# Reverse Guided Bone Regeneration (R-GBR) Digital Workflow for Atrophic Jaws Rehabilitation
## 4 Discussion  
The importance of soft tissues in conditioning a pre-implant reconstructive procedure was widely stated, protecting from infections and supplying nutrients and cells [16; 17; 18; 19; 20; 21]. The relationship between the soft and hard tissues and their features conditions the choice of a bone augmentation technical approach or, otherwise, renouncing to it and accepting a prosthetic compromise. The final prevision of the correct soft tissue profile with the prosthetic crowns can be particularly useful in managing complex alveolar defects with anatomic alterations and wrong occlusal interactions. Hence, the discussion between prosthodontists and patients allows for deciding the more suitable solution for each case. Screw-retained prostheses are today the fixed available solutions for partial dedentulous atrophies with aesthetic, functional and hygienic demands [22]. The fixed bridge, without false gingiva and directly connected to the fixtures, requires a precise evaluation of the final soft tissue profile, particularly in the aesthetic zone. The GBR technique is the most versatile approach, since the particulate graft, maintained by a scaffold, is adaptable to every defect shape. The use of titanium meshes enables the management of more critical defects with fewer infective complications than those with non-resorbable membranes, albeit a 0-68.9% of the reported exposure range [17; 18; 23]. Figure 9: The cross–section CBCT images relative to the second premolar (**A**), right lateral (**B**) and left central incisors (**C**) location in the second case after a month of healing. The literature reports 89.9% implant success up to three years of follow-up [2]. The digital manufacturing of the titanium mesh should have homogenized the final complications and implant success results. However, a considerable variation of reported outcomes poses a few questions. [PERSON] et al. and [PERSON] et al. recorded only 11 out of 53 and 1 out of 10 cases of dehiscences [4; 7], while [PERSON] et al. reported 66% post-operative exposure morbidity in nine patients [1]. Two authors reported 25% exposures, 16% minimal, 7% \"like one tooth width\" and 1.5% complete, without finding any correlation between these and the soft tissue management, thickness or mesh size [13]. [PERSON] et al. (2019), on 70 dis-homogeneous treated sites, reported 37% exposures [24]. [PERSON] et al. did not find a significant difference in mucosal dehiscence and infection between custom mesh and conventional [6]. The mean vertical bone gain reported by studies adopting linear measurements ranges from 3.9 mm [1] to 6.5 mm [25], with a maximum of 8.9 mm [4]. The width augmentation goes from 5.5 [25] to 6.35 [4] with a maximum of 11.5. These data were not compared with the virtually planned ones. Similar results were obtained with the no-digital technique, with a linear vertical augmentation mean range of 3.7-5.4 mm in combined defects [26]. Regarding the percentage of regenerated bone volume concerning the planned one, the values go from 65% [2] to 91.9% [4]. Such discrepancies can relate mainly to the different extension and morphology of the treated defects [12], often considered together in the same trial, or to the operators' experience in surgically managing the soft tissues, or, on the other hand, the precision and reliability of the digital systems and the confidence of the operator in using such a technology. Treating a homogeneous cohort of nineteen extended three-dimensional atrophies, [PERSON] et al. obtained five complete failures due to early infection and graft loss; nevertheless, once passed the first critical six weeks, the reliability of the technique in terms of osseous regeneration came to 88% [2]. The operator's surgical skill seems to maintain its importance, albeit, with the digital approach, a single expert surgeon obtained a lower exposure level (10-25%) [7; 13] than in the two trials with more operators (52.3-66%) [1; 2].