Augmented reality hologram combined with pre-bent distractor enhanced the accuracy of distraction vector transfer in maxillary distraction osteogenesis, a study based on 3D printed phantoms.

Background: Vector control is a significant concern in maxillary distraction osteogenesis (DO). Distraction vector planning on the patient's 3D-printed skull phantom is more intuitive for surgeons and cost-efficient than virtual surgical planning. However, the accuracy of transferring the planned vector to intraoperative (vector transfer) according to the shape of the pre-bent footplate alone is relatively limited. The application of augmented reality (AR) in surgical navigation has been studied for years. However, few studies have focused on its role in maxillary DO vector transfer. This study aimed to evaluate the accuracy of AR surgical navigation combined with the pre-bent distractor in vector transfer by comparing it with the pre-bent distractor alone. Methods: Ten patients with maxillary hypoplasia were enrolled with consent, and three identical 3D-printed skull phantoms were manufactured based on per patient's corresponding pre-operative CT data. Among these, one phantom was for pre-operative planning (n = 10), while and the other two were for the AR+Pre-bending group (n = 10) and the Pre-bending group (n = 10) for the experimental surgery, respectively. In the Pre-bending group, the distraction vector was solely determined by matching the shape of footplates and maxillary surface. In the AR+Pre-bending group, the distractors were first confirmed to have no deformation. Then AR surgical navigation was applied to check and adjust the vector in addition to the steps as in the Pre-bending Group. Results: For the angular deviation of the distraction vector, the AR+Pre-bending group was significantly smaller than the Pre-bending group in spatial (p < 0.001), x-y plane (p = 0.002), and y-z plane (p < 0.001), and there were no significant differences in the x-z plane (p = 0.221). The AR+Pre-bending group was more accurate in deviations of the Euclidean distance (p = 0.004) and the y-axis (p = 0.011). In addition, the AR+Pre-bending group was more accurate for the distraction result. Conclusions: In this study based on 3D printed skull phantoms, the AR surgical navigation combined with the pre-bent distractor enhanced the accuracy of vector transfer in maxillary DO, compared with the pre-bending technique alone.

Modified envelope flap, a novel incision design, can relieve complications after extraction of fully horizontal impacted mandibular third molar.

BACKGROUND/PURPOSE: Patients always suffer from dental extraction complications of fully horizontal impacted mandibular third molar, such as pain, swelling and limited mouth opening. A novel incision, modified envelope flap (MEF), was designed to alleviate the complications through minimizing the tissue injury during this surgery procedure. MATERIALS AND METHODS: With indications of removing bilateral fully horizontal impacted mandibular the third molars, 40 patients were recruited and received dental extraction under incision with modified envelope flap (MEF) in one lateral and modified triangular flap (MTF) in the other lateral respectively. MEF incision was made along the buccal gingival sulcus from mesial to distal of the mandibular second molar with an extension to retromolar trigone at 45°inclination. As a control, traditional incision MTF was made starting with a vertical incision at the mesial buccal gingiva of the mandibular second molar with extension as MEF. Fully horizontal impacted mandibular third molar were extracted successfully. Surgery time and postoperative pain, swelling and mouth opening were recorded at day 1, 3, 7. RESULTS: There was no significant difference of the surgery time, pain, swelling (day 1) and mouth opening (day1) between MEF and MTF group (p > 0.05). However, the scores of swelling (day 3, 7) and mouth opening (day3, 7) of MEF group were much lower than that of MTF group (p < 0.05), indicating attenuated complications and quicker recovery. CONCLUSION: With small injury, MEF hasn't prolong the surgery time but relieves complications after extraction of fully horizontal impacted mandibular third molar and might be a promising method compared with MTF.

Correction to: The Soft Tissue Angular Analysis of Facial Profile in Unoperated Adult Patients with Unilateral Cleft Palate.

Due to errors introduced during the production process, Tables were published incorrectly in the original publication of this article. The correct tables are given here.

The Soft Tissue Angular Analysis of Facial Profile in Unoperated Adult Patients with Unilateral Cleft Palate.

