lower 
lip is also evident, increasing the depth of the labiomental 
sulcus 47 (Fig. 10). Facial width is also affected by a dimin- 
ished facial measurement from AL to ME, altering the lat- 
eral configuration of the masseter muscle. The insertion of 
the mandibular sling muscles approaches their origin, 
causing fuller muscle bellies (Figs. 4 and 5) appearing as 
muscular hypertrophy. 
Horizontal evaluation of a well-proportioned face reveals 
the lateral border of the nose to be "1" and the width of the 
mouth (CH to CH) is 1.618 (¢). LC to LC measures ~2 and 
the temporal soft tissue at the level of the eyebrow is ¢3 
(Fig. 3). Because horizontal measurements of CH to CH 
and cheek width at the belly of the masseter muscles are 
sensitive to variation in vertical measurement from AL to 
ME, any subtle change in vertical facial height is reflected 
in horizontal balance and esthetics. 
Lip form is also affected by the radius of the anterior arch 
including the facial position of the individual teeth. This 
influence and the VDO are evaluated in considering lip 
esthetics 4s (Figs. 8 and 9). 
FACIAL FORM AND VERTICAL 
DIMENSION DISCREPANCIES 
Facial form is classified into three basic types. 3s This 
classification relates the vertical component of the face 
(nasion to soft tissue menton) to the horizontal component 
480 OCTOBER 1991 VOLUME 66 NUMBER 4 
VERTICAL DIMENSION: DYNAMIC CONCEPT 
Fig. 4. Centric occlusion with full posterior interdigita- 
tion. 
Fig. 6. Centric occlusion. 
Fig. 5. Repose illustrating lips in light, unstrained con- 
tact, face relaxed. 
Fig. 7. Repose. 
or bizygomatic width. The mesofacial form is a balanced 
proportion, characterized by a harmonious relationship of 
the vertical and horizontal facial planes. Further, charac- 
teristics of the mesofacial type include an ideal occlusal 
plane for lip support and filling of the smile space with the 
maxillary teeth described by Tjan and Miller 49 and 
Hulsey. 5° There is a minimal display of gingival tissues in 
the full smile, and the vertical dimension is pleasing to the 
eye. 
The dolichofacial type is characterized by an excessive 
vertical dimension relative to the horizontal dimension of 
the face. 51 The dolichofacial patient exhibits excessive 
dentoalveolar development with excessive height of the 
occlusal plane. When smiling, this patient displays consid- 
erable attached gingiva and in repose the maxillary ante- 
rior teeth are usually visible, extending beyond the upper 
lip. When this facial type is evaluated, either cephalomet- 
rically or clinically, excessive facial vertical dimension is 
readily apparent. 
Conversely, the brachyfacial patient is characterized by 
a deficient vertical dimension of the f ace , 36 m o r e apparent 
in the lower part of the face. In this inadequate dentoalve- 
olar complex, the occlusal planes are deficient in height 
with unsuitable lip support and inadequate filling of the 
"smile frame." 
Only patients exhibiting short facial tendencies require 
consideration of increased facial height. Dramatic skeletal 
imbalances in craniofacial dimension may require surgical 
correction to reestablish facial proportion. When skeletal 
relationships are not radically disproportionate and are 
closer to mesofacial dimension, restoring the occlusal plane 
can have a noticeable effect on the soft tissue. 47, 4s Because 
patients with soft tissue characteristics of a diminished 
lower part of the face usually demonstrate deficiencies in 
occlusal plane height, restoring the occlusal planes within 
physiologic limits improves the esthetics. 
The initial focus of judging vertical dimension is, there- 
fore,facial form. An improved proportion of a short face in 
the most relaxed position of lip competence (for example, 
repose) becomes the primary criteria for elevating vertical 
dimension (Figs. 4 through 7). In the patient's normal en- 
vironment, this same facial evaluation forms the layman's 
THE JOURNAL OF PROSTHETIC DENTISTRY 4 8 1 
MACK 
Fig. 8. Example of uncompensated attrition in patient 
with brachyfacial tendencies and poor vermillion border 
outline form. 
Fig. 10. Centric occlusion. 
