镁（Mg）补充剂与交替上颌扩弓和缩弓（Alt-RAMEC）对横向颌骨发育不足（TMD）患者的影响 (Mg + Alt-RAMEC)

有源比较器：Alt-RAMEC/MARPE Without Magnesium Supplementation

Participants receive alternate rapid maxillary expansion and constriction (Alt-RAMEC) using a micro-implant-assisted rapid palatal expansion (MARPE) appliance without magnesium supplementation. The appliance consists of a 10-mm Maxillary Skeletal Expander II supported by four palatal miniscrews. Activation consists of two expansion quarter-turns daily in weeks 1 and 3, one reverse quarter-turn daily in weeks 2 and 4, and one to two expansion quarter-turns daily in week 5 until the clinical expansion endpoint is reached. Weeks 6-12 comprise passive retention and follow-up. The appliance and activation schedule are identical to those used in the experimental arm; this arm serves as the control for evaluating the additional effects of magnesium supplementation.

设备：Micro-implant-Assisted Rapid Palatal Expansion (MARPE) With the Alt-RAMEC Protocol

Participants receive alternate rapid maxillary expansion and constriction (Alt-RAMEC) using a micro-implant-assisted rapid palatal expansion (MARPE) appliance. The appliance consists of a 10-mm Maxillary Skeletal Expander II supported by four palatal miniscrews, each 1.8 mm in diameter and 11 mm in length. Activation consists of two expansion quarter-turns daily in weeks 1 and 3, one reverse quarter-turn daily in weeks 2 and 4, and one to two expansion quarter-turns daily in week 5 until the clinical expansion endpoint is reached. Weeks 6-12 comprise passive retention and follow-up. The same appliance and activation protocol are used in both study arms.

实验性的：Alt-RAMEC/MARPE With Magnesium Citrate Supplementation

Participants receive alternate rapid maxillary expansion and constriction (Alt-RAMEC) using a micro-implant-assisted rapid palatal expansion (MARPE) appliance, together with oral magnesium citrate providing 400 mg of elemental magnesium daily, administered as three capsules with food for 12 weeks from the first day of activation. The appliance consists of a 10-mm Maxillary Skeletal Expander II supported by four palatal miniscrews. Activation consists of two expansion quarter-turns daily in weeks 1 and 3, one reverse quarter-turn daily in weeks 2 and 4, and one to two expansion quarter-turns daily in week 5 until the clinical expansion endpoint is reached. Weeks 6-12 comprise passive retention and follow-up, while magnesium supplementation continues.

设备：Micro-implant-Assisted Rapid Palatal Expansion (MARPE) With the Alt-RAMEC Protocol

Participants receive alternate rapid maxillary expansion and constriction (Alt-RAMEC) using a micro-implant-assisted rapid palatal expansion (MARPE) appliance. The appliance consists of a 10-mm Maxillary Skeletal Expander II supported by four palatal miniscrews, each 1.8 mm in diameter and 11 mm in length. Activation consists of two expansion quarter-turns daily in weeks 1 and 3, one reverse quarter-turn daily in weeks 2 and 4, and one to two expansion quarter-turns daily in week 5 until the clinical expansion endpoint is reached. Weeks 6-12 comprise passive retention and follow-up. The same appliance and activation protocol are used in both study arms.

膳食补充剂：Oral Magnesium Citrate Supplementation

Participants in the experimental arm receive oral magnesium citrate providing a total of 400 mg of elemental magnesium per day, administered as three capsules once daily with food for 12 weeks from the first day of MARPE activation. Supplementation continues during both the active Alt-RAMEC treatment period and the subsequent passive retention period. Participants in the active comparator arm receive no magnesium supplementation or placebo.

其他名称：

• 镁

Change from Baseline in Anterior Midpalatal Suture Separation at 12 Weeks

Change in anterior midpalatal suture separation measured in millimetres (mm) using cone-beam computed tomography (CBCT) at the anterior nasal spine (ANS) level. Measurements are assessed before the first activation of micro-implant-assisted rapid palatal expansion (MARPE; T0) and 12 weeks after activation begins (T1). The change is calculated as the T1 measurement minus the T0 measurement. Positive values indicate increased separation at the anterior part of the midpalatal suture. Changes are compared between participants receiving the alternate maxillary expansion and constriction (Alt-RAMEC) protocol with magnesium supplementation and those receiving the same protocol without magnesium supplementation.

Change from Baseline in Posterior Midpalatal Suture Separation at 12 Weeks

Change in posterior midpalatal suture separation measured in millimetres (mm) using cone-beam computed tomography (CBCT) at the posterior nasal spine (PNS) level. Measurements are assessed before the first activation of micro-implant-assisted rapid palatal expansion (MARPE; T0) and 12 weeks after activation begins (T1). The change is calculated as the T1 measurement minus the T0 measurement. Positive values indicate increased separation at the posterior part of the midpalatal suture. Changes are compared between participants receiving the alternate maxillary expansion and constriction (Alt-RAMEC) protocol with magnesium supplementation and those receiving the same protocol without magnesium supplementation.

