Peri-implant keratinized mucosa (PIKM) augmentation refers to surgical procedures aimed at increasing the width of PIKM. Consensus reports emphasize the necessity of maintaining a minimum width of PIKM to ensure long-term peri-implant health. Currently, several surgical techniques have been validated for their effectiveness in increasing PIKM. However, the selection and application of PIKM augmentation methods may present challenges for dental practitioners due to heterogeneity in surgical techniques, variations in clinical scenarios, and anatomical differences. Therefore, clear guidelines and considerations for PIKM augmentation are needed. This expert consensus focuses on the commonly employed surgical techniques for PIKM augmentation and the factors influencing their selection at second-stage surgery. It aims to establish a standardized framework for assessing, planning, and executing PIKM augmentation procedures, with the goal of offering evidence-based guidance to enhance the predictability and success of PIKM augmentation.
Humans ; Consensus ; Dental Implants ; Mouth Mucosa/surgery* ; Keratins

Objective:To explore the differences in the ability of different parts of the human skin to recognize vibration frequencies in order to provide data for physiological optimization of vibration parameters in pilots′ tactile vests.Methods:Ten healthy volunteers were selected and grouped by age as 20-40 years (6 cases) and 41-50 years (4 cases). All the subjects participated in 3 trials: ① identification test of frequency steps using cutaneous tactile perception: the back of the left hand was chosen as the test area, a dual-oscillator synchronous vibration system was adopted, and the frequency step was gradually increased (initially 0.1 Hz) to determine the threshold of frequency identification; ② maximum frequency threshold test of cutaneous tactile perception: the maximum frequency recognition thresholds in 7 parts of the trunk (the left waist, right waist, chest, back, left shoulder, right shoulder, neck) and the back of the hand were tested; ③ frequency discrimination test of cutaneous tactile perception: 5 equally spaced frequencies (covering the frequency recognition thresholds) were set to evaluate the accuracy of tactile frequency memory on the back of the hand after 3, 15 min and 24 h. The relationships between the adjacent step sizes of cutaneous tactile perception and the average value of the sum of adjacent frequencies were analyzed using simple linear regression. The highest identification thresholds of frequencies in different parts of the subjects as well as the accuracy of frequency discrimination during different periods were compared across the age groups.Results:The maximum thresholds of frequency identification of cutaneous tactile perception among the 10 subjects ranged from 16.20 to 33.55 Hz, while the range of adjacent step sizes was between 3.60 and 7.10 Hz. The adjacent step sizes were positively correlated with the average value of the sum of adjacent frequencies ( r=0.882, F=529.18, P<0.001). In the test on the maximum threshold of frequency identification of cutaneous tactile perception, there was a statistically significant difference in the main effect of an age group between the 2 groups ( F=15.87, P<0.001), but not in the main effect of the site ( P>0.05), or in the interactions between the group and age ( P>0.05). The accuracies of skin vibration frequency memory on the dorsal hand of the subjects at 3, 15 min and 24 h were 88%, 72% and 68% respectively. In the frequency discrimination test, there were no statistically significant differences in the main effect of the group, main effect of time or in their interactions between the 2 groups (all P>0.05). Conclusions:The ability of the human skin to identify vibration frequency is impacted by age, but there is no difference in sensitivity between the trunk and the back of the hand. It is recommended that the tactile vest for pilots be designed for general purposes to make it easy to adapt to vibration frequencies of multiple parts.

