Condition: Parodontitis

Pooling nine studies, mechanical subgingival instrumentation produced a weighted pocket-depth reduction of 1.4 mm (95% CI 1.0 to 1.7) at 6 to 8 months, with an estimated 74% of pockets closing (95% CI 64 to 85). Six trials found no difference between hand and sonic or ultrasonic instruments, and thirteen trials found no difference between quadrant-wise and full-mouth delivery. Measured in: Adults with periodontitis across randomized controlled trials of subgingival instrumentation; nine studies contributed baseline and final pocket-depth measures. Only one RCT compared instrumentation directly with supragingival cleaning alone, so most of the pocket-depth estimate comes from before-and-after measures, not a controlled contrast. The review reports infection control, not tooth retention over decades.

Across 51 trials (5345 participants), chlorhexidine mouthrinse used with mechanical oral hygiene produced a large reduction in plaque (SMD 1.45, 95% CI 1.00 to 1.90 at 4 to 6 weeks, high-quality evidence) and a small reduction in gingivitis (Gingival Index 0.21 lower, 95% CI 0.11 to 0.31) that the authors judged not clinically important. Use for four weeks or longer caused extrinsic tooth staining. Measured in: Children and adults using chlorhexidine mouthrinse for at least four weeks as an adjunct to mechanical oral hygiene, across 51 RCTs. The gingivitis reduction was small and rated not clinically relevant, and data were insufficient in people with moderate to severe gum inflammation. Rinsing for four weeks or longer causes tooth staining, and taste disturbance and mucosal soreness were also reported.

Pooling three placebo-controlled RCTs with matched designs (doxycycline 20 mg twice daily for 3 months, 9-month follow-up), adding subantimicrobial-dose doxycycline to scaling and root planing significantly improved clinical attachment level, probing depth and gingival indices against scaling with placebo. The dose is below the level that acts as an antibiotic. Measured in: Adults with chronic periodontitis in three randomized placebo-controlled trials of scaling and root planing with or without subantimicrobial-dose doxycycline. Only three RCTs met inclusion, all with the same short regimen and follow-up, so the estimate rests on a small evidence base; the authors call for further studies. The improvements were statistically significant but modest in size.

Across 33 RCTs pooled in meta-analysis, placing a sustained-release tetracycline-class antimicrobial into the pocket with scaling and root planing added a pocket-depth reduction of 0.52 mm (95% CI 0.41 to 0.62) and an attachment gain of 0.34 mm (95% CI 0.20 to 0.47) at 6 to 9 months, sustained at 12 months and beyond. Minocycline was most consistent, and gains were smaller in smokers than non-smokers. Measured in: Adults with chronic periodontitis across 33 RCTs pooled in meta-analysis of locally delivered tetracycline-class antimicrobials as an adjunct to scaling and root planing, follow-up at least 6 months. The added benefit is sub-millimeter and targeted to individual pockets, not the whole mouth. Split-mouth trial designs showed larger effects, and outcomes were markedly smaller in smokers, so the average overstates the gain for some patients.

Pooling six prospective studies, smokers had about 80% higher risk of periodontitis onset or progression than people who had quit (RR 1.79, 95% CI 1.36 to 2.35) and than never-smokers (RR 1.82, 95% CI 1.43 to 2.31), while the risk among quitters was not different from never-smokers (RR 0.97, 95% CI 0.87 to 1.08). Quitters also regained up to 0.2 mm more attachment and 0.32 mm more pocket reduction after periodontal therapy. Measured in: Adults across six prospective longitudinal observational and interventional studies of smoking cessation and periodontitis onset, progression or treatment response. What could explain it instead: Smokers differ from non-smokers in ways that also affect the gums, including socioeconomic status, diet, alcohol use, oral-hygiene habits and access to dental care, any of which could inflate the apparent risk difference.. Only six studies met inclusion, so the pooled estimates rest on a limited base. Because the risk comparisons come largely from observational data, the benefit of quitting is inferred, not proven by randomization.

Across 35 RCTs (3929 adults), flossing added to brushing may reduce gingivitis at one month (SMD -0.58, 95% CI -1.12 to -0.04; 8 trials), and interdental brushes may reduce gingivitis and plaque more than brushing alone and may be more effective than floss. The certainty was low to very low and most trials were short with low baseline inflammation. Measured in: Adults in 35 randomized trials comparing toothbrushing plus an interdental device with toothbrushing alone, mostly with low baseline gingival inflammation. The evidence is low to very low certainty: trials were mostly short, participants often had little inflammation to start with, and few measured periodontitis or interproximal decay directly, so the size of the benefit is uncertain even though its direction points to benefit.

