Table 6.

A summary of included studies.

Author	Title	Year	Type of Study	Oral Manifestation/s	Number of Participants	Age Range of Participants	Intervention/Exposure	Comparator/Control	Vitamin	Outcomes of Interest	Main Results
Wu, Y.-H. et al. [33]	Hemoglobin, iron, vitamin B12, and folic acid deficiencies and hyperhomocysteinemia in Behcet’s disease patients with atrophic glossitis	2018	Cross-sectional study	Recurrent aphthous stomatitis (RAS), atrophic glossitis (AG)	30 AG + RAS/BD patients, 33 AG־RAS/BD patients, and 126 healthy control subjects	18–82	Measurement of blood hemoglobin, iron, vitamin B12, folic acid, and homocysteine concentrations	Healthy control subjects	B9, B12	Hemoglobin, iron, vitamin B12, and folic acid deficiencies	AG + RAS/BD patients had significantly higher frequencies of hemoglobin, iron, vitamin B12, and folic acid deficiencies than healthy control subjects. They also had significantly higher frequencies of hemoglobin and vitamin B12 deficiencies than AG־RAS/BD patients. AG־RAS/BD patients had significantly higher frequencies of hemoglobin and iron deficiencies than healthy control subjects
Bao, Z. et al. [29]	Lingual Linear Lesions: A Clinical Sign Strongly Suggestive of Severe Vitamin B12 Deficiency	2020	Retrospective study	Lingual linear lesion (LLL)	57 patients presenting with lingual linear lesions (LLLs)	18–80	Measurement of serum levels of vitamin B12, folate, ferritin, hemoglobin, and zinc	/	B12	Serum levels of vitamin B12, folate, ferritin, hemoglobin, and zinc	98.25% of patients had severe serum vitamin B12 deficiency. LLLs were associated with significantly lower mean levels of vitamin B12 and significantly higher mean MCV, rapid improvement after replacement therapy
Khayamzadeh, M. et al. [30]	Determining salivary and serum levels of iron, zinc and vitamin B12 in patients with geographic tongue	2019	Case–control study	Geographic tongue	20 patients with geographic tongue, 20 healthy individuals	19–49	Evaluation of iron, zinc, and vitamin B12 levels in blood and saliva	Healthy subjects without geographic tongue	B12	Salivary and serum levels of iron, zinc, and vitamin B12	Patients with geographic tongue had lower salivary zinc levels compared to the control group. No significant differences were found in serum levels of iron, zinc, and vitamin B12
Cui, J. et al. [25]	Clinical Evaluation and Therapeutic Effects of Combination Treatment withMecobalamin + Vitamin E in Recurrent Oral Ulcer	2022	Randomized controlled trial	Recurrent oral ulcer	58 patients with aphthous oral ulcers (29 in the experimental group, 29 in the control group)	45–50	Mecobalamin tablets + vitamin E	Fe complex enzyme gargle	B12	Pain level (VAS score), ulcer status and number, proinflammatory cytokine levels, quality of life (SF-36), mean intermission time, mean ulcer healing time, and total effectiveness rate	Longer total intermission time, shorter mean ulcer healing time, fewer total ulcers, lower pain scores in test group, improved QoL in test group, and lower proinflammatory cytokine levels in test group
Hugar, S. et al. [10]	Assessment of Vitamin B12 and Its Correlation with Dental Caries and Gingival Diseases in 10- to 14-year-old Children: A Cross-sectional Study	2017	Cross-sectional study	Dental caries and gingival disease	42 healthy children (21 boys, 21 girls)	10–14	Serum vitamin B12 levels	/	B12, E	Dental caries (DMFT score) and gingival diseases (PI, GI scores)	64% of children had vitamin B12 deficiency, higher DMFT scores in deficient children, negative correlation between vitamin B12 levels and dental caries, and gingival indices
Jankovskis, V. et al. [28]	Vitamin B and Zinc Supplements and Capsaicin Oral Rinse Treatment Options for Burning Mouth Syndrome	2021	Randomized controlled study	Burning mouth syndrome (BMS)	89 patients (BMS), 20 patients (capsaicin rinse)	Not provided Mean age: 59 ± 19 years	Vitamin B complex and zinc supplements; 0.02% topical capsaicin rinse	/	B12	Pain/burning levels (assessed via visual analog scale) and salivary flow	Both treatment methods showed statistically significant reductions in pain/burning levels and no significant changes in salivary flow
Munday, M.-R. et al. [13]	A Pilot Study Examining Vitamin C Levels in Periodontal Patients	2020	Cross-sectional study	Periodontal disease	20 patients with periodontitis	Not provided Mean age: 65 ± 9	Serum vitamin C and C-reactive protein (CRP)	/	C	Serum vitamin C levels, C-reactive protein (CRP) levels, periodontal disease stage, and dietary intake	6 out of 20 patients had vitamin C levels below the institutional normal range, low vitamin C was associated with higher periodontal disease stage, elevated CRP was found in 2/3 of individuals with low vitamin C, with a significant negative correlation between vitamin C and CRP, and vitamin C levels did not correlate with patient-reported fruit or vegetable consumption but were associated with high processed meat intake
Woelber, J. P. et al. [26]	The influence of an anti-inflammatory diet on gingivitis. A randomized controlled trial	2019	Randomized controlled trial	Gingivitis	30 participants (15 in the experimental group, 15 in the control group)	Not provided Mean age of experimental group: 27,3 ± 4,7 years Mean age of control group: 33,7 ± 1	Diet low in processed carbohydrates and animal proteins, rich in omega-3 fatty acids, vitamin C, vitamin D, antioxidants, plant nitrates, and fibers for 4 weeks. Both groups suspended inter-dental cleaning	No change in diet. Both groups suspended inter-dental cleaning	C, D	Gingival bleeding (GI), plaque index (PI), probing pocket depths, bleeding on pocket probing, periodontal inflamed surface areas (PISA), body mass index, weight, and subgingival microbiome composition	Experimental group showed significant reduction in gingival bleeding (GI), significant increase in vitamin D values, and significant weight loss. No significant differences in plaque values between groups. No significant differences in inflammatory serological parameters or subgingival microbiome composition between groups
