Overview of biologics

A variety of orthobiologic materials are available or under development to enhance the repair of bone fractures. These materials vary widely in their composition, mechanism of action, and clinical results. This article provides a brief review of the currently available bone grafting materials, which include autografts, allografts, conductive substrates, demineralized bone matrix, platelet gels, recombinant bone morphogenic proteins, and bone marrow aspirate injections.

Bone substitutes: an update

Autograft is considered ideal for grafting procedures, providing osteoinductive growth factors, osteogenic cells, and an osteoconductive scaffold. Limitations, however, exist regarding donor site morbidity and graft availability. Allograft on the other hand, posses the risk of disease transmission. Synthetic graft substitutes lack osteoinductive or osteogenic properties. Composite grafts combine scaffolding properties with biological elements to stimulate cell proliferation and differentiation and eventually osteogenesis. We present here an overview of bone grafts and graft substitutes available for clinical applications.

Transplant of mesenchymal stem cells and hydroxyapatite ceramics to treat severe osteochondral damage after septic arthritis of the knee

We describe a 21-year-old man with a large osteochondral defect of the knee after septic arthritis, successfully treated by transplant of mesenchymal stem cells (MSC) from bone marrow and a new type of interconnected porous hydroxyapatite ceramic (IP-CHA). We confirmed successful cartilage-like tissue regeneration by a second arthroscopy. Biopsy of the repaired tissue revealed cartilage-like regeneration and bone formation. We were able to regenerate new bone and cartilage-like tissue in a one-stage operation, without sacrificing autologous bone or other tissue. This cultured MSC and IP-CHA hybrid material transplant represents a novel treatment for a severe osteochondral defect after septic arthritis.

Techniques used to fabricate all-ceramic restorations in the dental practice

Porcelain is an increasingly popular material to use for restorations. This article will discuss the 3 main ways to fabricate porcelain restorations. The first method involves waxing up the restoration to the proper form and casting it in molten porcelain similar to the lost wax technique for gold. The second technique requires the use of porcelain in a powder form to be stacked on top of a refractory die or a platinum foil and then fired in the oven. The third main technique is the use of a CAD/CAM system to mill the porcelain restoration from a solid block of porcelain. All 3 techniques are valid and the clinician should have a thorough understanding of which techniques are appropriate in various clinical situations.

The in vivo behaviour of a sol–gel glass and a glass-ceramic during critical diaphyseal bone defects healing

The in vivo evaluation, in New Zealand rabbits, of a sol-gel glass 70% CaO-30% SiO2 (in mol%) and a glass-ceramic obtained from thermal treatment of the glass, both bioactive in Kokubo's simulated body fluid (SBF), is presented. Femoral bone diaphyseal critical defects were filled with: (i) sol-gel glass cylinders, (ii) glass-ceramic cylinders, or (iii) no material (control group). Osteosynthesis was done by means of anterior screwed plates with an associate intramedullar Kirschner wire. Each group included 10 mature rabbits, 9 months old. Follow-up was 6 months. After sacrifice, macroscopic study showed healing of bone defects, with bone coating over the cylinders, but without evidence of satisfactory repair in control group. Radiographic study showed good implant stability and periosteal growth and bone remodelling around and over the filled bone defect. The morphometric study showed minimum evidences of degradation or resorption in glass-ceramic cylinders, maintaining its original shape, but sol-gel glass cylinders showed abundant fragmentation and surface resorption. An intimate union of the new-formed bone to both materials was observed. Mechanical study showed the higher results in the glass-ceramic group, whereas sol-gel glass and control group showed no differences. The minimum degradation of glass-ceramic cylinders suggests their application in critical bone defects locations of transmission forces or load bearing. The performance of sol-gel glass cylinders suggests their usefulness in locations where a quick resorption should be preferable, considering the possibility of serving as drug or cells vehicle for both of them.

