Animals ; Dental Implantation, Endosseous ; adverse effects ; Dental Implants ; adverse effects ; Dental Prosthesis, Implant-Supported ; adverse effects ; Dentition ; Humans ; Malocclusion ; etiology ; Maxillofacial Development

OBJECTIVETo study the mechanical properties of two kinds of composite resins reinforced by preimpregnated glass fibers.

METHODSSinfony and belleGlass composite resins were used to make standard samples (25 mm x 2 mm x 2 mm) with and without glass fibers. After all specimens were stored for 24 hours in distilled water at (37 +/- 1) degrees C, the flexural strength and flexural modulus were measured on a universal test machine.

RESULTSBoth flexural strength and flexural modulus of Sinfony composite reinforced by the glass fibers became significantly increased, which were (555.76 +/- 67.31) MPa and (12.59 +/- 3.06) GPa respectively, and 4.5 and 2.5 times much more than those of the specimens without glass fibers (P = 0); the flexural modulus of belleGlass composite became significantly increased, which was (14.10 +/- 2.88) GPa, and 0.9 time much more than the specimens without glass fibers (P = 0), but the improvement of flexural strength was not significant.

CONCLUSIONGlass fibers can improve the mechanical properties of composite resins, but the reinforcement effect is different between different resins.

Composite Resins ; chemistry ; Glass ; chemistry ; Materials Testing

OBJECTIVETo evaluate the mandible angle and to investigate the relationship of angle size to gender, age-group, cortical thickness at the mandibular angle (CTMA), height of mandibular residual body, and edentulous period in the elderly edentulous subjects.

METHODSA total of 356 panoramic radiographs of three groups of subjects were evaluated: the young dentate group, 131 subjects (mean age: 27); the older dentate group, 97 (mean age: 64); and the elderly edentulous group, 128 (ages 76, 81, or 86). Mandibular angle size, CTMA, and height of mandibular residual body were measured from panoramic radiographs. A structured questionnaire was used to determine the history of edentulousness.

RESULTSDifference in angle size was found between dentate men and women (P < 0.05, P < 0.001), but not between the elderly edentulous men and elderly women. The elderly edentulous subjects had larger mandibular angles than did older dentate subjects (P < 0.001). The angle size was negatively related to CTMA only among 76-year-old edentulous women (P < 0.01) and negatively associated with average height of the mandibular residual body in the edentulous men and women (P < 0.01). No association existed between angle size and duration of edentulousness.

CONCLUSIONSElderly edentulous subjects have large mandibular angles and the angle size is correlated with low-height of the mandibular residual body, which suggests that masticatory function of natural dentition and complete denture may influence change of the mandibular angle. The significant relationship of mandibular angle size to CTMA probably indicates the effect of systemic factors on change in the mandibular angle.

Adolescent ; Adult ; Age Factors ; Aged ; Aged, 80 and over ; Alveolar Process ; diagnostic imaging ; pathology ; Cephalometry ; Female ; Humans ; Jaw, Edentulous ; diagnostic imaging ; Male ; Mandible ; diagnostic imaging ; pathology ; Middle Aged ; Radiography

Objective To investigate the feasibility of ~1H-MR spectroscopy(~1H-MRS)imaging to quantitatively detect fatty liver.Methods Twenty patients with fatty liver and 11 healthy volunteers underwent plain CT scan,conventional MR imaging and ~1H-MRS analysis.The blood lipid and liver function were tested on the same day as the MR examination.~1H-MRS sequence measured the peaks of H_2O and lipid,and the areas under the peaks.The relative contents of the lipid compound were calculated,and compared with the results of CT scan and liver function tests.Results The CT values of the normal group and the fatty liver group were(59?9)HU and(24?11)HU respectively.On ~1H-MRS a protruding high H_2O peak and a flat low lipid peak were observed in the normal group,while the protruding high H_2O peak and a high lipid peak appeared in the fatty liver group.The values of lipid peak in the normal group and the fatty liver group were(0.05?0.01)?10~5,(0.70?0.24)?10~5 respectively(t=4.32,P0.05),the areas under the lipid peak were(1.36?0.73)?10~9、(2.35?1.15)?10~9 respectively(t=5.21,P0.05).Conclusion ~1 H-MRS imaging is feasible to quantitatively detect liver fat and is a non-invasive method for detecting early fatty liver.

