Vertical root fracture (VRF) is different from odontoclasis caused by trauma or injury. VRF is defined as a complete or incomplete fracture of roots caused by long-term and persistent stimulus, such as excessive forces from mastication or occlusion, improper tooth anatomy, and tooth treatment accident. Early diagnosis of VRF is essential to prevent the absorption of alveolar bone, thereby improving prognosis. Radiographic examination is the most common and effective evaluation method for VRF. Cone beam computed tomography can provide three-dimensional information for fracture details, which are more precise than traditional periapical films. In this paper, we present the radiographic features, differential diagnosis, and new treatment techniques for VRF.

Objective  This research aimed to fabricate a hydroxyapatite (HA)-chitosan scaffold via simulated body fluid (SBF) biomimetic mineralization and determine how mineralization time affects scaffold construction and cell compatibility. Methods  The HA-chitosan scaffolds were fabricated by freeze-drying technique and then subjected to precalcification, also known as alternative soaking method. Afterward, precalcificated scaffolds were placed into the SBF to conduct the mineralization process. Mineralization time was set at 7, 14, and 21 days, corresponding to three experimental groups. Pure chitosan scaffolds acted as the control group, and the physical and chemical properties of the four groups were tested. Osteogenicinduced adipose-derived stem cells (ADSCs) were seeded into the scaffolds to investigate the scaffolds’ cell compatibility. Results  The mineral substance of the 14-day group exhibited a uniform distribution. The crystal composition of the mineral substance suited the HA’s features. The compressive elastic modulus increased along with the extension of mineralization time. The 21-day group showed a statistically significant increase in compressive elastic modulus compared with the control group (P<0.05). The cell proliferation level of the 14-day group was significantly the highest among the three experimental groups (P<0.05). The calcium ion and the typeⅠcollagen had the highest secretion amount when the cells were seeded into the 14-day group. Conclusion  The SBF biomimetic mineralization method can be used to fabricate HA-chitosan bone-tissue engineering scaffolds. The biological compatibility, as well as the chemical and physical properties, reached the optimum levels at day 14.

Objective  This study aims to investigate the regulatory effects of calcitonin gene-related peptide (CGRP) on Nod-like receptor protein 3 (NLRP3) and interleukin-1β (IL-1β) to promote osteoblast differentiation. Methods  Different concentrations of CGRP (0, 10, 30, 100 ng•mL-1) were added to mouse osteoblasts in vitro. The mRNA and protein expression levels of both NLRP3 and IL-1β were examined using Real-time polymerase chain reaction and Western blot, respectively. Moreover, the concentrations of IL-1β protein and intracellular reactive oxygen species (ROS) were detected using enzyme-linked immunosorbent assay and flow cytometry, respectively. The osteogenic differentiation of mouse osteoblasts was identified through alizarin red staining. Results  The protein and mRNA expression levels of both NLRP3 and IL-1βsignificantly decreased (P<0.05) with increasing CGRP concentration. Moreover, the contents of intracellular ROS gradually decreased (P<0.05). The osteogenic differentiation of the osteoblasts was more enhanced in the group treated with 100 ng•mL-1 CGRP than in the empty group (0 ng•mL-1CGRP). Conclusion  CGRP promotes osteoblast differentiation by inhibiting the expression of inflammatory factors.

Objective  This research aimed to observe the expression of heat shock protein 27 (HSP27) in human gingival fibroblasts (HGFs) cell injury induced by different concentrations of cigarette smoke extract (CSE). Methods  The third to eighth generations of cultured HGFs were treated with serially diluted CSE of different concentrations (0, 2.5%, 5.0%, 12.5%, 25.0%, 50.0%). Wound-healing assay was performed to determine the migration of HGFs, and Western blot was used to determine the expression of HSP27. Results  The migration capability of HGFs weakened with the increase of CSE concentration. HSP27 expression was negative in normal HGFs but positive in CSE-intervened HGFs in a concentration-dependent manner. Conclusion  HSP27 concentration increased in the CSE-induced injury of HGFs. This finding suggests that HSP27 plays an important role in CSE-induced epithelial injury.

