Class II:2 malocclusion-prevalence and progression of labial gingival recessions during Herbst-Multibracket appliance treatment.

OBJECTIVES: To determine the prevalence, incidence, and changes in magnitude of labial gingival recessions (LGR) in class II:2 patients during Herbst-Multibracket appliance (Herbst-MBA) treatment (Tx) plus retention. SUBJECTS AND METHODS: All class II:2 patients of the Department of Orthodontics, University of Giessen, Germany who completed Herbst-MBA Tx (mean pre-Tx age 15.6 years). The cohort had undergone a Herbst phase (mean 8.1 months) as well as a subsequent MBA phase (mean 14.4 months). Study casts were evaluated from pre-Tx and after Herbst-MBA Tx plus ≥ 24 months of retention. RESULTS: Ratable pre-Tx and post-retention study casts (total observation period 53.5 ± 10.3 months) were available from 94 out of 173 patients. No significant difference existed regarding pre-Tx LGR data between patients with and without complete records. The prevalence for teeth with LGR ≥ 0.5 mm was 1.4% pre-Tx respectively 6.7% post-retention. The highest values of up to 5.3% (pre-Tx) and 20.2% (post-retention) were determined for the upper first premolars and lower central incisors. Incidence values of 4.7% (all teeth) and up to 14.9% (upper first right premolars) respectively 11.1% (lower central incisors) were calculated (LGR ≥ 0.5 mm). The overall LGR mean magnitudes were 0.01 mm pre-Tx respectively 0.06 mm post-retention. CONCLUSIONS: For the prevalence of LGR ≥ 0.5 mm an average increase of 5.3% was determined during ≈ 4.5 years of Herbst-MBA Tx plus retention. The highest incidence was seen for lower central incisors and upper right premolars (11.1/14.9%). The overall LGR mean magnitude increased by 0.05 mm. CLINICAL RELEVANCE: Herbst-MBA Tx is a common approach for class II:2 malocclusions. Very little, however, is known regarding LGR development in respective patients.

Herbst-multibracket appliance treatment: is there an association between lower incisor position changes and the development of labial gingival recessions?

PURPOSE: To assess a potential association between lower incisor (LI) position changes during Herbst-multibracket appliance (Herbst-MBA) treatment and the development of labial gingival recessions (LGR). METHODS: All class II patients (Department of Orthodontics, University of Giessen, Giessen, Germany) who had undergone Herbst-MBA treatment until 2015 with study models and lateral cephalograms available from before (T0) and after treatment plus ≥24 months of retention (T3) were included (n = 259). Lateral cephalograms were evaluated regarding LI position changes: iiL/ML (angle between LI long axis and mandibular plane [MP]), ii-MLPg (distance between LI incisal edge and a line perpendicular to MP through pogonion), apex-MLPg (distance between LI apex and a line perpendicular to MP through pogonion), ii-MLii (distance between LI incisal edge and MP on a line perpendicular to MP through incisal edge). Using study models the distance between the cementoenamel junction and the deepest point of the gingival margin was defined as LGR. RESULTS: The following cephalometric mean changes were recorded (T0-T3): iiL/ML +5.9 ± 5.76° (p = 0.929), ii-MLPg -0.2 ± 0.25 mm (p = 0.430), apex-MLPg +0.1 ± 0.32 mm (p = 0.363), ii-MLii +0.1 ± 0.36 mm (p = 0.206). The mean increase of LGR magnitude measured on the study models was 0.1 ± 0.35 mm. However, no association with the cephalometric LI position changes was found (|R| ≤ 0.2). CONCLUSION: There is no association between the amount of LI position changes and the development of LGR during Herbst-MBA treatment plus retention. Nevertheless, individual predisposition or excessive treatment changes and extraordinary treatment approaches, respectively, might still lead to development of LGR.

Cloning and characterization of an Mn-containing superoxide dismutase (SodA) of Bordetella pertussis.

The Fur titration assay (FURTA) recently developed by I. Stojiljkovic and coworkers (J. Mol. Biol. 236:531-545, 1994) was applied to clone iron-regulated genes of Bordetella pertussis. After sequence analysis, one of the clones obtained by this selection procedure was shown to contain an open reading frame with significant sequence similarities to Mn-containing superoxide dismutases (SodA). The open reading frame was preceded by a Fur consensus binding site, which according to primer extension analysis overlaps the -10 region of the sodA promoter. Southern blot analysis also revealed the presence of sodA homologous sequences in Bordetella bronchiseptica. On the transcriptional level, sodA expression is strictly iron regulated in both organisms and also in the heterologous host Escherichia coli harboring a plasmid with the sodA gene. Accordingly, SodA-mediated superoxide dismutase activity in Bordetella lysates was detected only after cultivation of the bacteria in iron-restricted media. A B. bronchiseptica fur mutant constitutively expressed SodA, thereby confirming the functional similarity of the iron regulatory systems in the two genera. Apart from iron regulation, sodA expression was affected by changes in DNA topology induced by coumermycin A but not by the global virulence regulatory Bvg system. B. pertussis and B. bronchiseptica sodA deletion mutants did not show significant changes in their growth properties. In contrast, mutation of the previously described Fe-containing SodB enzyme resulted in clones strongly impaired in viability. No direct involvement of SodA in bacterial virulence could be revealed because deletion of the sodA gene affected survival of Bordetella species neither in cultured macrophages nor in a mouse respiratory infection model.