Impact of the curriculum system on the quality of stomatology graduates: a multivariable analysis.

BACKGROUND: The curriculum system is a central component in achieving the goals and specifications of talent training schemes. However, problems and difficulties exist in curriculum provision due to a lack of curriculum system design logic. This study aimed to investigate the correlation between the university curriculum system and graduate quality and to reveal the design logic of the curriculum system. METHODS: A total of 699 stomatology graduates from a university in Zhejiang were selected as research subjects from 2015 to 2022. The students' curriculum system and graduate quality data were collected and classified. The graduate quality information contained (1) the National Board Dental Examination (NBDE) pass rate and score, (2) the postgraduate entrance rate and destination, and (3) the employment rate and work institution. Regression analysis was also conducted to assess the correlation between the curriculum system and graduate quality. RESULTS: Regression analysis revealed significant associations between general education, specialization, and stomatology X courses and NBDE score, postgraduate entrance rate and destination, and work institution. All courses except public elective courses had significant impacts on NBDE score. General basic, medical English, and employment guidance courses significantly influenced the postgraduate entrance rate and destination. Restricted elective and public elective courses had significant effects on employment rate and work institution. CONCLUSIONS: Increasing the quality of specialized and stomatology X courses in the curriculum system is beneficial for deepening graduates' expertise and enhancing their education. Moreover, English courses are suggested to be offered in the early stage to lay a better language foundation.

Force degradation of two orthodontic accessories analyzed in vivo and in vitro.

OBJECTIVE: To compare force degradation of elastomeric chains and NiTi coil springs in vivo and in vitro, and evaluate the effects of pre-stretched and reused elastomeric chains in the oral cavity during the time. METHODS: In the in vitro groups, 4-unit elastomeric chains and NiTi coil springs with an initial force of 200 g were placed in dry air and artificial saliva. The volunteers wore clear retainers which were used to hold the sample of 4-unit chains, pre-stretched 4-unit chains, and NiTi coil springs with the initial force of 200 g in the in vivo groups. After the first 4 weeks, 4-unit specimens were stretched to 200 g again for another 4 weeks in vivo. The force value and the percentage of force degradation were recorded at each measurement time interval in the in vivo and in vitro groups. RESULTS: The force degradation of elastomeric chains was greatest within the initial 4 hours, followed by a more stable phase after 1 week. The average force degradation of 4-unit elastomeric chains after 4 weeks was in vivo (64.8%) > artificial saliva (55.0%) > dry air (46.42%) (P < 0.05). The force degradation of NiTi coil springs in vivo (15.36%) or in artificial saliva (15.8%) was greater than in dry air (7.6%) (P < 0.05). NiTi coil springs presented a gentler force decay than elastomeric chains during the period (P < 0.05). In vivo, the force degradation of pre-stretched and reused elastomeric chains decreased less than the regular style(P < 0.05). CONCLUSION: The force degradation of the elastomeric chains and NiTi coil springs varied in different environments. NiTi coil springs presented a gentler force decay than elastomeric chains during the period. Orthodontists should consider the force degradation characteristics of orthodontic accessories in clinical practice.

Ipriflavone suppresses NLRP3 inflammasome activation in host response to biomaterials and promotes early bone healing.

AIM: Emerging studies have shown that immune response to biomaterial implants plays a central role in bone healing. Ipriflavone is clinically used for osteoporosis. However, the mechanism of ipriflavone in immune response to implants in early stages of osseointegration remains unclear. In this study, we aimed to investigate the potential role of ipriflavone in early bone healing process and uncover the underlying mechanism. MATERIALS AND METHODS: We carried out histological examination as well as analysis of proinflammatory cytokines and NLRP3 inflammasome activation in a tibial implantation mouse model with intra-peritoneal injection of ipriflavone. In addition, we explored the mechanism of ipriflavone in the regulation of NLRP3 inflammasome activation in macrophages. RESULTS: In vivo, ipriflavone ameliorated host inflammatory response related to NLRP3 inflammasome activation at implantation sites, characterized by reductions of inflammatory cell infiltration and proinflammatory cytokine interleukin-1ß levels. Ipriflavone treatment also showed beneficial effects on early osseointegration. Further investigations of the molecular mechanism showed that the suppression of NLRP3 inflammasome acts upstream of NLRP3 oligomerization through abrogating the production of reactive oxygen species. CONCLUSIONS: These results revealed an anti-inflammatory role of ipriflavone in NLRP3 inflammasome activation through improving mitochondrial function. This study provides a new strategy for the development of immune-regulated biomaterials and treatment options for NLRP3-related diseases.

