Ribbon-wise customized lingual appliance and orthodontic anchor screw for the treatment of skeletal high-angle maxillary protrusion without bowing effect
This case report demonstrates the treatment of a skeletal Class II high-angle adult patient with bimaxillary protrusion, angle Class I occlusion, and crowded anterior teeth. A ribbon-wise arch wire and a customized lingual appliance with anterior vertical slots were used to achieve proper torque control of the maxillary anterior teeth. An orthodontic anchor screw and a palatal bar were used for vertical control to avoid increasing the Frankfort-mandibular plane angle (FMA) by maxillary molar extrusion. Through the combined use of the ribbon-wise customized lingual appliance, palatal bar, and orthodontic anchor screw, vertical control and an excellent treatment result were achieved without the vertical and horizontal bowing effects peculiar to conventional lingual treatment.ABSTRACT
INTRODUCTION
In skeletal Class II cases with bimaxillary protrusion, the most important treatment goals are usually improvement of the occlusal relationship and facial profile.1 To achieve these goals, the anterior teeth should be moved carefully to prevent the loss of molar anchorage after tooth extraction, and they should be retracted with suitable torque control.2 Optimally, the mandibular anterior teeth should be upright enough to eliminate labial inclination, and the maxillary anterior teeth should be moved bodily toward the palatal side. When using a conventional edgewise lingual appliance with horizontal slots, extrusion and lingual tipping of the anterior teeth (ie, rabbited anterior teeth) tends to occur during anterior retraction. It is therefore necessary to avoid this side effect.3,4
Molar extrusion during treatment is known to result in clockwise rotation of the mandible, which causes the chin to move backward and, thus, does not help improve the facial profile,5 especially in hyperdivergent patients. Achieving vertical control during treatment is therefore important.
This report describes an excellent result in the treatment of a skeletal high-angle maxillary protrusion and mandibular retrusion case using a ribbon-wise customized lingual appliance (Incognito, TOP-Service, Bad Essen, Germany), which has vertical slots anteriorly and horizontal slots in the molar region. An orthodontic anchor screw (OAS) was also used for anchorage control, torque control, and vertical control.
CASE REPORT
Pretreatment Evaluation (History)
A 20-year-old woman presented with a complaint of crowded, protruding anterior teeth. Her overall general health was good. She was aware of regular oral respiration and sleeping with her mouth open. There was no significant medical history.
The frontal facial examination revealed maxillary anterior teeth protruding over the lower lip with a slight gummy smile. The facial profile was convex (Figure 1).
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
The intraoral examination revealed crowding and protrusion of the maxillary and mandibular anterior teeth. Oral hygiene maintenance was good. The molar occlusion was Class I on both sides, overjet was +6.0 mm, and overbite was ±0 mm. Maxillary and mandibular crown widths were larger than average, indicating that both the maxillary and mandibular arch widths were constricted when compared with the crown width. The curve of Spee was −2.5 mm (Figure 2).
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Panoramic radiograph findings revealed that the mandibular third molars were horizontally impacted bilaterally, the root of the right maxillary second premolar was arched and short, and four maxillary anterior teeth also had short roots and a tendency for root resorption (Figure 3).
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Lateral cephalometric analysis revealed skeletal maxillary protrusion with SNA, SNB, and ANB angles of 85.0°, 79.0°, and 6.0°, respectively. Frankfort-mandibular plane angle (FMA) was 33.5° and the SN-mandibular plane angle (SN-MP) angle was 40.5°, indicative of a high-angle skeletal pattern. Maxillary and mandibular anterior teeth labio-inclination was indicated by maxillary central incisors (U1) to Nasion-point A line (NA) of 10.0 mm/37.5°, mandibular central incisors (L1) to Nasion-point B line (NB) of 13.0 mm/39.5°, and an interincisal angle of 97.0°. Soft tissue findings confirmed a Z-angle of 54.0° and that the upper and lower lips were at +4.5 mm and +10 mm, respectively, to the esthetic line (E-line; Table 1).
