Genome-wide DNA methylation profile of human dental pulp stem cells during odontogenic differentiation.

OBJECTIVES: Human dental pulp stem cells (hDPSCs) is essential for dentin formation and regeneration, emerging evidence revealed that epigenetic regulation plays vital roles in odontogenic differentiation of hDPSCs. The purpose of this study was to explore the genome-wide DNA methylation changes during odontogenic differentiation of hDPSCs. DESIGN: hDPSCs were isolated from young healthy premolars and reduced representation bisulfite sequencing (RRBS) was taken to detect the genome-wide DNA methylation profile of hDPSCs during odontogenic differentiation. Genome-wide DNA methylation map, differentially methylated region (DMR) analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed. RESULTS: We found a totally different DNA methylation patterns during the odontogenic differentiation of hDPSCs. A total of 9309 differentially methylated genes (DMG) were identified. Bio-information analysis revealed that calcium signaling pathway, pathways in cancer, and HTLV-I infection signaling pathways may play potential roles in odontogenic differentiation of hDPSCs. NOTCH1, WNT7B, and AXIN2 proteins were related with calcium signaling pathway. CONCLUSIONS: This study revealed a comprehensive analysis of global DNA methylation profiles in odontogeinc differentiation of hDPSCs and provided several possible underlying signaling pathways and candidate genes that may regulate the odontogenic differentiation of hDPSCs.

[Accuracy evaluation of static guided implant placement using an intraoral scan method].

PURPOSE: To evaluate the accuracy of static guided implant placement with intraoral scanning technology and to analyze the influencing factors of guided surgery. METHODS: Totally 27 cases were included in this retrospective study. The implant designs were made in 3Shape Implant Studio and then guided implant surgeries were performed with CAD-CAM templates. Postoperative implant positions were detected with an intraoral scanner (3Shape TRIOS) and deviation of implantation was evaluated using established CAD/CAM based evaluation method. SAS 9.4 software package was used for data analysis. RESULTS: The mean deviation of entrance point and apical point was (1.182±0.609) mm and (1.658±0.741) mm, respectively. Angular deviation was (5.712±3.347)°. Implant quadrant, location of the implant site, guidance degree, supporting type and implant size influenced direction deviation, while angular deviation was mainly affected by guidance degree and number of missing teeth. CONCLUSIONS: Accuracy of static guided implant placement can be influenced by many factors. More research is needed to improve the accuracy of static guided implantation.

Advances on Hydrogels for Oral Science Research.

Hydrogels are biocompatible polymer systems, which have become a hotspot in biomedical research. As hydrogels mimic the structure of natural extracellular matrices, they are considered as good scaffold materials in the tissue engineering area for repairing dental pulp and periodontal damages. Combined with different kinds of stem cells and growth factors, various hydrogel complexes have played an optimistic role in endodontic and periodontal tissue engineering studies. Further, hydrogels exhibit biological effects in response to external stimuli, which results in hydrogels having a promising application in local drug delivery. This review summarized the advances of hydrogels in oral science research, in the hopes of providing a reference for future applications.

[Nonradiological methods for implant surgical guide accuracy measurement].

PURPOSE: To evaluate the accuracy of static computer-navigated implantation with surgical guides, based on a non-radiological method. Traditional measurements with a second cone-beam CT (CBCT) were applied to verify the accuracy. METHODS: A total of thirty template-guided implantations were designed and performed on 15 resin models. Two paralleled bone-level implants were planned in the edentulous space of each model, between which the distance was 4 mm. Postoperative implant positions were detected with both CAD/CAM-based measurements applying an intraoral scanner (3Shape TRIOS) and traditional ways via CBCT. Both methods were conducted with a CAD quality-control, reverse engineering software, Geomagic Studio 2013, comparing the positions with the virtual ones. Statistical analysis was processed with SPSS 23.0 software package. RESULTS: Measurements using CBCT (control group) showed a trend toward greater deviations when the results were directly compared(P<0.05). In the CAD/CAM-based evaluation of the 30 samples, the mean deviation of the insertion axis from the planned implant axis was 1.134°. The mean deviations of the implant shoulders in the horizontal direction and at the implant apices were 0.447 mm and 0.557 mm, respectively. No significant difference was observed when measuring distance deviation with the two assessment ways. CONCLUSIONS: Compared with evaluation based on radiology, CAD/CAM based evaluation system is able to evaluate implant accuracy precisely, effectively reduce radiological exposure of patients, being suitable for clinical evaluation.

[Study on cushioning and energy absorption of sports mouthguard].

