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Anterior open-bite: A cephalometric analysis and suggested treatment procedures
Anterior open-bite: A cephalometric analysis and suggested treatment procedures Henry I. Nahoum, D.D.S.*
New Yorlc, N. Y.
0
n e of the most difficult aspects of diagnosis lies in making a decision regarding the nature of the condition or syndrome under consideration. This conceptual difficulty is illustrated by some recent articles on the subject of anterior open-bite. I, 2 In these reports, “open-bite” is considered an adequate definition of the condition, and little consideration is given to the fact that this term includes several skeletal variants that all have in common a ?zegative incisal overbite.3 The purpose of this essay is to present a cephalometric assessment of various types of anterior open-bite malocclusion and to review some concepts that may help in understanding the limitations in the treatment of such patients. Many of these concepts are not new and have been ably presented by Hellman Subtelny and associates,5* 6 and Horowitz and Hixon.7 It should be emphasized that cephalometrics, at best, is a descriptive technique which helps to define or classify a condition but does not necessarily provide us with the insight for the successful treatment of an anomaly. Review of the literature
Anterior open-bite has been grouped into two broad categories. The first category consists of the acquired or dental open-bites which do not show any distinguishing craniofacial malformations. The second group consists of patients with craniofacial dysplasia in addition to the open-bite. The dental open-bites are believed to result from obstructed eruption of the anterior teeth (Fig. 1). Many of these show spontaneous remissions, and 75 to 80 per cent have marked improvement without any form of treatment.8 Presented before the Kortheastern Society of Orthodontists, Nov. 8, 1974. *Associate Professor of Dentistry, Columbia University School of Dental and Oral Surgery.
513
Fig. 1.
The dentition of a patient with a habitual anterior open-bite which was probably
initiated by thumb-sucking. Note the asymmetric opening caused by placing the thumb on the right side. This type of open-bite responds to habit therapy.
Fig. 2.
A,
The dentition of a patient with a “transitional” open-bite with a Class II
malocclusion and mild anterior crowding. B, The dentition of the same patient after treatment with cervical extraoral force. A lower lingual arch is in place and is being used t o m a i n t a i n a r c h l e n g t h . T h i s p a t i e n t h a s t h e s k e l e t a l contiguration with
close-bites.
(Tracings
in
Fig.
that is associated
5.)
Some respond to mvofunctional therapy.” Since the vast majority of these patients are children in the transitional dentition stage, it is conceivable that the rate of eruption of the anterior teeth had slowed down temporarily (Fig. 2). Eruption does not occur at a constant rate and may take place in spurts. Consequently, these subjects may be referred to as having “transitional” or “pseudo” open-bites. The group with the craniofacial malformations have varied characteristics which continue on into maturity.I(’ These subjects usuallv have slightly longer total anterior face height. The palatal plane map br tipped upward anteriorly, so that the upper anterior face height is shorter and the lower anterior face height is longer. The posterior face height is usually shorter t,han the norm.
PI L c
Class I
Class1
Normal d
ClassII
@
Normal Open Bite - - -
0
Fig. 3. A, Tracing of a subject with a dentofacial anterior open-bite. B, Average polygon pattern
(S-N-Me-Go-S]
pattern
of
normal
showing
control
occlusal
matched
and
against
palatal average
planes. of
Class
Normal II
controls.
open-bite
C,
Average
subiects.
Note
differences in S-GO, gonial angle, mandibular plane, face height, and cant of the occlusal planes and of the palatal plane. Superimposition along S-N registered at S.
The ratio of the upper anterior fact height to the lower anterior fact> height serves as one of the diagnostic criteria. (The normal IJFII/LFH ratio is 0.800, open-bite < 0.700 and closed bite > 0.900.) An obtuse genial angle is seen with a steep, notched mandibular plane. In addition, there are two distinct occlusal planes. The maxillary occlusal plant may bc tipped upward ankriorly in conjunction with the palatal plane, while the mantlibular ocelusal plam is canted downward. Our studies indicated that dcntoalvcolar height is ctf I( trsf normal except for the mandibular molar, whkh is significantly shorter.:’ Thr
5
16
Fig.
