Post-Treatment Status of Impacted Maxillary Central Incisors following Surgical-Orthodontic Treatment: A Systematic Review

Background and Objectives: The aim of this systematic review was to summarize currently available data of published articles that have investigated the post-treatment status of impacted maxillary central incisors (ICI) treated by the surgical-orthodontic approach. Materials and Methods: MEDLINE, Scopus, Cochrane Oral Health Group’s Trials Register, and ScienceDirect electronic databases were systematically searched with no publication date restrictions up to January 2021. Data assessing the status of ICI after combined surgical-orthodontic treatment and forced eruption duration were extracted, and the quality of the studies was evaluated. Results: In total, 7074 studies were identified, of which 42 articles were assessed for eligibility through full-text evaluation. Seven included studies (five retrospective studies, one randomized clinical trial, and one prospective clinical trial) met the inclusion criteria, representing 211 patients with unilaterally impacted maxillary incisors. The risk of bias ranged from moderate to high. The results show that the root length of immature ICIs increased significantly but remained shorter than that of homonym teeth at post-treatment. Periodontal parameters of treated ICIs were in a clinically acceptable range. Measurements of the alveolar bone showed a reduction of bone thickness and support. The average forced eruption duration ranged from 8.0 ± 4.5 to 14.41 ± 4.03 months. Conclusions: Based on existing evidence, it is reasonable to conclude that the surgical-orthodontic treatment affected the post-treatment status of ICI; however, the current literature is insufficient to draw concrete conclusions. Further well-conducted multi-center randomized studies with a large sample are needed to confirm this statement.

Lava flow growth inferred from morphometric parameters: a case study of Citlaltépetl volcano, Mexico

Recent (Quaternary) lava fields, such as those of Citlaltépetl (Pico de Orizaba) volcano in Mexico, are excellent places to obtain precise measurements of flow-field dimensions that can be used to estimate volume, eruption duration and effusion rates. The relationship between these parameters and the influence of some other interrelated features such as lava composition, superficial structures and lava type are important tools that can help to infer conditions when the lavas were active and thus improve understanding of how flow fields grow. The Holocene lavas of Citlaltépetl volcano are homogeneous in composition (dacites) and are generally blocky with well-developed levees. The eruption duration obtained for the Citlaltépetl lavas by a method proposed by C. Kilburn and R. Lopes presents a good correlation with the different lava types morphologically classified here. Results from that method compare favourably with the inferred effusion rates estimated by an empirical cooling method (Graetz). The lavas show different behaviour, mainly controlled by fluctuations in the effusion rate that promote changes from single- to multiple-flow style. The maximum distance achieved by a flow is directly proportional to the effusion rate in Citlaltépetl lavas, but it is always lower for multiple flows, independent of the volume of erupted lava. Observations of Citlaltépetl lavas can be used to understand how lava flow growth occurs on other volcanoes.

Superhumps in the SU UMa Star AK CNC

We have observed AK Cnc during the 1995 March superoutburst, by means of differential V – U photometry. The observations were obtained at Las Campanas (Chile), Ouda Station (Kyoto, Japan) and in England. Superhumps with amplitude 0.2 mag appeared at least 4d after maximum. They evolved from a single peak structure, developing a secondary peak during decline, until they reached a double-wave modulation with 0.05 mag amplitude, after 8 d. After removing linear trends in our data, the following ephemeris was found:This superhump period was confirmed, independently, with our homogeneous set of 462 V magnitudes, obtained at LCO, then adding 63 U data points and finally considering all the dataset, consisting of 789 V + U magnitudes. The superhump period is slightly larger than that reported by Kato (1995) during the 1992 January superoutburst (0.06735(5)d). Our results imply an orbital period Porb = 0.065(2) d, using the relationship given by Howell & Hurst (1994). The eruption duration was ≳ 10 d, and its amplitude > 6 mag. An abrupt and short luminosity decrease occured ≈ 12 d after maximum. Eleven outbursts have been observed since 1992 January, being the minimum reported lag between successive eruptions: 40 d. More details will be given in a future publication.