Skeletal, Dental and Soft-Tissue Changes Induced by the Jasper Jumper Appliance in Late Adolescence

The Jasper Jumper™ (American Orthodontics, Sheboygan, Wis) is a fixed functional appliance which keeps the mandible in a protruded position by applying continuous, light forces. In correction of Class II malocclusions, it acts like headgear, activator or a combination of both according to how it is activated. In addition, it has the advantages of allowing the mandible lateral movements, good patient cooperation, and easy oral hygiene.1,2 

Even though previous studies have revealed the clinical outcome of the appliance, there is still some debate about how much correction is achieved by skeletal changes vs dentoalveolar changes. In 1994, Cope et al3 used a Jasper Jumper in 31 Class II patients and evaluated the craniofacial changes. They reported that the changes were mostly dentoalveolar rather than skeletal. According to their results, the maxilla underwent significant posterior displacement, the maxillary incisors retroclined, whereas the maxillary molars tipped distally. Also, a clockwise rotation of the mandible was evident and the mandibular incisors proclined significantly, whereas the mandibular molars tipped mesially.

Weiland and Bantleon4 studied 17 consecutive growing patients with Class II, division 1 malocclusions treated with Jasper Jumper appliances and reported that the correction of the malocclusion was achieved both by skeletal (40%) and dental (60%) changes. As with these findings, Kucukkeles and Orgun5 showed that the appliance produced mostly dentoalveolar changes.

In a case study by Mills and McCulloch,2 the investigators used a modified Jasper Jumper on a mixed dentition Class II patient. They reported that the effects of the appliance were largely dentoalveolar.

Covell et al6 investigated the effects of treatment with the Jasper Jumper in 36 growing Class II patients. They stated that the appliance corrected Class II discrepancies mostly through dentoalveolar changes and, to a limited extent, by restraint of forward maxillary growth.

Consequently, a review of the literature shows that functional appliances including the Jasper Jumper have similar effects on dentoalveolar and skeletal structures. Among these changes, the increased inclination of the lower incisors is usually considered an unfavorable effect of functional therapy. In our study, to prevent or minimize this effect we applied the Jasper Jumpers using sectional arches.

Considering these findings, this study was done to evaluate the skeletal, dental, and soft-tissue changes in late-adolescent patients treated with Jasper Jumpers applied with sectional arches.

The study sample consisted of 30 subjects (15 treated, 15 untreated) with skeletal and dental Class II malocclusions. The patient inclusion criteria were (1) skeletal and dental Class II malocclusion caused by retrognathic mandible, (2) normal or low-angle growth pattern, and (3) postpeak growth period. The study method was approved by the Yeditepe University Ethical Committee.

Skeletal age was used for selecting the patients, and postpeak growth period was defined by hand-wrist radiographic stages. The mean pretreatment age for the treatment group was 15.06 ± 0.96 years and 15.13 ± 0.81 years for the control group. The age range and the sex distribution of treatment and control groups are shown in Table 1.

In the treatment group, standard edgewise brackets and bands were placed with a transpalatal arch in the upper arch to increase stability. After leveling, 0.017 × 0.022–inch and 0.017 × 0.025–inch stainless steel continuous archwires were inserted and cinched back in the upper and lower arches, respectively. In the lower arch, 0.018 × 0.025/0.022 × 0.028–inch cross tubes (order-no. 480-000-00 Dentaurum, Ispringen, Germany) were crimped distal to the canine brackets. Jasper Jumper mechanics were applied on 0.017 × 0.025–inch stainless steel sectional arches connected to the lower continuous archwire by means of 0.018 × 0.025/ 0.022 × 0.028–inch cross tubes. The anterior tip of the sectional arch was adjusted to pass close to the deepest part of the vestibular sulcus, which coincided with approximately one crown length of extension from the enamel-cement border of the canine tooth. Because it was impossible to pass through the center of resistance of the lower dentoalveolar arch, this way provided the most practical way to pass the force as near as possible to the center of resistance of the lower dentoalveolar arch without causing an excessive irritation on the mucosal surface of the vestibular sulcus (Figure 1).

Jasper Jumpers were selected according to the manufacturer's instructions and connected to the lower arch through sectional arches inserted between the auxiliary tubes of the lower molar bands and cross tubes.

The patients were seen every four weeks, and the appliances were activated every eight weeks. The appliance was removed when a Class I or overcorrected Class I canine and molar relationship was achieved.

