The effect of EHDP concentration on enamel demineralization in vitro

Efficacy of bisphosphonates in detection of early enamel caries using NIR fluorescence imaging and inhibition of caries progression

NIR fluorescence imaging using bisphosphonate-Indocyanine green has been indicated for early interproximal caries detection. This study assessed diagnostic accuracy of caries detection by NIR fluorescence imaging with OsteoSense 750^® (OS750) in vitro and ex vivo, and to analyze the therapeutic efficacy of a bisphosphonate (Etidronate) in inhibiting enamel caries progression in vitro. Methods: Four experiments were conducted using extracted human teeth; 1) to calculate the infiltration rate of OS750 into interproximal white spot lesions using fluorescence microscope, 2) to assess diagnostic accuracy of interproximal natural white spot lesions using desktop NIR fluorescence imaging device in vitro setting, 3) to assess diagnostic accuracy of artificially created deeper enamel carious lesion (0.5 mm~1.0 mm) using NIR fluorescence image through the head-mount display in ex vivo setting, 4) to compare the progression on the enamel caries lesions treated by Etidronate, NaF and distilled-water. Diagnostic accuracy was analyzed using sensitivity, specificity and receiver operating curves (ROC). The caries progression was calculated with micro-CT and was statistically analyzed using a two-way ANOVA and the Tukey HDS post-hoc test. Results: 1) The infiltration rate of OS750 was 101.83% ± 8.66 (Min: 90.10%, Max: 133.94%). 2) The average of sensitivity and specificity in vitro setting experiments were 86.7% ± 4.4% and 70% ± 11%, respectively. The average of area under the ROC curves (AUC) was 0.883 ± 0.059 indicating excellent performance. 3) The mean sensitivity and specificity in ex vivo setting was 82.97% ± 15% and 76.78% ± 13.27% respectively. 4) The carious lesion volume treated by Etidronate was significantly smaller at post treatment-1 (p<0.05) and treatment-2 (p<0.01) than the control. There was no significant difference in lesion volume in the Etidronate and NaF group at the time point of post treatment-1. Conclusion: This study suggests that bisphosphonates contribute to both early diagnosis of enamel caries and inhibition of caries progression.

The application of in vitro models to research on demineralization and remineralization of the teeth

Progress in in vivo and in situ experimentation has led many researchers to speculate as to the relevance and importance of in vitro testing protocols in caries research. A Medline/Biosis search for the present review revealed well over 300 citations (since 1989) documenting in vitro tests associated with caries research on mineralization and fluoride reactivity. The present survey documents these recent applications of in vitro test methods in both mechanistic and 'profile' caries research. In mechanistic studies, in vitro protocols over the past five years have made possible detailed studies of dynamics occurring in mineral loss and gain from dental tissues and the reaction dynamics associated with fluoride anticaries activity. Similarly, in profile applications, in vitro protocols make possible the inexpensive and rapid--yet sensitive--assessment of F anticaries efficacy within fluoride-active systems, and these tests represent a key component of product activity confirmation. The ability to carry out single variable experiments under highly controlled conditions remains a key advantage in in vitro experimentation, and will likely drive even further utilization, as advances continue in physical-chemical and analytical techniques for substrate analysis in these protocols. Despite their advantages in vitro testing protocols have significant limitations, most particularly related to their inability to simulate the complex biological processes involved in caries.

Clinical effects of bisphosphonates in involutional osteoporosis

The bisphosphonates are analogs of naturally occurring pyrophosphate. They appear to block bone resorption much more than mineralization. A series of compounds has been investigated. These have antiresorptive potencies ranging from 1 to 10,000. So far, structure-function relationships have eluded definition. These drugs increase the bone density in women with postmenopausal osteoporosis by about 5%-10% over 1 year. The bone density then appears to plateau, but most studies are of short duration. Improved bone density does not necessarily result in stronger bone, but no studies have had adequate power to assess fracture incidence. Bone formation rates decrease as measured histomorphometrically. This occurs while the bone density is improving, which implies an inhibition of bone resorption that is probably due to direct toxicity to the osteoclasts. Etidronate blocks mineralization as well as resorption and can cause osteomalacia, which is not seen with low-dose cyclical etidronate or with the second-generation compounds. The long-term effects of interfering with the remodeling cycle are still not known. Subtle side effects may be those on the bone itself. These might go undetected, since bone pain or fractures usually are attributable to the underlying disease.