In February 2024, the International Association of Dental Traumatology(IADT) and the Academy for Sports Dentistry(ASD) jointly released guidelines for the prevention of dental trauma. Drawing on clinical practice, these guidelines systematically summarize various prevention strategies and management methods for dental trauma with the aim of establishing standardized procedures for its prevention. This article offers a comprehensive analysis of the guidelines, aiming to assist clinicians in mastering and implementing the new version in order to effectively prevent dental trauma and reduce its potential negative effects.

Objective To measure the bone mass around the root of mandibular second molar and explore the limiting factors and related factors affecting the distal movement of mandibular second molar. Methods CBCT samples of patients before orthodontic treatment were collected. The alveolar bone width, root width, as well as the distance between root and bone cortex were measured at different levels. Distance between distal edge of crown and anterior edge of mandibular ascending branchwas also measured.The lateral cephalic film was generated for routine projection measurement. The correlation of the measurement index and the measurement level, patients age, gender and the shape of mandibular shape were also analyzed. Results Lingual distance and lingual distal distance of the root and bone cortex were the most limiting factors in value. The lingual distance was smaller in levels at the crown side than that in the apical level. There was a positive correlation between the distal distance and the lingual distal distance. There was no significant correlation between lingual distal distance and distance between distal edge of crown and anterior edge of mandibular ascending branch.There was no significant correlation between the lingual distal distance and the age, genderor the projection measures related to mandibular morphology. Conclusion The distance between the root and the lingual distal cortical bone may be the limiting factor for distal movement of mandibular molars. The distance between the mandibular second molar and the anterior edge of the mandibular ascending branch does not reflect the spatial situation of the distal movement of the molars. There is no significant correlation between the distal movement space of mandibular molars and the age, genderor mandibular morphology of patients.

Objective To evaluate the clinical efficacy of anterior maxillary segmental distraction osteogenesis and Le Fort Ⅰ Osteotomy on secondary maxillary hypoplasia in patients with cleft lip and palate. Methods Twenty-five patients with maxillary hypoplasia secondary to cleft lip and palate underwent surgery in maxillofacial surgical department of the Affiliated Stomatological Hospital of Nanjing Medical University were selected. Ten cases were treated using tooth-borne distractors for anterior maxillary distraction osteogenesis, and fifteen cases underwent Le Fort Ⅰ Osteotomy. Cone-beam CT, positive and lateral features, speech recording and nasopharyngeal fibroscope were taken one week before operation and one month after surgery. The clinical outcomes of the two methods and their influence on patients’ speech function were measured and compared using t-test. Results Both techniques effectively advanced the maxilla and significantly improved the patients’ profiles. Anterior maxillary segmental distraction osteogenesis, which was economical and minimally invasive, greater advanced the maxilla. However, the postoperative profile was better in patients undergoing Le Fort I osteotomy, with statistically significant differences (P<0.05). Neither technique significantly affected speech, but Le Fort Ⅰ osteotomy had a greater impact on palatopharyngeal anatomy, indicated by increased soft palate length (2.01±1.71)mm, reduced thickness (0.98±0.50) mm, and increased pharyngeal depth (3.06±1.35) mm, with statistically significant differences (P<0.05). Conclusion Anterior maxillary segmental distraction osteogenesis and orthognathic surgery are both effective methods for the treatment of secondary maxillary hypoplasia in cleft lip and palate patients. Anterior maxillary distraction osteogenesis has advantages over Le Fort I osteotomy in terms of economic benefits and its impact on the soft palate structure.

Objective To compare the effects of different crown materials on the stress distribution of dental implants by finite element method. Methods A three-dimensional finite element model of implant-supported crown restoration of the right mandibular first molar was established. Four kinds of crown restoration materials were used, including polymer infiltrated ceramic network Vita Enamic, resin nanoceramic Lava Ultimate, zirconia ceramic Cercon, and polyether-ether-ketone breCAM. A displacement load of 0.01 mm or 200 N was applied to the occlusal surface of the right mandibular first molar, and the analysis of reaction force, the maximum variability of shape, the maximum principal stress, the maximum equivalent stress was performed. Results The results of stress analysis under 0.01 mm displacement load showed that the maximum equivalent stress of Cercon was 937.30 MPa, and that of breCAM was 67.09 MPa. The stress concentration of crowns and implants was obvious. The maximum equivalent stress of the surrounding alveolar bone of Cercon was the highest(26.61 MPa), and that of breCAM was the lowest(3.87 MPa), which was about 1/7 of that of maximum group. The stress concentration range of resin-matrix ceramics and polyether-ether-ketone was relatively small, and the distribution was more uniform. When 200 N was applied, the maximum principal stress and the maximum equivalent stress distribution of the four models were similar, and the maximum variability of shape of breCAM was larger at the loading site. Conclusion Under the same displacement load, the stress concentration of polyether-ether-ketone and resin-matrix ceramics crown was lower than that of zirconia. There was no significant difference in stress concentration in the implant and surrounding alveolar bone among polyetheretherketone, resin-ceramic composite, and zirconia crown restorations under the same load. Further research on long-term durability of PEEK and resin-matrix ceramicsis needed through practical and clinical trials.

