Non-extraction treatment with non-compliance maxillary molar distalisation

Introduction and historical review

Molar distalisation has a long history in orthodontics. Molar distalisation, as a treatment strategy, has been in practice with the success of Kloehn headgear and facebow, in the 1960s, in bringing about restraint on the sagittal growth of the maxilla and creating distal movement of maxillary molars in young, growing children. The primary indication for the use of Kloehn headgear is to intercept the development of class II malocclusion and thereby correct growing superior protrusion. However, the success of this appliance is ‘compliance dependent’.

Several other methods have also been used for the distal movement of maxillary molars, such as force generated using class II elastics directed to drive the maxillary dentition distally either through a jig suggested by Tweed or distalising devices such as 3D Wilson arch ^, ( Fig. 60.1 ).

Mandibular molar distalisation is required for the correction of class III malocclusion.

Era of intraoral molar distalisation with anchorage derived from teeth and palate

The search for a simple, non-compliance system of intraoral molar distalisation continued in the late 1970s and 1980s. Repelling magnets, ^, open-coil springs and superelastic wires were tested. ^, Japanese NiTi coils were used to distalise the first molar using mesial arch segment anchorage by Gianelly, and later, superelastic NiTi wires were activated and held with a specially designed crimped stop on the principles used by Locatelli et al.

Dr. Bondemark used repelling magnets to distalise the maxillary molar. However, they proved to be less effective than previously known methods. The magnets have several other disadvantages. The most critical aspect lies in adjusting the optimum distance between two repelling magnets. In addition, the magnets are bulky, and oral hygiene maintenance is cumbersome ( Fig. 60.2 ).

Hilgers, in 1992, introduced the use of distal force application on the palatal aspect of maxillary molars with a spring designed in titanium–molybdenum alloy (TMA) wire that was anchored in a palatal acrylic button. He called it pendulum appliance ( Fig. 60.3 ). The pendulum appliance used a modified Nance button anchored to premolars to derive the anchorage. TMA wire springs embedded in acrylic, when activated by 30 degrees, generated a constant force of 100 g, and at 60-degree activation, 200+ g force was sufficient to distalise the maxillary first molars.

The Pendulum-X appliance features an expansion screw built into the wire framework to allow for simultaneous transverse expansion of the maxilla ( Fig. 60.4 ).

During the same years, Jones and White introduced a buccal sectional assembly, which is popularly called Jones jig (1992) ^, .

Kalra introduced a buccally placed TMA loop for molar distal movement, also known as the K loop (1995).

Distal Jet, a modification of spring-loaded appliance from modified Nance button, was introduced in 1996 ( Fig. 60.5 ). Around those years, Fortini et al. (1999) used a combination approach from palatal as well as buccal, for distal bodily movement of the molar and called it first class appliance (FCA). Keles and Sayinsu introduced what they called intraoral bodily molar distaliser again from the palatal approach ( Fig. 60.6 ).

Since then, several modifications and improvements in appliances have been introduced, on to buccal, palatal and into a combination of buccal and palatal devices. Intraoral molar distalisation is now an accepted modality of treatment in orthodontic practice for the treatment of select cases. Various intraoral molar distalising appliances are tabulated in Table 60.1 .

TABLE 60.1

Classification of intraoral molar distalisation appliance

1.
Dental/conventional anchorage derived appliances:
- a.
  Buccal appliance:
  - •
    Jigs with class II elastics
  - •
    Repelling magnets
  - •
    NiTi springs and wires
  - •
    Jones jig
  - •
    K-loop
- b.
  Palatal appliance:
  - •
    Pendulum appliance
  - •
    Modifications of pendulum appliance
  - •
    Fixed piston appliance by Greenfield
  - •
    Distal Jet spring-loaded palatal appliance
- c.
  Buccal and palatal appliance:
  - •
    First class appliance (FCA)
2.
Skeletal anchorage using miniscrew implant/skeletal anchorage system:
- a.
  Palatal anchorage:
  - •
    Bone-anchored pendulum appliance (BAPA)
  - •
    Miniscrew implant–supported pendulum appliance
  - •
    Palatal-supported all wire framework Beneslider
- b.
  TAD-supported buccal jig:
  - •
    TAD-supported long arm buccal jig
  - •
    TAD-supported Jig on the fixed appliance
  - •
    K connector–supported Jones jig
3.
Combination of buccal and palatal application of force:
- a.
  Dual-force distaliser supported with Nance button anchored with TAD

Era of bone screw–anchored, miniscrew implant (MSI)–supported molar distalisation and skeletal anchorage

Bone screws, including MSIs, have recently been introduced to orthodontic practice as devices for molar distalisation and skeletal anchorage systems (SAS). These tools are designed to distalise the maxillary and mandibular molars, as well as the entire arch. Clinicians have explored their use from both buccal and palatal approaches.

