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96 Reviews and abstracts Am. J. Orthod. Dentofac. Orthop. July 1992 ing patients received conventional retainers. A control group of five persons was similarly followed. The num- ber and distribution of centric and nonworking occlusal contacts were recorded, as well as the relative forces of these contacts. Of the three measurement modalities tested, articulating ribbon proved to be the most reliable method for locating occlusal contacts. Five weeks after debanding, the positioner group had an increase in cert- trie contacts (p = 0.073) and a decrease in nonworking contacts (p = 0.024). The variance of the force of occlusal contacts was found to decrease significantly in the positioner group, while remaining unchanged in the retainer group. These previously unreported findings suggests a more even distribution of occlusal contact forces occurred with positioner therapy. Cartilage-degrading proteinases in human temporomandibular joint synovial fluid Marie B. Farrar The University of Tennessee, Memphis, Tenn., 1991. It has been suggested that temporomandibular (TM) disorders are progressive and end ultimately in osteoar- thritis. In arthritis, metalloproteinases are known to be responsible for destruction of cartilage extracellular ma- trix. This study biochemically characterized the TM synovial fluid of patients suffering from various TM disorders. Synovial fluid "washes" were collected from 8 joints of 7 patients undergoing arthrographic surgery and from 32 joints of 16 patients referred for bilateral arthrog- raphy. Gelatinolytic activity was evaluated using SDS- PAGE with gelatin substrate. Specimens consistently exhibited lytic activity at 70 kDa; this enzyme was characterized as metalloproteinase on the basis of in- hibition/activation studies and identified as 70 kDa ge- latinase. This enzymeis produced by synoviocytes and chondrocytes and degrades gelatin (i.e., denatured col- lagen) and collagen types IV, V, and XI. Transferrin, as a measure of plasma proteins, was semiquantified densitometrically after SDS-PAGE. Transferrin values, total cell counts, and protein con- centrations correlated highly with each other, as they measure similar cellular processes. These three vari- ables also correlated significantly with disease severity (as graded clinically and/or arthrographically) and with gelatinase activity (as semiquantified densitometri- cally). However, no relationship could be demonstrated between gelatinase activity and disease severity as rated in this study. These findings implicate metalloproteinases in the joint destruction accompanying TM disorders. They further suggest that TM dysfunction represents a pro- gressive disorder marked by slow cartilage destruction by metalloproteinases with secondary synovial inflam- mation occurring late in the disease. In addition, they indicate that the disease may be progressing biochem- ically well before macroscopic degeneration is seen. Cephalometric characteristics of normal bite depth, deep bite, open bite Erwin Lubit New York University College of Deptistry, 1991. The purpose of this study was to evaluate lateral cephalogram characteristics associated with varying amounts of vertical overbite. Understanding these char- acteristics is important in establishing a diagnosis, choosing among therapeutic modalities, and in under- standing the prognosis of treatment. Three groups of 20 patients were compared ce- pha!ometrically. One group had normal bite depth, the second had deep bite, and the third had open bite. For each cephalometric characteristic a mean value and a standard deviation were calculated for each group. Then an analysis of variance (ANOVA) was performed to analyze differences among the groups. The most sig- nificant difference among the groups was in the dental measurements. The incisors were significantly more proclined in the open bite group than in the normal or closed bite group. The effects of extraction and non-extraction treatments on the growth of the lower anterior face height A. Chua College of Dentistry, New York Universitk; New York, 1991. The effect of orthodontic treatment on the lower anterior face height (Ans-Me) is of fundamental im- portance to the orthodontist. However, the choice be- tween the two main methods of treatment, extraction versus nonextraction is not clear-cut. It is believed that the extraction method decreases Ans-Me, whereas the nonextraction method results in an increase in Ans-Me. This study examined the effects of both methods on Ans-Me for a sample of 174 subjects divided equally between Class I and II malocclusions. A difficulty of such a study is distinguishing be- tween the composite effects of growth and treatment- induced changes in growing subjects. Most studies con- trolled for growth by using subjects in the same age group. However, this study controlled for growth by normalizing Ans-Me measurements to the Michigan Growth Standard. With this method, we could compare subjects who differ in terms of the age at which treat-