Force degradation of orthodontic latex elastics analyzed in vivo and in vitro.

INTRODUCTION: The objective of this study was to evaluate the characteristics of force degradation of latex elastics of 10 kinds of elastics over 48 hours, both in vivo and in vitro. METHODS: For the in vivo study, 10 different kinds of elastics were randomly chosen for investigation: 1/8-inch (2 oz); 1/8-inch (3.5 oz); 3/16-inch (2 oz); 3/16-inch (3.5 oz); 1/4-inch (2 oz); 1/4-inch (3.5 oz); 5/16-inch (2 oz); 5/16-inch (3.5 oz); 3/8-inch (2 oz); and 3/8-inch (3.5 oz). Ten volunteers (aged 22-24 years) were selected to wear personalized clear retainers, which were made to hold the elastics in the mouth and stretched to a specific length. Control samples of 1/4-inch (2 oz) and 1/4-inch (3.5 oz) latex elastics were stretched to the same length and held in dry air conditions (temperature = 25°C) and in artificial saliva (temperature = 37°C, pH = 6.7). Force value and percentage of force degradation were estimated 10 times over a 48-hour period in both the in vivo and in vitro groups. A 1-way ANOVA and t test were used to identify statistical significance (P <0.05). RESULTS: The force degradation of the latex elastic in vivo is greater than in vitro. In the in vivo groups, during the first hour, the extension rate of all elastics decreased sharply about 13.16%-18.79%, then the rate of force degradation declined. The degradation of initial force was about 29.35%-39.94% after 48 hours. The extension range of 2.0-oz elastics reduced less than that of the 3.5-oz elastics in vivo. At the same time, with the same initial force, elastics with larger inner diameters decreased more slowly than the smaller elastics (P <0.05). CONCLUSIONS: The force degradation of latex elastic in vivo is much greater than that in both air and artificial saliva. In vivo, the force value of the orthodontic latex elastics decreased sharply in the first hour. The larger the inner diameter and smaller the setting force value were, the slower the force decay.

[Effect of genipin pretreatment on type â collagen mineralization].

OBJECTIVE: To investigate the effects of bio-crosslinker genipin pretreatment on type Ⅰ collagen mineralization. METHODS: Type Ⅰ collagen gels were prepared and pretreated with 0.5wt%genipin (experimental group) and deionized water (control group) for 2 h, respectively. The pretreated products were subjected to Fourier transform infrared spectroscopy (FT-IR). Reconstituted collagen fibrils were pretreated with genipin or deionized water for 2 h and were mineralized for 4 h. The collagen density and mineralization degree were examined with transmission electron microscopy (TEM) and analyzed with ImageJ software. Then scanning electron microscopy (SEM) and TEM were used to observe the mineralization of cross-linked demineralized dentin collagen. RESULTS: FT-IR spectrum showed that the genipin was crosslinked with collagen. TEM observation and ImageJ results showed that after 4 h mineralization, the mineralization effect of 0.5wt% genipin group was significantly better than that of the control group[(73.3±5.3)%vs.(7.4±3.5)%,P<0.01]. TEM and SEM observation showed that the mineralization rate of type Ⅰ collagen and demineralized dentin pretreated with genipin were significantly faster than that of the control group. CONCLUSIONS: The study demonstrates that 0.5 wt% concentration of genipin can significantly promote the mineralization of type Ⅰ collagen.

Characteristics and fate of orthodontic articles submitted for publication: An exploratory study of the American Journal of Orthodontics and Dentofacial Orthopedics.

