Dipyridamole enhances osteogenesis of three-dimensionally printed bioactive ceramic scaffolds in calvarial defects

PURPOSE

The objective of this study was to test the osteogenic capacity of dipyridamole-loaded, three-dimensionally printed, bioactive ceramic (3DPBC) scaffolds using a translational, skeletally mature, large-animal calvarial defect model.

MATERIALS AND METHODS

Custom 3DPBC scaffolds designed to present lattice-based porosity only towards the dural surface were either coated with collagen (control) or coated with collagen and immersed in a 100 μM concentration dipyridamole (DIPY) solution. Sheep (n = 5) were subjected to 2 ipsilateral trephine-induced (11-mm diameter) calvarial defects. Either a control or a DIPY scaffold was placed in each defect, and the surgery was repeated on the contralateral side 3 weeks later. Following sacrifice, defects were evaluated through microcomputed tomography and histologic analysis for bone, scaffold, and soft tissue quantification throughout the defect. Parametric and non-parametric methods were used to determine statistical significance based on data distribution.

RESULTS

No exuberant or ectopic bone formation was observed, and no histologic evidence of inflammation was noted within the defects. Osteogenesis was higher in DIPY-coated scaffolds compared to controls at 3 weeks (p = 0.013) and 6 weeks (p = 0.046) in vivo. When bone formation was evaluated as a function of defect radius, average bone formation was higher for DIPY relative to control scaffolds at both time points (significant at defect central regions at 3 weeks and at margins at 6 weeks, p = 0.046 and p = 0.031, respectively).

CONCLUSION

Dipyridamole significantly improves the calvarial bone regeneration capacity of 3DPBC scaffolds. The most significant difference in bone regeneration was observed centrally within the interface between the 3DPBC scaffold and the dura mater.

Effects of different etching methods and bonding procedures on shear bond strength of orthodontic metal brackets applied to different CAD/CAM ceramic materials

OBJECTIVE

To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different types of ceramic surfaces treated with different etching procedures and bonding agents.

MATERIALS AND METHODS

Monolithic CAD/CAM ceramic specimens (N = 120; n = 40 each group) of feldspathic ceramic Vita Mark II, resin nanoceramic Lava Ultimate, and hybrid ceramic Vita Enamic were fabricated (14 × 12 × 3 mm). Ceramic specimens were separated into four subgroups (n = 10) according to type of surface treatment and bonding onto the ceramic surface. Within each group, four subgroups were prepared by phosphoric acid, hydrofluoric acid, Transbond XT primer, and Clearfill Ceramic primer. Mandibular central incisor metal brackets were bonded with light-cure composite. The SBS data were analyzed using three-way analysis of variance (ANOVA) and Tukey HSD tests.

RESULTS

The highest SBS was found in the Vita Enamic group, which is a hybrid ceramic, etched with hydrofluoric acid and applied Transbond XT Adhesive primer (7.28 ± 2.49 MPa). The lowest SBS was found in the Lava Ultimate group, which is a resin nano-ceramic etched with hydrofluoric acid and applied Clearfill ceramic primer (2.20 ± 1.21 MPa).

CONCLUSIONS

CAD/CAM material types and bonding procedures affected bond strength ( P < .05), but the etching procedure did not ( P > .05). The use of Transbond XT as a primer bonding agent resulted in higher SBS.

Biomaterials for Craniofacial Bone Regeneration

Functional reconstruction of craniofacial defects is a major clinical challenge in craniofacial sciences. The advent of biomaterials is a potential alternative to standard autologous/allogenic grafting procedures to achieve clinically successful bone regeneration. This article discusses various classes of biomaterials currently used in craniofacial reconstruction. Also reviewed are clinical applications of biomaterials as delivery agents for sustained release of stem cells, genes, and growth factors. Recent promising advancements in 3D printing and bioprinting techniques that seem to be promising for future clinical treatments for craniofacial reconstruction are covered. Relevant topics in the bone regeneration literature exemplifying the potential of biomaterials to repair bone defects are highlighted.

Comparison of Hypersensitivity in Metal Ceramic Crowns cemented with Zinc Phosphate and Self-adhesive Resin: A Prospective Study

BACKGROUND

Luting agents used to fix artificial prostheses, such as fixed partial denture (FPD) to tooth are basically viscous in nature and show chemical reaction for fixation. Postcementation hypersensitivity is a frequent complaint of patients. The present study was conducted to compare postcementation hypersensitivity with zinc phosphate and self-adhesive resin in complete coverage crown.

