Design and interpretation of clinical research studies in oral medicine: a brief review.

The objective of this short review is to help researchers improve the designs of their clinical studies. Also included is a discussion of the level of evidence provided by the various clinical research study designs.

Pilocarpine treatment of salivary gland hypofunction and dry mouth (xerostomia).

We studied the effects of pilocarpine hydrochloride, a para-sympathomimetic agent, on major salivary gland output and subjective responses in 31 patients with salivary hypofunction. Pilocarpine hydrochloride (5-mg capsules, three times daily) was given for 5 months and a placebo was randomly assigned for 1 month in a double-blind fashion. Objective measurements of major salivary gland output, subjective impressions of oral moisture, treatment-related side effects, and a number of physiologic measures were assessed monthly. Pilocarpine significantly increased salivary output in 21 of the 31 patients. Subjective improvement in the feeling of oral dryness, speaking, chewing, and swallowing were reported by 27 individuals. Side effects, while common, generally were mild and tolerable. There were no significant alterations in cardiovascular or other physiologic measures. We conclude that pilocarpine is an effective and safe treatment for salivary gland hypofunction and xerostomia in selected patients. The increase in major gland output provides beneficial natural secretions and relief of oral dryness.

Repetitive adenovirus administration to the parotid gland: role of immunological barriers and induction of oral tolerance.

This study assessed the mucosal and systemic immune responses following repetitive adenoviral vector instillation to the parotid glands. Also, we investigated the feasibility of oral tolerance induction as a rational strategy to overcome the immunological reactions. The replication-deficient recombinant adenovirus vector AdCMVCAT was instilled into rat parotid glands. Chloramphenicol acetyltransferase (CAT) activity in the parotid was observed after a first or second AdCMVCAT infection, but not after a third vector administration. ELISA assays showed increased anti-adenovirus immunoglobulin G (IgG) and IgM in serum, and also anti-adenovirus IgA in gland extracts and saliva after virus administration. The results of in vivo neutralization experiments demonstrated that salivary IgA and IgM prevented reinfection of the parotids with adenoviral vectors. Subsequently, studies were conducted to induce tolerance to adenovirus by peroral feedings of ultraviolet (UV)-inactivated virus before gene administration to the parotid glands. Between 3 and 13 doses of virus were fed to rats. Final parotid gene expression was dependent on the number of viral feedings and the amount fed. Tolerized animals showed prolonged and heightened gene expression in the salivary glands compared to control animals and displayed gene expression even after three administrations of vector. Mononuclear cells from the spleens of these animals showed reduced proliferation following adenovirus stimulation. This same cell population was depleted of CD8+ T cells and found to produce less interferon-gamma (IFN-gamma) after virus challenge. This profile indicates the down regulation of Th1 cell-mediated responses. These results indicate that oral tolerance induction is a potentially useful adjunct to virus-based gene therapy.

Polarized secretion of transgene products from salivary glands in vivo.

Previously (Kagami et al. Hum. Gene Ther. 1996;7:2177-2184) we have shown that salivary glands are able to secrete a transgene-encoded protein into serum as well as saliva. This result and other published data suggest that salivary glands may be a useful target site for vectors encoding therapeutic proteins for systemic delivery. The aim of the present study was to assess in vivo if transgene-encoded secretory proteins follow distinct, polarized sorting pathways as has been shown to occur "classically" in cell biological studies in vitro. Four first-generation, E1-, type 5 recombinant adenoviruses were used to deliver different transgenes to a rat submandibular cell line in vitro or to rat submandibular glands in vivo. Subsequently, the secretory distribution of the encoded proteins was determined. Luciferase, which has no signal peptide, served as a cell-associated, negative control and was used to correct for any nonspecific secretory protein release from cells. The three remaining transgene products tested, human tissue kallikrein (hK1), human growth hormone (hGH), and human alpha1-antitrypsin (halpha1AT), were predominantly secreted (>96%) in vitro. Most importantly, in vivo, after a parasympathomimetic secretory stimulus, both hK1 and hGH were secreted primarily in an exocrine manner into saliva. Conversely, halpha1AT was predominantly secreted into the bloodstream, i.e., in an endocrine manner. The aggregate results are consistent with the recognition of signals encoded within the transgenes that result in specific patterns of polarized protein secretion from rat submandibular gland cells in vivo.

Elevation of salivary antimicrobial proteins following HIV-1 infection.

