Prefabricated CAD/CAM PEEK Crowns For Primary Molars Restoration

Evaluation of Minimally Prepared CAD/CAM Polyetheretherketone (PEEK) Crowns Efficacy in Restoring Primary Molars

This Split-mouth randomized clinical trial aims to evaluate CAD/CAM prefabricated Polyether ether ketone crowns for primary molars restoration after pulpotomy compared to Stainless steel crowns Over follow-up periods of 3, 6, and 12 months, the sample included 60 children aged 5-9 years who had bilateral mandibular second primary molars.

Each child received a pulpotomy treatment followed by the placement of a stainless steel crown on one side and a PEEK crown on the contralateral side, distributed randomly.

Clinical parameters were subsequently evaluated during the three follow-up periods, including the gingival index, plaque index, bleeding on probing index, restoration retention and integrity, marginal adaptation, color stability, and both parental and child satisfaction.

Study Overview

• Status: Active, not recruiting
• Conditions: Dental Esthetic, Dental Care for Children, Dental Crowns
• Intervention / Treatment: Procedure: Prefabricated CAD/CAM PEEK with 0.2 mm thickness; Procedure: Prefabricated CAD/CAM PEEK with 0.4 mm thickness; Procedure: CAD/CAM-fabricated PEEK Crowns; Procedure: Satinless steel crowns

Detailed Description

Interest in the esthetic aspect of pediatric dental treatment has increased among both children and parents, as children's self-perception is strongly influenced by the appearance of their teeth from an early age. Most esthetic restorative options require extensive tooth preparation compared with stainless steel crowns (SSCs). However, only limited studies have investigated conservative esthetic alternatives for primary molars.

This randomized controlled clinical trial aimed to evaluate the clinical effectiveness of CAD-CAM prefabricated esthetic PEEK crowns compared with stainless steel crowns (SSCs) in restoring primary mandibular second molars after pulpotomy. Clinical performance was assessed according to restoration retention and integrity, gingival health, plaque accumulation, bleeding on probing, marginal adaptation, color stability, and child/parent satisfaction over follow-up periods of 3, 6, and 12 months.

The sample was randomly allocated using the website: randomization.com

A total crowns were randomly distributed into four groups (n=20 per group):

(A): Prefabricated CAD/CAM PEEK crowns with 0.2 mm thickness (B): Prefabricated CAD/CAM PEEK crowns with 0.4 mm thickness (C): CAD/CAM fabricated PEEK crowns prepared according to NuSmile recommendations (D): Stainless steel crowns (SSC). The study included healthy, cooperative children aged 5-9 years requiring pulpotomy treatment for mandibular second primary.

Clinical Procedure

Clinical and radiographic examinations are performed to confirm the indication for pulpotomy treatment, followed by completion of the study form. Local anesthesia and rubber dam isolation are carried out, and pulpotomy is performed according to the conventional technique described by Dean (2016). The tooth is then restored with glass ionomer cement.

After cement setting, conservative tooth preparation is performed using diamond burs with 1-2 mm occlusal reduction. For Groups I, II, and IV, proximal reduction is completed with minimal preparation. In Group III, tooth preparation follows NuSmile recommendations, including occlusal reduction, proximal opening, crown reduction, and a 1 mm subgingival finish line.

For Groups I, II, and IV, the appropriate crown size is selected, checked for marginal adaptation and proximal contacts, then cemented using Fuji I glass ionomer cement. Excess cement is removed using a dental explorer and dental floss.

For the CAD/CAM fabricated PEEK group, a silicone impression is taken and scanned digitally. Crowns are designed using Exocad software and fabricated with CAD-CAM technology. After polishing and internal surface conditioning with aluminum oxide particles, the crown is tried in, cemented with Fuji I glass ionomer cement, and excess cement is removed.

Clinical parameters are evaluated immediately after crown cementation for directly measurable baseline variables and during the three follow-up periods (after 3, 6, 12 months), including the gingival index, plaque index, bleeding on probing index, restoration retention and integrity, marginal adaptation, color stability, and both parental and child satisfaction.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Syria
  • Damascus, Syria
    • School of Dental Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Healthy children aged 5-9 years.
2. Children requiring pulpotomy of mandibular second primary molars.
3. Cooperative children rated as positive or definitely positive on the Frankl behavior scale.
4. No acute or chronic abscess at the anesthesia site.

