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Objective: To investigate the effect of porous surface morphology of zirconia on the proliferation and differentiation of osteoblasts., Methods: According to different manufacturing and pore-forming methods, the zirconia specimens were divided into 4 groups, including milled sintering group (M-Ctrl), milled porous group (M-Porous), 3D printed sintering group (3D-Ctrl) and 3D printed porous group (3D-Porous). The surface micromorphology, surface roughness, contact angle and surface elements of specimens in each group were detected by scanning electron microscope (SEM), 3D laser microscope, contact angle measuring device and energy-dispersion X-ray analysis, respectively. MC3T3-E1 cells were cultured on 4 groups of zirconia discs. The cell morphology of MC3T3-E1 cells on zirconia discs was eva-luated on 1 and 7 days by SEM. The cell proliferation was detected on 1, 3 and 5 days by cell counting kit-8 (CCK-8). After osteogenic induction for 14 days, the relative mRNA expression of alkaline phosphatase ( ALP ), type Ⅰ collagen ( Colla1 ), Runt-related transcription factor-2 ( Runx2 ) and osteocalcin ( OCN ) in MC3T3-E1 cells were detected by real-time quantitative polymerase chain reaction., Results: The pore size [(419.72±6.99) μm] and pore depth [(560.38±8.55) μm] of 3D-Porous group were significantly larger than the pore size [(300.55±155.65) μm] and pore depth [(69.97±31.38) μm] of M-Porous group ( P < 0.05). The surface of 3D-Porous group appeared with more regular round pores than that of M-Porous group. The contact angles of all the groups were less than 90°. The contact angles of 3D-Ctrl (73.83°±5.34°) and M-Porous group (72.7°±2.72°) were the largest, with no significant difference between them ( P >0.05). Cells adhered inside the pores in M-Porous and 3D-Porous groups, and the proliferation activities of them were significantly higher than those of M-Ctrl and 3D-Ctrl groups after 3 and 5 days' culture ( P < 0.05). After 14 days' incubation, ALP , Colla1 , Runx2 and OCN mRNA expression in 3D-Porous groups were significantly lower than those of M-Ctrl and 3D-Ctrl groups ( P < 0.05). Colla1 , Runx2 and OCN mRNA expressions in M-Porous group were higher than those of 3D-Porous group ( P < 0.05)., Conclusion: The porous surface morphology of zirconia can promote the proliferation and adhesion but inhibit the differentiation of MC3T3-E1 cells.

Objective: To investigate the influence of chronic masseter hyperalgesia induced by 17β-estradiol (E2) and experimental occlusal interference (EOI) on underlying mechanism in hippocampus of ovariectomized (OVX) rats., Methods: In the study, 32 OVX rats were randomly divided into 4 groups (8 rats/group): The control group was OVX group, and 0 μg/d E2 (vehicle) injection was started 7 d after OVX without EOI; in the experimental group (1) OVX + E2 group, 80 μg/d E2 injection was started 7 d after OVX without EOI; in the experimental group (2) OVX + EOI group, vehicle injection was started 7 d after OVX and EOI was applied 17 d after OVX; in the experimental group (3) OVX + E2 + EOI group, 80 μg/d E2 injection was started 7 d after OVX and EOI was applied 17 d after OVX. Bilateral masseter muscle mechanical withdrawal thresholds were measured before OVX, 7 days after OVX (before E2 injection), 17 days after OVX (10 days after E2 injection and before EOI) and 24 days after OVX (7 days after EOI). Immunofluorescence staining was used to reveal phospho-extracellular signal regulated kinase 1/2 (p-ERK1/2)-positive neurons in CA3 of hippocampus. The protein expression of p-ERK1/2 in hippocampus was detected using Western Blot., Results: Compared with the control group [left side: (135.3±8.5) g, right side: (135.4±10.8) g], bilateral masseter muscle mechanical withdrawal thresholds of OVX+E2 group [left side: (113.3±5.6) g, right side: (112.5 ± 5.6) g] and OVX+EOI group [left side: (93.3±5.4) g, right side: 90.8±5.5) g] were decreased ( P < 0.01). Bilateral masseter muscle mechanical withdrawal thresholds were significantly lower in OVX+E2+EOI group [left side: (81.2±6.2) g, right side: 79.8±7.7) g] than in the control, OVX+E2 and OVX+EOI groups ( P < 0.05). The proportion of p-ERK1/2 positive neurons in the CA3 region of the hippocampus was increased in the control, OVX+E2, OVX+EOI and OVX+E2+EOI groups in turn, and the difference between the groups was statistically significant ( P < 0.05). p-ERK1/2 protein expression was increased in the control, OVX+E2 and OVX+EOI groups in turn, but the difference was not statistically significant ( P >0.05). p-ERK1/2 expression was significantly higher in OVX+E2+EOI group than in the other three groups ( P < 0.05)., Conclusion: High concentration of E2 could exacerbated EOI-induced chronic masseter hyperalgesia in ovariectomized rats, and its central mechanism may be related to the upregulation of the phosphorylation of ERK1/2 in hippocampus.

