Dai Kawahara

Osseointegration under immediate loading: biomechanical stress-strain and bone formation--resorption.

During the past 10 years, clinicians have used two-piece implants as a one-piece system for immediate loading to accomplish early recovery for function and esthetics. The statistical analysis by the Institute of Clinical Materials demonstrates high survival rates of 92.3 ± 8.3%. Animal experiments of beagle dogs have been carried out to analyze successful conditions of immediate loading according to the dependency of bone formation–resorption upon the biomechanical stress–strain of bone. Histometric investigations clarified that the micromotion of less than 30 &mgr;m at the implant–bone interface did not interfere with the osteogenesis and new bone growth at the implant–bone interface. Bone formation and resorption are discussed from the standpoint of minimum effective strain on living bone.

Studies on the tissue adhesive capability to titanium by dynamic wettability test and cell attachment, in vitro

Abstract To investigate better methods of surface treatment of cleaning and sterilization for a titanium implant, measurements of contact angles to water and the critical surface tension were made and the iniial cell attachment on the treated surfaces of cp titanium was also observed. The results showed that cleaning using acetone, or acetone with 4% hydrofluoric acid treatment, yielded smaller contact angles and high critical surface tension values. On the other hand, treatment of detergent cleaning represented a large contact angle and a low critical surface tension. However, the initial cell attachment did not differ, regardless of these surface treatments and/or sterilization.

New Titanium Alloy of Ti-Fe-O-N for Dental Implant

Ti-6Al-4V alloy (Ti-Al-V) is used in dental implants and artificial hip joints to take advantage of its higher mechanical strength compared to cp Ti. However, the toxicity of vanadium and aluminum in the titanium alloy has been reported by several investigators since 1965. This study was carried out to compare the mechanical properties and the biocompatibility of Ti-Fe alloy (TiX®) to those of conventional metallic implant materials. The mechanical properties of TiX® were measured and compared with cp Ti, Ti-Al-V, SUS316, SUS304, Co-Cr-Mo, and Ag-Sn. The tensile strength of TiX® and Ti-Al-V were greater than those of Co-Cr-Mo, SUS316, and SUS304. The yield point of TiX® was slightly lower than that of Ti-Al-V, but higher than that of cp Ti. These results suggested the mechanical properties of TiX® were superior to those of Co-Cr-Mo, SUS316, and SUS304. To evaluate the biocompatibility, cell culture technique with L929 cells was used to investigate the cell multiplication, and SEM to investigate the morphological change of adhered cells onto TiX®. The cell growth rate of TiX® was slightly higher than those of Ti-Al-V and SUS316. Severe cytotoxicity was observed in Ag-Sn, and mild cytotoxicity in Ti-Al-V, SUS316, SUS304 using gyratory culture method. These results revealed that TiX® is a useful metallic material for wire, plate, porous, and mesh in dental and medical use, because of the favorable biocompatibility and easy fabrication.

Histometric Investigation on Bone Contact and Bone Occupancy around Sapphire Implant

Two-piece implants have became to be mainstream because osteogenesis and osseointegration were disturbed by micromotion at the implant bone interface under the biting stress of mastication [1, 2]. In recent year, two-piece implants have been used as a one-piece implant of single stage for immediate placement and immediate loading to accomplish early recovery of function and esthetics, and the survival rates demonstrated 80 to 100% [3, 4]. Statistical analysis of Institute of Clinical Materials, ICM on 55 immediate loading implants demonstrated high survival rate of 92.3±7.3% for 10 years or more [5]. These high survival rates were performed with recent progress in diagnosis of accurate predictability on bone quantity (morphology) and quality (density). As a inevitable result, one-piece implants of single stage might be revived as a latest implant procedure. Clinical investigations on sapphire screw implants of single stage demonstrated high survival rates of 92.65±8.40% [6, 7]. In this study, histometric measurement on bone contact and bone occupancy to/around the implant surface were carried out for the purpose of analyzing the successful condition of the sapphire screw implant under functional load.

Histometric Analysis on Crestal Bone Loss around Implant Neck

Statistical investigations on single stage implants have clarified high survival rates of 80% or more for 10 years over [1]. Clinical investigations on sapphire screw implants of single stage demonstrated high survival rates of 92.65±8.40% [2, 3]. This study was carried out to clarify causes of crestal bone loss around implants neck by histometric investigation using sapphire screw implants of single stage [4] implanted into monkey’s mandibles and maxillae and compare the crestal bone losses between the both implants loaded and unloaded..

Initial Implant Stability: Clinical Testing Methods and its Evaluation

Introduction Since immediate placement and/or loading procedure was introduced for dental implant, quantitative primary fixture stability measurement has become essential examination to achieve its predictability. Quantitative mobility measurement using PeriotestTM or resonance frequency analysis (RFA) immediately after fixture install, or maximum torque during fixture install surgery have been reported to ensure clinical predictability. However inter-relationships of quantitative values by means of these instruments is still unknown very well. The objective of this study is confirm these parameters interrelationships.

Clinical Characterization of Several Bone Grafting Materials as a Dental Implant Supporting Tissue

Introduction Several bone grafting materials have been designed for site development to achieve durable dental implant supporting tissue preparation, however its individual clinical advantages/disadvantages still remain unknown. Generally speaking, autograft is considered as gold standard to replace localized bone defect in dental implant surgery, but donor site is needed which cause sometime wider wound in different area from dental implant required. According to minimal invasive surgical procedure, several kinds of bone substitutes have been used as dental implant supporting tissue to eliminate further surgical invasion which is considered as more comfortable patient’s satisfaction. However combined application with autograft is still considered as indispensable procedures, because most of all bone substitutes doesn’t have osteoinductivity. The aim of this clinical investigation is to clarify what combined procedure is clinically advantageous, several kinds of clinical approaches using bone substitute were investigated.

An approach to evaluating patch test results

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