Objective  This research aimed to detect the expression levels of ffh gene in Streptococcus mutans (S. mutans) UA159 under different pH conditions, analyze the effect of pH on the expression of ffh gene in S. mutans, and identify the factors regulating the ffh gene expression. Methods  Samples of S. mutans were collected at different growth stages (4 h, 18 h) and pH values (pH 4.0-7.0). Fluorescence quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the relative mRNA expression and trend of the target gene ffh in S. mutans at different growth stages and pH values. Results  qRT-PCR results showed that the ffh gene expression decreased along with pH at 4 h, but the expression increased with decreasing pH at 18 h. Under the same pH conditions, the ffh gene expression was significantly different between 4 h and 18 h (P<0.05). Conclusion  Growth stage and pH value influenced the ffh gene expression in S. mutans.

Objective  To explore the possible relationship between recurrent aphthous ulcer (RAU) and single nucleotide polymorphism (SNP) of transforming growth factor-β1 (TGF-β1)-509T/C and interleukin-10 (IL-10)-1082A/G sites. Methods  A total of 138 RAU patients were recruited for this study. The control group consisted of 124 subjects. TGF-β1-509T/C and IL-10-1082A/G sites were detected by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) and sequence specific primer-polymerase chain reaction (SSP-PCR). Relative risk ratios were estimated by odds ratios (OR) and 95% confidence interval (95%CI). Results  Significant differences were found in the genotype frequencies or allele frequencies of TGF-β1-509T/C and IL-10-1082A/G sites between the RAU patients and controls (P<0.05). CT genotype (OR=1.231, 95%CI=0.702–2.160), TT genotype (OR=2.482, 95%CI=1.250–4.927), and T allele (OR=1.465, 95%CI=1.036–2.074) at the TGF-β1-509 site exhibited high risks. AG genotype (OR=1.391, 95%CI=0.808–2.396), GG genotype (OR=4.165, 95%CI=1.944–8.924), and G allele (OR=2.134, 95%CI=1.474–3.089) at the IL-10-1082A/G site also showed high risks. Conclusion  TGF-β1-509T/C and IL-10-1082A/G sites are associated with the risk of RAU. The TGF-β1 gene-509T allele and IL-10 gene-1082G allele may serve as genetic determinants for RAU.

Objective  This study aims to synthesize MT01 (a kind of oligodeoxynucleotides) and N-isopropylacrylamidemodified polyethylenimines (PEN) complexes (MT01/PEN) as well as to investigate the effect of the complexes on the expression of osteoprotegerin (OPG) and the receptor activator of nuclear factor κB ligand (RANKL) in the human osteoblast-like cell line MG63. Methods  MG63 cells were transfected by MT01/PEN complexes formed with three different mass ratios (1∶2, 1∶4, 1∶6) of MT01 to PEN. MT01 and MT01-s were used as positive control. Enzyme-linked immunosorbent assay and real-time polymerase chain reaction were performed to estimate the amount of OPG and RANKL released into the culture media and in MG63 at 24, 48, 72 h. Results  MG63 responded to the MT01/PEN complexes by significantly upregulating the OPG on the protein and mRNA levels (P<0.05). The protein and mRNA levels of RANKL were lower in most of the groups with complexes, and the OPG/RANKL ratio were higher (P<0.05). MG63 were affected by the MT01/PEN complexes with different mass ratios, particularly when the ratio was 1∶6. Conclusion  MT01 can enhance the promotion of ossification by establishing the delivery system with PEN.

