Scanning electron microscopic study of the effect of salivary pellicle on enamel erosion

A bovine tooth model system was used to study the effect of experimental salivary pellicle on enamel erosion. Test blocks with varnish-covered control surfaces in each specimen were immersed into an acidic cola beverage (pH 2.6) for 120 min, either with or without the pellicle which was grown for 7 days by using clarified human saliva. After immersion, the pellicle was removed from some specimens with 10% sodium hypochlorite (20 h at 20 degrees C) and ultrasonic bath (60 s) to study its effect on erosion. All specimens were then studied in the scanning electron microscope. The specimens without pellicle (positive controls) showed gross erosion with prism core dissolution in all study blocks. The specimens with pellicle showed occasionally a film-like integument covering the apparently intact test surfaces with adjacent enamel surfaces slightly eroded. The erosion, however, was not of the same magnitude as in the positive controls. After removing the pellicle, the enamel surfaces showed pitted appearance of the prism heads; the demineralization seemed to attack more the prism sheath areas. Thus, salivary pellicle was found to protect the underlining enamel from erosion in vitro.     

Utility of the Dental Aesthetic Index in Industrialized and Developing Countries

To be truly useful, an index must be applicable universally without modification. The data presented in this article support the use of the standard DAI without modification to assess need for orthodontic treatment in both developing and industrialized countries. When students from Thailand, Australia, the German Democratic Republic, and Native Americans residing on Indian reservations rated the same 25 occlusal stimuli (photographs of dental configurations) for dental aesthetics, their ratings of these stimuli when arranged in rank order were highly correlated with those of US students. These 25 occlusal stimuli were a subset of the original 200 occlusal stimuli used in deriving the standard DAI regression equation. This article presents data indicating that when a Native American DAI was derived based on Native American ratings of the same 200 occlusal stimuli used in deriving the standard DAI, the Native American DAI and the standard DAI had the same ten components (orthodontic measurements) and strikingly similar regression coefficients (weights). Further analysis indicated that the two equations were sufficiently similar to justify using the standard DAI to obtain DAI scores on Native Americans and to estimate the relative social acceptability of their dental aesthetics. If ratings for dental aesthetics for the full set of 200 stimuli were available for each of the countries where only 25 were rated, we expect that, as in the case of Native Americans, a country-specific DAI, if computed, would be sufficiently similar to the standard DAI that no modification would be needed to allow use of the standard DAI in that country.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early soft tissue healing around one-stage dental implants: clinical and microbiologic parameters

BACKGROUND: Despite the potential significance of early soft tissue healing to long-term outcomes, this aspect of one-stage dental implants has not been investigated. The purpose of this prospective study was to characterize clinical and microbiologic parameters of early soft tissue healing around dental implants placed following a one-stage protocol. METHODS: Twenty-one patients (11 females and 10 males, aged 18 to 78 years; two smokers) needing a single implant were included. Clinical parameters included probing depth, buccal flap thickness, papilla height, and bleeding on probing. Subgingival plaque samples were obtained pre- and postoperatively and analyzed using molecular techniques. RESULTS: The newly formed peri-implant sulcus probing depth remained fairly stable from 4 to 12 weeks (P > 0.05). There was no statistically significant association between flap thickness or papillary height and number of implant bleeding sites at 12 weeks (P > 0.05). Detection of known periodontal pathogens was rare. Fusobacterium nucleatum was present in 17 patients prior to surgery, and 71% of them became carriers of this bacterium at the implant site by the second postoperative week. The number of F. nucleatum-positive subjects around the implant was significantly lower than the number of F. nucleatum-positive subjects around teeth (P < 0.05). CONCLUSIONS: Peri-implant soft tissue clinical maturity may be established as early as 4 weeks following implant placement by a one-stage surgical protocol; neither preexisting flap thickness nor papillary height seemed to influence newly forming peri-implant sulcus depth or bleeding on probing prevalence. For the most part, the newly created peri-implant crevices were colonized by specific bacteria within 2 weeks.     

Comparative unsupervised clinical trial on caries inhibition effect of monofluorophosphate and amine fluoride dentifrices after 3 years in Strasbourg, France

A randomized, double blind clinical trial of the caries inhibition effects of dentifrices containing respectively monofluorophosphate and amine fluoride was performed. A third control group used a toothpaste without fluoride. A total number of 2008 schoolchildren ranging in age from 6 to 8 years and living in Strasbourg (France) participated in this study. After a baseline examination three groups were constructed with the block randomization technic. The caries inhibition effects of the three dental pastes were compared after 3 years of unsupervised use. The monofluorophosphate dentifrice showed a reduction of 7.02% for DMFT, 5.17% for DMFS and 25.26% for the df rate. The reduction of amine fluoride dentifrice caries was respectively 21.62% for DMFT, 20.94% for DMFS and 48.66% for the df rate.     

Crystallographic properties of a series of synthetic hydroxyapatites

The crystallographic properties of hydroxyapatites synthesized at temperatures of 200 degrees C, 500 degrees C, 900 degrees C and 1250 degrees C, designated HAP200, HAP500, HAP900 and HAP1250, respectively, were studied using X-ray powder diffraction. Values of a-axis length for the hydroxyapatites ranged from 9.406 A to 9.416 A, which were smaller than the corresponding value for stoichimetric hydroxyapatite, a = 9.418 A. Generally, the a-axis length decreased with the synthesis temperature, except for HAP500 which showed the smallest value. Crystallinity of the hydroxyapatites, measured by X-ray diffraction peak broadening as full width at the half-maximum value (FWHM), increased with the synthesis temperature, although HAP500 showed a decrease. These results suggest that the synthetic hydroxyapatites contained some carbonate ions, probably at the A-site of the apatite structure, and that the structure was depleted of carbonate ions at about 500 degrees C.     

Histological and immunohistochemical analysis of initial and early osseous integration at chemically modified and conventional SLA titanium implants: preliminary results of a pilot study in dogs

OBJECTIVES: The aim of the present pilot study was to investigate initial and early tissue reactions to modified (mod) and conventional sand-blasted, large grit and acid-etched (SLA) titanium implants. MATERIAL AND METHODS: Implantation of modSLA and SLA implants was performed bilaterally in both the mandible and maxilla of dogs. The animals were sacrificed after a healing period of 1, 4, 7 and 14 days, respectively. Peri-implant tissue reactions were assessed in non-decalcified tissue sections using conventional histology (Toluidine blue-TB and Masson Goldner Trichrome stain-MG) and immunohistochemistry using monoclonal antibodies to transglutaminase II (TG) (angiogenesis) and osteocalcin (OC). Bone density (BD) and bone to implant contact (BIC) were assessed histomorphometrically. RESULTS: Day 1 revealed an early TG antigen reactivity in the provisional fibrin matrix adjacent to both implant surfaces. Day 4 was characterized by the formation of a collagen-rich connective tissue (MG), which revealed the first signs of OC synthesis adjacent to modSLA surfaces. Immunohistochemical staining for TG revealed a direct correlation between angiogenesis and new bone formation, which was clearly identifiable after 7 days by means of increasing BD, BIC and OC values. After 14 days, modSLA surfaces seemed to be surrounded by a firmly attached mature, parallel-fibered woven bone. CONCLUSIONS: Within the limits of the present study, it might be concluded that the combination of immunohistochemical and conventional histological stainings in non-decalcified tissue sections is a valuable technique to evaluate the initial and early stages of wound healing around endosseous titanium implants.