Across 12 RCTs, oral probiotics used with mechanical treatment improved probing pocket depth, bleeding on probing and attachment loss and reduced levels of major periodontal pathogens, mainly with Lactobacillus strains. Continuous administration was needed to maintain the benefit, and the probiotics were well tolerated. Measured in: Adults with chronic or aggressive periodontitis across 12 randomized controlled trials of probiotics as an adjunct to mechanical periodontal treatment. The trials were small and used varied strains, doses and durations, and the benefit held only while probiotics were taken, so this is an early, well-tolerated add-on, not an established treatment.

Across four studies, vitamin D added to non-surgical periodontal therapy gave limited extra clinical benefit in people whose baseline levels were already sufficient, but in people who were deficient, regimens that restored serum 25(OH)D above 30 ng/mL were associated with greater reductions in probing depth, improved attachment, and lower plaque and bleeding indices. Measured in: Patients with periodontitis undergoing non-surgical periodontal therapy across four studies assessing vitamin D status or supplementation. Only four studies met inclusion and the review synthesized them qualitatively, not pooling them, so the benefit is best read as correcting a deficiency, not supplementing everyone; standardized protocols and long-term trials are still needed.

Across five RCTs (160 participants, lasting 10 to 45 days), oil pulling showed no significant difference from chlorhexidine mouthwash, placebo or routine hygiene in post-intervention plaque index in three studies, or in modified gingival index in two studies. The trials were small, short and varied in reporting quality. Measured in: 160 participants across five randomized trials comparing oil pulling with chlorhexidine, placebo or routine dental hygiene over 10 to 45 days. The trials were few, small and short, with variable reporting quality, and they measured plaque and surface gum inflammation, not periodontitis outcomes such as pocket depth or attachment, so oil pulling has not been tested as a treatment for periodontitis.

Across 30 studies (2443 analyzed participants), treating periodontitis by subgingival instrumentation lowered HbA1c by an absolute 0.43% (4.7 mmol/mol) at 3 to 4 months (95% CI -0.59% to -0.28%), with a 0.30% reduction still present at 6 months, on moderate-certainty evidence. Reported harms were none or mild. Measured in: People with type 1 or type 2 diabetes and periodontitis across 35 RCTs (3249 randomized), most focused on type 2 diabetes, comparing periodontal treatment with no treatment or usual care. Two of 35 studies were at low risk of bias, 14 at high risk and 19 unclear, though a sensitivity analysis of low-risk studies supported the finding. Follow-up ran 3 to 12 months, so the durability of the blood-sugar benefit past a year is uncertain.

Pooling 39 cohort studies (4,389,263 people), periodontal disease was associated with higher risk of major adverse cardiovascular events (RR 1.24, 95% CI 1.15 to 1.34), coronary heart disease (RR 1.20), myocardial infarction (RR 1.14), stroke (RR 1.26), cardiac death (RR 1.42) and all-cause mortality (RR 1.31). This is an association across observational cohorts, not proof that gum disease causes the events. Measured in: 39 prospective cohort studies totalling 4,389,263 individuals, following people with and without periodontal disease for later cardiovascular outcomes and mortality. What could explain it instead: Periodontitis and atherosclerosis share major drivers, including smoking, aging, diabetes and socioeconomic status, so much of the overlap may reflect shared causes, not a direct effect of gum disease on the heart.. This is observational: the studies show that periodontitis travels with cardiovascular risk, not that treating the gums lowers heart attacks, which trials have not shown. The associations varied by region, disease definition and follow-up length.

Across 11 RCTs (5671 participants), treating periodontal disease during pregnancy showed no clear difference in preterm birth before 37 weeks (RR 0.87, 95% CI 0.70 to 1.10, low-quality evidence). Low birth weight below 2500 g may be reduced (RR 0.67, 95% CI 0.48 to 0.95, 7 studies), and the effect on preterm birth before 35 or 32 weeks and on perinatal mortality was unclear. Measured in: Pregnant women with periodontitis (14 studies) or gingivitis (1 study) across 15 RCTs (7161 participants), comparing periodontal treatment with no treatment during pregnancy. All included studies were at high risk of bias, mostly from lack of blinding and baseline imbalance, and the evidence for preterm birth was low quality. Maternal harms and adverse events of treatment were not reported in any study, and no maternal deaths occurred.

In an oral epithelial cell model, cranberry juice showed antibacterial and anti-inflammatory activity against some periodontal pathogens, but it also increased the adherence of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis to oral cells, while reducing adherence of Fusobacterium nucleatum. The organic acids that carry much of the activity can also erode tooth enamel. Measured in: Laboratory study of cranberry juice against periodontal bacteria and in an oral epithelial cell model, with no clinical periodontitis trial. This is laboratory work in cells and bacteria, not a clinical trial in people with periodontitis, and the effects were mixed, not uniformly favorable, so it does not support cranberry as a treatment for gum disease.