Crowding
Crowding of the teeth is treated with orthodontics, often with tooth extraction, clear aligners, or dental braces, followed by growth modification in children or jaw surgery (orthognathic surgery) in adults. Surgery may be required on rare occasions. This may include surgical reshaping to lengthen or shorten the jaw (orthognathic surgery). Wires, plates, or screws may be used to secure the jaw bone, in a manner similar to the surgical stabilization of jaw fractures. Very few people have "perfect" alignment of their teeth. However, most problems are very minor and do not require treatment. Class I
While treatment is not crucial in class I malocclusions, in severe cases of crowding can be an indication for intervention. Studies indicate that tooth extraction can have benefits to correcting malocclusion in individuals. Further research is needed as reoccurring crowding has been examined in other clinical trials. Class II
A few treatment options for class II malocclusions include:

Functional appliance which maintains the mandible in a postured position to influence both the orofacial musculature and dentoalveolar development prior to fixed appliance therapy. This is ideally done through pubertal growth in pre-adolescent children and the fixed appliance during permanent dentition . Different types of removable appliances include Activator, Bionatar, Medium opening activator, Herbst, Frankel and twin block appliance with the twin block being the most widely used one.
However, some other regulatory authorities did not agree with the FDA decision, with Japans Pharmaceuticals and Medical Devices Agency stating in 2011 that the "risk-benefit balance of gemtuzumab ozogamicin has not changed from its state at the time of approval".In 2017, Pfizer reapplied for US and EU approval, based on a meta-analysis of prior trials and results of the ALFA-0701 clinical trial, an open-label Phase III trial in 280 older people with AML. In September 2017, gemtuzumab ozogamicin was approved again for use in the United States and in the European Union. See also
Inotuzumab ozogamicin

References
Further reading
AusPAR: Gemtuzumab ozogamicin. Therapeutic Goods Administration (TGA) (Report). October 2020. External links
"Gemtuzumab ozogamicin". Drug Information Portal. U.S. National Library of Medicine. Clinical trial number NCT00372593 for "Combination Chemotherapy With or Without Gemtuzumab in Treating Young Patients With Newly Diagnosed Acute Myeloid Leukemia" at ClinicalTrials.gov