BACKGROUND: Fiber post is widely used in front teeth aesthetic repair, but some defect teeth cannot form ferrule or thick root canal, which resulted in fiber post prosthetic replacement defluxion and a failure of repair. Presently, new-style resin cement had self sticking component, showing good effects in sticking of fiber post. Whether combination of new-style resin cement can repair affected teeth using fiber post deserves further investigation.OBJECTIVE: Through fatigue test, residual flexural strength and scanning electron microscope (SEM) observation to compare the strength of severely weakened roots restored with three resin cements. METHODS: Eighteen intact maxillary central incisors were collected and formed to severely weakened canals at the same size. Three kinds of resin cements were used to restore. Rely X Unicem, Panavia F and Super-Bond C&B resin cement and identical glass fiber post were used. All the specimens were restored using Ni-Cr ceramic crown, and placed on TCML chewing machine that loaded 1 200 000 cycle forces, and the cycle times when failure occurred were recorded. The samples were intact following loading received residual flexural strength testl SEM was employed to observe breakage surface of the samples. RESULTS AND CONCLUSION: Mean cyclic loading was significantly greater in the Super-Bond C&B Group (1 200 000 times) than in the Relyx Unicem Group (640 000 times) and Panavia F Group (550 000 times) (P< 0.05). No significant difference was detected between the Rely X Unicem and Panavia F Groups. Residual flexural strength was 747.99 N in the Super-Bond C&B Group. SEM demonstrated that Super-Bond C&B formed longer resin processes, which were more than other two groups. Results confirmed that Super-Bond C&B demonstrated better results when restoring flared roots with prefabricated glass fiber posts.

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 ??4 mm?4 mm?6 mm was made at both thighbones of 12 rabbits,and experimental material(chitosan microspheres/CPC) or control material(?-tricalcium phosphate cement,?-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 ?-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 degradated after 24 weeks with a few chitosan microspheres,and new bone replaced the degradated materials.The implants with ?-TCP were absorbed slowly compared with the chitosan microspheres/CPC.The cavities in ?-TCP were small.Conclusion: The chitosan microspheres/calcium phosphate cement has the characters of good biocomptable and osteocombinative ability.Compared with the control material,adding chitosan microspheres into CPC could enhance its degradability and facilitate the new bone formation.

Face ; physiopathology ; Humans ; Mouth ; physiopathology ; Pain ; Pain Threshold ; Somatoform Disorders

0.05).The dental plaque detactable rate of abutment teeth was higher than that of the controls(P

砄bjective: To explore an effective method for Electroneurography(ENoG) of facial nerve. Methods: ENoG of 114 normal subjets and 69 patients with traumatic facial nerve injuries were investigated. Latency time(LT), duration time(DT), amplitude(A) and square under the curve(S) were measured in facial muscles when facial nerve was stimulated postauricularly or anteroauricularly. Results: In most facial musles except square muscle of lower lip postauricular stimulation gave longer LT, shorter DT, lower A and smaller S. Conclusion: The postauricular stimulation is effective prior to anteroauricular stimulation for electroneurography of the facial nerve.

Objective:To evaluate diagnostic sensitivity of electroneurography(ENoG) for facial neurotmesis.Methods:The data of 24 patients suffering from facial neuratmesis 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 neuratmesis 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.

Objective:To make a within-subject comparison of masticatory function and pattern between complete denture(CD)and implant-supported overdneture(IOD).Methods: Three edentulous patients volunteered to take part in this test.Each of the patients was rehabilitated with lower CD first and lower IOD later,and with the upper denture of CD.The masticatory efficiency,mandibular movement trace and the surface electromyograph (EMG) of masseters,anterior temporlis and posterior temporlis were measured 3 month after the use of each set of the dentures.Results: With IOD,each patient increased masticatory efficiency,especially when chewing almond.The regulation of chewing cycle,centralization of end traces and occlusal slides of mandibular movement were significantly improved.The electricactivity of masseters,anterior and posterior temporlis all enhanced by means of increasing contract intensity and the rhythm of the mastication was more regular.The muscle activity pattern in two cases transformed from instable to stable,while that of the another patient changed from masseter preponderant pattern to temporlis preponderant pattern.Conclusion: Patients with IOD have a heigher masticatory efficiency,more regular mandibular movement pattern,more effective masticatory muscle contractive pattern and masticatory muscle coordinative pattern than those with CD.

Objective:To investigate varied electromyographic types in the patients with hemimasticatory spasm(HMS).Methods:Surface electromyography was recorded to study electromyographic features of 16 cases with HMS.Results:Spasm was found in mandibular rest position in 2 cases and in tooth contact position in 14 cases.During the involuntary spasm of the 14 cases, motor unit potential could be classified into three types:continuous(8 cases), rhythmic(3 cases) and irregular(3 cases).Conclusion:The electromyographic feature of hemimasticatory spasm is characterized by continuous motor unit potential discharge. The spasm is mostly triggered by tooth contact.

Objective:To investigate the relationship between the removal time of 0.2 mm occlusal in-terference 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 )nave 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 occlu-sion;(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 nave 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 ,3,5,7,1 0,1 4,21 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 nave group and the sham-occlusal interference control group,there was no significant difference in the mastica-tory 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 7,1 0,1 4,and 1 4,respectively [the masticatory muscle mechanical withdrawal thresholds of right masseter muscle were (1 37.46 ±2.08)g,(1 39.02 ± 2.1 1 )g,(1 40.40 ±0.98)g,(1 38.95 ±0.98)g,respectively].In the 6 d removal of occlusal inter-ference group,the masticatory muscle mechanical withdrawal threshold increased after removal of the crowns and became stable since day 1 4.There was a significant difference between the 6 d removal of oc-clusal 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 (1 31 .24 ±0.76 ) g and (1 41 .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 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)1 5 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 1 40 N,45 by 1 80 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 1 3.89 MPa.Under com-bined loading,compared with the normal occlusal surface height group,Von Mises stress peak values de-creased 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 .1 1 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.Con-clusion:Within the limitation of this study,within 30 μm reduction of the occlusal surface height of im-plant-supported single crown,no significant difference of the peak values was observed.