Celso Renato de Souza Resende

Mechanical properties, surface morphology and stability of a modified commercially pure high strength titanium alloy for dental implants

OBJECTIVE Commercially pure titanium (cp Ti) and Ti-6Al-4V (Ti G5) alloy have limitations for biomedical application, due to lower mechanical strength and the possibility of ion release, respectively. The purpose of this work was to compare the properties of a modified cp Ti grade 4 (Ti G4 Hard) with those of available cp Ti and Ti G5 alloys. METHODS Bars, discs and dental implants made with Ti G2, G4, G5 and G4 Hard were used. Mechanical tests (tension, compression, hardness and torque) and roughness measurements were performed. Clinical trials were used to evaluate the biological behavior of dental implants made with Ti G4 Hard and Ti G4. RESULTS The results of the mechanical tests showed that the mechanical strength of modified Ti G4 is higher than that of Ti G2, G4 and G5. Scanning electron microscopy analysis showed that modified Ti G4 after etching has better surface morphological features than conventional cp Ti and Ti G5. The clinical performances of Ti G4 and Ti G4 Hard were similar. SIGNIFICANCE The improvement of the mechanical properties of modified Ti G4 means that Ti G5 can be safely replaced by Ti G4 Hard without compromising the fracture resistance, with the advantage of not releasing toxic ions.

Removal Torque and Bone Adherence to Dental Implants Surface

The primary stability is an important factor in achieving a predictable dental implant treatment. Therefore, in order to reach longitudinal success, it is necessary to achieve and to maintain the primary stability as basic pre-requirement [1,2]. The primary stability can be considered the first stabilization that is obtained immediately after implant insertion [3]. Thus, the insertion torque during implant installation may be an indicative of implant survival [4]. However, the initial stability may not be a factor that assures the osseiointegration, because it can be influenced by bone properties, surgical techniques and implant design [3]. Consequently, the measurement of the insertion torque could not be the only parameter to predict the osseointegration success rate. Thus, there are studies that evaluate the implants surface treatment to investigate what may influence the prognosis [5-7]. After the initial wound healing, some features determine the secondary stability as the biological response to the surgical trauma, the conditions of the wound healing and the material of the implant per se [8]. Therefore, there is an increase in the contact in the bone-implant interface [8]. At the same time, the presence of osteocytes in the bone remodeling in the bone-implant interface as well as the amount of sclerostin, osteoprotegerin and RANKL influence this remodeling [9]. Thus, when a traumatic surgery is performed or load is applied before the right time can lead to a tissue injury, resulting in bone resorption [9]. The design of the dental implant has evolved to improve its mechanical, functional and esthetic efficiency [3-8]. Nonetheless, the events that occur in the bone-implant interface are still in need of further investigation [6,7]. Having that in mind, studies involving implants with different surface treatments and the understanding the effects of different torques are important to a more comprehensive knowledge of this surfaces and the interaction with the bone tissue [1-8]. Thus, the aim of this study was to analyze the influence of the insertion torque applied to titanium dental implants with different surface treatment (acid and fluoride) on the bone adherence to the implant surface after removal from rabbit tibia by scanning electronic microscopy (SEM) after 40 days of implantation.