Orthodontic facebows: safety issues and current management.

Some patients treated with extra-oral traction provided by simple elasticated materials and a standard facebow have experienced problems with the standard facebow coming out of the buccal tubes at night and the catapult effect of the extra-oral traction. The disengagement of the facebow at night has affected the success of treatment and occasionally injured the patient. This paper draws on material from a variety of papers and lists the known causes and considers the associated safety issues. It also provides some clinical tips and makes several suggestions for the continued use of this very useful form of additional orthodontic anchorage.

Changes in circumferential neck measurements during movements of the head in children and their relevance to extraoral traction.

One of the causes of facebow injuries to patients wearing extraoral traction has been the catapult effect of the simple elasticized materials used in the past. A variety of safety or self-releasing modular systems to counteract this catapult effect are currently available. However, the strap extension provided by these modules varies considerably. To reduce the catapult effect to a minimum, it is desirable to fit a system with the minimal travel that will accommodate any changes in distance between the facebow and the back of the head or neck. To ascertain the minimal travel required for the straps, circumferential neck measurements were carried out on 105 children aged between 9 and 14 years. The change in circumference was recorded for 3 different head positions. The mean distance change between the back of the neck and the end of the facebow was 25 mm per side, with a range of 4 mm to 50 mm. This study suggests that on average, modules with a 25-mm extension will be required for cervical traction.

Hazards of orthodontics appliances and the oropharynx.

Occasionally orthodontic appliances or parts of orthodontic appliances have caused problems with either the airway or the gastrointestinal tract. The type of appliances that have caused problems and their clinical management are discussed. A case is described in which an upper removable appliance with inadequate retention became lodged in a patient's pharynx lacerating the palatine tonsils. Suggestions are made to try and avoid the problems that were encountered in this case and others reported in the literature in patients undergoing orthodontic treatment.

The post-orthodontic prevalence of temporomandibular disorder and functional occlusion contacts in surgical and non-surgical cases.

This study aimed to assess mandibular mobility and the prevalence of functional occlusal contacts in subjects treated to a Class 1 incisor relationship by fixed orthodontic appliance therapy. Two hundred and thirty subjects participated (mean age=18 years) of whom 42 underwent orthognathic surgery. All subjects were in retention with a mean time of 7 months between debond and examination. Maximal mandibular opening, lateral and protrusive excursions were all significantly reduced in the surgical cases compared to the non-surgical group. Centric and eccentric non-ideal occlusal contacts were not different between surgical and non-surgical groups. Non-working side contacts occurred in 30% of subjects, posterior contacts on protrusion in 20% and RCP-ICP prematurities in 18% of subjects. Non-working side contacts were significantly more frequent in post-graduate cases compared to staff cases (P<0.05). An overbite less than the mean of 2.4 mm resulted in a reduced likelihood of canine guidance on the working side (P<0.001) and an increased frequency of non-working side contacts and posterior contacts on protrusion (P<0.001).

Functional occlusion after fixed appliance orthodontic treatment: a UK three-centre study.

This study aimed to assess the prevalence of functional occlusal contacts in cases treated to a Class I incisor relationship by upper and lower fixed appliance therapy. Helkimo's dysfunction indices were used by one examiner to assess mandibular mobility, clinical dysfunction and occlusal status. One-hundred-and-eighty-eight subjects participated in three UK orthodontic centres; Cardiff, Newport and Liverpool. The results show that RCP (CR)-ICP (CO) discrepancies occurred in 33 (18 per cent) cases, non-working side contacts were present in 31 per cent and posterior contacts on protrusion occurred in 44 (23 per cent) subjects. These interferences were significantly more frequent in cases treated by postgraduate students compared with those treated by staff clinicians (P < 0.05). An overbite greater than 2.4 mm resulted in a highly significant reduction in the occurrence of non-working side contacts and posterior protrusive contacts (P < 0.001). The prevalence of functional occlusal discrepancies in this UK sample of orthodontic cases is similar to that reported in the American literature.

A clinical study of space closure with nickel-titanium closed coil springs and an elastic module.

