A Systematic Review and Meta-Analysis Comparing Surgical and Nonsurgical Treatments for Excessive Gingival Display.

Excessive gingival display (EGD) is defined as more than 2 mm of gingiva display above the maxillary incisors at maximum smile. Various skeletal, dental, and soft tissue etiological factors for EGD have been suggested. This study assessed the effectiveness and stability of surgical (SX) and nonsurgical (NSX) interventions for correction of EGD through a systematic review and meta-analysis following PRISMA 2020 guidelines. An electronic search of Ovid MEDLINE, EMBASE, CENTRAL, Scopus, Web of Science, and LILACS was conducted (2010-2023). Results were expressed as mean change in gingival display using the random-effects model at 1, 3, 6, and 12-month follow-up. At 1 month, SX and NSX treatments yielded a comparable mean reduction of 3.50 mm (2.13-4.86) and 3.43 mm (2.67-4.19) in gingival display, respectively. However, by 6 months, NSX treatments showed a reduction of 0.51 mm compared to 2.86 mm with SX treatments. SX outcomes remained stable past 6 months, while NSX outcomes partially relapsed at 6 months and returned to baseline levels at 12 months. Notably, NSX treatments were more effective in cases with mild initial EGD, while SX treatments showed a better outcome in severe cases. To draw more robust conclusions regarding the treatment outcomes, future primary studies of greater rigor are required.

Relative contributions of implant hydrophilicity and nanotopography to implant anchorage in bone at Early Time Points.

OBJECTIVE: To compare the contributions of implant hydrophilicity and nanotopography on anchorage in bone. The effect of elevated calcium surface chemistry on bone anchorage was also investigated. MATERIALS AND METHODS: A full factorial study design was implemented to evaluate the effects of ultraviolet (UV) light and/or sodium lactate (SL) and discrete crystalline deposition of nanocrystals (DCD) treatments on the osseointegration of dual acid-etched (AE) titanium alloy (Ti6Al4V) and grit blasted and AE (BAE) commercially pure titanium (CpTi) implants. Sodium hydroxide (NaOH)-treated CpTi implants were immersed in simulated body fluid (SBF) to increase calcium surface chemistry. Implants were placed in the femora of Wistar rats and tested using pull-out testing (BAE implants: 5, 9, 14 days) or tensile testing (AE implants: 9 days, NaOH implants: 28 days). RESULTS: Ti6Al4V-AE implants with DCD- and UV-treated surfaces significantly increased bone anchorage compared with untreated Ti6Al4V-AE alloy implants. Pull-out testing of BAE-CpTi implants with the DCD treatment showed increased disruption force values compared with surfaces without the DCD treatment at 5, 9 and 14 days by 4.1N, 13.9N and 15.5N, respectively, and UV-treated implants showed an increase at 14 days by 8.4N. No difference was found between NaOH + SBF and NaOH + H2 O groups. CONCLUSIONS: Bone anchorage of implants was found to be improved by UV-treating implants or nanotopographically complex surfaces. However, implant nanotopography was found to have a greater contribution to the overall bone anchorage and is more consistent compared with the time-dependent nature of the UV treatment.

A "best fit" approach for synergistic surface parameters to guide the design of candidate implant surfaces.

Human bone resorption surfaces can provide a template for endosseous implant surface design. We characterized the topography of such sites using four synergistic parameters (fractal dimension, lacunarity, porosity, and surface roughness) and compared the generated values with those obtained from two groups of candidate titanium implant surfaces. For the first group (n = 5/group): grit-blasted acid etched (BAE), BAE with either discrete calcium phosphate crystal deposition or nanotube formation, machined titanium with nanotubes, or a nanofiber surface; each measured synergistic parameter was statistically compared with that of the resorbed bone surface and scored for inclusion in a "best fit" analysis. The analysis informed changes that could be made to a candidate implant surface to render it a closer "best fit" to that of the resorbed bone surface. In a second group of either titanium or titanium alloy implants their micro-topography, created by dual acid etching, was the same for each material substrate; but their nanotopographic complexity was changed by varying the degree of calcium phosphate crystalline deposits. These implants were also used in vivo where bone anchorage was tested using a tensile disruption test; and the "best fit" of synergistic parameters coincided with the best biological outcome for both titanium and titanium alloy implants. In conclusion, the four chosen synergistic parameters can be used to guide the sub-micron surface design of candidate implants, and our "best fit" approach is capable of identifying the surfaces with the best biological outcomes. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2165-2177, 2019.

