| Abstract|| |
Background: The present study was conducted to determine the frequency and type of adverse events (AEs) associated with ultrasonic scaler reported to the Food and Drug Administration manufacturer and user facility device experience (MAUDE) database.
Materials and Methods: The authors reviewed the ultrasonic scaler units (USU) related AEs reported to MAUDE from October 1, 1995, to September 31, 2015. Analyses of details collected are presented.
Results: MAUDE received a total of 667 unique USU-related AE reports. Of 667 cases, MAUDE classified 628 instances (94.2%) as malfunction 27 (4%) as injurious, 10 (1.5%) as others, and 2 (0.3%) claiming the use of USU as cause of death. Of the 667 cases, 511 (76.6%) were used for endodontic application, and 147 (22%) as scaler applications. In 512 (76.8%) instances, there was separation of the tips, posing danger to patients or users, and 112 (16.8%) instances of overheating, 12 (1.8%) instances of breakage, and electrical issues in 8 (1.2%) instances. These AE resulted in 19 instances of thermal injury, 2 suspicious deaths, and hearing loss in 3 cases. In 4 cases, patient swallowed broken parts requiring additional medical care.
Conclusions: Use of USU, a Class 2 device without exemption, carries a degree of risk to patient's safety, if not properly used. As of today, MAUDE data is the only reliable source of AE until another database or such study is carried out. Certain AE that has been largely anecdotal, such as hearing loss has been reported in this study. The findings from study reiterate that more in-depth analysis of AE of USU is needed. Until then operator needs to take all precautions to avoid AE when using USU.
Keywords: Adverse events, endodontic retrieval instrumentations, oral prophylaxis, overheating, thermal burns, ultrasonic scaler
|How to cite this article:|
Thennukonda RA, Natarajan BR. Adverse events associated with ultrasonic scalers: A manufacturer and user facility device experience database analysis. Indian J Dent Res 2015;26:598-602
Human is capable of hearing vibrations in the range of 20 Hz to 20 KHz. Any sound wave above this frequency is referred to as ultrasonic. , It was proposed in the early 1950s that ultrasonic sound waves can be used to disintegrate dental calcified tissues. With the introduction of high-speed rotary devices, interest in ultrasonic application waned. In mid-1950s, it was demonstrated that ultrasonics can be efficiently used to dislodge deposits from dental surfaces. Several other studies that followed confirmed the efficiency of ultrasonic in removing calculus. With such proof, widespread use of ultrasonics in dental clinic begin to emerge. It was since 1957, use of ultrasonics in endodontics began to materialize. 
|How to cite this URL:|
Thennukonda RA, Natarajan BR. Adverse events associated with ultrasonic scalers: A manufacturer and user facility device experience database analysis. Indian J Dent Res [serial online] 2015 [cited 2019 Oct 22];26:598-602. Available from: http://www.ijdr.in/text.asp?2015/26/6/598/176923
Currently, ultrasonics use in dentistry has grown to large proportions. All dental clinics in affordable settings have at least one type of ultrasonic scaler units (USU). The application of ultrasonic scaler units is found in dental scaling, has wide applications in endodontics, and oral surgical procedure. In a typical USU, ultrasonic is produced by "magnetostriction" (a mechanism which converts electromagnetic energy into mechanical energy) or based on "Piezoelectric principle" (crystal is used that changes dimension in an electrical field. Subsequent deformation of crystal results in a mechanical oscillation without producing heat).  The older units use the former principle while that newer units rely on piezoelectric principle. The newer USU have been used as a scaler, an endodontic retreatment application or as a piezo-surgical unit.
Currently, ultrasonic scaler unit is a Class 2 device, without exempt as per the Food and Drug Administration (FDA). As compared to the widespread use of USU, very little is known about adverse, deleterious effects, or hazards associated with its use. Only a very few case reports have been known to be reported in literature  and up to 2% of all adverse events (AEs) associated with dental devices and equipment were reported to involve scalers.  The FDA of the United States of American Government defines AEs as "any undesirable experience associated with the use of a medical product in a patient."  There is a paucity of literature on the quantum of such adverse effects associated with USU, with last one such report's qualitatively discussing the subject  and another not detailing into scalers. 
