Table 4.

Top 20 keywords in scaffold materials for applying in periodontal diseases

Rank	Count	Centrality	Year	Keywords
1	139	0.08	2009	scaffolds
2	79	0.11	2005	In vitro
3	79	0.10	2010	Tissue engineering
4	71	0.06	2009	Stem cells
5	68	0.07	2011	Bone regeneration
6	62	0.07	2006	Periodontal regeneration
7	61	0.03	2006	regeneration
8	56	0.07	2007	Mesenchymal stem cells
9	55	0.08	2007	Osteogenic differentiation
10	54	0.09	2011	differentiation
11	43	0.06	2014	delivery
12	40	0.06	2007	Tissue regeneration
13	39	0.05	2009	bone
14	37	0.01	2017	scaffold
15	37	0.08	2005	tissue
16	35	0.01	2005	Guided tissue regeneration
17	32	0.02	2014	nanoparticles
18	31	0.06	2011	Drug delivery
19	28	0.04	2009	chitosan
20	25	0.03	2018	membranes

Abbreviations: Centrality refers to betweenness centrality in the keyword co-occurrence network; higher values indicate a stronger bridging role