dental implantation is an effective therapeutic option to replace missing teeth in modern dentistry . in order for an implant to successfully sustain functional loads , there must be sufficient alveolar bone around the implant . implants must be at least 5 mm wide and 7 - 10 mm in length1 . after implantation , dehiscence or fenestration defects frequently occur because of insufficient residual bone volume . bone augmentation should be performed prior to and/or simultaneously with implant placement when the preoperative examination shows a lack of alveolar bone volume at the implant placement site . alveolar bone defects may be treated with various bone regeneration techniques including block bone graft , guided bone regeneration ( gbr ) , ridge splitting , and distraction osteogenesis2,3,4,5 . gbr is one of the most predictable methods , which mostly uses a barrier membrane to separate the grafted defect and the surrounding connective tissue for successful bone regeneration3 . two major types of non - resorbable barrier membranes are expanded polytetra - fluoroethylene ( e - ptfe ) and titanium mesh6 . despite many advantages of gbr , it is difficult to maintain suitable space for ideal bone regeneration because unless there is a hard structure to support the space , soft tissue collapses into it . it has been applied to various defects indicated for gbr , including sinus augmentation sites8,9 . several studies have used gbr procedures with titanium mesh and various bone graft materials including autologous bone , bovine bone mineral , alloplastic materials , and their combinations8,10,11,12,13,14 . however , studies that have used titanium mesh and allogeneic graft , especially freeze - dried bone allograft ( fdba ) , are rare . few of these studies present histologic evidence of bone maturation on the grafted site with titanium mesh and fdba . one complication related to titanium mesh is the high risk of exposure following repeated mucosal irritation . although titanium mesh exposure does not always lead to bone augmentation failure in a clinical setting8,13 , the bone quality of gbr would be adversely affected15 . before its application , titanium mesh should be cut , bent , and trimmed . any prominent , sharp edges resulting from these manipulations may cause membrane exposure . recently , preformed titanium mesh with round and blunt edges were developed to prevent mucosal irritation . we used a customized , three - dimensional , preformed titaniumn mesh ( smartbuilder ; osstem , busan , korea ) to reconstruct the peri - implant defects occurring immediately after implant placement . clinical and histologic investigations were used to evaluate the preformed titanium mesh 's efficacy as a barrier membrane against a mixture of autologous and fdba in localized alveolar bone regeneration . a total of 10 patients ( 5 male and 5 female , aged 17 - 87 years ) who were partially edentulous participated in this study between august 2012 and june 2014 at hanyang university hospital . preoperative clinical and radiologic evaluations indicated that the gbr procedure should be performed simultaneously with the implant placement in all patients . this study was approved by the institutional review board of hanyang university hospital ( hyh irb 2012 - 06 - 014 ) . implant were placed under local anesthesia using a trapezoidal full - thickness flap with two vertical releasing incisions . a total of 12 implants ( ts iii ca ; osstem ) in 10 patients were inserted by the standard procedure . in all cases , the implant threads were partially exposed and the gbr procedure was performed for these peri - implant defects . then , the preformed titanium mesh was located on that height and immobilized by cover cap for a staged approach or by healing abutment for transmucosal gbr . the height , cover cap , and healing abutment were specifically designed for the preformed titanium mesh.(fig . 2 ) an autobone collector ( osstem ) was used to harvest autologous bone chips were either from the mandibular ramus or from an area adjacent to the surgical site . the bone chips were mixed with fdba ( sure - oss ; hansbiomed , seoul , korea ) in 1 : 1 volume ratio . a mixture of the graft materials was placed on the dehiscence or fenestration defect ( fig . antibiotics and analgesics were administered three times daily for ten days in addition to 0.12% chlorhexidine mouth rinse . the sutures were removed two weeks after surgery , and the patients were followed every four weeks after surgery for wound assessment . after approximately four months of the healing period , re - entry surgery was performed to uncover the implant under the minimum flap reflection . 5 ) a trephine drill with a 2.2 mm internal diameter was used to obtain the core biopsy from the regenerated site.