PARTIAL TMJ IMPLANTS SHOULD BE IN CLASS III, PANEL SAYS, AFFIRMING FDA CLASSIFICATION PROPOSAL; ROOT APEX LOCATORS RECOMMENDED FOR CLASS II

Glenoid fossa and mandibular condyle temporomandibular joint implants should be placed in Class III so that the health risks associated with the partial TMJ prostheses can be addressed in premarket approval applications, FDA's dental products advisory panel recommended at a Feb. 11 meeting in Bethesda, Maryland. Six out of seven voting panel members maintained that premarket approval is necessary for the partial implants because they present risks greater than or equal to those of the total TMJ implant, which was recommended for Class III in April 1989. The panel also concluded that FDA should place a high priority on calling for PMAs for the partial implants. Summing up the opinion of the majority of panel members, panel consultant Charles Bertolami, DDS, University of California, Los Angeles, stated: "The magnitude and nature of the risks involved to individual patients in whom the implants may fail" could not be "controlled adequately under a Class II [special controls] designation." Although a non-voting member of the panel, Bertolami was the committee's lead reviewer of the existing data on partial TMJ implants. Specifying the risks associated with the partial TMJ implants, Bertolami referred to the hazards listed by FDA in its Sept. 18 Federal Register notice proposing Class III designations for the partial TMJ implants, total TMJ implants and interpositional TMJ implants ("The Gray Sheet" Sept. 21, p. 21). The risks include: "implant loosening or displacement" ** "degenerative changes to the natural articulating surfaces" ** "foreign body reaction" ** "infection" ** "loss of implant integrity" "corrosion" ** and "chronic pain." PMA studies would provide additional safety and efficacy data for the partial implants. Deborah Greenspan, University of California at San Francisco, stated: "I do not think the data is yet complete" on the safety and effectiveness of the partial implants, adding that "some of the preliminary data" from clinical trials of the devices "looks very promising." The one panel member who did not vote with the majority abstained. Larz Spangberg, DDS, University of Connecticut Health Center, said he was "not convinced that this device needs to be classified as a Class III device." The dental products panel did not make a classification recommendation for the partial implants at the 1989 meeting, maintaining that the devices should not be used because of the risks involved, particularly the potential for erosion of the natural glenoid fossa joint when a partial mandibular condyle prostheses is implanted. However, in September 1992, FDA issued a proposal for Class III status for all TMJ implants, including the partial devices. FDA said in its proposal that Class III is the only appropriate regulatory category for the partial implants because "general controls, either alone or in combination with the special controls applicable to Class II devices, are insufficient to provide reasonable assurance" of safety and effectiveness. The agency maintained that the implants "should be subject to premarket approval to ensure that each manufacturer of" the devices "develops sufficient information to provide reasonable assurance of the safety and effectiveness" of the devices. Following the publication of the proposal, the Washington, D.C. law firm of Patton, Boggs & Blow submitted a petition to the agency that argued that the classification proposal for partial implants was illegal because FDA had not obtained a formal recommendation from the advisory panel ("The Gray Sheet" Dec. 21, I&W-6). Consequently, the agency brought up the issue before the panel at the Feb. 11 session. In addition to considering partial TMJ implants, the panel made classification recommendations on two other types of preamendment devices: the dental electrical anesthesia device and the root apex locator. The products are among a list of devices identified under a Center for Devices and Radiological Health initiative to classify devices that were overlooked during previous classification efforts ("The Gray Sheet" July 13, p. 4). The panel unanimously recommended that FDA place the dental electrical anesthesia device into Class III. The group concluded that there is a lack of efficacy data for the device and uncertainty about its intended uses. Also used in general surgery applications, the device is designed to provide local anesthesia by passing an electrical current through the surgery site. The committee suggested that a call for PMAs for models of the device be a low priority. Richard Norman, DDS, Southern Illinois University, Alton, the lead panel reviewer of the products, cited two studies of the device in dental applications and said there is a "clear indication that the device is effective." However, Burton Rosan, University of Pennsylvania, expressed concern over the "very limited data" on the device's safety and effectiveness. "I do not like the data," he said. Panel members also were concerned about whether the device's leads and sensors could be adequately sterilized. Charles Kyper, assistant to the director at ODE, suggested that the device should be in Class III because the agency needs to know whether it is "really effective, and under what circumstances?" Thomas Callahan, associate director for reconstructive devices in the division of general and restorative devices of FDA's office of device evaluation, added that the intended uses of the device are "widespread," and "we really need to narrow that down." Panel members noted that one manufacturer is labeling its electrical anesthesia device for treatment of chronic pain caused by TMJ disorders. Root apex locators, used to measure the depth of a root canal when applying a filling, were recommended for Class II by the panel. Panel members identified no significant health risks associated with the device. Julianne Glowacki, PhD, Brigham and Women's Hospital, Boston, expressed the panel consensus that "all of the information presented to us appears to be consistent with the definition of Class II" devices. The device consists of a probe and two electrodes. One electrode is attached to the probe, the other to the patient's lip. The probe is then inserted into the root canal. When the probe touches the root apex at the bottom of the canal, electrical contact is made and the depth of the canal identified. Although the panel voted in favor of Class II, some members expressed concern that safety and effectiveness data on the apex locator was only available for single canals and not for double or triple canals. Greenspan commented that use of the device "in multi-rooted teeth is not well established." Another efficacy issue was raised by Paul Beninger, director of ODE's division of general and restorative devices. He said that it is not known how the device functions "in the face of metabolic imbalances" such as hyperglycemia and diabetes.