Fibroblast Interaction with Different Abutment Surfaces: In Vitro Study

A comparison of four decontamination procedures in Reusing healing abutments: An in vitro study

Objectives

This study aimed to compare the effect of four decontamination methods on the level of residual contaminants in the re-usage of dental healing abutments.

Materials and methods

In this experimental study, 50 used healing abutments were divided into five groups of ten as follows: 1. Control group: healing abutments were submerged in the ultrasonic device then autoclaved at 121 °C for 15 min; 2. Hypochlorite group: Same procedure as the control group, but the healing abutments were additionally immersed in 3 % hypochlorite for 20 min; 3. Chlorhexidine group: Same procedure as the control group, but the healing abutments were additionally treated with 12 % chlorhexidine; 4. Air polishing group: Same procedure as the control group, but the healing abutments were subjected to air polishing; 5. Hydrogen peroxide group: Same procedure as the control group, but the healing abutments were additionally exposed to 3 % hydrogen peroxide. Then, all healing abutments were stained with a protein-specific stain, Phloxine B. Five photographs were taken of each healing abutment, with four capturing the body (shank)and one capturing the top. All images were analysed, to measure the stained (contaminated) areas of each sample. The obtained data were analysed using statistical software (significance set at p < 0.05).

Results

The one-way ANOVA test indicated that the average percentage of contamination residues on the occlusal surface did not show a significant difference among the five groups: control: 5.5 ± 2.8, sodium hypochlorite: 4.9 ± 2.5, Chlorhexidine: 5.3 ± 2.5, air polisher: 3.1 ± 1.8 and Hydrogen peroxide: 4.8 ± 3.1. (p = 0.26). The average percentage of residual contamination on the body surfaces (shank part) was significantly lower in the air polisher (1.7 ± 1.1) and sodium hypochlorite (2.4 ± 1.1) groups compared to the other three groups (Control: 6.1 ± 2.3, Hydrogen peroxide: 4.6 ± 0.7, Chlorhexidine: 5.4 ± 2.4) (p < 0.05).

Conclusion

The results of this study showed that the use of sodium hypochlorite and air polishing, alongside autoclaving and ultrasonic cleaning, effectively reduced residual contamination on the body surfaces of healing abutments.

Nano-superhydrophilic and bioactive surface in poor bone environment. Part 1: transition from primary to secondary stability. A controlled clinical trial : Bioactive implant surfaces in poor density bone

OBJECTIVES

Bioactive surfaces were designed to increase the interaction between the surface and the cells. This may speed up the biological stability and loading protocols.

MATERIALS AND METHODS

36 patients with D3-D4 bone density were recruited and allocated into two groups. 30 bioactive (test group) and 30 traditional (control group) surfaced implants were placed. Insertion torque value (Ncm), insertion torque curve integral (cumulative torque, Ncm), torque density (Ncm/sec), implant stability quotient (ISQ) measured at three timepoints (baseline (T0), 30 (T30) and 45 (T45) days after surgery), and marginal bone loss (MBL) at 6 months of loading were assessed.

RESULTS

The mean ISQ and standard deviation at T0, T30, T45 were respectively 74.57 ± 7.85, 74.78 ± 7.31, 74.97 ± 6.34 in test group, and 77.12 ± 5.83, 73.33 ± 6.13, 73.44 ± 7.89 in control group, respectively. Data analysis showed significant differences between groups in ΔISQ at T0-T30 (p = 0.005) and T30-T45 (p = 0.012). Control group showed a significant decrease in ISQ at T30 (p = 0.01) and T45 (p = 0.03) compared to baseline, while no significant change was observed in test group. Due to the stability of the ISQ value ≥ 70, 26 test group and 23 control group implants were functionally loaded after 45 days. Conversely, due to the ISQ < 70 at T45, four test group implants and one control group implant were loaded after 90 days, and 6 control group implants were loaded after 180 days. Neither insertion torque nor ISQ at baseline were correlated with bone density (in Hounsfield units). There was no significant correlation between cumulative torque and ISQ at baseline. There was a significant positive slope in the correlation between torque density and ISQ at baseline, more accentuated in D3 than D4. This correlation remained significant for the test group in D3 bone at day 30 and 45 (p < 0.01 in both time frames), but not in D4 bone, and it was not significant in CG.

