DOI: 10.1051/odfen/2010402 J Dentofacial Anom Orthod 2010;13:317-333 RODF / EDP Sciences

Posterior mandibular rotations

Julia COHEN-LEVY, Sophie ROZENCWEIG With the gracious participation of Professor Jean DELAIRE

RESUME The morphological particularities of the posteriorly rotated mandible, first described by A. Bjo¨ rk, may correspond to extremely variable clinical situations. We can derive important information by analyzing the forms and proportions of different mandibular entities. This article proposes to illustrate the most frequently encountered situations by describing a number of cases of posterior rotation and by explaining how Delaire’s architectural analysis can be used in clinical practice.

KEYWORDS

Mandible Condyle Posterior rotation Article received: 06-2010 Growth. Accepted for publication: 07-2010 INTRODUCTION

Mandibular rotations are widely known and In Class II division 1 malocclusions, signs frequently used in determining the prognosis of posterior rotation may reflect weak of both vertical and posterior skeletal devia- mandibular growth and, because of it, make tions. The typological characteristics of ‘‘pos- the prognosis for effective functional ther- terior rotation,’’ considering the 7 points that apy dim. But for certain types of Class III Bjo¨rk2,3,4 initially described, orientation and malocclusion similar signs may, on the other shape of the mandibular condyles, shape of hand, accompany a strong growth potential the mandibular symphysis, shape of the lower and minimize the ‘‘real’’ interarch discre- occipital border, orientation of the mandibular pancy. canal, and the proportion of the lower third of According to Moss’s 1968 work, cited by the face, can, nevertheless, refer to very Latrou9, the anatomic mandible is formed different clinical situations. from the juxtaposition of several functional Address for correspondence: COHEN-LEVY, 255 rue Saint-Honore´, 75001 Paris, France. [email protected] 317

Article available at http://www.jdao-journal.org or http://dx.doi.org/10.1051/odfen/2010402 JULIA COHEN-LEVY, SOPHIE ROZENCWEIG, JEAN DELAIRE

entities, a systematic analysis of graph form with the maxillary area which such as the one proposed by represented in the naso-maxillary stage Delaire and Salagnac, makes it possi- in red, the dento-alveolar area in black ble for practitioners to create more and the mandible in blue. All are precise diagnoses5,6,7,13. These im- constructed with an ideal relationship proved formulations will be based on to each subject’s cranial and cervical the size of the condyles, which de- morphology. pends on genetic influences and adap- For the first case of a severe tive growth, the size of the coronoid mandibular hyperdivergence, Profes- processes, a function of the temporal sor Delaire, the eponymous creator of periosteal matrix, the form and the the analysis, himself has prepared a shape of the gonial region, a function of complete morphological study of the the masseter and the medial ptyergoid skeletal and pharyngeal structures matrix, with respect to the spinal that delineates the deformations and 11,12 column and, finally, the orientation insufficiencies in the development of of the alveolar processes. the different entities as well as the This article will review different notion of auxological potential. clinical situations described by a mor- We discuss the repercussions such phological analysis of the mandible and studies of the different types of then by an orthognathic architectural posterior rotation of the mandible can construction using Delaire’s digitized have on orthodontic, orthopedic, and TM analysis (Tridim ). The results of the surgical therapy, simplified analysis are presented in

PRESENTATION OF CASE NUMBER ONE

This 30 year-old patient suffers from production of the protein fibrillin-1 a rare systemic disease, related to and possibly transmitted by a domi- skin sclerosis, or scleroderma, called nant autosomic gene1,10. the stiff skin syndrome. Small in size, • An oral examination revealed: with deformed fingers she walked and – lack of lip closure at rest seated herself with difficulty. Although – a strongly convex facial profile the effort was not painful, she could – a ‘‘gummy’’ smile open her mouth only to a limited – and a reduced chin to neck extent making taking pictures of her distance teeth (fig. 1 a to g) a troublesome procedure. • The patient had a Class I molar The stiff skin syndrome is a geneti- occlusion, almost normal overjet cally transmitted disorder that affects as a result of orthodontic treatment skin and connective tissue throughout accompanied by the extraction of the body that leads to progressive both maxillary canines and two decrease in joint mobility, caused, lower bicuspids and germectomy an international team of researchers of all four third molars that she had discovered last year, by excessive undergone as a teenager.

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Figures 1 a to g Facial and intraoral photographs of patient 1, who suffers from the stiff skin syndrome. Note her facial convexity and her inability to close her lips at rest. Her dental occlusion, however, was relatively well balanced.

