Table 3 Study characteristics: general information, population characteristics, interventions and outcomes

2009

2016

2019

2019

4 weeks

8 weeks

4 weeks

8 weeks

Switzerland

Germany

Egypt

Germany

Longitudinal case series

Pilot Randomised Controlled Trial

Randomised Controlled Trial

Randomised Controlled Trial

To assess the oral microbiota and clinical data in subjects without access to traditional oral hygiene methods and who ate a diet available to humans during the Stone Age.

To evaluate an oral health optimized diet low in carbohydrates, and rich in Omega 3-fatty acids, vitamins C and D, antioxidants and rich in fibre.

To assess the effects of an anti-inflammatory diet on gingival health and serological parameters in child participants.

To investigate the influence of an anti-inflammatory diet on clinical, serological and subgingival microbiome parameters.

Yes, ethical approval obtained from the University of Zurich.

Yes, ethical approval was obtained from the University of Freiburg Ethics committee and the study was registered with the German Clinical Trials Register.

Yes, ethical approval obtained from the Research Ethics Committee, Faculty of Dentistry; Kafrelsheikh University.

Yes, ethical approval was obtained by the University of Freiburg Ethics committee and the study was registered with the German Clinical Trials Register.

Moderate

Moderate

Strong

Strong

10

16

40 (Intervention Group n = 20 Control Group n = 20)

38

None

1 intervention group participant

None

6 withdrawn due to unsuitable dietary regime

2 control group participants dropped out due to medical reasons

10

15 (Intervention Group n = 10 Control Group n = 5)

40 (Intervention Group n = 20 Control Group n = 20)

30 (Intervention Group n = 15 Control Group n = 15)

5 males: 5 females

7 adults (18-46yrs)

3 children (8-12yrs)

Intervention Group:

4 males: 6 females

Mean age 34.4 ± 14.1 years, ranging from 23 to 70 years

Control Group:

2 males: 3 females

Mean age 34.0 ± 16.5 years, ranging from 24 to 63 years

Intervention Group:

9 boys: 11 girls

Mean age 11.90 ± 1.410 years, ranging from 10 to 14 years

Control Group:

8 boys: 12 girls

Mean age 11.75±1.410 years, ranging from 10 to 14 years

Intervention Group (n = 15):

6 males: 9 females

Mean age 27.2 ±4.7 years

Control Group (n = 15):

7 males: 8 females

Mean age 33.7 ±13.1 years

Follow-up Time

After 4 weeks

Weekly intervals at weeks 5, 6, 7, 8

After 4 weeks

Weekly intervals at weeks 5, 6, 7, 8

Oral Hygiene Regime Intervention Group

None allowed other than the use of twigs and other natural products foraged.

At the start of the first week all participants were instructed to stop all interdental hygiene procedures for the next eight weeks.

Normal toothbrushing but no interdental cleaning

Participants were instructed not to perform any interdental hygiene throughout the study period.

Oral Hygiene Regime Control Group

N/A

At the start of the first week all participants were instructed to stop all interdental hygiene procedures for the next eight weeks.

Normal toothbrushing but no interdental cleaning

Participants were instructed not to perform any interdental hygiene throughout the study period.

Dietary Regime Control Group

N/A

Continue with usual diet mainly based on carbohydrates

No change in usual dietary habits

The control group was instructed not to profoundly change their diet for the next 6 weeks

Dietary Regime Intervention Group

Restricted Stone Age diet consisting of:

basic supply of whole grains of barley, wheat, spelt

salt, herbs, honey, milk,

meat from domestic animals (goats and hens),

berries, edible plants

fish

Reduction of the intake of carbohydrates <130 g/d:

See Table 5: Dietary Regime

Dietary recommendations were delivered verbally in an information brochure. This was done after the 2nd baseline measurements were taken.

2 further weeks were given to allow participants to adjust to the new dietary regime.

Participants were required to encouraged to follow the new diet for the remaining 4 weeks, completing a daily food diary.

Low-carbohydrates diet <130 g/ day:

See Table 5: Dietary Regime

Plus:

almonds and walnuts

gluten-free whole grains

olive oil and soy-based foods

herbs and spices

Detailed verbal data about dietary protocol was given to each patient and participant's parents/ caregivers.

At baseline, both groups had to continue their Western diet for 2 weeks.

After this, the test group had to change to an anti-inflammatory diet (AID) protocol for 4 weeks after two transitional weeks.

Reduction of the intake of starches <130 g/day:

See Table 5: Dietary Regime

Participants received detailed verbal introduction into the AID protocol for 30 min.

All participants were instructed to fill out a 24 hr-dietary diary for 1 week at the second, fifth and eighth week

Statistical analysis

Paired t-test to assess changes in the clinical indices PD, BOP, GI, and PI over time.

Significance declared at the P <0.001 level.

Mixed linear regression analysis used to test for differences between groups.

Multiple testing was corrected using the Scheffe method

Paired t-test to detect general changes within groups.

Mean and standard deviation for simple descriptive analysis (age and sex).

Student t-test used to assess changes between groups.

P-value 0.05 was considered as a level of significance.

Linear regression model used to analyse changes between groups.

Linear mixed model used to compare changes between groups over time, Bonferroni used to correct for multiple testing.

All analyses regarding the clinical (and serological) data were calculated with STATA 14.2.

Diet restriction, coupled with abstinence from oral hygiene, did not result in increased gingival inflammation; decreases in BOP and PDs were observed.

A low-carbohydrate diet that is rich in Omega-3 fatty acids, vitamins C and D, antioxidants and fibre can significantly reduce periodontal inflammation.

A low-carbohydrate, anti-inflammatory diet was able to significantly gingival inflammation.

The evaluated anti-inflammatory diet was able to significantly reduce gingival inflammation in a clinically relevant range.

Daily television reports were broadcast about participants experiences.

As a reward for participating in the study, the patients were given an electric toothbrush with a value of about 70 Euro.

N/A

Participants received

100 Euros for participation.