Table 1.

Studies evaluating the oral/periodontal microbiota of older adults or that have compared the oral/periodontal microbiota of different age groups

Reference	Number of subjects	Age groups (years old)		Microbiological technique	Sample	Summary of main results
Drake et al. (20)	Test 1: 375 PH (black) Test 2: 300 PH (white)	Mean Age: Test 1: 72.9 Test 2: 73.4		Immunofluorescence and BANA test Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia	Subgingival biofilm	Older black adults had higher proportions of Porphyromonas gingivalis, Prevotella intermedia and BANA scores in the subgingival plaque than older white adults (p<0.05).
Marsh et al. (59)	120 PH (41 with partial dentures)	Four categories: 20–39 40–59 60–79 ≥ 80		Microbial culture selective and non-selective media.	Supragingival biofilm and saliva	The proportions, mean log10 viable counts and the frequency of detection of yeasts and lactobacilli in saliva and plaque were consistently higher in partial-denture wearers (p<0.05). The proportions of Staphylococcus species and Streptococcus mutans were elevated in denture wearers, but these differences were not statistically significant.
Newman et al. (68)	7 PH	Mean: 63.0		Microbial culture selective and non-selective media.	Subgingival biofilm	Gram-positive organisms accounted for 50% of the predominant cultivable microbiota. Streptococcus species were the most frequently isolated organisms and were found in 83.8% of the samples.
Percival et al. (72)	79 PH	Four categories: 20–39 40–59 60–79 ≥ 80		Microbial culture selective and non-selective media.	Supragingival biofilm and saliva	The total counts of viable bacteria in saliva, and the prevalence of Streptococcus mutans in supragingival plaque and saliva did not differ among age groups (p>0.05). Mean proportions, mean viable counts and the isolation frequency of Lactobacillus species were higher in the saliva samples of subjects ≥ 70 years old compared to those ≤ 39 years old (p<0.05). Actinomyces naeslundii was found in higher proportions in the younger age groups (20–39 and 40–59 years old), when compared with the older age groups and Actinomyces oralis was found in higher proportions in the oldest age groups 60–79, ≥ 80 years old (p<0.05).
Preza et al. (75)	Control: 20 PH Test: 21 PH with root caries	Mean: Control: 84.3 Test: 88.7		16S rRNA-based microarray for 300 species	Supragingival biofilm	Lactobacillus casei/paracasei/rhamnosus and Pseudoramibacter alactolyticus were associated with root caries biofilm samples. Actinomyces species were found more frequently in subjects from the control group (p<0.05).
Rodenburg et al. (78)	Test 1: 38 (severe periodontites) Test 2: 104 (refractory periodontites)	Test 1 and Test 2 groups presented the following age categories: 14–20 21–10 31–40 41–70		Microbial culture Porphyromonas gingivalis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans	Subgingival biofilm	In Test 1 group the prevalence of Aggregatibacter actinomycetemcomitans-positive subjects and the number of those solely infected with A. Actinomycetemcomitans decreased with increasing age (p<0.05), whereas the prevalence of P. gingivalis-infected subjects increased with increasing age (p<0.05). However, these trends were not observed in the refractory periodontitis patients
Savitt et al. (82)	1,492	Test 1 and Test 2 groups presented the following age categories: 10–19 20–29 30–39 40–49 50–59 60–69		DNA probes Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis	Subgingival biofilm	Aggregatibacter actinomycetemcomitans was correlated with subjects in the youngest age group (10 to 19 years old) with decreasing prevalence and levels in older age groups in comparison with the younger groups (p<0.05). In contrast, Porphyromonas gingivalis showed an inverse association with subject age, showing highest prevalence and levels in older groups (>30 years old) compared to subjects in younger age groups (10–29, 20–29 years old) (p<0.05).
Slots et al. (86)	1624 periodontitis subjects	Range: 15 to 89 Six categories: 15–24 25–34 35–44 45–54 55–64 >64		Microbial culture Prevotella intermedia and Aggregatibacter actinomycetemcomitans	Subgingival biofilm	Aggregatibacter actinomycetemcomitans was in higher prevalence (74%) in subjects < 25years old than in adults and geriatric subjects (31%). Prevotella intermedia was present in 45% of the subjects and no predilection for a specific age group was detected.
Slots et al (87)	3075 “refractory” periodontitis	Range: 12 to 93 Fifteen categories:		Microbial culture selective and non-selective media.	Subgingival biofilm	Older females (15.9%) and males (15.3%) had higher prevalence of enteric rods and pseudomonads than younger subjects (10.9%) (p<0.05). Older infected females yielded significantly higher viable counts of these microorganisms than younger infected females (p<0.05).
		10–14 20–24 30–34 40–44 50–54 60–64 70–74 >80	15–19 25–29 35–39 45–49 55–59 65–69 75–79

PH, periodontal health