Intravital Imaging for Tracking of Angiogenesis and Cellular Events Around Surgical Bone Implants.

IMPACT STATEMENT: These new experimental methods allow us to image, and quantify, angiogenesis and perivascular cell dynamics in the endosseous healing compartment. As such, the method is capable of providing a new perspective on, and unique information regarding, healing that occurs around orthopedic and dental implants.

Topographic scale-range synergy at the functional bone/implant interface.

We sought to explore the biological mechanisms by which endosseous implant surface topography contributes to bone anchorage. To address this experimentally, we implanted five groups of custom-made commercially pure titanium implants of varying surface topographical complexity in rat femora for 9 days; subjected them to mechanical testing; and then examined the interfacial bone matrix by electron microscopy. The five implant surfaces were prepared by combinations of dual acid etching and grit blasting the titanium substrates and, in some cases, modifying the created surfaces with the deposition of nanocrystals of calcium phosphate, which resulted in 10 samples per group. In parallel, we cultured rat bone marrow cells on surrogate implants constructed from polymer resin coated with the same calcium phosphate nanocrystals, and monitored the deposition of bone sialoprotein by transmission electron immunohisto-micrography. We found that implant samples modified with sub-micron scale crystals were bone-bonding, as described by the interdigitation of a mineralized cement line matrix with the underlying implant surface. The in vitro assay showed that bone sialoprotein could be deposited in the interstices between, and undercuts below, the nanocrystals. In addition, when mineralized, the cement line matrix globules occupied micron-sized pits in the implant surfaces, and in part obliterated them, creating an additional form of anchorage. Our results also showed that collagen, elaborated by the osteogenic cells, wrapped around the coarse-micron features, and became mineralized in the normal course of bone formation. This provided a mechanism by which coarse-micron implant features contributed to a functional interface, which we have previously described, that is capable of resisting the mechanical loading that increases as peri-implant bone matures. Thus, our findings provide mechanistic explanations for the biologically-relevant criteria that can be employed to assess the importance of implant surface topography at different scale-ranges.

The roles of different scale ranges of surface implant topography on the stability of the bone/implant interface.

We sought to deconvolute the effects of sub-micron topography and microtopography on the phenomena of bone bonding and interfacial stability of endosseous implants. To address this experimentally, we implanted custom-made titanium alloy implants of varying surface topographical complexity in rat femora, for 6, 9 or 12 days. The five surfaces were polished, machined, dual acid etched, and two forms of grit blasted and acid etched; each surface type was further modified with the deposition of nanocrystals of calcium phosphate to make a total of 10 materials groups (n = 10 for each time point; total 300 implants). At sacrifice, we subjected the bone-implant interface to a mechanical disruption test. We found that even the smoothest surfaces, when modified with sub-micron scale crystals, could be bone-bonding. However, as locomotor loading through bone to the implant increased with time of healing, such interfaces failed while others, with sub-micron features superimposed on surfaces of increasing microtopographical complexity remained intact under loading. We demonstrate here that higher order, micron or coarse-micron, topography is a requirement for longer-term interfacial stability. We show that each of these topographical scale-ranges represents a scale-range seen in natural bone tissue. Thus, what emerges from an analysis of our findings is a new means by which biologically-relevant criteria can be employed to assess the importance of implant surface topography at different scale-ranges.

Periodontal regeneration using a bilayered PLGA/calcium phosphate construct.

The regeneration of tissues affected by periodontal disease is a complex process; it encompasses the formation of bone, cementum and periodontal ligament. We developed a semi-rigid PLGA (polylactide-co-glycolide acid)/CaP (calcium phosphate) bilayered biomaterial construct to promote periodontal regeneration, which has a continuous outer barrier membrane and an inner topographically complex component. Our experimental model compared periodontal prophylaxis alone with prophylaxis and biomaterial implantation in the treatment of class II furcation defects in dogs. Clinical evaluation, micro-computed tomography, histology and backscattered electron imaging were used for data analysis. Healing occurred uneventfully and bone volumetric values, trabecular number and trabecular thickness were all significantly greater in the treated group; while trabecular separation was significantly greater in the control group. New cementum, bone, and periodontal ligament with Sharpey fibre insertions were only seen in the treated group. Although periodontal regeneration has been reported elsewhere, the advantages of employing our bilayered PLGA + CaP construct are twofold: 1)it did not collapse into the defect; and, 2) its inner side was able to retain the blood clot throughout the buccal defect. The result was greater periodontal regeneration than has previously been reported with traditional flexible membranes.

