Cell Type-Specific Effects of Implant Provisional Restoration Materials on the Growth and Function of Human Fibroblasts and Osteoblasts

Comparative Analysis of Periodontal Parameters and Patient Satisfaction Utilising Different Temporary Crown Fabrication Techniques: A Parallel-Group Randomised Controlled Trial

Aim The study aims to evaluate the efficacy of different techniques for temporary crown fabrication in maintaining periodontal health and patient satisfaction, addressing a critical gap in the existing literature and informing evidence-based clinical practices. Materials and methods This study, conducted in accordance with CONSORT guidelines, was a parallel-group randomised trial conducted at a dental institute in India. In total, 36 participants aged 18-65 requiring anterior tooth region crowns were randomly assigned to three groups: direct (control), indirect (Test Group 1) and direct-indirect (Test Group 2) fabrication techniques. Participants were selected from outpatient departments based on eligibility criteria, and interventions were allocated using randomization tables. Outcome assessments included gingival health metrics and patient satisfaction levels, with statistical analyses performed using the Kruskal-Wallis test. Results Significant differences were observed in the pink esthetic score (PES) and patient satisfaction (P=0.029) among the three groups, with the direct-indirect technique group demonstrating the highest median PES (9 out of 10). However, no significant disparities were noted in the plaque index (PI) or probing depth (PD) among the groups. Conclusion The direct-indirect technique demonstrated superior PES and patient satisfaction, indicating potential benefits for periodontal health and patient experiences. Integration of virtual preparation workflows may optimise outcomes, but further research is needed for validation and guideline development.

Disparity in the Influence of Implant Provisional Materials on Human Gingival Fibroblasts with Different Phases of Cell Settlement: An In Vitro Study

The development of healthy peri-implant soft tissues is critical to achieving the esthetic and biological success of implant restorations throughout all stages of healing and tissue maturation, starting with provisionalization. The purpose of this study was to investigate the effects of eight different implant provisional materials on human gingival fibroblasts at various stages of cell settlement by examining initial cell attachment, growth, and function. Eight different specimens-bis-acrylic 1 and 2, flowable and bulk-fill composites, self-curing acrylic 1 and 2, milled acrylic, and titanium (Ti) alloy as a control-were fabricated in rectangular plates (n = 3). The condition of human gingival fibroblasts was divided into two groups: those in direct contact with test materials (contact experiment) and those in close proximity to test materials (proximity experiment). The proximity experiment was further divided into three phases: pre-settlement, early settlement, and late settlement. A cell culture insert containing each test plate was placed into a well where the cells were pre-cultured. The number of attached cells, cell proliferation, resistance to detachment, and collagen production were evaluated. In the contact experiment, bis-acrylics and composites showed detrimental effects on cells. The number of cells attached to milled acrylic and self-curing acrylic was relatively high, being approximately 70% and 20-30%, respectively, of that on Ti alloy. There was a significant difference between self-curing acrylic 1 and 2, even with the same curing modality. The cell retention ability also varied considerably among the materials. Although the detrimental effects were mitigated in the proximity experiment compared to the contact experiment, adverse effects on cell growth and collagen production remained significant during all phases of cell settlement for bis-acrylics and flowable composite. Specifically, the early settlement phase was not sufficient to significantly mitigate the material cytotoxicity. The flowable composite was consistently more cytotoxic than the bulk-fill composite. The harmful effects of the provisional materials on gingival fibroblasts vary considerably depending on the curing modality and compositions. Pre-settlement of cells mitigated the harmful effects, implying the susceptibility to material toxicity varies depending on the progress of wound healing and tissue condition. However, cell pre-settlement was not sufficient to fully restore the fibroblastic function to the normal level. Particularly, the adverse effects of bis-acrylics and flowable composite remained significant. Milled and self-curing acrylic exhibited excellent and acceptable biocompatibility, respectively, compared to other materials.

Genome-wide transcriptional responses of osteoblasts to different titanium surface topographies

