Clinical crown length of the maxillary anterior teeth preorthodontics and postorthodontics

BACKGROUND: Prevalence information on excessive gingival display in postorthodontic patients is limited. By studying the size relationship of the clinical crowns of teeth, in an orthodontic population, we can begin to quantify their need for periodontal plastic surgery. METHODS: Preorthodontic and postorthodontic crown dimensions were measured on 200 plaster models, and after 5 years, 31 of the subjects were recalled to repeat the measurements in a clinical examination. The measurements included clinical crown lengths and widths of the six anterior teeth, and these values were compared to known ideals. RESULTS: This study revealed a significant increase in the length of the maxillary anterior crowns over the three examinations, yet these values were still approximately 1.5 mm shorter than ideal. The mean crown width-to-length ratio was 87% to 88% for maxillary central incisors, clearly above the accepted "ideal." In addition, 61% to 71% of maxillary central incisors exceeded allowable crown width-to-length ratios, and 61% of subjects displayed asymmetry in gingival architecture. CONCLUSIONS: Although this study only examined one aspect of excessive gingival display, to our knowledge it is the first study to show that in a predominantly young, postorthodontic population, the prevalence of non-ideal width-to-length ratios is >65% and the presence of asymmetry is >60%. Therefore, close interaction between the periodontist and the orthodontist is necessary to diagnose these conditions to provide patients with all options for improving their smile.