Table 1.

Summary of the included studies

	Subjects; n	Study design; outcome measure	Intervention	Comparative	Assessment method	Results
Birkhed et al. (1979); Malmö, Sweden	19–58-yr-old adults, n = 110	Doubleblind, randomized, controlled study (3 mo); plaque amount (pom)	XYL lozenges (50%, 4 g/d, 4xd)	SOR, MAL, Lycasin lozenges (50%, 4 g/d, 4xd)	Fresh weight NOH 2 d	No decreases in the amount of plaque in any of the groups
Söderling et al. (1989); Ann Arbor, USA	19–35-old adults, n = 28	Blinded*, randomized*, controlled study (2 wk); plaque amount (pom)	XYL gum (76%, 11 g/d, 5xd), XYL-SOR gum (59% XYL, 17% SOR, 11 g/d, 5xd)	SOR gum (76%, 11 g/d, 5xd)	Fresh weight NOH 2 d CT not reported	Plaque decreased in the XYL and XYL-SOR groups, an increase in the SOR group (p < 0.05)
Steinberg et al. (1992); New York, USA	Adults, n = 28	Doubleblind, randomized, controlled cross-over study (6 wk); plaque amount (pom)	XYL gum (1.8 g/stick*, 9 g/d*, 5xd)	SOR gum (1.8 g/stick, 9 g/d, 5xd), no gum	Quigley-Hein PI NOH 0.5 d CT 5 × 10 min	The XYL (p < 0.001) and SOR (p < 0.05) gums decreased plaque compared to the baseline and no gum group
Cronin et al. (1994a); New Jersey, USA	> 18-yr-old adults, n = 59	Blinded, randomized, controlled study (2 wk); plaque amount (pom)	XYL-SOR gum (0.8 g XYL, 0.2 g SOR/piece, 8 g XYL/d, 5xd)	SOR gum (5xd)	Fresh weight NOH 2.5 d CT not reported	Plaque regrowth was reduced more by the XYL-SOR gum compared to the SOR gum (p < 0.05)
Cronin et al. (1994b); New Jersey, USA	> 18-yr-old adults, n = 154	Doubleblind, randomized, controlled trial (2 wk); plaque amount (pom)	XYL-SOR gum (0.8 g XYL, 0.2 g SOR/piece, 4.6–8 g/d, 3xd, 4xd, 5xd)	SOR gum (5xd)	Fresh weight NOH 2.5 d CT not reported	Plaque regrowth was reduced more by XYL-SOR gum compared to SOR gum (p < 0.05)
Cronin et al. (1994c); New Jersey, USA	> 18-yr-old adults, n = 142	Doubleblind, randomized, controlled study (2 wk); plaque amount (pom)	XYL pellet gum (850 mg/piece, 8.5 g/d, 5xd), XYL stick gum (850 mg/stick, 4.3 g/d, 5xd)	SOR gum (5xd)	Fresh weight NOH 2.5 d CT not reported	Plaque regrowth was reduced more by the XYL gums compared to the SOR gum (p < 0.01)
Merikallio et al. (1995); Pori, Finland	19–29-yr-old adults, n = 50 (MS > log 5)	Blinded*, randomized*, controlled study (2 wk); plaque amount (pom)	XYL gum (65%, 5.5–10 g/d, 3–5xd), XYL tablet (1.1 g, 3.3–5.5 g/d, 3–5xd)	No product	Fresh weight NOH 2 d CT not reported	No change in the amount of plaque in any of the groups
Tellefsen et al. (1996); Loma Linda, USA	21–35-yr-old adults, n = 14	Doubleblind, randomized, controlled cross-over study (6 d); plaque amount (pom)	XYL gum (0.8 g/piece, 4 g/d, 3xd)	SOR gum (1 g/piece, 5 g/d, 3xd)	Quigley-Hein PI NOH 6 d CT 3 × 20 min	XYL gum reduced plaque regrowth more than SOR gum (p < 0.01)