Objective: To establish the workflow of determining the jaw position of repositioning splint with the aid of digital technique, and to evaluate the accuracy of this workflow and compare the accuracy of raising different vertical dimensions in vitro ., Methods: A volunteer was recruited. The data of full-arch scans, cone beam computed tomography (CBCT) image and ultrasonic jaw motion tracking of the volunteer were acquired. The full-arch scans were merged with the CBCT image, which were then matched to the jaw motion tracking reference system. The jaw position of repositioning splint was determined when the anterior teeth opening was 3 mm and the condyle was in centric relation of the fossa in the sagittal plane. A digital repositioning splint was designed in the software based on virtual articulator and fabricated with additive manufacturing technique. After the splint was tried in, another CBCT image was taken and a qualitative analysis was conducted to compare the position of condyle between these two CBCT images. In the in vitro study, standard dental plaster casts with resin ball markers attached to the base were mounted onto a fully adjustable articulator in the intercuspal position. The dental casts were scanned by an extraoral scanner to establish digital models. The ultrasonic jaw motion tracking device was used to obtain simulated jaw movements on the articulator, which was repeated for three times. The digital models and data of jaw movements were merged in one coordination with the aid of bite forks. The jaw position of repositioning splint was determined by adjusting data of jaw movements, each of which was used to determine three vertical jaw positions 4 mm, 5 mm, and 6 mm with the horizontal jaw position of protrusion 2 mm. The virtual articulators with differently adjusted jaw movements were applied in designing repositioning splints, and the final repositioning splints and virtual jaw relationships were exported in STL format. Then the repositioning splints were fabricated with additive manufacturing technique and tried in plaster casts on the mechanical articulator, which were scanned and the jaw relationships on the mechanical articulator were exported later. The virtual jaw relationships and scanned jaw relationships were registered according to lower models and displacement of upper models was calculated. Ball markers were fit to acquire the coordinates of centers and absolute difference values of centers along three coordinating axes X , Y , and Z were calculated. One-way analysis of variance was conducted using SPSS 18.0 software to compare deviations of the three different vertical jaw relationships in two-side test and the significance level was 0.05., Results: With the aid of multi-source data fusion and individualized jaw motion, the clinical workflow of determining jaw position of repositioning splint was preliminarily established. The designed jaw position was realized on the right and the condyle was more inferior than the designed position on the left. Both displacement of the upper models and absolute difference values of centers showed no significant differences ( P >0.05) in different vertical jaw dimensions. The displacement of the upper models was (0.25±0.04) mm. The absolute difference values of centers along the three coordinating axes X , Y , and Z were respectively (0.08±0.01) mm, (0.30±0.02) mm, and (0.21±0.04) mm., Conclusion: A novel method of determining the jaw position of repositioning splint with the aid of digital technique is established. It is proved to be feasible by try-in after multi-data fusion, computer-aided design and computer-aided manufacturing. As is shown in vitro , it is accurate to apply this method in adjusting jaw position. Further clinical trial will be designed to evaluate its clinical effect.