Our study was carried out on 75 lateral cephalometric films, 15 of which were taken off the treatment group before the leveling stage. These preleveling cephalometric films were used for comparison of IMPA values before leveling, at insertion, and removal of the Jasper Jumper. Half of the remaining 60 were taken before placement and after removal of the Jasper Jumper appliance in the treatment group and the other half at the beginning and six months later in the control group. The pretreatment and posttreatment radiograms of each patient were traced on acetate paper at the same time by one examiner to minimize any method error. Cephalometric landmarks and measurements can be seen in Figures 2–6. The reference lines used in this study were also used in previous investigations.7–10 

The nonparametric Wilcoxon signed rank test was used to assess the differences in each group. To evaluate the differences between the groups the Mann-Whitney U-test was used. A confidence level greater than 5% was considered statistically not significant.

To assess the magnitude of the method error, 20 randomly selected cephalograms were traced and measured again by the same examiner after an interval of 20 days. Paired t-tests and correlation analysis were used to evaluate the findings. The method error did not exceed 0.10 mm and 0.75° for the linear and angular measurements, respectively.

Statistical comparisons of pretreatment and posttreatment values of the groups are shown in Tables 2–8. Comparisons of the cephalometric measurements revealed that the appliance had only limited skeletal effect on the maxilla. In the control group, SNA show a statistically significant increase (Table 2) whereas, no significant change was present in the treatment group (Table 3). When the two groups were compared, a significant decrease was found as seen in Table 4. As with this finding, a significant decrease was found in the A-RL2 line.

When measurements of the mandible were evaluated, no significant change between two groups was found (Table 4). However, the ANB angle demonstrated a significant decrease when the two groups were compared (Table 4).

When the skeletal vertical parameters were evaluated, the only significant change was found in the ANS-Me/N-Me ratio.

In the treatment group, the dental changes caused by Jasper Jumper were evident. The upper incisors were significantly retroclined as compared with the control group (Table 4). The maxillary incisal tip moved distally 2.17 mm, whereas the incisor apex moved mesially 0.30 mm. Likewise, significant vertical movements of the upper incisors occurred (Table 7).

On the other hand, in the treatment group, the lower incisors showed significant proclination (Tables 3 and 7). The IMPA increased 7.33°, whereas L1-NB distance increased 1.96 mm (Table 3). The changes relative to reference lines also support these findings. The mandibular incisal tip moved forward 2.67 mm, whereas the incisor apex moved backward insignificantly. The vertical changes of the lower incisors displayed a greater movement in the opposite direction to the maxillary incisors (Table 7).

The upper molar showed significant backward movement with distal tipping and intrusion, whereas the lower molar displayed a significant mesial tipping movement (Table 7).

The dentoalveolar effects that occurred both in the upper and lower jaws produced a clockwise rotation of the occlusal plane (Table 4).

The decrease in overbite and overjet supports the incisor inclination variations caused by the appliance (Table 4).

Soft-tissue profiles improved significantly, reflecting the changes that took place in the dentoskeletal structures. When the two groups were compared, a significant increase was seen in the nasolabial angle. Likewise, the statistically significant decrease in the labialis superior-RL2 distance and lip strength also showed the retrusion of the upper lip (Table 4).

When the parameters related to the lower lip were evaluated, the decrease in the E line-labialis inferior distance showed that the lower lip moved forward as the lower incisors protruded.

This study evaluated the skeletal, dental, and soft-tissue changes in late-adolescent patients treated with Jasper Jumpers, applied with sectional arches. The study sample was composed of late-adolescent patients who were at the end of their postpubertal growth period. This group was chosen because it would benefit from the minimal residual growth and have minimal relapse due to growth and posttreatment dentoskeletal changes.

In the treatment group, the Jasper Jumper was applied using sectional arches to prevent or minimize the lower incisor protrusion.1,11 Because the lower arch was stabilized by cinching the archwire behind the molar tubes, the center of resistance of the lower dentoalveolar arch was located between the roots of the premolars. Sectional arches were used to decrease the distance to the center of resistance to reduce the moment produced by this force. This way, the force vector produced passed as near as possible to the center of resistance of the mandibular arch (Figure 7).

