#Esthetics 03. Nov 2021

Zirconia: a key player in effective soft tissue healing

The development and maintenance of healthy peri-implant soft tissues are one of the main challenges in implant dentistry. The most common and popular way to grow and shape these tissues after implant placement is by inserting a prefabricated healing abutment.

Healing abutments are a unique type of abutment designed to facilitate the healing of bone and soft tissue around a dental implant. Once the gingiva has healed (generally 4-6 weeks after implant placement), the healing abutment is replaced with the final abutment that connects the implant to the restoration.

Abutment material

A wealth of research has shown that the abutment material itself has a significant role to play in peri-implant soft tissue health.1Healing abutments are currently available in a wide range of materials; the most common pre-manufactured stock healing abutments are made of titanium, ceramic and PMMA. Zirconia (zirconium dioxide, ZrO2) has been recognized as an exceptional material for implant abutments with mechanical properties comparable to the “gold standard” titanium.2

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Clinical advantages

Ceramic healing abutments are comparable to natural teeth and superior to titanium abutments and exhibit a range of clinical advantages.3 These include enhanced blood flow in tissues surrounding zirconia abutments (an indicator for the health of the soft tissue around implants), which translates into better nutrition of the tissues surrounding the implant.

The long-term survival of dental implants depends, among the other factors, on the control of bacterial infiltration in the peri-implant region.4 It has been observed that ceramic surfaces exhibit lower bacterial colonization on the implant-abutment interface5, 6 and a statistically significant decrease in human plaque biofilm formation compared to titanium surfaces.7 This reduces nitric oxide synthesis (an indicator of the bacteria-induced inflammatory process) in tissues around zirconia healing abutments.8

A systematic review that evaluated the impact of the abutment characteristics on peri-implant tissue health discovered significantly less bleeding on probing (BOP) and plaque accumulation with zirconia when compared to titanium abutments.1 Moreover, a comparison of the quality of the soft tissue surrounding zirconia and titanium abutments demonstrated lower inflammatory activity around the former5, 6. This finding was later confirmed by a pre-clinical study, which reported a lower proportion of pro-inflammatory leucocytes in the epithelium around zirconia than titanium abutments, indicating a superior gingival seal.9 Finally, zirconia surfaces also exhibited a faster formation of the epithelial attachments in vitro and a higher degree of soft tissue integration than titanium.10

Conclusion

In conclusion, the abutment material type plays a significant role in soft tissue healing and maintenance. As a highly soft-tissue-friendly material, zirconia could be considered a material of choice when successful soft tissue healing is essential.

References:

  1. Sanz-Martín, I., et al., Effects of modified abutment characteristics on peri-implant soft tissue health: A systematic review and meta-analysis. Clin Oral Implants Res, 2018. 29(1): p. 118-129.
  2. Manicone, P.F., P. Rossi Iommetti, and L. Raffaelli, An overview of zirconia ceramics: basic properties and clinical applications. J Dent, 2007. 35(11): p. 819-26.
  3.  Kajiwara, N., et al., Soft tissue biological response to zirconia and metal implant abutments compared with natural tooth: microcirculation monitoring as a novel bioindicator. Implant Dent, 2015. 24(1): p. 37-41.
  4. Dhir, S., Biofilm and dental implant: The microbial link. J Indian Soc Periodontol, 2013. 17(1): p. 5-11.
  5. Rimondini, L., et al., Bacterial colonization of zirconia ceramic surfaces: an in vitro and in vivo study. Int J Oral Maxillofac Implants, 2002. 17(6): p. 793-8.
  6. Scarano, A., et al., Bacterial adhesion on commercially pure titanium and zirconium oxide disks: an in vivo human study. J Periodontol, 2004. 75(2): p. 292-6.
  7. Roehling, S., et al., In Vitro Biofilm Formation on Titanium and Zirconia Implant Surfaces. J Periodontol, 2017. 88(3): p. 298-307.
  8. Degidi, M., et al., Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascular endothelial growth factor expression, and proliferative activity in peri-implant soft tissues around titanium and zirconium oxide healing caps. J Periodontol, 2006. 77(1): p. 73-80.
  9. Welander, M., I. Abrahamsson, and T. Berglundh, The mucosal barrier at implant abutments of different materials. Clin Oral Implants Res, 2008. 19(7): p. 635-41.
  10. Liñares, A., et al., Histological assessment of hard and soft tissues surrounding a novel ceramic implant: a pilot study in the minipig. Journal of Clinical Periodontology, 2016. 43(6): p. 538-546.