A dental implant drill-guide system 50 for guiding the drilling of dental-implant cavities in an edentulous maxillary or mandibular arch has a plurality of orthodontic screw-seats 26 on a dental drill-guide 24 which are each engagable in position with the head 42 of an apical part 38 of a two-part orthodontic screw 14 inserted into the osseous tissue. The apical head 42 may have a collar 43a receivable into an aperture in the guide 24, and an apical flange 43b upon which the guide 24 rests. A coronal part 44 of the screw 14, which may be retained within the guide aperture, has a male thread 45 which is receivable within a female thread within the apical collar 43a to secure the guide in place, prior to drilling being carried out through the drill guide apertures and dental implants being inserted.