Objective To explore the occlusal contact designs in accordance with biomechanical principles in the All-on-4 immediate loading scheme of the edentulous maxilla with four kinds of framework materials. Methods Cone beam CT of an edentulous maxilla was selected. The cone beam CT data, crown, framework, abutment and implant data were used and the titanium, cobalt-chromium alloy, polyetheretherketone(PEEK) and resin framework materials were specified. The finite element models were divided into 4 groups, according to whether the anterior teeth or the cantilever had occlusal contact(AC group: both the anterior teeth and the cantilever were loaded;ANC group: load on the anterior teeth and no load on the cantilever; NAC group: no load on the anterior teeth and load on the cantilever;NANC group: no load on both the anterior teeth and the cantilever). The stress of cortical bone, implant and framework, the micromotion of implant and the deformation of framework were calculated and statistical analysis was then performed. Results Among the four types of framework materials, in terms of cortical bone peak stress, the NAC group had the highest value and the ANC group had the lowest. There was a statistical difference between the NAC group and the other three groups respectively(P<0.05). With the four framework materials, in terms of the peak stress of implant, the ANC group had the highest. When the framework material was PEEK or resin, there was a significant difference between the ANC group and the other three groups(P<0.05). The peak stress value of the framework compared, the NAC group had the highest peak stress and was significantly different from the other three groups(P<0.05). The ANC group had the lowest peak stress and was significantly different from the other three groups(P<0.05) when the framework material was titanium or cobalt-chromium alloy. If the framework material was PEEK or resin, there were no statistical differences between the four occlusal schemes. Comparing the peak micromotion of implant or the peak deformation of framework, the ANC/NAC group was significantly higher than the AC/NANC group(P<0.05). Among the different framework materials, titanium and cobalt-chromium alloy had higher peak stress of framework compared to PEEK and resin(P<0.05), with less stress transmitted to the cortical bone and implant(P<0.05). Conclusion ①In terms of occlusal contact design, when the All-on-4 immediate loading scheme is applied to the edentulous maxilla, the scheme that the anterior teeth loaded and the cantilever unloaded(ANC) is more conducive to the stress distribution of bone-implant interface. ②The application of load on both anterior teeth and cantilever(AC) or the absence of load on both anterior teeth and cantilever(NANC) is favourable for reducing the peak micromotion of implant and the peak deformation of framework. ③Among the four types of framework materials, titanium or cobalt-chromium alloy framework transmit less stress to the bone-implant interface than PEEK or resin framework.

Objective To explore the influence of extracting different types of mandibular mesially impacted third molars on the proximal contact strength(PCS) of adjacent teeth. Methods One hundred and ten cases of mandibular mesially impacted third molars were divided into high impacted group(40 cases), middle impacted group(40 cases) and low impacted group(30 cases). The PCS of the adjacent teeth of impacted teeth(between the mandibular second premolar L5 and the mandibular first molar L6, and between the mandibular first molar L6 and the mandibular second molar L7) were measured by high-precision dynamometer before and after operation, and the mean and standard deviation were statistically measured. The differences of PCS before and after extraction in each group were analyzed. Results Without considering the classification of mesial impacted teeth, extraction of mandibular third molars led to the decrease in PCS of L5/L6 and L6/L7. In the high-middle impacted groups, the extraction of mandibular third molars led to the decrease in PCS of L5/L6 and L6/L7, while in the low impacted group, there was no statistical difference between the changes in PCS of L5/L6 and L6/L7. Conclusion The extraction of high-middle mandibular mesially impacted third molars can significantly reduce the adjacent teeth’s PCS, but the extraction of low mandibular mesially impacted third molars has no significant effect on the adjacent teeth’s PCS.

