[Evaluation of the three-dimensional stability using dental casts after orthognathic surgery]. / Valutazione gipsometrica della stabilità dimensionale dopo interventi di chirurgia ortognatodontica.

BACKGROUND: The increasingly frequent use of orthognathic surgery raises several questions on the results of operations, the resulting morphological and functional modifications, and the long-term three dimensional stability of the arches after surgery. In order to answer these questions a study was carried out using pre- and postoperative casts of the arches in a group of patients to evaluate the three dimensional stability of the correction. METHODS: Thirty-nine patients with different forms of malocclusion were selected who had undergone orthognathodontic surgery at least one year earlier. Twenty-seven patients (69.2%) received postoperative orthodontic treatment, including 9 who had undergone lower jaw surgery (33.3%), 3 maxillary surgery (11.1%) and 15 undergoing combined surgery (55.6%). Twelve patients (30.8%) did not receive postoperative orthodontic surgery, including 2 who had undergone lower jaw surgery (16.6%), 5 maxillary surgery (41.7%) and 5 undergoing combined surgery (41.7%). The two-dimensional reproductions of dental casts were studied using electronic image processing. Five different techniques were used (Bolton, Lundström, Howes, Staley and Reinhardt) to evaluate the dental arches. The study also evaluated whether any difference in results could be ascribed to use or absence of pre or postoperative orthodontic treatment. RESULTS: The results indicate that protocols and surgical techniques used produce dental arches that are three-dimensionally stable and the use of orthodontic treatment gives greater stability one year after surgery compared to cases treated with surgery alone. CONCLUSIONS: Major maxillary surgery should always be considered when assessing the possible solutions to malocclusions in order to correct anomalous bone formation with a reduced risk of recidivation of the correction.

[The determination of the level of the external osteotomy line in Le Fort I interventions for pure maxillary advancement]. / Determinazione del livello della linea osteotomica esterna negli interventi secondo Le Fort I di puro avanzamento del mascellare.

BACKGROUND: Therapy of severe malocclusions needs a cooperation between orthodontist and maxillo-facial surgeon. The aim of this study is to evaluate how the ortho-surgical team can get a common base of programmation to transfer on split-casts osteotomic simulation reaching a more exact surgical result. METHODS: In this paper were considered patients operated by orthognathic surgery from January 1994 to June 1997 have been studied. ENVIRONMENT: Patients were operated in the Institute in which authors work. PATIENTS: Patients included were 120, 65 female and 55 male between 20 and 42 (mean 31). OPERATIONS: Patients were operated, for the most part, by combined operation at maxilla and mandible. RECORDINGS: The mean of values noticed was calculated adding all values and dividing for the number of values. RESULTS: The mean calculated is 33 mm (DS 2,22) of distance from canine cusp and 29 mm (DS 2,19) from mesio-vestibular cusp of the first upper molar. CONCLUSIONS: This study demonstrates that it is possible, with a statistically significant precision, to transfer osteotomic reference lines from clinical practice to a planning more pertinent to surgical performance. In this study we tried to standardize a value to increase precision of surgery, transferring easily feasible surgical measurements to split-casts.