[Effect of titanium nitride coatings with different thickness on microhardness and cutting efficiency of nickel-titanium instruments].

Purpose: To investigate the effect of titanium nitride (TiN) coatings with different thicknesses on microhardness and cutting efficiency of nickel-titanium (NiTi) instruments, and to provide a basis for improving the efficiency of clinical root canal preparation.

Methods: Fifteen KV4 NiTi alloy sheets and sixty KV4 rotary NiTi files were selected and randomly divided into 5 groups: uncoated group, coating 1 h group, coating 2 h group, coating 3 h group and coating 4 h group. A layer of TiN coatings of different thicknesses was prepared on the surface of the coated groups by controlling the deposition time.

[Treatments of second mesiobuccal canals in maxillary permanent molar: a report of 2 cases].

With the increasing maturation of 3D printing technology, as well as its application in various industries, investigation of 3D printing technology into clinic medical education becomes an important task of the current medical education. The teaching content of oromaxillofacial head and neck surgical oncology is complicated and diverse, making lower understanding/memorizing efficiency and insufficient skill training. To overcome the disadvantage of traditional teaching method, it is necessary to introduce 3D printing technique into teaching of oromaxillofacial head and neck surgical oncology, in order to improve the teaching quality and problem solving capabilities, and finally promote cultivation of skilled and innovative talents.

[Comparison of wear resistance and flexural strength of three kinds of bulk-fill composite resins].

Purpose: To compare the abrasion resistance and flexure strength of three bulk-fill resin composites with an universal nano-hybrid composite resins.

Methods: The specimens were prepared with three kinds of bulk fill composites (SDR , sonicfill, Tetric N-Ceram Bulk Fill) and an universal nano-hybrid composite resins(Herculite Precis). 10 mm in diameter × 2mm in height specimens were prepared for abrasion resistance, while 2 mm in width × 2 mm in depth×25 mm in length specimens were prepared for flexure strength.

[Expression of Wnt5a in chronic apical periodontitis and its clinical significance].

Purpose: To detect the expression of Wnt5a in lesions of chronic apical periodontitis and determine the relationship between expression of Wnt5a and inflammation degree.

Methods: Ten patients with chronic apical periodontitis and 5 healthy controls were enrolled in this study. According to the inflammatory cell infiltration, the specimens were divided into 2 groups: severe inflammation group and mild inflammation group.

Biomechanical outcome of proximal femoral nail antirotation is superior to proximal femoral locking compression plate for reverse oblique intertrochanteric fractures: a biomechanical study of intertrochanteric fractures.

Objective: Reverse obliquity intertrochanteric fractures are a challenge for orthopedic surgeons. The optimal internal fixation for repairing this type of unstable intertrochanteric fractures remains controversial. This study aimed to compare the biomechanical properties in axial load and cyclical axial load of proximal femoral nail antirotation (PFNA) and proximal femoral locking compression plate (PFLCP) for fixation of reverse obliquity intertrochanteric fractures.

Biomechanical analysis of four types of internal fixation in subtrochanteric fracture models.

Objective: To compare the biomechanical properties of four types of internal fixation (proximal femoral nail [PFN], dynamic hip screw [DHS], dynamic condylar screw [DCS], and proximal femoral locking plate [PFLP]) for different types of subtrochanteric fractures.

Methods: Thirty-two antiseptic femurs were randomly divided into four groups. After internal fixation had been implanted, different types of subtrochanteric fracture models were produced and each tested under vertical, torsional and vertical damage loads.

[Study of the effect of chitosan and its composites on proliferation and differentiation of mouse osteoblasts].

Purpose: A mouse osteoblast cell line, MC3T3-E1, was cultivated in the medium that contained chitosan, type I collagen and recombinant human bone morphogenetic protein-2 in vitro to evaluate the effect of chitosan and its composites on proliferation and differentiation of mouse osteoblasts.

Methods: This study was categorized into 4 groups based on the medium used. Group A: α-MEM medium; group B: CS, type I collagen and α-MEM medium; group C: CS, type I collagen, rhBMP-2 and α-MEM medium.

Intramedullary nail versus dynamic compression plate fixation in treating humeral shaft fractures: grading the evidence through a meta-analysis.

There is a debate regarding the choice of operative intervention in humeral shaft fractures that require surgical intervention. The choices for operative interventions include intramedullary nailing (IMN) and dynamic compression plate (DCP). This meta-analysis was performed to compare fracture union, functional outcomes, and complication rates in patients treated with IMN or DCP for humeral shaft fractures and to develop GRADE (Grading of Recommendations, Assessment, Development, and Evaluation)-based recommendations for using the procedures to treat humeral shaft fractures.

[An in vitro evaluation of the effect of carboxymethyl chitosan and its composites against Enterococcus faecalis in the root canal].

Purpose: To evaluate the bacteriostasis effect of carboxymethyl chitosan and its composites on intracanal E. faecalis.

Methods: The pattern of E.

[Effect of root canal filling with warm vertical condensation under dental operating microscope].

Purpose: To evaluate the clinical effect of root canal filling with warm vertical condensation with or without dental operating microscope.

Methods: Fifty maxillary anterior teeth with single, straight canals were divided into two groups. Each tooth was instrumented by X-Smart rotary nickel-titanium files to a master file 0.

[Comparative study on the shaping ability of canals with 2 new nickel- titanium rotary instruments].

Purpose: To compare the shaping ability of two nickel-titanium rotary systems: Mtwo and K3.

Methods: Thirty-six mesio-buccal root canals of maxillary first molars were divided into two groups: group A(> or =20> or =) and group B(<20 degrees ),according to the angle of the canal. Then, each group was randomly divided into two subsets and prepared by Mtwo,K3, respectively.

[A study on acquired acid resistance of enamel and dentine irradiated by Er, Cr: YSGG laser in vitro].

Objective: To evaluate the acid resistance of enamel and dentin irradiated by Er, Cr: YSGG laser to artificial caries formation in vitro.

Methods: Enamel and dentin samples were irradiated with Er, Cr: YSGG laser at 6 W or 4 W for 6 second, respectively. Every sample was immersed in 3 ml of lactic demineralization solution at pH 4.

[Research on the effect of root canal seal achieved by irradiation of Er, Cr:YSGG laser].

Purpose: To evaluate the effect of root canal seal achieved by routine root canal preparation and irradiation of Er, Cr:YSGG laser in root canal therapy.

Methods: One hundred and five freshly single-rooted extracted human teeth were selected for the study, which were randomly divided into seven groups of fifteen each. The anatomic crowns were removed at the cementoenamel junction and the remaining roots were prepared endodontically with conventional methods.