CONCLUSIONS

The bioactive surface showed better behavior in terms of implant stability in D3-D4 bone quality in the early stages of bone healing. Clinical relevance This study demonstrated that the transition from primary to secondary stability is improved using bioactive surface, especially in cases of poor bone environment (D3/D4 bone).

Highly Ordered Nanotube-Like Microstructure on Titanium Dental Implant Surface Fabricated via Anodization Enhanced Cell Adhesion and Migration of Human Gingival Fibroblasts

Background

Titanium (Ti) surface with nanotubes array via anodization has been used in dental implants to enhance bone regeneration but little research was carried out to evaluate whether the presence of highly ordered or disorderly distributed nanotubes array on titanium surface would have an effect on cell behaviors of gingival fibroblasts.

Methods

The present study fabricated nanotubes arrays with varied topography under different constant voltage of electrochemical anodization in fluorine-containing electrolyte. Human gingival fibroblasts (HGFs) from extracted third molar were harvested and co-cultured with titanium disks with different nanotubes topography. Then cell behaviors of gingival fibroblasts including cell proliferation, adhesive morphology and cell migration were estimated to investigate the influence of titanium nanotubes on cell biology. Besides, gene and protein expression of adhesion molecule (integrin β1/β4/α6, fibronectin, intracellular adhesion molecule-1 and collagen type I) were detected to evaluate the influence of different surfaces on cell adhesion.

Results

Highly ordered arrays of nanotubes with pore diameter of 60 nm and 100 nm were fabricated under 30 and 40 V of anodization (TNT-30 and TNT-40) while disorderedly distributed nanotube arrays formed on the titanium surface under 50 V of anodization (TNT-50). Our results demonstrated that compared with raw titanium surface and disorderly nanotubes, surface with orderly nanotubes array increased cell area and aspect ratio, as well as cell migration ability in the early phase of cell adhesion (p<0.05). Besides, compared with raw titanium surface, gene and protein expression of adhesion molecules were upregulated in nanotubes groups to different extents, no matter whether in an orderly or disorderly array.

Conclusion

Within the limitations of our study, we conclude that compared with raw titanium surface, the presence of nanotubes array on titanium surface could enhance cells adhesion and cell migration in the early phase. And compared with disorderly distributed nanotubes, highly ordered nanotubes array might provide a much more favorable surface for gingival fibroblasts to achieve a tight adhesion on the materials.

Effect of argon plasma abutment activation on soft tissue healing: RCT with histological assessment

OBJECTIVE

To assess the peri-implant soft tissue profiles between argon plasma treatment (PT) and non-treated (NPT) healing abutments by comparing clinical and histological parameters 2 months following abutment placement.

MATERIALS AND METHODS

Thirty participants were randomly assigned to argon-plasma treatment abutments group (PT) or non-treated abutments (NPT) group. Two months after healing abutment placement, soft peri-implant tissues and abutment were harvested, and histological and clinical parameters including plaque index, bleeding on probing, and keratinized mucosa diameter (KM) were assessed. Specialized stainings (hematoxylin-eosin and picrocirious red) coupled with immunohistochemistry (vimentin, collagen, and CK10) were performed to assess soft tissue inflammation and healing, and the collagen content keratinization. In addition to standard statistical methods, machine learning algorithms were applied for advanced soft tissue profiling between the test and control groups.

RESULTS

PT group showed lower plaque accumulation and inflammation grade (6.71% vs. 13.25%, respectively; p-value 0.02), and more advanced connective tissue healing and integration compared to NPT (31.77% vs. 23.3%, respectively; p = 0.009). In the control group, more expressed keratinization was found compared to the PT group, showing significantly higher CK10 (>47.5%). No differences in KM were found between the groups.

SIGNIFICANCE

PT seems to be a promising protocol for guided peri-implant soft tissue morphogenesis reducing plaque accumulation and inflammation, and stimulating collagen and soft tissue but without effects on epithelial tissues and keratinization.