Nah own
4.
treatment taken
A by
and a
at 4-month
B,
Patient
trained
with
therapist
skeletal for
a
anterior period
of
open-bite 6
who
months.
received
myofunctional
Cephalometric
films
were
intervals. C, Patient’s dentition 2 years later. Note persistence of open-
bite. (UFH/LFH is 0.684.)
distance from the SN plal~c t o thtb maxillary incisor is shorter, would br in thosc~ suh,jc& in whom the ]‘>lIiItaI plane is tipptd UJ) (Fig. :j). All open-hitc patients dcmonstratc t.ongue tlrruding during swallowing. This is the way that the subjcet crctitcs ~JJ oral seal, which is necessary for tleglutition. In some, particularly those with skeletal v;triations, this map be a necessity. It is important to cdonsitlcr the size of the tongue ant1 the available space i n the oropharyns. The s i z e o f the oropharyngeal space influonc~cs t h e posturing of the tongue as it ptdains to respiration and ckyqlutit,ion.” I n a d d i t i o n , thcrca a r c suhtlr ~~(~~~~‘(~ttlusc~~lar cliffcrrnces bct,wcen the t w o major catcgorics of open-bite. Some cbf tht> patients in that c~rirniofaC.ial malformat i o n s g r o u p , w h o ;lre pcrnicaious tollgut> thrust,rrs, lack iI ga,g r&:x.‘“* ‘:I IJl t&s of stercognosis thcscl p a t i e n t s are unable t o icleutify diffrrrntly s h a p e d objects with the tongue, and some ot’ thc3tr subject,s c a n n o t eserut,e alternate repetitive movements with the tongue (tlvsclieclokokirl~~sis) .’ I These conditions arc probably due to deficient proprioc.t~l)t,ivr mechanisms.‘” E’inally, the exact WS
eXptY%d,
Anterior open-bite 517
Fig. 5. A, The skeletal configuration that is typical of a subject with a deep-bite. Note that this patient has a transitional open-bite. (UFH/LFH is 1.017.) B, Same patient 2 years later, after treatment of Class II malocclusion with cervical EOF. Note tendency to close-bite.
roles of the extrinsic and intrinsic muscles of the tongue and the levators and depressors of the mandible are not known.16 Tongue thrust may contribute to open-bite deformity. This condition is sometimes associated with tactile hypesthesia and disorders of oral motor activity. It has important diagnostic and therapeutic implications. The undeniable conclusion, then, is that open-bites have anatomic and neurologic components.l? Not all of these characteristics are noted in all open-bite patients, but various permutations of some of them are. The most common skeletal deformity is in the angle of the palatal plane to the mandibular plane. It is of paramount importance that open-bite subjects be carefully examined in order to determine the exact location of the deformity and to gain some insight as to the possible cause. Should all open-bites be treated in the same way, regardless of the variety? Can we hope for stability if the cause is not neutralized because it is not understood? Comments on treatment
The treatment of patients with anterior open-bite is difficult and is often unsuccessful. It requires good judgment and skill. Treatment shouhl attempt to correct the skeletal as well as the dental dysplasia. TJnfortunately, the means for accomplishing these ideal goals are not readily available, since we are severely limited in identifying and in eliminating, or diminishing, the causes of these malformations (that is, genetics, growth, neuromuscular, habitual, etc.). Subtelny and Sakuda5 correctly question the feasibility of treating all open-bites. Nearly all patients can be taught to swallow without tongue thrusting on a voluntary or conscious level. However, deglutition has reflex and involuntary
.I i,, J. O?.thod. .Ilrr !, 1 9 i i
5 1 8 Nahounz.
1965
Dec. 13, 1962
---- Mar. 16,
1965
Fig. 6. A, Cephalometric tracing of a patient with skeletal anterior open-bite. B, Tracing of same patient after 18 months of twin arch treatment and 1 year of retention. C, Beforeand after-treatment tracings superimposed on anatomic cranial landmarks. Note favorable growth of posterior face height in addition to maxillary growth.