Diagnosis and Treatment Objectives
The diagnosis was maxillary and mandibular anterior tooth labio-inclination and crowded teeth with angle Class I occlusion accompanied by skeletal high-angle maxillary protrusion.
The patient had an excessive vertical dimension of occlusion, and orthognathic surgery was recommended to correct this hyperdivergency. However, the patient declined surgery and orthodontic treatment without surgery was started. The Level Anchorage System, developed by Root,6 was used to set treatment goals, and the treatment plan and orthodontic mechanics were established accordingly. Because the patient had skeletal maxillary anterior protrusion with maxillary and mandibular anterior tooth labio-inclination, improvement of the facial profile was necessary. To achieve this, the decision was made to extract both maxillary and mandibular first premolars and retract both the upper and lower anterior teeth. However, because sufficient anchorage or vertical control was not otherwise obtainable, an OAS was used in the maxilla as well. The decision was made to consider the need for extracting the mandibular third molars after treatment.
Specific treatment goals were to reduce the ANB angle from +6.0° to +4.0°, U1 to NA from 10.0 mm to 4.0 mm, and L1 to NB from 13.0 mm to 7.0 mm. The ribbon-wise customized lingual appliance (Incognito; slot size 0.025 × 0.018 inches, vertical slots in the anterior region, horizontal slots in the molar region, and a low-friction slot known as a cutting edge self-ligation slot in the mandibular anterior teeth region) and ribbon-wise wire were used.7,8
In the present case, it was necessary to improve the skeletal high-angle maxillary anterior teeth with orthodontic treatment alone, reduce the SNA angle as much as possible, maintain or increase the SNB angle, and reduce the ANB angle. Accordingly, three treatment goals were set.
1. Torque control while retracting the maxillary and mandibular anterior teeth
This included control of maxillary anterior teeth with the goal of retracting the maxillary anterior teeth with bodily movement; control of mandibular anterior teeth wth the goal of making the mandibular anterior teeth upright with lingual tipping around the root apex; and bowing effect prevention. The appliance used to prevent vertical bowing had vertical slots in the anterior region, horizontal slots in the molar region, and a ribbon arch wire. As shown in Figure 4a, lever arms were applied to provide traction toward the center of resistance of the maxillary anterior teeth roots. This was also planned to avoid a vertical bowing effect by retracting backward directly from the OAS, which was inserted at the maxillary median palate. In addition, a palatal bar was used in the maxilla to avoid, or at least minimize, horizontal bowing.
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
2. Vertical control
By means of the OAS located at the maxillary median palate, an attempt was made to avoid extrusion of the maxillary molar teeth and control intrusion. Class II elastic use was avoided because of the risk of mandibular molar tooth extrusion, causing mandibular clockwise rotation.
3. Anchorage control
To prevent mesial movement of the upper molars, an OAS was used that would have a direct effect during maxillary anterior teeth retraction. In this way, mesial movement of the molars could also be prevented for optimal stable fixation of both the maxilla and mandible during retraction to minimize the use of Class II elastics.
Treatment Alternatives
An alternative to using the ribbon-wise customized lingual appliance in the present case would have been an edgewise lingual appliance such as the Kurz 7th generation bracket (Ormco Corp., Glendora, CA, USA). With conventional appliances, torque loss in the anterior region can easily occur, so the arch wire would need an antibowing curve added and the anterior teeth would need to be retracted gently. However, there can be loss of torque control when retracting with an edgewise lingual bracket, particularly if it is not properly customized during bonding and if the brackets are not tied correctly. Even with a customized bracket system, third-order clearance can lead to the loss of torque control. It was reasoned that the Incognito system might control torque better because arch wires with adequate compensations can be ordered and because, although a vertical insertion wire might improve torque control, there will be loss of vertical control. A self-ligating system such as Harmony (American Orthodontics Corp., Ltd., Sheboygan, Wis) or the In-Ovation L (Dentsply International Inc., York, Pa) could have the same effect.
