The chin cup has been used to treat skeletal mandibular prognathism in growing patients for 200 years. The pull on the orthopedic-force chin cup is oriented along a line from the mandibular symphysis to the mandibular condyle. Various levels of success have been reported with this restraining device. The vertical chin cup produces strong vertical compression stress on the maxillary molar regions when the direction of traction is 20 degrees more vertical than the chin-condyle line. This treatment strategy may prevent relapse due to counter-clockwise rotation of the mandible. In this report, we describe a new strategy for using chin-cup therapy involving thin-plate spline (TPS) analysis of lateral cephalometric roentgenograms to visualize transformation of the mandible. The actual sites of mandibular skeletal change are not detectable with conventional cephalometric analysis. A case of mandibular prognathism treated with a chin cup and a case of dental Class III malocclusion without orthodontic treatment are described. The case analysis illustrates that specific patterns of mandibular transformation are associated with Class III malocclusion with or without orthopedic therapy, and that visualization of these deformations is feasible using TPS graphical analysis.
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J Chin Med Assoc
December 2024
Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan, ROC.
Background: Operative delivery is a technique used during vaginal or cesarean birth to facilitate the patient's labor course through the assistance of a vacuum extractor. This method is increasingly used compared with forceps. This study aimed to investigate the forced effects of vacuum extractors comprising vacuum cups with different thicknesses on the fetal head and the vacuum extractor during vacuum-assisted delivery and to determine the optimal thickness for reducing the failure rate and minimizing neonatal and maternal morbidity.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
University of Califonia, Los Angeles, Department of Physics & Astronomy, Los Angeles, Califonia 90095-1547, USA.
Cureus
October 2024
Orthodontics and Dentofacial Orthopaedics, Manav Rachna Dental College, Faridabad, IND.
Class III malocclusion presents many challenges due to its varying elements of imbalance in skeletal, dental, and soft tissues. This necessitates a comprehensive treatment plan, including growth modification during the pre-pubertal growth phase, and long-term retention to reduce the chances of orthognathic surgery later. The components of Class III malocclusion include maxillary retrognathism, mandibular prognathism, or, in some cases, a combination of both.
View Article and Find Full Text PDFCochrane Database Syst Rev
April 2024
Cochrane Oral Health, Division of Dentistry, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
Background: Prominent lower front teeth (Class III malocclusion) may be due to jaw or tooth position or both. The upper jaw (maxilla) can be too far back or the lower jaw (mandible) too far forward; the upper front teeth (incisors) may be tipped back or the lower front teeth tipped forwards. Orthodontic treatment uses different types of braces (appliances) fitted inside or outside the mouth (or both) and fixed to the teeth.
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