CHAPTER 17

Mandibular Growth Anomalies in Acromegaly

When lecturing on the subject of mandibular growth anomalies I have often expressed the opinion that growth hormone overproduction in an adenoma of the pituitary gland will stimulate the condylar growth factors M or L, or both. So, in acromegaly, bilateral mandibular growth anomalies equal to bilateral symmetrical H.E., H.H. or hybrid forms will be produced. This was, in my opinion, the reason why in acromegaly only the mandible can in­crease in length and mass producing a rather typical an­temandibulism type while no other bones of the human skeleton will become longer as they do not contain any­thing similar to our assumed condylar growth factors.

As we did not know enough about the reaction of the various bones to the overproduction of human growth hormone, I asked two students to find the relevant infor­mation on the available number of patients with acrome­galy. They found 31 patients with acromegaly, proven by overproduction of human growth hormone, in their inves­tigation. A. Kunzler (1988) had the task of obtaining as much information about the influence of acromegaly on the viscerocranium. B. Degiacomi's ( 1991) duty was to fmd out what kind of changes in the neurocranium accompany acromegaly. Both doctorate theses are very interesting.

For the subject of mandibular growth anomalies, the findings of the influence of the growth hormone on the viscerocranium is of practical interest only, particularly its influence on the mandible. Kunzler compared the re­sults with those found in a group of 25 control subjects. There were only 6 patients out of 31 proven acromegaly cases who developed an antemandibulism and in all 6 cases this was symmetrical. They had come to our clinic for corrective surgery. He concludes that "There are dis­tinct alterations in the mandible, in the whole length of the ascending ramus as well as in the horizontal ramus, in particular in the chin prominence". He expresses the opinion that both types of condylar hyperactivity (H.E. and H.H.) are also found in acromegaly. He also states that "aside from these form anomalies there are also pathological mandibular configurations which cannot be attributed to these two growth anomalies".

When I tried to evaluate these cases of acromegaly-in­duced mandibular growth anomalies I found that radio­logically they may look like a bilateral symmetrical H.E. or H.H. form but they lack the corresponding condylar forms.

The fact that only about 20% of acromegaly cases pro­duce real antemandibulism and that these are of a H.E. or a H.H. type but without the corresponding condylar forms, leads me to the conclusion that in acromegaly, the growth stimulation is not the same as in the pure condy­lar hyperactivity cases. Three cases will demonstrate this.

If this whole philosophy of the existence of condylar growth regulators is of any value in the understanding of various typical mandibular growth anomaly types, or even accepted as a fact, then we should not be surprised to find one or other of these typical anomalies also devel­oping in a case of true acromegaly. This has been report­ed by H. Muller in 1979,in a case where the patient devel­oped acromegaly and simultaneous mandibular asym­metry at the age of 23. According to his illustrations there was no doubt about the acromegaly. But I cannot see from the radiograph whether it was a H.E., H. H. or a hy­brid type of mandibular asymmetry. From the patient's face I would diagnose a hybrid type of condylar hyperac­tivity as being the cause, as there is clear deviation of the mandible to the other side and clear increase in facial vertical height and flatness on the affected side.

H. Muller discussed the possibility of the hormonal influence for the simultaneous development of the two growth anomalies, acromegaly and the unilateral condy­lar hyperactivity, then still called "condylar hyperplasia''. He states that "an aetiological relationship between the hormonal dysfunction and condylar hyperplasia is not proven". According to my experience and knowledge, the two different mandibular growth anomalies cannot have the same hormonal cause, for three reasons. In the great number of acromegaly cases this anomalous combina­tion should occur more often. H. Muller's case is the only one so far reported. Secondly, those mandibular anoma­lies that I have seen as a result of acromegaly do not fit into the anomaly types found in condylar hyperactivity. Thirdly, condylar growth regulator hyperactivity can start at any time from 5 years of age up to 50 years or probably even more. I would therefore classify this case as a result of a very rare occurrence of having these two different growth anomalies in one mandible. Even in the 66 cases ofM.Rushton (195l),he does not mention a case of simultaneous appearance of "condylar hyperplasia'' and acromegaly.

