Final answer:
Yellow bands on certain teeth are likely caused by dental caries, tartar, and gingivitis, due to poor dental hygiene, or possibly by deficiency diseases affecting the enamel.
Step-by-step explanation:
The most likely cause of the yellow bands on teeth #8, #9, and #22 through #27 could be attributed to dental caries, tartar, and gingivitis, which are conditions commonly linked to the overgrowth of oral bacteria such as Streptococcus and Actinomyces species. These oral health issues tend to arise due to insufficient dental hygiene practices. An x-ray image can reveal fillings, present due to such dental issues, as demonstrated in Figure 30.22. Another possible cause of discoloration which might exhibit as yellow bands is deficiency diseases that lead to oxidation of unsaturated fatty acids in the enamel, converting them to peroxide, and thereby changing the color of the teeth.