Chemical-physical characteristics of artificial saliva substitutes: rheological evaluation.

OBJECTIVE: We aimed at evaluating some chemical-physical properties of artificial saliva substitutes easily available on the E.U. market, such as viscosity, pH, buffering capacity, superficial tension, density and spinnbarkeit and to compare the results with human natural saliva bibliographic data. MATERIALS AND METHODS: Based on the easy availability on the market, twelve artificial saliva solutions in liquid formulation were analyzed. Kinematic viscosity (cSt) was determined using a micro-Ubbelohde model capillary viscosimeter (ViscoClock, SCHOOT-GERATE Mainz, Germany). Dynamic viscosity (mPas) was determined, through a simple multiplication between density (g/cm3) and kinematic viscosity of each solution. pH analyses were carried out at room temperature using a pH-meter (Mettler Toledo®- Five Easy, Columbus, OH, USA). Spinnbarkeit analysis was performed by a self-owned instrument built for the purpose. RESULTS: The median density value, obtained from the cohort of artificial saliva substitutes, was 1.036 g/cm3. The median value of the kinematic viscosity was 8.984 cSt. The median spinnbarkeit value was 3.2 mm and the median pH value was 6.29. In this study we found an almost linear correlation between the kinematic viscosity and spinnbarkeit values of the artificial saliva substitutes evaluated. CONCLUSIONS: Saliva substitutes should be as faithful as possible to the characteristics of human saliva, in order to completely replace its functions in the oral cavity. Nevertheless, despite several R&D efforts, it is difficult to reproduce all the different features that belongs to natural saliva in one device. Therefore, it would be desirable to create more products reproducing saliva with various rheological characteristics in respect of the main salivary functions such as: chewing, speaking and tissue coating.

Changes in salivary flow rate and pH in pregnancy.

OBJECTIVE: To evaluate changes in pH and Flow Rate (FR) of the Unstimulated Whole Saliva (UWS) in a sample of pregnant women in different gestational periods. PATIENTS AND METHODS: After collecting demographic data and medical histories, as well as conducting an oral examination, a sample of pregnant women were instructed on how to prepare prior to the sample collection. At a time between 11.00 and 12.00 a.m., they were subjected to salivary collection (spitting method, time 5 minutes); the measurement of FR was carried out using a professionally calibrated precision scale and the pH with a portable pH meter. RESULTS: The average FR of the women's detected sample (0.40 ± 0.20 ml/min) was lower than that of non-pregnant women (0.48 ± 0.15 ml/min) of the same age (p <0.05). We observed an increase (p <0.001) of FR in the first trimester (0.56 ± 0.20 ml/min) compared to second (0.34 ± 0.14 ml/min) and third (0.31 ± 0.14 ml/min) trimester. The salivary pH of pregnant women was lower than the one detected in the non-pregnant women's sample (p <0.0001). CONCLUSIONS: Our study highlighted an increase in the FR in the first trimester compared to that detected in the second and third trimesters of pregnancy which viceversa was lower than the average FR in non-pregnant women. This data, combined with the decrease in salivary pH, supports the hypothesis that correlates the FR increase with the attempt to counter the decrease in pH due to gastric regurgitation frequent in the first trimester. Further studies are necessary to evaluate salivary FR and pH in pregnant women samples related to the emesis phenomenon.

Salivary pH and flow rate in menopausal women.

OBJECTIVE: This study aims at determining pH and Flow Rate (FR) of Unstimulated Whole Saliva (UWS) in a sample of 120 ♀ (60 menopausal women and 60 healthy fertile women with similar mean age); detecting the DMFT index (Decayed, Missing, Filled Teeth index) and evaluating any correlations between pH, FR, age and DMFT. PATIENTS AND METHODS: Concerning the day before sample collection, patients were advised to keep a relaxed attitude and not to practice sports. They were also told to not eat or drink during the hour preceding sampling procedures. Saliva was collected via "spitting" method. Each sampling session started at 11:00 a.m., lasted for 5 minutes and used a pre-weighed, dry, deionized and sterile test tube. The procedure took place under controlled environmental temperature and humidity conditions (means 23.27°C; 60.08%). FR was evaluated via weighing technique and pH was measured with a portable pH-meter. RESULTS: There was a minimal but significant pH difference (0.11; p<0.05) between menopausal women (6.75 ± 0.34) and fertile women (6.86 ± 0.24); and a FR difference (0.19; p<0.0001) between menopausal women (0.29 ± 0.17 mL/min) and fertile women (0.48 ± 0.19 mL/min). Correlation (R2) between pH and age was 0.0135 for fertile women and 0.0055 for menopausal women; while the correlation between FR and age was 0.0673 for fertile women and 0.139 for menopausal women. Mean DMFT was 11.93 ± 7.14 in menopausal women and 12.23 ± 6.37 in fertile women. CONCLUSIONS: We observed a minimal decrease in pH and a decrease in FR in menopausal women. Further studies will be needed to investigate the possible role of other environmental and individual variables in the determination of such values.

