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Objective: To investigate whether oral cleansing agents affect the essential work of fracture (EWF) and plastic work of fracture (PWF) for two types of orthodontic thermoplastic retainer materials. Materials and Methods: Polyethylene-terephthalate-glycol (PETG; Tru-Tain Splint) and polypropylene/ethylene-propylene rubber (PP-EPR) blend (Essix-C+) sheets were compared. For each material, six sets of 25 sheets were thermoformed into double-edge-notched-tension specimens; subsets of five specimens were formed with internotch distances (L) equal to 6, 8, 10, 12, or 14 mm, respectively. Sets were stored (160 hours, 25uC) in air (DRY), distilled water (DW), Original Listerine (LIS), mint Crest ProHealth (CPH), 3% hydrogen peroxide (HP), or Polident solution (POL). Specimens were fractured in tension at 2.54 mm/min. Areas under load-elongation curves were measured to determine total work of fracture (W f ). Linear regressions (W f vs L [n 5 25]) yielded intercepts (EWF) and slopes (PWF). Ninety-five percent confidence intervals were used to evaluate differences in EWF and PWF estimates. Results: PP-EPR blends showed higher EWFs after storage in HP vs storage in DW. PP-EPR blend showed higher EWFs after storage in CPH vs PETG. After HP storage, PP-EPR exhibited lower PWFs than with any other storage conditions. PP-EPR exhibited higher PWFs than PETG after storage in DRY, DW, and LIS. Conclusions: Compared with DW, none of the cleansers decreased the energy to initiate fracture. With one exception, no cleanser decreased the energy to continue plastic fracture extension. In PP-EPR blend, increased resistance to fracture initiation was observed with CPH and HP, yet, surprisingly, HP decreased resistance to plastic fracture growth. (Angle Orthod. 2010;80:554-561.)

Titanium and zirconia custom implant abutments are now commonly used for esthetic implant dentistry. Custom implant abutments allow the clinician to improve an implant's emergence profile, to customize cervical margins in accordance with the anatomy of the natural root, and to compensate for poor implant angulation. All of these are essential for optimum esthetic outcomes. Computer-aided design/computer-aided machining (CAD/CAM) technology allows the clinician to design custom implant abutment configurations and create natural-looking superstructures that are in harmony with the adjacent dentition and soft tissue. The CAD/CAM technique provides precise fit, reduces the cost of the procedure, and eliminates dimensional inaccuracies inherent in the conventional waxing and casting technique. The aim of this report is to describe a simplified technique for reconstructing emergence profiles during implant restoration using milled titanium and zirconia custom implant abutments. The results of 50 consecutive cases are reported.