DEPARTMENT OF REVIEWS AND ABSTRACTS

Edited by J. A. Salzmann, D.D.S. New Yo-rk City

A11 inquiries regarding information on reviews and abstracts should be dirsoted to the respective authors. Articles or books for review in this department 8Jwuld be addressed to Dr. J. A. Salzmmn, 65 Sutton Place South, New York, New York 100%

Abstracts of masters’ theses

Orthopedic Forces for the Treatment of Skeletal Open-Bite Class II, Division 1 Malocclusions

Frederick W&ht Fairleigh Diokirrpon University

Eight orthodontic patients with Class II, Division I skeletal open-bite maloc- clusion and a maxillary width deficiency showing a bilateral posterior cross-bite were studied. Their average age was 11.1 years, and seven out of the eight were girls. Seven of these patients underwent the following treatment, while one served as a control: Palatal expansion to correct the lateral deficiencies. An extraoral orthopedic force of 40 ounces was applied to the expansion appliance to establish a more favorable anteroposterior denture base relationship and to prevent further bite opening as the maxillary posterior teeth were moved buccally. No treatment was performed on the control patient, in order to give merit to the above form of treatment. Records (lateral and posteroanterior cephalograms, models, and photographs) were taken on these patients prior to treatment, following palatal expansion, and at 6 months to determine the effects of treatment.

The primary result showed that palatal expansion can be performed in skele- tal open-bite patients to achieve proper dental alignment. This was accomplished without increasing the original hyperdivergence of the malocclusion.

Point A movement forward as a result of palatal expansion was prevented in these cases. Point A did not move posteriorly during the 6 months of the investi- gation. The SN-palatal plane angle actually decreased, even though extraoral forces were directed in such a manner as to prevent this. There was no significant change in the amount of overjet or overbite. The positive effects of an orthopedic high-pull headcap in these cases showed that the molar was intruded and retracted a significant distance. As a result, there was no increase in the Go Bn-SN angle and a Class I molar relationship was established in all but one case. The nasal

692

Volume 72 Nwnber 6

Reviews and abstracts 693

width and nasal proportion increased significantly, as did the distance between both maxillary and mandibular molars and canines.

The benefits of this form of treatment appear to be a helpful adjunct in treating Class II, Division I skeletal open-bite malocclusions.

A Cephalometric Study of Skeletal Changes Resulting From Surgical Retraction of the Suprahyoid Muscles in the Growing Macaca Mulatta

Keyven N&y Fatileigh Diclcinwm Unizrersity

The purpose of this experimental investigation was to determine if altered muscular forces could direct bony changes, and whether or not these changes were stable ; to estimate the importance of the suprahyoid muscle group on growth direction of the mandible during an active growth period ; and to deter- mine whether surgical intervention is a viable means of increasing facial height.

A group of three growing female rhesus monkeys (Macclca mdatta) were studied. Two of them served as experimental animals and the third as a control. Suprahyoid muscle retraction was produced experimentally by the surgical shortening of the sternohyoid muscles in the experimental animals during an active growth period.

Conclusions:

1. The anterior facial height increased following surgical intervention in both experimental monkeys (skeletal vertical growth), whereas horizontal growth pattern was evident in the control animal.

2. A number of angular measurements of vertical dimension also increased following the surgical retraction of the suprahyoid muscle group.

3. An anterior dental open-bite was produced in both experimental monkeys, whereas the control subject exhibited a “normal” anterior dental relationship.

An Analytical Comparison of Unaltered oRd Remineralized Ena’mul After Acid Pretreatment and In Vivo Remlnerai~rutlon as Used in Direct Bonding Procedures

Jack 1. Green, Jr. Fairleigh Diclcinmn University

Ten clinic patients who required premolar extractions were selected. The premolars were faceted at approximately 2 mm. in diameter at the heighte of contour buccally and lingually, and the teeth were then exposed to a 4-minute, 50 per cent phosphoric acid etch of the buccal surfaces of the subject’s right side and the lingual surfaces of the subject’s left side. The nonetched surfsees (buecal of the left side and lingual of the right side) were maintained as controls. The teeth were allowed to remineralize in vivo for a 7-week period, after which they were extracted and maintained in a 10 per cent saline solution at approximately 40 c.