Analysis of the profile C2-C3 intervertebral disc, open to an cephalometric X-ray exaggerated extent, and with a marked antegonial notch. The sym- • The head of the condyle is small, physis is high and extremely narrow shorter than the coronoid process, in it upper sector. and oriented obliquely backward. • The apices of the molars are very The posterior border of the ramus close to the mandibular canal while is concave and the angle of the the apices of the incisors are at a mandible is positioned higher than considerable distance from the border

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of the mandible. The occlusal plane is What diagnosis has been tilted vertically, which makes the delineated? patient’s smile almost gummy • In addition, one can note, a The shortness of the condyles was narrowing of the caliber of the caused by an organic assault on the airways that appear to be shrunken condylar blastema that provoked in- behind the base of the tongue. A sufficient posterior vertical develop- partial calcification of the stylo- ment, a posterior rotation of the body hyoid ligaments can also be seen. of the mandible, and, finally, repercus- • An architectural orthognathic sions affecting the teeth and the analysis (shown in simplified form alveolar process. In addition to mal- in fig. 1 i, and in complete form in formation syndromes like hemi-facial fig. 1 j) gives a clear picture of the microsomia, the Treacher Collins or forward position of the condyle, Goldenhar syndromes as well as posterior vertical insufficiency, inflammatory, infectious, and trau- anterior vertical excess, bi-maxillary matic assaults on the condyles may retrusion with a short mandible as be at the root of the problem. well as a Class II skeletal pattern. While moderate cases that have The analysis presented in figure 1 k little clinical effect do exist, other, quantifies the developmental short- more serious disorders may, in their comings of the skeletal compo- development, express themselves in nents of the mandible, showing how it can be a formidable tool for planning surgical procedures. The tracing depicted in figure 1 l focuses on the pharyngeal airway.

Figure 1 i Simplified analysis with the ten most important traits portrayed. The ideal maxillary configuration is shown in black, and the ideal mandibular in blue in contrast to the actual cranial and cervical morphology of the patient. The Figure 1 h maxillary and mandibular structures are clearly seen in Profile cephalometric film. Note the signs of marked their retro position in relation to the ideal framework. The posterior rotation, thin symphysis and pronounced ensemble of this patient’s facial complex has rotated in a antegonial notch. distinct counter-clockwise fashion.

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Figure 1 j Here is the complete architectural and orthog- nathic analysis that Professor Jean Delaire has made of this case.

Figure 1 k Professor Delaire’s analysis of the surfaces of the mandible: interestingly the naso-maxillary and dento-alveolar regions show normal values indicating that they have not suffered any developmental insufficiency in contrast to the body and rami of the mandible.

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Figure 1 l Professor Jean Delaire’s analysis of the oro-pharyngeal soft tissues above the hyoid bone.

temporo-mandibular joint ankylosis, body of the mandible a relative excess intra-articular hemorrhage, condylar of length from the work of Professor fractures, prolonged immobilization of Ferri8). the mandible, systemic and local In this particular case, because of infections, scleroderma, and spondy- the patient’s serious systemic disease larthritic ankylosis. and in spite of the negative esthetic effects of the malocclusion, we did not plan any surgical intervention, not What procedures should the even a genioplasty, because, in the practitioner initiate and what surgeon ‘s opinion, the difficulties of eventual influence will this type intubation and the risk of poor oss- of posterior mandibular rotation eous consolidation would be too have on orthodontic great. treatment? On further examination we deter- mined the patient was suffering from In cases of short rami, traditional a moderate case of obstructive sleep orthognathic surgery could give apnea syndrome for which she had disappointing results. The usual treat- demonstrated no daytime symptoms. ment consists of a sagittal osteotomy She was successfully treated for this that corrects the antero-posterior dis- disorder with non-invasive positive crepancy but perpetuates the intrinsic pressure ventilation. mandibular imbalance and gives the

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PRESENTATION OF CASE NUMBER TWO