MATERIALS AND METHODS

This study included 30 patients in which 60 porcelein fused to metal crowns was placed. Two metal crowns were placed in each patient in nonantagonis-tic contralateral quadrants. First crown was cemented with zinc phosphate cement, while the other was cemented with self-adhesive resin. Hypersensitivity was evaluated by visual analog scale (VAS) score and by clinical test. For clinical evaluation of sensitivity, hot and cold water was applied to the cervical margin of restoration for 5 seconds and response was recorded.

RESULTS

This study consisted of 30 patients in which 60 crowns were given. There was no statistical difference in VAS score of mastication in zinc phosphate cement recorded at baseline, 1 week, 4 weeks, 6 months, 1 year, and 2 years (p > 0.05). Cold response also did not show a significant difference at six time points. Warm response showed slight decrease in subsequent time points but was nonsignificant (p > 0.05). Similarly, with self-adhesive resin cement, VAS score during mastication, hot and cold response was statistically nonsignificant (p > 0.05).

CONCLUSION

Postcementation hypersensitivity is a frequent complaint that patient may experience. However, we found no statistically significant difference in both cements tested.

CLINICAL SIGNIFICANCE

Postcementation hypersensitivity is an unpleasant sensation experienced by patients. This may affect the success of any prosthesis. Thus, selection of luting agent for cementation plays an important role to eliminate this symptom.

Dental Ceramics for Restoration and Metal Veneering

A survey of the development of dental ceramics is presented to provide a better understanding of the rationale behind the development and clinical indications of each class of ceramic material. Knowledge of the composition, microstructure, and properties of a material is critical for selecting the right material for specific applications. The key to successful ceramic restorations rests on material selection, manufacturing technique, and restoration design, including the balancing of several factors such as residual stresses, tooth contact conditions, tooth size and shape, elastic modulus of the adhesives and tooth structure, and surface state.

Effect of Hydrofluoric Acid Concentration and Etching Time on Bond Strength to Lithium Disilicate Glass Ceramic

The aim of this study was to evaluate the influence of different concentrations of hydrofluoric acid (HF) associated with varied etching times on the microshear bond strength (μSBS) of a resin cement to a lithium disilicate glass ceramic. Two hundred seventy-five ceramic blocks (IPS e.max Press [EMX], Ivoclar Vivadent), measuring 8 mm × 3 mm thickness, were randomly distributed into five groups according to the HF concentrations (n=50): 1%, 2.5%, 5%, 7.5%, and 10%. Further random distribution into subgroups was performed according to the following etching times (n=10): 20, 40, 60, 120, and 20 + 20 seconds. After etching, all blocks were treated with a silane coupling agent followed by a thin layer of an unfilled resin. Three resin cement cylinders (∅=1 mm) were made on each EMX surface, which was then stored in deionized water at 37°C for 24 hours before testing. The μSBS was in a universal testing machine at a crosshead speed of 1 mm/min until failure. Data were submitted to two-way analysis of variance, and multiple comparisons were performed using the Tukey post hoc test (α=0.05). One representative EMX sample was etched according to the description of each subgroup and evaluated using scanning electron microscopy for surface characterization. The HF concentrations of 5%, 7.5%, and 10% provided significantly higher μSBS values than 1% and 2.5% (p<0.05), regardless of the etching times. For 1% and 2.5% HF, the etching times from 40 to 120 seconds increased the μSBS values compared with 20 seconds (p<0.05), but etching periods did not differ within the 5%, 7.5%, and 10% HF groups (p>0.05). The effect of re-etching was more evident for 1% and 2.5% HF (p<0.05). Different HF concentrations/etching times directly influenced the bond strength and surface morphology of EMX.

Effect of prior silane application on the bond strength of a universal adhesive to a lithium disilicate ceramic

STATEMENT OF PROBLEM

Universal adhesives combine silane and various monomers in a single bottle to make them more versatile. Their adhesive performance is unclear.

PURPOSE

The purpose of this in vitro study was to assess the effects of an additional silane application before using a universal adhesive on the adhesion between a disilicate glass ceramic and a composite resin by using a microshear bond strength test (μSBS) and fracture analysis immediately and after thermocycling.

