Non-extraction treatment of severe crowding with pendulum appliance.

An extraction case was planned for non-extraction treatment using pendulum appliance and the effect of appliance was evaluated in a 14-year-old girl with a severe maxillary and mandibular crowding followed by non-extraction fixed appliance preadjusted edgewise appliance mechanotherapy. Total treatment time was for 22 months. The obtuse nasolabial angle was maintained intact. Correction of crowding, co-ordinated arch forms was achieved with molar distalization. The impetus on soft-tissue paradigm is stressed in this case report and pendulum appliance can indeed boost our clinical acumen and swing our priorities toward non-extraction treatment.

Maxillary molar distalization for non-extraction treatment of class II patients has become increasingly popular in recent years.[12] The pendulum appliance is a hybrid that uses a large Nance acrylic button in the palate for anchorage, along with 0.032" titanium molybdenum alloy (TMA) springs that deliver a light, continuous force to the upper first molars without affecting the palatal button.[2] Thus, the appliance produces a broad, swinging arc or pendulum of force from the midline of the palate to the upper molars.

Bussick and McNamara,[3] studied the largest sample of subjects treated with pendulum appliance to date, suggested moving the first molars distally before the eruption of second molars to avoid significant increases in mandibular plane angle and lower anterior facial height. Most studies on treatment effects induced by either the distal jet or pendulum appliance have been limited to the analysis of post-distalization changes. There is a little information about outcomes after comprehensive orthodontic treatment including a second phase of therapy with fixed appliances.[45] The aim of this case report is to evaluate the effect of pendulum appliance in a case of severe crowding and treatment effects were analyzed both at the end of distalization and at the end of comprehensive orthodontic treatment comprising fixed appliance therapy.

CLINICAL HISTORY

An adolescent girl, aged 14 years [Figure 1a-h], had a chief complaint of irregular upper and lower front teeth with no abnormal oral function and no dental or skeletal discrepancies. She had a symmetrical face, competent lips, no gingival exposure on smiling, relatively straight profile and an obtuse nasolabial angle. There was a bilateral end-on molar relationship and class I canine relationship on the right side. Maxillary left canine was not positioned in the arch and was buccally blocked out. Bilaterally the maxillary second molars were in buccal crossbite. The lower right lateral incisor was displaced lingually. The panoramic radiograph showed all third molars were present and unerupted.

Figure 1

(a-h) Pre-treatment photographs

The maxillary and mandibular dental arch length discrepancy was − 10 mm and − 7 mm respectively. There was a Bolton's discrepancy of 2.5 mm maxillary anterior excess, especially due to the increased mesio distal width of maxillary lateral incisors. The maxillary midline was deviated 2 mm to the right side. The over jet was 2 mm and overbite was 5 mm. There was 2 mm gingival recession in relation to 41, but without any attachment loss. Composite analysis revealed no skeletal discrepancy. Facial height and growth pattern were normal [Figure 2a and b].

Figure 2

(a and b) Pre-treatment radiographs

Treatment objectives

The main treatment objectives were to relieve the maxillary and mandibular dental crowding, preserve good facial profile and give patient an esthetic smile. In spite of the severe crowding, her nasolabial angle was obtuse and lips were competent. Although space requirement is indicating more toward extractions, molar distalization was opted followed by non-extraction fixed appliance mechanotherapy.

If the only consideration for this patient had been alignment, the treatment plan could have included extraction of maxillary and mandibular second premolars at the least. Extractions would have allowed alignment of the dentition easily, but may not have enhanced facial esthetics.

Treatment progress

Summary of treatment progress:

Bonding of maxillary arch, 0.014” Heat Activated NiTi (HANT) on 0.022” Preadjusted Edgewise Appliance (PEA) with Mclaughlin Bennet Trevisi (MBT) prescription

2 weeks later: Pendulum appliance was delivered as described by Hilgers,[2] with a modification of cross over wires onto occlusal surface of both the premolars. The appliance was stabilized with glass ionomer cement onto the premolar occlusal surfaces. With the appliance in place, the 0.032” TMA springs with 60° activation were placed in the lingual sheaths on maxillary first molar bands [Figure 3]

Figure 3

Pendulum appliance cemented in maxillary arch

8 months: Active molar distalization phase. Further Activation of Pendulum appliance was stopped and it's maintained passively for the purpose of retention as soon as bilateral super class I molar relation was achieved [Figure 4]. At the end of this phase, cephalogram and orthopantamogram (OPG) were taken with initiation of lower bonding

Figure 4

Post-molar distalization photographs

12 months: U/L 19 × 25” HANT given after proximal slicing of upper laterals mesially, distally resulting in 2 mm of space gain. Maxillary left canine was not engaged, maxillary 2nd molars which were in buccal cross bite were bonded

15 months: Left upper canine was brought into occlusion with piggy back 0.014” HANT on 17 × 25” SS base arch wire. Distalization of premolars, carried out by open coil springs placed distal to left upper lateral insicor. Pendulum appliance was removed and 12-O-tetradecanoylphorbol-13-acetate was placed, for anchorage requirements

18 months: Co-ordination of dental arches [Figure 5a-e]

Figure 5

(a-e) Pre-finishing photographs

20 months: Finishing, detailing with lateral cephalogram and OPG

22 months: Debond [Figure 6]

Figure 6

(a-h) Post-treatment photographs

Retention by essix clear retainers, vacuum formed with 0.75 mm bio-acryl sheet.

