Principles of Attachment Selection for Implant Supported Overdentures

making oral hygiene maintenance very difficult to perform. (Fig. 12B) Compression of the ­mucosa by the bar will cause hyperplasia of the gum. (Fig. 12C) It will also be impossible to clean underneath the bar. To

Sagittal Relationship of the Bar

to the Alveolar Ridge

The bar should be positioned directly above the crest of the ridge. (Fig. 12D) This position makes it easy to clean the bar and fabricate the prosthesis above the bar. If the bar is positioned lingual to the crest of the ridge, it will interfere with the tongue space, impeding function and speech. This problem is common in patients with a narrow and pointed alveolar ridge. One way to prevent this situation is to relocate the bar further ­anteriorly. Another solution is to use individual attachments. (Fig. 12E) If the bar is positioned labial to the crest of the ridge, it will interfere with lip support. Both labial and lingual scenarios will make fabrication of the prosthesis very difficult. (Fig. 12F)

Sagittal Relationship of the Bar

to the Hinge Axis

Ideally, the anterior bar in the edentulous mandible should be parallel to the hinge axis. (Fig. 13A) However, this relationship should be considered another reference for better positioning of the bar, because this orientation can’t be achieved in every case. Many clinicians have followed this rule, but as mentioned earlier, no studies have supported this claim. One long-term study (5-15 years) analyzed the influence of placing the bar parallel to the hinge axis on peri-implant parameters, including the clinical attachment level.35 The outcome of splinted versus un-splinted ­attachment was also assessed. No significant correlations were found.

SROMS

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Volume 19.6