Gingival Health After Zirconia Versus Stainless Steel Crowns in Children

Comparison of Gingival Health Outcomes Between Prefabricated Zirconia Crowns and Stainless Steel Crowns in Primary Molars: A Randomized Split-Mouth Clinical Trial

The goal of this clinical trial is to learn if prefabricated zirconia crowns (PZCs) improve gingival health compared to stainless steel crowns (SSCs) in primary molars of young children. It will also learn about plaque accumulation and parental satisfaction with the crowns. The main questions it aims to answer are:

1. Do PZCs lead to better gingival health than SSCs over time?
2. Do PZCs reduce plaque accumulation compared to SSCs?
3. Do parents report higher satisfaction with PZCs versus SSCs?

Researchers will compare PZCs to SSCs in a split-mouth design (each child receives one of each crown type on contralateral molars) to see if PZCs provide superior gingival health, plaque control, and satisfaction.

Participants will:

1. Receive PZCs on one primary molar and SSCs on the contralateral molar after tooth preparation
2. Attend follow-up visits at 12, 24, and 36 months for gingival health and plaque assessments
3. Complete parental satisfaction surveys at each follow-up visit

Study Overview

• Status: Enrolling by invitation
• Conditions: Gingival Disease
• Intervention / Treatment: Procedure: Prefabricated Zirconia Crown; Procedure: Stainless steel crown

Detailed Description

This clinical trial is a prospective, randomized, split-mouth controlled study designed to compare the long-term effects of prefabricated zirconia crowns (PZCs) and stainless steel crowns (SSCs) on gingival health, plaque accumulation, and parental satisfaction in primary molars of young children. The study addresses the need for evidence on how these restorative materials influence periodontal outcomes, given the conflicting data in existing literature regarding their biocompatibility, esthetics, and impact on gingival tissues. SSCs have been the standard for durability and cost-effectiveness in pediatric dentistry, but their metallic appearance and potential for plaque retention due to marginal microgaps raise concerns for esthetics and gingival inflammation. PZCs, offering superior esthetics and a polished surface, may provide advantages in reducing plaque adherence and improving mucosal compatibility, though long-term comparative data are limited.

This trial will employ a split-mouth design at the Pediatric Dental Clinic of Qassim University, Buraydah, Al-Qassim Province, Saudi Arabia. This intra-subject approach minimizes inter-individual variability in factors such as salivary composition, microbial ecology, brushing habits, dietary sugar intake, and systemic health, enabling direct comparison of the two crown types within the same child. One hundred healthy children with bilateral primary molars requiring full-coverage restorations will be enrolled. Randomization using a computer-generated sequence with allocation concealment via opaque envelopes opened chairside post-preparation will be implemented. Contralateral molars will receive either a PZC or SSC (randomly assigned), ensuring balanced distribution.

Tooth preparation will be standardized under local anesthesia (2% lidocaine with 1:100,000 epinephrine): pulpotomy/pulpectomy as indicated, circumferential reduction (1-1.5 mm) with tapered diamond burs, occlusal clearance (1.5-2 mm), and proximal adjustments. PZCs will be fitted without crimping for optimal marginal adaptation (<50 μm target), while SSCs will undergo mechanical crimping for tight cervical fit (<30 μm discrepancy). Both will be luted with resin-modified glass ionomer cement (RelyX™ Luting Plus, 3M™) for fluoride release and reliable bonding. Assessments will be conducted by two independent, calibrated examiners (inter-rater kappa >0.80) blinded to crown type via opaque cheek retractors.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Saudi Arabia
  • Al-Qassim Province
    • Buraidah, Al-Qassim Province, Saudi Arabia
      • Qassim University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Healthy children aged 3-7 years.
2. Bilateral primary molars requiring full-coverage restorations.
3. Adequate tooth structure (>50% remaining post-preparation).

Exclusion Criteria:

