Arnett-Facial Keys To Orthodontic Diagnosis II

 

A m er i ca cann J our na nall of of O R T H O D O N T I C S and D E N T O F C I L O R T H O P E D I C S Founded in 1915

Vo lu me 103 N u m b e r

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May 1993

Co p y r ig h t 9 1 9 9 3 b y th e Am e r ic a n As s o c ia tio n o f Or th o d o n tis ts

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F aci al k eys to to or thod hodoontic diagn di agn osis and tr tr eat atme ment nt p l an an n i n g pa r t H G . W i l lil i a m A r n e t t, t, D D S , ~ a n d R o b e r t T . B e r g m a n , D D S , M S b

S a n ta Ba r b a r a , Ca lif.

T h i s i s P a r t I I o f a t w o - p a r t a r t ic ic l e . P a r t I w a s p u b l i s h e d i n t h e A M E RI RIC A N J O U R N AL AL OF ORTHODO NTI NTICS CS AND DENTOFACIAL ORTHOPED ICS, Vo I. 1 0 3 , N o . 4 . P a r t I d i s c u s s e d t h e p r o b l e m o f a c c u r a t e o r t h o d o n t i c d i a g n o s i s . P a r t I1 I1 d i s c u s s e s t h e s o l u t i o n t o t h e o r t h o d o n t i c d i a g n o s t i c p r o b l e m . A M J O R T HO HO D DENTOFAC DENT OFAC ORTHOP 1993 ; 103 : 395 -411 . ) I. F r o n t a l a n d p r o f i l e f a c i a l e x a m i n a t i o n : the 19 facial traits included in the facial examination are listed

Table

N in et ee n

f a c i a l t r a it it s w e r e s e l e c t e d f o r t h i s

e x a m i n a t i o n ( T a b l e I ). ). T w o v i e w s o f t h e p a t ie ie n t a r e used for identification of problem s in three planes of space: I. Frontal A. B.

Relaxed lip Functional analysis 1 . C l o s e d li li p 2. Smile

II. Profile A.

Relaxed lip

FRONTAL VIEW

Natural head posture, centric relation, and relaxed lip posture are used to accura tely assess the frontal view.

Outline form a nd symmetry

Fig. 1

General outline form and asymmetries are noted.' T h e w i d e s t d i m e n s i o n o f t h e fa fa c e i s t h e z y g o m a t i c w i d t h

'Private Practic e, Orthognathic Orthognathic Surgery ; lecture lecturer, r, orthognathic surgery at Unive r sity of C a lif or nia a t Los A nge le s a nd Lom a Linda U nive r sity; c linic a l ininstruc str uc tor tor , O r thogna thic S ur ge r y a t U nive r sity of C a lif or nia a t Los A ng e le s a nd V a lle lle y Me dic a l C e nte r ; a tte nding sta f f a t S t. F r a nc is llos pita l a nd C otta ge Hospital, Santa Barbara. bln private orth odon tic practice. practice. C opyr ight 9 1993 by the A me r ic a n A ssoc ia tion of O r thodontists. 0 8 8 9 - 5 4 0 6 / 9 3 / S l . 0 0 + 0 . 1 0 8111428 8

1. Frontal view A. Outline form B. Facial level C. Midline alignments D. Faci al one-thirds E. Lower one-third one-third evaluation I. Upper and lower lower lip lengths lengths 2. Incisor to relaxed upper lip 3. Interlabial gap 4. Closed lip lip position position 5. Smile-lip level II. Profile view A. Profile angle B. Nasolabial angle C. Maxillary sulcus contour D. Mandibular sulcus contour E. Orbital rim F. Cheekbone contour G. Na sal base-lip contour H. Nasal projection I. Throat length length J. Subnasale-pogonion ine

( F i g . 1 ) . T h e b i g o n i a l w i d t h is is a p p r o x i m a t e l y 3 0 less than the bizy gom atie dim ension. Farkas '2 has established normal values for height and width. Tile height to width proportion is 1.3:1 for females and 1.35:1 for 95

 

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Fig. 1. widths: Facial height: Hairline to soft tissue e ).. Facial Zygo ma tic arch(H)ZA) to zygo mamenton tic arch ( M (ZA),. G o n i o n ( G o ) to g o n i o n (Go ).

m a l e s . A n a l t e r n a t iv iv e t o m e a s u r i n g h e i g h t a n d w i dt dt iJ iJ i s to artistically describe the face. Faces are wide or narrow, short or long, round or oval, square or rectangular. The important question when assessing these dim e n s i o n s i s: s : W i l l o rt r t h o d o n t i c a n d / o r s u r g i c a l c a re re n e c essary for bite correction correct or accentuate existing h e i g h t a n d w i d t h i m b a l a n c e ? A n e x a m p l e o f o r th th o d o n t i c c o r r e c t i o n o f h e i g h t - w i d t h i m b a l a n c e i s th th e u s e o f b i te te open ing me chanics to lengthen the face during bite corr e c t i o ~ A n e x a m p l e o f s u rg rg i c a l c o rr r r e c ti ti o n i s m a x i l l a r y impaction to shorten the long face. The extremes of disproportion are short and wide or long and narrow. Short, square facial outlines are indicative of deep bite Class II malocclusion, vertical m a x i l l a r y d e f i c i e n c y , a n d i n s o m e c a s e s , m a s s e t e r ic ic hyperplasia. Long, narrow faces are associated with vertical maxillary excess or mand ibular protrusion with dental interferences leading to open bite. The bizygomatic dimension is often deficient (cheekbone deficiency) in combination with maxillary retrusion. The bigonial dimension may be deficient in combination with mandibular retrusion. Height and width disproportion is corrected in two ways:

Fig. 2. Pupil plane (P P ) is horizo ntal line line drawn through pupil pupils. s. This line is usua lly par allel to to the horizon an d is referred referred to a s frontal postural horizontal. Upper dental arch (U D A ) level is a line forme d through through th e left and right ma xillary xillarycc a n i n e i p s. s. L o w e r dental arch (LD A ) level is a line formed through the left and right mand ibular canin e tips. tips. Chin-jaw line (CJL) is assessed b y a l i n e d ra w n o n th e u n d e r s u rfa rfa c e o f th e c h i n a t ma x i m u m iissue contact. All four lines should be pa rallel to ea ch ether.

Examples of the latter are chin lengthening to increase facial height (H to Me'), cheekbone augmentation to increase the bizygomatic width (Zy to Zy), or augmentation of the mandibular angles to increase the bigonial dimension (Go' to Go'). Buccal lipectomies

1. M a x i l l a r y o r m a n d i b u l a r s u r g e r y i s u s e d s i m u l -

ca ar ena sh.e l p r e d u c e e x c e s s i v e w i d t h i n t h e s u b m a l a r c h e e k As a general rule, the maxilla should rarely be m o v e d u p a n d b a c k . T h i s m o v e m e n t d e c re r e a s e s l ip ip s u p port, increases the nasolabial folds, decreases incisor exposu re, and can ma ke the facial outline appear short and wide. These changes give the appearance of prem a t u r e f a c i al al a g i n g . The most common to least common sites of facial a s y m m e t r y a r e c h in i n , m a n d i b u l a r a n g l e s, s, a n d c h e e k ~ bones. The maxilla is rarely in skeletal asymmetry. Asymmetries can occur with any growth abnormality b u t a r e s t r o n g l y a s s o c i a t e d w i t h u n i la la t e ra ra l c o n d y l a r h y perplasia. Correction of asymmetries are accomplished with

taneously to correct the bite and to lengthen or shorten the facial height. '. Augmentation or reduction of the facial height or w idth.

( 1 ) c a n t c o r r e c t i o n o r m i d l i n e m o v e m e n t o f th th e m a x i l l a and mandible simultaneous with occlusal correction or ( 2 ) a u g m e n t a t i o n d r r e d u c t i o n o f th th e s k e l e t a l s u r fa fa c e s . E x a m p l e s o f t h e l at a t t e r in in c l u d e u n i l a t er er a l c h e e k b o n e ,

 

American Journal o f Orthodontics and Dentofacial Orthopedics Volume 103 No 5

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Fig. 3. Constructed Constructed horiz horizontal ontal reference ine is is formed by draw ing line through pupil ar ea para llel to floor. This line is used wh en the pupil plane is is not parallel to the floor eyes are not level) when the head is in frontal postural horizontal.

angle, or body augmentation. A common asymmetry correction is chin shifting to the right or left to center the chin on the facial midline.

