On the relationship of dental microwear to dental macrowear

Dental microwear analysts have demonstrated that hard diets leave numerous microscopic pits on occlusal surfaces. The relationship between occlusal pitting and gross macrowear, however, is not well known. The current study seeks to elucidate the relationship between dental microwear and macrowear by determining if microscopically pitted teeth are associated with greater expressions of macrowear. This study examined microwear and macrowear on mandibular second molars from 60 prehistoric adult Native Americans representing three dietary regimes (foraging, mixed economy, and agriculture). Initially, two dental microwear feature variables were studied: percentage of pits and mean scratch width. Standard macrowear scores ranged from 4 to 40. ANOVAs suggested that neither of the microwear variables was affected by age or sex, but age affected macrowear scores. Because of this, the sample had a balanced number of young and old adults (i.e., those below and above skeletal age 35). A Pearson's correlation showed no covariation between scratch width and the percentage of pits. Regression analysis indicated that macrowear was not a function of the percentage of pits. However, a significant positive relationship was found between dental macrowear and scratch width. A post priori test found a significant negative relationship between macrowear and the total number of scratches. It is concluded, then, that wide scratches remove more enamel and dentin than do numerous pits, although both cause dental wear. It is suggested here that the term “abrasive” be used to describe those microwear profiles that lead to heavy macrowear and have relatively wide scratches. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Ecology of dental disease

Trace elements in the dental enamel of 43 prehistoric Indians from Illinois, Maryland and Virginia show concentration differences by age, sex and geographical locality. Sample areas on an incisor or first molar were blocked off with paraffin, washed twice with distilled water and etched 7 times with 6N HCl. An optical emission spectrophotometer was used to analyze the 9 samples, representing surface contamination and sequential enamel layers. Al, B, Ba, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Ti were present in most samples in micro or trace quantities; other elements were detected with less regularity. Comparisons of the 2 water washes with the 3 superficial, 4 deep and 7 total acid etches, suggest that during burial the residual inorganic portion of the enamel exchanged little or nothing with the soil. Enamel from archeological teeth may therefore be utilized in host factor studies in dental paleopathology. The Jy 50 Illinois Indians differ from the Potomac Creek, Virginia, Indians both in quantities of elements present and in internal sample variability. In each group, the sexes differ in 4 or more elements, both as to content and variability. Similarly, the older half of each sample differs from the younger. Patterns of sex and age difference are irregular, suggesting cultural differences, rather than physiological, in utilizing the environment during enamel-forming years. Enamel composition, as affected by differential environment utilization, may partially explain sex, age and geographical differences in dental pathology rates.     

Structural analysis of dental fear in children with and without dental trauma experience

The aim of the study was to evaluate dental fear in children with and without dental injuries in a randomly selected children in Croatia (59 girls and 88 boys). Children were divided into three groups depending on dental trauma experience. They were also divided into two age groups: 5-8 and 9-12 years. Only dental trauma to the permanent teeth was included in the study. The CFSS-DS, CDAS and CMFQ were used for evaluation of dental anxiety and the ISP Hollingshead Index of Social Position was calculated for evaluation of social status. The mean values of CDAS, CFSS-DS and CMFQ tests revealed that the anxiety level decreases with increasing experience of dental injury. The analysis of variance performed for CDAS showed a significant difference between children with and without dental trauma (p = 0,010). Regarding the groups, the analysis of variance for CMFQ (p = 0,021) and CFSS-DS (p = 0,001) showed a significant difference, as well as regarding age (CMFQ; p = 0,001 and CFSS-DS; p = 0,016). Cronbach's alpha coefficients revealed the highest reliability for CFSS-DS (alpha = 0,910). Pearson's correlation coefficients revealed significant correlations between the anxiety scores, age and ISP values for children without dental trauma, and between the anxiety scores and age for children with repeated dental trauma. The results of the ISP Hollingshead Index exhibited the highest frequency in children with dental injuries who belonged to the families with poor social background (ISP = 44-60). No significant difference was obtained between children with and without dental injuries depending on either gender or the ISP value.     

