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Each row is one question a systematic review asked: who, what, compared with what, and which outcome, with the effect it found and how certain that is. Words match anywhere in the field.
1,325 questions in 34 reviews · Oral medicine and oral cancer
current versionsNo studies 164 · 12.4%Ungraded 841 · 63.5%Very low 209 · 15.8%Low 72 · 5.4%Moderate 38 · 2.9%High 1 · 0.1%
Ungraded means an effect was reported without a GRADE rating; it is not a gap. No studies means the review found nothing to answer the question. The six categories are a display order, not a score.
| Question | Effect | Evidence | Status / GRADE |
|---|---|---|---|
Gum chewing (sugar-free) vs No gum chewing (control) Self-reported thirst · Elderly (>60 years) and medically compromised adults with xerostomia / dry mouth · Various (preoperative period to 3 + 1 months) The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised… (2023) | Narrative vote-count: of 7 studies measuring thirst, 6 found gum chewing reduced thirst [16,20,21,26,27,31] and 1 detected no effect [29]. | 7 studies | Ungraded |
Sentinel node biopsy (neck dissection only if biopsy positive) vs Elective neck dissection Locoregional recurrence · Adults with oral cavity or oropharyngeal cancer · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 1.04 [0.91, 1.19] | 1 study · 279 participants | Low |
PET-CT following chemoradiotherapy (neck dissection only if no/incomplete response) vs Planned neck dissection before or after chemoradiotherapy Recurrence · Adults with oral cavity or oropharyngeal cancer with nodal disease (stage N2 or N3) Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Recurrence: outcome not reported in a usable way (Mehanna 2017: nodal recurrence 3 vs 1; distant metastases 21 vs 23). | 1 study | Ungraded |
Gum chewing (sugar-free) vs No gum chewing (control) Salivary flow rate, stimulated and/or unstimulated (narrative synthesis) · Elderly (>60 years) and medically compromised adults with xerostomia / dry mouth · Various (single session to 12 months) The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised… (2023) | Narrative vote-count: of 19 studies measuring stimulated and/or unstimulated saliva flow rate, 9 found a positive effect of gum chewing [17,18,22,24,27,35,36,38,39] and 10 detected no effect… | 19 studies | Ungraded |
Supraomohyoid neck dissection vs Modified radical neck dissection Locoregional recurrence · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Locoregional recurrence: reported but not usable (variable follow-up) (Guo 2014). | 1 study | Ungraded |
Surgery vs Radiotherapy alone Total mortality · Adults with oropharyngeal cancer · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 0.83 [0.09, 7.46] | 1 study · 68 participants | Low |
Clear aligners (CA) vs Conventional fixed orthodontic appliances (CF) Plaque accumulation (Plaque Index) · Orthodontic patients undergoing comprehensive treatment (late mixed or permanent dentition, no active caries) · Range 1 to 12 months (maximum time-point per study), Study design: non-randomized studies of interventions White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared… (2023) | SMD -1.46 [-2.77, -0.15] | 5 studies · 246 participants | Moderate |
Elective neck dissection (at time of primary tumour resection) vs Therapeutic (delayed) neck dissection Recurrence · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | RR 0.58 [0.48, 0.70] | 3 studies · 633 participants | Moderate |
Elective radical (comprehensive) neck dissection vs Elective selective neck dissection Locoregional recurrence · Adults with oral cavity cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Locoregional recurrence: not reported. | 0 studies | No studies |
Gum chewing (sugar-free) vs Within-subject before/after comparison of soft gum vs hard gum (no no-gum control) Oral mucosal moisture · Elderly (>60 years) and medically compromised adults with xerostomia / dry mouth · 2-week chewing period (soft then hard gum, with 2-week wash-out) The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised… (2023) | Single study [22] (Nakagawa 2017): chewing hard gum significantly increased oral mucosal moisture whereas chewing soft gum did not. | 1 study · 12 participants | Ungraded |
Surgery vs Radiotherapy alone Locoregional recurrence · Adults with oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Locoregional recurrence: not reported. | 0 studies | No studies |
Surgery plus radiotherapy vs Radiotherapy alone Recurrence · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Recurrence: not reported. | 0 studies | No studies |
