Faculty Bibliography

Plasma-sprayed HA coating combines the strength of the metal and the bioactivity of the HA. However, this method has several disadvantages. Alternatives to the plasma-spray method such as electrochemical deposition (ECD) and biomimetic or precipitation methods are being explored. The purpose of this study was to develop an ECD method for coating Ti alloy substrate with different calcium phosphates (octacalcium phosphate, calcium deficient apatite, carbonate-substituted apatite, fluoride-substituted apatite). Pairs of Ti6Al4V plates that have been mechanically polished, ultrasonically cleaned, acid etched, rinsed and dried were used as anodes and cathodes. ECD was carried out using programmed pulse time electric fields. Results showed that uniform coating with only the desired calcium phosphate can be obtained using metastable calcium phosphate solutions at different pH and temperature conditions and different electrolyte concentrations. Coating thickness varied with the duration of coating deposition. Crystal size varied with other ECD conditions (e.g., pulse time, current density). This method can be used to obtain uniform coating of the desired calcium phosphate composition at low temperatures (25 to 80 degrees C) on substrates of any type of geometry

This study aimed to investigate the formation and properties of magnesium (Mg)-substituted tricalcium phosphate, beta-TCMP, its properties and potential as biomaterial for bone repair. beta-TCMPs were prepared and characterized using x-ray diffraction, FT-IR and SEM. Dissolution properties were determined in acidic buffer. beta-TCMP discs were implanted in surgically created holes in femoral and tibial diaphyses of rabbits. Results demonstrated that the formation of beta-TCMP and Mg incorporation in beta-TCMP were dependent on reaction pH, temperature and solution Mg/Ca ratios. Sintered beta-TCMP was significantly less soluble than beta-TCP. Implanted unsintered beta-TCMP showed osteoconductive properties associated with new bone formation. This study suggests that beta-TCMP (sintered or unsintered), alone or in combination with other calcium phosphates, may be useful as biomaterials for bone repair and maybe useful in cases where slower biodegradation than that of beta-TCP is desired

BACKGROUND, AIMS: Differences in prevalence, severity and risk factors for destructive periodontal diseases have been reported for ethnic/racial groups. However, it is not certain whether this disparity is due to ethnicity/race or factors associated with ethnicity/race. Therefore, the present study addressed whether the rates of disease progression and clinical and demographic factors associated with disease progression varied among three ethnic/racial groups. METHODS: The study population consisted of 53 Asian-, 69 African- and 62 Hispanic-Americans. Clinical measurements included probing depth, attachment level, gingival erythema, bleeding upon probing, suppuration and plaque. Disease progression was defined as a > 2 mm loss of attachment 2 months post baseline. The demographic variables examined included occupational status, report of a private dentist, years resident in the United States and smoking history. RESULTS: The rate of attachment loss for the entire population was 0.04 mm or 0.24 mm/year. No significant differences were found among the three ethnic/racial groups. Variables associated with subsequent attachment loss for the entire population were age, male gender, mean whole-mouth plaque, erythema, bleeding upon probing, suppuration, attachment loss and probing depth, and belonging to the "unskilled" occupational group. No differences in risk profiles were found among the 3 ethnic/racial groups. Using stepwise logistic regression analysis, a model was developed to relate the clinical and demographic variables examined with subsequent attachment loss. The model indicated that prior attachment loss, gingival erythema, suppuration, being a current smoker and belonging to the "unskilled" occupational group conferred high risk of > 1 site of attachment loss of > 2 mm. CONCLUSIONS: The results of this study suggest that variables associated with ethnicity/race, such as occupational status, are largely responsible for the observed disparity in destructive periodontal disease progression in these populations.

PURPOSE: To test the hypothesis that anticalculus agents cannot completely inhibit calculus formation but can influence the types of calcium phosphate which form, i.e., they can influence the composition of the inorganic component of human dental calculus (HDC). MATERIALS AND METHODS: The composition of HDC specimens obtained from a 16-week multi-center clinical study using three regimens were analyzed, investigators blinded. The treatment regimens were: (a) standard dentifrice (SD), (b) pyrophosphate antitartar dentifrice, and (c) SD with Tartar Control Listerine Antiseptic mouthrinse (containing essential oils and 0.09% zinc chloride). 25 individual samples and eight pooled samples from each group were analyzed using X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. RESULTS: (1) relative frequency of occurrence for: (a) bacteria: Group A = 100%, Group B = 60%, and Group C = 25%; (b) Carbonate hydroxyapatite (CHA): Groups A, B, and C = 100%; (c) dicalcium phosphate dihydrate (DCPD): Group A = 55%; Group B = 45%; Group C = 80%; (2) The relative amount of DCPD is inversely proportional to that of CHA in HDC: the higher the amount of DCPD, the lower the amount of CHA. Group C regimen with essential oil/ZnCl2 mouthrinse and standard dentifrice showed a significant anti-microbial effect and favored the formation of DCPD, the most soluble Ca-P.

