Highlights • Atemporal osseointegration would improve patient's function and quality of life. • Accelerating/improving osseointegration demands combined and multiple engineering domains. • ...Hierarchical designing shall provide an informed design rationale for development. • Implant macrogeometry and surgical technique define the osseointegration pathway. • Despite the several years after its introduction, osseointegration is yet unresolved.
This paper is aimed to present a biomaterials perspective in implant therapy that fosters improved bone response and long‐term biomechanical competence from surgical instrumentation to final ...prosthetic rehabilitation. Strategies to develop implant surface texturing will be presented and their role as an ad hoc treatment discussed in light of the interplay between surgical instrumentation and implant macrogeometric configuration. Evidence from human retrieved implants in service for several years and from in vivo studies will be used to show how the interplay between surgical instrumentation and implant macrogeometry design affect osseointegration healing pathways, and bone morphologic and long‐term mechanical properties. Also, the planning of implant‐supported prosthetic rehabilitations targeted at long‐term performance will be appraised from a standpoint where personal preferences (eg, cementing or screwing a prosthesis) can very often fail to deliver the best patient care. Lastly, the acknowledgement that every rehabilitation will have its strength degraded over time once in function will be highlighted, since the potential occurrence of even minor failures is rarely presented to patients prior to treatment.
Non-resorbable dental barrier membranes entail the risk of dehiscence due to their smooth and functionally inert surfaces. Non-thermal plasma (NTP) treatment has been shown to increase the ...hydrophilicity of a biomaterials and could thereby enhance cellular adhesion. This study aimed to elucidate the role of allyl alcohol NTP treatment of poly(tetrafluoroethylene) in its cellular adhesion. The materials (non-treated PTFE membranes (NTMem) and NTP-treated PTFE membranes (PTMem)) were subjected to characterization using scanning electron microscopy (SEM), contact angle measurements, X-ray photoelectron spectroscopy (XPS), and electron spectroscopy for chemical analysis (ESCA). Cells were seeded upon the different membranes, and cellular adhesion was analyzed qualitatively and quantitatively using fluorescence labeling and a hemocytometer, respectively. PTMem exhibited higher surface energies and the incorporation of reactive functional groups. NTP altered the surface topography and chemistry of PTFE membranes, as seen through SEM, XPS and ESCA, with partial defluorination and polymer chain breakage. Fluorescence labeling indicated significantly higher cell populations on PTMem relative to its untreated counterparts (NTMem). The results of this study support the potential applicability of allyl alcohol NTP treatment for polymeric biomaterials such as PTFE—to increase cellular adhesion for use as dental barrier membranes.
Injuries to the extremities often require resection of necrotic hard tissue. For large‐bone defects, autogenous bone grafting is ideal but, similar to all grafting procedures, is subject to ...limitations. Synthetic biomaterial‐driven engineered healing offers an alternative approach. This work focuses on three‐dimensional (3D) printing technology of solid‐free form fabrication, more specifically robocasting/direct write. The research hypothesizes that a bioactive calcium‐phosphate scaffold may successfully regenerate extensive bony defects in vivo and that newly regenerated bone will demonstrate mechanical properties similar to native bone as healing time elapses. Robocasting technology was used in designing and printing customizable scaffolds, composed of 100% beta tri‐calcium phosphate (β‐TCP), which were used to repair critical sized long‐bone defects. Following full thickness segmental defects (~11 mm × full thickness) in the radial diaphysis in New Zealand white rabbits, a custom 3D‐printed, 100% β‐TCP, scaffold was implanted or left empty (negative control) and allowed to heal over 8, 12, and 24 weeks. Scaffolds and bone, en bloc, were subjected to micro‐CT and histological analysis for quantification of bone, scaffold and soft tissue expressed as a function of volume percentage. Additionally, biomechanical testing at two different regions, (a) bone in the scaffold and (b) in native radial bone (control), was conducted to assess the newly regenerated bone for reduced elastic modulus (Er) and hardness (H) using nanoindentation. Histological analysis showed no signs of any adverse immune response while revealing progressive remodelling of bone within the scaffold along with gradual decrease in 3D‐scaffold volume over time. Micro‐CT images indicated directional bone ingrowth, with an increase in bone formation over time. Reduced elastic modulus (Er) data for the newly regenerated bone presented statistically homogenous values analogous to native bone at the three time points, whereas hardness (H) values were equivalent to the native radial bone only at 24 weeks. The negative control samples showed limited healing at 8 weeks. Custom engineered β‐TCP scaffolds are biocompatible, resorbable, and can directionally regenerate and remodel bone in a segmental long‐bone defect in a rabbit model. Custom designs and fabrication of β‐TCP scaffolds for use in other bone defect models warrant further investigation.
This study evaluated the effect of drilling speed on early bone healing in dog tibiae.
Thirty-six implants (4.0-mm diameter × 10-mm length) were placed in the proximal tibiae of 6 beagles with ...drilling speeds of 100, 500, and 1000 rpm, and insertion torque was recorded. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were evaluated.
Significant increase from 1 to 3 weeks was observed for all groups for BIC, whereas no significant differences between 1 and 3 weeks were detected for the 100- and 500-rpm groups for BAFO (P > .34 and P > .46, respectively). A significant difference from 1 to 3 weeks was observed for the 1000-rpm group (P < .03). The 100- and 500-rpm groups presented significantly higher BAFO than the 1000-rpm group at 1 week (P = .002).
Drilling speed is one of the decisive factors for early osseointegration, and overall, drilling at 1000 rpm seemed to yield the strongest biologic responses.