(fig . two months after the re - entry surgery , both the osseointegration and the integrity of the peri - implant tissue were evaluated . the complications and implant success rate were investigated for twelve months after the definite prosthesis was placed . the specimen obtained at re - entry was immediately fixed in 10% buffered formalin , dehydrated in a series of ethanol baths , and embedded in methyl methacrylate for histologic evaluation . the polymerized blocks were sectioned with a diamond saw microtome , micro - grinded and polished using sandpaper . the areas of vital bone , residual graft materials , and soft tissue were grossly measured and analyzed . a total of 10 patients ( 5 male and 5 female , aged 17 - 87 years ) who were partially edentulous participated in this study between august 2012 and june 2014 at hanyang university hospital . preoperative clinical and radiologic evaluations indicated that the gbr procedure should be performed simultaneously with the implant placement in all patients . this study was approved by the institutional review board of hanyang university hospital ( hyh irb 2012 - 06 - 014 ) . implant were placed under local anesthesia using a trapezoidal full - thickness flap with two vertical releasing incisions . a total of 12 implants ( ts iii ca ; osstem ) in 10 patients were inserted by the standard procedure . in all cases , the implant threads were partially exposed and the gbr procedure was performed for these peri - implant defects . then , the preformed titanium mesh was located on that height and immobilized by cover cap for a staged approach or by healing abutment for transmucosal gbr . the height , cover cap , and healing abutment were specifically designed for the preformed titanium mesh.(fig . 2 ) an autobone collector ( osstem ) was used to harvest autologous bone chips were either from the mandibular ramus or from an area adjacent to the surgical site . the bone chips were mixed with fdba ( sure - oss ; hansbiomed , seoul , korea ) in 1 : 1 volume ratio . a mixture of the graft materials was placed on the dehiscence or fenestration defect ( fig . antibiotics and analgesics were administered three times daily for ten days in addition to 0.12% chlorhexidine mouth rinse . the sutures were removed two weeks after surgery , and the patients were followed every four weeks after surgery for wound assessment . after approximately four months of the healing period , re - entry surgery was performed to uncover the implant under the minimum flap reflection . 5 ) a trephine drill with a 2.2 mm internal diameter was used to obtain the core biopsy from the regenerated site.(fig . two months after the re - entry surgery , both the osseointegration and the integrity of the peri - implant tissue were evaluated . the complications and implant success rate were investigated for twelve months after the definite prosthesis was placed . the specimen obtained at re - entry was immediately fixed in 10% buffered formalin , dehydrated in a series of ethanol baths , and embedded in methyl methacrylate for histologic evaluation . the polymerized blocks were sectioned with a diamond saw microtome , micro - grinded and polished using sandpaper . the areas of vital bone , residual graft materials , and soft tissue were grossly measured and analyzed . newly regenerated bone at the augmented sites was confirmed by re - entry at four months after the initial surgery . after removing the preformed titanium mesh , a thin connective tissue layer called " pseudoperiosteum " postsurgical complications were observed in three of the 10 patients ( 30% ) . in two of these patients , the titanium mesh became exposed and there was small flap dehiscence on the cover cap in one patient . during the healing period , the exposed titanium meshes and cover caps were frequently irrigated with 0.12% chlorhexidine until fibrous tissue formed beneath the titanium mesh and graft materials were no long lost into the oral cavity . no signs of infection or suppuration were identified in the soft tissue around the exposed area . in all cases , the quality and quantity of the regenerated bone was clinically acceptable ; however , at the exposed site , there was some resorption of graft materials . radiologic evaluation at mesh insertion , removal and 12 months after definitive prostheses were placed showed stable marginal bone in all implants.(fig . 7 ) histologic findings of the core specimen from patient # 2 revealed that the allograft particles are well - incorporated and surrounded by newly formed vital bone and connective tissue.(fig . 8) vital bone surrounded ~80% of the allograft , while fibrous marrow tissue surrounded 5% of the graft , and inflammatory cell infiltrates made up the remaining 15% . adequate bone volume is a prerequisite for the long - term success of endosseous implants . insufficient bone must be reconstructed with various hard tissue augmentation procedures2,3,4 . in order for augmentation procedures to be successful , it is imperative to stabilize the graft during healing , support the osteogenic potential of the graft materials , and close the primary soft tissue . gbr is often performed during implant placement to correct the peri - implant alveolar defects , and is considered a favorable procedure . the gbr technique uses a barrier membrane to prevent soft tissue cells from entering the grafted space , maintaining the space for successful bone regeneration . actually , the most important ability of gbr is its ability to maintain space under the membrane . this preliminary study focused on a titanium mesh , which is one of the most reliable barrier membranes in ridge augmentation . based on these qualities , titanium mesh has been useful in the reconstruction and augmentation of oral and maxillofacial defects . another advantage of the titanium mesh is its inherent rigidity that maintains the space needed to allow new bone growth . several studies have demonstrated that titanium mesh supports the grafted space and prevents soft tissue collapse better than does e - ptfe6,14 . in contrast , although some cross - linked collagen membranes are also rigid resorbable barrier membranes , they only protect the grafted space at the beginning