Effects of abutment materials on peri-implant soft tissue health and stability: A network meta-analysis

PURPOSE

This systematic review aimed to evaluate the effect of the abutment material on peri-implant soft tissue health and stability.

STUDY SELECTION

An electronic and hand search was conducted until February 2022. Only prospective randomized trials (RCTs) and controlled clinical trials (CCTs) comparing titanium abutments with abutments made of different materials, with a follow-up of at least 6 months, were selected by two independent reviewers. Data on marginal bone loss (MBL) and peri-implant tissue indexes, i.e., plaque index (PI), bleeding on probing (BOP), probing depth (PD), and recession (REC), were collected. The risk of bias for RCTs and non-RCTs was evaluated according to the tool reported in the Cochrane Handbook for Systematic Reviews of Interventions and the ROBINS-I tool, respectively. Both pairwise and network meta-analyses (NMA) were performed.

RESULTS

We included 18 relevant studies from 1,437 identified studies. Overall, 612 patients were treated, and 848 abutments were inserted. Five studies presented a low risk of bias. Pairwise meta-analysis showed that, as compared to titanium, zirconia abutments presented a significantly reduced MBL (0.20 mm, 95% Confidence Interval CI [0.14-0.26], P < 0.00001). No significant differences were found for the other outcomes. In the NMA, zirconia abutments demonstrated an 83.3% probability of achieving the highest rank in PI, an 87.0% in BOP, and a 65.0% in PD outcome, suggesting that zirconia abutments generally performed better than titanium and alumina abutments.

CONCLUSIONS

Within the limits of the present study, zirconia abutments seem a viable alternative to titanium ones.

In Vitro Characterization of an Anodized Surface of a Dental Implant Collar and Dental Abutment on Peri-Implant Cellular Response

The purpose of this paper was to determine the effect of anodization on the in vitro proliferation and adhesion of immortalized human keratinocytes (HaCats) and mouse bone marrow-derived mesenchymal stem cells (BM-MSCs) in Titanium Grade 23 (Ti6Al4V ELI) discs and to describe the surface topography, roughness, and composition of dental implants (body and collar) and abutments submitted to an area-specific anodization process. HaCat cells and BM-MSCs were seeded onto discs with three different surface treatments: machined, area-specific anodization for abutments, and area-specific anodization for implant collars. Cell proliferation was assessed using a resazurin-based fluorescent dye on days 1, 3, and 7, while cell adhesion was examined using scanning electron microscopy (SEM). Surface topography, roughness, and composition were evaluated for six implant bodies with an anodized rough surface, six anodized implant smooth collars, and six anodized prosthetic abutments. Both HaCats and BM-MSCs showed increased viability over time (p < 0.001) with no statistically significant differences among the different surfaces (p = 0.447 HaCats and p = 0.631 BM-MSCs). SEM analysis revealed an enhanced presence and adhesion of HaCat cells on the anodized surface for the implant collars and an increased adhesion of BM-MSCs on both the anodized and machined surface abutments. The topography characteristics of the treated implants and abutments varied depending on the specific implant region. Chemical analysis confirmed the presence of oxygen, calcium, phosphorus, and sodium on the anodized surfaces. The area-specific anodization process can be utilized to create variable topography, increase the specific surface area, and introduce oxygen, calcium, phosphorus, and sodium to dental implants and abutments. While BM-MSCs and HaCat cells showed similar adhesion and proliferation on anodized and machined surfaces, a positive interaction between anodized Ti6Al4V ELI surfaces and these two cell lines present in the peri-implant mucosa was observed. Due to the limitations of the present study, further research is necessary to confirm these findings.