Objective:To verify the applicability of the flight potential evaluation system in the psychological selection of pilots by testing the reliability and validity of the system.Methods:Between September and October 2021, 82 subjects, including 32 pilots and 50 volunteers, were recruited from the Aviation Force and the Air Force Medical Center to complete the flight potential evaluation system test. The pilots and volunteers were divided into the high score group (the top 27% in terms of scores) and low score group (the 27% from the bottom) according to the total score of the evaluation. In order to ensure the consistency of evaluation conditions, some subjects were selected to complete a second evaluation test one week later for reliability analysis. Six flight experts completed the Content Evaluation Form of the Flight Potential Evaluation System while the officer completed the Flight Performance Evaluation Questionnaire as the performance data of the pilots. The pass rates of the pilots and volunteers and discriminability of the flight potential evaluation system were analyzed to test the stability and effectiveness of the system.Results:①The flight potential evaluation system demonstrated a pass rate of 0.75 and a discriminability of 0.30 in pilots, compared with 0.30 and 0.51 in volunteers. The total scores of pilots and volunteers were (7.00±1.16) points and (3.38±2.15) points, respectively, with a statistically significant difference ( t=9.87, P<0.001). Significant differences were found in test scores between high-score group and low-score group for both pilots ( t=10.01, P<0.001) and volunteers ( Z=-4.65, P<0.001). ②Thirty-seven subjects (including 32 pilots and 5 volunteers, all from the Aviation Force) were tested twice, and the Pearson product-moment correlation coefficient for the paired results of 2 identical tests was r=0.750 ( P<0.001). ③As for the content of the evaluation system test, the experts′ degree of agreement and unanimity rate were 1. The evaluation score by the officer was positively correlated with the test score ( r=0.389, P=0.041). Conclusions:The flight potential evaluation system has a strong ability to distinguish flight-related abilities, suggesting that the system can be applied to the psychological selection of pilots and provide data for subsequent tests during the recruitment of candidates.

Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.

Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.

Objective:To explore the differences in the ability of different parts of the human skin to recognize vibration frequencies in order to provide data for physiological optimization of vibration parameters in pilots′ tactile vests.Methods:Ten healthy volunteers were selected and grouped by age as 20-40 years (6 cases) and 41-50 years (4 cases). All the subjects participated in 3 trials: ① identification test of frequency steps using cutaneous tactile perception: the back of the left hand was chosen as the test area, a dual-oscillator synchronous vibration system was adopted, and the frequency step was gradually increased (initially 0.1 Hz) to determine the threshold of frequency identification; ② maximum frequency threshold test of cutaneous tactile perception: the maximum frequency recognition thresholds in 7 parts of the trunk (the left waist, right waist, chest, back, left shoulder, right shoulder, neck) and the back of the hand were tested; ③ frequency discrimination test of cutaneous tactile perception: 5 equally spaced frequencies (covering the frequency recognition thresholds) were set to evaluate the accuracy of tactile frequency memory on the back of the hand after 3, 15 min and 24 h. The relationships between the adjacent step sizes of cutaneous tactile perception and the average value of the sum of adjacent frequencies were analyzed using simple linear regression. The highest identification thresholds of frequencies in different parts of the subjects as well as the accuracy of frequency discrimination during different periods were compared across the age groups.Results:The maximum thresholds of frequency identification of cutaneous tactile perception among the 10 subjects ranged from 16.20 to 33.55 Hz, while the range of adjacent step sizes was between 3.60 and 7.10 Hz. The adjacent step sizes were positively correlated with the average value of the sum of adjacent frequencies ( r=0.882, F=529.18, P<0.001). In the test on the maximum threshold of frequency identification of cutaneous tactile perception, there was a statistically significant difference in the main effect of an age group between the 2 groups ( F=15.87, P<0.001), but not in the main effect of the site ( P>0.05), or in the interactions between the group and age ( P>0.05). The accuracies of skin vibration frequency memory on the dorsal hand of the subjects at 3, 15 min and 24 h were 88%, 72% and 68% respectively. In the frequency discrimination test, there were no statistically significant differences in the main effect of the group, main effect of time or in their interactions between the 2 groups (all P>0.05). Conclusions:The ability of the human skin to identify vibration frequency is impacted by age, but there is no difference in sensitivity between the trunk and the back of the hand. It is recommended that the tactile vest for pilots be designed for general purposes to make it easy to adapt to vibration frequencies of multiple parts.