Objective  The effect of Kou Yan Qing Ke Li on the prevention and treatment of radiation-induced oral mucositis was investigated in patients with nasopharyngeal carcinoma. Methods  Sixty patients with nasopharyngeal carcinoma to be treated with radiotherapy were randomized into two groups: the experimental and control groups. The experimental group (30 patients) was treated with Kou Yan Qing Ke Li during the full course of radiotherapy. The control group (30 patients) rinsed their mouths in the same way with mouth washes containing 0.9% sodium chloride injection, lidocaine, dexamethasone, vitamin B12 and B2 gargle liquid mixture, when grade 2 and above radiation-induced oral mucositis appeared in the process of radiation. Radiation-induced oral mucositis was assessed according to the radiation therapy oncology group criteria. The time of occurrence and degree of pain grade were compared between the two groups. Results  The first onset of oral mucositis in the experimental group (12.40 d±2.74 d) was later than that in the control group (9.46 d ± 1.39 d) (t=5.241, P<0.001), whereas the grade of pain and acute radiation mucositis was lower in the experimental group than that in the control group. The difference was statistically significant. Conclusion  Kou Yan Qing Ke Li could delay the time of occurrence of radiation-induced oral mucositis, reduce the severity of radiation stomatitis, alleviate the pain of patients, improve the clinical symptoms of patients, and effectively prevent and treat radiation-induced oral mucositis in patients with nasopharyngeal carcinoma

Objective  The study investigated the epidemiology of Filifactor alocis (F. alocis) in subgingival plaque samples from subjects with different periodontal statuses. The relationship between the prevalence of F. alocis and clinical periodontal parameters was also analyzed. Methods  Subgingival plaque samples and periodontal data were collected from 68 healthy sites (H groups) in 17 healthy subjects, 64 healthy (G-H group) and 76 diseased sites (G-D group) in 19 patients with chronic gingivitis, and 36 healthy (P-H group) and 56 diseased sites (P-D group) in 14 patients with chronic periodontitis. The plaque samples were analyzed by polymerase chain reaction, and possible correlations between the F. alocis detection rate and the bleeding index, probing depth, or clinical attachment level were determined. Results  The detection levels of F. alocis increased in both healthy and diseased groups. The lowest level at 30.88% (21/68) was noted in the H group, whereas the highest level at 91.07% (51/56) was obtained from the P-D group. A significant correlation was found between the F. alocis detection levels and periodontal disease condition (P<0.000 1). Further analyses showed that a significant correlation also existed between the detection level of F. alocis and the abnormal clinical periodontal parameters, namely, bleeding index, probing depth, and clinical attachment loss. The odds ratios were 5.26, 8.85, and 11.65, respectively. Conclusion  F. alocis was found at increased levels in subjects with periodontal disease. The presence of F. alocis increases the risk of sites with abnormal clinical periodontal parameters.

Objective  This study aims to determine the effect of fluoride concentration on the corrosion behavior of cobaltchromium alloy fabricated by two different technology processes in a simulated oral environment. Methods  A total of 15 specimens were employed with selective laser melting (SLM) and another 15 for traditional casting (Cast) in cobalt-chromium alloy powders and blocks with the same material composition. The corrosion behavior of the specimens was studied by potentiodynamic polarization test under different oral environments with varying solubilities of fluorine (0, 0.05%, and 0.20% for each) in acid artificial saliva (pH=5.0). The specimens were soaked in fluorine for 24 h, and the surface microstructure was observed under a field emission scanning electron microscope after immersing the specimens in the test solution at constant temperature. Results  The corrosion potential (Ecorr) value of the cobalt-chromium alloy cast decreased with increasing fluoride concentration in acidic artificial saliva. The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes changed significantly when the fluoride concentration was 0.20% (P<0.05). The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes exhibited a statistically significant difference. The Icorr value of the cobalt-chromium alloy cast was higher than that in the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P<0.05). The Ecorr and Rp values of the cobalt-chromium alloy cast were lower than those of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P<0.05). Conclusion  Fluoride ions adversely affected the corrosion resistance of the cobalt-chromium alloy fabricated by two different technology processes. The corrosion resistance of the cobalt-chromium alloy cast was worse than that of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20%.