Objective: To establish a method for the production of digital individual tooth tray based on three-dimensional (3D) scan, computer-aided design (CAD) and 3D printing, and to evaluate the effect of impression taking of full-arch crown abutments by digital individual tooth tray technique and conventional method through in vitro study., Methods: The full crown preparation was performed on all the fourteen resin teeth in a standard model of mandibular dentition. The surface data of prepared abutments was collected by 3D scanning. A new project was created in a dental CAD software including all the fourteen teeth in the mandibular dentition. The design modules of anatomy crown and coping were selected for each tooth. The dentition was divided for three sections: right posterior teeth, anterior teeth, and left posterior teeth areas. The connector design was added between the abutments within the same section. The scanned data of the abutments were imported. The occlusal plane and insertion path were determined. The position of margin line, as well as the shape of anatomy crown and connector as the main body of the individual tooth tray were designed for each abutment. The shape of coping was generated as the space for holding the impression material. The finalized data of the main body was imported into Geomagic software. The retentive attachment was added at the external surface and the tissue stop was formed at the internal surface. The completed individual tooth tray was manufactured by 3D printing with resin material. The data of full-arch crown abutments were modified and printed. The conventional dentition trays A and B, as well as digital individual tooth tray were designed and printed for four copies each. The polyether impressions of the full-arch abutments were made by conventional one-step method using dentition tray A, and by sectional-impression technique using digital individual tooth tray and dentition tray B for four times each. The time spent for each impression taking and the numbers of defects at the shoulder and axial/occlusal surface in each impression were recorded. The impression quality of each abutment was evaluated. The overall quality distribution and the pass rate of abutments between the two methods were analyzed., Results: The impressions made by conventional method had more defects at shoulder than those made by digital individual tooth tray technique. No difference of the number of defects at axial/occlusal surface between the two methods was observed. The digital individual tooth tray technique for the full-arch abutment impression exhibited higher pass rate of abutments and better quality of impression, compared with conventional methods., Conclusion: A new method for the production of digital individual tooth tray based on digital scanning, CAD and 3D printing was established. Compared with conventional method, using digital individual tooth tray technique for impression taking of full-arch abutments can achieve better effect.

Objective: To compare the orofacial pain sensitivity with operant test and mechanical hyperalgesia with von Frey filaments of two orofacial pain models (EOI: experimental occlusal interference; pIONX: partial infraorbital nerve transection). To investigate the operant and evoked characteristics of EOI-rats., Methods: The orofacial operant behaviors were tested by Ugo Basile Orofacial Stimulation Test System. The mechanical thresholds of vibrissal pads were tested by von Frey filaments. Male Sprague-Dawley rats were randomly divided into eight groups: von Frey group: sham-EOI, EOI, sham-pIONX, pIONX (sham: sham-operated group); operant test group: sham-EOI, EOI, sham-pIONX, pIONX (sham: sham-operated group). The mechanical thresholds and orofacial operant behaviors were tested on pre-operation and post-operation days l, 3, 7, 10, 14 and 21., Results: In pIONX of von Frey group, the mechanical withdrawal threshold decreased from days 1 to 21 (P<0.05), peaking from days 7 to 10, and lasted until the end of the experiment. There was no significant difference between the bilateral sides. In pIONX of operant test group, the total contact time decreased from days 10 to 21 (P<0.05), peaking from days 10 to 14, and lasted until the end of the experiment. In EOI of von Frey group, the mechanical withdrawal threshold decreased from days 3 to 21 (P<0.05), peaking on day 7, and lasted until the end of the experiment. There was no significant difference between the bilateral sides. In EOI of operant test group, the total contact time decreased from days 1 to 21 (P<0.05), peaking from days 7 to 10, and lasting until the end of experiment., Conclusion: Orofacial operant test is a stable method to evaluate orofacial pain behaviors, which could discriminate the feature of neuropathic and EOI orofacial pain. In these two animal models, both of the operant behaviors and the mechanical hyperalgesia exhibited different time courses. Orofacial operant test provides a novel method for evaluating the orofacial pain sensitivity and studying the orofacial pain mechanism thoroughly.

Objective: To analyze changes in occlusal force distribution and occlusal contact in posterior partial fixed implant-supported prostheses over time, and to provide reference for the precise occlusion design, adjustment and maintenance of implant prostheses., Methods: According to certain inclusion and exclusion criteria, patients were recruited from partially edentulous patients who had received implant-supported single crown or fixed bridge in the posterior region. The patients were collected since the implant prostheses settling and scheduled for the routine examination of implant prostheses and the occlusal examinations of complete dentition after 2 weeks, 3, 6, and 12 months. Occlusal examinations were taken with the articulating papers and T-Scan III (Tekscan, South Boston, USA), which could check and measure the occlusal contact condition of complete dentition. The occlusion time and relative occlusal forces of implant prostheses, mesial adjacent teeth and control teeth were recorded at the same time., Results: Thirty-seven posterior partial fixed implant prostheses in 33 patients (17 women and 16 men, aged 24-70 years) were followed up for 3-12 months (average 8.3 months). At baseline, the relative occlusal forces of implant prostheses were significantly lower than those of the corresponding control teeth (P<0.001). However, after 3 months, the relative occlusal forces of implant prostheses had significantly increased (P<0.05), while control teeth decreased significantly (P<0.05), resulting in no statistical significance between them. The implant prostheses occlusion time ratio also increased significantly from 2 weeks to 3 months (P<0.05). There was no significant difference from the third month to the sixth month, or from the sixth month to the twelfth month (P>0.05)., Conclusion: Light contact and time-delayed occlusion of posterior implant prostheses changes significantly in the first three months after settling implant prostheses. These changes mainly include the advance of the time point of the implant prosthesis to start the occlusion contact, and the increase of the occlusal force of the implant prosthesis. The occlusion of posterior implant prostheses should be carefully monitored at end of the third month follow-up clinically.