Formation of bone-like tissue by dental follicle cells co-cultured with dental papilla cells

During tooth root formation, dental follicle cells (DFCs) differentiate into osteoblasts/cementoblasts when they are in contact with pre-existing dentin. Since some factors of dentin matrix were also produced by dental papilla cells (DPCs) and could induce DFCs differentiation, we hypothesized that DPCs can directly promote DFCs differentiation and that differentiation could occur in a co-culture model. To test this hypothesis, we investigated the characteristics of DFCs that are influenced by DPCs in an in vitro co-culture and in vivo heterotopic transplant model. One week into the co-culture, there were significant increases in the mRNA level of bone morphogenetic protein 2 (BMP2), osteoprotegerin (OPG), bone sialoprotein (BSP) and osteocalcin (OCN), and a decrease of the receptor activator of nuclear factor κB ligand (RANKL). Additionally, the number of BMP2-, OPG-, BSP- and OCN-positive DFCs increased whereas RANKL-positive DFCs decreased. Three weeks after co-culture, DFCs produced calcified nodules, accompanied with increased sub-cellular organelles for protein synthesis and secretion. In the heterotopic transplant model, the adult male rats were used as hosts, DFCs were transplanted into the omentum. In vivo 5-week growth of DFCs in the presence of DPCs led to the formation of bone-like tissues, positive for BSP, OCN and BMP2. In contrast, DFCs alone led to fibrous-like tissues. These results indicated that in the absence of pre-existing dentin, DPCs can stimulate osteogenesis and inhibit osteoclastogenesis in DFCs and suggested a novel strategy to promote DFCs differentiation.     

Influence of the fluoride releasing dental materials on the bacterial flora of dental plaque

The assessment of influence of silver-free, fluor releasing dental materials on dental plaque bacteria quantity. 17 patients were included into the study. 51 restorations were placed following manufacturers recommendations. Following materials were used: conventional glassionomer Ketac-Molar ESPE, resin modified glassionomer Fuji II LC GC and fluor containing composite Charisma Heraeus Kulzer Class V restorations were placed in following teeth of upper and lower jaw: canines, first bicuspids, second bicuspids. Sound enamel was a control. After 10 weeks the 72 hours old dental plaque was collected from surface of restorations and control using sterile probe. Total amount of 68 dental plaques were investigated. Each plaque was placed on scaled and sterile aluminum foil. The moist weight of dental plaque was scaled. Dental plaque was moved into 7 ml 0.85% NaCl solution reduced by cystein chlorine hydrogen and disintegrated by ultrasounds (power:100 Watt, wave amplitude: 5 micorm). The suspension of dental plaque was serially diluted from 10(-4) to 10(-5) in sterile 0,85% NaCl solution, and seeded with amount of 0.1 ml on appropriate base. In dental plaque trials the amount of cariogenic bacteria was calculated--Streptococcus mutans, Streptococcus, Lactobacillus, Veillonella and Neisseria, and also total amount of aerobic and anaerobic bacteria was measured. Microbiologic studies were performed in Institute of Microbiology, Medical University, ?ód?. Statistical analysis of collected data was accomplished. In 72 hours old dental plaques collected from the surfaces of Ketac -Molar, Fuji II LC, Charisma after 10 weeks since being placed into the class V cavity, results show no statistically significant differences in the amount of Streptococcus mutans, Streptococcus spp., Lactobacillus spp., Veillonella spp., Neisseria spp, in total amount of aerobic and anaerobic bacteria and in the quantity proportion of Streptococcus mutans versus Streptococcus spp. in comparison with control trail. Results show no statistically significant differences in the amount of listed above bacteria and in the proportion of Streptococcus mutans versus Streptococcus spp. in 72 hours old dental plaques collected from surfaces of investigated restorative materials.     

Helicoidal plane of dental occlusion

A helicoidal plane of postcanine occlusion has been patchily reported in many recent and fossil dentitions of man, and has been suggested as a taxonomic marker distinguishing between the dentitions of Homo and Australopithecines. The present paper describes the helicoidal plane in 19 out of 23 modern human (probably Indian) worn dentitions, in both gracile and robust Australopithecines and in extant anthropoids. It is suggested that tooth wear converts the plane of occlusion present in little-worn teeth, the Monson curve, into a helicoidal plane when 1) the diet is more abrasive, 2) the enamel is thinner and less abrasion resistant, and 3) a longer time separates the eruption of the three molar teeth in a jaw quadrant. A model demonstrates that during the power stroke of a chewing cycle the working side molars move in much the same direction whether the molar occlusal plan follows a Monson curve or a helicoidal plane. The difference is that in the former case the three molars work at the same time while in the latter case they work in sequence from anterior to posterior, thereby concentrating force on one tooth at a time. Because the occlusal plane changes during the life of individuals consuming an abrasive diet, the condition of most anthropoids and hominids, it is argued that the Monson curve has functional significance not because of its influence on occlusal relations and/or jaw movement but because the molar teeth are embedded in bone roughly perpendicular to it, a direction which resists tilting of the teeth during mastication. It is concluded that the helicoidal plane probably has little if any value as a taxonomic marker.     

