Cephalometric study of slow maxillary expansion in adults.

INTRODUCTION: The purpose of this retrospective study was to evaluate the dentoskeletal changes after slow maxillary expansion in adults. METHODS: Three kinds of maxillary expanders (Haas [Dyna Flex, Laboratory, St Louis, Mo], MAX-2000 [Dyna Flex], and DMAX-2000 [Dyna Flex]) were used randomly in 3 study groups of 65 adults treated with nonsurgical slow maxillary expansion, followed by full straight-wire appliance therapy. A control group of 22 adults, meeting the same inclusion criteria, were treated only with full straight-wire appliance therapy without expansion. Posteroanterior and lateral cephalometric records were taken before the start of treatment (T1) and after fixed orthodontic treatment (T2). The data were analyzed statistically by using paired t tests and Kruskal-Wallis H tests. RESULTS: From T1 to T2, there was no significant change in nasal width, maxillary width, and mandibular width in the 3 groups. The sella-nasion-mandibular plane angle increased 0.97 degrees (P <0.05) in the DMAX-2000 group. The mandibular incisor-mandibular place angle in the Haas, MAX-2000, DMAX-2000, and control groups had mean increases of 4.90 degrees, 4.42 degrees, 4.55 degrees, and 5.20 degrees (P <0.05 for each), respectively. The maxillary incisor-nasion-A-point angle increased 3.04 degrees (P = 0.05), and the distal root of the maxillary first molar-nasion perpendicular decreased 1.48 mm (P <0.05) in the control group. The distal facet of the maxillary first molar-nasion perpendicular decreased 3.57 mm (P <0.05), and the distal root of the maxillary first molar-nasion perpendicular decreased 2.50 mm (P <0.05) in the MAX-2000 group. CONCLUSIONS: After expansion treatment, there were no evident transverse or significant sagittal and vertical skeletal maxillary changes in the 3 groups.

The use of miniscrews for orthodontic anchorage.

The incorporation of miniscrews into orthodontic treatment planning has allowed for predictable control of anchorage and has increased the ability to correct severe skeletal discrepancy with nonsurgical orthodontics. It is the goal of this article to review the terminology, design, placement, and activation of miniscrews, as well as the advantages and complications associated with their use so that the multidisciplinary team will become familiar and comfortable with this novel treatment modality.

Effects of prestretching on force degradation of synthetic elastomeric chains.

INTRODUCTION: The purpose of this study was to evaluate the effects of prestretching on time-dependant force decay of synthetic elastomeric chains. METHODS: Five-unit (12.5 mm) and 6-unit (15.5 mm) modules (Generation II, Ormco, Glendora, Calif) were prestretched 100% for 1 hour (n = 12), 24 hours (n = 12), 2 weeks (n = 12), and 4 weeks (n = 12) in 37 degrees C distilled water. The prestretched and unprestretched (control) modules were then stretched to 30 mm in 37 degrees C water, and their forces were measured at 0 hour, 1 hour, 24 hours, and weekly for 4 weeks with a digital force gauge. RESULTS: The prestretched 5- and 6-unit modules yielded significantly lower initial force than the controls. All 5- and 6-unit prestretched and control groups showed substantial force decay during the first hour. However, at 1 hour, similar remaining forces were found in the 5-unit prestretched and control groups (P > .05), and small differences were seen in the 6-unit groups. The rates and patterns of force decay from 1 hour to 4 weeks were quite similar between the control and the prestretched modules of both the 5- and 6-unit groups. CONCLUSIONS: The effects of prestretching on force decay of elastomeric chains were noted mainly in the first hour. Thus, the clinical value of prestretching a synthetic elastomeric chain is questionable.

Mandibular basal structure response to lip bumper treatment in the transverse dimension.

The effect of orthopedic or orthodontic treatment on the transverse dimension has been the subject of endless debate among orthodontists. The purpose of this investigation was to examine the response on the transverse dimension of the basal structure of the mandible and maxilla following two different modalities of treatment: group A--standard edgewise orthodontic treatment and group B--maxillary orthopedics with a bonded (tissue borne) rapid palatal expander (RPE) combined with a mandibular lip bumper. Each group had a matched paired untreated control according to age, sex, race, and treatment duration. For all subjects the width of the maxilla (Mx-Mx) and mandible (Ag-Ag) were measured on pre- and posttreatment posteroanterior cephalograms. The rate of width change in the maxilla and mandible was calculated (in mm/y). Results showed that group A had no treatment effect on the transverse dimension of the maxilla and mandible when compared with controls. However, group B had a significant increase in the transverse dimension of Mx-Mx (P < .001) and Ag-Ag (P < .001) when compared with controls. It was concluded that the RPE treatment increased the maxillary skeletal width, and the lip bumper increased the transverse dimension of the basal structure of the mandible.

Ortodoncia: principios generales y técnicas

Diagnóstico y plan de tratamiento. Diagnóstico y plan de tratamiento en ortodoncia. Principios y reacciones biomecánicas. Fisiología, metabolismo y biomecánica del hueso en la práctica ortodóncica. Aplicación de la bioingeniería a la ortodoncia clínica. Aplicaciones de la informática en ortodoncia. Guía interceptiva de la oclusión con énfasis en el diagnóstico. Técnicas y tratamiento. Aparatos funcionales. Ortopedia combinada con aparato extraoral y activador. Tratamiento de la dentición mixta. Adhesión en ortodoncia. Aparato arco de canto de Tweed_merriefield: filosofía, diagnóstico y tratamiento. Mecánica de tratamiento con el aparato de arco recto. Interrelaciones ortodóntico-periodontales. Ortodoncia y cirugía ortognática: principios del tratamiento combinado. Contención y recidiva