Objective:To verify the applicability of the flight potential evaluation system in the psychological selection of pilots by testing the reliability and validity of the system.Methods:Between September and October 2021, 82 subjects, including 32 pilots and 50 volunteers, were recruited from the Aviation Force and the Air Force Medical Center to complete the flight potential evaluation system test. The pilots and volunteers were divided into the high score group (the top 27% in terms of scores) and low score group (the 27% from the bottom) according to the total score of the evaluation. In order to ensure the consistency of evaluation conditions, some subjects were selected to complete a second evaluation test one week later for reliability analysis. Six flight experts completed the Content Evaluation Form of the Flight Potential Evaluation System while the officer completed the Flight Performance Evaluation Questionnaire as the performance data of the pilots. The pass rates of the pilots and volunteers and discriminability of the flight potential evaluation system were analyzed to test the stability and effectiveness of the system.Results:①The flight potential evaluation system demonstrated a pass rate of 0.75 and a discriminability of 0.30 in pilots, compared with 0.30 and 0.51 in volunteers. The total scores of pilots and volunteers were (7.00±1.16) points and (3.38±2.15) points, respectively, with a statistically significant difference ( t=9.87, P<0.001). Significant differences were found in test scores between high-score group and low-score group for both pilots ( t=10.01, P<0.001) and volunteers ( Z=-4.65, P<0.001). ②Thirty-seven subjects (including 32 pilots and 5 volunteers, all from the Aviation Force) were tested twice, and the Pearson product-moment correlation coefficient for the paired results of 2 identical tests was r=0.750 ( P<0.001). ③As for the content of the evaluation system test, the experts′ degree of agreement and unanimity rate were 1. The evaluation score by the officer was positively correlated with the test score ( r=0.389, P=0.041). Conclusions:The flight potential evaluation system has a strong ability to distinguish flight-related abilities, suggesting that the system can be applied to the psychological selection of pilots and provide data for subsequent tests during the recruitment of candidates.

Objective:To investigate the accuracy of magnetic resonance imaging (MRI) cine sequences in determining the range of tumor motion in radiotherapy, providing a basis for the precise delineation of the target volume in motion for radiation therapy.Methods:A modified chest motion phantom was placed in a MRI scanner, and a water-filled sphere was used to simulate a tumor. True fast imaging with steady precession (TrueFISP) MRI cine sequences from Siemens were used to capture the two-dimensional motion images of the simulated tumor. The phantom experiments were divided into three modes: head-foot motion mode, rotation motion mode, and actual respiratory waveform mode. In the head-foot motion mode, respiratory motion period (3, 4, 5, 6, 7 and 8 s), amplitude (5, 10 and 15 mm), and respiratory waveform of the simulated tumor (sin and cos4) were set, resulting in a total of 36 motion combinations. In the rotation motion mode, a cos4 waveform was used for respiration, with respiratory periods of 3, 4, 5, 6, 7 and 8 s, head-foot motion set amplitudes of 5, 10 and 15 mm, and anterior-posterior (AP) and left-right (LR) motion set amplitudes in three combinations ([2.5, 2.5] mm, [2.5, 5.0] mm, [5.0, 5.0] mm), resulting in a total of 54 motion combinations. In the actual respiratory waveform mode, respiratory waveforms of 5 randomly selected patients from Affiliated Cancer Hospital of Zhengzhou University were obtained. Under each motion combination, TrueFISP cine images (30 frames, with an acquisition time of 11 s per frame) were obtained. The code was used to automatically identify the two-dimensional coordinates of the center of the simulated tumor in each image, and sin and cos4 functions were separately employed to fit the tumor position in the motion direction, thereby obtaining the fitted motion period and amplitude. The difference between the maximum and minimum values of the tumor's center coordinates in the head-to-foot direction is taken as the range of movement, referred to as the calculated amplitude. For the actual respiratory waveform, the distance between the measured maximum and minimum positions is used to calculate the amplitude.Results:In the head-foot motion mode, the fitted amplitudes of both sin and cos4 waveforms deviated from the set amplitudes by 0-0.51 mm, with relative deviations of 0%-4.2%. The deviation range between the calculated amplitudes and the set amplitudes of the two waveforms were 0.08-0.94 mm, with relative deviations of 1.1%-6.3%. In the rotation motion mode, the fitted amplitudes deviated from the set amplitudes by 0-0.61 mm, with relative deviations of 0%-6.2%. And the deviation range between the calculated amplitudes and the set amplitudes were 0.16-0.94 mm, with relative deviations of 0%-6.3%. In the actual respiratory waveform motion mode, the deviation range between the calculated amplitudes and the set amplitudes were 0.10-0.48 mm, with relative deviations of 2.2%-8.6%.Conclusion:TrueFISP cine sequences show minimal deviations in determining the range of tumor head-foot motion and effectively captures the tumor's movement state, thereby providing important support for the precise definition of the tumor movement target area during radiotherapy .