In vitro study of dentin hypersensitivity treated by Nd:YAP laser and bioglass

OBJECTIVES

An ideal material has yet to be discovered that can completely treat dentin hypersensitivity. However, if a highly biocompatible material such as bioglass, could be melted by laser irradiation to achieve better sealing depth for dentinal tubules, it may subsequently bond to dentin structures under a physiological environment and offer a prolonged therapeutic effect.

METHODS

The authors used four types of energy parameters to melt the composition-modified bioglass. These four types were 30 Hz, 330 mJ/pulse (G+ mode), 30 Hz, 160 mJ/pulse (G- mode), 10 Hz, 400 mJ/pulse (D+ mode), and 10 Hz, 200 mJ/pulse (D- mode). The temperature elevation, occlusive depth of bioglass, and phase changes in the bioglass after laser irradiation were evaluated by means of scanning electron microscope (SEM), thermometer, and X-ray diffractometer (XRD).

RESULTS

The occlusive depths of 2 and 10 microm in the dentinal tubules were achieved when the bioglass underwent 30 Hz, 160 mJ/pulse (G- mode) and 30 Hz, 330 mJ/pulse (G+ mode) of laser treatments, respectively. The bioglass experienced a temperature increase of less than 600 degrees C, and no phase transformation was observed after Nd:YAP laser irradiation.

SIGNIFICANCE

The melting point of a composition-modified bioglass could be reduced and its use plus Nd:YAP laser have the potential in clinical use to treat dentin hypersensitivity.

A comparative study of two CEREC software systems in evaluating manufacturing time and accuracy of restorations

This study compared the manufacturing times and the accuracy of proximal and occlusal contacts on restorations produced by two different versions of CEREC 3 software, COS and 3D. Fourteen casts containing pre-existing inlay and onlay preparations of premolars and molars were mounted on articulators. A bite registration was made in maximum intercuspation. Optical impressions of the preparation and the bite registration were made. The Wilcoxon signed rank test was applied for a statistical analysis of time expended in the different design and manufacturing steps of both software versions. The chi-square test was applied for the statistical analysis of proximal and occlusal contacts.

Bioresorbable glass fibres facilitate peripheral nerve regeneration

This is a proof of principle report showing that fibres of Bioglass 45S5 can form a biocompatible scaffold to guide regrowing peripheral axons in vivo. We demonstrate that cultured rat Schwann cells and fibroblasts grow on Bioglass fibres in vitro using SEM and immunohistochemistry, and provide qualitative and quantitative evidence of axonal regeneration through a Silastic conduit filled with Bioglass fibres in vivo (across a 0.5 cm interstump gap in the sciatic nerves of adult rats). Axonal regrowth at 4 weeks is indistinguishable from that which occurs across an autograft. Bioglass fibres are not only biocompatible and bioresorbable, which are absolute requirements of successful devices, but are also amenable to bioengineering, and therefore have the potential for use in the most challenging clinical cases, where there are long inter-stump gaps to be bridged.

Use of osteopromotive growth factors, demineralized bone matrix, and ceramics to enhance spinal fusion

Recently developed materials that can enhance fusion rates for posterolateral lumbar arthrodesis may be used alone or in combination with autogenous bone grafts. Novel osteopromotive growth factor preparations are currently under scrutiny; these include autogenous growth factor concentrate, bovine bone-derived osteoinductive protein, and recombinant human MP52. Demineralized bone matrix products may enhance or extend grafts. However, few studies, especially prospective randomized clinical trials, have assessed their efficacy, so it is difficult to compare formulations. Ceramics have been evaluated in animal studies and human clinical trials for a variety of applications in spinal surgery. These materials function best as bone graft extenders or as bioactive osteoinductive material carriers in posterolateral lumbar fusions. They have the advantage of variable porosity, low cost, and ease of manufacture. Hydroxyapatite/tricalcium phosphate ceramics have been shown to perform as well as autogenous bone grafts but with fewer complications.

Achieving quality esthetic dentistry and integrated comprehensive care with new generation techniques and materials

BACKGROUND

Prosthodontics is the dental specialty responsible for diagnosis, rehabilitation and maintenance of patients with complex clinical conditions involving missing or deficient teeth and/or craniofacial tissues. The essence of the specialty is expert treatment planning.

