As

CLINICIAN’S CORNER 

Efficiency of a skeletonized distal jet appliance 

supported by miniscrew anchorage for 

noncompliance maxillary molar distalization 

Gero S. M. Kinzinger, a Norbert Gülden, b Faruk Yildizhan, c and Peter R. Diedrich d 

Homburg/Saar and Aachen, Germany 

Introduction: Conventional anchorage appliances rely exclusively on intraoral anchorage for noncompliance 

molar distalization. The partial coverage of the palate, in particular, often results in compromised oral hygiene. 

An innovative alternative combines a skeletonized distal jet appliance with 2 paramedian miniscrews for additional 

anchorage. The objectives of this study were to investigate the suitability of the skeletonized distal 

jet for translatory molar distalization and to check the quality of the supporting anchorage setup. Methods: 

Two paramedian miniscrews (length, 8-9 mm; diameter, 1.6 mm) were placed into the anterior area of the palate 

in 10 patients. Skeletonized distal jet appliances fitted with composite to the first premolars and the collars 

of the miniscrews were used for bilateral molar distalization, and the coil springs were activated with a distalization 

force of 200 cN on each side. Results: The study confirmed the suitability of the appliance for translatory 

molar distalization (3.92 6 0.53 mm) with slight mesial inward rotation (on average, 8.35 6 7.66 and 

7.88 6 5.50 ). The forces acting reciprocally on the anchorage setup were largely absorbed by the anchorage 

unit involving 2 anchorage teeth and 2 miniscrews. Significant anchorage loss, in the form of first premolar mesialization 

of 0.72 6 0.78 mm, was found. Conclusions: The skeletonized distal jet appliance supported by 

additional miniscrew anchorage allows translatory molar distalization. Although the anchorage design combining 

2 miniscrews at a paramedian location and the periodontium of 2 anchorage teeth does not offer the 

quality of stationary anchorage, it achieves greater molar distalization in total sagittal movement than conventional 

anchorage designs with an acrylic button. (Am J Orthod Dentofacial Orthop 2009;136:578-86) 

As alternatives to the compliance-dependent headgear 

for maxillary molar distalization, appliances 

have been described that are worn only intraorally, 

are placed to remain fixed temporarily, and make 

treatment success independent of patient compliance. A 

major advantage for the patient, when comparing them 

with the extraorally anchored headgear, is the lack of esthetic 

impairment. One of these appliances is the distal jet 

(American Orthodontics, Sheboygan, Wis). 1-3 The distal 

jet has, as its active components, 2 coil-spring systems 

that must be placed palatally. Loading the compression 

coil springs generates forces that preformed bands abduct 

a Professor, Department of Orthodontics, University of Saarland, Homburg/Saar, 

Germany. 

b Orthodontist, Department of Orthodontics, University of Saarland, Homburg/ 

Saar, Germany. 

c Orthodontist, Department of Orthodontics, RWTH Aachen, Aachen, Germany. 

d Professor and head, Department of Orthodontics, RWTH Aachen, Aachen, 

Germany. 

The authors report no commercial, proprietary, or financial interest in the 

products or companies described in this article. 

Reprint requests to: Gero Kinzinger, Department of Orthodontics, University 

of Saarland, Kirrberger Strabe 1, D-66421 Homburg/Saar, Germany; e-mail, 

Kinzinger@kfo-homburg.de. 

Submitted, June 2007; revised and accepted, October 2007. 

0889-5406/$36.00 

Copyright Ó 2009 by the American Association of Orthodontists. 

doi:10.1016/j.ajodo.2007.10.049 

onto the permanent first molars and act distally. When it 

is accurately manufactured in the dental laboratory and 

anatomic relationships are favorable, the resultant lines 

of force are close to the centers of resistance of the molars. 

Therefore, as opposed to cervical headgear, which 

can achieve fractionated molar distalization only with 

combined coronal tipping and subsequent root uprighting, 

the biomechanics of the appliance should in theory 

enable it to perform almost translatory molar distalization. 

4 The reciprocally acting forces are therapeutically 

undesired and must be absorbed by intraoral anchorage. 

