Palatal expansion using the MARPE appliance: Macono Orthodontic and Dental Laboratories’ use of the Dentaurum hyrax® screw and tomas® system

Palatal expansion using the MARPE appliance: Macono Orthodontic and Dental Laboratories’ use of the Dentaurum hyrax® screw and tomas® system

Palatal expansion represents a specialised area within orthodontics, aimed at correcting a variety of clinical indications, including:
Transverse maxillary deficiency (crossbite, constricted palate)
Dental crowding due to reduced arch perimeter
Obstructive airway issues where maxillary constriction contributes to nasal airway limitation
Craniofacial asymmetry if maxillary width is part of the discrepancy
Preparing the maxilla for orthognathic surgery or complex orthodontic treatments where skeletal expansion is required

The Mini‑Screw Assisted Rapid Palatal Expander (MARPE) is a hybrid skeletal‑anchored device designed for non‑surgical maxillary expansion in adolescent and adult patients. Its design utilises temporary anchorage devices (TADs; mini-screws) anchored in the palate, which allows for more basal or skeletal force transmission, reducing dental tipping, minimising periodontal side effects, and improving skeletal expansion even when the midpalatal suture is partially or fully maturated.

Macono Orthodontic and Dental Laboratories is a high-quality dental lab specialising in Orthodontic solutions for its customers across Australia, New Zealand, and Oceania. Owner and director Charlie Sara sustains an acute focus on customer experience and the development of his team with the ultimate aim of delivering the highest-quality products. This focus has resulted in near-continuous growth of the business across decades and long-term business relationships with many of the industry’s most outstanding practitioners.

Macono: Making the MARPE appliance
We spoke to Lester Prentice, senior technician at Macono, about his approach to creating MARPE appliances using the Dentaurum tomas® system.

Lester began by explaining the growing demand for MARPE appliances. “Today, the most significant driver of MARPE appliances in clinical practice is a greater awareness and treatment of sleeping disorders in general health. Palatal expansion is an effective treatment for many indications of Obstructive Sleep Apnoea (OSA). Its use is growing”.

“The manufacture of MARPE appliances begins with us receiving a maxillary scan or impression from a clinical practice. In this case example, we received a scan from the renowned orthodontist, Dr Shimanto Purkayastha. From this scan, we create a Maxillary study model that is a precise replica of the entire upper jaw structure.

“Dr Shimanto required a four-pin anchored MARPE appliance. A four-pin anchored MARPE uses four tomas® EP TADs, two each in the anterior and posterior of the maxilla.

The first step in making the appliance is setting the tomas® RPE eyelet positions, which will determine the location of the tomas® TADs in the patient’s palate. The optimum location of these is 3mm either side of the mid-palatal suture. The anterior eyelets and pins are located at the level of the first premolar, and the posterior eyelets and pins are located at the level of the second molar.

“The aim is to select a location that combines a robust anchorage point where there is the greatest bone thickness.

Access to CBCT imaging to assess suture maturation, bone density, palatal anatomy (thickness, cortical plates) is very helpful prior to selecting MARPE.

“The second consideration is to determine the vertical level of the eyelets. The optimum position is level with the occlusal plane.

“The tomas® RPE eyelets are positioned on the model using the specially designed tomas® RPE support tool. This tool, supplied with eyelets, is thoughtfully designed and easy to use.

“The appliance is then manufactured by working through steps to ensure the highest possible clinical precision, strength and patient comfort.

The anterior tomas® RPE eyelets are laser-welded to the Dentaurum hyrax® click RPE Screw, and the posterior eyelets are attached using interconnecting heavy-gauge wire to provide the necessary palatal depth with high strength. Laser Welding is completed using the Dentaurum desktop Compact Laser Welder.

The same heavy-gauge wire is then used to fabricate wire legs, which are laser-welded to the expansion screw. The hyrax® expansion screw, tomas® RPE eyelets, and legs form the appliance’s primary foundation.

Occlusal support structures are created using bands, splints or occlusal rest seats. The structure is laser-welded to the appliance arms.
Several critical factors are involved in the fabrication of the appliances, which impact clinic efficacy, durability, and patient comfort. These can be broadly grouped into design, precision, and strength. Each of these is interdependent in achieving the highest level of appliance quality.

Design is a collaborative process between the clinician and the lab technician. The appliance’s design is critical to clinical efficacy and durability.

Precision is a product of the technician’s skill in conjunction with the quality of materials and tools used. No two appliances are ever the same, so while the techniques are replicated, the skill deployed in wire bending and welding is crucial.

Strength is achieved through the combined effects of design, materials, the quality of the expansion screw, and the precision with which the appliance is made.

“Of course, the highly developed skills of the treating clinician are central to clinical success. We are fortunate to regularly work with Dr Shimanto and other orthodontists when making these complex appliances. It provides a purpose filled with immense satisfaction.

Dentaurum products used
tomas® RPE eyelets
hyrax® click RPE screws
tomas® EP TADs
Dentaurum Wire
Orthocryl® acrylic
Dentaurum Bands
desktop Compact Laser Welder