Axially vascularized bone substitutes: a systematic review of literature and presentation of a novel model.

INTRODUCTION: The creation of axially vascularized bone substitutes (AVBS) has been successfully demonstrated in several animal models. One prototypical indication is bone replacement in patients with previously irradiated defect sites, such as in the mandibular region. The downside of current clinical practice, when free fibular or scapular grafts are used, is the creation of significant donor site morbidity. METHODS: Based on our previous experiments, we extended the creation of an arterio-venous loop to generate vascularized bone substitutes to a new defect model in the goat mandibula. In this report, we review the literature regarding different models for axially vascularized bone substitutes and present a novel model demonstrating the feasibility of combining this model with synthetic porous scaffold materials and biological tissue adhesives to grow cells and tissue. RESULTS: We were able to show the principal possibility to generate axially vascularized bony substitutes in vivo in goat mandibular defects harnessing the regenerative capacity of the living organism and completely avoiding donor site morbidity. CONCLUSION: From our findings, we conclude that this novel model may well offer new perspectives for orthopedic and traumatic bone defects that might benefit from the reduction of donor site morbidity.

Evaluation of 3D nano-macro porous bioactive glass scaffold for hard tissue engineering.

Recently, nano-macro dual-porous, three-dimensional (3D) glass structures were developed for use as bioscaffolds for hard tissue regeneration, but there have been concerns regarding the interconnectivity and homogeneity of nanopores in the scaffolds, as well as the cytotoxicity of the environment deep inside due to limited fluid access. Therefore, mercury porosimetry, nitrogen absorption, and TEM have been used to characterize nanopore network of the scaffolds. In parallel, viability of MG 63 human osteosarcoma cells seeded on scaffold surface was investigated by fluorescence, confocal and electron microscopy methods. The results show that cells attach, migrate and penetrate inside the glass scaffold with high proliferation and viability rate. Additionally, scaffolds were implanted under the skin of a male New Zealand rabbit for in vivo animal test. Initial observations show the formation of new tissue with blood vessels and collagen fibers deep inside the implanted scaffolds with no obvious inflammatory reaction. Thus, the new nano-macro dual-porous glass structure could be a promising bioscaffold for use in regenerative medicine and tissue engineering for bone regeneration.

Early Progressive Maxillary Changes with Nasoalveolar Molding: Randomized Controlled Clinical Trial.

OBJECTIVES: Quantitative assessment of 3-dimensional progressive changes of the maxillary geometry in unilateral cleft lip palate (UCLP) with and without nasoalveolar molding (NAM). METHODS: The study was designed as a prospective 2-arm randomized controlled clinical trial conducted in parallel. Forty infants with nonsyndromic UCLP were randomly assigned into a NAM-treated group (n = 20) and non-NAM treated group (n = 20). A total of 120 laser-scanned maxillary casts were collected and blindly analyzed via a modified algorithm at T0 (initial visit; baseline), T1 (after 3 wk; first interval), and T2 (after 6 wk; second interval). The main outcome measures were the amount and rate of cleft gap changes, the midline position, and the transverse, sagittal, and vertical growth through intervals. RESULTS: More than 50% of the cleft gap (56.42%; P < 0.001) was reduced in the first 3 wk of alveolar molding (AM). The end point of the AM was obtained in 6 wk (86.25%; P < 0.001); then, the kinks of the greater segment were noticed. The AM effect decreased as far as posterior; the anterior arch width reduced slightly (1.23%; P < 0.001), while the middle and posterior arches increased slightly (P > 0.999 and P = 0.288, respectively). The posterior arch width was the least changing and was considered a baseline, while the anterior was the pivot of the segment rotation. Both groups showed different patterns of segment rotation and sagittal growth. The non-NAM treated group showed a slight increase in cleft gap length, arch width, and midline position. CONCLUSION: Based on this study, it was concluded that the NAM treatment is effective in minimizing cleft severity and realigning maxillary segments without the deterioration of the transverse and vertical arch growth. Near follow-up visits are recommended to monitor the rapid gap reduction within the first 3 wk. Further trials are recommended to compare the outcomes regarding the sagittal growth to reference values (ClinicalTrials.gov NCT03029195). KNOWLEDGE TRANSFER STATEMENT: The results of this study will help clinicians understand nasoalveolar molding biomechanics that may improve the treatment outcomes for patients with unilateral cleft lip and palate. The trial data can be a valuable guide to the qualitative and quantitative predictive virtual molding in computer aided design-simulated nasoalveolar molding therapy. The modified algorithm can be used by researchers to quantify the rate, the sequence, and the direction of the maxillary segments movement in unilateral cleft lip and palate.