Here are the basic diagnostic features • An architectural analysis before of this case of a 12 year-old female treatment delineated the inade- patient suffering from Still’s disease, quate vertical development of the juvenile rheumatoid polyarthritis. rami before treatment (fig. 2 y), the • Occlusion: maxillary retrusion, and the conti- – asymmetric Class II division 1 nuation of the posterior rotation of malocclusion, the mandible, with a marked ascen- – a narrow maxillary arch with a sion of the mandibular angle during cross bite of the right buccal the course of treatment that con- teeth, tinued until the end of the growth – all four first molars had been period (fig 2 z to z’). extracted because of rampant car- ies, What diagnosis has been – anterior overjet of 5 mm. In delineated? anterior propulsion patient slid her mandible 2 mm away from Rheumatoid polyarthritis is a chronic centric relation. inflammatory disease that causes pro- • Basal bone wasinaClassII gressive destruction of joints and relationship with a retruded mand- imposes multiple and, sometimes, ible and hyperdivergent face. profound functional, psychological, so- • Treatment cial, and, later, professional problems Because of condylar resorption we on patients it strikes. It is the most consulted Professor Couly’s maxillo- frequently occurring and the most facial surgery service at the Necker severe of the inflammatory rheuma- Sick Children University Hospital Cen- toid diseases, affecting 0.3 to 0.5% of tre, which graciously agreed to take the French population. The disease care of the patient’s medical needs. develops in spurts separated by peri- With the approval of our consultants, ods of remission. During the acute we began a phase of orthopedic treat- phases, joints become swollen and ment with a monobloc activator. We painful and patients suffer from concluded with a full banded and bonded moderate fever and asthenia. When 30 month treatment, accompanied by attacks by the disease on both left and high pull head gear, to close spaces, right temporo-mandibular joints be- coordinate the arches, and to obtain a come aggravated they can cause Class I occlusion (see fig. 2 a to h, before deformities and a crippling destruction treatment, and fig. 2 I to p, after of the heads of the condyles. treatment). In this young patient’s case, the • At a check-up visit ten years after early destructive effect on the heads the end of treatment we found that of the condyles diminished the height the occlusion had relapsed to a Class II of the rami so that gonion rises in relation, the patient’s profile was relation to the lower border of the retrusive, and that a molar-to-molar odontoid process. This also generates open bite had appeared. (fig. q to x). an imbalance of the maxillo-facial

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Figures 2 a to h Facial and intraoral photographs of patient 2, who is afflicted with rheumatoid polyarthritis before treatment.

complex within its framework, mark- after such a therapeutic success, edly verticalizing the occlusal plane. which, even more gratifyingly, had been achieved after the end of the pubertal growth spurt. What procedures should the The brutal appearance of the anterior practitioner initiate and what open bite reflected a progression of the eventual influence will this type rheumatoid polyarthritis’s disintegrat- of posterior mandibular rotation ing action on the heads of the condyles, although the persistence of juvenile have on orthodontic treatment? swallowing may have made a func- This kind of severe relapse can tional contribution to the onset of this bewilder the orthodontist, especially unwelcome occlusal development.

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Figure 2 i to p The same patient after treatment. Note the harmonious smile, the well-balanced profile, with overjet and overbite within normal limits.

As a component of our plan to vertical dimension only slightly but treat this problem symptomatically, would have the effect of augment- we do not plan to grind the poster- ing the distribution of the inter-arch ior inter-arch contacts that protect contacts. the joints, but, instead to construct The increasing severity of the pa- a thin oral splint that would increase tient’s arthritic disease would make it

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Figures 2 q to x Facial and, especially, intraoral photos of the same patient ten years after the end of treatment show the brutal appearance of an open bite that extends from molar to molar associated with a retrusion of menton.

difficult to justify correcting the new future time to bring the maxilla to Class II relationship and the open bite mandible relationship and the unaes- with a mandibular osteotomy but we thetic ‘‘chinless’’ profile closer to may consider a genioplasty at some normal limits.

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Figure 2 y Profile cephalometric X-ray and architectural analysis before treatment.

Figure 2 z Figure 2 z’ Profile cephalometric X-ray at the end of treatment and Profile cephalometric X-ray taken at the end of growth simplified architectural analysis. period recall visit.

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PRESENTATION OF CASE NUMBER THREE

This 8 year-old girl consulted us (fig. 3 a to g). Even though her tonsillar because of the delayed eruption of her tissues were hypertrophied she dis- upper lateral incisors as well as the played no symptoms of otolaryngolo- upper first molars that were blocked gical infection or serious otitis. under the second temporary molars.

Figure 3 a to g Facial and intraoral photos of patient 3 who suffers from juvenile obstructive sleep apnea syndrome. She had a Class II malocclusion, a narrow and retruded maxilla, with bilateral buccal cross bites, and an anterior open bite.

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Analysis of the profile cephalo- and horizontal development of the metric X-ray (fig. 3 h) mandible causing both the body and the rami to be shorter than • Hypertrophied adenoidal tissue normal (fig. 3 i). with a narrowing of the retro-alveo- lar airway can be seen. • The head of the condyle is dimin- What diagnosis ished in size and is at the same has been delineated? level as the upper edge of the coronoid process. The posterior In this case of micro, or small borders of the rami are slightly mandible, development of all com- concave and the body and rami ponents has been altered with the are short. exception of the dento-alveolar • The mandibular angle is ascend- sector. The lower arch is well ing and rather open with a marked developed, without crowding. The antegonial notch narrow maxilla is retruded and the • The symphysis seems to be smal- upper teeth are in bi-lateral cross bite, ler than normal size. which may be related to the patient’s • An orthognathic analysis of the habitually keeping his tongue in a low profile head films reveals bi-max- position and being a mouth breather. illary retrusion, insufficient vertical

Figure 3 i Figure 3 h Simplified architectural analysis shows bi-maxillary Profile cephalometric film shows adenoid and tonsillar retrusion. The mandible’s vertical and horizontal dimen- hypertrophy. The maxillary first molars are in a mesial sions of both the corps and the rami are below average. position.