1. Children with moderate to severe baseline plaque accumulation (Silness & Löe Plaque Index ≥2) or parents/caregivers reporting inconsistent brushing (<2x/day).
2. Children with excessive sugar intake (>3 sugary snacks/beverages daily), assessed via the Beverage and Snack Questionnaire.
3. Systemic diseases affecting oral health (e.g., immunocompromised status, diabetes mellitus).
4. Active periodontal disease or severe malocclusion.
5. Allergy to crown materials.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Experimental arm (Prefabricated zirconia crowns); The experimental arm in this split-mouth randomized clinical trial involves the placement of prefabricated zirconia crowns (PZCs; specifically NuSmile® ZR) on one primary molar per participant.	Procedure: Prefabricated Zirconia Crown; Prefabricated zirconia crown (NuSmile® ZR) placed on primary molar after standardized preparation (1-1.5 mm circumferential reduction, 1.5-2 mm occlusal clearance); cemented with resin-modified glass ionomer (RelyX™ Luting Plus, 3M™).
Active Comparator: Active comparator arm (Stainless steel crowns); The comparator arm (active control) in this split-mouth randomized clinical trial involves the placement of stainless steel crowns (SSCs; specifically 3M™ ESPE™) on the contralateral primary molar per participant	Procedure: Stainless steel crown; Stainless steel crown (3M™ ESPE™) placed on contralateral primary molar after identical preparation; crown crimped at margins for adaptation; cemented with resin-modified glass ionomer (RelyX™ Luting Plus, 3M™)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Gingival Health	Gingival health assessed using the Löe Gingival Index. Four sites per tooth (mesial, distal, buccal, lingual) are scored as follows: 0 = Normal gingiva (no inflammation); = Mild inflammation - slight change in color, slight edema, no bleeding on probing; = Moderate inflammation - redness, edema, glazing, bleeding on probing; = Severe inflammation - marked redness and edema, ulceration, tendency to spontaneous bleeding Mean score per tooth (or per participant across assessed sites) is calculated. Higher scores indicate worse gingival inflammation. This primary outcome evaluates the comparative effect of prefabricated zirconia crowns versus stainless steel crowns on gingival tissue response over time, with assessments performed by blinded calibrated examiners.	Baseline, 12 months, 24 months, and 36 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Plaque Index Score	Plaque accumulation assessed using the Silness & Löe Plaque Index. Four sites per tooth (mesial, distal, buccal, lingual) are scored as follows: 0 = No plaque in the gingival area; = A thin film of plaque adhering to the free gingival margin and adjacent area of the tooth; plaque recognized only by running a probe across the tooth surface; = Moderate accumulation of soft deposits within the gingival margin or adjacent tooth surface, visible to the naked eye; = Abundance of soft matter within the gingival pocket and/or on the tooth and gingival margin Mean score per tooth (or per participant across assessed sites) is calculated. Higher scores indicate greater plaque thickness and accumulation. This outcome compares plaque control between prefabricated zirconia crowns and stainless steel crowns, evaluated by blinded calibrated examiners	Baseline, 12 months, 24 months, and 36 months

Collaborators and Investigators

• Sponsor: Murad Alrashidi

Publications and helpful links

General Publications

• Loe H. The Gingival Index, the Plaque Index and the Retention Index Systems. J Periodontol. 1967 Nov-Dec;38(6):Suppl:610-6. doi: 10.1902/jop.1967.38.6.610. No abstract available.
• Fischman SL. Current status of indices of plaque. J Clin Periodontol. 1986 May;13(5):371-4, 379-80. doi: 10.1111/j.1600-051x.1986.tb01475.x.
• Alzanbaqi SD, Alogaiel RM, Alasmari MA, Al Essa AM, Khogeer LN, Alanazi BS, Hawsah ES, Shaikh AM, Ibrahim MS. Zirconia Crowns for Primary Teeth: A Systematic Review and Meta-Analyses. Int J Environ Res Public Health. 2022 Feb 28;19(5):2838. doi: 10.3390/ijerph19052838.
• Taran PK, Kaya MS. A Comparison of Periodontal Health in Primary Molars Restored with Prefabricated Stainless Steel and Zirconia Crowns. Pediatr Dent. 2018 Sep 15;40(5):334-339.
• Alrashdi M, Alkhuwaiter S. Clinical Outcomes for Prefabricated Zirconia Crowns in Primary Dentition: A Systematic Review and Meta-Analysis. Pediatr Dent. 2025 Sep 15;47(5):312-321.
• Walia T, Salami AA, Bashiri R, Hamoodi OM, Rashid F. A randomised controlled trial of three aesthetic full-coronal restorations in primary maxillary teeth. Eur J Paediatr Dent. 2014 Jun;15(2):113-8.

Study record dates

Study Major Dates

• Study Start (Estimated): May 12, 2026
• Primary Completion (Estimated): May 12, 2029
• Study Completion (Estimated): June 1, 2029

Study Registration Dates

• First Submitted: February 21, 2026
• First Submitted That Met QC Criteria: February 21, 2026
• First Posted (Actual): February 27, 2026

Study Record Updates

• Last Update Posted (Actual): June 2, 2026
• Last Update Submitted That Met QC Criteria: May 29, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: gingival health; Plaque index; Zirconia crown; Stainless steel crown
• Additional Relevant MeSH Terms: Periodontal Diseases; Mouth Diseases; Stomatognathic Diseases; Gingival Diseases
• Other Study ID Numbers: 25-48-04

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Individual participant data will not be shared publicly to protect participant confidentiality. Summary data and results will be published in the peer-reviewed manuscript. Requests for additional aggregate data may be directed to the corresponding author.
• IPD Sharing Time Frame: Supporting information will be available upon reasonable request starting after publication of the primary results and indefinitely thereafter, or until no longer needed for scientific purposes.
• IPD Sharing Access Criteria: Aggregate/summary data underlying published results and supporting documents such as the study protocol may be shared upon reasonable request to the corresponding author (Murad Alrashdi, email: MU.ALRASHIDI@qu.edu.sa). Requests should include the requester's affiliation, research purpose, and intended use. Access will be granted at the author's discretion for legitimate scientific purpose. No automated repository or public link is planned.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No