Saliva and gastrointestinal functions of taste,mastication, swallowing and digestion

Saliva has multiple essential functions in relation to the digestive process taking place in the upper parts of the gastrointestinal (GI) tract. This paper reviews the role of human saliva and its compositional elements in relation to the GI functions of taste, mastication, bolus formation, enzymatic digestion, and swallowing. The indirect function of saliva in the digestive process that includes maintenance of an intact dentition and mucosa is also reviewed. Finally, pathophysiological considerations of salivary dysfunction in relation to some GI functions are considered.     

Influence of pH and storage time on the sorption and solubility behaviour of three composite resin materials

OBJECTIVES: The aim of this study was to determine whether pH and time has any influence on the sorption and solubility behaviour of composite resin materials stored in a buffer solution. METHODS: Three hybrid composite restorative resin materials (Spectrum, Z-100 and ArtGlass) with different matrix structure and filler composition were studied. One hundred and twenty specimens of each material were produced according to ISO 4049. The materials were stored in McIlvain's buffer solution at different pH (4, 6 and 8) at 1, 7, 60 and 180 days. pH measurements were carried out before and after completed storage. RESULTS: Time had a significant influence on the sorption and solubility behaviour of the composite resin materials tested. One of the materials Z-100 showed a significant mass increase and/or decrease depending on the pH of the solution. The material Spectrum was significantly influenced by pH, resulting in different sorption depending on the pH of the solution. CONCLUSIONS: Time of storage was important for the sorption and solubility behaviour of the composite resin materials tested. Comparison of solubility for one of the materials showed twice as high values in the present study as previously reported when distilled water was used as storage medium. pH in the solution seems to have an influence on the sorption and solubility behaviour of composite resin materials. The sensitivity of the sorption and solubility behaviour to time and pH of the materials tested seems to be related to the hydrophilicity of the matrix and the chemical composition of the filler.     

The effect of acid etching on vascular diameter of pulp-vessels in rat incisor (vitalmicroscopic study)

Conditioning agents used on dentin with composite materials are biologically active and may have deleterious effects on the pulpal microcirculation. No data are available on the immediate vascular effect of etching materials applied on a constant thin pulpal dentin. In this study the authors examined whether the application of 36% phosphoric acid (Conditioner 36, 15 seconds) or itakonic acid with 10% maleic acid (NRC Non-Rinse Conditioner, 20 seconds), as recommended by the manufacturers, alters the blood circulation in the pulp of the rat's lower incisors. The effect of prolonged etching time (60 seconds) was also assessed (Conditioner 36). The application of saline served as the untreated control. The technique of vitalmicroscopy was used on the first lower incisor of 40 (10-10 in each group) male Sprague-Dawley rats (weighing 350 +/- 8 g SE) to record the changes in vessel diameter prior to and at 5, 15, 30 and 60 minutes after the test materials were administered on the dentin. In the control rats, the vessel diameter was stable during the entire experiment. Acid conditioning as recommended by the manufacturers tended to cause vasodilatation, though these alterations were statistically not significant when compared to the control group (ANOVA, p > 0.05). After prolonged etching time (Conditioner 36, 60 seconds) significant vasoconstriction (-14.4 +/- 6.13; -10.59 +/- 4.2; -11.96 +/- 6.75; -5.49 +/- 5.78%) was observed (ANOVA, p < 0.05). In this group, stasis developed in pulpal blood circulation in 40% of rats (Cochran's-Q test, p < 0.05), gas-bubble formation was observed in 30% and the disappearance of the pulpal wall occurred in 20%. These results suggest that exposition time with acid is crucial to the pulpal microcirculation. That is, acid conditioning applied as indicated (for 15-20 seconds) onto a very thin layer of dentin only slightly affects the blood supply to the dental pulp; however, prolonged etching time (for 60 seconds) results in immediate failure of microcirculation in the dental pulp of rats.     