Fa cial leve l Fig. 2) T o e x a m i n e f a c i a l l e ve ve l s a r e l i a b l e h o r i z o n t a l l a n d m a r k line is necessary. With the patient in natural head

posture, 3 the pu pils are assessed fo r level with the ho rizon. If the pupils are level, they are used as the horizontal reference line and adjacent structures are meas u r e d r e l a t i v e to to t h is is l i n e ( F i g . 2 ) . S t r u c t u r es es c o m p a r e d with the pupil line are (1) upper canine level, (2) lower canine level, and (3) chin and jaw level. Mandibular deviations commonly have upper and lower occlusal cants with chin and jaw line canting associated. Deviations from level should be noted and correction integrated into the overall bite treatment plan. If bimaxillary surgery is contem plated, occlusal cant is corrected routinely at surgery. If one jaw surgery is contemplated, the occlusal cant can be neglected u n l e s s i t i s e st s t h e t i c a ll ll y p r o b l e m a t i c . W h e n p r o b l e m a t i c , either orthodontic tooth movement or bimaxillary surgery must be used to correct the cant. I f t h e p u p i l s , i n n a t u ra ra l h e a d p o s t u r e , a r e n o t l e v e l t o th th e h o r i z o n , a c o n s t r u c t e d f r o n t a l h o r iz iz o n t a l r e f e r e n c e line is used (Fig. 3). This line is visualized as follows: I. Frontal natural head posture.

F i g . 4. Im portant midline structures structures ar e assessed. Nasal bridge ( N B ) , nasal tip ( N T ) , filtrurrt ( F ) , upper incisor midline ( U I M ) , lower incisor incisor m idline ( L I M ) , a n d c h i n m i d l in in e p o i n t ( M e ) should

be on a line that is perpe ndicular to the frontal postural horizontal. Fil zontal. Filtrum trum is usua lly the leas t asymmetric of the se points and is there fore genera lly used a s a starting starting p oint for midline structure assessment. All midline points may not line up. The denta l midli midlines nes and chin should be place d to integrate integrate with other midlines most importantly the fil filtrum trum center).

2. Horizontal line parallel to the horizon through the pupil area. 3 . A s s e s s o t h e r s t r u c t u r e s re l a t i v e t o t h i s l i n e (Fig. 3).

M i d li n e a l ig n m e n t s

F ig ig . 4 )

Midlines are assessed with uppermost condyle pos i t i o n a n d f i rs t t o o t h c o n t a c t . If o c c l u s a i s l i d e s a l t e r joint position, no reliable midline assessment can be made. The relative positions of soft tissue landmarks ( n a s a l b r i d g e , n a s a l t i p , fi l t r u m , c h i n p o i n t ) a n d d e n t a l midline landmark s (upper incisor midline, lower incisor midline) are noted. Needed changes are incorporated into the surgical/orthod ontic treatment plan to position t h e s e s t r u c t u re re s o n t h e v e r t i c a l m i d l i n e o f t h e f a c e . F i l t r u m i s u s u a l l y a r e l ia ia b l e m i d l i n e s t r u c t u r e a n d c a n be used as the basis for midline asse ssment m ost often. When the pupils are level in natural head posture, a v e rt i c a l l i n e t h r o u g h f i l t r u m m i d p o i n t i s u s e d t o a s s e s s ..other hard and soft tissue midline structures (Fig. 4). I f th th e p u p i l s a r e n o t l e v e l , a v e r t i c a l l i n e t h ro u g h f i l t r u m midpoint, perpendicular to postural horizontal, is used to assess midline structures (Fig. 5). With the evalu-

 

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merican Journal of Orthodon Orthodontics tics and Dentofacial Orthopedics Orthopedics May 1993

1/3 Constructed Posaa alHorizontal alHorizontal

Middle 1/3

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Fig. 5. When pupils are not level, constructed horizontal refe r e n c e l in in e F i g . 3 ) i s u s e d . A p e r p e n d i c u l a r t o th th e c o n s t r u c t e d horizontal line through filtrum is used to assess other midline structures.

a t i o n o f s k e l e t a l o r d e n t a l m i d l i n e s , e t i o l o g i c f a c t o rs rs are assigned. Den tal midline shifts are the result of multip le dental factors including: 1. Spaces 2. To oth rotations 3. M issing teeth 4 . B u c c a l l y o r li li n g u a l l y p o s i ti ti o n e d t e e t h 5. Crowns or fillings which change tooth mass 6. Congenital tooth mass difference from left to right

Fig. 6. Face is .divided into thirds by draw ing lines through h a i r l i n e (H), m i d b r o w ( M b ) , s u b n a s a l e (Sn), a n d s o f t t is is s u e m e n ton (Me ).

o d o n t i c a l l y c o r r e c t t h e b i t e w h e n t h e e t i o lo lo g i c f a c t o r i s s k e l e t a l c a n p r o d u c e b u c c a l p l a t e v i o l a ti ti o n a n d g i n g i v a l recession.4 ~ Facial one thirds

Fig. 6)

T h e f a c e d i v i d e s v e r t i c a l l y i n t o t h ir ir d s f r o m h a i r li li n e to midbrow, midbrow to subnasale, and subnasale to soft tissue menton (Fig. 6). The thirds are within a

Model examination is used to distinguish dental midline shift etiologic factors (spaces, rotations). Dental midline shifts are treated orthodontically. Asymm e t r i c p r e m o l a r e x t r a c t i o n s m a y b e n e c e s s a r y t o a li li g n dental and skeletal midlines. Skeletal midline shifts are not corrected orthodontically, surgery is employed. W h e n t h e d e n t a l a n d s k e l e t a l m i d l i n e s d e v i a t e t o g e t h e r, r, the etiologic factor is usually skeletal, and surgery is u s e d t o c o r r e c t ( i. i. e . , c h i n a n d l o w e r i n c i s o r m i d l i n e a r e 3 mm to the left). Stability, periodontal health, and

ra abnl eg,e aonfd 5 t5h et o u6p5p emr mt h, i rvde ritsi c farlel yq .u eTn ht ley hlaoiwr l irnaen gis ise .v aI nr i-c r e a s e d l o w e r o n e - th th i r d h e i g h t i s f r e q u e n t l y f o u n d w i t h vertical maxillary excess and Class III malocclusions (lack of interdigitation opens vertical height). Decreased lower one-third height is associated with vertical maxillary deficiency and mandibular retrusion d e e p b i t e s. s . P r o d u c t i o n o f c o r r e c t p r o p o r t io io n i n f l u e n c e s the choice of surgical procedure used to correct the occlusion (i.e., max illary impaction to correct Class II m a l o c c l u s i o n a s s o c i a t e d w i t h l o n g l o w e r o n e - t h i rd rd rather than mandibular advancement). The equality of the middle and the lower thirds should not be used as the determining factor in facial height changes. The appearan ce of the landmarks (incisor exposu re, inter-

f a c ia ia l b a l a n c e a r e o p t i m i z e d w h e n d e n t a l s h i f t s th th e r e sult of skeletal deviation are treated with surgical, ra therthan orthodontic, tooth movement. Attempts to orth-

labial gap) within the lower third are more important i n a s se se s s i n g b a l a n c e t h a n a r e t h e e q u a l i t y o f t h e m i d d l e and the lower thirds.