INTRODUCTION: In this study, we aimed to give insight into the article review process by investigating the characteristics and the fate of manuscripts submitted to the American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO). METHODS: The following information was obtained for original articles submitted to the AJO-DO in 2008: (1) for rejected articles: the reasons for rejection and the journal of subsequent publication when applicable; (2) for accepted articles: the number of revisions and the time elapsed to publication; and (3) for all articles: study topic, study design, area of origin, and statistically significant findings. Findings were reported using descriptive statistics, the chi-square test for equality of proportions, and multiple regression where appropriate. Post-hoc pair-wise tests were checked against the Bonferroni correction to account for multiple testing. RESULTS: Of the 440 original articles submitted to AJO-DO in 2008, 116 (26%) were accepted and published an average of 21 months (SD, 5 months) after acceptance. Rejected articles totaled 324 (74%), with 137 (42%) finding subsequent publication an average of 22 months (SD, 11 months) after rejection by the AJO-DO. The top 3 reasons for rejection by the AJO-DO were (1) poor study design (59% of rejected articles), (2) outdated or unoriginal topic (42%), and (3) inappropriate for the AJO-DO's audience (27%). Manuscripts rejected for poor study design had the least success for subsequent publication, whereas those rejected as inappropriate for the AJO-DO had the highest rate of publication elsewhere. Area of origin was significantly associated with acceptance by the AJO-DO, with articles from United States and Canada most likely to be accepted (P < 0.01). Articles from countries with the lowest publication rate in the AJO-DO had the highest publication rate elsewhere. The presence of statistically significant findings was shown to be significantly associated with acceptance by the AJO-DO (P = 0.013) but not with publication elsewhere (P = 0.77). CONCLUSIONS: Rejection by the AJO-DO does not preclude publication elsewhere, although articles rejected for poor study design were least likely to be eventually published. Many publishable articles are rejected by the AJO-DO as inappropriate for its readership, and these were the most likely to find publication elsewhere. Articles with the highest chance of acceptance by the AJO-DO were those from the United States and Canada and those reporting statistically significant results.

Odontogenic MSC Heterogeneity: Challenges and Opportunities for Regenerative Medicine.

Cellular heterogeneity refers to the genetic and phenotypic differences among cells, which reflect their various fate choices, including viability, proliferation, self-renewal probability, and differentiation into different lineages. In recent years, research on the heterogeneity of mesenchymal stem cells has made some progress. Odontogenic mesenchymal stem cells share the characteristics of mesenchymal stem cells, namely, good accessibility, low immunogenicity and high stemness. In addition, they also exhibit the characteristics of vasculogenesis and neurogenesis, making them attractive for tissue engineering and regenerative medicine. However, the usage of mesenchymal stem cell subgroups differs in different diseases. Furthermore, because of the heterogeneity of odontogenic mesenchymal stem cells, their application in tissue regeneration and disease management is restricted. Findings related to the heterogeneity of odontogenic mesenchymal stem cells urgently need to be summarized, thus, we reviewed studies on odontogenic mesenchymal stem cells and their specific subpopulations, in order to provide indications for further research on the stem cell regenerative therapy.

The effect induced by alternated mechanical loading on Notch-1 in mandibular condylar cartilage of growing rabbits.

AIMS: The aim of our study is to investigate the effect induced by alternated mechanical loading on Notch-1 in mandibular condylar cartilage (MCC) of growing rabbits. METHODS: A total of 64 ten-day-old rabbits were randomly divided into two groups according to dietary hardness: normal diet group (pellet) and soft diet group (powder). In each group, the rabbits were further divided into four subgroups by feeding time: two weeks, four weeks, six weeks, and eight weeks. Animals would be injected 5-bromo-2'-deoxyuridine (BrdU) every day for one week before sacrificing. Histomorphometric analysis of MCC thickness was performed through haematoxylin and eosin (HE) staining. Immunochemical analysis was done to test BrdU and Notch-1. The quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were used to measure expression of Notch-1, Jagged-1, and Delta-like 1 (Dll-1). RESULTS: The thickness of MCC in the soft diet group was thinner than the one in normal diet group. Notch-1 was restricted in fibrous layer, proliferative layer, and hypertrophic layer. The expression of Notch-1 increased from two weeks to six weeks and then fell down. Notch-1 in normal diet group was higher than that in soft diet group in anterior part of MCC. The statistical differences of Notch-1 were shown at two, four, and six weeks (p < 0.05). The result of western blot and quantitative real-time PCR (qRT-PCR) showed the expression of Dll-1 and Jagged-1 rose from two to four weeks and started to decrease at four weeks. BrdU distributed in all layers of cartilage and subchondral bone. The number of BrdU-positive cells, which were less in soft diet group, was decreasing along with the experiment period. The significant difference was found at four, six, and eight weeks in anterior and posterior parts (p < 0.05). CONCLUSION: The structure and proliferation of MCC in rabbits were sensitive to dietary loading changes. The proper mechanical loading was essential for transduction of Notch signalling pathway and development of mandibular condylar cartilage. Cite this article: Bone Joint Res 2021;10(7):437-444.

