Objective To study the differences between the mandibular movement in empty opening and protrusion trace of the skeletal anterior reverse malocclusion before and after the early protraction treatment in early stage of mixed dentition. Methods ACRUSdigma system, a kind of ultrasonic mandibular movement record system, was used in the study. The kinematic center which can represent the translation and rotation of the condylar and the incisal points were used as reference point to compare the difference of the empty opening and protrusion mandibular movement trajectory of 30 individuals with skeletal anterior reverse bite malocclusions before and after the early protraction facemask treatment. Results For the kinematic center, the typical trajectory was changed, the upper movement disappeared and the distances between vertical and horizontal movements were increased at the end of the treatment in the empty opening movement on the sagittal plane. In the empty protrusion movement, the interplanar distance of the kinematic center was increased significantly on the sagittal plane. For the incisial point, it moved ahead at first and then downward vertically in the empty protrusion movement, and the interplanar distance was increased significantly on the sagittal plane in the empty opening movement. Conclusions By giving the protraction treatment, the relation of upper mandible and submaxilla of the skeletal anterior reverse bite malocclusions is changed. During the later stage of the treatment, for the occlusal splint was ground off, the normal occlusial inducement is built, which affords the rebuilding of temporomandibular joint (TMJ), ligaments and muscles. The trajectory also becomes normal. The normal trajectory may supply a better environment for the development and rebuilding of jaw, TMJ, ligaments and muscles.

Biomedical Research ; trends ; China ; Humans ; Temporomandibular Joint Disorders

Object To develop a mathematical model on the relationship between the temperature used in the course of extraction of medicinal herbs and the concentration of active component obtained Methods Based on the kinetic model on medicinal herb extraction process reported in our previous article *, diffusion coefficient and concentration gradient varying with temperature were further studied Results The process which tanshinone was extracted from Salvia miltiorrhiza Bge at different temperatures showed that the model could well match the experimental data Conclusion The relation between the temperature and the concentration of active component could be described by this model

Objective To study the biosafety of colored alumina-glass composite by mucosa irritation test. Methods The colored alumina-glass composite and a non-irritating material were separately fixed to the oral mucosa of a mouse. The contact parts were examined with bare eye, histologically and cytologically. Results No obvious inflammation of the mucosa was detected in the site where colored alumina-glass composite was in contact. Conclusion Alumina-glass composite has good biosafety.

Objective To investigate the expression change of receptor activator of NF ?B ligand (RANKL) and osteoprotegerin (OPG) mRNA in rat alveolar bone and the possible mechanism of alveolar bone resorption under traumatic occlusion. Methods Thirty SD rats weighed 270g?20g were used and divided into 6 groups, of which one group was as control. A square wire thickened about 1mm was bonded with Super bond composite resin on to the occlusal surface of left upper first molar of the rats in experiment groups. The animals were executed after 1,3,7,14,28 days. The left jaw were processed for the study of the expression of RANKL and OPG mRNA with RT PCR. Results Expression of RANKL and OPG mRNA in alveolar bone was significantly different between experiment and control groups. During occlusal trauma, expression of RANKL and OPG mRNA enhanced in 1 day group. The ratio of RANKL/OPG mRNA expression raised in 1、14 and 28 day groups. Conclusion The ratio of RANKL/OPG mRNA expression changed during occlusion trauma. RANKL and OPG might be involved in the restructure of periodontal tissue after traumatic occlusion

Objective A fibronectin like peptide was designed and synthesized based on the structure and function relationship study of extra cellular matrix protein in order to search after a kind of new method to improve the bioactivity of hydroxyapatite based biomaterials. Methods A peptides named P19 with two functional groups was synthesized by employing solid phase peptide synthesis. The synthesized peptides were preliminarily purified with Sephadex G 15 column chromatography and further modified with air oxidation method. The purity of P19 were determined with RP HPLC. The molecular weight of peptide was identified with TOF MS. Its binding characteristics and bioactivity was investigated. Results P19 has high affinity with hydroxyapatite and cannot be eluted under physiological condition. Its dissociation constant is 14 3?0 8?mol/L and the maximum of attached peptides by 100?g HA is 2 57?0 51nmol. It can affect the in vitro calcification of gel system. The plate pretreated with P19 can enhance the number of attached cells and the proliferation of attached cells is also promoted. The fibronectin like activity was also proved by the competitive inhibition effect of P19 on the cell attachment. It also can promote the proliferation of UMR 106 cell line. Conclusion The synthesized peptide possess two function as design, it may have extensive application prospect as an ingredients of HA based materials or coating layer of implant

