Premolar transplantation in a patient with solitary median maxillary central incisor syndrome.

This case report describes the orthodontic treatment of an 11-year-old girl with solitary median maxillary central incisor syndrome, a presumed microform of holoprosencephaly. Because both second premolars were missing in the maxilla, deciduous molar extraction and orthodontic space opening were performed, moving the solitary median maxillary central incisor electively off-center. A mandibular second premolar was transplanted to replace the missing incisor. The resulting spaces could be orthodontically closed in both arches. Prosthodontic reshaping of the transplanted tooth after debonding completed the dental treatment.

Upper molar distalization with skeletally anchored TopJet appliance.

OBJECTIVE: To retrospectively investigate clinical outcomes with the TopJet appliance. MATERIALS AND METHODS: Measurements were taken on dental casts reflecting situations in 15 patients aged 10-48 years before and after orthodontic treatment with a TopJet appliance. Each measurement was taken with a digital caliper and repeated 2 weeks later. Recorded parameters included the amounts of distalization achieved, durations of active treatment to calculate rates of tooth movement, as well as rotational and transversal changes involved in the distalization of upper first molars. Student's t-test was used to compare mean values (α=0.05), explorative analysis to distinguish between unilateral and bilateral use of TopJet appliances, and Pearsons's correlation coefficient to determine intraobserver variability. RESULTS: Over a mean treatment duration of 5.9 months, the upper first molars were distalized by 4.0 ± 2.2 mm, including a mean tooth movement rate of 0.8 ± 0.6 mm per month. The rotational changes involved in the movements (-1.4 ± 6.7°) were not statistically significant. Transversal changes were 0.9 ± 1.2 mm at the level of the mesiobuccal cusps, 1.1 ± 1.1 mm at the central fossae, and 0.9 ± 0.9 mm at the distobuccal cusps. All measurements, other than those for rotation (r=0.7), were highly reproducible. Bilateral use of the appliance resulted in greater distalization than unilateral use, the mean difference being 1.4 mm. Bilateral use was more likely to involve inward rotation (+2.0°) on the mesial aspect of the first molars, whereas unilateral use resulted in mild outward rotation (-0.5°). CONCLUSION: Our results indicate that upper molars can be distalized effectively and efficiently with TopJet appliances. Any degrees of rotation and transversal changes that the first molars undergo during this process do not seem to play a major role.

Influence of surface conditioning on ceramic microstructure and bracket adhesion.

The objective of this study was to investigate the influence of different conditioning procedures on various ceramic microstructures and bracket adhesion. Ceramic specimens (feldspathic, leucite, leucite-free, and fluorapatite) were mechanically conditioned (n = 20 per ceramic type) with conventional hydrofluoric acid (5 per cent HF; 60/30 seconds), buffered hydrofluoric acid (9.6 per cent BHF; 60/30 seconds), or sandblasting (Al(2)O(3)/SiO(2) particles). Silane coupling agents were added for chemical conditioning before bracket bonding. Bracket adhesion was calculated with a shear test in a universal testing machine. The bracket-composite-ceramic interface was further evaluated using the adhesive remnant index (ARI). One specimen of each ceramic/conditioning combination was subjected to qualitative electron microscopy investigation. One-way analysis of variance followed by Tukey's honestly significant difference test were applied for inferential statistics. Conditioning with conventional 5 per cent HF or sandblasting resulted in significantly (P < 0.001) higher bond strengths (mean values: 34.11 and 32.86 MPa, respectively) than with 9.6 per cent BHF (mean value: 12.49 MPa). Etching time or sandblasting particles had no statistical (P > 0.001) influence on bond strength. Higher ARI scores were found in the conventional 5 per cent HF and sandblasted groups, when compared with the 9.6 per cent BHF group. Microscopic examination of the conditioned ceramic surfaces showed that leucite and leucite-free ceramics differed most with respect to their surface roughness, though without an influence on shear bond strength (SBS; P < 0.001). Bracket adhesion was mostly influenced by the conditioning procedure itself. Sandblasted ceramic surfaces showed sufficient conditioning and bracket adhesion; however, the increased bracket adhesion was associated with a risk of ceramic surface damage.

Shear bond strength of fluoride-releasing orthodontic bonding and composite materials.

Several fluoride-releasing bonding materials are available for orthodontic bracket placement. These are supposed to prevent white spot lesions during therapy. The objectives of this in vitro study were to evaluate the shear bond strength (SBS) and failure mode of a recently introduced fluoride-releasing adhesive, as well as the comparison with established orthodontic adhesives. Sixty bovine mandibular incisors were randomly allocated to three groups (n = 20): stainless steel brackets were bonded with Transbond Plus Color Change Adhesive, Transbond XT, or Light Bond. A universal testing machine was used to determine the SBS at a crosshead speed of 1 mm/minute. After debonding, the adhesive remnant index (ARI) was used to assess the adhesive remaining on the brackets. One-way analysis of variance comparing the three experimental groups showed no differences between the bonding systems for mean SBS (P = 0.27). ARI scores showed more residual adhesive on the teeth bonded with the Transbond systems (P < 0.01). As the fluoride-releasing bonding system provided sufficient mean bond strength in vitro (19.9 MPa), it may be used as an additional prophylactic measure in orthodontic therapy. However, the clinical effectiveness of its fluoride release may be questionable, as the amount of fluoride required from a bonding material to be caries preventive is still unknown.