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Biomedical subjects

S D Springate

Publications and source records attributed to S D Springate.

8 recordsLinked to original sources
PubMed1998

The validity of two methods of mandibular superimposition: a comparison with tantalum implants.

The aim of this investigation was to examine and compare the validity of Björk's and Ricketts' methods for the superimposition of serial cephalometric radiographs of the mandible for the analysis of changes over the duration of routine orthodontic treatment in growing subjects (approximately 2 years). Pre- and posttreatment lateral cephalometric radiographs of 23 children, with tantalum markers implanted in the mandible, were studied. The differences in position of six dental and skeletal landmarks between superimposition on Björk's structures and on Ricketts' corpus axis were compared with those on the basis of the implants. A rotational effect was found for corpus axis resulting from differential movement of Xi point with growth, whereas Björk's method yielded results essentially similar to those of the implant-based superimposition. This resulted in statistically significant median differences between the two methods for all landmarks except pogonion and menton. The magnitude of the differences increased with distance from the central core of the mandible and were generally greater horizontally than vertically. Although most differences were less than 2 mm, approximately 10% of the subjects showed differences greater than 4 mm for molar and incisor landmarks. These findings suggest that, for growing subjects, Björk's method should be preferred Ricketts', which cannot be relied on to indicate the true (intramandibular) changes during orthodontic treatment in growing subjects.

Analysis of Variance↗
PubMed1996

Specialist orthodontics in the General Dental Service.

This study investigated treatment times and treatment standards produced by 10 specialist orthodontic practitioners working in the General Dental Service (GDS) in England. Twenty cases from each practitioner, consecutively completed with two-arch fixed appliance therapy, were selected and assessed to evaluate treatment times and treatment standards. Observer-generated timings were recorded to provide values for the time taken by these practitioners to perform the various component activities associated with fixed appliance orthodontic therapy. These timings were then pooled to produce an 'average' value for each procedure. Treatment time was assessed retrospectively by applying these average times to the appropriate appointments, as documented on the patient's record card. The treatment duration, number of visits, appliance type and extraction regime were also recorded. Treatment standards were assessed by applying the weighted Peer Assessment Rating Index (PAR Index) to pre- and post-treatment study casts. Relationships between each of these variables were investigated using multiple regression analysis. No relationship was found between treatment time and PAR score change. Predictors of treatment time were the number of visits, and more interestingly, the use of extra-oral forces. However, no useful predictors of the treatment standard were found. On the basis of this sample, it appears that when specialist orthodontic practitioners in the GDS provide two-arch fixed appliance therapy: treatment is completed, on average, in 3-5 hours of chairside time, in 20 visits, spread over 22 months; they provide a high standard of treatment, as assessed by the PAR Index, to a caseload of patients in need to treatment.

Episode of Care↗
PubMed1995

Stability of the lower labial segment following orthodontic treatment--a comparison of treatment with Andresen and Begg appliances.

This retrospective cephalometric study of Class II division 1 malocclusions investigates the effects on the lower labial segment of two forms of orthodontic treatment. Non-extraction Andresen myofunctional therapy and first premolar extraction Begg treatment are compared to the lower incisor changes found in appropriate non-extraction and first premolar extraction control groups, which also presented with Class II division 1 malocclusions. Using four angular and two linear measurements, the lower labial segment was found to procline during Andresen therapy (1-2 degrees, 1-2 mm), and on withdrawal of the appliance it retroclined by about one-half of the in-treatment proclination (0.4-0.8 degrees, 0.1-0.5 mm). During extraction Begg mechanics, the lower incisors were found to retrocline (1.3-1.5 degrees, 0.4-0.9 mm), and they continued to retrocline following removal of the appliance (0.2-3.0 degrees, 0.8-1.1 mm). In general, the variables used to measure lower incisor position demonstrated only very small changes, and were near method error. The reliability of these changes are discussed. It is considered that the axial inclination of the lower incisor in relation to the mandibular plane is the most consistent and therefore still the most useful clinical measurement of lower incisor change available from cephalometric radiographs.

Activator Appliances↗
PubMed1992

Indelible bond location marks: an avoidable aesthetic hazard.

An increasingly popular method of aiding the precise placement of bonded brackets is to identify the long axis and centre of the crown with small pencil marks. A case is reported where marks placed with a soft pencil in the centre of the etched enamel have led to the inclusion of pigment deep in the enamel surface which has proved impossible to remove.

Adolescent↗
PubMed1991

An evaluation of zirconium oxide brackets: a preliminary laboratory and clinical report.

A pre-production sample of zirconium oxide (ceramic) brackets was examined in this study. A laboratory investigation of the tensile/peel bond strength of the brackets was carried out using two light-cured adhesives (Prismafil and Heliosit) and one chemically-cured adhesive (Delphic). The mode of failure was also investigated using optical and scanning electron microscopy. The bond strengths achieved with Prismafil were statistically significantly (P less than 0.05) lower than Heliosit and Delphic between which no significant differences were found. All samples failed at the bracket-adhesive interface. A clinical test demonstrated the extreme ease of sliding along stainless steel and nickel-titanium archwires, and revealed a low plaque adhesion. The principal disadvantage of these brackets appears to be their off-white highly opaque appearance which in addition to giving poor aesthetics may adversely affect bond strength with light-cured adhesives.

Adhesives↗
PubMed1991

Unerupted premolars--an alternative approach.

These two cases illustrate variations of an alternative technique for moving unerupted teeth into the mouth. Previously described techniques may damage the tooth or the periodontium and the regular adjustments required can be uncomfortable and are unpleasant for the patient and the operator. The method described provides a stress free alternative which is readily acceptable to patients. Adjustments are rarely needed, but if required they usually involve repositioning a magnet in the removable appliance, a procedure carried out simply by the operator or technician using cold cure acrylic.

Adolescent↗
PubMed1989

Magnets and orthodontics.

The first part of this paper is a literature review of magnets and their uses in orthodontics. The biological safety of magnets is considered and a report is given of experiments carried out on rat osteosarcoma cell line UMR-106. The second part of the paper describes a case where neodynium-iron-boron magnets were used to assist eruption of an unerupted, vertically impacted upper right canine. Previously, space was available for this tooth, but it failed to show signs of eruption. Following surgical attachment of a magnet, and the use of a second magnet attached to an upper removable appliance, rapid eruption occurred producing a favourable position for bonding.

Animals↗