Thirty-seven HIV-1-positive patients contributed salivary samples from individual major salivary glands. Nineteen patients were unmedicated and asymptomatic, and 18 patients had developed signs of AIDS. Salivas from 15 healthy males served as controls. Levels of four salivary antimicrobial proteins (lactoferrin, lysozyme, secretory IgA, and histatins) were determined, as well as total fluid output of the major salivary glands. Concentrations of all four salivary antimicrobial proteins were found to be increased in the stimulated submandibular/sublingual saliva of all HIV-1-positive patients as well as the subset of unmediated HIV-1-positive patients. Those patients with evidence of oral candidiasis had the highest concentrations of lysozyme and histatins, potent antifungal proteins, in their saliva. Although the etiology of these protein increases is still unknown, these results further document salivary changes following HIV-1 infection.

Oral defense mechanisms are impaired early in HIV-1 infected patients.

We have examined the hypothesis that individuals infected with human immune deficiency virus type 1 (HIV-1) experience significant, specific alterations in mechanisms protecting the oral cavity prior to the appearance of AIDS-related systemic opportunistic infections. In a study of 13 early-stage, stable anti-HIV antibody positive patients, parotid salivary function was found to be generally intact. In contrast, several indicators of submandibular gland dysfunction were detected. In particular, stimulated fluid output was decreased and salivary lysozyme levels were increased relative to controls by 50-60% for both resting (p less than 0.05) and stimulated (p less than 0.001) conditions. Also, the frequency of albumin detection in submandibular saliva samples was approximately 65% in HIV-1 infected patients vs. 0% in controls (p less than 0.05). In addition, cytologic evaluation of oral mucosa revealed a fivefold increase in the prevalence of candidal hyphae in HIV-1 infected patients compared to controls (41% vs. 8%, p less than 0.05). We conclude that normal oral defense mechanisms show signs of compromise in HIV-1 infected individuals. We suggest that (a) effects of HIV-1 infection are seen early in the oral cavity, (b) impairment of oral defense mechanisms may facilitate entry of microorganisms with an attendant increased risk of morbidity and mortality, and (c) intensive oral surveillance and prophylactic care should be part of the routine management afforded to AIDS patients soon after HIV-1 infection is recognized.

Major salivary gland function in patients with radiation-induced xerostomia: flow rates and sialochemistry.

Radiation therapy for cancer of the head and neck region often causes salivary gland dysfunction and xerostomia. Several reports suggest that the submandibular/sublingual (SM/SL) glands may be less radiosensitive than the parotid. The purpose of this study was to evaluate differential radiation effects on the major salivary glands. Fifty patients with radiation-induced xerostomia were evaluated (33 males, 17 females; mean age 52.7). The average total tumor dose was 6034 cGy. Major salivary gland function was compared with that of 50 non-irradiated controls. Salivary flow rates included unstimulated and stimulated flows of both the parotid and SM/SL glands. Sialochemical analyses included total protein, lysozyme, lactoferrin, sodium, chloride, and potassium. All four measures of salivary flow were significantly reduced in patients as compared to controls (p = .0001). Like the parotid, submandibular/sublingual gland dysfunction appears to be radiation dose- and field-dependent. Patients in the lowest radiation dose quartile (< or = 5000 cGy) had significantly increased salivary flow compared to those in the highest dose quartile (> or = 6800 cGy; p = .025). Glands that were partially irradiated were more likely to have some residual function than fully irradiated glands (p = .003). Lactoferrin content was increased in parotid saliva of radiation patients (p = .0001). Chloride content was significantly increased also (p = .0001). The SM/SL glands are clearly dysfunctional in post-irradiation xerostomia patients compared to controls, in terms of both flow rates and sialochemistry.

Dental health and viridans streptococcal bacteremia in allogeneic hematopoietic stem cell transplant recipients.

Viridans streptococci were the most common cause of bacteremia in 61 consecutive myeloablative allogeneic hematopoietic stem cell transplant (HSCT) recipients, occurring in 19 of 31 bacteremic patients (61%) during the period of post-transplant neutropenia. Seven of the 19 had more than one viridans streptococcus in the same blood culture. Twenty isolates from 15 patients were Streptococcus mitis. Most viridans streptococci were resistant to norfloxacin, used routinely for prophylaxis. Comparison of the 19 patients with viridans streptococcal bacteremia with a contemporaneous group of 23 allogeneic HSCT recipients with fever and neutropenia but no identified focus of infection found that patients with viridans streptococcal bacteremia were more likely to have severe intraoral pathology while neutropenic (26% vs 0%) and slightly shorter interval between the last dental procedure and the onset of neutropenia (11 vs 14 days). Poor underlying dental health and the use of norfloxacin thus appear to predispose to viridans streptococcal bacteremia.

