Objective To extract and summarize the clinical registration information of periodontitis registered in the US ClinicalTrials.gov and Chinese Clinical Trial Registry(ChiCTR),and further analyze the registration characteristics of periodontitis clinical trials.Methods The ClinicalTrials.gov and ChiCTR data-bases were searched and compiled for periodontitis clinical registration information from 2000 to December 26,2024,including registration number,country/region of registration,annual number of registered projects,sample size,study type and design,study phase,and trial progress status.Results As of December 26,2024,a total of 520 242 registered clinical trials were retrieved from the ClinicalTrials.gov registry platform,of which 1 542(0.30%)were related to periodontitis.There were 189(12.26%)studies on periodontitis-related pro-jects in Turkey,while a total of 37(2.4%)projects were initiated by researchers in China,which ranked ninth.The Chinese Clinical Trial Register(ChiCTR)had 92 954 registered projects,of which 165 were on pe-riodontitis,and most of them were conducted by well-known affiliated hospitals and stomatology hospitals.The number of registrations in the ClinicalTrials.gov database increased year by year and reached a peak in 2022(146 registrations).Trial designs were focused on interventional and observational studies.ClinicalTri-als.gov study phases were focused on phases 2 and 4,while ChiCTR was clustered at phase 0(pre-registra-tion).Conclusion The number of clinical registrations for periodontitis in China's database is relatively low,and despite a steady upward trend,there is still a gap compared with other countries internationally.Future re-search should focus on how to encourage more oral health related research institutions to register on the plat-form and how to increase the sample size.

BACKGROUND:The treatment for bacterial biofilms after internal fixation surgery is a very difficult problem in clinic.It is a great significance to establish an animal model of irrigation for treating bacterial biofilms in the early stage after internal fixation surgery. OBJECTIVE:To establish an animal model for treating bacterial biofilms with different drugs through irrigation in early stage after internal fixation surgery. METHODS:Six New Zealand white rabbits were selected.Bilateral femoral surfaces were exposed and drilled holes were made,and bone plates colonized with Pseudomonas aeruginosa(experimental group)and blank bone plates(blank control group)were implanted around the drilled holes on one side,and two drainage tubes were retained and fixed to serve as the"inlet"and"outlet,"respectively.The model was immersed for a certain period of time after simulated perfusion before rinsing.After the simulated irrigation,the plates were soaked for a certain time before washing.At 5 days postoperatively,the rabbits were observed for body temperature,wound condition,bacterial culture of drainage fluid,and crystalline violet staining and scanning electron microscopy of the bone plate. RESULTS AND CONCLUSION:Six rabbits had difficulty in moving the affected limbs after surgery and showed elevated body temperature at 2-4 days after surgery.Local swelling could be touched at some wounds in the experimental group,and the wounds in the blank control group healed well.The results of bacterial culture of drainage fluid showed that Pseudomonas aeruginosa diffused or spread in the experimental group.At 5 days after surgery,the plate in the experimental group became purple shown by crystalline violet staining,and the absorbance value at 570 nm detected by the microplate reader was 2.621±0.088,indicating the presence of bacteria.Scanning electron microscopy at 5 days after surgery showed that a large number of bacterial microcolonies appeared on the surface of the plate in the experimental group,forming a highly inhomogeneous three-dimensional structure similar to the"mushroom-like"and"tower-like"structures,with filamentous water channels connecting the"mushroom-like"structures,which were typical biofilm structures with high densities,while no obvious colonies were seen in the blank control group.Overall,this animal model simulates the state of infected biofilm formation due to early infection after internal fixation and provides an available method of irrigation with different drugs.

Objective To investigate the outcome of a new designed extramedullary femoral alignment system and to compare with conventional intramedullary system in clinical results.Methods Twenty consecutive patients (3 males and 17females with an average age of 70.1 (range,52-82 years old) with osteoarthritis (OA) or rheumatoid arthritis (RA) who were treated with the extramedullary method between January 2015 to August 2015 and 20 consecutive patients (5 males and 15 females with an average age of 65.9 (range,52-87 years old) with OA or RA treated with conventional intramedullary method between April 2015 to September 2015 were studied.In extramedullary group,CT scan was used to evaluate the relation between the hip (femoral head) center and anterior superior iliac spine preoperatively.During the total knee arthroplasty,the hip joint center was defined according to the anterior superior iliac spine (ASIS).Knee joint center was defined as the center of the line connecting medial and lateral epicondyle.The terminal femoral bone cut plane was defined as the line between femoral and knee center.In intramedullary group,the traditional intramedullary method was adopted.The coronal and sagittal alignment,blood loss and drainage at one week postoperatively and the range of motion at one week,6 weeks and 3 months were evaluated.Results There was no significant difference in age,hip-knee-ankle (HKA) angle,the Hospital for Special Surgery (HSS) Knee Score,BMI,operation time within the two groups.Blood loss and drainage in extramedullary group (121 ±64 ml and 181±149 ml) was significantly less than that in intramedullary group (177±47 ml and 292±156 ml).There was no significant difference in coronal alignment of the femoral prosthesis within the two groups (89.8°±2.1° v.s.89.8°±2.2°,P＞0.05).However,the two groups had significant difference in sagittal alignment (-0.8°±2.2° v.s.2.5°±2.1 °,P＜0.05).The alignment of extramedullary group had much more tendency in flexion degree.No difference was found in range of motion at 1 week,6 weeks and 3 months postoperatively (103.8°±7.8° v.s.102.5°±7.2°,108.5°±8.0° v.s.108.3°±7.4°,117.0°±7.1° v.s.114.5°±8.1°,P＞0.05).Conclusion The present designed extramedullary system is practical in total knee arthroplasty and has more accuracy in sagittal plane.The patients treated with extramedullary system have less blood loss and drainage and have similar range of motion in early stage after operation when compared with the intramedullary method.