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. 2025 Aug 25:13:e19813.
doi: 10.7717/peerj.19813. eCollection 2025.

Internal and marginal fit of digitally fabricated all-ceramic crowns with auxiliary retentive features on short clinical abutments: a micro-CT study

Saeed M Alqahtani #  1 , Saurabh Chaturvedi #  1   2   3 , Mohamed Khaled Addas  1 , Nasser M Alqahtani  1 , Mohammad A Zarbah  1 , Mohammed Hussain Dafer Al Wadei  4 , Feras Ali Alsaeed  1 , Yasir Saad AlJaadan  1 , Ali Abdullah Ali Alqahtani  1 , Mohammed Abdullah Al Mansooi  5 , Mudita Chaturvedi  2
Affiliations

Internal and marginal fit of digitally fabricated all-ceramic crowns with auxiliary retentive features on short clinical abutments: a micro-CT study

Saeed M Alqahtani et al. PeerJ. .

Abstract

Background: Short clinical crowns/abutments (SCC) pose a challenge in achieving adequate retention. Auxiliary retentive features (ARF), such as grooves, are commonly employed to enhance retention. The marginal gap (MG) and internal fit (IF) of restorations are critical factors influencing clinical success. This study aimed to evaluate the MG, IF, and cement volume of digitally fabricated (computer-aided design (CAD) and computer-aided manufacturing (CAM)) all-ceramic crowns with and without grooves on SCC using micro-computed tomography (micro-CT).

Methods: A mandibular second molar typodont tooth was prepared to simulate SCC. Four groups of crowns (n = 30 per group) were fabricated: Group 1: CAD/CAM zirconia without grooves, Group 2: CAD/CAM zirconia with grooves, Group 3: CAD/CAM lithium disilicate with grooves, Group 4: Conventional lithium disilicate with grooves. Crowns were cemented using resin cement. MG, IF, and cement volume were evaluated using micro-CT. Gap measurements were taken in two planes across seven zones (Z1 to Z7). Statistical analysis was performed using one-way ANOVA and post hoc Tukey tests.

Results: Significant differences in MG and IF were observed among the groups (p < 0.001). Group 1 exhibited the lowest MG and IF, followed by Group 3, Group 2, and Group 4. Group 4 showed the highest average marginal discrepancy (AMD) and average wall discrepancy (AWD) ((AMD: Z1 = 197.36 ± 10.56 µm; Z7 = 226.5 ± 8.24 µm), (AWD: Z2 = 150.05 ± 10.89 µm; Z6 = 169.38 ± 10.57 µm)), followed by Group 2 > Group 3 > Group 1. The greatest discrepancy at the cuspal area was observed in Group 2, followed by Group 3 > Group 1 > Group 4. In the central fossa, the maximum discrepancy was also noted in Group 2 (CFD = 194.48 ± 13.71 µm). No significant differences were found in total cement space volume among the groups.

Conclusion: CAD/CAM crowns with grooves demonstrated clinically acceptable MG and IF values, with lithium disilicate crowns showing superior performance. These findings support the use of CAD/CAM technology for SCC restorations and underscore the importance of material selection and crown design for optimal clinical outcomes.

Keywords: All ceramic crown; Auxiliary features; Cement space; Fixed prosthodontics; Grooves; Marginal gap; Micro-CT.

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Conflict of interest statement

The authors declare there are no competing interests.

Figures

Figure 1
Figure 1. Flow chart of study steps.
Figure 2
Figure 2. Typodont tooth preparation representing short clinical crown of the abutment.
Figure 3
Figure 3. Snapshot of stl.file of prepared tooth (A) without groove; (B) with groove; (C) dies arranged on CAD software.
Figure 4
Figure 4. Representative image showing (A) Milled crowns with groove; (B) cemented crowns over respective dies.
Figure 5
Figure 5. Micro-CT images showing seven zones and three groove area of measurement.
Figure 6
Figure 6. Groupwise absolute marginal discrepancy (AMD) at Zone 1 and Zone 7.
Figure 7
Figure 7. Groupwise axial wall discrepancy (AWD) at Zone 2 and Zone 6.
Figure 8
Figure 8. Groupwise cuspal area discrepancy (CAD) at Zone 3 and Zone 5 and central fossa discrepancy (CFD) at Zone 5.
Figure 9
Figure 9. Groupwise auxiliary retentive groove area (G) measurements at G1, G2, G3.
See this image and copyright information in PMC

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References

    1. Abualsaud R, Alalawi H. Fit, precision, and trueness of 3D-printed zirconia crowns compared to milled counterparts. Dentistry Journal (Basel) 2022;10:215. doi: 10.3390/dj10110215. - DOI - PMC - PubMed
    1. ADA . A.D.A.: a guide to dental material and devices. 7th edition. American Dental Association; Chicago: 1974.
    1. Aktaş N, Akın Y, Ocak M, Atabek D, Bankoğlu Güngör M. Marginal and internal adaptation and absolute marginal discrepancy of 3D-printed, milled, and prefabricated crowns for primary molar teeth: an in vitro comparative study. BMC Oral Health. 2025;25:575. doi: 10.1186/s12903-025-05947-x. - DOI - PMC - PubMed
    1. Al-Dwairi ZN, Alkhatatbeh RM, Baba NZ, Goodacre CJ. A comparison of the marginal and internal fit of porcelain laminate veneers fabricated by pressing and CAD-CAM milling and cemented with 2 different resin cements. Journal of Prosthetic Dentistry. 2019;121:470–476. doi: 10.1016/j.prosdent.2018.04.008. - DOI - PubMed
    1. Al-Halabi MN, Bshara N, Nassar JA, Comisi JC, Rizk CK. Clinical performance of two types of primary molar indirect crowns fabricated by 3D printer and CAD/CAM for rehabilitation of large carious primary molars. European Journal of Dentistry. 2021;15:463–468. doi: 10.1055/s-0040-1721905. - DOI - PMC - PubMed

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