How Tony Melcher advanced our understanding of periodontal biology and regeneration.

Tony Melcher, a highly influential and forward-thinking scientist and teacher, focussed on the origins, behaviour and regulation of cells in periodontal tissues. His recent death in April 2020, has motivated us to highlight his multi-level contributions to research in biology and the dental sciences. Tony was particularly adept at recognizing the inherent instructive power of the periodontium, most notably as a model system for studying the inter-relationships between the structure, development and functions of connective tissues.

Novel grooved substrata stimulate macrophage fusion, CCL2 and MMP-9 secretion.

Rough surface topographies on implants attract macrophages but the influence of topography on macrophage fusion to produce multinucleated giant cells (MGC) and foreign body giant cells (FBGC) is unclear. Two rough novel grooved substrata, G1 and G2, fabricated by anisotropic etching of Silicon <110> crystals without the use of photolithographic patterning, and a control smooth surface (Pol) were produced and replicated in epoxy. The surfaces were compared for their effects on RAW264.

The effect of surface roughness on RAW 264.7 macrophage phenotype.

Monocyte-derived cells, including macrophages and foreign body giant cells, can determine the performance of implanted devices. Upon contact with biomaterials, macrophages can be activated into a classic inflammatory (M1) or wound-healing (M2) phenotype. Previously, we showed that high macrophage density on rough SLA implants was associated with early bone formation.

The effect of surface topography on cell shape and early ERK1/2 signaling in macrophages; linkage with FAK and Src.

Implant surface topography can modulate macrophage behavior during wound healing by the production of proinflammatory cytokines. This study investigated the activation of FAK, Src, and ERK1/2 signaling intermediates of the proinflammatory ERK1/2 pathway in RAW 264.7 macrophages in response to polished (P), coarse-grit-blasted (B), acid etched (E), and grit-blasted and etched (SLA) surface topographies.

Standardization of clinical protocols in oral malodor research.

The objective of this study is to standardize protocols for clinical research into oral malodor caused by volatile sulfur compounds (VSCs). To detect VSCs, a gas chromatograph (GC) using a flame photometric detector equipped with a bandpass filter (at 393 nm) is the gold standard (sensitivity: 5 × 10(-11) gS s(-1)). The baselines of VSC concentrations in mouth air varied considerably over a week.

Drug intercalation in layered double hydroxide clay: application in the development of a nanocomposite film for guided tissue regeneration.

It has been proposed that localized and controlled delivery of alendronate and tetracycline to periodontal pocket fluids via guided tissue regeneration (GTR) membranes may be a valuable adjunctive treatment for advanced periodontitis. The objectives of this work were to develop a co-loaded, controlled release tetracycline and alendronate nanocomposite plasticized poly(lactic-co-glycolic acid) (PLGA) film that would form a suitable matrix supporting osteoblast proliferation and differentiation. Alendronate release was successfully controlled, with complete suppression of the burst phase of release by intercalation of alendronate anions in magnesium/aluminum layered double hydroxide (LDH) clay nanoparticles and dispersed in the PLGA film matrix.

An in vitro study of plasticized poly(lactic-co-glycolic acid) films as possible guided tissue regeneration membranes: material properties and drug release kinetics.

Guided tissue regeneration (GTR), in periodontal therapy, involves the placement of a barrier membrane, to ensure the detached root surface becomes repopulated with periodontal ligament cells capable of regenerating this attachment. GTR procedures exhibit large variability in surgical outcome as a consequence of poor membrane performance. The objective of this study was to evaluate the suitability of plasticized poly(lactic-co-glycolic acid) (PLGA) as a material for GTR membranes.

The effect of surface topography on early NFκB signaling in macrophages.

Surface topography modulates macrophage expression of pro-inflammatory cytokines through triggering of a number of different signaling pathways. In this article, we investigated the early activation of the NFκB pathway in RAW 264.7 macrophages in response to four surface topographies: mechanically polished (PO), coarse sand blasted (CB), acid etched (AE), and sandblasted and acid etched (SLA).