Objective: To investigate the effect of long-term resistance exercise of hindlimb on mechanical hyperalgesia of bilateral masseter muscle in rats with or without occlusal interference., Methods: Six-teen male Sprague-Dawley rats (220-250 g) were randomly divided into four groups: the naive control group, naive exercise group, occlusal interference control group, and occlusal interference exercise group. The rats in occlusal interference groups (occlusal interference control group and occlusal interference exercise group) obtained occlusal interference with 0.4 mm-thick crowns bonded to the right maxillary first molars. The rats in exercise groups (naive exercise group and occlusal interference exercise group) performed squat-type resistance exercises for 30 minutes, once a day, 5 days/week, lasting for 14 weeks. Resistance exercise was recorded every day. Mechanical withdrawal thresholds of bilateral masseter muscle were tested per week by use of modified electronic von-frey anesthesiometer. The rats were weighed per week. After the 14-week exercise, the muscle strength of the hindlimb was tested with a grip strength meter. Muscle (gastrocnemius and soleus) weight of bilateral hindlimb and length of bilateral fibula of the rats were obtained. The muscle-mass/body-mass ratios and muscle-mass/fibula-length ratios were calculated., Results: Between the naive control group and naive exercise group, there was no significant difference in the mechanical withdrawal thresholds of bilateral masseter muscle for the 0-4 weeks (P>0.05). During the 5-14 weeks, the mechanical withdrawal thresholds of the rats in the naive exercise group were higher than those in the naive control group (P<0.05). Between the occlusal interference control group and occlusal interference exercise group, there was no significant difference in the mechanical withdrawal thresholds of bilateral masseter muscle for the 0-6 weeks (P>0.05). During the 7-14 weeks, the mechanical withdrawal thresholds of rats in the naive exercise group were higher than those in the occlusal interference control group (P<0.05). After the 14week exercise, the body mass of the rats in nonexercise group (the naive control group and occlusal interference control group) were larger than those in exercise group [(462±6) g vs. (418±14) g, P<0.05]. And the muscle strength of hindlimb of the rats in exercise group were bigger than those in non-exercise group [(6.75±0.13) N vs. (5.41±0.15) N, P<0.01]., Conclusion: long-term resistance exercise can increase mechanical withdrawal thresholds of the bilateral masseter muscle in rats with or without masseter muscle mechanical hyperalgesia.

Objective: To investigate the effect of occlusal interference on the energy metabolism of masticatory muscle by studying the changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), inosine monophosphate (IMP), phosphocreatine, creatine, lactate and pH level in masseter muscles of rats after occlusal interference., Methods: Fifty male Sprague-Dawley rats were randomly assigned into experimental group (n=40) and control group (n=10). In experimental group, 0.4 mm thick metal crown was cemented to the upper right first molar of the rat, and maintained for 3, 7, 10, 14 d separately (n=10 for each time point). No occlusal interference was applied for control group. Bilateral masseter muscles of all the rats were acquired under general anesthesia. The samples of 5 rats in each group were fully homogenized with 0.4 mol/L perchlorate (10 mL/g). The homogenates were centrifuged, filtered and analyzed for ATP, ADP, IMP, phosphocreatine, creatine and lactate content by high performance liquid chromatography. The other samples in each group were mixed with homogenates containing 5 mmol/L sodium iodoacetate (10 mL/g), then homogenized and measured for pH value by pH meter in thermostatic water bathunder 37 degrees centigrade., Results: Compared with control group, ATP content in bilateral masseter of the rats increased 3 d after occlusal interference [right side:(5.36±0.13) μmol/g,left side:(5.77±0.25) μmol/g] (P<0.05), and back to normal on 7, 10 and 14 d. There was an increase in IMP [right side:(0.21±0.03) μmol/g,left side:(0.19±0.03) μmol/g]and creatine content [right side:(24.76±2.94) μmol/g,left side:(27.75±2.23) μmol/g]in bilateral masseter of the rats 7 d after occlusal interference (P<0.05) and no difference was detected on 3, 10, and 14. Phosphocreatine content in bilateral masseter started to decline 7 d after occlusal interference and maintained the low level on 10 and 14 d [right side:(10.70±0.71) μmol/g, (11.57±0.52) μmol/g, (10.74±1.39) μmol/g, left side:(10.05±0.57) μmol/g, (10.75±1.12)μmol/g, (10.61±1.15) μmol/g](P<0.05). No change of ADP, lactate or pH level in bilateral muscles of the rats after occlusal interference was observed (P>0.05)., Conclusion: Occlusal interference influences the content of energy metabolites in masticatory muscle of rats, which may be related to the pathological process of masticatory muscles induced by occlusal interference, such as muscle pain, dysfunction and altered fiber architecture.