PURPOSE: Using impact test to study cushioning and energy absorption of sports mouthguard of different thickness, material and combination. METHODS: According to the thickness, material and combination, the mouthguards were divided into 7 groups with 6 testing pieces in each group. A pendulum device was used to apply impact energy to the mouthguard and dentition model, and the magnitude of the impact energy was measured by changing the release height of the pendulum. The force sensor and the laser vibrometer were respectively connected to the data acquisition and signal analyzer to obtain the incident speed, rebound speed, maximum collision force, collision start time and collision end time of the hammer head. Collision time, energy absorption and energy absorption ratio of the mouthguard were calculated, which reflected different mouthguard cushioning and energy absorption characteristics. One-way analysis of variance and t test in SPSS 22.0 software package was used to analyze the difference between different groups. RESULTS: No matter what type of mouthguard was worn by the dentition model, the impact force was significantly reduced than without mouthguards. At the same height, there was significant difference between the average maximum collision force and the average collision time among soft mouthguards with thicknesses of 2, 3, 4, and 5 mm(P<0.05); among which the average maximum collision force of the 5 mm was the smallest and the average collision time was the shortest. There was no significant difference in the average energy absorption and the average energy absorption ratio among these 4 groups. There was significant difference in the average maximum collision force, average collision time, average energy absorption and average energy absorption ratio between the two groups of mouthguards with the same thickness of splints and different materials(P<0.05). Among them, the average maximum impact force of the 4 mm soft mouthguard was smaller and the average collision time was longer. CONCLUSIONS: Wearing sports mouthguard can reduce the risk of tooth fracture during collision. Soft mouthguard has the best cushioning performance and it is positively related to thickness. Locally strengthening hard materials can enhance energy absorption and provide better protection.

[Study of the timing of tooth movement after repair of alveolar bone defects by rabbit BMSCs combined with beta-TCP].

PURPOSE: To investigate the effect of tooth movement at different time after repair of alveolar bone defects with tissue engineering bone constructed by rabbit bone marrow mesenchymal stem cells (BMSCs) and beta-tricalcium phosphate (ß-TCP). METHODS: Alveolar bone defect (6 mm×4 mm×8 mm) was made on the right side of 40 New Zealand rabbits, which was filled with tissue engineering bone constructed by BMSCs and ß-TCP as experimental sides. Tooth extraction on the other side was performed as control. The mandibular second molars in both sides were moved mesially 2, 4, 8 and 12 weeks after surgery. The specimens were taken 4 weeks after exertion. The distance of mandibular second molar moved was measured. The periodontal tissues were observed after H-E staining. TRAP staining was performed and osteoclasts were counted in the periodontal tissues on the pressure side. BMP-2 immunohistochemical staining was used to observe the average optical density of periodontal tissue on tension side. The results were analyzed with SAS 8.0 software package. RESULTS: The distance of tooth movement, the amount of TRAP positive cells and the optical density of BMP-2 in the experimental side of the 2-week and 4-week groups were all significantly lower than those in the control side, while there was no significant difference between the 8-week and 12-week groups. CONCLUSIONS: Eight weeks after repair of alveolar bone defect with rabbit BMSCs and ß-TCP is an appropriate time for orthodontic tooth movement.

[Study on energy absorption of mouthguard splints by impact test].

PURPOSE: Using impact test to study energy absorption ability of mouthguard splints of different thickness and materials. METHODS: In this experiment, group 1 was BIOPLAST 5 mm splint, group 2 was BIOPLAST 4 mm splint, group 3 was BIOPLAST 3 mm splint，group 4 was BIOPLAST 2 mm splint and group 7 was BIOPLAST 1 mm splint. Group 5 was ERKOLOC-PRO 2 mm splint, group 6 was DURAN 2 mm splint. Mouthguard splints were clashed by impact head from different heights. Digital Image Correlation System was used to record the process of the test. Images were transferred to data processing software, to analyze incident speed, incident depth and rebound height of the impact head. Absorbed energy and energy absorption ratio were calculated to analyze energy absorption ability of mouthguard splints of different thickness and materials. The data were analyzed using SPSS 22.0 software package for one-way analysis of variance and LSD. RESULTS: The higher impact head fell, the larger energy absorption ratio was. There was significant difference among group 1, 2, 3, 4, 7 in average energy absorption ratio（P<0.05）, and group 7 was the largest. There was significant difference among group 4, 5, 6 in average energy absorption ratio（P<0.05）, among which group 4 and group 5 were larger. CONCLUSIONS: 3 mm splint is good enough to be used to make mouthguard, which is also thinner and more comfortable. Splint of soft material is more suitable for mouthguard than splint of hard material.