MATERIAL AND METHODS

One hundred lithium disilicate glass ceramic disks were divided into 10 groups for bond strength testing according to the following 3 surface treatments: silane application (built-in universal adhesive or with additional application), adhesive (Adper Single Bond Plus [SB, 3M ESPE], Scotchbond Universal Adhesive [U, 3M ESPE], and mixed U with Dual Cure Activator [DCA, 3M ESPE]); or thermocycling (half of the specimens were thermocycled 10000 times). After surface treatment, 5 resin cylinders were bonded to each disk and submitted to a μSBS test. The failure mode was analyzed under a stereomicroscope and evaluated by scanning electron microscope and energy-dispersive x-ray spectroscopy. Data from the μSBS test were analyzed by 3-way ANOVA followed by the Tukey HSD post hoc test (α=.05).

RESULTS

An additional silane application resulted in a higher μSBS result for all adhesive groups (P<.05).

CONCLUSIONS

Ceramic surface treatment influenced the performance of adhesives, which may be improved with an additional silane application.

Spectrophotometric analysis of clinical factors related to the color of ceramic restorations: A pilot study

STATEMENT OF PROBLEM

Shade matching natural teeth with ceramic restorations is still an esthetic, clinical challenge.

PURPOSE

The purpose of this prospective clinical study was to evaluate the influence of color-related factors on the color variation of ceramic restorations based on spectrophotometric analysis.

MATERIAL AND METHODS

Color records were obtained from 11 participants who received 38 lithium disilicate restorations. CIELab color coordinates were measured with a spectrophotometer on the ceramic restoration, tooth (baseline), prepared tooth, and luted ceramics. Color variation (ΔE₀₀) was calculated for each variable (luting agent and restoration type, tooth substrate shade, ceramic thickness, and translucency parameters) measured at baseline on the prepared tooth and after cementation of the restorations. Confidence intervals (CI) for the means (95% CI) were calculated, and the ΔE₀₀ values and CIELab individual color coordinates were compared for each pair of variable by using the Student t test or Welch test (α=.05).

RESULTS

Greater color variation values were observed between measurements obtained on the prepared tooth and luted restoration. The lower ΔE₀₀ values were observed over darker tooth substrate measured at baseline and after luting (P=.007).

CONCLUSIONS

The 3 conditions evaluated presented clinically visible color differences, highlighting the importance of clinical evaluations on the visual color acceptability limits for restorations, which are usually defined in laboratory studies. The lithium disilicate ceramic showed lower masking ability over darker tooth substrate, whereas the coordinates L*, a*, and b* were cementation-dependent.

Outcomes of different bearings in total hip arthroplasty - implant survival, revision causes, and patient-reported outcome

Total hip arthroplasty (THA) is a common and successful treatment of patients suffering from severe osteoarthritis that significantly reduces pain and improves hip function and quality of life. Traditionally, the outcome of THA has been evaluated by orthopaedic surgeons and assessed in morbidity and mortality rates, and implant survival. As patients and surgeons may assess outcome after THA differently, patient-reported outcomes (PROMs) have gained much more interest and are today recognized as very important tools for evaluating the outcome and satisfaction after THA. One of the prognostic factors for the outcome of THA is the type of bearings. This PhD thesis focuses on the influence of different types of bearings on implant survival, revision causes, PROMs, and noises from THA. The aims of the thesis were: Study I: To examine the revision risk and to investigate the causes of revision of cementless ceramic-on-ceramic (CoC) THAs comparing them to those of "standard" metal-on-polyethylene (MoP) THAs. Study II: To compare the six-year revision risk for metal-on-metal (MoM) with that for MoP bearings in cementless stemmed THA, and further to study the revision risk for different designs of stemmed MoM THAs and the causes of revision. Study III: To examine the association between CoC, MoM, and MoP bearings and both generic and disease-specific PROMs, and furthermore to examine the incidence and types of noises from the three types of bearings and identify the effect of noises on PROM scores. In study I and III, we used data from the Danish Hip Arthroplasty Registry combined with data from the Civil Registration System and the Danish National Patient Registry. In study II, data from the Nordic Arthroplasty Register Association, containing data from hip arthroplasty registries in Denmark, Norway, Sweden, and Finland, was used. In study I, 11,096 patients operated from 2002 through 2009 with cementless THA were included. Of these, 16% had CoC THA and 84% had MoP THA. At 8.7-year follow-up, no difference in RR of revision for any cause was found for CoC compared to MoP THA. One cause of revision related only to CoC THA is ceramic fracture. Medical records were reviewed for patients who had revision surgery due to component failure, and six patients (0,34%) had been revised due to ceramic fracture. No other difference in prevalence of causes of revision was found when comparing CoC to MoP THA. Study II included 32,678 patients who were operated from 2002 through 2010 with cementless stemmed THA with either MoM bearings (11,567 patients, 35%) or MoP bearings (21,111 patients, 65%). At six-year follow-up, the RR of revision for any cause was significantly higher for MoM compared to MoP THA. When comparing different combinations of cup/stem with MoM to MoP bearings, there was an increased RR of revision for any cause for the ASR/Summit, ASR/Corail, and "other" combinations. There was a higher prevalence of revision due to aseptic loosening for MoM compared to MoP THA. In contrast, the prevalence of revision due to dislocation was lower for MoM THA. In study III, a set of questionnaires including HOOS, EQ-5D, UCLA activity score, and a questionnaire about noises from the THA was sendt to patients having THA with CoC, MoM, or MoP bearings. The response rate was 85% and among the 3,089 patients responding, 45% received CoC, 17% MoM, and 38% MoP THA. No differences in mean subscale scores were found for CoC and MoM compared to MoP THA, except for CoC THA that had a lower mean HOOS symptoms score than MoP THA. 27% of patients with CoC, 29% of patients with MoM, and 12% of patients with MoP bearings had experienced noises from the THA. For the three types of bearings, PROM scores from patients with noisy THA were significantly lower when compared to silent MoP THA, except for noisy CoC and MoM THA that had the same mean UCLA activity score as silent MoP THA.