components which are initiated and executed on a subconscious level.lx Swallowing occurs 1,200 to 1,500 times a day, and the patient is not aware of this activity.l!’ There is no evidence to support the claim of beneficial therapeutic effects of myofunctional therapy in skeletal open-bite patients20-22 (Fig. 4). The diagnosis of a growing child is different from that of an adult. The adult presents us with a fait accompli. There is no hope for improvement without treatment. The child presents us with an unusual challenge to make an educated guess as to the potential for favorable growth. Although generalizations may be made, it is extremely difficult to make precise predictions for the individual patient. Consequently, we are unable to render an accurate assessment of our patient and a valid prognosis. An illustration may serve to emphasize the importance of this concept. A child with the skeletal configuration that is typical of a close-bite will continue to grow as a close-bite patient (Fig. 5). It is unlikely that he will develop a skeletal open-bite. A similar, but opposite, generali-
Anterior open-bite 519 G.
P.
- 7-63 - - - - 6-66
0 Fig. 7. A, Patient with severe open-bite who was treated with vertical elastics. 6, Superimposed
tracings
to
indicate
minimal
closure
of
open-bite.
Craniofacial
malformation
is
unaffected.
zation may be made about an open-bite patient (Fig. 4). However, minor changes in the growth pattern may facilitate treatment, so that a poor prognosis can become a, favorable one. Apparently, growth makes the difference. If we think of the first or second molar as a fulcrum, consider what 1 or 2 mm. of additional posterior face height growth would mean to a patient with an anterior open-bite! Relatively small changes in strategic locations can modify the subject’s position within the spectrum of the deformity (Fig. 6). In a recent publication, Nemeth and Isaacson reported that orthodontically treated patients who exhibited anterior open-bite relapse “showed greater combined sutural and alveolar growth of the maxilla and alveolar growth of the mandible than posterior facial height increase.” This study indicated that some open-bite patients continued to have insufficient vertical growth of the posterior face as the other components continued their normal growth. Conversely, we may assume that, if the trend reverses itself and there is adequate growth in posterior face height, an open-bite may close. This is one area where we can observe structural differences in growing patients who exhibit the anterior open-bite syndrome. However, it should be stressed that this is not the only site of deformation. The patient with a craniofacial malformation should not be treated by elongation of anterior teeth. Dentoalveolar height is finite. Incisors should not be extruded without restraint. Even if the bite were closed, facial improvement would be limited except t.hrough favorable growth or surgical intervention (Fig. 7). It is not surprising that orthodontists would look for and readily accept some method of determining the severity of the overbite-positive or negative. Such an indicator has been suggested by Kim,’ who utilizes a combined measurement of the palatal plane angle to FH and the angle of the AB plane to the mandibular plane. It is referred to as the ODI. Although the use of the palatal
plant as o~c arca of tliscrepunc\- iii opclr-bitts had begun suggestetl previously, wo have not bcci~ su~cssful in applying the 0111. Whei~ tlic 0111 was applied to five a d u l t open-bite suhjccts W~ORC t ratings ;rppcarccl i n WI p u b l i c a t i o n ou the J)&tal JhIl(‘,“’ only one was in the opcwl)itc~ railgt~. Thc~s, in ntl(litiolr to other JMtiPllb, have lctl us to qucstioli 1hc valitlity oi’ this intlic%tor in its prcsrlkt form. There is no short-cut method for assessing skeletal anterior opcln-bites. The sites of the dysplasia vary and all must bc considcrcd. ITnfortunatcly, m o s t efforts have been tlirccted t,oward trcatrntwt of the dentition via mechanothcrapy and myofunctional therapy without c~onsidcration of anatomic liabilities. It is natural for orthodontists to lw c9nccrncd with dental ilS&IWtS of opc’llbitts and to accept cosmetic improvcmcnt as a welcomcl bonus t,o treatment. The fact that the facial, neuromuscular, and yharyngcal components are of usual or greater importance has led us into partnerships with other disciplines. The surgical correction of anterior open-bites is bring refinctl to the point whcrc we must consider this modality as a primary mcthotl ot’ treating this dysplasia, cvcn though t,he results are not cntircly stable. The removal of molars and partial glosscctomy have been rcvivt~d.“:’ These J~rocctlurcs are I~eing iltltll’tl 10 various types of maxillary and mandibular ostcotomy. Time will tell if tllr benefits tha,t accrut’ a r c w o r t h t h e t i m e and effort rspcntled. LKt~rcrtllelcss, we sh0~11d btl acutely awart’ of the fact that, we art’ treating symptoms. This is the reason that treatment is often haphazard alld unsuccessful. Summary
and
conclusion
3. A detailed description of the open-bite subject, with a craniofacial malformation is given in order to diffrrentiate this malocclusion from the acquired open-bite. 2. The reasons for the failure of various modes of treatment ilr(’ presented in the light of neuromuscular and anatomic variations that, are inhcrcnt in these patients. 3. The importance of growth in strategic: sites is emphasized as a determining factor in successful treatment. The author gratefully acknowledges the suggestions of Kicbolns A. DiSalro and Sidney I,. Horowitz in the preparation of this article. REFERENCES
I. Semetb, R. B., and Isaxcson H. J.: Vwtical anterior relapse, Ah<. J. ORTHOI). 65: 565-585, 1974. 2. Kim, Young H.: Overbite tlept,h indicntor, A&f. J. ORTHOD. 65: 586.611, 1974. 3. Naboum, 11. I., Horowitz, H. I,., and Benedicto, E.: Varirt.ies of anterior open-bite, A&z. J. ORTHW. 61: 486.492,
1972.