Conventionally, the anchorage setup of a distal jet appliance 

includes periodontal anchorage combined with further 

intraoral anchorage support: several teeth of the 

maxillary dentition are laced to an acrylic palatal button, 

by using bands or occlusal wire rests, to form an anterior 

anchorage unit. Because of the temporary partial coverage 

of the palate, in particular, which restricts hygiene 

capacity, this anchorage design has been the subject of 

critical discussion. 5 Furthermore, certain dentition stages 

do not allow sufficient periodontal anchorage. 6 

As an alternative, a skeletonzed distal jet appliance 

supported by additional miniscrew anchorage could be 

used. 5,7 It allows noncompliance molar distalization in 

the maxilla even with limited dental anchorage quality 

578

American Journal of Orthodontics and Dentofacial Orthopedics Kinzinger et al 579 

Volume 136, Number 4 

and, by dispensing with an acrylic button, also achieves 

better hygiene of the palatal mucosa. 

In an in-vitro study, Kinzinger and Diedrich 4 demonstrated 

that the distal jet coil-spring systems allowed 

almost translatory tooth movement in the sagittal plane 

with uprighting effects on the dental root over a simulated 

distalization section of 3 mm based on a constant 

distalization force of 200 cN, combined with a mesial 

tipping moment. In the transverse plane, a force constantly 

directed toward the buccal aspect and a mesially 

rotating moment resulted in combined buccal movement 

and therapeutically undesired mesial and inward 

rotation of the permanent first molar. 

The aims of this in-vivo study were to investigate 

clinically the efficiency of the skeletonized distal jet 

supported by additional miniscrew anchorage and to 

compare the outcomes with the in-vitro series of measurements. 

A review of the literature resulted in a discussion 

of the share of anchorage loss in the total 

movement in the sagittal plane, hence of the quality of 

the miniscrew-supported periodontal anchorage setup, 

when comparing it with other conventional intraorally 

anchored, noncompliance distalization appliances. 

MATERIAL AND METHODS 

A skeletonized distal jet appliance was placed for bilateral 

molar distalization in the maxilla in 10 patients 

(8 girls, 2 boys; average age, 12 years 1 month) with 

dentoalveolar Class II malocclusion and dental archlength 

discrepancies. The mean treatment duration 

was 6.7 months. Of the total of 20 second molars, 11 

were germinating, and 5 were erupting. Only 4 had 

already reached the occlusal plane. 

For the distal jet used in this study, the palatal acrylic 

button was removed as a means of anchorage. Instead, the 

modified appliance was anchored skeletally to 2 miniscrews 

placed into the palate at a paramedian location 

and, additionally, dentally to 2 occlusal rests. In terms 

of laboratory technique, this meant that prefabricated telescope 

spring assemblies, whose wings were bent distally 

to form occlusal rests, were connected to each other by using 

a soldered or laser-welded transverse wire (Fig 1). 

Every patient’s bone supply in the anterior area of the 

palate was analyzed on lateral cephalographs to determine 

the length of the screw shaft. After a preoperative 

mouth rinse with 0.1% chlorhexidine gluconate solution 

and local terminal anesthesia with an adrenalin-free 

anesthetic, 2 miniscrews with neck and collar (length, 

8-9 mm, diameter, 1.6 mm; Forestadent, Pforzheim, 

Germany; or System Dual Top, Jeil Medical Corporation, 

Seoul, South Korea) were placed at a paramedian location 

in the anterior area of the palate (at the line of the first 

Fig 1. Skeletonized distal jet appliance supported by 

additional miniscrew anchorage: treatment of a girl 

aged 11 years 1 month; duration of distal jet treatment, 

5 months. A, Occlusal view immediately after skeletonized 

distal jet placement: in terms of laboratory technique, 

prefabricated coil-telescope systems, the wings 

of which are bent distally to form occlusal rests, are connected 

to each other with a wire soldered to them. This 

transverse connecting wire is fitted dorsally to the miniscrew 

necks. B, Occlusal view after molar distalization: 

clinical assessment shows bodily molar distalization 

and spontaneous second premolar dental drifting. 

premolars) with a manual screwdriver and adequate 

sodium chloride cooling. No predrilling was performed. 