Objective:To compare the effects on DNA strand break induced by ultra-high dose rate (FLASH) electron beam and conventional irradiation, and investigate whether FLASH effect was correlated with a reduction of radiation response.Methods:Aqueous pBR322 plasmid was treated with FLASH (125 Gy/s) and conventional irradiation (0.05 Gy/s) under physioxia (4% O 2) and normoxia (21% O 2). Open circle DNA and linear DNA were detected by agarose gel electrophoresis, and the plasmid DNA damage was quantified with an established mathematical model to calculate the relative biological effect (RBE) of DNA damage. In some experiments, Samwirin A (SW) was applied to scavenge free radicals generated by ionizing radiation. Results:Under physioxia, the yields of DNA strand breakage induced by both FLASH and conventional irradiation had a dose-dependent manner. FLASH irradiation could significantly decrease radiation-induced linear DNA compared with conventional irradiation ( t=5.28, 5.79, 7.01, 7.66, P<0.05). However, when the aqueous plasmid was pretreated with SW, there was no difference of DNA strand breakage between FLASH and conventional irradiation ( P>0.05). Both of the yields of open circle DNA and linear DNA had no difference caused by FLASH and conventional radiotherapy at normoxia, but were significantly higher than those under physioxia. In addition, the yields of linear DNA and open circle DNA induced by FLASH irradiation per Gy were (2.78±0.03) and (1.85±0.17) times higher than those of conventional irradiation, respectively. Conclusions:FLASH irradiation attenuated radiation-induced DNA damage since a low production yield of free radical in comparison with conventional irradiation, and hence the FLASH effect was correlated with oxygen content.

Alveolar bone is an important anatomic basis for implant-supported denture restoration, and its different degrees of defects determine the choices of bone augmentation surgeries. Therefore, the reconstruction of alveolar bone defects is an important technology in the clinical practice of implant restoration. However, the final reconstructive effect of bone quality, bone quantity and bone morphology is affected by many factors. Clinicians need to master the standardized diagnosis and treatment principles and methods to improve the treatment effect and achieve the goal of both aesthetic and functional reconstruction of both jaws. Based on the current clinical experience of domestic experts and the relevant academic guidelines of foreign counterparts, this expert consensus systematically and comprehensively summarized the augmentation strategies of alveolar bone defects from two aspects: the classification of alveolar bone defects and the appropriate selection of bone augmentation surgeries. The following consensus are reached: alveolar bone defects can be divided into five types (Ⅰ-0, Ⅰ-Ⅰ, Ⅱ-0, Ⅱ-Ⅰ and Ⅱ-Ⅱ) according to the relationship between alveolar bone defects and the expected position of dental implants. A typeⅠ-0 bone defect is a bone defect on one side of the alveolar bone that does not exceed 50% of the expected implant length, and there is no obvious defect on the other side; guided bone regeneration with simultaneous implant implantation is preferred. Type Ⅰ-Ⅰ bone defects refer to bone defects on both sides of alveolar bone those do not exceed 50% of the expected implant length; the first choice is autologous bone block onlay grafting for bone increments with staged implant placement or transcrestal sinus floor elevation with simultaneous implant implantation. Type Ⅱ-0 bone defects show that the bone defect on one side of alveolar bone exceeds 50% of the expected implant length, and there’s no obvious defect on the other side; autologous bone block onlay grafting (thickness ≤ 4 mm) or alveolar ridge splitting (thickness > 4 mm) is preferred for bone augmentation with staged implant placement. Type Ⅱ-Ⅰ bone defects indicate that the bone plate defect on one side exceeds 50% of the expected implant length and the bone defect on the other side does not exceed 50% of the expected implant length; autologous bone block onlay grafting or tenting techniques is preferred for bone increments with staged implant implantation. Type Ⅱ-Ⅱ bone defects are bone plates on both sides of alveolar bone those exceed 50% of the expected implant length; guided bone regeneration with rigid mesh or maxillary sinus floor elevation or cortical autologous bone tenting is preferred for bone increments with staged implant implantation. This consensus will provide clinical physicians with appropriate augmentation strategies for alveolar bone defects.