4. Hellnmn, M.: Open bite, INT. J. OKTHOI).
8: 421, 1931. 5. Subtclny, J. I)., and Subtelny, .J. I).: Oral habits; studiw in form, function, ant1 therapy, Angle Orthod. 43: 347-383, 1973. 6. Subtelny, .J. U., and Sakuda, M.: Open-bite; diagnosis and treatment, A&f. J. (~RTIIOI). 50: 337-358, 1964. i. Iforowitz, S. L., and Hixon, E. H.: The nature of orthodontic diagnosis, St. Louis, 1966, The (1. V. Mosby Company.
Anterior
open-bite
521
8. Worms, F. W., Meskin, L. H., and Isaacson, R. J.: Open-bite, AX J. ORTHOD. 59: 589-595, 1971. 9. Staub, W. : Malfunction of the tongue, AM. J. ORTHOD. 46: 404-424, 1960. 10. Nahoum, H. I.: Vertical proportions and the palatal plane in anterior open-bite, AM. J. ORTHOD. 59: 273-282,1971. 11. Linder-Aronson, Sten : Adenoids : Their effect on mode of breathing and nasal air flow and their relationship to characteristics of facial skeleton and the dentition, Aeta Otolaryngol; Supp 265, 1970. 12. Whitman, C. L.: Habits can mean trouble, AM. J. ORTHOD. 37: 647, 1951. 13. McDonald, E. T., and Aungst, L. F.: Studies in oral sensorimotor function. In Bosma, J. F.: Symposium on oral sensation and perception, Springfield, Ill., 1967, Charles C Thomas Publisher, Chap. 11. 14. Bloomer, H. Harlan: Oral manifestation of dysdiadokokinesia with oral asteriognosia. la Bosma, J. F.: Symposium of oral sensation and perception, Springfield, Ill., 1967, Charles C. Thomas Publisher, chap. 19. 15. Henkin, R. I.: Sensory mechanism in familial dysautonomia. In Bosma, J. F.: Symposium on oral sensation and perception, Springfield, Ill., 1967, Charles C Thomas Publisher chap. 20. 16. Graber, T. M.: “The three M’s”-Muscles, malformation, and malocclusion, AM. J. ORTHOD. 49: 418-450, 1963. 17. Henkin, R. I., Christiansen, R. L., and Bosma, J. F.: Facial hypoplasia, growth retardation, impairment of oral sensation: A new syndrome, Second Symposium on Oral Sensation and Perception, Springfield, Ill., 1970, Charles C. Thomas Publisher. 18. Graber, T. M.: Orthodontics: Principles and practice, Philadelphia, 1972, W. B. Saunders Company, chap. 6. 19. Kydd, W. L., and Neff, C. W.: Frequency of deglutition of tongue thrusters compared to a sample population of normal swallowers, J. Dent. Res. 43: 363, 1964. 20. Barrer, II.: Limitations in orthodontics, AM. J. ORTHOD. 65: 613-625, 1974. 21. Tully, W. J.: A critical appraisal of tongue thrusting, AM. J. ORTHOD. 55: 640-649, 1969. 22. Speidel, T. Michael, Isaacson, R. J., and Worms, F. W.: Tongue thrust therapy and anterior dental open-bite, AM. J. O RTHOD. 62: 287-295, 1972. 23. Lines, P. A., and Steinhauser, E. W.: Diagnosis and treatment planning in surgical orthodontictherapy, AM. J. O RTHOD. 66: 378-379, 1974.