If an OAS could not have been used, high-pull headgear would have been needed for the long term and Class II elastics would have been used. In such a skeletal high-angle case, headgear would need to be used properly to avoid the possibility of clockwise mandibular rotation, which would have compromised the treatment goals. The likelihood of improper use of the headgear may rule out its use, but esthetics is another reason to do so.
Treatment Progress
Step 1: alignment of the maxillary and mandibular teeth and establishment of torque (8 months)
Ribbon-wise customized lingual appliances were applied in the maxilla and mandible. Half occlusal pads were set in the second lower molars to prevent bond failure. After applying the ribbon-wise customized lingual appliance on the maxilla and mandible and extracting both the maxillary and mandibular first premolars, levelling was initiated in the maxillary and mandibular arches with a 0.010-inch nickel titanium wire. Wire sizes were increased in small increments until confirming the establishment of torque with a 0.025 × 0.018 inch nickel titanium wire (Figure 5A).
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Step 2: retraction of the maxillary and mandibular anterior teeth en masse (maxillary 19 months, mandibular 6 months)
A mid-palatal miniscrew (Dual Top Auto Screw, ProSeed Corp., Seoul, South Korea; diameter 2.0 mm, length 6.0 mm) was placed in the mid-palatal area and healing was allowed for 3 months as described in several publications.9–12 Subsequently, lever arms were soldered to the anterior region with a 0.024 × 0.016 inch stainless steel wire. The height of the lever arm was set to the level of the plane between the OAS and center of resistance at the level of the upper central incisor, referring to cephalograms. An elastic chain was used from the OAS in the mid-palatal region to the lever arm for en masse retraction and to exert intrusive force on the anterior teeth with sliding mechanics. A 13° lingual root torque was set in the anterior region to prevent lingual tipping while retracting the teeth (Figure 4).
A palatal bar was used to prevent horizontal bowing and to help prevent lingual tipping and lingual movement of the maxillary molars. In addition, to achieve vertical control, intrusive force was applied to the maxillary first molars by using the OAS.
About 6 months after starting the retraction, the mandibular space had completely closed. Retraction was continued, and the right side of the space eventually closed completely 13 months after treatment started. However, there was still a 3-mm space on the left side, so dental and panoramic radiographs were obtained. The left side of the maxillary canine tooth root started approaching the base of the maxillary sinus, and an impacted gum was hindering retraction. Therefore, it was decided to continue en masse retraction of the anterior teeth after gum surgery; space closure was completed 19 months after the initial retraction. Thus, the side effects of vertical bowing and horizontal bowing were kept to a minimum (Figure 5B).
Step 3: detailing and finishing (maxillary 6 months, mandibular 19 months)
The 0.025 × 0.017 inch β III-Ti wires were used in both the maxillary and mandibular arches, and these were then sized up to 0.0182 × 0.0182-inch β III-Ti wires for maxillary detailing and final finishing. Specifically, small bends were added to an arch wire and religated for suitable torque control, tooth axis, and in–out adjustment. Buttons were added to correct molar rotation on the maxillary second molars. Finally, after 2 years and 9 months of active treatment, the brackets were removed from the maxilla and mandible (Figure 5C).
Treatment Results
Frontal facial examination after completing treatment showed complete resolution of mentalis strain in the lips that was present at the initial diagnosis. The patient could close her lips normally (Figure 6).
