292 Reviews and abstracts Am. J. Orthod. Dentofac. Orthop. September 1992

population-based normative samples for prediction; and (5) the state of computer hardware and software de- velopment. Although significant progress has been made independently in all of these areas, there are few examples where they have come together as a pastiche.

The purpose of this report is to present an algebraic derivation of Bookstein's geometric biorthogonal tensor analysis, which will run within any spreadsheet pro- gram. This is then applied to characterizing the nasal functional space of a normative sample population in terms of skeletal maturational attainment and velocity. Guidelines and exclusionary criteria for cephalographs that would be included in a population characterized by skeletal maturation are detailed.

Summary statistics are presented to verify the va- lidity of the method. It is hoped that this formula will help researchers and educators develop a dialectic re- garding morphometric analysis of the craniofacial com- plex which will eventually supplant current dogmatic systems of analysis. Heretofore, the application of this type of tensor analysis of craniofacial morphology has required a mainframe computer running customized software developed at a handful of research centers.

Correlation between maxillary skeletal asymmetry and the occlusal plane K. W. Deeney and M. R. Deeney Eastman Dental Center, Rochester, N.Y., 1991.

The purpose of this study was to determine if a correlation exists between a vertical right to left cant of the occlusal plane and specific skeletal maxillary landmarks.

A total of 30 patients were selected on the basis of having obvious right to left vertical maxillary skeletal discrepancy. Analysis of the frontal radiograph was done with a horizontal reference plane drawn at the junction of the greater and lesser wings of the sphenoid bone. Bilateral measurements from this plane to the buccal cusps of the maxillary first permanent molars established the degree of cant to the occlusal plane. The degree of skeletal midface asymmetry was measured from the sphenoid reference plane to right and left zy- gomatic archs, right and left "J" points, and right and left nasal floors. The vertical difference at key ridge points from the lateral radiograph were also measured. Oblique radiographs were measured in an attempt to determine how the mandible adapted to the cant of the occlusal plane.

Left to right differences in the occlusal .plane. strongly correlated (p = 0.05) with differences at the zygomatic point (r = 0.65), "J" point (r = 0.71), and

the floor of the nose (r = 0.75). There was a stronger correlation as the landmarks approached the occlusal plane. A correlation of r = 0.58 was found at the key ridges from the lateral radiograph. Interesting but not significant, in the majority of cases the mandibular ra- mus was greater in length on the side of greatest max- illary molar eruption. The mandibular body was shorter on the side of greater maxillary molar eruption.

Mandibular kinesiology as an adjunct in the diagnosis of TMJ internal derangement in asymptomatic volunteers D. M. Muench, R. H. Tallents, H. M. Proskin, and W. Murphy Eastman Dental Center, Rochester, N.Y., 1991.

Previous studies suggest a relationship between the shapes of masticatory mandibular motion recordings in the frontal plane and TMJ dysfunction. All of these studies compare pain subjects with "normal" subjects in which meniscal position is uncertain due to absent or random application of imaging technology. Investi- gators report that as many as 50% of asymptomatic subjects have abnormal meniscal position, therefore this study evaluated 50 asymptomatic volunteers, all of whom had MRI and arthrography, to determine if the graphic representation of jaw movement could separate subjects with normal TMJs from subjects with abnormal TMJs (i.e., unilateral/bilateral internal derangements [ID]) in an asymptomatic population. Each subject chewed deliberately on the left and fight sides. Fifteen to 20 chews per side were recorded with the BIO-EGN and stored on magnetic disk with specialized software (BIO-PAK). Maximum opening and closing velocity, maximum sagittal deviation, maximum vertical open- ing, maximum lateral deviation, side of initial opening deviation, and chewing cycle shape were subjected to statistical analysis. The chewing cycle shape was an- alyzed according to the method of Proschel (1987). Approximately 1500 individual chewing cycles were evaluated, resulting in approximately 13,500 observa- tions. The results of this investigation revealed that for all parameters evaluated no significant differences ex- isted between asymptomatic normals and asymptomatic abnormals. However, in some instances, left-right dif- ferences did exist, but only within subgroups. The mean maximum closing velocity during affected-side chew- ing in fight unilateral ID's was less than (p = 0.048) unaffected-side chewing. In subjects with bilateral ID, mean maximum vertical opening during left-sided chewing was greater than (p = 0.013) for fight-sided chewing. In normal TMJs (p < 0.001) and bilateral