Cell pellets from dental papillae can reexhibit dental morphogenesis and dentinogenesis

We isolated dental papilla mesenchymal cells (DPMCs) from different rat incisor germs at the late bell stage and incubated them as cell pellets in polypropylene tubes. In vitro pellet culture of DPMCs presented several crucial characteristics of odontoblasts, as indicated by accelerated mineralization, positive immunostaining for dentin sialophosphoprotein and dentin matrix protein 1, and expression of dentin sialophosphoprotein mRNA. The allotransplantation of these pellets into renal capsules was also performed. Despite the absence of dental epithelial components, dissociated DPMCs with a complete loss of positional information rapidly underwent dentinogenesis and morphogenesis, and formed a cusp-like dentin-pulp complex containing distinctive odontoblasts, predentin, dentin, and dentinal tubules. These results imply that DPMCs at the late bell stage can reexhibit the dental morphogenesis and dentinogenesis by themselves, and epithelial-mesenchymal interactions at this stage may not be indispensable. Furthermore, different DPMC populations from the similar stage may keep the same developmental pattern.     

Proteomic analysis of dental tissues

Teeth are highly refined structures formed by several types of specialised cell. Tooth formation embraces many areas of biomedical interest, including cellular mechanisms for calcium handling, protein secretion and mineralised tissue production. Proteomics offers great potential to elucidate these cellular roles, and to establish their relevance to general cell types. Here we review our proteomic investigations of dental enamel formation, covering both the approaches taken and some findings of general biomedical relevance.     

Stem cells of dental pulp

Any clinician dreams to obtain the regeneration of the destroyed organ for his patient. In the human being, the regeneration of complex structures is not possible, except the liver and the bone marrow, which can be regenerated because of the presence of adult stem cells in these tissues. The stem cells have two principal properties: they ensure their self-renewal and they have the ability to differentiate into several cellular types. Using specific markers allowing the identification of the stem cells in bone marrow, stem cells were observed in dental pulp tissues. Although the origin, the identification, and the localization of these stem cells of dental pulp remain under consideration, the optimism in research on stem cells permits to believe that the knowledge on dental stem cells will lead to their use in therapeutics.     

First-time dental care and the most recent dental treatment in relation to utilisation of dental services among dentate elderly patients in Lithuania

Objectives: To describe the initial dental treatments of Lithuanian dentate elderly patients and the content of the most recent treatment in relation to their dentist‐visiting behaviour. Materials and methods: A cross‐sectional questionnaire study was carried out at two public dental offices in Kédainiai, Lithuania, among dentate patients aged 60+ years. A self‐administered questionnaire covered first‐time dental care, the most recent dental treatment, check‐up behaviour, interval since the most recent dental visit, and number of teeth. Age, gender and education served as background information. Statistical evaluation was by chi‐squared test, anova and logistic regression for odds ratio (OR). Results: In all, 174 dentate elderly responded, mean age being 69.2 (SD = 6.6) years. The mean age at the first visit was 16.3 years [95% confidence interval (CI) 14.9–17.6]. Regular dental check‐ups were reported by 30%, and 36% had visited a dentist within the past 12 months. As to the content of the most recent treatment, 78% of the elderly reported filling therapy, 50% endodontics, 48% tooth extraction, 21% radiography, 10% cleaning or scaling and 6% polishing of fillings. Those going for check‐ups were more likely to report diagnostic (OR 1.9; 95% CI 1.1–2.8; p = 0.01) and preventive (OR 4.8; 95% CI 2.5–9.0; p = 0.002) treatment when analysed by a logistic regression model, controlling for age, gender, education and number of teeth. Conclusions: Check‐up‐orientated utilisation of dental services should be encouraged among the Lithuanian elderly. Dentists and health officials should place greater emphasis on prevention.