Product Development Background


Curvex and its derivatives were developed to offer innovative toothbrushes with bristle arrays that would not only geometrically fit the most difficult-to-clean areas of the mouth, but would also utilize the softest filaments in the accepted range of “soft” toothbrushes, while maintaining plaque removal efficacy. Within this category, 0.007 inches diameter bristle filaments are the most commonly used, but they can be as large as 0.008 inches, (also the start of the “medium range”) or as small as 0.006 inches (typically labeled Extra Soft.)

From the outset of the development effort, three main considerations were recognized:(1) the softer the bristle, the greater the risk that bristle deformation would occur from brushing in the customary to-and-fro motion; (2) a softer bristle must achieve an adequate level of plaque removal; and (3) if a softer bristle could be successfully integrated into the brushhead design, there could be benefits to the gingival health of the user, as well as creating a more comfortable brushing experience.

Concept & Theoretical Research

A key concept underlying the development of Curvex was that the brushhead would incorporate a tapering bristle array at each end of a larger planar mid-section bristle grouping. While that central segment would function to clean the most easily-reached areas (e.g. facial surfaces of teeth), the tapering ends would result in an innovative geometric fit that more closely approximates the lingual anterior curve of the upper and lower arches. In addition, when brushing in the usual longitudinal to-and-fro motion, the end bristle groupings could support the larger mid-section and thus potentially reduce bristle splaying. This would permit use of the softer 0.006 inch diameter filament without reducing plaque removal efficacy.

To complement this unique bristle array, a convex head was devised. By curving away from the roof of the mouth, this not only allowed the toothbrush to reach further back (when brushing the lingual of upper molars), but also enabled the end bristle groups to easily gain contact behind any terminal molar. This configuration also meant that the toothbrush could avoid hitting the mandible when reaching the lingual surfaces of lower molars.

As a third primary design feature, the neck and handle of the toothbrush were reverse-curved -- unlike most conventional toothbrushes -- to allow further reach without hitting the tips of the upper and lower anterior teeth.

Initial Testing

Dr. Harada developed initial prototypes of his envisioned product by modifying commercially-available toothbrushes to his specifications and design. Over a six-month period, he provided samples to a limited number of dental professionals for evaluation. With their very encouraging feedback, he was determined to advance the product development effort.

Initial Commercialization

After further trials to determine optimum dimensions for strength, design, ergonomics and commercial engineering, design engineers were recruited to construct computer assisted design (CAD) drawings with which to create a mould. A pilot run of toothbrushes was made and distributed to selected dental professionals. The positive response prompted investment in increased production capactity.


The FDA was consulted and their registration requirements were met. In addition, US patents were awarded to both the Curvex and Curvex II.