Influence of 45S5 Bioactive Glass in A Standard Calcium Phosphate Collagen Bone Graft Substitute on the Posterolateral Fusion of Rabbit Spine

INTRODUCTION

Spinal fusion surgery is an effective but costly treatment for select spinal pathology. Historically iliac crest bone graft (ICBG) has remained the gold standard for achieving successful arthrodesis. Given well-established morbidity autograft harvest, multiple bone graft replacements, void fillers, and extenders have been developed. The objective of this study was to evaluate the in vivo efficacy and safety of two mineralized collagen bone void filler materials similar in composition. Both bone void fillers were composed of hydroxyapatite (HA), tricalcium phosphate (TCP) and bovine collagen. The first test article (Bi-Ostetic bioactive glass foam or "45S5") also contained 45S5 bioactive glass particles while the second test article (Formagraft or "FG") did not. 45S5 and FG were combined with bone marrow aspirate and iliac crest autograft and compared to ICBG in an established posterolateral spine fusion rabbit model.

MATERIALS AND METHODS

Sixty-nine mature New Zealand White rabbits were divided into 3 test cohorts: ICBG, 45S5, and FG. A Posterolateral fusion model previous validated was utilized to assess fusion efficacy. The test groups were evaluated for spine fusion rate, new bone formation, graft resorption and inflammatory response using radiographic, μCT, biomechanical and histological endpoints at 4, 8 and 12 weeks following implantation.

RESULTS

There were 4 clinical complications unrelated to the graft materials and were evenly split between groups (ICBG graft harvest complications; hind limb mobility, chronic pain) and were euthanized. These omissions did not affect the overall outcome of the study. Radiographic scoring of the fusion sites indicated a normal healing response in all test groups, with no adverse reactions and similar progressions of new bone formation observed over time. All groups demonstrated significantly less range of motion in both flexion/extension and lateral bending compared to normal not-fused controls, which supports fusion results observed in the other endpoints. Fusion occurred earlier in the 45S5 group: ICBG 0%, FG 0%, and 45S5 20% at 4 weeks; ICBG 43%, FG 38%, and 45S5 50% at 8 weeks; and ICBG 50%, FG 56%, and 45S5 56% at 12 weeks. Histopathology analysis of the fusion masses, from each test article and time point, indicated an expected normal response for resorbable calcium phosphate (HA/TCP) and collagen graft material. Mild inflammation with macrophage and multinucleated giant cell response to the graft material was evident in all test groups.

