Stability of extraction space closure.

INTRODUCTION: The objectives of this study were to evaluate the prevalence and long-term behavior of extraction space reopening in patients with Class I malocclusion and to identify some associated factors. METHODS: A sample of 43 patients met the inclusion criteria. Dental casts at the onset of treatment, after treatment, and 1 and 5 years after debonding were used. Initial and final cephalometric radiographs were used to measure the amount of incisor retraction. Cochran tests were used to compare the numbers of open and closed extraction spaces after treatment and at 1 and 5 years after debonding (P <0.05). Initial incisor crowding, amounts of anterior retraction, and angulations between the canines and the second premolars were compared between patients with and without space reopening with t tests. RESULTS: Of the sample, 30.23% had extraction space reopening. The frequency of open spaces significantly increased between the final and the 1-year posttreatment dental casts and decreased between the casts at 1 and 5 years posttreatment. Patients with space reopening had less initial anterior crowding and greater amounts of mandibular incisor retraction during treatment. CONCLUSIONS: There was a high prevalence of space reopening 1 year after treatment. However, these spaces tended to decrease by 5 years after treatment.

The use of fixed appliances in the UK: a survey of specialist orthodontists.

OBJECTIVE: To investigate the use of fixed appliances in the UK. DESIGN: Prospective postal questionnaire. SETTING: UK. PARTICIPANTS: All members of the General Dental Council Specialist List in Orthodontics still in active practice and not in training posts. METHOD: A preemptive letter of explanation was sent inviting orthodontists to participate in the survey. The questionnaire was subsequently posted to 935 specialists. Data analysis investigated differences in clinical practice related to varying provider groups, level of operator experience and geographical region. RESULTS: The response rate achieved was 66.3%. A majority of orthodontists routinely used the 0.022 inch pre-adjusted edgewise system, standard size Siamese pattern stainless steel brackets, conventionally ligated and bonded using standard etch and light cured composite. Nickel titanium and stainless steel were the most popular archwire materials. Anchorage was supported routinely by palatal and lingual arches in up to 25% and by headgear in over a third of respondents. Newer innovations showed variable popularity. Self-etching primer was used routinely by one-third of respondents with 11% use of self-ligating brackets. Banding of first molars was preferred by over 60% of clinicians. Bone screw implants were used by only 0.2% of respondents. Clinicians with less than 10 years experience used more headgear, light curing, MBT prescription and molar bonding. Operators with over 20 years experience used more chemically cured bonding, Roth prescription, banded first molars, 0.018 inch slot size and Tip-Edge(TM), with less use of headgear. Fixed appliance use differed from that reported in the US with lower use in the UK of standard edgewise and Roth systems, aesthetic, miniaturised and 0.018 inch slot brackets and rapid maxillary expansion. CONCLUSION: Most UK orthodontic specialists routinely used the 0.022 inch pre-adjusted edgewise system with standard size Siamese steel brackets bonded using standard etch and light cured composite with conventional ligation. Variations were seen between different provider groups, types of treatment funding, levels of operator seniority and geographical regions. Differences were noted particularly in the use of bracket prescription and design, types of molar attachment and anchorage control.

[Tooth shape and color as criteria for or against orthodontic space closure in case of a missing lateral incisor].

AIM: The aim of this study was to examine the esthetic parameters that are applied, more or less unconsciously, in deciding for or against orthodontic space closure in the case of aplasia or traumatic loss of lateral incisors. MATERIALS AND METHOD: The width-height index for teeth 13 to 23 was measured on 200 dental students. The VITA Easyshade system was used to determine the components of the tooth color (L, C, h) and to identify differences between each tooth. Eight investigators subjectively assessed digital photographs of the subjects, opting for or against space closure. The Spearman correlation coefficients were calculated for the parameters measured. RESULTS: A comparison of the parameters showed that not one factor alone was responsible for the decision for or against space closure for esthetic reasons. Orthodontists were more likely to favor space closure when the canine was slightly wider and had a less pointed shape and the differences were very small between canine and central incisor in terms of hue, chroma, and lightness. CONCLUSION: We observed that the subjective decision on the esthetic aspects of space closure correlates closely with the objective criteria.

Force characteristics of nickel-titanium tension coil springs.

Nickel-titanium closed coil springs are commonly used for space closure. The springs possess a high resistance to permanent deformation and the potential for relatively constant force delivery. A study was designed to determine whether relatively constant forces can be delivered and whether the force magnitudes approach the manufacturer's targeted force values. Heavy, medium, and light springs were activated 15 mm at temperatures that ranged from 15 degrees C to 60 degrees C. The forces were measured during deactivation with a specially constructed force transducer temperature chamber. Relatively constant forces can be achieved with an over-activation procedure that allows relaxation to the desired activation. The light springs delivered forces that were near the targeted force; no difference was found between the heavy and medium springs in the constant force range. The force magnitudes varied markedly depending on mouth temperature.

Effect of ion implantation of TMA archwires on the rate of orthodontic sliding space closure.

A split-mouth randomized clinical trial was used to determine whether ion implantation of beta-titanium archwire would facilitate sliding space closure. After bilateral maxillary first premolar extractions, 0.19 x 0.025-inch beta-titanium arch wires, ion-implanted on one half only, were placed in 30 subjects aged 10 to 42 years wearing unimplanted 0.022 inch slot appliances. Nickel-titanium springs (150 g) were placed bilaterally to close the extraction spaces. Space closure was measured intraorally at monthly intervals until either the space on one side closed or 6 months had elapsed. The median rates of space closure were not significantly different between the ion-implanted and the unimplanted sides. The average rate of space closure on these beta-titanium wires, with or without ion implantation, was similar to the rate reported on stainless steel arch wires.

Indications for compensatory extractions in orthodontic space closure in the frontal segments.

This follow-up study presents patients who underwent orthodontic space closure in the maxilla after traumatic loss of frontal teeth or aplasia of a lateral incisor. Comparison covers findings obtained from casts and cephalograms in 24 patients with or without compensatory extraction. The findings indicate that acceptable results regarding axial tooth positioning and profile can be obtained without compensatory extraction. Prerequisites are distal occlusion of the first molars by one premolar width and continuous monitoring for regular overbite and uncrowded lower incisors. If orthodontic space closure can be achieved only by compensatory extraction, the indication for this space closure procedure calls for even more critical judgement.