Note 11 - Segment and Geographic Data - Summary of Operations by Geographic Area (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Product sales, net	$ 167,674	$ 2,257,851	$ 1,979,060	$ 4,173,759
Dental Segment [Member]
Product sales, net	165,674	2,242,751	1,969,260	4,158,260
Medical Segment [Member]
Product sales, net	2,000	15,100	9,800	15,500
Domestic [Member]
Product sales, net	40,354	1,058,853	657,605	1,875,274
Domestic [Member] | Devices [Member]
Product sales, net		130,138	525	232,205
Domestic [Member] | Handpieces [Member]
Product sales, net	38,812	897,357	635,490	1,597,316
Domestic [Member] | Other Products [Member]
Product sales, net	1,542	31,358	21,590	45,753
Domestic [Member] | Dental Segment [Member]
Product sales, net	38,354	1,047,753	655,605	1,864,174
Domestic [Member] | Dental Segment [Member] | Devices [Member]
Product sales, net		119,338	525	221,405
Domestic [Member] | Dental Segment [Member] | Handpieces [Member]
Product sales, net	36,812	897,057	633,490	1,597,016
Domestic [Member] | Dental Segment [Member] | Other Products [Member]
Product sales, net	1,542	31,358	21,590	45,753
Domestic [Member] | Medical Segment [Member]
Product sales, net	2,000	11,100	2,000	11,100
Domestic [Member] | Medical Segment [Member] | Devices [Member]
Product sales, net		10,800		10,800
Domestic [Member] | Medical Segment [Member] | Handpieces [Member]
Product sales, net	2,000	300	2,000	300
Domestic [Member] | Medical Segment [Member] | Other Products [Member]
Product sales, net
Rest of World [Member]
Product sales, net	127,320	1,148,998	1,321,455	2,198,485
Rest of World [Member] | Devices [Member]
Product sales, net	31,800	357,796	281,904	665,068
Rest of World [Member] | Handpieces [Member]
Product sales, net	87,632	764,163	1,018,123	1,485,067
Rest of World [Member] | Other Products [Member]
Product sales, net	7,888	27,039	21,428	48,350
Rest of World [Member] | Dental Segment [Member]
Product sales, net	127,320	1,144,998	1,313,655	2,194,085
Rest of World [Member] | Dental Segment [Member] | Devices [Member]
Product sales, net	31,800	357,796	274,304	665,068
Rest of World [Member] | Dental Segment [Member] | Handpieces [Member]
Product sales, net	87,632	760,163	1,017,923	1,480,667
Rest of World [Member] | Dental Segment [Member] | Other Products [Member]
Product sales, net	7,888	27,039	21,428	48,350
Rest of World [Member] | Medical Segment [Member]
Product sales, net		4,000	7,800	4,400
Rest of World [Member] | Medical Segment [Member] | Devices [Member]
Product sales, net			7,600
Rest of World [Member] | Medical Segment [Member] | Handpieces [Member]
Product sales, net		4,000	200	4,400
Rest of World [Member] | Medical Segment [Member] | Other Products [Member]
Product sales, net
CHINA
Product sales, net		50,000		100,000
CHINA | Devices [Member]
Product sales, net
CHINA | Handpieces [Member]
Product sales, net		50,000		100,000
CHINA | Other Products [Member]
Product sales, net
CHINA | Dental Segment [Member]
Product sales, net		50,000		100,000
CHINA | Dental Segment [Member] | Devices [Member]
Product sales, net
CHINA | Dental Segment [Member] | Handpieces [Member]
Product sales, net		50,000		100,000
CHINA | Dental Segment [Member] | Other Products [Member]
Product sales, net
CHINA | Medical Segment [Member]
Product sales, net
CHINA | Medical Segment [Member] | Devices [Member]
Product sales, net
CHINA | Medical Segment [Member] | Handpieces [Member]
Product sales, net
CHINA | Medical Segment [Member] | Other Products [Member]
Product sales, net