That's an interesting question!
So I will first explain the exact mechanism of Xylitol in our oral cavity.
Xylitol, is a naturally occurring five-carbon sugar polyol, a white crystalline carbohydrate.
Now the most significant contributor or the pioneer bacteria for dental caries (which further leads to tooth decay) is Streptococcus Mutans.
Xylitol reduces the levels of mutans streptococci (MS) in plaque and saliva by disrupting their energy production processes, leading to futile energy cycle and cell death. It reduces the adhesion of these microorganisms to the teeth surface.
Xylitol, like any other sweetener, promotes mineralization by increasing the salivary flow when used as chewing gum or large xylitol pastille. The uniqueness of xylitol is that it is practically nonfermentable by oral bacteria. Also, there is a decrease in levels of MS, as well as the amount of plaque, when there is habitual consumption of xylitol.
You can read in more detail about the mechanism of action from the reference website
Overall benefits of Xylitol in the oral cavity-
Xylitol decreases the incidence of dental caries by increasing salivary flow and pH13 and reducing the number of cariogenic (MS) and periodontopathic (Helicobacter pylori) bacteria, plaque levels, xerostomia, gingival inflammation, and erosion of teeth.
Now xylitol is available in number of preparations-
Xylitol mouth rinses
Both topical and non topical preparations are equally effective for reducing as well as prevention of dental caries.
Except the xylitol wipes you may read about each of the preparations from the reference website
Now coming to the xylitol wipes.
A number of studies have been done for the efficacy of Xylitol wipes in dental caries of children.
The American Academy of Pediatric Dentistry (2008)has recommended tooth wipes as an important tool for oral hygiene care in infants and toddlers.
According to one such study
Our study clearly showed a significant reduction of new caries lesions in young children as a result of daily xylitol-wipe use, with 7 times fewer young children from the xylitol-wipe group developing new caries lesions compared with the placebo-wipe group.
In one more interesting study
Our study explored the anti-caries mechanisms of xylitol wipes on MS in our clinical trial, which showed marked inhibition of caries progression in young children who were treated with xylitol wipes. We first explored the genetic profile of MS colonization. Our results may suggest that MS colonization is less stable in the xylitol-wipe group as compared with the placebo-wipe group. This indicates that daily xylitol-wipe use may affect the stability of MS colonization in young children
However they found that there was no reduction in the number of MS bacteria.
Hence one concluding statement for xylitol wipes by the previous study
These results suggest that, instead of reducing MS levels, the anti-caries effect of direct and indirect use of xylitol may have been achieved by modifying the virulence of the cariogenic bacteria or the ecology of the oral flora to be less cariogenic or less transmissible.
Some mechanisms have been proposed by several dentists for xylitol wipes-
She said the reason that a change in caries didn't correlate with a change in S mutans might be that other species of bacteria are involved.
Dr. Zhang told Medscape Medical News that she agreed that this is one possible explanation. Another might be that xylitol changes S mutans in some way that makes it less virulent, she said. Or perhaps it affects the biofilm in which the organism works.
The xylitol wipes are also applied on the tooth along with the gums in those infants who can not chew gums.
Hence Xylitol wipes are equally useful for the reduction as well as in prevention of dental caries.
As a concluding statement I will suggest that rather than comparing gums vs wipes OP should look that both of them have got different indications.
Though the mechanism of wipes has not been clearly understood, studies do suggest that it is effective in reducing as well as preventing dental caries in infants who have not learnt to chew. And after they grow old then xylitol gums can be easily chewed by them.
However, still if given a choice then definitely xylitol gums are more effective,-
Moreover, the act of chewing and suckling are potent stimulators of salivary flow which enhances the clearance of food debris, oral bacteria, and acid buffering capacity benefiting the remineralization of enamel and protecting from tooth decay.
Hope I have satisfactorily answered your question :)