Objective The purpose of this study was to compare the functional and morphological changes in the cervical spine with protrusion of cervical disc (PCD) under different directions of traction. Methods MRI scanning was used to study the effect of different directions of traction on the movement of protrusive disc，compression index of spinal cord and changes of intervetebral space,as well as the cases with degeneration. Results　Differences were found in the effect of different directions of traction. Most significant partial reduction of the protrusive disc was experienced in flexion traction. Both flexion and extension traction caused significant decrease in the index of compression of spinal cord. Extension traction caused marked narrowing of the posterior intervertebral space in the group with decreased disc size,while no difference between the groups with and without decreased disc size when given flexion traction. There was no difference in the anterior intervertebral space between the two directions of traction. No morphological change was observed in cases with degeneration using either direction of traction. Conclusion PCD could caused the change in the fine morphology of normal vertebral joints. The traction direction should be chosen according to the condition of the individual case. The compression index could better reflect the nature of spinal cord injury than the size of the disc protrusion. Traction would not give much benefit in cases with degeneration.

Objective:To evaluate the feasibility of fMRI on the location of brain regions related to cold stimulated toothache. Methods: 8 patients with cold induced dentinalgia of the right maxillary bicuspid and 8 healthy volunteers with full and healthy dentition were selected to perform the fMRI study, all of which are right handed. Block designed blood oxygen level dependent(BOLD) functional MRI scan covering the whole brain was carried out. SPM2 software was adopted to generate the activation map. Results: The patient group showed significant bilateral activations in insula/SII, basal ganglion, cingulate gyrus, midbrain red nucleus. BOLD signals were also found unilaterally in right thalamus, inferior parietal lobule(BA7) and left inferior frontal gyrus(BA44), MII/PMC. In contrast, the normal group showed increased signals in bilateral PMC and inferior parietal lobule BA40. Left lentiform nucleus, SI/MI and right inferior parietal lobule(BA7) were also excited in none painful cold sensation. Conclusions: Motor related cortex including PMC, SMA and BA44 have strong signals during dental pain. Compared with limb pain, tooth pulp stimulation evoked a more pronounced activation in the ipsilateral hemisphere in some brain regions.

To explore the characteristics and treatment of pseudopericoronitis of wisdom teeth of the mandible by clinical analysis of 36 cases.Results showed that the patients of pseudopericoronitis of the wisdom tooth of the mandible were of elder age,mild symptoms, totally impacted in the mandible,resulting in overgrowth of the corresponding third molar of the maxtilla overgrown.The observations indicated that the symptoms of pseudocoronitis of the wisdom tooth of the mandible was the injury inflicted to the soft tissue due to excessive growth of the third molar in the maxilla directly or indirectly.The method of treatment is to extract the overgrown third molar in the maxilla,and leave the wisdom tooth of the mandible alone.

Objective:To develop an automatic and continuous distraction osteogenesis technique by using totally embedded distractor of nickel titanium (Ni-Ti) shape-memory alloy for the reconstruction of mandibular ramus. Methods:16 adult New Zealand rabbits were used in the experiment. Mandibular ramus and condyle on one side was removed to create a 1.5 cm segmental defect. A transport disc was created by "L" shape osteotomy at the end of the remnant ramus and Ni-Ti distractor was fixed and totally embedded in tissues. The rabbits were sacrificed 2 months after operation and the mandibles were harvested.The bone reconstruction were studied with radiographic and histological examination. Results: 2 months after operation all the animals were alive and mandible function kept well.The Ni-Ti distractors were self-activated and performed distraction osteogenesis automatically. The mandibular ramus achieved preliminary reconstruction. Histological examination showed bone regeneration in the distraction area. Conclusions: Ni-Ti distractor can fulfill automatic and continuous distraction osteogenesis.