Hardy Limeback

The application of ozone in dentistry: a systematic review of literature.

OBJECTIVES (1) To systematically review the clinical application and remineralization potentials of ozone in dentistry; (2) To summarize the available in vitro applications of ozone in dentistry. SOURCES Ovid MEDLINE, CINAHL, etc. (up to April 2007). STUDY SELECTION In vitro or in vivo English language publications, original studies, and reviews were included. Conference papers, abstracts, and posters were excluded. RESULTS In vitro: Good evidence of ozone biocompatibility with human oral epithelial cells, gingival fibroblast, and periodontal cells; Conflicting evidence of antimicrobial efficacy of ozone but some evidence that ozone is effective in removing the microorganisms from dental unit water lines, the oral cavity, and dentures; Conflicting evidence for the application of ozone in endodontics; Insufficient evidence for the application of ozone in oral surgery and implantology; Good evidence of the prophylactic application of ozone in restorative dentistry prior to etching and the placement of dental sealants and restorations. In vivo: Despite the promising in vitro evidence, the clinical application of ozone in dentistry (so far in management of dental and root caries) has not achieved a strong level of efficacy and cost-effectiveness. CONCLUSIONS While laboratory studies suggest a promising potential of ozone in dentistry, this has not been fully realised in clinical studies to date. More well designed and conducted double-blind randomised clinical trials with adequate sample size, limited or no loss to follow up, and carefully standardised methods of measurement and analyses are needed to evaluate the possible use of ozone as a treatment modality in dentistry.

Development and evaluation of an oral health literacy instrument for adults.

OBJECTIVES To develop and validate an instrument to measure the functional oral health literacy of adults. METHODS For the generation of items different dental patient educational materials and text types were selected that had reading levels similar to materials used for the Test of Functional Health Literacy in Adults (TOFHLA) which was the model for our Oral Health Literacy Instrument (OHLI). The OHLI contains reading comprehension and numeracy sections. The reading comprehension section is a 38-item test with words omitted from one passage on dental caries and another on periodontal disease. The numeracy section has 19 items to test comprehension of directions for taking common prescriptions associated with dental treatment, postextraction instructions and dental appointments. We also developed a 17-item oral health knowledge test. The OHLI, the TOFHLA, the oral health knowledge test and a brief questionnaire were administered to a convenience sample of 100 patients. Internal reliability of OHLI was assessed with Cronbachs alpha. Test-retest reliability was examined by intra-class correlation coefficient (ICC). Concurrent validity was tested by comparing OHLI scores across categories of education level and frequency of dental visits. Construct validity was assessed by correlating OHLI scores with TOFHLA scores and with the oral health knowledge scores using Spearmans rho (rho) and multiple linear regression. RESULTS Participants averaged 39 years (SD = 12.4); 73% were female; 64% had college/university education; 40% visited a dentist every 3-6 months. Total OHLI and TOFHLA weighted mean scores were 87.2 and 91.7, respectively (possible range 0-100). The Cronbachs alpha values were high (>0.7) for OHLI and its components. The ICC values indicated good agreement between the test and retest results for OHLI and the oral health knowledge test. Patients visiting a dentist every 3-6 months had significantly higher levels of oral health literacy than those visiting only when they felt pain. The association between OHLI and education level was not significant. OHLI scores were significantly correlated with the scores on the TOFHLA (rho = 0.613) and the test of oral health knowledge (rho = 0.573). These associations remained significant in multiple regression models. CONCLUSION Initial testing of OHLI suggested that it is a valid and reliable instrument to evaluate oral health literacy among adults, although additional work is needed to investigate the instruments predictive validity and sensitivity to change using oral health outcomes with population groups known to be at high risk of low functional oral health literacy.

Is Fluoride Concentration in Dentin and Enamel a Good Indicator of Dental Fluorosis

Despite some studies correlating dental fluorosis (DF) and fluoride (F) concentration in dental enamel, no information is available about DF and dentin F concentration. Our objective was to determine the correlation between teeth F concentration and DF severity in unerupted human 3rd molars, and the correlation between dentin and enamel F concentrations in the same tooth. Ninety-nine 3rd molars were studied—53 from Fortaleza, Brazil (F water, 0.7 ppm), 22 from Toronto (1.0 ppm), and 24 from Montreal (0.2 ppm). DF severity was evaluated according to the Thylstrup-Fejerskov Index, while F concentration was analyzed by Instrumental Neutron Activation Analysis. DF severity varied between TF0 and TF4, while F concentration ranged between 39 and 550 ppm in enamel and 101 and 860 ppm in dentin. Our results showed correlation between dentin F concentration and DF (rS = 0.316, p = 0.001), but no correlation between enamel F concentration and DF (rS = 0.154, p = 0.133). No correlation was observed between dentin and enamel F concentrations in the same tooth (rS = 0.064, p = 0.536).