 

American Journal of o f Orthod Orthodontics ontics and Dentofitcial Orthopedics Vohtme 103 No. 5

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Upper L ip Length

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F i g . 7 . With lips relaxed lower third third is subdivided subdivided by drawing lilines nes thro ugh subnasale (S n), upp er lip infer inferior ior (ULI), lowe r lip lip s u p e ri o r (LLS ), and soft tissue menton ( M e ) . T h e u p p e r l i p i s half the length of th e lower. Low er one-third e valua tion

Figs. 7 through 9)

T h i s a r e a o f fa fa c i a l a n a l y s i s i s e x t r e m e l y i m p o r t a n t in surgical orthodontic diagnosis and treatment plann i n g . T h e i m p o r t a n c e o f r e l a x e d l i p p o s i t i o n f o r th th e s e mea suremen ts cannot be overem phasized. Upper and lower lip lengths (Fig. 7). The lips are m easured independe ntly in a relaxed position (Fig. 7). T h e n o r m a l l e n g t h f r o m s u b n a s a l e t o u p p e r li l i p in in f e r i o r i s 1 9 to t o 2 2 m m . x I f t h e u p p er lip is a n a to m ica lly sh o rt ( 1 8 m m o r l e s s) s ) , a n i n c r e a s e d i n t e r la la b i a l g a p a n d i n c i s o r e x p o s u r e i s se se e n w i t h a n o r m a l l o w e r f a c e h e i g h t . T h i s s h o u l d n o t b e c o n f u s e d w i t h v e r t ic ic a l m a x i l l a r y e x c e s s ( i n c r e a s e d i n t e r l a b ia ia l g a p , i n c r e a s e d u p p e r i n c i s o r e x posure, increased low er one-third facial height). T h e l o w e r l ip i p is i s m e a s u r e d f r o m l o w e r l ip ip s u p e r i o r to soft tissue menton and normally measures in a range o f 3 8 t o 44 44 m m . ~ n a t o m i c s h o r t l o w e r l i p i s s o m e t i m e s a s s o c i a t e d w i t h C l a s s I I m a l o c c l u s i o n a n d i s v e ri r i f i ed ed b y c e p h a l o m e t r i c m e a s u r e m e n t o f t h e l o w e r a n t er er i o r dental height (lower incisor tip to hard tigsue menton; w o m e n , 4 0 m m + 2 m m , a n d m e n , 4 4 m m - 2 m m ) .6 .6 A n a t o m i c s h o r t l o w e r l ip ip sh sh o u l d n o t b e c o n f u s e d w i t h a s h o rt rt l o w e r l i p s e c o n d a r y t o p o s t u r e ( u p p e r i n c i s o r i n t e r f e re re n c e s ) s e e n i n C l a s s I I d e e p b i t e c a s e s w i t h n o r m a l a n t e r i o r d e n t a l h e i g h t.t . A n a t o m i c s h o r t l o w e r l i p can be lengthened with a lengthening genioplasty.

F i g . 8. Incisor expo sure is is m easu red with with lilips ps relaxe d from from upper lip inferior ( U L I ) to ma xillary inci incisor sor ed ge ( M x l E ) . T h e uppe r tooth tooth to lip ( U T T L ) is the ve rtical dimension dimension of the inci incisor sor exposed between U L I and Mx lE .

natomic long lower lip can be associated with C l a s s I I I m a l o c c l u s i o n s . T h i s s h o u l d b e v e r i fi fi e d w i t h the cepha lom etric anterior dental height me asurem ent. A c l o s e d l i p p o s it i t i o n w i l l p r o d u c e a lo lo n g l o w e r l i p i n c o m b i n a t i o n w i t h i n c r e a s e d l o w e r f a c ia i a l h e i g h t ( v e r ti ti c a l m a x i l l a r y e x c e s s a n d C l a s s I I 1 ) a s t h e li l i p e lo lo n g a t e s t o c l o s e . T h e c l o s e d l i p le le n g t h i s m i s l e a d i n g a n d s h o u l d n o t b e u s e d f o r t r e a t m e n t p l a n n i n g . T h e n o r m a l r a ti ti o o f u p p e r t o l o w e r l i p i s 1 : 2 . j P r o p o r t i o n a t e l ip ip s h a r m o n i z e r e g a r d l e s s o f l e n g th th ; d i s p r o p o r t i o n a t e l i p s m a y need length m odification to appe ar in balance. L ip meas u r e m e n t s i d e n t i f y n o r m a l o r a b n o r m a l s o f t t i s su su e l e n g t h that can be related to dentoskeletal length norm alcy, e x c e s s , o r d e f ic ic i e n c y . L i p r e d u n d a n c y i s se s e e n i n c a s e s o f v e r t ic ic a l m a x i l l a r y deficiency and mandibular retrusion with deep bite and, rarely, long lip lengths. T o accurately assess lip lengths w i t h r e d u n d a n t l i p s, s, t h e p a t i e n t s b i t e m u s t b e o p e n e d u n t il il t h e l i p s s e p a r a t e ( F i g s . 7 ) . ~ T h i s i s b e s t a c c o m p l i s h e d w i t h a p in i n k b a s e p l a t e w a x b i t e u s e d to to o p e n the bite on centric relation (no translation), t Th e face i s e x a m i n e d i n t h a t p o s t u r e , a n d v e r t i c a l s k e l e ta ta l i n creases are planned.

U p p er to o th to lip rela tio n sh ip ( F i g . 8 ) . T h e d i s tance from upper lip inferior to maxillary incisal edge is m easured (Fig. 8). The norm al range is 1 to 5 mm .t W o m e n s h o w m o r e w i t h i n t h is i s ra ra n g e . S u r g i c a l a n d orthodontic vertical chang es are based prim arily on this m e a s u r e m e n t ( i .e . e . , p o s t s u r g i c a l i n c i so so r e x p o s u r e r a n g e oflto5mm). Conditions of disharmony

are produced by four

variables: 1 . I n c r e a s e d o r d e c r e a s e d a n a t o m i c u p p e r l ip i p le le n g t h (infrequently). 2 . I n c r e a s e d o r d e c r e a s e d m a x i l l a r y sk sk e l e t a l l e n g t h (frequently).

 

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( n a t u r a l c h a n g e w i t h a g i n g , e sp e c i a l l y i n m a l e s) , a n d m a n d i b u l a r r e t r u si o n w i t h d e e p b i t e . A b n o r m a l i t i e s s h o u l d b e c o n s i d e r e d w h e n p l a n n in i n g s k e l e t al al c h a n g e s . A n a n a t o m i c a l l y s h o r t u p p e r l i p s h o u ld ld b e r e c o g n i z e d a s a so f t t i ssu e p r o b l e m a n d sh o u l d n o t b e t r e a t e d b y e x c e s si v e l y sh o r t e n i n g t h e m a x i l l a . T h i s c a n l e a d t o a

r } Interlabial Gap

LI ~

F i g 9 I n t e r l a b i a l g a p i s m e a s u r e d i n r e l a x e d l i p p o s i t i o n frfr o m u p p e r l i p i n f e r i o r ULI) t o l o w e r l i p s u p e r i o r LLS).

3 . T h i c k u p p e r l i p s e x p o se l e ss i n c i so r t h a n t h i n u p p e r l i p s, a l l o t h e r f a c t o r s b e i n g e q u a l . 4 . T h e a n g l e o f v ie i e w c h a n g e s t h e a m o u n t o f i n c is is o r v i si b l e t o t h e v i e w e r . T h e t h r e e v a r i a b l e s t h a t contribute to the angle of view are (1) the pat i e n t ' s h e i g h t , ( 2 ) t h e o b se r v e r ' s h e i g h t , a n d ( 3 ) t h e d i st a n c e f r o m t h e f a c i a l su r f a c e o f t h e u p p e r l i p t o t h e i n c i si v e e d g e ( i n c r e a se d l i p t h i c k n e ss r e v e a l s l e ss r e l a t i v e t o o t h e x p o su r e ) .