Clear aligners (CA) vs Conventional fixed orthodontic appliances (CF) Severity of white spot lesions (surface area and depth) · Orthodontic patients undergoing comprehensive treatment (late mixed or permanent dentition, no active caries) · Baseline to end of treatment (varying) White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared… (2023) | Not meta-analyzed. 2 RCTs assessed WSL severity by lesion surface area (Albhaisi 2020 [12]; Alshatti 2017 [31]) and 1 (Albhaisi 2020 [12]) also by lesion depth; reported narratively with differing methods, generally… | 2 studies | Ungraded |
Surgery plus adjuvant radiotherapy vs Chemotherapy (chemoradiotherapy) Total mortality · Adults with oral cavity or oropharyngeal cancer · oral cavity Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Total mortality: study reported survival significantly better with surgery and RT vs chemoradiotherapy, but no useable data; 32 participants (1 RCT, Iyer 2015 oral cavity subgroup). | 1 study · 32 participants | Very low |
Superselective neck dissection vs Selective neck dissection Disease-free survival (new disease, progression, and mortality) · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes · 36 months Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Disease-free survival: Pandey 2018 reported 83% (superselective) vs 91% (selective) at median 36 months, not significant (P=0.69); unable to analyse (variable follow-up); 32 participants (1 RCT). | 1 study · 32 participants | Very low |
Sentinel node biopsy (neck dissection only if biopsy positive) vs Elective neck dissection Adverse events associated with treatment · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Adverse events: no adverse events were reported (Garrel 2020). | 1 study · 279 participants | Very low |
PET-CT following chemoradiotherapy (neck dissection only if no/incomplete response) vs Planned neck dissection before or after chemoradiotherapy Total mortality · Adults with oral cavity or oropharyngeal cancer with nodal disease (stage N2 or N3) · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 0.92 [0.65, 1.31] | 1 study · 564 participants | Moderate |
Elective radical (comprehensive) neck dissection vs Elective selective neck dissection Adverse events associated with treatment · Adults with oral cavity cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Adverse events (BHNCSG 1998): flap necrosis, wound infection, fistula, vascular rupture, haematoma, seroma, chyle fistula; no complications in 45/76 modified radical ND and 54/72 supraomohyoid ND; 2 vs 1 postoperative… | 1 study · 148 participants | Low |
Surgery plus adjuvant radiotherapy vs Chemotherapy (chemoradiotherapy) Adverse events associated with treatment · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Adverse events: not reported for any participants (Iyer 2015). | 0 studies | No studies |
Superselective neck dissection vs Selective neck dissection Adverse events associated with treatment · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Adverse events: no adverse events reported; 72 participants (2 RCTs). | 2 studies · 72 participants | Very low |
Superselective neck dissection vs Selective neck dissection Total mortality · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Total mortality: not reported. | 0 studies | No studies |
Clear aligners (CA) vs Conventional fixed orthodontic appliances (CF) Salivary caries-associated bacteria (S. mutans and Lactobacilli, subjects with >10^5 CFU/mL) · Orthodontic patients undergoing comprehensive treatment (late mixed or permanent dentition, no active caries) · 3 and 6 months White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared… (2023) | Not meta-analyzed (insufficient number of studies). Both included observational studies (Mummolo 2020 [19]; Mummolo 2020 [25]) reported a higher number of subjects with S. mutans and Lactobacilli >10^5 CFU/mL in the… | 2 studies | Ungraded |
Supraomohyoid neck dissection vs Modified radical neck dissection Disease-free survival · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Disease-free survival: not reported (Guo 2014 reported disease-specific survival, not a review outcome). | 0 studies | No studies |
Sentinel node biopsy (neck dissection only if biopsy positive) vs Elective neck dissection Total mortality · Adults with oral cavity or oropharyngeal cancer · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 1.00 [0.90, 1.11] | 1 study · 279 participants | Low |
Surgery plus adjuvant radiotherapy vs Chemotherapy (chemoradiotherapy) Recurrence · Adults with oral cavity or oropharyngeal cancer · oral cavity Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Recurrence: not reported for the oral cancer subgroup (Iyer 2015). | 0 studies | No studies |