[The effect of low-magnitude high-frequency loading on peri-implant bone healing and implant osseointegration in Beagle dogs].

PURPOSE: Low-magnitude, high-frequency（LMHF） loading has been confirmed to play an important role in bone healing. The present study aimed to evaluate the effect of LMHF loading applied directly to titanium dental implants on peri-implant bone healing and implant. METHODS: The mandibular premolars and molars were extracted from six male Beagle dogs. Three months post-extraction, six titanium implants (Aadva Standard Implant Narrow, 3.3 mm×8 mm) were inserted into the mandibular premolar and molar area (three implants per side) in each of the six dogs. In each animal, one side was randomly selected to undergo daily LMHF loading (experimental group), while the other side had no further intervention (control group). The loading was applied directly to the implant abutment using an individual jig and a custom-made loading device (8 µm,100 Hz). The implant stability quotient (ISQ) was tested every week. Three dogs were euthanized after 2 weeks, and three were euthanized after 8 weeks. Tissue samples were fixed and stained for micro-computed tomography(micro-CT) and histomorphometric analyses. The data were statistically analyzed using SPSS 13.0 software package. RESULTS: The experimental group had significantly increased peri-implant bone volume relative to tissue volume in region of interest 2 (100-500 µm) compared with the control group after 2 weeks of loading (P<0.05); however, there was no significant difference between the two groups after 8 weeks (P>0.05). The ISQ value and the micro-CT results did not differ between the two groups during the study period. CONCLUSIONS: LMHF loading positively influences peri-implant bone healing and osseointegration in the early healing period.

Differential expression of apoptosis-associated proteins in chondrocytes of the mandibular condyles of rabbits with anterior disk displacement.

Apoptosis is a potential contributor to anterior disk displacement (ADD) in temporomandibular joint disorders (TMD). The aim of this study was to investigate the expression of key protein regulators involved in apoptosis in the chondrocytes of mandibular condyles with induced ADD in experimental animals. ADD was surgically induced in the left temporomandibular joint (TMJ) of 15 rabbits without opening their bursas. A sham operation was performed on the right TMJ without displacing the disk forward. At the end of one, two, and four weeks after surgery, mandibular condyle samples were collected for protein extraction. The production of apoptosis-associated proteins Fas, capase-8, Bcl-2, and Bax was determined using Western blotting. The results indicate that the production of Fas and caspase-8 increased continuously after ADD. Meanwhile, the level of Bcl-2 decreased, and the production of Bax gradually increased following ADD. These results indicate that alterations in protein production of Fas, caspase-8, and the ratio of Bcl-2 to Bax are consistent with an increase of apoptotic activity in the chondrocytes, which may eventually lead to TMD.

[Expression of BMP/Smads in rabbit condylar cartilage during mandibular forward positioning].

OBJECTIVE: To identify the relationship between the expression of BMP/Smads in condylar cartilage and condylar growth modifications in rabbits during mandibular forward positioning. METHODS: Sixty male rabbits with 8 weeks of age were randomly divided into the experimental group (n=36) and control group (n=24). The mandibles of rabbits in the experimental groups were induced to forward position by a functional appliance. The rabbits in the experimental group and control group were sacrificed after 3 days and 1, 2, 4, 8, 12 weeks, respectively. The expression of BMP-2, Smad1/5, 4 and 6 in condylar cartilage was examined by immunohistochemical staining. RESULT: The expression of BMP-2, Smad1/5, 4 and 6 was mainly found in the chondrocytes from the transitional zone and hypertrophic zone, and was also found in the chondrocytes and osteoblasts of the mineralized zone. Compared with those of the age-matched controls, the positive signals for BMP-2, Smad1/5, 4 and 6 in the experimental animals were stronger at early stage (P<0.05), coinciding with the remodeling in condylar cartilage after functional appliance. CONCLUSION: The expression of BMP-2, Smad1/5, 4 and 6 is associated with the adaptive remodeling of the condylar cartilage after functional appliance.

Forward mandibular positioning enhances the expression of Ang-1 and Ang-2 in rabbit condylar chondrocytes.