Osteogenic phase-specific co-regulation of collagen synthesis and mineralization by β-glycerophosphate in chick periosteal cultures

Mineralized bone formation in vitro can be induced by the alkaline phosphatase substrate beta-glycerophosphate (GP). GP may not only be essential for mineralization in vitro, but could also modulate other metabolic activities of bone cells, particularly if GP is presented to these cells during different phases of development. To assess GP modulation of bone cell metabolism, biochemical and autoradiographic analyses of chick periosteal cultures treated with GP were performed. About 50% less (p less than 0.05) Type I collagen was produced in periosteal cultures treated with GP. If the fibrous portion of the periostem was microdissected from the osteogenic layer prior to culture, GP inhibition of Type I collagen synthesis was even more marked (60%: p less than 0.05). To define organic phosphate-sensitive phases of osteogenesis, cultures were exposed to GP for various time periods. Mineralization occurred reproducibly when periosteal cultures were treated with GP from the outset of the incubation period (positive control). However, if GP was added after the third day of incubation, phosphate content was the same as in positive control cultures, whereas calcium content was significantly (20%: p less than 0.05) lower. Moreover, if GP was added on day 6, there was virtually no calcium accumulation by day 12, while massive amounts of phosphate had accumulated. Taken together, these findings indicate that organic phosphates may modulate phenotypic expression of osteogenic cells, and that osteogenic cells traverse an organic phosphate-sensitive phase, after which they may be incapable of normal mineralization.

How Does Fluoride Affect Dentin Microhardness and Mineralization

Fluoride (F) has been a useful instrument in caries prevention. However, only limted data exist on the effect of its long-term use on dentin mineralization patterns and microhardness. The objective of this study was to evaluate the influence of tooth F concentration ([F]) and dental fluorosis (DF) severity on dentin microhardness and mineralization. We collected 137 teeth in Montreal and Toronto, Canada, and Fortaleza, Brazil, where optimum or suboptimum levels of water F were 0.2 ppm, 1 ppm, and 0.7 ppm, respectively. Teeth were analyzed for DF severity, dentin [F], enamel [F], dentin microhardness, and dentin mineralization. Dentin [F] correlated with DF severity; enamel [F] correlated with dentin microhardness and dentin mineralization; DF severity correlated with dentin microhardness. Genetic factors (e.g., DF severity) and environmental factors (e.g., tooth [F]) influenced the mechanical properties (microhardness) of the teeth, while only the environmental factors influenced their material properties (e.g., mineralization). Fortaleza teeth were harder and less mineralized and presented higher dentin [F] values. Montreal teeth presented lower levels of DF when compared with both Toronto and Fortaleza teeth.

The Long-term Effects of Water Fluoridation on the Human Skeleton:

Municipal water fluoridation has notably reduced the incidence of dental caries and is widely considered a public health success. However, ingested fluoride is sequestered into bone, as well as teeth, and data on the long-term effect of exposure to these very low doses of fluoride remain inconclusive. Epidemiological studies suggest that effects of fluoride on bone are minimal. We hypothesized that the direct measurement of bone tissue from individuals residing in municipalities with and without fluoridated water would reveal a relationship between fluoride content and structural or mechanical properties of bone. However, consonant with the epidemiological data, only a weak relationship among fluoride exposure, accumulated fluoride, and the physical characteristics of bone was observed. Analysis of our data suggests that the variability in heterogenous urban populations may be too high for the effects, if any, of low-level fluoride administration on skeletal tissue to be discerned.

How Does Fluoride Concentration in the Tooth Affect Apatite Crystal Size

Despite fluoride’s (F) well-documented ability to prevent caries, the effects of F concentrations on enamel and dentin apatite crystals are unknown. The present study examined the hypothesis that tooth F concentration and tooth crystallite size correlate. One hundred human unerupted third molars were studied—53 from Fortaleza-Brazil (F water 0.7 ppm), 23 from Toronto (1.0 ppm), and 24 from Montreal (0.2 ppm). F concentration was analyzed by Neutron Activation Analysis and apatite crystal size by powder x-ray diffraction. A positive correlation between dentin F concentration and enamel crystallite length and width was found. Enamel crystallite length was significantly greater in teeth from Fortaleza than in teeth from Toronto (p = 0.011) and Montreal (p = 0.003). Enamel crystallite widths were significantly greater in Fortaleza teeth compared with those from Toronto (p = 0.020) and Montreal (p < 0.001). No difference in the dentin crystallite size was seen in the 3 regions. Thus, tooth F concentration and crystallite size correlate.