Surgery vs Radiotherapy alone Disease-free survival (new disease, progression, and mortality) · Adults with oropharyngeal cancer · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 1.07 [0.27, 4.22] | 1 study · 68 participants | Low |
Surgery vs Radiotherapy alone Recurrence · Adults with oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Recurrence: not reported. | 0 studies | No studies |
Daily chewing gum for 2 weeks or longer vs No gum chewing or control Unstimulated whole salivary flow rate · Elderly people and medically compromised people with xerostomia · 2 to 12 weeks, Meta-regression by chewing duration The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised… (2023) | SMD per week 0.06 | 6 studies · 291 participants | Ungraded |
Clear aligners (CA) vs Conventional fixed orthodontic appliances (CF) Plaque accumulation (Plaque Index) · Orthodontic patients undergoing comprehensive treatment (late mixed or permanent dentition, no active caries) · 3 months, Follow-up: 3 months White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared… (2023) | SMD -1.08 [-1.93, -0.24] | 5 studies · 211 participants | Ungraded |
Clear aligners (CA) vs Conventional fixed orthodontic appliances (CF) Plaque accumulation (Plaque Index) · Orthodontic patients undergoing comprehensive treatment (late mixed or permanent dentition, no active caries) · Maximum reported time-point per study (range 1-18 months) White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared… (2023) | SMD -1.58 [-2.57, -0.58] | 8 studies · 357 participants | Ungraded |
Superselective neck dissection vs Selective neck dissection Recurrence · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Recurrence: outcome not reported in a usable way in either study. | 0 studies | No studies |
Supraomohyoid neck dissection vs Modified radical neck dissection Adverse events associated with treatment · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Adverse events: significant difference in complication rates, lower for supraomohyoid (SOND 13.0% vs MRND 21.9%, P=0.040). UW-QOL at 1 year: supraomohyoid superior in pain relief (78.8% vs 75.2%, P=0.013) and shoulder… | 1 study · 332 participants | Very low |
PET-CT following chemoradiotherapy (neck dissection only if no/incomplete response) vs Planned neck dissection before or after chemoradiotherapy Locoregional recurrence · Adults with oral cavity or oropharyngeal cancer with nodal disease (stage N2 or N3) · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 1.00 [0.94, 1.06] | 1 study · 564 participants | Moderate |
Elective neck dissection (at time of primary tumour resection) vs Therapeutic (delayed) neck dissection Locoregional recurrence · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 0.58 [0.43, 0.78] | 4 studies · 458 participants | Moderate |
Supraomohyoid neck dissection vs Modified radical neck dissection Total mortality · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Total mortality: reported but not usable (Guo 2014: during follow-up 113/322 (35.1%) died; SOND 53, MRND 60). No GRADE rating. | 1 study | Ungraded |
Elective radical (comprehensive) neck dissection vs Elective selective neck dissection Recurrence · Adults with oral cavity cancer · 5 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | RR 1.21 [0.63, 2.33] | 1 study · 143 participants | Very low |
Gum chewing (sugar-free) vs No gum chewing (control) Unstimulated whole salivary flow rate · Elderly (>60 years) and medically compromised adults with xerostomia / dry mouth · Gum chewed daily for >=2 weeks (2 to 12 weeks; multiple time points for Kim and Ozen) The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised… (2023) | SMD 0.44 [0.22, 0.66] | 6 studies · 291 participants | Ungraded |
Supraomohyoid neck dissection vs Modified radical neck dissection Recurrence · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Recurrence: reported but not usable (variable follow-up) (Guo 2014). | 1 study | Ungraded |
Elective neck dissection (at time of primary tumour resection) vs Therapeutic (delayed) neck dissection Mortality (overall survival) · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 0.64 [0.50, 0.83] | 4 studies · 883 participants | Moderate |
Sentinel node biopsy (neck dissection only if biopsy positive) vs Elective neck dissection Disease-free survival (new disease, progression, and mortality) · Adults with oral cavity or oropharyngeal cancer · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 0.98 [0.90, 1.07] | 1 study · 279 participants | Low |