Objective  To evaluate the effects of thermal and mechanical cycling on the metal-ceramic bond strength of machine-milled Ti2448 alloy and commercial pure titanium (cp Ti). Methods  Ceramic-cp Ti (n=30) specimens and ceramic-Ti2448 combinations (n=30) were prepared in accordance with ISO 9693. The specimens from each metal-ceramic combination were randomly divided into three subgroups. In group A or the control group, the specimens were only stored in distilled water for 24 h at 37 °C; in groups B and C, the specimens were subjected to 3 000 cycles of thermal cycling between 5 and 55 °C for a dwell time of 60 s and to mechanical cycling of 20 000 or 40 000 cycles with 50 N load and 4 Hz in distilled water at 37 °C. A crack initiation test was performed using a universal testing machine in accordance with ISO 9693. Failure types at the metal-ceramic interface and the morphological and elemental composition of this interface were analyzed using a scanning electron microscope and an energy dispersive spectrometer. Statistical analysis was performed via two-way ANOVA and Tukey’s adjustment test (α=0.05). Results  The bond strength of the ceramic-Ti2448 combination was significantly higher than that of the ceramic-cp Ti combination regardless of fatigue conditions (44.86 MPa±1.75 MPa and 29.21 MPa±2.20 MPa for Ti2448 and cp Ti, respectively; P<0.01). The mean bond strengths of ceramic-cp Ti and ceramic-Ti2448 combinations in group C were significantly lower than that of group A (P<0.01). Although ceramic-cp Ti combination failed adhesively at the metal-ceramic interface without the ceramic on the substrate surface, Ti2448 frameworks exhibited cohesive failure; as a result, large amounts of residual porcelain were retained on the specimens. Conclusion  The metal-ceramic bond strength of cp Ti and Ti2448 is decreased by thermal and mechanical cycling.

Objective  This study aimed to explore the differences of membrane thickness and pressure on the paranasal sinus membrane in goats and analyze their causes. The results can provide theoretical basis and guidance for the issues of the maxillary sinus floor augmentation related to the membrane. Methods  The membrane was cut into two sizes from every sinus membrane. The membrane was fixed in formalin to obtain tissue specimens for the membrane thickness study and pressure study. The correlation between the two parameters was then analyzed, and appropriate statistical methods and software were selected. Results  The top of maxillary sinus, the bottom of maxillary sinus and the frontal sinus membrane thickness were (410.03±65.97), (461.33±91.37), (216.90±46.47) μm. The pressure were (260.08±80.12), (306.90±94.37), (121.72±31.72) kPa. The mean differences of the membrane thickness between the top of the maxillary sinus and the frontal sinus, bottom and frontal, and top and bottom were statistically significant (P<0.05). The mean differences in membrane pressure were also statistically significant (P<0.05). Conclusion  The membrane thickness and pressure of the top and bottom of the maxillary sinus are higher than those of the frontal sinus membrane. However, the thickness and pressure of the bottom membrane are slightly higher than those of the top membrane. Pressure and membrane thickness are positively correlated in the sinus membrane.

Objective  This study investigated the influence of different designs and porcelain/glaze firing on the marginal and internal fit of three kinds of computer aided design/computer aided manufacturing (CAD/CAM) zirconia ceramic implantsupported crowns. Methods  Three groups of zirconia ceramic implant-supported crowns with different designs were produced from copings by using a Cercon CAD/CAM system (n=8). The first two groups comprised double-layer crowns (zirconia coping+veneer) with regular (Group A) and full circumferential zirconia-collar marginal designs (Group B). The third group was composed of anatomic single-layer zirconia crowns without cores (Group C). Initially, the marginal and internal gaps of the copings and crowns were individually replicated by light-body silicon and then measured by micro-computed tomography scanning before and after porcelain/glaze firing. Five measurements were employed: vertical marginal gap (MG); horizontal marginal discrepancy (HMD); chamfer area (CA); axial wall (AW); and axial-occlusal transition area (AOT). Statistical analyses were performed by SPSS 17.0. Results  HMD measurements in Group A were statistically higher than those in Groups B and C (P<0.05), regardless of whether the values were obtained before or after porcelain/glaze firing. By contrast, the HMD measurements in Groups B and C showed no significant difference (P>0.05). Moreover, no differences were noted in MG, CA, AW, and AOT among the three groups (P>0.05). All the measurements in the three groups showed no significant change after porcelain/glaze firing (P>0.05), except for MG in Group A, which significantly decreased (P< 0.05). Conclusion  The marginal fits of the double-layer crowns with full circumferential zirconia-collar and the anatomic single-layer zirconia crowns were superior to that of the double-layer crowns with regular margins. The MG of the crowns with regular margins was obviously influenced by porcelain firing.