sh o r t , r o u n d f a c i a l o u t l i n e . Clo sed lip p o sitio n . E v e n t h o u g h a n u n d e r s t a n d in in g o f r e l a x e d l i p p o si t i o n i s e sse n t i a l,l, a n u n d e r st a n d i n g o f c l o se d l i p p o si t i o n a d d s su p p o r t t o d i a g n o st i c p a t t e r n s. T h e c l o s e d l i p p o s i t io io n a l s o r e v e al al s d i s h a r m o n y b e t w e e n sk e l e t a l a n d so f t t i ssu e l e n g t h s. I n c r e a se d m e n t a l i s c o n t r a c t i o n ( m e n t a l i s str str a i n ) , l i p st r a i n , a n d a l a r b a se n a r r o w i n g a r e o b se r v e d i n v e r t ic ic a l sk e l e t a l e x c e ss , a n a t o m i c sh o r t u p p e r l ip ip a n d so m e c a se s o f m a n d i b u l a r p r o t r u s i o n w i t h o p e n b i te te . L i p r e d u n d a n c y i s se e n w i t h v e r t i c a l m a x i l l a r y d e f i c i e n c y a n d m a n d i b u l a r r e t r u si o n w i t h d e e p b i t e . W i t h b a l a n c e d l i p a n d sk e l e t a l l e n g t h s, t h e l ip ip s sh o u l d i d e a l l y c l o se f r o m a r e l a x e d , se p a r a t e d p o si t i o n w i t h o u t l i p , m e n t a l i s, o r a l a r b a se st r a i n . T h e m a x i l l a sh o u l d n o t b e i m p a c t e d t o i d e a l i z e t h e sh o r t u p p e r l i p c l o su r e u n l e ss t h e f a c i a l o u t l i n e w i l l t o l e r a t e su c h a c h a n g e . S m ile p o sitid n lip level. W h e n e x a m i n i n g t h e s m i l e p o st u r e , d i f f e r e n t l i p e l e v a t i o n s a r e o b se r v e d i n n o r m a l a n d a b n o r m a l sk e l e t a l p a t t e r n s. I d e a l e x p o su r e w i t h s m i l e i s t h re re e - q u a r t er er s o f t h e c r o w n h e i g h t t o 2 m m o f g i n g i v a , f e m a l e s m o r e t h a n m a l e s. ~ V a r i a b i l i t y i n g i n g i v a l e x p o su r e i s r e l a t e d t o ( I ) l i p l e n g t h , ( 2 ) v e r t i c a l maxillary length, (3) maxillary anatomic crown length, a n d ( 4 ) m a g n i t u d e o f l i p e l e v a t i o n w i t h sm i l e . Excess gingival exposure m ay be caused by a short u p p e r l i p , v e r t i c a l m a x i l l a r y e x c e ss, sh o r t c l i n i c a l c r o w n , a n d / o r l a r g e l ip ip e l e v at a t i o n w it i t h s m i li li n g . B e c a u s e o f e t i o l o g i c v a r i a b i l it it y , su r g i c a l sh o r t e n i n g o f t h e m a x -

Overimpaction of upper incisor teeth leads to the a p p e a r a n c e o f p r e m a t u r e a g i n g , e s p e c i a l l y in in c o n j u n c t i o n w i t h m a x i l l a r y r e t r a c t i o n . T h i s t y p e o f su r g i c a l movement is rarely indicated. Posterior movement of t h e m a x i l l a r y i n c i so r s i s i n d i c a t e d o n l y f o r t r u e m a x i l l a r y p r o t r u si o n . O r t h o d o n t i c o v e r r e t r a c t i o n , w h i c h i s u se d t o o c c l u sa l l y c o r r e c t m a n d i b u l a r r e t r u si o n , p r o d u c e s p r e m a t u r e a g in in g o f t h e f a c e . l n t e r l a b ia ia l g a p F i g . 9 ) . W i t h t h e l i p s rela xed , a s p a c e o f 1 to to 5 m m ~ b e t w e e n u p p e r l ip i p i n f e r io io r a n d l o w e r l i p su p e r i o r i s p r e se n t ( F i g . 9 ) . F e m a l e s sh o w a l a r g e r g a p w i t h i n t h e n o r m a l ra ra n ge ge . T h i s m e a su r e m e n t i s a l so d e p e n d e n t o n l i p l e n g t h s a n d v e r t i c a l d e n t o sk e l e t a l h e i g h t . I n c r e a se s i n i n t e r l a b i a l g a p a r e se e n w i t h a n a t o m i c

i l l a i s i n d i c a t e d o n l y w h e n e x c e ss g i n g i v a l e x p o su r e i s f o u n d i n c o m b i n a t i o n w i t h i n c r e a se d i n t e r l a b i a l g a p , i n c r e a se d t o o t h e x p o su r e , i n c r e a se d l o w e r f a c e h e i g h t , a n d / o r m e n t a l is is s t r a i n. n. D e f i c i e n t e x p o su r e e t i o l o g i c f a c t o r s i n c l u d e a l o n g u p p e r l i p , v e r t i c a l m a x i l la la r y d e f i c i e n c y , a n d / o r m i n i m a l sm i l e l i p e l e v a t i o n . D e c r e a se d i n c i so r e x p o su r e i s t r e a te te d w i t h m a x i l la la r y l e n g t h e n i n g w h e n f o u n d i n c o m b i n a t i o n w i t h d e c r e a se d i n t e r l a b i a l g a p - l i p r e d u n d a n c y , s h o r t l o w e r o n e - t h i r d f a c e h e i g h t,t, a n d n o r m a l u p p e r l i p length. W h e n i m p a c t i n g o r l e n g t h e n in in g t h e m a x i l l a o n t h e basis of reposed incisor exposure, gingival smile exposure should also be co nsidered. For example, if the p a t i e n t h a s n o r m a l sm i l e g i n g i v a l e x p o su r e ( 1 t o 2 m m )

sh o r t u p p e r l i p , v e r t i c a l m a x i l l a r y e x c e ss, a n d m a n d i b u l a r p r o t r u si o n w i t h o p e n b i t e se c o n d a r y t o c u sp i n t e r f e r e n c e s. D e c r e a se d i n t e r l a b i a l g a p i s f o u n d w i t h v e r tical maxillary deficiency, anatomically long upper lip

a n d t h e i n c i so r s a r e l e n g t h e n e d t o t r e a t d e c r e a se d r e l a x e d l i p i n c i so r e x p o su r e , e x c e ss i v e sm i l e g i n g i v a l e x p o su r e w i l l r e su l t . P a r t i c u l a r c a r e sh o u l d b e t a k e n w i t h sh o r t c l i n i c a l

 

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Fig. 10. Profile Profile angle is m easured b y connecting connecting point pointss glab ella ( G ) , subnasale ( S n ) , and soft tissue tissue pogonion ( P g ) . The angle is measured on the left hand side with the patient facing right.

Fig. 11. Nasolabial angle is developed by connecting columella line inferior nasal septum) ( C ) , subnasaTe S n ) , and upper lip anterior point ( U L A ) .

c r o w n s . A 3 t o 4 m m r e p o s e i n c is is o r e x p o s u r e m a y e x p o s e u n a c c e p t a b l e a m o u n t s o f g i n g i v a w h e n s m i l in in g because of short maxillary incisor crowns. This situat i o n is is p r o p e r l y t r e a t e d b y p l a c i n g n o r m a l l e n g t h c r o w n s

include maxillary protrusion (rare), vertical maxillary e x c e s s ( c o m m o n ) , a n d m a n d i b u l a r r e tr t r u s io io n ( c o m m o n ) . Cl a s s I I I s k e l e t a l p a t t e r n s i n c l u d e m a x i l l a r y r e t r u s i o n (common), vertical maxillary deficiency (rare), and

) otnh et hree pmoasxei lan n( vi ne ng e ferros m alna dr y s imn ci lies opres r sa pn edc tt riv i ve ae t. mTehnet p gl ai nn -g i v a l s m i l e i s n e v e r t re re a t e d t o i d e a l a t t h e e x p e n s e o f underexposing the incisors in the relaxed lip position.

mandibular protrusion (common). Surgical procedures should generally address the cosmetic imbalance established with this angle. The profile angle is the most important key to the need for anteroposterior surgical correction. When values are l e ss ss t h a n 1 6 5 ~ o r g r e a t e r t h a n 1 7 5 ~ s k e l e t a l m a l o c c l u sions needing surgery are probably the cause. Angles a t t h e e x t r e m e o f n o r m a l ( g r e a t e r t h a n 1 7 5~ o r l e s s t h a n 1 6 5~ a r e u s u a l l y c a u s e d b y s k e l e t a l d i s h a r m o n y . S o f t tissue thickness differences are not capable of causing t h e se se e x t r e m e a n g l e c h a n g e s .

PROFILE VIEW Natural head posture, centric relation, and relaxed lips are used to accurately assess profile.' P r o f i le le a n g l e F i g . 10) This angle is formed by connecting soft tissue glab e l l e , s u b n a s a l e , a n d s o f t t is is s u e p o g o n i o n ' ( F i g . 1 0 ). ). 7.8 General harmon y of the forehead, midface, and lower face is appraised with this angle. Maxillary and mandibular basal bone antero posterior discrepancies are e a s i l y v i s u a l i z e d . Cl a s s I o c c l u s i o n p r e s e n t s a t o t a l f a c i a l a n g l e r a n g e o f 1 6 5~ t o 1 7 5 ~ ' C l a s s I I a n g l e s a r e l e s s t h a n 1 6 5 ~ a n d Cl a s s I I I a r e g r e a t e r t h a n 1 7 5 ~ S k e l e t a l d i s c r e p a n c i e s p r o d u c i n g Cl a s s I I a n g u l a t i o n

Nas olablal angle Fig. 11) T h i s a n g l e i s f o r m e d b y t h e i n t e rs rs e c t io io n o f t h e u p p e r lip anterior and columella at subnasale (Fig. 11). This a n g l e c a n c h a n g e n o t i c e a b l y w i t h o r t h o d o n t i c an an d s u r gical procedures that alter the anteroposterior position or inclination of the max illary an terior teeth.9I' All procedures should place this angle in the cosmetically

 

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A merican merican Journal of Orthodont Orthodontics ics and Dentof Dentofacial acial Orthoped Orthopedics ics May

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mass proportion (upper versus lower), posterior rotations, curve of Spee (upper versus l o w e r ) , a n d a n c h o r a g e ( h e a d g e a r , Cl a ss I I elastics). 7 . E x t r a c t i o n v e r su s n o n e x t r a c t i o n . 8 . E x t r a c t i o n p a t t e r n ( f i r st st v e r su s s e c o n d p r e m o l a r s) .