DISCUSSION

This study has confirmed the biocompatibility, safety, efficacy and bone healing characteristics of the HA-TCP collagen (with or without 45S5 bioactive glass) composites. The results show that the 3 test groups had equivalent long-term fusion performance and outcome at 12 weeks. However, the presence of 45S5 bioactive glass seemed to accelerate the fusion process as evidenced by the higher fusion rates at 4 and 8 weeks for the HA-TCP-collagen composite containing bioactive glass particles. The results also demonstrate that the HA-TCP-45S5 bioactive glass-collagen composite used as an extender closely mirrors the healing characteristics (i.e. amount and quality of bone) of the 100% autograft group.

Translucency and strength of high-translucency monolithic zirconium oxide materials

The purpose of this study was to evaluate the translucency and strength of highly translucent monolithic zirconia ceramic materials recently introduced to the market. Four monolithic zirconium oxide materials promoted as having high translucency (BruxZir Shaded 16, BruxZir HT, Lava Plus, and inCoris TZI C) were compared to a high-translucency, lithium disilicate monolithic glass-ceramic material (IPS e.max CAD HT). To evaluate translucency, the materials were sectioned into 0.5-, 1.0-, 1.5-, and 2.0-mm-thick specimens; all were sintered and polished. Translucency parameters were calculated with a spectrophotometer. To evaluate flexural strength and modulus, the ceramic materials were sectioned to create beams and fractured in a universal testing machine. The lithium disilicate had significantly greater translucency than the zirconia materials at each thickness. In general, the translucencies of the zirconia materials were similar at each thickness. However, at the manufacturers' recommended minimal thicknesses, 0.5-mm specimens of BruxZir Shaded 16, inCoris TZI C, and Lava Plus were more translucent than the 1.0-mm-thick specimens of IPS e.max CAD HT. Translucency significantly decreased for each material at each increase in thickness. The flexural strengths of the zirconia materials were similar to each other and significantly greater than that of IPS e.max CAD HT. Flexural moduli were more variable. Of the zirconia materials, BruxZir Shaded 16 had an overall better combination of translucency, strength, and modulus.

Key Parameters of Hybrid Materials for CAD/CAM-Based Restorative Dentistry

Hybrid materials are a recent addition to the dental armamentarium for computer-assisted design/ computer-assisted manufacturing (CAD/CAM)-based restorative dentistry. They are intended to provide dentists with the capability of restoring single teeth in one appointment with a material that emulates the structure and physical properties of natural teeth. This article aims to provide an overview of currently available hybrid materials and offer the reader further understanding of their key clinical parameters and possible limitations.

How to Bond Zirconia: The APC Concept

Zirconia has become one of the most popular materials in dentistry. New high-translucent zirconia ceramics have favorable optical properties and can be applied as monolithic full-contour restorations in various clinical indications for posterior and anterior teeth. However, having reliable cementation protocols is fundamental for clinical success of indirect ceramic dental restorations, including those made from zirconia materials. Resin bonding supports ceramic restorations and is necessary for onlays, laminate veneers, and resinbonded fixed dental prostheses. The APC zirconia-bonding concept is based on decades of research on how to achieve high and long-term durable bond strengths to high-strength ceramics. It includes three practical steps: (A) airparticle abrasion, (P) zirconia primer, and (C) adhesive composite resin. This article discusses the history and development of high-translucent zirconia and explains the necessity for proper cementation. The rationale and science behind a simplified zirconia-bonding concept is explained and illustrated with a clinical case presentation.

Adhesive Bonding to Hybrid Materials: An Overview of Materials and Recommendations

Recently, hybrid materials have been introduced to the dental market. Together with computer-assisted design/computer-assisted manufacturing (CAD/CAM) composite resins, they form a new class of dental CAD/CAM materials that combine the positive effects of ceramics and composites. As bonding is essential for their clinical longevity, it is crucial to have a good understanding of their material properties and cementation protocols. This review offers clinicians an overview of available hybrid materials and recommendations for their respective adhesive placements.

