Volume 98 Number 3

Reviews and abstracts 281

selected, are clearly described and illustrated. To yield perspective on the state of the art in the mid-1960s and later in the mid-1970s, the author compares occlusal characteristics of dental casts displayed at meetings of the American Association of Orthodontists, the Tweed Foundation, and the Angle Society with those of the untreated optimal sample. Photographs of the 128 pairs of casts in the 1960s, and 186 pairs in the 1970s show that few posttreatment results meet the Six Key stan- dards. Photographs of all these cases are included in the text. After publication of the "Six Keys" article, an informal study of 210 American Board casts in the mid- 1980s revealed the adoption by many orthodontists of the new standards of an optimal occlusion. By 1988, about 30% of all American orthodontists were using the fully programmed straight wire appliance. Another 50% were using partly programmed edgewise appli- ances (loosely termed straight-wire appliances). Some of the differences achieved with nonprogrammed, partly programmed, and fully programmed (straight wire) ap- pliances are described. Included among the differences are the quantity of the slot-siting features, quality of the design features that correctly position the slots, the separate design concepts of the standard and translation brackets, the system for siting each bracket, and the effect of each when used with unbent arch wires.

Probably the most common misconception is that no single appliance can be designed to treat all mal- occlusions to an optimal occlusion. No one is more aware of such an improbability than the author, who clearly states that as no two individuals are identical, neither are any two malocclusions. Treatment plans, therefore, must be tailored for each person, except for the portion mesial or distal to movement. For this por- tion there are 12 treatment options for the maxillary arch and 11 for the mandibular arch, hence the prac- ticality of prearranging brackets into sets for prescrip- tion. According to the author, an individualized, cor- rectly sited, fully programmed appliance will provide optimal positioning of teeth with variations of no more than 0.5 mm and 2 ° from the averages found in the optimal sample in 90% of cases. The remaining 10% will require wire bending to the extent of the variations.

No claim is made as to the fully programmed ap- pliance being able to move teeth any faster than is biologically possible. In fact, except for the Six Key occlusion and optimal arch lines, the book provides no instruction on treatment procedures. According to the author, a second book is planned to address his treat- ment philosophy and its clinical application. The book is concisely written, the diagrams are beautifully exe- cuted, and the numerous black and white photographs of plaster casts of teeth are crisp. It would be to the

advantage of all clinicians using preangulated and pre- torqued brackets to have this particular text available for reference.

Alex Jacobson

Editor's note: The attthor informs me that the book is not a commercial and that he solely financed the writing of it. There is no affiliation with and no royalties received from any dental company. Orders for the book need to be placed directly with the Foundation, the sole source for the book in the United States. The proceeds will pay for the cost of the book, and if there is any excess, this will be used for research.

Thesis abstracts

A Study of Deep Overbite Correction With Lingual Orthodontics Randall K. Bennett Loma Linda, California: Loma Linda University, 1988

The purpose of the present study was to cephalo- metrically evaluate the biteplane effect associated with deep overbite correction in cases treated exclusively with the Ormco-Kurz lingual orthodontic appliance, and to evaluate whether differences existed between dolichofaeial and brachyfacial types. The measured variables involved in the biteplance effect were incisor intrusion and proclination, molar extrusion, and man- dibular rotation. Fifty-nine cases were evaluated by means of computer digitized tracings of pretreatment and postteatment lateral cephalograms. Mandibular in- cisor proclination 4.5 °, mandibular incisor intrusion of 2.3 mm, lower anterior facial height opening of 1.3 mm, and maxillary incisor intrusion of 1.2 mm all con- tributed to correction of the deep anterior overbite. No significant differences existed between dolichofacial and brachyfacial types for any of the variables mea- sured.

The Fracture Strength of Ceramic Brackets: A Comparative Study Daniel A. FIores Loma Linda, California: Loma Lh~a University, 1988

The purpose of this study was to compare the frac- ture strength of ceamic brackets under different surface conditions and different ligation methods.

A method was developed to accurately test the brackets in a reproducible manner. This test used a "hard" bracket holding fixture attached directly to an Instron machine and a torsional wire-bending force sim- ilar to the clinical torquing force placed on brackets.