Tooth Surface Morphology Research Articles

Comparisons of the Apatite Presentation and Demineralization in Enamel and Cementum by Atomic Force Microscopy

AFM is used to study tooth surfaces (enamel and cementum) in order to compare the pattern of particle distribution and demineralization process in the two dissimilar tooth hard tissues. Our approach is focusing mainly on the qualitative observations of tooth surface morphology and quantitatively measuring the early stages of mineral loss. The native enamel presented globular particles tightly packed. After polishing the aprismatic layer, the particles observed were relatively larger and more organized than ones in the outmost enamel surface. The cementum had small grains arranged in some degree of ordered packing with varying crystallite orientations. After different time treatment with citric acid solution, all the sample surfaces became more irregular and had the deeper grooves. The maximum mineral loss was greatest for the cementum sample and lowest for the native enamel. The demineralization difference between the enamel and cementum shows the structure and component play important roles in the morphological changes of demineralization. These demonstrate that the microstructure and demineralized difference between enamel and cementum obtained with AFM are complementary to the usual SEM images and TEM data. AFM is suitable for measuring early stages of tooth surface demineralization.

Nondestructive, in vitro quantification of crown margins

Statement of problem. It is important that artificial crowns fit the prepared tooth accurately, as marginal deficiencies are predisposed to plaque accumulation and lead to increased risk of periodontal disease. Various methods of evaluation for marginal fit are described in the literature, but most approaches are limited by destructive methods of assessment and/or small points of measurement. Purpose. This study compared, in vitro, the marginal fit of 4 types of complete crowns on human premolar teeth with the use of nondestructive profilometry. This method determined whether fit was influenced by type of crown or surface morphology of the tooth, namely, grooved or ungrooved surfaces. Material and methods. Four groups of specimens were prepared for complete crowns: group BA, bonding alloy with chamfer finish line; group G, gold alloy with chamfer finish line; group PC, porcelain with a chamfer finish line; and group PS, porcelain with a shoulder finish line. Two profiles of grooved mesial and ungrooved distal surfaces of the teeth were performed: (1) teeth prepared for each type of crown and (2) teeth with crowns seated but not cemented.Marginal fit (absolute marginal discrepancy) from the finish line edge of the tooth preparations to crown edges (CE) and leading edges (LE) of crowns were measured. Results. A 2-way analysis of variance for crown type and tooth surface morphology revealed significant differences between crown types for all measurement parameters, except vertical LE. The effect of surface morphology was not significant, except for vertical LE (P<.05). For all parameters, except vertical LE, the ranking of marginal fit discrepancies from greatest to least was as follows: group PC, G, BA, and PS. For vertical LE distances, the ranking was PS, BA, G, and PC (P<.05). Conclusion. Profilometry was used as a nondestructive, accurate method of evaluating the absolute marginal fit of different types of crowns. Marginal fits varied continuously around the circumference of each crown and made clinical assessment of fit accuracy subjective and arduous. ( J Prosthet Dent 2001;85:575-84.)

Saliva and Dental Caries

Caries is a unique multifactorial infectious disease. Our understanding of etiological factors, the progress of the disease, and the effectiveness of prophylactic procedures have led us to believe that we understand the disease. However, we still have too few answers to many questions: "Why can we not predict who will get the disease?" "Why do we not become immunized?" "How much saliva is enough?" or "Which salivary components are protective?" and "Which salivary components predispose for caries?" It is generally accepted, however, that saliva secretion and salivary components secreted in saliva are important for dental health. The final result, "caries to be or not to be", is a complex phenomenon involving internal defense factors, such as saliva, tooth surface morphology, general health, and nutritional and hormonal status, and a number of external factors-for example, diet, the microbial flora colonizing the teeth, oral hygiene, and fluoride availability. In this article, our aim is to focus on the effects of saliva and salivary constituents on cariogenic bacteria and the subsequent development of dental caries.

Retention of adhesive cement on the tooth surface after crown cementation

Statement of problem. Adhesive cements increase crown retention, but it is unknown if traces of cement remain undetected on the tooth surface after clinical removal of excess cement, which could exacerbate plaque retention. Purpose. This study measured the surface area, volume, mean depth, and maximum depth of a resin composite and a compomer luting cement left adherent on the tooth surface after removal of excess cement, as judged clinically. Methods and material. Four groups of specimens (n = 48) were prepared for full coverage crowns: group AC bonding alloy with chamfer finish line, group G gold alloy with chamfer finish line, group PC porcelain with a chamfer finish line, and group PS porcelain with a shoulder finish line. Two profiles of the mesial and distal surfaces of the teeth were carried out: (1) tooth with crown seated but not cemented and (2) tooth with the crown cemented in place. Two cements and 2 methods of cement removal were studied. Results. A 4-way analysis of variance for cement, crown type, method of removal, and tooth surface morphology showed that significantly greater volumes and mean depth, but not surface areas, of resin composite cement remained adherent than compomer cement ( P<.05). Among crown types, significant differences were found for cement volume (group G>AC, G>PC, G>PS), cement surface area (group AC>PC, G>PC, G>PS), and maximum cement depth (group G>AC). There was no significant difference between the 2 methods of cement removal. Significantly larger surface areas and maximum depths of cement were retained on the anatomically grooved mesial surface of the maxillary first premolars than on the ungrooved distal surface. Conclusion. Subclinical cement retention occurred after crown cementation, which was influenced by cement, crown type, and tooth surface morphology but not method of cement removal. (J Prosthet Dent 1999;81:668-77.)

Observations of Tooth Surface Morphology in Snakes

ABSTRACr.-An investigation of tooth surface features in a number of snake taxa revealed that, in addition to the typical lateral and medial some species possess accessory ridges that are generally confined to the posterior tooth surface and are most pronounced at the tooth base. The presence of accessory ridges appears to be confined to species with relatively long teeth that are piscivorous or feed on soft-bodied invertebrates. Several hypotheses are presented regarding the functional significance of these features. Investigations of morphology in snakes have concentrated primarily upon modifications associated with the delivery of venom (Anthony, 1955; Bogert, 1943; Brattstrom, 1964; Klauber, 1939; Smith, 1952). General treatments of snake and other reptilian dentition can be found in Edmund (1969) and Peyer (1968). Detailed descriptions and functional considerations of the surface features on typical noncanaliculate teeth have been confined to the position and extent of the or ridges. Frazzetta (1966) described the ridges on the teeth of several species of Python. These paired or cutting edges as he referred to them, run parallel to each other from the apex of the tooth; one extends laterally along the tooth shaft, the other medially. Wright et al. (1979) employed scanning electron microscopy to examine these dental ridges, as well as other aspects of the morphology, in the colubrid species Thamnophis elegans. Except for the 2 or 3 rear maxillary teeth, the orientation of the ridges is the same as that described for the pythons. The relative lengths of the ridges depend upon the tooth type and location. On the enlarged rear maxillary teeth the orientation of the ridges is shifted approximately 90? to form a long, bladelike posterior ridge and short anterior ridge. Descriptions of unique tooth morphology in which ridges are mentioned or figured have been reported for Xenodermus (Bogert, 1964), Iguanognathus (Boulenger, 1898), Dinodon and Stegonotus (McDowell, 1972), Regina (Rossman, 1963), Scaphiodontophis (Taylor and Smith, 1943), and Xenopeltis