ABSTRACT
The long-term stability of Class II, Division 1 nonextraction therapy, using cervical face-bows with full fixed orthodontic appliances was evaluated for 42 randomly selected patients. Part 1, a study model analysis, was published in the March 1996 issue of the JOURNAL. Each patient was treated by the same practitioner, with the same techniques, and the treatment goals had been attained for all patients. Pretreatment records were taken at a mean age of 11.5 years; the posttreatment and postretention records were taken 3.0 and 11.6 years later, respectively. The results showed that the ANB angle decreased 2 degrees during treatment, most of which was due to the 1.6 degree decrease of the SNA angle. The mandibular plane angle was not changed significantly during treatment. Although upper incisor inclination was maintained during treatment, the lower incisor was proclined 2.3 degrees and the lower molar was tipped back 4 degrees. Of the 22 cephalometric measures evaluated, only four indicated relapse related with the treatment change. Three of the four measures pertain to lower incisor retroclination subsequent to excessive proclination. The ratio of treatment proclination of incisors to posttreatment retroclination is approximately 5:1. Similarly, for every 3 degrees of molar tip back, there was approximately 1 degree of relapse. It is concluded that nonextraction therapy for Class II malocclusion can be largely stable when the orthodontist ensures proper patient selection and compliance and attains treatment objectives.
Subject(s)
Cephalometry , Extraoral Traction Appliances , Malocclusion, Angle Class II/therapy , Adolescent , Adult , Child , Evaluation Studies as Topic , Follow-Up Studies , Humans , Incisor/pathology , Longitudinal Studies , Malocclusion, Angle Class II/pathology , Mandible/pathology , Maxilla/pathology , Models, Dental , Molar/pathology , Orthodontic Appliances , Patient Compliance , Patient Selection , Recurrence , Serial ExtractionABSTRACT
The long-term stability of Class II, Division 1 nonextraction therapy remains poorly described. This study evaluates the face-bow therapy, in conjunction with full-fixed appliance therapy, of 42 patients (34 females and 8 males) who were treated by the same practitioner. Treatment goals had been attained for all patients. The pretreatment, posttreatment, and postretention records were taken at 11.5, 14.5, and 23.1 years, respectively. The results showed that mandibular and maxillary arch widths were increased significantly during treatment. Mandibular intercanine width decreased 0.3 mm during the postretention period; the remaining width measures increased or remained stable. Arch length, which did not change during treatment, decreased 1.0 mm after treatment. Overjet and overbite decreased 4.4 mm and 2.5 mm, respectively, during treatment. Both overjet (0.5 mm) and overbite (0.4 mm) showed small increases after retention. Mandibular incisor irregularity was decreased 2.7 mm during treatment and increased only 0.4 mm after treatment. Within the limits of this study, it is concluded that, when the described techniques are used, nonextraction therapy for patients with Class II malocclusion is largely stable.
Subject(s)
Extraoral Traction Appliances , Malocclusion, Angle Class II/therapy , Orthodontics, Corrective/methods , Adolescent , Adult , Child , Female , Follow-Up Studies , Humans , Male , Models, Dental , Recurrence , Retrospective Studies , Tooth Extraction , Treatment OutcomeABSTRACT
Specific antiserum raised against Calbindin-D28 kappa, a vitamin D-dependent calcium-binding protein (CaBP) isolated from chick intestine, was used for localization of the protein in developing rat molars. Previously, CaBP had been localized in specific cells associated with the continuously erupting rat incisor: late pre-secretory ameloblasts, secretory and maturation zone ameloblasts, stratum intermedium cells adjacent to ameloblasts in the late zone of enamel secretion, and papillary cells underlying maturation zone ameloblasts. In this study, the peroxidase anti-peroxidase technique was used for localization of the peroxidase anti-peroxidase technique was used for localization of CaBP in histological sections of rat mandibles from 18-day-old rat embryos through 20-day-old neonates. CaBP was not detected in any cells of the enamel organ, dental papilla, or dental sac during early odontogenesis from the dental lamina stage through the advanced bell stage. The protein first appeared in secretory ameloblasts which were situated opposite odontoblasts with newly secreted dentin. CaBP was present in the cytoplasm of more mature ameloblasts, but not in less mature ameloblasts. Some stratum intermedium cells subjacent to well-developed secretory and maturation zone ameloblasts also contained CaBP. The protein was not detected in odontoblasts, pulp cells, or other cells associated with the developing molars. It was also absent from the demineralized enamel and dentin matrix. In developing rat molars, the time-course of appearance of CaBP, a protein dependent for its synthesis on the vitamin D endocrine system in other organ systems, suggests a potential direct role of this hormonal system in enamel mineralization.