A previous study has shown that a 150-gram nickel-titanium closed coil spring (Sentalloy, GAC International Inc.) closed spaces more quickly and more consistently than an elastic module (Alastik, Unitec/3M). This study used the same friction sensitive sliding mechanics of pitting the six anterior teeth against the second bicuspid and first molars, to examine the rate of space closure of 100-gram and 200-gram nickel-titanium closed coil springs. The results for the three springs and elastic module were compared. The nickel-titanium closed coil springs produced a more consistent space closure than the elastic module. The 150- and 200-gram springs produced a faster rate of space closure than the elastic module or the 100-gram spring. No significant difference was noted between the rates of closure for the 150- and the 200-gram springs.

Use of nickel titanium closed-coil springs to align unerupted teeth: a case report.

We describe a case in which a patient with a class II division I incisor relationship on a skeletal II base was transferred midway through a treatment that consisted of aligning the upper and lower arches with fixed appliance orthodontics in preparation for a mandibular advancement osteotomy. The lower second molars had previously been extracted; the lower third molars were left unerupted and some distance from the lower first molars. To provide a good occlusion at the end of treatment, it was decided to expose and approximate the lower third molars to the distal aspect of the lower first molars with the use of nickel titanium closed-coil springs; this was to be done before the osteotomy.

Mandibular mobility and occlusal relationships after orthognathic surgery.

Mandibular mobility and the occurrence of occlusal interferences were assessed in a group of 42 subjects, all of whom underwent orthognathic surgery without maxillomandibular fixation. A minimum period of 3 months (mean of 12.9 months) had elapsed since surgery. Mandibular advancement (n = 8) and bimaxillary advancement procedures (n = 8) resulted in significantly greater end-of-treatment overjet than did Le Fort I (n = 12), mandibular setback (n = 3), or maxillary advancement with mandibular setback (n = 11). Mean maximum protrusion (5.9 mm) and mean maximum excursions to right and left (6.8 and 6.1 mm, respectively) were significantly higher after Le Fort I osteotomy. The frequency of right lateral, but not left lateral, non-working-side contacts was significantly greater in the mandibular setback group and the maxillary advancement with mandibular setback group. The mandibular setback group exhibited the only severe interference between retruded contact position and intercuspal position.

A review of orthodontic face-bow injuries and safety equipment.

Reports of soft tissue injuries from orthodontic face-bows have continued to appear in the dental and medical publications since the American Association of Orthodontists reported problems in 1975. In 1994 the results of a preliminary survey of face-bow injuries of the orthodontic societies and dental schools in Europe recorded nine serious injuries. The results of a recent face-bow injury survey of orthodontic practitioners in the United Kingdom and Eire recorded 33. The relative effectiveness of current extraoral traction safety products is discussed in relation to the cause of these continuing injuries.

A national survey of orthodontic facebow injuries in the UK and Eire.

There have been several reports of soft tissue injuries from orthodontic facebows in the dental and medical literature, but the magnitude of the problem in the UK and Eire has never been previously investigated. In order to obtain information, questionnaires were distributed to 1682 Dental practitioners providing orthodontic treatment in the UK and Eire. A total of 1117 (66 per cent) replied. Of these 859 (77 per cent) reported using Kloehn type facebows. Thirty-one practitioners (3.6 per cent) gave details of 33 injuries from Kloehn type facebows. The results of this questionnaire are compared and discussed with previous reports in the dental and medical literature. The relative effectiveness of extra-oral traction safety products is discussed.

The monitoring of orthodontic tooth movement over a 2-year period by analysis of gingival crevicular fluid.