New Yorlc, N. Y.
0
n e of the most difficult aspects of diagnosis lies in making a decision regarding the nature of the condition or syndrome under consideration. This conceptual difficulty is illustrated by some recent articles on the subject of anterior open-bite. I, 2 In these reports, “open-bite” is considered an adequate definition of the condition, and little consideration is given to the fact that this term includes several skeletal variants that all have in common a ?zegative incisal overbite.3 The purpose of this essay is to present a cephalometric assessment of various types of anterior open-bite malocclusion and to review some concepts that may help in understanding the limitations in the treatment of such patients. Many of these concepts are not new and have been ably presented by Hellman Subtelny and associates,5* 6 and Horowitz and Hixon.7 It should be emphasized that cephalometrics, at best, is a descriptive technique which helps to define or classify a condition but does not necessarily provide us with the insight for the successful treatment of an anomaly. Review of the literature
Anterior open-bite has been grouped into two broad categories. The first category consists of the acquired or dental open-bites which do not show any distinguishing craniofacial malformations. The second group consists of patients with craniofacial dysplasia in addition to the open-bite. The dental open-bites are believed to result from obstructed eruption of the anterior teeth (Fig. 1). Many of these show spontaneous remissions, and 75 to 80 per cent have marked improvement without any form of treatment.8 Presented before the Kortheastern Society of Orthodontists, Nov. 8, 1974. *Associate Professor of Dentistry, Columbia University School of Dental and Oral Surgery.
513
Fig. 1.
The dentition of a patient with a habitual anterior open-bite which was probably
initiated by thumb-sucking. Note the asymmetric opening caused by placing the thumb on the right side. This type of open-bite responds to habit therapy.
Fig. 2.
A,
The dentition of a patient with a “transitional” open-bite with a Class II
malocclusion and mild anterior crowding. B, The dentition of the same patient after treatment with cervical extraoral force. A lower lingual arch is in place and is being used t o m a i n t a i n a r c h l e n g t h . T h i s p a t i e n t h a s t h e s k e l e t a l contiguration with
close-bites.
(Tracings
in
Fig.
that is associated
5.)
Some respond to mvofunctional therapy.” Since the vast majority of these patients are children in the transitional dentition stage, it is conceivable that the rate of eruption of the anterior teeth had slowed down temporarily (Fig. 2). Eruption does not occur at a constant rate and may take place in spurts. Consequently, these subjects may be referred to as having “transitional” or “pseudo” open-bites. The group with the craniofacial malformations have varied characteristics which continue on into maturity.I(’ These subjects usuallv have slightly longer total anterior face height. The palatal plane map br tipped upward anteriorly, so that the upper anterior face height is shorter and the lower anterior face height is longer. The posterior face height is usually shorter t,han the norm.
PI L c
Class I
Class1
Normal d
ClassII
@
Normal Open Bite - - -
0
Fig. 3. A, Tracing of a subject with a dentofacial anterior open-bite. B, Average polygon pattern
(S-N-Me-Go-S]
pattern
of
normal
showing
control
occlusal
matched
and
against
palatal average
planes. of
Class
Normal II
controls.
open-bite
C,
Average
subiects.
Note
differences in S-GO, gonial angle, mandibular plane, face height, and cant of the occlusal planes and of the palatal plane. Superimposition along S-N registered at S.
The ratio of the upper anterior fact height to the lower anterior fact> height serves as one of the diagnostic criteria. (The normal IJFII/LFH ratio is 0.800, open-bite < 0.700 and closed bite > 0.900.) An obtuse genial angle is seen with a steep, notched mandibular plane. In addition, there are two distinct occlusal planes. The maxillary occlusal plant may bc tipped upward ankriorly in conjunction with the palatal plane, while the mantlibular ocelusal plam is canted downward. Our studies indicated that dcntoalvcolar height is ctf I( trsf normal except for the mandibular molar, whkh is significantly shorter.:’ Thr
5
16
Fig.