Functionalized Antimicrobial Composite Thin Films Printing for Stainless Steel Implant Coatings

In this work we try to address the large interest existing nowadays in the better understanding of the interaction between microbial biofilms and metallic implants. Our aimed was to identify a new preventive strategy to control drug release, biofilm formation and contamination of medical devices with microbes. The transfer and printing of novel bioactive glass-polymer-antibiotic composites by Matrix-Assisted Pulsed Laser Evaporation into uniform thin films onto 316 L stainless steel substrates of the type used in implants are reported. The targets were prepared by freezing in liquid nitrogen mixtures containing polymer and antibiotic reinforced with bioglass powder. The cryogenic targets were submitted to multipulse evaporation by irradiation with an UV KrF* (λ = 248 nm, τ_FWHM ≤ 25 ns) excimer laser source. The prepared structures were analyzed by infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and profilometry, before and after immersion in physiological fluids. The bioactivity and the release of the antibiotic have been evaluated. We showed that the incorporated antibiotic underwent a gradually dissolution in physiological fluids thus supporting a high local treatment efficiency. Electrochemical measurements including linear sweep voltammetry and impedance spectroscopy studies were carried out to investigate the corrosion resistance of the coatings in physiological environments. The in vitro biocompatibility assay using the MG63 mammalian cell line revealed that the obtained nanostructured composite films are non-cytotoxic. The antimicrobial effect of the coatings was tested against Staphylococcus aureus and Escherichia coli strains, usually present in implant-associated infections. An anti-biofilm activity was evidenced, stronger against E. coli than the S. aureus strain. The results proved that the applied method allows for the fabrication of implantable biomaterials which shield metal ion release and possess increased biocompatibility and resistance to microbial colonization and biofilm growth.

Bioactive Materials in Endodontics: An Evolving Component of Clinical Dentistry

Achieving biocompatibility in a material requires an interdisciplinary approach that involves a sound knowledge of materials science, bioengineering, and biotechnology. The host microbial-material response is also critical. Endodontic treatment is a delicate procedure that must be planned and executed properly. Despite major advances in endodontic therapy in recent decades, clinicians are confronted with a complex root canal anatomy and a wide selection of endodontic filling materials that, in turn, may not be well tolerated by the periapical tissues and may evoke an immune reaction. This article discusses published reports of various bioactive materials that are used in endodontic therapy, including calcium hydroxide, mineral trioxide aggregate, a bioactive dentin substrate, calcium phosphate ceramics, and calcium phosphate cements.

Effect of a new salivary-contaminant removal method on bond strength

The study evaluated the effect of salivary-contaminant removal methods on the bond strength of resin cement to hydrofluoric acid-etched ceramic. Treatment with a new cleaning paste resulted in bond strengths not significantly different from those obtained in phosphoric acid-treated, hydrofluoric acid-treated, and uncontaminated control groups; thus the paste may be considered an alternative to phosphoric acid or hydrofluoric acid for removal of salivary contaminants.

Evaluation of the marginal fit of single-unit, complete-coverage ceramic restorations fabricated after digital and conventional impressions: A systematic review and meta-analysis

STATEMENT OF PROBLEM

In existing published reports, some studies indicate the superiority of digital impression systems in terms of the marginal accuracy of ceramic restorations, whereas others show that the conventional method provides restorations with better marginal fit than fully digital fabrication. Which impression method provides the lowest mean values for marginal adaptation is inconclusive. The findings from those studies cannot be easily generalized, and in vivo studies that could provide valid and meaningful information are limited in the existing publications.

PURPOSE

The purpose of this study was to systematically review existing reports and evaluate the marginal fit of ceramic single-tooth restorations after either digital or conventional impression methods by combining the available evidence in a meta-analysis.

MATERIAL AND METHODS

The search strategy for this systematic review of the publications was based on a Population, Intervention, Comparison, and Outcome (PICO) framework. For the statistical analysis, the mean marginal fit values of each study were extracted and categorized according to the impression method to calculate the mean value, together with the 95% confidence intervals (CI) of each category, and to evaluate the impact of each impression method on the marginal adaptation by comparing digital and conventional techniques separately for in vitro and in vivo studies.

RESULTS

Twelve studies were included in the meta-analysis from the 63 identified records after database searching. For the in vitro studies, where ceramic restorations were fabricated after conventional impressions, the mean value of the marginal fit was 58.9 μm (95% CI: 41.1-76.7 μm), whereas after digital impressions, it was 63.3 μm (95% CI: 50.5-76.0 μm). In the in vivo studies, the mean marginal discrepancy of the restorations after digital impressions was 56.1 μm (95% CI: 46.3-65.8 μm), whereas after conventional impressions, it was 79.2 μm (95% CI: 59.6-98.9 μm)

CONCLUSION

No significant difference was observed regarding the marginal discrepancy of single-unit ceramic restorations fabricated after digital or conventional impressions.