Bone formation on rough, but not polished, subcutaneously implanted Ti surfaces is preceded by macrophage accumulation.

Implanted rough surfaces have long been associated with the accumulation of macrophages and other cells of the monocytic lineage such as foreign body giant cells and osteoclasts. As cells of the moncytic lineage are part of the immune system, the response of this cell family to biomaterials has attracted wide concern. This study compared events at the interface of implant surface topographies with varied roughness in a rat subcutaneous model.

Comparison of the response of cultured osteoblasts and osteoblasts outgrown from rat calvarial bone chips to nonfouling KRSR and FHRRIKA-peptide modified rough titanium surfaces.

Mimicking proteins found in the extracellular matrix (ECM) using specific peptide sequences is a well-known strategy for the design of biomimetic surfaces, but has not yet been widely exploited in the field of biomedical implants. This study investigated osteoblast and, as a control, fibroblast proliferation to novel consensus heparin-binding peptides sequences KRSR and FHRIKKA that were immobilized onto rough (particle-blasted and chemically etched) commercially pure titanium surfaces using a poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) molecular assembly system. This platform enabled a detailed study of specific cell-peptide interactions even in the presence of serum in the culture medium; thanks to the excellent nonfouling properties of the PLL-g-PEG surface.

Directional change produced by perpendicularly-oriented microgrooves is microtubule-dependent for fibroblasts and epithelium.

Anisotropic substrata such as micromachined grooves can control cell shape, orientation, and the direction of cell movement, a phenomena termed topographic guidance. Although many types of cells exhibit topographic guidance, little is known regarding cell responses to conflicting topographic cues. We employed a substratum with intersecting grooves in order to present fibroblasts and epithelial cells with conflicting topographic cues.

Controlled release of alendronate from polymeric films.

Bisphosphonate drugs alter the balance of bone resorption and formation, leading to a net increase in bone density. Therefore, these drugs are commonly used to treat osteoporosis or as an adjunct to cancer chemotherapy. Local delivery of bisphosphonates, such as alendronate, from polymeric films has the potential to improve efficacy and decrease side-effects common to oral bisphosphonate therapy.

Modulation of human gingival fibroblast adhesion, morphology, tyrosine phosphorylation, and ERK 1/2 localization on polished, grooved and SLA substratum topographies.

Attachment of connective tissue to dental implants, which is influenced by surface topography, is an important determinant of implant success. Approaches employed to alter topography include acid etching or blasting to produce roughened surfaces, and production of precisely defined topographies using microfabrication techniques. The aim of this study was to assess the influence of polished, microgrooved, and sand-blasted, large grit, acid-etched (SLA) topographies on fibroblast adhesion, morphology, activation, and ERK 1/2 phosphorylation and localization.

Fabrication of TiO2-coated epoxy replicas with identical dual-type surface topographies used in cell culture assays.

The goal of this study was to reproducibly generate samples with complex surface topographies and chemistries identical to a "master surface" and to test their response in cell culture using rat calvarial cells. Negative replicas of dual-type topography were fabricated using dental impression material with half of the surface exhibiting smooth and rough topography, respectively. Positive epoxy resin replicas were cast from the same negative replica eight times consecutively and coated with a 60-nm thin film of titanium dioxide using a vapor deposition technique.

Triton X-100 pretreatment of LR-white thin sections improves immunofluorescence specificity and intensity.

The staining of intracellular antigenic sites in postembedded samples is a challenging problem. Deterioration of antigenicity and limited antibody accessibility to the antigen are commonly encountered on account of processing steps. In this study preservation of the antigen was achieved by fixing the tissues with mild fixatives, performing partial dehydration, and embedding in a low crosslinked hydrophilic acrylic resin, LR-White.

Comparative response of epithelial cells and osteoblasts to microfabricated tapered pit topographies in vitro and in vivo.

Microfabricated tapered pits in vivo can stimulate connective tissue and bone attachment to percutaneous devices, secondarily preventing epithelial migration, and promoting long-term implant survival. Epithelial cells, which form a seal with a dental implant, acting as a barrier, and osteoblasts, which form bone, can come into contact with the same implant topography. To investigate whether the phenotypic characteristics of each cell type influenced cell response to micro-topography, we compared the response of the two cell types to the same dimensions of tapered pits, in vitro, and in vivo.