Objective To explore the effect and mechanism of relaxin on the production of extracellular matrix (ECM) excreted by high glucose stimulated human renal mesangial cells.Methods Cultured human mesangial cells (HMCs) were divided into three groups:(1) normal glucose group (NG,5.5 mmol/L D-glucose),(2) high glucose group (HG,30 mmol/L D-glucose),and (3) high glucose + relaxin group.Cell count kit (CCK8) was used to examine the cell proliferation.The levels of fibronectin and collagen type Ⅳ in the culture supernatants were examined with a solid-phase enzyme-linked immunoadsorbent assay (ELISA);Western blot method was used to detect the expression of α-smooth muscle actin (α-SMA) protein.The transforming growth factor-β1 (TGF-β1) mRNA expression was detected with quantitative polymerase chain reaction (qPCR) method.Results No proliferation and inhibition effects were observed in both normal and high glucose group.Compared to the normal glucose group,the levels of fibronectin,and collagen type Ⅳ increased significantly (57.28 ± 0.59 vs 41.85 ± 0.03,56.52 ± 0.88 vs 33.80 ± 0.24,P ＜ 0.01)after cultured 48 h in high concentration of glucose.Compared to the high glucose group,a significantly decreases of fibronectin and collagen type Ⅳ (47.08 ± 0.03 vs 57.28 ± 0.59,36.16 ± 0.52 vs 56.52 ±0.88,P ＜0.01) were observed in the relaxin treated group.The expressions of α-smooth muscle actin and TGF-β1 were decreased (P ＜0.01).Conclusions Relaxin can suppress the overproduction of ECM excreted by HMC cultured in high ambient glucose,and its mechanism is partly due to the inhibition of TGF-β1.

OBJECTIVETo compare electrical sensory threshold (EST) and electrical pain threshold (EPT) of bilateral masseters, temporal muscles and finger region of chronic masticatory muscle pain (MMP) patients and the controls, and to analyze the mechanism of pain threshold change.

METHODSTwelve patients with MMP and 12 matched controls participated in this study. EST and EPT of bilateral masseters, bilateral temporal muscles, and left middle finger were recorded and compared within group and between groups.

RESULTSCompared to the controls, the EPTs of patients significantly decreased [left masseter (5.9 +/- 1.1) mA,right masseter (5.7 +/- 1.0) mA, left temporal muscle (5.3 +/- 1.4) mA, right temporal muscle (5.5 +/- 1.7) mA,finger (5.2 +/- 1.0) mA] (P < 0.001). There was no significant difference in EST between patients and the controls. No relationship was found among VAS, ESP, and EPT.

CONCLUSIONSDecreased pain thresholds of masseters, temporal muscles and fingers in MMP indicated that peripheral sensitization was induced in MMP patients. Decreased pain threshold in patients meant that MMP might influence the central modulation of nervous system.

Adult ; Case-Control Studies ; Chronic Disease ; Electric Stimulation ; Face ; Facial Pain ; physiopathology ; Female ; Fingers ; Humans ; Male ; Masticatory Muscles ; physiopathology ; Middle Aged ; Pain Measurement ; Pain Threshold ; Young Adult

OBJECTIVETo study the natural head posture (NHP) of edentulous patients compared with dentate people and to understand NHP shift immediately inserting complete dentures and three months after denture wearing.

METHODSThe NHPs of twenty edentulous patients and twenty-two dentate subjects were recorded with cephalometric technique. The NTPs of edentulous patients were exposed three times, before inserting, right after inserting and three months after inserting dentures. The NHPs of dentate subjects were recorded once as a controlled group. Six angles measured from the radiographs were evaluated for the NHP and three angles and two linear measures for the mandibular position.

RESULTSCompared with dentate subjects, the craniomandibular angles of the edentulous patients increased and the camber of the cervical columns decreased, but changes of the NHP were not significant. The mandible showed a significant upward moving (P < 0.05) and an insignificant forward moving. At the time of denture insertion, the camber of the cervical columns significantly increased (P < 0.05). Three months after using the dentures, the craniomandibular angles of the patients obviously decreased. (P < 0.05).

CONCLUSIONThe shift of NHP after denture inserting does exist. The shifted NHP of the patients with dentures is a new balanced posture and closer to the normal position than the NHP of them without dentures.

