Sub-ablative laser irradiation to prevent acid demineralisation of dental enamel. A systematic review of literature reporting in vitro studies.

Aim: Caries lesions begin with enamel acid demineralisation mediated by microorganisms. Lasers with sub-ablative energy might act as a prophylactic intervention to reinforce enamel against lesions caused by acid.

Materials And Methods: A systematic review of the literature was performed evaluating only in vitro studies published from 2010 to 2018. The research was performed using the following databases: Medline, Embase and the Web Of Science. A further search was performed consulting the list of references of the included studies as well as book chapters which dealt with this topic.

Results: A total of 347 records were retrieved and, after their evaluation, 36 studies were included. CO2 lasers were the most described and effective device in preventing acid demineralisation. This type of laser was unique in improving the already positive results obtained with fluoride-based interventions. Er,Cr:YSGG (with fluencies > 8.5J/cm2), diode and argon lasers also improved enamel acid resistance (p-values ranging from 0.05 to 0.001) producing similar effects with fluoride-based interventions. Regarding the sealant retention outcome, the Er:YAG laser was able to perform an enamel etching which was as effective as the traditional acid etching with the advantage of being easier and usually well accepted by low-compliant patients (i.e. younger children). Nd:YAG presented the worst results. The most common structural changes after the laser irradiation were water and carbonate reduction in the enamel combined with a phosphate and calcium enamel content increase. Moreover, the calcium/phosphate ratio was found to reach the 1.67 ideal ratio.

Conclusion: The in vitro studies that examined the prophylactic use of lasers for increasing enamel acid resistance presented interesting results that are enough to support a further in vivo experiment. This would entail the use of a clinical laser as an alternative or in combination with fluoride-based interventions.