3D-Printed Versus Band-and-Loop Versus Denovo Space Maintainers in Primary Dentition.

3D-Printed Custom Versus Conventional Band-and-Loop Versus Chairside Denovo Space Maintainers in the Primary Dentition: A Randomized Controlled Trial Protocol

Purpose of the Study When a child loses a "baby" molar early due to a cavity or injury, the surrounding teeth can shift into the empty space. This often blocks the permanent adult tooth from growing in correctly. To prevent this, dentists use a small metal device called a space maintainer.

This study aims to find out which of three different types of space maintainers lasts the longest, is most comfortable for the child, and is most efficient for the dental office to provide.

The Three Study Groups

Children in this study are randomly assigned to one of three groups:

1. 3D-Printed Custom Group: The dentist takes a digital picture (scan) of the child's mouth instead of a traditional mold. A custom-fit appliance is then 3D-printed using a specialized, medical-grade clear material.
2. Conventional Band-and-Loop Group: This is the traditional method. The dentist takes a physical mold of the teeth, which is sent to a laboratory. The child usually has to return for a second appointment a week later to have the metal appliance glued into place.
3. Denovo Chairside Group: This uses a kit of pre-made metal parts. The dentist selects the best fit and assembles the appliance right at the chairside, allowing it to be placed during a single visit.

What is Being Measured?

Researchers are following the children for 12 months to track:

Survival: Which appliance stays glued in and doesn't break most effectively?

Time: How much time does the dentist spend making and fitting the appliance?

Comfort: How much discomfort or pain did the child feel during the process?

Health: Does the appliance cause any irritation to the gums or surrounding teeth?

Who Can Participate? The study includes children between the ages of 5 and 10 who have lost at least one primary (baby) molar early and need a space maintainer to protect their future adult smile.

Importance of This Research By comparing these three methods, this study helps dentists understand if newer technologies, like 3D printing or pre-made kits, are better or more convenient than the traditional lab-made metal loops used for decades. This information will help families choose the best treatment for their children.

Clinical Workflow and Device Fabrication

The trial compares three distinct manufacturing and clinical delivery pathways for pediatric space maintenance:

1. 3D-Printed Custom Workflow (Experimental Arm)

   Data Acquisition: Digital impressions are captured using a high-precision intraoral scanner (3Shape TRIOS).

   Design Phase: The STL files are imported into CAD software (exocad), where a custom space maintainer is designed with a specific focus on anatomical adaptation to the abutment tooth and the edentulous ridge.

   Manufacturing: Appliances are fabricated via Stereolithography (SLA) using a Form 3B+ printer with BioMed Clear Resin. Post-processing includes a 20-minute isopropyl alcohol wash and 60 minutes of UV curing at 60°C to ensure biocompatibility and optimal mechanical properties.

   Delivery: The printed appliance is bonded using a light-cured orthodontic adhesive.

2. Conventional Band-and-Loop Workflow (Active Comparator)

   Clinical Phase: Traditional alginate impressions are taken and poured with dental stone to create a physical working model.

   Laboratory Phase: A stainless steel band (3M Unitek) is fitted to the abutment tooth on the model. A 0.036-inch stainless steel wire is contoured to the ridge and silver-soldered to the band.

   Delivery: The appliance is polished and cemented in a subsequent clinical appointment using glass ionomer cement.

3. Denovo Chairside Workflow (Active Comparator)

Selection: A prefabricated kit (Denovo Dental) is used to select a band size that fits the abutment tooth.

Assembly: A pre-formed wire loop is selected and adjusted for length at the chairside. The loop is mechanically secured to the band using the system's specialized crimping and locking mechanism, eliminating the need for soldering or laboratory delays.

Delivery: The assembled appliance is cemented during the same appointment as the initial measurement.

Randomization and Standardization Participants are allocated 1:1:1 using a computer-generated randomization sequence. To ensure consistency, all clinical procedures-including tooth preparation, scanning, and cementation-are performed by a group of calibrated pediatric dentists following a standardized protocol. For the 3D-printed group, resin batches and printer calibration are monitored weekly to ensure material integrity.

Inclusion Criteria:

1. Children aged 5 to 10 years
2. Premature unilateral loss of at least one primary first or second molar
3. Radiographically confirmed developing permanent successor at Nolla developmental stage 4 to 7
4. Parent or legal guardian able and willing to provide written informed consent, and child able to provide age-appropriate assent

Exclusion Criteria:

1. Systemic disease affecting bone metabolism or tooth development
2. Clinically significant mesiodistal space loss at screening, defined as greater than 3 mm
3. Poor oral hygiene precluding band placement, defined as a full-mouth plaque score greater than 50%
4. Known allergy or hypersensitivity to stainless steel or resin components
5. Current participation in another interventional clinical trial