Are silicone breast implants safe or not? Experts say there is still a lack of good evidence proving either way, Reuters reported.

Silicone breast implants were introduced on the U.S. market in the 1960s, but the U.S. Food and Drug Administration stopped their use in 1992 because of certain health concerns raised, such as an increased risk of breast cancer, rheumatoid arthritis and reproductive problems.

However, because no substantial evidence was found linking silicone breast implants with these health problems, silicone breast implants were reintroduced in 2006. Almost 10 years since the moratorium on these products were lifted, there is still no conclusive evidence regarding the effects of silicone breast implants on women's health.

Researchers who are contributing to the establishment of a national breast implant registry, a joint project of the American Society of Plastic Surgeons and the U.S. Food and Drug Administration, conducted a review of past studies about the effect of silicone breast implants on women's health.

They investigated over 5,000 studies published between 1964 and 2003. The reports included women from Europe, North America and Australia. Of the 5,000 reports reviewed, only 32 satisfied the researchers' criteria in order to be included in the present study.

Upon investigation of the 32 studies, the research team still found no clear evidence that silicone breast implants are associated with an increased cancer risk and other health problems. Even though a number of studies suggested a link between breast implants and certain diseases, the results were not consistent, the researchers said.

One common flaw among the studies reviewed was that other factors like alcohol consumption and smoking were not considered. Most of them also investigated breast implants in general and not specifically silicone breast implants.

"If you don't account for those factors, you can't know whether there's a true association between the implants themselves and health outcomes," lead study author Dr. Ethan Balk from Brown University School of Public Health in Rhode Island told HealthDay.

The planned national breast implant registry is intended to track the health of breast implant patients from the day they get the implant until they get it replaced.

"Hopefully it'll show what the implants do in five, 10 or 15 years, because that's what's lacking in the current data," Dr. Rod Rohrich from the University of Texas Southwestern Medical Center in Dallas told Reuters.

The study was published Nov. 10 in the Annals of Internal Medicine.