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European Journal of Dentistry

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Anna Surdackaa, MD, PhDKrystyna Strzykaab, MD, PhDAnna Rydzewskac, MD, PhD

AbstrAct

Objectives: In dentistry, the results of in vivo studies on drugs, dental fillings or prostheses are

routinely evaluated based on selected oral cavity environment parameters at specific time points. Suchevaluation may be confounded by ongoing changes in the oral cavity environment induced by diet, druguse, stress and other factors. The study aimed to confirm oral cavity environment changeability.

Methods: 24 healthy individuals aged 2030 had their oral cavity environment prepared by havingprofessional hygiene procedures performed and caries lesions filled. Baseline examination and theexamination two years afterwards, evaluated clinical and laboratory parameters of oral cavity environ-ment. Caries incidence was determined based on DMFT and DMFS values, oral cavity hygiene on PlaqueIndex (acc. Silness & Le) and Hygiene Index (acc. O`Leary), and the gingival status on Gingival Index(acc. Le & Silness) and Gingival Bleeding Index (acc. Ainamo & Bay). Saliva osmolarity, pH and concen-trations of Ca2+, Pi, Na+, Cl-, total protein, albumins, F- and Sr2+ were determined.

Results: The results confirmed ongoing changeability of the oral cavity environment. After 2 yearsof the study reduction in oral cavity hygiene parameters PLI and HI (P

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mediated by both inorganic and organic compo-nents of the saliva that should be accounted forwhen evaluating the effects of human saliva anddental caries pathogenesis.7-9 The phenomenon ofsaliva components adsorption on the teeth surfacehas been experimentally proven and early carietic

lesions may undergo remineralisation as a resultof saliva action.10 As saliva is in constant contactwith teeth, changes in saliva organic and inorganiccomponents should certainly have a major impacton their condition. The composition and specificbiological and physicochemical characteristicsof saliva maintain physiological equilibrium be-tween demineralization and remineralisation ofthe enamel.9,11

The aim of the study was to answer the ques-tion if there are changes of the resting mixed sa-liva composition and selected clinical parametersin the same oral environments over a specified

time period.

MAterIAls And Methods

Twenty four healthy volunteers aged 20-30,who remained under constant dental care, tookpart in the study. The study was approved by theRegional Ethics Committee and each of the par-ticipants signed the informed consent. In orderto determine changeability of clinical and labora-tory parameters of the oral cavity environment theevaluation was performed twice - at study begin-ning (baseline assessment) and after two years.

Oral cavity hygiene was evaluated using PlaqueIndex (PLI) as proposed by Silness and Le12 andHygiene Index (HI) as proposed by O`Leary.13 Thecondition of the gingiva was assessed based on thevalues of Gingival Index (GI) developed by Le andSilness and Gingival Bleeding Index (GBI) proposedby Ainamo and Bay.14 The incidence of caries wasassessed using DMFT and DMFS values.

Mixed resting saliva was collected before anymeals, early in the morning between 7.00 and 9.00a.m. to avoid circadian variation in its composition.Subject were seated and asked to lean forward.Saliva was drooled at 30-s intervals into a plastic

tube - salivete kit with a cotton swab and without

a stimulator (Sarstedt, Germany)15 was used forcollecting the saliva for subsequent determiningof albumin and total protein level, saliva osmolar-ity and the concentration of inorganic phospho-rus, sodium, potassium, chloride and calcium.The measurements were carried out on the day

saliva was collected. The saliva for fluoride andstrontium concentration was collected to plasticcontainers, frozen and stored until the day whenthe assays were to be carried out. The pH valueof the mixed resting saliva was determined us-ing pH-meter N 517 pH meter (Poland) with silverchloride electrode filling solution (Orion Res. Inc.,USA). The electrode was calibrated against stan-dard pH buffers (pH 4.0, 7.0 and 9.3) (Corning Inc.NY, USA), prior to and after each test as well asduring tests as necessary.

Saliva concentration of sodium, potassium, andchloride ions was determined with ionoselective

method using Corning 644 analyser.16 Inorganicphosphorus and ionised calcium concentrationswere determined with spectrophotometric meth-od, using Cobas Mira analyser (Roche).16,17 Albuminlevel was assayed with turbidimetric method,18 andmodified Exton method was used to assay the totalprotein level.16 Saliva osmolarity was determinedwith crioscopic method with Knauer microos-mometer. Saliva strontium concentration was as-sayed with atomic absorption spectrophotometrywith electrothermic atomisation ET AAS, usingVarian Spectr AA 20 Plus spectrophotometer.19The results were submitted for statistical analysisand the differences between the baseline values ofthe analysed parameters and the values obtainedafter two years were verified with non-parametricMann-Whitney test.

results

Differences between the baseline values ofthe analysed parameters and the values obtainedafter two years of the study could be observed(Tables 1 and 2). Mean DMFT values were not sig-nificantly changed, yet DMFS values rose slightly(Table 1). The oral cavity hygiene indices (PLI and

HI) decreased (P

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values of the gingival status parameters, i.e. GIand GBI (Table 1).

The comparative analysis of mean values ofsaliva parameters and saliva constituents at base-line and after two years revealed statistically sig-nificant decrease in the concentration of calcium

(P

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strontium.25 Such a hypothesis is confirmed by theresults presented in Table 2 which show calciumlevel decrease of 40% after 2 years and inorganicphosphorus level increase of about 45% againstthe baseline values. The change in the concentra-tion of those ions may be related to the function of

the salivary glands which, as a result of repeatedstimulation, could secrete saliva of changed com-position. Mean mixed resting saliva concentra-tion of Ca+2 at baseline in young adults equalled2.480.63 (Table 2) and was higher compared tothe results reported by other authors, yet afterits decrease over two years it reached concentra-tions similar to those observed in other studies.26Mean and individual concentrations of inorganicphosphorus in the saliva, both at baseline and af-ter two years of the study, were either similar tothe concentrations reported by other authors22 orlower.27

Oral cavity characteristics and the degree ofsaliva osmolarity are dependent on protein con-centration, but also on the concentration of ion-ised sodium, potassium and chloride. Any changein saliva osmolarity will affect the processes ofdiffusion that occur between the solid and the liq-uid phases in the oral cavity. In this study salivasodium and potassium concentration exhibited adownward trend, yet the low concentrations werestill within the range of normal, physiological val-ues.28 Saliva chloride concentration did not signifi-cantly change over the 2-year study period.

Saliva strontium level decreased over 2-yearstudy period by a mean value of 5% against base-line value (P

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