The buccal-sourced skeletal systems include: (i) Skeletal anchorage system by Sugawara et al., (ii) Bollard miniplate-supported buccal force by Cornelis and De Clerck and (iii) Miniscrew-anchored sliding jig by Lim and Hong ( Fig. 60.7 ).

The palatal bone-anchored devices for molar distalisation are as follows: bone-anchored pendulum appliance (BAPA) by Kircelli et al. ^, ( Fig. 60.8 ): (i) Miniscrew implant–supported distalisation (MISDS) system by Papadopoulos ( Fig. 60.9 ); (ii) Miniscrew-supported skeletonised Distal Jet appliance by Kinzinger et al. ^, ( Fig. 60.10 ); (iii) Miniscrew-supported dual-force distaliser by Oberti et al. ( Fig. 60.11 ); (iv) MISDS by Beneslider ( Fig. 60.12 ) and (v) Skeletal Frog appliance by Ludwig et al.

Indications of intraoral molar distalisation

In general, children with normal or horizontal growth patterns are more suitable for maxillary molar distalisation. Maxillary molar distalisation is considered with the objectives to treat less than half-cusp class II malocclusion or gain space to resolve superior protrusion or crowding up to 4 mm ( Table 60.2 ). Intraoral non-compliance molar distalisation is possible with either palatally or buccally acting appliance.

TABLE 60.2

Major indications and contraindications of maxillary molar distalisation

S. no.	Indications	Contraindications
1.	Molar distalisation is indicated to normalise the mesially migrated maxillary molars due to their premature mesial drift. Such a situation may exist unilaterally or bilaterally.	Discrepancy of more than 4 mm and where the profile is not favourable.
2.	To correct class II dental relationship of no more than half-cusp severity and mild maxillary dentoalveolar protrusion. The mandibular arch either does not require or need minimal orthodontics. The profile of such a patient is normal or slightly protrusive at the upper lip due to the dental/dentoalveolar protrusion.	Subjects with high Frankfurt mandibular plane angle (FMA) or vertical growth trend.
3.	In class I occlusion patients, molar distalisation may be indicated to gain space to resolve minor crowding in the anterior segment. Up to 4 mm of crowding can be addressed with molar distalisation.	Dental open bite tendency. Molar distalisation is associated with some amount of distal tipping and extrusion action which might have adverse effects on occlusion. It may lead to anterior open bite in patients with vertical growth trend.
4.	To obtain space for erupting canines, more so by utilising the leeway space and minor distal movement of the molars.
5.	To recover anchorage loss during active orthodontic treatment.

Palatal acting appliances include the pendulum appliance and its infinite variations, including three-dimensional (3D) metal printed appliances.

Clinical protocol in the use of molar distalisation appliance

The successful outcome of molar distalisation (MD) depends significantly on the careful selection of suitable cases. Therefore, it is imperative to prepare a complete set of orthodontic records and conduct a thorough diagnosis to formulate a comprehensive treatment plan. Prior to initiating distal movement of molars, a comprehensive postdistalisation should be available. Molar distalisation represents only one aspect of the overall treatment plan. The treatment sequence involves appliance fabrication, cementation activation, molar stabilisation and post-distalisation mechanics.

Palatally acting appliances

Pendulum appliance

Hilgers introduced the pendulum appliance in 1992. The appliance used a modified Nance button for anchorage and TMA wire springs to apply force from the palatal side for molar distalisation ( Figs 60.13 and 60.14 ).

The pendulum appliance consists of anchorage derived from premolars. Bands on first premolars and soldered palatal extensions of 0.036 in. stainless steel (SS) wire is embedded in an acrylic button in the rugae area and contour of the anterior palate. The maxillary first molars are provided with a welded lingual tube on each of the molar bands.

Two palatal springs are made of 0.032 in. TMA wire are embedded in the Nance button on either side of the midline. The right and left pendulum springs consist of a re-curved molar intrusion wire, a small horizontal adjustment loop, a close helix and a loop for retention in the acrylic button. The activated springs deliver 150 g of force sufficient to distalise the molar partly by bodily and partly by tipping movement. The rate of molar distal movement can be evaluated at the cervical margin of the molar to a distance from the second premolar.

Pendulum intraoral molar distalisation appliance

To begin the process, the first molar bands are selected and welded with buccal and lingual tubes. The lingual sheaths are 0.036 in. in dimension. The well-fitted molar bands are then used to make an alginate impression. Afterwards, the bands are removed and transferred to the impression and the study model.

In the case of erupted premolars, bands are also prepared on the first and second premolars and transferred to the model. Molar distalising spring(s) are then fabricated in 0.32 in. TMA wire embedded in acrylic. The Nance button is attached to a wire framework that is either soldered to the premolars or bonded to their occlusal surfaces.

To make the spring as effective as possible, it is bent parallel to the mid-palate line. The springs are extended as close to the centre of the palatal button as possible to maximise their range of motion, allow easier insertion into the lingual sheaths, and reduce forces to an acceptable range.