Nah own
4.
treatment taken
A by
and a
at 4-month
B,
Patient
trained
with
therapist
skeletal for
a
anterior period
of
open-bite 6
who
months.
received
myofunctional
Cephalometric
films
were
intervals. C, Patient’s dentition 2 years later. Note persistence of open-
bite. (UFH/LFH is 0.684.)
distance from the SN plal~c t o thtb maxillary incisor is shorter, would br in thosc~ suh,jc& in whom the ]‘>lIiItaI plane is tipptd UJ) (Fig. :j). All open-hitc patients dcmonstratc t.ongue tlrruding during swallowing. This is the way that the subjcet crctitcs ~JJ oral seal, which is necessary for tleglutition. In some, particularly those with skeletal v;triations, this map be a necessity. It is important to cdonsitlcr the size of the tongue ant1 the available space i n the oropharyns. The s i z e o f the oropharyngeal space influonc~cs t h e posturing of the tongue as it ptdains to respiration and ckyqlutit,ion.” I n a d d i t i o n , thcrca a r c suhtlr ~~(~~~~‘(~ttlusc~~lar cliffcrrnces bct,wcen the t w o major catcgorics of open-bite. Some cbf tht> patients in that c~rirniofaC.ial malformat i o n s g r o u p , w h o ;lre pcrnicaious tollgut> thrust,rrs, lack iI ga,g r&:x.‘“* ‘:I IJl t&s of stercognosis thcscl p a t i e n t s are unable t o icleutify diffrrrntly s h a p e d objects with the tongue, and some ot’ thc3tr subject,s c a n n o t eserut,e alternate repetitive movements with the tongue (tlvsclieclokokirl~~sis) .’ I These conditions arc probably due to deficient proprioc.t~l)t,ivr mechanisms.‘” E’inally, the exact WS
eXptY%d,
Anterior open-bite 517
Fig. 5. A, The skeletal configuration that is typical of a subject with a deep-bite. Note that this patient has a transitional open-bite. (UFH/LFH is 1.017.) B, Same patient 2 years later, after treatment of Class II malocclusion with cervical EOF. Note tendency to close-bite.
roles of the extrinsic and intrinsic muscles of the tongue and the levators and depressors of the mandible are not known.16 Tongue thrust may contribute to open-bite deformity. This condition is sometimes associated with tactile hypesthesia and disorders of oral motor activity. It has important diagnostic and therapeutic implications. The undeniable conclusion, then, is that open-bites have anatomic and neurologic components.l? Not all of these characteristics are noted in all open-bite patients, but various permutations of some of them are. The most common skeletal deformity is in the angle of the palatal plane to the mandibular plane. It is of paramount importance that open-bite subjects be carefully examined in order to determine the exact location of the deformity and to gain some insight as to the possible cause. Should all open-bites be treated in the same way, regardless of the variety? Can we hope for stability if the cause is not neutralized because it is not understood? Comments on treatment
The treatment of patients with anterior open-bite is difficult and is often unsuccessful. It requires good judgment and skill. Treatment shouhl attempt to correct the skeletal as well as the dental dysplasia. TJnfortunately, the means for accomplishing these ideal goals are not readily available, since we are severely limited in identifying and in eliminating, or diminishing, the causes of these malformations (that is, genetics, growth, neuromuscular, habitual, etc.). Subtelny and Sakuda5 correctly question the feasibility of treating all open-bites. Nearly all patients can be taught to swallow without tongue thrusting on a voluntary or conscious level. However, deglutition has reflex and involuntary
.I i,, J. O?.thod. .Ilrr !, 1 9 i i
5 1 8 Nahounz.
