Prevalence of malocclusion and orthodontic treatment need in 10-year-old New Zealand children
Finishing occlusion, degree of stability and the PAR index
An investigation of mandibular morphology in subjects with different vertical facial growth patterns
Electropalatographic and cephalometric assessment of myofunctional therapy in open-bite subjects
The duration of fixed orthodontic treatment: a comparison of two groups of patients treated using Edgewise brackets with 0.018" and 0.022" slots
Dental changes and space gained as a result of early treatment of pseudo-Class II malocclusion
Non-extraction treatment of a thirteen-year-old boy with a Class III skeletal discrepancy and severe crowding in both the upper and lower dentitions
The need for orthodontic treatment was determined in a random sample of 10-year-old Dunedin, New Zealand schoolchildren using the Dental Aesthetic Index (DAI); an index based on the social acceptability of dental appearance. When absent or unerupted teeth were disregarded, orthodontic treatment was considered to be "mandatory" for one third of the children. The remaining children were almost equally divided into the three other treatment-need groups: "highly desirable", "elective", and "not necessary". The majority of the children had crowding and spacing in at least one incisor segment, and a molar occlusion other than Angle Class I. In this predominately mixed-dentition sample, more children were considered to need orthodontic treatment than older children in studies using the DAI. This raises some questions about the suitability of the DAI as a tool to assess orthodontic treatment need in mixed-dentition samples.
Received for publication: December 1998
The occlusions of sixty-five patients, treated by one private specialist orthodontist with consistent philosophy and goals, were assessed according to the PAR Index. For each patient, pre-treatment, post-treatment and follow-up study models were assessed. Follow-up models were taken at least 6.5 years following the removal of all retention appliances. Mean-weighted PAR scores were calculated for the total sample and various sub-groups at each stage. Mean percentage changes in weighted PAR scores were also calculated. The relationships between the occlusal standards at the end of active treatment and at the end of the follow-up period, and specific diagnostic and treatment factors were then investigated to search for any factors that might be predictive of long-term post-treatment occlusal stability or instability.
Received for publication: January 1999
In the present study, mandibular morphology was investigated on lateral cephalometric head films and dental casts of 60 subjects (30 females and 30 males) who had different vertical facial growth patterns. The sample had a mean age of 13.5 years, with a range of 11 to 15.5 years. The subjects were divided into three groups with regard to vertical facial growth by using the SN/GoGn angle to define low-angle, normal, and high-angle groups. In addition, each group was divided into two subgroups according to sex. The effects of the SN/GoGn angle and gender on mandibular morphology were investigated by means of analysis of variances. Tan Go, IMPA, SL, and EL measurements were found to be related to SN/GoGn, and the measurements of Go-Gn, Symphysis depth, and Intermolar width to be related to sex.
Accepted: July 1999
Myofunctional therapy (MFT) is often prescribed to correct tongue-thrust swallowing, with the expectation that anterior open bite (AOB) will reduce spontaneously if a more posterior tongue posture is learned. However, MFT has not been subjected to systematic evaluation. Electropalatography (EPG), which is used in speech pathology to measure dynamic tongue function for diagnostic, therapeutic and research purposes, is a suitable technique for the evaluation of MFT.
Received for publication: November 1998
The duration of fixed appliance Edgewise orthodontic treatment times using brackets with 0.018" and 0.022" slots was measured to determine whether there were any clinically or statistically significant differences between the two appliances. Sixty-four consecutively treated, fully banded patients were selected from two different practice locations. All 64 patients were treated by one clinician. Thirty-two patients (Groups 1) were treated using the 0.018" slot bracket and 32 (Group 2) were treated using the 0.022" slot bracket. The patients in each group were treated to the same standard of care using the same technique. The mean duration of treatment for Group 1 was 20.2 months and for Group 2, 21.7 months. Although the mean difference (1.5 months) was not clinically significant, it was statistically significant at p<0.05.
Received for publication: March 1997
This study was designed to investigate the dental changes and the space gained following early treatment of pseudo-Class III malocclusion, using a simple fixed appliance. Twenty-one consecutively treated patients who had a pseudo-Class III malocclusion comprised the treated group. Fifteen untreated control subjects were used as matched controls for the three-year follow-up after completion of treatment. Lateral cephalograms and study models were analysed for the treated, the control and the follow-up group. The arithmetic mean and standard deviation were calculated for each variable, and paired t-tests were performed to assess the effects of treatment on the treated group. The Mann-Whitney test was performed to evaluate the difference between the follow-up group and the control group. Anterior crossbites and mandibular displacements were eliminated after the treatment. An average, the space gained as a result of the treatment was 4.7 mm in the upper arch (p<0.001° ). Comparison of the space available as a result of early treatment with the space required for alignment of posterior segments in the upper arch of the untreated control group indicated that there was enough space for the eruption of the canines and premolars as a result of early treatment; whereas, lack of space was evident in the untreated controls. In conclusion, a pseudo-Class III malocclusion, proclination of the upper incisors and/or retroclination of the lower incisors contributed to the correction of anterior crossbite and the elimination of mandibular displacement. Proclination of the upper incisors, utilisation of leeway space, and arch-width increase provided the space required for eruption of the premolars and canines.
Received for publication: June 1999
This case report was one of the winners of the Australasian Edgewise Study Group awards for 1997
A thirteen-year-old boy presented with a Class III skeletal tendency in association with severe crowding in both the upper and lower arches. Whilst there was not a frank posterior crossbite, it was felt that the upper arch was narrow and that the lower arch was similarly constricted. Taking this into account along with the fact that his upper lip was flat and the nasolabial angle obtuse, it was decided to pursue a non-extraction treatment, with the aim of providing by expansion an extra 16 mm in the lower arch to accommodate the full dentition, and with a view to extracting third molar teeth later. This proved to be successful, albeit over an extended period of time, with active treatment taking nearly three and a half years. A realistic alternative would have been to remove four bicuspid teeth and pursue an orthodontic/surgical approach to treatment. In retrospect, and with the benefit of reviewing his records without surgical intervention, the treatment plan decided upon has been well justified.
Received for publication: August 1999