Is it normal to bond custom made lingual braces almost 6 months after impressions and after many treatments were done?

I had a device in my mouth that kept in place a pontic with a wire.Ortho took impressions with that pontic on.After,I had emergency extraction,bone graft etc. to cure perio disease.Then he glued a different pontic-no wire involved.6 months went by.Ortho said 'now you must bond the braces' without retaking impressions.Then he un-glued one side of the pontic to let the teeth move.Pontic crumbled in my throat during sleep,Cpr was performed.Was everything standard procedure and I was just unlucky?

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