Objective: To evaluate the effect of the occlusal surface height of a mandibular posterior implant-supported single crown on stress in bone tissues., Methods: Three-dimensional finite element models of the implant-supported single crown replacing the missing right lower second premolar, mesial and distal natural teeth, periodontal membrane, alveolar bone, loaded rigid body and analog food of almond were established. Using the Federation Dentaire International (FDI) system, the first premolar, the second premolar and the first molar were represented with 44, 45, 46. Three occlusal surface heights of the crown were studied: (1) normal height; (2) 15 μm reduction in height; (3) 30 μm reduction in height. The models were loaded by independent loading with maximal occlusal force(44 by 280 N, 45 by 360 N, and 46 by 480 N) and average occlusal force(44 by 140 N, 45 by 180 N, and 46 by 240 N)on the single crown; combined loading (maximal occlusal force transformed into uniform load of 3.7 MPa on top of rigid body, in contact with points on the occlusal surface), and analog almond-like food loading (average occlusal force transformed into uniform load of 1.67 MPa in simulated food chewing, in contact with points on the occlusal surface)., Results: For maximal biting force under independent loading, Von Mises stress peak values in bone tissues around 44, 45, and 46 were 82.57 MPa, 45.26 MPa and 27.79 MPa; For average biting force, peak values were 41.28 MPa, 22.63 MPa and 13.89 MPa. Under combined loading, compared with the normal occlusal surface height group, Von Mises stress peak values decreased 4.6 MPa, by 0.84%; increased 7.52 MPa, by 20.04%, and decreased 1.8 MPa, by 5.84%, for 45, 46, and 44 in the 30 μm infra-occlusion group, respectively. Under food loading, Von Mises stress peak values decreased 0.34 MPa, by 1.62%; increased 1.11 MPa, by 2.66%; and increased 0.06 MPa, by 0.54%, and for 45, 46, and 44 in the 30 μm infra-occlusion group, respectively., Conclusion: Within the limitation of this study, within 30 μm reduction of the occlusal surface height of implant-supported single crown, no significant difference of the peak values was observed.

