Effect of the prosthetic index on stress distribution in Morse taper connection implant system and peri-implant bone: a 3D finite element analysis.

BACKGROUND: The combination of a prosthetic index with Morse taper connection was developed, with the purpose of making prosthetic procedures more precise. However, the presence of the index may compromise the mechanical performance of the abutment. The aim of this study is to evaluate the effect of prosthetic index on stress distribution in implant-abutment-screw system and peri-implant bone by using the 3D finite element methodology. METHODS: Two commercial dental implant systems with different implant-abutment connections were used: the Morse taper connection with platform switching (MT-PS) implant system and the internal hex connection with platform matching (IH-PM) implant system. Meanwhile, there are two different designs of Morse taper connection abutment, namely, abutments with or without index. Consequently, three different models were developed and evaluated: (1) MT-PS indexed, (2) MT-PS non-indexed, and (3) IH-PM. These models were inserted into a bone block. Vertical and oblique forces of 100 N were applied to each abutment to simulate occlusal loadings. RESULTS: For the MT-PS implant system, the maximum stress was always concentrated in the abutment neck under both vertical and oblique loading. Moreover, the maximum von Mises stress in the neck of the MT-PS abutment with index even exceed the yield strength of titanium alloy under the oblique loading. For the IH-PM implant system, however, the maximum stress was always located at the implant. Additionally, the MT-PS implant system has a significantly higher stress level in the abutment neck and a lower stress level around the peri-implant bone compared to the IH-PM implant system. The combined average maximum stress from vertical and oblique loads is 2.04 times higher in the MT-PS indexed model, and 1.82 times for the MT-PS non-indexed model than that of the IH-PM model. CONCLUSIONS: MT-PS with index will cause higher stress concentration on the abutment neck than that of without index, which is more prone to mechanical complications. Nevertheless, MT-PS decreases stress within cancellous bone and may contribute to limiting crestal bone resorption.

An Up-To-Date Overview of Dental Tissue Regeneration Using Dental Origin Mesenchymal Stem Cells: Challenges and Road Ahead.

Stem cells (SCs) research has experienced exponential growth in recent years. SC-based treatments can enhance the lives of people suffering from cardiac ischemia, Alzheimer's disease, and regenerative drug conditions, like bone or loss of teeth. Numerous kinds of progenitor/SCs have been hypothesized to depend on their potential to regain and/or heal wounded tissue and partly recover organ function. Growing data suggest that SCs (SCs) are concentrated in functions and that particular tissues have more SCs. Dental tissues, in particular, are considered a significant cause of mesenchymal stem cells (MSCs) cells appropriate for tissue regeneration uses. Tissue regeneration and SCs biology have particular attention in dentistry because they may give a novel method for creating clinical material and/or tissue redevelopment. Dental pulp, dental papilla, periodontal ligament, and dental follicle contain mesenchymal SCs. Such SCs, which must be identified and cultivated in specific tissue culture environments, may be used in tissue engineering applications such as tooth tissue, nerve regeneration, and bone redevelopment. A new cause of SCs, induced pluripotent SCs, was successfully made from human somatic cells, enabling the generation of the patient and disease-specific SCs. The dental SC's (DSCs) multipotency, rapid proliferation rate, and accessibility make it an ideal basis of MSC for tissue redevelopment. This article discusses current advances in tooth SC investigation and its possible application in tissue redevelopment.

Modified membrane fixation technique in a severe continuous horizontal bone defect: A case report.

BACKGROUND: Continuous severe horizontal bone defect is common in the aesthetic maxillary anterior area, and presents a major challenge in implant dentistry and requires predictable bone augmentation to increase the width of the alveolar bone. CASE SUMMARY: A 24-year-old man, with a history of well-controlled IgA nephropathy, presented to the Dentistry Department of our hospital complaining of missing his right maxillary anterior teeth 1 mo ago. Severe horizontal alveolar bone defects at sites of teeth 12, 13 and 14 were diagnosed. A modified guided bone regeneration surgical approach stabilizing the absorbable collagen membrane and particulate graft materials by periosteal diagonal mattress suture (PDMS) combined with four corner pins was used for this severe continuous horizontal bone defect. The outcome revealed that the newly formed alveolar ridge dimension increased from 0.72 mm to 11.55 mm horizontally 10 mo postoperatively, with no adverse events. The implant surgery was successfully performed. CONCLUSION: This case highlights that PDMS combined with four corner pins is feasible to maintain the space and stabilize the graft and membranes in severe continuous horizontal bone defect.

Systematic comparison of biologically active foreign ions-codoped calcium phosphate microparticles on osteogenic differentiation in rat osteoporotic and normal mesenchymal stem cells.

Osteoporosis is a disease characterized by structural deterioration of bone tissue, leading to skeletal fragility with increased fracture risk. Calcium phosphates (CaPs) are widely used in bone tissue engineering strategies as they have similarities to bone apatite except for the absence of trace elements (TEs) in the CaPs. Bioactive glasses (BGs) have also been used successfully in clinic for craniomaxillofacial and dental applications during the last two decades due to their excellent potential for bonding with bone and inducing osteoblastic differentiation. In this study, we evaluated the osteogenic effects of the ionic dissolution products of the quaternary Si-Sr-Zn-Mg-codoped CaP (TEs-CaP) or 45S5 Bioglass® (45S5 BG), both as mixtures and separately, on rat bone marrow-derived mesenchymal stem cells (rOMSCs & rMSCs) from osteoporotic and normal animals, using an MTT test and Alizarin Red S staining. The materials enhanced cell proliferation and osteogenic differentiation, especially the combination of the BG and TEs-CaP. Analysis by quantitative PCR and ELISA indicated that the expression of osteogenic-specific genes and proteins were elevated. These investigations suggest that the TEs-CaP and 45S5 BG operate synergistically to create an extracellular environment that promotes proliferation and terminal osteogenic differentiation of both osteoporotic and normal rMSCs.