Temporomandibular Joint Disc Reduction And Fixation.

OBJECTIVE: To evaluate the clinical effectiveness and stability of open suture versus micro-screw anchored disc reduction and fixation in treating disc displacement without reduction in the anterior temporomandibular joint. METHODS: A total of 38 patients (51 sides) with anterior disc displacement without reduction (ADDwR) of the TMJ treated in our hospital from August 2021 to January 2023 were selected, including 19 cases in group A (23 sides) treated with open temporomandibular joint disc reduction and anchorage, and 19 cases in group B (28 sides) treated with temporomandibular joint disc reduction and suture. The Magnetic Resonance Imaging (MRI) data of the two groups before and after operation were compared to evaluate the effective rate of articular disc reduction, the change of articular disc length, The Maximal Interincisal Opening (MIO) and Numeric Rating Scale (NRS) were measured before and after operation. RESULTS: In group A, the MRI effective rate 6 months after disc reduction was 95.65% (22/23), the disc length gain was 1.74mm, MIO was 40.32±5.067mm, and NRS was 0.47±0.697. The MRI effective rate 6 months after disc reduction in group B was 100% (28/28). The disc length gain was 1.78mm, MIO was 41.58±3.746mm, and NRS was 0.00. There was no significant difference between the two groups (P>0.05). CONCLUSIONS: TMJ disc reduction and suture and open TMJ disc anchorage can effectively reduce the TMJ disc. The TMJ disc stability is high at 6 months after operation, and the pain and mouth opening can be improved, which is worthy of further promotion in clinical practice.

[Estimation of biomechanical behavior in deep wedge-shaped defects restored by different methods under static and dynamic loads: a 3D finite analysis].

PURPOSE: To analyze the biomechanical properties of the right mandibular second premolar with deep wedge-shaped defects under static and dynamic loads by finite element method, so as to select appropriate repair method in clinic. METHODS: To establish the deep wedge-shaped defect model of the right mandibular second premolar, the unrepaired model after root canal treatment was used as the control group, and resin filling (group A), resin filling after post restoration (group B), crown restoration after resin filling (group C), post and crown restoration after resin filling (group D) were used as the experimental groups. According to different materials, group B and group D were further divided into fiber post (B1, D1) group and pure Ti post (B2, D2) group. Static and dynamic loading were applied by three dimensional finite element analysis software, and the stress and strain were analyzed before and after restoration. RESULTS: Compared with the control group, the stress values under static loading was much lower than that under dynamic loading. Von Mises and the maximum principal stress in each experimental group decreased significantly under static and dynamic loading. In the post group, the stress distribution of fiber post was more uniform than that of pure Ti post. CONCLUSIONS: Dynamic load has great influence on the stress distribution. Full crown restoration is beneficial to the stress distribution of the teeth with deep wedge-shaped defects. If a post is necessary, fiber post should be selected.

New series of corers for taking undisturbed vertical samples of soft bottom sediments.

A new series of sediment corers--a Single Tube Gravity Corer and a Multiple Tube Gravity Corer has been developed for taking undisturbed vertical soft sediment samples, and a Hydraulic Pressure Multiple Tube Corer has been preliminarily designed. The Single Tube Gravity Corer can be operated by hand easily without using a winch, and it might be the simplest and the cheapest core sampler available. The Multiple Tube Gravity Corer was developed based on the Single Corer, which normally consists of three coring tubes, however, it is possible to install up to six tubes. The Hydraulic Pressure Multiple Tube Corer has been designed based on the Multiple Corer, which would take undisturbed sediment samples, and would be controlled by a computer and monitored by an underwater video camera. The pore water collection and the sediment Eh measurement-subsampling process through the transparent plastic tube wall is straightforward. Compared to other types of coring devices, such as the famous KC Kajak sediment core sampler made in Denmark; these corers have greater reliability, being simple in structure, relatively light weight, easy and efficient to operate, highly adaptable, and relatively inexpensive to produce.