All miniscrews were tested for primary stability by using 

a probe; they were loaded a week after placement. 

Skeletonized distal jet appliances were attached to the 

premolars by using occlusal wire rests and to the necks of 

the miniscrews with transverse wires fitted dorsally and 

secured with composite. The occlusal rests also resulted 

in transverse reinforcement of the appliances. Accordingly, 

the anchorage setup consisted of a periodontal

580 Kinzinger et al American Journal of Orthodontics and Dentofacial Orthopedics 

October 2009 

UR2 

UL2 

A 

N 

S 

ANS-PNS´ 

UR6 

mb 

cf 

db 

UL6 

Ar 

PNS 

A 

ANS 

Go-Me´ 

MPR 

Fig 2. Cast analysis (changes in the horizontal plane): 

angular and linear measurements to determine changes 

in the transverse width of the dental arch and rotation of 

the first molars. 

Go 

B 

footing with the added support of miniscrews. The wings 

of the arc sections, which represent a bayonet bend, were 

fitted into the palatal sheaths of the molar bands. Then the 

loaded coil systems, with superelastic compression 

springs, were activated by fitting attachment screws dorsally 

with a distalization force of 200 cN for each system 

and reactivated every 4 weeks. 

To verify molar movement in the horizontal plane, 

plaster dental casts were taken at the start of treatment 

(T1) and after distal jet appliance removal (T2). The 

changes near the molars were assessed by measuring 

corresponding casts with a digital sliding caliper. Objects 

of analysis were changes in length of the supporting 

zone, increase or decrease of the transverse width of the 

dental arch at the line of the first molars, and extent and 

kind of tooth rotation. For every cast, the distance from 

the distal point of contact of the lateral incisor to the mesial 

point of contact of the first molar and, bilaterally, the 

distance from the lowest point of the central fossa to the 

mesiobuccal and the distobuccal cusps of the first molar 

were registered. In addition, the angles between a line 

running through the mesiobuccal and distobuccal cusps 

and the midpalatal raphe were measured (Fig 2). 

The cephalographs taken at T1 and T2 were analyzed 

to determine changes in the following parameters (Fig 3). 

1. SNA: the angle between the anterior cranial base 

and the deepest point of the ventral concavity of 

the maxilla. 

2. SNB: the angle between the anterior cranial base 

and the deepest point of the ventral concavity of 

the mandible. 

3. S-N/ANS-PNS: the angle between the anterior 

cranial base and the palatal plane. 

B 

P 

S 

Pt 

PNS 

4. ANS-PNS/Go-Me: the angle between the palatal 

plane and the mandibular plane. 

5. Björk’s summation angle: the sum of the saddle 

angle (NSAr), the articular angle (SArGo), and 

the gonial angle (ArGoMe). 

Me 

Or 

N 

ANS 

Fig 3. Cephalometric analysis (changes in the sagittal 

plane): angles and distances registered on the lateral 

cephalograph before and after molar distalization: A, 

skeletal angular and linear values; B, dental angular 

and linear values.



6. S-Go:N-Me: the facial height ratio (posterior face 

height to anterior face height). 

7. U1-CEJ/PTV: the distance from the maxillary 

central incisor to the pterygoid vertical. 

8. U4-CEJ/PTV: the distance from the maxillary first 

premolar to the pterygoid vertical. 

9. U5-CEJ/PTV, the distance from the maxillary second 

premolar to the pterygoid vertical. 

10. U6-CEJ/PTV: the distance from the maxillary first 

molar to the pterygoid vertical. 

11. U1/ANS-PNS: the angle between the maxillary 

central incisor and the palatal plane. 

12. U1/SN: the angle between the maxillary central 

incisor and the anterior cranial base. 


first premolar and the palatal plane. 

14. U4/SN: the angle between the maxillary first premolar 

and the anterior cranial base. 


second premolar and the palatal plane. 

16. U5/SN: the angle between the maxillary second 

premolar and the anterior cranial base. 


first molar and the palatal plane. 

18. U6/SN: the angle between the maxillary first 

molar and the anterior cranial base. 

19. U1-CEJ/ANS-PNS: the distance from the maxillary 

central incisor to the palatal plane. 