Development, characterization and clinical use of a biodegradable composite scaffold for bone engineering in oro-maxillo-facial surgery.

We have developed a biodegradable composite scaffold for bone tissue engineering applications with a pore size and interconnecting macroporosity similar to those of human trabecular bone. The scaffold is fabricated by a process of particle leaching and phase inversion from poly(lactideco-glycolide) (PLGA) and two calcium phosphate (CaP) phases both of which are resorbable by osteoclasts; the first a particulate within the polymer structure and the second a thin ubiquitous coating. The 3-5 µm thick osteoconductive surface CaP abrogates the putative foreign body giant cell response to the underlying polymer, while the internal CaP phase provides dimensional stability in an otherwise highly compliant structure. The scaffold may be used as a biomaterial alone, as a carrier for cells or a three-phase drug delivery device. Due to the highly interconnected macroporosity ranging from 81% to 91%, with macropores of 0.8∼1.8 mm, and an ability to wick up blood, the scaffold acts as both a clot-retention device and an osteoconductive support for host bone growth. As a cell delivery vehicle, the scaffold can be first seeded with human mesenchymal cells which can then contribute to bone formation in orthotopic implantation sites, as we show in immune-compromised animal hosts. We have also employed this scaffold in both lithomorph and particulate forms in human patients to maintain alveolar bone height following tooth extraction, and augment alveolar bone height through standard sinus lift approaches. We provide a clinical case report of both of these applications; and we show that the scaffold served to regenerate sufficient bone tissue in the wound site to provide a sound foundation for dental implant placement. At the time of writing, such implants have been in occlusal function for periods of up to 3 years in sites regenerated through the use of the scaffold.

Discrete calcium phosphate nanocrystalline deposition enhances osteoconduction on titanium-based implant surfaces.

We sought to assess the ability of nanotopographically complex titanium surfaces to accelerate osteoconduction. For this, 130 miniature bone ingrowth chambers (called "T plants"), fabricated from either commercially pure titanium (cpTi) or titanium alloy (Ti6Al4V or Ti64), with microtopographically complex surfaces were used in the study, of which 50 were further modified by the discrete crystalline deposition (DCD) of calcium phosphate (CAP) nanoparticles that superimposed a nanotopographic complexity on each implant surface. Thus, four experimental groups were generated (cpTi, cpTi-DCD, Ti64, and Ti64-DCD), and the Tplants were implanted bilaterally in the femora of Wistar rats for 9 days. After harvesting, the femora were trimmed, and multiple-mounted samples were embedded in PMMA. The blocks produced were ground and block faces observed by back-scattering electron imaging (BSEI) at different planes through the chambers. Osteoconduction was assessed, as a function of bone-implant contact, on a total of 1087 BSEI micrographs and submitted to rigorous statistical analyses. Our results showed both the important effects of anatomic location on bone ingrowth and the significant increase in osteoconduction (p < 0.001) as a function of the enhanced surface nanotopography obtained by the CAP nanocrystals.

The effect of discrete calcium phosphate nanocrystals on bone-bonding to titanium surfaces.

We sought to address the question: Can metallic surfaces be rendered bone-bonding? We employed dual acid-etched (DAE) commercially pure titanium (cpTi) and titanium alloy (Ti6Al4V) custom-made rectangular coupons (1.3 mm x 2.5 mm x 4 mm) with, or without, further modification by the discrete crystalline deposition (DCD) of calcium phosphate (CAP) nanocrystals. A total of 48 implants comprising four groups were placed bilaterally in the distal femur of male Wistar rats for 9 days. After harvesting, the bone immediately proximal and distal to the implant was removed, resulting in a test sample comprising the implant with two attached cortical arches. The latter were distracted at 30 mm/min, in an Instron machine, and the disruption force was recorded. Results showed that alloy samples exhibited greater disruption forces than cpTi, and that DCD samples had statistically significantly greater average disruption forces than non-DCD samples. The bone-bonding phenomenon was visually evident by fracture of the cortical arches and an intact bone/implant interface. Field emission scanning electron microscopy showed the bone/implant interface was occupied by a bony cement line matrix that was interlocked with the surface topographical features of the implant. We conclude that titanium implant surfaces can be rendered bone-bonding by an increase in the complexity of the surface topography.