Comparison of osseointegration in piezoimplants versus cylindrical implants

BACKGROUND: Dental implants have been successful for the restoration of edentulous areas, but current techniques are inadequate in areas lacking sufficient bone volume. Piezoelectric surgery has shown encouraging effects on both osseous healing. A new wedge-shaped titanium PiezoImplant requires piezoelectric osteotomy. This study compares PiezoImplants to conventional threaded cylindrical shaped implants by microcomputed tomography and histology to assess osseointegration, tissue response, and alveolar ridge changes. METHODS: After 3 months post-extraction, 18 conventional cylindrical implants and 18 wedge-shaped PiezoImplants were placed using a split-mouth design in 3 adult mini pigs. The cylindrical implant sites were prepared for osteotomy with rotary instrumentation while the PiezoImplant sites were prepared with piezoelectric surgical inserts. One animal was sacrificed at 4, 8, and 12 weeks post operation. Quantitative µCT and histological analysis evaluated bone volume, osseointegration, and post-operative cellular events. RESULTS: The results of a multivariable linear regression model demonstrated that the PiezoImplants, arch location, and time were significant factors on higher BV/TV percentage. Bone to implant contact (BIC) analysis by high resolution microscopy and histomorphometry indicated osseointegration though intimate contact between implants and adjacent alveolar bone in both groups. The tissue response displayed no evidence of abnormal healing and the PiezoImplant was classified as a non-irritant. CONCLUSION: The combination of piezoelectric osteotomy and newly designed PiezoImplants had favorable effects on wound healing and osseointegration compared to conventional cylindrical implants. These novel wedge-shaped implants may be beneficial for narrow ridge spaces without additional ridge augmentation. Further research is needed to establish clinical validity

A Bayesian Incentive Compatible Mechanism for Fair Division

We consider the problem of fairly allocating one indivisible object when monetary transfers are possible, and examine the existence of Bayesian incentive compatible mechanisms to solve the problem. We propose a mechanism that satisfies envy-freeness, budget balancedness, and Bayesian incentive compatibility. Further, we establish the uniqueness of the mechanism under an order additivity condition. This result contrasts well with various results on the incompatibility between efficiency and ex post incentive compatibility.

Secure Implementation in Shapley-Scarf Housing Markets

This paper considers the object allocation problem introduced by Shapley and Scarf (1974). We study secure implementation (Saijo, Sjostrom, and Yamato, 2007), that is, double implementation in dominant strategy and Nash equilibria. We prove that (i) an individually rational solution is securely implementable if and only if it is the no-trade solution, (ii) a neutral solution is securely implementable if and only if it is a serial dictatorship, and (iii) an efficient solution is securely implementable if and only if it is a sequential dictatorship. Furthermore, we provide a complete characterization of securely implementable solutions in the two-agent case.

Secure Implementation in Shapley-Scarf Housing Markets

This paper considers the object allocation problem introduced by Shapley and Scarf (1974). We study secure implementation (Saijo, Sjöström, and Yamato, 2007), that is, double implementation in dominant strategy and Nash equilibria. We prove that (i) an individually rational solution is securely implementable if and only if it is the no-trade solution, (ii) a neutral solution is securely implementable if and only if it is a serial dictatorship, and (iii) an efficient solution is securely implementable if and only if it is a sequential dictatorship. Furthermore, we provide a complete characterization of securely implementable solutions in the two-agent case.ISER discussion paperDecember 2008 Revised February 200

On Group Misfiring in Series Circuit Electric Blasting

In an electric blasting circuit where a large number of electric detonating caps are hooked up in a straight series, several instances have been reported in which a group of detonating caps situated in the vicinity of the middle part of the circuit were apt to misfire, and the cause of this kind of misfire has been ascribed to the leak of igniting current. Every misfire will ultimately be traceable to the lack of the amount of electric power given to the detonating cap, while in this paper, to account for one of the factors leading to the cause of such misfire, the time required for the progressing current wave to arrive at the middle part of the circuit and also the gradual decay of the intensity of current during the transition are investigated. Consequently, the intensity-time curves of igniting current and the amount of accumulated heat energy for detonating caps placed at the middle part and both ends in the circuit were studied and discussed under several feasible circuit conditions, and next, it was suggested that both the higher and the lower limits of the intensity of igniting current should be considered in order to reduce the possibility of misfire in such situations

Inspection of Internal Impairments of Steel Wire Rope by Electromagnetic Detecting Method

In this paper, to contribute to the development and the practice of the electromagnetic inspection of the internal impairments of steel wire ropes, the method which was employed in this study and the results of some fundamental experiments are stated. The outline of some field inspections which were carried out with the trial equipment are shown, and the result of the visual inspection obtained by breaking up an actual rope and the electromagnetic inspection record of the identical part are correlated and discussed. Further, the procedure of estimation of present strength of a wire rope by electromagnetic inspection are stated. Taking this procedure, we can estimate the present strength with reasonable high accuracy, and it has been recognized that the electromagnetic inspection is an effective method for the good maintenance of steel wire ropes

On the Electromotive Force and the Electric Conductivity Accompanied with the Detonation of Explosives

The electromotive force and the electric conductivity in the ionized gases produced by the detonation of Sakura dynamite were investigated in this study. This investigation was carried out to obtain several fundamental data for developing a method by which the detonation rate of an explosive could be estimated. As to the electromotive force, the maximum values ranging from 1V to 2V were obtained and these electromotive forces were generally observed in the negative signal against the ground. In the majority of records, between 10 micro-seconds and 20 micro-seconds after detonation, the conductivity was observed to attain to its stationary value which was ranged from 5×lO⁻² mho/cm to 30×l0⁻² mho/cm