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Biomedical subjects

Hong-chen Liu

Publications and source records attributed to Hong-chen Liu.

At least 19 recordsLinked to original sources
PubMed2006

[Bone mineral density and biomechanical characters of the augmented alveolar ridge by distraction osteogenesis using Ti-Ni shape memory alloy distractor].

OBJECTIVE: To evaluate the quality of the alveolar ridge augmented by Ti-Ni shape memory alloy (Ti-Ni SMA) distractor. METHODS: All of the mandibular premolars and the first molars were extracted from 12 adult mongrel canines. One month later, box-shaped osteotomy was carried out in the left mandibles and Ti-Ni SMA distractors were imbedded. The right sides served as blank control. The canines were killed 3 or 6 months later and specimens were taken from corresponding area of the experiment sides and the control. Bone mineral density and biomechanical function were measured. RESULTS: Bone mineral density, ultimate compressive strength and Young's Modules of the augmented ridge were lower than the blank control three months after distraction. But the indexes increased and showed no significant difference with the control six months after distraction. CONCLUSIONS: The canines mandibular posterior alveolar ridge could be augmented by distraction osteogenesis using Ti-Ni SMA distractor, and the new bone is strong enough for implant placement.

Alveolar Ridge Augmentation↗
PubMed2005

[A study of mandible chewing movement in patients with developmental lateral jaw deformity].

OBJECTIVE: The purpose of the present study was to investigate effects of developmental lateral jaw deformity (DLJD) on masticatory movement. METHODS: Three coordinates of mandibular movement signals were recorded in 35 young healthy adults with normal occlusion and 28 patients with DLJD by means of a Sirognathography System during gum chewing movement. Paired and unpaired t-tests were used to compare significant difference of intra-group and inter-groups in displacement and speed. P < 0.05 was chosen as significance level. RESULTS: (1) The rhythm and directional sequence of chewing trajectory in both frontal and sagittal planes were normal in control group, while anomalies of rhythm and distribution (n = 9) and reversed sequencing (n = 7) were found in DLJD group. (2) The maximum magnitude of jaw retrusion and average speed were significant higher in DLJD group than those in control group (P < 0.01). The spatial displacement and average speed in horizontal plane and in chewing phase were also higher in DLJD group compared with control group (P < 0.05). CONCLUSIONS: DLJD patients showed anomalies in chewing pattern as well as chewing speed and displacement in horizontal plane.

Adult↗
PubMed2005

[Effects of different TiNi-SMA distractor on the height of alveolar ridge augmentation].

OBJECTIVE: To discuss the effects of titanium nickel shape memory alloy (TiNi-SMA) distractor with different stretching force and different distance between two fixed ends on the height of alveolar ridge augmentation. METHODS: The mini distractors were all made of TiNi-SMA wire. The maximum stretching force and the distance between two fixed ends according to different distractors (A, B and C) were 20 mm, 700 g; 15 mm, 1000 g; 20 mm, 1000 g. 15 adult mongrel canines were divided into three groups randomly and extracted the mandibular premolars and first molar. One month later, box-shaped osteotomies of the alveolar bone were carried out in the left mandible and the TiNi-SMA distractors were buried. The bone height was measured and the radiographs were taken before and five weeks post operation continuously. RESULTS: One week post operation, the vertical ridge augmentation of group A, B and C averaged (7.55 +/- 1.02) mm, (4.97 +/- 0.34) mm, (8.54 +/- 0.82) mm and the height remained (7.20 +/- 1.05) mm, (4.93 +/- 0.21) mm, (8.04 +/- 0.78) mm five weeks post operation. There was no statistic difference in the height of alveolar ridge augmentation between Group A and C, but Group B showed significant difference with the other two groups. In each group, the height did not changed significantly with the time. The radiographs showed obvious distraction gap post operation, and the new bone regenerated five weeks later. CONCLUSION: It suggests that in the scope of suitable stretching force, the height of alveolar ridge augmentation was determined by the size of TiNi-SMA distractor, that is to say, determined by the distance between the two fixed ends.

Adult↗
PubMed2005

[Neuronal activities related to right-sided mastication detected with functional magnetic resonance imaging].

OBJECTIVE: To observe neuronal activities related to right-sided mastication in cortex and to explore the effect of mastication on brain function. METHODS: Neuronal activities related to right-sided mastication were detected with functional magnetic resonance imaging in 10 healthy volunteers. Image data was analyzed by SPM99 software with the use of t test. RESULTS: Localization of activation in brain was different among subjects. Brain activation during mastication included left basal ganglion, Broca's area, angular gyrus and right supramarginal gyrus. CONCLUSIONS: The functional areas related to right-sided mastication and speech were closely connected, which indicated close relationship between mastication and speech. The central control of mastication might share part of common neural mechanism with that of speech. The roles of activated brain regions in mastication still remained to be elucidated.

