Date of Award
Master of Dental Science (MDS)
Dental Science (Orthodontics)
Edward F. Harris, PhD
Quinton C. Robinson, DDS, MS Marjorie A. Woods, DDS
Tooth dimensions, Odontometrics, Incisors, Tooth crown, Sexual demorphism
“Early” or two-phase orthodontic treatment of Class II malocclusions is a highly debated topic in the orthodontic literature. We report here on a retrospective cephalometric study of patients with Class II, division 1 malocclusions. One group consisted of 32 consecutively treated patients who received “early” treatment with a Fränkel II appliance followed by treatment with full fixed appliance. These subjects were “matched” by sex and cephalometric value, to a subject treated with standard edgewise appliances in a single phase. Matching criteria focused on the bony facial characteristics, notably ANB, NAP, Y Axis, AOBO, FMA, overjet, and overbite. The question was whether the cephalometric results at the end of treatment were comparable. Two-phase subjects were treated on average 2 years longer than the one-phase edgewise group. Neither integumental variable (Z angle, E plane) differed statistically. Two of eight skeletal variables differed statistically, namely ANB and FMA. ANB was on average 1.3° smaller in the two-phase group, while the FMA was on average 1.8° steeper in the one-phase group. Four of the eleven dental variables differed statistically between the two groups. These variables were related to incisor position. Overall, the incisors in both treatment groups proclined during treatment. The two-phase subjects had a lower rate of premolar extraction (3% vs. 56%) than the one-phase subjects. Similar skeletodental endpoints were achieved regardless of treatment protocol; indicating the treatments can be viewed as equivalent approaches to a common problem.
Couch, William Max , "Root Morphology and Sexual Dimorphism : Size Standards for Crown and Root Dimensions in Adolescents" (2007). Theses and Dissertations (ETD). Paper 48. http://dx.doi.org/10.21007/etd.cghs.2007.0058.