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Common attachment defects classification
| Defects that fundamentally change the attachment size. | ||
|---|---|---|
| Overfill | Excess composite resin associated directly with the attachments’ surfaces results in an attachment that is larger volumetrically than planned. The overall shape of the attachment can be accurate; however, excess resin in the template causes the attachment to protrude further than intended (Figure 3A) | |
| Underfill | A deficiency in the composite resin results in decreased attachment volume and smaller surfaces than planned. However, the overall shape of the attachment remains intact (Figure 3B) | |
| Volumetric | Bowing | A discrepancy that results in one or more attachment surfaces being distorted towards the centre of the attachment ridges, creating a bowed appearance. This is most likely attributed to distortion within the attachment template because of pressure on this more flexible part of the template (Figure 3C) |
| Shape | Attachments with a significant volumetric error so that the ridges are not accurately reproduced, resulting in a defect in the overall shape (Figure 3D) | |
| Separation | The shape of the attachment ridges and the active and passive faces are intact; however, there is a substantial volumetric defect at the base of the attachment between the attachment and the tooth (Figure 3E) | |
| Abrasion | Abrasion is the gradual loss or distortion of an attachment due to mechanical and/or chemical interactions. Attachments exist in the oral environment; abrasion of attachments occurs through normal oral functions and repeated removal and replacement of aligners. (Figure 3F) | |
| Locational | Defects due to the attachment being bonded in a position other than what was planned (Figure 3G) | |
| Errors | Defects in attachments that do not fit into one of the other categories | |
| Bubbles | There is a minor round volumetric error at the surface of the attachments (Figure 3H) | |
| Porosities | Bubbles in the composite resin that are contained within the body of the attachment. These may not affect the overall dimensions of the attachment; however, they may affect its structural integrity and the aesthetics of the attachment (Figure 3I) | |
| Roughness | Increased surface roughness when compared to the ideal CAD-CAM design due to the attachment template being formed on a coarse 3D printed model (Figure 3J) | |
| Flash | A thin layer of excess composite around the perimeter of the attachment, which does not affect the attachment volume but may compromise the accuracy of the location of the attachment (Figure 3K) | |
| Bonding | Failure of the bonding of the attachment to the tooth (Figure 3L) |