Adult↗
PubMed2005

[Design and application of internal devices for automatic elasticity distraction osteogenesis].

OBJECTIVE: To improve the design of the devices used for autoatic elasticity distraction osteogenesis, and to preliminarily testify their feasibility for clinical application. METHODS: The internal automatic distraction devices were constructed by three parts, including sinusoid shape memory alloy distractor, reconstructive plate and mini-plate. The animal model of trifocal bone transport reconstruction of canine mandibular mentis was duplicated, in which a 6 cm mandibular mentis segment was removed and the transport disc was created by osteotomy in both ends of the mandibular defect. The plates were used for internal fixation and shape reconstruction of the mandible. They also served as transport distraction guidance for the elasticity distractor. RESULTS: The new devices could complete bone transport as expected. Regenerated bone segments were formed in two months and both sides of the mandibular body were lengthened. Because of the narrow angle and obstruction from the thick soft tissues in the mentis area, the ultimate symphysis mentalis was not reconstructed. CONCLUSION: The design of the internal elasticity distraction devices showed potential feasibility for clinical practice. But further studies are still needed for better control of the strength and balance of distraction forces.

Animals↗
PubMed2005

[Inhibition effect of methylene blue on the acids production of Streptococcus mutans].

OBJECTIVE: To study the effect of methylene blue on the growth and acid production of Streptococcus mutans, and the effect of methylene blue on acid production metabolism in plaque glycolysis model (i-PGM) in vitro, and investigate the practicability of methylene blue as a new kind of dental caries prevention agent. METHODS: Nephelometer method was used to measure OD value of Streptococcus mutans culture fluid in the different incubation conditions. The kinds and quantities of acid produced by Streptococcus mutans in the different incubation conditions were measured with gas chromatography. pH values of glycolysis buffer media of i-PGM in the different treatment conditions were measured by ORION electrode. RESULTS: (1) The OD value of Streptococcus mutans treated by methylene blue was lower than that by normal saline, and there was significant statistical difference between them. (2) The kinds of acid in three different culture fluid were same, but the total quantities of acid were significantly different among three different culture fluid, in which the total quantities of acid of culture fluids treated by glucose was the greatest, and treated by methylene blue was the lest. (3) The pH value of i-PGM treated by methylene blue was significantly different compared with negative control group, but was not significantly different compared with positive control group. CONCLUSION: Methylene blue can inhibit the growth and acid production metabolism of Streptococcus matans and acid production metabolism of i-PGM.

Dental Caries↗
PubMed2005

[Segmental mandibular reconstruction by elasticity distraction osteogenesis associated with guided bone regeneration].

OBJECTIVE: To accelerate distraction osteogenesis by utilizing guided bone regeneration technique, and to improve the automatic process of canine segmental mandibular reconstruction by elasticity distraction osteogenesis using shape memory metal alloy distractor. METHODS: Adult hybrid canines were used. Osteotomy was performed to remove a bone segment of 2.5-4.0 cm in one side of the mandible. Mandibular fixation devices and shape memory metal alloy distractor were secured according to the principles of bi-focal distraction technique. A piece of ePTFE membrane was sutured to cover the buccal side of bone defect and osteotomy gap of transport disc, where the periosteum was peeled for exposing mandible in operation. Then the incisions were totally closed. The canines were sacrificed 3 months later to harvest the mandibles for morphological observation and measurement of bone density and intensity. RESULTS: The shape memory metal alloy distractor performed distraction osteogenesis automatically and reconstructed the mandibles with bone defect. A regenerated bone segment of 1.5-2.0 cm was formed in the compression region between transport disc and contralateral mandibular end. The new bone in both of distraction and compression regions had similar height and thickness with normal mandible. Moreover the new bone density and intensity were rather satisfied. CONCLUSIONS: Membrane guided bone regeneration can avoid bone synthesis commonly caused by cicatrization of soft tissue in the bone defect, and accelerate ossification and maturation of new generated bone.

Animals↗
PubMed2004

[A three-dimensional finite element analysis of stress distribution in mandibular FPDs with different length pontics].

OBJECTIVE: To investigate the stress distribution in the mandibular fixed partial denture (FPD) by changing the length of pontics. METHODS: Based on a 3-DFE model of the mandibular FPD, we analyzed the stress distribution in the mandibular FPDs by loading the same level force at pontics with different lengths that were 2 to 4 times of normal length. RESULTS: The distribution trends of the stresses in the mandibular FPDs with differently elongated pontics were similar, but the highest von Mises stress in the bridge was enlarged. CONCLUSION: Damages may develop in the mandibular FDP, when the length of the pontic is longer than 3 times of normal length.

