Occlusal surface

K.L. Weerheijm, E.A.M. Kidd, H.J. Groen, The effect of fluoridation on the occurrence of hidden caries in clinically sound occlusal surfaces. Caries Res. 31 (1997) 30-34. 

Tooth type and position are often noted with a combination of numbers and letters, depending on the species. Each tooth has a lingual side, adjacent to the tongue, and a labial surface, which is closest to the lips (if there are any). The posterior teeth are at the back of the mouth, and the anterior to the front. The occlusal surface is the area where opposing teeth meet during chewing or biting. 

Fig. 13. Characteristic index fossil of the older phases of the Middle Pleistocene, the vole Mimomys savini Hinton, (a) and (b) Occlusal surface of the first molar of a young and an adult specimen (c) and (d) same from lateral view occlusal surface of (e) M2 (f) M2 and (g) M] (upper first molar). Characteristic from lateral view is the weak development of roots. Locality rock shelter of Tarkd.

Fig. 16. Schematic drawings of the occlusal surface of the upper third molars (M, upper row) and lower first molars (Mj, lower row) of the rootless steppe lemming species stratigraphically characteristic of the Middle and Upper Pleistocene, (a) and (e) Lagurus pannonicus, Kovesvarad (b), (c) and (f), (g) Lagurus transiens, rock shelter of Tark6 (d) and (h) Lagurus lagurus, Subalyuk.

Fig. 27. Occlusal surface of some characteristic rootless vole species of the Middle and Upper Pleistocene, as based on the lower first molar (M,). Small species (a) Microtus gregalis (b) Pitymys arvalidens-subterraneus (c) Microtus arvalinus-arvalis. Water vole (Arvicola genus) (d) Arvicola cantiana (enamel thick posteriorly, thin anteriorly) (e)/fmco/a sp. I (thick layer of enamel) (f) Arvicola sp. II (thin layer of enamel).

From a materials perspective there are two possible reasons why dental enamel shows the large variations in mechanical properties shown in figure 1 firstly, chemical variations in apatite composition and, secondly, changes in enamel structure with position from the occlusal surface to the EDJ. The chemical composition of enamel can be examined with a lateral resolution of 1-10 pm with electron microprobe analysis. Enamel structure can be obtained with SEM. To perform an accurate microprobe analysis, natural and synthetic minerals are used as standards to calibrate the instrument. This is fairly routine for geologists and earth scientists who are able to obtain chemical compositions with an accuracy of <0.1% for a wide range of elements simultaneously (including Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, Hf, Ta, Pb, Th, U, F and Cl). In enamel only a few of these (Na, Mg, Al, P, K, Ca, Ti, Cl and F) are above the detection limit. The Ti is likely to be an impurity or contaminant rather than a constituent of enamel. This technique does not work for lighter elements such as C, S, O and N which may be present in enamel. 

The present results are in conformity with those of Weatherell et al. (1986) who found that when a fluoride tablet was placed in the buccal vestibule, the fluoride concentration peaked in the fluid adjacent to the tablet but was much lower both mesially and distally. The previous reports and our results suggest that when parotid saliva exits the parotid duct, it primarily flows downwards and then, from the results of Weatherell et al. (1986), probably lingually over the occlusal surface of the teeth, rather than flowing mesially or distally in the buccal sulcus. If it flowed primarily in either of these two directions, one would have expected very little difference between the clearance rates from the mesial or distal agar cylinder and that from the cylinder positioned over the parotid duct opening. Sass and Dawes (1977) also reported that very little parotid saliva appeared to flow mesially when flow was either unstimulated or stimulated by the use of chewing gum. 

Figure 4. Case B3 A four-unit posterior zirconia bridge in (a). The piece on the left is gold coated, (b) shows the fracture surfaces with the piece s occlusal surfaces mounted back-to-back. Compression curls are marked with small arrows. The origin is marked by the large arrows.

Fang JJ, Kuo TH (2009) Tracked motion-based dental occlusion surface estimation for crown restoration. Comput Aided Des 41(2009) 315-323... 

Pit and fissure sealants (12) used as caries preventive treatment for filling deep fissures in posterior teeth, primarily deciduous molars, are rather popular despite the controversy on the economic efficacy. The sealants now in use are composed of methyl methacrylate, Bis-GMA and/or urethane methacrylate mixtures. They are applied to phosphoric acid-etched occlusal surface in a very fluid state to flow into the surface (Fig. 11), and cured by U.V. or are self curable. They attach to the enamel by mechanical locking into the etched surface rather than by adhesion. 

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