Time-dependent microbiome dynamics in orthodontic thermoplastic materials: comparing PETG and TPU

Area of Science:

• Oral microbiology
• Biomaterials science
• Orthodontic materials

Background:

• Orthodontic aligners are increasingly used for teeth straightening.
• The materials used in aligners, such as thermoplastic polyurethane (TPU) and polyethylene terephthalate glycol (PETG), may influence the oral environment.
• Understanding the impact of these materials on the oral microbiome and salivary pH is crucial for patient health.

Purpose of the Study:

• To compare the effects of TPU and PETG aligners on the oral microbiome and salivary pH.
• To investigate microbial shifts and pH changes associated with different aligner materials during orthodontic treatment.

Main Methods:

• Ten participants wore both TPU and PETG aligners for 24 hours.
• Saliva and microbial samples from aligners and plaque were collected at five time points.
• 16S rRNA sequencing was used to analyze microbial composition and diversity; salivary pH was measured.

Main Results:

• PETG aligners significantly decreased salivary pH early in wear (T4).
• Microbial shifts in plaque were observed earlier with PETG (T8) than with TPU (T12-T24).
• TPU aligners showed reductions in specific bacteria (Veillonella, Actinomyces, Fusobacterium) at 24 hours, while PETG increased Streptococcus and Fusobacterium.

Conclusions:

• PETG aligners impact salivary pH and plaque microbiome composition more rapidly than TPU aligners.
• TPU aligners induce distinct microbial shifts during prolonged wear.
• Material selection and cleaning protocols may need personalization based on microbial impact.