Objective: To investigate the relationship between the removal time of 0.2 mm occlusal interference and the recovery of masticatory muscle mechanical hyperalgesia in rats., Methods: Forty male Sprague-Dawley rats (200-220 g) were randomly assigned to eight groups, with five rats in each group: (1) naive group: these rats were anesthetized and their mouths were forced open for about 5 min (the same duration as the other groups), but restorations were not applied; (2) sham-occlusal interference control group: bands were bonded to the right maxillary first molars which did not interfere with occlusion; (3)occlusal interference group: 0.2 mm thick crowns were bonded to the right maxillary first molars; (4) 2, 3, 4, 5, and 6 d removal of occlusal interference groups: 0.2 mm thick crowns were bonded to the right maxillary first molars and removed on days 2, 3, 4, 5, and 6. The naive group and sham-occlusal interference control group were control groups. The other groups were experimental groups. Bilateral masticatory muscle mechanical withdrawal thresholds were tested on pre-application days 1, 2, and 3, and on post-application days 1, 3, 5, 7, 10, 14, 21 and 28. The rats were weighed on pre-application day 1 and on post-application days 1, 2, 3, 4, 5, 6, and 7., Results: Between the naive group and the sham-occlusal interference control group, there was no significant difference in the masticatory muscle mechanical withdrawal threshold of bilateral temporalis and masseters at each time point. No significant difference was detected between the contralateral side and ipsilateral side in experimental groups (P>0.05). In the 2, 3, 4, and 5 d removal of occlusal interference groups, the masticatory muscle mechanical withdrawal thresholds decreased after occlusal interference and increased after removal of the crowns and recovered to the baseline on days 7, 10, 14, and 14, respectively [the masticatory muscle mechanical withdrawal thresholds of right masseter muscle were (137.46 ± 2.08) g, (139.02 ± 2.11) g, (140.40 ± 0.98) g, (138.95 ± 0.98) g, respectively]. In the 6 d removal of occlusal interference group, the masticatory muscle mechanical withdrawal threshold increased after removal of the crowns and became stable since day 14. There was a significant difference between the 6 d removal of occlusal interference group and the sham-occlusal interference group on day 28 (P<0.05), the masticatory muscle mechanical withdrawal thresholds of right masseter muscle were (131.24 ± 0.76) g and (141.34 ± 1.43) g, respectively., Conclusion: After removal of the 0.2 mm thick crown within 5 days, the mechanical hyperalgesia of the rats could reverse completely. The mechanical hyperalgesia of the rats could only be relieved, but not reverse completely after removal of the 0.2 mm thick crown on day 6. As the time went on, even minor occlusal interference could cause irreversible mechanical hyperalgesia of masticatory muscles. This study suggested that occlusal interference caused by dental treatment should be eliminated as soon as possible, to avoid irreversible orofacial pain.

Objective: To establish the preliminary somatosensory data stratified by gender, age group, and sites in the trigeminal region through standardized quantitative sensory testing on healthy individuals, and to evaluate the effects of gender, age, and sites on somatosensory functions., Methods: The standardised QST battery developed by the German Research Network on Neuropathic Pain consists totally of 13 different parameters. A total of 70 healthy individuals participated. The subjects were stratified into two groups according to age: younger group (16 female, 16 male, age 24-40 years old) and elder group (20 female, 18 male, age 41-69 years old). The test was performed bilaterally over the infraorbital, mental, and hand regions., Results: The preliminary orofacial somatosensory data stratified by gender, age group, and sites were presented. Female were more sensitive than male for most of the parameters (P<0.05). Age had a significant effect on most of the parameters (P<0.05), the younger group was more sensitive compared with the elder group (P<0.01) for heat pain threshold (HPT): younger group (38.07±2.94) °C, elder group (39.85±3.52) °C; warmth detection threshold (WDT): younger group (1.40±0.74) °C, elder group (1.89±1.14) °C; mechanical detection threshold (MDT): younger group (0.73±1.66) mN, elder group (1.41±2.82) mN; pressure pain threshold (PPT): younger group (171.71±92.51) kPa, elder group (196.36±73.73) kPa; cold pain threshold (CPT): younger group (25.90±5.38) °C, elder group (21.64±6.78) °C; cold detection threshold (CDT): younger group (-0.97±0.55) °C, elder group (-1.36±0.90) °C, and wind-up ratio (WUR): younger group (3.33± 2.20), elder group (2.67±1.68). The inverse results were demonstrated for mechanical pain threshold (MPT): younger group (111.50±88.93) mN, elder group (104.49±94.94) mN; mechanical pain sensitivity (MPS): younger group (6.96±5.61), elder group (8.93±6.53), and vibration detection threshold (VDT): younger group (7.44±0.52) scale, elder group (7.55±0.48) scale (P<0.05). Somatosensory function was site dependent (P<0.001), the two trigeminal sites (infraorbital and mental) were more sensitive than the hand for CDT, HPT, WDT, thermal sensory limen (TSL), MDT, MPT, MPS, and PPT (P<0.001), but the inverse result was observed for VDT (P<0.001)., Conclusion: The preliminary orofacial somatosensory data of Han Ethnicity stratified by gender, age group, and sites were established. The study evaluated the effects of gender, age and sites on orofacial somatosensory functions by employment standardized quantitative sensory testing.