Change from Baseline in Interzygomatic Width at 12 Weeks

Change in interzygomatic width measured in millimetres using cone-beam computed tomography (CBCT). Interzygomatic width is the distance between the anterior outer points of the right and left zygomaticomaxillary sutures on a standardized axial section. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased transverse width.

Change from Baseline in Maxillary Jugale-to-Jugale Width at 12 Weeks

Change in the transverse distance between the right and left jugale landmarks, measured in millimetres using cone-beam computed tomography (CBCT). Each jugale landmark is identified at the intersection of the outlines of the maxillary tuberosity and zygomatic process on a standardized coronal section. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased maxillary width.

Relative Palatal Expansion Ratio at 12 Weeks

The proportion of mechanical expansion expressed as skeletal midpalatal suture opening. The mean change in suture separation at the anterior nasal spine (ANS) and posterior nasal spine (PNS), measured using cone-beam computed tomography, is divided by the recorded mechanical expansion of the MARPE screw in millimetres. The calculation is [(ANS change + PNS change)/2]/mechanical expansion. The outcome is reported as a unitless ratio (mm/mm). Higher values indicate greater skeletal opening per unit of mechanical expansion.

Change from Baseline in Maxillary Alveolar Width at 12 Weeks

Change in maxillary alveolar width measured in millimetres using cone-beam computed tomography (CBCT). Alveolar width is measured between the right and left buccal alveolar bone surfaces on a standardized coronal section along the line connecting the maxillary first-molar furcations. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased alveolar width.

Change from Baseline in Maxillary First-Molar Interfurcation Width at 12 Weeks

Change in the distance between the furcations of the right and left maxillary first molars, measured in millimetres using cone-beam computed tomography (CBCT). Measurements are obtained on standardized coronal sections showing both furcations. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased interfurcation width.

Change from Baseline in Right Maxillary First-Molar Inclination at 12 Weeks

Change in the inclination of the right maxillary first molar, measured in degrees using cone-beam computed tomography (CBCT). Inclination is the angle between the palatal reference line and the palatal root axis, defined by the root apex and canal orifice, on a standardized coronal section. Change is calculated as the angle at 12 weeks (T1) minus the baseline angle (T0).

Change from Baseline in Left Maxillary First-Molar Inclination at 12 Weeks

Change in the inclination of the left maxillary first molar, measured in degrees using cone-beam computed tomography (CBCT). Inclination is the angle between the palatal reference line and the palatal root axis, defined by the root apex and canal orifice, on a standardized coronal section. Change is calculated as the angle at 12 weeks (T1) minus the baseline angle (T0)

Change from Baseline in Right Maxillary Alveolar Inclination at 12 Weeks

Change in right maxillary alveolar inclination, measured in degrees using cone-beam computed tomography (CBCT). Alveolar inclination is the angle between the right palatal alveolar bone and the palatal plane on a standardized coronal section. Change is calculated as the angle at 12 weeks (T1) minus the baseline angle (T0).

Change from Baseline in Buccal Bone Thickness at the Right Maxillary First Molar at 12 Weeks

Change in buccal bone thickness at the right maxillary first molar, measured in millimetres using cone-beam computed tomography (CBCT). Thickness is measured from the root surface to the outer buccal bone surface at the first-molar trifurcation level on a standardized coronal section. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Negative values indicate reduced buccal bone thickness.

Change from Baseline in Buccal Bone Thickness at the Left Maxillary First Molar at 12 Weeks

Change in buccal bone thickness at the left maxillary first molar, measured in millimetres using cone-beam computed tomography (CBCT). Thickness is measured from the root surface to the outer buccal bone surface at the first-molar trifurcation level on a standardized coronal section. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Negative values indicate reduced buccal bone thickness.

Change from Baseline in Mean Midpalatal CBCT Gray Value at 12 Weeks

Change in the mean cone-beam computed tomography (CBCT) gray value within a standardized 4-mm-diameter region of interest centered on the midpalatal suture at the level of the line connecting the palatal roots of the maxillary first molars. Corresponding regions are assessed at baseline and 12 weeks using standardized image orientation. Change is calculated as the mean gray value at T1 minus the mean gray value at T0 and is reported in CBCT gray-value units. This measurement is a relative radiographic density proxy, not calibrated bone mineral density.

Change from Baseline in Maxillary Intercanine Width at 12 Weeks

Change in maxillary intercanine width measured in millimetres on digital dental models obtained by intraoral scanning. Intercanine width is the distance between the cusp tips of the right and left maxillary canines. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased intercanine width.