The effects of extraction and non-extraction treatments on the growth of the lower anterior face height

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96 Reviews and abstracts Am. J. Orthod. Dentofac. Orthop. July 1992

ing patients received conventional retainers. A control group of five persons was similarly followed. The num- ber and distribution of centric and nonworking occlusal contacts were recorded, as well as the relative forces of these contacts. Of the three measurement modalities tested, articulating ribbon proved to be the most reliable method for locating occlusal contacts. Five weeks after debanding, the positioner group had an increase in cert- trie contacts (p = 0.073) and a decrease in nonworking contacts (p = 0.024). The variance of the force of occlusal contacts was found to decrease significantly in the positioner group, while remaining unchanged in the retainer group. These previously unreported findings suggests a more even distribution of occlusal contact forces occurred with positioner therapy.

Cartilage-degrading proteinases in human temporomandibular joint synovial fluid Marie B. Farrar The University of Tennessee, Memphis, Tenn., 1991.

It has been suggested that temporomandibular (TM) disorders are progressive and end ultimately in osteoar- thritis. In arthritis, metalloproteinases are known to be responsible for destruction of cartilage extracellular ma- trix. This study biochemically characterized the TM synovial fluid of patients suffering from various TM disorders.

Synovial flui d "washes" were collected from 8 joints of 7 patients undergoing arthrographic surgery and from 32 joints of 16 patients referred for bilateral arthrog- raphy. Gelatinolytic activity was evaluated using SDS- PAGE with gelatin substrate. Specimens consistently exhibited lytic activity at 70 kDa; this enzyme was characterized as metalloproteinase on the basis of in- hibition/activation studies and identified as 70 kDa ge- latinase. This enzymeis produced by synoviocytes and chondrocytes and degrades gelatin (i.e., denatured col- lagen) and collagen types IV, V, and XI.

Transferrin, as a measure of plasma proteins, was semiquantified densitometrically after SDS-PAGE. Transferrin values, total cell counts, and protein con- centrations correlated highly with each other, as they measure similar cellular processes. These three vari- ables also correlated significantly with disease severity (as graded clinically and/or arthrographically) and with gelatinase activity (as semiquantified densitometri- cally). However, no relationship could be demonstrated between gelatinase activity and disease severity as rated in this study.

These findings implicate metalloproteinases in the joint destruction accompanying TM disorders. They further suggest that TM dysfunction represents a pro-

gressive disorder marked by slow cartilage destruction by metalloproteinases with secondary synovial inflam- mation occurring late in the disease. In addition, they indicate that the disease may be progressing biochem- ically well before macroscopic degeneration is seen.

Cephalometric characteristics of normal bite depth, deep bite, open bite Erwin Lubit New York University College of Deptistry, 1991.

The purpose of this study was to evaluate lateral cephalogram characteristics associated with varying amounts of vertical overbite. Understanding these char- acteristics is important in establishing a diagnosis, choosing among therapeutic modalities, and in under- standing the prognosis of treatment.

Three groups of 20 patients were compared ce- pha!ometrically. One group had normal bite depth, the second had deep bite, and the third had open bite. For each cephalometric characteristic a mean value and a standard deviation were calculated for each group. Then an analysis of variance (ANOVA) was performed to analyze differences among the groups. The most sig- nificant difference among the groups was in the dental measurements. The incisors were significantly more proclined in the open bite group than in the normal or closed bite group.

The effects of extraction and non-extraction treatments on the growth of the lower anterior face height A. Chua College of Dentistry, New York Universitk; New York, 1991.

The effect of orthodontic treatment on the lower anterior face height (Ans-Me) is of fundamental im- portance to the orthodontist. However, the choice be- tween the two main methods of treatment, extraction versus nonextraction is not clear-cut. It is believed that the extraction method decreases Ans-Me, whereas the nonextraction method results in an increase in Ans-Me. This study examined the effects of both methods on Ans-Me for a sample of 174 subjects divided equally between Class I and II malocclusions.

