## 4 Discussion  
Although SABG performed with autogenous bone is the elementary part of the surgical protocol in the majority of centers all over the world because of its efficiency, this study aimed to evaluate the efficiency of the method which eliminates donor site necessity. We compared the outcomes, such as complication rate and bone volume formation, of SABG and EGPP performed at the mixed dentition stage. ABG as a standard procedure in alveolar cleft is generally classified into primary and secondary. Secondary ABG is usually performed in 9- to 11-year-old patients, in which cancellous bone is harvested from the iliac crest and grafted into the alveolar cleft before canine teeth eruption [10]. The surgical timing of our patients was also at mixed dentition age. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Canine Status** & **Impaction** & **Eruption** & & \\ \hline  & & & Total & \(p\) Value \\ SABG & 1 & 18 & 19 & \\ EGPP & 1 & 24 & 25 & \\  & 2 & 42 & 44 & 0.84 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Canine eruption. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Type** & **I** & **II** & **III** & **IV** & \\ \hline  & & & & Total & \(p\) Value \\ SABG & 16 & 2 & 0 & 1 & 19 & \\ EGPP & 21 & 3 & 0 & 1 & 25 & \\  & 37 & 5 & 0 & 2 & 44 & 0.549 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Bergland scale score. ABG is undoubtedly recognized as an effective method to promote more bony stock for the maxillary teeth. Nonetheless, the most discussed drawback of ABG is its permanent scar and donor site morbidity. According to [PERSON] et al., patients complained of pain after bone graft harvesting, which usually reached a pain score of 7.3/10, in the open harvest group. The pain of donor site was worse than pain associated with cleft reconstruction intraorally. It also prolongs the hospital length of stay [11]. The other reported complications are hematoma, revision surgery for bleeding, infection, delayed wound healing, and sensory disturbances of the lateral femoral cutaneous nerve [12]. Given the complications of ABG, surgeons are searching for alternative methods to replace or enhance autogenous bone graft. Periosteoplasty was first described as a \"boneless bone grafting\" by [PERSON] in 1967 [13]. It is performed to remove the soft tissue barrier in the cleft and create a mucoperiosteal tunnel, which can restore the continuity of the attached gingiva, maintaining the space for bone regeneration. [PERSON] recommends performing periosteoplasty in infancy, and good bone formation of the alveolar cleft was noted in 47% of patients [14]. Some centers perform primary GPP with a high successful rate [15]. In 2012, [PERSON] et al. reported 68.2% successful bone formation rate in primary GPP in patients aged 3 months [16]. Compared with delayed periosteoplasty, which is performed between infancy and before 7 years of age, good bone formation was found in 80% of patients [14]. As for early secondary gingvaalveolaroplasty, [PERSON] reported that 71.7% of patients developed type I alveolar bridging by modified Bergland scale score [17]. Although primary GPP has fair results in bone regeneration, it was found to affect the sagittal growth of the maxilla at 5 years of age [4]. Early secondary gingvaalveolaroplasty also appeared to have an inhibiting effect on maxillary growth that may increase the need for further orthognathic surgery [18]. According to [PERSON] et al., not only GPP but also ABG surgery, regardless of the timing of surgery, can cause vertical and horizontal maxillary growth restriction [19]. Compared with the late surgery group, the early ABG group presented more severe growth disturbance in both the sagittal and vertical directions [20]. These results indicate that facial growth disturbance relates to early alveolar surgery, explaining the fact that both GPP and ABG affect the vertical height of the maxilla. Considering the benefit of tooth eruption, the current trend is to perform surgery at the age of mixed dentition [9; 21; 22; 23].