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Summary Anterior mandibular alveolar osteotomy, as described by Hofer (1942), is a time-honored technique utilized in the correction of a variety of maxillo-mandibular disharmonies. Mobilization of the mandibular alveolar process further distally, certainly as far distally as the 3rd molar region, would seem to have very few indications. Mobilization of the entire alveolar process in this fashion, however, has proved successful in several situations, most predominantly infantile apertognathia. The author views mandibular condylar agenesis/hypoplasia and regression subsequent to mandibular repositioning through the ramus as other indications. Trauma to the inferior alveolar nerve is the most prominent theoretical and actual undesirable effect of this surgery, but, in all cases treated thus far, post-operative paresthesias have been transient. Maintenance of the desired occlusion with no suggestion of regressive tendency (longest postoperative period 27 months) is the major advantage of the technique. Review of the European and American literature suggests that total mandibular osteotomy has not been previously reported.

Some animals which carry the sex-linked gene for tabby ( Ta ) in the mouse have a supernumerary molar in front and/or lack the third molar at the back. In Ta ♂♂ and Ta/Ta ♀♀, presence or absence of these features must be due to threshold mechanisms. The threshold levels are essentially the same both in Ta / + ♀♀ and in Ta ↔ + chimaeras (as also in the autosomal mimic of tabby, crinkled, where cr/cr and + /cr are similarly affected). The data on the molars of Ta and Ta / Ta , on Ta / + and on Ta ↔ + do not discriminate for or against the inactive X-chromosome hypothesis. Possible explanations are suggested for the fact that the phenotype of Ta ↔ + chimaeras shows a shift towards tabby as compared with Ta / + heterozygotes.