Table 2.

Summary of the included studies

Study ID	Authors	Population	n	Age Range	Tooth Sample
1	Yang et al. 2006 33	Belgian	19	23–70	U1, U2, U3, L1, L2, L3, L4
2	Wu et al. 2016 34	Chinese	420	15–84	U1
3	Nemsi et al. 2017 35	Tunisian	120	22–67	U3, U5
4	Helmy et al. 2020 17	Egyptian	187	21–50	U7 L7
5	Rai et al. 2016 36	Indian	60	20–85	U3
6	Pinchi et al. 2015 2	Italian	148	10–80	21
7	Elgazzar et al. 2020 37	Egyptian	200	15–60	U3 L3
8	Yang et al. 2020 38	Chinese	230	8,18–19,92	21 23
9	Biuki et al. 2017 39	Iranian	122	13–70	U1 U2 U3 L1 L2 L3
10	Ceena Denny et al. 2021 40	Indian	100	-	U6 U7 L6 L7
11	Salemi et al. 2020 41	Iranian	300	14–60	13
12	Molina et al. 2021 42	Spanish	107	14–70	U1 U2 U3 L1 L2 L3 L4 L5
13	Penaloza et al. 2016 43	Malaysian	101	15–75	U1 U2 U5 L2 L3 L4
14	Koh et al. 2017 44	Malaysian	284	Above 20	L4
15	Asif et al. 2019a 45	Malaysian	73	15–23	L8
16	Al-Omoush et al. 2020 46	Jordanian	135	18–63	U8
17	Archana et al. 2018 9	Indian	100	12 - Above 18	U8 L8
18	Doni et al. 2021 47	-	160	20–70	L5 L6
19	Gulsahi et al. 2018 48	Turkish	204	Above 15	U1 U2 U3 L3 L4 L5
20	Haghanifar et al. 2019 49	Iranian	377	20–69	U1 U3 L1 L3
21	Andrade et al. 2019 50	Brazilian	116	13–70	U1 U3
22	Farhadian et al. 2019 51	Iranian	300	14–60	U3
23	Kazmi et al. 2019 52	Pakistan	717	15–65	23 33
24	Asif et al. 2019b 53	Malaysian	300	16–65	U3 11
25	Kazmi et al. 2021 12	Pakistan	717	15–65	23 33
26	Star et al. 2011 54	Belgian	111	10–65	U1 U2 U3 U4 U5 L1 L2 L3 L4 L5
27	Alsoleihat et al. 2017 55	Jordanian	155	18–58	L8
28	De Angelis et al. 2015 56	Italian	91	15–85	13
29	Adisen et al. 2018 57	Turkish	131	17–75	U3
30	Zhan et al. 2020 58	Chinese	392	16–76	21 22 23
31	Asif et al. 2018 59	Malaysian	110	16–65	U1
32	Zhang et al. 2019 60	Chinese	414	20–65	L8
33	Oscandar et al. 2018 61	Indonesian	180	6–50	L6
34	Porto et al. 2015 62	Brazilian	72	22–70	U1
35	Asif et al. 2020 15	Malaysian	191	7–14	U3
36	Różyło-Kalinowska et al. 2020 63	Polish	121	5–13	31 32 33 34 35 36 37
37	Ugur Aydin et al. 2019 64	Turkish	120	14–75	U1
38	Lee et al. 2017 65	South Korean	224	20–77	13
39	Buchanan 2019 66	Hispanic	250	8.5–20.7	Left or Right Region

L, Lower; U, Upper.

Number notation in Tooth Sample follows the Federation Dentaire Internationale (FDI) numbering.