Maxillary reconstruction using tunneling flap technique with 3D custom-made titanium mesh plate and particulate cancellous bone and marrow graft: a case report

3D printing for bone regeneration: challenges and opportunities for achieving predictability

3D printing offers attractive opportunities for large-volume bone regeneration in the oro-dental and craniofacial regions. This is enabled by the development of CAD-CAM technologies that support the design and manufacturing of anatomically accurate meshes and scaffolds. This review describes the main 3D-printing technologies utilized for the fabrication of these patient-matched devices, and reports on their pre-clinical and clinical performance including the occurrence of complications for vertical bone augmentation and craniofacial applications. Furthermore, the regulatory pathway for approval of these devices is discussed, highlighting the main hurdles and obstacles. Finally, the review elaborates on a variety of strategies for increasing bone regeneration capacity and explores the future of 4D bioprinting and biodegradable metal 3D printing.

Investigating the accuracy of mandibulectomy and reconstructive surgery using 3D customized implants and surgical guides in a rabbit model

BACKGROUND

This study aimed to analyze the accuracy of the output of three-dimensional (3D) customized surgical guides and titanium implants in a rabbit model, and of mandibulectomy, reconstructive surgery, and surgical outcome; additionally, the correlation between surgical accuracy and surgical outcomes, including the differences in surgical outcome according to surgical accuracy, was analyzed.

RESULTS

The output of implants was accurately implemented within the error range (- 0.03-0.03 mm), and the surgical accuracy varied depending on the measured area (range - 0.4-1.1 mm). Regarding surgical outcomes, angle between the mandibular lower borders showed the most sensitive results and distance between the lingual cusps of the first molars represented the most accurate outcomes. A significant correlation was noted between surgical accuracy in the anteroposterior length of the upper borders pre- and postoperatively and the angle between the mandibular lower borders (regression coefficient = 0.491, p = 0.028). In the group wherein surgery was performed more accurately, the angle between the mandibular lower borders was reproduced more accurately (p = 0.021). A selective laser melting machine accurately printed the implants as designed. Considering the positive correlation among surgical accuracy in the mandibular upper borders, angle between the mandibular lower borders, and more accurately reproduced angle between the mandibular lower borders, the angle between the mandibular lower borders is considered a good indicator for evaluating the outcomes of reconstructive surgery.

CONCLUSION

To reduce errors in surgical outcomes, it is necessary to devise a positioner for the surgical guide and design a 3D surgical guide to constantly maintain the direction of bone resection. A fixed area considering the concept of three-point fixation should be selected for stable positioning of the implant; in some cases, bilateral cortical bone fixation should be considered. The angle between the mandibular lower borders is a sensitive indicator for evaluating the outcomes of reconstructive surgery.

High porosity 3D printed titanium mesh allows better bone regeneration

BACKGROUND

Most patients with insufficient bone mass suffer from severe horizontal or vertical bone defects in oral implant surgery. The purpose of this study was to compare the bone regeneration effects of titanium meshes with different porosity in the treatment of bone defects.

METHODS

Nine beagle dogs were equally divided into three groups based on execution time. Three months after the extraction of the first to fourth premolars of the mandible, three bone defects were randomly made in the mandible. Bone particles and three kinds of three-dimensional (3D) printed titanium nets with different porosities (low porosity group (LP), 55%; medium porosity group (MP), 62%; and high porosity group (HP), 68%) were replanted in situ. The beagles were killed 4, 8, and 12 weeks after surgery. Formalin-fixed specimens were embedded in acrylic resin. The specimens were stained with micro-CT, basic fuchsin staining, and toluidine blue staining.

RESULTS

Micro-CT analysis showed that the trabecular thickness, trabecular number, and bone volume fraction of the HP group were higher than those of the other two groups. Moreover, the trabecular separation of the HP group decreased slightly and was lower than that of the MP and LP groups. Histological staining analysis showed that the trabecular number in the HP group was higher than in the other two groups at 8 and 12 weeks, and the bone volume fraction of the HP was higher than that in the other two groups at 12 weeks. Moreover, the trabecular thickness of the MP was higher than that of the LP group at 12 weeks and the trabecular separation was lower in the HP group at 4 and 8 weeks. The differences were statistically significant (p < 0.05).

