P. Lionel Sadowsky

Combined rapid maxillary expansion and protraction facemask in the treatment of class III malocclusions in growing children: A prospective long-term study

A prospective study of 28 growing children (mean age of 8 years 3 months) with Class III malocclusions was consecutively treated using rapid maxillary expansion and maxillary protraction. All patients were treated from a negative overjet to a positive overjet and from a Class III dental malocclusion to a Class I dental relationship. For each patient, a lateral cephalogram was taken before treatment (T1), immediately posttreatment (T2), and after an observation period (T3) averaging 2 years 5 months. Using analysis of variance, the cephalograms were analyzed to determine skeletal and dental changes resulting from treatment. Long-term changes (2 years 5 month observation period) were also evaluated. Results showed that immediately posttreatment, the maxilla moved anteriorly a mean of 1.54 mm and Sella-Nasion-A point increased 0.87 degree. The maxillary teeth moved anteriorly 2.73 mm and proclined 5.23 degrees, while the mandible rotated in a downward and backward direction. Long-term, the anterior position of the maxilla was maintained, but some of the Class III correction was lost because of mandibular growth. Comparison of this studys results to Riolos longitudinal Class I data showed that, overall, rapid palatal expansion and maxillary protraction produced a small orthopedic effect with a moderate dentoalveolar effect which together contributed to the correction of the Class III malocclusion.

An in vitro evaluation of a metal reinforced orthodontic ceramic bracket

The objectives of the present study were to measure and compare the bond strength and failure sites of a currently available ceramic bracket (Transcend 3M-Unitek) with the new metal reinforced ceramic bracket (Clarity 3M-Unitek) and to evaluate the amount of composite left on the tooth using the Adhesive Remnant Index in the teeth that were debonded with pliers recommended for this purpose. In addition, the presence or absence of enamel damage after debonding was also assessed. One hundred and twenty extracted premolar teeth were divided into 4 groups of 30 each. Two groups of 30 teeth had Transcend 6000 brackets bonded, and the other 2 groups had Clarity brackets bonded. Shear bond strength was carried out on 30 Transcend 6000 brackets and 30 Clarity brackets, whereas the other 2 groups of 30 teeth bonded with Transcend 6000 and Clarity brackets were debonded with debonding pliers recommended by the manufacturer of both ceramic brackets. The mean shear bond strength of the Clarity brackets was 13.27 MPa, whereas that of the Transcend 6000 was 21.19 MPa. Both brackets failed mostly at the bracket-adhesive interface (75%), indicating a possible reduction of the chances of enamel damage. Six of the premolars, bonded with Transcend 6000 brackets and debonded with the plier, showed an increase in the number or length of enamel cracks as evaluated by an optical microscope (Micro-Vu); one premolar, bonded with Clarity brackets and debonded with the pliers, showed an increased enamel crack length. Gross enamel damage, assessed by enamel dislodgment, was not evident in any specimen. Results of this study suggest that the new metal reinforced ceramic bracket (Clarity) may be recommended for clinical use because of its acceptable shear bond strength and possible reduced chances of enamel damage during bracket removal.

Orthodontic Appliances and Magnetic Resonance Imaging of the Brain and Temporomandibular Joint

Experimental and clinical studies find that orthodontic appliances can produce artifacts in MRI, mostly in the facial region. Removal of removable components, especially archwires, with close checking of the security of banded and bonded attachments, should be sufficient in most cases requiring this diagnostic procedure.