A bioarchaeological study of medieval Portuguese skeletons reveals that Islamic oral hygiene practices, rooted in religious teachings, may have protected against dental disease compared to Christian counterparts.
Imagine a world without toothbrushes, toothpaste, or dentists. What would your teeth look like? For most people in medieval Europe, the answer is grim: rampant cavities, severe tooth loss, and painful abscesses. But a groundbreaking new study published in Frontiers in Environmental Archaeology suggests that one group may have had significantly better oral health than others—medieval Muslims.
The study, titled “The role of religious faith in dental pathological lesion patterning and approaches to care in a medieval Portuguese assemblage,” analyzed over 3,000 teeth from 639 burials in Santarém, Portugal, comparing individuals buried according to Islamic and Christian funerary rites between the 7th and 13th centuries CE.
The findings are striking: Islamic males showed significantly lower rates of dental caries (cavities) and calculus (tartar) compared to Christian males. Islamic females also showed significantly lower rates of calculus compared to Christian females. The researchers attribute these differences not primarily to diet, but to religiously motivated oral hygiene practices—specifically, the use of the miswak (siwak), a teeth-cleaning twig recommended by the Prophet Muhammad (peace be upon him).
The Medieval Mouth: A Battlefield of Disease
Before modern dentistry, oral disease was rampant. Dental caries, periodontal disease (gum disease), and antemortem tooth loss (teeth lost before death) affected the vast majority of adults. Without effective cleaning, plaque hardened into calculus (tartar), which irritated gums, caused them to recede, and created pockets where bacteria flourished.
The study documented these conditions in detail:
- Antemortem tooth loss (AMTL): As expected, older individuals (50+ years) lost significantly more teeth than younger adults (18-49 years). In Islamic females aged 50+, 31.3% of teeth were lost before death. In Christian females of the same age, the rate was even higher at 43.6%.
- Dental caries (cavities): Corrected caries rates (accounting for teeth lost to decay) revealed that Islamic females aged 18-49 had significantly more cavities (25.9%) than their Christian counterparts (16.5%). However, Christian males aged 18-49 had significantly more cavities (19.2%) than Islamic males (11.6%).
- Calculus (tartar):Â This is where the most dramatic differences emerged. Islamic individuals consistently had lower rates of calculus than Christians. For calculus severity, Christians had significantly higher rates of moderate to severe tartar buildup (scores 2 and 3), while Muslims had higher rates of minimal tartar (score 1). Specifically, Christian males had significantly more calculus overall (55.7%) than Islamic males (49.0%).
Key Dental Health Indicators by Religious Group and Sex
| Indicator | Islamic Females | Christian Females | Islamic Males | Christian Males |
|---|---|---|---|---|
| AMTL (50+ years) | 31.3% | 43.6% | 36.7% | 33.3% |
| Caries, Corrected (18-49 years) | 25.9% | 16.5% | 11.6% | 19.2% |
| Calculus, Total | 58.6% | 58.6% | 49.0% | 55.7% |
| Calculus, Score 2-3 (Moderate-Severe) | Lower | Higher | Lower | Higher |
| Periodontal Disease (50+ years) | 26.1% | 53.5% | 30.0% | 32.9% |
Why the Difference? The Role of Oral Hygiene
The researchers considered several possible explanations for the observed differences:
Dietary Differences: Islamic dietary law prohibits pork and alcohol, while Christian diets emphasized pig and wine. However, stable isotope analysis of bone collagen (which reflects protein sources) showed no significant dietary differences between the two groups. Both consumed predominantly C3 plants (wheat, barley, rye) and terrestrial animal protein. The one Christian individual analyzed actually showed higher marine protein consumption, but this was not representative.
Access to Care: Could Christians have had less access to dental care? The study notes that “keeping a clean mouth was both a physical and spiritual act” in Islam. The Prophet Muhammad (peace be upon him) strongly encouraged the use of the miswak (siwak)—a teeth-cleaning twig from the Salvadora persica tree—as part of daily hygiene.
