In a curious twist of irony, the global figures for tooth decay are rising dramatically due to modern advances in prolonging overall tooth health.

Professor Wagner Marcenes, professor of oral epidemiology at Queen Mary, University of London, led a team of researchers in discovering the startling statistic that over half of the world's population -- 3.9 billion people -- suffers from major untreated dental problems.

The research comes as part of an international investigation into oral health, which has been compiled into the 2010 Global Burden of Diseases, Injuries, and Risk Factors Study (GBD). Of all 291 major diseases and injuries assessed by the GBD, untreated tooth decay and cavities -- known also as dental caries -- were the most common, affecting 35 percent of the world population.

"There are close to 4 billion people in the world who suffer from untreated oral health conditions that cause toothache and prevent them from eating and possibly sleeping properly, which is a disability," said Professor Marcenes in a news release. "This total does not even include small cavities or mild gum diseases, so we are facing serious problems in the population's oral health."

The irony in all this is that tooth loss has been far more debilitating in the past. When the advances in dentistry moved at a slower pace, people frequently lost their teeth when they couldn't receive proper help. Over time those people put less pressure on the system, as they had increasingly fewer teeth that needed fixing.

Now, modern dentistry has the technology to preserve decaying teeth for decades, an advancement Professor Marcenes said ends up prolonging the burden.

"Tooth loss is often the final result when preventive or conservative treatments for tooth decay or gum disease fail or are unavailable," he said. "It is likely that current dental services are coping better to prevent tooth loss than in the past but major efforts are needed to prevent the occurrence and development of gum diseases and tooth decay. Ironically the longer a person keeps their teeth the greater the pressure on services to treat them."

The greatest increases in the burden of oral conditions came from Eastern Africa (52 percent), Central and Sub-Saharan Africa (51 percent), and Oceania (48 percent). Meanwhile, data from the National Institute of Health (NIH) reveals tooth decay no longer poses a threat in the United States the way it once did.

"In addition to improved products to fight tooth decay, more people benefit from preventive dentistry," the NIH fact sheet explains, "including the use of fluorides and dental sealants to prevent decay. Compared to previous years, these techniques have made it possible for millions more people to keep their natural teeth for a lifetime."

Without the assistance modern dentistry provides, 18.6 million more Americans would lose all their teeth by age 45.

"It is estimated that from 1979 through 1989 alone, the American public saved more than $39 billion in dental expenditures due to the power of prevention," the fact sheet continues, which runs in stark contrast to other parts of the world where dependence on modern dentistry can become cost-prohibitive as teeth remain intact.

"Our findings are set to shake up the setting of health priorities around the world," Professor Marcenes said, "providing an unparalleled amount of up-to-date, comparable data on the diseases, risk factors, disabilities, and injuries facing populations."

The GBD began in the spring of 2007, with nearly 500 scientists involved in the global aggregation of disease- and injury-related data.

Source: Marcenes W, Kassenbaum N J, Bernabe E, et al.Global Burden of Oral Conditions 1990-2010: A Systematic Analysis. Journal of Dental Research. 2013.