Bioglass in Alveolar Bone Regeneration in Orthodontic Patients: Randomized Controlled Clinical Trial.

This study was designed as a split-mouth randomized controlled clinical trial to evaluate the effects of a novel bioactive glass scaffold-tailored amorphous multiporous (TAMP)-for the preservation of alveolar bone following tooth extraction in class II orthodontic patients. TAMP scaffolds were prepared and sterilized. Patients were screened for eligibility, and 6 patients accounting for 14 extraction sockets were included in this stage. Sockets were randomly allocated to either control (left empty) or test (grafted with TAMP scaffold particles). Follow-up was done after 1, 2, 4, 8, and 12 to 17 wk with digital periapical radiographs to evaluate changes in crestal bone height and bone mineral density (BMD), 3-dimensional volumetric analysis of impression casts, and histologic analysis of core biopsies. Furthermore, alveolar bone marrow mesenchymal stem cells were cultured from control and test sockets following biopsy retrieval to evaluate the ability of TAMP bioactive glass scaffolds to recruit host progenitor cells. Results showed that sockets grafted with TAMP bioactive glass scaffolds better preserved height after 3 mo where mesially 57.1% of test cases showed preservation of socket height, compared with 28.6% of control cases. Distally, this was 42.9% of test cases versus none of the control cases. Regarding BMD, the test sides had higher BMD in all 3 sections of the socket, with the greatest reduction in BMD found in the coronal third. Results were not statistically significant. Histologically, sockets grafted with TAMP bioactive glass scaffolds showed a distinct pattern of bone healing characterized by vertical trabeculae and large vascularized marrow spaces with sockets showing corticalization. Volumetric analysis showed a better preservation of socket contour with TAMP bioactive glass scaffolds. TAMP bioactive glass scaffolds appeared to enhance the recruitment of stem cells from the grafted sockets. In conclusion, TAMP scaffolds appear to better preserve alveolar bone following extraction and allow for a more active bone modeling and remodeling process( ClinicalTrials.gov identifier:NCT01878084). Knowledge Transfer statement: The results of this study set the stage for the recommended use of novel biomimetic scaffolds, such as the tailored amorphous multiporous bioactive glass for preservation of the socket following extraction. This can be valuable for patients and clinicians alike when deciding on long-term prosthetic alternatives that not only result in immediate bone preservation but will accommodate the dynamic nature of bone.

Naturally Occurring Extracellular Matrix Scaffolds for Dermal Regeneration: Do They Really Need Cells?

The pronounced effect of extracellular matrix (ECM) scaffolds in supporting tissue regeneration is related mainly to their maintained 3D structure and their bioactive components. These decellularized matrix scaffolds could be revitalized before grafting via adding stem cells, fibroblasts, or keratinocytes to promote wound healing. We reviewed the online published literature in the last five years for the studies that performed ECM revitalization and discussed the results of these studies and the related literature. Eighteen articles met the search criteria. Twelve studies included adding cells to acellular dermal matrix (ADM), 3 studies were on small intestinal mucosa (SIS), one study was on urinary bladder matrix (UBM), one study was on amniotic membrane, and one study included both SIS and ADM loaded constructs. We believe that, in chronic and difficult-to-heal wounds, revitalizing the ECM scaffolds would be beneficial to overcome the defective host tissue interaction. This belief still has to be verified by high quality randomised clinical trials, which are still lacking in literature.

