Skeletal maxillary constriction is a popular orthodontic malocclusion that can be seen at any age. The maxillary expansion is the most important treatment choice of this skeletal problem in the upper jaw. There are many types of maxillary expansion regarding the force amount and the number of expansion times: slow maxillary expansion (SME) rapid maxillary expansion (RME), and semi-rapid maxillary expansion (SRME).~Practitioners are conscious that complaints submitted by children and adolescents during the active phase of expansion, such as pain, discomfort and oral ulcers are common symptoms. This trial of two parallel groups will compare the pain, discomfort and functional impairments accompanying the rapid and slow maxillary expansion in early adolescent patients.~RME group: A bonded modified Hyrax palatal expander will be applied. SME group: A removable palatal expansion appliance with a midline screw will be applied.~To assess the pain, discomfort and functional impairments, patients will be asked to fill out questionnaires of six questions: 1) What is the degree of pain/discomfort you have experienced?; 2) Do you have difficulty in mastication?; 3) Do you have difficulty in swallowing?; 4) Do you have a sense of tension or pressure in soft tissue?; 5) Do you have swelling in soft tissue?; and 6) How easy is the treatment procedure?.
This study will assess and compare the levels of pain, discomfort, and functional impairments between rapid and slow maxillary expansion in treating skeletal maxillary constriction in the early adolescence period (i.e. between 12 and 16 years).~The study sample will consist of 32 patients who suffer from a skeletal posterior crossbite. The sample will be allocated randomly into two groups: RME group and SME group.~The patients will be asked to fill out the attached questionnaires at three assessment times.