Influence of fracture resistance of prosthesis with different thickness of ferrule restored with fiber post and resin core and crown / 中华口腔医学杂志

Objective@#To evaluate the influence of fracture resistance of endodontically treated teeth with different thickness of ferrule by mechanical fatigue test and static loading test, and so as to provide a reference for the clinical treatment planning.@*Methods@#Fifty bovine incisors were divided into 5 groups by random number table method (n=10). Group A was the control group in which the incisors were prepared without a ferrule design (0 mm). The other four groups (B, C, D, E) were experimental groups, and the thickness of the dentin ferrule prepared for specimens in each group was 0.5, 1.0, 1.5, and 2.0 mm. The height of ferrules in all the specimens was 2 mm. Cyclic fatigue loading (2.33 Hz, 50 N) was applied on each specimen until either the specimen was dislodged/fractured or the 300 000 cycles were finished. After fatigue loading, the mode of failure was observed. Those intact specimen after fatigue loading were tested under a gradually increasing force using a universal testing machine (0.05 mm/min) until fracture occurred. The forces required to fracture and failure model was recorded.@*Results@#The results of cyclic loading tests showed that: all specimens survived the 300 000 cycles of intermittent loading. The results of static loading tests showed that: the fracture force of A, B, C, D and E groups respectively were (226.4±67.7), (369.7±34.5), (400.7±48.2), (528.1±56.3), and (555.4±98.5) N (F=15.227, P=0.000). There was a significant difference in fracture resistance between group A and the other four groups, and between group B, C and group D, E (P<0.05). No statistical difference were found in fracture resistance among the other groups (P>0.05). There was strong correlation between the thickness of ferrule and the fracture force by Pearson correlation analysis (r=0.973, P=0.002).@*Conclusions@#Within the limitations of this study, the following conclusions can be drawn: The different thickness of ferrule can influence the fracture resistance of the teeth, and when the height of the ferrule is 2.0 mm, the fracture force increased significantly with an increasing ferrule thickness.

The effect of restraint stress on masseter mechanical hyperalgesia and the activity of neurons and astrocytes in the spinal trigeminal nucleus caudalis in rats / 中华口腔医学杂志

Objective@#To investigate the effect of restraint stress on masseter mechanical hyperalgesia and the activity of neurons and astrocytes in the spinal trigeminal nucleus caudalis (Vc).@*Methods@#The animals were randomly divided into the control group, 1-, 3-, 5-, 7-, 9-, 11-and 14-day stress groups, with 10 rats in each group. The body weight increase and behavior tests were used to testify the animal model. The mechanical sensitivity of masseter of the rat before and after the stress was measured with Von Frey filaments. Histological examinations were used to evaluate the expression of neuronal c-fos and astrocytic glial fibrillary acidic protein (GFAP).@*Results@#Restraint stress resulted in remarkable mechanical allodynia in the masseter muscle. The head withdrawal threshold was significantly lower in the 7-, 9-, 11-and 14-day stress groups ([0.071±0.011], [0.059±0.020], [0.052±0.011], [0.033±0.011] N) than that in the control group ([0.120±0.025] N) (P<0.05). Compared to the control group, the rats in the 1-day stress group showed a significant increase of c-fos in neurons of the Vc and then declined to normal level after 1 week gradually. The GFAP expression in astrocytes of the Vc was significantly increased in the 7-, 9-, 11-and 14-day stress groups (4.3±1.0, 4.5±0.6, 4.6±0.5, 4.8±1.3) compared with the control group (2.0±0.8) (P<0.05).@*Conclusions@#Chronic restraint stress could lower the threshold of mechanical allodynia in the masseter muscle and activate the neurons and astrocytes in Vc. The activation of neurons and astrocytes plays an important role in the masseter hyperalgesia induced by restraint stress in rats.

