![]() ![]() Identification of premature internal contacts can be performed with paint on occlusion indicator liquids (e.g., AccuFilm ® IV Arti-Spot ® ). These spots can often prevent complete seating when removed from the cast prior to restoration fabrication. This should not interfere with seating of the restoration and will be filled with the luting agent. If an air bubble remains on the cast after the impression is poured, a corresponding void will be created in the prosthetic material. Placing a curved intraoral impression tip into the deepest part of the preparation floor and extruding a light body polyvinylsiloxane (PVS) material - making sure to keep the tip in the material as it’s expressed - will force air out of the preparation, decreasing entrapment. These errors may be avoided by thorough flushing and drying of the preparation prior to impression taking. While the cause of large, internal, ill-defined areas in these preparations is usually fluid accumulation, air entrapment may also be a factor in narrow, deep preparations. In these cases, it is more prudent to take a new impression and be assured of accurate detail capture. Use of a wash impression is difficult in a completed inlay/onlay impression, as complete seating can be complicated and lead to either a “stepped” or distorted impression. This can be more critical when using all-ceramic materials, as they require minimum thicknesses to perform as expected. The prosthetic material may also be thinner than recommended. ![]() If they occur due to air entrapment, fit will not be compromised.īubbles that occur as a result of fluid accumulation may be large enough to affect the long-term success of the luting agent, which must now fill a wider space. If the bubbles occur on the internal line angles of inlay and onlay preparations due to fluid accumulation, a substandard fit will be developed. Bubbles on the margins of the preparations can negatively affect the fit of the prosthetics. Internal bubbles occur as a result of either fluid accumulation (when larger and less sharp in definition) or air entrapment (when small and well defined) (Fig. ![]()
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