Objective  This study aims to construct a chitosan (CS)–polycaprolactone (PCL)–hydroxyapatite (HA) composite biomimetic scaffold to replace condyle and to explore the tissue engineering applications of condylar. Methods  A resin mold of the mandibular condyle was prepared by using rapid prototyping techniques. A mandibular condylar integrated biomimetic scaffold model was prepared by solution casting-ice Lek. PCL and CS were mixed at a ratio of 4︰1. HA at quality ratios of 40%, 50%, 60%, and 70% was added to groups a, b, c, and d, respectively. The microscopic morphology, porosity, infrared spectra, X-ray diffraction pattern, and mechanical properties of the scaffold were observed. Results The scaffold that includes both upper and lower parts displayed the same features (i.e., shape, yellow-white appearance, and hard texture) as the mandibular condyle. Scanning electron microscopy showed that the composite scaffold had a 3D network spatial structure, 70%–85% porosity, and 10–200 μm pore size. Infrared spectra showed that the peak intensity reduced with decreasing HA content. X-ray diffraction showed that the diffraction peak decreased with increasing HA content. Suitable tensile and compressive and flexural strength were discovered in the presence of 50% HA. Conclusion  The scaffold prepared by solution casting-ice Lek shows favorable comprehensive features and is expected to replace human condylar.

Objective To establish objectively biomechanical criteria for temporomandibular joint disc tissue engineerings. Methods  Eight temporomandibular joint discs from a four-month-old goat were separated completely. A cylindrical sample with diameter of 3 mm in the anterior, intermediate, and posterior bands was obtained, and the samples underwent pre-compression test with three cycles under a speed of 0.025 mm•s-1. With the end condition for the maximum load of less than 4.9 N and 1.5 mm compression displacement, the formal compression test was performed with the same speed. Moreover, this test obtained the stress–strain relationship and elastic modulus of each disc band. Ultrastructure and collagen fiber orientation of the district zone were observed by scanning electron microscope and polarized light microscope. Results  1)The physiological strain range of an articular disc was within 10%, and the quasilinear constitutive equation of articular disc tissues can be fitted with the polynomial function: y=ax+bx2+cx3. 2) The elastic modulus of the intermediate disc zone was the largest (P<0.05). No significant difference existed between the anterior and posterior bands (P=0.361). 3) Scanning electron microscope and polarized light microscope showed an annular disc collagen network structure, which was the internal part of the goat tem-poromandibular joint disc. The collagen arrangement of intermediate bands was tensely arranged anterior–posteriorly. The collagen of anterior and posterior bands went through mediolaterally with intersection of anterior-posterior branch fibersd. Conclusion  Annular collagen network structure is the basis for goat temporomandibular joint disc compression resistance properties. The intermediate band demonstrat ed higher compression resistance performance than the anterior and posterior bands.