OVERVIEW/LITERATURE REVIEWED

In recent years, new approaches and technology have been introduced as a result of research performed in universities and by industry. The field of prosthodontics continues to evolve owing to a better understanding of the biology of the oral cavity and the introduction of new techniques and improved biomaterials. Improvements in periodontal and oral surgical techniques, implant procedures and materials, esthetic restorative materials, and jaw tracking recorders and articulators have led to enhanced functional and esthetic oral and maxillofacial prostheses.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The complexities of today's technical and clinical procedures and the higher expectations for more esthetically pleasing dentistry by the general patient population have placed a premium on teamwork involving general dentists, specialists and dental technicians.

Iliac crest reconstruction with a bioactive ceramic spacer

This study aimed to investigate the long-term clinical results of the apatite wollastonite-containing glass ceramic (AWGC) iliac spacer and to discuss its efficacy in reconstruction of the bone graft donor site at the iliac crest. Thirty-one patients were studied for more than 10 years. All patients underwent anterior spinal fusion using autogenous tricortical iliac bone graft. After harvest of tricortical iliac bone graft, an AWGC iliac spacer ranging from 15 mm to 70 mm in length was press-fitted into the gap. Long-term clinical results were obtained from radiological and blood examinations. Thirty patients (97%) were satisfied with the spacer. There was new bone formation around the spacer on the radiograph. There was no abnormal silicon concentration in blood examinations. AWGC iliac spacer appears to be useful in the reconstruction of harvested iliac crest. New bone formation occurs, reducing the defect size.

[Application of glass-crystalline granules of biosit-elcor for reducing the size of trepanation cavity in middle ear surgery]

The authors describe experience in application of bioglass preparations (biosit-elcor) for partial obliteration of mastoid cavities in open operations on the middle ear in 17 patients. Long-term results were studied with otomicroscopy and computed tomography of the temporal bones. A good morphological result of the operation (complete epithelization of the wound surface, no discharge from the ear) was achieved in all the patients. Computed tomography showed step-by-step osteointegration of the implant.

Healing of human intrabony defects following regenerative periodontal therapy with an enamel matrix protein derivative alone or combined with a bioactive glass. A controlled clinical study

AIM

The purpose of the present study was to compare clinically the treatment of deep intrabony defects with a combination of an enamel matrix protein derivative (EMD) and a bioactive glass (BG) to EMD alone.

METHODS

Thirty patients (16 females and 14 males) suffering from advanced marginal periodontitis were included in this prospective, controlled parallel design multicenter study. In each of the patients, one intrabony defect was randomly treated with either EMD+BG (test) or with EMD alone (control). Clinical measurements were recorded at baseline and at 1 year following therapy.

RESULTS

No differences in any of the investigated parameters were observed at baseline between the two groups. Healing was uneventful in all patients. At 1 year after therapy, the test group showed a reduction in mean probing depth (PD) from 8.5+/-1.1 to 4.4+/-1.2 mm (p<0.001) and a change in mean clinical attachment level (CAL) from 10.4+/-1.5 to 7.1+/-1.5 mm (p<0.0001). In the control group, the mean PD was reduced from 8.5+/-1.5 to 4.0+/-1.6 mm (p<0.001) and the mean CAL changed from 10.2+/-2.1 to 6.3+/-2.2 mm (p<0.01). In the test group, 12 sites (80%) gained at least 3 mm or more of CAL, whereas in the control group a CAL gain of 3 mm or more was measured at 13 sites (87%). No statistically significant differences in terms of PD reduction and CAL gain were found between the test and the control treatment.

CONCLUSIONS

Within the limits of the present study it can be concluded that: (i) at 1 year after surgery, both therapies resulted in significant PD reductions and CAL gains, and (ii) the combination of EMD+BG does not seem to additionally improve the clinical results.

