Maxillary Deficiency with Relative Mandibular Excess Growth Patterns

Published on 13/06/2015 by admin

Filed under Surgery

Last modified 13/06/2015

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 3588 times

20

Maxillary Deficiency with Relative Mandibular Excess Growth Patterns

Developmental Class III skeletal problems generally result from maxillary deficiency in combination with relative mandibular excess. Through trial and error, it is now recognized that either growth modification in the preadolescent patient or camouflage treatment in the teenager or adult as a method of managing this type of dentofacial deformity is at best relatively ineffective. In addition, even mild degrees of a Class III facial appearance are aesthetically noticeable as unattractive by the general population.76 Therefore, the perceived need for treatment (i.e., de facto orthognathic surgery) for the Class III patient—whether by the public, the evaluating clinicians, the affected individual, or the patient’s family and friends—will be high.13,72,78,125

There is a strong family tendency for a Class III skeletal pattern. The so-called “Habsburg jaw” within the royal European family is well documented.58,104,106,122,124 The frequency of Class III skeletal patterns among white people of European or North American ancestry is reported to have a prevalence in the low single digits. There is a somewhat higher prevalence of Class III skeletal patterns among Africans than among Caucasians.27 Data from Japan, Korea, and China confirm a more frequent Class III pattern among Asians than among any other subgroup (i.e., >4%).28,117 Incidence rates of Class III malocclusion of as high as 13% have been reported in specific regions of Asia.119 Lew and colleagues examined occlusal parameters in 1050 Chinese schoolchildren who were between 12 and 14 years old.48 They found an incidence of 12.6% for Class III malocclusion, 58.8% for Class I occlusion, and 21.5% for Class II malocclusion. Samman and colleagues investigated 300 Chinese individuals residing in Hong Kong who were known to have dentofacial deformities and who had been referred to an “orthognathic surgery clinic.”91 After excluding those individuals with cleft lip and palate, 222 study patients remained. Forty-seven percent of these individuals (n = 104) were found to have a Class III skeletal malocclusion.

Despite hereditary tendencies, the development of a Class III jaw disharmony is believed to be multifactorial and complex.8,33,39,57 Alternatively, it has been documented that environmental factors have a significant effect on vertical facial growth (see Chapter 21). The combination of an individual’s hereditary tendency toward a Class III skeletal pattern and a longstanding, forced mouth breathing, open-jaw posture during growth explains the occasional occurrence of a long face growth pattern (i.e., excess vertical growth) with Class III negative overjet malocclusion.29 An outlier for a Class III skeletal pattern is the impaired midface growth that is seen in many individuals from all backgrounds with repaired cleft palates (see Chapters 32, 33, and 34). Another commonly seen clinical pattern is the individual with maxillary vertical deficiency and a prominent pogonion (i.e., pseudoprognathism) as a result of “over closure” (see Chapter 23).97,99,109

An additional source of data regarding the prevalence of individuals with skeletal Class III is the National Health and Nutrition Examination Survey III, a large-scale epidemiologic survey of the U.S. population that was carried out during the 1990s (see Chapter 3).77 The data from this study confirm that Class III problems increase from early childhood through adolescence.1,18 This can be explained by the expected late growth spurt in the mandible as compared with the maxilla. The study also confirmed that the presence of 2 mm or more of negative overjet is about twice as likely to occur among African Americans than among Caucasian Americans or Mexican Americans. Data from a U.S. public health survey of youths between the ages of 12 and 17 years indicates that about 14% have a mandibular first molar that is mesial in relation to the maxillary first molar.42

With regard to treatment, by the late 1800s, both Edward Angle, an orthodontist, and Vilray Blair, a surgeon, recognized that orthodontic treatment alone could not solve the Class III skeletal problem.15 Angle suggested that the only possible way to correct a true mandibular protrusion was with a combination of orthodontics and surgery.2 By the late 1800s, the initial orthognathic procedures were carried out to “set-back” the prominent mandible (see Chapter 2).

Functional Aspects

• Predictable articulation errors in speech result from a Class III malocclusion (see Chapter 8).

• Chronic obstructed nasal breathing is commonly seen in the presence of maxillary deficiency (see Chapter 10).

• Characteristic difficulties with swallowing and chewing as a result of a Class III malocclusion are expected (see Chapter 8).

