## 4 Discussion
In addition, most of the studies used a single method of tooth proportion evaluation [14, 15, 16, 17, 20, 21, 23, 24, 25, 26, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68]. Out of which, 29 studies used 2D photograph analysis to investigate the occurrence of the GP between the perceived widths of the maxillary anterior teeth [14, 15, 17, 20, 21, 25, 26, 31, 32, 33, 34, 37, 40, 41, 42, 45, 46, 47, 48, 49, 50, 51, 56, 58, 59, 60, 63, 65, 68]. Followed by 10 studies which used dental cast analysis [16, 23, 24, 30, 43, 53, 54, 55, 56, 53, 52, 53, 54, 55, 56, 51]. All these studies might have flaws, including the volumetric changes in the impression or inaccuracies in the pouring of dental casts and positional differences or magnification errors that can occur during 2D photography. Only six studies considered direct clinical measurement of teeth [35, 36, 38, 39, 66, 67] as an assessment method. A few others (06) used both 2D photograph and dental cast analysis [18, 19, 22, 57, 62, 65]. Therefore, it is suggested that a combination of assessment methods with low error, including direct clinical measurements and digital scans, should be employed for the assessment of tooth proportions in future studies. Few studies reported GP to exist between the apparent widths of all anterior teeth on both sides, including [PERSON] et al. [16], where 63% of the population observed GP in all anterior teeth; however, this was a pilot study with a sample of 44 patients only. GP was also found in a small number of 4 other studies, including [PERSON] [23] (20.4%), [PERSON] [50] (19%), and 18.57% in studies by [PERSON] et al. [17] and [PERSON] et al. [32], respectively. They concluded that although GP was present in some participants, statistically reliable value explained in the form of a range would be more clinically applicable for dental practitioners to support the existing theories on aesthetic parameters. [PERSON] et al. [47] suggested that rather than emphasizing a single value such as GP of 62%, a range of dental proportion ratios should be proposed to achieve ideal aesthetics. The current systematic review proposes a range of dental proportions based on geographic location, which could be utilized to restore anterior teeth in different races and ethnicities. In addition, it is suggested that GP only existed between apparent widths of lateral and central incisors by [PERSON] et al. 35%, [PERSON] et al. 34%, [PERSON] et al. 25%, [PERSON] et al. 21.70%, [PERSON] et al. 21.25%, [PERSON] et al. 17%, and [PERSON] et al. 14.28%, respectively [14, 15, 18, 22, 37, 42, 45, 47, 48]. These studies found that the frequency of the golden proportion was quite low for La and Ca (\(\leq\)10%) [14, 15, 22, 37, 45, 48]. [PERSON] believed that when the golden proportion is used, the lateral incisor appears too narrow, and the resulting canine is not esthetic. He preferred using a 70% proportion [6]. Therefore, it was concluded that GP could be helpful to achieve aesthetic restorations of the maxillary central and lateral incisors, though it should not be considered as a decisive factor in determining dental attractiveness and other factors should be considered. Furthermore, variations in GP were also noted between the right and left sides of the arches [21, 24, 25]. [PERSON] et al. observed that 17.9% had left CI in GP to left LI, whereas 16.1% had right CI in GP to right LI. Whereas 25% had left LI in GP to left Ca and 14.3% had right LI in GP to right Ca [21]. Similar variations were noted by [PERSON] et al. and [PERSON] et al. [24; 25]. These differences can be due to misalignment, including rotation, spacing, overlapping, and other forms of malalignment of teeth. If the misalignment factors are absent or eliminated, then the apparent width is affected by the curvature of the arch form and the inter-arch tooth size relationships themselves.