Functionalization of Calcium Sulfate/Bioglass Scaffolds with Zinc Oxide Whisker

There are urgent demands for satisfactory antibacterial activity and mechanical properties of bone scaffolds. In this study, zinc oxide whisker (ZnOw) was introduced into calcium sulfate/bioglass scaffolds. Antimicrobial behavior was analyzed using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results showed that the scaffolds presented a strong antibacterial activity after introducing ZnOw, due to the antibacterial factors released from the degradation of ZnO. Moreover, ZnOw was also found to have a distinct reinforcing effect on mechanical properties. This was ascribed to whisker pull-out, crack bridging, crack deflection, crack branching and other toughening mechanisms. In addition, the cell culture experiments showed that the scaffolds with ZnOw had a good biocompatibility.

Experimental maxillary sinus augmentation using a highly bioactive glass ceramic

Physicochemical characteristics of a biomaterial directly influence its biological behavior and fate. However, anatomical and physiological particularities of the recipient site also seem to contribute with this process. The present study aimed to evaluate bone healing of maxillary sinus augmentation using a novel bioactive glass ceramic in comparison with a bovine hydroxyapatite. Bilateral sinus augmentation was performed in adult male rabbits, divided into 4 groups according to the biomaterial used: BO-particulate bovine HA Bio-Oss(®) (BO), BO+G-particulate bovine HA + particulate autogenous bone graft (G), BS-particulate glass ceramic (180-212 μm) Biosilicate(®) (BS), and BS+G-particulate glass ceramic + G. After 45 and 90 days, animals were euthanized and the specimens prepared to be analyzed under light and polarized microscopy, immunohistochemistry, scanning electron microscopy (SEM), and micro-computed tomography (μCT). Results revealed different degradation pattern between both biomaterials, despite the association with bone graft. BS caused a more intense chronic inflammation with foreign body reaction, which led to a difficulty in bone formation. Besides this evidence, SEM and μCT confirmed direct contact between newly formed bone and biomaterial, along with osteopontin and osteocalcin immunolabeling. Bone matrix mineralization was late in BS group but became similar to BO at day 90. These results clearly indicate that further studies about Biosilicate(®) are necessary to identify the factors that resulted in an unfavorable healing response when used in maxillary sinus augmentation.

[Bioactive glass 45S5-silk fibroin membrane supports proliferation and differentiation of human dental pulp stem cells]

OBJECTIVE

To investigate the effect of bioactivity glass 45S5- silk fibroin(BG45S5- SF) membrane on growth, proliferation and differentiation of human dental pulp stem cells(hDPSC), and to provide new ideas and method for the regeneration of pulp-dentine complex.

METHODS

hDPSC seed on pure silk fibroin membrane (protein membrane group) and BG45S5-SF membrane with different concentrations(1 000, 5 000 mg/L, composite membrane group A and B, respectively) were prepared, and the materials were incubated in cell culture fluid for 24 h. No material membrane orifice plate was used as blank control group. Contact angle meter was used to measure surface contact angle of protein membrane and composite membrane group(each group had three repeated holes). Cell proliferation was assessed by cell counting kit- 8 on the 4, 7, 14, and 21 days. The state of adhesion and growth of hDPSC on the materials surface was evaluated by scanning electron microscopy and cytoskeleton staining; and alkaline phosphatase (ALP) activity was measured to evaluate the cell differentiation potential. The expression of odontoblastic differentiation-related genes was measured by real-time PCR.

RESULTS

Surface contact angle of the protein membrane group and composite membrane group A and group B were 89.51° ± 0.12°, 70.32° ± 0.07° and 71.31° ± 0.09° respectively. hDPSC adhered well on each materials surface on the 7, 14, 21 days, ALP activity and differentiation genes of composite membrane group A and B rised more significantly than the blank control group and protein membrane group did (P<0.05). Dentin matrix protein1(DMP- 1), dentin sialoprotein(DSP), ALP, osteocalcin(OC) mRNA expression reached peak on the 14 days in group A, and in group B on the 21 days. Bone sialoprotein(BSP) mRNA expression in both group A and B reached peak on the 21 days.

CONCLUSIONS

BG45S5- SF membrane is able to support the proliferation and showed the potential of odontoblastic differentiation for hDPSC. This finding suggests that BG45S5-SF membrane was a kind of tissue engineering film material with the regeneration potential for pulp-dentine complex.