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Intraoral findings showed improvement of both the crowded teeth and labial tipping of the maxillary and mandibular anterior teeth. The maxillary and mandibular dental midlines coincided. Periodontal tissue health was maintained without gingival recession. A Class I molar relationship was established on both sides, with reductions in overjet and overbite from +6.0 mm to +2.5 mm and from 0 mm to +2.0 mm, respectively (Figure 7). The panoramic radiograph showed that root parallelism was established except for the upper lateral incisors, and the level of alveolar bone and periodontal tissue were maintained. Although small amounts of root resorption were noted at the maxillary anterior teeth (which were shorter from the outset), the maxillary left canine tooth roots approached close to the base of the maxillary sinus during anterior teeth retraction (Figure 8). A lateral cephalogram showed improvements in the SNA from 85.0° to 84.5°, SNB from 79.0° to 79.5°, and ANB from 6.0° to 5.0°. FMA was reduced from 33.5° to 33.0°, and SN to MP was reduced from 40.5° to 40.0°. These results indicate that there was no clockwise rotation of the mandible, which readily occurs in high-angle cases. Instead, slight mandibular anticlockwise rotation was noted, which resulted from attention to vertical control.
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Dental findings included a change in the anterior region of U1 to NA from 10.0 mm/37.5° to 2.0 mm/19.0°, L1 to NB from 13.0 mm/39.5° to 7.0 mm/29.5°, interincisal angle from 97.0° to 126.5°, and IMPA from 100.5° to 90.5°. The superimposition of pre- and posttreatment cephalometric tracings revealed that the anterior maxillary teeth had moved backward with intrusion and palatal tipping, and the mandibular anterior teeth had uprighted to the lingual side, thereby establishing the ideal positional relation of the anterior maxillary and mandibular teeth. Also, intrusion of the maxillary molars was about 0.5 mm and extrusion of the mandibular molars was 0.5 mm, indicating 0.5 mm mesial movement around the molar region. Thus, the treatment goals of anchorage control and vertical control were achieved (Table 1).
The treatment goals set according to the Level Anchorage System chart before treatment were to reduce the ANB from +6.0° to +4.0°, U1 to NA from 10.0 mm to 4.0 mm, and L1 to NB from 13.0 mm to 7.0 mm. These goals were mostly achieved, with an ANB angle of +5.0°, U1 to NA of 2.0 mm, and L1 to NB of 7.0 mm.
With regard to retention, the patient was instructed to wear soft retainers on both the maxilla and mandible all day, every day. The mandibular third molar on each side was extracted during retention. After 24 months of active retention, stable occlusion and periodontal health were maintained (Figures 9–12).
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
DISCUSSION
In general, when using edgewise lingual brackets, vertical and horizontal bowing effects should be monitored closely during anterior tooth retraction.3,4 In particular, the vertical bowing effect and open bite in the premolar region that occurs when retracting the maxillary anterior teeth often results in insufficient orthodontic outcomes (Figure 13A). Once these problems occur, recovery can take a long time.13–15 Vertical bowing is mainly caused by wire flexibility, which will exert some friction.16 Accordingly, a ribbon-wise customized lingual bracket that causes very little, if any, vertical bowing was used (Figure 13C).17–19 An OAS was used at the maxillary median palate, and lever arms provided the traction vector toward the center of resistance of the maxillary anterior tooth roots and then retraction proceeded from the deepest intraoral point so the maxillary anterior teeth could move freely with intrusion (Figure 4). Furthermore, when retracting the maxillary anterior teeth, the ribbon-wise customized lingual bracket avoids the loss of torque caused by the wire slipping out of the slots because it has anterior vertical slots, which help to minimize vertical bowing. This appears to be the best method of avoiding the most troublesome undesirable effects of lingual orthodontic treatment.
Citation: The Angle Orthodontist 88, 6; 10.2319/072717-498.1
A ribbon-wise customized lingual bracket helps prevent vertical deflection. However, because ribbon-wise wire is thinner, it causes horizontal bowing, such as lingual movement of the molars and lingual tipping during anterior maxillary teeth retraction (Figure 13D). Therefore, to prevent horizontal bowing, it is necessary to continuously wear a palatal bar on the maxilla and avoid lingual movement and lingual tipping of the maxillary molar teeth. By doing this, a constant maxillary intermolar width was maintained. Thus, for lingual orthodontic treatment, combined use of a ribbon-wise bracket, palatal bar, and OAS can be an effective method to avoid vertical and horizontal bowing.
