Xerostomia . Xerostomia is defined as a subjective sensation of decrease or absence of salivary secretion. It is also known as asialorrhea, hyposalivation, or dry mouth.


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  • 1 Introduction
  • 2 Etiology of xerostomia
  • 3 Pathogenesis of xerostomia
  • 4 Clinical diagnosis and complementary tests
  • 5 Quantitative measurements of salivary flow
  • 6 Qualitative measurements of salivary flow
  • 7 Other tests used
  • 8 Conclusions
  • 9 Sources


It was first described by Bartley in 1868 , who established a relationship back then between the symptoms presented in patients who suffered from it and its repercussion on their quality of life. It is convenient to highlight how xerostomia does not suppose a specific clinicopathological entity, but rather an underlying symptom of specific pathological conditions and their local or systemic treatment.

Regarding its current prevalence, we must highlight its high incidence, around 20%, among subjects over 60 years of age. This is justified in the large number of these subjects who receive systemic treatment for multiple chronic diseases, treatments that in a large number of cases are harmful to the glandular apparatus that produces saliva . However, and despite its considerable prevalence in the population, it is a picture often undervalued by the patient, and consequently its passage is in many cases unnoticed by healthcare.

Xerostomia aetiology

The origin of this disorder is multiple, and may be the result of a localized alteration on the saliva-producing glands , or the result of a systemic imbalance or alteration. Thus, among the possible causes of this disorder we find chronic diseases, highlighting uncontrolled diabetes mellitus , chronic tuberculosis , primary biliary cirrhosis, sarcoidosis , hemolytic anemia, malignant lymphomasand infection by the human immunodeficiency virus. In addition to the above, xerostomia may be the result of certain autoimmune disorders, such as Sjögren’s syndrome or systemic lupus erythematosus, or very frequently among cancer patients receiving treatment with polychemotherapy and radiation therapy in regions near the neck .

Saliva is produced in our body by a specialized glandular system for such effects and its function is none other than to protect the mucosa that lines the oral cavity against dental trauma and external agents. Its daily synthesis does not usually exceed 500 milliliters, approximately, of which 200 are secreted during the process of swallowing and ingesting food, and the remaining 300 as a moisturizing effect of the oral cavity in situations of non-ingestion of food .

Xerostomia pathogenesis

The decrease in salivary production in a subject is mediated by multiple processes and at different levels in terms of organic involvement. Thus, a decrease in its production could be caused by the presence of alterations at the level of the salivary centers of the central nervous system (CNS). In this type of distortion , symptoms such as anxiety , depression or psychosis will be involved , although certain organic diseases such as Alzheimer’s, postmenopausal syndrome or brain tumors may be the source of this salivary dysfunction.

Another reason for dysfunction in the salivary synthesis process is derived from alterations in the autonomic nervous system (ANS). At this level, peripheral innervation can be altered due to the use of certain pharmacological treatments such as cytostatics, among others, and the administration of radiotherapy and surgery in head and neck regions .

In the case of radiotherapy, it is known how ionizing radiation can cause alterations in the glands, their degree and severity being directly proportional to the intensity and time of exposure to radiation. Considering the degree of glandular involvement, we must highlight how the submandibular, sublingual, and especially the parotid, are more sensitive to the effects of radiation, as opposed to the minor glands, which show greater resistance to the action of radiation ionizing. Thus, radiation doses above 52 Gy will cause severe glandular dysfunction. In addition, modifications have been described at the level of salivary composition, motivated by exposure to radiation, among which we can highlight an increase in the concentration of substances such asproteins , calcium or sodium chloride, as well as a slight decrease in pH and its buffering capacity, with the consequent risk of oral infections.

In the case of chemotherapy, the effects on salivary production and its glands are less intense. This affectation by chemotherapeutic agents usually affects more the cells of the mucosa, reason why the appearance of ulcers and inflammation of these tissues (mucositis), accompanied by pain and burning mouth, is frequent.

But, without a doubt, the most specific process and the one with the greatest repercussion in relation to the development of this dysfunction in the salivary production process will be the direct involvement of the salivary glands. Glandular aplastic processes, as well as infectious symptoms at this same level, will be responsible for the possible establishment of a salivary deficit.

On the other hand, another reason for reducing the secreted salivary volume will be the possible existence of an obstructive picture at the level of the glandular saliva drainage and evacuation. This situation may be mediated by various processes, among which the presence of stones in the ducts of secretion (sialolithiasis), infectious glandular processes (sialoadenitis) and atresia of the secretory ducts should be highlighted, perhaps due to their greater frequency .

Clinical diagnosis and complementary tests

The evaluation of the degree of dysfunction of the salivary glands has been a basic objective for science. In this sense, there are numerous procedures and methods that are currently used in order to achieve an effective, early and highly efficient diagnosis.

In the first place, it is essential to prepare a clinical history aimed at isolating possible diseases underlying this symptom, as well as taking certain drugs with the ability to induce symptoms of hyposalivation, and thus symptoms of gingival hyperplasias .

In this personal interview with our patient, it will be of vital importance to ask questions about the amount and frequency of water ingested daily by him, as well as to ask about possible difficulties related to swallowing or sensations such as burning in the oral cavity. All this will guide us in the degree of suffering and intensity of this condition in our patient.

On the other hand, another procedure of great interest in the clinical diagnosis and evaluation of xerostomia will be the performance of an adequate clinical inspection of the patient’s oral cavity. Thus, we can observe the possible absence of saliva in the floor of the mouth, accompanied by a dry, erythematous, oral and lingual mucosa, to which fissures are frequently added. On the other hand, the presence of dental caries and episodes of gingivitis are frequent , further worsening the process.