Reports containing such warnings may help the users and even government officials to recall the potentially dangerous materials from the market. To cite an example, the recall of a denture cream with excess zinc leading to a downstream of events such as hypocupremia and neurological disease in a young individual who was using a partial denture and denture cream with high zinc content. Such seemingly unrelated correlations is often missed in general practice. ,, Database such as manufacturer and user facility device experience (MAUDE) could be collection of such events, providing strong large-scale collective evidence for knowledge of AE as well as practice.
General dentistry, especially seemingly harmless equipment such as an ultrasonic scaler, over these years of usage have poor patient safety literature baring very few isolated case report unlike in medical field. , Probably, this could emanate from the fact that most of the dental devices being Class 1 and 2 devices, the possibility/probability of injury arising from the use of such materials might be less severe, follow-up is rare or fear of lengthy, costlier legal proceeding or the inherent gap in patient safety culture.  The aim of this manuscript is to list possible AE associated with USU usage in dental clinics in the past 10 years.
| Materials and Methods|| |
The FDA of the federal government of the United States is the agency that is responsible for the approval and grant of permission of all the health-related products and devices. This agency maintains an open access database, called as the MAUDE (http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/search.cfm) that lists all the AE associated all FDA approved devices. It is mandated that the manufacturer/or distributor should file an AE in an preapproved, prescribed, narrative format within 30 days of event being reported compulsorily while voluntary reports are also being accepted by the organization. The MAUDE database contains the submitted anonymous narrative description of the AE, manufacturer's versions, and conclusions about reported events. 
For this study, all AE, as defined by FDA (any undesirable experience associated with the use of a medical product in a patient) by the usage of USU, as identified by the unique code supplied, (ELC), for dental ultrasonic scaler units between October 1, 2005 and September 30, 2015 were collected from the MAUDE database.
From the data, the following were collected and then categorized as - voluntary or mandatory reports; The year of reporting; broad event type; application used - scalers/endodontic/piezo-surgical; types of defect; place of event; nature and site of injury; and outcome of the injury.
These data were then entered in Statistical Package for Social Services (version 20.0, IBM, IL, USA). Descriptive statistics were performed and presented. Simple cross-tabulations were employed to identify the outcome AE with nature of reporting (voluntary/mandatory) and applications (endodontics/periodontics/others). Chi-square test was used to identify the statistical significance. A P ≤ 0.05 was taken to be significant.
| Results|| |
There were 675 reports of AE involving USU collected from the MAUDE database in the time frame. Of them, 8 were identified to be duplicates which were removed from further analysis. Hence, a total of 667 cases were collected for this study. Among the cases, 653 (97.9%) were mandatory reports while a 14 (2.1%) were voluntary reports. The annual reporting trend for the time frame is given in [Figure 1].
|Figure 1: Annual trends in adverse event reports associated with ultrasonic scaler in the study population|
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Of the 667 cases, 5 cases involved operator. Of the 667 cases, MAUDE classified 628 instances (94.2%) as malfunction 27 (4%) as injurious, 10 (1.5%) as others, and 2 cases (0.3%) claiming the use of USU as cause of death. Of the 667 cases, 511 (76.6%) were used for endodontic application, 147 (22%) as scaler applications, and 9 cases exclusively for piezo-surgical applications. In 512 instances (76.8%), there was separation of the tips, posing danger to patients or users, 112 (16.8%) instances of overheating, 12 (1.8%) instances of breakage, electrical issues in 8 (1.2) instances, poor flow of coolant in 2 (0.3%) of cases, and failure in 1 case.