Evaluation of salivary surface tension in a cohort of young healthy adults.

OBJECTIVE: To determine salivary pH, flow rate (FR) and surface tension (γs) in a cohort of 30 healthy young adults. To acquire cohort biological independent variables (age, gender, weight, height, medications, smoking, pathologies, and allergies) and to correlate them with pH, FR and γs obtained values. Evaluate the possible variation of the γs values during the time after the withdrawal and the influence of the operational abilities of the experimenting operators. Evaluate the relationship between γs, pH and FR  and the dependence between pH and FR. PATIENTS AND METHODS: Non-stimulated saliva samples were taken in four different time span, for three days, with a drooling method for 15 minutes. The saliva sample was analyzed, in terms of γs, by two different operators (OP1 and OP2), twice consecutive (γs-1 and γs-2) for a total of 360 measurements. The γs was calculated using the du Noüy method. The FR was evaluated by weighing technique and pH by pH indicator papers. RESULTS: The measurements of γs performed by two different operators (OP1, OP2) showed respectively average values of 46.46 mN/m and 43.45 mN/m, while the mean FR was 0.29 ± 0.13 mL/min and the average pH was 7.1 ± 0.43. There were no significant correlations between γs and the biological variables analyzed. CONCLUSIONS: We can consider as reference values, in a sample of young adults, γs 45.56 ± 6.51 mN/m.

Salivary flow rate and pH in patients with oral pathologies.

OBJECTIVE: Determine salivary pH and flow rate (FR) in a sample of 164 patients who came to Oral Pathology ambulatory, 84 suffering from oral lesions and 80 without oral lesions. Another aim was to evaluate factors that influence salivary flow rate. PATIENTS AND METHODS: Subjects underwent clinical examination and completed an anamnestic questionnaire in order to obtain useful information that was used to classify participants in different groups. Unstimulated whole saliva (UWS) was collected using the spitting method at 11:00 am. The FR was evaluated with the weighing technique and a portable pHmeter, equipped with a microelectrode, was used to measure pH. Both univariate and classification (single and Random Forest) analyses were performed. RESULTS: The data analysis showed that FR and pH showed significant differences (p < 0.001) between patients with oral lesions (FR = 0.336 mL/min, pH = 6.69) and the ones without oral lesions (FR = 0.492 mL/min, pH = 6.96). By Random Forest, oral lesions and antihypertensive drugs were ranked in the top two among the evaluated variables to discretize subjects with FR = 0.16 mL/min. CONCLUSIONS: Our study shows that there is a relationship between oral lesions, antihypertensive drugs and alteration of pH and FR.

Determination of breath alcohol value after using mouthwashes containing ethanol in healthy young adults.

OBJECTIVE: To evaluate breath alcohol value and blood alcohol concentration after using mouthwashes containing ethanol in a panel of healthy young adults. To determine zeroing time of these values and if subjects' body mass index or gender influenced it. Breathalyzer test is a practice performed to detect alcohol-impaired-drivers that can be penalized. Sometimes Italian judges revoke the penalty justifying that the presence of residual ethanol in the oral cavity can cause false positive values. PATIENTS AND METHODS: Our study involved 40 young adult volunteers; the cohort was composed of University students aged between 21 and 30 years. They underwent a medical examination to evaluate BMI. We selected four alcoholic mouthwashes available on the market with a different ethanol amount and an ethanol/ water (10/90) mixture as a reference. Breath alcohol concentration values were collected using a portable breathalyzer immediately after the rinse (T0), after 10 and 20 minutes (T10 and T20). We evaluated blood alcohol concentration 5 minutes after the rinse. RESULTS: All T10 values are lower than 0.5 g/L (Italian BAC driving limit). Differences between average values at T0-T10 are statistically significant (p < 0.05). Correlations between BAV and BMI are not statistically significant respectively at T0 (A: p = 0.54. B: p = 0.96. C: p = 0.93. D: p = 0.53) and T10 (A: p = 0.42. C: p = 0.99. D: p = 0.66). Differences between male and female groups aren't statistically significant (A: p = 0.49; B: p = 0.79; C: p = 0.97; D: p = 0.06). CONCLUSIONS: High BAV values determined at T-0 are a consequence of residual ethanol present in the oral cavity, the zeroing time of these ones (oppure thereof) is very swift. Our study shows that rinsing with an alcoholic mouthwash before undergoing the breathalyzer test does not realistically influence the result.

Kinematic viscosity of unstimulated whole saliva in healthy young adults.