• Wide lip separation (often with upper lip hypotonia) and mentalis strain required for lip seal are commonly seen in the presence of a significant negative overjet.

• Detrimental long-term effects on the dentition and the periodontium that result from a Class III malocclusion (secondary occlusal trauma), dental crowding, or previous camouflage orthodontics are often seen (see Chapter 6).

• The incidence of temporomandibular disorder (TMD) may be higher among these patients than among individuals with normal jaw harmony and occlusion (see Chapter 9).

Clinical Characteristics

The Role of Growth Modification in the Preadolescent Patient

Since the mid 1800s, clinicians have developed and used devices to attempt to correct and prevent a worsening Class III skeletal pattern during childhood. Despite this extensive history, little long-term success has been documented involving the use of these devices. Techniques have included use of a chin cup to “hold back” the mandible; a face mask to “grow” the maxilla; and, more recently, the use of skeletal anchorage devices and elastics in an attempt to do both.

Most studies have found no difference in the ultimate size of the mandible between children with Class III conditions who were treated with a chin cup and those who were not.105 Wylhelm-Nold and colleagues presented some evidence that the use of the chin cup in preschool-aged children was able to decrease mandibular anterior growth if good compliance was achieved.123 Unfortunately, this did not prevent the mandible from continuing an excess growth pattern later during childhood, after the chin cup treatment was stopped. In fact, a rebound accelerated growth effect was documented. What chin cup therapy may accomplish is a change in the growth vector of the mandible, with more downward and backward (clockwise) rotation.37 These secondary changes have their own negative effects on facial morphology and occlusion (i.e., the law of unintended consequences).

With the realization that the presenting maxillary deficiency should be the primary focus of the correction for most skeletal Class III individuals, growth modification moved toward methods of stimulating the upper jaw. The Delaire face mask has been used extensively to pull the maxilla forward.24 The work of Baccetti and McNamara confirmed that use of the Delaire face mask for the individual with maxillary deficiency is more likely to have effect when it is used before the patient is 8 years old.6,21,92 After this age, tooth movement (dental compensation) and mandibular clockwise rotation will be the likely consequences of this form of treatment rather than the hoped for horizontal maxillary projection. In addition, many children experience recurrence of the deformity after face mask therapy is discontinued. It is unlikely that face mask (for the maxilla) and chin cup (for the mandible) interventions will be effective in the long term for preventing the need for orthognathic surgery in all but mild cases. An accepted guideline is that more than 2 to 4 mm of reverse overjet in the preadolescent child indicates that surgery will eventually be needed if both facial and dental correction are sought.

DeClerck and colleagues used orthopedic traction on the maxilla and compression on the mandible with temporary mini-plate skeletal anchorage and elastics in a limited number (n = 3) of 10- to 11-year-old children presenting with skeletal Class III malocclusions.25 Pure bone-borne orthopedic forces were applied with intermaxillary elastics on the skeletally anchored mini-plates. This approach was shown to either enhance midface growth or to hold back the mandible; in any case, the intent was to produce a corrected overjet. Although the authors were encouraged, many unknowns remained, including the ideal age for this type of orthopedic traction; the effect of the direction of force on the rotation of the palatal and mandibular planes; the long-term effects on the temporomandibular joints; and the need for retention to prevent catch-up growth of the mandible or relapse of the maxilla afterward. DeClerck’s ongoing prospective clinical trial of this promising work on a larger sample of patients (as well as the work of other independent researchers) will help to answer these questions and to determine the true effectiveness of a growth-modification approach that involves temporary skeletal anchorage and elastics.21,92

Orthodontic Camouflage Approach

The decision to proceed with an orthodontic camouflage approach frequently implies that orthopedic growth modification mechanisms to overcome the Class III pattern were either ineffective earlier during the patient’s life or that the patient presents to the orthodontist at an age at which such mechanisms are not feasible. In the adolescent or adult, when a significant reverse overjet remains, the possibility of achieving even the limited parameter of a neutralized occlusion with the use of only orthodontic maneuvers is questionable. In fact, doing so may require the further displacement of the teeth outside of the supporting alveolar bone as a means of compensation for the underlying jaw discrepancy. The extraction of the mandibular first premolars in combination with Class III elastics and extraoral forces on the maxilla (i.e., the proclination of the maxillary incisors) will improve the occlusion for the Class III patient; however, treatment generally falls short of expectations and rarely produces acceptable facial aesthetics. Even minimal retraction of the lower incisors often magnifies the chin’s prominence, which is likely a primary reason why the patient sought treatment. Furthermore, camouflage orthodontics will not succeed in altering any combined vertical skeletal problems. In fact, the orthodontic mechanisms that are used to reposition the dentition often extrude the posterior teeth, thus further accentuating the vertical facial disproportion.