MxS

F i g . 1 2 . M a x i l l a r y s u l c u s c o n t o u r MxSC) s s u b j e c t i v e l y a s sessed. Th e contour is described as e ither accentua ted, gentle c u r v e n o r m a l ) o r flfl a t . M e a s u r e m e n t o f t h i s c o n t o u r is is im im p r a c t ic a l.

I f t h e n a so l a b i a l a n g l e i s o p e n ( a p p r o x i m a t e l y , 1 0 5 ~ r e t r a c t io io n o f a n t e r i o r t e e t h o r t h o d o n t i c a l l y a n d su r g i c a l l y sh o u l d b e a v o i d e d i n t r e a t m e n t p l a n n i n g . L i k e w i s e , a l o n g n o s e w i l l b e c o m e a d v e r s e l y p ro ro m i n e n t w i t h l i p r e t r a c t i o n . P r e se n t l i m i t e d k n o w l e d g e o f h o w l i p s r e s p o n d t o a n t e r o p o s t e r i o r m o v e m e n t o f t h e t e e th th d i c tates a conservative approach when large movements a r e c o n t e m p l a t e d . rowding dictates t h e n e e d f o r e x traction, facial balance influences which teeth are ext r a c t e d a n d h o w sp a c e s a r e c l o se d . S u r g i ca c a l m o v e m e n t o f t h e m a x i l l a a ls ls o a f f e c t s t h e n a so l a b i a l a n g l e . T h e sa m e f a c t o r s t h a t a f f e c t o r t h o dontic change should be analyzed when considering maxillary movement. As a general rule, the maxilla s h o u l d n o t b e m o v e d p o s t e r i o r l y i n t r e a ti ti n g d e n t o f a c i al al deformities, especially in combination with superior r e p o si t i o n i n g . T h i s c r e a t e s n a sa l e l o n g a t i o n , a l a r b a se d e p r e ssi o n , a n d o p e n i n g o f t h e n a so l a b i a l a n g l e , a l l o f which create facial premature aging. Inadvertent maxi l l a r y r e t r a c t i o n o c c u r s w i t h i so l a t e d L e F o r t su r g e r y when the VTO x-ray film is taken with the condyles o n t h e e m i n e n c e r a t h e r t h a n se a t e d i n t h e f o ssa . M a x i lll l a r y s u l c u s c o n t o u r

F ig ig . 1 2 )

d e si r a b l e r a n g e o f 8 5 ~ t o 1 0 5 ~ I F e m a l e p a t i e n t s w i l l u su a l l y b e m o r e o b t u se w i t h i n t h i s r a n g e . F a c t o r s t o b e c o n s i d e r e d i n t r e a tm tm e n t p l a n n i n g t o c o r r e c t l y a c h i e v e t h i s a n g l e a r e a s f o l l o w s: I . E x i st i n g a n g l e . 2. Tilting versus bodily movement of maxillary t e e t h ( o r t h o d o n t i c a n d su r g i c a l ) a n d p r e d i c t e d e f f e c t o n t h e e x i st i n g l i p p o si t i o n . 3 . E st i m a t i o n o f li li p t e n si o n p r e se n t . T e n se l ip ip s m a y m o v e m o r e p o s t e r i o r l y w it it h t o o t h a n d b a s a l b o n e m o v e m e n t a n d l e ss a n t e r i o r l y . F l a c c i d l i p s m a y m o v e l e ss w i t h p o st e r i o r t o o t h a n d b a sa l b o n e m o v e m e n t a n d l e s s w i th th a n t e r i o r . ' 4 . A n t e r o p o st e r i o r lili p th th i c k n e ss. T h i n l i p s ( 6 to to 1 0 ram) 9 12 ~3m ay m ov e mo re with tooth retraction m ov em en t than th ick lips (1 2 to 20 m m ). I-''~4 5 . T h e m a g n i t u d e o f t h e m a n d i b u l a r r e t ru ru s i o n ( o v e r j e t ) . T h e l a r g e r t h e o v e r j e t d i st a n c e , t h e

N o r m a l l y t h i s su l c u s i s g e n t l y c u r v e d 15 a n d g i v e s i n f o r m a t i o n r e g a r d i n g u p p e r l ip ip te te n si o n ( F i g . 1 2 ). ). W i t h l i p t e n si o n , t h e su l c u s c o n t o u r f la la t te te n s. F l a c c i d l i p s f o r m a n a c c e n t u a t e d c u r v e w i t h t h e v e r m i l i o n l i p a r e a sh o w i n g a n a c c e n t u a t i o n o f c u r v e . ,2 ,2 T h e f l a c c id id l i p g e n e r a l l y is thick (12 to 20 mm from anterior vermilion to labial i n c i so r ) g i v i n g t h e l i p ( i . e . , h e a d g e a r w i t h Cl a ss I I e la la stics or functional appliance treatment) the appearance o f b e i n g t o o f a r f o r w a r d r e l a t i v e to to t h e t e e t h . '2 T h e m a x i l l a sh o u l d n o t b e r e t r a c t e d si g n i f i c a n t l y w h e n a d e e p l y c u r v e d , t h i c k l i p i s p r e se n t si n c e t h i s p r o d u c e s p o o r l i p su p p o r t a n d c o sm e t i c s. I f p o ssi b l e , t h e m a x i l l a should be moved forward into a thick, curved lip to i m p r o v e l i p su p p o r t .

m o r e r e t r a c t i o n o f t h e m a x i l l a r y i n c i so r s w i l l b e necessary, thus opening the nasolabial angle..gLz angle..gLz 6 . T h e f o l l o w i n g f a c to to r s a f f e c t t h e a n t e r o p o s t e r io io r movement of incisor teeth after extractions: A m o u n t o f a n te te r i o r c r o w d i n g , s p a c e s , t o o t h

i s f l a c c i d i n c h a r a c t e r ( Cl a ss I 1 , v e r t i c a l m a x i l l a r 3 / d e f i c ie ie n c y ) . T h e d e e p c u r v e i s u s u a ll ll y s e c o n d a r y t o m a x i l la la r y i n c i so r i m p i n g e m e n t i n t h e c a se o f d e e p b i t e Cl a ss II and vertical maxillary deficiency. When flattened, t h e l o w e r l i p d e m o n st r a t e s t e n si o n o f t issu issu e s ( Cl a ss I 11 11 ). ).

M a n d i b u l a r s u l c u s c o n t o u r F ig ig . 1 3 )

This con tour is a gentle curve ~ (Fig. 13) and can i n d i c a t e l i p t e n si o n . W h e n d e e p l y c u r v e d , t h e l o w e r l i p

 

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American Journal of Orthodo Orthodontics ntics and Dentofacial Orthoped Orthopedics ics Volume 103 No 5

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F i g . 1 3 . M a n d i b u l a r s u lc lc u s c o n t o u r MdS C ) s s u b j e c t i v e l y a s sessed. The contou r is either accentu ated, gentle curve norma l) or flat. Me asu rem ent of this contour is impractical.

Fig. 14. Orbital rim projection is measured from the anterior m o s t g l o b e Gb) o t h e o r b i t a l r im im p o i n t OR). A s u b j e c t i v e o r b i ta ta l r i m d e s c r i p t i o n i s a l s o g i v e n : N o r m a l , f l a t,t, o r p r o t r u d e d .