Adult ; Aged ; Aged, 80 and over ; Cephalometry ; methods ; Denture, Complete ; Female ; Head ; physiopathology ; Humans ; Male ; Mandible ; physiopathology ; Middle Aged ; Mouth Rehabilitation ; methods ; Mouth, Edentulous ; physiopathology ; rehabilitation ; Neck ; physiopathology ; Posture

OBJECTIVETo measure passive tactile threshold of natural teeth in six orthogonal orientations, to analyze impact factors, and to guide the occlusal adjustment in a personalized manner.

METHODSThe passive tactile thresholds of 218 natural teeth from 20 healthy subjects were measured in six orthogonal orientations using a digital test system for tactile function of teeth. The subjects were composed of 10 males and 10 females, with a mean age of 25 years. The natural teeth were tested from central incisors to first molars in maxilla and mandible. The passive tactile thresholds of teeth were measured respectively in the four horizontal orientations of labial (buccal), lingual, mesial and distal, and the two axial orientations of apical and coronal. The multilevel modeling (MLM) was used to analyze impact factors.

RESULTSThe passive tactile thresholds of anterior teeth, premolars and molars were 16 (18), 38(57) and 105 (115) mN respectively. The difference between subjects was of statistical significance (P < 0.05). The three factors of tooth, gender and orthogonal orientation were disclosed to influence the passive tactile threshold of natural teeth (P < 0.01). The influence level of the factors was tooth > gender > orthogonal orientation.

CONCLUSIONSA force level of 10 mN could be detected by natural teeth. There was statistical difference in the passive tactile threshold between subjects. The passive tactile threshold was affected with tooth, gender and orthogonal orientation.

Adult ; Bicuspid ; Cuspid ; Female ; Humans ; Incisor ; Male ; Mandible ; Maxilla ; Molar ; Mouth, Edentulous ; Sex Factors ; Tooth ; physiology ; Tooth Crown ; Touch

OBJECTIVETo explore a fabricating method of incisor all-ceramic cantilevered resin-bonded fixed partial denture (RBFPD) and evaluate their clinical performances.

METHODSAll-ceramic cantilevered RBFPDs were made to replace 1 missing incisor in each of 10 patients. The RBFPDs with lingual surface retainer were made of Empress II ceramic materials and luted with resin cement. The prostheses were examined at 2 weeks, 1 year and 2 years after denture insertion. Examining criteria included: fracture of bridge, marginal adaptation, secondary caries, and color match.

RESULTSThe average follow-up period was 14. 7 months. No framework fracture and retainer debonding were observed and marginal adaptation was evaluated as good. Seven RBFPDs matched the color of adjacent teeth, and other three did not match well but within the acceptable range of tooth shade difference.

CONCLUSIONSThe results of this preliminary study suggest that the clinical performances of all-ceramic cantilevered RBFPDs are good in short-term evaluation, but their long-term success needs to be further investigated.

Adult ; Denture, Partial, Fixed ; Denture, Partial, Fixed, Resin-Bonded ; Female ; Follow-Up Studies ; Humans ; Incisor ; Male ; Young Adult

OBJECTIVETo compare the difference of stress distribution among models with different fiber frameworks.

METHODSFour models were generated in Marc 2003 software. Four types of loads simulating normal mastication were selected. The stress within models was calculated, and output by means of graph and data.

RESULTSThere was stress concentration around connectors and retainers near connectors under cusp -fossa load, occlusal even load, and lateral load. When dentures were reinforced with fiber framework, area of stress concentration and principal stress max could decrease in comparison with pure composite resin bonded fixed partial denture. Under buccal-lingual load, there was another stress concentration around central fossa beside above two stress concentration areas. Only modified fiber framework constructed with both mesial-distal and lingual-buccal directional glass fiber could markedly reduce principal stress under buccal-lingual cusp loads.

CONCLUSIONUnder 4 types of loads simulating normal mastication, three critical regions were disclosed at the area of retainers adjacent connectors, connectors and occlusal central fossa and fissures. Only modified fiber framework constructed with both mesial-distal and lingual-buccal directional glass fiber could markedly reduce stress concentration under buccal-lingual cusp loads.

Composite Resins ; Denture Design ; Denture, Partial, Fixed, Resin-Bonded ; Glass