20. U4-CEJ/ANS-PNS, the distance from the maxillary 

first premolar to the palatal plane. 


second premolar to the palatal plane. 


first molar to the palatal plane. 

SNA, SNB, S-N/ANS-PNS, ANS-PNS/Go-Me, 

Björk’s summation angle, and the facial height ratio 

were measured or computed to verify any skeletal 

changes. 

In the sagittal plane, the relative incisor and first premolar 

mesial movement, hence the anchorage loss, and 

the relative second premolar and first molar distal movement 

in relation to the pterygoid vertical (U1-CEJ/PTV, 

U4-CEJ/PTV, U5-CEJ/PTV, and U6-CEJ/PTV) were 

determined. The respective points of reference for the 

measurements were the cementoenamel junction 

(CEJ) on the longitudinal axis of the teeth. Growthinduced 

changes (increase of 1 mm per year) were taken 

into account. 

The amounts of labial tipping of the incisors and 

first premolars and distal tipping of the second premolars 

and first molars were determined based on the 

angles between the longitudinal tooth axis and, respectively, 

the palatal plane or the anterior cranial base (U1/ 

ANS-PNS, U1/SN; U4/ANS-PNS, U4/SN; U5/ANS- 

PNS, U5/SN; U6/ANS-PNS, U6/SN). 

Potential tooth intrusions and extrusions were verified 

in the palatal plane (U1-CEJ/ANS-PNS, U4-CEJ/ 

ANS-PNS, U5-CEJ/ANS-PNS, and U6-CEJ/ANS- 

PNS). 

Statistical analysis 

Statistical computations were performed with SPSS 

software (version 14, SPSS, Chicago, Ill). Casts and lateral 

cephalographs were traced twice at a 4-week interval. 

If values deviated, the means of both measurements 

were fed into the statistical analysis. Then the arithmetic 

mean and the standard deviation were computed for every 

variable used in the in-vivo measurements, and the 

changes of each variable from T1 to T2 were statistically 

analyzed with a 1-sample t test. Thereby, we determined 

which effective changes were therapeutically 

induced by the treatment as evidence against the null 

hypothesis. Differences with a probability of error less 

than 5% (P \0.05) were considered statistically significant. 

RESULTS 

Metrical assessment of the maxilla casts before and 

after molar distalization with a skeletonized distal jet 

appliance showed the following dental position changes 

of the permanent first molars (Table I). 

The supporting zones increased by 4.01 6 0.63 mm 

in the first quadrant and 3.64 6 0.69 mm in the second 

quadrant. The transverse widths of the dental arch increased 

by means of 1.79 6 1.08 mm between the mesiobuccal 

cusps, 2.58 6 0.69 mm between the central 

fossae, and 3.03 6 0.68 mm between the distobuccal 

cusps; this indicates both expansion and mesial inward 

rotation of the permanent first molars. When we looked 

more closely, the permanent first molars of the first 

quadrant had rotated mesiopalatally and distobuccally 

by a mean 8.35 6 7.66 and those of the second quadrant, 

by 7.88 6 5.50 . All position changes of the 

permanent first molars were significant. 

Skeletal assessments showed that the cranial base 

remained constant, with changes of the SNA angle of 

only a mean 0.19 6 0.80 and the SNB angle of only 

a mean 0.13 6 0.82 . The positional relationships of 

the palatal plane to the anterior cranial base and to the 

mandibular plane were virtually unchanged. Björk’s 

summation angle changed by only 0.73 6 1.26 during 

molar distalization, and the facial height ratio changed 

by 0.58% 6 1.51%. All registered skeletal changes 

during treatment were not significant (Table II).


