**1. Introduction**

Satisfactory bone volume is the first condition for obtaining a predictable long-term prognosis in oral implantology. However, some patients may present inadequate bone, which frequently makes difficult the successful outcome of the correct implant placement. Different techniques have been developed to increase bone volume, but at the present time, guided bone regeneration (GBR) represents the gold standard in bone regeneration for implant placement [1,2]. The biological bases of this technique focus on the "PASS" principles: primary closure, angiogenesis, space maintenance, and blood clot stability [3], in other words, this technique focus on the mechanical protection of the blood clot and the isolating of the bone defect, by using a barrier, to facilitate the migration and proliferation of bone-forming cells and to prevent soft tissue colonization inside the bone defect [1,4]. In the last two decades, several membrane designs have been studied. They can be divided into two categories: absorbable and non-resorbable, with different physical and biomaterial properties between them, but all types must have some properties such as

**Citation:** Aceves-Argemí, R.; Roca-Millan, E.; González-Navarro, B.; Marí-Roig, A.; Velasco-Ortega, E.; López-López, J. Titanium Meshes in Guided Bone Regeneration: A Systematic Review. *Coatings* **2021**, *11*, 316. https://doi.org/10.3390/ coatings11030316

Academic Editor: Jun-Beom Park

Received: 21 February 2021 Accepted: 8 March 2021 Published: 10 March 2021

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biocompatibility, tissue integration, space-making, cell selectivity, tissue integration, and clinical manageability [5,6]. The physical and biomaterial properties of the membranes will influence the development of their function, as well as the result of the treatment, therefore, it will be of great importance to know the advantages and disadvantages of each of them [5,6].

The non-resorbable barriers are expanded and dense forms of titanium-reinforced polytetrafluoroethylene membranes (e-PTFE and d-PTFE), the titanium foils, and perforated titanium meshes (preshaped or customized) (Figure 1).

**Figure 1.** (**a**) Custom-made titanium mesh (AVINENT®® Digital Health); (**b**) Use of Computer-Aided Design (CAD) and Computer-Aided manufacturing (CAM)to design custom-made devices for guided bone regeneration (GBR).

The biggest disadvantage of these types of membranes is they need to be removed with a second-stage surgical procedure. Despite this, they offer several advantages such as, maintaining the space for a sufficient period of time, providing an effective barrier function in terms of biocompatibility, they are simple to manage and present a reduced risk of long-term complications [7].

In cases where vertical augmentation is desired, or in the presence of severe bone atrophy, the use of more resistant and stable membranes is required. To satisfy these requirements, the e-PTFE membranes were subjected to modifications such as titanium reinforcement that favoured their properties and predictability, or the use of screws in its fixation to improve stability [8]. Thus, the titanium mesh appeared to intend to obtain a balance between the ideal malleability and enough rigidity to accomplish reconstructions of wide bone defects [9].

In the last 8 years, only three reviews about this subject have been conducted [10–12], therefore, the main objective was to assess the use of titanium meshes during guided bone regeneration, the quantity of augmented bone, survival and success rates of implants, complications, and predictability of this surgical technique.