1965
Dec. 13, 1962
---- Mar. 16,
1965
Fig. 6. A, Cephalometric tracing of a patient with skeletal anterior open-bite. B, Tracing of same patient after 18 months of twin arch treatment and 1 year of retention. C, Beforeand after-treatment tracings superimposed on anatomic cranial landmarks. Note favorable growth of posterior face height in addition to maxillary growth.
components which are initiated and executed on a subconscious level.lx Swallowing occurs 1,200 to 1,500 times a day, and the patient is not aware of this activity.l!’ There is no evidence to support the claim of beneficial therapeutic effects of myofunctional therapy in skeletal open-bite patients20-22 (Fig. 4). The diagnosis of a growing child is different from that of an adult. The adult presents us with a fait accompli. There is no hope for improvement without treatment. The child presents us with an unusual challenge to make an educated guess as to the potential for favorable growth. Although generalizations may be made, it is extremely difficult to make precise predictions for the individual patient. Consequently, we are unable to render an accurate assessment of our patient and a valid prognosis. An illustration may serve to emphasize the importance of this concept. A child with the skeletal configuration that is typical of a close-bite will continue to grow as a close-bite patient (Fig. 5). It is unlikely that he will develop a skeletal open-bite. A similar, but opposite, generali-
Anterior open-bite 519 G.
P.
- 7-63 - - - - 6-66
0 Fig. 7. A, Patient with severe open-bite who was treated with vertical elastics. 6, Superimposed
tracings
to
indicate
minimal
closure
of
open-bite.
Craniofacial
malformation
is
unaffected.
zation may be made about an open-bite patient (Fig. 4). However, minor changes in the growth pattern may facilitate treatment, so that a poor prognosis can become a, favorable one. Apparently, growth makes the difference. If we think of the first or second molar as a fulcrum, consider what 1 or 2 mm. of additional posterior face height growth would mean to a patient with an anterior open-bite! Relatively small changes in strategic locations can modify the subject’s position within the spectrum of the deformity (Fig. 6). In a recent publication, Nemeth and Isaacson reported that orthodontically treated patients who exhibited anterior open-bite relapse “showed greater combined sutural and alveolar growth of the maxilla and alveolar growth of the mandible than posterior facial height increase.” This study indicated that some open-bite patients continued to have insufficient vertical growth of the posterior face as the other components continued their normal growth. Conversely, we may assume that, if the trend reverses itself and there is adequate growth in posterior face height, an open-bite may close. This is one area where we can observe structural differences in growing patients who exhibit the anterior open-bite syndrome. However, it should be stressed that this is not the only site of deformation. The patient with a craniofacial malformation should not be treated by elongation of anterior teeth. Dentoalveolar height is finite. Incisors should not be extruded without restraint. Even if the bite were closed, facial improvement would be limited except t.hrough favorable growth or surgical intervention (Fig. 7). It is not surprising that orthodontists would look for and readily accept some method of determining the severity of the overbite-positive or negative. Such an indicator has been suggested by Kim,’ who utilizes a combined measurement of the palatal plane angle to FH and the angle of the AB plane to the mandibular plane. It is referred to as the ODI. Although the use of the palatal