The study of tongue pressure during swallowing liquid in healthy adults / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the tongue pressure (TP) produced by tongue-hard palate contact in the process of normally swallowing liquid in healthy adults.</p><p><b>METHODS</b>Thirteen adult male subjects were recruited to perform a single swallow of 5 ml water when sitting with upright position. The tongue pressure sensor sheet was used to monitor TP as a result of tongue-hard palate approximatation in the anteriomedian, midmedian, posteriomedian and circumferential parts, and the swallowing sound was recorded by microphone. The temporal sequence of TP at each measured part was obtained after setting the swallowing sound as the reference time. Also, the total duration, pre-peak duration, post-peak duration, maximum magnitude and integrated value of TP were recorded and compared among the measured parts.</p><p><b>RESULTS</b>TP was produced from anterior to posterior along the midline of hard palate during normal swallowing of water [Ch1: (-0.40 ± 0.22) s, Ch2: (-0.36 ± 0.21) s, Ch3: (-0.24 ± 0.18) s], with the circumferential TP [Ch4: (-0.38 ± 0.23) s, Ch5: (-0.40 ± 0.23) s] occurring nearly to the anteriomedian one (P > 0.05). Before the swallowing sound (P < 0.05), TP at each part reached a peak synchronously [Ch1: (-0.12 ± 0.24) s, Ch2: (-0.16 ± 0.22) s, Ch3: (-0.13 ± 0.21) s, Ch4: (-0.16 ± 0.23) s, Ch5: (-0.17 ± 0.23) s] in a rapid manner (P > 0.05), then decreased gradually until disappeared simultaneously [Ch1: (0.32 ± 0.23) s, Ch2: (0.27 ± 0.21) s, Ch3: (0.23 ± 0.16) s, Ch4: (0.33 ± 0.31) s, Ch5: (0.33 ± 0.29) s] (P > 0.05) after the swallowing sound (P < 0.05). The TP related parameters (the total duration of TP:Ch1: (0.72 ± 0.20) s, Ch2: (0.63 ± 0.16) s, Ch3: (0.47 ± 0.17) s, Ch4: (0.70 ± 0.35) s, Ch5: (0.73 ± 0.29) s; the pre-peak duration of TP: Ch1: (0.28 ± 0.21) s, Ch2: (0.20 ± 0.16) s, Ch3: (0.12 ± 0.10) s, Ch4: (0.21 ± 0.22) s, Ch5: (0.23 ± 0.21) s; the post-peak duration of TP: Ch1: (0.44 ± 0.23) s, Ch2: (0.43 ± 0.18) s, Ch3: (0.36 ± 0.18) s, Ch4: (0.49 ± 0.25) s, Ch5: (0.50 ± 0.23) s; the maximum magnitude of TP: Ch1: (13.80 ± 7.73) kPa, Ch2: (12.40 ± 6.51) kPa, Ch3: (10.26 ± 7.15) kPa, Ch4: (12.16 ± 5.38) kPa, Ch5: (13.08 ± 5.05) kPa; the integrated value of TP: Ch1: (4.99 ± 3.69) kPa×s, Ch2: (4.25 ± 2.13) kPa×s, Ch3: (2.88 ± 1.87) kPa×s, Ch4: (4.32 ± 3.47) kPa×s, Ch5: (4.63 ± 2.49) kPa×s were significantly smaller in the posteriomedian part among all the five parts measured. No laterality was found in TP produced at the circumferential parts of the hard palate (P > 0.05).</p><p><b>CONCLUSIONS</b>The TP at each part coordinates precisely during swallowing. The effective measurement of TP by tongue pressure sensor sheet will facilitate the evaluation of oral swallowing and the diagnosis of dysphagia simply and non-invasively.</p>

Effects of tongue pressure sensor sheet on the signal waveform of laryngeal movement produced by bend sensor during deglutition / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To evaluate the effects of the application of tongue pressure sensor sheet on the signal waveform of laryngeal movement produced by the bend sensor during deglutition.</p><p><b>METHODS</b>Twelve adult male subjects were recruited to perform a single swallow of 5 ml water when sitting on the dental chair with upright position. The data recorded by bend sensor was obtained with attaching tongue pressure sensor sheet simultaneously or not. Then the measured parameters by bend sensor with or without concurrent application of tongue pressure sensor sheet were compared.</p><p><b>RESULTS</b>There were no significant differences between the same time point on the signal waveform produced by bend sensor whether concurrently attaching tongue pressure sensor sheet or not (P > 0.05). Additionally, we found no statistical significances between matched phases on the signal waveform recorded by bend sensor with or without application of tongue pressure sensor sheet (P > 0.05).</p><p><b>CONCLUSION</b>The findings in this study suggest us that the usage of tongue pressure sensor sheet exerted no influences on the waveform of the laryngeal movement produced by bend sensor during deglutition, facilitating us to further apply tongue pressure sensor sheet and bend sensor simultaneously to record tongue pressure production and hyoid activity during deglutition.</p>

