The aim of the study is to compare preformed metal crowns and 3D-printed ceromer crowns in primary molars of 4-9 years old children. The main questions it aims to answer are:

• How does 3D-printed ceromer crowns compare clincally to stainless steel crowns when restoring posterior molars?
• What is the level of satisfaction of the patient with both materials?
• What is the level of parental satisfaction with both materials?

Study methodology:

This study is a split-mouth clinical trial where participants will receive at least one of each materials in different quadrants of the mouth.

This randomized clinical trial is designed following the Consolidated Standards of Reporting Trials (CONSORT) guidelines and will adopt a prospective, split-mouth approach. The objective is to compare the clinical performance of crowns fabricated with three-dimensional (3D) printed ceromer material against conventional preformed stainless steel crowns in extensively decayed primary posterior teeth. The unit of observation will be gingival inflammation in the area surrounding the restorations, evaluated at specific time points over a 12-month follow-up period (3, 6 and 12 months).

Each eligible participant will receive both types of crowns, with assignments made to contralateral quadrants of the mouth to allow for within-subject comparison. This methodology minimizes inter-individual variability and strengthens internal validity. The ceromer crowns will be fabricated via additive manufacturing (3D printing), while the stainless steel crowns will follow the conventional selection and crimping technique.

Written informed consent will be obtained from their guardians or parents. An expected total of 50 primary molars of healthy participants will be restored.

Inclusion Criteria:

• Children aged 4 to 9 years with at least 2 primary molars affected by deep occlusoproximal caries.
• Teeth may require pulp therapy (pulpotomy or pulpectomy) and be suitable for full-coverage restoration.
• Teeth must have an antagonist and be located in opposing hemiarches.
• The affected primary molars must be expected to remain in the mouth for at least 12 months.
• The child must be in general good health.
• Parents or legal guardians must sign informed consent, and the child must provide assent.
• Patient does not come to control appointment or does not want to continue research.

Exclusion Criteria:

• Children with systemic diseases or medical conditions affecting oral health.
• Uncooperative behavior (Frankl scale 3 or 4).
• Temporomandibular joint disorders or parafunctional habits (e.g., bruxism).
• Absence of antagonist or adjacent teeth in the selected quadrants.
• Children on long-term medication.
• Patient with allergy to local anesthetic, nickel or chromium.

IPD will be shared to with

Due to the esthetic nature of the different materials, masking of the participants and investigators is not possible, however outcomes assessor with be masked.