Adenoviral-mediated gene transfer to mouse salivary glands.

Adenoviral vectors effectively transfer genes to rat salivary glands. However, potent immune responses limit their use in vivo. Mice offer more opportunities than rats for the study of these immune processes. We first established conditions for infection of mouse salivary glands, with an adenoviral vector. The effects of time, viral dose, viral diluent buffer volume, and dexamethasone on expression of a transgene, luciferase, were determined by means of the recombinant vector AdCMVluc. Optimal luciferase expression was observed when the vector was suspended in 50 microL of buffer. This volume completely filled the gland parenchyma and slightly distended the capsule. Dexamethasone increased immediate transgene expression and reduced the acute inflammation one day following viral administration, but did not alter subsequent mononuclear inflammation or transgene expression 14 or 28 days later. An adenoviral vector encoding either anti-inflammatory cytokine IL-4 or IL-10 was co-administered with AdCMVluc to increase transgene expression at 14 and 28 days. While this strategy did not extend the duration of luciferase expression, co-administration of AdCMVIL-10 with AdCMVluc almost completely eliminated the chronic inflammatory infiltrate in the glands after 28 days. This study demonstrates that adenoviral-mediated gene transfer to mouse submandibular glands is possible by intraductal cannulation and that reduction of either the acute or chronic inflammatory infiltrates was insufficient to increase long-term transgene expression in this tissue.

Prednisone and piroxicam for treatment of primary Sjögren's syndrome.

Primary Sjögren's syndrome is a systemic autoimmune exocrinopathy characterized by a lymphoplasmacytic infiltrate and destruction of salivary and lacrimal glandular tissues. There is no widely accepted or effective systemic therapy for this disorder. The purpose of this 6-month randomized, double-blinded, placebo-controlled study was to examine the effects of prednisone (30 mg, alternate days), piroxicam (20 mg, daily), or placebo on the salivary, lacrimal and immunologic alterations of primary Sjögren's syndrome. Eight patients were enrolled in each group. Salivary and lacrimal function were assessed at entry and at the completion of treatment. Labial minor salivary gland tissue was obtained at these times and examined for intensity of infiltration (focus scores) and for the relative proportion of glandular elements. Serologic and subjective evaluations were done as well, and patients were monitored for therapy-related side effects. Neither active treatment led to significant improvement in salivary or lacrimal function, although prednisone improved salivary flow in selected patients and was associated with positive subjective responses. Prednisone also significantly decreased the serum total protein, IgG, IgA, and sedimentation rate and increased the white cell count. There were no significant alterations in either focus scores or the percentage of glandular component tissues of minor glands with either active treatment. This study demonstrated that 6 months of prednisone or piroxicam at the doses utilized failed to improve the histological or functional parameters of salivary and lacrimal glands in primary Sjögren's syndrome.

Taste performance in Sjogren's syndrome.

Sjogren's Syndrome (SS) patients have impaired salivary gland function and an elevated frequency of oral complaints. The taste complaints are thought to be due to sensory deficits that arise in the absence of sufficient saliva to maintain taste receptors. We assessed the subjective complaints, salivary production and taste functioning of SS patients and unaffected individuals. We found the expected decreased salivary gland function and increased frequency of taste complaints. Our taste assessment with weak stimuli confirmed and expanded the previous report of decreased taste threshold sensitivity in SS. However, perception of stronger taste stimuli was not impaired. In contrast with previous reports, patient judgments of intensity were not significantly reduced for any of the four taste qualities. Although the salivary gland function of all patients was markedly impaired relative to that of controls, patients lacking measurable salivary flow were no more likely than patients with residual function to exhibit subjective complaints or taste impairments. Our observations are inconsistent with a simple causal chain running from salivary gland dysfunction to sensory loss to taste complaints.

Salivary gland dysfunction.

Clinically significant declines of salivary output are not a function of aging. Complaints of oral dryness (xerostomia) are common in the elderly patient, however. This complaint is most often a consequence of medications; tricyclic antidepressants, certain antihypertensives, and anticholinergics can cause marked decreases in salivary flow rates. Other medications such as diuretics may cause xerostomia without decreasing salivary output. Systemic diseases such as Sjögren's syndrome can destroy salivary glands. Specific serologic, ophthalmologic, and salivary findings are necessary for the diagnosis of Sjögren's syndrome. Radiation therapy for treatment of head and neck cancers also can damage salivary glands permanently. Infectious agents such as mycobacteria, Epstein-Barr virus, and various oral bacteria can infect human salivary glands. Diminished salivary output can lead to serious oral sequelae. Rapidly progressing dental caries and oral candidiasis are found frequently in this age group. Close supervision of the geriatric patient's oral and dental health is essential.

