Does labial movement of lower incisors influence the level of the gingival margin? A case-control study of adult orthodontic patients.

It has been suggested that proclination of the lower incisors results in gingival recession. Proclination is, however, a valuable alternative to extraction especially when considering facial aesthetics in adult patients. The aim of this study was to evaluate the association between the extent of labial movement of the lower incisors and the prevalence and severity of gingival recession in orthodontically treated adult patients. A retrospective case-control study based on the analysis of study-casts and intra-oral slides of 300 adult patients was carried out. One hundred and fifty pairs matched by age and sex were selected using simple random sampling. Recordings of gingival recession were made using casts as well as intra-oral slides. Dental displacement was measured on casts comparing the measurements before and after treatment. The intra-oral slide recordings of gingival recession were more reliable than the cast recordings. Although the difference in prevalence of individuals with gingival recession among cases and controls was statistically significant (P < 0.001), no significant difference in the mean recession value could be found between cases and controls (P > 0.10). The mean value of the extent of recession of the four lower incisors amounted to 0.36 mm for treated subjects and 0.22 mm for the controls. This mean difference of 0.14 mm between members of a pair was not clinically relevant. Faced with the alternative between extraction and labial movement of lower incisors the present study indicates that the latter is a valuable alternative leading to no clinically relevant deterioration of the periodontium.