Looking over the medical records at a specialty clinic in Virginia, public health investigators have uncovered a cluster of dental workers with a progressive lung disease that appears to be occupationally acquired.

In 2016, a Virginia dentist seeking treatment at the clinic was diagnosed with idiopathic pulmonary fibrosis (IPF), a progressive lung disease of unknown etiology. The dentist contacted the CDC after becoming aware that other dental workers also were being treated for IPF at the clinic.

“The clinic where these dental personnel sought care specializes in the treatment of IPF,” said Randall Nett, MD, MPH, a medical officer in the CDC’s Respiratory Health Division, and lead investigator. “The dentist who reported this cluster to CDC was told of several dentists who had been treated at the same clinic by his treating physician.”

This is the first report of IPF, but dental workers are known to be at risk to infectious agents, chemicals, airborne particulates, ionizing radiation, and other potentially hazardous materials, the CDC reported.

“Inhalational exposures experienced by dentists likely increase their risk for certain work-related respiratory diseases,” the CDC report noted.1 “For example, cases of dental technicians with pneumoconiosis, a restrictive occupational lung disease resulting from inhalation of dust, have been identified after exposure to either silica or cobalt-chromium-molybdenum-based dental prostheses.”

Grim Prognosis

Occupational exposures have been linked to other professions, but this is the first published report describing IPF in dental workers. The lung disease has a grim prognosis, with the estimated median survival time after diagnosis ranging from three to five years.

Investigators reviewed the medical records for all 894 patients treated for IPF at the Virginia clinic from 1996 to 2017. They were looking for patients who had worked as dentists, dental hygienists, or dental technicians. Among 894 patients treated for IPF, nine (1%) were identified as dental personnel, including eight dentists and one dental technician. At the time of pulmonary consultation, the median patient age was 64 years (range: 49-81 years). In addition to patients from Virginia, three were from Maryland, and one was from Georgia. Seven of the nine patients had died by the time of the investigation, with a median survival time from consultation of three years (range: 1-7 years). One patient underwent a lung transplant three years after diagnosis.

Risk ‘23-fold’ Higher

The report stated that “during 2016, dentists accounted for an estimated 0.038% of U.S. residents, yet represented 0.893% of patients undergoing treatment for IPF at one tertiary care center, nearly a 23-fold difference.” That certainly raises concern for these workers nationally, but Nett was hesitant to go beyond the cluster data.

“At this time, we do not have any information about additional clusters of IPF occurring among dentists,” he said. “We are in the planning stages for conducting additional studies to determine if the dental community is at higher risk for developing IPF.”

A phone interview was conducted with the patient who had contacted the CDC. The patient was a nonsmoker, and reported never wearing a NIOSH-approved respirator during 40 years of dentistry. However, he wore a surgical mask for the last 20 years of his dental practice.

“He reported performing polishing of dental appliances, preparing amalgams and impressions, and developing X-rays using film developing solutions,” the CDC reported. “He also reported work-related exposure to dust while working as a street sweeper for three months before entering dental school, and environmental exposure to dust from coral beaches for approximately 15 years while intermittently visiting the Caribbean region as a practicing dentist.”

The report recommended that “dental personnel who perform tasks that result in occupational exposures to known respiratory hazards should wear adequate respiratory protection if other controls (e.g., improved ventilation) are not practical or effective.” The choice in appropriate respiratory protection (e.g., surgical mask vs. N95 respirator) depends on the particular inhalational hazard, Nett said.

“For example, surgical masks would be protective against blood splattering from the patient, but would not be protective against silica exposure caused by grinding or polishing,” he said.

Nett referred further inquiries on this question to the OSHA webpage about potential occupational exposures in dentistry, at: https://bit.ly/2GlmN7C.

This resource does not address IPF, but cites the danger of silicosis, another lung disease that has been linked to inhaling silica when working with dental casting and grinding porcelain. Though this would not be routine dental care, the recommendations for preventing silica exposures are to “wear a respirator when other control methods are missing or do not work. The type of respirator recommended is, at a minimum, a half-mask air-purifying respirator with type N100 particulate filters.”

Nine cases of silicosis were recognized among dental laboratory technicians exposed to crystalline silica in five states during 1994-2000, the CDC reported. Based on the Virginia dental cluster, NIOSH is not considering new recommendations for respiratory protection of dental healthcare workers at this time.

“This was an isolated cluster that involved nine cases of IPF at a single tertiary care clinic,” Nett said. “We need to conduct further studies to determine if the dental community is at higher risk for developing IPF.”

REFERENCE

1. CDC. Dental Personnel Treated for Idiopathic Pulmonary Fibrosis at a Tertiary Care Center — Virginia, 2000–2015. MMWR 2018;67:270–273.