A difficulty of such a study is distinguishing be- tween the composite effects o f growth and treatment- induced changes in growing subjects. Most studies con- trolled for growth by using subjects in the same age group. However, this study controlled for growth by normalizing Ans-Me measurements to the Michigan Growth Standard. With this method, we could compare subjects who differ in terms of the age at which treat-

Voh~me 102 Reviews and abstracts 97 Number I

ment was started, as well as subjects whose treatment were of different duration. Consequently, the pool of available subjects was enlarged compared to earlier studies. Our larger sample size would also make the results more reliable.

The results of this study showed that nonextraction treatment in Class I and II subjects caused a significant increase in the Ans-Me above and beyond the amount of normal growth. Extraction treatment did not result in any significant change in Ans~ Thus extraction treatment does not lead to a reduction in the anterior vertical dimension as is traditionally believed.

A survey of etiological factors in a sample population and their distribution according to sex, race, and molar classification D. J. Dowd, L. Jerrold, and E. Lubit New York University College of Dentistry Department of Orthodontics, New York, 1991.

From a review of the literature, it does not appear that anyone has attempted to quantify etiologic factors according to their prevalence in a sample population. The objective of this study was to examine a sample population and determine which etiologic factors were listed as the causes of malocclusion, how frequently each factor occurred, and how these factors related to sex, race, and molar classification.

In the study 124 case reports written by first and second year orthodontic residents at NYUCD were re- viewed for the etiologic factors that were considered as contributing to the malocclusion. The factors that were listed most frequently were in descending order: tooth size/arch length discrepancy, skeletal discrepancy, car- ies/premature loss of deciduous or permanent teeth, overretained deciduous teeth, habit (thumb sucking, lip sucking, tongue thrust), and mouthbreathing. Although no statistical analysis of the data could be accom- plished, some trends emerged from the study. 1. Overretained deciduous teeth and habits occurred inordinately more frequently in females than males. 2. Mouthbreathing occurred with greater frequency in the white population than in the Hispanic, black, or Asian populations. 3. Hispanics had an inordinately high percent of cases attributed to caries/premature loss of deciduous or permanent teeth. 4. Blacks had an in- ordinately high number of cases attributed to habit. 5. Asians had an inordinately low number of 2cases attributed to tooth size/arch length discrepancy, caries,

habit, or mouthbreathing and an inordinately high num- ber of cases attributed to skeletal discrepancy.

The effectiveness of cortical anchorage in patients treated with Class II elastics Gary Pulsipher Department of Orthodontics, Unirersity of Illinois, 1991.

The purpose of this study was to evaluate the ef- fectiveness of cortical anchorage when Class II elastics were used to treat Class II, Division 1 malocclusions. Thirty-five patients whose mandibular arches were pre- pared with cortical anchorage were compared with 30 patients with no special anchorage preparation. The age, sex, and duration of elastic wear were similar in the two groups. Cephalometric radiographs taken at the start and end of treatment were used to generate 29 variables. Differences between the groups occurred pri- marily in the dentoalveolar area, and included maxillary incisor vertical position and inclination, the cant of the occlusal plane, and inclination of the mandibular molar and incisor. The mandibular molar, which was most expected to reflect the effectiveness of cortical anchor- age, showed no difference in its vertical or mesial movement between the two groups.

Comparison of the straight-wire and standard edgewise appliances Paul Kattner Department of orthodontics, Ut, iversity of lllinois, 1991.

A retrospective comparison of treatment results was made using 60 completed cases treated with the straight- wire appliance (SWA) and 60 cases treated with the standard edgewise appliance (SEA). The Ideal Tooth Relationship Index (ITRI) scores showed no significant differences overall between the two groups before or after treatment. Examination of individual arch seg- ments showed that the posterior lingual relationships were better with SEA than with SWA. It was observed that the clinicians did a better job of correcting dis- crepancies that were highly visible. A Six Keys Anal- ysis, based on criteria established by Andrews (1972), found significantly better angulation of the posterior teeth with the SWA. Despite the improved angulation and inclination, the SWA did not produce a higher ITRI score following orthodontic treatment.