Fig. 9. Same patient as in Fig. 8 with maxillary occlusal 
plane restored to physiologic position with improved lip 
form, smile, and facial proportion. 
impression of beauty. Mounted casts and occlusal relation- 
ships cannot always convey this critical improvement in 
facial form. The patient's perception of vertical dimension 
relates to beauty, whereas, the dentist with mounted casts 
has a tendency to view vertical dimension as an occlusal 
plane on the articulator without the aid of a face. 
Once incisor length has been established using esthetics 
and phonetics, knowledge of the angle of divergence of the 
maxillary occlusal plane from that of the palatal plane with 
dimorphic variations related to the patient's facial form 
and sex makes it a simple matter to establish the position 
of the posterior maxillary plane of occlusion. 35, 3s, 52 
O C C L U S A L P L A N E R E Q U I R E M E N T S 
An occlusal plane position is key to the restoration of in- 
adequate facial height. The constraints of physiologic and 
Fig. 11. Repose. 
esthetic occlusal planes Precede neuromuscular or tem- 
poromandibular joint (TMJ) limitations. 53 
A pleasing maxillary plane has a dramatic effect on the 
perception of a beautiful smile (Figs. 8 and 9). In a full 
pleasant smile, the incisal edge of the maxillary incisors 
parallels and just contacts the inner curvature of the lower 
lip. The entire maxillary incisor is exposed without dis- 
playing gingival tissues. Although this observation accu- 
rately establishes the ideal length of the maxillary anterior 
teeth, a display of excessive gingival tissue could result 
from an altered passive eruption despite a suitable occlusal 
plane. This differential diagnosis is made possible by 
relating the osseous crest to the upper lip in the full smile 
position. 
Esthetic evaluation for an ideal position of the dentog- 
ingival complex involves the upper and lower lips in a full 
smile and is appropriately termed the smile frame. Caution 
must be exercised during this analysis, because some 
patients have a restricted smile frame. This is attributed to 
4 8 2 OCTOBER 1991 VOLUME 66 NUMBER 4 
V E R T I C A L D I M E N S I O N : D Y N A M I C C O N C E P T 
PLANE 8°,~<, 
OCCLUSAL 
PLANE 8°4 
FRANKFORT 
HORIZONTAL 9004 
Fig. 12. Boltonstandardlateralcephalometric, young adult composite demonstrating (1) 
ideal lip-incisor relationship, (2) occlusal and palatal plane relationship, and (3) occlusal 
and palatal plane relationship to Frankfort horizontal plane. 
a guarded smile from compromised esthetics or a limited 
smile window related to a diminished vertical facial height. 
Initial correction of the VDO, esthetics, or gingival defi- 
ciencies is required for an accurate assessment of the smile 
frame. 
An acceptable maxillary incisor length is confirmed by 
evaluation of the length necessary for upper lip fullness and 
the most ideal vermillion border form. In repose the max- 
illary anterior teeth should be as long or slightly longer than 
the upper lip with the lips just separated 54 (Fig. 12). The 
importance of the relationship with the lip form and the 
position of the incisor teeth has been repeatedly 
emphasized. 6 Phonetics is also important in determining 
the adequate maxillary incisor position. The "S" sound, or 
closest speaking space, and the "F" sound are closely eval- 
uated for articulation correctness. 
In the adult maD with mesofacial or brachyfacial pro- 
portions, the vertical facial development results in an oc- 
clusal plane that is nearly parallel to the palate and 
approximately eight degrees divergent from the Frankfurt 
horizontal plane (Fig. 12). The vertical facial development 
in the adult woman with the same facial proportions results 
in an occlusal plane with a greater anterior angulation be- 
cause of limited growth of the posterior part of the face. 
In the mandible, lipform is also dependent on adequate 
dentoalveolar height in the mandible, and the plane of oc- 
clusion should be located at or just below the commissure 
of the mouth. Posterior orientation is the superior third of 
the retromolar pad. This occlusal plane height is limited by 
its relationship with the lateral border of the tongue at rest. 
The lower occlusal plane should not restrict the tongue in 
manipulating the bolus of food during mastication, and the 
tongue should be allowed free access to the vestibule to 
sustain the bolus of food on the occlusal table. 
