two to four notches are made below the mylohyoid ridge (5). The length of these grooves are dictated by the overall contour, slope and amount of undercut that exists beneath the mylohyoid ridge. The width and depth of these grooves should be no wider than 2mm and no deeper than three quarters of a mm respectively. The sharp line angles of the grooves are smoothed away with a tapered diamond stone (6). These grooves serve as a two-fold purpose; for immediate retention and seating of the implant, so that the lingual fingers of the implant fit flush with the bone therefore, the thin friable lingual tissues are not stretched nor interfered with, once the implant is seated and the tissues sutured closed (6a).

With a mix of heavy silicone, the material is moulded over the entire exposed area of the bone, making sure to include the external oblique ridge, the mental nerve area, the inferior border of the bone anterior to it, most of the lingual border of the mandible, and at least two or more anterior teeth. The patient's jaw is brought into a centric relationship and the patient is told not to move his teeth or open his mouth during which time the operator moulds the material accurately to the bony topography (7). Some of the excess flash of the material flanking the lingual and buccal surfaces of the upper teeth is then removed with a scalpel, being sure to keep the impression in place during this procedure (8). This enables the operator to then take a full lower elastic or stone impression of the remaining teeth of the lower jaw, including the silicone impression of the partially edentulous area. It is now preferred by the author, to use a rubber impression, using a pre-fabricated Omnivac tray. This tray is fabricated from a previous direct bone impression, using either silicone or rubber base material. With this rubber impression inside the Omnivac tray, and fitted over the partially edentulous bony quadrant, the author, then picks it up with a full mouth lower impression, using again, rubber base material (9). The entire model is poured in stone and carefully the elastic or plaster impression is separated from the

105