Functional appliances correct dental malocclusion, partly by exerting an indirect mechanical stimulus on the condylar cartilage, initiating novel bone formation in the condyle. Angiopoietin is involved in the angiogenesis associated with novel bone formation. This study aimed to determine the expression of angiopoietin (Ang)­1 and ­2 following forward mandibular positioning (FMP) in the condylar chondrocytes of rabbits. Sixty rabbits (age, 8 weeks) were randomly allocated to the experimental and control groups (n=30 per group). In the experimental group, FMP was induced by a functional appliance. Five rabbits from the experimental group and the control group were sacrificed following 3 days and 1, 2, 4, 8 and 12 weeks, respectively. The right temporomandibular joints (TMJs) were collected and the expression of Ang­1 and -2 was evaluated by immunohistochemical staining. The expression of Ang-1 increased at day 3 and reached a peak at 2 weeks, whereas Ang­2 reached maximal expression 4 weeks after FMP. Subsequently, the expression of Ang­1 and ­2 gradually decreased. Thus, FMP enhanced the expression of Ang­1 and Ang­2 in condylar cartilage, which is related to angiogenesis in the process of endochondral ossification.

[The temporal and spatial expression of CBFalpha1 in rabbit condylar cartilage during forward mandibular positioning].

PURPOSE: To identify the relationship between the expression of Core binding factor alpha1 (Cbfalpha1) in condylar cartilage and condylar growth modifications in growing rabbits following forward positioning mandibles with functional appliance. METHODS: Sixty rabbits with age of 8 weeks were randomly divided into the experimental group (n=36) and control group (n=24). Rabbits in the experimental groups were induced to forward their mandibles by a functional appliance. The animals in the two groups were killed after 3 days and 1, 2, 4, 8 and 12 weeks, respectively. The temporal and spatial expression of Cbfalpha1 in condylar cartilage was examined by immunohistochemical staining and measured with Image Computer Analysis Software. Date was statistically analyzed by Student's t test and one-way ANOVA. RESULTS: The expression of Cbfalpha1 was mainly found in the chondrocytes from the transitive zone and hypertrophic zone, and was also observed in the chondrocytes and osteoblasts of the mineralized zone. Compared with those of the age-matched controls, the positive signals for Cbfalpha1 of each zone in the experimental animals were significantly stronger (P<0.05), and the highest expression of transitive zone, hypertrophic zone and mineralized zone was detected after 4 weeks of treatment (71.00+/-1.52, 50.00+/-0.75, 82.00+/-0.39). CONCLUSION: The pattern of Cbfalpha1 expression is concerned with the adaptive remodeling of the condylar cartilage after functional appliance.

[The morphology of the cells in the cartilage of rabbit mandibular condyle].

PURPOSE: To study the tissue layers and their function of the cartilage in mandibular condyle in rabbits. METHODS: Six adult Japanese white rabbits were subjected. Their temporomandibular joints were studied by immunohistochemistry for FGFR3 and PCNA, and in situ hybridization for aggrecan and collagen II mRNA expression, as well as ultrastructure. RESULTS: The upper proliferative cells did not express FGFR3, but the lower proliferative cells expressed FGFR3. Only few cells in the upper proliferative layer were PCNA positive, but all cells in the lower proliferative layer were positive for PCNA. No collagen II mRNA expression was found in the upper proliferative cell, but aggrecan and collagen II mRNA coexpressed in the lower proliferative layer. The cells in both layers were different in ultrastructure. CONCLUSION: The cartilage in mandibular condyle should have the 5 following tissue layer: fibrous layer, proliferative layer, transitional layer, cartilaginous layer and calcified cartilaginous layer. The cells in the proliferative layer are undifferentiated and the cells in the differentiated layer are prechondrocytes.

[Gene expression changes of cartilage matrix of condylar cartilage with anterior disc displacement].

OBJECTIVE: To study the gene expression changes in extracellular matrix of condylar cartilage following disc anterior displacement of rabbit TMJ. METHODS: The right sides of 28 joints in 40 rabbits were subjected to surgical operation of disc displacement. The condylar Collagen II and Aggrecan mRNA expression were detected by in situ hybridization. RESULTS: Collagen II and Aggrecan mRNA mainly expressed in the lower zone of condylar chondrocyte. Aggrecan mRNA decreased faster than collagen II following disc displacement, and adjusted to normal later. CONCLUSION: Anterior disc displacement leads to alteration of extracellurar matrix gene expression in the condylar chondrocyte, which means the start of remodeling.