## 3 Results
### Types of Treatment
#### 3.3.2 Regenerative Procedures for Implant Site Development  
For implant site development, different regenerative procedures were used: four studies [15; 17; 19; 20] performed a guided bone regeneration (GBR), in particular, two studies [15; 19] used a one-stage GBR (implant placement and simultaneous bone regeneration), one study [20] used a two-stage GBR (bone regeneration and delayed implant placement in the regenerated bone) and another study [17] divided the patients in two groups and used both types of GBR, one-stage GBR in one group and two-stage GBR in the other one; three studies [16; 18; 25] performed a bone graft procedure, in particular, one study [18] used an allogeneic block graft, whereas the other two studies [16; 25] used autogenous bone grafts from an intra-oral site; finally two studies [24; 27] performed an alveolar distraction osteogenesis (Table 3). All studies gave information about the materials used for the regenerative procedures: for GBR procedures, one study [15] used a deproteinized bovine bone mineral (Bio-Oss), one study [17] used a freeze-dried mineralized bone allograft, and the other two studies [19; 20] used demineralized freeze-dried bone particles (Dembone); for bone grafting, one study [18] used a Puros block allograft rehydrated with platelet-rich plasma and additional Puros particulate mineralized bone graft material, and the other two studies used autogenous bone grafts from symphysis [25] and from retromolar area [16]; and the studies [24; 27] performing alveolar distraction osteogenesis used the same type of distraction device (Modus distractor, Medartis). All studies performing GBR or bone graft procedures used barrier membranes: three studies [15; 16; 18] used resorbable membranes and the other four studies [17; 19; 20; 25] used non-resorbable membranes. Regarding the timing of implant placement, two studies [15; 19] performed a regenerative procedure with simultaneous implant placement, two studies [17; 25] performed a regenerative procedure with simultaneous or delayed implant placement, depending on each patient's clinical condition, and five studies [16; 18; 20; 24; 27] performed a regenerative procedure with delayed implant placement in the regenerated bone. All studies except two [16; 20] gave details about the type of implants used. The follow-up period ranged from a minimum of 6 months [15] to a maximum of 3 years [16; 24; 25], depending on each study. All studies reported good outcomes, with an enhancement of hard tissue, but none of them gave quantitative data about the amount of regenerated bone. Regarding soft tissue changes, no study reported data, except one [24], using an alveolar distraction osteogenesis procedure which referred to a simultaneous lengthening of soft tissues surrounding the distracted bone segment. Only three studies [17; 24; 25] indicated the implant survival rate (100%, 97.3% and 97.1%, respectively). Only three studies [20; 24; 25] reported complications: one study [24] using alveolar distraction osteogenesis referred to a lingual inclination of the distracted bone segment occurred during distraction in one patient and a post-operative infection in another patient; one study [20] using a GBR technique reported an early exposure of the e-PTFE membrane; finally, one study [25] using an only bone graft from the mandibular symbiosis reported four cases of paresthesia at the donor site immediately following the graft surgery. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline
**Author** & **Patient Age** & **Sex Tested Tech Tech** & **Type of Defect Treatment** & **Type of Defect Treatment** & **Materials** & **Type of Membranes** & **Follow-Up** & **Hard Tisser Changes** & **Soft Tisser Changes** & **Compplications** & **Impleant Survival Rate** \\ \hline \multirow{4}{*}{[PERSON] et al.