STudies suggest risks from unprotected Dental appliances

There is growing clinical and scientific evidence that orthodontic aligners and retainers can contribute to increased risk of dental decay (caries) and enamel demineralization—particularly when oral hygiene and pH control are inadequate. Below are key studies and findings supporting this concern:

• Study: "White Spot Lesions during Clear Aligner Treatment: A Prospective Clinical Study" (Buschang et al., 2021)
   
• Findings: Clear aligner patients developed white spot lesions, a sign of early decay, particularly when aligners were worn for extended hours and hygiene was not optimal.
   
• Conclusion: Aligners act as a barrier, trapping acids and plaque close to enamel.
   

• Study: "Salivary pH and Flow Rate in Orthodontic Patients Using Clear Aligners" (Alfaqeeh et al., 2020)
   
• Findings: Wearing aligners significantly reduced salivary flow and pH, leading to acidic oral conditions favorable to caries development.
   

• Study: "Risk of dental caries in patients treated with orthodontic appliances: a meta-analysis" (Xie et al., 2020)
   
• Findings: While most meta-analyses focus on fixed appliances, some included removable aligners, showing that microbial accumulation and acid retention under aligners posed caries risk similar to or higher than brackets in some cases.
   

• Study: "Changes in Oral Microflora and pH of Saliva in Patients Using Invisalign" (Li et al., 2018)
   
• Findings: Clear aligner use increased S. mutans and Lactobacillus counts, both highly cariogenic bacteria.
   
• Conclusion: Aligner use modifies oral microbiota toward a decay-prone state.
   

• Study: "Oral hygiene and bacterial plaque accumulation with Invisalign® aligners: a clinical study" (Bollen et al., 2015)
   
• Findings: Aligner wear creates a low-pH microenvironment under the plastic, especially when sugary or acidic drinks are consumed without rinsing or brushing.
   

Orthodontic aligners and retainers:

• Can trap acidic byproducts of bacteria against enamel.
   
• Reduce natural saliva flow and buffering.
   
• Create an anaerobic, acidic niche ideal for cariogenic bacteria.
   
• Require enhanced hygiene and pH management to prevent decay.
   

Dental professionals may consider recommending:

• pH-buffering gels or pastes (like baking soda or nano-hydroxyapatite formulations)

• pH testing: A new idea that could assess risk to dental patients is to pH test the inside of dental appliances in the morning. (See pH testing below)
   
• Daily fluoride use or hydroxyapatite
   
• Avoidance of acidic or sugary beverages while wearing appliances
   
• More frequent professional monitoring

Given the increased risk of enamel demineralization, low salivary pH, and microbial shifts associated with orthodontic aligners and retainers, applying a pH-buffering gel like pH7Smile inside the appliance before sleep may offer meaningful protection.

• Maintains a neutral to mildly alkaline pH during sleep when salivary flow is lowest.
   
• Buffers acids trapped beneath aligners or retainers.
   
• Delivers bioactive ingredients (like nano-hydroxyapatite or xylitol) directly against enamel.
   
• Supports remineralization and helps reduce bacterial adhesion.
   

• After brushing and flossing at night, apply a thin layer of pH7Smile gel inside the aligner or retainer.
   
• Wear the appliance overnight as usual.
   
• Do not rinse gel off before insertion — allow it to remain in contact with enamel for maximum benefit.
   

• Patients with white spot lesions or moderate to high caries risk
   
• Patients with acid reflux, dry mouth, or frequent snacking
   
• Anyone in active aligner treatment or in long-term retention

An off-label use of a new pH test developed by Harvard and Tufts University experts using CaviSense indicators has been suggested by the founder of pH7smile and presented to the company in August 2025 (an alternative they had not yet considered). This simple idea involves using the device inside the dental appliance immediately after waking up - running the tip inside the whole appliance and checking the results. If the tip of the indicator turns yellow (from purple) in ten seconds the acidity levels are a concern (below pH 5.5 when acidity is more harmful to teeth). If acidity concerns are discovered protective measures - such as the use of a protective pH gel, certain toothpastes and even a medical consult should be considered. 

The indicators may be ordered online: https://cavisense.com/

https://www.dentistryiq.com/dental-hygiene/clinical-hygiene/article/14248356/using-ph-testing-for-caries-management

Why is pH relevant to the oral condition and caries management? We know that every time we eat or drink, the pH in our mouth changes. This may lead to an acidic environment in the oral cavity. With this change in pH and the presence of caries-causing bacteria, mouths are susceptible to decay. “The pH scale measures a substance's acidity or alkalinity. The scale ranges from 0 to 14, with 7 representing neutrality. The lower end of the scale is acidic, and the higher end of the scale is alkaline.”1 

Do you know the pH of your oral cavity? What about your patients’? “Saliva has a normal pH range of 6.2 to 7.6 with 6.7 being the average pH.”2 How can we test the pH of saliva? There are many resources and tools to guide us while educating our patients to implement caries prevention practices.  

In-office saliva testing is a conversations starter about pH. There are a few ways to think about this. You’re able to provide a baseline pH level in a controlled environment and use the results as an educational tool. One easy-to-use test kit is the Saliva-Check BufferR by GC America. It’s used in schools and practices to educate students and patients on saliva pH factors. It includes tests for resting saliva, visual inspection of hydration, saliva consistency, and pH measurement.3 “Resting pH of mouth does not fall below 6.3. In the oral cavity, the pH is maintained near neutrality (6.7–7.3) by saliva.”2 The stimulated saliva is tested through saliva quantity and buffering capacity. All instructions, test strips, and charts are provided. 

Your local pharmacy will sell simple pH strips that can be used inside dental appliances in the morning to check the level. These strips are LESS EASY to read than the CaviStrip mentioned above, They could also be a fun experiment following harmful habits such as drinking energy drinks or wine with appliances in place. Prediction is this could be an A+ science project. 

They can be found online at various sources including: https://www.walmart.com/c/kp/ph-testing-strips-tablets