Antibiotic resistance is a major public health problem worldwide and the finding of alternative methods for eliminating bacteria is one of the 3prerogatives of medical research. The indiscriminate use of antibiotics in dentistry, especially for the treatment of peri-implantitis, could lead to superinfections.

Alternative methods, like photodynamic therapy mediated by the use of aminolevulinic acid and a red light has been largely described, especially in dentistry, but results were encouraging against Gram-positive bacteria, but limited against Gram-negative.

The effectiveness of photodynamic therapy mediated by a novel product containing aminolevulinic acid, Aladent (ALAD) has been tested in this in vitro study, against different types of bacteria particularly involved in the infections of the oral cavity and peri-implantitis. The novelty of ALAD is the marked hydrophilicity that should increase the passage of the molecule through the membrane pores of Gram-negative bacteria.

Considering the novelty of the product a preliminary experiment permitted to test the effectiveness against Enterococcus faecalis after 1 h of ALAD incubation at different concentrations, with or without different timings of LED irradiation. The count of CFUs and the live/dead observation with fluorescent microscopy showed a significant reduction and killing of bacterium.

Then, in the second stage, that could meet the necessity of effectiveness and the clinician's requests to reduce the timing of treatment, ALAD, with and without irradiation, was tested on Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Veillonella parvula and Porphyromonas gingivalis.

In particular, the efficiency of different concentrations of the product after a 25 min incubation was tested with and without the adjunctive LED irradiation for 5 min.

A slight ALAD bactericidal effect was reported for all bacteria, also without LED irradiation, however, the most effective treatment was 25 min of 50% ALAD incubation followed by 5 min of a red LED.

The in vitro tests demonstrated that ALAD gel with LED irradiation exerts a potent antibacterial activity on different bacteria, both Gram-positive and Gram-negative.

抗生素耐药性是全球主要的公共卫生问题，寻找消除细菌的替代方法是医学研究的三大特权之一。牙科中不加选择地使用抗生素，尤其是治疗种植体周围炎，可能会导致重复感染。

替代方法，如通过使用氨基乙酰丙酸和红光介导的光动力疗法，已得到广泛描述，尤其是在牙科领域，但对革兰氏阳性细菌的研究结果令人鼓舞，但对革兰氏阴性细菌却有限。

在这项体外研究中，已经测试了由包含氨基乙酰丙酸的新产品Aladent（ALAD）介导的光动力疗法针对不同类型的细菌（尤其是涉及口腔和种植体周围感染的细菌）的有效性。ALAD的新颖之处在于其显着的亲水性，可以增加分子穿过革兰氏阴性细菌膜孔的通道。

考虑到产品的新颖性，可以进行初步实验来测试在不同浓度下（无论有无LED照射时间）的ALAD孵育1小时后对粪便肠球菌的有效性。CFU的计数和荧光显微镜下的生/死观察表明细菌的显着减少和杀死。

然后，在第二阶段，可以满足疗效的需要，并减少临床医生减少治疗时间的要求，在有或没有辐射的情况下，对金黄色葡萄球菌，粪肠球菌，大肠埃希菌，细小韦拉氏菌和牙龈卟啉单胞菌进行了ALAD试验。

特别地，在有和没有辅助LED照射5分钟的情况下，在孵育25分钟后测试了不同浓度产物的效率。

据报道，所有细菌都有轻微的ALAD杀菌作用，也没有使用LED照射，但是，最有效的处理方法是50％ALAD孵育25分钟，然后是红色LED 5分钟。

在体外测试中证实，ALAD凝胶用LED照射上施加不同的细菌的有效抗菌活性，革兰氏阳性和革兰阴性。