求翻译：另外，由于唾液的酸碱度属于中性，所以接吻能预防牙科疾病。由此可见，每次接吻就相当于免费咀嚼健齿口香糖，环保、卫生、有效，一举三得。是什么意思？

In addition, because saliva pH is neutral, so kissing can preventing dental diseases. This shows that the kiss at a time is equivalent to free chewing health of teeth chewing gum, environmental protection, health, and effective, have three.