This is the first genome-wide transcriptional profiling study using RNA-sequencing to investigate osteoblast responses to different titanium surface topographies, specifically between machined, smooth and acid-etched, microrough surfaces. Rat femoral osteoblasts were cultured on machine-smooth and acid-etched microrough titanium disks. The culture system was validated through a series of assays confirming reduced osteoblast attachment, slower proliferation, and faster differentiation on microrough surfaces. RNA-sequencing analysis of osteoblasts at an early stage of culture revealed that gene expression was highly correlated (r = 0.975) between the two topographies, but 1.38 % genes were upregulated and 0.37 % were downregulated on microrough surfaces. Upregulated transcripts were enriched for immune system, plasma membrane, response to external stimulus, and positive regulation to stimulus processes. Structural mapping confirmed microrough surface-promoted gene sharing and networking in signaling pathways and immune system/responses. Target-specific pathway analysis revealed that Rho family G-protein signaling pathways and actin genes, responsible for the formation of stress fibers, cytoplasmic projections, and focal adhesion, were upregulated on microrough surfaces without upregulation of core genes triggered by cell-to-cell interactions. Furthermore, disulfide-linked or -targeted extracellular matrix (ECM) or membranous glycoproteins such as laminin, fibronectin, CD36, and thrombospondin were highly expressed on microrough surfaces. Finally, proliferating cell nuclear antigen (PCNA) and cyclin D1, whose co-expression reduces cell proliferation, were upregulated on microrough surfaces. Thus, osteoblasts on microrough surfaces were characterized by upregulation of genes related to a wide range of functions associated with the immune system, stress/stimulus responses, proliferation control, skeletal and cytoplasmic signaling, ECM-integrin receptor interactions, and ECM-membranous glycoprotein interactions, furthering our knowledge of the surface-dependent expression of osteoblastic biomarkers on titanium.

Vacuum Ultraviolet (VUV) Light Photofunctionalization to Induce Human Oral Fibroblast Transmigration on Zirconia

Soft tissue adhesion and sealing around dental and maxillofacial implants, related prosthetic components, and crowns are a clinical imperative to prevent adverse outcomes of periodontitis and periimplantitis. Zirconia is often used to fabricate implant components and crowns. Here, we hypothesized that UV treatment of zirconia would induce unique behaviors in fibroblasts that favor the establishment of a soft tissue seal. Human oral fibroblasts were cultured on zirconia specimens to confluency before placing a second zirconia specimen (either untreated or treated with one minute of 172 nm vacuum UV (VUV) light) next to the first specimen separated by a gap of 150 µm. After seven days of culture, fibroblasts only transmigrated onto VUV-treated zirconia, forming a 2.36 mm volume zone and 5.30 mm leading edge. Cells migrating on VUV-treated zirconia were enlarged, with robust formation of multidirectional cytoplastic projections, even on day seven. Fibroblasts were also cultured on horizontally placed and 45° and 60° tilted zirconia specimens, with the latter configurations compromising initial attachment and proliferation. However, VUV treatment of zirconia mitigated the negative impact of tilting, with higher tilt angles increasing the difference in cellular behavior between control and VUV-treated specimens. Fibroblast size, perimeter, and diameter on day seven were greater than on day one exclusively on VUV-treated zirconia. VUV treatment reduced surface elemental carbon and induced superhydrophilicity, confirming the removal of the hydrocarbon pellicle. Similar effects of VUV treatment were observed on glazed zirconia specimens with silica surfaces. One-minute VUV photofunctionalization of zirconia and silica therefore promotes human oral fibroblast attachment and proliferation, especially under challenging culture conditions, and induces specimen-to-specimen transmigration and sustainable photofunctionalization for at least seven days.

Conditional Mitigation of Dental-Composite Material-Induced Cytotoxicity by Increasing the Cure Time

Light-cured composite resins are widely used in dental restorations to fill cavities and fabricate temporary crowns. After curing, the residual monomer is a known to be cytotoxic, but increasing the curing time should improve biocompatibility. However, a biologically optimized cure time has not been determined through systematic experimentation. The objective of this study was to examine the behavior and function of human gingival fibroblasts cultured with flowable and bulk-fill composites cured for different periods of time, while considering the physical location of the cells with regard to the materials. Biological effects were separately evaluated for cells in direct contact with, and in close proximity to, the two composite materials. Curing time varied from the recommended 20 s to 40, 60, and 80 s. Pre-cured, milled-acrylic resin was used as a control. No cell survived and attached to or around the flowable composite, regardless of curing time. Some cells survived and attached close to (but not on) the bulk-fill composite, with survival increasing with a longer curing time, albeit to <20% of the numbers growing on milled acrylic even after 80 s of curing. A few cells (<5% of milled acrylic) survived and attached around the flowable composite after removal of the surface layer, but attachment was not cure-time dependent. Removing the surface layer increased cell survival and attachment around the bulk-fill composite after a 20-s cure, but survival was reduced after an 80-s cure. Dental-composite materials are lethal to contacting fibroblasts, regardless of curing time. However, longer curing times mitigated material cytotoxicity exclusively for bulk-fill composites when the cells were not in direct contact. Removing the surface layer slightly improved biocompatibility for cells in proximity to the materials, but not in proportion to cure time. In conclusion, mitigating the cytotoxicity of composite materials by increasing cure time is conditional on the physical location of cells, the type of material, and the finish of the surface layer. This study provides valuable information for clinical decision making and novel insights into the polymerization behavior of composite materials.