This study identified 2 cases of accidental foreign body aspiration and 37 cases of accidental foreign body ingestion that occurred over a 7-year period at a single dental hospital. Severe complications did not occur, and no surgical intervention was needed. The incidence rate was higher in males than in females, and increased markedly in old patients aged 80 or older. It was highest in the Predoctoral Student Clinic and second highest in the Department of Prosthodontics. The most frequently swallowed foreign bodies were fixed dental prostheses and dental implant components.
A particularly interesting finding of this study was the incidence rate being more than twofold higher in males than in females. Another 7-year-long retrospective study analyzing cases of the endoscopic removal of dental foreign bodies in a medical and dental hospital in Japan found a male-to-female ratio of 21:8, which is similar to that in the present study. The anatomies of the larynx and pharynx are known to differ between males and females, with the oropharynx volume being larger in males. In addition to anatomical differences, tongue strength and endurance might also affect the incidence rate, although sex-related differences in these parameters are controversial[9, 10].
The higher incidence of accidental foreign body aspiration and ingestion in older people is consistent with the findings of previous studies, which may be explained by the effects of a decreased gag reflex and an increased prevalence of various medical conditions. Foreign body aspiration and ingestion was reported to occur frequently in children and rarely in adults[11, 12], which contrasts to the present study finding a low incidence in children. This might be due to various methods for preventing accidental foreign body aspiration and ingestion being applied more actively for children. In the Department of Pediatric Dentistry of Yonsei University Dental Hospital, rubber dams are strictly applied during all possible treatments, with other preventive measures such as gauze throat pack being used when performing a dental procedure in which it is impossible to use a rubber dam.
It is noteworthy that 7 of the 39 patients in this study had impaired cognition or conditions that may have affected swallowing. Patients who receive excisional surgeries for oral and maxillofacial cancer and those with oral and maxillofacial deformities may be at a higher risk of accidental foreign body aspiration and ingestion, due to their throat being open during dental treatment. There have been several case reports of accidental foreign body aspiration and ingestion in patients with Parkinson’s disease, stroke, and psychiatric problems . The present retrospective study has confirmed that these patients are at a high risk.
The high incidence rate found in the Predoctoral Student Clinic in this study is consistent with other studies finding that accidental foreign body ingestion occurs more frequently when procedures are performed by unskilled practitioners[15, 16]. This is consistent with unskilled practitioners probably being more likely to make various mistakes compared to skilled operators. We found three cases of accidental ingestion of low-speed contra-angle dental burs in the Predoctoral Student Clinic, which were due to obvious bur-fastening errors—experienced practitioners rarely make such mistakes.
If object loss is identified in the oral cavity and the object is not found in the treatment field, the presence of the foreign body within the respiratory or digestive tract should be confirmed using radiography, laryngoscopy, or bronchoscopy. There might be no symptoms if the foreign body is aspirated. Urgent endoscopic intervention may be required depending on the type and location of the foreign body in cases of ingestion. Ingested foreign bodies that are sharp are much more likely to cause complications, and so they must be removed. A case report found that a dental implant screwdriver that was swallowed had remained in the intestine for more than 7 days, and so colonoscopy under general anesthesia was needed to remove it. Ingested foreign bodies for which the decision is made not to remove them must be followed up until they are excreted.
It is crucial to apply interventions aimed at preventing the aspiration and ingestion of foreign bodies. First of all, dental practitioners need to identify high-risk patients. Patients aged 80 or older can be considered to be at a very high risk. Patients with conditions that cause muscle weakness, decreased reflexes, cognitive impairment, and which can affect swallowing are also at a high risk. All possible preventive measures should be actively applied for such high-risk patients.
A rubber dam is the most obvious preventive measure, and one that completely covers the oral cavity should be used whenever possible. Alternatives may be used in situations where a rubber dam is not suitable. It is advisable to wear tight gloves and not to recline the chair too much (i.e., only to the semi-supine position) when handling small objects within the oral cavity or when extracting deciduous teeth. It might be prudent to use floss to secure objects such as rubber dam clamps, bridge restorations, dental implant screwdrivers, and endodontic files. Placing a gauze throat pack is also recommended. However, since such gauze can be swallowed, the use of 4 × 4 gauze with a radiopaque thread that can be seen in case of swallowing is recommended over the 2 × 2 size.
Checking that dental burs are properly installed is useful for preventing them from dropping into the oral cavity. When a dental bur is mounted on a low-speed contra-angle handpiece, it should be pushed all the way in and then pulled back in order to check that it does not come out. Activating a handpiece before using it within oral cavity will check that the bur is installed properly and does not detach from the handpiece. Most dental burs are sharp and dangerous objects that can puncture the digestive tract when they are ingested.
The case of a fractured scaler tip fragment being swallowed indicates that dental practitioners should be aware that instruments with a thin tip may fracture. Care should therefore be taken to ensure that instruments do not fracture within the oral cavity by ensuring the use of the correct instrumentation and avoiding applying excessive forces. Dentists should check the connections of instruments with detachable parts, such as dental mirrors. The use of a swaged needle is recommended in order to prevent needle ingestion, given that one case was found in this study.