Long-term results

The fixed appliance was removed after a period of 22 months. Good intercuspation was achieved. No further gingival recession was noted in relation to lower right lateral incisor. Clear retainers made of bioacry l 0.75 mm sheet were vaccum formed and the patient was instructed to wear full time. Overall, the treatment result was pleasing in delivering a vibrant and consonant smile to the patient preserving the pleasing facial profile of the patient.

Discussion

Many intraoral molar distalization appliances have been designed to minimize or eliminate the need for patient co-operation. Pendulum appliances though, succeeded by many non-compliant molar distalization appliances stands its test in delivering a range of forces for distalization and a broad, swinging arc or pendulum of force from the midline of the palate to the upper molars. Severe crowding of the upper and lower anterior teeth, buccally blocked out canine, buccal crossbite of second molars, predispose the case for extraction protocol. The decision to go ahead with molar distalization was taken up as there was no gross skeletal discrepancy and the patient still has some residual growth left. There was severe crowding, but an obtuse nasolabial angle is present along with retroclined incisors. Though studies showed that, molar distalization, is best achieved when the second molars are not erupted,[6] a recent understanding on molar distalization by Kinzinger,[7] who stated that, molar distalization is even possible in fully erupted second molars and it is the angulation of second molar and third molar tooth bud, which is a detrimental factor and not the eruption status that is necessary, to take a decision whether to opt for molar distalization or not. The advantage with Pendulum appliance is its design and the customized fabrication, which can be performed with ease as compared to other non-compliance molar distalization appliances, which may require stocking of inventory. Thus, pendulum appliance can be a part of cost-effective treatment plan.

The treatment results achieved in this case report can be summarized [Table 1] as Skeltal changes: During the distalization phase of treatment, there was an increased mandibular growth that was associated with a more protruded chin, in spite of slight downward and backward rotation of mandible and resultant increase in lower anterior facial height. These findings were expected with molar distalization.[8] The bite opening might have been caused by extrusion of posterior teeth or maxillary molars being distalized into the arc of closure. The amount of changes in vertical skeletal relationships during molar distalization is comparable with those reported in previous studies.[3]

Table 1

Comparison of cephalometrics

Very little change occurred in the inclination of the mandibular plane at the end of the 2 phase treatment. This partly can also be attributed to the differential mandibular growth which could have occurred during the 22 month treatment period. Overall, the entire treatment shows a favorable response on the mandibular growth in improving the mild class II skeletal relationship.

Dentoalvelolar changes

A super class I molar relationship was achieved during the active 8 month therapy with pendulum appliance for molar distalization. The effect of cementing the appliance with glass ionomer cement applied onto premolars was detrimental in creating the posterior open bite for the unimpeded molar distalization. The molars moved posteriorly by 3 mm overall after the uprighting, during the consolidation phase, which was sufficient to achieve bilateral class I, molar and canine relationship. The amount of tipping initially was greater immediately post-distalization and later was normalized. The overall degree of tipping was acceptable. However, the anchorage loss in the anterior region was of concern in terms of mild proclination of upper anteriors by 2 mm and 5°. The overall increase in the upper anterior proclination can be partly attributed to the expression of torque with the PEA appliance and the incisors were retroclined pre-treatment. The difference between planned incisor position and the incisor angulation achieved was 2 mm and 2°, which is in the normal range keeping in view the pleasing esthetics and an obtuse nasolabial angle post-treatment. The final root paralleling, which was achieved is a good aspect as far as retention is concerned. This stresses the proper study of assessing the treatment results only after a comprehensive fixed appliance therapy post-molar distalization.

Conclusion

Pendulum appliance is a non-compliant intraoral molar distalization appliance commonly used in the treatment of class II malocclusions. This case report provides a valuable insight in opting for a non-extraction therapy. The swing to non-extraction therapy has to be more enhanced when there is an obtuse nasolabial angle and pleasant profile to start with in spite of severe crowding. Molar distalization can be a valuable option in delivering the treatment for the above conditions.

Our findings can be summarized as follows

Molar distalization achieved was 3 mm overall and there was a significant correction in the crowding.

There was a mild increase in the resultant upper incisor angulation than the planned incisor position, but obtuse nasolabial angle remained unchanged resulting in a pleasing profile and esthetics.

A pleasant and consonant smile arc was achieved.