H. L. Obwegeser, Mandibular Growth Anomalies© Springer-Verlag Berlin Heidelberg 2001

340 CHAPTER 17 Mandibular Growth Anomalies in Acromegaly

Acromegaly of Bilateral Pseudo-H.E., Slender Type (Fig. 76)

Sex and Age. Male, 56 years of age.

Aetiology and History. Some years previously the pa­tient had realized that his facial appearance had changed. He did not remember how long back. When he went to see his general medical practitioner he was re­ferred to an endocrinologist who diagnosed a surplus of growth hormone production. Therefore, he was referred to a neurosurgeon, who operated on his pituitary gland tumour. As he had a full upper denture and the remain­ing lower teeth were placed in front of it, his dentist had informed him that without a set back of the mandible there was not much chance of a better-functioning upper denture. He now sought more detailed informa­tion about what ought to be done to his jaws.

Clinical Findings. The patient is of rather large build. His head is broad and rather round (Fig. 76a, b). His lower lip protrudes, but not his chin. The soft tissues are very thick. It is impossible to gain an idea of the shape of the angle areas. Mouth opening is normal.

The lower front teeth protrude with lots of space between them. There is no occlusion with the full upper denture (Fig. 76c-e). The tongue is very large. The max­illa is edentulous with a badly-fitting full denture.

Radiographs. The panoramic view (Fig. 76f) reveals a mandible of unusual shape. Both sides are absolutely straight, from the condyles to the chin. On the left side there is no angle at all and on the right side just a very rudimentary one. Both hemimandibles are rather slim, with most of the cheek teeth missing. The condyle looks just like a cherry sitting on top of a thin straight stem.

The TMJ tomograms were regrettably missing. The lateral cephalogram (Fig. 76g) shows the very

classical facial skeletal changes typical of acromegaly including a prominent forehead due to extensive pneu­matization of the frontal sinuses. The mastoids are overpneumatized and the sella turcica is very large. The ethmoid cells also look expanded. The base of the max-

Fig. 76a-e. Acromegaly of bilateral pseudo-H.E., slender type. a, b The p atient's appearance does not permit a ny conclusion regarding the shape of its skeletal background. c-e The full upper denture has no occlusion with the remaining mandibular teeth. The latter are protruded with l arge interdental spaces due to a macroglossia

17 Mandibular Growth Anomalies in Acromegaly 341

Fig. 76f, g. Acromegaly with bilateral pseudo-H.E., slender type. f, g The panoramic view as well as the lateral cephalogram disclose a slim and straight mandible with thin necks and rounded condyles

ilia is on the short side and was too far back (retromax­illism). The mandible was straight like a stick, from the condyles to the chin. The chin itself does not protrude very much, but the remaining front teeth are tilted for­wards.

Provisional Diagnosis. Acromegaly with an elongated mandible of the bilateral H.E., slender type, and retro­maxillism.

Treatment Plan. In order to create a normal intermaxil­lary relationship and a favourable situation for a subse­quent denture, the following surgery has to be carried out: advancement of the maxilla by aLe FortI-type os­teotomy and a set back of the mandible by bilateral sag­ittal splitting of the rami with the lateral osteotomy ex­tending to the angle, in order to rotate the body into a horizontal position. In addition, the protruded anterior alveolus with its teeth should be brought into an upright position. In order to prevent relapse of the repositioned alveolar segment, the size of the tongue must be re­duced.

Actual Treatment. The patient refused any surgery of the type suggested.

Discussion and Conclusion. In this case of acromegaly, the mandible had a very similar shape to that observed in cases of severe bilateral H.E., slender type. In the lat­ter case one would not expect such very round medium­sized condyles but rather condyles of the same width as their necks. It is interesting to note that the mandible

does not seem to have gained much in length, with this change mainly through the increase in the angulation. The enlarged tongue had gained sufficient space by pushing the lower teeth forward. Because of this it would be essential to reduce the size of the tongue be­fore the protruded lower alveolus was repositioned, in addition to the set back and upward rotation of the mandible. I have learned this through experience gained in some cases which led me to the following con­clusion: "The active cause of a facial skeletal anomaly is stronger than screws and plates. Plates and screws can­not prevent a relapse if the cause of the anomaly is still active" (Principle No. 31).

