Histologic Tissue Rearrangement Following a Circumferential Supracrestal Fiberotomy on Orthodontically Rotated Teeth in Dogs

Abstract

The purpose of this study was to determine whether a circumferential supracrestal fiberotomy has a biologic basis in the management of rotational relapse.

The maxillary second incisors of seven beagle dogs, approximately two years of age, were rotated orthodontically from nine to 52 degrees. The incisors were retained. A circumferential supracrestal fiberotomy was performed twice unilaterally on the maxillary left second incisor of six dogs by incising through the gingival crevice parallel to the long axis of the tooth. The seventh dog was sacrificed and used for comparison of the tissue rearrangement after rotation but before fiberotomy and/or retention. The remaining dogs were paired for retention periods of one, three, and six months.

Ten days before sacrifice all seven dogs were injected intraperitoneally with procion brilliant red H-8BS to determine appositional activity. At the end of the respective retention periods, the dogs were sacrificed and the specimens were fixed, decalcified, and serially sectioned horizontally, perpendicular to the long axis of the teeth. Sections were stained with H and E for histologic examination using light microscopy. Some sections were left unstained for evaluation of procion labelling using fluorescent light microscopy. The rearrangement of the subcrestal periodontal ligament fibers was determined by whether they produced a force capable of causing an increased alveolar and/or cemental apposition and not by their angulation to the root surface.

The results failed to support a biologic basis for performing circumferential supracrestal fiberotomies on orthodontically rotated teeth. The supracrestal fiberotomy combined with retention had no additional effect on increasing the rearrangement of the supracrestal tissues compared to retention alone. Six months of retention, with and without a supracrestal circumferential fiberotomy, was sufficient for the supracrestal tissues to rearrange. Some of the subcrestal periodontal fibers in the tension and pressure areas at six months in retention may play a role in relapse. Undermining root resorption was evident in some pressure areas.

Neither the angulation of the subcrestal and supracrestal periodontal fibers to the tooth surface nor the angulation of the epithelium was an accurate measure of the amount of tissue rearrangement. The circumferential supracrestal fiberotomy caused a cemental hyperplasia adjacent to areas nicked by the scalpel blade.