Clonal distribution of osteoprogenitor cells in cultured chick periostea: Functional relationship to bone formation

Folded explants of periosteum from embryonic chick calvaria form bone-like tissue when grown in the presence of ascorbic acid, organic phosphate, and dexamethasone. All osteoblast-like cells in these cultures arise de novo by differentiation of osteoprogenitor cells present in the periosteum. To study the spatial and functional relationships between bone formation and osteoprogenitor cells, cultures were continuously labeled with [3H]thymidine for periods of 1-5 days. Radioautographs of serial 2-microns plastic sections stained for alkaline phosphatase (AP) showed maximal labeling of 30% of fibroblastic (AP-negative) cells by 3 days while osteogenic cells (AP-positive) exhibited over 95% labeling by 5 days. No differential shifts in labeling indices, grain count histograms of fibroblastic and osteogenic cells or numbers of AP-positive cells were observed, indicating no significant recruitment of cells from the fibroblastic to the osteogenic compartment. Despite the continuous presence of [3H]thymidine, less than 35% of both osteoblasts and osteocytes were labeled at 5 days, indicating that only one-third of the osteoprogenitor cells had cycled prior to differentiation. Spatial clustering of [3H]thymidine-labeled cells was measured by computer-assisted morphometry and application of the Poisson distribution to assess contagion. Cluster size and number of labeled cells per cluster did not vary between 1-3 days, but the number of clusters increased 20-fold between Day 1 and Day 3. Clusters were predominantly AP-positive and located close to bone. Three-dimensional reconstruction from serial sections showed that clusters formed long, tubular arrays of osteogenic cells up to eight cells in length and located within 2-3 cell layers from the bone surface. Selective killing of S-phase cells with two pulse labels of high specific activity [3H]thymidine at 1 and 2 days of culture completely blocked bone formation. These data indicate that a very small population of cycling osteoprogenitor cells is essential for bone formation in vitro and give rise to relatively small numbers of clonally distributed progenitors with limited proliferative capacity. The progeny of these clusters undergo restricted migration and differentiate into osteoblasts.

Study Incapable Of Detecting IQ Loss From Fluoride

This article discusses a study conducted to determine the toxicity of fluoride in community water resources, with a particular focus on possible effects on IQ. The author examines the fluoride levels tested and the conclusions drawn from the research, which found no connection between fluoride and IQ loss.

Response to Letter to the Editor, “The Long-term Effects of Water Fluoridation on the Human Skeleton”

Thank you for allowing us the opportunity to respond to the Letter to the Editor submitted by Phillips et al. in response to our paper in this journal, “The Long-term Effects of Water Fluoridation on the Human Skeleton” (Chachra et al., 2010). We appreciate the points that they raise regarding the confounding effects of age, gender, and disease states on the effect of fluoride on bone quality. In fact, we explicitly address the interaction effect of age and fluoride, under the heading “Variability in the Data” (p. 1221). The reference cited there is the doctoral thesis of the first author (Chachra, 2001), from which the data presented in this paper are excerpted. That thesis includes a detailed analysis of the data by age, gender, and disease state, which were collected for each patient and are presented in Table 1 (p. 1220). These analyses are outside the scope of the work presented here, but briefly, there was no evidence of a gender-specific relationship between the mechanical properties and the fluoride content. The relationship between the ultimate compressive stress and the fluoride content was slightly weaker when the osteoporotic samples were excluded, suggesting that both disease states have a similar effect on mechanical strength of bone. As for the inclusion/exclusion criteria of patients: We apologize, since it was not clear from the brief text that all patients undergoing primary total hip arthroplasties under the care of our collaborating orthopedic surgeons were approached to participate in this study. No other criteria were applied. Finally, we agree with Phillips et al. that the work presented here does not conclusively address the effects of long-term administration of environmental levels of fluoride on the mechanical properties of bone. To do that, we would need to track not only the duration of exposure to fluoridated water, as they point out, but also factors such as diet (Singer et al., 1985) and use of fluoride-containing oral care products and fluoride supplements (Ismail, 1994; Whitford, 1994). Gathering these kinds of detailed data retroactively for the requisite period of many decades is prohibitive. As well, beverages and foods are increasingly prepared with fluoridated water (Clovis and Hargreaves, 1988), so living in a non-fluoridated area does not guarantee the absence of exposure to environmental fluoride. This inability to measure the exposure accurately was the rationale for the comparison of mechanical properties with the fluoride content of the bone tissue, measured directly. Fig. 2 (p. 1222) displays the wide variation in response to fluoride, since only about 5% of the variability in the data could be explained by the fluoride content. As we pointed out, this is consistent with many decades of epidemiological studies that have failed to find a relationship between fluoride exposure and bone quality (McDonagh et al., 2000). In agreement with Phillips et al., we wrote in the conclusions of our paper (p. 1222) that we cannot rule out subtle effects of long-term ingestion of fluoride on the mechanical properties of bone, especially in the case of susceptible individuals. However, at the population level, there is no substantive evidence that fluoridated drinking water alone has an effect on bone quality.