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ePaper created 2016-03-24, 17:16:09 | version 1.38.0
industry | 411 2016 implants play a role in tissue recession and prevention of crestal bone loss. The ability of the cells to attach and spread is dependent upon surface hydrophilic- ity(wettability)and“lack”ofsurfacecontamination. Although designed and labelled for single use, some clinicians advocate re-using—or “recycling”—heal- ing abutments from one patient to the next for purely economic reasons. A breach of manufacturer guidelines, this is not a wise choice. Five reasons why healing abutments are for single use only 1. According to Nobel Biocare guidelines, the company’s healing abutments should each only be used once. The argument against re-using a healing abutment is evident in the images above (Fig. 1). No matter the method used—steam or chemical autoclave, ultra-violet light, or ethylene oxide—sterilisation can never completely recreate the pristine surface of the original abutment. 2. Re-using a healing abutment labelled for single use may seriously degrade the performance of the product. Sterilisation with a steam autoclave, chemical autoclave, lasers or ethylene oxide may alter the composition of the titanium surface, negatively affecting cells. Physical surface topog- raphy changes the titanium wettability, which in- terferes with the epithelium and fibroblast cells’ ability to attach and spread. This effect is quite different from that of a new (i.e. not previously used) healing abutment. 3. New screw threads are vital for consistently fa- vourable results. The screw thread component of the healing abutment may also contain bio-bur- den after it has been removed, and a screw thread is by far the most difficult part of the healing abutment to clean (Fig. 2). Although not in direct contact with healing tissue, studies have con- firmed contamination and wear affect the screw thread and may result in damage within the im- plant. Contamination can also lead to healing abutments “locking” onto the implant. This is an extreme issue and has been known to result in the implant being reverse-torqued out of the bone in attempts to unscrew the abutment. 4. The screwdriver may not properly engage a re- used healing abutment. Very difficult-to-remove debris (Fig. 3) may clog the screwdriver insertion site. It should be noted that ultrasonic baths are not likely to get rid of this tightly packed material. Also, with repeated use, the screw head itself can become mechanically damaged. Case reports in the literature report that such damage—unneces- sary if you follow the manufacturer’s single-use guidelines—makes healing abutment retrieval problematic (Fig. 4). 5. Mechanical cleaning of a previously used abut- ment—especially via air particle abrasion—can damage the abutment/implant connection, thus reducing its sealing capacity and altering the component connection (Figs. 5a & b). Studies have also reported abrasive impregnation into the softer titanium, resulting in metal contamination. A potentially costly risk Take these five points under careful consideration and you will find that the potential monetary sav- ings of re-using a healing abutment a second time do not outweigh the known and potential health risks to the patient. In short: in order to provide pa- tients with the greatest chance of soft tissue at- tachment, minimised inflammation and the preven- tion of possible recession—and to give the bone a healthy start—always use a clean new healing abut- ment!_ Editorial note: Full references for this article are available online at nobelbiocare.com/news. Fig. 5a Fig. 5b Contact Nobel Biocare Services AG P.O. Box 8058 Zürich-Flughafen Switzerland Fig. 5: Scanning electron microscopy images of conical connection at 500 x magnification (a–to the left). The effect of air particle abrasion cleaning on the fitting surface of an implant abutment is clearly evident (b–to the right). The implant- abutment interface with a new, clean abutment surface for comparison. 4112016