Optimized Gingiva Cell Behavior on Dental Zirconia as a Result of Atmospheric Argon Plasma Activation

Several physico-chemical modifications have been developed to improve cell contact with prosthetic oral implant surfaces. The activation with non-thermal plasmas was one option. Previous studies found that gingiva fibroblasts on laser-microstructured ceramics were hindered in their migration into cavities. However, after argon (Ar) plasma activation, the cells concentrated in and around the niches. The change in surface properties of zirconia and, subsequently, the effect on cell behavior is unclear. In this study, polished zirconia discs were activated by atmospheric pressure Ar plasma using the kINPen^®09 jet for 1 min. Surfaces were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and water contact angle. In vitro studies with human gingival fibroblasts (HGF-1) focused on spreading, actin cytoskeleton organization, and calcium ion signaling within 24 h. After Ar plasma activation, surfaces were more hydrophilic. XPS revealed decreased carbon and increased oxygen, zirconia, and yttrium content after Ar plasma. The Ar plasma activation boosted the spreading (2 h), and HGF-1 cells formed strong actin filaments with pronounced lamellipodia. Interestingly, the cells' calcium ion signaling was also promoted. Therefore, argon plasma activation of zirconia seems to be a valuable tool to bioactivate the surface for optimal surface occupation by cells and active cell signaling.

Strontium-loaded hydrogel scaffolds to promote gingival fibroblast function

Dental implant clinical success is dependent on effective peri-implant tissue attachment to the trans-mucosal portion following placement. Modification of transmucosal implant surfaces can improve cellular adhesion and function leading to formation of an effective soft-tissue seal during healing, of which gingival fibroblasts are prominent cells to migrate to repair wounds and crucial for the development of a collagen rich connective tissue. Biocompatible loaded scaffold materials have been developed to allow local release of molecules with effective biological activity. Our previous studies indicate that strontium can promote gingival fibroblast metabolism, decrease apoptosis and support adhesion to titanium healing abutments. In this study, we developed a strontium-loaded alginate hydrogel scaffold which can be easily personalized to fit over any size and shape of implant transmucosal collar or healing abutment. Results indicate that biologically active strontium ions are effectively released from loaded alginate hydrogel material to promote fibroblast viability and migration to repair in vitro wounds similar to that of strontium citrate solution. Overall, this novel strontium-loaded alginate scaffold device displays good biocompatibility and functionality, demonstrating high potential as a system to provide local delivery of strontium to improve peri-implant mucosal healing following implant placement and clinical success.

Bacterial and Cellular Response to Yellow-Shaded Surface Modifications for Dental Implant Abutments

Dental implants have dramatically changed the rehabilitation procedures in dental prostheses but are hindered by the possible onset of peri-implantitis. This paper aims to assess whether an anodization process applied to clinically used surfaces could enhance the adhesion of fibroblasts and reduce bacterial adhesion using as a reference the untreated machined surface. To this purpose, four different surfaces were prepared: (i) machined (MAC), (ii) machined and anodized (Y-MAC), (iii) anodized after sand-blasting and acid etching treatment (Y-SL), and (iv) anodized after double acid etching (Y-DM). All specimens were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Moreover, the mean contact angle in both water and diiodomethane as well as surface free energy calculation was assessed. To evaluate changes in terms of biological responses, we investigated the adhesion of Streptococcus sanguinis (S. sanguinis) and Enterococcus faecalis (E. faecalis), fetal bovine serum (FBS) adsorption, and the early response of fibroblasts in terms of cell adhesion and viability. We found that the anodization reduced bacterial adhesion, while roughened surfaces outperformed the machined ones for protein adsorption, fibroblast adhesion, and viability independently of the treatment. It can be concluded that surface modification techniques such as anodization are valuable options to enhance the performance of dental implants.

Human Gingival Fibroblast Attachment to Smooth Titanium Disks with Different Surface Roughnesses

Peri-implantitis is a significant problem associated with dental implants. It has been hypothesized that creating a soft-tissue seal around the implant neck prevents peri-implantitis. This study aims to clarify the effects of the surface smoothness of titanium disks on soft tissues. Thus, titanium disks were prepared through electrolytic composite polishing (ECP), sisal buffing (SB), hairline polishing (HP), and laser cutting (LC). The surface roughness values of seven items was measured. For ECP, SB, HP, and LC samples, the Ra values were 0.075, 0.217, 0.671, and 1.024 μm and the Sa values were 0.005, 0.115, 0.500, and 0.676, respectively, indicating that the surface roughness was remarkably lower with ECP. Moreover, the Wsk values for ECP, SB, HP, and LC were 0.521, 1.018, -0.678, and -0.558, respectively. The smooth surfaces produced by ECP and SB were biased toward the concave surface, whereas those produced by HP and LC were biased toward the convex surface. The Rku values for ECP, SB, HP, and LC were 2.984, 11.774, 14.182, and 26.232, respectively. Only the ECP exhibited a moderate bias peak and produced an extremely smooth surface. The contact angles in the cases of ECP, SB, HP, and LC were 60.1°, 66.3°, 68.4°, and 79.3°, respectively, indicating the hydrophobicity of the titanium disks. Human oral fibroblasts were then incubated on each disk for 24 and 48 h to measure cell attachment, and no significant differences were observed. The differences in Ra and Sa did not affect cell attachment. Therefore, by applying ECP to the abutment or implant neck, the cell attachment required for soft-tissue formation while preventing bacterial adhesion can be achieved.