Analysis of cortical bone of the mandibular body in psychological stressed rats by micro-CT / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To calculate the bone mineral density (BMD) of buccal and lingual mandibular cortical bone in psychological stressed rats.</p><p><b>METHODS</b>One hundred adult male SD rats were randomly divided into psychological stress group(PS group, 40 rats), control group (C group, 40 rats) and foot shock group (FS group, 20 rats). In addition, the PS group and C group were equally divided into week 1, week 2, week 3, week 4 and week 5 subgroup at random. The animals placed intervally in the communication box to receive the psychological stimuli were considered as the PS group animals. The stressors were from their neighboring FS group rats which were receiving foot shock. After observing the behavioral changes of the PS group rats and C group rats with elevated plus maze test, the mandibles were removed carefully and BMD of regions of interest (ROI) in the mandible were calculated by Micro-CT. The ROI were located at the equidistant five points, i.e. A, B, C, D and E, along the anteroposterior border and approximately halfway between the superior and inferior border of the mandible.</p><p><b>RESULTS</b>Significant decrease of time spent in the open arms, ratio of open arms time and ratio of open arms entries were observed in PS group [time spent in the open arms: (16.6 ± 2.3), (17.1 ± 2.4), (15.8 ± 1.6), (15.8 ± 2.2), (17.9 ± 2.6) s]; ratio of open arms time: [(30.5 ± 3.7)%, (30.3 ± 2.5)%, (26.8 ± 3.8)%, (26.5 ± 2.0)%, (27.4 ± 2.6)%]; ratio of open arms entries: [(34.1 ± 4.4)%, (34.6 ± 4.1)%, (32.6 ± 3.9)%, (34.5 ± 4.8)%, (31.8 ± 3.3)%] compared with control group at each time point (P < 0.05), no differences were observed among PS groups (P > 0.05). On the buccal side of mandibular body, BMD in point D of week 5 PS group [(1 085.4 ± 88.5) mg/cm³] was higher than that of matched control group [(782.3 ± 53.7) mg/cm³) ]and week 1 PS group [(825.2 ± 88.5) mg/cm³] (P < 0.05). Similar results of BMD were obtained in point E between week 5 PS group [(657.2 ± 101.7) mg/cm³] and control group [(415.9 ± 99.7)mg/cm³], week 1 and 2 PS group [(348.1 ± 111.3), (339.3 ± 74.0) mg/cm³] (P < 0.05). On the lingual side of mandibular body, the alterations of BMD were observed in point B and C between week 5 PS group [(1 755.6 ± 156.6), (1 367.8 ± 115.8) mg/cm³]and matched control group [(1 364.6 ± 120.2), (922.6 ± 102.6) mg/cm³] and week 1 PS group [(1 299.7 ± 172.9), (1 052.3 ± 107.9) mg/cm³] (P < 0.05). No differences of BMD were observed in the other points between PS group and control group at each time point(P > 0.05).</p><p><b>CONCLUSIONS</b>Psychological stress induced by communication box could result in the anxious behavior of SD rats and increase the BMD of cortical bone in certain regions of the mandibular body.</p>

The effect of sevoflurane and propofol anesthetic techniques on interleukin-6 and interleukin-10 in patients with laparoscopic hysterectomy / 中国医师进修杂志

Objective To study the effect of sevoflurane and propofol anesthetic techniques on interleukin (IL)-6 and IL-10 in patients with laparoscopic hysterectomy.Methods Fifty elective laparoscopic hysterectomy patients were randomly divided into sevoflurane group (25 patients) and propofol group (25 patients) who received either sevoflurane or propofol for their anesthesia.After induction,adjusted the sevoflurane inhalation concentration in sevoflurane group and propofol pumping speed in propofol group.Maintained the Bispectral index (BIS) value at 50 +5.Recorded heart rate (HR),mean arterial blood pressure (MAP),BIS,IL-6,IL-10 on 5 min before anesthesia (T1),10 min after pneumoperitoneum (T2),40 min after pneumoperitoneum (T3) and 5 ain before the end of the operation (T4),and compared.Results The level of BIS,HR,MAP in two groups and between two groups had no significant difference (P ＞ 0.05).The level of IL-6,IL-10 on T2-T4 were significantly higher than those on T1 [sevoflurane group:(31.0 ± 9.0),(33.0 ± 11.0),(34.0 ± 16.0) ng/L vs.(29.0 ± 8.0) ng/L and (19.3 ± 1.7),(24.0 ± 2.8),(27.0 ± 8.0) ng/L vs.(2.0 + 0.4) ng/L; propofol group:(38.0 ± 9.0),(40.0 + 12.0),(45.0 ± 18.0) ng/L vs.(29.0 + 11.0) ng/L and (8.2 ± 2.3),(11.0 ± 4.2),(18.0 ± 7.0) ng/L vs.(2.0 ± 0.3) ng/L] (P ＜ 0.05).The level of IL-6,IL-10 on T1 between two groups had no significant difference (P ＞ 0.05).The level of IL-6 on T2-T4 in sevoflurane group was significantly lower than that in propofol group and the level of IL-10 on T2-T4 in sevoflurane group was significantly higher than that in propofol group (P＜ 0.05).Conclusions At maintaining the balance of cytokines in laparoscopic hysterectomy,the effect of sevoflurane is better than propofol.Sevoflurane is more suitable for maintenance of anesthesia for laparoscopic gynecologic operation.