CONCLUSION

A 3D printed titanium mesh with HP in a certain range may have more advantages than a titanium mesh with LP in repairing large bone defects.

Customized Barrier Membrane (Titanium Alloy, Poly Ether-Ether Ketone and Unsintered Hydroxyapatite/Poly-l-Lactide) for Guided Bone Regeneration

Sufficient bone volume is indispensable to achieve functional and aesthetic results in the fields of oral oncology, trauma, and implantology. Currently, guided bone regeneration (GBR) is widely used in reconstructing the alveolar ridge and repairing bone defects owing to its low technical sensitivity and considerable osteogenic effect. However, traditional barrier membranes such as collagen membranes or commercial titanium mesh cannot meet clinical requirements, such as lack of space-preserving ability, or may lead to more complications. With the development of digitalization and three-dimensional printing technology, the above problems can be addressed by employing customized barrier membranes to achieve space maintenance, precise predictability of bone graft, and optimization of patient-specific strategies. The article reviews the processes and advantages of three-dimensional computer-assisted surgery with GBR in maxillofacial reconstruction and alveolar bone augmentation; the properties of materials used in fabricating customized bone regeneration sheets; the promising bone regeneration potency of customized barrier membranes in clinical applications; and up-to-date achievements. This review aims to present a reference on the clinical aspects and future applications of customized barrier membranes.

[Relationship between prognosis and different surgical treatments of zygomatic defects: A retrospective study]

OBJECTIVE

To evaluate the effect and summarize the characteristics of different treatment methods in repairing zygomatic defect.

METHODS

A total of 37 patients with zygomatic defect were reviewed in the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from August 2012 to August 2019. According to the anatomical scope of defect, the zygomatic defects were divided into four categories: Class 0, the defect did not involve changes in zygomatic structure or continuity, only deficiency in thickness or projection; Class Ⅰ, defect was located in the zygomatic body or involved only one process; Class Ⅱ, a single defect involved two processes; Class Ⅲa, referred to a single defect involving three processes and above; Class Ⅲb, referred to zygomatic defects associated with large maxillary defects. The etiology, defect time, defect size and characteristics of zygomatic defects, the repair and reconstruction methods, and postoperative complications were collected and analyzed. Postoperative computed tomography (CT) data were collected to evaluate the outcome of zygomatic protrusion. Chromatographic analysis was used to assess the postoperative stability.

RESULTS

Among the causes of defects, 25 cases (67.57%) were caused by trauma, and 11 cases (29.73%) were of surgical defects following tumor resection. We performed autologous bone grafts in 19 cases, 6 cases underwent vascularized tissue flap, 5 cases underwent external implants alone, and 7 cases underwent vascularized tissue flap combined with external implants. After the recovery of the affected side, the average difference of the zygomatic projection between the navigation group and the non-navigation group was 0.45 mm (0.20-2.50 mm) and 1.60 mm (0.10-2.90 mm), with a significant difference (P=0.045). Two patients repaired with titanium mesh combined with anterolateral thigh flap had obvious deformation or fracture of titanium mesh; 2 patients with customized casting prosthesis had infection after surgery and fetched out the prosthesis finally.

CONCLUSION

Autologous free grafts or alloplastic materials may be used in cases without significant structural changes. Pedicle skull flap or vascularized bone tissue flap is recommended for zygomatic bone defects with bone pillar destruction, chronic inflammation, oral and nasal communication or significant soft tissue insufficiency. Titanium mesh can be used to repair a large defect of zygomatic bone, and it is suggested to combine with vascularized bone flap transplantation.