Gingival crevicular fluid (GCF) was collected from around canine teeth before orthodontic treatment, during retraction, and in retention. The aim was to investigate the changes in the flow of GCF and its glycosaminoglycan (GAG) components at these three stages of orthodontic treatment, and relate them to tooth movement, gingival inflammation, and other clinical parameters recorded at the time of GCF sampling. GAG in GCF samples, collected for a 15-minute period into microcapillary tubes, were separated and identified electrophoretically, stained with Alcian blue and quantitated using a laser densitometer. The increase in GCF volume during orthodontic tooth movement and the decrease during retention are only partly due to changes in the severity of gingival inflammation. Levels of the GAG component chondroitin sulphate found in GCF samples taken during retention appear to be related to the duration of retention, particularly the length of time that the fixed appliance is passive before debonding. GCF analysis may assist the clinician to conduct this phase of orthodontic retention more reliably.

Orthodontic facebow injuries and safety equipment.

Facebows are widely used in orthodontic treatment to reinforce anchorage, and in selected cases can be very useful and effective. However, they are not without their problems. Reports of injuries with this appliance have continued to appear in the literature since 1975. This article reports the results of a preliminary survey of 23 European countries confirming 10 eye injuries and includes a review of the current literature. The safety headgears currently available are examined and their adequacy, in the light of this survey, is assessed.

Characterization of proteoglycan metabolites in human gingival crevicular fluid during orthodontic tooth movement.

Previous studies have identified glycosaminoglycans in gingival crevicular fluid (GCF) associated with a variety of clinical conditions, notably those involving bone resorptive activity. GCF was here collected from around teeth undergoing active orthodontic movement. Proteoglycan metabolites were purified from GCF by anion-exchange chromatography using fast performance liquid chromatography. Sulphated glycosaminoglycan was associated with the most highly anionic protein fractions IV, V and VI, and biochemical analysis was restricted to these fractions. Analysis included glycosaminoglycan content by cellulose acetate electrophoresis, molecular size by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting and amino acid analyses. Fraction IV contained hyaluronan (18.7%) and chondroitin sulphate (10.9%), fraction V heparan sulphate (29.5%) and chondroitin sulphate (19.6%) and fraction VI chondroitin sulphate only (21.3%). SDS-PAGE revealed two Coomassie blue bands in fraction V of 72 and 60 kDa and two further bands in fraction VI of 71 and 56 kDa. These proteoglycans appeared resistant to digestion by chondroitinase ABC or heparinase III, although the glycosaminoglycan chains underwent degradation after protein-core removal. The molecular mass and amino acid composition of the chondroitin sulphate proteoglycan fractions showed a close similarity to those of human alveolar bone proteoglycan. The presence of heparan sulphate proteoglycan in GCF in association with orthodontic movement is in accord with previous reports. The findings support the view that proteoglycans in GCF are 'biomarkers', notably those associated with active resorption of alveolar bone.

The effects of orthodontic tooth movement on the glycosaminoglycan components of gingival crevicular fluid.

In this study, gingival crevicular fluid (GCF) was collected from around a canine tooth, in children, before and during orthodontic tooth movement. The aim was to identify and quantify the glycosaminoglycan (GAG) components of GCF and relate them to tooth movement, gingival inflammation, plaque accumulation, pocket probing depth and GCF volume recorded at the site of sampling. GAG in GCF samples, collected for a 15-min period into microcapillary tubes, were separated electrophoretically, stained with Alcian blue and quantified using a laser densitometer. 2 GAG components of hyaluronic acid (HA) and chondroitin sulphate (CS) were identified. The increase in GCF volume during orthodontic tooth movement was only partly due to increased gingival inflammation. GAG levels varied with different types of orthodontic tooth movement. In GCF, levels of CS, in particular, may reflect the changes in the deeper periodontal tissues which could be monitored during orthodontic tooth movements.

A comparison of the rate of space closure using a nickel-titanium spring and an elastic module: a clinical study.

A study of the efficiency of space closure after premolar extraction was undertaken, comparing a nickel-titanium closed coil spring and an elastic retraction module by using sliding mechanics along an 0.019 x 0.025-inch stainless steel arch wire in 0.022 x 0.028-inch preadjusted stainless steel brackets. The rate of space closure in 17 subjects was analyzed from study models and was found to be significantly greater and more consistent with the nickel-titanium closed coil springs than with the elastic modules, in both arches. There were no clinically observable differences in the tooth positions between the respective techniques.