Rapid, nonsurgical open-bite closure with a passive self-ligating bracket system using a differential bonding technique

Drs. Michael Choy and John Burnheimer discuss closing a patient’s severe anterior open bite in 4 months

Figure 1: Pretreatment photographs

Abstract

An 8-mm anterior open bite in an 18-year-old man was closed in 4 months by means of a passive self-ligating system using a differential bonding technique without extractions, surgery, miniscrews, or multiloop archwires. Ideal overjet and overbite of the anterior teeth were created, and an Angle Class I molar relationship was preserved. A functional occlusion was obtained, a consonant smile arc was created, and an acceptable gingival display was achieved.

Clinical relevance

This severe 8-mm anterior open bite was closed in 4 months’ time.

Objectives statement

The reader should understand the clinical advantages of the Damon® System in closing anterior open bite malocclusions.

Introduction

One of the most difficult malocclusions to treat is anterior open bite (AOB) mal-occlusion, defined as a lack of vertical overlap between the maxillary and mandibular incisors. It can be classified as either primarily dental or skeletal with a prevalence that varies between ethnic and age groups.^1,2 Like many orthodontic problems, open bite malocclusion is multifactorial. Individuals with skeletal AOB generally present with many common cephalometric values — such as increased gonial, mandibular, and occlusal plane angles — and common facial features — such as increased lower anterior facial height (LAFH) and noticeable lip strain.^3,4 Due to its multifactorial etiology and high tendency to relapse, skeletal AOB in adults is regarded as one of the most challenging malocclusions to treat.^1,5

In the past, extractions for adult patients were often prescribed to allow the orthodontists to obtain bite closure by combining incisor extrusion (or uprighting) and molar intrusion, ideally obtaining a counterclockwise rotation of the mandible.¹

More recently, non-extraction therapy with multiloop archwires has been reported to intrude posterior teeth while extruding the anteriors. This seems to produce dramatic dental changes without significant changes in the skeletal pattern.6 However, for nongrowing patients, Carano, et al.,⁷ describe rapid molar intrusion (RMI) and obtained significant skeletal changes.

Another common approach that has been used in the past few years is skeletal anchorage devices such as miniscrews or miniplates.^8,9 Both these therapies can be used for molar intrusion and often dental and skeletal changes take place.^9-11 Posterior buildups are also an effective option, which can intrude and control eruption of the posterior teeth.¹²

Finally, orthognathic surgery for correcting AOB malocclusion commonly consists of performing a LeFort I osteotomy and, in some cases, mandibular ramus osteotomy, thereby repositioning the maxilla and allowing the counterclockwise rotation of the mandible.¹³

Even though most of the aforementioned treatments are successful, the amount of time to close the open bite varies considerably.

In this case report, we introduce the use of a passive self-ligating bracket system with differential bonding technique to close an 18-year-old male’s severe anterior open bite in four months without extractions, surgery, skeletal anchorage, or multiloop archwires.

Figure 2: Pretreatment lateral cephalogram, tracing, and panoramic radiograph

Diagnosis and etiology

The patient was an 18-year-old male with chief complaints of anterior open bite. The patient’s medical history was unremarkable. He admitted to a habit of tongue thrusting; however, lips were competent.

A convex profile due to a retrognathic mandible was noted. A shallow labiomental fold, an increased lower facial height, and minimal musculature strain on lip closure were observed. Both midlines were deviated to the left of the facial midline, and a nonconsonant smile arc was present. Intraorally, the patient had an Angle Class I molar relationship with a severe anterior open bite of 8 mm and moderate spacing in both the maxillary and mandibular arches (Figures 1 and 2). Periodontal tissues were within normal limits. No symptoms of temporomandibular disorder were detected.

The lateral cephalometric analysis showed a skeletal Class II jaw relationship with mandibular retrusion (ANB, 4.7) and a high mandibular plane angle (FMA, 35.0). Both the maxillary and mandibular incisors were proclined labially (Table 1). The panoramic radiograph was unremarkable and included fully erupted third molars. This patient was diagnosed with an Angle Class I malocclusion with a skeletal Class II base, a high mandibular plane angle, and a severe anterior open bite.

Treatment objectives

The treatment objectives were to close the open bite while achieving a consonant smile arc by using a passive self-ligating system. Other goals included to level and align the dental arches, to normalize the overjet and overbite relationships, to center the midlines, and to establish a functional occlusion.