The effect of substratum topography on osteoblast adhesion mediated signal transduction and phosphorylation.

Substratum surface topography is a powerful modulator of cell behaviour, but how it influences intracellular signaling is largely unknown. We investigated the influence of microfabricated topographies on the activation of nonreceptor tyrosine kinases Src, FAK and ERK 1/2, as well as the transcription factor, Runx2, in rat osteoblasts, cultured on substrata that varied in their ability to promote bone-like tissue formation. Total tyrosine phosphorylation increased on grooves, tapered pits, and gap cornered boxes, relative to the levels found on smooth surfaces, with the greatest activity at 1 week.

Effects of surface topography on the connective tissue attachment to subcutaneous implants.

Purpose: A major concern for implants that penetrate stratified epithelia is aggressive epithelial proliferation and migration. This epithelial downgrowth on the implant can be inhibited by a firm attachment between the underlying connective tissue and the implant. This study evaluates the connective tissue attachment to titanium implants with various well-defined surface topographies.

Biomimetic modification of titanium dental implant model surfaces using the RGDSP-peptide sequence: a cell morphology study.

Surface topography and (bio)chemistry are key factors in determining cell response to an implant. We investigated cell adhesion and spreading patterns of epithelial cells, fibroblasts and osteoblasts on biomimetically modified, smooth and rough titanium surfaces. The RGD bioactive peptide sequence was immobilized via a non-fouling poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) molecular assembly system, which allowed exploitation of specific cell-peptide interactions even in the presence of serum.

Effect of titanium surface topography on macrophage activation and secretion of proinflammatory cytokines and chemokines.

The macrophage has a major role in normal wound healing and the reparative process around implants. Murine macrophage-like cells RAW 264.7 were used to investigate the effect of titanium surfaces on macrophage activation and secretion of proinflammatory cytokines [interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha] and chemokines (monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 alpha).

Introduction to the proceedings of the Fifth International Conference on Breath Odour Research.

These proceedings represent a sample of the many fine papers that were presented at the Fifth International Conference on Breath Odour Research held in Tokyo on 2-3 July 2001. Space limitations precluded publication of all the papers, and the ones selected illustrate the diversity of approaches and the international nature of breath odour research.

Use of Ti-coated replicas to investigate the effects on fibroblast shape of surfaces with varying roughness and constant chemical composition.

A two-stage replica technique with a subsequent titanium (Ti)-coating treatment was used to faithfully replicate topographies of polished, acid-etched, machined-like, finely blasted, coarsely blasted, coarsely blasted and acid-etched, and Ti plasma-sprayed Ti surfaces. The replicas were used to study the influence of different rough surface topographies on the response of human fibroblasts in vitro under conditions of constant surface chemistry for all surfaces. The surface topographies of the replicas were characterized using non-contact laser profilometry, scanning electron microscopy (SEM), and stereo-SEM, whereas surface chemistry was examined using X-ray photoelectron spectroscopy.

The use of diagnostic data in clinical dental practice.

This article has briefly introduced the dental clinician to the principles and practical application of diagnostic decision analysis. There are trade-offs and uncertainties in the process of arriving at a diagnosis, but they can be understood and controlled. First, the clinician must understand the significance of disease prevalence and assign to the patient an initial probability of disease being present.

Subcutaneous microfabricated surfaces inhibit epithelial recession and promote long-term survival of percutaneous implants.

The long-term success of percutaneous devices is compromised by problems such as infection, mechanical avulsion and epithelial downgrowth. The objective of this study was to test the effects of microfabricated surfaces on tissue integration and long-term survival of percutaneous implants, using a modified implant design and a two-stage surgical method. Hexagonal titanium-coated epoxy implants were constructed with separate subcutaneous and percutaneous components, so that the effects of surface topography on connective tissue could be separated from the effects on epithelium.