Söderling et al. (1997); Turku, Finland	23–25-yr-old adults, n = 37 (MS ≥ log 5)	Doubleblind, randomized*, controlled study (2 wk); plaque amount (pom)	XYL gum (65%, 6–10 g/d, 3–5xd), XYL-SOR gum (37.5% XYL, 37.5% SOR, 6–10 g/d, 3–5xd)	Gum base	Fresh weight NOH 2 d CT 3–5 × 3 min	XYL (p < 0.01) and XYL-SOR (p < 0.05) gums decreased plaque. No change in the gum base group
Mäkinen et al. (2005); Daegu, Korea	5-yr-old children, n = 149	Doubleblind, randomized, controlled trial (6 mo); plaque amount (pom)	XYL gum (80%, 4.5–5 g/d, 5xd)	SOR gum (73%, 4.5–5 g/d, 5xd), no gum	Quigley-Hein PI NOH not reported CT 4 × 5 min	XYL gum decreased plaque (p < 0.05), no change in the SOR gum group. Results for no gum not reported
Holgerson et al. (2007); Sävar, Sweden	7–12-yr-old children, n = 128	Doubleblind, randomized, controlled study (4 wk); plaque amount (pom)	XYL gum (77%, 6.2 g/d, 3xd)	SOR-MAL gum (SOR 64%, MAL 5%, 4.4 g/d, 3xd)	Simplified oral debris index NOH not reported CT 3 × 10 min	XYL and SOR/MAL gums decreased plaque compared to baseline (p < 0.05)
Al-Haboubi et al. (2012); London, UK	≥ 60-yr-old adults, n = 186	Doubleblind, randomized, controlled study (6 mo); plaque amount (som)	XYL gum (66%, 2.8 g/d, 2xd)	No gum	Silness-Löe PI NOH not reported CT 2 × 15 min	XYL gum decreased plaque (p < 0.001), no change in the no gum group
Runnel et al. (2013); Tartu, Estonia	7–8-year-old children, n = 485	Doubleblind, randomized, controlled trial (3 yr); plaque amount (som)	Xylitol candies (90%, daily dose appr. 7.5 g/d, 3xd)	SOR, ERY candies (90%, daily dose appr. 7.5 g, 3xd)	Fresh weight NOH 0.5 d	ERY candies decreased plaque (p < 0.05), no change in the XYL and SOR groups
Thabuis et al. (2013); YiXing, China	13–15-year-old children, n = 288	Doubleblind, randomized, controlled study (30 d); plaque amount (som)	XYL gum (59%, 10 g/d, 5xd)	MAL gum (59%, 10 g/d, 5xd), gum base, no gum	Quigley-Hein PI NOH 2 d CT 5 × 10 min	XYL and MAL gums decreased plaque compared to no gum (p < 0.05). Results for gum base not reported
Keukenmeester et al., (2015); Amsterdam, the Netherlands	> 18-yr-old adults, n = 303 (moderate gingivitis)	Doubleblind, randomized, controlled study (3 wk); plaque amount (som)	XYL gum (64%*, 9 g/day*, 5xd)	MAL gum (64%*, 9 g/day*, 5xd), gum base, no gum	Quigley-Hein PI NOH 0.5 d CT 5 × 10 min	XYL, MAL gums (p < 0.001) and gum base (p < 0.01) decreased plaque in brushed upper jaw. No changes in the no gum group or nonbrushed lower jaw
Akgül et al. (2020); Istanbul, Turkey	18–29-yr-old* adults, n = 154	Blinded, randomized, controlled study (3 wk); plaque amount (som)	XYL gum (5.4 g/d, 3xd)	Gum base*	Silness-Löe PI NOH not reported CT 3 × 10 min	XYL gum decreased plaque (p < 0.05), no change in the gum base group

XYL, xylitol; SOR, sorbitol; MAL, maltitol; ERY, erythritol; PI, plaque index; MS, mutans streptococci; wk, weeks; yr, years; mo, months; d, days; min, minutes; pom, primary outcome measure; som, secondary outcome measure; NOH, no oral hygiene; CT, recommended gum chewing time; *details on the study obtained from the authors