A LONG-TERM STUDY OF TRANSVERSE STABILITY OF MAXILLARY TEETH IN PATIENTS WITH UNILATERAL COMPLETE CLEFT-LIP AND PALATE

The aim of this study was to investigate the long term post-treatment transverse stability of the maxillary dental arch in subjects with uni lateral complete cleft lip and palate (UCLP) treated by the Harvold/Bo hn method of orthodontic expansion and prosthodontic retention. The tr eatment of 22 consecutive patients, primarily operated on during the p eriod 1957-60, was completed at a mean age of 18.1 years by the provis ion of a fixed partial retention prosthesis across the cleft using the cleft side central incisor and canine only as abutment teeth. The cle ft side lateral incisor was missing in each case. Dental casts were ma de at the time of abutment preparation and at six subsequent times wit h the final observation 13.5 years after treatment completion. Measure ments of any shift in the transverse position of cleft side and non-cl eft side canines, premolars and first molars were made on standardized photographs of the casts. A constructed anteroposterior palatal line served as 'midline' reference. A mean reduction of width at the final observation, as recorded from the palatal surface to the reference lin e, was for the cleft side canine: -0.4mm, the premolar immediately dis tal to the prosthesis and the first molar: both -1.2 mm. The correspon ding mean width reductions on the noncleft side were: canine -0.9mm, p remolar -1.2mm, first molar -1.6 mm. The rate of movement towards the midline decreased linearly with In(time) for all variables (P < 0.02) but for the cleft side canine.