Guided tissue regeneration using a bioabsorbable membrane: a 21-case series.

Background: The purpose of this paper is to demonstrate how a bioabsorbable membrane in the treatment of intrabony defects, combined with appropriate case selection, produces a significant improvement in the clinical assessment of affected teeth. This study demonstrates success in 21 successive cases.

Methods: Consecutive patients presenting advanced intrabony defects (8 to 15 mm) meeting the predetermined criteria were treated by guided tissue regeneration (GTR) with flap debridement and placement of a bioabsorbable copolymer membrane.

Response allocation to concurrent fixed-ratio reinforcement schedules with work requirements by adults with mental retardation and typical preschool children.

The present experiments examined the effect of work requirements in combination with reinforcement schedule on the choice behavior of adults with mental retardation and preschool children. The work requirements of age-appropriate tasks (i.e.