Qat chewing did not significantly blunt short-term TMD improvement, but uncertainty remains
In conflict-affected Yemen, habitual qat chewing did not produce a statistically significant short-term disadvantage in conservative treatment for temporomandibular disorders when compared with non-chewing patients. At three months, 87.0% of habitual chewers improved versus 93.6% of non-chewers, a difference of 6.6 percentage points that did not reach statistical significance.
The number is reassuring on the surface. It is also not definitive enough to close the question.
This prospective cohort followed 148 consecutive patients diagnosed through Research Diagnostic Criteria for Temporomandibular Disorders Axis I examination at Sana’a University and Al-Kuwait Teaching Hospital between October 2018 and October 2020. Fifty-four patients, or 36.5%, were habitual qat chewers, defined as use on three or more sessions each week. Every participant completed the three-month follow-up, which removes one common source of bias from a study already operating in a difficult humanitarian setting.
Conservative care was uniform in its broad intent and pragmatic in its execution. All patients received reassurance, education, and self-care advice, with the clinician adding an NSAID, diazepam, amitriptyline, or a stabilization splint as routine care. The outcome was a patient-reported global rating of change, dichotomized as improved or not improved. Among chewers, 47 of 54 improved; among non-chewers, 88 of 94 improved.
Pain severity looked different in chewers before treatment began
Baseline pain did not simply run higher in chewers. It took a different shape. Nearly a third of chewers, 29.6%, reported no pain, while 24.1% reported severe pain, and none fell into the mild category. In the non-chewing group, 38 of 82 symptomatic patients rated pain as moderate or severe. The pain distributions differed in form, not in rank, suggesting that qat exposure may alter the clinical presentation of TMD rather than increasing pain in a smooth, linear way.
The biology makes sense. Qat contains cathinone, an amphetamine-like alkaloid that increases masticatory muscle activity. Long chewing sessions, often lasting several hours, place repeated mechanical load on the jaw muscles and temporomandibular joint, creating a plausible pathway toward myofascial pain and joint dysfunction. Chronic exposure may also interact with the central sensitization that already shapes TMD in many patients, especially in a population living through sustained stress and psychological burden.
One sentence captures the core result: the treated chewers improved almost as often as non-chewers.
Still, the adjusted analysis did not eliminate concern. The crude odds ratio for improvement among chewers was 0.47, and after age and sex were entered into the model it moved to 0.92, with age emerging as the only consistent predictor of non-improvement. Chewers were older than non-chewers, which matters clinically because age can influence both tissue resilience and symptom persistence. The study did not identify a treatment component that differed between groups, so the small gap in response cannot be explained by obvious imbalance in the care delivered.
The study was underpowered to rule out a meaningful disadvantage
The investigators planned for a difference of 16 percentage points or more, which means the cohort was not built to detect smaller treatment gaps. The 95% confidence interval for the absolute difference in improvement stretched from -16.8 to 3.7 percentage points. In practical terms, the trial cannot exclude a disadvantage for chewers that is clinically meaningful even if it failed to cross a conventional threshold for significance.
The same caution applies to the regression model. Once age and sex were included, the adjusted estimates rested on only 13 non-improvement events. That is a thin base for inference, and the authors were right to treat those adjusted findings as hypothesis-generating rather than conclusive.
The setting deserves attention because it shapes the meaning of the data. Yemen’s humanitarian crisis has left high rates of anxiety, depression, and post-traumatic stress disorder, all of which can amplify pain perception, reinforce clenching behavior, and prolong TMD symptoms. In that context, qat chewing sits on top of an already loaded pain ecology. The habit may worsen jaw loading, but it does not automatically translate into poor short-term response once conservative treatment is started.
That nuance is clinically useful. It argues against assuming that habitual qat users are destined to fail routine TMD care, while still leaving room for closer monitoring, especially in older patients and those with more severe baseline symptoms. Conservative management remained effective for the great majority of patients in both groups, and 9 in 10 overall improved by three months.
What the study does not answer is whether repeated qat exposure alters long-term relapse, whether it changes response to specific therapies such as splints or pharmacologic regimens, or whether cessation would improve outcomes beyond standard counseling. Those questions matter because the habit is deeply embedded in daily life and its mechanical and neurochemical effects are not trivial. The short-term message is narrower: conservative management worked well, but the data are too limited to dismiss a modest qat-related penalty in recovery.
Clinical relevance for dentists and maxillofacial clinicians
For clinicians practicing in regions where qat use is common, the findings support a careful but not fatalistic approach. Habitual chewers can still respond well to reassurance, self-care advice, medication, and stabilization splints. Baseline assessment should still ask about chewing behavior, because the habit may shape pain phenotype, muscle activity, and joint strain even when it does not dramatically change early improvement rates.
The study also reinforces the importance of interpreting response data in context. A non-significant result does not automatically mean no effect exists, especially when the confidence interval is wide and the number of outcome failures is small. Here, the signal points toward possible reduced improvement among chewers, but the sample size and event count leave the estimate imprecise.
For now, the most defensible reading is restrained. Habitual qat chewing did not produce a clear short-term treatment failure signal, yet the cohort was not large enough to rule out a disadvantage that would matter at the bedside.