Simply Science - Dental Caries

- it's all about amount, time and water

 

Applying toothpaste, brushing your teeth, spitting and rinsing – it’s as easy as 1-2-3, right? Well, not really, since in each of these steps, the interproximal fluoride concentration* will be affected, depending on the amount of toothpaste, the brushing time, and the water used to rinse the mouth. This is the assumption in a randomised crossover study by Ishizuka et al. (2020). The results reinforce and highlight the importance of precise recommendations to patients about their toothbrushing behaviours.

 

“Our hypothesis was that different amounts of toothpaste, durations, amounts of water and different kinds of toothpaste affect the interproximal fluoride concentration after toothbrushing.” - Ishizuka et al.

 

How the study was conducted

To examine the effects of toothbrushing routines on interproximal fluoride (F) concentration, the study involved 16 healthy adults, divided into two test series:

• Series 1: different toothbrushing routines. Investigated the impact of different amounts of toothpaste (1 cm vs. 2 cm), brushing durations (1 min vs. 2 min), and water rinsing volumes (10 mL vs. 20 mL) on fluoride retention**.
• Series 2: different forms of toothpaste administration. Assessed the influence of different fluoride toothpaste formulations (paste, gel, and foam) with different post-brushing rinsing conditions (no rinsing vs. 10 mL water).

Participants followed specific brushing protocols using a manual toothbrush (TePe GOOD™ Regular Soft) and fluoride toothpaste (1,450 ppm F). Fluoride levels in interproximal saliva were measured with an ion-specific electrode, with samples taken before brushing and up to 60 minutes after.

 

What the study found out

The study demonstrated that fluoride retention in interproximal areas is significantly influenced by:

• Amount of toothpaste used: A simple increase from 1 cm to 2 cm led to a 47.2% rise in fluoride concentration.
• Brushing duration: By extending brushing time from 1 minute to 2 minutes, fluoride retention was substantially increased by 26.8%.
• Post-brushing rinsing: Reducing water rinsing from 20 mL to 10 mL enhanced fluoride concentration by an impressive 41.2%.
• Type of toothpaste: Paste and gel formulations yielded approximately 50% higher fluoride levels than foam-based products.

 

These findings emphasise why dental professionals should recommend brushing for 2 minutes with 2 cm toothpaste and, at the same time, limit the amount of water for rinsing. It also shows us why patient education is important in affecting brushing habits, especially when it comes to fluoride retention for caries prevention.

Practical tips to bring into your practice

 

It is safe to assume that very few people consider how their toothbrushing routine affects the amount of fluoride their teeth get to enjoy. However, this knowledge is worth sharing – for healthier and stronger teeth. So, never assume that your patients are aware of this. Instead, make it a habit to explain the importance of fluoride and share these tips:

 

 

1. Encourage the suitable use of toothpaste

 

Advise patients to use 2 cm of fluoride toothpaste containing 1,450 ppm F (or equivalent, as recommended by local guidelines) for optimal protection. Emphasise this, especially for those at higher risk of caries.

Since the toothbrush head varies in size, it is not always enough to cover the bristles from edge to edge. One may need to make a U-turn while squeezing out the toothpaste to get the proper amount. Below, you can see 2 cm of TePe Daily™ toothpaste on a TePe Supreme™ toothbrush.

 

 

2. Promote brushing for longer

 

Encourage brushing for at least 2 minutes to maximise fluoride exposure. Why not recommend some good songs that are around 2 minutes long? Brushing along to a good song helps you brush for a long(er). Here are some song suggestions:

”Song 2" – Blur (2:01)

 

"And Your Bird Can Sing" – The Beatles (2:02)

 

"409" – The Beach Boys (1:58)

 

"She Came in Through the Bathroom Window" – The Beatles (1:57)

 

“I Wanna Be Sedated” – The Ramones (2:29)

 

“Respect” – Aretha Franklin (2:27)

 

 

3. Minimise rinsing after toothbrushing

 

Recommend patients to spit but not rinse, or to use minimal water (≤10 mL), to retain the fluoride in teeth for a longer period.

Key takeaways

 

This study shows how important controlled brushing routines are for fluoride retention. As dental professionals, we can help improve caries prevention by encouraging our patients to brush better. Simple tweaks – like using more toothpaste, brushing a little longer, and rinsing less – can really boost the power of fluoride, leading to better overall oral health.

 

 

*Fluoride concentration refers to the amount of fluoride present in the interproximal saliva at a given time after brushing.

 

**Fluoride retention refers to how long fluoride remains in the mouth after brushing, particularly in the interproximal areas.