This case gives reason enough to especially mention that the external appearance of an antemandibulism case does not always permit conclusions regarding its skeletal background type. The patient had a very round face and a rather small negative overjet and yet both hemimandibles were straight like sticks. When we look at paintings from the various ancient members of the famous Habsburg family we generally see two different facial types of their antemandibulism. In one type they have a very slim long face with a pointed chin. In these individuals we would expect a similar type of mandible as in this case. But there is also the other type of the Habsburg jaw with a round face. But since we do not have any radiographs of these famous antemandibulism cases we cannot know the shape of the skeletal structure of their faces. This case proves, the appearance does not permit one to make a correct diagnosis of the shape of the mandible without radiographs.

342 CHAPTER 17 Mandibular Growth Anomalies in Acromegaly

Acromegaly of Bilateral H.E., Non-Slender Type (Fig. 77)

Sex and Age. Male, 50 years of age.

Aetiology and History. When the patient was 44 years old he was referred to the Department of Endocrinolo­gy in a very large governmental hospital because of his acromegaloid appearance. No such abnormality in growth hormone values was found. Because of this re­sult, no therapy seemed indicated. He himself had never realized that his head, hands and feet had become larg­er. His dentist had now sent him for improvement of his intermaxillary relationship for prosthetic reasons. We sent him to the Department of Endocrinology at the University Hospital of Zurich. Again the growth hor­mone values were found to be normal at this very com­petent second institution. Thereafter, a mandibular push back operation was performed using the bilateral sagittal splitting procedure on the rami. A good inter­maxillary relationship was achieved and 4 months later the patient was provided with prostheses. Two years lat­er, at a routine follow up, the mandible seemed to have moved forward by 1-2 mm and 4 years after his man­dibular set back operation, his tongue was found to be larger and his lower teeth protruded with larger inter­dental spaces. His fingers seemed thicker and his man­dible had come forward by 3-4 mm. He was again sent for endocrinological screening. Once more the result was negative as far as a growth hormone abnormality was concerned and 4 years later, i.e. 8 years after the sur­gery on his protruding mandible, the same endocrinol­ogy department now found proof of an active acrome­galy, but not to such a degree that neurosurgery was in­dicated. The patient received medication and his inter­maxillary relationship was improved by advancement of the edentulous maxilla.

Clinical Findings. The patient presented all the classic facial signs of acromegaly (Figs. 77a,b ). His middle third seemed very flat while the very protrusive mandible seemed broad with rather stretched angles. The chin was rounded and the mouth movement normal. The tooth situation was very poor. The first bicuspids, ca­nines and anterior teeth were the only teeth in the man­dible. The cheek teeth were missing and also a few of those in the maxilla. There was no occlusion whatsoev­er and a negative overjet of 14 mm.

Radiographs. The panoramic view (Fig. 77c) showed an almost symmetrical, strong mandible with condyles and their necks of rather large size and shape and there were also rather unusually long ascending rami with stretched angles, more so on the left than the right. The mandibular body on both sides seemed very long and high. The midline of the lower front teeth and the sym-

physis was deviated to the left side by about 4 mm. The mandibular canals ran at a normal distance from the lower border on both sides. The right body was remark­ably higher than the left which was also higher than normal, considering the fact that it was edentulous. The trabecular structure of the mandibular bone was rather coarse.

Measuring the tracing of this radiograph was only partially possible as parts of the two condyles were not on the radiograph. The length of the trunks differed by 7 mm, in favour of the right and the horizontal rami dif­fered by 3 mm in favour of the left side. The most strik­ing difference was found in the height of the horizontal rami, the right being 10 mm higher (deeper) in the mo­lar region than the left. Also, the angles differed quite a bit, the left, at 142° being 1 oo larger than the right. There was nothing to signify any of the condylar hyperactivity abnormalities.

