Custom-made Versus Prefabricated Zirconia Crowns for Primary Molars.

This study is a randomized, 12-month follow up clinical trial. According to sample size calculation, ten patients will be selected in conjunction with departments of Pedodontics and Crowns & Bridges. The study will be conducted in accordance with the principles of the Research Ethics Committee, Faculty of Dental Medicine for Girls, Al-Azhar University, Egypt.

The purpose of the investigation and the clinical procedures of this study will be explained to the parents and children. A written informed consent form will be signed from patient guardians and obtained prior to study initiation. The inclusion and exclusion criteria are established as the following;

• Inclusion criteria

• Children of 5-9 years old.
• The children have at least 2 pulpotomized primary molars with no clinical signs & symptoms or periapical pathosis.
• Presence of an intact contralateral primary molar as a control.
• Willingness to participate and to continue with the follow up appointments.
• Clinical and radiographically confirmed dental caries extending to the middle third of dentin.
• Presence of teeth in opposite arch with normal occlusion.
• Exclusion criteria

• Children with systemic health problem.
• Children with periodontal disease.
• Children with unilateral chewing habit or allergic to local anesthesia.
• Presence of parafunctional habit.
• Clinical procedure;

• Patient selection and education; The participating children will continue with their routine dental appointments in the undergraduate training clinic. Before beginning, children, along with their parents will receive a standard oral hygiene education by an undergraduate student through brushing demonstration on a model. Parents will be warned when signs of gingival inflammation are present, or plaque control is inadequate.
• Samples grouping and teeth preparation:

Forty primary molars will be included in the study. Twenty decayed teeth will be restored with crowns (10 with custom-made ZrCs and 10 with prefabricated ZrCs), and the other twenty intact contralateral teeth will be evaluated as the controls (10 molars will be the controls for custom-made ZrCs and 10 molars will be the controls for prefabricated ZrCs). Preparation of the crowns will be performed under local anesthesia, according to manufacturers' instructions with the following guidelines; 1-2mm occlusal reduction, 0.5-1mm axial reduction, and a chamfer finish line will be established 0.5-1mm subgingivally.

• Impression taking and temporization:

After preparation, rubber-base impressions will be taken for the teeth specific for custom-made ZrCs. Then SSCs will be temporarily cemented over the prepared teeth till the next appointment.

• Try-in and cementation of ZrCs:

SSCs will be removed and the custom-made and prefabricated ZrCs will be tried in and permanently cemented.

• Follow-up visits:

The participants will be recalled for evaluation after a baseline and at 1, 3, 6 and 12 months.

• Evaluation methods:

• The periodontal health will be assessed using the plaque index (PI) and the gingival index (GI).
• The clinical success of the crowns will be assessed in terms of crown retention, marginal adaptation, crown contour, fracture, stain resistance, opposing tooth wear and tooth exfoliation.

Inclusion criteria

• Children of 5-9 years old.
• The children have at least 2 decayed primary molars.
• Presence of an intact contralateral primary molar as a control.
• Willingness to participate and to continue with the follow up appointments.
• Clinical and radiographically confirmed dental caries extending to the middle third of dentin.
• Presence of teeth in opposite arch with normal occlusion.

Exclusion criteria

• Children with systemic health problem.
• Children with periodontal disease.
• Children with unilateral chewing habit or allergic to local anesthesia.
• Presence of parafunctional habit.