The Relationship Between Vibration Frequency And The Stability Of Fiber Post After Bonding

The modulus of fiber post is similar to the dentin. The fiber post is widely used inprosthodontics because of its beauty and simple. With the widely use of fiber post, the lossof fiber post also appears to increase, especially in some teeth which have too much defector the root is too short. It is difficult to estimate the long term effect on the restoration.Thus, it is necessary to search an evaluation to assess the stability and the long term effectof fiber post. In order to guide the retention and maintenance of residual crown and root.Study on the adhesive properties of fiber post were mainly in adhesive material andbond strength between the bonding interface. The study of bond strength mainly usedmethods of micro tensile and push out test to measure loss or fracture strength. It cannotbe used for monitoring the function of fiber post after bonding. The overall stability ofpost and core system has not been reported. The vibration system includes fiber post, resinadhesive and dentin. The vibration occurs when the external excitation appears. It can useresonance frequency to reflect the osteogenesis around the implant has been reported.There are also a lot of reports about using tooth vibration frequency to reflect theperiodontal status. But the research of fiber post vibration frequency has not been reported.The vibration frequency of fiber post has a close correlation with length of root canal, diameter of root canal and fatigue loading. The post and core system has the naturalfrequency when the conditions are the same. It has not been reported about usingvibration frequency to reflect the stability of post and core system.Single rooted teeth with different lengths or diameters of root canal and differentload times are selected as subjects. Analysis of the relationship between vibrationfrequency and diameter and length of root canal, fatigue life by measuring vibrationfrequency and bond strength. To study the feasibility and accuracy of vibration frequencyas a indicators to reflect the bonding state. In order to provide the theoretical basis formonitoring the stability of fiber post.The study includes four parts.1. The relationship between vibration frequency and stability of post after bongding60plexiglass specimen were selected as subjects. The vibration frequency and thebond strength were measured in different diameters and lengths of canal. In order todiscuss the feasibility of the vibration frequency method.The results show that: When the diameter of canal increased from1.8mm to3.8mm,the vibration frequency decreased from649Hz to270Hz, the bond strength decreased from65MPa to14MPa. When the length of canal increased from5mm to9mm, the vibrationfrequency increased from450Hz to673Hz, the bond strength increased from49MPa to72MPa. It explains that vibration frequency are most assoclated with the diameter andlength of canal. Vibration frequency can reflect the function of fiber post after bonding.2. Effect of root canal diameter on the vibration frequency of fiber post24single rooted teeth were prepared by drills as specimens with the canal length of7mm, the diameter varing from1.0mm,1.2mm,1.4mm,1.6mm. To study the relationshipbetween canal diameter and vibration frequency and bond strength by testing them.The results show that: When the root canal diameter increased from1.0mm to1.6mm, vibration frequency decreased from515Hz to299Hz, bond strength decreasedfrom212MPa to51MPa. That may indicate there was a negative correlation between rootcanal diameter and vibration frequency and bond strength. It reflects that reduction instability of fiber post by removing too much dental tissues should be avoided in clinical. 3. Effect of root canal length on the vibration frequency of fiber post24single rooted teeth were prepared by drills as specimens with the canal diameterof1.0mm, the length varing from5mm,6mm,7mm,8mm,9mm. To study the relationshipbetween canal diameter and vibration frequency and bond strength by testing them.The results show that: When the root canal length increased from5mm to9mm,vibration frequency increased from303Hz to643Hz, bond strength increased from86MPato132MPa. That may indicate there was a positive correlation between root canaldiameter and vibration frequency and bond strength. It reflects the proper increase of rootcanal length can improve the stability of fiber post.4. The relationship between vibration frequency and fatigue life of fiber post afterbonding24single rooted teeth were prepared by drills as specimens with the10N loadedvaring from500times,1500times,2500times,4000times. To study the relationshipbetween loading times and vibration frequency and bond strength by testing them.The results show that: When the loading times increased from500times to4000times, vibration frequency decreased from564Hz to361Hz，bond strength decreasedfrom78MPa to22MPa. That may indicate there was a negative correlation between rootloading times and vibration frequency and bond strength. It reflects vibration frequencycan be used to monitor the long term effect of fiber post after bonding and forecast theworking life.