Effect of the Acid-Etching on Grit-Blasted Dental Implants to Improve Osseointegration: Histomorphometric Analysis of the Bone-Implant Contact in the Rabbit Tibia Model

Previous studies have shown that the most reliable way to evaluate the success of an implant is by bone-to-implant contact (BIC). Recent techniques allow modifications to the implant surface that improve mechanical and biological characteristics, and also upgrade osseointegration. Objective: The aim was to evaluate the osseointegration in rabbit tibia of two different titanium dental implant surfaces: shot-blasted with Al2O3 (SB) and the same treatment with an acid-etching by immersion for 15 s in HCl/H2SO4 (SB + AE). Material and methods: Roughness parameters (Ra, Rt, and Rz) were determined by white light interferometer microscopy. Surface wettability was evaluated with a contact angle video-based system using water, di-iodomethane, and formamide. Surface free energy was determined by means of Owens and Wendt equations. Scanning electron microscopy equipped with X-ray microanalysis was used to study the morphology and determine the chemical composition of the surfaces. Twenty-four grade 4 titanium dental implants (Essential Klockner®) were implanted in the rabbit’s tibia, 12 for each surface treatment, using six rabbits. Six weeks later the rabbits were sacrificed and the implants were sent for histologic analysis. Resonance frequency analysis (RFA) was recorded both at the time of surgery and the end of the research with each device (Osstell Mentor and Osstell ISQ). Results: The roughness measurements between the two treatments did not show statistically significant differences. However, the effect of the acid etching made the surface slightly more hydrophilic (decreasing contact angle from 74.7 for SB to 64.3 for SB + AE) and it presented a higher surface energy. The bone-to-implant contact ratio (BIC %) showed a similar tendency, with 55.18 ± 15.67 and 59.9 ± 13.15 for SB and SB + AE implants, respectively. After 6 weeks of healing, the SB + AE showed an implant stability quotient (ISQ) value of 76 ± 4.47 and the shot-blasted one an ISQ value of 75.83 ± 8.44 (no statistically significant difference). Implants with different surface properties had distinctive forms of behavior regarding osseointegration. Furthermore, the Osstell system was an invasive and reliable method to measure implant stability. Conclusion: Both surfaces of implants studied showed high osseointegration. The SB and SB + AE implants used in our study had similar behavior both in terms of BIC values and RFA. The RFA systems in Osstell Mentor and Osstell ISQ confirmed nearly perfect reproducibility and repeatability.

Collagen Fibres Orientation in the Bone Matrix around Dental Implants: Does the Implant’s Thread Design Play a Role?

The aim of this study was to analyse the influence of different thread shapes of titanium dental implant on the bone collagen fibre orientation (BCFO) around loaded implants. Twenty titanium dental implants, divided for thread shapes in six groups (A–F) were analysed in the present study. All implants were immediately loaded and left in function for 6 months before retrieval. The parameters evaluated under scanning electron microscope were the thread width, thread depth, top radius of curvature, flank angle, and the inter-thread straight section. Two undecalcified histological sections were prepared from each implant. Birefringence analysis using circularly polarized light microscopy was used to quantitively measure BCFO. For groups A–F, respectively, transverse BCFO was 32.7%, 24.1%, 22.3%, 18.2%, 32.4%, and 21.2%, longitudinal BCFO was 28.2%, 14.5%, 44.9%, 33.1%, 37.7%, and 40.2%. The percentage differences between transverse and longitudinal orientation were 4.50% (A), 9.60% (B), −22.60% (C), −14.90% (D), −5.30% (E), and −19.00% (F). Following loading, the amount of transverse and longitudinal BCFO were significantly influenced by the thread shape. The greater flank angles and narrower inter-thread sections of the “V” shaped and “concave” shaped implant threads of groups A and B, respectively, promoted the predominance of transverse BCFO, compared to groups C-F (p < 0.05). A narrow inter-thread straight section promotes transverse BCFO, as do “V” shaped and “concave” shaped threads, which can thus be considered desirable design for implant threads.

Effect of Different Titanium Dental Implant Surfaces on Human Adipose Mesenchymal Stem Cell Behavior. An In Vitro Comparative Study

Background: The aim of this research was to evaluate the effects of three different titanium (Ti) implant surfaces on the viability and secretory functions of mesenchymal stem cells isolated from a Bichat fat pad (BFP-MSCs). Methods: Four different Ti disks were used as substrate: (I) D1: smooth Ti, as control; (II) D2: chemically etched, resembling the Kontact S surface; (III) D3: sandblasted, resembling the Kontact surface; (IV) D4: blasted/etched, resembling the Kontact N surface. BFP-MSCs were plated on Ti disks for 72 h. Cell viability, adhesion on disks and release of a panel of cytokines, chemokines and growth factor were evaluated. Results: BFP-MSCs plated in wells with Ti surface showed a viability rate (~90%) and proliferative rate comparable to cells plated without disks and to cells plated on D1 disks. D2 and D4 showed the highest adhesive ability. All the Ti surfaces did not interfere with the release of cytokines, chemokines and growth factors by BFP-MSCs. However, BFP-MSCs cultured on D4 surface released a significantly higher amount of Granulocyte Colony-Stimulating Factor (G-CSF) compared either to cells plated without disks and to cells plated on D1 and D2. Conclusions: The implant surfaces examined do not impair the BFP-MSCs cell viability and preserve their secretion of cytokines and chemokines. Further in vitro and in vivo studies are necessary to define the implant surface parameters able to assure the chemokines’ optimal release for a real improvement of dental implant osseointegration.

A Possible Relationship between Peri-Implantitis, Titanium Hypersensitivity, and External Tooth Resorption: Metal-Free Alternative to Titanium Implants

Titanium dental implant surface does not remain unaltered but may corrode and release ions or particles which trigger soft and hard tissue damage. Titanium may induce clinically relevant hypersensitivity in patients chronically exposed. A 56-year-old female patient presented peri-implantitis around a single titanium implant positioned three years earlier. Despite nonsurgical therapy, a rapid bone loss associated with pain and swelling occurred, and adjacent teeth presented external resorption. Compromised teeth were removed, and three titanium implants were inserted. Six months later, the patient complained about high mucosa sensitivity and implant exposure. At clinical and radiographic examinations, tissue inflammation and vertical bone loss involved the new implants and the process of external resorption affected the teeth. The blood test confirmed titanium hypersensitivity. Titanium implants were removed, and 5 zirconia implants were placed. No sign of bone loss or tooth resorption was recorded at clinical and radiographic control during 18 months of follow-up.