Choosing a Toothbrush.
Tooth brushing is the major behavior performed by patients to fulfill their needs to feel clean and fresh and to avoid dental problems.  It is also considered by the dentist-dental hygienist team to be the major tool in the removal and control of dental biofilm and the prevention of periodontal diseases and dental caries.
Effective brushing is important but so is the design and selection of the brush.  Not all brushes are the same.  By using the appropriate brush and technique together, patients can maximize their daily oral hygiene efforts.
Why must plaque be removed?  When the plaque matures, the microbial ecology changes and becomes pathogenic due to the different microorganisms, their by-products, and in the case of gum disease, the inflammatory response provoked by the host.
For gum health the plaque must be removed from:
*the healthy sulcus or shallow pocket, the ideal anaerobic breeding ground
*the gum tissue where maturing and growing supra gingival plaque deposits are in contact with the marginal gum tissue and can alter the sub gingival environment
*the interproximal areas-in between the teeth, which are hard to reach.
For cavity prevention:
Plaque must be removed from the the gum line, pits and grooves in the teeth and the interproximal areas.
Understanding the different elements of toothbrush design will help with making the correct selection.
Head and Bristles
The toothbrush head is an extension of the handle and is contoured to position the bristles.  Bristles are typically round nylon filaments.  The degree of hardness is determined by the diameter and the length of the bristles.  Larger diameter bristles are stiffer and do not extend as easily into hard to reach areas.  The shape of the end of the bristle has evolved over many years.  The tapering of the bristle allows greater flexibility and slenderness to reach deep into the sulcus.  A recently introduced bristle has a feathered tip, providing up to 70% more surface contact with the tooth.  Positioning of the bristles is also important.  Positioning tufts10 -20 degrees away from the vertical axis increases interproximal penetration.  A dome-shaped head of bristles, where the bristles are raised in the center, has been shown to increase plaque removal.
Handle
The ideal handle grip should aid in holding the brush at the correct angle so the bristles are present at 45 degrees to the long-axis of the tooth.  Is should be long enough to provide adequate grip to give full control, and the distance between the grip area and the head should enable easy access to the most posterior teeth.
Toothbrushes alone do not lead to adequate plaque removal.  There is a clear need for between-the-teeth cleaning.  This includes flossing and interproximal brushes.  These are available in a wide variety of designs and a high level of customization is available.
Summary
*The bristles must be effective in cleaning the hard-to-teach areas-extremely tapered bristles have demonstrated superiority
*The handles should have a grip designed to automatically position the brush to achieve the correct angle
*The brush is only one element of a plaque removal system
*The brush should be readily available commercially
*The brush head should be compact to reach to the back of the mouth and have soft bristles to minimize soft and hard tissue trauma and sensitivity, while maximizing cleaning
*The brushes should be designed and manufactured by a long-established supplier of scientifically tested toothbrushes