Effect of Axial Wall Height on Bacterial Adhesion, Marginal Seal, and Color Change of One-piece Molar Zirconia Endocrown.

Aim: This study investigates the effect of various preparation designs influence the bacterial adhesion, vertical discrepancy, and mean color change (ΔE*), of maxillary and mandibular one-piece zirconia endocrowns cemented to molar teeth.

Materials and methods: Forty extracted human maxillary and mandibular molars (n = 20 each) were divided into two groups based on the remaining all surfaces axial height as group with 2 mm and group with 4 mm. Streptococcus mutans adhesion was evaluated using Mueller-Hinton agar plates, and vertical discrepancies of the cemented endocrowns were assessed by a digital microscope. The specimens were stained using Saudi coffee, then the color parameters were measured using a spectrophotometer before and after immersion of the samples. Data were analyzed using SPSS to assess significance between and within groups, where a p-value of ≤ 0.05 indicated statistical significance.

Results: Colony-forming units were between 489 ± 4.912 and 518 ± 6.667 (CFU/mm²) for both one-piece endocrown groups with no significant difference. Marginal discrepancy values were the highest with 2 mm axial wall in mandibular molars (44.30 ± 2.73 µm) and the lowest with 2 mm axial wall in maxillary molars (4.75 ± 0.85), with a significant difference (p < 0.05). The mean ΔE* values for one-piece endocrown for maxillary molars at 2 mm axial wall were the highest at 7.18 ± 1.16, followed closely by 4 mm axial wall in maxillary molars at 7.10 ± 0.61. In mandibular molars with 4 mm axial wall, the ΔE* was 2.51 ± 0.32, and the difference was significant (p < 0.001).

Conclusion: The one-piece endocrown with the used axial wall height did not significantly affect the bacterial adhesion. The ΔE* values were slightly high but still within clinically acceptable ranges for both groups with maxillary molars exhibited higher ΔE*, particularly with 2 mm height group. Marginal discrepancy values were within the recommended range for both groups.

Clinical significance: Using a one-piece endocrown restoration after endodontic treatment may minimize the bacterial adhesion and provide a good coronal seal. So, endocrowns can be a good option for posterior maxillary and mandibular molar teeth with remaining 2-4 mm axial height. How to cite this article: Tarrosh MY. Effect of Axial Wall Height on Bacterial Adhesion, Marginal Seal, and Color Change of One-piece Molar Zirconia Endocrown. J Contemp Dent Pract 2025;26(3):303-310.