ABSTRACT
OBJECTIVE: To test if placing a Southend clasp on the upper and lower incisors during Twin-block appliance treatment will control their angulation and enhance skeletal correction. DESIGN: Prospective, randomized, controlled clinical trial (ISRTCTN 45965219). SETTING: Orthodontic Department, Royal Preston District General Hospital, Preston, UK. PARTICIPANTS: Fifty-two consecutive patients aged 9-30 years undergoing treatment for Class II division 1 malocclusion (ANB>5°, OJ>6 mm). METHODS: Two alternative designs of Twin-block appliance were allocated randomly. One with a Southend clasp on the upper and lower central incisors and one without. The appliances were identical in all other aspects. OUTCOMES: Skeletal and dental changes measured on before and after treatment lateral cephalometric radiographs. RESULTS: There was a statistically significant change in ANB angle between the Southend group (-3·5°) and the Non-Southend group (-2·6°) (Pâ=â0·004). The change in upper incisor angulation was -6·1° for the Southend group and -12·0° for the Non-Southend group, which was statistically significant (Pâ=â0·005). The change in lower incisor angulation was 3·0° for the Southend group and 6·9° for the Non-Southend group, which was statistically significant (Pâ=â0·005). CONCLUSIONS: The presence of a Southend clasp on the upper and lower incisors during Twin-block treatment limited their tipping which enhanced the skeletal correction.
Subject(s)
Malocclusion, Angle Class II/therapy , Orthodontic Appliance Design , Orthodontic Appliances, Functional , Adolescent , Adult , Cephalometry , Child , Dental Stress Analysis , Female , Humans , Incisor , Prospective Studies , Statistics as Topic , Torsion, Mechanical , Young AdultABSTRACT
OBJECTIVE: The ratio of the cranium to the face has been traditionally reported in textbooks without any firm evidence base. The present study was undertaken to measure the increase in size with age of the cranium, face, upper and lower face components. METHOD: Bolton standard mean outlines for ages 1 to 18 years were analysed by the Autoceph computer program. We measured the area of each craniofacial component outline. RESULTS: The ratio of the size of the cranium to the face was less than previously reported at birth, 2 years, and 5 years of age, but more nearly correct in the adult. Growth of the cranium largely ceased by 9-years indicating precocious growth of the brain in relation to the face. The size of the face increased relative to the cranium by 69%. The lower face increased relative to the upper face by 22%. The average percentage increase in area was 78% lower face, 68.9% total face, 58.8% upper face, 26% cranium. The absolute growth rate of the face was greater than that of the cranium, and that of the lower face was greater than that of the upper face. The 95% confidence intervals for the growth rates did not overlap, indicating a statistically significant difference. The relative growth rate (cm2/cm2/yr) was 0.0444 lower face, 0.0391 total face, 0.0328 upper face, 0.0084 cranium. CONCLUSIONS: There was a differential gradient of change increasing from the cranium to the upper face to the lower face. This gradient was most clearly expressed by the relative growth rates and average percentage increases in area.
Subject(s)
Aging/physiology , Anthropometry/methods , Cephalometry/methods , Facial Bones/anatomy & histology , Facial Bones/growth & development , Skull/anatomy & histology , Skull/growth & development , Adolescent , Child , Child, Preschool , Computer Simulation , Female , Humans , Infant , Male , Models, Anatomic , Models, Biological , Organ Size/physiologyABSTRACT
A retrospective case note study was performed on 500 consecutive patients attending an orthodontic clinic. The total number of appointments and number of failed appointments was ascertained. The outcome of treatment was recorded as one of five categories: default before treatment, 46 (9.2%); still under treatment, 42 (8.4%); transferred elsewhere, 9 (1.8%); default during treatment, 88 (17.6%); or completed treatment, 315 (63.0%). Using a chi-square test, the 315 patients who completed treatment were compared with the 88 who defaulted during treatment. The total number of appointments was significantly fewer, but the number of failed appointments was significantly greater in the discontinued treatment groups. The standardized failure rate (total number of failed appointments / total number of appointments x 100) was used to compensate for the difference in the total number of appointments between the groups. The mean standardized failure rate was only 10.3% for the completed treatment group compared with 21.4% for the discontinued treatment group.
