240 orthodontic brackets were bonded to buccal surfaces of bovine teeth. As bonding material we used four glass ionomer cements without etching and two normal orthodontic bracket bonding materials with etching of enamel. Brackets of group 1 were tested with a material testing machine for shear and tensile strength after ten minutes. Brackets of group 2, 3 and 4 were tested after one day, 28 days and 98 days, respectively. In the average the bonding strength of glass ionomer cements was 50% less than the bonding strength of the comparison group with etching. The fracture of the bonding took place to 80% between the mesh base and the glass ionomer cements. Defects of the enamel surface were never observed. The bonding between mesh-base and glass ionomer cements has to be improved before the use of this bonding material can be recommended for the use in a busy practice.

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The new removable double-plate appliance has characteristics which provide for efficient treatment of Class II malocclusions: virtually unimpaired speaking and free breathing seem to support patient compliance. The sagittal activation is easy to change and the plates for the upper and the lower jaw can be worn separately or in combination, with and without the "Pro-Stab" rods even with different wearing hours (modular concept). Evaluation of lateral head films taken at the beginning and at the end of treatment (mean interval 1.45 years) of 40 patients provided information on therapy-induced changes, which were then compared with results of recent publications. The data obtained with the new system indicate similar results as with bite-jumping appliances and headgear-supported activators. Inhibition of the sagittal development of the upper jaw and retrusion of the upper incisor segment have been primarily responsible for the correction of Class II malocclusions. The effect as regards the sagittal position of the lower jaw has been moderate. In comparison with similar appliances, protrusion of the lower incisors was more pronounced when treated with the Goettingen Type I "Pro-Stab" removable plate system.

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The temporomandibular joint function of 66 children (mean: 11.5) with malocclusion was investigated with help of axiographic tracings. Besides other parameters of the tracings we studied the relationship between centric occlusion, centric relation and their positions in regard to the axiographic tracing line of the protrusion movement with a gauge between the front teeth. The distance between CR and CR measured as a vector was 0.7 mm (+/- 0.4 mm). Though we investigated a group with serious malocclusions the distance of CO measured perpendicular to the gauge protrusive tracing was 0 (+/- 0.4 mm). In 60 joints the CO tracing point did not coincide with the gauge protrusive line: On account of these measurements the terms compression and distraction of the joint have a graphic meaning. In 4% of the children we found tracings which were typical for joint pathology: reciprocal clicking. In 21% of the patients we found "disturbed" tracings, but their prognostic value is still unknown.