Bonding in dentistry technically means attaching a material substance to the tooth structure through a chemical bond. Typically it is used by many people to describe three different processes: recontouring front teeth to fill unsightly gaps, repairing chipped corners or edges on front teeth or putting a veneer of composite resin over the whole surface of a tooth to change its color or contour. Bonding is actually used in many ways in cosmetic dentistry today: 1. Repair or fill abraded and sensitive areas of teeth at the gum line 2. Fill cavities or chipped and broken areas of front teeth 3. Minor reshaping or recontouring teeth to provide more natural contours and contacts between teeth 4. Filling cavities in back teeth with composite resins in place of silver amalgam 5. Sometimes resurfacing the whole face of a tooth (best accomplished by bonding a porcelain veneer rather than composite resin) 6. The sealants used to "seal" and protect the grooves in children's teeth are bonded flowable composite resins 7. Bonded cements are used now to chemically bond crowns and bridges to their anchor teeth. If properly applied, bonded restorations preserve more tooth structure than traditional fillings because deeper drilling is not required just to "retain" the material as with older methods. Bonded restorations are strongest at the place where tooth and bonding meet, so these restorations do not tend to chip and pull away from tooth structure and leak at the margins as the older materials did. Since there is ofte less drilling required and less marginal leakage, bonded restorations are typically less sensitive afterwards than the older methods and often can be done during the appointment without anesthetic. These restorations are much better looking than the older materials. Composite resins come in many shades to better match tooth color. Due to the bonding and expansion properties of composites, there seem to be fewer cracked and broken teeth with these restorations. Tooth bonding itself is a one visit procedure, though the bonding can be associated with restorations that have been made in a laboratory. If the area of tooth to be restored is small, the materials used usually require only one visit. Larger areas require the two visit procedures. If done in two visits, there will be a temporary restoration (usually also a composite resin) placed with a sedative temporary cement. Before bonding, any decay or old filling material present is removed. Then the tooth surface to be bonded is slightly roughened and treated with a mild etchant to provide maximum bond strength. Then the bonding materials are placed in a layered sequence and "cured" with a high intensity light after each layer. Then the restoration is shaped and polished to a smooth finish and proper contour and fit with adjacent and opposing teeth. Sometimes the tooth and bonding are then treated again and "sealed" with a clear sealer layer of bonding material. It is very important to maintain the bonded restorations just like teeth by carefully brushing and flossing using a non-abrasive toothpaste. If many of the biting surfaces of teeth have been restored or there is a history of grinding or clenching of the teeth, then the dentist may recommend a plastic guard, called "occlusal guard" or "night guard" since many people wear them at night. This guard protects the jaw joints and teeth as well as the restorations.