T H E D I A G N O S T I C R E S T O R A T I O N 
An increase in the vertical dimension of the face through 
an elevation in the VDO necessitates longitudinal study. 
Inferior repositioning of the mandible can have a notice- 
able effect on the anterior horizontal overlap relationship 
in a high Frankfort mandibular plane angle (FMA) class II 
patient and can lengthen the resting length of the sling 
muscles and stabilizers of the mandible while changing the 
angulation between the origin and insertion of these mus- 
cles. 
The location of the occlusal plane should be evaluated 
esthetically, functionally, and cephalometrically. Long- 
term stability and comfort of occlusion is an indication of 
condylar stability and physiologic muscle balance. TMJ 
articulation should be closely monitored. Evaluation of 
these terms of changes in patient acceptance and physio- 
logic response is essential (Fig. 13). This is usually accom- 
plished with an accurate and stable provisional restoration, 
which is more appropriately termed a diagnostic restora- 
tion because of the information conveyed. 
The final restoration evolves from the design of this di- 
agnostic prosthesis. Accuracy and detail of the provisional 
T H E J O U R N A L OF P R O S T H E T I C D E N T I S T R Y 4 8 3 
M A C K 
FACIAL PROPORTION AND FORM 
I 
VERTICAL DIMENSION OF LOWER FACE 
I 
COMBINED VERTICAL HEIGHT OF 
DENTO-ALVEOLAR COMPLEX 
I 
OCCLUSAL PLANE 
SPEECH MASTICATORY SMILE COMFORTABLE 
(CLOSEST SPEAKING FUNCTION ESTHETICS NEURO-MUSCULATURE 
SPACE) 
Fig. 13. Interrelationship of factors involved in change of vertical dimension that must 
be closely evaluated by use of meticulously made diagnostic restoration. 
restoration cannot be overemphasized. Models of this 
prosthesis mounted precisely in maximum intercuspation 
guide the dental laboratory technician. Information not 
present on mounted die casts, such as the occlusal plane, 
midline, tooth morphology, and incisal edge location, usu- 
ally can be prescribed. 
S U M M A R Y 
The VDO is commonly related to rest position, and 
maintenance of a constant interocclusal distance by mus- 
cle force is believed to control vertical facial height. In the 
dentate patient, compensating dentoalveolar eruption is 
believed to maintain the balance between the VDO and 
clinical rest. In contrast to this hypothesis of muscle force 
controlling interocclusal distance and a constant clinical 
rest position, Hellsing 25 and Carlsson et al. 24 demonstrated 
neuromuscular response to increases in the VDO by main- 
tenance of a preexisting interocclusal distance, thus ex- 
panding resting facial height. EMG studies have demon- 
strated interocclusal distances of 1 to 3 mm for clinical and 
5 to 12 mm for physiologic rest. From these measurements, 
scientific literature, and clinical success of elevated adult 
facial height, there is a range of resting muscle length that 
is physiologically acceptable. 
Without arbitrarily limiting vertical dimension byneu- 
romuscular determinants, a more dynamic assessment is 
possible by use of improved esthetics of the soft tissue of 
the face. Patients with slight imbalances tending toward 
short facial characteristics will demonstrate dramatically 
improved lip form, cheek form, and proportionally bal- 
anced lower to midfacial components when allowing the 
mandible to posture in a completely unstrained position 
with a pleasing lip form. These patients exhibit a deficiency 
in dentoalveolar height and occlusal plane position both 
cephalometrically and clinically. Esthetics of the facial 
mask can be improved by increasing the VDO but the re- 
sult is dependent on the limitations of occlusal plane height 
modification. 
C O N C L U S I O N S 
1. Proposed alteration of the existing VDO should be 
preceded by a stable, diagnostic restoration to evaluate 
adaptive muscle response. Muscle accommodation can 
then progress from a functional to a structural response al- 
lowing speech, masticatory function, and esthetics to be 
evaluated. 
2. Improvements in facial proportion and lip form, an 
original prognosticator in diagnosis, are carefully scruti- 
nized so that final restorative procedures at the altered 
VDO can be provided that are biologically compatible with 
the existing facial matrix. 
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