Bahramian, A. et al. [34]	Comparing Serum and Salivary Levels of Vitamin D in Patients with Recurrent Aphthous Stomatitis and Healthy Individuals	2018	Cross-sectional study	Recurrent aphthous stomatitis (RAS)	26 RAS patients, 26 healthy individuals	18–60	Evaluation of serum and salivary vitamin D levels	Healthy Individuals	D	Serum and salivary levels of vitamin D	Serum vitamin D levels were significantly lower in patients with RAS compared to healthy individuals. Salivary vitamin D levels did not show a significant difference between patients with RAS and healthy individuals. A significant positive correlation was observed between serum and salivary levels of vitamin D in all participants
Kim, I.-J. et al. [35]	A cross-sectional study on the association between vitamin D levels and caries in the permanent dentition of Korean children	2018	Cross-sectional study	Dental caries	1688 children	10–12	Blood vitamin D [25(OH)D] concentrations	/	D	Association between 25(OH)D levels and dental caries	The group with 25(OH)D levels < 50 nmol/L had higher proportion of caries in permanent dentition and first molar, no significant correlation between 25(OH)D levels and caries when controlling for external factors, but significant correlation with first molar caries. Children with 25(OH)D levels < 50 nmol/L 1.295 times more likely to have first molar caries and negative correlation between 25(OH)D levels and DMFT
Gyll, J. et al. [36]	Vitamin D status and dental caries in healthy Swedish children	2018	Cross-sectional study	Dental caries	85 children	8	Vitamin D supplementation	/	D	Dental caries, enamel defects, saliva LL37 levels	Weak inverse association between vitamin D status at 6 years and caries 2 years later. Higher vitamin D levels correlated with being caries-free. Vitamin D status unrelated to enamel defects but positively associated with saliva LL37 levels
Balci Yuce, H. et al. [27]	Assessment of local and systemic 25-hydroxy-vitamin D, RANKL, OPG, and TNF levels in patients with rheumatoid arthritis and periodontitis	2017	Randomized controlled trial	Periodontal disease	17 RA + CP patients, 18 CP patients, 18 healthy controls	RA + CP patient: 37–61 CP patients: 36–65. Control group: 36–65	Nonsurgical periodontal treatment	Healthy individuals	D	Clinical periodontal parameters, GCF, and serum levels of vitamin D	GCF vitamin D levels were higher in RA +CP and CP groups than in healthy controls but decreased in the RA + CP group after periodontal treatment. Local vitamin D levels might be an important indicator of periodontal bone loss
Borsting, T. et al. [31]	Maternal vitamin D status in pregnancy and molar incisor hypomineralisation and hypomineralised second primary molars in the offspring at 7–9 years of age: a longitudinal study	2022	Longitudinal study	Molar incisor hypomineralization (MIH) and hypomineralized second primary molars (HSPM)	176 mother and child pairs	7–9	Maternal serum 25-hydroxyvitamin D levels	/	D	Molar incisor hypomineralization (MIH) and hypomineralized second primary molars (HSPM)	Insufficient maternal serum vitamin D at mid-pregnancy was associated with a higher number of affected teeth among the offspring with MIH at 7–9 years of age. Further prospective studies are needed to investigate whether this finding is replicable and to clarify the role of maternal vitamin D status during pregnancy and MIH, as well as HSPM, in children
Nuszkiewicz, J. et al. [37]	Parameters of Oxidative Stress, Vitamin D, Osteopontin, and Melatonin in Patients with Lip, Oral Cavity, and Pharyngeal Cancer	2021	Cross-sectional study	Lip, oral cavity, or pharyngeal cancer in situ	25 LOCP patients (YCG), 20 LOCP elderly patients (OCG), 25 healthy volunteers	Not provided Mean age of YCG: 58:24 ± 1:29. Mean age of OCG: 69:7 ± 1:49. Mean age of control group: 55:36 ± 1:17	Concentrations of vitamin D, osteopontin, melatonin, and malondialdehyde; activities of antioxidant enzymes	Healthy volunteers	D	Vitamin D deficiency and disturbed oxidant–antioxidant homeostasis observed in LOCP patients; association of osteopontin with LOCP carcinogenesis	Disruption of oxidant–antioxidant homeostasis in the lip, oral cavity, and pharyngeal cancer patients impaired antioxidant enzymatic defense, and increased lipid peroxidation, correlated with high levels of osteopontin, was determined in this type of cancer. However, vitamin D deficiency in the LOCP patients was found
Biedermann, J.S. et al. [32]	Predictors of oral cavity bleeding and clinical outcome after dental procedures in patients on vitamin K antagonists	2017	Cohort study	Periprocedural bleeding	1845 patients	64–81	VKA management strategies (continuation with tranexamic acid mouthwash, interruption with or without bridging)	/	K	Clinically relevant oral cavity bleeding, non-oral cavity bleeding, thromboembolic events, hospitalization, all-cause mortality within 30 days	Bridging therapy, antiplatelet therapy, and a supratherapeutic or unobjectified INR before the procedure were identified as strongest predictors of oral cavity bleeding. Different management strategies showed varying risks of oral cavity bleeding