October 2009 

Table I. Changes in permanent first molar position induced by distal jet therapy in the horizontal plane 

Cast analysis n T1 mean T1 SD T2 mean T2 SD DT1-T2 mean DT1-T2 SD Significance 

UR2 distal-UR6 mesial (mm) 10 20.80 2.04 24.81 2.34 –4.01 0.63 

UL2 distal-UL6 mesial (mm) 10 21.17 1.90 24.81 2.08 –3.64 0.69 

‡ 

Mesiobuccal cusp tips UR6-UL6 (mm) 10 50.80 2.16 52.59 1.28 –1.79 1.08 

† 

Central fossa UR6-UL6 (mm) 10 45.80 2.36 48.39 2.04 –2.58 0.69 

‡ 

Distobuccal cusp tips UR6-UL6 (mm) 10 53.06 1.70 56.09 1.49 –3.03 0.68 

‡ 

Tooth UR6 rotation ( ) 10 12.86 6.15 21.21 6.28 –8.35 7.66 * 

Tooth UL6 rotation ( ) 10 13.43 4.29 18.93 5.94 –7.88 5.50 * 

Determination of type of molar rotation: angle between midpalatal raphe and a line running through the mesiobuccal and distobuccal cusps of the 

molars; for DT1-T2 (value before distalization) – (value after distalization): positive value 5 mesiobuccal and distopalatal rotation, negative value 5 

mesiopalatal or distobuccal rotation. 

*P \0.05; † P \0.01; ‡ P \0.001. 

‡ 

Table II. Skeletal angular and linear measurements 

Cephalometric analysis n T1 mean T1 SD T2 mean T2 SD D T1-T2 mean D T1-T2 SD Significance 

Skeletal-angular 

SNA ( ) 10 83.55 2.63 83.36 2.78 0.19 0.80 NS 

SNB ( ) 10 79.83 3.42 79.70 3.27 0.13 0.83 NS 

S-N/ANS-PNS ( ) 10 5.56 1.92 5.18 1.53 0.38 1.18 NS 

ANS-PNS/Go-Me ( ) 10 24.20 4.31 25.08 4.14 –0.88 1.09 NS 

Björk’s summation angle ( ) 10 389.61 3.29 390.34 3.49 –0.73 1.26 NS 

Skeletal-linear 

S-Go:N-Me (%) 10 67.49 2.79 66.91 2.60 0.58 1.51 NS 

NS, Not significant. 

In the area of the CEJ, the permanent first molars 

were distalized by a mean of 3.92 6 0.53 mm and intruded 

by a mean of 0.16 6 0.26 mm. At the same 

time, they experienced distal tipping of 2.79 6 2.51 

in relation to the palatal plane and 3.00 6 2.31 in relation 

to the anterior cranial base. The second premolars, 

which were not part of the anchorage setup, drifted distally 

after the molars by 1.87 6 0.74 mm, elongating by 

0.42 6 0.41 mm and tipping, in relation to the respective 

reference planes, by 3.00 6 2.69 and 3.21 6 2.86 . 

The first premolars, included in the anchorage setup, 

mesialized by 0.72 6 0.78 mm, extruded by 0.14 6 0.14 

mm, and, at the same time, tipped by 1.15 6 2.98 in 

relation to the palatal plane and by 0.79 6 2.23 in relation 

to the anterior cranial base. The central incisors 

were protruded by 0.36 6 0.32 mm and extruded by 

0.14 6 0.29 mm, and showed slight labial tipping 

of 0.57 6 0.79 in relation to the palatal plane and 

0.64 6 0.75 to the anterior cranial base. 

All linear dental movements in relation to the pterygoid 

vertical, the extrusion of the premolars, and the 

angular dental position changes of the second premolars 

and first molars were significant (Table III). 

The total movement in the sagittal plane was 4.28 6 

0.51 mm (cumulating molar distalization and central incisor 

protrusion) or 4.64 6 1.06 mm (cumulating molar 

distalization and first premolar mesialization). Based on 

the values obtained for the permanent first molars— 

distalization length of a mean 3.92 6 0.53 mm—molar 

distalization represents 91.71% 6 7.32% and 86.56% 

6 13.21%, respectively, of the total sagittal movement 

(Table IV). 

DISCUSSION 

The outcomes confirm the efficiency of the distal jet 

in clinical applications. Cast registrations showed that 

the supporting zone had increased, and that a therapeutically 

desired widening of the dental arch, as well as mesial 

inward and distal outward rotations of the molars, 

had occurred. The biomechanical explanation of this effect 

is that force is applied palatally from the center of 

resistance of the molars. In theory, a toe-in bend would 

be appropriate to compensate for this effect, but it results 

in friction in the guide tubes of the appliance. 