Individuals who present to the orthodontist with a Class III skeletal pattern will usually have dental compensation that developed as an adaptive biologic mechanism during growth. Typically, the upper incisors are at least somewhat proclined relative to the maxillary basal bone. The lower incisors are often overly upright relative to the basal bone of the mandible. If an orthodontic camouflage approach is chosen, then the upper incisors are proclined, and the lower incisors are retropositioned even further.

It is not uncommon for the orthognathic surgeon to see an adult in consultation who is emotionally exhausted after having undergone failed growth modification followed by disappointment after additional years of camouflage orthodontics. The individual may present with 1) significant residual malocclusion (i.e., effects on speech, swallowing, and chewing) 2) deteriorating periodontal health (i.e., crest bone loss and gingival recession associated with lower anterior and upper posterior teeth), 3) often with chronic upper airway obstruction (i.e. deviated septum, hypertrophic inferior turbinates, and tight nasal apertures) and 4) self-esteem and body image issues related to the facial disproportion and disappointment with failed treatment (Figs. 20-1 through Fig. 20-4).

image

Figure 20-1 A 34-year-old male arrived for the evaluation of a longstanding jaw deformity with malocclusion, chronic obstructive nasal breathing, and periodontal issues. Since his early childhood years, the patient was known to have a maxillary deficiency with a relative mandibular excess growth pattern. The family elected a camouflage orthodontic approach that included four bicuspid extractions and the introduction of dental compensation in an attempt to neutralize the occlusion when the patient was 10 to 15 years old. He is a forced mouth breather as a result of increased nasal airway resistance. The patient underwent septoplasty when he was 20 years old, but significant improvement of the airway did not occur. His general dentist confirmed labial bone loss and gingival recession of the mandibular anterior and maxillary posterior dentition. He was referred to this surgeon, and a comprehensive orthognathic and dental rehabilitation approach was selected. Consultation with a periodontist, an orthodontist, and an ear, nose, and throat specialist was carried out. The patient was confirmed to have residual deviation of the septum and enlarged inferior turbinates, which explained the continual difficulty that he had breathing through his nose. A degree of root resorption of the anterior dentition was confirmed. The need for gingival grafting to attain improved root coverage and to generate a wider band of attachment was recommended for tooth nos. 3, 11, 14, 19, 20, 23 through 26, 29, and 30. This will be followed by the orthodontic removal of dental compensation and then orthognathic and intranasal procedures to improve long-term dental health, to enhance facial aesthetics, and to open the upper airway. A, Frontal facial and occlusal views before retreatment. B, Profile facial and lateral cephalometric radiograph before retreatment. C, Panorex radiograph before retreatment.

image

Figure 20-3 A 30-year-old man arrived for the evaluation of a longstanding jaw deformity with malocclusion, chronic obstructive nasal breathing, and an awareness of periodontal issues. Since his early childhood years, he was known to have a jaw deformity with malocclusion, including an anterior open bite. When he was between 8 and 12 years old, he underwent orthodontic camouflage treatment in an attempt to close the open bite; this included full bracketing and the use of heavy anterior elastics. By the time that he graduated from high school, he was conscious of a significant recurrent anterior open bite with dental crowding. Throughout his college years, he was aware of gingival recession on the labial aspect of many of the anterior teeth of the maxilla more so than the mandible. He was sent by his general dentist for an orthodontic evaluation and then to this surgeon for an opinion. The patient was referred for periodontal evaluation with confirmation of significant labial bone loss of the anterior dentition (more so on the maxilla than the mandible) and gingival recession. A comprehensive approach was recommended; this would include gingival grafting and four bicuspid extractions, with orthodontic retraction of the anterior dentition into the solid alveolar bone. This would be followed by jaw reconstruction, finishing orthodontics, and periodontal surveillance. A, Frontal facial and occlusal views before retreatment. B, Profile facial view and lateral cephalometric radiograph before retreatment. C, Panorex radiograph before retreatment.