Surgical procedures that correct the basal bone generally will improve the mandibular sulcus angle (i.e., deep contour associated with deep bite Class II malocclusion or flatness associated with mandibular pro-

deficient in combination with maxillary retrusion. Deficient cheekbones may correlate positionally with a retruded maxillary position because the osseous structures are often deficient as groups, rather than in iso-

trusion).

lation. Cheekbone contour is used as one of the main i n d i c a t o r s o f m a x i l l a r y r e tr tr u s i o n . T h i s a r e a s h o u l d h a v e an apex at the cheekbone point (CP) and not appear f ia ia t.t. T h e C P i s l o c a t e d 2 0 t o 2 5 m m i n f e r i o r a n d 5 t o 10 mm anterior to the outer canthus (OC) of the eye w h e n v i e w e d i n p r o f i le l e (F (F i g . 1 5) 5) . W h e n v i e w e d f r o n t a l l y t h e CP i s 2 0 t o 2 5 m m i n f e r i o r a n d 5 t o 1 0 m m l a t e ra ra l t o th th e O C ( F i g . 1 6 ). ). I t s h o u l d b e n o t e d t h a t t ru ru e m a n d i b u l a r p r o g n a t h i s m c a n s h o w m i l d m a l a r f l a tn tn e s s a s a r e la la t i v e o b s e r v a t i o n t o t h e e x t r e m e c h i n p r o t r u s i o n . True maxillary hypoplasia often is associated with true m a l a r d e f i c i en en c y .

O r bi tal r i m F i g. 14) T h e o r b i ta ta l r i m i s a n a n t e r o p o s t e r i o r in in d i c a t o r o f m a x i l l a r y p o s i t i o n . D e f i c i e n t o r b i t a l r im im s m a y c o r r e l a t e positionally with a retruded maxillary position because the osseous structures are often deficient as groups, rather than in isolation. The globe normally is positioned 2 to 4 m m anterior to the orbital rim (Fig . 14). t The surgical maxillary versus mandibular decision is influenced by the orbital rim position. Deficient orbital rims dictate maxillary advancement, all other factors being equal. Ch eekb one co ntour

F ig ig s . 1 5 a n d 1 6 )

Cheekbone assessment requires frontal and profile e x a m i n a t i o n s i m u l t a n e o u s l y ( F i g s . 1 5 a n d 1 6 ) . Ch e e k bone contour (CC) correlates with maxillary anteroposterior position, frequently the cheekb one co ntour is

N a s a l b a s e - l i p c o n t o u r F i g s. s. 1 5 a n d 1 6 )

The nasal base-lip contour (Nb-LC) line requires - -frontal and p rofile exam ination simultaneo usly (Figs. 1 5 a n d 1 6 ). ). T h e l i n e i s t h e c o n t i n u a t i o n o f th th e c h e e k b o n e c o n t o u r l i n e . T h i s a r e a i s a n i n d i c a to to r o f m a x i l l a r y and ma ndibular skeletal antero posterio r position. Nor-

 

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Figs . 15 a nd 16. Chee kbo ne conto ur is is anteriorly facing, facing, curved curved line that starts starts just anterior to ear, e x te n d i n g forw forw a rd rd th ro u g h c h e e k b o n e p o i n t CP), then ex tending anteridr-i anteridr-inferi nferiorly orly ending at m axilla p o i n t M x P ) adjace nt to alar base of nose. F.ordescri descripti ptive ve purposes the c hee kbon e contour contour is divided into three areas: 1) zygom atic arch, 2) middle contou r area, and 3) subpupil subpupil areas. The se three three areas, whe n taken together, constitute constitute the chee kbon e contour. Reconstruction Reconstruction of che ekbo ne contour, whe n deficient, deficient, should a nalyz e all three parts s epara tely in terms o f correction. correction. C P a n d M x P indicates osseous chee kbon e and ma xillary bas e positions, positions, respectively. respectively. The nasal base -lip contour Nb-LC) exten ds inferior inferiorly ly from the ma xilla point M x P ) as a gentle, anteriorly faci facing ng curve, ending just just b elow and latera l to the mo uth commissure. In normoskeletal normoskeletal patients the chee kbon e-na sal base-li base-lipp contour com plex is a smooth conti continuation, nuation, a nteriorly faci facing, ng, curved liline. ne. This line, when v iewe d frontally frontally or from the side, is a definite flowing flowing curve w ith no interruptions interruptions which are ap pare nt with skeletal defordeformities.

axillary axil lary R etrusion

h

m a l p o si t i o n is is i n d i c a t e d b y th th e m a x i l l a p o i n t M x P ) d i r e c t l y b e h i n d t h e a l a r b a se . T h e M x P i s t h e m o st anterior point on the con tinuum of the cheekbone-nasallip contour and is an indication of maxillary anterop o st e r i o r p o si t i o n . M a x i l l a r y r e t r u si o n i s i n d i c a t e d b y a st r a i g h t o r c o n c a v e c o n t o u r a t M x P F i g . 1 7 ).). W h e n t h is is a n a t o m i c area is concave or fiat, maxillary advancement is nece ssa r y . M a n d i b u l a r p r o t r u si o n i n t e r r u p t s t h e n a sa l b a se - l i p l i n e i n t h e l en en g t h o f t h e u p p e r l i p F i g . 1 8 ). ). W h e n t h e line is interrupted within the height of the upper lip a m a n d i b u l a r s e t b a c k m a y b e i n d i ca ca t e d .

N a s a l p r o j e c t io io n

F ig ig . 1 9 )

T h e n a s a l p r o je j e c t i o n N P ) m e a s u r e d h o r i z o n ta ta l l y f r o m su b n a sa l e t o n a sa l t i p i s n o r m a l l y 1 6 t o 2 0 m m Fig. 17. Ma xillary retr retrusion: usion: C heek bone -nasa l base-li base-lipp cu rve is interrupted at M xP. interrupted

 

  meri merican can Journal of Orth Orthodon odontics ticsand Dento Dentofaci facial al Orth Orthoped opedics ics Volume 1 0 3 N o . 5

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a n d i b u l a r P r o t r u s io io n

P T

Fi g. 18. M and i bul ar prot protrus rus ion: ion: C heek bone -nas al bas e-l i p c urv e i s i nt errupt ed i n upper l i p area.

( F i g . 1 9 ) . ' N a sa l p r o j e c t i o n i s a n i n d i c a t o r o f m a x i l l a r y a n t e r o p o s t e r i o r p o s i t io io n . T h i s l e n g th th b e c o m e s p a r t i c u l a rl rl y i m p o r t a n t w h e n c o n t e m p l a t i n g a n t e r io io r m o v e m e n t o f th th e m a x i l l a . D e c r e a se d n a sa l p r o j e c t i o n c o n t r a i n d i c a t e s m a x i l l a r y a d v a n c e m e n t . W i t h a Cl a ss I I I m a l o c c l u si o n , sh o r t n o se , a n d a l l o t h e r f a c t o r s e q u a l , 9 m a n d i b u l a r se t b a c k i s i n d i c a t e d . Throat length and contour

Fig . 19. Nasal projection projection ( N P ) i s m eas ured f rom s ubna s al e (S n) t o nas a l t ip ip (NT). T h e l in in e s t h r o u g h S n a n d N T are perpendi c ul ar t o t he f l oor w hen t he head i s i n a na t ural pos tural tural pos i titi on.

Fig. 20)

The distance from the neck-throat jun ction to the s o f t t is i s s u e m e n t o n s h o u l d b e n o t e d ( F i g . 2 0 ) . N o m i lllimeter measurement is necessary, but a planned mand i b u l a r se t b a c k w i l l c h a n g e t h i s l e n g t h . T h e p r e d i c t e d e st h e t i c r e su l t sh o u l d p r o d u c e a n o r m a l a p p e a r i n g l e n g t h w i t h o u t sa g g i n g . A p a t i e n t w i t h a sh o r t , sa g g i n g t h r o a t l e n g t h i s n o t a g o o d c a n d i d a t e f o r m a n d i b u l a r se t b a c k . A l o n g , st r a i g h t t h r o a t le le n g t h i s a m e n a b l e t o m a n d i b u l a r se t b a c k . O f t e n a m a n d i b u l a r se t b a c k i s n e c e ssa r y w i t h chin augmentation to balance lips with chin and maint a i n t h r o a t l e n g t h . S u c t i o n l i p e c t o m y i s a u se f u l a d j u n c t f o r c o n t r o l l i n g su b m e n t a l sa g w i t h se t b a c k s o r w h e n i so l a t e d f a t a c c u m u l a t i o n i s p r e se n t . S u b n a s a l e - p o g o n i o n l in in e (S (S n - P g )

Fig. 21)

Bu r st o n e r e p o r t e d t h a t t h e u p p e r l i p i s i n f r o n t o f t h e S n - P g ' l i n e b y 3 .5 .5 m m • 1 . 4 m m , a n d t h e l o w e r lip iiss in fron t o f the the line by 2.2 mm --- 1.6 mm . 16 T h e r e l a t i o n sh i p o f t h e l i p s t o t h e S n - P g ' l i n e i s a n i m p o r t a n t a i d i n o r t h o d o n t i c so f t t i ssu e a n a l y si s a n d t r e a tm tm e n t . T o o t h m o v e m e n t c h a n g e s t h e r e la l a t io io n s h i p o f t h e l i p s t o t h e S n - P g ' l i n e a n d t h e r e f o r e t h e e st h e t i c

F i g . 2 0 . T h r o a t l e n g t h (TL) is assessed from neck-throat point ( N T P ) t o s oft oft t i s s ue m ent on (Me'). Thi s di s tanc tanc e i s s ubj ec t i v el y des c ri bed as ei t her norm al , l ong or s hort l engt h, and w i t h or w i t hou t s ag.

