. . "For instance, Chalmers used a binary variable, with or without 3 or more medical conditions to measure the impact of comorbidity on dental caries in OAD. This method was questionable because a patient with 3 medical conditions such as osteoporosis, hyperlipidemia and anemia is not necessary to have a higher risk to develop caries than a patient who has only one medical condition such as Hemiplegia" . .