Objective To evaluate the difference in accuracy of edentulous titanium implant frameworks fabricated using subtractive and additive-subtractive hybrid fabrication techniques. Methods Implant frameworks for a maxillary edentulous jaw model with 6 implants were designed using design software(EXOCAD) and exported as STL files. Five titanium implant frameworks were fabricated using subtractive manufacturing(SM) and additive-subtractive hybrid manufacturing(AM-SM) techniques, respectively. The 3D coordinates of the center points of the upper and lower planes of each implant abutment-prosthesis interface were obtained by using a coordinate measuring machine, and were “best-fit-aligned” to the original STL files in a specific software to obtain the linear deviation of the center points of the upper and lower planes of each interface in the x, y, and z axes, and the 3D deviation of each implant abutment-prosthesis interface. The centroid coordinates were imported into a reverse-measurement software(Geomagic Control X) and the angular deviation of each interface was calculated by creating “line features”. Statistical tests were performed using Kruskal-Wallis, ManneWhitney U, and one-way ANOVA(α=0.05). Results Between the differences in the implant abutment-prosthesis interfaces of the two fabrication methods, there was no statistical difference in the linear deviation on the x, y, and z axes of each interface and the 3D deviation and angular deviation of the interface(P>0.05), and the deviation values were within the clinically acceptable range. There were statistically significant differences in the 3D deviation between the different implant sites of the edentulous implant frameworks in both techniques. Conclusion Fabrication techniques do not affect the accuracy of the implant abutment-prosthesis interface. The accuracy of edentulous fixed implant frameworks fabricated by additive-subtractive hybrid fabrication techniques is within the clinically acceptable range. The implant site has a certain influence on the accuracy of the implant framework.

Objective To compare the clinical efficacy of a new bioceramic material iRoot BP Plus and a traditional pulp capping material calcium hydroxide for indirect pulp capping of deep primary molar caries. Methods A total of 104 deep primary molar caries in children who visited the Department of Pediatric Stomatology of Jing’an District Dental Hospital from July 2020 to June 2022 were selected as the research objects. They were randomly divided into two groups, which were treated with chemically cured calcium hydroxide Dycal and iRoot BP Plus for indirect pulp capping respectively. The patients were followed up regularly at 6 months and 12 months after the operation for clinical efficacy and imaging detection. The clinical efficacy and reparative dentin thickness of the two groups were compared. Results After 12 months of treatment, the success rate of treatment in the iRoot BP Plus group(96.23%) was higher than that in the Dycal group(82.35%), and the difference was statistically significant(χ²=5.289, P=0.021). The increase in reparative dentin thickness in the iRoot BP Plus group ((0.161±0.017), mm) was greater than that in the Dycal group ((0.143±0.023), mm), and the difference was not statistically significant(P>0.05). Conclusion The application of iRoot BP Plus in the indirect pulp capping of deep primary molar caries has good expectations, which can promote the formation of reparative dentin to a certain extent and improve the long-term success rate of the treatment fordeep primary molar caries.

Objective To compare the advantages and disadvantages of two fiber post removal methods, guide-supported and ultrasound assisted, for the removal of fiber posts in molars using in vitro experiments. Methods Twelve human extracted molars were randomly divided into a guide group and an ultrasound group for root canal treatment and fiber post restoration. The fiber posts were removed using digital guide and ultrasound instruments, respectively. The time of removal of fiber post and the degree of tooth tissue damage was compared between two groups. Results The operation time for each tooth in the ultrasound group was (11.14±1.62) minutes, while that in the guide group was (5.40±0.90) minutes. The ultrasound group had a significantly longer duration than the guide group, and the degree of crown damage to dental tissue was also significantly higher than that of the guide group. Conclusion Removing fiber posts with the support of guide can shorten clinical operation time, reduce technical sensitivity, and preserve remaining dental tissue as much as possible.