Exclusion Criteria:

1. Root resorption exceeding the apical third.
2. Non-restorable teeth.
3. Presence of swelling, fistula, or acute or chronic pulpitis.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Prefabricated PEEK crowns of 0.2 mm thickness; Minimally prepared teeth restored with prefabricated PEEK crowns of 0.2 mm wall thickness.	Procedure: Prefabricated CAD/CAM PEEK with 0.2 mm thickness; The pulpotomized molar assigned to experimental group will be received A Polyether ether ketone prefabricated crown with 0.2mm thickness on one side of mandibular arch, and the other side will be received a Stainless steel crown as control group.
Experimental: Prefabricated PEEK crowns of 0.4 mm wall thickness; Minimally prepared teeth restored with prefabricated PEEK crowns of 0.4 mm wall thickness.	Procedure: Prefabricated CAD/CAM PEEK with 0.4 mm thickness; The pulpotomized molar assigned to experimental group will be received A Polyether ether ketone prefabricated crown with 0.4mm thickness on one side of mandibular arch, and the other side will be received a Stainless steel crown as control group.
Experimental: CAD/CAM-fabricated PEEK crowns; Teeth receiving comprehensive preparation and restored with CAD/CAM-fabricated PEEK crowns following the NuSmile preparation protocol.	Procedure: CAD/CAM-fabricated PEEK Crowns; The pulpotomized molar assigned to experimental group will be received A CAD/CAM fabricated Polyether ether ketone crown on one side of mandibular arch, and the other side will be received a Stainless steel crown as control group.
Active Comparator: Stainless steel crowns; Minimally prepared teeth restored with prefabricated stainless steel crowns, as the positive control group.	Procedure: Satinless steel crowns; The pulpotomized molar assigned to control group will be received a Stainless steel crown as control group on one side of mandibular arch, and the other side will be received one of the arm 1, 2, or 3

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gingival Index	0 = No gingival inflammation.; = Mild inflammation with slight changes in color and texture affecting part of the marginal gingiva or papilla.; = Mild inflammation with changes in color and texture involving the entire marginal gingiva or papilla.; = Moderate gingival inflammation with obvious redness, surface glazing, edema, and/or enlargement of the marginal gingiva or papilla.; = Severe gingival inflammation with marked redness, edema and/or enlargement of the marginal gingiva or papilla, spontaneous bleeding, and ulceration.	Baseline, 3 months, 6 months, and 12 months postoperatively
Plaque Index	0 = No plaque accumulation around the gingival margin.; = Slight plaque accumulation detected only by passing a probe.; = Moderate plaque accumulation visible to the naked eye.; = Heavy plaque accumulation on the crown surface, gingiva, and interdental areas.	Baseline, 3 months, 6 months, and 12 months postoperatively
Bleeding on Probing	Bleeding on probing is assessed using a Williams periodontal probe inserted into the gingival sulcus around each crowned tooth. Four sites (mesial, distal, buccal, and lingual) are examined, and bleeding is evaluated 10 seconds after probing as follows: (-) No bleeding. (+) Bleeding present.	Baseline, 3 months, 6 months, and 12 months postoperatively
Wong-Baker Faces Scale	A Wong-Baker Faces Scale consisting of six expressive faces is used, ranging from "no hurts" to "hurts worst," to facilitate the child's selection of the appropriate face. The scale ranges from 0 to 10. The child is given a questionnaire displaying the faces immediately after crown placement and is asked to choose the face that best represents their feeling at that moment. The child indicates the selected face by pointing to it, and the response is recorded in the study form.	Baseline, 3 months, 6 months, 12 months postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Color Stability	Color stability is assessed using a shade guide as a reference standard. The crown color is compared with the shade guide at each follow-up visit (3, 6, and 12 months) according to the following criteria: 0 = No color change.; = Slight change from the original color.; = Unacceptable color change.	3 months, 6 months, 12 months postoperatively
Restoration retention and integrity	The clinical condition of the crown is evaluated during follow-up visits according to the following criteria: 0 = No visible fracture.; = Minor crown fracture that is repairable.; = Major crown fracture that can still be repaired.; = Crown loss and exclusion from the study sample.	3 months, 6 months, 12 months postoperatively
Marginal Adaptation	Marginal adaptation discrepancies were evaluated clinically using a sharp explorer and direct visual examination under dental operating light According to the modified United States Public Health Service (USPHS) criteria; (A): An Alpha grade represented a clinically ideal restoration with excellent marginal adaptation, no detectable gap on exploratory examination. (B): A Bravo grade indicated a clinically acceptable restoration with a slight marginal discrepancy detectable by an explorer, but without dentin exposure. (C): A Charlie grade was assigned to restorations that were clinically unacceptable due to a definite marginal gap, with exposed dentin. (D): A Delta grade denotes the worst clinical condition, characterized by gross marginal failure, loss of retention, or other major defects, for which complete replacement of the restoration is required.	3 months, 6 months, 12 months postoperatively
Patient/Parent Satisfaction	The child and one parent are asked about their satisfaction with the crowns regarding esthetics and function, and the responses are recorded in the patient form. Evaluation is performed as follows: = Completely satisfied with both esthetic and functional outcomes.; = Satisfied with esthetic and functional outcomes with a minor remark.; = Minor criticism without negative clinical effects or esthetic defects.; = Desire for improvement in esthetic and functional aspects.; = Completely dissatisfied.	3 months, 6 months, 12 months postoperatively

