Table 2. Summary of the main characteristics and results of the included studies.
| Author | Sample size and tooth type | Sample standardization | Groups | Evaluation method | Main results |
|---|---|---|---|---|---|
| Çapar et al. 2014 [34] | 50 mandibular premolars | Single root canals | Control | Fracture load 1 mm/min | There was no statistically significant difference between groups. |
| Straight roots | PTU (F4) with no filling | ||||
| Similar buccolingual and mesiodistal dimensions measured using an electronic caliper | PTU (F4) with filling | ||||
| SAF with no filling | |||||
| SAF with filling | |||||
| Çiçek et al. 2015 [35] | 72 mandibular premolars | Single root canals | PTU (F4) | Fracture load 1 mm/min | Statistically significant difference was found between PTN and MT. |
| Straight roots | PTN (X4) | ||||
| Similar buccolingual and mesiodistal dimensions measured using an electronic caliper | WO (40/0.08) | ||||
| TF (40/0.04) | |||||
| MT (40/0.06) | |||||
| RS (40/0.06) | |||||
| Control | |||||
| Zogheib et al. 2018 [36] | 60 maxillary premolars | Two separate roots | iRaCe® (30.04) | Fracture load 1 mm/min | No statistically significant difference was registered between groups. |
| Similar lengths and crown dimensions | iRaCe® (30.06) | ||||
| Krikeli et al. 2018 [37] | 58 maxillary canines | Single root canals | Hand File (40/0.02) | Fracture load 1 mm/min | Statistically significant difference was observed between MT (40/0.06) and control group. |
| Similar buccolingual and mesiodistal dimensions measured using an electronic caliper | MT (40/0.04) | ||||
| MT (40/0.06) | |||||
| Control | |||||
| Tian et al. 2019 [38] | 100 mandibular premolars | Single root canals | Control | Fracture load 0.5 mm/min | The values were significantly higher in 40/.05 and 45/.05 groups than 45/.15 group. |
| Similar lengths and degrees of canal curvatures (< 10º) | 40/0.05 | ||||
| Similar buccolingual and mesiodistal dimensions measured using an electronic caliper | 45/0.05 | ||||
| 50/0.05 | |||||
| 55/0.05 | |||||
| 60/0.05 | |||||
| 40/0.10 | |||||
| 40/0.15 | |||||
| 45/0.10 | |||||
| 45/0.15 | |||||
| Doğanay Yıldız et al. 2020 [39] | 84 mandibular incisors | Single root canals | K3XF (25/0.04) | Fracture load 1 mm/min | Significant differences were found between 25/0.04 and 25/0.08; 30/0.04 and 30/0.08; and 25/0.08 and 30/0.04. |
| Straight roots | K3XF (25/0.06) | ||||
| Similar buccolingual and mesiodistal dimensions measured using an electronic caliper | K3XF (25/0.08) | ||||
| K3XF (30/0.04) | |||||
| K3XF (30/0.06) | |||||
| K3XF (30/0.08) | |||||
| Control | |||||
| Augusto et al. 2020 [40] | 32 mandibular molars | Three roots and canals | Bassi Logic™ (40/0.03) with traditional cavity | Fracture load 1 mm/min | No significant differences were observed in fracture resistance values. |
| Similar lengths and degrees of canal curvatures (< 20º) | Bassi Logic™ (40/0.05) with traditional cavity | ||||
| Similar surface area, volume, and 3D configuration obtained by Micro CT | Bassi Logic™ (40/0.03) with ultraconservative cavity | ||||
| Bassi Logic™ (40/0.05) with ultraconservative cavity | |||||
| Lin et al. 2020 [41] | 80 mandibular premolars | Single root canals | Control | Fracture load 1 mm/min | Significant differences were found between files with .04 and .06 taper. |
| Type I canal configuration confirmed by CBCT | T-Pro (25/0.04) | ||||
| HyFlex CM (25/0.04) | |||||
| TG6 (25/0.06) | |||||
| ZenFlex (25/0.06) |
PTU, ProTaper Universal; PTN, ProTaper Next; WO, WaveOne; TF, Twisted File; MT, Mtwo; RS, Revo-S; CT, computed tomography; CBCT, cone-beam computed tomography.