Oral manifestations in patients with aplastic anemia.

OBJECTIVE: The aim of the present study was to characterize the prevalence and risks of oral complications in aplastic anemia (AA). STUDY DESIGN: Approximately 79 patients with AA (age, 37 +/- 17 years) and 66 control patients with schizophrenia (age, 33 +/- 12 years) were examined. Records were reviewed for demographic, clinical, and radiographic information. Prior medical therapy, laboratory values, disease duration, and medical treatment response were noted for patients with AA. Odds ratios (OR) and 95% CI were calculated for oral manifestations in cases and in control subjects. Univariate analysis identified important variables for logistic regression. RESULTS: Patients with AA presented more frequently with oral petechiae (OR = 49; 95% CI, 2.9-825), gingival hyperplasia (OR = 27; 95% CI, 1.6-463.5), spontaneous gingival bleeding (OR = 27; 95% CI, 1.6-463.5), and herpetic lesions (OR = 27; 95% CI, 1.6-463.5). Prior cyclosporine use was associated with gingival hyperplasia (P =.0001). No other predictors for oral manifestations or treatment outcomes were found. CONCLUSIONS: Oral soft tissue changes and infections were more common in patients with AA. Prior cyclosporine use was predictive of the presence of gingival hyperplasia.

Sjogren's syndrome: oral and dental considerations.

Patients with Sjogren's syndrome have many oral health needs. Due to the extensive oral involvement, dentists may be the first to recognize this condition. Characteristics and treatment options for this disorder are discussed and three case histories are presented.

Salivary gland dysfunction: causes, symptoms, treatment.

The three most common known causes of salivary gland dysfunction are medication usage, radiation therapy and Sjogren's syndrome. Current therapeutic options to treat salivary dysfunction are limited. Clinical considerations as well as the outlook for individuals experiencing salivary dysfunction are discussed.

Oral manifestations of primary immunological diseases.

BACKGROUND: Primary immunodeficiencies have many oral manifestations. The clinical presentation of these diseases demonstrates the roles of different immune cells for the maintenance of oral health. METHODS: The authors reviewed selected literature describing systemic and oral manifestations of the primary immunodeficiencies published between 1966 and 1999. RESULTS: The authors found that oral candidiasis and herpetic infections are seen frequently in patients with T-cell deficiencies, while patients with B-cell deficiencies are most susceptible to bacterial infections. Periodontitis and oral candidiasis are found in some, but not all, phagocyte deficiencies. CONCLUSIONS: These findings demonstrate that T cells, B cells and phagocytes all have roles in oral immunity. CLINICAL IMPLICATIONS: Acquired conditions that affect the immune system such as diabetes, alcoholism and acquired immunodeficiency syndrome, as well as certain medications, will affect oral defense mechanisms. The effects that acquired immunodeficiencies will have on oral health can be predicted from the oral manifestations of primary immunodeficiencies.

Salivary inhibition of HIV-1 infectivity: functional properties and distribution in men, women, and children.

Human salivary gland secretions inhibit infection of human lymphocytes by the human immunodeficiency virus 1 (HIV-1), the causative agent of the acquired immune deficiency syndrome (AIDS). This activity was found in saliva collected directly from the orifice of the major salivary gland ducts and the whole saliva of healthy male volunteers. In the current report, the observations on salivary secretions are expanded to a greater number of individuals, including healthy women and children, and men infected with HIV-1.

Oral manifestations associated with leukocyte adhesion deficiency: a five-year case study.

A five-year case study of a child with leukocyte adhesion deficiency is presented. The report describes the generalized progressive periodontitis and intraoral infections associated with both the primary and permanent dentition. The associated therapeutic challenges and largely unsuccessful treatment regimens utilized in the attempts to arrest the periodontal disease are described.

Salivary enhancement: current status and future therapies.

Saliva provides the principal protective milieu for teeth by modulating oral microbial ecosystems and reversing the initial phases of caries development. Patients with inadequate salivary function are at increased risk for dental decay. Therefore, it is likely that therapies that increase overall fluid output of these individuals will reverse early carious lesions. The most common causes of salivary dysfunction are medication usage, Sjögren's syndrome, and damage of salivary parenchyma during therapeutic irradiation. For patients with remaining functional acinar tissue, treatment with the parasypathomimetic secretogogues pilocarpine and Cevimeline may provide relief. However, these medications do not benefit all patients. The possibilities of using gene therapy and tissue engineering to develop treatments for those with severe salivary dysfunction are discussed.