Main Applications and Recent Research Progresses of Additive Manufacturing in Dentistry

In recent ten years, with the fast development of digital and engineering manufacturing technology, additive manufacturing has already been more and more widely used in the field of dentistry, from the first personalized surgical guides to the latest personalized restoration crowns and root implants. In particular, the bioprinting of teeth and tissue is of great potential to realize organ regeneration and finally improve the life quality. In this review paper, we firstly presented the workflow of additive manufacturing technology. Then, we summarized the main applications and recent research progresses of additive manufacturing in dentistry. Lastly, we sketched out some challenges and future directions of additive manufacturing technology in dentistry.

A pH-response chemotherapy synergistic photothermal therapy for tumor suppression and bone regeneration by mussel-inspired Mg implant

Primary malignant bone tumors can be life-threatening. Surgical resection of tumor plus chemotherapy is the standard clinical treatment. However, postoperative recovery is hindered due to tumor recurrence caused by residual tumor cells and bone defect caused by resection of tumor tissue. Herein, a multifunctional mussel-inspired film was fabricated on Mg alloy, that is, an inner hydrothermal-treated layer, a middle layer of polydopamine, and an outer layer of doxorubicin. The modified Mg alloy showed excellent photothermal effect and thermal/pH-controlled release of doxorubicin. The synergistic effect of chemotherapy and photothermal therapy enabled the modified Mg alloy to kill bone tumor in vitro and inhibit tumor growth in nude mice. Moreover, because of the controlled release of Mg ions and biocompatibility of polydopamine, the modified Mg alloy supported extracellular matrix mineralization, alkaline phosphatase activity, and bone-related gene expression in C3H10T1/2. Bone implantation model in rats verified that the modified Mg showed excellent osteointegration. These findings prove that the use of mussel-inspired multifunction film on Mg alloy offers a promising strategy for the therapy of primary malignant bone tumor.

Titanium mesh and pedicled buccal fat pad for the reconstruction of maxillary defect: case report

Background

Pedicled buccal fat pad (PBFP) has been used for the reconstruction of small-sized maxillary defects but cannot be used without hard tissue support on the defect larger than 4 cm × 4 cm × 3 cm.

Case presentation

A 64-year-old man had a history of squamous cell carcinoma of the left maxilla. After removal of the posterior maxilla, a complex bone defect (size, 5 cm × 4 cm × 3 cm) was immediately reconstructed using PBFP combined with a titanium mesh. A pinpoint fistula was found in the left palatal region 1 month after the surgery and was treated with a palatal sliding flap. There were no further complications during the follow-up.

Conclusion

The present technique demonstrated that PBFP combined with a titanium mesh could be used for the reconstruction of complex maxillary defect (size, 5 cm × 4 cm × 3 cm) without additional bone graft.

Patient-specific plate for navigation and fixation of the distal radius: a case series

Purpose

Corrective osteotomy of a malunited distal radius conventionally relies on 2D imaging techniques for alignment planning and evaluation. However, this approach results in suboptimal bone repositioning, which is associated with poor patient outcomes. In this case series, we evaluate the use of novel patient-specific plates (PSPs), which feature navigation and fixation of bone segments as preoperatively planned in 3D.

Methods

Ten participants with distal radius malunion underwent CT scans for preoperative alignment planning. Patient-specific guides and plates were designed, 3D-printed, and sterilized for use in corrective surgery of the distal radius. Pre- and postoperative results were compared in regard to clinical, functional, and radiographic outcomes.

Results

The application of a PSP was successful in 7 of the 10 cases. After treatment, the residual alignment error was reduced by approximately 50% compared with conventional treatment. The use of PSPs reduced pain significantly. Pre- and postoperative results were pooled and demonstrated significant correlations between: (1) pain and malpositioning, (2) the range of pro- and supination motion, the MHOQ score, the EQ-5D-5L score and dorsovolar angulation, and (3) MHOQ score and proximodistal translation.

Conclusion

The correlation between malalignment and MHOQ score, EQ-5D-5L score, pain, and range of motion shows that alignment should be restored as well as possible. Compared to the conventional approach, which relies on 2D imaging techniques, corrective osteotomy based on 3D preoperative planning and intraoperative fixation with a PSP has been shown to improve bone alignment and reduce pain.

Level of evidence

IV.