Of the 667 cases reported, 453 cases (67.9%) of episodes occurred intraorally, 82 occurred (12.3%) extraorally, involved the whole body in 4 cases. There was no detail in 116 (17.4) instances and not applicable in 7 cases (1%) were the USU were being used for demonstration or in standard packing. On studying the nature of the outcome of AE, 91 instances were found to be not applicable in 91 cases (13.6%), and no details in 134 cases (20.1%). Of the remaining cases, tooth was involved in 243 (36.4%) of cases, lip injury was observed in 9 (1.3%) cases, mouth in 60 (9%) of cases, gingival in 8 (1.2%), 6 instances of alveolar bone (0.9%) damage, emphysema in 1 cases, and 4 instances were instruments were dislodged and swallowed. Infection was result in 3 cases, hearing issues in 3 (0.4%), and Bell's palsy in a single case.
Of the 667 cases, in terms of outcome of AE, there were 2 instance of (0.3%) death; 2 cases of emphysema, strokes each (0.3); benign paroxysmal positional vertigo in a single case; hearing loss in 3 cases (0.4%); 4 cases swallowed dislodged material (0.6%); and epilepsy, Bell's palsy, and traumatic cut injury in each one case (0.1). Thermal burns were observed in 19 cases (2.8%), dislodgment and foreign body impaction in tissues necessitating surgical removal in 9 cases (1.3%). The remaining instances were either not applicable (56 cases) or no details available or no lesions noted.
[Table 1] shows the comparison of outcome parameters by the status of reports. There is statistically significant difference in between voluntary and mandatory reports (P = 0.000). On comparing the applications in terms of the type of AE and the site of injury or being affected was compared. There was statistically significant difference between the endodontic, periodontic, and piezo-applications (P = 0.000) [Table 2].
|Table 1: Outcome parameter's compared between the mandatory and voluntary reports |
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|Table 2: Outcome parameters classified by application of the ultrasonic scaler units |
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| Discussion|| |
Knowledge of AE would help a dentist to take sufficient precaution, equip and train themselves to react and provide help in times of AE. Furthermore, such a knowledge can help them to inform, educate their patient, helping in the informed decision-making process. The MAUDE database reports are not extensively validated as they do have their shortcomings.  However, in certain high-risk fields such as cardiology, obstetrics, and gynecology, they have been used with varying success. ,,,
MAUDE suffers from the chance of multiple reporting, as evidence from this study too. They do not grade the severity of the event; chance of root cause analysis is nearly impossible; possibility of missing data and time line; MAUDE database is not a true global reflection of all dentists, even that of America.  Hence, a greater caution should be exercised while using the numbers that arising from this data. However, in the absence of any other such data, they could provide with robust numbers and list the possibility of AEs associated with any dental devices.
Ultrasonic powered dental equipment such as scalers and endodontic tips are ubiquitously used nearly in all dental settings. It is not possible to document the number of USUs and possibly all AE arising with the use of USU. However, in the last review of the hazards of using an ultrasonic scaler, several potential hazards events were listed. However, the relative incidences of the hazards were not arrived at. This manuscript probably attempts to address this issue.
The low volume of voluntary reporting in this study of about 2.1% indicates that most of AE are not serious in nature. In contrast about, 5% of all AE in a study comprising all dental materials and devices comprised voluntary reports.  Our further exploration in this study also indicates that most of the AE are self-limiting and did not warrant hospitalization, medication, or a day care. The difference in annual reporting trend is rather confusing, and a rationale explanation could not be arrived at. Furthermore, as MAUDE has issued against at reporting annual trend or comparison of AE across brands using MAUDE data is isolation, hence both of them were not probed further.