Objective: To evaluate the relationship of incisal point displacements in the mandibular retruded contact position (RCP) between the self-controlled retruded approach and bimanual manipulation method., Methods: Twelve healthy young volunteers were selected. The RCP was guided through the self-controlled retruded approach and bimanual manipulation method. The track of the incisal point was recorded, using the mandibular movement trace recording system. The movement direction of the incisal point in horizontal plane was observed. The distance between the incisal point of the RCP and intercuspal contact position (ICP) was measured., Results: Except one volunteer's incisal point movement direction of the RCP was oblique, others were straight toward posterior. The displacements of the incisal point from the ICP to RCP guided through self-controlled approach and bimanual manipulation method were (1.15 ± 0.64) mm, (0.98 ± 0.29) mm respectively. There was no statistical significance between the two methods (P > 0.05)., Conclusion: The displacements of the incisal point from the ICP to RCP guided through self-controlled approach and bimanual manipulation method are approximately the same.

Objective: To assess the masticatory efficiency and patient' satisfaction in long-centric occlusal pattern complete denture wearers., Methods: The anatomic occlusal pattern and long-centric occlusal pattern complete dentures were made for each of 10 edentulous patients with severe alveolar rigde absorption simultaneously using the technique of interchangeable artificial teeth. The order of delivery of different occlusal pattern complete denture was determined according to randomized principle. For each kind of occlusal pattern complete denture, the masticatory efficiency was measured with spectrophotometer after the dentures were worn 2, 4, 6, 8, 10 and 12 weeks. A psychometric questionnaire was completed by the patients after wearing the dentures for more than three months and analyzing the patients' rating of the denture satisfaction., Results: No significant differences in masticatory efficiency was found between the long-centric occlusal pattern complete denture wearers and the anatomic occlusal complete denture wearers. The patients' grade of denture satisfaction in long-centric occlusal pattern complete dentures wearers was significantly better than that in anatomic occlusal denture wearers (P<0.05)., Conclusion: Complete denture with long-centric occlusion can be used to improve the clinical effect of edentulous patients with severe absorption of residual alveolar rigde.

Objective: To evaluate the protection of calcium alginate hydrogel beads for mouse preosteoblastic cell line (MC3T3-E1) during the setting reaction of calcium phosphate cement (CPC) pastes and to analyze related influencing factors., Methods: The MC3T3-E1 cells encapsulated in alginate hydrogel beads were cultured in vitro with β-tricalcium phosphate/calcium phosphate cement (β-TCP/CPC) pastes and discs until 2 d. The cell viability and number of live/dead cells were tested using the CCK-8, Calcein-AM and PI, respectively. The effects of CPC paste and CPC disc, different treatment and time to renewal medium on cell viability were compared., Results: There were no significant differences in optical density and number of live cells between β-TCP/CPC pastes and discs (1 d: P=0.827; 2 d: P=0.965). There were different influences on cell viability between different treatment and time to renewal medium., Conclusion: The results indicated that the calcium alginate hydrogel beads had a good protection to MC3T3-E1 cells during the setting reaction of CPC pastes. CPC paste might affect the cell proliferation even when solidification. After setting reaction, it may be favorable for cell viability to renew the medium every 6 h in 1 d.

Objective: To evaluate biocompatibility of three kinds of self-developed injectable calcium phosphate cements (CPCs): chitosan microspheres/CPC, β-tricalcium phosphate (β-TCP)/CPC, and K(+)/CPC and the viability of the osteogenic cells cultured with CPC pastes and discs for 10 days., Methods: The rabbit marrow stromal cells (rMSCs), isolated from rabbit bone marrow with density gradient centrifugation and flow cytometer, were cultured, expended and induced into osteoblasts. Alizarin red staining was used to determine the function of ossification. Then, rMSCs were incubated randomly on both the pastes and solidified discs of the 3 kinds of CPCs. The cells cultured on a 24-well plate were as blank control. Each group had 4 samples. The proliferation and differentiation of each group were observed using acid phosphatase assay (APA) and by testing the activity of alkaline phosphatase (ALP) at day 1, 4, 7, and 10. After stained by acridine orange(AO), the cells were observed, counted and analyzed with an epifluorescence microscopy. The morphology of the cells on CPCs was observed with scanning electron microscope(SEM).The data was subjected to two-way ANOVA followed by LSD test to compare between groups., Results: The process of solidification of the three kinds of CPC pastes has the toxic effect on cells, which is irreversible. The proliferation( the average absortion of pastes are 0.049,0.050,0.049; the discs are 0.898,0.867,0.909;P<0.001), function(the average ALP activity of pastes after ten days are 0.775,0.782,0.798 U/g protein; the discs are 49.288,49.631, 49.744 U/g protein;P<0.001) and number of cells(the average number of cells of pastes after ten days are 3.7,3.7,3.7; the discs are 91.1,89.7,93.7;P<0.001) directly exposed to CPC paste significantly decreased compared with those contacting with the discs. By contrast, cells on the three kinds of discs showed better viability, proliferation, and ossification and cell numbers increased obviously with culture days., Conclusion: The process of solidification of the three kinds of CPC pastes has toxic effect on cells. Further study needs to explore a method to protect osteoblasts when seeded into the CPC paste.