The TM] tomograms (Fig. 77d,e) show rather large condyles with a partially flattened surface. The articular eminences are flattened and sclerosed. The right condy­lar neck seems a little elongated but of normal thickness while the left seems thicker and its condyle a little larg­er than normal.

The p.a. projection with the mandible open showed nothing remarkable other than a very large mandible which deviated a little to the left.

The lateral cephalogram (Fig. 77f) shows the typical acromegalic facial skeleton with severe retromaxillism. The mandible is large and had almost no angles. Also, the supraorbital rims protrude and the nose is very large with a drooping tip. The sella turcica is not clearly defined.

Provisional Diagnosis. Acromegaly with bilateral H.E., non-slender type, deformities with some additional asymmetries of the various parts of the mandible, and retromaxillism.

Treatment Plan. Anterior repositioning of the maxilla and retropositioning of the mandible utilizing a Le Fort 1-type osteotomy and bilateral sagittal splitting of the rami.

Actual Treatment. The surgery was carried out by a trainee according to the treatment plan.

Discussion and Conclusion. Within the scope of this book, it is the abnormal growth of the mandible which is the main interest. Naturally, it would also be very interesting to know how, in acromegaly, the various

17 Mandibular Growth Anomalies in Acromegaly 343

Fig. 77a- f. Acromegaly with bilateral H. E., non-slender type. a, b The patient's appearance is very typical of acromegaly. c Panoramic view: very large and strong mandible with stretched angles. d, e The TMJ tomograms disclose rather large and differently shaped con­dyles, on the left with a short thick neck and on the right side with an elongated neck. f The lateral cephaiogram reveals a facial skeleton typical of acromegaly with a large and strong mandible with stretched angles and severe retromaxillism

344 CHAPTER 17 Mandibular Growth Anomalies in Acromegaly

skeletal parts increase in volume. But that has not yet been determined. However, regarding the mandible, I tend to be of the opinion that the hGH (human growth hormone) output might reactivate one, the other, or both condylar growth regulators thus causing them to produce bilaterally either a H.H. type, a H.E. type or a hybrid form anomaly of the mandible. In this case it is the shape of a mandible which is very much akin to a bi­lateral H.E., non-slender type, in a primarily rather strong mandible. Although both hemimandibles and both condyles are not absolutely symmetrical in shape, we still have to accept that, in this case of acromegaly,

Acromegaly with Bilateral Hybrid Type Condyles, but a H.H. Type Mandible (Fig. 78)

Sex and Age. Male, 38 years of age.

Aetiology and History. The patient had noticed the first signs of acromegaly 5 years previously. His pituitary gland adenoma had been removed 1 year ago. He now sought information regarding possible correction of the facial skeletal abnormalities caused by his acromegaly. He claimed that before the acromegaly developed he had had a normal overbite, with no negative overjet.

Clinical Findings. The patient was of average build. He seemed to have a strong general skeleton with broad shoulders. He had a round face (Fig. 78a, b) with anum­ber of clear signs of acromegaly including a strong and protruding mandible, a large nose, enlarged supraorbital rims and zygomatic bones, thick skin and fingers, etc. His broad chin prominence was deviated slightly to the left. The strong mandible had rounded angles and straight lower borders. The mouth movements were normal.

Almost all teeth were present (Fig. 78c). On closure he had a negative overjet of a few millimetres. The low­er teeth midline was shifted to the left by the width of about half a lower incisor. His tongue was rather large.

Radiographs. The panoramic view (Fig. 78d) discloses an extremely strong mandible with both sides almost equal. Both condyles seem to be of the same p.a. diameter as the well elongated necks which are a little on the thick side. On both sides, the ascending rami including the condyles seem clearly longer than normal. They make a strong but not abnormally curved angle with the very high mandib­ular bodies. The incisor midline is shifted to the left by the width of half a lower incisor. The mandibular canals run rather high on both sides, and on both sides the body has a strikingly strong trabeculation. This is not the case in the ramus and condylar regions.