Plasma of Argon Treatment of the Implant Surface, Systematic Review of In Vitro Studies

This paper aims to review the evidence of the cellular activity on titanium samples exposed to Plasma of Argon (PoA) treatment. A systematic review was carried out based on the PRISMA statement by searching the Cochrane Library, PubMed, Web of Science, EMBASE and Scopus, up to October 2020. Papers were selected according to PICOS format that is: Population (P): osteoblasts, fibroblasts, gingival cells; Intervention (I): PoA disinfection treatment; Comparison (C): untreated controls; Outcome (O): cell culture; Setting (S): in vitro assays. The quality assessment was performed according to the CRIS Guidelines (Checklist for Reporting In vitro Studies). A total of 661 articles were found, of which 16 were included. The quality assessment revealed an overall poor quality of the studies analyzed. In vitro studies on the potential of PoA showed a potential effect in promoting higher cell adhesion and protein adsorption in the earliest times (hours). This outcome was not so evident when later stages of cell growth on the surfaces were tested and compared to the control groups. Only one study was conducted in vivo on a human sample regarding abutment cleaning. No meta-analysis was conducted because of the variety of experimental settings, mixed methods and different cell lines studied. PoA seems to be effective in promoting cell adhesion and protein adsorption. The duration of this effect remains unclear. Further evidence is required to demonstrate the long-term efficacy of the treatment and to support the use of PoA treatment in clinical practice.

Integration of collagen fibers in connective tissue with dental implant in the transmucosal region

Dental implants have been widely accepted as an ideal therapy to replace the missing teeth for its good performance in aspects of mechanical properties and aesthetic outcomes. Its restorative success is contributed by not only the successful osseointegration of the implant but also the tight soft tissue integration, especially the collagen fibers, in the transmucosal region. Soft tissue attaching to the dental implant/abutment is overall similar, but in some aspects distinct with that seen around natural teeth and soft tissue integration can be enhanced via several surface modification methods. This review is going to focus on the current knowledge of the transmucosal zone around the dental implants (compared with natural teeth), and latest strategies in use to fine-tune the collagen fibers assembly in the connective tissue, in an attempt to enhance soft tissue integration.

Influence of cold atmospheric plasma on dental implant materials - an in vitro analysis

Background and objectives

Alterations in the microenvironment of implant surfaces could influence the cellular crosstalk and adhesion patterns of dental implant materials. Cold plasma has been described to have an influence on cells, tissues, and biomaterials. Hence, the mechanisms of osseointegration may be altered by non-thermal plasma treatment depending on different chemical compositions and surface coatings of the biomaterial. The aim of the present study is to investigate the influence of cold atmospheric plasma (CAP) treatment on implant surfaces and its biological and physicochemical side effects.

Materials and methods

Dental implant discs from titanium and zirconia with different surface modifications were treated with CAP at various durations. Cell behavior and adhesion patterns of human gingival fibroblast (HGF-1) and osteoblast-like cells (MG-63) were examined using scanning electron microscopy and fluorescence microscopy. Surface chemical characterization was analyzed using energy-dispersive X-ray spectroscopy (EDS). Quantitative analysis of cell adhesion, proliferation, and extracellular matrix formation was conducted including real-time PCR.

Results

CAP did not affect the elemental composition of different dental implant materials. Additionally, markers for cell proliferation, extracellular matrix formation, and cell adhesion were differently regulated depending on the application time of CAP treatment in MG-63 cells and gingival fibroblasts.

