Abstract

Objectives:

To determine the validity of five profile planes commonly used to describe the horizontal changes of the lower lip during orthodontic treatment.

Materials and Methods:

Pretreatment and posttreatment cephalograms of 79 patients (12.4 ± 2.8 years of age) were evaluated. Lower lip (labrale inferiorus) changes over time were measured relative to the Rickett's E-line, Steiner's S1-line, Burstone's B-line, Sushner's S2-line, and Holdaway's H-line. As an independent measure of actual horizontal lip changes, the labrale inferiorus was measured relative to a stable reference plane registered on the sella and oriented on the SN-7°.

Results:

The lower lip actually moved anteriorly 2.35 ± 3.35 mm during orthodontic treatment; the five profile planes indicated that the lower lip moved to a more retrusive, posterior position. The five profile planes also showed no statistically significant sex differences in terms of the treatment changes that occurred, while the actual lip changes showed that males exhibited significantly greater changes than females. Actual treatment changes showed that the lower lip moved to a more protrusive position with nonextraction than with extraction treatments, changes that were not evident based on the five profile lines. While lip changes based on the five profile planes demonstrated moderately high to high intercorrelations ranging from 0.81 to 0.97, they showed only weak correlations (r < .35) with the actual horizontal changes of the labrale inferiorus.

Conclusions:

While all five planes measured similar aspects of positional change, none of them closely reflected the actual lower lip changes that occurred. These planes should not be used to measure changes in lip position that occur during treatment.

Abstract

Objective:

To evaluate the skeletal and dentoalveolar components in adult subjects with skeletal open bite in the presence or absence of dental compensation.

Materials and Methods:

The study sample included 69 adult female subjects who belonged to three groups according to skeletal vertical relationships and overbite. A total of 15 variables (5 angular, 10 linear) were evaluated. Values in the dentally compensated open bite group (COBG), the dentally noncompensated open bite group (NCOBG), and the control group with normal vertical skeletal relationships and overbite (CG) were compared by means of parametric statistics.

Results:

The COBG and the NCOBG showed significantly greater incisor and molar heights in both jaws than the CG. No significant difference in upper or lower molar height was found between COBG and NCOBG. Incisor height was significantly greater in COBG than in NCOBG. Elongation in the incisor region was accompanied by significant narrowing of the lower anterior alveolar process in both skeletal open bite groups. Proclination of the upper incisors was significantly smaller in the COBG than in the other groups.

Conclusions:

Dentoalveolar components consisting of incisor elongation and inclination play a significant role in compensating for skeletal open bite configuration in adult subjects. Increased molar height is a common finding in adults with skeletal open bite.

Abstract

Objective:

To quantify the amount of tooth movement and orthodontically induced root resorption (OIRR) in ovariectomized rats.

Materials and Methods:

Five 10-week-old female Wistar rats undergoing ovariectomy (OVX) were investigated as the experimental group, and the other five without ovariectomy served as the control group. Four weeks after ovariectomy, 25-g nickel-titanium closed-coil springs were applied mesially to the maxillary left first molars. Micro–computed tomography was taken at day 0, 1, 3, 7, 14, 21, and 28. At day 28, the molars were extracted. The surface area of root resorption craters, depth, and volume were measured using electron and laser scanning microscopes.

Results:

Tooth movement gradually increased with time throughout 28 days. There was a significant difference in the amount of tooth movement between the control group and the OVX group. For OIRR, the OVX group showed wide and shallow root resorption craters scattered on the mesial root. The deep resorption craters were observed on the distal roots distributed in the cervical, middle, and apical thirds of the roots. Statistically significant differences were found between the control and the OVX groups in the depth and the volume of root resorption craters in the distal roots and the total volume of root resorption craters in all three roots.

Conclusion:

Ovariectomy affected not only tooth movement but also OIRR. Tooth movement in the OVX group was more rapid than the control group. Furthermore, the amount of OIRR in the OVX group was more severe than the control group.

This listing of academic opportunities is provided as a free service to the profession and the community.

ALABAMA

Rank: Orthodontic Residency Program Dir.

University of Alabama at Birmingham School of Dentistry

Dept. of Orthodontics, Birmingham, AL 35294-0007

Contact: Dr. Chung How Kau, (205) 934-1289

FAX: (205) 975-7590 e-mail: ckau@uab.edu

Rank: 2 Orthodontic Instructors

University of Alabama at Birmingham School of Dentistry

Dept. of Orthodontics, Birmingham, AL 35294-0007

Contact: Dr. Chung How Kau, (205) 934-1289

FAX: (205) 975-7590 e-mail: ckau@uab.edu

CONNECTICUT

Rank: Assistant Professor

University of Connecticut School of Dental Medicine

Dept. of Orthodontics, Farmington, CT 06030-1725

Contact: Dr.

Lip incompetence resolved by active vertical control in nonsurgical treatment of a protrusion case with vertical maxillary excess

Johnny JL Liaw,

Jae Hyun Park,

Fang Fang Tsai,

Betty MY Tsai, and

Wendy WT Liao