Objective: To investigate the peripheral mechanism by studying the histological changes of masseter muscles using HE stains and substance P (SP) and protein gene product 9.5 (PGP9.5) immunohistochemical stains., Methods: Fifteen male Sprague-Dawley were randomly assigned into occlusal interference group (n=12) and control group (n=3). In occlusal interference group, 0.4 mm thick crowns were bonded to the rats' first molar of the maxillary. In the control group, rats were anesthetized and mouths were forced open for about 5 min but restorations were not applied. 1, 5, 10, and 21 d after 0.4 mm occlusal alteration treatment, mechanical pain thresholds of bilateral masseter muscles were quantitatively measured by modified electronic anesthesiometer in control group and occlusal interference group. The rats were euthanized by transcardiac perfusion after deep anesthetization at different time points. The paraffin sections of masseter muscles were made and processed for HE, SP, and PGP9.5 immunohistochemical staining., Results: Decreased head withdrawal threshold to mechanical pressure was detected in masseter muscles on both sides following occlusal interference. Histological stains of masseter muscles presented intact following occlusal interference, and no inflammatory cells were observed in both sides. Intensely stained PGP9.5 was observed at 1 d in occlusal interference groups and maintained until the end of the experiment. SP expression was the most obviously increased at 5 d in both sides and gradually decreased to the level of control., Conclusion: Experimental occlusal interference-induced masticatory muscle pain is associated with peripheral sensitization of nociceptive neurons rather than muscle damage and inflammation.

Objective: To investigate bioactivity, biodegradation, bone conductive properties, and clinical maneuverability of a novel injectable chitosan microspheres/calcium phosphate cement (CPC)., Methods: The bone defect of pi x 4 mmx4 mmx6 mm was made at both thigh bones of 12 rabbits, and experimental material (chitosan microspheres/CPC) or control material (alpha-tricalcium phosphate cement, alpha-TCP) was injected into the defect respectively. The filling situation was evaluated by X-ray 3 days after operation. The rabbits were divided into three groups, four for each group. The samples with chitosan microspheres and the control with alpha-TCP were collected at 8, 16, 24 weeks after operation. Histological examination and scanning electron microscope (SEM) evaluation were performed., Results: The absorption of implants with chitosan microspheres was observed at 8 weeks, and became more apparent at 16 weeks. Different size of cavities were observed in CPC after the degradation of chitosan microspheres. The chitosan microspheres/CPC was dramatically degraded after 24 weeks with a few chitosan microspheres, and new bone replaced the degraded materials. The implants with alpha-TCP were absorbed slowly compared with the chitosan microspheres/CPC. The cavities in alpha-TCP were small., Conclusion: The chitosan microspheres/calcium phosphate cement has the characters of good biocompatible and osteocombinative ability. Compared with the control material, adding chitosan microspheres into CPC could enhance its degradability and facilitate the new bone formation.

Objective: To evaluate diagnostic sensitivity of electroneurography (ENoG) for facial neurotmesis., Methods: The data of 24 patients suffering from facial neurotmesis on one side, having non-emergency operation, and having preoperative records of ENoG were collected. Among the patients, 18 were men and 6 were women, aged from 3 to 55 years (median 28). The duration of injury before ENoG examination was from 1 to 56 days (mean 23.6 days) for them. The electroneurographic examination was carried out for facial nerves on both sides preoperatively. Percentages of evoked potential amplitude reduction on affected sides were calculated according to the value of normal side. The 90% reduction of amplitude was used as a cutting point. The facial neurotmesis was observed during operation. The sensitivity and false negative proportions of ENoG were analyzed., Results: Among the 24 patients with facial neurotmesis, 22 had ENoG amplitude reduction over 90%, and 2 having this reduction less than 90%. The sensitivity and false negative proportions of ENoG in patients with facial neurotmesis were 91.7% and 8.3% respectively., Conclusion: The preoperative ENoG examination is high sensitivity for facial neurotmesis. The patients whose ENoG reduction over 90% should be advised to have a facial neurorrhaphy as soon as possible.