To date, porcelain laminate veneers have been used primarily to solve esthetic problems. As bonding materials and veneer restoration techniques have improved, however, functional demand has now been accepted. Porcelain laminate veneers have been applied to compensate for the limitations of orthodontic treatment. In order to allow optimum functional movement of the mandible, anterior and lateral guidances are required in the maxillary dentition. These guidances provide pathways for the opposing mandibular teeth. Anterior and canine guidances have been established by means of veneer placement, and no broken restorations have been observed in the past four years. When diastema spaces have recurred subsequent to orthodontic space closure, they have been restored with porcelain veneers so effectively that no relapse has been observed. This paper also examines instances where small lateral incisors have caused a discrepancy in the tooth size ratio between the upper and lower arches. Porcelain veneers were placed to harmonize the tooth size and to stabilize the occlusion. Relapse sometimes occurs after orthodontic tooth alignment. Over correction, therefore, is usually applied for rotated teeth, anterior deep or open bite, and Class II or III molar relationships. Some malocclusions, however, cannot be over corrected. For example, the spacing between the teeth, such as diastema, can easily reopen because it is impossible to apply over correction once space closure has been achieved. The same is true of lateral open bites, because occlusal contact cannot be corrected properly. In these cases, the patient must wear a retainer for longer than usual, and/or permanent splints must be used to stabilize the occlusion. Another causal factor of relapse is dysfunctional occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)