Mandibular Midline Distraction (MMD) and Surgically Assisted Rapid Maxillary Expansion (SARME) are techniques to widen the mandible and maxilla, respectively. Little is known on the patient experience and satisfaction of these techniques. Research on MMD is mostly performed using conventional research methods, including dental cast models and posterior-anterior cephalograms. Research on bimaxillary expansion (BiMEx), combination of MMD and SARME, is reported sparsely. This study aims to assess patient experience, satisfaction, and 3-dimensional (3D) soft tissue effects following MMD and/or SARME.
Materials and methods:
Patients who underwent MMD and/or SARME at the Department of Oral and Maxillofacial Surgery, Erasmus MC, University Medical Center Rotterdam, the Netherlands, were included in this retrospective study. This study was divided in 2 sub-studies:
1) Between 2010-2012, patients were asked to fulfill a visual analogue scale questionnaire (VAS) on how they perceive the treatment (Table). A score was given on a 10cm VAS scale. The longitudinal data were analyzed using linear mixed models whereby the preoperative (T1) is regarded as baseline. A P-value < .05 was regarded as significant.
2) Between 2008-2013, stereophotogrammetry records were taken at time points: T1, direct post-distraction (T2), and 1-year pos-operative (T3). Stereophotogrammetry analyses were performed with automatic 3D facial landmarking algorithm using 2D Gabor wavelets (Image). Two-sided paired-samples t-test was used to assess differences between T1 and T3. A Bonferroni correction was applied to adjust P-values for the MMD outcome (adjusted significance level P < .0026) and for the SARME outcome (adjusted significance level P < .0025), separately.
In VAS-group, 17 patients were included, of which 16 patients underwent both MMD and SARME; 1 patient was treated with MMD only. Noticeably, is the increase in VAS-score for patients after stop of distraction regarding dentition and appearance of mouth, whereby the increase regarding dentition was significant for 3 months post-distraction and 1-year postoperative (P < .05). Satisfaction of patients with their dentition was statistically higher than patients expected. Hindrance score for tooth-borne distractor used in maxilla was lower than the bone-borne distractor used in mandible. Regarding the impact of procedures, the lowest scores were given at stop of distraction and 3 months post-distraction and were significant (P < .05). Overall satisfaction remained stable at a score of around 8 and did not differ statistically significant from preoperative expectations (P > .05). Pain score for the mandible was postoperatively significantly higher than expected (P < .05). In addition, the given scores for the mandible were higher than for maxilla.
Twenty patients who had undergone SARME were included, 12 of whom had undergone BiMEx. Age at time of surgery ranged from 16 to 47 years. There was a significant mean downward displacement of 3.12mm of the soft tissue Pogonion (P < .0026). Furthermore, there was a significant mean increase of 2.20mm in inter-alar width (P < .0025) and a non-significant mean increase of 1.77mm in inter-alar curvature point width (P > .0025). These outcomes indicate a transverse widening of inter-alar width and a tendency toward an increase in inter-alar curvature point width.
In general, patients who underwent SARME and MMD are very satisfied with the treatment. Automatic stereophotogrammetry landmarking analysis of soft tissue effects showed a downward displacement of the soft tissue Pogonion following BiMEx and a transverse widening of the inter-alar width and a tendency toward an increase in the inter-alar curvature point width after SARME. Clinicians should communicate these possible soft tissue effects to the patient carefully during the planning of the orthognathic surgery.
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2. de Gijt JP, Vervoorn K, Wolvius EB, Van der Wal KG, Koudstaal MJ. Mandibular midline distraction: a systematic review. J Craniomaxillofac Surg 2012;40:248–60.