plant as o~c arca of tliscrepunc\- iii opclr-bitts had begun suggestetl previously, wo have not bcci~ su~cssful in applying the 0111. Whei~ tlic 0111 was applied to five a d u l t open-bite suhjccts W~ORC t ratings ;rppcarccl i n WI p u b l i c a t i o n ou the J)&tal JhIl(‘,“’ only one was in the opcwl)itc~ railgt~. Thc~s, in ntl(litiolr to other JMtiPllb, have lctl us to qucstioli 1hc valitlity oi’ this intlic%tor in its prcsrlkt form. There is no short-cut method for assessing skeletal anterior opcln-bites. The sites of the dysplasia vary and all must bc considcrcd. ITnfortunatcly, m o s t efforts have been tlirccted t,oward trcatrntwt of the dentition via mechanothcrapy and myofunctional therapy without c~onsidcration of anatomic liabilities. It is natural for orthodontists to lw c9nccrncd with dental ilS&IWtS of opc’llbitts and to accept cosmetic improvcmcnt as a welcomcl bonus t,o treatment. The fact that the facial, neuromuscular, and yharyngcal components are of usual or greater importance has led us into partnerships with other disciplines. The surgical correction of anterior open-bites is bring refinctl to the point whcrc we must consider this modality as a primary mcthotl ot’ treating this dysplasia, cvcn though t,he results are not cntircly stable. The removal of molars and partial glosscctomy have been rcvivt~d.“:’ These J~rocctlurcs are I~eing iltltll’tl 10 various types of maxillary and mandibular ostcotomy. Time will tell if tllr benefits tha,t accrut’ a r c w o r t h t h e t i m e and effort rspcntled. LKt~rcrtllelcss, we sh0~11d btl acutely awart’ of the fact that, we art’ treating symptoms. This is the reason that treatment is often haphazard alld unsuccessful. Summary
and
conclusion
3. A detailed description of the open-bite subject, with a craniofacial malformation is given in order to diffrrentiate this malocclusion from the acquired open-bite. 2. The reasons for the failure of various modes of treatment ilr(’ presented in the light of neuromuscular and anatomic variations that, are inhcrcnt in these patients. 3. The importance of growth in strategic: sites is emphasized as a determining factor in successful treatment. The author gratefully acknowledges the suggestions of Kicbolns A. DiSalro and Sidney I,. Horowitz in the preparation of this article. REFERENCES
I. Semetb, R. B., and Isaxcson H. J.: Vwtical anterior relapse, Ah<. J. ORTHOI). 65: 565-585, 1974. 2. Kim, Young H.: Overbite tlept,h indicntor, A&f. J. ORTHOD. 65: 586.611, 1974. 3. Naboum, 11. I., Horowitz, H. I,., and Benedicto, E.: Varirt.ies of anterior open-bite, A&z. J. ORTHW. 61: 486.492,
1972.
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open-bite
521
8. Worms, F. W., Meskin, L. H., and Isaacson, R. J.: Open-bite, AX J. ORTHOD. 59: 589-595, 1971. 9. Staub, W. : Malfunction of the tongue, AM. J. ORTHOD. 46: 404-424, 1960. 10. Nahoum, H. I.: Vertical proportions and the palatal plane in anterior open-bite, AM. J. ORTHOD. 59: 273-282,1971. 11. Linder-Aronson, Sten : Adenoids : Their effect on mode of breathing and nasal air flow and their relationship to characteristics of facial skeleton and the dentition, Aeta Otolaryngol; Supp 265, 1970. 12. Whitman, C. L.: Habits can mean trouble, AM. J. ORTHOD. 37: 647, 1951. 13. McDonald, E. T., and Aungst, L. F.: Studies in oral sensorimotor function. In Bosma, J. F.: Symposium on oral sensation and perception, Springfield, Ill., 1967, Charles C Thomas Publisher, Chap. 11. 14. Bloomer, H. Harlan: Oral manifestation of dysdiadokokinesia with oral asteriognosia. la Bosma, J. F.: Symposium of oral sensation and perception, Springfield, Ill., 1967, Charles C. Thomas Publisher, chap. 19. 15. Henkin, R. I.: Sensory mechanism in familial dysautonomia. In Bosma, J. F.: Symposium on oral sensation and perception, Springfield, Ill., 1967, Charles C Thomas Publisher chap. 20. 16. Graber, T. M.: “The three M’s”-Muscles, malformation, and malocclusion, AM. J. ORTHOD. 49: 418-450, 1963. 17. Henkin, R. I., Christiansen, R. L., and Bosma, J. F.: Facial hypoplasia, growth retardation, impairment of oral sensation: A new syndrome, Second Symposium on Oral Sensation and Perception, Springfield, Ill., 1970, Charles C. Thomas Publisher. 18. Graber, T. M.: Orthodontics: Principles and practice, Philadelphia, 1972, W. B. Saunders Company, chap. 6. 19. Kydd, W. L., and Neff, C. W.: Frequency of deglutition of tongue thrusters compared to a sample population of normal swallowers, J. Dent. Res. 43: 363, 1964. 20. Barrer, II.: Limitations in orthodontics, AM. J. ORTHOD. 65: 613-625, 1974. 21. Tully, W. J.: A critical appraisal of tongue thrusting, AM. J. ORTHOD. 55: 640-649, 1969. 22. Speidel, T. Michael, Isaacson, R. J., and Worms, F. W.: Tongue thrust therapy and anterior dental open-bite, AM. J. O RTHOD. 62: 287-295, 1972. 23. Lines, P. A., and Steinhauser, E. W.: Diagnosis and treatment planning in surgical orthodontictherapy, AM. J. O RTHOD. 66: 378-379, 1974.