OBJECTIVE: The purpose of this study was to investigate the differences in facial profile development between unoperated adult cleft palate (UACP) patients and normal controls and to analyse the reasons for the differences. MATERIALS AND METHODS: A total of 50 individuals with a unilateral cleft palate and 20 normal controls were selected to undergo angular measurement of their facial profiles. Data with significant differences between the two groups were analysed. RESULTS: Seven angle measurements of the facial profile showed that the mid-facial protrusion of the UACP patients had no significant differences from the control group (p > 0.05). But their angle of the medium face (N'-Trg-Sn) was significantly lower than the non-cleft controls (p < 0.05), suggesting a worse vertical development of the middle face. A significantly larger nasal tip angle (Cm-Sn/N'-Prn) for UACP patients suggested they had a rounder and blunter nasal tip (p < 0.05). The soft tissue facial angle and chin-lip angle of UACP patients had significant differences from non-cleft controls (p < 0.05), but the head position angle (Sn-Sm-THP) had no significant difference between two groups (p > 0.05), which suggested a steep mandibular plane for UACP patients but without severe retraction of the chin. CONCLUSION: The development of facial protrusions in UACP patients is similar to that in normal adults, but the vertical development in the middle face is insufficient. Such hypoplasia may be related to the intrinsic deficiency of the maxilla. There is a tendency for flat nasal growth and insufficient development of the chin in UACP patients. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

[Application of joint reconstruction with autogenous coronoid process graft to treat temporomandibular joint ankylosis].

PURPOSE: To evaluate the clinical effect of joint reconstruction by using autogenous coronoid process graft to treat temporomandibular joint(TMJ) ankylosis. METHODS: Nine cases of TMJ ankylosis from September 2008 to September 2010 were surgically treated by joint reconstruction with autogenous coronoid process graft, using autogenous articular disc or prosthodontic membrane as interpositional material. Mouth opening, occlusion and cone beam CT(CBCT) were used for evaluation before and after surgery. RESULTS: Satisfactory mouth opening was achieved in all patients and no one got occlusal changes or reankylosis during follow-up. CBCT showed that coronoid process graft reached bone union with the ramus and turned to be round. CONCLUSIONS: It is effective to cure TMJ ankylosis through joint reconstruction with autogenous coronoid process graft.

[Experimental study on transplantation of bone morphogenetic protein-2 gene transfected bone mesenchymal stem cells compounded with Pluronic F-127 for promoting bone regeneration in rabbit mandibular distraction].

OBJECTIVE: To investigate the promotive effect of transplantation of bone morphogenetic protein-2 (BMP-2) gene transfected bone mesenchymal stem cells (BMSCs) compounded with injectable bone tissue engineering scaffold material Pluronic F-127 on bone regeneration in rabbit mandibular distraction osteogenesis(DO). METHODS: Forty-eight New Zealand's white rabbits were randomized into four groups with twelve in each. All the objects were prepared into DO surgical model. On the 2nd day of consolidation, group A, B, C and D were injected with the same amount of 200 microL of the compound of BMP-2 gene transfected BMSCs with Pluronic F-127, the solution with BMP-2 gene transfected BMSCs, the solution of BMSCs and physiological saline at distraction zone, respectively. Two halves of the objects of all groups were sacrificed at the end of 2nd and 6th week consolidation, respectively. And the specimens of right mandible were prepared for radiological, histomorphological and immunohistochemical examinations to evaluate bone regeneration. RESULTS: Both radiological and immunohistochemical images were analyzed and processed with professional software. At the end of 2nd and 6th week consolidation, the bone mineral density and the expression of BMP-2 protein in distraction area of group A were significantly higher than those of B, C, D group (P<0.01). Group B was significantly higher than that in group C and D (P<0.01). There was no significant difference between group C and D (P>0.05). And the regeneration quality of distraction zone in group A and B were better than those in group C and D, just as that of group A better than group B. Conclusion The transplantation of BMP-2 gene transfected BMSCs compound with Pluronic F-127 could effectively promote bone regeneration in rabbit mandibular DO.