of regeneration and gradually lose their rigidity6 . one of the prerequisites of successful gbr is a barrier mem brane that restricts epithelial cell migration . unlike other barrier membranes the macro - pores allow sufficient blood flow and diffusion of nutrients and oxygen that consequently enhance the regeneration of the bone and soft tissue . as the membrane pore size of increases , so does the regenerative capacity . despite concern that epithelial cells and bacteria could infiltrate through large pores , space maintenance was found to actually play a greater role in bone regeneration than does cell occlusiveness18 . when blood clot stabilization is achieved with the titanium mesh in addition , the titanium mesh with large pores demonstrates more osseous formation and less soft tissue attachment than does a titanium mesh with small pores12 . we found that easily removable titanium meshes tend to have less adhesive fibrous tissue formation . the titanium meshes used in this study have two different pore sizes that permit the migration of bone - forming cells , but block the grafted materials from leaking . a major limitation of the titanium mesh is the fairly high rate of mesh exposure through the tissue . corinaldesi et al.8 reported a exposure rate of 14.8% after particulated bone augmentation in the mandible . louis et al.14 reported 52% exposure of the maxilla and mandible with a range of 43%-55% . three of the 10 patients ( 30% ) in this study experienced titanium mesh exposure during the healing period ( with one in the maxilla and two in the mandible ) . however , even in cases of membrane exposure , there was satisfactory bone regeneration and successful implant survival . the most common cause of mesh exposure is continuous mucosal irritation by the titanium mesh . sharp edges produced by improper mesh adjustment may increase the risk of exposure . using a preformed titanium mesh having a preformed mesh not only shortens the duration of surgery , but also reduces the risk of mesh exposure . in our study , there were no titanium mesh edge exposures because the preformed titanium meshes had optimal round and blunt edges . ciocca et al.10 also prepared a customized titanium mesh using computer - aided design and computer - aided manufacturing ( cad / cam ) technology to augment the atrophic alveolar ridge and demonstrated satisfactory bone regeneration . few studies have reported the histological results of new bone formation with titanium mesh use in humans . proussaefs and lozada19 demonstrated ~36% new bone formation after 8 months in a histologic study of cases augmented by mixed grafts of autologous and inorganic bovine bone ( in a 1 : 1 volume ratio ) . using the mesh with either a combination graft ( of 70% autologous bone and 30% bovine bone matrix ) or a graft of autologous bone alone produces similar amounts of total bone volume 8 - 9 months after grafting11 . in accordance with previous studies using allogeneic grafts20,21 , preliminary histologic analysis in our study demonstrated a satisfactory amount of new bone formation with limited allograft particle embedding . it is thought that fdba scaffolding connects with marrow trabeculae , providing favorable osteoconductivity for new bone formation . moreover , marginal bone levels around the implant remained stable for 12 months after the final prostheses were placed . the customized , three - dimensional , and preformed titanium mesh used in combination with autologous bone and fdba induced successful bone regeneration in peri - implant defects occurring after implant placement . even in the cases of titanium mesh exposure , this preliminary study shows histologic evidence of satisfactory vital bone formation in the augmented area . preformed titanium mesh supports the grafted space for new bone formation , makes application and removal convenient , and minimizes the risk of mesh exposure in the reconstruction of peri - implant alveolar bone defects .
objectivesthe purpose of this preliminary study is to evaluate the effectiveness of a customized , three - dimensional , preformed titanium mesh as a barrier membrane for peri - implant alveolar bone regeneration.materials and methodsten patients were recruited for this study . at the time of implant placement , all patients had fenestration or a dehiscence defect around the implant fixture . 
 a mixture of particulate intraoral autologous bone and freeze - dried bone allograft was applied to the defect in a 1 : 1 volume ratio and covered by the preformed titanium mesh . 
 a core biopsy specimen was taken from the regenerated bone four months postoperatively . 
 patients were followed for 12 months after the definitive prosthesis was placed.resultssatisfactory bone regeneration with limited fibrous tissue was detected beneath the preformed titanium mesh . 
 histologic findings revealed that newly formed bones were well - incorporated into the allografts and connective tissue . 
 new growth was composed of approximately 80% vital bone , 5% fibrous marrow tissue , and 15% remaining allograft . 
 all implants were functional without any significant complications.conclusionthe use of preformed titanium mesh may support bone regeneration by maintaining space for new bone growth through its macro - pores . 
 this preliminary study presents the efficacy of a preformed titanium mesh as a ready - to - use barrier membrane around peri - implant alveolar bone defect . 
 this preformed mesh is also convenient to apply and to remove .