An In Vitro Biomechanical Evaluation of a New Commercial Titanium-Zirconium Alloy Dental Implantby Aaron Yu-Jen Wu, Jui-Ting Hsu, Heng-Li Huang

Implant Dentistry

About

Year
2014
DOI
10.1097/ID.0000000000000108
Subject
Oral Surgery

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Text

An In Vitro Biomechanical Evaluation of a New Commercial Titanium-Zirconium

Alloy Dental Implant: A Pilot Study

Aaron Yu-Jen Wu, DDS, PhD,* Jui-Ting Hsu, PhD,† and Heng-Li Huang, PhD‡

C ommercial pure (CP) titanium (Ti) and its alloys are widely used as metallic biomaterials in bone screws and plates, and also as the orthopedic and dental replacements due to their excellent biocompatibility and mechanical properties, including low modulus, high corrosion resistance, and lightness.1,2 However, pure Ti and Ti alloys still fail to meet some of the requirements for implant biomaterials in clinical applications. The tensile strength of Ti is insufficient for its use in orthopedic joints and bone plates and screws,3 and its poor wear resistance4 also prevents its widespread application in many medical fields. A Ti-aluminum (Al)-vanadium (V) alloy is the most commonly used Ti-based material for medical implants. Although Ti-Al-V alloys have very good corrosion resistance and biocompatibility, some concerns remain about the release of toxic Al and V ions into the surrounding tissue during long-term implantation.

Zirconium (Zr) has been considered as an excellent alternative biomaterial to Ti. Not only is Zr a nontoxic metal, but a bone-like apatite layer can form on its surface that attracts the growth of bone tissue.5 There is in vivo evidence of Zr exhibiting good osseointegration with bone in animal studies.6–8 Additionally, Zr-based materials have advantages of outstanding corrosion resistance9 and high bending strength and fracture toughness.10,11 The increasing use of computer-aided design and computer-aided manufacturing techniques in recent decades has also increased the general acceptance of Zr-based materials in dental applications.12

Ti and Zr are the group 4 elements in the periodic table and hence they have similar chemical properties.

Some researchers have selected Zr as an alloying element to improve the properties of CP Ti and to create different types of Ti-Zr–based alloys formedical uses, especially for implant applications.3,13–16 A novel alloy based on Ti that contained 13% to 17% Zr was recently developed for use in small-diameter implants. Decreasing the diameter of an implant increases the risk of implant fracture because of the lower mechanical fatigue strength.17

However, the superior tensile and fatigue *Assistant Professor and Director, Department of Dentistry,

Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan. †Associate Professor, Biomechanics Res. Lab, School of

Dentistry, China Medical University, Taichung, Taiwan. ‡Professor, Biomechanics Res. Lab, School of Dentistry, China

Medical University, Taichung, Taiwan.

Reprint requests and correspondence to: Heng-Li

Huang, PhD, School of Dentistry, China Medical

University, 91 Hsueh-Shih Road, Taichung 40402,

Taiwan, Phone: 1-886-4-22053366 ext. 2306, Fax: 1-886-4-22014043, E-mail: henleyh@gmail.com

ISSN 1056-6163/14/02305-534

Implant Dentistry

Volume 23  Number 5

Copyright © 2014 by Lippincott Williams & Wilkins

DOI: 10.1097/ID.0000000000000108

Background: The study compared the implant mobility and surrounding bone strain between the titanium-zirconium (Ti-Zr) alloy and the commercial pure (CP) Ti implants.

Methods: The mobilitydquantified as the implant stability quotient (ISQ) and Periotest value (PTV)dof implants constructed from Ti-Zr alloy and CP Ti placed into artificial type-2 jawbone models were measured. Specimens were tested by applying 190 N vertically or at 30 degrees laterally. Peak values of the principal strains of bone were recorded by rosette strain gauges with a data acquisition system and were analyzed statistically using

Wilcoxon rank-sum test.

Results: PTV and ISQ values did not differ significantly between the

Ti-Zr and CP Ti implants (P . 0.01).

Under vertical loading, the peak bone strains did not differ significantly between the Ti-Zr and CP Ti specimens (P. 0.006). However, the peak strains were 52% lower around the

Ti-Zr implant than around the Ti implant on the buccal side of bone under lateral loading (P , 0.001).

Conclusions: The implant material (Ti-Zr alloy vs CP Ti) had no effect on the mobility of small-diameter dental implants. However, using Ti-Zr alloy as an implant material decreased the periimplant bone strain under lateral loading in this pilot study. (Implant Dent 2014;23:534–538)

Key Words: small-diameter implant,

Ti-Zr alloy, CP Ti, implant mobility, bone strain 534 TI-ZR ALLOY DENTAL IMPLANT  WU ET AL strengths of the new Ti-Zr alloy compared with CP Ti18 resulted in it exhibiting acceptable mechanical strength for dental implant. Additionally, its biocompatibility in enhancing osseointegration has been confirmed in both animal tests and a clinical study.18–21

Since 2010, the mechanical strength and biocompatibility of Ti-Zr implants have been demonstrated in animal studies and a 1-year clinical observation.18–21 However, the effects of Ti-Zr implants relative to Ti implants on the biomechanical characteristics of the surrounding bone remain to be determined. This study applied a strain-gauge analysis to artificial jawbone samples to compare the biomechanical effects of Ti-Zr and CP Ti implants on induced bone strains. In addition, the mobilities of Ti-Zr and

CP Ti implants were compared by measuring the implant stability quotient (ISQ) and Periotest value (PTV).

MATERIALS AND METHODS

Implant Design Parameters and Bone

Specimen Preparation

Implants constructed from 2 kinds of materials were selected for analysis: (1) Ti implant (SLActive; Institute

Straumann AG, Basel, Switzerland) and (2) Ti-Zr implant (Roxolid; Institute Straumann AG) (Fig. 1). These 2 implant types had hydrophilic sandblasted and acid-etched surfaces, a diameter of 3.3 mm, and a length of 12 mm.

A Sawbone model of trabecular bone with a density of 0.64 g/cm3 and elastic modulus of 759 MPa (model 1522–05; Pacific Research Laboratories, Vashon Island,WA)was prepared to attach to a 3-mm-thick commercially available synthetic cortical shell (model 3401–02; Pacific Research