 

4 6

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merican Journal of o f Orthodontics and Demofacial Orthopedics Orthopedics May 9 9 3

l i p s t h r o u g h su b n a s a l e . I f P g i s si g n i f i c a n t ly ly p o st e r i o r to the line, a chin augmentation is indicated. Female c h i n s a r e so f t e r r e l a t i v e t o t h i s l i n e . SOFT TISSUE CH SKELET

Sn

R

CTERISTICS

OF COMM ON

L DEFORMITIES

W i t h t h e 1 9 fa fa c i a l k e y s, 8 p u r e sk e l e ta ta l d e f o r m i t i e s w i t h p r e d i c t a b l e so f t t i ssu e a p p e a r a n c e s c a n b e d e f i n e d . The greater magnitude of the skeletal deformity the m o r e d i st i n c t th th e so f t t i ssu e p a t t e r n . S k e l e t a l d e f o r m i t i e s m a y occur hz combin tion ( i . e . , v e r t i c a l m a x i l l a r y e x c e ss w i t h m a n d i b u l a r p r o g n a t h i sm ) a n d f a c i a l t r a i t s a r e t h e r e f o r e b l e n d e d . I n a l l c a se s, f a c i a l t r a i t s a r e h e l p f u l i n d i ag a g n o s i n g s k e l e t al al p r o b l e m s . T h e e i g h t u n c o m b i n e d o r p u r e o r u n m i x e d a n t e r o p o s t e r i o r f a c ia i a l - sk sk e l e ta ta l t y p e s a r e a s f o l l o w s: A . Cl a ss I f a c i a l a n d d e n t a l ( f a c i a l a n g l e Cl a ss l ) (Fig. 24) 1 . V e r t ic ic a l m a x i l l a r y e x c e ss ( T a b l e lI lI ) 2 . V e r t ic ic a l m a x i l l a r y d e f i c i e n c y ( T a b l e I I I )

Fi g. 2 1. S u bnas al e pogo ni on ref eren c e l i ne i s generat ed t h r o u g h p o i n t s s u b n a s a l e ( S n ) a n d s o ftft t i s s u e p o g o n i o n ( P g ) . Li p projec projec t ions ions are ev al uat ed rel at i v e to to t hi s l i ne.

r e su l t . A l l t o o t h m o v e m e n t s sh o u l d b e a sse sse d i n r e g a r d t o th th e a n t i c i p a t e d li li p c h a n g e t o t h e S n - P g l i n e . E x t r a c ti t i o n s s h o u l d b e a v o i d e d w h e n t h e y m o v e t h e t e e th th a n d c r e a t e r e t r a c t i o n o f t h e l i p s ( d i sh e d - i n ) b e h i n d t h i s l i n e ( F i g . 2 2 ) . O n t h e o t h e r h a n d , i f u n r a v e l l in in g t h e crowding with extractions allows for lip balance to the S n - P g l i n e , t h e e x t r a c t i o n s a r e e st h e t i c a l l y a c c e p t a b l e . T h e r e l a t i o n sh i p o f t h e l i p s t o t h i s l i n e i s a f f e c t e d b y t h e f o l l o w i n g f a c t o r s: 1 . S k e l e t a l r e l a t io io n sh i p : W h e n a n t e r i o r o r p o st e r i o r skeletal disharmony exists, producing overjet a b n o r m a l i t i e s ( p o si t i v e o r n e g a t i v e ) , t h e S n - P g has no validity. 2 . I n c i so r i n c l in in a t i o n s: W i t h a Cl a ss I sk e l e t a l p a ttt e r n , t h e u p p e r a n d l o w e r i n c i so r s m u st b e a t proper overjet and axial inclination to produce p r o p e r p r o t r u si o n o f t h e l i p s r e l a t i v e t o t h e S n Pg line. 3 . L i p t h i c k n e ss: T h e l ip ip r e la la t i o n sh i p t o t h e S n - P g l i n e i s d e p e n d e n t o n l i p t h i c k n e ss. T h e Bu r st o n e r e l a t i o n sh i p t6 i s t r u e o n l y i f t h e l i p s a r e t h e sa m e t h i c k n e ss, a l l o t h e r f a c t o r s b e i n g i d e a l . Cl a ss I i n c i so r s ( u p p e r i n c i so r i n f r o n t o f l o w e r i n c i so r ) p r o d u c e Cl a ss I l i p s ( u p p e r l i p i n f r o n t o f l o w e r l i p ) o n l y i f t h e l i p s a r e o f e q u a l t h i c k n e ss. T h i s l i n e i s a l so u se d w h e n p l a n n i n g su r g e r y o n t h e V T O ( F i g . 2 3 ) . T h e S n - P g l i n e i s i d e a l ly ly d r a w n t o th th e

B. Cl a ss I I f a c i a l a n d d e n t a l ( f a c i a l a n g l e Cl a ss I I ) (Fig. 25) 3 . M a x i l l a r y p r o t r u si o n ( T a b l e I V ) 4 . V e r t ic ic a l m a x i l l a r y e x c e ss ( T a b l e I I ) 5 . M a n d i b u l a r r e t r u si o n ( T a b l e V ) C. Cl a ss I I I fa fa c i a l a n d d e n t a l ( f a c i a l a n g l e Cl a ss I I I ) (Fig. 26) 6 . M a x i l l a r y r e t r u si o n (T (T a b l e V I ) 7 . V e r t i c al al m a x i l l a r y d e f i c i e n c y ( T a b l e I l l) l) 8 . M a n d i b u l a r p r o t r u si o n (T (T a b l e V I I ) K n o w i n g t h e e i g h t u n m i x e d sk e l e t a l p a t t e r n s i s h e l p ful in organizing facial analys is inform ation into a coh e si v e , m e a n i n g f u l w h o l e . W i t h o u t f a c i a l a n a l y si s, d i st i n g u i sh i n g t h e sk e l e t a l so u r c e o f t h e m a l o c c l u si o n c a n b e d i f f i c u l t . F a c i a l t r a i t i d e n t i f ic ic a t i o n a n d c a t e g o r i z a t i o n l e a d s t o a d i f f e r e n t i a l d i a g n o si s o f sk e l e t a l p a t t e r n s ( T a b l e V I I I Cl a ss I I , T a b l e IX IX Cl a ss I l l ) . Ce p h a l o m e t r i c a n a l y si s h a s b e e n s h o w n t o b e i n e f f e c t i v e in in t h i s r e g a r d . T h e a d v a n t a g e o f a d i a g n o si s b a se d o n f a c i a l t r a i t s i s important. Skeletal malocclusions have profound soft t i ssu e i m b a l a n c e t h a t p a t i e n t s e x p e c t t o b e c o r r e c t e d . F a c i a l b a se d t r e a t m e n t p l a n n i n g e n su r e s t h a t f a c i a l change will be correct, whereas cephalometrics have b e e n s h o w n t o h e u n r e l ia ia b l e . ORTHOD ONTIC

