The stiffness of titanium mesh is a double-blade sword to repair larger alveolar ridges defect with excellent space maintenance ability, while invade the surrounding soft tissue and lead to higher mesh exposure rates. Understanding the mechanical of oral mucosa/titanium mesh/bone interface is clinically meaningful. In this study, the above relationship was analyzed by finite elements and verified by setting different keratinized tissue width in oral mucosa.
Two three-dimensional finite element models were constructed with 5 mm keratinized tissue in labial mucosa (KM cases) and 0 mm keratinized tissue in labial mucosa (LM cases). Each model was composed of titanium mesh, titanium screws, graft materials, bone, teeth and oral mucosa. After that, a vertical (30 N) loadings were applied from both alveolar ridges direction and labial mucosa direction to stimulate the force from masticatory system. The displacements and von Mises stress of each element at the interfaces were analyzed.
Little displacements were found for titanium mesh, titanium screws, graft materials, bone and teeth in both LM and KM cases under different loading conditions. The maximum von Mises stress was found around the lingual titanium screw insertion place for those elements in all cases. The keratinized tissue decreased the displacement of oral mucosa, decreased the maximum von Mises stress generated by an alveolar ridges direction load, while increased those stress from labial mucosa direction load. Only the von Mises stress of the KM cases was all lower than the tensile strength of the oral mucosa.
The mucosa was vulnerable under the increasing stress generated by the force from masticatory system. The adequate buccal keratinized mucosa width are critical factors in reducing the stress beyond the titanium mesh, which might reduce the titanium exposure rate.

UNASSIGNED: To explore the effectiveness of two-stage operation on free latissimus dorsi myocutaneous flap transplantation and skull contour reconstruction in the treatment of head titanium mesh exposure complicated with soft tissue infection.
UNASSIGNED: Between January 2015 and December 2021, 13 patients with head titanium mesh exposure complicated with soft tissue infection were admitted. There were 9 males and 4 females with a mean age of 42.9 years (range, 23-64 years). The duration of titanium mesh exposure was 22-609 days (median, 102 days). The wound site located at the frontal part in 3 cases, the parietal part in 1 case, the occipital part in 2 cases, the frontal-parietal part in 1 case, the temporal-parietal part in 4 cases, and the frontotemporal part in 2 cases. The titanium mesh had been taken out in 5 patients before admission, leaving skull defect and shape collapse, with signs of infection. The bacterial culture was positive in 7 cases and negative in 6 cases. The imaging examination revealed that the size of the skull defect ranged from 6 cm×5 cm to 21 cm×17 cm and the scalp defect ranged from 1 cm×1 cm to 15 cm×10 cm. The soft tissue infection did not reach dura in 5 cases, reached dura in 6 cases, and reached frontal sinus in 2 cases. The two-stage surgical protocol was used in all patients. In the first-stage operation, the latissimus dorsi myocutaneous flap was designed to repair the skull and scalp defects after removing the titanium mesh and thorough debridement. The size of muscle flap ranged from 13.5 cm×4.0 cm to 21.0 cm×17.0 cm, and the skin flap ranged from 7.0 cm×4.0 cm to 15.0 cm×10.0 cm. After the flap survived and stabilized, the second-stage operation was performed. The titanium mesh was implanted to reconstruct the skull contour. The size of titanium mesh ranged from 7.0 cm×6.0 cm to 21.5 cm×17.5 cm. The interval between the first- and second-stage operations was 3.7-17.8 months, with an average of 11.4 months. The survival of the skin flap, the appearance of the head, and the presence of re-exposed titanium mesh and infection were observed after operation.
UNASSIGNED: At the first-stage operation, venous embolism occurred in 1 case, and no obvious abnormality was observed after treatment. All the flaps survived and the incisions healed by first intention. Besides, the incisions of the second-stage operation healed by first intention. All patients were followed up 1-96 months (median, 14 months). During follow-up, no exposure to titanium mesh, infection, or other complications occurred. The appearance satisfaction rate of the patients was 92.31% (11/13). There was no significant difference in the skull contour between the affected side and the healthy side in all patients.
UNASSIGNED: For the head titanium mesh exposure with soft tissue infection, the application of two-stage operation on free latissimus dorsi myocutaneous flap transplantation and skull contour reconstruction can reduce the risks of implant exposure and infection again by increasing the thickness of the scalp and blood supply, filling the wound cavity, and obtain good effectiveness.
UNASSIGNED: 探讨分阶段游离背阔肌皮瓣移植及颅骨轮廓重建治疗头部钛网外露合并软组织感染的疗效。.
UNASSIGNED: 2015年1月—2021年12月，收治13例头部钛网外露合并软组织感染患者。男9例，女4例；年龄23～64岁，平均42.9岁。钛网暴露时间22～609 d，中位时间102 d。创面部位：额部3例，顶部1例，枕部2例，额顶部1例，颞顶部4例，额颞部2例。其中5例该次入院前钛网已取出，遗留颅骨缺损和外形塌陷，存在感染征象。细菌培养阳性7例，阴性6例。影像学检查示颅骨缺损范围为6 cm×5 cm～21 cm×17 cm，头皮缺损范围为1 cm×1 cm～15 cm×10 cm；软组织感染深度：未侵及硬脑膜5例，侵及硬脑膜6例，侵及额窦2例。采用分阶段手术方案，第1阶段取出钛网、彻底清创后，切取背阔肌皮瓣修复颅骨及头皮缺损。背阔肌皮瓣切取范围：肌瓣13.5 cm×4.0 cm～21.0 cm×17.0 cm，皮瓣7.0 cm×4.0 cm～15.0 cm×10.0 cm。待皮瓣成活稳定后行第2阶段手术，再次植入钛网，重建颅骨轮廓；钛网范围为7.0 cm×6.0 cm～21.5 cm×17.5 cm。两次手术间隔时间3.7～17.8个月，平均11.4个月。术后观察皮瓣成活、头部外观，有无钛网再次外露和感染等情况发生。.
UNASSIGNED: 第1阶段术后1例出现皮瓣静脉栓塞，经处理后未见明显异常；背阔肌皮瓣全部成活，供受区创面均Ⅰ期愈合。第2阶段术后切口均Ⅰ期愈合。13例患者均获随访，随访时间1～96个月，中位时间14个月。随访期间无再次钛网外露、感染等情况发生。末次随访时，患者外观主观满意率为92.31%（11/13）。所有患者创区颅骨轮廓与健侧无明显差异。.
UNASSIGNED: 对于头部钛网外露合并软组织感染，分阶段游离背阔肌皮瓣移植及颅骨轮廓重建方案通过增加头皮厚度及血供、填塞死腔，减少了钛网再次暴露和二次感染风险，临床疗效确切。.

