Impact of Nano-Crystalline Diamond Enhanced Hydrophilicity on Cell Proliferation on Machined and SLA Titanium Surfaces: An In-Vivo Study in Rodents.

Robert Stigler,Michela Bruschi,Robert Gassner,Kathrin Becker,Doris Steinmüller-Nethl

doi:10.3390/nano8070524

Abstract

By coating surfaces with nano-crystalline diamond (NCD) particles, hydrophilicity can be altered via sidechain modifications without affecting surface texture. The present study aimed to assess the impact of NCD hydrophilicity on machined and rough SLA titanium discs on soft tissue integration, using a rodent model simulating submerged healing. Four different titanium discs (machined titanium = M Titanium, NCD-coated hydrophilic machined titanium = M-O-NCD, sand blasted acid etched (SLA Titanium) titanium, and hydrophilic NCD-coated SLA titanium = SLA O-NCD) were inserted in subdermal pockets of 12 Wistar rats. After one and four weeks of healing, the animals were sacrificed. Biopsies were embedded in methyl methacrylate (MMA), and processed for histology. The number of cells located within a region of interest (ROI) of 10 µm around the discs were counted and compared statistically. Signs of inflammation were evaluated descriptively employing immunohistochemistry. At one week, M-O-NCD coated titanium discs showed significantly higher amounts of cells compared to M Titanium, SLA Titanium, and SLA-O-NCD (p < 0.001). At four weeks, significant higher cell counts were noted at SLA-O-NCD surfaces (p < 0.01). Immunohistochemistry revealed decreased inflammatory responses at hydrophilic surfaces. Within the limits of an animal study, M-O-NCD surfaces seem to stimulate cell proliferation in the initial healing phase, whereas SLA-O-NCD surfaces appeared advantageous afterwards.

Highlights

Dental implants are frequently used to achieve an oral rehabilitation of partly or completely edentulous patients
The demanded features may be associated with O-nano-crystalline diamond (NCD) coatings, and this hypothesis was supported by the findings of the present investigation: Significant higher cell counts were detected around M-O-NCD and SLA-O-NCD surfaces compared with the non-coated groups, favoring O-NCD coated surfaces over the control groups
A possible explanation for the higher cell counts on M-O-NCD surfaces in week 1 and SLA-O-NCD surfaces at week 4 can be derived from a recent finding reporting that within the first 3 h, most of the fibroblasts attach to polished surfaces, whereas after 3 days of healing more cells are found close to rough surface textures [20]

Summary

Introduction

Dental implants are frequently used to achieve an oral rehabilitation of partly or completely edentulous patients. Whereas several surface modifications and chemical treatments have been identified to improve osseointegration [1], the creation of an ideal transmucosal part is still challenging. The formation of a connective-tissue seal through collagen adhesion is desired to prevent bacterial penetration, favoring rough surfaces. As rough surface promotes biofilm adhesion [2], machined surfaces may be beneficial to prevent peri-implant inflammation. Various mechanical and chemical surface treatments have been proposed to improve hard and soft tissue adhesion [3,4,5,6].

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Discussion

Conclusion