Comparative Analysis of Clinical Effects of Mineral Trioxide Aggregate in the Treatment of Endodontic Diseases.

BACKGROUND: We aimed to evaluate the efficacy of mineral trioxide aggregate (MTA) in the treatment of endodontic disease. METHODS: Oversell, 384 patients with endodontic disease treated in Xuzhou Stomatological Hospital, Xuzhou, China, from June 2015 to June 2017 were selected, and randomly divided into four groups with 96 cases per group. The repair effects of MTA, zinc phosphate cement (ZPC), silver amalgam and light-curing calcium hydroxide (LCH) on the teeth and dental pulp of patients in the four groups were compared. Meanwhile, the ill symptoms of the patients were observed to confirm whether they could be alleviated. Besides, whether the repair effects were related to ages of patients, perforation diameters of diseased teeth and repair materials was discussed. RESULTS: The success rates of MTA group, ZPC group, LCH group and silver amalgam group were 90.6%, 68.7%, 70.8% and 52.1%, respectively. The success rate of MTA group was significantly higher than that of ZPC group, silver amalgam group and LCH group. When the success rates of four groups were compared, the differences were statistically significant (P=0.0072). The patient's age, repair material and perforation diameter were positively correlated with MTA repair effect (P=0.003, P=0.002, P=0.01). The patients' teeth in each group were repaired with different materials, and the reexamination was conducted 4 weeks later. Three patients in the silver amalgam group were found to have gingival swelling. CONCLUSION: The therapeutic effect of MTA was significant in the treatment of endodontic disease, and it is worthy of clinical application.

Toxic effects of four kinds of dental restorative materials on fibroblast HGF-1 and impacts on expression of Bcl-2 and Bax genes.

The aim of this study was to investigate and discuss the toxic effect of four kinds of dental restorative materials on fibroblast HGF-1 and their impacts on the expression of B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) genes. One hundred and ninety-two patients (240 diseased teeth), who received dental restoration in the Department of Stomatology of Xuzhou Stomatology Hospital from March 2014 to March 2015, were selected and randomly divided into four groups; namely, silver amalgam group, glass-ionomer cement group, nichrome group and novel nano-composite resin group, with 60 teeth in each group. The diseased teeth were restored. The fibroblast HGF-1 was incubated in the water extracts from the four kinds of materials and ordinary cell culture fluid (negative control). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to measure the levels of Bcl-2 and Bax. A flow cytometer was applied to detect cell apoptosis. RT-qPCR results showed that compared with those in the negative control group, the mRNA expression levels of Bcl-2 in the cells of silver amalgam group, glass-ionomer cement group and nichrome group were decreased, while those of Bax were upregulated (P<0.05). The mRNA expression of Bcl-2 in glass-ionomer cement group was the highest among these three groups; the mRNA expression of Bax in nichrome group was the highest of all groups. The western blotting results revealed the same tendency as those of RT-qPCR. The results via the flow cytometer showed that cell apoptosis in nichrome group, silver amalgam group and glass-ionomer cement group was increased significantly (P<0.05) compared with that in the negative control group. The novel nano-composite resin has no obvious toxic effect on cells, and its clinical application effect is better than that of traditional dental restorative materials, which is worthy of application and generalization in clinical practice.

[Contributions of edentulous mandibular alveolar ridge height and denture adhesive to complete denture retention].

The present paper is to investigate the relationship between height and stress-bearing area of mandibular alveolar ridge, their influence on retention of complete denture, and the effectiveness of denture adhesive (DA). Five mandibular edentulous models of different heights and a rabbit palate model were prepared in Die-Stone. Measurements were made on the heights and stress-bearing areas of mandibular alveolar ridge, the retention force of mandibular models 15 min after DA administration, and the retention force on the rabbit palate before and after adhering. All available data were analyzed statistically. Linear regression relationship was demonstrated between ridge height and bearing area, ridge height and retention force, and bearing area and retention force (P<0.01), separately. Retention force per unit area was positively related to the height and area. Retention force increased to 2.87 times postadhesive-treating. Height and stress-bearing area of mandibular alveolar ridge directly correlate with the retention of complete denture, and DA significantly improves the retention ability of complete denture.

[Relationship between tissular structure and strength of fresh bull periodontal ligament].

OBJECTIVE: To study the relationship between the width and the content of fiber in peridontal ligament (PDL) and the strength of peridontal membrane. METHODS: Fresh mandible of bull was obtained to prepare for a 5 mm x 2 mm x 10 mm cuboid including teeth, peridontal membrane, and alveolar bone. The width of the PDL was measured under a stereomicroseope. Pull stress was loaded on the test piece until it broke. The stress-strain curve was recorded. The broken ends of the PDL was dyed with siriue to adalyze the content of fiber. RESULTS: The relationship between the width of the PDL and the maximum stress was expressed as Y = 9.786e(-3.6693x). The relationship between the width of the PDL and the physiological ultimate stress was expressed as Y = e((2.188(-3.953)x). The relationship between the percentage of fiber and maximum stress was expressed as Y = 20.788-0.755x + 0.007x(2). The relationship between the percentage of fiber and the physiological ultimate stress was expressed as Y = 1.39e(-14) x x(7.666). The initial physiological stress was 0.28 N/mm2. CONCLUSION: The strength of PDL increases with the decrease of PDL width and increase of fiber content.

[A structural mechanics study with human maxillary premolar].

OBJECTIVE: To evaluate the stress distribution and offset of dental and periodontal tissues imposed by changes in inner diameter of pulp cavity. METHODS: Six models of maxillary second bicuspid tooth with different inner diameter of pulp cavity were established, including: (1) calcificated pulp without pulp chamberi (2) mostly calcificated pulp chamber with inward reduction of 0. 5 mm in normal pulp cavity; (3) initially calcificated pulp chamber with inward reduction of 0.25 mm in normal pulp cavity; (4) normal pulp cavity; (5) initially absorbed pulp chamber with outward expansion of 0.25 mm in normal pulp cavity; (6) mostly absorbed pulp chamber with outward expansion of 0.5 mm in normal pulp cavity. Vertical and oblique forces with 160 N were loaded on the central fossa, respectively, in order to calculate the stress distribution of dental and periodontal tissues and the maximum incipient offset of the teeth. RESULTS: With loaded vertical and oblique forces on central fossa, increased stress distribution of periodontal tissues and maximum incipient offset of teeth were found in all of the models, which increased with the increase of pulp cavity. CONCLUSION: The change in inner diameter of pulp cavity has an impact on the stress distribution of periodontal tissues and maximum incipient offset of the second upper bicuspid teeth.