image

Figure 20-4 A 29-year-old man arrived for the evaluation of a longstanding developmental jaw deformity characterized by maxillary deficiency with relative mandibular excess. There is malocclusion and chronic obstructive nasal breathing. By the time he was 13 years old, he was referred by his pediatric dentist to an orthodontist for the evaluation of a Class III negative overjet malocclusion. He then underwent a 2-year course of compensatory orthodontics in an attempt to neutralize the occlusion. He was left with an Angle Class III negative overjet and early signs of gingival recession. The patient also has a history of stress-induced asthma and chronic obstructed nasal breathing. He uses Flonase, Singulair, and other medications in an effort to open the nasal airway, and he is also being seen by an allergist. For his gingival recession, he was referred to a periodontist, and connective tissue grafting was carried out for the lower anterior dentition on several of the maxillary posterior teeth. An orthodontic consultation confirmed crowding, the proclination of the maxillary anterior dentition, and uprighted mandibular anterior teeth. Evaluation of the upper airway documented a deviated septum and hypertrophic inferior turbinates. An orthodontic and surgical approach was recommended to limit further secondary dental trauma, to stabilize the periodontium, and to correct the occlusion. A, Frontal facial and occlusal views before retreatment. B, Profile facial and lateral cephalometric radiographs before retreatment. C, Panorex radiograph before re-treatment.

All too often, the orthodontic camouflage approach was centered on the achievement of a neutralized occlusion as the primary objective, without full disclosure to the patient and his or her family. If the goals of treatment are to achieve long-term ideal dental health, improved facial aesthetics and an open upper airway, few treatment plans for the Class III patient would include a camouflage approach. Clear contraindications to an orthodontic camouflage approach include the following:

Surgical Camouflage Approach

Some orthodontists have been buoyed in their efforts to neutralize the occlusion in the individual with a skeletal Class III condition on the basis of a belief that limited cosmetic surgery can improve the facial appearance and thus avoid major orthognathic procedures. Attempts at surgical camouflage for the patients with a Class III skeletal pattern may include a combination of reduction genioplasty; onlay grafting to the midface; upper lip augmentation; lower lip reduction; and neck and chin soft-tissue procedures. In general, these camouflage surgical techniques are ineffective, irreversible, and disappointing.

Often, a prominent chin and apparent flat cheek bones are perceived by the patient to be the aesthetic issues. Although a reduction genioplasty seems to be a logical approach, the surgical reduction of the prominent chin as an isolated procedure in the absence of orthognathic surgery rarely satisfies the facial aesthetic concerns. “Setting back the chin” generally leads to drooping (i.e., ptosis) of the associated soft tissues; irregularities of the mentalis muscles when in function; and a double-chin appearance of the neck. Submental lipectomy may then be considered in an attempt to improve the chin ptosis and the appearance of the neck, but with only limited effects. Onlay grafts or implants involving the anterior maxilla have been used in an attempt to camouflage the midface deficiency. These perinasal implants run the risk of looking and feeling unnatural. Augmentation of the zygomas and the infraorbital rims is generally misguided and will produce an unnatural and “operated” look. Upper lip augmentation and lower lip reduction procedures in the Class III patient also tend to look and feel unnatural.

To be fair to the patient and his or her family, the limitations of compensating orthodontics followed by surgical camouflage should be disclosed before the initiation of treatment.

Definitive Reconstruction

Timing of Orthognathic Surgery

Skeletally immature individuals with true mandibular excess can be expected to outgrow any early orthodontic or surgical corrections and later require further treatment.7,17,83,90 Indirect methods of assessing growth maturity (e.g., a hand–wrist film to determine bone age) are not accurate enough to be used in isolation for planning the timing of surgery. A reasonable method to assess growth maturation is through the analysis of serial lateral cephalometric radiographs. These radiographs can be used in two ways: for a cervical vertebral analysis or to make sequential direct mandibular measurements. Surgery is delayed until the deceleration of growth can be documented. The use of a quantitative condylar head bone scan can also be helpful to evaluate the growth of the mandible in the adolescent, but both false-positives and false-negatives may occur. If the Class III condition is largely the result of maxillary deficiency, gauging the preferred timing of surgery is more straightforward, because the late postsurgical growth of the mandible is less likely (see Chapter 17).

