Possible hazardous effects of hydrofluoric acid and recommendations for treatment approach: a review

Abstract

Hydrofluoric acid (HF) is commonly used for conditioning the glass ceramics either prior to cementation or for intraoral repair in prosthetic and restorative dentistry. The present study offers a review of chemical properties of HF used, highlight the possible hazardous effects of this agent, and to recommend the treatment approach for potential risks. Available published information documented in PubMed, Medline, and Picarta literature databases was reviewed. Additional information was derived from scientific reports, medical and chemical textbooks, handbooks, product information, manufacturers' instructions, Internet web sites of the HF manufacturers. No report was found on the incidence of the hazardous effects of HF in dentistry. Reports from other fields presented incidences of acute and chronic symptoms in exposure to HF. While acute symptoms include skin or nail burns, chronic ones involve systemic toxicity, eye injuries, inhalation and ingestion-related symptoms that can be even fatal. HF can be harmful and particularly aggressive to soft tissues, but symptoms may not be apparent immediately after exposure. The hazardous effects are not based on the pH value, but on the toxicity of HF. Potential hazards of HF known from other applications than dentistry should be considered also in dental applications. Especially the clinicians, who often deal with adhesive cementation or repair of glass ceramics, should take necessary precautions for possible hazards of HF. Scientific reports, medical and chemical textbooks, handbooks, product information, manufacturers instructions, Internet web sites of the HF manufacturers were also referred. In dentistry, HF is most commonly used for conditioning the glass ceramics either prior to cementation or for intraoral repair.Exposure to HF can be harmful and may not be immediately apparent being particularly aggressive for soft tissues. This is not based on the pH value, but on its toxicity. Common routes of exposure are inhalation, dermal exposure and ingestion that lead to the general symptoms of toxicity such as lung injury, skin burns, systemic toxicity and painful necrotic lesions. General symptoms are skin burns, systemic toxication and eye irritation by fume exposure. No report was found on the hazardous effects of HF in dentistry. HF is commonly used to condition the ceramic surfaces prior to cementation or repair. Especially the clinicians, who often deal with glass ceramics, should take necessary precautions for possible hazards of HF.

Dental zirconia can be etched by hydrofluoric acid

“…Hydrofluoric acid is the inorganic acid hydrogen fluoride. Industrially, hydrofluoric acid is used to etch silica-based materials, clean metal surfaces before electroplating, and etch silicon wafers in electronic semiconductor materials [47][48][49][50] . Concentrations of 4%-10% hydrofluoric acid are typically used in the dental clinic and dental laboratory.…”

Influence of different treatments of the ceramic surface and thermal cycling on the bond strength of brackets to ceramic

“…Some studies have shown that different treatments, such as phosphoric acid, aluminum oxide or without etching presented lower bond strength in relation to surface HF acid etching 2,11,13 . However, previous studies have shown that HF acid may promoted severe problems for dental personnel and patients because this solution is extremely toxic, reactive and corrosive 10,15 , and the severity depends on the acid concentration, exposure time and penetration into the exposed Figure 1. Frequency distributions (%) of the adhesive remnant index (ARI) scores for all groups.…”

“…HF acid is an efficient surface modification agent that is capable of dissolving the glassy ceramic matrix, increased the roughness 6 , contact surface and wettability 7,8 , promoting higher bond between bonding materials and ceramics [9][10][11] . The application of hydrofluoric acid followed by a silane solution have been used prior to bonding glass ceramic to increase the bond strength and durability between brackets and ceramic surface 3,12,13 or luting glass ceramic restorations 12 .…”

“…However, it may be harmful for patients and dental personnel 10 because it is corrosive, highly toxic and reactive 15 . Thereby, a primer adhesive Clearfil Ceramic Primer (CCP, Kuraray America) specific for ceramics has been indicated without the need of HF acid etching.…”

Chemical burn injury due to hydrofluoric acid: a case of successful management without hexafluorine

“…A 2.5% calcium gluconate gel is often used to treat burn lesions induced by acid [6,7]. After first aid by washing and application of gel, 5% of calcium gluconate injections may be required for lesions especially of deep burns with a large surface area [5]. Severe systemic toxicity may occur following HF burns.…”