Clinical Study on the Minimally Invasive-Guided Genioplasty Using Piezosurgery and 3D Printed Surgical Guide.

INTRODUCTION: A retrospective clinical study was performed regarding the minimally invasive-guided genioplasty technique (MIGG technique) described in a previous clinical note. The aims of this clinical study were to study the incidence of immediate complications with this technique compared with a control group using a nonminimally genioplasty technique, to validate the accuracy of the three-dimensional (3D) printed cutting guide, and to evaluate the duration of the surgery and the satisfaction of the surgeons with this technique. MATERIALS AND METHODS: One controlled group, including 56 patients, operated with a classical genioplasty and one group, including 24 patients operated with the MIGG technique. The inclusion criteria were patients from 18 years old benefiting from orthognathic surgery for dysmorphic maxillofacial disorders, sleep apneas, or posttraumatic malocclusion; operated by the three same surgeons. A database was retrospectively made, including the demographics parameters, the indication, the type and the duration of surgery, the incidence of complication, and the type of complication. The accuracy of the cutting guide was also studied by the comparison of two distances in the MIGG group on the preoperative surgical simulation and on the postoperative cephalometric radiography. A satisfaction survey for the surgeons of the department regarding the MIGG technique was also analyzed. CONCLUSION: No statistical difference was found in the incidence of complications between the MIGG group and the control group. Using a guide does not cause more surgical infection. The protection of the inferior alveolar nerve is obvious. The absence of statistical difference is due to the fact that the majority of patients also benefited from the bilateral sagittal split osteotomy during surgery. The 3D-cutting guide used is very accurate: There is indeed no significative difference in the measurements A and B before and after the genioplasty. The MIGG technique is thus a predictable, safe, and easy-to-use technique that should be used routinely by maxillofacial surgeons. It combines the latest technologies in piezosurgery and in 3D-guided surgery by the creation of a validated-accurate 3D-printed cutting guide. This technique is affordable by the use of open-source program and a desktop fused deposit Modeling 3D-printer. Finally, the comfort of the surgeon is improved, and the operating time is decreased.

The Minimally Invasive-Guided Genioplasty Technique using Piezosurgery and 3D printed surgical guide: An innovative technique.

INTRODUCTION: Mental nerve injuries with neurosensory deficits, asymmetries, and intra-operative bleeding are the main immediate complications of genioplasty. Following a recent systematic review, three-dimensional (3D)-printed cutting guide could improve the predictability and accuracy of this surgical technique avoiding postoperative asymmetries. Furthermore, anatomical structures in the surgical area (mental nerve and teeth roots) are better protected, reducing the morbidity and providing safer results. Ultrasonic piezoelectric osteotomy allows by its intrinsic characteristics, a selective cut of mineralized structure with a lower risk of vascular and nervous damage (microvibrations), intra-operative precision (thin cutting scalpel and no macro-vibrations), and blood-free site (cavitation effect). The aim of this article is to present a new minimally invasive technique: the minimally invasive-guided genioplasty technique (aka MIGG technique). This technique combines the advantages of piezosurgery and of a space-saving 3D-printed cutting guide, requiring open-source programs and an affordable 3D printing technology. MATERIALS AND METHODS: All the steps of this technique are described: preoperative surgical planning (CT scanner, segmentation with 3D slicer®, and design of the cutting guide with Blender®) and 3D printing of the guide and sterilization of it. The surgical procedure is presented in detail as well as the postoperative care. CONCLUSION: The MIGG technique offers, according to the authors, a better postoperative recuperation, a reduction in operating time, less complications, and protection of the anatomical structures (mental nerve, teeth, lingual soft tissue and vessels). This minimally invasive technique for genioplasty is a promising approach to perform a chin osteotomy.

Genioplasty with surgical guide using 3D-printing technology: A systematic review.

BACKGROUND: The purpose of this systematic review is to evaluate the current state of the art of making genioplasties using 3D printing technology. MATERIAL AND METHODS: A multi-database single-reviewer systematic review identified sixteen papers that fulfilled the selection criteria. There were mainly case series and case reports available (Level IV of the Oxford Evidence-based medicine scale); only two prospective study (Level III) evaluated this subject. These articles are analyzed in details and summarized in this review. RESULTS: The realization of genioplasties with surgical guide using 3D-printing technology could improve predictability and accuracy. It protects anatomical structures in the environment of the surgery, reducing by this way the morbidity and providing safer results. The type of printer and material used as well as the sterilization techniques should be further developed by the authors. The use of open-access software should also be further explored to allow the use of these new technologies by the largest number of surgeons. CONCLUSIONS: Finally, prospective multi-center studies with larger samples should be performed to definitively conclude the benefits of this new technology and allow for its routine use. This article is the first systematic review on this topic. Key words:Genioplasty, printing, three-dimensional, surgery, computer-assisted.