The aim of this study was to determine the clinical outcomes and long-term stability of individualized titanium mesh combined with free flap for orbital floor reconstruction after maxillectomy and to identify the risk factors for titanium mesh exposure.
The data of 66 patients who underwent maxillectomy and orbital floor defect reconstruction by individualized titanium mesh in Peking University School and Hospital of Stomatology between 2011 and 2019 were retrospectively reviewed. Postoperative ophthalmic function and success of aesthetic restoration were assessed. Titanium mesh exposure was recorded and the risk factors were identified.
Mean follow-up was for 24.8 months (range, 6-92 months). Ophthalmic function was successfully restored in 63/66 patients. Aesthetic restoration was not considered satisfactory by 10 patients. Titanium mesh exposure occurred in six patients (exposure rate, 9.1%). Preoperative radiotherapy was identified as an independent risk factor for mesh exposure (OR = 28.8, P = 0.006). Previous surgery, postoperative radiotherapy, pathological type of the primary lesion, the type of tissue flap applied, and the use of intraoperative navigation were not significant risk factors. Six patients with titanium mesh exposure underwent second surgery, but mesh exposure recurred in two patients due to insufficient soft tissue coverage.
Individualized titanium mesh with free flap can effectively restore maxilla-orbital defects. Preoperative radiotherapy is an independent predictor of postoperative titanium mesh exposure. Adequate soft tissue coverage of the mesh may reduce the risk of mesh exposure.
4 (case-control study) Laryngoscope, 131:2231-2237, 2021.

OBJECTIVE: Titanium mesh implants (TMIs) are used for various purposes in craniotomy. Although delayed implant exposure and thinning of the overlying skin are well-known complications, the mechanism has not yet been elucidated. We reviewed our cases and propose a mechanism for TMI exposure.
METHODS: From 2009 to 2018, we treated 14 patients with delayed titanium implant exposure after craniotomy. The exposed titanium implant was a TMI in 4 patients, a titanium mesh plate in 6 patients, and a titanium fixation plate with holes in 4 patients. We reviewed the preoperative computed tomography (CT) scans and operative findings.
RESULTS: The interval between craniotomy and implant exposure was 13 years (range, 5-27). Implant exposure occurred at the temporal region in 7 patients, frontal region in 6 patients, and parietal region in 1 patient. The skin ulcer size ranged from 0.25 to 10 cm2 (mean, 1.95). In the patients with TMI exposure, the dura was expanded, and no residual epidural space was identified on the CT scans; however, epidural dead space was revealed on the CT scan in the patients with titanium mesh plate or titanium fixation plate exposure.
CONCLUSIONS: We believe that the key factor resulting in delayed titanium mesh exposure is the pressure gradient between the atmosphere and the intracranial space. Fluctuation of this gradient exerts dynamic stress on the tissue in the mesh holes and the adjacent tissue, resulting in tissue damage and implant exposure.

BACKGROUND: Skin ulcers and alloplastic implant exposure are intractable complications that arise after cranial defect reconstruction. Many methods have been used to repair these defects, including skin grafting, local flaps, and free flaps; however, in most cases, alloplastic implants must be removed to control infections. Here, we describe the use of a reversed temporal island flap to repair exposed titanium mesh without removing it.
METHODS: Eight cases of skin and titanium mesh exposure were included from 2010 to 2015. A preauricular flap pedicled on the reversed superficial temporal artery was designed to repair forehead defects. The titanium mesh was retained, resterilized, and reimplanted.
RESULTS: Flaps were survived completely, and the titanium meshes were reimplanted with no complications. The results were aesthetically and functionally sufficient, with minimal donor-site morbidity in all cases during the 10- to 24-month follow-up period.
CONCLUSIONS: The described method is easy to design and perform. The flap has a reliable blood supply to help fight infection. The titanium mesh is preserved completely, avoiding a second cranioplasty.