This effect was verified with the casts used and by an 

in-vitro registration. The resultant adhesive effect expressing 

this friction reduced the distalization force substantially 

and, accordingly, would be an obstacle for 

distalization of the molars. Therefore, a toe-in bend 

should not be used, although it would be therapeutically 

desirable. 4 After the distal jet treatment, the molars



Table III. Dental angular and linear measurements 

Cephalometric analysis n T1 mean T1 SD T2 M T2 SD D T1-T2 M D T1-T2 SD Significance 

Dental-angular 

U1/AN-PNS ( ) 10 107.93 4.80 108.50 4.94 –0.57 0.79 NS 

U1/SN ( ) 10 101.86 5.28 102.50 5.45 –0.64 0.75 NS 

U4/AN-PNS ( ) 10 91.86 6.01 90.71 6.11 1.15 2.98 NS 

U4/SN ( ) 10 85.86 7.61 85.07 7.37 0.79 2.23 NS 

U5/ANS-PNS ( ) 10 82.29 4.71 79.29 5.62 3.00 2.69 * 

U5/SN ( ) 10 76.50 5.37 73.29 5.26 3.21 2.86 * 

U6/ANS-PNS ( ) 10 75.36 3.82 72.57 4.04 2.79 2.51 * 

U6/SN ( ) 10 69.71 4.79 66.71 4.35 3.00 2.31 * 

Dental-linear 

U1-CEJ/PTV (mm) 10 52.54 2.94 52.90 2.98 –0.36 0.32 * 

U4-CEJ/PTV (mm) 10 38.47 3.37 39.19 3.78 –0.72 0.78 * 

U5-CEJ/PTV (mm) 10 31.21 3.11 29.34 3.00 1.87 0.74 

† 

U6-CEJ/PTV (mm) 10 22.59 3.31 18.67 3.11 3.92 0.53 

‡ 

U1-CEJ/ANS-PNS (mm) 10 17.96 2.62 18.10 2.44 –0.14 0.29 NS 

U4-CEJ/ANS-PNS (mm) 10 15.79 1.53 15.93 1.55 –0.14 0.14 * 

U5-CEJ/ANS-PNS (mm) 10 14.59 2.06 15.01 1.97 –0.42 0.41 * 

U6-CEJ/ANS-PNS (mm) 10 13.16 1.78 13.00 1.65 0.16 0.26 NS 

*P \0.05; † P \0.01; ‡ P \0.001; NS, not significant. 

Table IV. Proportion of maxillary molar distalization in 

total movement in the sagittal plane 

Cephalometric analysis n D T1-T2 mean D T1-T2 SD 

Dental-linear (mm) 

U1-CEJ/PTV (mm) 10 –0.36 0.32 

U4-CEJ/PTV (mm) 10 –0.72 0.78 

U6-CEJ/PTV (mm) 10 3.92 0.53 

Total sagittal movement 1-6* 10 4.28 0.51 

Total sagittal movement 4-6 † 10 4.64 1.06 

Calculation of ratio (%) 

Proportion of molar 10 91.71 7.32 

sagittal movement 1-6 ‡ 

distalization in total 

Proportion of molar 


sagittal movement 4-6 § 10 86.56 13.21 

*Total movement in the sagittal plane 1-6 5 [U1-CEJ/PTV] 1 [U6- 

CEJ/PTV]; † Total movement in the sagittal plane 4-6 5 [U4-CEJ/ 

PTV] 1 [U6-CEJ/PTV]; ‡ Calculation: proportion of molar distalization 

in total sagittal movement 1-6 5 100 3 (U6-CEJ/PTV)/([U1- 

CEJ/PTV] 1 [U6-CEJ/PTV]); § Calculation: proportion of molar distalization 

in total sagittal movement 4-6 5 100 3 (U6-CEJ/PTV)/ 

([U4-CEJ/PTV] 1 [U6-CEJ/PTV]). 

should be derotated with an appropriate appliance, such 

as a transpalatal bar or a bi-helix. 

