Introduction The aim of this study was to verify whether the use of short implants could optimize stress distribution of bone surrounding implants in atrophic mandibles with different bone qualities. Methods A three-dimensional model of the atrophic mandible with three levels of bone quality was made using computer software. Short implants (6 mm) and standard implants (10 mm) were used in four designs: Design 1 "All-On four", Design 2 "All-On-four" with two short implants, Design 3 four vertical implants with two short implants, and Design 4 six short implants. The distal short implants were placed at the first molar position. All twelve models were imported into finite element analysis software, and 110 N oblique force was loaded on the left second premolar. Maximum principal stress values of peri-implant bone and the volumes of bone with over 3000 microstrians (overload)were analyzed. Result Stress values and volumes of overload bone increased in all four groups with the decline of bone quality. The highest stress values were found in the cortical bone surrounding the Design 1 inclined implant in two lower bone quality mandibles, and the lowest in Design 3. However, Design 1 had less overload bone tissue than all three designs with short implants. Conclusion Short implants placed posteriorly helped decrease stress values in peri-implant bone, while bone surrounding short implants had a high resorption risk in low bone quality mandible.

The application of titanium in the orthopedic and dental fields is associated with bacterial infection and chronic inflammation, especially in the early stages after its implantation.

Implant repair is a common means to restore the normal function of the hard tissues (bone or teeth). At present, the commonly and potentially used implant materials include titanium alloy (Ti), zirconia (Zr), polyetheretherketone (PEEK), and 30% carbon fiber reinforced PEEK (CFR-PEEK). This study compares their physicochemical and biological properties, including surface morphology, contact angle, nano hardness, elastic modulus, and the impact on the proliferation and osteogenic differentiation of bone marrow mesenchyml stem cell. Additionally, the differences in bacteria adhesion rates among materials were compared. CFR-PEEK had the highest contact angle, followed by PEEK, Zr, and Ti. Zr had the highest nano hardness and modulus of elasticity, followed by Ti, CRF-PEEK, and PEEK. There was no statistically significant difference in cytotoxicity among materials based on the liquid extract test. However, the relative cell proliferation rate on the surface of CFR-PEEK was slightly lower than that of Ti and Zr. Moreover, alkaline phosphatase activity, extracellular matrix mineralization, and osteogenic gene expression with the Ti and Zr materials were higher than with the PEEK and CFR-PEEK materials at Day 7, and Zr showed the highest osteogenic gene expression level among materials at Day 14. Ti had the greatest number of bacterial colonies that adhered to it, followed by Zr, CFR-PEEK, and PEEK. While the mechanical properties of PEEK and CFR-PEEK were closer to bone tissue and their anti-adhesion effect against bacteria was better than those of Ti and Zr, modification methods are needed to improve the osteogenic properties of these biopolymers.

The aim of this retrospective study was to evaluate the horizontal bone gain at the different level of alveolar bone using titanium screw as a reference plane by titanium mesh with tent screw (exposed or not) and autologous bone grafting. 16 patients and 23 measured points were enrolled in this study. CBCT data of immediately and 6 months after bone grafting were measured at crestal (CW), midway (MW), and basal (BW) level and reconstructed for area measurement. The exposure of Ti-mesh or not had been evaluated. The area of bone gained and absorption ratio were almost the same. The width absorption ratio of titanium mesh and onlay grafting group or at CW, MW, and BW were almost the same. However, the width absorption ratio of the exposed Ti-mesh at CW, MW, and BW were significantly higher than the not exposed one. Thin biotype was a main factor of titanium mesh exposure. The exposed Ti-mesh at late phase also can achieve clinically accepted bone gained after certain anti-inflammatory treatment. Ti-mesh with tenting screw could achieve the same bone augmentation effect as the autogenous bone block did, even it is exposed at late phase. However, the absorption ratio significantly increased if exposed.