The expression of SP and CGRP in the temporomandibular joints of the rats undergone emotional stress / 中华行为医学与脑科学杂志

Objective To observe the substance P(SP) and calcitonin gene-related peptide(CGRP) expressions in the temporomandibular joints(TM J) of the rats undergone emotional stress and explore the relationship between emotional stress and temporomandibular joint disorder(TMD). Methods Ninety SD rats were averagely randomly divided into emotional stress ( ES ) group( n = 30 ), electric foot-shocked (FS) group ( n = 30 ) and control (CON) group( n = 30). The emotional stress was induced by communication box. The TMJ tissues in ES and CON groups were removed after 1, 3 and 5 weeks of emotional stress for scanning electron microscope ( SEM ) test and immunohistochemistry test. The SP and CGRP expressions were examined with SABC immunohistochemistry and then analyzed by image analysis system. Results The expressions of SP and CGRP had significant difference after 1 ,3 and 5 weeks emotional stress ( SP: 124.5 ± 16.9,185.6 ± 1.8 and 193.5 ± 3.5, respectively; CGRP: 185.9 ±5.3, 112.5 ±5.2 and 174.3 ±5.3 ,respectively) (P＜0. 05 ). The SEM results showed that there was a series of structural change on the condylar surface after emotional stress. Conclusion The SP and CGRP energy nerve fibers take part in the TMJ pathological process undergone emotional stress.

Morphologic observation on root canal of mandibular incisors / 实用口腔医学杂志

medial distal wall. The root canal length of central and lateral incisors were (12.96?6.46) mm and (11.47?6.32) mm respectively. The double root canal was found in 35.9 % of central incisors and in 27.5% of lateral incisors. Most mandibular incisors with long concavity had single root canal. Conclusion: The root canal wall of mandibular incisors was thinner in medial and distal wall than in lingual and labial wall. Mandibular incisors have higher rate in double root canal and the long concavity is not significantly related with number of root canal.

Hemagglutinin A of Porphyromonas gingivalis function as adhesion and invasion in human gingival epithelial cells / 实用口腔医学杂志

Objective: To determine if the hemagglutinin A (HagA) of Porphyromonas gingivalis could be involved in the adhesion and invasion in human gingival epithelial cells (HGEC). Methods:P. gingivalis 381 hagA mutant was constructed by conjugation method. The whole length of hagA gene was cloned into pYA292 in Salmonella typhimurium x4072 (S. typhimurium-hagA). The strains were used to test their ability of adhesion and invasion into HGEC using a standard antibiotic protection assay. S. typhimurium x4072 strains containing empty vectors were used as negative control. HagA expression in S. typhimurium-hagA was confirmed by Western blot. Results:Although there were no significant differences between P. gingivalis 381 hagA mutant and wild type in adhesion and invasion into HGEC, the adhesion values of S. typhimurium-hagA to HGEC were increased by 3 times compared to their respective controls, while the invasion ability of S. typhimurium-hagA was 4 times greater than that of the negative controls. Conclusion: These results suggest that HagA may participate in P. gingivalis adhesion and invasion into HGEC.

The pathological changes of rat temporomandibular joint under emotional stress / 实用口腔医学杂志

Objective:To observe the influence of emotional stress on the temporomandibular joint(TMJ) of SD rats. Methods:Standard animal model of emotional stress was created by emotion communication emergency box technique in 30 SD rats and foot-shocked in another 30. Control rats were 30 without treatment. The microstructure and ultrastructure of the disc surface, condylar surface and external pterygoid muscle were observed 1, 3 and 5 weeks after emotional stress treatment. Results:Obviously pathological changes were observed in the experimental animals, especially at 3 weeks, involving the fissures on the disc and condylar surface, the collagen fibers were disordered. Electron microscopy observation showed that condylar collagen was exposed. The mitochondria edema and vacuolar degeneration in the external pterygoid muscle were found.At 5 weeks, the condylar cartilage started to recover. Conclusion:Long term emotional stress may lead to pathological changes of the temporomandibular system. The changes can be partly recovered after a certain time of adaption of TMJ.

Effect of occlusal splint oa electromyogram of lateral pterygoid muscie dysfunction / 实用口腔医学杂志

The electromyogram(EMG) of lateral pterygoid muscle (LP) in 43 patients with LP dysfunction was measured before, when and after the use of occlusal splint. The postural and clenching activity of superior LP decreased dramatically when patients were wearing the occlusal splint. Normal EMG was observed in patients with normal arthrograra when the symptoms and signs were eliminated or reduced by occlusal splint. The EMG of dysfunctional LP in some patients with anteriorly displaced disk recovered to that with normal function as the incoordinated condyle -disk rektion was corrected. However, LP dysfunction was still present in most patients with irreversible anterior disk displacement and disk perforation after splint therapy.