WITHDRAWN: Ceramic inlays for restoring posterior teeth

Withdrawn as the review has been superseded by a more up to date version of a Cochrane review of the same title.

The editorial group responsible for this previously published document have withdrawn it from publication.

Advanced Chemoembolization by Anti-angiogenic Calcium-Phosphate Ceramic Microspheres Targeting the Vascular Heterogeneity of Cancer Xenografts

The purpose of the present study was to develop an advanced method of anti-angiogenic chemoembolization to target morphological vascular heterogeneity in tumors and further the therapeutic efficacy of cancer treatment. This new chemoembolization approach was designed using resorbable calcium-phosphate ceramic microspheres (CPMs), in a mixture of three different sizes, which were loaded with an anti-angiogenic agent to target the tumor vasculature in highly angiogenic solid tumors in humans in vivo. The human uterine carcinosarcoma cell line, FU-MMT-3, was used in this study because the tumor is highly aggressive and exhibits a poor response to radiotherapy and chemotherapeutic agents that are in current use. CPMs loaded with TNP-470, an anti-angiogenic agent, were injected into FU-MMT-3 xenografts in nude mice three times per week for 8 weeks. The treatment with TNP-470-loaded CPMs of three different diameters achieved a greater suppression of tumor growth in comparison to treatment with single-size TNP-470-loaded CPMs alone, and the control. Severe loss of body weight was not observed in any mice treated with any size of TNP-470-loaded CPMs. These results suggest that treatment with a mixture of differently-sized anti-angiogenic CPMs might be more effective than treatment with CPMs of a single size. This advanced chemoembolization method, which incorporated an anti-angiogenic agent to target the morphological vascular heterogeneity of tumors may contribute to effective treatment of locally advanced or recurrent solid tumors.

Hard tissue regeneration using bone substitutes: an update on innovations in materials

Bone is a unique organ composed of mineralized hard tissue, unlike any other body part. The unique manner in which bone can constantly undergo self-remodeling has created interesting clinical approaches to the healing of damaged bone. Healing of large bone defects is achieved using implant materials that gradually integrate with the body after healing is completed. Such strategies require a multidisciplinary approach by material scientists, biological scientists, and clinicians. Development of materials for bone healing and exploration of the interactions thereof with the body are active research areas. In this review, we explore ongoing developments in the creation of materials for regenerating hard tissues.

Angiogenesis and bone regeneration of porous nano-hydroxyapatite/coralline blocks coated with rhVEGF165 in critical-size alveolar bone defects in vivo

To improve the regenerative performance of nano-hydroxyapatite/coralline (nHA/coral) block grafting in a canine mandibular critical-size defect model, nHA/coral blocks were coated with recombinant human vascular endothelial growth factor(165) (rhVEGF) via physical adsorption (3 μg rhVEGF165 per nHA/coral block). After the nHA/coral blocks and VEGF/nHA/coral blocks were randomly implanted into the mandibular box-shaped defects in a split-mouth design, the healing process was evaluated by histological observation and histomorphometric and immunohistological analyses. The histological evaluations revealed the ingrowth of newly formed blood vessels and bone at the periphery and cores of the blocks in both groups at both 3 and 8 weeks postsurgery, respectively. In the histomorphometric analysis, the VEGF/nHA/coral group exhibited a larger quantity of new bone formation at 3 and 8 weeks postsurgery. The percentages of newly formed bone within the entire blocks in the VEGF/nHA/coral group were 27.3% ± 8.1% and 39.3% ± 12.8% at 3 weeks and 8 weeks, respectively, and these values were slightly greater than those of the nHA/coral group (21.7% ± 3.0% and 32.6% ± 10.3%, respectively), but the differences were not significant (P>0.05). The immunohistological evaluations revealed that the neovascular density in the VEGF/nHA/coral group (146 ± 32.9 vessel/mm(2)) was much greater than that in the nHA/coral group (105 ± 51.8 vessel/mm(2)) at the 3-week time point (P<0.05), but no significant difference was observed at the 8-week time point (341 ± 86.1 and 269 ± 50.7 vessel/mm(2), respectively, P>0.05). The present study indicated that nHA/coral blocks might be optimal scaffolds for block grafting in critical-size mandibular defects and that additional VEGF coating via physical adsorption can promote angiogenesis in the early stage of bone healing, which suggests that prevascularized nHA/coral blocks have significant potential as a bioactive material for bone regeneration in large-scale alveolar defects.