Change from Baseline in Maxillary Intermolar Width at 12 Weeks

Change in maxillary intermolar width measured in millimetres on digital dental models obtained by intraoral scanning. Intermolar width is the distance between the mesiobuccal cusp tips of the right and left maxillary first molars. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased intermolar width.

Change from Baseline in Maxillary Anterior Arch Length at 12 Weeks

Change in maxillary anterior arch length measured in millimetres on digital dental models. Anterior arch length is the perpendicular distance from the line joining the right and left maxillary canine cusp tips to the most prominent maxillary central-incisor point. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased anterior arch length.

Change from Baseline in Maxillary Molar-Level Arch Length at 12 Weeks

Change in maxillary arch length at the first-molar level, measured in millimetres on digital dental models. The measurement is the perpendicular distance from the line joining the mesiobuccal cusp tips of the right and left maxillary first molars to the most prominent maxillary central-incisor point. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased arch length.

Change from Baseline in Palatal Width at the Maxillary Canine Level at 12 Weeks

Change in palatal width at the maxillary canine level, measured in millimetres on digital dental models. Width is measured between the right and left palatal gingival-margin midpoints at the maxillary canines. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased palatal width at the canine level.

Change from Baseline in Palatal Width at the Maxillary First-Molar Level at 12 Weeks

Change in palatal width at the maxillary first-molar level, measured in millimetres on digital dental models. Width is measured between the right and left palatal gingival-margin points corresponding to the centers of the mesiopalatal cusps of the maxillary first molars. Change is calculated as the measurement at 12 weeks (T1) minus the baseline measurement (T0). Positive values indicate increased palatal width at the first-molar level.

Change from Baseline in Normalized Right Masseter Activity During Chewing at 12 Weeks

Change in normalized surface electromyographic activity of the right masseter muscle during a standardized chewing task. At each assessment, the root mean square (RMS) amplitude during chewing is divided by the same muscle's RMS amplitude during maximum voluntary clenching in intercuspation, recorded during the same session, and multiplied by 100. Change is calculated as the normalized value at 12 weeks (T1) minus the baseline value (T0) and is expressed in percentage points of maximum voluntary clench-normalized activity.

Change from Baseline in Normalized Left Masseter Activity During Chewing at 12 Weeks

Change in normalized surface electromyographic activity of the left masseter muscle during a standardized chewing task. At each assessment, the root mean square (RMS) amplitude during chewing is divided by the same muscle's RMS amplitude during maximum voluntary clenching in intercuspation, recorded during the same session, and multiplied by 100. Change is calculated as the normalized value at 12 weeks (T1) minus the baseline value (T0) and is expressed in percentage points of maximum voluntary clench-normalized activity.

Change from Baseline in Normalized Right Anterior Temporalis Activity During Chewing at 12 Weeks

Change in normalized surface electromyographic activity of the right anterior temporalis muscle during a standardized chewing task. At each assessment, the root mean square (RMS) amplitude during chewing is divided by the same muscle's RMS amplitude during maximum voluntary clenching in intercuspation, recorded during the same session, and multiplied by 100. Change is calculated as the normalized value at 12 weeks (T1) minus the baseline value (T0) and is expressed in percentage points of maximum voluntary clench-normalized activity.

Change from Baseline in Normalized Left Anterior Temporalis Activity During Chewing at 12 Weeks

Change in normalized surface electromyographic activity of the left anterior temporalis muscle during a standardized chewing task. At each assessment, the root mean square (RMS) amplitude during chewing is divided by the same muscle's RMS amplitude during maximum voluntary clenching in intercuspation, recorded during the same session, and multiplied by 100. Change is calculated as the normalized value at 12 weeks (T1) minus the baseline value (T0) and is expressed in percentage points of maximum voluntary clench-normalized activity.

Overall Activation-Period Pain Intensity Assessed at 12 Weeks

Participant-reported overall pain intensity experienced during the active alternate maxillary expansion and constriction (Alt-RAMEC) treatment period, assessed at the 12-week visit using a 0-10 pain intensity scale. A score of 0 indicates no pain or discomfort, and a score of 10 indicates the worst imaginable pain or discomfort. Higher scores indicate greater pain intensity. The outcome is reported in scale points and represents recalled overall activation-period pain, not a change from baseline.

Number of Participants by Most Frequent Pain Location During Active Treatment

The most frequent location of pain experienced during the active alternate maxillary expansion and constriction (Alt-RAMEC) treatment period, reported using a structured questionnaire at the 12-week visit. Participants select one location: anterior palate, posterior palate, molar region, or zygomatic region. The outcome is reported as the number of participants selecting each location.