Shear bond strength after multiple bracket bonding with or without repeated etching.

The purpose of the study was to measure the in vitro shear bond strength (SBS) of metal brackets after multiple bonding and debonding with and without repeated etching. One hundred and twenty extracted premolars were divided into three equal groups. In group 1, the brackets were bonded and debonded three times with repeated enamel etching and in groups 2 and 3 without repeated etching. In group 2, all composite remnants were removed before bonding, while in group 3, the remnants were levelled. Analysis of variance was used to determine significant differences in SBS with Bonferroni adjustment for the multiple testing procedures. The results showed that in group 1, the mean SBS was 11.69 MPa (SD 2.65) at the first, 14.30 MPa (SD 2.69) at the second, and 12.19 MPa (SD 2.26) at the third debonding. In group 2, SBS decreased from 12.57 MPa (SD 2.54) to below 8.0 MPa. In group 3, SBS remained constant from the first (11.93 MPa; SD 2.14) to the second (12.06 MPa; SD 1.65) debonding and only decreased significantly to 9.74 MPa (SD 1.80) at the third debonding. Less composite remained on the teeth after each debonding sequence. This was characterized by a shift from adhesive remnant index (ARI) scores 2 and 3 after the first debonding to ARI scores 1 and 2 after the second debonding to predominantly scores 0 and 1 after the third debonding. After bracket loss and levelling of composite remnants, the SBS is sufficient for application of orthodontic forces. Repeated etching may involve a higher risk of enamel tear-outs during debonding.

Autotransplantation of first premolar to replace a maxillary incisor - 3D-volume tomography for evaluation of the periodontal space.

UNLABELLED: The anterior maxilla is the most traumatized region during childhood and tooth loss is frequently involved. Space closure with implants is contraindicated in growing patients and maintenance of space is necessary over a long period. Transplantation of premolars from the mandible with two-third to three-quarter root formation wide open foramen provides the best prognosis for permanent survival. CASE REPORT: This report describes the management of a 10 year old girl with autotransplantation to replace an upper incisor by a lower premolar under consideration of special care for the periodontal ligament during surgical procedure. A 3-D imaging with digital volume tomography (DVT) was used 20 months after transplantation to evaluate the periodontal morphology. DISCUSSION: Autotransplantation of premolars with incomplete root formation to replace maxillary incisor is a treatment alternative after traumatic loss of teeth. There were no signs of pathosis like resorption or ankylosis and a normal periodontal space demonstrated with DVT. There is no need for endodontic treatment before transplantation. In this case of autotransplantation of a premolar, the DVT after 20 months gives evidence of a successful regeneration of the periodontal ligament.