Tipping of the upper laterals occurred. The advantage of vertical slots in the anterior region of the appliance is that this can control rotation and labiolingual tipping during retraction. However, mesiodistal tipping readily occurs if the tie is inadequate.
Because of the high angle in this case, an OAS was inserted at the median palate and treatment was continued, monitoring vertical and anchorage control closely. For vertical control specifically, to avoid clockwise rotation of the mandible, an OAS was used for intrusion of the maxillary molar teeth and to avoid extrusion during treatment.20–23 Because treatment could proceed without using Class II elastics, extrusion of the mandibular molars was kept to a minimum and counter-clockwise rotation of the mandible occurred. For anchorage control, traction force from the screw was used directly to avoid mesial movement of the molar teeth during maxillary anterior tooth retraction. Therefore, by preventing mesial molar movement, the maxillary anterior teeth were moved bodily and retracted. For the lingual bracket appliance, which requires vertical and anchorage control, the OAS embedded in the maxillary palatal region was effective. Therefore, this appears to be an excellent combination of appliances for a lingual treatment system (Figure 12).
CONCLUSION
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In this patient with skeletal high-angle maxillary protrusion, the anterior maxillary teeth were retracted with intrusion, and a slight mandibular anticlockwise rotation occurred. Using the combination of a ribbon-wise customized lingual bracket, a palatal bar, and an OAS, an excellent treatment outcome was achieved by preventing vertical and horizontal bowing effects often associated with lingual bracket treatment.
Pretreatment facial and intraoral photographs 20 years and 10 months old.
Pretreatment study models 20 years and 10 months old.
Pretreatment radiographs and tracing 20 years and 10 months old. (A) Lateral cephalogram. (B) Posteroanterior cephalogram. (C) Panoramic radiograph. (D) Pretreatment lateral cephalogram's tracing.
Retraction method for fully customized lingual bracket treatment with midpalatal miniscrew and palatal arch. (a) Lever arm. (b) Midpalatal miniscrew. (c) Transpalatal arch. (d) Center of rotation. (e) Elastomeric chains.
Intraoral photographs during treatment (treatment steps). (A) Step 1, leveling and alignment, torque establishment. (B) Step 2, anterior en masse retraction. (C) Step 3, detailing and finishing.
Posttreatment facial and intraoral photographs 23 years and 11 months old.
Posttreatment study models 23 years and 11 months old.
Posttreatment radiographs and tracing 23 years and 11 months old. (A) Lateral cephalogram. (B) Posteroanterior cephalogram. (C) Panoramic radiograph. (D) Posttreatment lateral cephalogram tracing.
Retention facial and intraoral photographs 26 years and 5 months old.
Retention study models 26 years and 5 months old.
Retention radiographs and tracing 26 years and 5 months old. (A) Lateral cephalogram. (B) Posteroanterior cephalogram. (C) Panoramic radiograph. (D) Posttreatment lateral cephalogram tracing.
(A) Pretreatment and posttreatment superimposition of cephalometric tracings on the Sella – Nasion plane (SN) plane at Sella turcica (S). (B) Pretreatment and posttreatment superimposition of cephalometric tracings on the Nasal floor (NF) at Anterior nasal spine (ANS) and on the mandibular plane at Menton (Me). (C) Posttreatment and retention superimposition of cephalometric tracings on the SN plane at S. (D) Posttreatment and retention superimposition of cephalometric tracings on the NF at ANS and on the mandibular plane at Me.
(A) Vertical bowing effect in horizontal slot bracket. (B) Horizontal bowing effect in horizontal slot bracket. (C) Vertical bowing effect in vertical slot bracket. (D) Horizontal bowing effect in vertical slot bracket.
Contributor Notes