This randomized clinical trial will compare two types of expansion appliances used with surgically assisted rapid maxillary expansion (SARME) in adults with a narrow upper jaw. SARME is a surgical and orthodontic treatment used to widen the upper jaw when orthodontic expansion alone is not sufficient. The study will investigate whether a tooth-borne appliance, which is supported by the teeth, and a hybrid appliance, which is supported by both the teeth and two small screws placed in the palate, produce different treatment outcomes.
A total of 32 adults scheduled for SARME at Aalborg University Hospital in Denmark and Lund University Hospital in Sweden will be randomly assigned to treatment with either the tooth-borne appliance or the hybrid appliance. Participants will be examined before surgery, after completion of the expansion phase, and six months after completion of expansion. Assessments will include cone-beam computed tomography (CBCT), digital dental scans, facial imaging, periodontal examinations, recording of complications, and questionnaires about pain, recovery, oral health-related quality of life, general quality of life, and treatment experience.
The main outcome of the study is skeletal relapse, meaning how much of the widening of the upper jaw is lost between the end of expansion and the six-month follow-up. Other outcomes include the amount of skeletal and dental expansion, tooth tipping, changes in the supporting bone and gums around the teeth, facial soft-tissue changes, complications, recovery, and patient-reported quality of life. The study aims to determine whether one appliance provides better stability or fewer unwanted effects and thereby improve future treatment recommendations for adults undergoing SARME.
Moderate or severe maxillary transverse deficiency (MTD).
Healthy adults aged 18 years or older.
Completed craniofacial growth.
Presence of the maxillary first premolars and first molars.
Previous surgical treatment of facial trauma or dentofacial deformities.
Systemic disease, medication, genetic disease, or developmental condition expected to affect craniofacial morphology, bone turnover, or healing.
Pregnancy.
Inability to understand the study information or provide written informed consent.
Parallel
Tooth-Borne Maxillary Expansion Appliance
DeviceA CAD/CAM-fabricated tooth-borne maxillary expansion appliance used during surgically assisted rapid maxillary expansion (SARME). The appliance consists of four printed metal bands cemented to the maxillary first premolars and first molars and connected to a palatal expansion mechanism. Anchorage is provided exclusively by the teeth, with no palatal mini-implants. The appliance is cemented before surgery. Following a postoperative latency period of 5-7 days, the appliance is activated at approximately 0.5 mm per day until the planned expansion or clinical overcorrection is achieved. The appliance is subsequently maintained passively during the six-month consolidation period.
Hybrid Tooth-Bone-Borne Maxillary Expansion Appliance
DeviceA CAD/CAM-fabricated hybrid tooth-bone-borne maxillary expansion appliance used during surgically assisted rapid maxillary expansion (SARME). The appliance consists of four printed metal bands on the maxillary first premolars and first molars connected to a palatal expansion mechanism. In addition to dental anchorage, skeletal anchorage is provided by two palatal mini-implants (BENEfit® DIRECT screws, 2.0 mm diameter and 9 mm length) inserted immediately before surgery and connected to the expander. Following a postoperative latency period of 5-7 days, the appliance is activated at approximately 0.5 mm per day until the planned expansion or clinical overcorrection is achieved, followed by a six-month passive consolidation period.
Transverse Skeletal Relapse in External Maxillary Width
Transverse skeletal relapse will be assessed as the reduction in external maxillary width (EMW) from the end of the distraction phase (T1) to the six-month follow-up (T2). EMW will be measured in millimetres on CBCT images at the maxillary first premolar and first molar levels, using the hard palate as the skeletal reference. Skeletal relapse will be calculated as the T1 EMW minus the T2 EMW; a larger positive value indicates greater skeletal relapse.
Change in External Maxillary Width During Expansion
Change in external maxillary width (EMW) from baseline (T0) to the end of the distraction phase (T1). EMW will be measured in millimetres on CBCT images at the maxillary first premolar and first molar levels, using the hard palate as the skeletal reference.
Change in Maxillary Dental Arch Width
Maxillary transverse dental width will be measured in millimetres using digital dental models and/or CBCT-derived dental landmarks. Measurements include intercanine width (cusp tip to cusp tip), interpremolar width at the first premolars (buccal cusp tip to buccal cusp tip), and intermolar width at the first molars (mesiobuccal cusp tip to mesiobuccal cusp tip). Changes between T0, T1, and T2 will be calculated to assess expansion and subsequent dental relapse.
Change in Maxillary Tooth Inclination
Change in inclination of the maxillary canines, first premolars, and first molars will be measured in degrees on standardized coronal CBCT images. Tooth inclination will be determined using predefined crown and root landmarks, and angular changes between study timepoints will be calculated.
Plaque Index
Periodontal plaque accumulation will be assessed using the Plaque Index according to the standardized periodontal examination protocol. Measurements will be obtained at predefined sites around selected maxillary teeth, with corresponding mandibular teeth assessed as controls.
Change in Midpalatal Sutural Expansion Width
Midpalatal sutural expansion width will be measured in millimetres on axial CBCT images at the incisor, canine, first premolar, and first molar levels. Changes between T0, T1, and T2 will be calculated to characterize sutural opening during the distraction phase and subsequent change during the consolidation period.
Change in Maxillary Midline Diastema Width
The width of the midline diastema between the maxillary central incisors will be measured in millimetres on digital dental models obtained from standardized intraoral scans. Measurements at T0, T1, and T2 will be compared to assess development of the diastema during expansion and subsequent change during consolidation.
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Aalborg University Hospital
Lead sponsor
Lund University Hospital
Collaborator
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