The aim of this study was to quantify the polymerization volumetric shrinkage of one regular and two low shrinkage bulk fill composites in class I cavities with or without an adhesive layer, using ...three-dimensional (3D) micro-computed tomography (μCT).
Class I cavity preparations (2.5 mm depth × 4 mm length × 4 mm wide) were standardized in 36 extracted human third molars, which were randomly divided in six groups (n = 6 each) as follows: Group VIT (regular composite without bonding agent); Group SDR (low shrinkage flowable composite without bonding agent); Group TET (low shrinkage composite without bonding agent); Group VIT/P (regular composite with bonding agent); Group SDR/X (low shrinkage flowable composite with bonding agent); TET/T (low shrinkage composite with bonding agent). Each tooth was scanned via µCT at cavity preparation, immediately after cavity filling, and after light-curing. Acquired μCT data were imported into Amira software for analysis and volume values evaluated between steps from cavity preparation until light-curing.
Both low shrinkage composites showed a significantly less volumetric shrinkage than VIT. The use of dental adhesive significantly decreased the average volumetric contraction similarly for the three composites, by about 20%.
Both low shrinkage composites showed less volumetric polymerization contraction than the regular composite. The use of dental adhesive decreased the total volumetric shrinkage for all evaluated composites.
The aim of this study was to evaluate fatigue resistance of dental fixtures with two different fixture-abutment connections by in vitro fatigue testing and in silico three-dimensional finite element ...analysis (3D FEA) using original computer-aided design (CAD) models.
Dental implant fixtures with external connection (EX) or internal connection (IN) abutments were fabricated from original CAD models using grade IV titanium and step-stress accelerated life testing was performed. Fatigue cycles and loads were assessed by Weibull analysis, and fatigue cracking was observed by micro-computed tomography and a stereomicroscope with high dynamic range software. Using the same CAD models, displacement vectors of implant components were also analyzed by 3D FEA. Angles of the fractured line occurring at fixture platforms in vitro and of displacement vectors corresponding to the fractured line in silico were compared by two-way ANOVA.
Fatigue testing showed significantly greater reliability for IN than EX (p<0.001). Fatigue crack initiation was primarily observed at implant fixture platforms. FEA demonstrated that crack lines of both implant systems in vitro were observed in the same direction as displacement vectors of the implant fixtures in silico.
In silico displacement vectors in the implant fixture are insightful for geometric development of dental implants to reduce complex interactions leading to fatigue failure.
Objectives
To evaluate the influence of implant‐abutment interface (IAI) placement depth on bone remodeling around implants with two different types of tapered internal IAI: screwed‐in (SI) and ...tapped‐in (TI) connections in dogs.
Materials and methods
Eight weeks post mandibular tooth extraction in six beagle dogs, two SI implants (OsseoSpeed™, Astra Tech, DENTSPLY) and two TI implants (Integra‐CP™, Bicon LLC) were placed in one side of the mandible. The four experimental groups were as follows: (i) SI‐placed equicrestally (SIC); (ii) TI‐placed equicrestally (TIC); (iii) SI‐placed 1.5 mm subcrestally (SIS); and (iv) TI‐placed 1.5 mm subcrestally (TIS). Healing abutments were connected 12 weeks after implant placement. Sixteen weeks later, the dogs were sacrificed and histomorphometric analysis was performed. Histometrical outcomes were evaluated using a nonparametric Brunner–Langer model.
Results
Mean distance from the IAI to first bone‐implant contact (IAI‐fBIC) was 0.88 mm (median: 0.77; SD: 0.54) for SIC group, 1.23 mm (median: 1.22; SD: 0.66) for TIC group, 0.41 mm (median: 0.31; SD: 0.36) for SIS group, and 0.41 mm (median: 0.26; SD: 0.45) for TIS group. Subcrestal groups showed lower IAI‐fBIC compared with equicrestal groups (P < 0.001). Connective tissue presented similar measurements regardless of the IAI placement depth and IAI type (P > 0.05), but the epithelium length and peri‐implant soft tissue length in subcrestal groups were significant larger than that in the equicrestal groups (P < 0.001 and P = 0.004, respectively).
Conclusion
Subcrestal implant placement with tapered internal IAI is beneficial for bone contact with the implant neck, and concurrently, it may not increase the soft tissue inflammation around IAI.
Purpose To investigate the influence of different materials and fixation methods on maximum principal stress (MPS) and displacement in reconstruction plates using in silico 3-dimensional finite ...element analysis (3D-FEA). Materials and Methods Computer-assisted designed (CAD) models of the mandible and teeth were constructed. Champy and AO/ASIF plates and fixation screws were designed with CAD software. 3D-FEA was performed by image-based CAE software. Maximum and minimum values of biomechanical stability, MPS, and displacement distribution were compared in Champy and AO/ASIF plates made from commercially pure titanium grade 2 (cp-Ti) and a titanium-and-molybdenum (14.47% wt) alloy (Ti-15Mo). Results For plates fixed on a model of a fractured left angle of the mandible, the maximum and minimum values of MPS in the cp-Ti–constructed Champy plate, upper AO/ASIF plate, and lower AO/ASIF plate were 19.5 and 20.3%, 15.2 and 25.3%, and 21.4 and 4.6% lower, respectively, than those for plates made from Ti-15Mo. In the same model, the maximum and minimum values of displacement in the cp-Ti–constructed Champy plate, upper AO/ASIF plate, and lower AO/ASIF plate were 1.6 and 3.8%, 3.1 and 2.7%, and 5.4 and 10.4% higher, respectively, than those for plates made from Ti-15Mo. Conclusions This in silico 3D-FEA shows that Ti-15Mo plates have greater load-bearing capability.
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