A systematic review on soft-to-hard tissue ratios in orthognathic surgery part II: Chin procedures.

PURPOSE: Precise soft-to-hard tissue ratios in orthofacial chin procedures are not well established. The aim of this study was to determine useful soft-to-hard tissue ratios for planning the magnitude of sliding genioplasty (chin osteotomy), osseous chin recontouring and alloplastic chin augmentation. MATERIAL AND METHODS: A systematic review of English and non-English articles using PubMed central, ProQuest Dissertations and Theses, Science Citation Index, Elsevier Science Direct Complete, Highwire Press, Springer Standard Collection, SAGE premier 2011, DOAJ Directory of Open Access Journals, Sweetswise, Free E-Journals, Ovid Lippincott Williams & Wilkins total Access Collection, Wiley Online Library Journals, and Cochrane Plus databases from their onset until July 2014. Additional studies were identified by searching the references. Search terms included soft tissue, ratios, genioplasty, mentoplasty, chin, genial AND advancement, augmentation, setback, retrusion, impaction, reduction, vertical deficit, widening, narrowing, and expansion. Study selection criteria were as follows: only academic publications; human patients; no reviews; systematic reviews or meta-analyses; no cadavers; no syndromic patients; no pathology at the chin or mandible region; only articles of level of evidence from I to IV; number of patients must be cited in the articles; hard-to-soft tissue ratios must be cited in the articles or at least are able to be calculated with the quantitative data available in the article; if all patients of one article have had bilateral sagittal split osteotomy (BSSO) performed along with chin osteotomy, there should be an independent group evaluation of the data concerning to the chin; and no restriction regarding the size of the group. Independent extraction of articles by two authors using predefined data fields, including study quality indicators (level of evidence). RESULTS: The search identified 22 articles. Eleven additional articles were found in their reference sections. Of these, two were evidence level IIIb, three were evidence level IIb, and the rest were evidence level IV. Three studies were prospective in nature. A high variability of soft-to-hard tissue ratios regarding genioplasty seemed to disappear if data were stratified according to confounding factors. With the available data, a soft-to-hard pogonion ratio of 0.9:1 and 0.55:1 could be used for chin advancement and chin setback surgery, respectively. CONCLUSION: Advancement and extrusion movements of the chin segment show respectively a 0.9:1 of sPg:Pg horizontally and 0.95:1 of sMe:Me vertically. Setback and impaction movements show respectively a -0.52:1 of sPg:Pg horizontally and -0.43:1 of sMe:Me vertically. Prospective studies are needed that stratify by confounding factors such as type of osteotomy technique, magnitude of the movement, age, sex, race/ethnicity, and quantity and quality of the soft tissues. More specifically, studies are needed regarding soft-to-hard tissue changes after chin extrusion ("downgrafting"), intrusion ("impaction"), and widening and narrowing surgery.

Impact of the mandibular divergence on the position of the inferior alveolar nerve and mylohyoid nerve: a computed tomography study and its relevance to bilateral sagittal split osteotomy.

PURPOSE: Bilateral sagittal split osteotomy (BSSO) is the most common procedure used to treat mandibular deformities. BSSO procedures include the Epker technique and the Dal Pont technique which are the most frequently used. Because of the intramandibular pathway of the inferior alveolar nerve (IAN), neurosensory disturbance of the lower lip and chin is the most common complication of BSSO. This study performed quantitative measurements from computed tomographic (CT) data obtained on dry human mandibles. The main aim of the study was to evaluate if mandibular divergence can predict the position of the IAN and the mylohyoid nerve (MHN) to prevent nerve injury. METHODS: After CT and 3D reconstruction of 65 dry mandibles, 30 measurements were made on 3 planes for each hemi-mandible. This allowed analysis of the IAN and MHN pathways. Three groups of hemi-mandibles were created depending on their divergence, and a statistical analysis was performed. RESULTS: Eight out of the 30 measurements showed a significant difference among the 3 groups. There was no significant difference for the remaining 22 measurements. CONCLUSIONS: The IAN seems to have a more superior position in the groups of mandibular hypo- and hyper-divergence. Orthognathic surgeons should use a more superficial retromolar bone incision in these cases. Finally, the Epker technique would be safer for preserving the MHN in normo- and hypo-divergent patients.