Collaborators and Investigators

• Sponsor: Arab International University
• Collaborators: Damascus University
• Investigators: Principal Investigator: Bushra Munzer Shamma, MSc, DDS., Damascus University; Study Chair: Mohannad Laflouf, PhD, MSc, DDS., Damascus University; Study Director: Saleh Al Kurdi, PhD, MSc, DDS., Arab International University

Publications and helpful links

General Publications

• Attia MA, Blunt L, Bills P, Tawfik A, Radawn M. Micro-CT analysis of marginal and internal fit of milled and pressed polyetheretherketone single crowns. J Prosthet Dent. 2023 Jun;129(6):906.e1-906.e10. doi: 10.1016/j.prosdent.2023.03.018. Epub 2023 Apr 16.
• Heimer S, Schmidlin PR, Roos M, Stawarczyk B. Surface properties of polyetheretherketone after different laboratory and chairside polishing protocols. J Prosthet Dent. 2017 Mar;117(3):419-425. doi: 10.1016/j.prosdent.2016.06.016. Epub 2016 Sep 28.
• Chen Y, Liu W, Wu Z, Wang S, Li Y, Su B, Li S. Advantages and feasibility of prefabricated PEEK crowns for aesthetic restoration in primary teeth. Sci Rep. 2024 Nov 18;14(1):28398. doi: 10.1038/s41598-024-79306-1.
• Stawarczyk B, Beuer F, Wimmer T, Jahn D, Sener B, Roos M, Schmidlin PR. Polyetheretherketone-a suitable material for fixed dental prostheses? J Biomed Mater Res B Appl Biomater. 2013 Oct;101(7):1209-16. doi: 10.1002/jbm.b.32932. Epub 2013 Apr 6.
• Skirbutis G, Dzingute A, Masiliunaite V, Sulcaite G, Zilinskas J. PEEK polymer's properties and its use in prosthodontics. A review. Stomatologija. 2018;20(2):54-58.
• Nagarathna, C., Deepthi, L., & Cam, C. A. D. (2026). Next Generation Smile Solutions - PEEK Crowns in Pediatric Dentistry. Journal of Chemical Health Risks, 16(1), 1734-1742.

Study record dates

Study Major Dates

• Study Start (Actual): April 2, 2024
• Primary Completion (Actual): December 10, 2025
• Study Completion (Estimated): August 26, 2026

Study Registration Dates

• First Submitted: May 22, 2026
• First Submitted That Met QC Criteria: May 28, 2026
• First Posted (Actual): June 1, 2026

Study Record Updates

• Last Update Posted (Actual): June 1, 2026
• Last Update Submitted That Met QC Criteria: May 28, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: CAD/CAM; Stainless steel crowns; Polyetheretherketone; Prefabricated crowns
• Other Study ID Numbers: 106/SRC/Sep.23.2024

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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