Clinical Outcomes and Satisfaction of Stainless Steel vs Bioflx Crowns in Primary Molars

January 20, 2026 updated by: PHAM LE ANH THY

Comparison of Clinical Outcomes, Parent and Child Satisfaction Between Stainless Steel Crowns and Prefabricated Hybrid (Bioflx) Crowns in Primary Molars

The goal of this clinical trial is to learn if the Bioflx crown (a tooth-colored material) is as effective as the standard stainless steel crown for treating severely decayed baby back teeth in children aged 4 to 10 years old. The study also aims to evaluate parent and child satisfaction with these restorative options.

The main questions it aims to answer are:

  1. Is the Bioflx crown as effective as the stainless steel crown in terms of durability, staying in place, and protecting the tooth from new decay?
  2. Does the Bioflx crown maintain better gum health and cause less wear on the opposing teeth compared to the stainless steel crown?

Researchers will compare the Bioflx crown to the stainless steel crown to see which material works better to restore tooth function and health.

Participants will:

  1. Receive one Bioflx crown and one stainless steel crown on similar teeth on opposite sides of the mouth.
  2. Visit the clinic for two separate appointments, spaced 1 to 2 weeks apart, to have the crowns placed.
  3. Return for checkups at 3 months and 6 months so researchers can examine the health of the teeth and gums.
  4. Answer questions about how happy they are with the appearance and feel of the crowns.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

The standard treatment for fixing severely decayed baby back teeth is the stainless steel crown, which is a durable metal cap. While these metal crowns work very well, many parents and children prefer a more natural, tooth-colored look. This study tests a newer option called the Bioflx crown, which is made of a flexible, tooth-colored material.

The Treatment Process The crowns are placed during two separate visits, usually 1 to 2 weeks apart. It gives the child time to get used to the first crown and ensures their bite is comfortable before the second one is placed. It makes the appointments shorter and easier for the child to handle. The side of the mouth that gets the metal crown and the side that gets the tooth-colored crown is randomized.

How Success is Measured

After the crowns are placed, researchers will check them again at 3 months and 6 months. They will use professional standards to evaluate the effectiveness of the crowns, focusing on:

  1. Durability: Do the crowns stay glued to the teeth and resist wearing down from chewing?
  2. Prevention: Does the new material prevent new cavities from forming at the edges of the crown?
  3. Gum Health: Do the gums around the tooth stay healthy, or do they become red and swollen?
  4. Satisfaction: How do the child and parent feel about the color, size, and shape of the tooth-colored crown compared to the metal one?

Study Type

Interventional

Enrollment (Estimated)

25

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Vietnam
      • Ho Chi Minh City, Vietnam, 700000
        • University of Medicine and Pharmacy at Ho Chi Minh City
      • Ho Chi Minh City, Vietnam
        • University of Medicine and Pharmacy at Ho Chi Minh City

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Children with at least two carious primary molars located on both the right and left sides of the dental arch and indicated for crown placement
  • Children and their parents have ability to communicate in Vietnamese

  • Primary molars indicated for full-coverage crown restoration, including teeth with:

    • Multi-surface caries
    • Extensive caries or enamel-dentin defects
    • Interproximal caries
    • High risk of failure with other restorative materials
    • Teeth following pulpotomy or pulpectomy

Exclusion Criteria:

  • Uncooperative children
  • Presence of psychiatric or neurological disorders affecting communication ability
  • Malocclusion (crossbite or scissors bite)
  • Having abnormal parafunctional habits
  • Teeth with root resorption exceeding one half of the root length

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Stainless steel crown
Participants receive a prefabricated stainless steel crown placed on a primary molar according to standard pediatric dental procedures. The crown is selected, adapted, and cemented following conventional clinical protocols and serves as the standard treatment comparator in this study.
Device: Stainless Steel Crown
Stainless steel crowns are prefabricated metal crowns that have been widely and long used in pediatric dentistry to restore primary molars with extensive caries or following pulp therapy.
Experimental: Bioflx crown
Participants receive a prefabricated Bioflx crown placed on a primary molar using manufacturer-recommended techniques. The crown is selected and cemented following standardized clinical procedures and is evaluated as the experimental intervention for clinical performance and patient-related outcomes.
Device: Bioflx crown
Bioflx crowns are prefabricated tooth-colored polymer crowns designed to improve esthetics compared with conventional stainless steel crowns

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
- Clincal outcomes: crown stability; bite discomfort; fit and color changes at the crown edge; crown shape; crown retention; crown wear; wear of the opposing tooth or crown - Oral hygiene and gum health around the crowns
Time Frame: - Crown stability, bite discomfort, fit and color at the crown margin, and crown shape were checked after crown placement, at 3 months, and at 6 months follow-up visits. Others were checked at 3, 6 months, except secondary caries was checked at 6 months

  • Each clinical parameter was assessed using the modified United States Public Health Service (USPHS) criteria.

    • Outcomes were rated on a three-level scale (Alpha, Bravo, Charlie), where Alpha indicates an ideal condition, Bravo an acceptable condition with minor defects, and Charlie an unacceptable condition requiring repair or replacement. For analysis, Alpha and Bravo scores were considered acceptable, while Charlie scores were considered failures.
    • Secondary caries were assessed using periapical radiographs, while all other clinical parameters were assessed by dental explorer and documented using photographs (Canon 6D camera).
  • This outcome evaluates how clean the teeth are and how healthy the gums are around crowned teeth. Plaque and gum condition were evaluated using standard dental indices (Plaque Index and Gingival Index). Dentists exam by using a periodontal probe at six points around the crowns, and the scores were combined to provide an overall result.
- Crown stability, bite discomfort, fit and color at the crown margin, and crown shape were checked after crown placement, at 3 months, and at 6 months follow-up visits. Others were checked at 3, 6 months, except secondary caries was checked at 6 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
parent and child satisfaction
Time Frame: From immediately after crowns placement through the 3-month and 6-month follow-up visits.
  • Children's and parents' satisfaction are assessed using two separate questionnaires, both employing a 5-point Likert scale with scores ranging from 1 to 5 (Units on a Scale). For children, a facial expression Likert scale is used.

  • The Likert scale levels are defined as follows:

    1. - Very dissatisfied
    2. - Dissatisfied
    3. - Neutral
    4. - Satisfied
    5. - Very satisfied
  • Higher scores indicate greater satisfaction
  • Parent questionnaire includes the following items: size, shape, color of two crowns; child's ability to eat a variety of foods after treatment and overall parental satisfaction.
  • Another questionnaire scale based on children ratings of treatment on them consists of five categories, including 1) Appearance of the teeth before crown placement; 2) Crowns have improved the appearance of the child's teeth; 3) The child avoided smiling before crowns; 4) Child smiling after crowns; 5) The oral health of the child improved after crowns.
From immediately after crowns placement through the 3-month and 6-month follow-up visits.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

PHAM LE ANH THY

Investigators

  • Study Chair: Huong Thi Nguyen Nguyen, PhD, Faculty of Dentistry, University of Medicine and Pharmacy at Ho Chi Minh City

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 1, 2025

Primary Completion (Estimated)

July 1, 2026

Study Completion (Estimated)

October 1, 2027

Study Registration Dates

First Submitted

January 17, 2026

First Submitted That Met QC Criteria

January 20, 2026

First Posted (Actual)

January 22, 2026

Study Record Updates

Last Update Posted (Actual)

January 22, 2026

Last Update Submitted That Met QC Criteria

January 20, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 3526/QĐ-ĐHYD

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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