Gum chewing (sugar-free) vs No gum chewing (control) Self-reported xerostomia / symptoms of dry mouth · Elderly (>60 years) and medically compromised adults with xerostomia / dry mouth · Various (single session to 3 months) The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised… (2023) | Narrative vote-count: of 17 studies measuring self-reported xerostomia / dry mouth, 12 found a positive effect of gum chewing [18,19,21,23,24,25,26,27,30,31,38,40] and 5 detected no effect [17,29,33,34,37]. No study… | 17 studies | Ungraded |
Superselective neck dissection vs Selective neck dissection Locoregional recurrence · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Locoregional recurrence: data not presented usably and inconsistent; Pandey 2018 no difference (3/12 vs 3/20); Rastogi 2018 lower recurrence with superselective (Kaplan-Meier P<0.05); 72 participants (2 RCTs). | 2 studies · 72 participants | Very low |
Elective neck dissection (at time of primary tumour resection) vs Therapeutic (delayed) neck dissection Disease-free survival (new disease, progression, and mortality) · Adults with oral cavity cancer (tongue or floor of mouth) and clinically negative neck nodes · 3 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 0.56 [0.45, 0.70] | 5 studies · 954 participants | Moderate |
Surgery plus radiotherapy vs Radiotherapy alone Adverse events associated with treatment · Adults with oral cavity or oropharyngeal cancer Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Adverse events: severe acute effects in both groups (subcutaneous fibrosis, telangiectasia, moderate-to-severe oedema, xerostomia, trismus, dysphagia); subcutaneous fibrosis more prevalent with surgery + radiotherapy… | 1 study · 35 participants | Very low |
Clear aligners (CA) vs Conventional fixed orthodontic appliances (CF) Plaque accumulation (Plaque Index) · Orthodontic patients undergoing comprehensive treatment (late mixed or permanent dentition, no active caries) · 12 months, Follow-up: 12 months White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared… (2023) | SMD -2.14 [-3.64, -0.64] | 3 studies · 113 participants | Ungraded |
Surgery plus adjuvant radiotherapy vs Chemotherapy (chemoradiotherapy) Locoregional recurrence · Adults with oral cavity or oropharyngeal cancer · oral cavity Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Locoregional recurrence: reported difference between groups not statistically significant (P=0.355), but no useable data; 32 participants (1 RCT, Iyer 2015). | 1 study · 32 participants | Very low |
PET-CT following chemoradiotherapy (neck dissection only if no/incomplete response) vs Planned neck dissection before or after chemoradiotherapy Adverse events associated with treatment · Adults with oral cavity or oropharyngeal cancer with nodal disease (stage N2 or N3) Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Adverse events: 22 surgical complications in the PET-CT group vs 83 in the planned-surgery group (Mehanna 2017). | 1 study · 564 participants | Very low |
PET-CT following chemoradiotherapy (neck dissection only if no/incomplete response) vs Planned neck dissection before or after chemoradiotherapy Disease-free survival · Adults with oral cavity or oropharyngeal cancer with nodal disease (stage N2 or N3) Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | Disease-free survival: outcome not reported in a usable way (Mehanna 2017: disease-specific and other-cause mortality did not differ, P=0.80 and 0.41). | 1 study | Ungraded |
Elective radical (comprehensive) neck dissection vs Elective selective neck dissection Disease-free survival (new disease, progression, and mortality) · Adults with oral cavity cancer · 5 years Interventions for the treatment of oral cavity and oropharyngeal cancers: surgical treatment (2023) · Cochrane | HR 0.57 [0.29, 1.11] | 1 study · 104 participants | Very low |
Genetically predicted gene expression (TWAS; S-PrediXcan with GTEx v8 cis-eQTL across 49 tissues; cross-tissue S-MultiXcan) vs ECC-unaffected children (association of genetically predicted expression) Early childhood caries (ECC) - association with genetically predicted expression of TAS2R43 (chr12p13.2) · Children up to age 5-6 years (European / European non-Hispanic ancestry); 843 ECC-affected vs 2124 unaffected across 5… · Cross-sectional (ECC ascertained at the last dental exam before age 6), TAS2R43 (chr12p13.2); 27 (3) tissues; significant (Bonferroni p < 3.09x10-6) Association of Early Childhood Caries with Bitter Taste Receptors: A Meta-Analysis of Genome-Wide… (2022) | Z-score (cross-tissue mean, S-MultiXcan) 1.80 | 5 studies · 2974 participants | Ungraded |