Conclusions

CAP application is beneficial for dental implant materials to allow for faster proliferation and adhesion of cells from the surrounding tissue on both titanium and zirconia implant surfaces with different surface properties.

Clinical relevance

The healing capacity provided through CAP treatment could enhance osseointegration of dental implants and has the potential to serve as an effective treatment option in periimplantitis therapy.

Influences of cold atmospheric plasma on apoptosis related molecules in osteoblast-like cells in vitro

Background

Cold atmospheric plasma (CAP) has recently been identified as a novel therapeutic strategy for supporting processes of wound healing. Since CAP is additionally known to kill malignant cells, our study intends to determine the influence of CAP on crucial molecules involved in the molecular mechanism of apoptosis in osteoblast-like cells.

Methods

Human osteoblast-like cells were CAP-treated for 30 and 60 s. CAP effects on critical factors related to apoptosis were studied at transcriptional and protein level using real time-PCR, immunofluorescence staining and western blot. Phalloidin / DAPI staining was used for analyzing the cell morphology. In addition, apoptotic outcomes of CAP were displayed using flow cytometry analysis. For studying intracellular signaling pathways, MAP kinase MEK 1/2 and PI3K were blocked. Finally, the effects of CAP on caspase-3 activity were examined using a caspase-3 assay.

Results

CAP treatment resulted in a significant downregulation of p53 and apoptotic protease activating factor (APAF)-1, caspase (CASP)9, CASP3, BCL2 Antagonist/Killer (BAK)1, and B-Cell Lymphoma (BCL)2 mRNA expression at 1 d. An inhibitory effect of CAP on apoptotic genes was also shown under inflammatory and apoptotic conditions. Nuclear translocation of p53 was determined in CAP treated cells at the early and late stage, after 15 min, 30 min, and 1 h. p53 and APAF-1 protein levels were reduced at 1 d, visualized by immunofluorescence and western blot, respectively. Moreover, a morphological cytoskeleton modification was observed after CAP treatment at 1 d. Further, both CAP-treated and untreated (control) cells remained equally vital as detected by flow cytometry analysis. Interestingly, CAP-associated downregulation of CASP9 and CASP3 mRNA gene expression was also visible after blocking MAP kinase and PI3K. Finally, CAP led to a decrease in CASP3 activity in osteoblast-like cells under normal and apoptotic conditions.

Conclusions

Our in vitro-study demonstrated, that CAP decreases apoptosis related molecules in osteoblast-like cells, underlining a beneficial effect on hard-tissue cells.

Culturomic and quantitative real-time-polymerase chain reaction analyses for early contamination of abutments with different surfaces: A randomized clinical trial

BACKGROUND

Rough and/or plasma-activated abutments seem to be able to increase soft tissue adhesion and stability; however, limited evidence is available about bacterial contamination differences.

PURPOSE

The aim was to investigate the oral microbiota on four dental abutments with different surfaces by quantitative real-time polymerase chain reaction (qRT-PCR) and culturomic approach.

METHODS

Forty patients needing a single implant rehabilitation were involved in the study. Forty healing abutments, especially designed for the study, were divided into four groups according to the surface topography (1. machined [MAC], 2. machined plasma of argon treated [plasmaMAC], 3. ultrathin threaded microsurface [UTM], 4. UTM plasma of argon treated [Plasma UTM]). Random assignment was performed according to predefined randomization tables. All patients underwent surgical intervention for implant and contextual healing abutment positioning. After 2 months of healing, a sterile cotton swab was used for microbiological sampling for culturomics, while sterile paper points inserted into the sulcus were used for qRT-PCR.

RESULTS

At the end of the study, 36 patients completed all procedures and a total of 36 abutments (9 per group) were analyzed. qRT-PCR retrieved data for 23 bacterial species whereas culturomics revealed the presence of 74 different bacteria, most of them not routinely included into oral cavity microbiological kits of analysis or never found before in the oral microenvironment. No statistically significant differences emerged analyzing the four different surfaces (p = 0.053). On the contrary, higher total and specific bacterial counts were detected in the plasma-treated surfaces compared to the untreated ones (p = 0.021).