Biphasic calcium phosphate (BCP) ceramics consist of intimate mixture of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) in varying HA/beta-TCP ratios. BCP bioceramics are commercially available and is gaining greater acceptance as bone substitute materials in many dental and medical applications. The purpose of this study was to explore different methods of preparing BCP and determine their dissolution properties. Calcium-deficient apatites (CDA) were prepared using the following methods: (1) precipitation or (2) hydrolysis of dicalcium phosphate dihydrate (DCPD) or dicalcium. phosphate anhydrous (DCPA) under different solution composition, pH and temperature conditions. CDA and the BCPs obtained after sintering CDA after above 700degreesC were characterized using scanning electron microscopy, x-ray diffraction and FTIR. Dissolution properties were determined from the release of calcium ions with time onto acidic buffer. Results demonstrated that BCP composition is affected by the reaction conditions in the CDA preparation. Dissolution properties in vitro depended on the HA/beta-TCP ratio of the B

Biphasic calcium phosphate (BCP) bioceramics belong to a group of bone substitute biomaterials that consist of an intimate mixture of hydroxyapatite (HA), Ca(10)(PO(4))(6)(OH)(2), and beta-tricalcium phosphate (beta-TCP), Ca(3)(PO(4))(2), of varying HA/beta-TCP ratios. BCP is obtained when a synthetic or biologic calcium-deficient apatite is sintered at temperatures at and above 700 degrees C. Calcium deficiency depends on the method of preparation (precipitation, hydrolysis or mechanical mixture) including reaction pH and temperature. The HA/beta-TCP ratio is determined by the calcium deficiency of the unsintered apatite (the higher the deficiency, the lower the ratio) and the sintering temperature. Properties of BCP bioceramics relating to their medical applications include: macroporosity, microporosity, compressive strength, bioreactivity (associated with formation of carbonate hydroxyapatite on ceramic surfaces in vitro and in vivo), dissolution, and osteoconductivity. Due to the preferential dissolution of the beta-TCP component, the bioreactivity is inversely proportional to the HA/beta-TCP ratio. Hence, the bioreactivity of BCP bioceramics can be controlled by manipulating the composition (HA/beta-TCP ratio) and/or the crystallinity of the BCP. Currently, BCP bioceramics is recommended for use as an alternative or additive to autogeneous bone for orthopedic and dental applications. It is available in the form of particulates, blocks, customized designs for specific applications and as an injectible biomaterial in a polymer carrier. BCP ceramic can be used also as grit-blasting abrasive for grit-blasting to modify implant substrate surfaces. Exploratory studies demonstrate the potential uses of BCP ceramic as scaffold for tissue engineering, drug delivery system and carrier of growth factors.

Disparities in the prevalence and severity of destructive periodontal diseases have been reported for American minority populations and have raised the following questions. Are differences in destructive periodontal disease prevalence and severity due to genetic or other confounding variables associated with ethnicity race? Do risk factors for destructive periodontal diseases differ among American minority populations or differ from the population at large? Answers to these questions will have profound impact on the direction of future research and the allocation of resources to address disparities in destructive periodontal diseases in American minority populations. Risk assessment studies that examined a set of clinical, demographic, immunologic, and microbiologic parameters of Asian Americans, African Americans, and Hispanic Americans resident in the greater New York City region suggest that occupational status, monitored as a surrogate variable for socioeconomic status, may be a more robust risk factor than ethnicity/race for destructive periodontal diseases in these populations

According to available limited epidemiology studies, the prevalence of oral disease is much greater in American minorities (Blacks, Hisoanics, Asians, Native Americans) than in the majority population. The purpose of this article is to describe the oral health status and current treatment needs of a group of African-American (AA) adults in New York City. The convenience sample consisted of 951 AA adults (M = 662, F = 289) recruited through community- or faith-based institutions, and the in-house screening conducted by the Research Center for Minority Oral Health in dedicated dental clinics at the New York University College of Dentistry. The age of participants ranged from 18 to 64 years, (mean age 42, SD = 11.04). Calibrated examiners performed the clinical examinations utilizing National Institute of Dental and Craniofacial Research (NIDCR) diagnostic criteria. The DMFT, DMFS, DFS, and %D/DFS indices were obtained and results indicated the following. For the 18 to 34 age group (n = 246), the mean DMFT was 8.83, the mean DMFS was 21.36, the mean DFS was 12.10, and the mean %D/DFS was 30. For the 35 to 49 age group (n = 523), the mean DMFT was 14.03, the mean DMFS was 48.21, the mean DFS was 18.76, and the mean %D/DFS was 29. For the 50 to 64 age group (n = 182), the mean DMFT was 15.38, the mean DMFS was 64.48, the mean DFS was 17.98, and the mean %D/DFS was 29. For all age groups, the findings indicated a high prevalence of dental decay and greater number of filled surfaces compared with the United States national surveys.