Nickel and chromium levels in the saliva and serum of patients with fixed orthodontic appliances

The aim of this study was to evaluate the concentrations of nickel and chromium ions in salivary and serum samples from patients treated with fixed orthodontic appliances. A second aim of this study was to determine any significant changes in these concentrations during any period of the treatment time. Saliva and blood samples were collected from 100 patients ranging in age from 12 to 33 years. Twenty samples from each group were obtained. The groups were as follows: In the first group, saliva and blood samples were collected before insertion of the fixed appliances. In the second, third, fourth, and fifth groups, samples were collected at 1 week, 1 month, 1 year, and 2 years after appliance insertion. The serum was prepared by centrifuging the blood samples at 3000 rpm for 10 minutes. The fixed appliances consisted of an average of 4 bands and 20 bonded brackets. No palatal or lingual appliances welded to bands or extraoral auxiliary appliances were used. The spectrophotometric determinations were carried out using electrothermal atomic absorption spectrophotometry. The results indicated certain differences in the amounts of nickel and chromium released from fixed orthodontic appliances during different periods of treatment. The Mann-Whitney U-test from the SPSS statistics program was used to analyze the significance of the differences between no-appliance samples and those obtained with the appliances present. In the serum, there were statistically significant increases in ion concentration in the second-year groups. In saliva samples, nickel and chromium reached their highest levels in the first month and decreased to their initial level in the rest of the groups. It can be concluded that fixed orthodontic appliances release measurable amount of nickel and chromium when placed in the mouth, but this increase doesn't reach toxic levels for nickel and chromium in the saliva and serum.     

Shear strength after ethylenediaminetetraacetic acid conditioning of dentin

On the basis of previous studies, it was hypothesized that a chelating agent such as ethylenediamine-tetraacetic acid (EDTA) in a saturated aqueous solution (24%) can function as a dentin conditioning agent with exposure times comparable to that of phosphoric acid without compromising shear bond strength. Thirty caries-free human third molars, divided equally between two groups, were used. In group one, four experimental surfaces were prepared on each tooth, and cylindrical copper matrixes with a diameter of 5 mm were attached to the prepared surfaces. The experimental surfaces were then treated with a 24% EDTA gel for 30, 60, 120, or 240 sec, respectively. Dentin was bonded with All Bond 2, after which a flowable composite was added and light-cured. In group two, which served as control, two surfaces were prepared on each tooth. One surface was left unetched, whereas the other side was treated with 24% EDTA-gel for 30 sec. A shear bond strength test was performed at a crosshead speed of 1 mm/min until the composite debonded. There was no statistically significant difference (P< 0.89) between results of the shear bond strength test for the different EDTA conditioning times. The control group showed a significant difference in shear bond strength between untreated surfaces and surfaces conditioned for 30 sec with EDTA. Thus, the results indicate that the duration of EDTA gel conditioning of dentin surfaces need not exceed that of phosphoric acid in clinical practice to obtain an acceptable level of bond strength.     

Technical quality of root fillings performed by dental students at the dental teaching centre in Reims, France

Aim  To evaluate the technical quality of root fillings performed by undergraduate students at a dental teaching centre in France.
Methodology  A random sample of 419 records of patients who received dental treatment at the dental service of the teaching Hospital, in Reims, France between 2005 and 2006 was investigated. Evaluation of root filled was based on radiographical criteria defined by the French National Health Service. The length of root fillings, the radiodensity and the presence of voids in the root filling or between root filling and root canal walls were recorded and scored. Chi-square analysis was used to determine statistically significant differences between the technical quality of root fillings and tooth type.
Results  Of the 304 teeth included in the study, 69% had an adequate length of root filling and 42.7% had a dense root filling without voids; only 30.3% of teeth fulfilled these criteria at the same time. The relationship between the technical quality of root fillings and tooth type was statistically significant ( P  < 0.001), the highest percentage of adequate root fillings occurred in single-rooted teeth (36.1%). The highest percentage of inadequate root fillings according to the criteria of root filling length and lateral adaptation was found in molar teeth (71.9%).
Conclusion  Overall, the technical quality of root fillings performed by undergraduate students was poor.     

Expression of two drug-metabolizing cytochrome P450-enzymes in human salivary glands

Objective:  The oral cavity is constantly lubricated by saliva and even small amounts of xenobiotics and / or their metabolites in the saliva may affect the oral mucosa. Our aim was therefore to clarify if xenobiotic metabolizing enzymes CYP1A2 and CYP3A4 are expressed in salivary glands.
Methods:  Formalin-fixed paraffin-embedded specimens from parotid (10), submandibular (7) and labial (10) salivary glands were examined immunohistochemically and by in situ hybridization for expression of CYP1A2 and CYP3A4 protein and mRNA.
Results:  CYP1A2 and CYP3A4 protein and mRNA were detected in ductal and seromucous / serous acinar cells in all gland types although to a varying degree and intensity. Mucous acinar cells were positive to a lesser extent.
Conclusion:  The results indicate a xenobiotic metabolizing capability of salivary glands. This may have implications for development of oral mucosal disease as a result of mucosal exposure to metabolites originating from internal sources (blood) as well as from saliva.     