CONCLUSIONS

Abutments with different topographies and surface treatments resulted contaminated by similar oral bacterial flora. Abutments with moderately rough surface were not associated with a greater bacterial adhesion compared to machined ones. Conversely, more bacteria were found around plasma-treated abutments. Furthermore, data reported suggested to include new species not previously sought in the routine analyses of the oral bacterial microflora.

Soft tissue integration of different abutment surfaces: An experimental study with histological analysis

OBJECTIVE

To evaluate whether abutment surface and surface bio-activation have an effect on soft tissue morphogenesis.

MATERIALS AND METHODS

36 patients (36 implants) were included. Abutments were randomly divided into 4 groups (n = 9): Smooth Surface-MAChined (MAC), Ultrathin Threaded Microsurface (UTM), MAC Plasma of Argon activated (Plasma-MAC), and UTM Plasma of Argon activated (Plasma-UTM). After 2 months of healing, soft tissue samples were collected and prepared for histological analysis. The margin of the peri-implant mucosa (PM), the apical extension of the barrier epithelium (aJE), and the apical location of the abutment (AM) were identified. Significances of differences among groups were tested by means of the Kruskal-Wallis test and between pairs of results by means of the Mann-Whitney test.

RESULTS

The mean (SD) vertical dimension of the mucosa was 2.5mm (1.0), including a connective tissue portion (CTP) of 0.8mm (0.8) in the MAC group; 3.6mm (0.2) with a CTP of 1.6mm (0.4) in the Plasma-MAC group; 3.2mm (1.0), with a CPT of 0.5mm (0.6) in the UTM; and 3.3mm (0.8), with a CPT of 0.9mm (0.7) in the Plasma-UTM group. Statistically significant differences were observed in the aJE-AM height and PM-aJE profile among the four experimental groups (p = .042 and p = .039, respectively). The Mann-Whitney test indicated differences between the Plasma-abutments and the untreated abutments both for PM-AM (p = .025) and AjE-AM (p = .021). The differences appeared more evident when the preoperative soft tissue thickness was ≤2mm.

CONCLUSIONS

Within its limits, the study demonstrated a favorable effect of the plasma treatment on the connective tissue portion tissues. Plasma-MAC group highlighted the best performance. This behavior appeared strictly correlated with the soft tissue thickness.

Evaluation of residual contamination on reused healing abutments

OBJECTIVES

The purpose of this study is to evaluate residual contamination of healing abutments sterilized by dealers of dental implant companies.

MATERIAL AND METHODS

Healing abutments collected from dealers of different implant companies were randomly numbered, and they were examined for visible deformation and contamination on the abutment surface, packaging errors, and presence of a sterilization indicator. The healing abutments were stained with a dye solution for contamination detection and evaluated by dividing into different regions. The presence of residual contamination was examined through photographic images taken from the healing abutments and the data obtained were recorded. Pearson's chi-square analysis was used to evaluate the relation between implant brands and contamination status. Significance was evaluated as p <0.05.

RESULTS

Visible residual contamination was detected in approximately 31% of the healing abutments. After the staining procedure, in the visual assessment of the stained surfaces, residual contamination was found in at least one region of all healing abutments except one (n=176, 99.4%). The most intense staining was seen in the screw driver hole (n=172, 97.1%), body (n=113, 63.8%), occlusal (n=107, 60.4%), screw (n=79, 44.6%), and connector (n=72, 40.6%) regions, respectively. A significant relationship was found between the brands and the contamination status (p <0.05).

CONCLUSION

The reuse of healing abutments is not suitable, as it does not ensure optimum cleaning and sterilization, and it is not possible to eliminate contaminants completely.

CLINICAL RELEVANCE

Despite the economic benefits of multiple use of healing abutments, disadvantages should be carefully evaluated by clinicians.