Alexander and colleagues completed a study of craniofacial growth changes in Caucasians with untreated Class III malocclusions by using longitudinal cephalometric records (n = 103).1 In girls, the mandibular growth spurt generally occurred between the ages of 10 and 12 years. In boys, the growth spurt was usually between the ages of 12 and 15 years. In some of the Class III subjects, limited degrees of mandibular growth relative to that of maxillary growth were documented to continue after the adolescent spurt. After the age of 13 years in girls and 15 years in boys and until closer to the age of 17 years, annual increments of mandibular growth were often between 1.5 mm and 2.0 mm, whereas increments of midface length dropped to less than 1 mm. The authors concluded that the differential growth behavior of the two jaws among individuals with Class III conditions may result in recurrent jaw disharmony and malocclusion when orthodontic or surgical treatment is undertaken before or during puberty.

Orthodontic Preparation for Orthognathic Surgery

1. Before orthodontic decompensation, assess the level of attached gingiva, the position of the labial and lingual plates, and the alveolar crest heights. Consider the effects of any planned orthodontic maneuvers on the periodontium.

2. Make decisions about the tooth (root) size to alveolar volume discrepancies in each arch and the need for extractions to establish and preserve periodontal health.

3. Create a plan (i.e., separate surgical and orthodontic objectives) to achieve preferred anteroposterior and vertical incisor positions in the maxilla and the mandible.

4. Understand how the orthodontic objectives become more limited when they are combined with the planned surgical procedures (e.g., maxillary segmentation, bimaxillary osteotomies) to then achieve the final desired arch form, midline positioning, occlusion, and facial symmetry and proportions.

5. Make decisions about orthodontic mechanics and anchorage requirements to achieve the chosen objectives.

6. At the end of the presurgical orthodontic phase (i.e., 4 to 6 weeks before surgery), full-dimensional stabilizing (i.e., passive) arch wires should be in place. The placement of surgical hooks can be done just before surgery.

Leveling the Mandibular Arch

When an accentuated curve of Spee is present in the lower arch of a patient with Class III malocclusion, it is managed through a combination of intrusion of the incisors and extrusion of the premolars or molars.20,49 In preparation for surgery, repositioning the lower incisors forward is generally advantageous for the Class III skeletal pattern. Therefore, lower arch extractions are rarely indicated. If limited labial bone is present, a periodontal evaluation is recommended before the incisors are orthodontically moved forward. If gingival recession has occurred or if the gingiva is genetically inadequate, augmentation grafting procedures are indicated (see Chapter 6).

Leveling of the Maxillary Arch

If the upper arch is narrow, then orthodontic leveling is performed in segments in anticipation of surgical management.8,14,16,22,71,88,95,114 If the curve of Spee is excessive as a result of vertical skeletal dysplasia, then leveling is also done in segments in preparation for surgical correction (see Chapter 17).

In the presence of maxillary deficiency, limited space to uncrowd the upper teeth may leave the roots tipped outside of the solid alveolar housing. In this circumstance, maxillary first bicuspid extractions with space closure before surgery is preferred. With only borderline crowding, extractions are often not carried out. Limited dental space deficiency can often be managed through the judicious use of interproximal reduction. In addition, the aesthetic consequences of mildly proclined incisors (i.e., A-point to B-point discrepancy in profile) can be improved via the clockwise rotation of the maxillomandibular complex at the time of surgery (see Chapters 12 and 13).

Related posts:

Temporomandibular Disorders: Effects of Occlusion, Orthodontic Treatment, and Orthognathic Surgery Selected Complex Malformations that Frequently Require Maxillofacial Reconstruction: Evaluation & Treatment Nasal Airway Considerations in the Evaluation and Treatment of Dentofacial Deformities Asymmetric Mandibular Excess Growth Patterns Dentofacial Disharmonies in Adults: Reconstruction and Rejuvenation Cleft–Orthognathic Surgery: The Unilateral Cleft Lip and Palate Deformity