Ceramics in total hip replacement

Alumina-on-alumina total hip arthroplasty has been used for 32 years in Europe. The theoretical advantages of this combination are represented by its remarkable sliding characteristics, its very low wear debris generation, and its improved fracture toughness. These advantages are achieved if the material is processed properly with high density, high purity and small grains. We summarize the results obtained with the alumina-on-alumina combination concerning in vitro and in vivo wear behavior with special emphasis on wear debris characterization and quantification and histologic tissue examinations. Alumina-on-alumina seems to be one of the best choices in young and active patients provided that sound socket fixation is maintained in the long term.

The marginal quality of luted ceramic inserts in bovine teeth and ceramic inlays in extracted molars after occlusal loading

PURPOSE

To compare the marginal adaptation of adhesively luted ceramic inserts in standardized cylindrical cavities of bovine dentin and enamel with the marginal adaptation of adhesively luted ceramic inlays in extracted molars after mechanical loading, and to calculate the minimum sample size required to differentiate between material groups based on the findings of this investigation.

MATERIALS AND METHODS

Ceramic inserts of similar dimension were luted in standardized cylindrical cavities of bovine dentin and enamel (n = 6, O = 4 mm) with seven different adhesive/resin cement systems (Syntac/Variolink, Prime & Bond NT/Variolink, Excite DSC/Variolink, AdheSE/Variolink, Excite DSC/Multilink, Multilink Primer/ Multilink, RelyX Unicem). The same materials were used to lute ceramic inlays (Empress II) in three-surface cavities of extracted human molars (n = 6 per group). All specimens were submitted to 2000 cycles of thermocycling. In addition, restored teeth were submitted to cyclic loading (640,000 cycles, 50 N) in a chewing simulator. Replicas after stressing were analyzed with SEM, and the percentage of continuous margin of the inserts and the inlays was calculated, differentiating the proximal part of the inlay into cervical dentin/enamel and axio-proximal enamel. The mean percentage values per material group of the insert and inlay groups were ranked using relative ranks. Sample size estimation was done for pooled standard deviations comparing between two and seven materials and assuming 20% or 10% of the mean of continuous margin to be statistically significant.

RESULTS

The Spearman correlation coefficient between the variables "insert dentin" and "inlay cervical dentin" was 0.71 (p = 0.07), between "insert enamel" and "inlay axio-proximal enamel" 0.07 (p = 0.9). The variability of the test results was large for both the insert and inlay variables, especially at the resin-dentin interface. No statistically significant difference between the materials could be found for the insert method when ANOVA and Bonferroni post-hoc tests were applied (p > 0.05), while the inlays luted with Prime & Bond NT/Variolink showed significantly less continuous margin at the cervical dentin than all other groups with the exception of RelyX Unicem. At least 16 (63) inlays and 14 (57) inserts had to be used per group for differences of 20% (10%) of the mean of continuous margin.

CONCLUSION

To evaluate luting agents with regard to their ability to reduce marginal discrepancies, the inlay model is inadequate due to high sample numbers which make the test time-consuming and expensive; furthermore its clinical relevance is uncertain. Alternatively, the insert method may be a suitable screening method for dentinal margins, although its clinical relevance is also unknown.

[Ceramic-ceramic articulation in uncemented total hip arthroplasty]

The main problem in total hip arthroplasty (THA) surgery is aseptic loosening of prosthesis components. In most cases the phagocytes reaction against the wear particle during the hip movement is responsible for aseptic prosthesis loosening. To prevent this reaction different hip articulation are invented to reduce this reaction. One of these solutions is ceramic-ceramic hip prosthesis articulation. The aim of this study was to evaluate the long-term results in patients who were treated because of coxarthrosis by means of ceramic-ceramic hip prosthesis. We analyzed 258 primary THA (222 patients, 116 women and 106 men) who were treated because of advanced coxarthrosis by Mittelmeier type hip endoprosthesis (ceramic-ceramic articulation). The mean age of patients at the surgery was 45.6 years and a mean follow-up 10.2 years. In most of our cases the idiopathic, traumatic and dysplastic coxarthrosis was noted. For clinical evaluation the classification system proposed by Merle d'Aubigne and Postel with Charnley modification was used. For radiological evaluation of the steam implantation the classification system proposed by De Lee and Charnley was used and for the cup implantation the system by Gruen and Moreland. In 87 patients (33.7%) the final results was graded as very good, in 96 (37.2%) as good, in 47 (18.2%) as satisfactory and in 28 patients (10.9%) the final results was poor. In analyzed group in 13 patients (5.0%) the revision surgery was necessary.

