Hard tissue lubrication by salivary fluids

doi:10.1016/0267-6605(90)90005-G

Clinical Materials

Volume 6, Issue 2, 1990, Pages 151-161

Clinical Materials

https://doi.org/10.1016/0267-6605(90)90005-G Get rights and content

Abstract

The frictional coefficients for human parotid (HPS) and human submandibular/sublingual (HSMSL) salivas and water were measured for five subjects. Twenty different biomechanical conditions were used which approximated the range of force and movement of the human mandible. The experimental set-up comprised a bruxing motion under servohydraulic control; a microchamber with a small recirculating volume (3 ml minimum) under physiologic temperature control; and a maxillary element capable of measuring frictional forces at the enamel interface. The relative movement of enamel-on-enamel demonstrated the slip-stick phenomenon which was consistent with the negative velocity gradient of the coefficient of friction under all conditions. Studies on the variation of the frictional forces as a function of vertical load confirmed that the mechanism of lubrication was thin film, under the experimental conditions. HSMSL saliva had the greatest potential to vary the lubrication mechanism. At low speeds and higher force, it is suggested that boundary lubrication may offer the greatest potential in the development of enhanced lubrication of the hard tissues in the oral cavity.

References (20)

M.N. Hatton et al.
Lubrication and viscosity features of human saliva and commercially available saliva substitutes
J. Oral Maxillofac. Surg.
(1987)
A. Aguirre et al.
In vitro characterization of human salivary lubrication
Arch. Oral Biol.
(1989)
I. Al-Hashimi et al.
Characterization of in vivo salivaryderived enamel pellicle
Arch. Oral Biol.
(1989)
D.J. Neill et al.
Functional loading of the dentition during mastication
J. Pros. Dent.
(1989)
R. Delong et al.
The wear of dental amalgam in an artificial mouth: a clinical correlation
Dent. Mater.
(1985)
R.L. Sakaguchi et al.
The wear of a posterior composite in an artificial mouth: a clinical correlation
Dent. Mater.
(1986)
R. Delong et al.
The wear of dental porcelain in an artificial mouth
Dent Mater.
(1986)
D.A. Swann et al.
The lubricating activity of synovial fluid glycoproteins
Arthritis Rheum.
(1981)
D.A. Swann et al.
The lubricating activity of human synovial fluids
Arthritis Rheum.
(1984)
M.N. Hatton et al.
Masticatory lubrication: role of carbohydrate in the lubricating property of a salivary glycoprotein-albumin complex
Biochem. J.
(1985)

There are more references available in the full text version of this article.

Cited by (10)

