Patients taking insulin for diabetes must adhere to their diet. Consumption of adequate calories and medication at proper intervals is important to determine before treatment is initiated. Failing to eat in accordance with their diabetes management plan may result in a hypoglycemic event. A hypoglycemic reaction also may be due to an overdose of insulin or an oral hypoglycemic agent [12].

Pulps from patients with diabetes tend to have limited capillary exchange, collateral circulation, impaired immune response, increased risk of acquiring pulp infection (especially anaerobic ones), or necrosis, besides toothache and occasional tendency toward pulp necrosis caused by ischemia. In regard to molecular pathology, hyperglycemia is a stimulus for bone resumption, inhibiting osteoblastic differentiation and reducing bone recovery [11].

A study reviewed data from electronic patient records. It investigated the effect of diabetes mellitus on endodontic treatment outcome. It determined that patients with diabetes have increased periodontal disease with endodontic involvement compared with patients who did not have diabetes. There was also a trend toward increased symptomatic periradicular disease in patients with diabetes who received insulin, as well as flare-ups in all patients with diabetic disease [5].

Two years or longer postoperatively, 68 % of cases followed were successful. Older age, absence of preoperative lesions, presence of permanent restorations, and longer postoperative evaluation periods all were associated with a successful outcome. A multivariate analysis showed that in cases with preoperative periradicular lesions, history of diabetes was associated with a significantly reduced successful outcome. It was concluded that patients with diabetes have increased periodontal disease in teeth with endodontic problems and have reduced likelihood of success of endodontic treatment in cases with preoperative periradicular lesions [5].

Patients with liver disease and/or alcoholism require special consideration in terms of drugs to be used in conjunction with treatment. For example, a history of liver disease affects the choice of analgesics and precludes the use of acetaminophen.

Alcoholic patients with cirrhosis may require increased amounts of local anesthetics or additional anxiolytics due to liver enzyme induction and central nervous system effects of alcohol [12]. Dental drugs metabolized primarily by the liver include lidocaine (Xylocaine), mepivacaine (Carbocaine), prilocaine (Citanest), and bupivacaine (Marcaine). Their safety depends on the dose of the drug used and the severity of liver disease. Aspirin, acetaminophen (Tylenol), codeine, meperidine (Demerol), and ibuprofen (Motrin) should be avoided or used in a limited dose. Sedatives such as diazepam (Valium) and barbiturates should also be avoided or used in a limited amount depending on the severity of liver disease. The antibiotics metronidazole and vancomycin should also be avoided in the presence of severe liver disease (accute hepatitis and cirrhosis) [12].

A history of chronic facial pain or headaches provides an important clue indicating that the clinician will have to differentiate between non-odontogenic and odontogenic pain.

There is recent evidence that a history of chronic painful conditions (e.g., temporomandibular dysfunction or chronic headaches) may predispose a patient to pain associated with endodontic treatment. A history of chronic painful conditions represents a potentially significant finding [16, 17].

The dental history should also include details concerning past dental experiences including recent restorations and periodontal treatment. Either of those could cause postoperative symptoms that may complicate the diagnosis.

The history provides important insight into the patient’s level of dental sophistication in terms of how they value preservation of their natural dentition. For example, a patient missing numerous teeth and having poor oral hygiene is an unlikely candidate for complex treatment with a questionable prognosis. Ultimately, the treatment plan must be individualized and appropriate for the patient. Prudent use of the patient’s financial resources is another factor to consider.

Patients in severe pain may not be able to provide accurate information about the history of pain due to their physical and emotional distress. They may seem angry and depressed which are common outcomes of prolonged pain. Extreme pain can dominate a patient’s life and cause a person’s personality to totally change. Emily Dickinson, the American poet, expressed that feeling in a portion of a poem.

PAIN has an element of blank;

It cannot recollect

When it began, or if there were

A day when it was not.

It is not uncommon for a patient in acute pain at an emergency visit to seem angry and hostile, but after being relieved of pain the patient returns almost as a different human being. Understanding and empathy are important characteristics for a clinician treating a patient in pain.

A clinical study examined 79 endodontic emergency patients. Patients and dentists assessed the level of pain by using a verbal numeric rating scale (VNRS.) Results of that study indicated that patients presenting with odontogenic pain localized the painful tooth 73.3 % of the time. Patients experiencing periradicular pain localized the painful tooth (89 %) of the time, significantly more often than those without periradicular symptoms (30 %, p < 0.0001.) It was concluded that the presence of periradicular pain increases the accuracy of pain localization. The VNRS is highly correlated with other pain scales and is an acceptable initial pain assessment tool for endodontic emergency patients [13].

Patients were frequently able to localize pain to the proper arch. The study found that the pain could be localized in 94.6 % of cases when there was pain to percussion and 90 % (p = 0.60) for an overall arch localization of 92.3 %.

In assessing pain it is useful to have the patient describe the level of pain on a scale of 1–10. A written scale can be used for the patient to self-assess their level of pain. It is helpful in gauging the patient’s progress or regression, if the patient must return for an additional diagnostic visit.

Some clinicians add descriptors to numbers such as “worst pain imaginable” for number 10 or “barely noticeable” for number 1 and ask the patient to indicate where they fall on that scale (Fig. 1.1).

Non-odontogenic “toothache” is a less common finding than odontogenic toothache. Differentiating odontogenic from non-odontogenic pain can be a challenging process. There are basic steps that can differentiate the site of where pain is experienced from the actual source of pain. Definitive treatment should never be initiated until the source of pain is clearly identified.

The finding of non-odontogenic pain is often confirmed by the patient’s description of the onset of pain. If the description omits any of the most common causes of dental pain (e.g., thermal sensitivity or pain during mastication), it is another important clue pointing toward non-odontogenic causation. While the precise cause of pain at that stage remains unknown, it is clear that an endodontic dental cause is unlikely.

A myofascial source may be the cause of a toothache due to referred pain. Myofascial pain is often described as a deep, dull, aching pain that may be associated with referred pain to a tooth. Finger pressure and palpation of a specific myofascial trigger point may result in both muscle and tooth pain. Further tests are then required to identify the primary cause of pain. Palpation of musculature is an essential part of the diagnostic process and is discussed further in Chap. 2. It is not uncommon to find that a patient who has responded normally to sensibility and clinical tests experiences pain on palpation of the musculature.

Non-odontogenic toothache of sinus or nasal mucosal origin may be due to viral, bacterial, or allergic rhinitis and may be expressed as referred pain in the maxillae or maxillary teeth experienced by the patient as a toothache. Bacteria-induced sinusitis pain is often characterized as severe, throbbing pain with a sense of pressure [9].

After a tentative diagnosis of pain due to sinus involvement, it is prudent to refer the patient to a physician for confirmation of the diagnosis and treatment.