Treatment alternatives

With the severe anterior open bite and the high mandibular plane angle (FMA, 35.0º), a LeFort I osteotomy with posterior maxillary impaction was considered.¹³ Another option would have been to use miniscrews or miniplates to intrude the maxillary posterior dentition.¹⁴ Additionally, extraction of the premolars or the first molars could also have been indicated to help decrease the vertical dimension while helping reduce the anterior and soft tissue protrusion. The patient immediately declined the surgical option. Without careful management and good cooperation, extractions could lead to over extrusion of the anterior teeth during retraction, which could cause an unwanted gingival display and an unattractive smile arc.¹⁵ Extractions were therefore not chosen for this patient. A passive self-ligating system using a differential bonding technique was chosen because it was noninvasive and required neither surgery, miniscrews, extractions, nor complicated multiloop archwires.

Figure 3: Fixed appliances placed using differential bonding technique with initial archwires and elastics

Figure 4: Open bite closed 4 months later

Treatment progress

Passive self-ligating appliances (Damon® 3) were bonded on both arches for initial alignment and leveling. The differential bonding technique positions the brackets more occlusal on the posterior teeth and more gingival on the anterior teeth to minimize posterior extrusion while allowing open bite closure.

Initial archwires were 0.014 CuNiTi with elastics (5/16 in, 3.5 oz) in a triangle configuration from U3s to L3-4s (Figure 3) progressing to 0.018 CuNiTi and triangle elastics (1/4 in, 3.5 oz) from U3s to L2-3s. After 4 months, maxillary and mandibular 0.014 x 0.025 CuNiTi archwires were placed at which time the open bite had closed (Figure 4). Three months later, maxillary and mandibular 0.018 x 0.025 CuNiTi were placed for 6 weeks while continuing elastics and space closure. After 10 months, bracket repositioning was performed, and re-leveling was initiated. Finishing and detailing was performed in 0.017 x 0.025 TMA with anterior box elastics at night. After debonding, full records were taken, and a maxillary wrap-around Hawley retainer and bonded 3-3 retainer were delivered. Total treatment time was 28 months.

Treatment results

There were little changes in the facial profile except for a more everted upper lip. The deficient chin remains, and the lower facial height was unchanged (Figure 5). The open bite was closed in 4 months, ideal overjet and overbite of the anterior teeth were created, and an Angle Class I molar relationship was maintained (Figure 6). There was no gingival recession after the orthodontic treatment. The panoramic radiograph showed no obvious apical root resorption, and root parallelism was acceptable (Figure 6). A functional occlusion was obtained, and the occlusion appears stable 6 months post debond.

Figure 5: Final photographs

Figure 6: Final lateral cephalogram, tracing, and panoramic radiograph

Discussion

The treatment of severe open bites has often involved a combination of orthodontics and orthognathic surgery. Even though the success of this combined procedure has been proven, many patients reject it for financial constraints or concerns of surgery. Much effort has been made to develop techniques that can help in the treatment of severe open bite orthodontic problems. Successful treatment results have been reported in the literature with various types of mechanics and techniques. However, the long-term treatment stability remains to be determined.

This young adult patient was treated conservatively without extractions, surgery, miniscrews, or multiloop archwires. Careful control of the vertical dimension and essentially no autorotation of the mandible were achieved as noted on the superimposition (Figure 7). The maxillary and mandibular superimpositions show control of the molars and retraction and extrusion of the incisors. Accordingly, over retraction of the anterior teeth with extraction therapy could have increased the gingival display to an unacceptable degree and worsened the smile arc. Together, for these and other reasons it was decided to treat non-extraction.

Certainly, this patient could have been treated with any of the other treatment options to a successful result, but few could have closed the anterior open bite this quickly.

With the exception of shorter treatment times, most studies have shown no advantage to the passive self-ligating system when compared to conventional preadjusted edgewise brackets.16,17 This case affirms the rapidity of a passive self-ligating system using differential bonding, as this severe open bite was closed in 4 months. In this patient, the closing of the open bite and the restoration of full arch interdigitation solely by an ortho-dontic approach were generally acceptable.

Conclusions

A severe open bite with a skeletal Class II base and a high mandibular plane angle can be corrected by using a passive self-ligating system and preventing eruption of the molars, minimal to no rotation of the mandible, ideal restoration of overjet and overbite, and a consonant smile arc. Further clinical research is needed to assess this consistency of this rapid treatment modality.

Figure 7: Cephalometric superimpositions