Comparison of increased overjet cases and controls: normative data for condylar positions

The aim was to compare normal overjet versus large overjet cases with clinically healthy temporomandibular joints (TMJ); to establish normative data regarding the difference between condylar positions in centric occlusion (CO) and maximum intercuspation (MI) and deflective CO contacts. Two study groups of normal overjet and large overjet cases consisted each of 33 subjects with no detectable clinical signs of temporomandibular disorder (TMD). CO-MI differences were recorded using the SAM Mandibular Position Indicator. Deflective contacts were examined on models mounted in CO. There was a significant difference between groups in the vertical (P = 0.030) and transverse (P = 0.008) range of movement from CO to MI, but not in the antero-posterior direction. There were no differences in the location of deflective contacts. Results of this study showed that patients with increased overjet show some differences compared with normal overjet patients, even in the non-patients. Further research on TMD patients is needed to find out about the role these features play in the aetiology and treatment of temporomandibular disorder (TMD). This study indicates that the clinician should be paying special attention to the TMJ status of patients with a large overjet.     

Evaluation of the plaque removal efficacy of two commercially available dental floss devices

OBJECTIVE: This single blind, crossover design, clinical trial provided a comparative assessment of the oral cleaning of two dental devices as demonstrated through the removal of dental plaque when used according to marketed product-use directions. METHODOLOGY: Twenty-six subjects, both male and female between the ages of 19 and 64 years, completed this two-cell crossover study. Subjects were assessed for whole mouth plaque levels, both before and after use of each of the randomly assigned floss devices, by assessing disclosed plaque using the Modified Turesky Plaque Index. The two floss devices were a Mint Floss Pick and a standard rolled floss. Subjects abstained from brushing the night before appearing in the clinic, and based upon meeting the minimum plaque criteria of 1.5 at the first phase of the crossover, used one of the two floss devices according to the directions for use found on the product packaging. Both pre- and post-device use plaque levels were recorded with calculations made of both the actual difference in plaque level, as well as the percent plaque removed. Data were subjected to an analysis of covariance (ANCOVA), and employed a model consistent with crossover design. RESULTS: Overall results from both phases of the crossover showed the Mint Floss Pick product removed 19.4% of the plaque. The standard rolled floss product removed 15% of the plaque. Both products removed statistically significant plaque when assessed versus pre-treatment levels. Although the ANCOVA identified a statistically significant difference between treatments favoring the Floss Pick product, further statistical examination revealed a significant sequence effect, which led to a conservative product comparison of equivalence. This analysis confirmed that the Floss Pick product was "at least as good as" the standard floss product for plaque removal. Additional analyses of various sites in the mouth, i.e., interproximal, anterior, posterior, etc., also confirmed similarity of performance for both products in this test. CONCLUSION: A two-way crossover assessment of the cleaning capability of a Mint Floss Pick product compared to a standard rolled floss product was performed through assessment of the removal of dental plaque. Results of this clinical investigation support the Floss Pick product to be "at least as good as" standard rolled floss in cleaning capability when both products were used according to their product-use directions.     

Immediate function with NobelPerfect implants in the anterior dental arch

This study examined the clinical performance of the scalloped NobelPerfect implant in a one-stage procedure (immediate provisionalization in the esthetic zone). In 20 patients, immediate prosthetic restorations were placed on 31 NobelPerfect implants and followed for up to 27 months. Outcome variables were success rates, marginal bone levels, and Pink Esthetic Score (PES) assessed per implant. One implant failed (success rate: 96.8%). Marginal bone levels averaged 1.7 mm above the first thread and remained stable during the observation period. Mean PES ratings were 11.3 (range, 8 to 14). Survival rates, marginal bone levels, and esthetic results suggest proof of principle for the preservation of the interproximal bony lamella with a scalloped implant design.