Reinforcement of denture base resin with glass fillers.

PURPOSE: This study evaluated the effect of short glass fibers on the transverse strength of a heat-polymerized acrylic resin denture base material. MATERIALS AND METHODS: Four groups of specimens (n = 10) were fabricated according to the ISO standard for the transverse strength test. E-glass fibers were triturated to produce short fibers of different lengths. Specimens for Group 1 (control) were made of unfilled polymethylmethacrylate (PMMA). For group 2, the PMMA powder was modified with 0.1 g of dry glass fibers. For group 3, the PMMA powder was modified with 0.1 g of silanized glass fibers. For group 4, the PMMA powder was modified with 0.2 g of silanized glass fibers. A three-point loading test was used to determine the transverse strength of the tested specimens. The fracture surface of each specimen was evaluated using SEM. RESULTS: The addition of untreated glass fibers increased the transverse strength by 11% but produced some porosity in the polymeric matrix. The addition of silane-treated glass fibers increased the transverse strength of PMMA by 28% for group 3 and by 26% for group 4, and produced a dense structure for the polymer-fiber composite. CONCLUSION: The transverse strength of PMMA can be slightly increased by the addition of short glass fibers.

Measurement (in vitro) of the amount of force required to dislodge specific clasps from different depths of undercut.

A fundamental principle in clasp selection for a specific abutment is the reduction of the transmission of excessive forces to that abutment. The flexibility of a clasp was believed to directly affect the reduction of such forces. This study compares the average measurements of forces required to dislodge two kinds of circumferential clasps in different amounts of undercuts: one with a half-round retentive arm and the other with a round retentive arm under tensile load. Three commonly used undercuts were created on six cast crowns, premolars, and molars. Each clasp was exposed to adequate tensile load until dislodgment occurred. The test was run six times for the same clasp. The means of tensile load required to dislodge each of the different clasps were compared statistically. However, no significant difference was detected for the main effects of the three variables studied: tooth type, undercut, and amount and clasp type. Findings indicated the possible use of cast round clasps where advantages of clinical fit and reduction of transmitted forces to the abutments can be gained.

Restoration of inadequate occlusal face height by using resin bonded to etched metal removable prosthesis.

The resin bonded to etched metal casting of a removable partial denture was used anteriorly in combination with posterior acrylic resin teeth to restore patients with mandibular overclosure. The procedure is simple, esthetic, conservative, inexpensive, and not time-consuming. Patients maintained their new occlusal facial height with normal functional activity. The remaining natural teeth showed no signs of changes in 6 months in either opposing tooth structure or the periodontium.

Effect of low-energy laser application in the treatment of denture-induced mucosal lesions.

STATEMENT OF PROBLEM: Mucosal inflammation under dentures causes problems for prosthodontists and patients. PURPOSE OF STUDY: This study evaluated the effectiveness of a low-energy laser used in the treatment of denture-induced mucosal lesions in comparison with other conventional methods. MATERIAL AND METHODS: Eighteen men were selected and divided into three groups of six according to the treatment applied: denture removal, relined dentures with temporary tissue treatment, and application of laser irradiation for the lesions while continuing to wear the dentures. Oral hygiene and nutrition were maintained during the study. Clinical, histologic, and densitometric assessments were used to evaluate the three treatment methods. RESULTS: The results revealed that lesions in the group treated with laser irradiation were clinically superior in healing when compared with the other groups. Histologic evidence of the therapeutic effect of lasers in healing denture-induced mucosal lesions was demonstrated. Densitometric evaluation showed an increase in the optical density of alveolar bone underneath the irradiated lesions compared with untreated lesions. CONCLUSION: These findings suggest the effect of therapeutic laser treatment on both soft tissue and bone with subsequent improvement of denture foundation after treatment of denture-induced mucosal lesions.