We found, during lateral cephalograph analysis, unlike 

the results of the in-vitro analysis, that the permanent 

first molars experienced slight dental crown 

tipping in the sagittal plane rather than root uprighting. 4 

The cause of this might be that the patients’ palatal 

vaults were not deep enough to enable placement of 

the loaded coil systems at the level of the center of resistance 

of the molars. Also, the location of the center of 

resistance can be determined only by approximation. 

Moreover, the respective development stages of the second 

molars might influence the extent of distal tipping 

of the first molars. In most patients in this study, the second 

molars were germinating or erupting. In a clinical 

study with pendulum appliances, Kinzinger et al 8 

showed that the extent of distal tipping is relatively 

greater when the second molars are only germinating. 

This phenomenon can be explained as follows: a germinating 

second molar has the same effect as a lever pivot 

point on the permanent first molar to be distalized; the 

first molar, when reacting to distalization, tips over the 

second molar germ. As its root is developing and the 

permanent second molar is erupting, the point of contact 

between the 2 molars gradually moves coronally. The 

tendency for the first molar to tip thereby decreases. 

Conventionally, the anchorage setup of exclusively 

intraorally anchored appliances for noncompliance molar 

distalization combines an acrylic button on the palatal 

mucosa with using the periodontium of anchorage 

teeth. The disadvantages of this kind of anchorage include, 

in particular, restrictions to hygiene 5 and contraindications 

based on certain dentition stages and local 

situations. 7 Moreover, it must be discussed how far 

the anchorage effect of an anteriorly placed Nance 

button potentially relies only on hydrodynamic interactions 

due to the resilient mucosa. Thereby it would be 

a disqualifying design for stationary anchorage designs, 

and hence must not be overestimated in terms of anchorage 

quality. 5


October 2009 

Table V. Studies using different conventionally intraorally anchored appliances for maxillary molar distalization 

Author/reference 

Distalization appliance 

Treatment Soft-tissue 

subjects (n) support* Dental anchorage † 

Share of molar 


movement (%) 

Angelieri et al 31 Hilgers pendulum with uprighting activation 22 NP 2 B PM1 35.7 PM1, 45.4 I 