CONCLUSIONS

The long-term results of THA with the use of Mittelmeier type of hip prosthesis presented a very low percentage of aseptic loosening. This type of prosthesis gives very high patients satisfaction.

Biomaterials in total joint replacement

The current state of materials systems used in total hip replacement is presented in this paper. An overview of the various material systems used in total hip replacement reported in literature is presented in this paper. Metals, polymers, ceramics and composites are used in the design of the different components of hip replacement implants. The merits and demerits of these material systems are evaluated in the context of mechanical properties most suitable for total joint replacement such as a hip implant. Current research on advanced polymeric nanocomposites and biomimetic composites as novel materials systems for bone replacement is also discussed. This paper examines the current research in the materials science and the critical issues and challenges in these materials systems that require further research before application in biomedical industry.

Dentinal crack incidence following ultrasonic vibration to intra-radicular posts

OBJECTIVE

To determine the incidence of dentinal cracks on the root-face of extracted teeth containing intra-radicular posts subjected to prolonged ultrasonic vibration. Design & Setting This in-vitro experiment, conducted at the University of Manchester, UK, used post type and ultrasonic vibration as dependent variables.

MATERIALS AND METHODS

Forty canine teeth were decoronated and root-filled with gutta-percha and sealer. A parallel shaped post-space of 1.4 mm diameter and 10 mm depth was prepared in each root. The teeth were grouped into morphologically similar pairs, and for each pair one tooth was randomly allocated to receive a zirconium ceramic post, the other a stainless steel post. The pairs of teeth were randomly assigned to a control or to a test group. The root-face was examined for dentine cracks or fractures with direct vision and at 20x magnification with transillumination. Samples were then stored in sterile water for one week. Ultrasonic vibration was applied continuously for 30 minutes to the top of the posts in the test groups. All samples were then re-examined for dentine cracks or fractures.

RESULTS

Following storage, no new cracks were evident for the control groups. Seven new cracks occurred in the test groups (following application of ultrasonic vibration), six of which were on the root-face of samples with ceramic posts. The difference in crack distribution between the two groups was significant (Fisher's Exact Test, p=0.029).

CONCLUSION

Prolonged application of ultrasonic vibration to ceramic posts increased the incidence of root-face cracks.

[Fronto-temporal anatomy and its application for augmentation plasty]

OBJECTIVE

To decide the safe dissection plane and evaluate the multiple materials used for the fronto-temporal augmentation.

METHODS

Clinical anatomical observation were made during the fronto-temporal operations. Forty-one patients were treated for the fronto-temporal augmentation with various granular or patched materials in different anatomical plane.

RESULTS

Four relatively safe dissection planes were found in the fronto-temporal area: (1) subcutaneous or above superficial temporal fascia, (2) subgalea plane 1.5 cm above the zygomatic arch, (3) between the deep temporal fascia and the temporal muscle, and (4) beneath the temporal periosteum. With the follow-ups from 6 months to 1 year, the appearance after the fronto-temporal augmentation in each patient was satisfactory or improved, except for the fat granule group with partial absorption and the ePTFE or Medpor hypothesis group shown a stepped contouring at the margin in a few patients.

CONCLUSION

Four dissection planes could be shown in the fronto-temporal region for the augmentation plasty with different advantages and disadvantages. The combination could be overcome the disadvantages to improve the results. Fat granule could be the best autograft for frontotemporal augmentation.