Potential biomarkers of human salivary function: A modified proteomic approach
2009, Archives of Oral Biology
Citation Excerpt :
Given its strong calcium-binding activity, it is not surprising that statherin has been found to be a plentiful component of the enamel pellicle, both in vitro and in vivo.14,18–20 Statherin in pellicle is distributed close to the enamel surface,19 which may be related to the high levels of lubricity that were demonstrated with purified statherin in an artificial mouth system.21 However, a recent study has shown that a statherin- and calcium-rich layer also forms at the air–liquid interface of salivary films in vitro.22
In previous studies, we defined groups of subjects with opposite salivary function. Group membership was associated with clinically relevant outcomes. High aggregation-adherence (HAA) groups showed lower levels of caries, supragingival plaque, total streptococci, and Tannerella forsythensis than low high aggregation-adherence (LAA) groups. In this study, we used a proteomic approach to search for biomarkers which could be useful as risk indicators for those outcomes.
Clarified resting whole saliva from each of 41 HAA and LAA subjects was separated by preparative isoelectric focusing. Fractions showing the most distinctive protein profiles were pooled into four sets (pI 3–3.5, pI 4–4.7, pI 5.7–7.7, pI 10–11.5). Each pool then was compared by SDS–PAGE. Image analysis software was used to quantify matched bands. Partial least squares analysis (PLS) was used to determine which of the 65 bands from all four pools were the best predictors of group membership, caries, total plaque, total streptococci, and T. forsythensis counts. Those bands were identified by mass spectroscopy (MS-MS).
Two bands consistently were strong predictors in separate PLS analyses of each outcome variable. In follow-up univariate analyses, those bands showed the strongest significant differences between the HAA and LAA groups. They also showed significant inverse correlations with caries and all the microbiological variables. MSMS identified those bands as statherin, and a truncated cystatin S missing the first eight N-terminal amino acids.
Levels of statherin and truncated cystatin S may be potential risk indicators for the development of caries and other oral diseases.
Lubrication of saliva substitutes at enamel-to-enamel contacts in an artificial mouth
1996, Journal of Prosthetic Dentistry
Mechanisms of salivary lubrication can be quantitatively measured by a reduction in the coefficient of friction. It is important that lubrication be assessed under the conditions of the oral cavity to properly assess lubrication regimes. The relative lubricity of three artificial salivas and two controls were assessed at a bovine enamel interface in an artificial mouth with a range of conditions that approximate oral function. Statistical analysis indicated that the enamel lubricity of sodium dodecylsul-fate (SDS) and Oracare-D saliva substitutes were different from the other saliva substitutes and water. The low friction with Oracare-D and SDS saliva substitutes was because of resident amphipaths adsorbed at the enamel interface. Amphipaths adsorbed on enamel may provide a reduction in interocculsal friction and its resulting complications for patients with xerostomia.
Considerations for modeling
1996, Dental Materials
There has been a great growth in the biophysical knowledge base of the human masticatory system, which increases the chances of success in numerical and experimental modeling of the oral environment. The chief advances in understanding are in the areas of the dentino-enamel complex, the force-movement cycle of the mandible, mastication, comminution and salivary lubrication. These areas are reviewed, and suggested average clinical conditions are offered as a starting point for experiments in laboratory clinical simulation as it relates to the studies in biomaterials and biomechanics in dental research.
Lubrication of human and bovine enamel compared in an artificial mouth
1995, Archives of Oral Biology
Bovine enamel has been a good model for human enamel across a broad range of studies. The present work sought to consider if bovine enamel would be a suitable substitute for human enamel in experiments on simulated oral lubrication. Enamel samples of the same size were prepared from bovine and human teeth for use as maxillary and mandibular elements in a miniature artificial mouth. Sliding speeds from 1.99 to 7.84 mm/s and occlusal forces of 3.8–19.5 N were used. Water and four solutions consisting of a mucin-rich fraction, a statherin-rich fraction, 3[(3-cholamidopropyl)-dimethylammonio]-1-propanesulphonate and sodium dodecyl sulphate were evaluated. The high correlations between widely different lubricants on the two enamel substrates gives confidence in the use of bovine enamel as a model for human enamel in salivary lubrication studies. Knoop hardness indentations on enamel samples were combined with friction data and calculations of the true contact area to give a method for the indirect determination of surface shear. The calculated surface shear value was compared with published values obtained by punch shear testing.
Statherin: A major boundary lubricant of human saliva
1991, Biochemical and Biophysical Research Communications
The lubricating properties of human submandibular-sublingual salivary fractions were examined using a servohydraulic model of mandibular movement. Fractions containing statherin exhibited a strong tendency to boundary lubrication. The lubricity of purified statherin was confirmed and compared to the amphipathic molecules gramacidin S and sodium dodecyl sulfate. Contact angle measurements of statherin paralleled the other amphipathic molecules. The helical content of statherin increased in trifluoroethanol indicating the presence of amphipathic helical regions. CD studies and hydrophobic moment calculations indicated that statherin adopts an amphipathic helical conformation at the N-terminus. An energy-minimized model of the polar N-terminal residues 1–15 suggested that this domain could be positioned in space to interact with a hydroxyapatite substrate. These data imply that under appropriate conditions statherin may display an amphipathic nature which enables it to function as a boundary lubricant on enamel.
Oral Mucosa: Physiological and Physicochemical Aspects
2014, Mucoadhesive Materials and Drug Delivery Systems

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Hard tissue lubrication by salivary fluids

Abstract

J. Oral Maxillofac. Surg.

Arch. Oral Biol.

Arch. Oral Biol.

J. Pros. Dent.

Dent. Mater.

Dent. Mater.

Dent Mater.

The lubricating activity of synovial fluid glycoproteins

Arthritis Rheum.

The lubricating activity of human synovial fluids

Arthritis Rheum.

Masticatory lubrication: role of carbohydrate in the lubricating property of a salivary glycoprotein-albumin complex

Biochem. J.