Table 1.
Assessment of risk of bias
| Article | Structured summary in the abstract | Calculation of sample size | Obvious description of sample preparation methods | Randomization | Adherence to the manufacturer’s recommendation for sintering | Optical methods clearly described | Optical outcomes clearly reported | Total | Risk of bias |
|---|---|---|---|---|---|---|---|---|---|
| Salah et al. 2023 [39] | 0 | 1 | 0 | 2 | 1 | 0 | 0 | 3 | low |
| Yousry 2023 [40] | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 2 | low |
| Savas and Akin 2022 [41] | 0 | 0 | 0 | 2 | 1 | 0 | 0 | 3 | low |
| Liu 2022 et al. [42] | 0 | 0 | 0 | 2 | 1 | 0 | 2 | 5 | medium |
| Liu 2022 et al. [43] | 0 | 0 | 0 | 2 | 1 | 0 | 2 | 5 | medium |
| Vafaei et al. 2022 [44] | 0 | 1 | 0 | 2 | 1 | 0 | 0 | 4 | low |
| Park et al. 2022 [45] | 0 | 2 | 0 | 2 | 1 | 0 | 0 | 5 | medium |
| Kongkiatkamon and peampring 2022 [46] | 0 | 1 | 0 | 0 | 2 | 0 | 0 | 3 | low |
| Mourouzis and Tolidis 2022 [47] | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | low |
| Kanpalta, Burduroglu and Kara 2022 [48] | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | low |
| Jerman et al. 2021 [49] | 1 | 2 | 1 | 2 | 0 | 0 | 1 | 7 | medium |
| Lümkemann and Stawarczyk 2021 [50] | 1 | 2 | 0 | 2 | 0 | 1 | 1 | 7 | medium |
| Reyes et al. 2021 [51] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Pekkan 2021 [52] | 1 | 2 | 1 | 2 | 0 | 0 | 0 | 5 | medium |
| Luz et al. 2021 [38] | 1 | 2 | 1 | 2 | 1 | 1 | 2 | 10 | high |
| Yang et al. 2020 [53] | 1 | 2 | 1 | 2 | 0 | 0 | 2 | 8 | medium |
| Cardoso et al. 2020 [54] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Cho et al. 2020 [55] | 0 | 2 | 0 | 2 | 1 | 0 | 0 | 5 | medium |
| Cokic et al. 2020 [56] | 0 | 2 | 0 | 2 | 1 | 0 | 2 | 7 | medium |
| Kim 2020 [57] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Sanal and Kilinc 2020 [58] | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 2 | low |
| Lawson and Maharishi 2020 [59] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Aljanobi and Al-Sowygh 2020 [60] | 1 | 2 | 1 | 2 | 0 | 0 | 2 | 8 | medium |
| Zhang et al. 2019 [61] | 1 | 1 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Walczak et al. 2019 [62] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Alshamrani and Souza 2019 [63] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Elsaka 2019 [64] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Li et al.2019 [65] | 0 | 2 | 1 | 2 | 1 | 0 | 2 | 8 | medium |
| Jansen et al. 2019 [66] | 0 | 2 | 1 | 2 | 0 | 0 | 2 | 7 | medium |
| Juntavee and Attashu 2018 [67] | 0 | 2 | 0 | 0 | 0 | 0 | 1 | 3 | low |
| Yan et al. 2018 [68] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Liebermann et al. 2018 [69] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Inokoshi et al. 2018 [70] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Sen et al. 2018 [71] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Mao et al. 2018 [37] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Kwon et al. 2018 [72] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Zadeh et al. 2018 [73] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Alghazzawi 2017 [74] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Kim and Kim 2017 [75] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Carrabba et al. 2017 [76] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Stawarczyk et al. 2016 [77] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Kim and Kim 2016 [78] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Vichi et al. 2016 [79] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Abdelbary et al. 2016 [80] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Harada et al. 2016 [81] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Tuncel et al. 2016 [21] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Sulaiman et al.2015 [82] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Kurtulmus and Ulusoy 2014 [83] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Stawarczyk et al. 2014 [84] | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 4 | low |
| Ebeid et al. 2014 [85] | 0 | 2 | 2 | 2 | 0 | 0 | 0 | 6 | medium |
| Kanchanavasita et al. 2014 [86] | 1 | 2 | 1 | 2 | 0 | 0 | 0 | 5 | medium |
| Stawarczyk et al. 2013 [87] | 0 | 2 | 2 | 2 | 0 | 0 | 0 | 6 | medium |
| Kim et al. 2013 [88] | 0 | 2 | 2 | 2 | 0 | 0 | 0 | 6 | medium |
| Jiang et al. 2011 [89] | 0 | 2 | 2 | 2 | 0 | 0 | 0 | 6 | medium |