2.5 Statistical analysis
Statistical analyses were performed using Excel 14.3.9 and SPSS. Continuous variables are expressed as mean ± standard error of the mean and categorical variables as proportions (%). Means of continuous variables were compared by the X test and proportions by the Y test. All tests were 2-tailed and a P <.05 was accepted as statistically significant.
There were no significant differences in birth weight (kg), gestational age (week), ratio of males to females, and incidence of palatal cleft between the control group and the 3D print group (all P >.05) (Table 1). Of preoperative factors examined, only age at operation differed, with control patients significantly older (P <.05), indicating that average patient condition for surgery was actually superior in the control group.
During surgery, the traction process went well for both groups, the bone formed well at the surgical site, and no infections or other complications occurred in the perioperative period (6 months). Surgery efficacy and safety were rated according to 5 indices, surgery time (minutes), bleeding amount (mL), time of post-surgical separation of the artificial airway (days), time of hospitalization (days), and time of post-surgical oral feeding (days) (Table 2). Surgery time was significantly shorter for the 3D print group than the control group (P = .023), while bleeding amount (mL), time of post-surgery separation of artificial airway (days), time of hospitalization (days), and time of post-surgery oral feeding (days) did not differ (P >.05). Time to post-surgical separation of the artificial airway and time of hospitalization showed a trend towards a shorter time period in the experimental group (P = .056).
Postoperative complications were assessed by 7 parameters, local skin infection, nerve injury, tractor shedding, dental injury, accidental fracture, facial asymmetric deformity, and scarring (Table 3), none of which differed significantly between groups. However, age at operation was significantly younger in the 3D print group and surgeries were more complex, requiring a higher degree of surgical accuracy.
Mandibular distraction osteogenesis was first described by McCarthy in 1989 and has since become the most widely used and effective treatment for airway obstruction caused by PRS. The aim is to lengthen the mandible, which in turn will move the tongue root forward, thereby relieving respiratory tract obstruction induced by glossocoma. Successful application has been demonstrated to improve respiratory function, sleep, and swallowing. It is generally performed when body position change and other conservative treatments cannot improve respiration or help wean patients from artificial respiration. However, mandibular distraction osteogenesis is a high-risk treatment when used in infancy as multiple postoperative complications may occur, such as permanent tooth injury, tractor fall off, fracture accidents, mandibular alveolar nerve injury, bone nonunion, infection, and scars Moreover, the severity of these congenital malformations varies widely among patients, so pre-operational individualized planning is essential to improve surgery efficacy and reduce postoperative complications. Developments in computerized structural modeling have provided surgeons with a platform to facilitate individual surgical design, but application remains difficult during actual surgery. In infants, the small size of the mandible necessitates highly precise operative design and procedures, and any minor error can lead to serious complications. The use of surgical guides helps greatly in surgery design. However, traditional surgical guides fabricated manually often have poor accuracy. The development of 3D printing technology may help solve this problem. By 3D printing, the surgical guide is a reverse engineered product of the surgery design. In this study, 2 different manufacturing methods of surgical guides were compared. We found that 3D printing guide plate has obvious advantages, but the sample size of this study was small, and further enlargement of sample size is needed for comparison in the future.
Frequently used 3D printing techniques include fused deposition modeling (FDM), stereo lithography apparatus (SLA), selected laser sintering (SLS), and 3D spray (3DP). A wide range of materials can be used for 3D printing, including natural and synthesized polymers, metals, and ceramics. Several processing methods can also be chosen for surgical guide synthesis, but the mechanical and biological properties will vary. Choosing the optimal processing method and material composition involves many considerations. In this study, a bio-resin was used for 3D printing of surgical guides, and results demonstrated significant advantages compared to surgical guides made by traditional methods. The limitation of the investigation is the small sample size. In future studies, the sample size needs to be further expanded. So that whether this 3D printing method using bio-resin is sufficient for other clinical requirements requires additional evidence. Requirements of physical strength and dimensional accuracy vary according to operation site and surgical method. Further, the additional cost of fabrication must be balanced against clinical advantages. For different operation sites and techniques, a variety of raw materials and printing methods can be adopted for 3D printed surgical guides to lower synthesis costs while still meeting clinical requirements.
Three-dimensional printed surgical guides have sufficient accuracy and physical strength to meet the clinical requirements of difficult mandibular distraction osteogenesis. With the help of 3D printed surgical guides, we were able to shorten operative time significantly. Prospective studies are required to confirm our findings. We hypothesize that choice of the appropriate 3D printing technique and materials can reduce synthesis costs while still fulfilling clinical requirements.
Conceptualization: Na Zhang.
Data curation: Zhe Mao.
Formal analysis: Zhe Mao.
Project administration: Yingqiu Cui.
Resources: Na Zhang.
Supervision: Yingqiu Cui.
Writing – original draft: Zhe Mao.
Writing – review & editing: Yingqiu Cui.
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Keywords:Copyright © 2019 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
3D print; bilateral mandibular traction osteogenesis; Pierre Robin sequence; surgery guide