The results showed that Class II correction was achieved mostly through dentoalveolar changes and skeletal changes played a minor role (Figures 8 and 9). The results revealed that the appliance had a limited skeletal effect on the maxilla. This restraint of forward maxillary growth was the only skeletal change caused by the appliance. This finding is in accordance with the results of other investigators who showed that the appliance had a high-pull headgear effect on the maxilla.2,3,6,11,12 Weiland and Bantleon,4 on the other hand, found that the Jasper Jumper had limited effects on the maxilla and stated that the change at point A is the result of the retrusion of the upper incisors.

Unlike the maxilla, we did not find any significant effect on mandibular growth. Our results support the findings of Cope et al,3 Kucukkeles and Orgun,5 and Covell et al6 but contradict Weiland and Bantleon.4 This contradiction may be related to several factors such as age, variance of the sample groups, and different treatment mechanics.

The ANS-Me/N-Me ratio was the only vertical skeletal parameter found to be significant in our study. This decrease in the lower facial height may be related to the sample having a normal or low-angle growth pattern.

The findings related to the dentoalveolar structures showed significant treatment effects. Because the upper molars and incisors were blocked together, the upper incisors retroclined and the molars distalized considerably as a result of the high-pull effect of the appliance. This is in accordance with the findings of Mills and McCulloch,2 Cope et al,3 Weiland and Bantleon,4 Kucukkeles and Orgun,5 and Covell et al.6 In our study, the use of the segmental arches allowed the force vector to be shifted to a more vertical direction. Consequently, this vertical force vector tipped and intruded the upper molars significantly. Therefore, we think that Jasper Jumpers used with the segmental arches can be used in high-angle cases.

The increased lower incisor inclination is usually considered an unfavorable functional therapy effect. To prevent or minimize this effect, we applied the Jasper Jumpers using sectional arches, but a statistically significant protrusion still occurred at the lower incisors. This may be the result of the fact that it was impossible to pass through the center of resistance of the lower dentoalveolar arch without causing an excessive irritation in the vestibular sulcus of the patients. Our results are similar to those in the literature.2,3,5,6,13 The use of lower incisor brackets with negative torque values or having lingual crown torque at the lower anterior segment of the archwire may be further options to prevent the protrusion of the lower incisors.

Retrusion and extrusion of the upper incisors and distal tipping of upper molars, and protrusion and intrusion of the lower incisors and mesial tipping of the lower molars all point to a clockwise rotation of the occlusal plane. Cope et al,3 Weiland and Bantleon,4 Kucukkeles and Orgun,5 and Covell et al,6 all reported similar effects on the occlusal plane in their studies. In addition, the changes in overbite and overjet are consistent with our previous dentoalveolar findings. The correction of the overjet was achieved by combination of the retrusion of the upper incisors and protrusion of the lower incisors. These tipping movements were also effective at correcting the excessive overbite. Previous Jasper Jumper3–6 and Herbst14–18 studies also have shown significant decreases in overbite and overjet.

The change of the angulation of the incisors probably is due to the anchorage loss during treatment. Because this tipping movement occurs around their apices, extrusion and intrusion were observed at the upper and lower incisors, respectively. These findings reveal that the changes were mostly dentoalveolar rather than skeletal.

The soft-tissue parameters show that the Jasper Jumper favorably improved the profile. As the upper incisors retruded, the upper lip moved back and the lower lip was no longer captured behind the upper incisors. Moreover, the proclined lower incisors supported the lower lip. Lip strength decreased favorably because of the upper incisor retrusion. Previous studies show similar soft-tissue changes.5,13 

Most of the time, Class II surgery is indicated for the patients who have very little growth left similar to the patients in our study. De Clerck and Timmerman19 reported that there were no significant differences between patients treated with headgear-activator and the ones who had undergone mandibular advancement osteotomy. Likewise, Ruf and Pancherz14 suggested the use of functional therapy in some of the borderline cases instead of orthognathic surgery. Also, Weiland and Droschl13 used a Jasper Jumper in one of their cases who did not want surgery and received very satisfactory results. Taking these into consideration this treatment method could be an alternative to orthognathic surgery in some borderline Class II cases.

This study demonstrated the skeletal, dental, and soft-tissue effects of the Jasper Jumper used in late adolescence. The results revealed that, the appliance corrected Class II discrepancies mostly through dentoalveolar changes. Because the Jasper Jumper can successfully correct the soft-tissue profile in late-adolescent patients, it is suggested that this treatment method could be an alternative to orthognathic surgery in borderline Class II cases. However, further studies will be needed to evaluate the long-term effects and stability of the appliance used in young adults.