The spring has a re-curved molar insert segment, a horizontal adjustment loop, a closed helix and a segment with a loop that can be held in the acrylic part of the Nance button. After that, the Nance button appliance is prepared in acrylic with a wire framework of the premolars and two springs embedded in the acrylic. The acrylic button can be fabricated with high-strength cold-cure acrylic.

The anterior part of the pendulum appliance, which is the Nance button and anchorage unit of the premolars, is fixed first, followed by the cementation of the molar bands. Figure 60.13 (A-G) illustrate steps in the fabrication and insertion of PA in mouth.

Appliance activation

After the pendulum is inserted, the spring arm of each spring is checked for activation and gently inserted into the lingual sheath. The pendulum spring is pushed forward with fingers, the mesial end of the loop is held with Weingart pliers, and the spring end is seated in the lingual sheath. The horizontal adjustment loop allows for some lingual compression of the spring during placement.

On insertion with 60 degree activation, about one third of activation is lost and remaining activation produces a force of 150-200 grams. The molars move distally following the arc of the spring, which opens towards the midline of the appliance.

Reactivation of the appliance is done every 3–4 weeks. The spring is activated by holding the helix with pliers, pushing it distally towards the midline, and then being re-inserted.

The potential consequences of palatal spring activation, which moves in an arc, are as follows: (i) palatal movements of the molars and (ii) distal tipping of the molars.

As the molar is driven distally into a wider intermolar width of the palate, it also moves on an arc towards the midline of the palate, in other words, towards cross-bite. This tendency can be counteracted by opening the adjustment loop slightly for expansion and molar rotation.

Molar stabilisation

Following distalisation, molar(s) can be stabilised in a new position with a fully bonded fixed appliance. An omega loop mesial to molars works well to prevent their mesial movement.

Hilgers has suggested using Insta Nance, a 0.036-in. preformed lingual crib inserted into lingual tubes. Insta Nance stabilises the molars and allows the upper premolars to drift distally as the trans-septal fibres recoil and reorient into a newly acquired position of the first molars. A preformed lingual crib (0.036 in. SS wire) is inserted into the lingual sheaths. A small ball of TRIAD (Dentsply Sirona, Charlotte, North Carolina, USA) light-cured acrylic is formed over the retention loop of the crib against the vertical slope of the palatal vault, smoothed with a moistened finger and cured with a light source for 1 min. Hilgers strongly recommends Insta Nance, for he found it to be the most stable and dependable way to maintain molar positions. Insta Nance connecting with the distalised first molars can also be prepared in the clinical laboratory immediately after the pendulum appliance removal.

An upper utility arch in a fully bonded arch is also a good option for maintaining distalisation. Here, the tip-back bands apply distal thrust to the molars.

The other option involves using a fixed appliance with molar stops supported by the Insta-Nance appliance for intra-arch space closure and retraction of the anterior segment.

Fig. 60.14 shows the treatment of a young girl who had a mid-class II molar and canine relations, and a lack of lip seal. She received non-extraction treatment using a pendulum appliance, followed by fixed appliance therapy using a standard edgewise 0.022 in. appliance. The post-treatment follow-up revealed a well-balanced soft tissue and skeletal profile with a class I molar and canine relationship. Throughout the follow-up, her class I, canine and molar relations, interdigitation and parabolic arch forms were maintained. The post- and follow-up cephalograms showed significant improvement in her skeletal and soft tissue profiles, lip posture and lip contours.

Efficacy of pendulum appliance

A recent systematic review has reported that the pendulum appliance showed mean molar distalisation of 2–6.4 mm, distal tipping of molars from 6.67 to 14.50 degrees and anchorage loss with mean premolar and incisor mesial movement of 1.63–3.6 mm and 0.9–6.5 mm, respectively.

Pendulum X and pendulum K

When maxillary expansion is indicated in a narrow maxillary arch, the molar distalisation and maxillary expansion can be carried out simultaneously. An expansion screw can be incorporated into the centre of the Nance button ( Fig. 60.4 ). The screw activation is initiated after a week. The expansion schedule usually involves a one-quarter turn every three days to produce a slow, stable expansion.

The standard pendulum appliance was modified by Kinzinger et al. by integrating a distal screw into its base and by a pre-activation of the pendulum springs for sustained bodily distalisation. Activation of the spring provides a continuous force of 150 g. Pendulum-K appliance is expected to minimise or prevent altogether all the side effects through the incorporation of a distal screw into the Nance button, which is further supported by the initial application of an uprighting and a toe-in bend in the region of the pendulum springs. ^,

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Tags: Kharbanda's Orthodontics: Diagnosis and Management of Malocclusion and Dentofacial Deformities, OP Kharbanda

May 10, 2026 | Posted by drzezo in Orthodontics | 0 comments