Among the complementary tests to be carried out we find two main groups, the so-called quantitative tests, whose procedure is based on the quantification of saliva production, and, on the other hand, qualitative techniques, based on aspects related to the composition of saliva.

Quantitative measurements of salivary flow

Within this section we find the performance of sialometry as a star procedure, which constitutes an objective methodical process in determining salivary flow and is correlated with the degree of xerostomia. The performance of this technique will take place at the level of the different saliva-producing glands, or by determining the salivary volume produced by all of them together, which is called global salivary flow.

  • Partial determination of glandular salivary volume:
  • At the level of the parotid salivary glands. Cannulas are placed in the Stenon salivary ducts, and in many cases their placement is inconvenient and painful for the patient. Thus, currently the most widely used procedure is the implantation of the Laslhey capsules at the base of the mouth, which through a vacuum system will proceed to completely drain the saliva from the cavity. Through this procedure, the total salivary parotid volume can be quantified, considering flows of less than 0.3 ml / 15 minutes as pathological.
  • In minor salivary glands. The total salivary volume produced by these is collected, by applying absorbent paper strips at the level of these glands.
  • Mixed salivary measurement at rest. Within this section, the following techniques should be highlighted:
  • Saliva drainage and expectoration. The saliva produced is deposited in a graduated container for its subsequent quantification per unit of time. In the case of expectoration, the patient is invited to spit inside a graduated container for quantification.
  • Suction test. By means of this procedure, the total salivary production existing in the buccal soil is collected by means of a vacuum evacuator system.
  • Cotton Weight Test. The basis of this test lies in the application of three cottons on the secretion ducts of the parotid glands. After some time from their initial placement, they will be weighed in order to determine the difference in weight achieved by them from the absorption of the salivary glandular flow.
  • Sugar cube test. It takes place by placing a sugar cube at a specific location in the oral cavity, the lingual dorsum. Next, the time elapsed until the complete dissolution of the same fruit of the salivary secretion will be counted.
  • Oral Schimmer test. To carry out this test, a millimeter strip of paper approximately 1 cm wide by 17 cm long will be placed on the floor of the mouth. For its placement, it will be taken into account that the non-millimeter part is the one that contacts the ground and the millimeter is in a polystyrene bag. Thereafter, a period of 5 minutes is allowed to elapse in order for the saliva to soak the paper and thus the millimeters of impregnated paper can be read.
  • Saxon test. This test is carried out by placing a sponge inside the oral cavity in order for the patient to chew it. Then, it will be weighed in order to measure the salivary volume stored inside it.
  • Measurement of stimulated saliva. Through this technique we will obtain information regarding the secretory capacity of the salivary glands. The most widely used mechanism to stimulate the parotid gland is the use of citric acid or by chewing paraffin. Then, the tests discussed in the previous section will be used. Thus, the result of a parotid flow less than 0.5 milliliters / minute is a pathognomonic finding of glandular hypofunction.

Qualitative measurements of salivary flow

This type of procedure is based on the study of sialochemistry, or what is the same, the study of the different components of saliva and their concentrations in it. Thus, Na +, Cl-, amylase and bicarbonate concentrations are assessed. In this section, the determination of oral pH will also take place, which may be greatly affected after radiation exposures in patients treated with radiotherapy. In addition, the levels of certain immune proteins such as IgA and IgM immunoglobulins, which may affect their number in irradiated patients, may be assessed.

Other tests used

In addition to the aforementioned tests, there is another series of tests aimed at obtaining an accurate diagnosis of xerostomia. Next, we describe each one of them. • Sialography. It is a less used procedure in daily clinical practice. It consists of the inspection of the glandular secretion ducts. For this, the inoculation of a contrast (generally iodolipol or iodine) will be necessary, in order to visualize the permeability of the ducts, all from serial radiographs. • Scintigraphy with Tc 99 or scintigraphy. It is a non-invasive imaging test from which it will be possible to obtain a study of the morphology and function of the salivary glands. By using technetium 99 as a radiotracer, we will be able to assess the degree or severity of the dysfunction, the time of incorporation into the interior and the consequent excretion thereof. • Glandular biopsy. In this case, the biopsy of the salivary glands, and specifically of the minor glands, represents a simple procedure. After local anesthetic infiltration of the lower lip, a small incision will be made on thelabial mucosa , generally between the midline of the lip and its commissure, to then dissect the minor salivary glands. Another variant of biopsy is that based on glandular puncture, which is another of the possible ways of assessing glandular status.


Currently the number of patients who report having a constant feeling of dry mouth is considerable. It is precisely this high prevalence that should make xerostomia a symptom of potential research and study today.

Until now, xerostomia has only been addressed in a palliative way, and the results obtained are often mediocre in terms of effectiveness. Only through a thorough knowledge of its pathophysiology, as well as the possible agents that induce its appearance in patients, will we be in a position to improve its clinical and therapeutic approach. In the case of subsidiary patients receiving radiotherapy treatment, or in the case of those who already receive it, it is essential to maintain adequate oral and dental hygiene, since this contributes to improving their symptoms and avoiding the appearance of secondary complications. which could further obscure the picture.

Regarding the prescription of medications , it is essential that the physician consider and accurately assess the type of drug to be prescribed in all those patients who are susceptible to developing this condition. The potential for toxicity that a large group of drugs pose to the oral mucosa is known .

Therefore, we believe that its prevention should be carried out from daily practice, both by health personnel, taking advantage of the potential that health education has in its daily practice, as well as by the patients themselves. Our desire with this work is to contribute with an updated review of the subject and to promote the investigation of this symptom, since its therapeutic approach seems not to be tacitly clear even in the present.


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