BOOK REVIEWS
Twin Block Functional Therapy: Applications in Dentofacial Orthopaedics
WILLIAM J. CLARK, BS, DDO
2nd edition. 384 pages. 1,344 illustrations. $160. 2002.
Mosby
11830 Westline Industrial Drive
St. Louis, MO 63146
(800) 325-4177; www.mosby.com
As the author insightfully points out in the preface to this book, there are two great controversies in theoretical orthodontics that were left unresolved at the end of the 20th century. The first is the endless extraction vs. nonextraction debate--from the heated battles of Angle and Case around the turn of the previous century, through the mid-century extractionist philosophies of Tweed and Begg, to the current populist-based anti-extractionism.
The second unresolved controversy centers around functional appliances and their ability to address growth discrepancies between the two jaws. Put otherwise, the question is whether non-surgical dentofacial orthopedics as a means of growth modification is a viable treatment option.
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In the first edition of Twin Block Functional Therapy, William Clark presented a user-friendly, highly adaptable, removable functional appliance--the twin block--that seemed capable, through a number of possible variations, of correcting skeletal discrepancies in all three planes of space. In this second edition, Dr. Clark elaborates further on the myriad clinical applications of his versatile appliance, while providing a wealth of references from reputable orthodontic journals to support the orthopedic nature of functional appliance therapy.
Dr. Clark presents case after case beautifully illustrating applications of the twin block, from Class II, division 1 malocclusions with deep overbites to Class III therapy, management of crowding, adult treatment, and TMJ pain relief. He also covers two relatively new appliances, the Concorde facebow and the trombone appliance. The former is a modification of the decades-old Kloehn facebow with the addition of a labial hook that allows for the attachment of an elastic to the lower member of the twin block, with the aim of restricting maxillary growth while encouraging mandibular forward growth. The Concorde facebow is worn primarily at night, thus solving a minor shortcoming of the twin block--disclusion while the patient sleeps. The author adds discreetly, "Patient comfort and acceptance is similar to a conventional facebow."
The trombone appliance is a fixed arch-development appliance, the heart of which is a length of silicone tubing, activated by an inner tube that slides freely within an outer tube "with the facility to extend or contract the length of the appliance". This device serves mainly to flare the incisors when deemed desirable.
Overall, this text is extraordinary. The author's systematic approach to cephalometrics, patient examination, diagnosis, and treatment planning alone justifies the price of the book. The copious full-color illustrations are outstanding. In addition to providing a remarkable range of clinical applicability, the author also provides some down-to-earth philosophy with regard to the use of statistics, evidence-based decision making, and the future of orthodontics. I was especially enamored of his comparison of orthodontics to the game of chess. As seen through Dr. Clark's eyes, the analogy is highly appropriate.
RGK