Dental Stress Analysis↗
PubMed2004

[The expression of PPTA and c-fos mRNA in dog caudal spinal trigeminal nucleus induced by traumatic occlusion].

OBJECTIVE: PPTA and c-fos mRNA expression were detected in dog caudalis subnucleus of trigeminal spinal tract nucleus (VC) induced by trauma occlusion in order to investigate orofacial pain mechanism. METHODS: The occlusal surface of the first and second maxillary right molars in 15 dogs were unilaterally raised 1.5 mm with casting Ni-Cr inlay which were fixed in Class I hole. On days 3, 7, 14, 30 and 60 after teeth operation, the VC of right and left sides were removed. PPTA and c-fos mRNAs were detected in experimental and control groups with reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: (1) The basal levels of PPTA and c-fos mRNAs were extremely low and poorly detectable in VC in control animals. (2) The expression of PPTA mRNA in VC of traumatic side was up regulated from 3 days after inlay was fixed in molar and reached peak level during 14 to 30 days and then down-regulated gradually and no significant difference was noted between 60 days group and control group. (3) c-fos mRNA expression was more intense during 3 to 7 days compared with the control group but undetectable in the other experimental period. (4) Both PPTA and c-fos mRNAs expression in VC of trauma occlusal side were more intense than that in the contralateral side. CONCLUSIONS: The present results show that both PPTA and c-fos mRNA expression are elevated in dog's VC induced by traumatic occlusion. The primary afferent terminal of orofacial area is sensitized, which suggest one kind of mechanism of orofacial pain in the condition of traumatic occlusion.

Animals↗
PubMed2004

[Expression of PN3 and NaN in trigeminal ganglion during occlusal trauma in rat].

OBJECTIVE: To investigate changes of two sodium channels, PN(3) and NaN, during orofacial pain by occlusal trauma in rat. METHODS: Expressions of PN(3) mRNA and NaN mRNA in trigeminal ganglion were tested during various periods of persistent occlusal trauma with reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In groups, including control, occlusal trauma groups, PN(3) mRNA and NaN mRNA were all expressed in trigeminal ganglion neurons. In the control group, there were similar density values bilaterally. In the occlusal trauma group, the density values in gel electrophoresis of PN(3) mRNA and NaN mRNA on the intervention side were slightly greater than those on the control side. CONCLUSIONS: The stimulation of occlusal trauma upregulates expressions of PN(3) mRNA and NaN mRNA, which suggests the signal occurring and conduction of chronic pain by occlusal trauma have the same molecular mechanism of sodium channel as inflammatory pain.

Animals↗
PubMed2003

[Induction of lymphangiogenesis by mouse ascites hepatoma cell H22 in vitro].

OBJECTIVE: To construct lymphangiogenesis model of Balb/c mouse in vitro to observe the impact of mouse ascites hepatoma cell H22 on the lymphangiogenesis and lymphatic endothelial proliferation. METHODS: Intraperitoneal benign lymphangioma induced by incomplete Freund's adjuvant in Balb/c mouse was harvested and embedded in fibrin gel to culture in vitro with conditioned medium (CM) of H22 cell. The gels, observed by inverted microscope and transmission electron microscope, were then digested to separate the cells. The expression of Flt-4, c-fos and iNOS in the cell and the content of NO in medium were studied by immunohistochemical and histochemical method. RESULTS: Lymphatic capillary generating from lymphangioma specimen in the gels was observed by inverted microscope and transmission electron microscope. H22 CM was observed to enhance growth of the vessels, induce expressions of Flt-4, c-fos and iNOS in the separated cells and increase content of NO in the medium. CONCLUSION: The model is convenient for in vitro study of lymphangiogenesis. H22 cell can accelerate lymphangiogenesis, which warrants further study for the understanding of the role of lymphangiogenesis in metastasis.

Animals↗
PubMed2003

[Reconstruction of segmental mandibular defect of canine using titanium-nickel distractor].

OBJECTIVE: To establish a continuous and automatic distraction osteogenesis technique in reconstruction of segmental mandibular defect by using embedded titanium-nickel alloy distractor with characteristics of shape-memory and super-elasticity. METHODS: Adult hybrid canines were used as the animal model. Segmental defects of 1-3 cm in the body of mandible were created by surgical osteotomy. Bi-focal distraction osteogenesis was applied using embedded titanium-nickel distractor designed by the authors. The canines were sacrificed 3 months after the operation and the mandibles were harvested to examine the results of bone regeneration. RESULTS: The histocompatibility of titanium-nickel distractors was good. Distraction osteogenesis was completed automatically and the defects were elementarily restored. Radiological and histological examination showed well bone regeneration in distraction area. CONCLUSIONS: Distraction osteogenesis using embedded self-loading titanium-nickel distractor could be a hopeful and useful technique. It might help to solve the problems of functional mandibular reconstruction in the near future.

Animals↗