PREP

R

TION FOR SURGER Y

F a c i a l a n d d e n t a l d i sc r e p a n c i e s m a y n o t b e p r o p o r t i o n a te te b e c a u s e o f d e n t a l c o m p e n s a t i o n s t o t h e a n t e r o p o st e r i o r sk e l e t a l m a l a l i g n m e n t . ~7 D e n t a l c o m p e n s a t i o n s a r e i n c i so r a x i a l i n c l i n a t i o n c h a n g e s i n r e sp o n se to increased or decreased overjet. Mandibular retrusion a n d , o c c a si o n a l l y , v e r t i c a l m a x i l l a r y e x c e ss a r e a sso c i a t e d w i t h l o w e r i n c i so r f l a r i n g a n d u p p e r i n c i so r u p -

 

A m e ri ri ca ca n J o u rn rn a l o f O r th th t M o nt nt ic ic s a n d D e n te te ~ a ci ci a l O r th th o p ed ed i cs cs Volume 103 N o 5

Ar ne tt an d Be rg m an

407

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Fig. 22. A, No rmal lip relationship to Sn-P g' line. B, Premature aging asso ciated with prem olar ext r a c t io io n s a n d i n c i s o r r e t ra ra c t i o n . T h e l i p s f a l l o n o r b e h i n d t h e S n .~ .~ P g ' i n e g i v in in g t h e d i s h e d - i n o r t h o d o n t i c a p p e a r a n c e . T h e n a s o l a b i a l a n g l e m a y a l s o o p e n t o u n a c c e p t a b l e ra ra n g e s .

r i g h t i n g . M a n d i b u l a r p r o t r u si o n , m a x i l l a r y r e t r u si o n a n d v e r t i c a l m a x i l l a r y d e f i c i e n c y a r e a sso c i a t e d ~ v i t h u p p e r i n c i s o r f la la r in in g a n d l o w e r i n c i s o r u p r i g h t i n g . Extraction patterns and mechanics are aimed at removing dental compen sations.before surgery. Compen sa t i o n r e m o v a l l e a d s to to b e t t e r fa fa c i a l r e su l t s. A n e x a m p l e o f t h is is i s a 1 0 m m sk e l e t a l m a n d i b u l a r r e t r u si o n . I n c i so r dental compensations to the overjet may decrease the 10 mm overje t to 5 ram. If the mandible is advanced w i t h t h e c o m p e n sa t i o n s p r e se n t , t h e c h i n d e f i c i e n c y i s st i l l 5 m m . I n c o n t r a st , w h e n d e n t a l c o m p e n sa t i o n s a r e r e m o v e d , t h e 1 0 m m o v e r j e t a n d 1 0 m m c h i n re re t r u s io io n a r e si m u l t a n e o u sl y a n d t o t a l l y c o r r e c t e d w i t h su r g i c a l advancement. I n a p p r o p r ia ia t e o r t h o d o n t i c p r e p a ra ra t i o n ( e . g . , u p p e r f ir ir st st p r e m o l a r e x t r a c t i o n s, h e a d g e a r a n d Cl a ss I I e l a st i c s t o t r e a t a sk e l e t a l m a n d i b u l a r r e t r u si o n ) d i st o r t s t h e equality of the dental and facial problems far mo re than d e n t a l c o m p e n sa t i o n s. I n a n a t t e m p t t o c o r r e c t t h e b i t e w i t h o u t s u r g e r y , th t h e d e n t al al d i s c r e p a n c y b e c o m e s m u c h l e ss t h a n t h e f a c i a l d i sc r e p a n c y m a g n i t u d e . S u b se q u e n t l y , i f su r g e r y i s u se d f o r d e n t a l c o r r e c t i o n , th th e so f t t i ss ss u e p r o b l e m i s o n l y m i n i m a l l y c o r r e c t e d . T h i s p r o b l e m l e a d s t o t h e c o n c l u si o n t h a t su r g e r y sh o u l d b e planned from the beginning to obtain optimal facial c h a n g e s w i t h b i t e c o r r e c t i o n . ' 7 ~ E x t r a c t i o n s sh o u l d b e p l a n n e d a r o u n d f a c t o r s i n c l u d i n g , m o st i m p o r t a n t l y , c r o w d i n g , p e r i o d o n t a l n e e d s, a n d f a c i a l i m p l i c a t i o n s. G e n e r a l l y , e x t r a c t io i o n p a t t er er n s d e c r e a s e d e n t a l c o m p e n sa t i o n t o t h e i n c i so r o v e r j e t p r o b l e m . The most common appropriate extractions for rout i n e f a c i a l - sk e l e t a l d e f o r m i t i e s a r e a s f o l l o w s:

Sn Ideal

t pg lk NeededChl.e Augmmtatloe

Fig. 23. S n-Pg ' line is frequently used to surgically assess chinlip-nasal base b alance. With the v- ro occlusion in Class I, the l i n e is is o r i e n t e d f r o m S n t h r o u g h i d e a l l i p p o s i t io io n . I f P g ' f a l l s o n the chin, balance of chin-lip-nasal base is ideal. If Pg' falls behind the line, a chin advancement is necessary to obtain balance.

A . Cl a ss 1 f a c i a l a n d d e n t a l ( c h i n i n b a l a n c e w i t h the face) 1 . V e rt r t ic ic al a l m a x i ll l l a ry ry e x c e s s I v a r i a b l e 2 . V e rt rt ic ic al al m a x i l l a r y d e f i c i e n c y I v a r i a b l e

 

408

  merican Journal of Orthodontics and Dentofaeial Orthopedics Orthopedics

M a y 1993

Arnett and Bergman

CL AS S

I s

e ie n

F igv,ert 2 4i c. al Cla s iIl l oary c c lu sio sio a n dy . cThhe in pant ro eropOs je c tio tio n teri a noroprof c c u ri l eini sc onorm mbminala tio n with wit e rtic maght x ill illaaofrythe e x cf ac e s es or msax def i cnienc ienc tcerior nor but t heh vvert i c ala lhei the i s l ong or s hort . 4

Table II. Vertical maxillary excess: common

T a b l e I ll l l . V e r t i c al al m a x i l l a r y d e f i c i e n c y : c o m m o n

f a c i a l c h a r a c t e r i s ti ti c s o f v e r t i c a l m a x i l l a r y excess are listed

deficiency are listed

Vertical maxilla ry excess

facial characteristics of vertical maxillary Vertical maxillary deficiency

Increased lower one-third Increased interlabial gap Increased incisor exposure Increased gingival smile Mentalis strain Decreased total profile angle* Accentuated mandibular sulcus contour

Decreased lower one-third Decreased interlabial gap Decreased incisor exposure Decreased incisor exposure with smile Lip redundancy Straight to to C lass Ill profile angle* Accentuated mandibular sulcus contour

Decreased throat length Norm al nasal projection projection Norm al nasotabial angle

Norm al nasal projection projection Norm al to decreased nasolabial angle Increased throat length Norm al cheekbones, cheekbones, alar base

*Class I VME can have a norm al total total facial angle.

*Class I VMD can have a normal total facial angle. B. Class II facial and dental

chin retruded)

1. M a x i l l a r y p r o t r u s i o n - - l o w e r s e c o n d a n d / o r upper first prem olars, o rthodontic correction. No surgery required. 2 . V e r ti t i c al a l m a x i l l a r y e x c e s s - - u p p e r e x t r a c ti ti o n based on extent and location of crowd ing, lower extraction based on effects on u pper lip support when LeFort I is done to correct vertical maxillary excess. 3 . M a n d i b u l a r r e t r u s i o n - - u p p e r s e c on on d p r e m o l a r a n d / o r l o w e r f i rs rs t p r e m o l a r s C . C l a s s I II II f a c i a l a n d d e n t a l c h i n p r o t r u d e d )

1 , M a x i l l a r y r e t r u s i o n - - u p p e r f ir i r st st a n d l o w e r second premolars 2 . V e r ti t i c al a l m a x i l l a r y d e f i c i e n c y - - u p p e r fi f i rs rs t a n d lower second premolars 3 . M a n d i b u l a r p r o t r u s i o n - - u p p e r ffii rs rs t a n d l o w e r second premolars A n a d d i t i o n a l b e n e f i t o f t h e s u r g ic ic a l e x t r a c t i o n p a t t e r n i s t h at at t h e a n t i c i p a t e d s u r g i c a l r e l a p s e b e c o m e s t h e o p p o s i t e o f t h e o r t h o d o n t ic i c r e l a p s e p a tt t t e r n. n. A n e x a m p l e o f t h i s i s m a n d i b u l a r a d v a n c e m e n t w i t h l o w e r f i r st st p r e -

 

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xce~ -