Votume 102 Reviews and abstracts 293 Number 3

IDs (p = 0.002), mean maximum lateral deviation during right-sided chewing was greater than for left- sided chewing. Finally, in normal TMJs, a significantly greter mean percentage of chewing cycles (p = 0.05) showed initial opening deviations toward the contra- lateral side during left-sided chewing. In summary, this investigation does not support the concept that jaw tracking is a useful clinical tool to differentiate between subjects with normal and abnormal TMJs in an asymp- tomatic (pain free) population.

Demineralization susceptibility from interproximal reduction of enamel S. Cassata Eastman Dental Center, Rochester, N.Y., 1991.

This study was designed to determine whether in- terproximal reduction or "stripping" of human enamel renders teeth more susceptible to demineralization. Five subjects requiring extractions provided 15 carefully se- lected upper and lower premolars. These teeth were stripped mesially and distally to reduce approximately 0.25 mm of enamel per contact. Upper premolars were given a 1.25% APF 4-minute tray fluoride treatment immediately after stripping. Teeth on the right side were extracted the same day after stripping. Teeth on the left side were extracted approximately 2 months later. All crowns were sectioned buccolingually to produce a me- sial and distal segment. One of these was subjected to a lactate buffer solution, the other was not and served as a control. Sections were examined for deminerali- zation characteristics by using microhardness testing, polarized light, and scanning electron microscopy. Re- sults demonstrated no significant differences between groups in the nonlactate buffer control. In the lactate buffer group, the only statistically significant result was seen in groups extracted immediately after stripping. The nonfluoride group showed less demineralization than the fluoride groups. Overall, interproximal strip- ping did not appear to increase enamel susceptibility to demineralization.

Soft tissue growth and development of the nose and upper lip in complete unilateral cleft lip and palate W. Ziegler I I I Eastman Dental Center, Rochester, N.Y., 1991.

Growth and development of the nose and upper lip of children born with complete unilateral cleft lip and palate were studied by using nine linear and four angular measurements as observed on lateral cephalometric headfilms. The sample consisted of a total of 26 male and female children analyzed during the age ranges approximating 5, 10, and 15 years of age. None of these children had any syndrome associated with the clefting at the time of birth. All patients were treated by the surgeon, R. C. Millard, and orthodontist, S. Berkowitz. Headplates were collected on a mixed lon- gitudinal basis. The mean and standard deviations of the cleft sample were compared with Bolton (average) norms as a reference for each of the parameters mea- sured at the ages 5, 10, and 15 years. Most measure- ments used for this study were comparable to those used by R. S. Nanda et al., Angle Orthod 60(3):177- 89 (1990).

Results show normal lip thickness at the vermillion border; decreased soft tissue thickness overlying point A and similar lip heights. The nasolabial angle was decreased in the cleft sample. Lower nasal height and anterior nasal depth were decreased in the cleft samples. Upper nasal height and posterior nasal depth were greater in the cleft group as compared with the Bolton Standards. Inclination of the base (Cm-Sn) of the nose to the ptergomaxillary vertical reference plane was in- creased in the cleft sample, whereas the inclination of the dorsum (Prn-N') of the nose to the ptergomaxillary vertical reference plane was decreased. These findings may be explained by a possible downward and less forward position of the tip of the nose (Prn) relative to the averaged normals and slight retraction of the soft tissue in the area of the surgical repair.