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What procedures should the suffered from a severe case of ob- practitioner initiate and what structive sleep apnea syndrome with eventual influence will this type peaks of oxygen desaturation. After we began to treat her with rapid of posterior mandibular rotation palatal expansion, the index of ap- have on orthodontic treatment? nea-hypopnea spontaneously im- proved making a tonsillectomy and Because of the patient’s facial adenoidectomy less urgent. retrusion and young age, we decided to attempt to stimulate growth with Later, treatment with an activator orthopedic procedures and to avoid may be indicated to stimulate growth extractions. of the mandible, whose vertical growth, despite the anterior open bite, After an orthodontic evaluation, we was inadequate, probably because of requested a polysomnographic exam- the tongue’s habitual low and forward ination. It confirmed what our assess- positioning. ment had indicated, that the patient

PRESENTATION OF CASE NUMBER FOUR

Surgeons had operated on this Analysis of the profile seventeen year-old boy numerous cephalometric X-ray (fig. 4 h) times to correct his left labio-alveolar- palatal cleft by closing the oro-nasal • The head of the condyle is quite opening, performing a uni-lateral Z large with a long and thick neck labioplasty, and bringing the upper left resembling the coronoid process, cuspid into its place in the arch with which is also over-developed. surgico-orthodontic means. His upper • The angle of the mandible is split, left lateral incisor was congenitally lowered on one side, and extremely absent. open, with a well-chiseled antego- The esthetic repercussions of his nial notch. deformity, which were profound, were • The mandibular symphysis is caused by lack of support for his nose rather delicate, with the lower and insufficient lateral growth of the dental arch seemingly retruded as maxilla (fig. 4 a to g). a compensation for the Class III malocclusion. Because of the narrow and retruded • Paralleling these features tongue upper arch, there was a bilateral cross posture is low, maxillary structure bite of the buccal teeth. A severe seems to have collapsed with the anterior open bite was present to- pre-maxilla rising as a component of gether with asymmetry caused jointly an exaggerated compensatory by the maxillary midline’s drifting to curve. the left toward the space of the • An orthognathic analysis reveals missing lateral incisor and by the a skeletal Class III conformation lateral deviation of the mandible.

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Figures 4 a to g Facial and intraoral photographs of patient 4 who had received treatment for a naso-labio-alveolar-palatal cleft. He had a Class III malocclusion with insufficient lateral growth of the maxilla.

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Figure 4 h Figure 4 i The mandible is long and massive and shows marked This simplified architectural analysis shows the exces- signs of posterior rotation. sively long body of this mandible that extends vertically beyond the ‘‘ideal’’ framework but whose rami seem to conform better to the standard dimensions. The under- developed maxilla has an ascending anterior portion.

with a retruded maxilla, a custom- ary finding in patients with labio- The architectural analysis reveals alveolar clefts, a large mandible, that this patient does not have a true antecondylia, and excess anterior macro-mandible but, instead, ante- height (fi. 4 i). riorly placed condyles in addition to an excessively long mandibular body or dolicho mandible. What diagnosis has been delineated? What procedures should the Macro-mandibles, which show in- crease of substance in all three practitioner initiate and what dimensions of space, are rare anoma- eventual influence will this type lies, notably found in cases of acro- of posterior mandibular rotation megaly. They exhibit very strong have on orthodontic treatment? condylar growth, a phenomenon that often generates a Class III mal-occlu- In cases of true hypercondylia, a sion that is likely to be asymmetrical. single or bilateral condylectomy is The lowering of the mandibular angle strongly indicated. On the other hand, toward the second cervical vertebra (C when the mandibular angle is located 2) reflects excess of posterior vertical above the C 2 vertebra, this is usually height, a finding that does not seem to a sign of vertical posterior insuffi- obtain in this particular case. ciency.

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CONCLUSION

Like cats, all images of posterior We invite our readers to intensify rotation may look gray in the dark, but their understanding of the subject by after a careful morphological analysis, reading the principal works of Profes- effectively completed by an architec- sors Jean Delaire, Mercier, and Salag- tural construction, mandibles all have nac, whose studies have been the their own specific characteristics and primary inspiration for these lines. the orthodontic, orthopedic, and surgi- cal therapeutics for treating posterior rotation are numerous.

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