Augmentation of faciolingual gingival dimensions with free connective tissue grafts before labial orthodontic tooth movement : an experimental study with a canine model

Purpose: The aim of this study was to determine in an animal model whether any increase in gingival thickness after placement of free connective tissue autografts is maintained after labial orthodontic tooth movement. Material: In a split-mouth technique, the maxillary second and third incisors of 4 adult greyhounds were used as experimental, control, and sham-control teeth. The experimental teeth underwent gingival augmentation surgery. Two to 3 months later, the teeth were moved with a bonded orthodontic appliance over 2 to 3 months. Baseline and 2-month retention clinical measurements of gingival height were taken before the animals were killed. Histometric measurements recorded the free gingival height and the gingival thickness at 5 graduated levels down the teeth. Results: Clinical measurements of changes in gingival margin position revealed a mean coronal shift of 0.44 mm over grafted teeth, with 50% of nongrafted teeth and 100% of the sham-control teeth experiencing small amounts of gingival recession. The histometric results showed that gingival thickness measurements for the grafted teeth were, on average, between 0.13 and 0.18 mm thicker at all levels of measurement than for the nongrafted teeth (P < .01). Conclusions: Free connective tissue grafts placed on the labial aspect of incisors might help prevent the faciolingual thinning of the gingival tissues that can occur as a result of labial orthodontic tooth movement. Further research is required to confirm these results in a larger sample and determine the long-term benefits of preorthodontic gingival augmentation to prevent gingival recession.