Palatal expansion using a bonded appliance. Report of a case.

A case involving the use of an acrylic-lined bondable palatal expansion appliance is reported. The proposed design modifications allow the expansion appliance to be used in patients of any dental age while keeping the palate free of acrylic. Clinical trial of this appliance suggests that it is an acceptable alternative to conventional expansion appliance designs.

Lower premolar extraction/removable plastic Herbst treatment for mandibular retrognathia.

The patient was a 12-year-old girl with a Class I malocclusion characterized by maxillary arch width constriction, dental crowding, and mandibular retrognathia. Treatment goals related to the chief compliant were anterior mandibular repositioning, maxillary arch expansion, and dental alignment. Because the preexisting overjet was minimal and prevented adequate anterior repositioning of the mandible, lower first premolar extraction was recommended to increase the overjet and allow greater anterior repositioning. Treatment was divided into four stages: (1) extraction of mandibular first premolar teeth, alignment, space closure, and an increase in the overjet, (2) anterior mandibular repositioning with a removable plastic Herbst appliance, (3) arch alignment and detailing of the occlusion with full fixed appliances and a tooth positioner, and (4) retainers. At the end of treatment, the patient had an acceptable dental alignment with a Class III molar relationship and an improvement in facial appearance.

Clinical management of the acrylic splint Herbst appliance.

This article describes one variation in Herbst appliance design--the acrylic splint Herbst. Topics discussed include early fixed appliance treatment before Herbst therapy, impression taking, bite registration, and evaluation of appliance fabrication. The specifics of appliance delivery, including bonding of the maxillary appliance when indicated, are also discussed as are the techniques of appliance advancement and removal.

A comparison of the Herbst and Fränkel appliances in the treatment of Class II malocclusion.

This study investigated the treatment effects produced by two types of functional appliance, one primarily tooth-borne (the Herbst appliance) and one primarily tissue-borne (the FR-2 of Fränkel). Serial cephalometric radiographs from 45 patients who had been treated with the acrylic splint Herbst appliance and from 41 patients who had been treated with the FR-2 appliance were compared with serial radiographs of 21 untreated persons with Class II malocclusions. Treatment effects were identified through the use of a conventional cephalometric analysis. The results of this study indicated that both appliances had influenced the growth of the craniofacial complex in treated persons. Significant skeletal changes were noted in both treatment groups, with both groups showing an increase in mandibular length and in lower facial height, as compared with controls. Greater dentoalveolar treatment effects were noted in the group wearing the tooth-borne functional appliance than in those wearing the tissue-borne appliance.

An examination of dental crowding and its relationship to tooth size and arch dimension.

This investigation was undertaken to examine the extent to which tooth size and jaw size each contribute to dental crowding. Two groups of dental casts were selected on the basis of dental crowding. One group, consisting of 50 pairs of dental casts (18 males and 32 females), exhibited gross dental crowding. A second group, consisting of 54 pairs of dental casts (24 males and 30 females), exhibited little or no crowding. Means and standard deviations of the following parameters were used to compare the two groups: individual and collective mesiodistal tooth diameters, dental arch perimeters, and buccal and lingual dental arch widths. Statistically, the crowded and noncrowded groups could not be distinguished from each other on the basis of mesiodistal tooth diameters. However, significant differences were observed between the dental arch dimensions of the two groups. The crowded group was found to have smaller dental arch dimensions than the noncrowded group. The results of this study suggest that consideration be given to those treatment techniques which increase dental arch length rather than reduce tooth mass.

Magnetic bead purification of M13 DNA sequencing templates.

A method for the preparation of multiple M13 DNA sequencing templates is described. No phenol extraction is required and the procedure can be carried out in Eppendorf tubes or 96-well microtiter plates. Starting with a phage supernatant, the entire procedure is carried out in the same reaction vessel and all separation steps are based on a novel application of magnetic bead separation. The design of a 96-well magnetic separator is presented and the application of the method for large-scale sequencing is discussed.