The evaluation of the tracing of the panoramic radio­graph (Fig. 78e) proves that both hemimandibles areal-

the mandible has grown to a shape similar to a bilateral H.E., non -slender type. I do not have any other case with the same anomaly of non-acromegalic origin. I would expect absolute symmetry because the anomaly is cen­trally steered, except if there was already a pre-existing asymmetrical bilateral H.E. before the acromegaly de­veloped. So, what do we really know about these things?

This case also tells us that the clinical signs must al­ways be congruent with the laboratory values. Often enough, it is not the clinical diagnosis which is wrong, but the laboratory findings which were just not sensitive enough to clarify it.

most equal. The horizontal ramus on the right side measures 3 mm more in length than does the left. All other measurable distances are almost equal. The right angle is 8° larger than the left, the latter, at 114° is small­er than the average.

The TM] tomograms (Fig. 78f, g) confirm the exis­tence of rather strong and very long condylar necks and, to some degree, enlarged condyles of abnormal shape. They are not really distinguishable from the neck, as if the enlargement of the condyles has extended into their necks. The right condyle has a small anterior "beak" and the left has on its top a slightly sclerosed, protruding ir­regularity.

The p.a. projection of the mandible in the open posi­tion (Fig. 78h) also demonstrates the very strong man­dible with long ascending rami and large condyles. The maxilla too seems rather high in the vertical dimension. Both ascending rami and condyles have a strikingly coarse bone trabeculation.

The sinus projection in Water's view showed very large frontal sinuses and also rather strong zygomatic bones. The maxilla again looked very high.

The lateral cephalogram (Fig. 78i) confirms the typi­cal acromegalic skeletal picture with a rather short and retrodisplaced maxillary base.

Provisional Diagnosis. Macromandibulism and micro­retromaxillism in a case of acromegaly. The shape of the mandible was almost a bilateral H.H. type but without the necessary inferior convexity of its lower borders. The condylar necks were of the H.E. type with a condyle neck appearance and shape as in mild hybrid form cases.

Treatment Plan. Advancement of the maxilla by 10 mm into a normal overjet position and reduction of the su­praorbital rims and nose.

17 Mandibular Growth Anomalies in Acromegaly 345

Fig. 78a- e. Acromegaly with hybrid type condyles, but a H .H.-type mandible. a, b Typical acromegalic appearance in front and side views with a strong, rounded mandibular shape, no chin deviation. c In occlusion there is a negative o verjet with t he lower m idline a lit­tle over to the left. d The panoramic view d iscloses a very strong mandible equal on both sides, normal curvature of the angles, but long and rather thick cvndylar necks with no clear condyles, very similar to the articular process of the H. E., slender type anomaly. e The measurements of the tracing disclose that both hernimandibles are almost identical

346 CHAPTER 17 Mandibular Growth Anomalies in Acromegaly

Fig. 78f-i. Acromegaly with hybrid type condyles, but a H.H.-type mandible. f, g The TMJ tomograms disclose a neck-condyle situation similar to hybrid forms. h The mandible p.a. projection in the open mouth position reveals a strong mandible with long ascending rami and large condyles. i The lateral cephalogram shows a facial skeleton which is very typical of acromegaly with a strong mandible with­out any inferior convexity of its lower rim and, in addition, a medium degree micro- and retromaxillism

Actual Treatment. The patient did not present himself for surgery.

Discussion. The patient primarily probably had a straight retroface profile which is typical of Greek peo­ple like himself. Therefore, it seems logical not to repo­sition the mandible posteriorly, where it had come from and also in order to prevent the necessity of reducing the large tongue, but to advance the maxilla. So the cor­rection of the occlusal problem would have been very easy.

In this acromegaly case, the mandible seemed ex­tremely strong and with an unusual body height and length of the condylar necks. The very much elongated

and thick condylar necks did not match with the almost rectangular strong mandible. These necks along with their irregularly formed, rather slightly enlarged con­dyles, would normally match those found in a hybrid form with the H.E. very predominant. But then the an­gles of the mandible should be more stretched. So the whole mandible seems to consist of parts which do not fit together according to our knowledge and under­standing of mandibular growth and its misregulation.

Conclusion. In acromegaly, the abnormal growth of the mandible does not follow the pattern of H.E. or H.H. or its hybrid forms.