2 OW PM2 

Bolla et al 32 Distal jet 20 NP 2 B PM1 71.1 PM1 

Bondemark and Kurol 33 Magnets 10/10 NP 2 B PM2 70 I 

Bondemark et al 34 Magnets/supercoils 18/18 NP 2 B PM2 53.7 I/62.7 I 

Bondemark and Kurol 35 Magnets/supercoils 18/18 NP 2 B PM2 55 I/59 I 

Bondemark 36 Magnets/NiTi coils 21/21 NP 2 B PM2 59.1 PM1, 

57.8 I/67.6 PM1, 61.9 I 

Brickman et al 37 Jones jig 72 NP 2 B PM2 55.7 PM1 

Bussick and McNamara 38 Hilgers pendulum 101 NP 4 OW 76.0 PM1 

Byloff and Darendeliler 39 Hilgers pendulum 13 NP 4 OW 70.9 PM1 

Byloff et al 40 

Hilgers pendulum with 

20 NP 4 OW 64.2 PM1 

uprighting activation 

Chaques-Asensi and Kalra 41 Hilgers pendulum 26 NP 2 B PM1 70.6 PM1; 71.8 I 

Chiu et al 42 Distal jet/Hilgers pendulum 32/32 NP 2 B PM2/4 OW 51.8 PM1/81.3 PM 

Fortini et al 43 FCA 17 NP 2 B PM2 70.2 PM1; 76.9 I 

Fuziy et al 44 Hilgers pendulum 31 NP 2 B PM1 63.5 PM1 

2 OW PM2 

Gosh and Nanda 45 Hilgers pendulum 41 NP 4 OW 56.9 PM1 

Gulati et al 46 Jones jig 10 NP 4 B PM1 and PM2 55.0 PM1 

Haydar and Üner 47 Jones jig 10 NP 2 B PM2 45.0 PM1 

Joseph and Butchart 48 Hilgers pendulum 7 NP 4 OW 57.9 I 

Kinzinger et al 50 Pendulum K 50 NP 4 OW 72.5 I 


Kinzinger et al 50 Pendulum K 30 NP 4 OW 76.3 PM1; 74.2 I 


Mavropoulos et al 52 Jones jig 66 NP 2 B PM2 47.8 PM2; 51.3 I 

Ngantung et al 53 Distal jet 33 NP 2 B PM2 44.9 PM2 

Nishii et al 54 Distal jet 15 NP 2 B PM2 63.1 PM1; 61.5 I 

Papadopoulos et al 55 Modified jig 14 NP 2 B PM2 35 PM1, 37.8 I 

NiTi, Nickel-titanium; FCA, first-class appliance. 

* Intraoral anchorage designs: NP, Nance pad; B, premolar bands anchored to the Nance pad with connecting wires; OW, occlusal wire rests anchored 

to the Nance pad; PM1, first premolars; PM2, second premolars. 

† With specific reference: PM1, first premolar; PM2, second premolar; I, central incisor. 

Alternative anchorage components for molar distalization 

appliances include titanium miniscrews of small 

diameter and orthodontic implants of short length. In 

clinical application, short endosseous titanium implants 

provide quality stationary anchorage. 9-13 So-called miniscrews, 

placed at a location paramedian to the palatal 

suture in the patients in this study, are less costly and, 

compared with short implants, can be placeed and removed 

with minimal invasion. 

Most clinical and experimental studies as well as 

case reports on anchorage with miniscrews deal with 

primary stability, rate of loss, and patient comfort of 

these implants. 14-27 Only a few studies provide information 

on position stability of these anchorage components 

during orthodontic treatment. Liou et al 28 and Kinzinger 

et al 29 examined the anchorage quality of miniscrews 

subjected to orthodontic forces and concluded that, 

although they allowed stable anchorage, they did not 

fully maintain their positions under continuous loading. 

According to Park et al, 30 some mobility in orthodontic 

screw implants does not necessarily mean that the outcome 

is compromised. Rather, even minimally mobile 

miniscrews can provide sufficient anchorage quality. 

Our results show that the described miniscrew-supported 

periodontal anchorage does not allow anchorage 

of stationary quality. Nevertheless, it offers essential advantages 

compared with conventional anchorage designs; 

by limiting the number of occlusal rests to 2, 

treatment is possible even with fewer teeth, with lower 

anchorage quality in the supporting zone. Spontaneous 

distal drifting of the second premolars, which were 

not part of the anchorage setup, reduced the length of 

the subsequent treatment phase. In this study, the second 

premolars drifted distally after the molars almost bodily



by 1.87 6 0.74 mm. In the subsequent active distalization 

of the anterior dentition, the molars can be 

anchored to the miniscrews. 

Various studies, in which different intraoral appliances 

with conventional anchorage designs (acrylic 

button and 2-4 anchorage teeth) were used for molar 

distalization, give the share of molar distalization in 

the total movement as 35% to 81.3% (Table V). 8,31-55 

The miniscrew-supported periodontal anchorage of 

the skeletonized distal jet used in this study, on the other 

hand, allows greater molar distalization in the total 

movement—91.71% and 86.56%; this is a reason that 

this innovative anchorage design makes sense as a treatment 

alternative. 

CONCLUSIONS 

In the sagittal dimension, the miniscrew-supported 

distal jet appliance allows almost translatory molar distalization. 

Because of the palatal force application from 

the center of resistance of the molars, the teeth experience 

therapeutically undesired mesial inward and distal 

outward rotation. 

The incorporation into the anchorage setup of 2 

miniscrews at paramedian locations has the following 

advantages compared with conventional anchorage designs: 

by dispensing with an acrylic button that covers 

the palate, hygiene of the palatal mucosa improves. Additional 

dental anchorage requires only 2 teeth. The second 

premolars, which are not part of the anchorage, can 

drift distally spontaneously under the pulling effect of 

the transseptal fibers. 

Although a miniscrew-supported periodontal anchorage 

of a skeletonized distal jet appliance does not offer stationary 

anchorage quality, it allows a greater percentage of 

molar distalization in the total movement than do conventional 

anchorage designs with an acrylic palatal button. 

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