Brush head composition, wear profile, and cleaning efficacy: an assessment of three electric brush heads using in vitro methods.

OBJECTIVE: The objective of this research was to evaluate a current store brand (SB) brush head for composition/physical characteristics, Wear Index (WI), and cleaning efficacy versus the previous SB brush head refill design (SB control) and the Oral-B Precision Clean brush head (positive control, PC). METHODS: This research consisted of three parts: 1) Analytical analysis using Fourier Transform Infrared (FT-IR) spectrometry to evaluate the chemical composition of the current SB brush head bristles relative to the SB control. In addition, physical parameters such as bristle count and diameter were determined. 2) Wear Index (WI) investigation to determine the Wear Index scores of in vitro-aged brush heads at four weeks (one month) and 13 weeks (three months) by a trained investigator. To "age" the brush heads, a robot system was used as a new alternative in vitro method to simulate aging by consumer use. 3) Robot testing to determine the cleaning performance of in vitro-aged brush heads, comparing one month-aged current SB brush heads with the SB control (one and three months-aged) and the PC brush heads (three months-aged) in a standardized fashion. RESULTS: 1) FT-IR analysis revealed that the chemical composition of the current and control SB refill brush heads is identical. In terms of physical parameters, the current SB brush head has 12% more bristles and a slightly oval brush head compared to the round brush head of the SB control. 2) Wear Index analysis showed there was no difference in the one month-aged current SB brush head versus the one month-aged SB control (1.67 vs. 1.50, p = 0.65) or versus the three months-aged PC brush head (1.67 vs. 1.50, p = 0.65). The one month-aged current SB brush head demonstrated statistically significantly less wear than the three months-aged SB control (1.67 vs. 2.67, p = 0.01). 3) Analysis of cleaning efficacy shows that the one month-aged current SB brush head had improved cleaning performance over the one month-aged SB control brush head (p < 0.05), despite no statistically significant difference in wear. Both the one month-aged current and control SB brush heads showed statistically significantly lower cleaning performance compared to the three months-aged PC brush heads (p < 0.01). CONCLUSION: While the current SB brush head showed improved cleaning over the SB control, it demonstrated significantly lower durability and cleaning in comparison to the PC brush head. Dental professionals should be aware of these differences, both in durability and in cleaning performance, when recommending brush heads to their patients.

Long-term response of osteogenic cells on micron and submicron-scale-structured hydrophilic titanium surfaces: sequence of cell proliferation and cell differentiation.

OBJECTIVE: Modifications of surface topography and surface chemistry are key factors for guiding target cells during dental implant healing. Recent in vitro studies confirmed promotion of early osteogenic cell differentiation on submicron scaled surfaces in particular when hydrophilized. However, no long-term observations on both osteogenic cell proliferation as well as on cell maturation have been reported for respectively modified surfaces. Aim of this study was to monitor osteogenic cell proliferation and expression of specific osteogenic cell differentiation markers on a protein level over an extended period of 3 weeks with respect to surface modifications. MATERIAL AND METHODS: Modified titanium (Ti) disks were obtained from Institute Straumann, representing the following surfaces: smooth pretreatment (PT), sandblasted/acid etched (SLA), and hydrophilized (modSLA). Surface topography was analyzed by scanning electron microscopy, surface elemental composition was assessed by X-Ray Photoelectronic Spectroscopy (XPS). Tissue culture polystyrene (TCPS) served as a control substrate. Human osteogenic cells (HOB-c) were cultivated on the respective substrates. After 24 hrs, 48 hrs, 72 hrs, 7 d, 14 d and 21 d, cell count was assessed as well as osteogenic cell differentiation utilizing cellular Quantitative Immuno-Cytochemistry (QIC) assay for collagen type I (COL), alkaline phosphatase (AP), osteopontin (OPN) and osteocalcin (OC). Data were normalized with respect to internal controls. RESULTS: In contrast to the other modified Ti disks, modSLA stands out due to low surface carbon contamination. TCPS and PT surfaces preserved a rather immature, mitotic active osteogenic phenotype (high proliferation rates, no increase of OC production), SLA and especially modSLA surfaces promoted the maturation of osteogenic precursors into post-mitotic osteoblasts. In detail, modSLA resulted in lowest cell proliferation rates, but exhibited highest expression rates of OC. DISCUSSION: Our results, which confirm previous studies, reveal long-term promotion of osteogenic cell maturation by topography (micron and submicron scale roughness) and surface hydrophilicity.

Stannous fluoride/sodium hexametaphosphate dentifrice increases dentin resistance to tubule exposure in vitro.

OBJECTIVE: The purpose of this study was to compare the reactivity of three dentifrice formulations on smear layer-covered root dentin surfaces, and the effects of the formulation treatments on resistance to acid softening and dentinal tubuli disclosure. METHODOLOGY: Commercial dentifrices, including Crest Cavity Protection Regular, Colgate Total, and a new dentifrice comprised of stannous fluoride/sodium hexametaphosphate (SnF2/HMP: Crest Pro-Health), were cycled through a pre-treatment period on smear layer-covered dentin surfaces, including intermittent soaking in dentifrice slurries and whole human saliva immersion. Following pre-treatments, the cycling treatments were modified to include dietary acid exposure, including soaks in an acidic soft drink. Vickers surface microhardness, variable pressure scanning electron microscopy (VP-SEM), and confocal laser scanning microscopy in reflection mode (CLSM) were used to characterize dentin reactivity and smear layer protection. RESULTS: CLSM and SEM analyses showed that specimens treated with SnF2/HMP appeared to resist acid solubilization, evidenced by the absence of disclosed dentinal tubuli. The histo-tomographic observations in this study were in agreement with the hardness measurements. The superior surface protection of dentin with SnF2/HMP would suggest potential benefits in ameliorating dentinal hypersensitivity in the clinical situation. CONCLUSION: A stannous fluoride/sodium hexametaphosphate dentifrice prevents dietary acid softening and tubule exposure of smear layer dentin surfaces.