A commentary on

Yazdanian M, Armoon B, Noroozi A et al.

Dental caries and periodontal disease among people who use drugs: a systematic review and meta-analysis. BMC Oral Health 2020; 20: 44.

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GRADE rating

Commentary

Dental health problems are among the most prevalent comorbidities associated with long-term drug use.1,2 Chronic drug use has been associated with higher risk for dental caries, periodontal disease, xerostomia, tooth wear and tooth loss.2,3 Dental health complications may be attributed to: a) the direct impact of the chemical qualities of the illicit substances on oral tissues (mucosa, gingivae and teeth)4,5 and on saliva production;6,7 and b) the user's associated health risk behaviours (that is, poor oral hygiene and high consumption of refined carbohydrates).4,8,9

The aim of this systematic review and meta-analysis was to examine the association between drug use and oral health. In terms of oral health conditions, the authors focused on periodontal disease and dental caries. Outcomes in terms of illicit drugs included methamphetamines, cocaine, heroin, opiates, crack and cannabis.

Following de-duplication and screening, ten papers were included in the review. The age or gender of the participants was not provided, nor the duration of drug use. The sample sizes of the included studies ranged from 18 to 1,015. Five of the studies were cross-sectional, four were case-control and another one was a cohort study. The drugs used by participants (some refer to the same study) included methamphetamine (three studies), cannabis (two studies), heroin (two studies), opiate (two studies), amphetamines (one study), opioid (one study), marijuana (one study) and illicit drugs (one study). Pooled estimates demonstrated that drug use was associated with higher risk of periodontal disease (OR 1.44; 95% CI 0.8-2.6) and dental caries (DMFT) (OR 4.11; 95% CI 2.07-8.15).

The protocol was not registered a priori. The PRISMA guidelines were followed for the conduct and reporting of the review. The inclusion and exclusion criteria could have been defined using the PICO framework. The decisions for some of the exclusion criteria lack clear justification. For example, the authors seem to have excluded studies which recruited people who 'use alcohol or smoke tobacco', although it has been shown that a considerable proportion of those who use drugs also consume alcohol and/or tobacco.4,10 Furthermore, studies involving people experiencing homelessness, among whom drug use is known to be prevalent, were excluded.11 The authors searched only online databases and only included studies in English language, and therefore there is an increased risk of publication bias. However, Begg's test found no evidence of publication bias for periodontal disease or caries. The search strategies used are clearly presented. Although a critical appraisal was conducted, the authors did not specify how this may have influenced interpretation of results. The findings of this review and meta-analysis are limited by the fact that the majority of studies were of cross-sectional design. Hence, causation was difficult to infer. Very importantly, the I2 statistic indicated high heterogeneity between studies and, as a result, there is high uncertainty in the effect estimates. Therefore, the results and conclusions of this systematic review should be interpreted with caution.

Consistently with another systematic review and meta-analysis,4the present review showed that drug use is associated with higher risk of periodontal disease and dental caries. In addition to the direct impact of drugs on oral health tissues, this could be suggestive of poor oral hygiene and low utilisation of dental services among people who use illicit substances.4,12 Considering the negative impact of long-term drug use on oral health, targeted interventions to improve oral health habits and access to dental services for people who use drugs are warranted.