A Clinical Trial of Dental Implants in Titanium-zirconium Alloy

Background

Implants have been used for the purpose of replacing lost teeth since the 1960s. Since then, the treatment of edentulism with dental implants has been implemented in a large scale. The main reason for this is that research has shown that treatment with implants are very predictable in terms of implant survival. The accumulated knowledge, as seen from 15 and 20 year follow-ups, has been based on prerequisites that are not always followed today. One of them is that the implants used in the aforementioned studies are manufactured in titanium that has good rigidity and is used as the main implant material today. In addition, the studies have examined implants with a turned surface. This standard revised in the mid 1990s when a series of studies showed increased and accelerated osseous ingrowth of implants with a moderate raw surface that had been achieved by blasting. The related biological events describing this process have been described in detail in the literature.

Today, other materials are being explored as an alternative to the well documented implant material titanium with a focus on finding a material with higher stiffness combined with equivalent biological characteristics. A stiffer material theoretically gives possibilities for implants installations without bone augmentation in cases with reduced bone volumes.

An alternative implant material which has reached the clinic is titanium-zirconium alloy. It has been shown to have an increased rigidity in comparison with titanium and comparable biological characteristics but the documentation consists mainly of animal studies and short term clinical follow-up in the form of case-series. Since it has been demonstrated that the choice of implant material may influence osseointegration, it is necessary to evaluate the implants made of titanium-zirconium in a clinical controlled study with long-term follow-up in which the emphasis is put on the clinical outcome.

Aims

The aim of the study is to compare the clinical outcome of implants made of titanium-zirconium with a proven implants made of titanium.

The scientific question in this project is if there are differences in the clinical outcomes of an implant made of titanium and a corresponding implants in titanium-zirconium alloy.

Materials and Methods

Patients referred for implant treatment at the Department of Prosthodontics, Specialisttandvården Borås will be asked to participate in the study and provide written consent after review of delivered information sheet. Implants will be installed by two well experienced surgeons at Oral Maxillofacial Surgery att Borås Regional Hospital according to the protocol used for dental implant surgery and recommended by the manufacturer.

Two groups, matched for age and gender, will be defined after block randomisation for smoking. The test group will receive titanium-zirconium implants and the control group titanium implants. For a power of 80% and for p < 0.05, (SD = 1.66 according to previous studies, estimates made from 1 mm difference in margin bone level between the groups), the size of the groups has been defined as 44 patients per group. The investigators anticipate a loss of approximately 10% and therefore, the investigators have increased each patient group to 48 individuals. The data collection is completed when the number of patients has been reached.

The evaluation will involve no additional clinical or radiological examinations as compared to the usual procedures. Normally, this means examination and therapy planning, surgical examination, implant installation, impression, placement of prosthetic restoration, baseline X-ray, control/follow-up tightening of prosthetic screw/hygiene monitoring. No additional time or costs arises in connection with participation in the study, the cost of both groups are equivalent.

National guidelines will be followed regarding possible need of antibiotic prophylaxis. Registration will be done with regard to history of periodontal disease, smoking, medication, and implant position in the jaw.

The data collection will take place at four different times: in connection with the placement of the prosthetic construction (baseline) and after 1.3 and 5 years. Standard x-ray examinations will be carried out to check the marginal bone level which will take place through individualized x-ray holders that will be produced by impression material (Putty). Registration of pocket depth, bleeding on probing, amount of keratinized mucosa and measurements on x-ray will be done by the same person. Prosthetic complications and possible total implant loss will be registered.

The marginal bone level for each implant will be presented as the average of the mesial and distal bone level (primary outcome). The mean value of pocket depth will be recorded for each implant at a 4-point measurement. The hypothesis is to be tested with the independent samples t-test.

The impact of restoration distance from the bone level, the effect of implant type, margin bone level, bleeding on probing and pocket depth will be controlled using regression analysis. SPSS is used for statistical analysis.

The hypothesis is that there are no differences in the clinical outcomes between the two types of implants.

Potential benefits of the Project

The investigators can conclude that the materials are equivalent if there is no difference between implant types available. Since, titanium-zirconium alloy has a higher stiffness than titan, the investigators will be able to provide patients with thinner implant and thus costly and painful treatments to optimize the width of the bone in the installation area should be avoided.

From a social perspective, if it turns out that titan-zirconium have equal or better clinical performance than titanium, can unnecessary healthcare costs for surgery for modulation of the surgical site in the form of augmentation or sinus elevation associated with implant treatment should be avoided. If optimizing surgery can be avoided, this means even shorter therapy times and increased availability by the released health time which can be used to more quickly treat other patients as possible had standing in line for their treatment. Limits can be found in the study's applicability in general dentistry because all operations are carried out at specialist clinic in which case the patient clientele and the processor's level of expertise is not fully comparable with the general dentist.

Research ethical considerations

Treatment with dental implants in titanium is a known treatment that has helped to restore good chewing function for many patients and years all over the world and can be thought of as a safe treatment with high success rates. The study protocol calls for no difference in the x-ray examination or the surgical protocol as compared to the procedures followed in regular treatment basis. In previous studies, there is no listing of suspected allergy to titanium-zirconium alloy.

Patient information and storage of personal data in accordance with the recommendations of the Board of ethical review.