Objective This study aimed to evaluate the morphometric changes in the alveolar bone of the maxillary and mandibular anterior regions after retraction in adolescents. Methods The sample size comprised 30 adolescent patients with class 1 bimaxillary protrusion (12 males and 18 females, age:12–18 years old) and were treated by extracting four first premolars. Cone beam computed tomography (CBCT) was performed 1 month before and 1 month after the retraction. For each maxillary and mandibular anterior tooth, the labial and palatal alveolar plates at cervical 1/3, middle 1/3, and apical 1/3 levels for bone thickness changes during the retraction of the maxillary and mandibular anterior regions were checked. The movements of cervical 1/3, middle 1/3, and apical 1/3 levels of the maxillary central incisor were measured. Statistical analyses were performed with SPSS 16.0. Results For the adolescents, alveolar bone thickness increased on the labial side and decreased on the palatal side. The alveolar bone thicknesses of cervical 1/3 and middle 1/3 of maxillary central incisor, cervical 1/3 and apical 1/3 of maxillary lateral incisor, middle 1/3 of mandibular central incisor, apical 1/3 of mandibular lateral incisor, and middle 1/3 and apical 1/3 of mandibular canine all increased after retraction. By contrast, the alveolar bone thickness of the apical 1/3 of maxillary canine and the cervical 1/3 of mandibular canine decreased after retraction. No statistically significant difference was observed in other region. Conclusion During retraction, a controlled tipping movement occur in adolescents.
After retraction, the alveolar bone thickness of the labial side increase, whereas that of the palatal side decrease. Moreover, the thicknesses of major areas in the alveolar bone significantly increase.

Objective  This study aimed to analyze the bone anatomy of edentulous sites in the posterior maxillary by cone beam computed tomography (CBCT). Methods  A total of 100 CBCT radiographs from patients with missing maxillary posterior teeth were obtained, resulting in a sample size of 217 edentulous sites. The width and height of edentulous were assessed by three-dimensional reconstruction. In addition, the angle A and morphology of the maxillary sinus walls were evaluated. Results  The mean bone height was 9.53 mm, and the percentage of sites than 10 mm was 62.67% (136/217). The mean bone width was 9.30 mm, and the percentage of sites more than 6 mm was 91.71% (199/217). The bone height decreased from premolar to molar areas, but the opposite trend was observed in bone width. Regarding the morphology of the sinus floor, 64.52% exhibited an oblique configuration. In angle A, the group of less than 30° was 10.14%, 30°–60° was 42.40%, and greater than 60° was 47.47%. Conclusion  A high percentage of edentulous sites in the posterior maxillary requires sinus floor elevation to allow the placement of dental implants. Thus, the use of CBCT scans is recommended to evaluate the anatomical structure of the maxillary sinus for reasonable implant planning.

As an interdisciplinary of stomatology and space medicine, space oral medicine focuses mainly on oral diseases happened under space environment. With the manned space technology stepping into the new era, space oral medicine has been put under the spotlight. This article will review the historical events on this subject, summarize the newly progress especially on craniomaxillofacial bone, tooth-derived stem cell and oral microbiology researches and still put forward future prospect.

Pathogen-associated molecular patterns (PAMPs) are conservative molecules associated with groups of pathogens or their products. These molecules are recognized by relevant receptors. PAMPs induce the expression of inflammatory cytokines through the signal cascade. The role of PAMPs in the initiation and development of periodontitis is recently attracting attention. PAMPs induce the expression of inflammatory mediators after they are recognized in the periodontium. This process damages the periodontal soft tissue and osseous tissue, thus resulting in periodontitis. The results of this study will provide an excellent resolution for the treatment of periodontitis by blocking the pathogenic pathway of PAMPs.

A case diagnosed as ossifying fibroma and compound odontoma in the mandible was reported. The clinicopathological features, diagnosis, and treatment were discussed with the literature review.

Calcifying epithelial odontogenic tumor (CEOT) is a rare benign epithelial tumor of odontogenic origin. CEOT is a benign but a locally infiltrative tumor. CEOT has two clinical variants: intraosseous (central) CEOT and extraosseous (peripheral) CEOT. The peripheral type is rare. In this paper, we report two cases of CEOT. The diagnoses of the cases were verified by histopathology. This study aims to explore the clinical and imaging appearances of CEOT and improve the understanding of the disease.