Objective To explore the effect of a formative assessment of mini clinical evaluation exercise (Mini-CEX) and direct observation of procedure skills (DOPS) on clinical internship teaching in periodontology. Methods Fifty-six undergraduates, who were interning in the Department of Periodontics, were selected and randomly divided into the control group and the teaching reform group. The traditional summative evaluation teaching mode was adopted in the control group, while the formative evaluation teaching methods of Mini-CEX and DOPS were used in the teaching reform group. The application effect was evaluated through the examination scores of two groups of students before and after the clinical practice, the Mini-CEX and DOPS scores of students in the teaching reform group before and after clinical practice, and a questionnaire survey. Results There was no significant difference in the scores of pre-clinical practice examination between the two groups (P>0.05). However, after the clinical practice, the scores of case report and clinical skills of the students in the teaching reform group were significantly higher than those in the control group (P<0.05). In addition, after the clinical practice, the scores of each item in the Mini CEX and DOPS of teaching reform group were significantly improved compared with those before clinical practice (P<0.05). The students and teachers were both satisfied with the formative assessment and its effectiveness. Conclusion The formative evaluation system of Mini-CEX and DOPS can effectively improve the quality of clinical internship teaching in periodontology, which has been widely recognized by students and teachers and is worthy of promoting and application.

The condylar movement trajectories in healthy people usually have relatively consistent characteristics, while the change of the trajectory of the temporomandibular condyle often indicates the occurrence of various oral diseases. An in-depth understanding of the condylar movement can help physicians diagnose and evaluate the efficacy of oral diseases. This article reviews the development of condylar motion tracing technique, and introduces the research progress and clinical application status of condylar motion tracing analysis in various oral diseases. At the same time, the limitations of the current condylar motion tracing technique and the prospect of future clinical application are proposed.

In recent years, peri-implantitis has garnered extensive attention as a complication of dental implant restoration due to its potential to incite inflammation, infection, bone loss, and ultimately implant failure. The control of biofilm plays a pivotal role in the treatment of peri-implantitis. Electrochemical treatment, as an adjuvant therapeutic approach in peri-implantitis management, has shown promising results in biofilm removal. This article reviews its effectiveness, mechanism, influencing factors and potential adverse reactions, in order to offer valuable guidance for future clinical practice and research design.

The imbalance of microbiota is related to various diseases in the human body, and the gut, as the largest microbial habitat in the human body, is closely related to the oral microbial environment. The oral microbiota can migrate to the intestinal mucosa with the digestive system. At the same time, microbial transmission from the gut to the mouth can also occur through interpersonal and community transmission. Microbial transmission between the mouth and intestines can shape or reshape the microbial ecosystem in the two habitats, ultimately regulating the pathogenesis of the disease. The dysbiosis of the oral-gut microbiota axis can have a significant impact on related diseases such as respiratory diseases. This article reviews the research status of the relationship between oral-gut microbes and respiratory diseases.

Chronic obstructive pulmonary disease is a pulmonary disease characterized by persistent, progressive airflow restriction and chronic inflammation, which is closely related to the occurrence and development of periodontitis. There are common risk factors and mutual influence between the two diseases. Based on existing studies, this paper discusses the correlation between periodontitis and chronic obstructive pulmonary disease and its influence on patients from the perspective of common molecular mechanisms, in order to provide theoretical guidance for optimizing clinical treatment.

There are two different types of computer-assisted implant placement techniques: static guide systems and dynamic navigation systems. There is greater accuracy and drastically reduced risk of perioperative/postoperative complications using the static guide compared to the freehand placement of implants. A zygoma drill guide can increase the precision of zygomatic implant placement. A combined bone- and mucosa-supported static guide can facilitate optimal zygomatic implant position. Using static guide systems for zygomatic implant placement faces several shortcomings. First, the use of static guides depends largely on the accurate positioning of surgical guides on the underlying tissue, and static guides do not have adequate underlying tissue to stabilize the surgical guides in a severely compromised defected maxilla. A second major concern with static guides is inadequate access for the drills, especially when using long twist drills with limitation in mouth opening. The dynamic navigation systems with actively tracked surgical drills have been proposed to provide real-time control of the drill position and achieve a precise zygomatic implant placement with minimal invasiveness, and challenges with static guides can be overcome. It is especially useful in patients with mouth opening limitation or extensive maxillary defect. The dynamic navigation technology has been recommended for placing more than one zygomatic implant on one side. Flapless placement of zygomatic implants guided by dynamic navigation has satisfactory safety and accuracy. Computer-assisted implant placement techniques can improve the accuracy and avoid complications of zygomatic implant placement for the reconstruction of severe maxillary atrophy and maxillary defects.