Crystallinity of TiO2 nanotubes and its effects on fibroblast viability, adhesion, and proliferation

Titanium and titanium alloys are widely used as a biomaterial due to their mechanical strength, corrosion resistance, low elastic modulus, and excellent biocompatibility. TiO₂ nanotubes have excellent bioactivity, stimulating the adhesion, proliferation of fibroblasts and adipose-derived stem cells, production of alkaline phosphatase by osteoblasts, platelets activation, growth of neural cells and adhesion, spreading, growth, and differentiation of rat bone marrow mesenchymal stem cells. In this study, we investigated the functionality of fibroblast on titania nanotube layers annealed at different temperatures. The titania nanotube layer was fabricated by potentiostatic anodization of titanium, then annealed at 300, 530, and 630 °C for 5 h. The resulting nanotube layer was characterized using SEM (Scanning Electron Microscopy), TF-XRD (Thin-film X-ray diffraction), and contact angle goniometry. Fibroblasts viability was determined by the CellTiter-Blue method and cytotoxicity by Lactate Dehydrogenase test, and the cell morphology was analyzed by scanning electron microscopy. Also, cell adherence, proliferation, and morphology were analyzed by fluorescence microscopy. The results indicate that the modification in nanotube crystallinity may provide a favorable surface fibroblast growth, especially on substrates annealed at 530 and 630 °C, indicating that these properties provide a favorable template for biomedical implants.

The Effect of Different Cleaning Protocols of Polymer-Based Prosthetic Materials on the Behavior of Human Gingival Fibroblasts

Dental implant abutment and prosthetic materials, their surface treatment, and cleaning modalities are important factors for the formation of a peri-implant soft tissue seal and long-term stability of bone around the implant. This study aimed to investigate the influence of a polymeric material surface cleaning method on the surface roughness, water contact angle, and human gingival fibroblasts (HGF) proliferation. Polymeric materials tested: two types of milled polymethylmethacrylate (PMMA-Ker and PMMA-Bre), three-dimensionally (3D) printed polymethylmethacrylate (PMMA-3D), polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). Titanium (Ti) and zirconia oxide ceramics (ZrO-HT) were used as positive controls. A conventional surface cleaning protocol (CCP) was compared to a multi-step research cleaning method (RCP). Application of the RCP method allowed to reduce S_a values in all groups from 0.14-0.28 µm to 0.08-0.17 µm (p < 0.05 in PMMA-Ker and PEEK groups). Moreover, the water contact angle increased in all groups from 74-91° to 83-101° (p < 0.05 in the PEKK group), except ZrO-HT-it was reduced from 98.7 ± 4.5° to 69.9 ± 6.4° (p < 0.05). CCP resulted in higher variability of HGF viability after 48 and 72 h. RCP application led to higher HGF viability in PMMA-3D and PEKK groups after 48 h, but lower for the PMMA-Ker group (p < 0.05). After 72 h, no significant differences in HGF viability between both cleaning methods were observed. It can be concluded that the cleaning method of the polymeric materials affected surface roughness, contact angle, and HGF viability at 48 h.

Photo and Plasma Activation of Dental Implant Titanium Surfaces. A Systematic Review with Meta-Analysis of Pre-Clinical Studies

Background: Ultraviolet (UV) and non-thermal plasma functionalization are surface treatment modalities that seem able to improve osseointegration. The aim of this systematic review and meta-analysis is to assess the effect of the two methods and possible differences. Materials and Methods: The systematic research of pre-clinical animal studies was conducted up to May 2020 in the databases PubMed/Medline, Scopus and the Cochrane Lybrary. A meta-analysis was performed by using the DerSimonian–Laird estimator in random-effects models. Results: Through the digital search, 518 articles were identified; after duplicate removal and screening process 10 papers were included. Four studies evaluating UV treatment in rabbits were included in the meta-analysis. The qualitative evaluation of the included studies showed that both UV photofunctionalization and non-thermal plasma argon functionalization of titanium implant surfaces might be effective in vivo to improve the osseointegration. The meta-analysis on four studies evaluating UV treatment in rabbits showed that bone to implant contact values (expressed as standardized mean differences and raw mean differences) were significantly increased in the bio-activated groups when follow-up times were relatively homogeneous, although a high heterogeneity (I² > 75%) was found in all models. Conclusions: The present systematic review and meta-analysis on pre-clinical studies demonstrated that chair-side treatment of implants with UV or non-thermal plasma appear to be effective for improving osseointegration. This systematic review supports further clinical trials on this topic.