跪求牛人指点一句子

They said it might have been prevented had he received the dental care
he needed.

这一句中had he received the dental care
he needed. 怎么理解

这一段文字为

For example, in two thousand seven, doctors in the Washington area said a boy died when a tooth
infection spread to his brain. They said it might have been prevented had he received the dental care
he needed. He was twelve years old.

请牛人指教

他们（医生）说，如果他（这个小孩）能得到需要的dental care，他就不会挂点了。

the dental care (that 省略) he needed 为定从结构

had he received the dental care 是虚拟语气，假设，实际是没有得到该有的dental care

非常感谢！