## 4 Discussion  
The results of this retrospective study provide clinically useful information on postoperative complications occurring after peri-implant reconstructive therapy. Postoperative soft tissue dehikences were the most frequent complication affecting 57.1% (95%CI = 27% to 87%) of patients and 52.4% (95%CI = 29% to 76%) of implants. Several reports are in line with these results, showing that wound dehikences are common and can occur in approximately half of cases [35; 36; 41]. This complication might have an important impact on treatment outcomes, especially when membranes are used. Indeed, the scientific literature has shown that early membrane exposure can significantly compromise the regenerative outcome and increase the risk of secondary complications [42]. In the present report, membrane exposure was found in 19.1% of cases and showed a clear correlation with the presence of dehikences (\(p\) = 0.034). Peri-implant surgery seems to have a higher risk of would dehiscence in comparison with other procedures such a ridge augmentation (16.9%) and regenerative periodontal surgery (15%) [43; 44]. This might be partially explained by the defect anatomy, since peri-implant defects usually have a supracrestal component [20; 21] that hampers wound closure. The dimension of the dehikence is an important variable to consider since it provides objective data on the magnitude of this complication. In the present study, dehikences had a mean length of 7.6 mm (SD = 2.0) and affected 21.4% of the total incision length. Previous authors have reported similar data, with mean lengths ranging from 4 to 7 mm, typically accounting for 15% to 25% of the total incision length [45; 46]. It is notable that, despite the high frequency of dehikences, no cases of postoperative infections were found. The absence of suppuration or infectious signs/symptoms might be related to the applied antibacterial postoperative protocols (prophylactic antibiotic administration, use of postoperative chlorhexidine mouthrinses, and mechanical cleaning of the wound with a soft toothbrush). These measures seemed to be sufficient, even though 57.1% of patients had visible biofilm in the surgical wound area. Although the association between the presence of biofilm and dehiscence did not reach statistical significance (\(p\) = 0.130), [PERSON] et al. [47] emphasize that effective plaque control is critical during the initial weeks of healing and should be considered a key factor for successful regeneration. Complications occurred in both surgical techniques. Regenerative approaches had a dehikence rate of 50%, while combined approaches seemed to be more prone to this complication (60% of patients). The reported rates seem to vary considerably. While a recently published clinical trial observed that only 19% of implants with a regenerative \begin{table}
\begin{tabular}{l c c c c c} \hline \hline \multicolumn{2}{c}{**Type of Surgery**} & \multicolumn{2}{c}{**Incision**} & \multicolumn{2}{c}{**Dehiscence**} \\ \hline  & **N (\%)** & \
\begin{tabular}{c} **(mm)** \\ **Mean (SD)** \\ \end{tabular} & **N (\%)** &
\begin{tabular}{c} **(mm)** \\ **Mean (SD)** \\ \end{tabular} & **(\%)** \\ \hline Combined & 13 (61.9) & 18.7 (5.1) & 8 (61.5) & 7.9 (2.2) & 25.7 (22.5) \\ \hline Regenerative & 8 (38.1) & 15.9 (5.2) & 3 (37.5) & 6.8 (0.5) & 14.5 (21.9) \\ \hline \(p\)-value & & 0.237 & & 0.220 & 0.274 \\ \hline Total & 21 (100) & 17.7 (5.2) & 11 (52.4) & 7.6 (2.0) & 21.4 (22.4) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Number, percentage, and millimeters of dehiscence according to the type of surgery. N = number; SD = standard deviation. submerged approach had dehiscences [35], [PERSON] et al. found a much higher figure (62.5% of implants) after 2 weeks of healing using the same technique [48]. Factors that may influence the appearance of wound dehiscence may include flap tension [49], periosteal release incisions [50], use of membrane [40; 51; 52], suturing technique [53], or submerged or non-submerged healing [54].