The predominant AE was malfunction - mostly arising due to separation of endodontic tips. Only about 4% of the instances were listed as injurious and 0.3 very grievous in nature. In most of the instances in this group, USU was used as an endodontic application - in about 76.6% of cases. An approximate number of cases of separation of tips were reported as the AE. It could be seen in the [Table 1] and [Table 2] that in 240 cases, separated tips were lodged inside the tooth and required additional efforts in retrieving. In some cases, it caused damage to gingival tissues and or permanent loss of tooth. This finding probably indicates the safety aspects of endodontic tips are most probably not followed by the operator, as outlined in the manual. In addition, the observation of that only certain tips separated more often than others, the design of such tips needed to be revised. More in-depth analysis of this phenomenon are the need of the hour to prevent untoward events endangering patients and rarely the operators.
The next more common AE was overheating which was more observed with scaler. Though only 19 cases of thermal injury resulted in this serious, some of them have been described to be as large as 6 cm and at least in two instances required plastic surgery intervention as the burn was associated with vermillion border and part of lower lip skin too. Using the incompatible tips, using in dry mode, flash clogs, biofilm build-up, and using tips beyond its recommended time/use are sited to be some of the common reasons for overheating and in certain instances thermal injury. Operators should be well-educated that different instruments at different settings and tip permit the different amount of coolant.  As they are specific in nature, every effort shall be made to stick to recommended regimen than standardizing this. In cases of breakage of tips, positioning of tip has been found to be the most common mistake. The operators in several instances probably have used the sides of tip instead of the head of the tip to make the contact with teeth. Piezosurgery has least number and most commonly associated with overheating and breakage of tips, resulting in foreign body impaction inside oral tissues.
In the review of hazards of using ultrasonic scalers, the phenomenon of "cavitation" and "microstreaming" has been discussed. The subsequent damage of platelets has been discussed.  In this study, there have been two instances of stroke caused by the dislodged plaque and attributed to the deep scaling 24 to 48 h before the AE. As a root-cause-analysis could not be performed, more details are needed to confirm and attribute such an event to scaling needs to be explored. Until such evidence emerges, the association needs to be eyed with suspicion.
Possibility of occurrence of acoustic trauma in patient with use of USU has been predicted,  though no evidence provided in support of such a possibility. The finding of three cases in this database provides a direct evidence of this remote possibility. Furthermore, one more case where there was tinnitus that was subsequently diagnosed to have benign paroxysmal positional vertigo strengthen the notion that acoustic trauma from a USU is a possibility, and at least 4 cases have been identified from this data. More detailed analysis is needed to establish the complete pathogenesis other than previously proposed. Infection, especially one that reported after a postoral prophylaxis, if serious such as infective endocarditis, needs to be acted against in a rapid manner. Two deaths have been reported in this data and attributed to dissemination of infection via deep scaling. Though largely anecdotal until date, more reliable evidence needs to be collected before establishing the cause-effect relationship. Similarly, Bell's palsy and trigeminal neuralgia have been reported with use of USU. Though nerve injury is a remote possibility resulting with USU use, more details are needed to confirm the association. The possibility of postoral prophylaxis sensitivity of teeth and triggering of an epilepsy episode also needs to be viewed under the same angle.
Swallowing of broken or dislodged parts, embedding of broken material in the gingival, teeth, alveolar bone are events that can be managed uneventfully often and rarely resulting in widespread necrosis, as reported under AE. A dentist or hygienist handling a USU needs to be aware of the potential hazards associated with it. All manufacturers' recommendation need to be adhered to very rigorously.
| Conclusion|| |
To the best of our knowledge, this manuscript is the first of its kind to describe AE associated with USU use. As any other dental device, USU is not free from the risk of AEs. Considering the widespread use of USU, an operator needs to be educated about all the listed potential risks of using USU application. Operator should be adequately trained to approach and manage if such an AE arises in practice. Prior possibility of such an AE shall be explained, and consent shall be obtained to avoid medicolegal issues too. Until further strong evidence emerges, this robust number of events shall serve as a reference marker of AEs associated with use of ultrasonics scalers.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Dr. Rajagopal Athmarao Thennukonda
Department of Dentistry, Madurai Medical College and Hospital, Madurai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]