OBJECTIVE: To analyze kinematic viscosity and pH of unstimulated whole saliva, evaluate possible variations after sampling, identify any gender differences and detect possible correlations between them. SUBJECTS AND METHODS: The sample consisted of sixty-four healthy young adults (37 females and 27 males, mean age 25.2 years). Saliva was collected using the spitting method at 11:00 am. Kinematic viscosity was determined with a capillary viscometer (ViscoClock, Schott-Geräte Mainz, Germany) equipped with a micro-Ubbelohde capillary. Viscosity and pH were measured at a temperature of 36 °C in a thermostatic bath. Viscosity and pH data were evaluated almost simultaneously at six different times after sampling in order to identify any variations due to aging. The data were statistically analyzed using Student's t test and Wilcoxon-Mann-Whitney test. RESULTS: In total sample kinematic viscosity was 1.40 cSt (SD = 0.39; RSD % = 27.81), in the male and female groups was 1.33 cSt (SD = 0.35, RSD% = 26.31) and 1.45 cSt (SD = 0.41, RSD % = 28.45) respectively; the difference was not statistically significant. Viscosity decreased exponentially as a function of time after sampling then reaching a plateau around 1.12 cSt, while the pH values increased linearly. There was a trend of pH to decrease while viscosity decreases. CONCLUSIONS: Kinematic viscometry could be a valid tool to evaluate salivary viscosity. Degradation of saliva after sampling affects viscosity and slightly pH. The use of capillary viscometer to evaluate salivary aging needs more improvements. Further studies are required to investigate and explain the effects of different techniques to reduce the film forming on the air/liquid interface during measurement.

Daily and annually variation of unstimulated whole saliva flow rate and pH and their relation with body profile in healthy young adults.

AIM: To analyse pH and flow rate (FR) of unstimulated whole saliva (UWS), detecting their possible correlations both among themselves and with body profile; in addition to identify daily, annually and gender differences. MATERIALS AND METHODS: Eighty-one (47 ♀; 34 ♂) healthy young adults (mean age 22.7±4.09 years old) were enrolled. Saliva was sampled using spitting method. The data were statistically analysed using Pearson's coefficient, ANOVA or Kruskal-Wallis test, Student's t test or the Wilcoxon-Mann-Whitney test. RESULTS: The mean UWS/FR was 0.643 ml/min (range 0.164-1.656 ml/min; percentile 25 = 0.400 ml/min; percentile 50 = 0.643 ml/min, percentile 75 = 0.832 ml/min; median = 0.590 ml/min) and no significant differences were found in gender. The mean UWS/pH was 6.95 (range 6.06-7.91, S.D. 0.28, RSD % 4.08): pH was higher in males (7.02) than females (6.92; p = 0.009). The UWS/FR increased almost steadily during the day: from 0.593 ml/min at 9:00 to 0.669 ml/min at 17:00 (p = 0.04), the greatest increase was found between 9:00 and 11:00. Through the seasons the UWS/FR decreased from summer to spring with a difference of 0.048 ml/min (p < 0.05). The UWS/pH showed a slight increase between 9:00 and 17:00 (p < 0.05). There were little differences in UWS/pH among the seasons (max. 0.09; p < 0.05). Only a significant correlation between UWS/FR and pH was found (R = 0.20; p = 0.008). CONCLUSIONS: We did not find correlations between body profile vs UWS/FR or pH. UWS/FR varies more widely than UWS/pH: maintaining a proper acid/base balance is an essential factor for the homeostasis of the oral cavity and probably this would explain the reason for the lack of the variables evaluated influencing UWS/pH.

Incisor and mandibular movement during retrusion.

Human mastication, respiration, speech, swallowing and suckling are directed by the jaw muscle activites, the temporo-mandibular joints, the ligaments and by the occlusal dental contacts. Mastication is usually assessed by border movements of the mandibular incisors. While the border movements of opening, protrusion and lateratrusion are often used to determine the mandibular functions, the movement of retrusion is rarely considered in the study of the human oro-facial functions. Our purpose was to evaluate the mandibular movement of retrusion in a population that did not present any symptoms nor clinical signs of temporo-mandibular disorders. The study was performed on 117 males and 121 females (age range: 17.7-65.2 years; mean age: 31.1 years) using electrognathographic registrations (Sirognatograph(*), Siemens, Benshein, Germany). Every patient was instructed and trained before recording. The measurements were calculated on the sagittal plane registrations. The results showed that the mandibular movement of retrusion was present in 233 out of the 238 studied subjects (97.9%) whatever was the dental class, the age or the sex. The width range was between 0.3 and 5.4 mm and the mean value was 1.75+/-0.91 mm. The inferential analysis performed by a 3-way ANOVA model demonstrated no significant difference in retrusion value by dental class, gender or age. The most frequent numerical value was 1.5 mm, observed in 16 subjects (6.7% of the studied population). These results suggest that, in order to respect the physiological characteristics, more attention is needed in performing dental treatments.