[Effects of dimethylamine tetracycline combined with tea polyphenols on the levels of IL-1ß and IL-17F in patients with early peri-implant soft tissue inflammation].

PURPOSE: Using impact test to study energy absorption ability of mouthguard splints of different thickness and materials. METHODS: In this experiment, group 1 was BIOPLAST 5 mm splint, group 2 was BIOPLAST 4 mm splint, group 3 was BIOPLAST 3 mm splint，group 4 was BIOPLAST 2 mm splint and group 7 was BIOPLAST 1 mm splint. Group 5 was ERKOLOC-PRO 2 mm splint, group 6 was DURAN 2 mm splint. Mouthguard splints were clashed by impact head from different heights. Digital Image Correlation System was used to record the process of the test. Images were transferred to data processing software, to analyze incident speed, incident depth and rebound height of the impact head. Absorbed energy and energy absorption ratio were calculated to analyze energy absorption ability of mouthguard splints of different thickness and materials. The data were analyzed using SPSS 22.0 software package for one-way analysis of variance and LSD. RESULTS: The higher impact head fell, the larger energy absorption ratio was. There was significant difference among group 1, 2, 3, 4, 7 in average energy absorption ratio（P<0.05）, and group 7 was the largest. There was significant difference among group 4, 5, 6 in average energy absorption ratio（P<0.05）, among which group 4 and group 5 were larger. CONCLUSIONS: 3 mm splint is good enough to be used to make mouthguard, which is also thinner and more comfortable. Splint of soft material is more suitable for mouthguard than splint of hard material.

Agreement of young adults and orthodontists on dental aesthetics & influencing factors of self-perceived aesthetics.

BACKGROUND: The aim of this study is to assess the agreement between orthodontist's and Chinese young adult's self-perceived aesthetics, the normative treatment need based on the Index of Orthodontic Treatment Need (IOTN), and the main factors affecting the self-perceived aesthetics. METHODS: A random sample of 348 Chinese young adults (116 males and 232 females) aged 17-24 years were recruited in this study. Two orthodontists were involved in rating the cases. Orthodontic treatment need was assessed according to the Index of Orthodontic Treatment Need, including Aesthetic components and Dental Health Components (AC and DHC). Personality traits were assessed according to Eysenck Personality Questionnaire (EPQ). Cohen's kappa test was used to assess the agreement, and spearman's correlation coefficient was used to analyze the association among all variables. RESULTS: A statistically significant level of agreement was observed between young adult's perception and orthodontist's perception in IOTN (kappa = 0.14). A positive relationship (p < 0.001)existed between the young adult's AC and the orthodontist' s AC (r = 0.275), and between the young adult' s AC and the normative need DHC (r = 0.195). The orthodontist's AC was strongly related to the normative need (r = 0.743, p < 0.001). Association between the young adult's AC and gender and EPQ-E were also observed. CONCLUSIONS: Young adults tend to be less critical in assessing orthodontic treatment needs than orthodontists. The orthodontist's AC reflecting subjective treatment need is strongly connected to the normative need. The adult's perception of aesthetic component is affected by factors such as gender and personality traits.

Effect of personality on oral health-related quality of life in undergraduates.

OBJECTIVES: To evaluate the effects of personality traits and other variables on oral health-related quality of life (OHRQoL) of Chinese undergraduates aged 17 to 24 years with no history of orthodontic treatment. MATERIALS AND METHODS: A total of 443 undergraduate students aged 17 to 24 years were selected and completed a two-section questionnaire: the Eysenck Personality Questionnaire Short Scale Chinese version and the Oral Health Impact Profile-14 Chinese version (OHIP-14). Malocclusion severity was assessed via clinical examination using the dental health component (DHC) and esthetic component of the Index of Orthodontic Treatment Need (IOTN). Severe dentofacial deformities that required orthognathic surgery were excluded. RESULTS: The total and all dichotomized OHIP-14 dimensions correlated closely with the neuroticism personality traits ( P < .001). The total and some subscales of OHIP-14 were related with psychoticism. Women had higher OHIP-14 scores than men, especially in the normal occlusion group. Nevertheless, men with more severe malocclusions had higher scores that were similar to those of women. OHRQoL was significantly different between the major of dentistry and other majors. CONCLUSIONS: Personality affects comprehensive OHRQoL, and the most significant predictor is neuroticism. Female young adults have worse OHRQoL than male young adults, especially among those with mild malocclusion.