Calculus Severity by Religious Group and Sex
| Calculus Score | Islamic Females | Christian Females | Islamic Males | Christian Males |
|---|---|---|---|---|
| Score 1 (Minimal) | Significantly Higher | Lower | Significantly Higher | Lower |
| Score 2 (Moderate) | Lower | Significantly Higher | Lower | Significantly Higher |
| Score 3 (Severe) | Lower | Higher | Lower | Higher |
The Prophet (peace be upon him) said: “The siwak is a means of purification for the mouth and pleasing to the Lord” (Sahih Bukhari). He specifically recommended its use before prayers, upon waking, and when entering the home. This religious practice would have been performed multiple times daily by devout Muslims.
The Miswak: Nature’s Toothbrush
The Salvadora persica tree (arak) has been used for oral hygiene for thousands of years. Its twigs contain natural antibacterial compounds, including benzyl isothiocyanate, which inhibits the growth of plaque-forming bacteria. Chewing the twig frays the fibers, creating a brush-like end that mechanically removes plaque and food debris.
The study’s findings align perfectly with this practice. Lower calculus rates in Islamic individuals suggest more effective mechanical cleaning of tooth surfaces. Lower caries rates in Islamic males (compared to Christian males) suggest reduced plaque accumulation and bacterial activity.
Notably, Islamic females did not show the same advantage in caries rates—in fact, they had higher corrected caries rates than Christian females. The researchers suggest this may be due to differential access to oral hygiene practices between sexes, or the impact of pregnancy and fertility on dental health (pregnancy can increase caries risk due to hormonal changes and dietary cravings).
Periodontal Disease: A Striking Difference in Older Women
One of the most dramatic findings involved periodontal disease (gum disease) in older women. Among individuals aged 50+ years, 53.5% of Christian females had periodontal disease compared to only 26.1% of Islamic females—a difference of over 27 percentage points.
The researchers note that “older (50+) Christian females exhibited more periodontal disease than their Islamic female counterparts (G = 12.26, p < 0.01).” This suggests that Islamic oral hygiene practices may have been particularly protective for aging women, who are more vulnerable to gum disease due to hormonal changes.
Tooth Wear: Similar Across Groups
Interestingly, tooth wear (the loss of enamel from chewing) did not differ significantly between religious groups. This suggests that both populations consumed similarly abrasive foods, and the differences in oral health were not due to diet but to hygiene.
The majority of individuals (75-84%) had relatively minor tooth wear (scores < 5), indicating that severe attrition was not a major factor in their dental disease.
The Bigger Picture: Faith as a Determinant of Health
This study is part of a growing field of “bioarchaeology of religion,” which examines how religious beliefs and practices shape physical health in past populations. The researchers note that “the presence of distinct faith communities buried in adjacent graves offers us the opportunity to furnish a comparative approach to see how health and disease vary by faith community.”
The findings challenge common assumptions about medieval oral health. While popular media often portrays the Middle Ages as a time of universally poor dental hygiene, this study shows that religious practice could significantly mitigate disease risk.
Limitations and Future Directions
The study has several limitations. The Christian sample was smaller than the Islamic sample, and the Christian individuals came from a later period (13th-17th centuries) than the Islamic individuals (8th-12th centuries). Temporal differences in diet or access to resources could confound the results, though the researchers attempted to control for this.
Additionally, the study could not directly measure miswak use—it inferred it from the archaeological and historical context. Future research should examine dental calculus from medieval Islamic populations for microscopic evidence of plant fibers consistent with Salvadora persica.
The stable isotope pilot sample was small (n = 18), limiting the ability to detect dietary differences. Larger isotopic studies are needed to confirm the absence of dietary differences between the groups.
A Final Word of Hope
This study is a testament to the power of religious practice to shape health outcomes. The Prophet Muhammad (peace be upon him) emphasized cleanliness as half of faith, and his followers took this commandment seriously. Their teeth—preserved for centuries in the soil of Santarém—tell the story.
For modern Muslims, the message is clear: the miswak is not just a relic of the past. It is a scientifically validated tool for oral health. Studies have shown that miswak use can reduce plaque, gingivitis, and bacteria comparable to or better than conventional toothbrushes.
The medieval Muslims of Santarém did not have dentists, fluoride toothpaste, or electric toothbrushes. But they had faith—and that faith kept their mouths cleaner than their Christian neighbors.
As the Prophet (peace be upon him) said: “The siwak is a means of purification for the mouth and pleasing to the Lord.” Science has confirmed the first part. May we all benefit from the second.
Reference: here
Other Articles:
